(Industrial Electrochemistry and Electrochemical Engineering Division H. H. Dow Memorial Student Achievement Award) Mechanistic Analysis of Interface Stability in Solid-State Batteries

Solid-state batteries (SSBs) utilizing lithium metal anodes are promising next-generation energy storage systems, capable of offering enhanced energy density and power density when compared to conventional lithium-ion batteries. However, the morphological instability of the lithium anode continues to be a major challenge, resulting in filamentous lithium growth and internal short circuit across a wide range of inorganic solid electrolytes. In addition, the formation and growth of interfacial voids during stripping is a critical mechanism that limits the rate performance of SSBs. A coupled set of electrochemical-transport-mechanics processes governs the dynamic evolution and stability of the solid electrolyte/lithium interface. This interaction is affected by various factors including the mechanical properties and microstructure of the solid electrolyte and lithium metal, external pressure, operating temperature, and interfacial heterogeneities. In this presentation, the competing nature of interfacial mechanisms including electrodissolution, lithium mechanics and lithium diffusion kinetics on the origin of voids during stripping will be discussed. The coupled electrochemical-mechanical processes governing the evolution of lithium filaments, especially driven by microstructural heterogeneities such as grain boundaries will be delineated. An analysis pertaining to the dependence of such failure mechanisms on the external temperature, temperature and current density will be presented. Lastly, the role of underlying electrochemical interactions at the solid-solid interface on the onset of thermal instability in SSBs will be evaluated.