issue and challenges facing rechargeable thin film lithium batteries

Review

Issue and challenges facing rechargeable thin film lithium batteries

Arun Patil, Vaishali Patil, Dong Wook Shin, Ji-Won Choi,Dong-Soo Paik, Seok-Jin Yoon *

Thin Film Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea

Received 28 February 2007; received in revised form 23 August 2007; accepted 27 August 2007

Available online 1 September 2007

Abstract

New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meetthe challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties orcombinations of properties as electrodes and electrolytes in a range of energy devices. Technological improvements in rechargeablesolid-state batteries are being driven by an ever-increasing demand for portable electronic devices. Lithium batteries are the systemsof choice, offering high energy density, flexible, lightweight design and longer lifespan than comparable battery technologies. Wepresent a brief historical review of the development of lithium-based thin film rechargeable batteries highlight ongoing researchstrategies and discuss the challenges that remain regarding the discovery of nanomaterials as electrolytes and electrodes for lithiumbatteries also this article describes the possible evolution of lithium technology and evaluates the expected improvements, arisingfrom new materials to cell technology. New active materials under investigation and electrode process improvements may allow anultimate final energy density of more than 500 Wh/L and 200 Wh/kg, in the next 5–6 years, while maintaining sufficient powerdensities. A new rechargeable battery technology cannot be foreseen today that surpasses this. This report will provide keyperformance results for thin film batteries and highlight recent advances in their development.# 2007 Elsevier Ltd. All rights reserved.

Keywords: A. Electronic materials; A. Inorganic compounds; A. Thin films

Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1914

2. Historical developments in Li-battery research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1915

3. Design of thin film batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1917

4. Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1921

4.1. Materials for anode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1921

4.2. Main problems with anode materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1924

4.3. Materials for cathode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1924

4.3.1. Transition-metal dioxides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1925

4.3.2. Metal dichalcogenides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1928

4.3.3. LiFePO4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1928

4.3.4. LiMn2O4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1929

4.3.5. V2O5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1931

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Materials Research Bulletin 43 (2008) 1913–1942

* Corresponding author. Tel.: +82 2 958 5550; fax: +82 2 958 6720.E-mail address: [email protected] (S.-J. Yoon).

0025-5408/$ – see front matter # 2007 Elsevier Ltd. All rights reserved.doi:10.1016/j.materresbull.2007.08.031

mailto:[email protected]

http://dx.doi.org/10.1016/j.materresbull.2007.08.031

5. Solid electrolytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1932

6. The electrode–electrolyte interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1933

7. Present status and remaining challenges of thin film lithium batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1933

8. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1936

Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1937

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1937

1. Introduction

The beginning of research on lithium secondary batteries goes back to the 1960s and 1970s due to the first energycrises and the growing interest in power sources for mobile applications. However, no breakthrough has been madebefore the early 1990s though there were a lot of demands for high power and energy density battery systems. One ofthe great challenges in the 21st century is unquestionably energy storage. In response to the needs of modern societyand emerging ecological concerns, it is now essential that new, low-cost and environmentally friendly energyconversion and storage systems are found; hence the rapid development of research in this field. The performance ofthese devices depends intimately on the properties of their materials. Innovative materials chemistry lies at the heart ofthe advances that have already been made in energy conversion and storage by introducing the rechargeable lithiumbattery. Further breakthroughs in materials, not incremental changes, hold the key to new generations of energystorage and conversion devices. Nanomaterials in thin film form have attracted great interest in recent years because ofthe unusual mechanical, electrical and optical properties. One need only consider the staggering developments inmicroelectronics to appreciate the potential of materials with reduced dimensions. Nanomaterials in thin film form arebecoming increasingly important for electrochemical energy storage [1–5]. Rechargeable lithium cells are keycomponents of the portable, entertainment, computing and telecommunication equipment required by today’sinformation-rich, mobile society.

A thin film battery is composed of several electrochemical cells that are connected in series and/or in parallel toprovide the required voltage and capacity. Each cell consists of a cathode and an anode electrode separated by anelectrolyte, which enable ion transfer between the two electrodes. Once these electrodes are connected externally, thechemical reactions proceed in electrodes, thereby liberating electrons and enabling the current to be tapped by the user.Usually it is desirable that the amount of energy stored in a given mass or volume is as high as possible. To compare theenergy content of cells, the terms specific energy (expressed in Wh/kg) and energy density (in Wh/L) are used, whereasthe rate capability is expressed as specific power (in W/kg) and power density (in W/L). To reach the goal of a highspecific energy and energy density two fundamental requirements must be met by electrode materials: (i) high specificcharge (in Ah/kg) and charge density (in Ah/L), i.e., a high number of available charge carriers per mass and volumeunit of the material; (ii) high (cathode electrode) and low (anode electrode) standard redox potential of the respectiveelectrode redox reaction, leading to high cell voltage. Moreover, in rechargeable cells reactions at both anode andcathode electrodes have to be highly reversible to maintain the specific charge for hundreds of charge/discharge cycles.All which are linked directly to the chemistry of the system. Among the various existing technologies thin film lithiumbatteries are considered as the most competitive power source because of their high volumetric energy density andgravimetric energy density, superior power capability and design flexibility [6]. Fig. 1 shows the comparison of thevolumetric and gravimetric energy density with other batteries.

This explains why they receive most attention at both fundamental and applied levels. The chances of finding apractical new battery system with a significant higher energy density in the next 10 years are extremely small. There issimply no such concept being presently studied at research level, as was the case for many years for rechargeablelithium battery. Thin film lithium battery has however been in constant evolution since its beginning, and will continueto evolve.

Now, thin film lithium batteries are used as power sources in many kinds of high value electronics such as videocameras, portable computers and telephones and its application such as in zero-emission vehicles, medicalinstruments, aerospace industry and military is almost reality. Its market is very promising, but the competition isintense. As a result, electrode materials have been widely investigated and very rapid and significant improvementshave been made over the electrode materials such as short manufacture time, lower preparation temperature, lowercost, high capacity, good cycling behavior [7,8]. This is a sizeable challenge facing those involved in materials

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research into energy conversion and storage. It is important to appreciate the advantages of nanomaterials for energyconversion and storage, as well as how to control their synthesis and properties.

The idea of a rechargeable lithium cell based on Li+ insertion reactions has been studied and numerous lithiuminsertion electrodes have been proposed to date. Since metallic lithium combines with an anode having high negativeredox potential and low equivalent weight. This anode combined with a cathode electrode material, such as atransition-metal oxide or chalcogenide capable of reversible lithium reaction and rechargeable cell can be constructed.The basic electrochemistry involves only the transfer of Li+ cations between the two insertion electrodes, so that theelectrolyte volume is minimized to a very thin film. The cycle ability of Li+ ion transfer cells depends mainly on thedimensional stability of the host material during insertion and deinsertion of Li+. Mechanical stresses occur duringcharge/discharge cycles, causing cracks and finally, the alloy becomes crumbly.

A major door was opened with the discovery of an insertion of lithium ions into the amorphous carbon structure asan anode associated with LiCoO2, an already known cathode material studied with lithium metal and the batterysystem was born [7].

The purpose of this paper is to discuss the history, design of thin film battery, different anodes, cathodes,electrolytes, their actual facts, key problems of anode and cathode at nano-level and ways of improvement andextrapolate the possible evolution in the future. Here we review recent progress on this aspect.

2. Historical developments in Li-battery research

Before reviewing the present status of research and future challenges for thin film lithium battery technologies, wepresent a brief historical account of developments over the past 30 years, as personally perceived [9]. The motivationfor using a battery technology based on Li metal as an anode relied initially on the fact that Li is the mostelectropositive (�3.04 V versus standard hydrogen electrode) as well as the lightest (equivalent weight M = 6.94 g/mol, and specific gravity r = 0.53 g/cm3) metal. It is lightest alkali metal with very high thermal and electricalconductivity, and highest specific heat of any solid element, thus facilitating the design of storage systems with highenergy density. The advantage in using Li metal was first demonstrated in the 1970s with the assembly of primary (forexample, non rechargeable) Li cells [10]. Owing to their high capacity and variable discharge rate, they rapidly foundapplications as power sources for watches, calculators or for implantable medical devices. Over the same period,numerous inorganic compounds were shown to react with alkali metals in a reversible way. The discovery of suchmaterials, were later identified as intercalation compounds which was crucial in the development of high-energyrechargeable Li systems. Like most innovations, development of the technology resulted from several contributions.By 1972, the concept of electrochemical intercalation and its potential use were clearly defined [11] although theinformation was not widely disseminated, being reported only in conference proceedings. Before this time, solid-statechemists had been accumulating structural data on the inorganic layered chalcogenides [12] and merging between thetwo communities was immediate and fruitful.

A. Patil et al. / Materials Research Bulletin 43 (2008) 1913–1942 1915

Fig. 1. Comparison of the volumetric and gravimetric energy density with other batteries.

In 1972, Whittingham [13,14] embarked on a large project using TiS2 as the cathode electrode, Li metal as an anodeelectrode and lithium per chlorate in dioxolane as an electrolyte. TiS2 was the best intercalation compound available atthe time, having a very favorable layered-type structure. As the results were published in readily available literature,this work convinced a wider audience. But in spite of the impeccable operation of the positive electrode, the systemwas not viable. It soon encountered the shortcomings of a Li-metal/liquid electrolyte combination—uneven Li growthas the metal was replated during each subsequent discharge–recharge cycle, which led to explosion hazards.Substituting Li metal for an alloy with Al solved the dendrite problem [15] but, as discussed later, alloy electrodessurvived only a limited number of cycles owing to extreme changes in volume during operation. In the meantime,significant advances in intercalation materials had occurred with the realization that oxides, besides their early interestfor the heavier chalcogenides [16] were giving higher capacities and voltages. Moreover, the previously held beliefthat only low-dimensional materials could give sufficient ion diffusion disappeared as a framework structure (V6O13)proved to function perfectly [17]. Goodenough and his co-workers discovered LixMO2 as cathode material [18,19]. Tocircumvent the safety issues surrounding the use of Li metal, several alternative approaches were pursued in whicheither the electrolyte or the anode electrode was modified. The first approach involved substituting metallic Li forsecond insertion material. The concept was first demonstrated by Murphy et al. [20] and then by Lazzari et al. [21] andled, at the end of the 1980s and early 1990s, to the so-called Li-ion or rocking-chair technology. The principle ofrocking-chair batteries had been used previously in Ni-mesh batteries [22,23]. Because of the presence of Li in its ionicrather than metallic state, Li-ion cells solve the dendrite problem which is, inherently safer than Li-metal cells. Tocompensate for the increase in potential of an anode electrode, high-potential insertion compounds were needed forthe cathode electrode, and emphasis shifted from the layered-type transition-metal disulfide to layered or three-dimensional-type transition-metal oxides [18]. Metal oxides are more oxidizing than disulfide (because, they havehigher insertion potential) owing to the more pronounced ionic character of ‘M˘O’ bonds compared with ‘M˘S’ bonds.Nevertheless, it took almost 10 years to implement the Li-ion concept. Delays were attributed to the lack of suitablematerials for the anode electrode (either Li alloys or insertion compounds) and the failure of electrolytes to meetbesides safety measures the costs and performance requirements for a battery technology to succeed.

The practical thin film battery started in 1982, when solid-state thin film battery was announced from Hitachi Co.,Japan. It comprised a TiS2 cathode prepared by CVD, a Li3.6Si0.6P0.4O4 glass electrolyte by RF sputtering and metalliclithium as an anode deposited by a vacuum evaporation. Also, WO3V2O5 cathode prepared by sputtering in H2–Arplasma was combined with the above battery [24,25].

The second approach involved replacing the liquid electrolyte by a dry polymer electrolyte, leading to the so-calledLi solid polymer electrolyte (Li-SPE) batteries. But this technology was restricted to large systems (electric traction orbackup power) and not to portable devices, as it requires temperatures up to 80 8C [26]. Shortly after this, severalgroups tried to develop a Li hybrid polymer electrolyte (Li-HPE) battery [26], hoping to benefit from the advantages ofpolymer electrolyte technology without the hazards associated with the use of Li metal. ‘Hybrid’ meant that anelectrolyte included three components: a polymer matrix swollen with liquid solvent and a salt. Companies such asValence and Danionics were involved in developing these polymer batteries, but HPE systems never materialized atthe industrial scale because Li-metal dendrites were still a safety issue.

Creation of the C/LiCoO2 rocking-chair cell was commercialized by Sony Corporation in June 1991 [27]. This typeof Li-ion cell, having a potential exceeding 3.6 V (three times that of alkaline systems) and gravimetric energydensities as high as 120–150 Wh/kg (two to three times those of usual Ni–Cd batteries), was found the most high-performance portable electronic devices.

NTT Co. Group in Japan had developed thin film batteries by using Li3.4V0.6Si0.4O4 glass as electrolyte and LiCoO2

[28] and LiMn2O4 [29] for cathodes by using RF sputtering method. The battery size was about 1 cm2 and thethickness was 1–5 mm of cathode, 1mm of electrolyte and 4–8 mm of lithium anode. Thin film batteries were alsodeveloped by Ever-ready Battery Co. and Bellcore Co., USA in 1980 using sulfide glass of Li4P2S7 or Li3PO4–P2S5 forelectrolytes, TiS2 cathode and Li and LiI for anode [30,31]. Bellcore Co. also announced the lithium cell consisting ofLiMn2O4 cathode, a lithium borophosphate (LiBP) glass or lithium phosphorus oxynitride glass (LiPON) forelectrolyte and metallic lithium anode. The cell has 4.2 V OCV and operated at 3.5–4.3 V, 70 mA/cm2 for more than150 cycles. The group in Oak Ridge National Laboratory (ORNL) in USA has been energetically studying thin filmbatteries using lithium phosphonitroxide glass (LiPON). The LiPON was prepared by RF sputtering of Li3PO4 targetin nitrogen gas, which is rather stable in comparison with other lithium oxide or sulfide based glasses in spite ofmoderate ionic conductivity of 2.3 � 10�6 S/cm at room temperature and activation energy of 0.55 eV [32]. The


current potential curve indicates the stability range of LiPON was from 0 to 5.5 V with respect to Li electrode. Lithiummetal anode was prepared by vacuum evaporation, and LiPON electrolyte and cathodes of LiCoO2, LiMn2O4, etc.were by RF sputtering. They have reported some combinations of anodes and cathodes with LiPON electrolyte, whichexhibited very good performance in voltage range from 2 to 5 V, current density up to 10 mA/cm2 and cyclability morethan 10,000 [33]. It is noteworthy that Neudecker et al. reported a Li-free thin-film battery with an in situ plated Lianode on copper electrode [34]. This technique is useful to avoid the presence of low melting lithium (m.p. 178 8C)during solder reflow conditions. LiPON is now recognized as a standard solid electrolyte for thin film lithium batteriesand have been used by many groups especially private companies in USA. It is also used in Park et al. in Korea [35] andBaba and Kumagai in Iwate University Japan. Baba et al. reported thin film batteries using LiPON electrolyte, usingLixV2O5 as an anode and V2O5 or LiMn2O4 as cathode by means of RF magnetron sputtering [36]. These rocking-chairtype batteries without using lithium metal anode have strong merit in preparation and safety, although they need initialcharging processes before use. Their battery exhibited so-called ‘‘forming behavior’’ increasing the capacity withincreasing the cycle number up to 20 cycles when the capacity maximum of 10 mAh/cm2 [37]. This behavior isattributed to the gradual decreasing of interfacial resistance. Baba et al. also proposed high-voltage and high-currentbatteries by stacking two cells on the same substrate, which comprises of layers of current collectors. It works 3–6.5 Vin 2 mA/cm2 operation [38].

