Suitable Position of Reference Electrode in Three-Electrode Cell for Impedance Measurements in Lithium-Ion Rechargeable Battery Investigated By Finite Element Method

Abstract

Our group [1] determined the suitable position of the reference electrode for impedance measurements in lithiumion rechargeable batteries (LIRBs) with a three-electrode cell by finite element method (FEM). Electrochemical impedance spectroscopy (EIS) is a powerful method to investigate the performance of batteries [2-7]. It is important to obtain the electrochemical paramters of the positive and negative electrodes in LIRBs. In order to measure the impedance spectra of both electrodes in LIRBs cell, a three-electrode cell is used for the impedace measurement. Although the electrochemical properties of the positive and negative electrodes in LIRBs cell were investigated using the three-electrode cell by EIS [8-11], the position of the reference electrode was yet to be established for the impedance measurement. As the measured impedance spectra are affected by the current distribution between electrodes, it is important to determine the suitable position of the reference electrode in the LIRBs cell. In the present study, we proposed the best position of the reference electrode for measurement of the impedance spectra of the positive and negative electrodes in the LIRB cell by using a three-electrode cell. A symmetrical model for the LIRB cell is used for the FEM simulation. The simulations of the current and potential distributions for both electrodes are performed by FEM. The impedance spectra of both electrodes were also calculated by FEM to discuss the effect of the position of the reference electrode on the current distribution between both electrodes.