Influence of Glass Former Ratio on Ionic Transport and Electrochemical Stability of LiCl-Substituted Li₂S-Sb₂S₃-GeS₂ Glass Electrolytes

We report a LiCl-substituted Li₂S–Sb₂S₃–GeS₂-based glass electrolyte, LiSb₀.₈₃₃GeS₃.₅Cl₀.₅, synthesized via mechanochemical processing and thermal annealing. Structural analyses confirm a fully amorphous framework composed of [SbS₃]³¯ and [GeS₄]⁴¯ units with embedded Li₂S and LiCl glass modifiers. Compared to the parent LiSbGeS₄ electrolyte, LiSb₀.₈₃₃GeS₃.₅Cl₀.₅ exhibits significantly enhanced Li-ion conductivity (6.43 × 10¯⁴ S·cm¯¹ at 30 °C), a low activation energy of 0.22 eV, and a widened electrochemical stability window of 0.30–2.40 V vs. In/InLi. A comparative study with LiSbGe₀.₈₇₅S₃.₅Cl₀.₅​ reveals that, beyond LiCl substitution, the relative ratio of Sb₂S₃ and GeS₂ critically governs the balance between Li-ion transport and electrochemical stability by modulating glass network softness and redox stability. These findings establish a compositional design strategy for phosphorus-free sulfide glass electrolytes that reconciles high ionic conductivity with improved chemical and electrochemical robustness for all-solid-state lithium batteries.