prof. dr. s. kaskel fraunhofer institute for material and beam technology...
TRANSCRIPT
Recent Progress in Lithium-Sulfur-Batteries
Prof. Dr. S. Kaskel
Fraunhofer Institute for Material and Beam Technology IWS
AABC Europe 2017
January 31, 2017, Mainz
© Fraunhofer IWS
Overview
Progress in Lithium-Sulfur-Batteries
Introduction
Status of Li-S-technology
Technology development
Cathode chemistry
Anode materials
Separator
Role of electrolyte
Conclusion
© Fraunhofer IWS
ALT: 23.02.2016 Netzwert/BamoSa
© Fraunhofer IWS
500 1000 1500 2000
capacity (mAh/g)
1 V
2 V
3 V
4 V
5 V
Si/C-Komposite
Hardcarbon
Graphite
Li4Ti5O12
Li2S
Po
ten
tial
vs L
i/Li+
4000
Si Li
Cathode materials
Anode materials
inte
rcala
tio
n
Theor. specific cathode energy (Voltage x capacity)NMC: ca. 630 Wh/kgLi2S: 2.550 Wh/kg
CostsNMC: 23 €/kgSulfur: << 1 €/kg
Sulfur as next generation battery material
LiFePO4
LiCo1/3Ni1/3Mn1/3O2
Future potential:
high energy plus cost savings
Li+e-
Components of Li-S cell
Status of Li-S technology
Li-S-cell (330 Wh/kg)
Electrolyte
Separator
Lithium Metal
Current collector (+)
Polymer-Binder
Conductive additive
Sulfur/carbon
composite
© Fraunhofer IWS
ALT: 23.02.2016 Netzwert/BamoSa
© Fraunhofer IWS
Li-S-Battery: Introduction
Cathode properties
25 % cathode porosity (discharged)
47 % cathode porosity (charged)
Electrolyte excess for volume change
1000 mAh/g (Li2S), 2,1 V
65 wt-% Li2S content in cathode
Areal capacity: 5 mAh/cm2
Li-Anode: 100 % excess
Li+
Achievable energy density: Basic estimationson stack level
Li2S
S8
Status of Li-S technology
Energy density (charged state): 672 Wh/kg / 840 Wh/L
Examples of existing prototype cells
Status of Li-S technology
Li-S-cell (up to 330 Wh/kg)Li-S-cell (350 Wh/kg) Li-S-cell (up to 325 Wh/kg,
320 Wh/L)
Energy density is far from it‘s theoretical limit
Cycle life is limited to < 50 cycles for the high energy cells
However, applications are already there:
High Altitude Pseudo-Satellite (HAPS)
http://www.droneuniversities.com/drones/the-zephyr-high-altitude-pseudo-satellite-haps-aircraft-gets-lithium-sulfur-li-s-batteries/
Main cause of low cycle life:Lithium anode surface reactions
Degradation mechanisms
Depletion of org. electrolyte, cells dry out
Dendritic or porous structure causes shortcuts
Self-discharge and active material loss throughpolysulfide shuttle Anode Degradation
Status of Li-S technology
fresh Li
0.7 mm
cycled Li
0.7 mmLi+
Polysulfide Shuttle:Chemical reduction of dissolved PS at anode surface
LiNO3-Additive suppresses shuttle
© Fraunhofer IWS
Lithium Sulfur Batteries
Focus topic Li-S-Battery at Fraunhofer IWS, Dresden
Cathodes SeparatorsAnodes Electrolytes
Coating Laser-Cutting AssemblyMixing Tests
© Fraunhofer IWS
Cathode Materials Development
Chemical Surface and Battery Technology
Lee, J. T.; Zhao, Y.; Thieme, S.; Kim, H.; Oschatz, M.; Borchardt, L.; Magasinski, A.; Cho, W. I.; Kaskel, S.; Yushin, G.:
Advanced Materials 2013, 25(33), 4573-4579; M. Oschatz, S. Kaskel et al. Chem. Commun. 2013, 49(52), 5832-5834. M.
Oschatz, S. Kaskel et a. Advanced Energy Materials 2014, C. Hoffmann, S. Kaskel et al. ACS Nano, 2014.P. Strubel, S. Thieme et al., Adv. Funct. Mater., 2014, 10.1002/adfm.201402768
5 μm
Adam, Kaskel et al.
