Separation composition evaluation in model rechargeable silver-zinc cells

In previous reports, the evaluation of Viskase sausage casings (SCs) in a variety of configurations for silver/zinc rechargeable cells has been reported. The conclusions have been that several layers of SC, while providing improved resistance to silver migration acid zinc dendrite growth compared to standard cellophane film, also impart increased internal impedance which leads to faster capacity loss in comparison to standard cellophane film. The principal direction for further work appeared to be to incorporate a thin film layer of polyvinyl alcohol to serve as an additional barrier to silver migration. This would allow a reduction in the number of layers of SC, resulting in a decrease in impedance and an increase in capacity performance. The purpose of this program was to evaluate the possibility of reducing the number of layers of cellulosic sausage casing (SC) on the cathode of model silver/zinc rechargeable cells, in order to improve the cycling discharge performance and also to allow greater loading on the electrodes for improved volumetric energy density. Another objective was to evaluate the effect of splitting standard cellophane wrap between the cathode and anode to determine if cycle life and/or wet life performance could be improved over standard cathode-only wrap.