Ramasamy Kulandaivel Saminathan

Lead Acid Battery.Attacking SulphatePassivation and Cyclability Problems

Research Paper(postgraduate)

Natural Science

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Ramasamy Kulandaivel Saminathan

Lead Acid Battery. Attacking Sulphate Passivation andCyclability Problems

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LEAD ACID BATTERY – ATTACKING SULPHATE PASSIVATION AND

CYCLABILITY PROBLEMS

RAMASAMY K. SAMINATHAN

2

3

TABLE OF CONTENTS

INTRODUCTION ........................................................................................ 9

1.1 Timeline of Battery History: ..............................................................13

1.2. Characteristics of Some batteries and achievable performance: .....15

1.3. Lead-acid battery ..............................................................................16

1.3.1. Advantages of lead-acid system ....................................................16

1.3.2. Technical developments in Lead-acid battery: ..............................17

1.3.3. Charging and Discharging Reactions: ............................................19

1.3.4. Theoretical voltage and capacity: ..................................................20

1.3.5. Capacity of a cell: ...........................................................................20

1.3.6. Thickness of the plates and capacity: ............................................23

1.3.7. Rate of Discharge ...........................................................................24

1.3.8. Electrolyte Temperature ...............................................................25

1.3.9. Effect of Concentration of the electrolyte: ....................................25

1.3.10. Manufacture of Lead-acid battery ...............................................26

1.3.11. Flow chart for the Manufacture of flooded lead-acid battery ....27 1.4. Classification of Lead-acid battery: ......................................................................... 28

1.4.1. SLI batteries: ..................................................................................28

1.4.2. Stationary batteries: ......................................................................28

1.4.3. Motive power batteries:................................................................28

1.4.4. Special purpose batteries: .............................................................28

1.4.5. Valve Regulated Lead-acid Batteries (VRLA) .................................29

1.5. Failures in Lead-acid batteries: .........................................................29

1.5.1. Sulphation is due to the following reasons: ..................................29

1.5.2. Shedding of the positive mass: ......................................................30

4

1.5.3. Destruction of the positive grids: ..................................................30

1.5.4. Defects in the negative mass: ........................................................31 1.6. CHARGING OF LEAD-ACID BATTERY ........................................................................ 32

1.6.1. Constant-current charging (CC) .....................................................32

1.6.2. Constant-Voltage charging (CV).....................................................33

1.6.3. Taper charging ...............................................................................33

1.6.4. Pulse charging ................................................................................33

1.6.5. Trickle Charging .............................................................................33

1.6.6. Float Charging ................................................................................34

1.6.7. Battery charger should have the following Characteristics ...........34 1.7. GRID MATERIALS: .................................................................................................... 34

1.7.1. Grid alloy properties ......................................................................34

1.7.2. Ease of fabrication .........................................................................35

1.7.3. Mechanical strength ......................................................................35

1.7.4. Creep strength ...............................................................................35

1.7.5. Corrosion resistance ......................................................................36

1.7.6. Conductivity ...................................................................................36

1.7.7. Compatibility with active material ................................................36

1.7.8. High hydrogen and oxygen over potential ....................................37

1.7.9. cost effective .................................................................................37

1.7.10. Various Types OF Grid alloys: ......................................................37

1.7.11. Beneficial elements .....................................................................37

1.7.12. Self discharge behaviour .............................................................39

1.7.13. Detrimental elements..................................................................39 1.8. GRID production methods: ...................................................................................... 39

1.9. VARIOUS TYPES OF GRIDS: ..................................................................................... 41

1. M C B-GRID ................................................................................................................. 41

5

2. BOX –NEGATIVE PLATE ............................................................................................... 41

3. MONCHESTER GRID .................................................................................................... 41

4. IRONCLAD GRID .......................................................................................................... 41

6. EXPERIMENTAL BATTERY GRID .................................................................................. 41

References ...................................................................................................................... 42