With the aim of combining the recent commercial success enjoyed by liquid Li-ion batteries with the manufacturingadvantages presented by the polymer technology. Bellcore researchers introduced polymeric electrolytes in a liquidLi-ion system. They developed the first reliable and practical rechargeable Li-ion HPE battery, called plastic Li-ion,which differs considerably from the usual coin-, cylindrical- or prismatic-type cell configurations. Such a thin-filmbattery technology, which offers shape, versatility, flexibility and lightness, has been developed commercially since1999, and has many potential advantages in the continuing trend towards electronic miniaturization. Finally, the ‘nextgeneration’ of bonded liquid-electrolyte Li-ion cells, derived from the plastic Li-ion concept, are entered the marketplace. Confusingly called Li-ion polymer batteries, these new cells use a gel-coated, microporous poly-olefin separatorbonded to the electrodes (also gel-laden), rather than the P(VDF-HFP)-based membrane (that is, a copolymer ofvinylidenedifluoride with hexafluoropropylene) used in the plastic Li-ion cells. Having retraced almost 30 years ofscientific venture leading to the development of the rechargeable Li-ion battery, we now describe design of thin filmbattery, some of the significant issues related to the anode, cathode, electrolyte and its key problems, future challengesand opportunities highlighting the various areas in need of technological advances.

3. Design of thin film batteries

In the last few years various rechargeable lithium systems have been developed but only few of them have beensuccessfully commercialized [39]. Nowadays, lithium ion transfer cells dominate development in this sector, and thecommercial interest in lithium ion transfer systems grows continuously. This is because the Li+ ion transfer battery is avery promising system for satisfying the demand for high specific energy and high power batteries for portableapplications, especially for cellular phones and portable computers. Comparison with other systems it is clear that thelithium ion transfer battery is a worthy candidate for energy storage in electric vehicles [40–42]. Lithium-ion batteriesare one of the great successes of modern materials electrochemistry [43]. The concept of the thin film battery is verysimple just to construct solid films of anode, solid electrolyte and cathode sequentially on a substrate. Fig. 2 shows theschematic cross-section of a thin film lithium battery structure [44]. In thin film battery both electrodes are capable ofreversible lithium insertion. Because of the difference in chemical potentials of lithium in the two electrodes, thetransfer of lithium ions from the anode through the electrolyte into the cathode (discharge) delivers energy, whereasthe reverse lithium transfer (charge) consumes energy. Fig. 3 shows the schematic illustration of the discharge andcharge processes of lithium rechargeable battery. When the battery is discharged, the lithium ions in the anode materialmigrate to the cathode material, and a discharging current flow while the battery is charged, the lithium ions in thecathode material migrate between the layers of material to form the anode, and a charging current flows. In order toconstruct a thin film battery, it is necessary to fabricate all the battery components, as an anode, a solid electrolyte, acathode and current leads into multi-layered thin films by suitable techniques. Usually, the lithium metal used foranode is prepared by vacuum thermal vapor deposition (VD). Solid electrolytes and cathode or sometimes anodematerials of oxides are prepared by various sputtering techniques as RF sputtering (RFS), RF magnetron sputtering(RFMS). In some cases chemical vapor deposition (CVD) and electrostatic spray deposition (ESD) are used. Recently,


pulsed laser deposition (PLD) and sol–gel is often used especially for cathode materials. Typical thin film batteriesreported so far are listed in Table 1. For practical cells, carbon based anode and metal oxide-based cathode have beenselected, as they can provide maximum specific energy, sufficient specific power, and long cycle life [45–53,43].

At present, four cathode materials are favored: LiCoO2 [54–58], LiNiO2 [59–62], LiMn2O4 [63–67], and V2O5

[68]. The electrodes are scarcely air sensitive. In the case of V2O5 a lithium metal laminate is attached to the carbonanode. After filling in the electrolyte, the metallic Li reacts with carbon and forms LixC6, which is then the lithiumsource in the cell. However, the use of moisture- and air-sensitive lithium metal complicates the cell assembly andthere is also a safety uncertainty since residual metallic lithium might remain in the cell even during cycling. Thus, thision transfer system has found only limited application in small coin cells [53,68].

By using polymer or gel electrolytes, some thick film battery of less than 0.3 mm has been already available [69].Fig. 4 shows the general structure of thin film lithium battery. The cell is usually less than 30 mm in total thickness andaimed to integrate with semiconductor devices. Beside the material properties, the electrodes and cell design are alsoimportant sources of improvement. In thin film lithium battery mass transport limitations generally worsen theutilization and rate capability of electro-active materials and, thus, the specific energy and power of batteries. This isespecially true for lithium insertion materials [39]. Insertion electrodes are preferably fabricated as thin films fromsmall particle size (�5–20 mm) electro-active materials [69,70]. There are activities to develop very thin, all-solid-state micro batteries using vapor-phase deposition techniques [71,72]. Thin composite porous layers (�60–90 mm) ofthe electro-active material (oxide or carbon) with a few percent of a polymer binder (to adjust the mechanicalproperties of the layer) are coated on both sides of a current collector. The current collector is usually a 20 mm thick Alfoil for the cathode and a copper foil of the same thickness for the anode. In addition, the metal oxides contain about10% of an inert material, ensuring electronic conductivity (e.g., graphite). The composite electrodes are separated bythin microporous separators. The thickness of the whole package is typically about 400 mm. The use of a polymerelectrolyte instead of a liquid one offers several advantages in cell assembly [73–76]. The polymer electrolytes are


Fig. 2. Schematic cross-section of a thin film lithium battery structure.

Fig. 3. Schematic illustration of the discharge and charge processes of a lithium rechargeable battery.

used both as a binder and as a separator. Batteries with enormous shape, flexibility can be designed where aconceivable leakage of the liquid electrolyte is avoided.

One or more charge/discharge cycle(s) are generally performed after the assembly of lithium ion transfer cells.During the first cycle(s) a solid electrolyte interface (SEI) film is formed on the carbon anode and, possibly, interface orfilm effects also occur on the cathode. The film formation irreversibly consumes charge. The practical specific energyof formed cells is therefore only 80–90% of that corresponding to the mass of the built-in electro-active materials. Ofcourse, a careful adjustment of the balance of anode to cathode material masses is required to reach maximumperformance [77,78]. In an average design, cell stack (electrodes + separator + electrolyte) occupy about 70–80% ofthe total volume for medium-sized cells and the weight is about 80–85%. The ratio between active components(cathode and anode materials) and non-active is varying dependent on the power required. A high-power design willnecessitate larger electrode surfaces, more separator, electrolyte, and current collector. Any improvement in the


Table 1Typical thin film batteries

Anode Electrolyte Cathode Voltage (V) Current (mA/cm2) Capacity Reference

Li Li3.6Si0.6P0.4O4 TiS2 2.5 16 45–150 mAh/cm2 [25]Li Li3.6Si0.6P0.4O4 TiS2 2.5 16–30 – [279]Li Li3.6Si0.6P0.4O4 WO3–V2O5 1.8–2.2 16 60–92 Ah/cm2 [24]Li LiBO2 In2Se3 1.2 0.1 – [277]Li Li2SO4–Li2O–B2O3 TiSxOy 2.6 1–60 40–15 mAh/cm2 [280]Li Li2S–SiS2–P2S5 V2O5–TeO2 2.8–3.1 0.5–2 – [278]LiV2O5 LiPON V2O5 3.5–3.6 10 6 mAh/cm2 [36]V2O5 LiPON LiMn2O4 3.5–1 >2 18 mAh/cm2 [37]Li/LiI LiI–Li2S–P2S5–P2O5 TiS2 1.8–2.8 300 70 mAh/cm3 [89]Li LiBP, LiPON LiMn2O4 3.5–4.5 70 100 mAh/g [262]Li Li6.1V0.61Si0.39O5.36 MoO2.89 2.8 20 60 mAh/cm2 [28]Li Li6.1V0.61Si0.39O5.36 LiMn2O4 3.5–5 10 33.3 mAh/cm2 [29]Li LiPON LiMn2O4 4.5–2.5 2–40 11–81 mAh/cm2 [281]Cu LiPON LiCoO2 4.2–3.5 1–5 130 mAh/cm2 [34]Li LiPON LiCoO2 4.2–2.0 50–400 35 mAh/cm2 [33]Li LiPON Lix(MnyNi1�y)2�xO2 4–3.5 1–10 100 mAh/g [282,283]Li LiPON LiMn2O4 4–5.3 10 10–30 mAh/cm2 [284]Li LiPON Li–V2O5 1.5–3 2–40 10–20 mAh/cm2 [72]SiSnON LiPON LiCoO2 2.7–4.2 �5000 340–450 mAh/g [285]Li LiPON LiMn2O4 4.3–3.7 �800 45 mAh/(cm2-mm) [35]SnO Li6.1V0.61Si0.39O5.36 LiCoO2 2.7–1.5 10–200 4–10 mAh/cm2 [89]

Fig. 4. General structure of thin film lithium battery.

electrode designs, allowing better electrode kinetics, may result in a reduction of non-active components, for constantpower. Fig. 5 represents the volume and weight distribution inside the cell stack for average cell design. As it can beseen, the cathode material weight is a major part of the total weight, while electrolyte occupies a very large part of thetotal volume. The clearest way for improvement is the electrolyte volume reduction, i.e., electrode porosity. Beneficialeffect of small particle size (high specific surface area) on the specific power, numerous investigations have proved thatan increased specific surface area of the electro-active particles negatively influences the safety characteristics, thecharge losses, and the cycling performance of ion transfer cells [79]. The cell construction model can visualize thepossible gains that can be obtained at the complete cell level. Fig. 6 shows the cell specific energy and energy densityvariation as a function of electrode porosities. In this case, the cathode and anode are supposed to have the sameporosity. The manufacture pressure for electrode preparation is also crucial [80].

Low manufacture pressures usually give higher electrode porosity but rather poor contacts between the particles. Athigh manufacture pressures the electrode porosity is low and hence the electrode is insufficiently wetted by theelectrolyte. Moreover, in low-porous electrodes variations in volume of the individual particles during lithiuminsertion and deinsertion induce mechanical stress between the particles, that is, in the entire composite electrode [81].For optimum performance the electrode porosity should be precisely adjusted, for example, by the use of pore-formingadditives [80]. Mathematical modeling techniques can be used for electrode and cell optimization [82–84].

As could be anticipated, the influence is much more sensitive on volumetric energy. So, any improvement of powercharacteristics of the electrodes, through new electrolyte compositions, binder, active material physical properties,


Fig. 5. Weight and volume distribution of cell stack components (average design).

Fig. 6. Cell specific energy and energy density variation as a function of electrode porosities.

electrodes process, etc. can be translated into power, or energy increases. From the average present situation, animprovement of up to 20% can be expected in the coming years.

During these 15 years, the advancement of semiconductor thin film technology allows us to use low power devicessuch as CMOS, FE-RAM and liquid crystal displays, etc. Now, it is possible to operate some small electric devices bythe thin film battery. Moreover, the recent developments of micro electric devices such as wearable computers, RF-ICtags, micro-machines, etc. strongly demand micro power sources with high energy density. Fortunately, now we havemuch more choices of the materials for battery components owing to the developments in solid-state ionic field, thuswe will prospect the usual practical use of the thin film batteries in near future [85–92].

Now, we are reaching the limits in performance using the current electrode and electrolyte materials. For newgenerations of rechargeable lithium batteries, not only for applications in consumer electronics but especially for cleanenergy storage and use in hybrid electric vehicles, further breakthroughs in materials are essential. We must advancethe science to advance the technology. When such a situation arises, it is important to open up new avenues. Oneavenue that is already opening up is that of nanomaterials for lithium batteries so, we have discussed; a short review ofthe historical efforts of developing various nanomaterials used for the cathode and anodes in thin film lithium batteryfollowed its future.

4. Electrodes

Recent studies of lithium ion batteries focus on improving electrochemical performance of electrode materials andlowering the cost. Considerable improved electrochemical performance of the electrode materials has been achieved.There are still problems needing further investigation including theoretical aspects, which stimulate the investigationfor better electrode materials. The nature of the active materials is of primary importance to the resulting cell energydensity. The main features of the active materials which determine cell energy are the number of electrons they canstore per unit volume or weight (volumetric capacity or specific capacity), and the electrochemical potential theyproduce.

There are several potential advantages and disadvantages associated with the development of nanomaterials ascathode and anode for lithium batteries. Advantages include (i) better accommodation of the strain of lithiuminsertion/removal, improving cycle life, (ii) new reactions not possible with bulk materials, (iii) higher electrode/electrolyte contact area leading to higher charge/discharge rates, (iv) short path lengths for electronic transport(permitting operation with low electronic conductivity or at higher power), and (v) short path lengths for Li+ transport.Disadvantages include (i) an increase in undesirable electrode/electrolyte reactions due to high surface area, leading toself-discharge, poor cycling and short life, (ii) inferior packing of particles leading to lower volumetric energydensities unless special compaction methods are developed, and (iii) potentially more complex synthesis. With theseadvantages and disadvantages in mind, efforts have been devoted to exploring the new nanomaterials for anodes andmore recently, for cathodes [93,94].

4.1. Materials for anode

Metals that store lithium are among the most appealing and competitive candidates for new types of anodes(negative electrodes) in lithium-ion batteries. A number of metals and semiconductors, for example aluminum, tin andsilicon, react with lithium to form alloys by electrochemical processes that are partially reversible and of low voltage,involve a large number of atoms per formula unit, and in particular provide a specific capacity much larger than thatoffered by conventional graphite [95–99]. For example, the lithium–silicon alloy has, in it’s fully lithiatedcomposition, Li4.4Si, a theoretical specific capacity of 4200 mAh/g compared with 3600 mAh/g for metallic lithium.

At present mostly carbons are used as the anode of commercial rechargeable lithium batteries: (i) because theyexhibit both higher specific charges and more negative redox potentials than most metal oxides, chalcogenides andpolymers; (ii) due to their dimensional stability, they show better cycling performance than Li alloys. Due toelectrochemical reduction (charge) of the carbon host, lithium ions from the electrolyte penetrate into the carbon andform a lithium/carbon intercalation compound, LixCn this reaction is reversible. The quality of sites capable of lithiumaccommodation strongly depends on the crystallinity, the microstructure, and the micro morphology of thecarbonaceous material [97–106]. Thus, the kind of carbon determines the current/potential characteristics of theelectrochemical intercalation reaction. Carbonaceous materials suitable for lithium intercalation are commercially


available in hundreds of types and qualities [98,107,108]. Graphitic carbons are carbonaceous materials with a layeredstructure but typically with a number of structural defects. Throughout the search for carbon alternatives, much efforthas been devoted to the use of Li alloys. SnO-based glasses, or composites such as Sn˘Fe˘C, Sn˘Mn˘C or Si˘C [109–

115], several authors have demonstrated that these electrodes show a considerable improvement in their cyclingresponse in lithium cells. The Si˘C nanocomposites have attracted considerable interest because they show capacity ashigh as 1000 mAh/g for more than 100 cycles [116].

The first commercial cell was introduced in the 1980s by Matsushita; this was based on low-melting alloy of Bi, Pb,Sn and Cd whose cycling performances were found to deteriorate with increased depth of discharge. In most caseseven the binary systems Li–M are very complex. Among the matrix metals, M, that form Li alloys electrochemically,for example, Al, Si, Sn, Pb, In, Bi, Sb, Ag, and some multinary alloys [117], aluminum alloys [118] have been studiedmost carefully. Lithium alloys LixM are of highly ionic character for this reason they are usually fairly brittle. Thus,mechanical stresses, related to the volume changes, induce a rapid decay in mechanical properties and, finally,pulverization of the electrode. The metallurgical structure and morphology of Li alloys (grain size, shape, texture, andorientation) strongly affect their dimensional stability [119]. Thick electrodes consisting of large alloy particles are notflexible enough and degrade mechanically during cycling. A limitation of the cycling depth to very thin reaction layers[120,121] improves the cycle ability. However, the specific charge with respect to the total electrode mass is low. Thisapproach has been applied to alloy electrodes in rechargeable coin cells [121,122]. In 1997 Fuji announced thecommercialization of a new Li-ion technology using an amorphous tin composite oxide as anode. This reactsreversibly with Li at about 0.5 V, and has a specific capacity twice that of graphite. Fuji film Celltech Co. Ltd.announced that [123] use of an amorphous tin-based composite oxide (abbreviated TCO or ATCO) for the anode. TheTCO combines both: (i) a promising cycle life, and (ii) a high specific charge (>600 Ah/kg) and charge density(>2200 Ah/L) [124]. However, only the Sn II compounds in the composite oxide are said to form theelectrochemically active centers for Li insertion. In order to explain the high specific charge a mechanism can besuggested in which the tin oxide reacts to form Li2O and metallic Sn [119,125]. This reaction is associated with largecharge losses due to the irreversible formation of Li2O. In a second step the Sn then alloys with lithium reversibly. Onthe other hand, according to Fuji film Celltech [124] no Li2O was found after lithium insertion. However, the idea thatthe high specific charge of the TCO is due to the alloying of metallic tin which led to a renaissance of Li-alloy anoderesearch and development [125,101].

