Effects of intrinsic deformation-dependent diffusion-induced stress of electrode particles in lithium-ion batteries

This work explores the mechanical behavior of silicon (Si) anode materials in lithium-ion batteries (LIBs) during the charge–discharge process, with a focus on the impact of intrinsic deformation on diffusion-induced stress and the diffusion coefficient. Compared to traditional graphite anodes, silicon offers a significantly higher theoretical capacity and is more cost-effective due to its abundance. However, Si anodes experience substantial volume changes, up to 300% during lithiation, leading to large intrinsic strains that affect the diffusion process and stress distribution within the electrode. The study investigates how these intrinsic deformations influence the diffusion coefficient, using a theoretical model based on large deformation theory and continuum mechanics. The diffusion-induced stress is analyzed using the thermal stress analogy method, and numerical simulations are performed to solve the complex nonlinear equations involved. The results reveal how intrinsic deformation-related changes in the diffusion coefficient affect lithium concentration distribution and stress in the electrode under various conditions. These findings are crucial for the design of low-stress, high-performance LIBs, offering insights into optimizing the mechanical stability and electrochemical performance of Si-based anodes.