Improving the Stability of 75Li2S<middle dot>25P2S5 Glass-Ceramic Electrolytes Against Lithium Metals Through Li2O Doping

The chemical and electrochemical stability between solid-state electrolytes (SSEs) and lithium metals is one of the crucial factors in the performance of all-solid-state lithium batteries (ASSLBs). Doping modification has been shown to improve the ionic conductivity and air stability of SSEs, but further research is needed to demonstrate its effectiveness in enhancing stability with lithium metal. In this work, a series of Li2O-doped 75Li(2)S<middle dot>25P(2)S(5) glass-ceramic electrolytes have been successfully synthesized using ball milling method. Powder X-ray diffraction (pXRD) and Li-7 magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy results revealed that Li2O doping effectively reduced the percentage of residual Li2S in the ball milling stage and generated a high ionic conductivity phase Li7P3S11 during annealing. The electrolyte has the highest ionic conductivity (1.5 x 10(-4) S cm(-1) at room temperature) when doped with 1 mol% Li2O. Various electrochemical characterizations have shown that all doped electrolytes can effectively slow/suppress lithium dendrite formation while being chemically and electrochemically stable to some extent. Among these, 1 mol% Li2O-doped electrolyte performs the best, as the Li|1Li(2)O|Li cell maintains voltage and resistance nearly unchanged after 1000 h and 900 cycles, with no noticeable degradation in the material structure.