Thin amorphous silicon films deposited on a specially roughened copper foil surface by a sputtering process wereshown to have close to 100% reversibility at capacities larger than 3000 mAh/g. Excellent capacity retention was alsonoted for silicon electrodes prepared with a nanopillar surface morphology because size confinement alters particledeformation and reduces fracturing. Perhaps the greatest disadvantage of primary nanoparticles is the possibility ofsignificant side-reactions with the electrolyte, is one of the most critical issues for thin film lithium batteries and poorcalendar life. Table 2 shows that both the specific charges and the charge densities of lithium insertion materials aretheoretically lower than that of metallic lithium. However, considering that the cycling efficiency of metallic lithium is�99%, one has to employ a large excess of lithium [49,126,50] to reach sufficient cycle life. The practical chargedensity of a secondary lithium electrode is therefore much lower than the theoretical one so that it is comparable withthe charge densities of alternative lithium-containing compounds. However, the potential of the electrode materialsalso has to be considered because a higher potential versus Li/Li+ of the anode means a lower cell voltage. For


Table 2Characteristics of the few anode materials for lithium battery

Alloy Specific capacity(Ah/g)

Volumetric capacity(Ah/cm3)

Volume at chargedstate (m3/Ah)

Volume dischargedstate (cm3/Ah)

Variation(%)

Li 3.861 2.06 0.485 – –

Li2Sn5 0.790 2.023 0.494 0.138 259Li2Si5 2.012 2.374 0.421 0.102 312Li3Sb 0.564 1.788 0.559 0.227 147Li3As 0.840 2.041 0.490 0.163 201LiAl 0.790 1.383 0.723 0.373 94LiC6 0.339 0.760 1.316 1.195 10

instance, the potential of many Li alloys is �0.3–1.0 V versus Li/Li+ whereas it is only �0.1 V versus Li/Li+ forgraphite anode.

Early Li+ ion transfer systems used anode containing transition-metal oxides or chalcogenides with low redoxpotentials, for example, WO2 [127,118], TiS2 [128] or MoO2 [129]. These materials show rather low specific charges and,if combined with an oxidic cathode, rather low cell voltage. However, the low cell voltage (�1.5–2 V) makes these cellsfairly safe [129–131]. Low voltage oxides, for example, TiO2 [132] are still under development for special applications.Recent papers proposed novel oxidic anode such as LiMVO4 (M = Co, Cd, Ni, Zn) [133] or MnV2O6 [134] or lithium/metal nitrides [133–135] with high specific charge. However, the practical merit of these new materials cannot be judgedyet. The transition-metal vanadates M˘V˘O was first proposed by Fuji Co. [136] and later studied by several groups,Poizot et al. [137] reinvestigated the reactivity of Li-metal oxide as anode material for thin film battery. For instance, MO-type compounds (where M is Co, Ni, Fe, Cu or Mn), having a rock salt structure and containing metal elements (M) that donot alloy with Li, exhibited capacities two to three times those of carbon with 100% capacity retention for up to 100cycles. A nanostructured anode based on transition metal oxides has recently been described. The full electrochemicalreduction of oxides such as CoO, CuO, NiO, Co3O4 and MnO versus lithium, involving two or more electrons per 3d-metal, was shown to lead to composite materials consisting of nanometer-scale metallic clusters dispersed in anamorphous Li2O matrix [138]. Owing to the nanocomposite nature of these electrodes the reactions are termed‘conversion reactions’ which are highly reversible. The new results, in stark contrast, turn out not to be specific to oxidesbut can be extended to sulfides, nitrides or fluorides [139]. These findings help to explain the previously reported unusualreactivity of complex oxides including RVO4 (R = In, Fe) or AxMoO3 towards lithium [140,141]. Such conversionreactions offer numerous opportunities to ‘tune’ the voltage and capacity of the cell [138] owing to the fact that the cellpotential is directly linked to the strength of the M˘X bonding. Weaker M˘X bonding gives larger potentials. The capacityis directly linked to the metal oxidation state, with the highest capacity associated with the highest oxidation states. Thus,by selecting the nature of M and its oxidation state, as well as the nature of the anion, one can obtain reactions with aspecific potential. Based on low-cost elements such as Mn or Fe, fluorides generally yield higher potentials than oxides,sulfides and nitrides. Great progress has already been achieved with oxides, especially metallic RuO2, which display a100% reversible conversion process involving 4e�, and some early but encouraging results have been reported withfluorides [142–144] but a great deal remains to be done in this area. A further hint that working at the nanoscale mayradically change chemical/electrochemical reaction paths of inorganic materials comes from recent studies [145]. In thisrespect, many materials were previously rejected because they did not fulfill the criteria as classical intercalation hosts forlithium, are now worth for reconsideration. Carbon nanotubes have been explored as anodes [146,147], their cost ofsynthesis is viable remains an open question. Nanomaterials consisting of nanoparticles or nano-architectured materials,as described so far in this review, are not always easy to make because of difficulties in controlling the size and sizedistribution of the particles or clusters. The potential disadvantage of a high external surface area, leading to excessiveside reactions with the electrolyte and hence capacity losses or poor calendar life has already been mentioned where theparticles are significantly larger than the nanodomains. As well as reducing side reactions with the electrolyte, this canhave the advantage of ensuring higher volumetric energy densities.

In the middle of the 1990s, it was found that amorphous carbon prepared at low temperatures could be a promisinganode material for the second generation of lithium ion battery since its preparation temperature is lower and itscapacity higher than that for graphitic carbon [8,148] In addition, with some kinds of carbonaceous materials, it isfound that the content of hydrogen in the carbon structure does not change after several cycles [149]. However, thecontent of H can be as low as 0.039, and the reversible capacity can be up to 975 mAh/g [150]. Boron is the onlynonmetallic element in Group IIIA which can be incorporated into carbon materials [151,152]. The enhancement ofthe reversible lithium capacity after introduction of boron atoms seems to be due to the electron deficiency of boron[152]. Nitrogen can also be incorporated into carbonaceous materials [153]. The mechanical mixing of silicon andgraphite produced a composite of C0.8Si0.2 whose reversible capacity can be up to 1039 mAh/g and after 20 cycles canbe still 794 mAh/g [154]. A composite of silicon and carbon can also yield considerably increased reversible capacity[155]. The main reason seems to be that the introduced silicon can promote the diffusion of lithium in the interior ofcarbonaceous materials and effectively prevent the production of dendrites. The effects of phosphor on carbonaceousmaterials depend on the precursors [156,157]. The effect of the incorporation of sulfur on the electrochemicalperformance of the obtained carbons depend on the sulfur states [158]. Metals introduced into carbonaceous materialsinclude main group and transition group elements. Main group elements studied so far include potassium(Group IA),magnesium(IIA), aluminum and gallium(IIIA); transition metals include vanadium, iron, cobalt, nickel and copper.


The introduction of potassium and magnesium was found accidentally [159,160]. However, details of its effect are notyet understood. The introduction of aluminum and gallium can increase the reversible capacity of carbon anodesmainly because they can form solid solutions in planar structures with graphene molecules [161,162]. Aluminum maybe deposited on the surface of graphite [163]. Transition elements such as vanadium [164,165], nickel and cobalt areadded. Metallic nickel can be deposited on the surface of graphite [166].

A new approach to alleviate the problems of alloy expansion, involves the selection of intermetallic alloys such asCu6Sn5, InSb and Cu2Sb that show a strong structural relationship to their lithiated products, Li2CuSn and Li3Sb forthe Sn and Sb compounds, respectively. InSb and Cu2Sb thin film electrodes are particularly attractive candidatesbecause they operate through a reversible process of lithium insertion and metal extrusion. InSb and Cu2Sb electrodesprovide reversible capacities between 250 and 300 mAh/g. Cu6Sn5 in which, lithium can reversibly intercalate and de-intercalate. This is a promising alloy anode for thin film lithium batteries [167]. The main reason is that addition oflithium results in ductile alloys with greatly reduced volume change [168,169]. Table 2 shows the characteristics of thefew anode material for thin film lithium battery.

Remaining issues relate to a problem of surface, with the chemical reactivity being enhanced as the particle sizebecomes smaller. These findings open new avenues of research aimed at capitalizing on the beneficial effect thatparticle-size confinement could have within the field of electrochemistry. These and related nanocluster systems underdevelopment hold much promise for future developments.

4.2. Main problems with anode materials

The lower safety, linked to the much higher reactivity of Li metal, especially when cycled, remains a very difficultissue, unlikely to be solved. As a conclusion, there is little chance that Li metal will come back and give practicalbatteries with improved energy density. Search for pure lithium substitution by different metallic alloys was soonexplored, with little success, to solve the problem of dendrites and low reversibility. The fact that these alloys sometimeshave much higher specific and volumetric capacity than LiC6 made them again attractive and induced a renewed interestand research in this field. Table 2 describes the main properties of such compounds. The volumetric capacity can even bein some cases higher than pure lithium however, the first problem to solve is the volume change between the charged anddischarged states. These big volume changes produce enormous constraints on the metal grains, and induce heavyfragmentation, very detrimental for cyclability. By comparison, the volume change of lithiated graphite LiC6 is only10%. This is actually a key point in the Li-ion concept, because the solid electrolyte interface (SEI) produced on theanode interface by reaction with electrolyte, is not destroyed during cycling. If that was the case, the small lithium loss,which would be consumed at each cycle to repair it, would result in rapid capacity drop and poor cycle life.

Recent developments concentrate on nanoparticles of amorphous alloys, which could solve the problem offragmentation. In some cases, an inert matrix (like oxides) around the particles would sustain the volume variation.However, the much lower density make the compounds less attractive on a volumetric basis, and the problem of SEIlayer stability on cycling remains, whatever the particle size. Some numbers illustrate that the lithium loss observedduring the first charge of a Li-ion battery to create the SEI on the graphite interface is generally of the order of 10% ofthe capacity. If during cycling, 5% of this layer is destroyed, 0.5% of the capacity will be lost at each cycle forrepairing, and 100 cycles will result in 50% capacity loss. In the same way, the use of nanomaterials increasesdrastically the interface area to be passivated by SEI increasing proportionally the amount of lithium lost at the firstcycle. These facts show the difficulty to succeed in this area and enlighten the exceptional properties of graphite in thisrole. Discovery of a new electrolyte, thermodynamically stable at this low voltage, would drastically modify the dataof the problem, but this is unlikely. A second factor influencing the complete cell energy density is the working voltageof the anode versus Li metal. In most of the cases, the working potential of these alternative anodes is significantlyhigher than Li; therefore the cell potential is consequently reduced, which reduces the energy density. This is also thecase of non-crystalline or amorphous carbons which can accommodate larger quantities of lithium than pure graphite.Their higher voltages, sometimes higher than 1 V makes them practically unsuitable.

4.3. Materials for cathode

Concept of the ‘thin film lithium battery’ its development has been very rapid due to its many advantages overtraditional rechargeable battery systems such as average high output voltage, light weight, high energy density,


excellent cycling life, low self-discharge and the absence of potentially environmental pollutants such as lead andcadmium. In order to satisfy all the demands cathodes, anodes and electrolytes are need to be tailored. The choice ofthe cathode depends on whether we are dealing with rechargeable Li-metal or Li-ion batteries. For rechargeable Libatteries, owing to the use of metallic Li as an anode, the cathode does not need to be lithiated before cell assembly. Incontrast, for Li-ion batteries, because the carbon anode is empty (no Li); the cathode one must act as a source of Li,thus requiring use of air-stable Li-based intercalation compounds to facilitate the cell assembly.

Nanomaterials for the cathode are much less developed than the nanomaterials of anode. There are many kinds ofcathode materials, lithium cobalt oxides (LiCoO2), lithium nickel oxides (LiNiO2), lithium manganese oxides such asLiMnO2 and LiMn2O4, Phospo-olivines (LiFePO4) [170,171], metal chalcogenides (TiS2) and vanadium oxides (V2O5),etc. The classical cathode materials such as LiCoO2, LiNiO2 or their solid solutions can lead to greater reaction with theelectrolyte, and ultimately more safety problems [172,173], especially at high temperatures. Rechargeable Li cellsmainly use Li-free V2O5 or its derivatives as the cathode. Table 3 shows characteristics of the cathode material for lithiumbattery. Numerous materials have been proposed for cathode of rechargeable thin film lithium batteries. The largestnumbers of cathode materials that are being discussed are inorganic transition-metal oxides or sulfides. Cathode materialsthat contain no lithium after their synthesis are in the charged state. They must be combined with anode that serves as alithium source in the first discharge cycle. These nonlithiated cathode electro-active materials usually electrochemicallyinsert lithium at potentials negative of 3 V versus Li/Li+. In the lithiated state they are usually not stable to air andmoisture. On the contrary, there are various lithium-containing materials that could serve as lithium source inelectrochemical cells. They must be charged (the lithium must be deinserted) in a first formation cycle. These lithium-containing materials are typically stable to air and moisture, and electrochemically deinsert lithium in the 4 V potentialregions.

4.3.1. Transition-metal dioxidesThe structure of the two-dimensional lithium transition metal oxides with the general formula LiMO2 with M = V,

Cr, Fe, Co and Ni adapt the a-NaFeO2-type structure, which can be regarded as a distorted rock salt superstructure[174–179]. In cubic close-packed oxygen array the lithium and transition-metal atoms are distributed in the octahedralinterstitial sites in such a way that MO2 layers are formed consisting of edge-sharing [MO6] octahedral. In betweenthese layers lithium resides in octahedral [LiO6] coordination, leading to alternating (1 1 1) planes of the cubic rock-salt structure. This (1 1 1) ordering induces a slight distortion of the lattice to hexagonal symmetry. Fig. 7 shows atypical two-dimensional crystal structure of LiMnO2.

Complete deinsertion of the lithium ions results in the layered CdCl2 structure type. The oxides arethermodynamically stable only in the intercalated state LiMO2. The reason for this is the high electro negativity ofoxygen, which leads to a higher ionic character of the metal-oxygen bonds in comparison to the covalent nature ofmetal-chalcogen bonds. The resulting negative charge of the transition metal-oxygen layers causes repulsiveinteractions between adjacent layers, which have to be compensated by positively charged ions between the adjacentoxygen layers [180]. Among the above-mentioned isostructural dioxides, particularly LiCoO2, LiNiO2, and the mixedoxides Li(Co, Ni)O2 have gained industrial importance as electrode materials.


Table 3Characteristics of the cathode material for lithium battery

Positive electrodematerial

MolecularWeight

Density Reversiblerange

Theoritical specificcharge (Ah/kg)

Theoritical chargedensity (Ah/L)

ChargedTiS2 112.01 3.27 1 239 782MoS2 160.06 5.06 0.8 134 678V2O5 181.88 3.36 1 147 495V6O13 513.64 3.91 3.6 188 734MnO2 86.94 5.03 0.5 154 775NbSe3 329.81 8.7 3 244 2121

DischargedLiCoO2 97.87 5.16 0.5 137 706LiNiO2 97.63 4.78 0.7 192 919LiMn2O4 180.82 4.28 1 148 634

4.3.1.1. LiCoO2. The use of LixCoO2 as cathode electro-active material was first reported by John Goodenough in1980; while at Oxford University [18] LiCoO2 could be used as a high potential electrode for lithium batteries. LiCoO2

is formed at high temperatures and has a layered structure. The most widespread positive material for Li-ion, lithiumcobaltite LiCoO2, produces a very high potential. It is superior in cycling behavior due to its high structural stabilityand can be cycled more than 500 times with 80–90% capacity retention. Thanks to the materials ability to release abouthalf (0.5) a lithium atom per mole, and oxidize half of the cobalt to the tetravalent stage, the resulting specific capacityis close to 140 Ah/kg and density capacity 690 Ah/L. Thin film LiCoO2 cathodes discharged between 4.2 and 3.0 Vgive the best power densities [151]. This is due to the high diffusivity of lithium in the layered LiCoO2 structure. Notethat with a 4-mm thick LiCoO2 cathode, batteries can provide 1 mWh/cm2 energy at a 1 mW/cm2 power discharge.

