Transport processes in zinc-silver oxide battery separators

Diffusion rates were measured using an electrochemical technique; the electrical currents generated were diffusion--controlled. The separator was assumed isotropic. The current-time dependence yielded two asymptotic solutions: (1) Short time solution. The current decreases monotonously with the square root of time. The magnitude of the currents is dependent on the concentration of the electroactive species and the electrode area; it is independent of the separator thickness. (2) Steady-state solution. The currents vary linearly with concentration of the electroactive species, electrode area and reciprocal of separator thickness. Duffusion rates were correlated with measurable geometrical parameters of the porous matrix (thickness and cross-sectional area), electrolyte (concentration of electroactive species), and the effective diffusion coefficient of the separator.