LITERATURE SURVEY AND SCOPE OF THE WORK ........................................................... 46

2.1 LITERATURE SURVEY: .........................................................................46 REFERENCES ................................................................................................................... 64

2.2. SCOPE OF THE WORK............................................................................................... 67

EXPERIMENTAL DETAILS................................................................................................. 70

3.1. Chemicals and materials used ..........................................................70

3.2. Weight loss Studies ..........................................................................71

3.3. Cyclic Voltammetry ..........................................................................72

3.4. Impedance measurements ...............................................................75

3.5. Anodic polarisation studies ..............................................................76

3.6. CHRONO AMPEROMETRIC STUDIES .................................................76

3.7. XRD ...................................................................................................77

3.8. Scanning Electron Microscope..........................................................77

3.9. Charge acceptance studies. ..............................................................78

3.10. cycle life test. ..................................................................................78

1. cycle life test with low capacity battery ..............................................78

2. Heavy load endorsement test .............................................................79 REFERENCES : ................................................................................................................. 80

6

RESULTS & DISCUSSION.................................................................................................. 81

4.1. WEIGHT LOSS STUDIES .....................................................................82

4.1.1. Dense Lead sulphate removal from the positive plate. ................82

4.1.2. Dense lead sulphate removal from the negative plate .................87 SUMMARY:..................................................................................................................... 88

4.2. Cyclic Voltammeteric Studies ........................................................92

4.2.1 .Cyclic Voltammetric Studies of the Positive Plate. ........................92

CV STUDIES in electrolyte containing different acetates. .......................96 CV STUDIES for the mixture of boric acid and ACETATES.............................................. 112

CV STUDIES for the mixture of Phosphoric acid and ACETATES. ...........128

Electrochemical Kinetic Parameters for the formation of lead sulphate in the absence and presence of sodium acetate and Phosphoric acid

combined additive. ................................................................................145

4.2.2. Cyclic VOLTAMMETRIC STUDIES of the negative PLATE. .............148

CV STUDIES IN ELECTROLYTE CONTAINING DIFFERENT ACETATES. ......151

CV STUDIES FOR THE MIXTURE OF BORIC ACID AND ACETATES. ..........165

CV STUDIES FOR THE MIXTURE OF PHOSPHORIC ACID AND ACETATES. ...............................................................................................................181

ELECTROCHEMICAL KINETIC PARAMETERS FOR THE FORMATION OF LEAD SULPHATE IN THE ABSENCE AND PRESENCE OF SODIUM ACETATE

AND PHOSPHORIC ACID COMBINED ADDITIVE. ....................................197 SUMMARY:................................................................................................................... 198

4.3. ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY STUDIES ..........202

4.3.1. EIS STUDIES on active / passivated POSITIVE PLATES in the absence and presence of additives. ......................................................202

4.3.2. EIS STUDIES on active / passivated NEGATIVE PLATES in the absence and presence of additives. ......................................................212

7

4.4. Studies on the passivation phenomena of lead (negative electrode) in the BATTERY ELECTROLYTE. ..............................................................221

4.5. Self-Corrosion of the electrodes in the battery electrolytes ..........225

4.6. Studies on the electro formation of Lead Sulphate with and with out the additives. .........................................................................................228

4.7. SEM STUDIES. .................................................................................236

4.8. X-ray diffraction studies. ................................................................243 4.9 CHARGE ACCEPTANCE STUDIES. ............................................................................. 246

4.1 CYCLE LIFE TEST ...................................................................................................... 248

4.10.1. Slow rate cycle life test with low capacity Battery. ...................248 4.10.2. HEAVY LOAD ENDORSEMENT TEST WITH HEAVY DUTY BATTERY .................... 251

REFERENCES: ................................................................................................................ 253 CONCLUSIONS .............................................................................................................. 257

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9

CHAPTER-1

INTRODUCTION

A battery is defined as an electrical storage device, which is

able to convert the stored chemical energy into work of an electrical

nature. The word battery was originally applied by Benjamin Franklin

as a collective term to describe the apparatus obtained when several

leyden jar capacitors were connected together. When the batteries

were first invented, they had seen as merely laboratory curiosities.

