Interfacial contact loss and bending effects on electrochemical-mechanical modeling for all-solid-state Li-ion batteries

Abstract

All-solid-state Li-ion batteries (ASSLBs) are ideal power sources for the future electric vehicle and energy storage industries, but electrodes/solid-electrolytes (SE) interface issues and mechanical flexibility are emerging as the major limitation to the development of ASSLBs. In this paper, a flexible thin-film ASSLB composed of NMC811 cathode, SiC anode, and LGPS solid-electrolyte is studied. An interfacial contact model and a coupled electrochemical-mechanical model of the ASSLB with bending effects are developed by numerical solution. The results show that bending effects can alleviate the interfacial stress which occurs during lithiation. In addition, external pressure, a smoother interface and a softer solid electrolyte can effectively improve the actual contact area. To investigate the effects of contact factors and curvature on the cell potential, a complete charge-discharge cycle is simulated. It is found that increasing the curvature and contact factor can delay the time to reach the cut-off voltage which increases the cell capacity. The curvature mainly affects the electrolyte potential while the contact coefficient mainly affects the overpotential. Taken together, this study explains the effects of curvature and contact loss on the mechanical and electrochemical behavior of ASSLBs, and provides theoretical guidance for improving the interface design and enhancing cell stability.