Study of resistance changes related to premature capacity loss in lead battery plates

Measurements of the resistance of the active material and of the interphase between the active material and the lead grid were performed by an exact d.c. method during cycling under two different regimes using specially prepared positive test electrodes with grids from seven different lead alloys. The results were compared with those obtained earlier by using a higher (1 h) discharge rate. In both cases, the premature capacity loss was caused by a low charging rate and it was related with increasing resistance of the active material, although the cycle life was distinctly longer at the lower (4 h) rate of discharge. The interphase resistance values of the individual ribs show a scatter which becomes very pronounced at the end of the cycle life, indicating a degradation of the porous electrode structure, often manifested by shedding of the active material.