Chemistry The lead acid battery uses lead as the anode and lead dioxide as the cathode, with an acid electrolyte. The following half-cell reactions take place inside the cell during discharge: At the anode: Pb + HSO 4 – → PbSO 4 + H + + 2e – At the cathode: PbO 2 + 3H + + HSO 4 – + 2e – → PbSO 4 + 2H 2 O ...