Electrochemical-Thermal-Mechanical Coupling Analysis of Lithium-Ion Batteries under Fast Charging

Thermal runaway and volume expansion caused by temperature rise under fast charging of lithium-ion batteries (LIBs) are the major reasons of battery explosion and cycle performance degradation. In this work, considering the radiation heat transfer on the battery surface, an electrochemical-thermal-mechanical coupling model of cylindrical LIBs under fast charging (state of charge (SOC) ≤80%) is developed in order to investigate the distributions of the temperature and stress. Then, choosing 18650 LIBs as the object, the charge efficiency, temperature, and stress distributions are compared between fast charging and galvanostatic operation under SOC≤80%, respectively. Finally, the influences of the thickness, particle radius, the maximum lithium-ion concentration of the cathode, and initial electrolyte concentration on the temperature, radial stress, and hoop stress of LIB during charge are explored, respectively. Numerical results show that fast charging improves 20.8% of the charge efficiency. Increasing the cathodic thickness and decreasing the cathodic maximum lithium-ion concentration or initial electrolyte concentration can reduce the temperature of LIB during the charge. The results of this work will provide some reference value for the design of LIBs under fast charging.