Research on separators for alkaline zinc batteries

A hybrid separator as an improved battery separator in alkaline zinc secondary batteries with particular emphasis on mitigating the failure of zinc electrodes by controlling the permselectivity of the separator. Hybrid separators consist of a microporous film, radiation-grafted with a monomer containing ion-exchange groups and incorporate the favorable aspects of both ion-exchange membranes and microporous separators. Such hybrid separators should ideally be highly specific for fast transport of electrolyte while inhibiting zincate diffusion. Hybrid separators with a wide range of percent graft (0% to 60%) were made by varying the monomer concentration and radiation time. The grafting of these ionic groups imparts the ion selectivity of the separators. The electrolyte uptake of hybrid separators is ca. 60 wt %. The higher the percent graft of the separator, the higher the water uptake and the lower the KOH uptake that are observed. The permeabilities of zincate ions were measured for a series of hybrid separators.