The cell reactions when the battery is in use are given below:
Anode:
Pb(s) + SO4
2–(aq) ® PbSO4(s) + 2e–
Cathode:
PbO2(s) + SO4
2–(aq) + 4H+(aq) + 2e– ® PbSO4 (s) + 2H2O (l)
i e , overall cell reaction consisting of cathode and anode reactions is:
Pb(s) + PbO2(s) + 2H2SO4(aq) ® 2PbSO4(s) + 2H2O(l)
On charging the battery the reaction is reversed and PbSO4(s) on
anode and cathode is converted into Pb and PbO2, respectively Fig