Thermodynamic Analysis of Initial Steps for Void Formation at Lithium/Solid Electrolyte Interphase Interfaces

Lithium metal batteries are a critical piece toward electrifying aviation. For electric aircraft, high discharge power requirements necessitate stripping of lithium metal in a uniform way. Recent studies have identified the evolution of surface voids and pits as a failure mechanism. In this work, using density functional theory calculations and thermodynamic modeling, we investigate the initial step associated with void formation, that is, vacancy congregation, on lithium metal surfaces and interfaces with solid electrolyte interphase (SEI) materials. For isolated lithium slabs, the (111) surface is the least likely to exhibit pitting issues. However, once interfaces with SEI materials are considered, only the (110) lithium facet has the potential of preventing void growth, and exclusively when paired with lithium carbonate. Our work suggests that faceting control during electrodeposition could be a key pathway toward preventing voids and highlights the importance of interface design for optimal battery performance.