In recent studies, LiCoO2 batteries have been cycled to 4.4 V with good results. This high-voltage stability isattributed to the ability of submicron grains to accommodate the volume changes associated with further Li extraction.Cycling to 4.4 V gives a 26% increase in the specific energy. In addition, a study of batteries with LiCoO2 cathodes of5 nm to 4 mm thick films indicates that the energy densities are ultimately limited by the rapidly decreasing Li-iondiffusivity as the lithium content approaches compositions of Li>0.96CoO2 at cell voltages <3.8 V versus Li. LiCoO2

thin film batteries have been cycled many thousands of times with only small capacity losses, typically �0.2 nAh/(cm2 cycle) at 25 8C. For LiCoO2 prepared at high temperatures (800–900 8C) the first-order transition involves anincrease in the c-lattice parameter of the hexagonal unit cell and an enlargement of the intersheet distance as well as asignificant decrease in the Co–Co distances [181]. The increase in the interlayer distance can be explained by theincreasing electrostatic repulsion of adjacent oxygen layers. The decrease in the Co–Co distances leads to a dispersionof the electronic energy bands assigned to the electron wave functions of the Co atoms [182,183]. This dispersionresults in an overlap of the valence and conduction bands and explains the observed change from semi conducting tometallic conductivity during this phase transition. Measurements of the lithium diffusion coefficient in LiCoO2 gavevalues ranging approximately from 10�11 to 10�12 m2/s at room temperature, based on different techniques andinterpretation approaches. These diffusion coefficients are slightly higher than those measured for TiS2 and giveevidence for good lithium ion mobility [182].

In addition, preparation of LiCoO2 is easy and it shows high capacity. As a result, it is the most common cathodematerial in the market. However, cobalt is the most expensive component as compared with nickel, manganese andvanadium. In order to lower its cost and enhance its reversible capacity, doping is also employed, such as the dopingwith fluorine, magnesium, aluminum, nickel, copper or tin [184,185]. LiF are added the reversible capacity is higherthan that of pure LiCoO2. When aluminum is used partly as a substitute for cobalt then the open-voltage and working


Fig. 7. Two-dimensional crystal structure of LiMnO2.

voltage will increases with aluminum content. Reversible capacity of LiAl0.15Co0.85O2 can be up to 160 mAh/g andthe volume structure does not change after 10 cycles [185].

Several different experiments have been used to quantify the self-discharge of our thin film batteries. The opencircuit cell voltage has been monitored over prolonged periods for Li batteries with LiCoO2 and LiMn2O4 cathodesranging from 500-Å thick to more useful cathodes of 1–2 mm thickness. These batteries were stored at various states ofcharge under an inert atmosphere near 25 8C. Comparison of the battery potentials with low current discharge curvessuggests a self-discharge rate of 1–3 mAh/(cm2 year). For a battery with a 2-mm thick cathode, this corresponds to<2% self-discharge per year. If the self-discharge is attributed to the electronic conduction through the Liponelectrolyte film, the resistivity of Lipon must be >1014 V cm. The fully charged batteries were stored at roomtemperature under open circuit conditions for different periods of time before being suddenly discharged in a highcurrent pulse. The decrease in capacity reflects not only the self-discharge, but also any deleterious aging effectsleading to an increase in cell resistance loss of capacity. It indicates the excellent shelf life and negligible self-discharge that can be expected from these thin film batteries.

The Li/LixCoO2 cells exhibit very high voltages with open circuit voltage (OCV) in the range from 3.9 to 4.7 V forstoichiometries of 0.07 < x < 1. Thus, a very high specific energy of 1070 Wh/kg is expected, based on an averagedischarge voltage of 3.9 V.

4.3.1.2. LiMnO2. Among the electrode materials with the composition LiMO2, the lithium manganese oxideLiMnO2 would be the most attractive for ecological and economical reasons. The material discharges in the 3 Vregions. Its structure could be described as a modified rock-salt type with a distorted cubic close packed oxygen anionarray. The lithium and manganese cations occupy the octahedral interstitial sites in such a way that alternating zigzaglayers of edge-sharing [LiO6] and [MnO6] octahedral are generated. Although the structure can be described aslayered, it differs from the layered structure of LiNiO2 and LiCoO2. It delivers a specific charge of 190 Ah/kg in thepotential interval between 2.0 and 4.25 V versus Li/Li+. Layered LiMnO2 may be cycled with > 99.9% capacityretention, despite undergoing the same cubic–tetragonal transformation.

Unfortunately, the oxygen arrays in the structure are unstable upon lithium extraction, which limits the use of thiscompound as a secondary electrode material. The capacity loss observed during successive lithium insertion/deinsertion. However, all the LiMnO2 materials suffer from a limited cycling stability. In the final stages of thedelithiation process, LiMnO2 transforms irreversibly into a spinel-type structure [186]. Thus, on cycling, theorthorhombic LiMnO2 component transforms gradually into a tetragonal lithiated spinel compound, which isresponsible for the poor cycle ability of the electrode [186,187]. LiMnO2 has been more fruitful by doping. Whenchromium is doped in LiMnO2 it forms Li1+xMn0.5Cr0.5O2 which exhibit a capacity of 190 mAh/g. It seems that withinthese materials, the role of Mn is to stabilize the layered structure of the chromium oxide. It is unfortunate that Crpresents major toxicity and pricing issues. The successful stabilization of the layered structural framework by anintercalating di, tri or tetravalent cationic substitute for Ni or Co (Al, Ga, Mg, or Ti) leads to LiNi1�xTix/2Mgx/2O2

phases, which were claimed to be safe and which displayed practical capacities of 180 mAh/g.

4.3.1.3. LiNiO2. The isostructural LiNiO2 is attracting intense attention not only because of its economic advantageover LiCoO2 but also because the redox potential of LiNiO2 is about 0.25 V more negative than that of LiCoO2 makingthe former less prone to electrolyte oxidation problems [188]. LiNiO2 has a layered structure like LiCoO2. Although itis cheaper than LiCoO2 and it has a higher specific capacity up to 200 Ah/kg during the first charge is higher than thatof LiCoO2.It is difficult to prepare on a large scale with an ideal layered structure. This material have some drawbackssuch as less stable in the overcharge state, which increases the potential hazards and it’s slightly lower voltage isdetrimental to the application of mobile phones. LiNiO2 decomposes easily into Li-deficient compounds at high heat-treatment, which act as impure phases and are unfavorable for lithium intercalation and de-intercalation. Lithium canmove in LixNiO2 in between the NiO2 layers via a vacancy diffusion mechanism. The chemical diffusion coefficientfor lithium can reach up to 2 � 10�11 m2/s for Li0.95NiO2. At this composition the lithium mobility is very high [189].Unfortunately, several problems arise during the synthesis of the layered LiNiO2 at temperatures above 600 8C whichare necessary to complete the oxidation from Ni2+ to Ni3+ in oxygen atmosphere and to obtain a sufficiently highdegree of crystallinity. Due to the volatility of Li2O at elevated temperatures, any known thermal treatment of LiNiO2

leads to a decrease in the lithium oxide content. The resulting lithium-deficient compositions have a partiallydisordered cationic distribution at the Li sites. This defect structure is considered to be responsible for the gradual


breakdown of the oxide structure during repeated lithium insertion/deinsertion cycles and leads to a diminishing of thespecific charge during cycling of the LiNiO2 electrode [190].

Several optimized preparation procedures have been suggested to achieve the stoichiometric composition LiNiO2

with the two-dimensional structure that is considered to have the best electrochemical performance [191–193]. Inorder to overcome these disadvantages for synthesis, doping is a promising method. There are many kinds of dopantelements such as Mg, Al, Ti, Mn, Fe, Co, Zn, Ga, Nb and F. The solid solution LiNi0.5Co0.5O2 is claimed to deinsertlithium in a homogeneous phase [194–197]. A redox potential is slightly more negative than LiCoO2 and LiNiO2 and aspecific charge of about 130 Ah/kg make this insertion compound as promising electro-active material.

In the case of substitution by magnesium, Ni2+ is mainly substituted at small added amounts of Mg2+ which resultsin good cycling behavior. With large added amounts magnesium may substitute Ni4+ result in a quite differentelectrochemical performance [198]. Aluminum can be uniformly doped into LiNiO2 [199]. LiAlxNi1�xO2 can be asingle-phase compound. LiAl0.25Ni0.75O2 can also be prepared [199]. Ti4+ can be doped into LiNiO2 to form layeredLiNi1�xTixO2 by solid-state reaction [200]. The reversible capacity can be as high as 240 mAh/g and cyclability isexcellent (over 100 cycles) in the range 2.8–4.3 V [200]. After doping with Fe3+ the potential for lithium de-intercalation increases resulting in more difficult oxidation of Ni3+. In addition, numerous Ni2+or Fe3+ ions occupylithium sites and thus electrochemical performance deteriorates [201]. Doping with cobalt can also be performed onthe basis of a sol–gel method. Its high rate capability is better than those of materials prepared via a solid phase method[202]. Addition of arsenium, calcium, indium or niobium shows only very limited improvements in cell performance[203]. The reversible capacity of LiNi0.75Ti0.125Mg0.125O2 and LiNi0.70Ti0.15Mg0.15O2 can be up to 190 mAh/g [204].Of course, dopants will result in better electrochemical performance. From this point of view doped LiNiO2 can be agood candidate as a cathode material for rechargeable lithium ion batteries.

4.3.2. Metal dichalcogenidesLayered type dichalcogenides of the transition metals Ti, Nb, Ta, Mo, and W, as well as dioxides of the transition

metals V, Cr, Fe, Co, and Ni are of interest as cathode materials [205]. The salient structural features of the transitionmetal dichalcogenides MX2 with a CdI2-type structure are blocks of two hexagonally close packed chalcogen layersbetween which the transition metals reside in either prismatic or octahedral coordination of six chalcogens. The Vander Waals gap between the X-M-X sheets provides the space for guest reactants in intercalation reactions. During theintercalation of lithium, a complete charge transfer occurs that involves the reduction of M4+ to M3+ and the diffusionof Li+ into the Van der Waals gaps [206] resulting in the expansion of the host structure along the crystallographic c-direction. The Van der Waals forces between the layers are thereby replaced by coulombic interactions. The octahedraland tetrahedral interstitial sites are available for the intercalation of lithium ions. Generally, the octahedral sites areenergetically more favored [207] leading to a maximum possible intercalation level of one lithium atom per formulaunit. Diffusion of lithium proceeds via the tetrahedral sites [208].

Among the transition-metal dichalcogenides TiS2 in particular satisfies the criteria for a proper rechargeableelectrode material. A high free energy for the lithium intercalation reaction, a single homogeneous phase ofintercalation with only 10% lattice expansion in the entire intercalation range of up to x = 1 in LixTiS2, a goodelectronic conductivity in both the non-intercalated and lithiated state, and a fast lithium diffusion with a diffusioncoefficient of about 10�12 m2/s at room temperature leading to high rate capability [209] are the characteristics of TiS2.An average discharge voltage of 2.1 Vand an almost 100% TiS2 utilization result in a specific energy of about 450 Wh/kg of a rechargeable cell with metallic lithium negative electrode. The rechargeability of TiS2 has been demonstratedin over 400 cycles with only 20% loss in the electrode utilization [209]. For comparison, crystalline MoS2 is stableonly at low discharge depths of about 10%. Intercalation of lithium into MoS2 is accompanied by a structural changefrom prismatic to octahedral molybdenum coordination [209]. Due to the low free energy of formation of the hostsulfide itself, a higher degree of lithium intercalation leads to the formation of Li2S and Mo metal. However, a betterelectrode behavior with a high degree of reversibility and a continuous discharge profile was observed for amorphousMoS2 [210].

4.3.3. LiFePO4

The pursuit of a clean environment and ubiquitous information networks has stimulated much effort in improvingrechargeable lithium thin film batteries, considered to be the most advanced energy storage systems. With theremarkable advances that have been made worldwide in lithium battery technology over the past decade, and the


tremendous impact that these batteries have had in powering electronic devices, such as laptop computers and cellulartelephones. The high cost, toxicity, safety hazards and chemical instability of the conventional LiCoO2, LiNiO2, andLiMn2O4 based cathode materials prohibits their use in biomedical applications. As part of an intensive search foralternative materials, lithium iron phosphate (LiFePO4) is a promising cathode material for lithium rechargeablebatteries. LiFePO4 has become of great interest as storage cathodes for rechargeable lithium batteries because of theirhigh energy density, low raw materials cost, environmental friendliness, high thermal stability at fully charged stateand safety than conventional materials. LiFePO4 olivine (well known as the natural mineral triphylite) is the simplest,most widely studied and potentially most useful. LiFePO4 has a high lithium intercalation voltage (�3.5 V relative tolithium metal), high theoretical capacity (170 mAh/g), ease of synthesis and stability when used with common organicelectrolyte systems [211]. Many efforts have been made to prepare this material since it was discovered that LiFePO4

could be used as a cathode material in lithium secondary batteries.Lithium iron phosphate, LiFePO4, was first reported as a cathode for rechargeable lithium-ion batteries in 1997 by

John Goodenough and co-workers at the University of Texas, Austin [212]. The LiFePO4, however, has not been usedas a commercial cathode material due to its low electrical conductivity (10�9 to 10�10 S/cm). This is because theLiFePO4 has an ordered olivine structure, in which Li, Fe, and P atoms occupy octahedral 4a, octahedral 4c andtetrahedral 4c sites, respectively, LiFePO4 electrodes are actually composed of two separate phases, LiFePO4 andFePO4, which are both poor electronic conductors because they each contain Fe cations with just one oxidation state(2+ or 3+, respectively). In practice one could not obtain the full capacity of the material because, as theelectrochemical reaction proceeds, ‘electronically’ isolated areas remain inactive in the bulk electrode. As a result, thismaterial was largely ignored. Therefore, in order to obtain acceptable energy and power from the lithium cells, it isnecessary to use small LiFePO4 particles, coated or in intimate contact with electronically conductive carbon [213].This simultaneously reduces the distance for Li+ transport, and increases the electronic contact between the particles.Procedures of this kind have led to a greatly improved electrochemical response and the full capacity of the material isnow accessible even under prolonged cycling. The search for new electro-active materials is now wider than everbecause such materials do not require a particularly high electronic conductivity, nor a high diffusion coefficient forlithium [214]. LiFePO4 can presently be used at 90% of its theoretical capacity (165 mAh/g) with decent ratecapabilities, and thus is a serious candidate for the next generation of thin film lithium batteries cells.

4.3.4. LiMn2O4

Manganese oxides are among the most popular cathode materials in primary lithium batteries due to their highabundance, low cost, favorable charge density, rather high electronic conductivity, better stability on overcharge andsuitable electrode potential. Three-dimensional framework structures of LiMn2O4 have cross-linked channelsallowing ion insertion as shown in Fig. 8. The size of the channels must be sufficiently large to accommodate the ions.The advantage of three-dimensional frameworks over two-dimensional layered structures like LiCoO2 and LiMnO2 is:(i) the possibility of avoiding, for steric reasons, the co-insertion of bulky species such as solvent molecules; (ii) thesmaller degree of expansion/contraction of the framework structure upon lithium insertion/deinsertion. (iii) LiMn2O4

has a spinel structure, different from LiCoO2 and LiNiO2 [215] which explain why it is more common in largebatteries. However, compared to the others it suffers from a smaller energy density and a lower chemical stability,inducing a shorter life especially at high temperature. In the case of Li–Mn–O cathodes such as LiMn2O4, the use ofsmall particles increases undesirable dissolution of Mn. Coating the particles with a stabilizing surface layer may helpto alleviate such problems but can reduce the rate of intercalation. By retaining large particles, there is less dissolutionthan with primary nanoparticulate materials, and high volumetric densities are retained. Conventional wisdom statedthat to sustain rapid and reversible electrode reactions in rechargeable lithium batteries, intercalation compounds mustbe used as the electrodes and that the intercalation process had to be single phase, that is, a continuous solid solution onintercalation. However, there are now many examples where lithium intercalation is facile despite undergoing phasetransitions. Transformation of cubic LiMn2O4 to tetragonal Li2Mn2O4, leads to a marked loss of capacity. However, itscapacity fades slowly, and this prevents its commercial use.

