Microscopic Structure and Discharging Properties of Mechanically-Milled Positive Active Material PbO₂ with an Addition of Sb in Lead-Acid Battery

Abstract

PbO₂ powder, which is active positive-electrode material in the lead-acid battery, was mechanically milled with Sb₂O₃ powder. It is well known that Sb contained in the grid of the lead-acid battery is useful for the protection of the premature capacity loss. The results of the X-ray diffraction and EPMA (Electron Probe Micro Analyzer) showed that the alloying between PbO₂ and Sb₂O₃ proceeded during the milling process. The position of the reduction peak in the CV (Cyclic Voltammetry) curve shifted to the lower potential and the intensity of the reduction peak increased with an increase of the scanning speed of the potential. The intensity of the reduction peak in the CV curve for the electrode constructed from PbO₂ powder added with Sb₂O₃ was much reduced compared to that for the electrode constructed from PbO₂ powder. The result of EPMA showed that the reduction reaction from PbO₂ to PbSO₄ proceeded more rapidly in the electrode constructed from PbO₂ powder added with Sb₂O₃, and that Sb was not detected in PbSO₄ particles. The above phenomena observed in the electrode constructed from PbO₂ powder added with Sb₂O₃ seem to be concerned with the protection of the premature capacity loss of the lead-acid battery.