Probing the Thermal Implications in Mechanical Degradation of Lithium-Ion Battery Electrodes

In a lithium-ion cell, heat generation and temperature evolution during operation pose a significant bearing on the mechanical degradation and cell performance. The thermal implications on the electrode mechano-electrochemical behavior have been elucidated. Crack formation due to diffusion-induced stress in the active particles has been analyzed. Temperature dependence of the mechanophysicochemical parameters has been taken into account. Total amount of diffusion-induced damage has been estimated for different current density, ambient temperature and particle size. For subzero temperatures, adiabatic operation can boost the cell performance significantly. Increased mechanical degradation has been observed for high C-rate and larger particle sizes. Decreasing ambient temperature results in aggravated crack formation resulting in severe capacity loss. However, at subzero temperatures and under high C-rate conditions, significant concentration gradient exists near the active particle peripheral region resulting in reduced damage penetration. The cell performance analysis reveals that the impact of mechanical degradation on the capacity loss is most prominent at subzero temperatures. The effect of cycling shows accelerated damage in the first few cycles followed by a plateau in the damage evolution. Existence of a critical particle size for maximum damage has been suggested which depends significantly on the cell temperature.