2. What are Batteries, Fuel Cells, and Supercapacitors, Chem Rev, 2004, 104, 4245, Martin Winter and
Ralph J. Brodd
Battery types:
Primary Battery: Non reversible chemical reactions (no recharge)
Secondary Battery: Rechargeable
Common characteristics
Electrode
complex coposite of powders of active material and conductive
diluent, polymer matrix to bind the mix
typically 30% porosity, with complex surface throughout the material
allows current production to be uniform in the structure
Current distribution
primary – cell geometry
secondary – production sites within the porous electrode
parameters affecting the secondarycurrent distribution are
conductivity of diluent (matrix)
electrolyte conductivity,
exchange current
diffusion characteristics of reactants and products
total current flow
porosity, pore size, and tortuosisity
3. What are Batteries, Fuel Cells, and Supercapacitors, Chem Rev, 2004, 104, 4245, Martin Winter and
Ralph J. Brodd
We will briefly look at: Lead and Lithium insertion
4. What are Batteries, Fuel Cells, and Supercapacitors, Chem Rev, 2004, 104, 4245, Martin Winter and
Ralph J. Brodd
5. What are Batteries, Fuel Cells, and Supercapacitors, Chem Rev, 2004, 104, 4245, Martin Winter and
Ralph J. Brodd
Require very good conductivity
Throughout the system
Which tends to lower the energy
Content of the system
In the lead acid system a significant amount
Of the weight Is in the grids required
To hold the paste
6. Equivalent Circuit for a Battery
Terminals, Resistance
To current flow of, RM
External Resistance, Rext
Internal Discharge
Rate (e.t.)
Capacitance of
electrode
Resistance of
electrolyte
7.
8. ad Acid Battery
Basic requirements for a battery
1. chemical energy stored near the electrode ( if too far away current will
be controlled by time to get to electrode)
2. The chemical form coating the electrode must allow ion transport, or
better yet, electronic conduction
3. The chemical form of the energy must be mechanically robust
4. The chemical form of the energy should generate a large voltage
9. Fitch lead book Support grids
The capacity of the battery depends on
The type of material present.
10. PbO e H SO PbSO H
s aq s
2 2 4
2 2
, ,
One possible mechanism:. simultaneous dissolution of PbO2 and introduction of 2e
Requires electronic conductivity of PbO2 and pore space for motion of wat
1. Add e, H+ and OH- to PbO2
2. Add 2nd e to reduce valence of Pb
3. Add 3rd e to reduce valence while r
4. PbO is more soluble than PbO2 so
5. Initiate formation of PbSO4, nuclea
6. PbSO4 structure is rhombic which
7. Therefore need to control the alletr
11. Beta PbO2 is formed under acid and can be compressed to shorten bonds
overlap induces semiconductor behavior which increases the performance
Of the battery
Alpha forms when Pb metal
Corrodes – reduces lifetime of
Battery, is more compressible.
Add antiomony
To drive reaction
To beta phase
12. Lead Acid battery
a.What is the potential associated with a lead
acid battery with the overall reaction:
at the following concentration:
[H2SO4] = 4.5 M
Pb PbO H HSO PbSO H O
s s aq aq s
2 4 2
2 2 2 2
, ,
13. -0.35
Vo
1.69
-(-0.35)
2.04
1.69
PbO H e SO PbSO H O
s aq aq s
2
2
4 2
4 2 2
, ,
PbSO e Pb SO
s s aq
4
2
2
,
PbO H e SO PbSO H O
s aq aq s
2
2
4 2
4 2 2
, ,
Pb SO PbSO e
s aq s
2
4 2
,
Pb PbO H HSO PbSO H O
s s aq aq s
2 4 2
2 2 2 2
, ,
V V
n
Q Q
o
00592
2 04
00592
2
.
log .
.
log
14. Lead Acid battery energy
Pb PbO H HSO PbSO H O
s s aq aq s
2 4 2
2 2 2 2
, ,
V Q
PbSO H O
Pb PbO HSO H O
s
s s aq
2 04
00592
2
2 04
00592
2
4
2
2
2
3
2
.
.
log .
.
log
,
V Q
HSO H O
aq
2 04
0 0592
2
2 04
0 0592
2
1
2
3
2
.
.
log .
.
log
V
2 04
00592
2
1
45 45
2 2
.
.
log
. .
V
2 04 00296 2 6 211
. . . .
15. c. What is the free energy associated with the
lead acid battery?
nFV G RT K
o
ln
G 2 96 485 2 04
, .
G kJ
3936
.
16. PbO H SO e PbSO H O
solid aqueous aqueous solid
2 4
2
4 2
4 2 2
, , ,
Dendrites are
Good: porous (makes more
Of possible energy available)
Bad: fragile, break and fall
from underlying
electrode
= NO CURRENT
e
No e
17. The type of structure that forms depends upon the rate of crystallization which
Depends upon rate of reaction which depends upon:
Loss/production of products (current)
Which depends also upon the rate constant (potential dependent)
18. One way to “image” the various processes described above is by an
Equivalent Circuit
19. In a simplified system
IDisch e
arg
Rext
Rapparent ernal resis ce
int tan IDisch e
arg
V I R R
t d ext app
0
V I R
Disch e D ext
arg
V I R
remaining D app
As the battery is discharged the discharge voltage is the
Difference between what we started with and the remaining
Voltage in the battery
V V I R
Disch e t D App
arg
0
20. Lead acid batteries can be valve regulated to control the pressure associated
With
1.29 V
1.38 V
No pressure
pressurized
Lower CT resistance
Under pressure
Suggests higher
Degree of interparticle
Contact under pressure
21. Insulating layer which can conduct only protons and lead
Solubility
Diffusion
Et at conducting PbO2
24. Solubility
Diffusion
Et at conducting PbO2
Different magnitude of discharge
Changes the solubility and proton conc
As well as the conductivity of the film
25.
