Page 214 - Handbook of Battery Materials

6.4 PbO 2 as Active Material in Lead–Acid Batteries 183

Table 6.6 Molar weight of lead dioxide, required quantity,
and utilization.

Molar weight Required quantity Utilization a
−1
(g) (g Ah )
Theory Practice
−1
−1
−1
(Ah kg ) (Ah lb ) (Ah kg )
239.2 4.462 224.1 101.7 60–130
a Utilization in theory derived from Equation 6.29; utilization in practice
mainly depends on electrode thickness (cf. Ref. [12]).

88.11

Figure 6.4 Cross-section of a Plant´ e plate. The fine lamellas
of the casting enlarge its surface area by a factor of 8–12.
On the top, the current collector, the plate lug, is to be
seen.
plate. The plate is cast from pure lead. Its surface is enlarged by lamellas that
can be seen in Figure 6.4. Plant´ e formed the dioxide layer by a large number of
charge–discharge cycles. Nowadays, the electrochemical oxidation is enhanced by
the addition of perchloric acid (HClO 4 ) during the ‘formation process.’ It increases
the solubility of lead and increases the corrosion rate so far that a single charging
cycle is sufficient. The precisely controlled process results in a layer of active
material, that is, about 220 µm thick.