(401b) Computational Design of Defects and Doping in Solid Electrolytes and Solid-Electrolyte Interphases

Native point defects and dopants strongly influence the ionic and electronic conductivity of solid electrolytes and solid-electrolyte interphases (SEIs) in all-solid-state batteries (ASSBs). Point defects such as vacancies mediate solid-state diffusion, while charged defects are a source of electronic carriers (electrons, holes). In solid electrolytes, aliovalent dopants are employed to increase the concentration of defects that mediate ion diffusion. Direct experimental characterization of defects and dopants in ASSBs is limited by metrological challenges. The emergence of first-principles methods to reliably determine defect formation thermodynamics offers a practical way to estimate defect and electronic carrier concentrations. Such calculations can also offer physical insights for understanding and rationally designing ASSB components. In this talk, I will share three example studies where we have leveraged first-principles calculations to: (1) reveal the effects of isovalent substitutions in Na₃SbS₄ – a Na-ion electrolyte, (2) identify new aliovalent dopants that enhance the ionic conductivity of Li₃MCl₆ (M = Sc, Y) halide solid electrolytes, and (3) explain the apparent stability of the Li-LiPON interface that arises from the electronic passivation of the SEI components. Together, the findings of these studies have practical implications for systematic doping to enhance ionic conductivity and suppress electronic conductivity and design of stable solid-solid battery interfaces. The computational approaches to study defects and doping can complement experimental investigations to develop energy-dense and safer ASSBs.