General aperiodic equivalent circuit for charge permeable thin-layer cells of symmetric or asymmetric types. Part 2.—Interfacial kinetics

Abstract

In Part 1, various predictions of the basic Barker–Brumleve–Buck (BBB) sub-circuit units, were illustrated, viz., the conventional two-feature mass transport-controlled impedance was generated. This finite two-port, four-terminal network designed by us, generally as a two-port, 2n-terminal network, can replace the classical one-port, two-terminal cable transmission line analogue. Results were specifically used to compare BBB impedances with shorted and open finite cables to show conditions of equivalence. We used a newer procedure that was not available in our laboratory in 1980: SPICE circuit simulation. The well known two-feature impedance plane plot arises for two charged species from this simple circuit when interfacial ion transport is reversible. Both symmetric or asymmetric cell results depend only on the ion or electron terminals used.

In Part 2, the usual three-feature impedance plane plots follow for slow, potential-dependent ion and/or electron transfers with usual linearized activation kinetics, by addition of parallel activation resistance and relaxed double layer capacitance network for each ion requiring activation to cross the interfaces. In addition, residual cell solution resistance and total cell geometric capacitance has been included. These four-feature impedance plots are frequently observed for chemically modified electrode cells.