Faraday distinguished electrodes into anode and cathode. These

were derived from the Greek words ‘way up’ and ‘going down’

respectively as Faraday supposed that the anode releases the

electrons which are consumed by the cathode.

It was just 200 years since the invention of the first battery; this

has been ascribed to Alessandro Volta (1745-1827), Professor of

Natural Philosophy (physics) at Pavia University, Italy. His name is

commemorated at all time by the unit of electrical potential, the volt.

Volta’s famous experiment, described in a letter to the Royal Society

of London in 1800, involved the assembly of a pile of alternate silver

(or brass or copper) and zinc (or tin) discs, with each pair of dissimilar

metals separated from the next by a piece of cloth which was

saturated with brine. One end of the pile was terminated in a silver

disc and the other in a zinc disc, and a continuous current of electricity

10

was produced as soon as a wire conductor connected the two. This

was the first galvanic or primary battery and became known as

‘Volta’s pile’. Batteries have come a long way in 200 years!

The next significant step in the development of batteries was the

invention of the ‘Daniell cell’ by John Daniell (1790 -1845), Professor

of Chemistry at King’s College, London. In 1836, he took a copper

vessel filled with copper sulfate solution and Zinc rod with zinc

sulphate solution separated by gullet of an ox. This constituted a so

called ‘cell’. Discharge of the cell caused the zinc electrode to dissolve

and copper to be deposited at the positive electrode. The cell

produced a voltage of 1.1 V.

This was possibly the first practical galvanic cell to give a

continuous current of useful magnitude. Further modifications (Fig1.1a)

included the use of porous ceramic pots (‘separators’) instead of

animal membranes, substitution of sulfuric acid by zinc or magnesium

sulfate, and the development of multi-cell batteries. Daniell cells were

adopted by commercial telegraphic systems following a rapid

expansion of such services in the early 1850s.

11

A subsequent major advance was made by the French chemist

Georges Leclanche´ (1839-1882) who, in 1866, invented the primary

cell, which bears his name. This cell consists of a zinc rod as the

negative electrode and a carbon rod as the positive electrode, both

immersed in a solution of ammonium chloride contained in a glass jar.

The positive electrode was housed in an inner porous

ceramic pot and packed around with a mixture of powdered

manganese dioxide and carbon. The cell, which has been extensively

developed ever since, gives a voltage of 1.5 V. A major advance took

place in the 19th century when the idea of using a zinc cane as both

container and electrode was patented and came into general use.

Before the invention of these galvanic cells, the only electricity known

Fig 1.1. a) Schematic of Plante`s lead acid cell b) early illustration of a battery of three Plante`s lead acid cell [1]

12

and available was static electricity, as produced by friction between

dissimilar materials or in thunderstorms.

The first effective demonstration of a secondary (rechargeable)

cell was given in 1859 by the French chemist Gaston Plante´ (1834-

1889). This cell consisted of two concentric spirals of lead sheet,

separated by porous cloth, immersed in dilute sulphuric acid within a

cylindrical glass vessel .The ‘lead-acid battery’ thus constructed gave

an output of 2 V, but very little current was initially gained because of

the low surface area of the plates. By a series of discharges and

charges, the chemical reactions at the surface of the plates resulted in

the gradual build-up of deposits of higher surface area and the current

was progressively improved. This became known as the ‘formation

process’, a term still used today in the initial charging of lead-acid

batteries. In March 1860, Plante´ presented a battery of ten cells (20

V) to the French Academy of Sciences in Paris; an illustration of an

early battery of Plante´ cells is shown in Figure 1.1b.

An important advancement in the technology of the Lead-Acid

battery was achieved by the French chemical engineer Camille Faure´

(1840-1898) who, in 1881, showed the change in level of electrical

charge, or the ‘capacity’, of the system could be greatly increased by

coating the lead plates with a paste of lead dioxide and sulphuric acid.

