Sn-Substituted Sulfide Solid Electrolyte Prepared by Liquid-Phase Synthesis for All-Solid-State Batteries

Sulfide solid electrolytes (SEs) are widely regarded as one of the most promising candidates for practical all-solid-state batteries (ASSBs) owing to their high ionic conductivities and excellent deformability. However, sulfide SEs are vulnerable to moisture, resulting in the release of toxic H₂S gas and degradation in Li⁺ conductivity when exposed to ambient air. To improve the moisture stability, various compositions have been explored, and their common preparation method has been solid-state synthesis. While liquid-phase synthesis has the potential advantage for mass production, the poor solubility of metal chalcogenides (e.g., SnS₂ and GeS₂) has restricted the available composition to only metal-free ones. Recently, our group developed amine-thiol chemistry enabling liquid-phase syntheses of metal-containing sulfide SEs.<br/>In this presentation, we report Sn-substituted sulfide SEs derived via amine-thiol chemistry. The product SEs exhibit improved air-stability compared to conventional metal-free SEs. Mechanical properties of Sn-substituted sulfide SEs are also discussed. Finally, all-solid-state cell performances under practically meaningful conditions such as low pressures are presented.<br/><br/>[1] <i>Adv. Energy Mater</i>. <b>2018</b>, <i>8</i>, 1800035.<br/>[2] <i>Adv. Mater</i>. <b>2022</b>, 2200083.