A study of the passivation mechanism of negative plates in lead/acid batteries

The passivation mechanism of negative plates has been investigated by means of linear sweep voltammetry and scanning electron microscopy. It is found that the reduction peak of PbSO4 is split into two peaks on a seriously passivated negative plate. This is attributed to the reduction of PbSO4 crystals of different sizes. The reduction rate of the negative plate depends on the diffusion of SO4; from the depth of micropo from the depth of micropores to the bulk solution. The narrow and long microporous passageways and the big PbSO4 crystals in the active mass result in serious sulfation of the negative plate. The effects of the active mass structure and the additive in the solution are also discussed.