Sn Substitution in the Lithium Superionic Argyrodite Li6PCh5I (Ch = S and Se)

• Published in: Inorganic chemistry Vol. 60; no. 24; pp. 18975 - 18980
• Main Authors: Gautam, Ajay, Ghidiu, Michael, Hansen, Anna-Lena, Ohno, Saneyuki, Zeier, Wolfgang G
• Format: Journal Article
• Language: English
• Published: American Chemical Society 20.12.2021
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.1c02813

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+x Sn x P1–x Se5I in direct comparison to the previously reported Li6+x Sn x P1–x S5I series. The (P5+/Sn4+)­Se4 3/4– 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.