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

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.