Fracture analysis of bi-layer electrode in lithium-ion battery caused by diffusion-induced stress

An analytical model has been developed to study the fracture behavior of bi-layer electrodes in the lithium-ion battery under galvanostatic intercalation and deintercalation. The bi-layer electrode is composed of an active strip and a current collector. Crack initiation and propagation may occur when the peak tensile stress caused by diffusion exceeds the theoretical strength of the active strip. For this, solutions of concentration distribution and diffusion-induced stress are derived and the stress intensity factors at the crack tips are calculated. Numerical results show that cracks may be more easily initiated during extraction of lithium ions in the active strip since the peak tensile stress during extraction is much larger than that during insertion. Stress intensity factor decreases with increasing values of crack length, which demonstrates that crack propagation may cease when it reaches a certain length