Investigation of low-zinc-solubility electrodes and electrolytes in zinc/silver oxide cells

The cycle-life performance of the Zn/AgO cell is limited by high rates of Zn active material redistribution (shape change) and Zn dendrite growth. Reduced-zinc-solubility electrolytes, prepared by adding F−, CO32−, BO33− and PO43− salts to aqueous KOH solutions, were used in 5 A h Zn/AgO cells to determine their effect on cell lifetimes. Ca(OH)2 additions to the Zn electrode were also evaluated in cells of the same capacity and mass as the calcium-free cells. It was found that all of the anion additives to KOH electrolytes resulted in lower cell capacities and shorter lifetimes, which could be attributed the formation of soluble Ag-containing salts and subsequent degradation of the Ag electrode performance. The calcium-containing Zn electrode was found to significantly improve the performance of the Zn/AgO cell by promoting higher capacities, especially over the initial 20 cycles. The higher capacities could be attributed to the formation of a calcium zincate complex, crystals of which were found in the cycled Zn electrodes.