The spinel LiMn2O4, is possessing 10% less capacity than LiCoO2. Batteries with a thin crystalline LiMn2O4 spinelcathode when cycled between 4.5 and 3.0 V give energies comparable to that of LiCoO2 at low current discharge.Unfortunately the LiMn2O4 batteries have not proven to be as reproducible as the LiCoO2 batteries in terms of the cellresistivity and cycle stability. This is believed to be largely due to difficulties in optimizing and controlling thecomposition of the sputter deposited cathodes. Research is continuing to address these problems. The kind of battery


included an unannealed, nano-crystalline cathode film, nLixMn2�yO4. The performance of these batteries has beenreported [216–218]. The compositions of the as-deposited film are significantly Mn deficient, leading to a lithiumsubstituted spinel structure when crystallized. Although the 4.5–2.5 V capacity of this cathode is comparable to thewell-crystallized cathode, the Li+ diffusivity is greatly reduced in the disordered material, thereby limiting the powerthat can be realized with this thin-film cathode. The bright side, however, is that this cathode can be used to fabricatethin-film batteries on low temperature substrates or temperature sensitive devices.

Mixed results have been obtained for cells with LiMn2O4 cathodes. Several have achieved thousands of cycles with<1 nAh/(cm2 cycle) loss rates, while other batteries exhibit capacity fades of 30 nAh/cycle over at least part of thecycle life. These variations are only partially attributable to differences in the cathode film compositions.

A lot of elements have been introduced into LiMn2O4 to investigate doping effects [219]. LiFexMn2�xO4 spinelcan be used as 5 V cathode materials for lithium ion battery [220]. Cobalt exists in the spinel structure LiCoyMn2�xO4

[221]. The conductivity of LiCoyMn2�yO4 is much higher than that of LiMn2O4 because the diffusion coefficient ofLi+ increases. Furthermore, after doping with cobalt, the particle size becomes larger and the specific surface areadecreases, consequently, the contact area between active materials and electrolytes also becomes smaller, and thedecomposition rate of electrolytes and self-discharge rate decrease. The presence of cobalt inhibits the passivationprocess occurring on the cathode surface, increases the exchange current density and facilitates the charge-transferreaction of the active material [222]. All of these factors can favor the reversible intercalation and de-intercalation oflithium, and result in evident improvement in cycling behavior LiCo(1�x)/2Mn(3�x)/2O4 can be a cathode material for5 V lithium ion battery [223]. Nickel exists as divalent cation in LiMn2O4 [224]. The capacity of LiNi0.5Mn1.5O4

under cycling between 4.9 and 3.0 V can be stable above 100 mAh/g [225]. After the introduction of zinc into thespinel structure, there is no Jahn–Teller distortion since Zn2+ is in 3d10 configuration. Similar to the effects of dopingwith lithium and magnesium, the Jahn–Teller effect is blocked and cycling behavior improves. The reversiblecapacity of LiZn0.05Mn1.95O4 can stay at 102 mAh/g after 20 cycles [226]. Tailor the doping in such a way that itshould give

(1) Increase in Mn valence suppressing Jahn–Teller effect [227,228].(2) Improvement in stability of spinel frame of Li[Mn2]O4 lowering structural change during charge and discharge

process and inhibiting the solution reaction of Mn happening as equation of [224,222,221].(3) Increase in conductivity favoring reversible lithium intercalation and de-intercalation [222].(4) Decrease of surface area resulting in decrease in contacting area between active cathode materials with electrolyte

and decomposition rate of electrolyte and self-discharge rate [222].


Fig. 8. Three-dimensional framework structures of LiMn2O4.

Oxygen and sulfur can be used as dopants. LiMn2O3.98S0.02, can be prepared by a sol–gel method. Since sulfuratoms are bigger than oxygen, the structure stability can be kept during cycling and it can circumvent the Jahn–Tellerdistortion around 3 V [223]. LiAl0.24Mn1.76O3.98S0.02 will not show Jahn–Teller effects and reversible capacity can beup to 215 mAh/g [224,225]. However, all the reported doping methods have led to a decreased specific chargecompared to the undoped LiMn2O4 materials so far. It is expected that the current on going research will producematerials with improved energy.

4.3.4.1. Main problem of manganese oxides. The oxide MnO2 [Mn2] O4 represents the host spinel framework thatresults from the stoichiometric spinel phase LiMn2O4 by completely extracting lithium (chemically in an acid orelectrochemically) [229,230]. Besides LiNiO2 and LiCoO2 the lithiated spinel LiMn2O4 is at present a very popularlithium-containing cathode material [231,232]. Its cubic spinel structure, can be described as a cubic close-packedoxygen array with the oxygen anions on the crystallographic sites. The manganese cations occupy half of theoctahedral interstitial sites and the lithium cations one eighth of the tetrahedral sites. The interstitial space in the[Mn2]O4 framework represents a diamond type network of tetrahedral and surrounding octahedral sites. These emptytetrahedral and octahedral are interconnected with one another by common faces and edges to form diffusion pathwaysfor Li+ ion [19]. Chemical diffusion coefficients in the range 10�12 to 10�14 m2/s could be obtained, depending on thesynthesis conditions and measurement technique [233] of the three-dimensional crystal structure of LiMn2O4. Theelectrochemical Li+ deinsertion from the tetrahedral sites of LiMn2O4 is reversible and proceeds at about +4 V versusLi/Li+ [234]. The good rechargeability and cycling stability of LiMn2O4 is attributed to the fact that Li+ is deinsertedfrom the cubic structure with a minimal contraction of the unit cell over a wide composition range. However, atpractical potentials (�5 V versus Li/Li+) it is not possible to extract all the lithium electrochemically and form MnO2.It is also possible to insert additional Li+ in the empty octahedral 16c sites of LiMn2O4 but the cycling performance israther poor. The poor cycling behavior of Li/LiMn2O4 cells in the 3 V voltage range is attributed to an asymmetriclattice expansion/contraction of the LiMn2O4 electrode during discharge/charge reactions. This lattice distortion islargely a result of the Jahn–Teller effect of the Mn3+ ion. This effect transforms the cubic crystal symmetry of thespinel electrode into tetragonal symmetry [232,235]. Thus, charging and discharging in the 3 V potential rangetypically proceeds in a two-phase region consisting of the cubic and tetragonal spinel within a nominal compositionrange of 0.1 < z < 0.8 in Li1+zMn2O4 [236]. The electrochemical performance in the 3 V potential window can besignificantly improved by decreasing the amount of Mn3+ in the spinel compound. Mean oxidation states higher than3.5 can be found for manganese in defect spinel compounds with nominal compositions Li2OyMnO2 (2.5 � y � 4),which exhibit higher specific charges and better cycling stabilities in the 3 V region than materials with the ideal spinelcomposition [237]. The electrochemical performance in the 4 V potential regions of stoichiometric spinels LiMn2O4

strongly depends on the method of their preparation, especially the choice of the starting materials for the solid-statereactions and the heat treatment conditions. These parameters are especially important to achieve a high crystallinity,to avoid phase impurities, and to adjust the correct oxygen stoichiometry [238–240]. Replacing some manganese inLiMn2O4 with mono or multivalent cations (e.g., Li+, Mg2+ or Zn2+) or, alternatively, doping the oxide with additionaloxygen increases the average manganese-ion oxidation state slightly above 3.5, suppresses the Jahn–Teller effect ondeep discharge, and leads to an improved rechargeability of the oxide [241]. A particularly promising field is the so-called ‘‘5 V class materials’’, increasing significantly the cell working voltage with no or small sacrifice in capacity.One of the most cited is Li [Ni1/2Mn3/2]O4, with an average working voltage of about 4.7 V versus a lithiated graphitenegative electrode, while maintaining more than 120 Ah/kg. This is the best result published till now.

4.3.5. V2O5

Highly oxidized oxides of vanadium, chromium, niobium as well as molybdenum are well known for their ability toelectrochemically insert large amounts of lithium [210,205,226]. Vanadium is also cheap and easily derived fromexisting mineral deposits like Mn, and its oxides are attractive cathode materials due to accommodation of three stableoxidation states (V5+, V4+ and V3+) within its closely packed oxygen structure. So far, a wide range of vanadium oxideshas been investigated. V2O5 has a layered structure with a distorted close-packed oxygen array. Its theoretical capacityis the highest within the vanadium oxide family (442 mAh/g) However, due to a limited cycling stability, the vanadiumoxides V2O5 and V6O13 have gained importance as rechargeable 3 Velectrode materials. The oxide V2O5 forms layersof edge- and corner-sharing VO5 square pyramids [227]. The apical vanadium–oxygen bond distance is much shorterthan the four other distances and corresponds to a double bond. It is also possible to describe the structure of V2O5 as


distorted VO6 octahedral [228,242]. The very large length of the sixth vanadium–oxygen bond unique cathodeelectrode material for secondary lithium batteries for which a specific energy of up to 900 Wh/kg can be obtained. 100cycles with more than 450 Wh/kg have been demonstrated for a LixV2O5/Li cell in a voltage range between 3.4 and1.9 V [243]. Porous alumina nanopillars of V2O5 or LiMn2O4 have been grown on a metal substrate. Nanotubes of VOx

have also been prepared and investigated as cathodes. V2O5 aerogels were recently reported to have electro-activecapacities. Besides crystalline V2O5, promising results have been reported for V2O5 glasses with P2O5, V2O5 xerogels[244] and V2O5 aerogels [245]. These amorphous or low-crystalline materials offer considerable advantages by virtueof their morphology. A large electrochemically active surface area, small particle size and low density provide bothhigh overall diffusion coefficients and low volume expansion during lithium insertion. Specific energies of over700 Wh/kg were measured for lithium cells with a xerogel cathode electrode [246]. The layered structure of LiVO2 isdestabilized by lithium deinsertion. At x = 0.3 in LixVO2, approximately one third of the vanadium ions migrate fromthe vanadium layer to the lithium depleted layer. This process destroys the two-dimensional space for lithium diffusionand results in a defect rock-salt structure which offers only limited electrochemical activity [247]. However, limitedlong-term cycling stability is a major problem of such electrode materials at present.

5. Solid electrolytes

Solid-state lithium batteries have been studied as a fundamental solution of safety issue of conventional lithiumbatteries with solid electrolytes. These batteries have been also anticipated for thin film rechargeable lithiumbatteries, which will be used as on-chip power source [248–254]. Thin film solid electrolytes for the thin filmbatteries are required to have a higher ionic conductivity, a negligible electronic conductivity and be stable incontact with the anode and cathode electrodes. Progress in lithium batteries relies as much on improvements in theelectrolyte as it does on the electrodes. Solid polymer electrolytes is currently the most popular electrolyte forlithium ion batteries which represent the ultimate in terms of desirable properties for batteries because they canoffer an all-solid-state construction, simplicity of manufacture, good mechanical and electrochemical properties, awide variety of shapes and sizes and a higher energy density as the constituents of the cell are more tightly wound.No corrosive or explosives can leak out, and internal short-circuits are less likely, hence greater safety. In true solidelectrolytes only Li+ ions are mobile. Other much less mobile ions in a solid electrolyte are arranged in a crystallineor glassy matrix in which Li+ moves through vacant and/or interstitial sites. This type of Li+ transport occurs ininorganic solid electrolytes. At ambient temperature the ionic conductivity of solid electrolytes is poor. In true solidelectrolytes the contribution of the counter anion to the ionic conductivity is considerable. The most desirablepolymer electrolytes are those formed by solvent free membranes, for example poly(ethylene oxide), PEO, and alithium salt, LiX, like LiPF6 or LiCF3SO3.It is also called as high molecular weight dry polymers. In all cases, thebattery electrolyte film is an amorphous lithium phosphorous oxynitride [255–259,254,32]. This electrolyte iscommonly known as Lipon and now being used with good results by a number of research and development groups.The Lipon electrolyte has an acceptable lithium ionic conductivity (2 � 10�6 S/cm) and a good electrochemicalstability with both metallic lithium and the transition metal cathodes at cell potentials up to 5.5 V versus Li. Inaddition, the electronic resistivity of the Lipon films is >1014 V cm, which greatly minimizes the short circuit self-discharge of the battery.

Recent studies have shown that the crystalline complexes PEO:LiXF6 (X = P, As, Sb) demonstrate good ionicconductivity. Recently it has been shown that the conductivity of the crystalline polymer electrolytes may be raised bytwo orders of magnitude by partial replacement of the XF6 ions with other mono or divalent anions. Nanoscaleinorganic fillers such as Al2O3, TiO2 and SiO2 have been proved effective in enhancing the mechanical strength andconductivity of the polymer electrolyte [260,90]. However, there are still debates and even contradicted reports as towhy adding nanosized ceramic particles can improve the ionic conductivity of the polymer electrolytes [261,262].Nanoscale ceramic additives have two important common features: large specific surface areas and grains coveredwith various Lewis acidic or basic groups. The interactions between these surface groups and the ionic species of thesalt are responsible for the observed conductivity enhancement [261,262]. A solid electrolyte categorized in thio-LISICON family [263–265], Li3.25Ge0.25P0.75S4 exhibited a high ionic conductivity of 2.2 � 10�3 S/cm at 25 8C, highelectrochemical stability, and no reaction with lithium metal and no phase transition up to 500 8C. These features makethe thio-LISICON thin film especially promising for its use as a thin film solid electrolyte in the thin film rechargeablelithium batteries.


The advantages of polymer electrolytes are their high mechanical stability and flexibility, which allows: (i) simplefabrication of thin electrolyte films by casting or spin-coating, and (ii) various electrode and/or cell designs forexample, fabrication of composite electrodes containing both electro-active material and polymer electrolyte. Themajor drawback of polymer/salt complexes is their poor ambient-temperature conductivity.

6. The electrode–electrolyte interface

The Li-ion cell density can be improved through a selective use of appropriate existing or new materials for anodeand cathode electrodes. However, optimizing an electrode material is only the first step in the process leading to itsimplementation in a practical cell. Indeed, the capacity of a cell is nested in the structural or electronic behavior of itselectrode, poor cell lifetimes are rooted mainly in side reactions occurring at the electrode–electrolyte interface. Thus,mastering the chemical stability of any new electrode material with respect to its operating electrolyte medium whichrequires a control of the electrode–electrolyte interface through surface chemistry is as important as designing newmaterials. Tackling interfacial issues is both tedious and complex. We should remember that, despite many years ofresearch devoted to the mechanism by which the solid electrolyte interphase forms on Li or carbonaceous materials, itscomposition and nature are still the subject of much controversy. In contrast, the cathode interface has received littleattention over the years, despite its equally crucial role. Its importance is amplified with the Li technology, where highvoltages exceed the electrochemical resistance of the electrolyte oxidation and even favor its catalytically drivendecomposition. Thus, it is critical to control the electrode surface so as to modify its catalytic activity towardselectrolyte decomposition. The strategy developed to address this issue uses coatings that encapsulate, throughchemical or physical means, the electrode grains with an inorganic phase. This concept, successfully applied to thespinel LiMn2O4, is based on minimizing the surface area of the active material in direct contact with the electrolyte[266–269]. The coating must allow easy diffusion of Li-ions and, although insulating in nature, must be thin enough toallow the electrons to tunnel through. Equally relevant is the unexplained role of filler additives in polymer electrolytes[270,255,271] which markedly reduce the interfacial impedance in contact with Li. Thirty years after its initialobservation, the key issue of Li dendrite growth which was thought to be governed mainly by current densities,remains highly topical [272]. Bates et al. [90] succeeded in cycling LiCoO2/Li thin-film batteries for more than 50,000cycles using a glassy electrolyte in �1-mm thick films obtained by sputtering techniques. By controlling the uniformLi stripping–plating mechanism, the same authors demonstrated the feasibility of a Li-free, rechargeable, thin-filmbattery—that is, cells constructed in the discharged state with no Li metal initially present [34]. The use of solidelectrolyte, show that the problem of dendrite growth can be solved, at least with special cell configurations. Visco andco-workers [273] recently showed that a glassy nanometric layer deposited on Li metal completely insulates it from itsenvironment, even in the presence of liquids, and that coating can be applied at a high production rate. With furtherwork devoted to the implementation of these findings to large-size Li batteries, the development of a Li-freerechargeable battery remains a realistic goal for the future. The principal challenge for Li-based rechargeable batteries,or indeed for any battery, lies in gaining better understanding and control of the electrode–electrolyte interface in thehope of designing new solid–solid interfaces. For example, the nature of the secondary reactions occurring at hightemperature, which cause cell failure, remains an unanswered question that must be addressed to ensure the practicalsuccess of these technologies. In this case, however, the main difficulty stems from a lack of available techniques toprobe the evolution of the electrode–electrolyte interface at a local level. How the electrodes or interfaces age withtime either under cycling or storage conditions, thereby missing key information. But introduction of the plastic Li-ion-type technology has created new opportunities to perform a wide variety of in situ characterization techniques.These include X-ray absorption near-edge structure, nuclear magnetic resonance and Mossbauer spectroscopy, or evenscanning electron microscopy observations that allow real-time visualization of dendrite growth at an interface [274].Efforts aimed at developing new characterization tools must be vigorously pursued so as to create a comprehensivedatabase on the electrode–electrolyte interface.

