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Comparison of time constants for liquid ion-exchange membrane electrode responses determined by an impedance method and an activity step method

1979; Elsevier BV; Volume: 109; Issue: 2 Linguagem: Inglês

10.1016/s0003-2670(01)84257-4

1873-4324

Frederick S. Stover, Timothy R. Brumleve, Richard P. Buck,

Advanced Battery Technologies Research

Linear current-step perturbations and resulting membrane potential responses of liquid ion-exchange membranes have been analyzed and the numerous possible time constants examined and catalogued. Ideal activity steps at a single membrane interface produce potential—time responses similar to those resulting from current steps. The common time constants have nearly identical values. However, fewer time constants are observed for activity steps than for current steps. Slow processes at the active interface dominate and obscure short time processes. For liquid ion-exchange membranes it is concluded that an activity step on one side is not identical to a current step because processes involving bulk membrane transport and the far side of the membrane are not involved to the same extent for the two excitation modes. Two analog circuit models (one active, one passive) are proposed for the potential—time response to an activity step. Systems containing neutral carriers are not considered.