Analytical solution for thermal-diffusion induced stress model and numerical simulation of battery structure during charging-discharging process

Abstract

During the course of thousands of charging and discharging cycles, batteries commonly undergo capacity fade and resistance growth, known as electrode aging. This phenomenon is attributed to local inhomogeneous deformation, as well as the possibility of fracture within electrode particles due to complex multi-physical couplings. To mitigate electrode aging and slow down the rate of fading, it is crucial to develop protective designs and tailored battery management strategies. However, accurately predicting potential fracturing and conducting precise battery simulations remain open challenges. This study presents a battery aging simulation model that incorporates multiphysical couplings of heat, concentration, stress, electric, and phase fields to assess battery performance at both the structural and electrode particle levels. Initially, an analytical solution is derived to determine stress distribution at the particle level within the thermal-concentration-mechanical deformation coupling, enabling quick calculation of stress distribution. Subsequently, a comprehensive battery structure is constructed to simulate discharge performance. Furthermore, the model computes the stress levels and fracture potential of the electrodes, thereby identifying locations prone to aging. Analytical and numerical findings indicate that tensile stress on the surface of an individual electrode acts as the driving force for fracture during lithium intercalation. Moreover, electrodes in close proximity to the electrolyte generate higher heat, while those near the electrode current collector are more susceptible to fracturing.