IMPLANTED PROBES FOLLOW CHANGES IN ELECTROLYTE-COMPOSITION IN CYCLING ZN/NIOOH CELLS

Implanted probes in zinc electrodes within 150 Ah-size zinc/nickel oxide cells were used to analyze the composition of electrolyte samples at different locations and stages of cycling. The probes had a negligible effect on the performance of the cells out to 300 cycles. Analyses of electrolyte density and dissolved zinc, and changes in KOH and carbonate concentration, were used to investigate the shape change process, which was followed using an x-ray radiography technique. It was found that the loss in cell capacity was directly related to the shape change of the zinc electrode. The data indicates that the shape change process involves several stages of development and that eventually the calcium zincate used to trap the dissolved zincate in solution and retard shape change loses its effectiveness, possibly through the formation of calcium carbonate in the electrode structure. © 1990, The Electrochemical Society, Inc. All rights reserved.