Understanding the Role of Lithium Metal Microstructure in Chemo-Mechanical Instability of Solid-State Batteries

Abstract

Increased energy density and safety relative to conventional lithium (Li)-ion batteries motivate the development of solid-state batteries (SSBs). However, maintaining interface stability at the metal anode–solid electrolyte (SE) interface remains a critical challenge to achieving practical areal capacities, especially during stripping/discharge. Here, a mesoscale model informed by atomistic simulations is employed to examine void formation at the Li metal–SE interface during discharge/stripping. The model reveals how void-formation-driven interfacial contact loss behavior depends on the microstructural properties of the polycrystalline Li anode. In agreement with prior studies, Li microstructures with small grain sizes promote self-diffusion-induced void healing and generally exhibit better interfacial contact. We further show the effect of operating conditions, such as applied pressure, stripping current density, and temperature, on the stripping performance for different Li microstructures. Through this study, we shed light on the importance of taking microstructural features into account in predicting interfacial contact evolution during stripping of Li metal SSBs.