Numerical modeling on the delamination-induced capacity degradation of silicon anode

Silicon is a promising candidate for the negative electrode in lithium-ion battery. However, silicon-based electrodes experience large volume changes during the lithiation-delithiation process, which may lead to their failure and hinder their application. Delamination of the silicon layer from the current collector substrate is one of the critical failure modes; its effects on the performance degradation of Si anode need to be better understood. In this study, a multi-physics based finite element model is established to investigate the impact of Si layer delamination, where an artificial insulating interface is introduced to simulate the delamination phenomenon. It is found that delamination could result in a large amount of residual lithium within Si phase at the end of the delithiation process, leading to the capacity degradation of the Si anode. Furthermore, depth of delamination, Si layer thickness and charging/discharging C-rate are three critical influencing factors for the performances of the Si anode. With the increase of depth of delamination and Si layer thickness, the remaining useful capacity of the Si anode will gradually reduce. In addition, under high C-rate operating conditions, the capacity loss of the anode will be largely exaggerated by the presence of the delamination.