Electrochemical noise for evaluating susceptibility of lead–acid battery electrodes to intergranular corrosion

Abstract

Operating and cycle life performance of lead–acid batteries is governed in part by intergranular corrosion (IGC) of the positive electrode, which results in significant weight loss by grain dropping. The present paper demonstrates the use of frequency and time domain noise measurements to evaluate the effect of grain boundary structure on the resistance of lead electrodes to IGC. Microstructures processed to contain high frequencies of special crystallographically ordered boundaries were compared with conventional cast alloys. Significant reductions in localisation function and in the time constant for repassivation occur as the proportion of special boundaries in the microstructure increases. This reflects a tendency for these ordered interfaces to repassivate more readily and to promote the formation of a more compact, stable, and dense PbO₂-PbSO₄ layer. Electrochemical noise measurements demonstrate the potential for minimising localised intergranular attack and extending battery life by increasing the frequency of highly ordered grain boundaries in the microstructure of lead–acid battery electrodes.