7. Present status and remaining challenges of thin film lithium batteries

The performance of a thin film battery is evaluated in (i) open circuit voltage, (ii) maximum current, (iii) capacity,(iv) cyclability, etc. The open circuit voltage is almost determined by the combination of cathode and anode materialsas in the case of conventional lithium batteries. The cycle-life and lifetime are dependent on the nature of the interfaces


between the electrodes and electrolyte. The maximum available current of the battery is strongly depends on theinterfacial condition between the cathode, electrolyte and anode as well as on the diffusivity of electrons and ions inthe components.

Compared with mature batteries technologies, such as lead–acid or Ni–Cd, rechargeable Li-based batterytechnologies are still in their infancy, leaving much hope for improvement over the next decade. Table 4 shows thecomparison of the lithium battery performance with the other battery. Good cycle performance even more than 10,000has been reported, which is a strong advantage of thin film batteries [33,34]. Most important factor is the capacity ofthe battery, which depends primarily on the volume (thickness � area) of the cathode and anode as well as theirqualities. Such improvements should arise from changes in battery chemistry and cell engineering. Advances in activechemistry are left to the solid-state chemist’s creativity and innovation in the design and elaboration of newintercalation electrodes. Increase of the apparent capacity can be achieved by stacking two or more cells on onesubstrate [38], which will be a promising approach for future. Large volume change of electrode material duringcharge discharge process is another important factor of limiting the size and cycle performance. The shrink of theanode during discharging causes a clack of the anode or cathode which limit the maximum thickness and area of theelectrodes. Good and strong contact between electrode and electrolyte is necessary to overcome this difficulty, whichcan be achieved by post-anneal treatments. Actually, larger voltage drop appearing at the interface further limits themaximum current. If one can use lithium oxysulfide glasses whose conductivity is about 10�3 S/cm [275], theavailable current density will be up to 1 A/cm2. This is a reason of high performance of Eveready battery [89].


Table 4Comparison of the lithium battery performance with the other battery

Fig. 9. Different materials for the different battery applications.

Fig. 10. Previous and expected evolution of energy density/specific energy of Li-ion batteries (low power high density design).

Fig. 11. Smart card battery use as fingerprint scan, face recognition, hand geometry, eye scan, signature verification, voice recognition.

It is remaining to be addressed in future, finding the best-performing combination of electrode electrolyte can beachieved only through the selective use of existing and new materials as anode and cathode electrodes. It is necessaryto choose the right electrolyte combination, so as to minimize detrimental reactions associated with the electrode–

electrolyte interface. Battery technology is now in transition stage from traditional electrochemistry to solid-statephysics concerning ionic transport in solids and their interface. Thin film battery is a good entrance to this newchallenging field. Ideal thin film lithium battery must have these characters: (1) thin film must be compact and lightweight; (2) no heavy metal housing and modular; (3) can be made in variety of design and size; (4) excellent reliability,inherently safe; (5) high cycle time and high energy capacity; (6) low cost and wide temperature range; (7) 1% energyloss/year; (8) a high power density and high discharge voltage; (9) no memory effect; (10) do not use poisonous metals,such as lead, mercury or cadmium.

As a conclusion, one can expect a continuation of thin film lithium battery improvements in the next decade,resulting from both material and electrode design improvements. Various materials have the different advantages andalso some disadvantages in battery applications; this can be better understood by Fig. 9. Fig. 10 can explain in terms ofspecific energy or energy density of low-power cells, what can be anticipated, by extrapolation of the past 10 years.More than 200 Wh/kg and 500 Wh/L should be attained in few years [276]. Hope, in coming very short future thin filmlithium battery smart card will be commonly used for fingerprint scan, face recognition, hand geometry, eye scan,signature verification and voice recognition as shown in Fig. 11.

8. Conclusion

A rechargeable thin-film solid-state lithium battery is available today. The performance features of the battery also‘‘open the door’’ for an innovative method of recharging the battery and the battery offers the potential for an effectivelow energy power solution for many low power applications. Consumers are in constant demand for thinner, lighter,space effective and shape-flexible batteries with larger autonomy. Such demand will continue to generate muchresearch activity towards the development of new cell configurations and new chemistries. In this review we hope tohave conveyed the message that the field of energy storage is advancing faster than it perhaps has ever done in the past.The benefits, in terms of weight, size and design flexibility provided by today’s state-of-the-art Li-ion configurations.The Li-based battery chemistry is relatively young and as such is a source of aspirations as well as numerous excitingchallenges. The latter are not limited to solid-state chemists. The effort should be highly multidisciplinary with strongroots in the fields of organic and inorganic chemistry, physics, surface science and corrosion. Through materials designwe can expect significant improvements in energy density. Designing new materials can be intuitive or based onchemical concepts, coupling these efforts with those of theorists who are able to perform band-structure calculationson envisioned compounds will prove to be highly beneficial. Of equal importance is a better understanding of theelectrode–electrolyte interface to facilitate design of new interfaces. As thin film lithium rechargeable batteries entertheir teenage years, scientists and engineers predict an even brighter future lies ahead.

This review demonstrates how moving from bulk materials to the nanoscale can significantly change electrode andelectrolyte properties and consequently their performance in devices for energy storage and conversion. Anodes andcathodes of the nanomaterials with particular morphologies, like nanotube seem to be involved internally. Space-charge effects at the interface between small particles can result in substantial improvements of properties. There is aprofound effect of spatial confinement and contribution of surfaces, due to small particle size, on many of theproperties of materials; this challenges us to develop new theory. We also foresee that this subject will bring togetherthe disciplines of materials chemistry and surface science, as both are necessary to understand nanomaterials.

From a performance standpoint, lithium battery has the capability to replace nearly any other battery.Manufacturing costs for this battery based upon production techniques. The battery has three key design features thatoffer product designers greater flexibility in battery sizing, integration and power management:

(1) Solid state stability that prevents the battery from self-discharging with losses<1% per year when the battery is notin use.

(2) Long life, permanent power performance that negates the need to replace the battery for most applications. Thebattery has demonstrated full charge/discharge cycle performance >90,000.

(3) A very high packaging energy of >800 mW-h/cm2 and power density >120 mW/cm2 for pulse loads at a totalthickness of 35–60 mm (including substrate).


Traditionally, product designers size a battery for a defined performance life (i.e., 10 years) based on a power loadthat includes the primary power for the application, the self-discharge losses in the battery and some design margin. Nomajor revolution is expected for portable battery systems in the next 5–10 years. Increase in energy density andspecific energy of thin film lithium battery is, presently the best technical solution. It will still increase and rapidlyreach a limit. Thin film lithium battery will be the best option in most cases when long term operation is required formedium power systems, a hybrid system of lithium thin film battery and fuel cell appears to be a very attractive optionthat is available today. The Li–LiCoO2 battery is the most mature having the highest capacity, energy and powerdensities. These cells have cycle and shelf lives of thousands of cycles and many years, respectively. Promising resultshave also been obtained for cells with LiMn2O4 cathodes and for both the Li-free and Li anodes; although in each caseadditional research is required to understand and optimize the properties of the materials and interfaces. When thechemical states of the doped elements are optimized, electrochemical performance of materials is much improved.Introduction of heteroatom into anode and cathode will not only lower the cost but also improve electrochemicalperformance. This will propel the advance of composite/doping technology to prepare better and novel electrodematerials.

Both the performance and the safety of rechargeable lithium batteries strongly depend on the materials employed.Nowadays, rechargeable lithium batteries are essentially based on insertion electrodes. The present practice is tocombine a 4 V metal oxide (LiCoO2, LiNiO2, or LiMn2O4) with carbon (non-graphitic or graphite). The application ofmixed or doped oxides is also promising. For economical and ecological reasons there is a trend towards manganeseoxides. Carbon is generally used as the anode electro-active material, lithium-free cathode materials such as V2O5

have only had limited success on the market. However, the possible introduction of lithiated anode materials such asadvanced lithium alloys could change the situation. Carbonaceous electro-active materials are the state-of the-art ofthe anode. And still the future trends are directed towards higher specific charges and energy densities. In this respect,attention should be devoted to alternative anode materials because the charge densities of certain Li alloys exceed byfar that of carbon. Besides the development of materials, technical improvements, for example, new electrode and celldesigns, will also contribute to the rise of new generations of ion transfer cells. At the present stage of development,thin film lithium batteries are available for portable electronic devices. Moreover, several companies have announcedthe appearance of electric cars equipped with large lithium ion transfer thin film batteries in short future.

Acknowledgements

One of the author Dr. Arun Patil would like to thank to Hon. Rajkumar Agarwal Chairman of the BANSILALRAMNATH AGARWAL CHARITABLE TRUST, PUNE, India, Mr. Bharat Agarwal and Prof. S.B. Mantri fordeputing to the KIST, Seoul, South Korea.

References

[1] L.F. Nazar, et al. Int. J. Inorg. Mater. 3 (2001) 191.[2] M. Hirshes, Mater. Sci. Eng. B 108 (2004) 1.[3] S. Santhanagopalan, J. Power Sources 156 (2) (2006) 620.[4] T. Moon, C. Kim, B. Park, J. Power Sources 155 (2) (2006) 391.[5] J. Schwenzel, V. Thangadurai, W. Weppner, J. Power Sources 154 (1) (2006) 232.[6] M. Armand, Thesis, Grenoble, 1978; French Patent 78 32977 (1978).[7] A. Yoshino, Japanese Patent 1989 293 (1985) to Asahi Kasei; US Patent 4,668,595 (1987).[8] Y.P. Wu, C. Wan, C. Jiang, S.B. Fang, Introduction, Principles and Advances of Lithium Secondary Batteries, Tsinghua University Press,

Beijing, 2002.[9] J.M. Yarascon, M. Armand, Nature 414 (2001) 359.

[10] H. Ikeda, T. Saito, H. Tamura, in: A. Kozawa, R.H. Brodd, Proc. Manganese Dioxide Symp., vol. 1, IC Sample Office, Cleveland, OH, 1975.[11] B.C.H. Steele, in: W. Van Gool (Ed.), Fast Ion Transport in Solids, North-Holland, Amsterdam, 1973, pp. 103–109.[12] F.J. Di Salvo, R. Schwall, T.H. Geballe, F.R. Gamble, J.H. Osieki, Phys. Rev. Lett. 27 (1971) 310.[13] M.S. Whittingham, Science 192 (1976) 1226.[14] M.S. Whittingham, Chalcogenide Battery. US Patent 4009052.[15] B.M.L. Rao, R.W. Francis, H.A. Christopher, J. Electrochem. Soc. 124 (1977) 1490.[16] J. Broahead, A.D. Butherus, Rechargeable Non-Aqueous Battery. US Patent 3791867.[17] D.W. Murphy, P.A. Christian, Science 205 (1979) 651.[18] K. Mizushima, P.C. Jones, P.J. Wiseman, J.B. Goodenough, Mater. Res. Bull. 15 (1980) 783.


[19] M.M. Thackeray, W.I.F. David, P.G. Bruce, J.B. Goodenough, Mater. Res. Bull. 18 (1983) 461.[20] D.W. Murphy, F.J. DiSalvo, J.N. Carides, J.V. Waszczak, Mater. Res. Bull. 13 (1978) 1395.[21] M. Lazzari, B. Scrosati, J. Electrochem. Soc. 127 (1980) 773.[22] F.G. Will, US Patent 3874958 (1975).[23] A. Percheron-Guegan, J.C. Achard, J. Sarradin, G. Bronoël, French Patent 7516160 (1975).[24] F. Kirino, Y. Ito, K. Miyauchi, T. Kudo, Nippon Kagakukaishi (1986) 445.[25] K. Kanehori, K. Matsumoto, K. Miyauchi, T. Kudo, Solid State Ionics 9–10 (1983) 1445.[26] I.E. Kelly, J.R. Owen, B.H. Steel, J. Power Sources 14 (1985) 13.[27] T. Nagaura, K. Tozawa, Prog. Batteries Solar Cells 9 (1990) 209.[28] H. Ohtsuka, J. Yamaki, Jpn. J. Appl. Phys. 28 (1989) 2264.[29] H. Ohtsuka, S. Okada, J. Yamaki, Solid State Ionics 40 (1990) 964.[30] J.R. Akridge, H. Vourlis, Solid State Ionics 18–19 (1986) 1082.[31] J.R. Akridge, H. Vourlis, Solid State Ionics 28–30 (1988) 841.[32] X. Yu, J.B. Bates, G.E. Jellison, F.X. Hart, J. Electrochem. Soc. 144 (1997) 524.[33] B. Wang, J.B. Bates, F.X. Hart, B.C. Sales, R.A. Zuhr, J.D. Robertson, J. Electrochem. Soc. 143 (1996) 3203.[34] B.J. Neudecker, N.J. Dudney, J.B. Bates, J. Electrochem. Soc. 147 (2000) 517.[35] Y.S. Park, S.H. Lee, B.I. Lee, S.K. Joo, Electrochem. Solid State Lett. 2 (1999) 58.[36] M. Baba, N. Kumagai, H. Kobayashi, O. Nakano, K. Nishidate, Electrochem. Solid State Lett. 2 (1999) 320.[37] M. Baba, N. Kumagai, N. Fujita, K. Ohta, K. Nishidate, S. Komaba, H. Groult, D. Devilliers, B. Kaplan, J. Power Sources 97–98 (2001) 798.[38] M. Baba, N. Kumagai, H. Fujita, K. Ohta, K. Nishidate, S. Komaba, B. Kaplan, H. Groult, D. Devilliers, J. Power Sources 119 (2003) 914.[39] O. Haas, E. Deiss, P. Novmk, W. Scheifele, A. Tsukada, in: C.F. Holmes, A.R. Landgrebe (Eds.), Batteries for Portable Applications and

Electric Vehicles, The Electrochemical Society, Pennington, NJ, 1997, PV 97-18, p. 451. Adv. Mater. 1998, 10, No. 10 Ó WILEY-VCH VerlagGmbH, D-69469 Weinheim, 1998, 0935-9648/98/1007-0761 $17.50+.50/0 761 M. Winter et al./Insertion Electrode Materials for LithiumBatteries 762 Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 1998, 0935-9648/98/1007-0762 $17.50+.50/0 Adv. Mater. 1998, 10,No. 10.

[40] F.R. Kalhammer, A. Kozawa, C.B. Moyer, B.B. Owens, Interface 1 (1996) 33.[41] Y. Nishi, K. Katayama, Extended Abstracts of the 8th Int. Mtg. on Lithium batteries, Nagoya, Japan, (1996), p. 13.[42] K. Brandt, Extended Abstracts of the 8th Int. Mtg. on Lithium Batteries, Nagoya, Japan, (1996), p. 9.[43] B. Scrosati, Nature 373 (1995) 557.[44] Zhang et al., US Patent 10,207,445 (2002).[45] K. Zaghib, X. Song, J. Power Sources 119–121 (2003) 8.[46] Doron Aurbach, Hanan Teller, J. Power Sources 119–121 (2003) 2.[47] A. Concheso, R. Santamaría, R. Menéndez, J.M. Jiménez-Mateos, R. Alcántara, P. Lavela, J.L. Tirado, Carbon 44 (2006) 1762.[48] F. Béguin, F. Chevallier, C. Vix-Guterl, S. Saadallah, V. Bertagna, J.N. Rouzaud, E. Frackowiak, Carbon 43 (2005) 2160.[49] K. Brandt, Solid State Ionics 69 (1994) 173.[50] K. Brandt, J. Power Sources 54 (1995) 151.[51] S. Basu, US Patent 4 423 125, 1983.[52] K. Brandt, R. Herr, GDCh-Monograph 3 (1996) 429.[53] S.A. Megahed, W.B. Ebner, in: Proceedings of the 9th Annual Battery Conference on Applications and Advances, Long Beach, CA, (1994), p.

