Electrochemical reactions coupled multiphysics modeling for lithium ion battery with non-heterogeneous micro-scale electrodes structures

Abstract

During high-rate discharging process of lithium-ion battery (LIB), the macroscopic models struggle to capture the actual three-dimensional spatial evolutions of physical fields. In this study, an electrochemical-thermal-species coupled microscale homogeneous (MNH) three-dimensional model for LIB is built, with which the electrochemical reaction, lithium-ion concentration, electric potential, and heat generation rate inside the microscale LIB electrodes can be visualized and analyzed. The simulation results show that conventional volume-averaged 1 + 1D Newman models underestimate the influence of the microscopic electrode structure on the diffusion kinetics and reaction kinetics within the electrode. At high multiplicities, the localized pore structure causes insufficient utilization for the electrode material near the collector, leading to the localized hot spots in narrow pores. Additionally, the effects of extreme heat exchange environments on the physical laws within the electrodes are discussed. The results indicate that under an isothermal environment, the mass transfer capability of the electrode decreases. Moreover, the extent of delithiation and heat generation behavior of the particles exhibit stronger spatial nonuniformity, resulting in an increased final cut-off voltage. Furthermore, we conclude that an electrolyte phase potential caused overpotential due to pore structure contributes to the sensitivity of the active polarization heat towards the heat exchange environment.