Systematic parameter acquisition method for electrochemical model of 4.35 V LiCoO2 batteries

摘要

Electrochemical model plays an important role in studying the relationship between the corresponding parameters and battery performance. To improve the accuracy and persuasion of the electrochemical model, a systematic method for key parameters acquisition in 4.35 V LiCoO2 batteries with wound type cell design is presented in this paper. The design specification, lithium ion concentrations, kinetic parameters are measured using different experimental and computational method. In this work, the volume fractions, porosity, states of charge of individual electrodes, diffusion coefficient and membrane impedance R-sf of LiCoO2/graphite pouch cells were estimated. It is found that the diffusion coefficients during discharge processes are larger than the values in the charge processes by Galvanostatic intermittent titration technique (GITT), while the diffusion coefficient calculated by electrochemical impedance spectroscopy (EIS) showed two orders of magnitude smaller as compared with GITT. Based on the experimental and computational results obtained herein this work, the pseudo-two-dimensional (P2D) electrochemical model can predict the electrochemical characteristics with high accuracy.