Congener Substitution Reinforced Li₇P_2.9Sb_0.1S_10.75O_0.25 Glass-Ceramic Electrolytes for All-Solid-State Lithium–Sulfur Batteries

Glass-ceramic sulfide solid electrolytes like Li7P3S11 are practicable propellants for safe and high-performance all-solid-state lithium–sulfur batteries (ASSLSBs); however, the stability and conductivity issues remain unsatisfactory. Herein, we propose a congener substitution strategy to optimize Li7P3S11 as Li7P2.9Sb0.1S10.75O0.25 via chemical bond and structure regulation. Specifically, Li7P2.9Sb0.1S10.75O0.25 is obtained by a Sb2O5 dopant to achieve partial Sb/P and O/S substitution. Benefiting from the strengthened oxysulfide structural unit of POS33– and P2OS64– with bridging oxygen atoms and a distorted lattice configuration of the Sb–S tetrahedron, the Li7P2.9Sb0.1S10.75O0.25 electrolyte exhibits prominent chemical stability and high ionic conductivity. Besides the improved air stability, the ionic conductivity of Li7P2.9Sb0.1S10.75O0.25 could reach 1.61 × 10–3 S cm–1 at room temperature with a wide electrochemical window of up to 5 V (vs Li/Li+), as well as good stability against Li and Li–In alloy anodes. Consequently, the ASSLSB with the Li7P2.9Sb0.1S10.75O0.25 electrolyte shows high discharge capacities of 1374.4 mAh g–1 (0.05C, 50th cycle) at room temperature and 1365.4 mAh g–1 (0.1C, 100th cycle) at 60 °C. The battery also presents remarkable rate performance (1158.3 mAh g–1 at 1C) and high Coulombic efficiency (>99.8%). This work provides a feasible technical route for fabricating ASSLSBs.