J. Mater. Chem. A, 2015, 3, 24103.
1 μm
Oschatz , Kaskel et al.
Angewandte Chemie 2012,51, 7577.
500 nmHoffmann, Kaskel et al.
ACS Nano 2014, 8, 12130.
100 nm
Borchardt et al.
Phys. Chem. Chem. Phys .2016,
100 nm100 nm
20 nm
Borchardt, Kaskel et al.
Carbon 2012, 50, 3987.
S. Dörfler, M. Hagen, S. Kaskel et al, Chem. Commun., 2012, 48, 4097.
Up to SA = 3000 m2/gPV = 3-4 cm3/g
2e–
Li+
Li+
I
Li+
Reducing PS Shuttle by Tailoring porous carbons
© Fraunhofer IWS
Hard carbons form stable SEI in ether electrolytes
4000 reversible cycles achieved
Recommended for cathode evaluation
Chemical Surface andBattery Technology
Anode materials development
Hard carbon
ether
molecule
lithium ion
SEI
J. Brückner, S. Kaskel et al., Adv. Funct. Mater., 2014 24 9, 1284–1289, DOI:10.1002/adfm.201302169
0 1000 2000 3000 40000
200
400
600
800
1000
1200
1400
1600
1 C
0.5 C
Dis
ch
arg
e c
ap
ac
ity
/ m
Ah
g-1 S
Cycle number
0.1 C
E/S = 12.00
20
40
60
80
100
CE
/ %
0 10 20 4080 4090 41000
400
800
1200
1600
S. Thieme et al., J. Mater. Chem. A 2015, 3, 3808 - 3820, DOI: 10.1039/C4TA06748G
Projected:up to 190 Wh/kg
© Fraunhofer IWS© Fraunhofer IWS
Nafion as cation-selective polymer coating to reduce polysulfide shuttle
Chemical Surface and Battery Technology
Ion-selective separator coatings
I. Bauer et al., J. Power Sources, 2014 251, 417–422, DOI:10.1016/j.jpowsour.2013.11.090
SEM Nafion@Celgard
1 µm1 µm
SEM Celgard 2500
Cathode mechanism in ether electrolyte requires dissolution ofpolysulfides
Most studies use >> 5 µl Electrolyte / mg S
S
Li2S
Poly-sulfides
Status of Li-S technology
The role of electrolyte
Saturated PS-solution in DME/DOL
DOL
DOL Gn (n ≥ 1); DME (n = 1)
LiNO3: SEI former LiTFSI: salt
© Fraunhofer IWS
Michael Kohl, 27. April 2015 14© Fraunhofer IWS
The role of LiNO3
Standard electrolyte additive in DME/DOL
LiNO3: Directing SEI formation in Li-S cells
Surface film: inorganic and organic species (LiNxOy, ROLi + ROCO2Li)
Compact and homogenous surface film formed with LiNO3
Enhanced stability of lithium anode and improved cycle life
S. Xiong et al. / Journal of Power Sources 246 (2014) 840-845
Electrolyte depletion and LiNO3 consumption is major cause for low cycle life
Excess electrolyte can enhance cycle life drastically
0 50 100 150 2000
200
400
600
800
1000
1200
1400
1600
E/S = 5.0
E/S = 6.5
E/S = 8.0
E/S = 12.0
Dis
ch
arg
e c
ap
acit
y / m
Ah
/g
Cycle number
50 cycles100 cycles
150 cycles
> 200 cycles
0
20
40
60
80
100
CE
/ %
C/10, LiTFSI/LiNO3 DME/DOL
S. Thieme et al., J. Mater. Chem. A, 2015, 3, 3808–3820, DOI: 10.1039/C4TA06748G
Electrolyte content determines cycle life
LiNO3 is consumed during cycling
M. Hagen et al. „Lithium–Sulfur Cells: The Gap between the State-of-the-Art and the Requirements for High Energy Battery Cells”DOI 10.1002/aenm.201401986
Most research papers useE/S >> 5 or not even mention it
E/S =Electrolyte Volume
Sulfur Mass
Inactive materials dominate the mass of Li-S cells
Li-S cathode Li-Ion cathode
Status of Li-S technology
Coating (NCA): 100 µm
Areal capacity: 5 mAhPorosity: 25 %Cell voltage: 3,7 V
Coating (S/C): 100 µm
Areal capacity: 5 mAhPorosity: 65 %Cell voltage: 2,1 V
76 wt-% active material17,5 wt-% active material
Weight distribution
~ C/7, 1.8 mgS/cm2,IWS electrolyte
IWS stacked
3.7 Ah pouch cell
Li-S pouch cell with ref. cathode, IWS elelctrolyte
3.4 µL/mgS vs. 2.5 µL/mgS
New electrolyte shifts the limit for minimum electrolyte content!
