Probing process kinetics in batteries with electrochemical impedance spectroscopy

Electrochemical impedance spectroscopy provides information on the steady state of an electrochemical redox reaction and its kinetics. For instance, impedance is a very useful technique to investigate kinetics in batteries, such as diffusion processes or charge-transfer reaction dynamics during battery operation. Here, we summarize procedures for conducting reliable impedance measurements on a battery system, including cell configurations, readiness of a system for impedance testing, validation of the data in an impedance spectrum, deconvolution of electrochemical processes based on the distribution of relaxation time and equivalent circuit fitting of the impedance spectrum. The aim of this paper is to discuss key parameters for accurate and repeatable impedance measurements of batteries. Electrochemical impedance spectroscopy is a powerful and increasingly accessible approach for studying kinetic processes in batteries. Here, key factors for using impedance to obtain accurate and reproducible data from batteries are discussed, providing guidance for researchers.