FUNDAMENTAL-STUDIES TO DEVELOP THE MAINTE NANCE FREE LEAD-ACID-BATTERIES .1. INFLUENCE OF GRID ALLOY ON CYCLE LIFE OF LEAD-ACID-BATTERIES

To develop maintenance free lead-acid batteries, the relationships bet ween gride alloys and cycle life were studied. From the relationships between alloy composition and the H-2 evolution potential, it was foun d that Sb and Cu components in alloys were the main elements to promot e water loss during charge and the both existence of Sb and Cu was mos t effective for reducing water loss. The self-discharge reaction on th e positive plate with Pb-Ca-Sn alloy grid mainly progressed at the int erface between the grid and the active material, affecting the storage characteristics. Thus, the self-discharge of lead-acid batteries was inhibited by the formation of an electrochemically stable alpha-PbO2 l ayer at the interface between the grid and the active material. Since the stable oxide decomposes during discharge, overdischarge of positiv e plate must be avoided. The growth of Pb-Ca-Sn alloy grid was mainly caused by the increase in the degree of corrosion, due to lead-sulfati on at the grain boundary. This phenomena occurred exceedingly during t he overcharge and the deep discharge.