real capacity ~ 2.5 Ah
36 h rest
ref. cathode
3.4 µL/mgS
2.5 µL/mgS
12 h rest
real capacity ~ 2.7 Ah
0 20 40 60 80 1000
400
800
1200
1600
Cycle
Cap
acit
y / m
Ah
/g
E
44.4 %
Li
S
Li
S
E
37.7 %
3.4 µL/mgS 2.5 µL/mgS
Patent pending
New Electrolytes with low PS
solubility (without LiNO3)
Reducing electrolyte content
1.5M LiTFSI / 0.25M LiNO3
in DME/DOLIWS electrolyte
Work in progress
Li anode, 89 cycles, DME/DOL
50 µm
50 µm
Li anode, 100 cycles, new El.
Electrolytes with low PS solubility
Reduced anode degradation Improved safety
Smooth Lithium deposition
Low flammability
Work in progress
Safety of LiS-Cells
Safety Tests: Lithium-Sulfur Pouch Cell
(IWS electrolyte)
▪ Standardized Tests by SGS Germany GmbH (München)
▪ Thermal Stability (130 °C), Overcharge,Simulated Internal Short Circuit, Nail Penetration,Short Circuit
▪ no „Thermal Runaway“
▪ max. Hazard Level (according to EUCAR): HL 3
▪ Significantly improved safety of Li-S-Cells, as compared to Li-Ion-Cells with same cell format
▪ Li-Metal burning at T > 190 °C;only if externally heated
Li-metal burning
Cell after Nail Penetration
Status of Li-S technology
Li-S-cells reach 350 Wh/kg lightest accumulator today
Volumetric energy density currently lower than Li-Ion
Cycle life in high energy cells is limited today to 50-100 cycles
Available cells not yet suitable for automotive
Potential for step-change
Anode
Cathode
Electrolyte
Separator
Niche markets are growing and may expand
Conclusions
Related projects
Thanks to co-workers, partners and funding agencies!
Li-S-Battery-Team at IWS
Acknowledgements
6th Workshop »Lithium-Sulfur Batteries«
201420132012 2015
Annual conference in Dresden
More than 150 participants from industry and academia
Save the date: November 6–7, 2017
20162016
Prof. Dr. S. Kaskel
Dr. Holger Althues
Fraunhofer IWSWinterbergstraße 2801277 Dresden, Germany
Phone +49 351 83391-3476 Fax +49 351 83391-3300E-Mail [email protected]
www.iws.fraunhofer.de
Thank you for your attention!
© Fraunhofer IWS
Status and Potential of Li-S-Technology
SoA (LIB) SoA (Sion-Li-
S)
Prognosis
(Li-S) – GM*
Prognosis
(Li-S)BMW**
Prognosis
(Li-S) - IWS
Grav. Energy density
(Cell)
140 - 250
Wh/kg
350
Wh/kg
550
Wh/kg
419
Wh/kg
490
Wh/kg
Vol. Energy density
(Cell)
280 - 670
Wh/L
320
Wh/L
620
Wh/L
644
Wh/L
685
Wh/L
Panasonic 18650 (Tesla):
243 Wh/kg Sion-Power:
350 Wh/kg (cell)260 Wh/kg (pack)
Li-Ion-Cells (examples) Li-S-cells
LG Pouch-Cell (Opel Ampera):
140 Wh/kg
* T. Greszler, GM Beyond Lithium Ion 5, Berkeley, CA 2012 ** Dr. P. Oberhumer, BMW Li-S-Battery-Workshop 2013, Dresden
Oxis-Energy: -5 – 80°CULC: 300 Wh/kg, 200 Wh/LDemonstrated: 400 Wh/kgLLC: 180 Wh/kg, 170 Wh/L
Li-S-Battery SeminarIntroduction
ULC = Ultralight Cell
LLC = Long life cell