Environmental Engineering Reference
In-Depth Information
TABLE 6.1
Characteristics of Major Secondary Systems
Vanadium
Redox
Lead-Acid
NaS
LiIon
Chemistry:
Anode
Cathode
Electrolyte
Pb
PbO
2
H
2
SO
4
Na
S
β-alumina
C
LiCoO
2
Organic solvent
V
2+
↔ V
3+
V
4+
↔ V
5+
H
2
SO
4
Cell voltage:
Open circuit
Operating
2.1
2.0 to 1.8
2.1
2.0 to 1.8
4.1
4.0 to 3.0
1.2
Specific energy and
energy density
:
Wh/kg
Wh/L
10 to 35
50 to 90
133 to 202
285 to 345
150
400
20 to 30
30
Discharge profile
Flat
Flat
Sloping
Flat
Specific power
(W/kg)
Moderate
35 to 50
High
36 to 60
Moderate
80 to 130
High
110
Cycle life (cycles)
200 to 700
2,500 to 4,500
1,000
12,000
Advantages
Low cost,
good high
rate
Potential low
cost, high cycle
life, high
energy, good
power density,
high efficiency
High specific
energy and
energy
density, low
self discharge,
long cycle life
High energy,
efficiency,
and charge
rate, low
replacement
cost
Limitations
Limited
energy
density,
hydrogen
evolution
Thermal
management,
safety, seal and
freeze-thaw
durabilities
Lower rate
(compared to
aqueous
systems)
Cross mixing
of electrolytes
Lead-Acid Batteries
All lead-acid designs share the same basic chemistry. The positive elec-
trode is composed of lead dioxide (PbO
2
) and the negative electrode is
composed of metallic lead (Pb). The active material in both electrodes
is highly porous to maximize surface area. The electrolyte is a sulfuric
acid, usually around 37% by weight when the battery is fully charged.
The major starting material is highly purified lead. The lead is used for
the production of alloys (for subsequent conversion to grids) and to pro-
duce lead oxides (for subsequent conversion first to paste and ultimately
to the positive lead dioxide active material and the negative sponge lead
active material).
The preparation of the active material precursor consists of a series of
mixing and curing operations using a mixture of lead and lead oxide
(PbO + Pb), sulfuric acid, and water. The ratios of the reactants and curing
