The transmission line equivalent circuit model in solid-state electrochemistry

This note presents a generalization of the small-signal ac transport description of systems with electronic and ionic charges. To be specific, hole polarons and counterions in a conjugated polymer are considered. The derivation of the transmission line equivalent circuit is in principle close to the one of Sah (1969¯1970) for solid-state electronics. It is shown (i) that in non-equilibrium current generators have to be added to the Barker/Brumleve/Buck circuit; (ii) in addition, traps for both the hole polarons and the ions are taken into account; (iii) the reduction to the lf limit is discussed; (iv) the principle extension to a porous two-phase system is presented.