Threedimension Multiscale Electrochemical Model for Lithiumion Battery Based on Similarity Theory

Abstract:

A dimensional analysis method was performed to derive similarity criteria and the similarity coefficients of parabolic partial differential equation, and then it was further generalized to deduce the similarity coefficients of the electrochemical process. To validate the similarity criteria and the similarity coefficients, threedimension finite element models of electrochemical process of lithium ion battery under specified conditions were established with the software of Comsol Multiphysics. The simulation results show that the similarity criteria and the similarity coefficients are certified to be correct and the modelling method based on the similarity theory can achieve equivalent simulation. Moreover, the simulation results reveal that the inner state of the battery tends to be uneven under high rate operation, thus corresponding measurements in design and management based on conventional Pseudo2D model should be modified to avoid safety issues due to a local overcharge or overdischarge.

Key words:lithium ion battery; electrochemical field; similarity theory