This process also reduced the time required for plate formation from

months to hours, and thus became part of the basic technology of the

lead-acid battery industry.

13

an array of charged glass plates.

1791 Luigi Galvani Experiment

1800 Alessandro Volta invented the voltaic pile and discovered the

first practical method of generating electricity.

1836 John F. Daniel invented the Daniel Cell that used two

electrolytes

1839 William Robert Grove developed the first fuel cell.

1860 Gaston Plante developed the first practical storage lead-acid

battery.

The most important event in the history of Lead-acid battery was the invention of the electric self-starter by kettering in 1912. As a result, the battery market has grown with the growth of the automobile market throughout the last century.

1.1. Timeline of Battery History: 1748 Benjamin Franklin first coined the term "battery" to describe

Fig 1.2. a) Schematic of Plante`s lead acid cell b) early illustration of a battery of nine Plante`s lead acid cell [1]

14

1866 Georges Leclanche patented the carbon-zinc wet cell

battery.

1868 Twenty thousand of Georges Leclanche's cells were used

with telegraph

1881 J.A. Thiebaut patented the first battery with both the negative

electrode and porous pot placed in a zinc cup.

1881 Carl Gassner invented the first commercially successful dry

cell battery

1899 Waldmar Jungner invented the first nickel-cadmium

rechargeable battery.

1903 Thomas Alva Edison invented the alkaline storage battery.

1927 Andre, Zinc-Silver oxide cells

1928 Pflerder, spoon, Gimelin,& Ackerman Sintered electrode

1935 Haring & Thomas, Lead-calcium alloy

1949 Lew Urry invented the small alkaline battery.

1950 Ruben, sealed Zinc- Mercuric oxide cell

1954 Gerald Pearson, Calvin Fuller and Daryl Chapin - first solar

battery.

1956 Bacon, alkaline fuel cell

1966 Kummer & Weber Sodium-Sulphur battery

1970 Tobias aprotic solvent research

1980 Sealed lead-acid batteries become common

To

present

VARLA, Li-Ion Batteries successfully commercialised

15

A number of primary, secondary, reserve and fuel cells are also

developed. Each one has special features and they have their own

limitations. Performance and characteristic of few systems are

presented in the following table.

1.2. Characteristics of Some batteries and achievable performance:

Lead -

Acid

Ni-

Cd Zn-air Ni-Fe Ni-Zn Zn-Cl2 Na-S Li-TiS2 Li-S

Electrolyte H2SO4 KOH KOH KOH KOH ZnCl2 Al2O3 Various Licl /

LiKI

OCV (Volt per

cell) 2.05 1.35 1.65 1.37 1.71 2.12 2.1-1.8 2.3

1.9-

1.4

Life cycles

(80%) DOD 500 2000 1000 2000 350 250 2000 250 200

Energy

Efficiency (%) 75 70 55 60 75 65 75 --- 75

Specific Energy

(Wh Kg-1) (1h

rate)

24 28 80 40 70 120 120 --- 140

Wh Kg-1 5h rate 40 30 100 55 75 150 140 100 ---

Energy density

(Wh dm-3) (1h

rate)

70 60 80 100 140 180 170 330 ---

16

1.3. Lead-acid battery

Lead - acid battery is the workhorse of the rechargeable battery

systems. It is the single most used battery worldwide. Although many

new systems may challenge its position, its reliability, low cost and

good operational life, can’t so easily be substituted. The first secondary battery (Lead-acid battery) was discovered and

developed by Gaston plants [1-5] in 1859. Since then enormous developments

have been taken place in the science and technology of the battery system. A

number of references are available dealing with Lead-acid battery [6-20]. In

principle, the Lead-acid battery consists of two electrodes immersed in a common

electrolyte. The characteristic feature of such a cell is the conversion of electron

conduction into ionic conduction at the phase boundary of the

electrode/electrolyte. This change in conductivity is established by the

electrochemical reaction, i.e., a chemical reaction accompanied with the

exchange of electric charge.

