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

Abstract

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 Li₇P_2.9Sb_0.1S_10.75O_0.25 via chemical bond and structure regulation. Specifically, Li₇P_2.9Sb_0.1S_10.75O_0.25 is obtained by a Sb₂O₅ dopant to achieve partial Sb/P and O/S substitution. Benefiting from the strengthened oxysulfide structural unit of POS₃^3- and P₂OS₆^4- with bridging oxygen atoms and a distorted lattice configuration of the Sb-S tetrahedron, the Li₇P_2.9Sb_0.1S_10.75O_0.25 electrolyte exhibits prominent chemical stability and high ionic conductivity. Besides the improved air stability, the ionic conductivity of Li₇P_2.9Sb_0.1S_10.75O_0.25 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 Li₇P_2.9Sb_0.1S_10.75O_0.25 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.