WFU Physics Colloquium

TITLE: First principles investigations of solid-solid interfaces in lithium battery materials

SPEAKER: Nicholas D. Lepley

TIME: Friday September 18, 2015 at 2:30 PM

PLACE: Room 101 Olin Physical Laboratory

I explain some of the current issues driving the development of Li batteries and some of the current research opportunities. In particular I focus on my work using ab initio theoretical methods to model electrode/electrolyte interfaces for inorganic solid electrolyte materials, especially those related to Li₃PS₄. I present a general scheme based on the interface energy for analyzing interfaces between crystalline solids, quantitatively including the effects of varying configurations and lattice strain. This scheme is successfully applied to the modeling of likely interface geometries of several solid state battery materials including Li metal, Li₃PO₄, Li₃PS₄, Li₂O, and Li₂S. This formalism, together with partial density of states analysis, allows me to characterize the extent, stability, and transport properties of these interfaces. My investigation finds that all of the interfaces in this study are stable with the exception of Li₃PS₄/Li. For this chemically unstable interface, the partial density of states helps to identify mechanisms associated with the interface reactions. The energetic measure of interfaces and analysis of the band alignment between interface materials indicate multiple factors which may be predictors of interface stability, an important property of electrolyte systems.