Which species is oxidized during the discharge of the battery?

The answer is Pb (oxidized during battery discharge) Pb + PbO2 + H2SO4 Discharge --> Charge<-- 2PbSO4 + 2H2O.  When a metal go through corrosion it is called Oxidation-reduction.  Redox reaction is the oxidation half-reaction and the reduction-half reaction occur at the same time.

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