1.3.1. Advantages of lead-acid system Lead-acid battery is technically well-established electrochemical device

and is produced in quantities for different applications. Its production and use

continues to grow. The most attractiveness of the Lead-acid battery is due to the

following reasons.

Well established technology of production.

• Popular low-cost secondary battery.

• Capable of manufacturing with simple methods.

• Manufactured in capacity ranges from smaller than 1 Ah to 1000 Ah.

• Good high-rate performance-suitable for engine starting.

• Good low and high temperature performance

• Easy state-of-charge indication.

• Electrically efficient .

17

1.3.2. Technical developments in Lead-acid battery: Year Precursor Achievements

1860 Raymond Gaston

Plante

First practical Lead-acid battery corroded Pb foil to form

active material.

1881 Faure Coated lead foils with PbO2 – H2SO4 paste for positive

electrode to increase capacity.

1881 Sellon Pb – Sb grid alloy.

1881 Volkinar Perforated lead plates to provide pockets for support of

oxide.

1882 Brush Mechanically bonded PbO2 to lead plates.

1882 Gladstone and

Tribe

Double sulphate theory of reaction in Lead-acid battery.

PbO3 + Pb + 2H2SO4 2PbSO4 + 2H2O

1883 Tudor Pasted mixture of lead oxides on a grid

1886 Lucas Formed Lead plates in solutions of chlorates and per

chlorates.

1890 Phillipart Early tubular construction individual rings.

1890 Woodward Early tubular construction.

1935 Haring and

Thomas

Pb – Ca alloy grids.

1935 Harmer and

Harned

Experimental proof of double sulphate theory.

1956 Bode and Voss

Ruetschi and

Cahan J.Burbank

Classification of properties of two crystalline forms of

PbO2.

1990 To present Expanded metal grid technology composite plastic / metal

grids sealed and maintenance – free LAB. Glass fiber and

improved seperators high energy density batteries.

VRLA with AGM Seperators

18

The electrochemical reactions specify the most important parameters of the

cell. The cell voltage is determined by chemical affinity of the reacting substances

and capacity is defined by the amount of electrode material that can be converted.

The reactions taking place in the Lead-acid battery are given below.

Positive Electrode:

PbO2 + 3H+ + HSO4- + 2e - PbSO4 + 2H2O -- (1)

E0 = + 1.690 V

Negative Electrode:

Pb + HSO4- PbSO4 + H+ + 2e- -- (2)

E0 = - 0.350V

Overall reaction:

Pb + PbO2 + 2HSO4- + 2H+ 2PbSO4 + 2H2O -- (3)

E0 = + 2.04V

Equation (1) and (2) represents reactions during discharge, where lead dioxide is

reduced to lead sulphate at the positive electrode, while metallic lead is oxidized

at the negative electrode. Reversal of the current reverses (1) and (2), and

recharges the cell.

19

1.3.3. Charging and Discharging Reactions:

NEGATIVE PLATE ELECTROLYTE

POSITIVE PLATE

DISCHARGE REACTIONS

ORIGINAL ACTIVE MATERIAL

Pb

2H2SO4 , 2H20

PbO2

IONISATION PROCESS

SO4 2- , SO4

2-, 4H+

4OH- , Pb 4+

CURRENT –PRODUCING PROCESS

2 e - + Pb 2+

Pb 2+ - 2e-

FINAL PRODUCTS OF DISCHARGE

PbSO4

4H2O

2H20 2H2O

PbSO4

CHARGE REACTIONS

FINAL PRODUCTS OF DISCHARGE

PbSO4

4H2O

PbSO4

IONISATION PROCESS

Pb2+, SO42-

2H+, 4 OH- , 2H+

S042-, Pb2+

CURRENT – CONSUMBTION PROCESS

2e-

2e- Pb 4+

ORIGINAL ACTIVE MATERIAL

Pb

2H20

H2SO4 H2SO4

PbO2

20

1.3.4. Theoretical voltage and capacity: To calculate the equilibrium cell voltage, the change in free energy (ΔG) is

used, which is derived as the difference of the standard free energies of the

substance involved in the reaction. For equation (3) this difference turns out to be

