Proposal of novel equivalent circuit for electrochemical impedance analysis of commercially available lithium ion battery

To analyze impedance response of an electrochemical system, it is important to model the system with an adequate equivalent circuit. In the present work, an equivalent circuit was designed for the analysis of lithium ion batteries with the contributions of a variety of diffusion parameters resulting from the various particle sizes for the cathode and the solid-electrolyte interphase formed on the anode particles, as well as electrochemical reactions and inductive components. Residual errors resulting from the data fitting was investigated for a variety of equivalent circuits used. The electrochemical impedance of the electrodes in commercial lithium ion batteries at various states of charge was analyzed to evaluate the proposed circuit.

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► An equivalent circuit with inductive component, anode, SEI, cathode, and diffusion of Li+ was designed and proposed.
► The cathode with two sets of different parameters was considered.
► The impedance of a commercial LIB with variation of SOC was successfully analyzed.
► Errors of data fitting were also discussed.