129.[54] J. Thomas, Nat. Mater. 2 (2003) 705.[55] Young-II Jang, B.J. Neudecker, N.J. Dudney, Electrochem. Solid State Lett. 4 (6) (2001) A74.[56] N.J. Dudney, Young-II Jang, J. Power Sources 119–121 (2003) 300.[57] S.H. Choi, J. Kim, Y.S. Yoon, J. Power Sources 135 (2004) 286.[58] K. Ozawa, Solid State Ionics 69 (1994) 212.[59] Y. Idemoto, H. Narai, N. Koura, J. Power Sources 119–121 (2003) 125.[60] Yoshanari Makimura, Tsutomu Ohzuku, 119–121 (2003) 156.[61] M. Broussely, F. Perton, P. Biensan, J.M. Bodet, J. Labat, A. Lecerf, C. Delmas, A. Rougier, J.P. Peres, J. Power Sources 54 (1995) 109.[62] A. Lecerf, M. Broussely, J.-P. Gabano, US Patent 4 980 080 (1990).[63] P. Piszora, W. Paszkowicz, J. Alloy Compd. 382 (2004) 119.[64] J. Rodriguez-Carvajal, G. Rousse, C. Masquelier, M. Hervieu, Phy. Rev. Lett. 81 (1998) 4660.[65] T.A. Erricson, M.M. Doeff, J. Power Sources 119–121 (2003) 145.[66] Z.P. Guo, K. Konstantinov, G.X. Wang, J. Power Sources 119–121 (2003) 221.[67] J.-M. Tarascon, US Patent 5 196 279 (1993).[68] Y. Asami, K. Tsuchuya, H. Nose, S. Suzuki, in: R.J. Brodd (Ed.), Progress in Batteries and Battery Materials, vol. 14, JEC Press, Brunswick,

OH, 1995, p. 151.[69] I. Exnar, L. Kavan, S.Y. Huang, M. Grätzel, J. Power Sources 68 (1997) 720.[70] M. Hess, E. Lebraud, A. Levasseur, J. Power Sources 68 (1997) 204.[71] C. Julien, in: G. Pistoia (Ed.), Lithium Batteries: New Materials, Developments and Perspectives, Elsevier, Amsterdam, 1994, p. 167.[72] J.B. Bates, N.J. Dudney, D.C. Lubben, G.R. Gruzalski, B.S. Kwak, X. Yu, R.A. Zuhr, J. Power Sources 54 (1995) 58.[73] M. Armand, J.Y. Sanchez, M. Gauthier, Y. Choquette, in: J. Lipkowski, P.N. Ross (Eds.), The Electrochemistry of Novel Materials, VCH,

Weinheim, 1994, p. 65.


[74] M. Alamgir, K.M. Abraham, in: G. Pistoia (Ed.), Lithium Batteries: New Materials, Developments and Perspectives, Elsevier, Amsterdam,1994, p. 49.

[75] R.P. Hollandsworth, M.A. Mueller, E.A. Cuellar, J.A. Read, in: Proceedings of the 37th Power Sources Conference, Cherry Hill, NJ, (1996), p.307.

[76] E.A. Cuellar, B.M. Coffey, J.R. Read, S. Lewin, in: Proceedings of the 37th Power Sources Conference, Cherry Hill, NJ, (1996), p. 291.[77] C.N. Schmutz, J.M. Tarascon, A.S. Gozdz, P.C. Warren, F.K. Shokoohi, in: S. Megahed, B.M. Barnett, L. Xie (Eds.), Rechargeable Lithium

and Lithium-Ion Batteries, Electrochemical Society, Pennington, NJ, 1995, , p. 330, PV94-28.[78] D. Fouchard, L. Xie, W. Ebner, S. Megahed, in: S. Megahed, B.M. Barnett, L. Xie (Eds.), Rechargeable Lithium and Lithium-Ion Batteries,

Electrochemical Society, Pennington, NJ, 1995, , p. 349, PV94-28.[79] S. Hossain, in: D. Linden (Ed.), Handbook of Batteries, McGraw-Hill, New York, 1995 (chapter 36).[80] P. Novmk, W. Scheifele, M. Winter, O. Haas, J. Power Sources 68 (1997) 267.[81] J. Yang, M. Winter, J.O. Besenhard, Solid State Ionics 90 (1996) 281.[82] S. Atlung, K. West, J. Power Sources 26 (1989) 139.[83] M. Doyle, J. Newman, J. Power Sources 54 (1995) 46.[84] B. Paxton, J. Newman, J. Electrochem. Soc. 143 (1996) 1287.[85] J.-M. Tarascon, M. Armand, Nature 414 (2001) 359.[86] W. Wakihara, O. Yamamoto (Eds.), Lithium Ion Batteries—Fundamentals and Performance, Kodansha-Wiley-VCH, Weinheim, 1998.[87] W. van Schalkwijk, B. Scrosati (Eds.), Advances in Lithium-Ion Batteries, Kluwer Academic/Plenum, New York, 2002.[88] R. Creus, S. J., and R. M., Solid State Ionics 53(6) (1992) 641.[89] S.D. Jones, J.R. Akridge, Solid State Ionics 53-6 (1992) 628.[90] J.B. Bates, N.J. Dudney, B. Neudecker, A. Ueda, C.D. Evans, Solid State Ionics 135 (2000) 33.[91] M. Duclot, J.L. Souquet, J. Power Sources 97 (8) (2001) 610.[92] J.L. Souquet, M. Duclot, Solid State Ionics 148 (2002) 375.[93] M. Winter, J.O. Besenhard, M.E. Spahr, P. Novak, Adv. Mater. 10 (1998) 725.[94] A.S. Arico, P. Bruce, B. Scrosati, J.-M. Tarascon, W. Van Schalkwijk, Nature 4 (2005) 366.[95] R.A. Huggins, in: J.O. Besenhard (Ed.), Handbook of Battery Materials, Wiley-VCH, Weinheim, 1999, , Part III (chapter 4).[96] M. Winter, J.O. Besenhard, Electrochem. Acta 45 (1999) 31.[97] M.-S. Park, S. Rajendran, Y.-M. Kang, K.-S. Han, Y.-S. Han, J.-Y. Lee, J. Power Sources 158 (1) (2006) 650.[98] J.R. Dahn, A.K. Sleigh, H. Shi, B.M. Way, W.J. Weydanz, J.N. Reimers, Q. Zhong, U. von Sacken, in: G. Pistoia (Ed.), Lithium Batteries: New

Materials, Developments and Perspectives, Elsevier, Amsterdam, 1994, p. 1.[99] M. Yoshio, S. Kugino, N. Dimov, J. Power Sources 153 (2) (2006) 375.

[100] R. Yazami, M.Z.A. Munshi, Handbook of Solid State Batteries and Capacitors, 1995 ISBN no. 981-02-1794-3.[101] I.A. Courtney, J.R. Dahn, J. Electrochem Soc. 144 (1997) 2045.[102] T. Doi, K. Takeda, T. Fukutsuka, Y. Iriyama, T. Abe, Z. Ogumi, Carbon 43 (11) (2005) 2352.[103] F. Béguin, F. Chevallier, C. Vix-Guterl, S. Saadallah, V. Bertagna, J.N. Rouzaud, E. Frackowiak, Carbon 44 (10) (2005) 2160.[104] G. Brancolini, F. Negri, Carbon 42 (5–6) (2004) 1001.[105] S. Pruvost, C. Hérold, A. Hérold, P. Lagrange, Carbon 42 (8–9) (2004) 1825.[106] C. Hérold, S. Pruvost, A. Hérold, P. Lagrange, Carbon 42 (10) (2004) 2122.[107] T.D. Tran, J.H. Feikert, X. Song, K. Kinoshita, J. Electrochem. Soc. 142 (1995) 3297.[108] S. Pruvost, C. Hérold, A. Hérold, P. Lagrange, Carbon 41 (6) (2003) 1281.[109] D. Billaud, L. Balan, R. Schneider, P. Willmann, Carbon 44 (2006) 2508.[110] C. Arbizzani, S. Beninati, M. Lazzari, M. Mastragostino, J. Power Sources 158 (1) (2006) 635.[111] H. Zheng, K. Jiang, T. Abe, Z. Ogumi, Carbon 44 (2) (2006) 203.[112] L. Balan, J. Ghanbaja, P. Willmann, D. Billaud, Carbon 43 (11) (2005) 2311.[113] C. Delabarre, M. Dubois, J. Giraudet, K. Guérin, A. Hamwi, Carbon 44 (2006) 2543.[114] A. Concheso, R. Santamaría, R. Menéndez, J.M. Jiménez-Mateos, R. Alcántara, P. Lavela, J.L. Tirado, Carbon 44 (9) (2006) 1762.[115] N. Yoshizawa, O. Tanaike, H. Hatori, K. Yoshikawa, A. Kondo, T. Abe 44 (2006) 2558.[116] H. Konno, T. Morishita, S. Sato, H. Habazaki, M. Inagaki, Carbon 43 (5) (2005) 1110.[117] L. Bai, US Patent 5 480 740 (1996).[118] K.M. Abraham, D.M. Pasquariello, E.B. Willstaedt, G.F. McAndrews, in: J.-P. Gabano, Z. Takehara, P. Bro (Eds.), Primary and Secondary

Ambient Temperature Lithium Batteries, Electrochemical Society, Pennington, NJ, 1988, , p. 669, PV88-6.[119] J.O. Besenhard, J. Yang, M. Winter, J. Power Sources 68 (1997) 87.[120] T. Nohma, S. Yoshimura, K. Nishio, Y. Yamamoto, S. Fukuoka, M. Hara, J. Power Sources 58 (1996) 205.[121] Sanyo Electric, US Patent 4 820 599 (1989).[122] JEC Battery Newslett. 3 (1989) 15.[123] Nippon Denki Shinbun, March 11, 1996.[124] Y. Idota, T. Kubota, A. Matsufuji, Y. Maekawa, T. Miyasaka, Science 276 (1997) 1395.[125] R.A. Huggins, in: C.F. Holmes, A.R. Landgrebe (Eds.), Batteries for Portable Applications and Electric Vehicles, Electrochemical Society,

Pennington NJ, 1997, , p. 1, PV97-18.[126] Z.P. Guo, Z.W. Zhao, H.K. Liu, S.X. Dou, Carbon 43 (7) (2005) 1392.[127] E.J. Plichta, W.K. Behl, J. Electrochem. Soc. 140 (1993) 46.[128] B. Scrosati, J. Electrochem. Soc. 139 (1992) 2776.


[129] J.J. Auborn, Y.L. Barberio, J. Electrochem. Soc. 134 (1987) 638.[130] C. Tsang, A. Manthiram, J. Electrochem. Soc. 144 (1997) 520.[131] A. Concheso, R. Santamaría, C. Blanco, R. Menéndez, J.M. Jiménez-Mateos, R. Alcántara, P. Lavela, J.L. Tirado, Carbon 43 (5) (2005) 923.[132] M. Grätzel, Chemtech 67 (1995) 1300.[133] D. Guyomard, C. Sigala, A. Le Gal La Salle, Y. Piffard, J. Power Sources 68 (1997) 692.[134] Y. Piffard, F. Leroux, D. Guyomard, J.-L. Mansot, M. Tournoux, J. Power Sources 68 (1997) 698.[135] T. Shodai, S. Okada, S. Tobishima, J. Yamaki, J. Power Sources 68 (1997) 515.[136] Y. Idota, et al., Nonaqueous Battery, US Patent No. 5,478,671 (1995).[137] P. Poizot, S. Laruelle, S. Grugeon, L. Dupont, J.-M. Tarascon, Nature 407 (2000) 496.[138] Y. Idota, T. Kubota, A. Matsufuji, Y. MaeKawa, T. Miyasaka, Science 276 (1997) 1395.[139] J.-M. Tarascon, S. Grugeon, S. Laruelle, D. Larcher, P. Poizot, in: G.-A. Nazri, G. Pistoia (Eds.), Lithium Batteries Science and Technology,

Kluwer Academic/Plenum, Boston, 2004 , p. 220 (chapter 7).[140] S. Denis, E. Baudrin, M. Touboul, J.-M. Tarascon, J. Electrochem. Soc. 144 (1997) 4099.[141] F. Leroux, G.R. Coward, W.P. Power, L.F. Nazar, Electrochem. Solid State Lett. 1 (1998) 255.[142] F. Badway, F. Cosandey, N. Pereira, G.G. Amatucci, J. Electrochem. Soc. 150 (2003) A1318.[143] H. Li, G. Ritcher, J. Maier, Adv. Mater. 15 (2003) 736.[144] J. Jamnik, J. Maier, Phys. Chem. 5 (2003) 5215.[145] D. Larcher, et al. J. Electrochem. Soc. 150 (2003) A133.[146] J.Y. Eom, H.S. Kwon, J. Liu, O. Zhou, Carbon 42 (12–13) (2004) 2589.[147] Z. Zhou, X. Gao, J. Yan, D. Song, M. Morinaga, Carbon 42 (12–13) (2004) 2677.[148] K. Sato, M. Noguchi, A. Demachi, N. Oki, M. Endo, Science 264 (1994) 556.[149] Y.P. Wu, C. Wan, C. Jiang, S.B. Fang, Y.Y. Jiang, Carbon 37 (1999) 1901.[150] G. Sandi, R.E. Winans, K.A. Carrado, J. Electrochem. Soc. 143 (1996) L95.[151] C. Kim, T. Fujino, K. Miyashita, T. Hayashi, M. Endo, M.S. Dresselhaus, J. Electrochem. Soc. 147 (2000) 1257.[152] T. Shirasaki, A. Derre, K. Guenrin, S. Flandrois, Carbon 37 (1999) 1961.[153] Y.P. Wu, S.B. Fang, Y.Y. Jiang, Solid State Ionics 120 (1999) 117.[154] C.S. Wang, G.T. Wu, X.B. Zhang, Z.F. Qi, W.Z. Li, J. Electrochem. Soc. 145 (1998) 2751.[155] M. Kamauchi, Y. Takada, T. Nishihara, JP 7-302558 (1995).[156] Y.P. Wu, C. Wan, C. Jiang, S.B. Fang, Y.Y. Jiang, Chin. J. Power Sources 24 (2000) 36.[157] Y.P. Wu, S.B. Fang, Y.Y. Jiang, J. Power Sources 75 (1998) 201.[158] Y.P. Wu, S.B. Fang, Y.Y. Jiang, R. Holze, J. Power Sources 108 (2002) 245.[159] R. Tossici, M. Berrettoni, M. Rosolen, R. Marassi, B. Scrosati, J. Electrochem. Soc. 144 (1997) 186.[160] Y. Nishi, IUPAC Eighth International Symposium on Macromolecule Metal complexes (MMC-8), 1999, p. 44.[161] Y. Nitsuta, JP 8-106898 (1996).[162] Y. Nitsuta, JP 8-106899 (1996).[163] S. Kim, Y. Kadoma, H. Ikuta, Y. Uchimoto, M. Wakihara, Electrochem. Solid State Lett. 4 (2001) A109.[164] Y.P. Wu, W.G. Ju, S.B. Fang, Y.Y. Jiang, J. Power Sources 70 (1998) 114.[165] Y.P. Wu, S.B. Fang, Y.Y. Jiang, J. Power Sources 75 (1998) 167.[166] P. Yu, J.A. Ritter, R.E. White, B.N. Popov, J. Electrochem. Soc. 147 (2000) 1280.[167] M.M. Thackeray, J.T. Vaughey, A.J. Kahaian, K.D. Kelper, R. Benedek, Electrochem. Commun. 1 (1999) 111.[168] J.O. Besenhard, J. Yang, M. Winter, J. Power Sources 68 (1997) 87.[169] J. Yang, M. Wachtler, M. Winter, J.O. Besenhard, Electrochem. Solid State Lett. 2 (1999) 161.[170] Y. Wen, L. Zeng, Z. Tong, L. Nong, W. Wei, J. Alloy Compd. 416 (1–2) (2006) 206.[171] C.H. Mi, X.G. Zhang, X.B. Zhao, H.L. Li, J. Alloy Compd. 424 (2006) 327.[172] K. Onda, T. Ohshima, M. Nakayama, K. Fukuda, T. Araki, J. Power Sources 158 (2006) 535.[173] P.G. Balakrishnan, R. Ramesh, T. Prem Kumar, J. Power Sources 155 (2) (2006) 401.[174] K. Kobayashi, K. Kosuge, S. Kachi, Mater. Res. Bull. 4 (1969) 95.[175] W. Rüdorf, H. Becker, Z. Naturforsch. 9 (1954) 614.[176] C.L. Liao, M.T. Wu, J.H. Yen, I.C. Leu, K.Z. Fung, J. Alloy Compd. 414 (1–2) (2006) 302.[177] S.-C. Han, H.-S. Kim, M.-S. Song, P.S. Lee, J.-Y. Lee, H.-J. Ahn, J. Alloy Compd. 349 (1–2) (2003) 290.[178] J. Yamaki, M. Makidera, T. Kawamura, M. Egashira, S. Okada, J. Power Sources 153 (2006) 245.[179] P. Liu, S.-H. Lee, Y. Yan, C.E. Tracy, J.A. Turner, J. Power Sources 158 (2006) 659.[180] W.Y. Liang, in: M.S. Dresselhaus (Ed.), Intercalation in Layered Materials, NATO ASI Series B 1986, vol. 148, p. 31.[181] A. Mendiboure, C. Delmas, P. Hagenmuller, Mater. Res. Bull. 19 (1984) 1383.[182] M.G.S.R. Thomas, P.G. Bruce, J.B. Goodenough, Solid State Ionics 18 (1986) 794.[183] J. Molenda, Phys. Stat. Sol. B 122 (1984) 591.[184] S. Konezawa, T. Okayama, H. Tsuda, M. Takashima, J. Fluorine Chem. 87 (1998) 141.[185] H. Huang, G.V. Rao, B. Chowdari, J. Power Sources 81–82 (1999) 690.[186] R.J. Gummow, D.C. Liles, M.M. Thackeray, Mater. Res. Bull. 28 (1993) 1249.[187] R.J. Gummow, M.M. Thackeray, J. Electrochem. Soc. 141 (1994) 1178.[188] S.A. Campbell, C. Bows, R.S. McMillan, J. Electroanal. Chem. 284 (1990) 195.[189] P.G. Bruce, A. Lisowska-Oleksiak, M.Y. Saidi, C.A. Vincent, Solid State Ionics 57 (1992) 353.


