Micromechanisms of Capacity Fade in Silicon Anode for Lithium-Ion Batteries

Abstract

Large volume change and associated stress generation is known to cause failure of the silicon thin film anode used for Lithium-ion batteries after a few cycles. Experimental observations suggest that plastic deformation of the underlying Cu substrate and degradation of the active/inactive interface are the primary reasons responsible for the capacity fade. The goal of the present study is to examine the interplay between these mechanisms using a computational mechanics approach. In the present study, a novel multi-physics finite element framework has been developed to simulate the lithiation and de-lithiation induced failure of amorphous Si (a-Si) thin film on Cu foil. The numerical framework is based on the finite deformation of the active silicon wherein diffusion of lithium occurs, plastic deformation of the Cu foil, and debonding of the active/inactive interface. The effect of substrate property, interfacial energy and kinetics of interface degradation has been examined.