Tuning Ionic Conductivity and Stability of Li10GeP2S12 Solid-State Electrolyte

Abstract

All-solid-state Li-ion batteries gained a huge attention because they exhibit higher power density, wider electrochemical stability windows, and overall safety of solid-state electrolytes (SSE) compared to conventional liquid electrolyte-based batteries. Unfortunately, most of the SSE materials have not matched the ionic conductivity of their liquid counterpart. But, recent research and the synthesis of new materials have shown SSE can conduct ions at an equivalent or even higher rate. However, the electrochemical stability needs to be improved. There is a growing research effort in identifying a solid electrolyte that is both electrochemically stable and has a very high ionic conductivity. The Li10GeP2S12 (LGPS) is one of the superionic conductors, is known for its high ionic conductivity that can be deployed as a solid electrolyte in batteries. However, LGPS is not stable as exposed to air and moisture, posing challenges during its manufacturing, and designing process. Thus, in an attempt to optimize the stability and ionic conductivity, the effect of antimony (Sb), tin (Sn), and oxygen (O) substitution on conductivity and stability of LGPS is investigated using Density Functional Theory (DFT). The systematic study of compositional variation, phase stability, defects chemistry, and the impact on electronic properties and ionic conductivity is performed. Thus, this study will provide significant insights on ion conduction mechanisms and strategies that can tune the ionic conductivity and stability of LGPS based electrolytes. This project was supported in part by COE SJSU, DOE NERSC, and XSEDE.