[190] H. Hirano, R. Kanno, Y. Kawamato, Y. Takeda, K. Yamaura, M. Takano, K. Ohyama, M. Ohashi, Y. Yamaguchi, Solid State Ionics 78 (1995)123.

[191] L. Xie, W. Ebner, D. Fouchard, S. Megahead, in: S. Megahed, B.M. Barnett, L. Xie (Eds.), Rechargeable Lithium and Lithium-Ion Batteries,Electrochemical Society, Pennington, NJ, 1995, , p. 263, PV94-28.

[192] A. Rougier, P. Gavereau, C. Delmas, J. Electrochem. Soc. 143 (1996) 1168.[193] T. Ohzuku, A. Ueda, M. Nagayama, Y. Iwakoshi, H. Komori, Electrochim. Acta 38 (1993) 1159.[194] S.J. Jin, C.H. Song, K.S. Park, A.M. Stephan, K.S. Nahm, Y.S. Lee, J.K. Kim, H.T. Chung, J. Power Sources 158 (2006) 620.[195] J. Kim, B.H. Kim, Y.H. Baik, P.K. Chang, H.S. Park, K. Amine, J. Power Sources 158 (2006) 641.[196] X. Li, F. Kang, W. Shen, Carbon 44 (7) (2006) 1334.[197] J. Li, X. He, R. Zhao, C. Wan, C. Jiang, D. Xia, S. Zhang, J. Power Sources 158 (2006) 524.[198] C. Delmas, M. Menetrier, L. Croguenmec, I. Saadonne, A. Rougier, C. Pouillerie, G. Prado, M. Grune, L. Fournes, Electrochim. Acta 45

(1999) 243.[199] J.N. Reimers, E. Rossen, C.D. Jones, J.R. Dahn, Solid State Ionics 61 (1993) 335.[200] I. Uchida, J.R. Selman, J. Solid State Electrochem. 3 (1999) 148.[201] J. Kim, K. Amine, Electrochem. Commun. 3 (2001) 52.[202] H.J. Kweon, G.B. Kim, H.S. Lim, S.S. Nam, D.G. Park, J. Power Sources 83 (1999) 84.[203] T. Sato, T. Koyama, M. Mukai, K. Kobayakawa, Denki Kagaku 66 (1998) 1215.[204] Y. Gao, M.V. Yakovleva, W.B. Ebner, Electrochem. Solid State Lett. 1 (1998) 117.[205] J. Desilvestro, O. Haas, J. Electrochem. Soc. 137 (1990) 5C.[206] B.G. Silbernagel, Solid State Commun. 17 (1975) 361.[207] B. van Laar, D.V.W. Ijdo, Solid State Commun. 3 (1974) 590.[208] S.-C. Han, H.-S. Kim, M.-S. Song, J.-H. Kim, H.-J. Ahn, J.-Y. Lee, J. Alloy Compd. 351 (1–2) (2003) 273.[209] M.S. Whittingham, Prog. Solid State Chem. 12 (1978) 41.[210] A.J. Jacobson, R.R. Chilannelli, M.S. Whittingham, J. Electrochem. Soc. 12 (1979) 2277.[211] A. Yamada, S.C. Chung, K. Hinokuma, J. Electrochem. Soc. 148 (2001) A224.[212] A.K. Pahdi, K.S. Najundaswamy, J.B. Goodenough, J. Electrochem. Soc. 144 (1997) 1188.[213] H. Huang, S.-C. Yin, L.F. Nazar, Electrochem. Solid State Lett. 4 (2001) A170.[214] H.-H. Chang, C.-C. Chang, H.-C. Wu, Z.-Z. Guo, M.-H. Yang, Y.-P. Chiang, H.-S. Sheu, N.-L. Wu, J. Power Sources 158 (2006) 550.[215] S.R. Das, I.R. Fachini, S.B. Majumder, R.S. Katiyar, J. Power Sources 158 (2006) 518.[216] R. Schöllhorn, Angew. Chem. Int. Ed. Engl. 19 (1980) 983.[217] P. Shen, D. Jia, Y. Huang, L. Liu, Z. Guo, J. Power Sources 158 (2006) 608.[218] J. Tu, X.B. Zhao, J. Xie, G.S. Cao, D.G. Zhuang, T.J. Zhu, J.P. Tu, J. Alloy Compd. 432 (2007) 313.[219] Y.P. Wu, Y. Li, C. Wan, C. Jiang, Chin. J. Funct. Mater. 31 (2000) 18.[220] H. Shigemura, H. Sakaebe, H. Kageyama, H. Kobayashi, A.R. West, R. Kanno, S. Morimoto, S. Nasu, M. Tabuchi, J. Electrochem. Soc. 148

(2001) A730.[221] A.R. Armstrong, A.D. Robertson, P.G. Bruce, Electrochim. Acta 45 (1999) 285.[222] P. Avora, B.M. Popov, R.E. White, J. Electrochem. Soc. 145 (1998) 807.[223] Y.K. Sun, Y.S. Jeon, Electrochem. Commun. 1 (1999) 597.[224] G. Li, H. Ikuta, T. Uchida, M. Wakihara, J. Electrochem. Soc. 143 (1996) 178.[225] Q. Zhong, A. Bonakderpour, M. Zhang, Y. Gao, J.R. Dahn, J. Electrochem. Soc. 144 (1997) 205.[226] R.J. Gummow, A. De Kock, M.M. Thackeray, Solid State Ionics 69 (1994) 59.[227] F. Le Cras, D. Bloch, M. Anne, P. Strobel, Solid State Ionics 89 (1996) 203.[228] A. de Kock, E. Feng, R.J. Gummow, J. Power Sources 70 (1998) 247.[229] J.C. Hunter, J. Solid State Chem. 39 (1981) 142.[230] A. Mosbah, A. Verbaere, M. Tournoux, Mater. Res. Bull. 18 (1983) 1375.[231] T. Ohzuku, in: G. Pistoia (Ed.), Lithium Batteries: New Materials, Developments and Perspectives, Elsevier, Amsterdam, 1994, p. 239.[232] M.M. Thackeray, Mater. Res. Soc. Symp. Proc. 369 (1995) 17.[233] L. Chen, X. Huang, E. Kelder, J. Schoonman, Solid State Ionics 76 (1995) 91.[234] T. Ohzuku, H. Fukuda, T. Hirai, Chem Express 2 (1987) 543.[235] A. Yamada, M. Tanaka, Mater. Res. Bull. 30 (1995) 715.[236] W.I.F. David, M.M. Thackeray, L.A. Picciotto, J.B. Goodenough, J. Solid State Chem. 67 (1987) 316.[237] F. Le Cras, D. Bloch, M. Anne, P. Strobel, Mater. Res. Soc. Symp. Proc. 369 (1995) 39.[238] T. Tsumura, A. Shimizu, M. Inagaki, Solid State Ionics 90 (1996) 197.[239] Y.-P. Fu, Y.-H. Su, S.-H. Wu, C.-H. Lin, J. Alloy Compd. 426 (2006) 228.[240] A. Caballero, L. Hernán, M. Melero, J. Morales, R. Moreno, B. Ferrari, J. Power Sources 158 (2006) 583.[241] R.J. Gummow, A. de Kock, M.M. Thackeray, Solid State Ionics 69 (1994) 59.[242] B.G. Hyde, S. Anderson (Eds.), Inorganic Crystal Structures, Wiley, New York, 1989, p. 16.[243] C. Delmas, in: G. Pistoia (Ed.), Lithium Batteries: New Materials, Developments and Perspectives, Elsevier, Amsterdam, 1994, p. 457.[244] J.P. Pereira-Ramos, N. Baffier, G. Pistoia, in: G. Pistoia (Ed.), Lithium Batteries: New Materials, Developments and Perspectives, Elsevier,

Amsterdam, 1994, p. 281.[245] K. Salloux, F. Chaput, H.P. Wong, B. Dunn, M.W. Breiter, J. Electrochem. Soc. 142 (1995) L191.[246] K. West, B. Zachau-Christiansen, T. Jacobsen, S. Skaarup, Electrochim. Acta 38 (1993) 1215.


[247] L.A. de Picotto, M.M. Thackeray, G. Pistoia, Solid State Ionics 28 (1988) 1364.[248] F. Croce, G.B. Appetcchi, L. Persi, B. Scrosati, Nature 394 (1998) 456.[249] B. Scrosati, F. Croce, L. Persi, J. Electrochem. Soc. 147 (2000) 1718.[250] P.A.R.D. Jayathilaka, M.A.K.L. Dissanayake, I. Albinsson, B.E. Mellander, Electrochim. Acta 47 (2002) 3257.[251] B.K. Mandal, A.K. Padhi, Z. Shi, S. Chakraborty, R. Filler, J. Power Sources 162 (2006) 690.[252] B.K. Mandal, A.K. Padhi, Z. Shi, S. Chakraborty, R. Filler, J. Power Sources 161 (2006) 215.[253] Y. Li, J.A. Yerian, S.A. Khan, P.S. Fedkiw, J. Power Sources 161 (2006) 1288.[254] C. Korepp, H.J. Santner, T. Fujii, M. Ue, J.O. Besenhard, K.-C. Möller, M. Winter, J. Power Sources 158 (1) (2006) 578.[255] H. Nakahara, S.-Y. Yoon, S. Nutt, J. Power Sources 158 (1) (2006) 600.[256] T. Kawamura, S. Okada, J.-I. Yamaki, J. Power Sources 156 (1) (2006) 547.[257] F. Croce, S. Sacchetti, B. Scrosati, J. Power Sources 161 (2006) 560.[258] J. Reiter, J. Michálek, J. Vondrák, D. Chmelíková, M. Prádny, Z. Micka, J. Power Sources 158 (1) (2006) 509.[259] J.M. Reddy, P.P. Chu, U.V. Subba Rao, J. Power Sources 158 (1) (2006) 614.[260] S.D. Jones, J.R. Akridge, F.K. Shokoohi, Solid State Ionics 69 (1994) 357.[261] N. Kuwata, J. Kawamura, K. Toribami, T. Hattori, N. Sata, Electrochem. Commun. 6 (2004) 417.[262] S.S. Zhang, J. Power Sources 161 (2006) 1385.[263] R. Kanno, M. Murayama, J. Electrochem. Soc. 148 (2001) A742.[264] M. Murayama, N. Sonoyama, A. Yamada, R. Kanno, Solid State Ionics 170 (2004) 173.[265] M. Tatsumisago, F. Mizuno, A. Hayashi, J. Power Sources 159 (2006) 193.[266] P. Balaya, A.J. Bhattacharyya, J. Jamnik, Yu.F. Zhukovskii, E.A. Kotomin, J. Maier, J. Power Sources 159 (2006) 171.[267] J. Han, Y. Jia, S. Jin, Y. Jing, M. Tillard, C. Belin, Energy 31 (12) (2006) 1757.[268] C.-L. Liao, C.-H. Wen, K.-Z. Fung, J. Alloys Compd. 432 (2007) L22.[269] K. Edström, M. Herstedt, D.P. Abraham, J. Power Sources 153 (2) (2006) 380.[270] H. Nakahara, S.-Y. Yoon, T. Piao, F. Mansfeld, S. Nutt, J. Power Sources 158 (1) (2006) 591.[271] T. Doi, K. Miyatake, Y. Iriyama, T. Abe, Z. Ogumi, T. Nishizawa, Carbon 42 (15) (2004) 3183.[272] D. Aurbach, J. Power Sources 89 (2000) 206.[273] S.J. Visco, Conference Proceedings of the International Meeting on Power Sources for Consumer and Industrial Applications, Hawaii,

September 3–6, 2001.[274] F. Orsini, et al. J. Power Sources 81–82 (1999) 918.[275] M. Tatsumisago, S. Hama, A. Hayashi, H. Morimoto, T. Minami, Solid State Ionics 154 (2002) 635.[276] M. Broussely, G. Archdale, J. Power Sources 136 (2004) 386.[277] F. Kirino, Y. Ito, K. Miyauchi, T. Kudo, Nippon Kagakukaishi (Jap) (1986) 445.[278] R. Creus, J. Sarradin, R. Astier, A. Pradel, A.M. Ribes, Mater. Sci. Eng. B3 (1989) 109.[279] K. Kanehori, Y. Ito, F. Kirino, K. Miyauchi, T. Kudo, Solid State Ionics 18–19 (1986) 818.[280] G. Meunier, R. Dormoy, A. Levasseur, Mater. Sci. Eng. B3 (1989) 19.[281] N.J. Dudney, J.B. Bates, R.A. Zuhr, S. Young, J.D. Robertson, H.P. Jun, S.A. Hackney, J. Electrochem. Soc. 146 (1999) 2455.[282] B.J. Neudecker, R.A. Zuhr, J.D. Robertson, J.B. Bates, J. Electrochem. Soc. 145 (1998) 4148.[283] B.J. Neudecker, R.A. Zuhr, J.D. Robertson, J.B. Bates, J. Electrochem. Soc. 145 (1998) 4160.[284] J.B. Bates, D. Lubben, N.J. Dudney, F.X. Hart, J. Electrochem. Soc. 142 (1995) L149.[285] B.J. Neudecker, R.A. Zuhr, J.B. Bates, J. Power Sources 81–82 (1999) 27.


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