A Fully Coupled Thermomechanical Analysis of Lithium-Ion Batteries with Total Heat Generation Rate

Abstract

The performance of Lithium-ion batteries (LIBs) is seriously affected by temperature rise and mechanical degradation during the charge or discharge. In this work, a fully coupled thermomechanical model with the total heat generation rate is developed to analyze the mechanism of the temperature rise and stress distribution. Then numerical simulations are performed to show the evolution of temperature and stress for 18650 LIBs. The comparisons of the surface temperature evolution between the present model and experimental results, and the temperature variation with radius between the present model and the pure thermal model are made, respectively. Finally, the influences of some design parameters upon the Li-ions concentration and the stress are discussed. The numerical results show that the present model is more validated against the pure thermal model, and the temperature and stress will be reduced if the positive electrode particle radius, the volume fraction of the positive active material and the initial electrolyte salt concentration are decreased, or the positive electrode thickness is increased which will provide some guides for the design of LIBs.