In-parallel and In-series Distributed Circuits as Equivalent Circuits for Electrochemical Impedance —Methods to Reflect Non-uniformity of Electrode and Electrolyte

Abstract

“In-parallel distributed circuits” and “in-series distributed circuits,” which comprise numerous similar circuit units connected in parallel and in series, are proposed, as expansions of traditional lumped constant equivalent circuits for electrochemical impedance spectroscopy, such as Randles-type circuit. An in-series distributed circuit is used to describe non-uniformity of some properties along the direction of the current, whereas an in-parallel distributed circuit is used to describe those along the direction perpendicular to the current. The calculation method of the impedance values of the proposed distributed circuit is presented generally. Qualitative characteristics of the impedance values of several types of distributed circuits were investigated. The results include some types of deviations from behaviors of lumped constant circuits, which is often observed experimentally, such as a distorted semicircle and an inclined vertical line. The proposed calculation method is not specialized for the examples described in this work, and can be widely used to any kind of circuits.