New approach to prevent premature capacity loss of lead-acid battery in cycle use

Pb–Ca foil laminated on rolled sheet for positive grid of lead-acid battery is proposed to prevent premature capacity loss (PCL) during charge–discharge cycling. Batteries with Pb–Ca foil laminated on positive grid had longer life during charge–discharge cycle than conventional battery, which failed early by PCL. PCL is a phenomenon due to the increase of the interfacial resistance between the positive grid and the positive active mass (PAM) during discharging by PbSO4 formation in the corrosion layer. Positive plates suffered from PCL when the compression between the grid and the PAM was poor, H2SO4 concentration at the interface was high or the corrosion layer mainly consisted of β-PbO2. Adhesion between the PAM and Pb–5%Sb alloy or Pb–1%Ca alloy was firmer than that between the PAM and Pb–0.06%Ca–1.5%Sn. Corrosion layer formed at the interface between grid material and the PAM during cycle included more α-PbO2 on Pb–5%Sb and on Pb–1%Ca than on Pb–0.06%Ca–1.5%Sn. It was found out that excellent cycle life performance with Pb–1%Ca foil against PCL is due to firm adhesion between the PAM and grid material, and that α-PbO2 is formed at the interface as a result of firm adhesion of the PAM and Pb–1%Ca grid.