Studies on the microstructure of the positive lead-acid battery plate and its electrochemical reactivity

It has been shown that the physicochemical properties of PbO2 in the positive plate of a lead-acid battery relates to the PbO2 crystal size growth during charge/discharge cycling. It was found that there were two types of PbO2 present in an uncycled positive plate thermally decomposed into tet-PbO: One with, and the other without, forming β-PbOx. The degree of crystallinity was found to be lower in the surface layer of PbO2 crystals than in the interior. The degree of crystallinity of PbO2 crystals increased with cycling, and at the same time the size of PbO2 crystals became larger, causing decrease in the specific surface area and surface roughness. It was also concluded that the electrochemical reactivity of the surface layer of PbO2 was strongly influenced by the properties of the PbO2 crystal lattice characterized by the formula PbO2-δ(xH2O).