Direct Energy, 2018a

226 9.5 Battery Types
at the anode is
Pb+SO 2−
4 → PbSO 4 +2e − (9.48)
with a redox potential of V rp =0.37 V [140]. The reaction at the cathode
is
PbO 2 + SO 2−
4 +4H + +2e − → PbSO 4 +2H 2 O (9.49)
with a redox potential of V rp =1.685 V [140]. The overall cell voltage is
V cell =2.055 V, so in a car battery, six cells are packaged in series.
Lead acid batteries have a long history. The development ofthe battery
dates to the work ofVolta around 1795 [3, p. 2], and practical lead acid
batteries were rst developed around 1860 by Raymond Gaston Planté
[128, p. 16.1.1]. Today, lead acid batteries are used to start the ignition
system in cars and trucks, used as stationary backup power systems, and
used in other applications requiring large capacity and large output current.
Typically, lead acid batteries can handle relatively high current, and they
operate well over a wide temperature range [128, p. 15.2]. Additionally,
they have a at discharge curve [128, p. 15.2]. Other types ofbatteries have
a higher energy density and specic energy, so lead acid batteries are used
in situations where specic energy is less ofa concern than other factors.
9.5.3 Alkaline
Alkaline batteries typically have a zinc anode and a manganese dioxide
MnO 2 cathode [128, p. 8.10]. Figure 9.7 shows naturally occurring manganese
dioxide (the dark mineral) on feldspar (the white mineral) from
Ruggles mine near Grafton, New Hampshire. The batteries are called alkaline
due to the use ofan alkaline electrolyte, typically a liquid potassium
hydroxide KOH solution [128, p. 8.10]. Most alkaline batteries are primary
batteries, but some secondary alkaline batteries are available. Alkaline batteries
have many nice properties. They can handle high current outputs,
they are inexpensive, and they operate well over a wide temperature range
[128, p. 8.10]. One limitation, though, is that they have a sloping discharge
curve [128, p. 8.10]. Alkaline batteries were originally developed for military
applications during WWII [128, ch. 8]. They became commercially
available in 1959, and they became popular in the 1980s with improvements
in their quality [128, p.11.1]. They are commonly used today in inexpensive
electronics, toys, and gadgets.