ΔG = -372.5 KJ mole-1

and the standard equilibrium cell voltage (emf) is

E0 = 372.5 *1000 / 2*96500 = 1.930V

Since, free energy depends upon concentration of electrolyte, the equilibrium cell

voltage changes with the concentration or activity of the reacting species except

those present in solid state (activity = 1) according to the Nernst equation,

E = E0 + RT/ nF ln aH + aHSO4-

aH2O

where E0 represents the standard equilibrium cell voltage, ‘a’ the activity (moles/

litre). The Lead-acid cell can be represented as follows.

(-) Pb / PbSO4 / H2SO4 / PbO2 / PbSO4 (+)

The electric potential difference is equal in sign and magnitude to the electrode

potential of a metallic conductor attached to the right hand side electrode minus

that of an identical lead on the left.

Ecell = Eright - Eleft

= 1690 – (-350) mV

= 2040 mV

1.3.5. Capacity of a cell: Specific capacity (k) is defined as the ampere hours obtainable from a unit

of the active material e.g. Ahkg-1. A related parameter is the coefficient of

utilization of active material .

21

The current density is expressed as

c.d (Adm-2 or Am-2).

The area expressed may be either the apparent geometric area (reckoned

for the two sides of the plates) or the BET surface area, sometimes the c.d. is

expressed as amperes per Kg of the active materials.

The capacity (C) is usually expressed in Ah (3.6 x 103 Coulombs)

specifying the flow of current per unit area in number of hours eg. C20 = 60 Ah

implies that the battery can be discharged at 3 amperes over a period of 20 hours

and it can deliver the declared capacity of 60 Ah before it reaches its end voltage

(also called cut off voltage) usually about 1.75 to 1.70 V per cell. Sometimes the

batteries are tested for their output in terms of unit power, energy for a unit time,

watts.

In the electrochemical power source, the full utilization of the active

material has not been realized. Thus in declaring the capacity, two types are

distinguished, namely the theoretical capacity CTh and the practical capacity (C).

The practical capacity depends on several parameters like discharge rate, Cell

design, etc., and hence has to be declared very specifically under a given set of

conditions.

The theoretical capacity is determined from the reaction according to

Faraday’s laws and is equivalent to ZF Coulombs for one mole of reactants (here

PbO2, Pb and H2SO4). The effective capacity equal to Current x Time is

determined by discharging the battery at a definite rate over a period of time till it

reaches the cut – off voltage.

From equation (3) it can be readily estimated that the theoretical amounts of the

reacting materials required for 1 Ah are

22

207.2 + 239.2 + 196g = 642.4g

For 2 x 96500 C or 2 x 26.80 Ah = 53.6 Ah.

239.2 The weight of PbO2 for 1Ah is equal to =

53.6 = 4.46 g.

Similarly the weight of PbSO4 1 Ah is = 5.65 g

(Formed during discharge and consumed during charge )

Likewise the weight of Pb and H2SO4 required per Ah will be 3.86 and

3.66g respectively. Assuming the discharge voltage to be 2.0V, Specific energy

per unit weight will be

= 53.60 x 2.0 / 0.6424

= 167 Wh / Kg

The value is only by the weight of the reacting substances. The inclusion of

the weight of the inactive components such as grids, containers, and covers,

poles and separators reduces the practical energy density to values as low as 30-

40 WhKg-1 (at 5- hour rate of discharge). Since the reaction product on both

plates is PbSO4, which is a poor conductor of electricity, the realization of the

theoretical energy density is made still more difficult.

Capacity of the battery depends on various factors such as the amount of

active material, porosity of the plate, thickness of the plate, rate of discharge,

electrolyte temperature and concentration of the electrolyte.

The theoretical requirements per Ah of capacity of the active materials are

given below