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 degrees 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 Li-7 nuclear magnetic resonance spectroscopy. Excellent electrochemical performances of TiS2 electrodes employing Li3.85Sn0.85Sb0.15S4 in all-solid-state batteries are demonstrated.