Li+ conduction in air-stable Sb-Substituted Li4SnS4 for all-solid-state Li-Ion batteries

Abstract Development of new sulfide Li+ superionic conductors with mechanical sinterability is the key to the success of all-solid-state lithium batteries. While phosphorus-containing sulfide superionic conductor materials have been widely investigated, phosphorus-free materials showing good air-stability have been overlooked. Herein, the Li+ dynamics in Sb-substituted Li4SnS4 showing a high Li+ conductivity of max. 0.85 mS cm−1 at 30 °C and excellent dry-air stability as well as negligible H2S evolution is described. Structural analysis with X-ray and neutron diffraction reveals that Sb-substitution renders an expansion of the lattice volume and formation of Li vacancies. Additionally, 1D-preferable 3D Li+ diffusion channels in Li4-xSn1-xSbxS4 are disclosed. The fast Li+ diffusion in Li4-xSn1-xSbxS4 is rationalized by complementary analysis using AC impedance measurements, bond valence energy landscape calculation, and 7Li nuclear magnetic resonance spectroscopy. Excellent electrochemical performances of TiS2 electrodes employing Li3.85Sn0.85Sb0.15S4 in all-solid-state batteries are demonstrated.