Li4-xSbxSn1-xS4 solid solutions for air-stable solid electrolytes

The sulfide solid electrolytes have the characteristics of high ionic conductivity and low grain boundary resistance, which make them suitable for bulk-type all-solid-state batteries. However, most of them suffer from poor stability in air. Here, we explore the air stable sulfide solid electrolytes in Li 4 SnS 4 -Li 3 SbS 4 system. The solid solutions of Li 4– x Sb x Sn 1– x S 4 (0 ≤  x  ≤ 0.5) can be formed in Li 4 SnS 4 -Li 3 SbS 4 system. Li 3.8 Sb 0.2 Sn 0.8 S 4 achieves the highest ionic conductivity of 3.5 × 10 −4  S cm −1 in this system, which is 5 times as that of Li 4 SnS 4 and 3 orders of magnitude higher than that of Li 3 SbS 4 , respectively. Li 3.8 Sb 0.2 Sn 0.8 S 4 crystallizes into the same structure with high ionic conductivity phase of β -Li 3 PS 4 . Moreover, Li 3.8 Sb 0.2 Sn 0.8 S 4 owns good stability in humid air . Matching with LiCoO 2 and Li 4 Ti 5 O 12 , Li 3.8 Sb 0.2 Sn 0.8 S 4 exhibits the potential to be applied in all-solid-state batteries.