Patent ID: 7029792

Claim:
A secondary, zinc ion battery comprising in combination; a battery case containing; a body of alkaline electrolyte; a zinc electrode disposed in said body of electrolyte; a counter-electrode disposed in said body of electrolyte; and a cellulose separator film having a thickness from 10 microns to 250 microns, being resistant to alkaline electrolyte, being impermeable to zinc ions containing a continuous cellulose phase and a dispersion of discrete domains of polymer having a high hydrogen permeability of at least 1×10 −13 cm 3 cm −1 s −1 Pa −1 , within said cellulose phase said film being impermeable to hydrogen except where said discrete polymer domains of high hydrogen permeability are present in said film and said discrete domains of high hydrogen permeability polymer are present in said film in an amount of 10 to 60 parts by weight to 100 parts of the cellulose film, and said separator film is disposed in said body of electrolyte between said electrodes.