INVESTIGATIONS INTO THE ELECTROCHEMISTRY OF RECOMBINANT, SEALED LEAD-ACID-BATTERIES

In modern stationary and cycling operations of lead/acid batteries, gas-recombination technology is being used more and more frequently to eliminate battery maintenance. Research studies in the Central Laboratory of Batteries and Cells (CLAiO) are focused on the optimization of the gas-recombination process in lead/acid batteries, mainly in float duties. This work includes investigations of the kinetics of gas evolution on different types of alloy, and of the effect of paste composition and the method employed for electrolyte immobilization (i.e., gel or absorptive glass-mat). Tests have been performed on stationary cells of 4.5 A h capacity (C/10) and using grids of size 66.0 mm X 96.5 mm. The grids were made from low-antimony alloy (1.7 wt.% Sb), lead-tin-calcium-aluminium alloy, or pure lead. Investigations of the gas-evolution kinetics has confirmed that during the initial phase of float operation, the lowest gassing is observed for nonantimonial and pure-lead grids in cells using absorptive glass-microfibre separators. Higher rates of gas evolution take place in cells with gelled electrolyte, but these decrease as the float operation is continued. Cells have been dismantled in order to investigate changes in the phase composition of the positive active material. Changes in phase composition of the active material during float operation have been monitored by X-ray diffraction phase analysis.