The lithium argyrodites Li6PS5X (X = Cl, Br, and I) have attracted interest as fast solid ionic conductors for solid-state batteries. Within this class of materials, it has been previously suggested that more polarizable anions and larger substituents should influence the ionic conductivity (e.g., substituting S by Se). Building upon this work, we explore the influence of Sn substitution in lithium argyrodites Li6+xSnxP1–xSe5I in direct comparison to the previously reported Li6+xSnxP1–xS5I series. The (P5+/Sn4+)Se43/4– polyhedral volume, unit cell volume, and lithium coordination tetrahedra Li(48h)-(S/Se)3-I increase with Sn substitution in this new selenide series. Impedance spectroscopy reveals that increasing Sn4+ substitution results in a fivefold improvement in the ionic conductivity when compared to Li6PSe5I. This work provides further understanding of compositional influences for optimizing the ionic conductivity of solid electrolytes.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry