In lead acid battery, chemical reactions are induced to
do work on charge and produce a voltage difference between the two output
terminals.
In a lead storage battery, the negative terminal is
composed of lead electrode (Pb2+) while in the positive terminal it is composed
of lead dioxide electrode (PbO2).
The chemical half reactions in each electrode are:
Negative Terminal: Pb2+
+ SO4(2-) ---> PbSO4 + 2e
Lead
electrode is oxidized to supply electrons.
Positive Terminal: PbO2 + H2SO4 + e ---> PbSO4
Lead dioxide
electrode is reduced by the addition of electrons.
Answer: Lead dioxide is reduced.