26.
27. IDisch e
arg
Rext
Rapparent ernal resis ce
int tan IDisch e
arg
V I R R
t d ext app
0
V I R
Disch e D ext
arg
V I R
remaining D app
P V I
D D
P I R I I R
D ext D D ext
2
P
V R
R R
ext
app ext
0
2
2
V
R R
I
t
ext app
d
0
Based on V. S. Bagotsky text, Fundamentals of Electrochemistry
28. V V I R
Disch e t D App
arg
0
P
V R
R R
ext
app ext
0
2
2
0
0.5
1
1.5
2
2.5
0 0.5 1 1.5 2 2.5
Current Density
V
0
0.2
0.4
0.6
0.8
1
1.2
P
For the simplified model
30. High charge transfer
Resistance due to insulating
PbSO4 layer
Charge transfer resistance
Decreases due formation of more porous PbO2
Small diameter
Of impedance
Circle here indic
The fast et kine
O2 reaction.
Increasing
Charge transfer
Resistance due
To layer of PbSO4
31. Reaction Vo
Li++e Li -3.0
K+ + e K -2.95
Na+ + e Na -2.71
NCl3_4H+ + 6e 3Cl- + NH4
+ -1.37
2H2O + 2e H2 + 2OH- -0.828
Fe2+ + 2e Fe -0.44
Pb2+ + 2e Pb -0.13
2H+ + 2e H2(gas) 0
N2(g) + 8H+ + 6e 2NH4
+ 0.275
Cu2+ + 2e Cu 0.34
O2 + 2H2O + 4e 4OH- 0.40
O2 + 2H+ + 2e H2O2 0.68
Ag+ + e Ag 0.799
NO3
- + 4H+ + 3e NO(g) +2H2O 0.957
Br2 + 2e 2Br- 1.09
2NO3
- + 12H+ + 10e N2(g) +6H2O 1.246
Cl2
+ 2e 2Cl- 1.36
Au+ + e Au 1.83
F2 + 2e 2F- 2.87
7g/mol
207g/mol
32.
33. Lithium oxidation proceeds a little too
uncontrollably
Lithium reduction does not not result
in good attachment back to the lithium
metal
Forms dendrites which can grow to
Short circuit
C e Li LiC
6 6
1
Lithium intercalated in graphite is close
to metallic, formal potential differs by
only 0.1 to .3 V = -2.7 to -2.9V
34. Anode –
Solid electroactive metal salt
(Can change overall charge so that it can electrostatically stabilize & localize Li+
Potential should be very positive (far from -2.5 V for Li/C reaction
Solid should conduct charge throughout
Solid should allow ion motion
Should have fast kinetics (open and porous)
Should be stable (does not convert to alleotropes)
Low cost
Environmentally benign
M X M X e
x
m
z
x
x
m
z
x
1
M. Stanley Whittingham, Lithium Batteries and Cathode Materials, Chem. Rev. 2004, 104, 4271-4301
M X Li M X Li
x
m
z
x
x
m
z
x
fast
M X Li M X Li e
x
m
z
x
x
m
z
x
fast
35. M. Stanley Whittingham, Lithium Batteries and Cathode Materials, Chem. Rev. 2004, 104, 4271-4301
LiTiS2 LiVSe2 LiCoO2
LiNiO2
Group I
Group II
V O
2 5 MoO3
Group III
Spinels
Mn O
2 4
36. M. Stanley Whittingham, Lithium Batteries and Cathode Materials, Chem. Rev. 2004, 104, 4271-4301
LiTiS2
Smooth galvanostatic curve indicates
That there are no sites nucleating
Alleotropes of the compound.
Allotropes would alter the structure,
Porosity, and the ease of intercalation,
Potential, and conductivity
Went to market
In the late 1970s
Single phase
Light weight
Conducting, but not
Reactive (oxidised or reduced)
Li ion intercalates in response to double layer charging
37. M. Stanley Whittingham, Lithium Batteries and Cathode Materials, Chem. Rev. 2004, 104, 4271-4301
LiVSe2
Indicates various crystal forms
V Se xLi xe Li V Se
IV
x
IV x
2 2
Li V Se x Li x e LiV Se
x
IV x III
2 2
1 1
LiV Se Li e Li V Se
III II
2 2 2
Lithium ion inserts in response
To reduction of vanadium
Different phases of VSe2 have similar structures
So the distortion is not great
octahedral
2nd is tetrahedral
38. M. Stanley Whittingham, Lithium Batteries and Cathode Materials, Chem. Rev. 2004, 104, 4271-4301
Group II
V O
2 5 MoO3
39. Major phase changes in LixV2O5
(x<0.01) is well ordered
Є ( 0.35<x<0.7)is more puckered
(x=1) shifting of layers
(x>1) results in permanent structural change
ω (x>>1) is a rock salt form
41. M. Stanley Whittingham, Lithium Batteries and Cathode Materials, Chem. Rev. 2004, 104, 4271-4301
Group III
Spinels
Mn O
2 4
These materials have a major change in
Unit cell dimensions when Mn changes
Oxidation state (see B). Need to keep the
Lattice parameter less than 8.23 A for good
Cycling, which
1. Keeps Mn in higher oxidation state,
therefore
less soluble
2. Prevents distortion in the coordination of
oxygen (Jahn-Teller)
around the manganese. These distortions
will alter the oxidation and
reduction potential as seen in the next slide
42. M. Stanley Whittingham, Lithium Batteries and Cathode Materials, Chem. Rev. 2004, 104, 4271-4301
