Abstract
The behaviors of In3+ and activator were studied on Pb anode of lead-acid batteries. The deposition of In with high hydrogen overpotential during the potential scan deviates negatively the hydrogen evolution potential. The current in redox couple of Pb/PbSO4 is slightly decreased because of PbSO4 formation on Pb adsorbed with In. This is the important difference between In3+ and Ag+ added to 5M H2SO4. The activator is less adsorbable on bear Pb, and adsorbed easily on PbSO4 formed on Pb. The complex ions of In3+ and activator molecules are adsorbable on Pb, and PbSO4 is initially formed on the adsorbed layer of complex ion at the potential in redox couple of Pb/PbSO4.
