Development of sulfide glass-ceramic electrolytes for all-solid-state lithium rechargeable batteries

Development of Li2S-P2S5-based glass-ceramic electrolytes is reviewed. Superionic crystals of Li7P3S11 and Li3.25P0.95S4 were precipitated from the Li2S-P2S5 glasses at the selected compositions. These high temperature or metastable phases enhanced conductivity of glass ceramics up to over 10(-3) S cm(-1) at room temperature. The original (or mother) glass electrolytes itself showed somewhat lower conductivity of 10(-4) S cm(-1) and have important role as a precursor for obtaining the superionic crystals, which were not synthesized by a conventional solid-state reaction. The substitution of P2O5 for P2S5 at the composition 70Li(2)S center dot 30P(2)S(5) (mol%) improved both conductivity and electrochemical stability of glass-ceramic electrolytes. The all-solid-state In/LiCoO2 cell using the 70Li(2)S center dot 27P(2)S(5)center dot 3P(2)O(5) (mol%) glass-ceramic electrolyte showed initial capacity of 105 mAh g(-1) (gram of LiCoO2) at the current density of 0.13 mA cm(-2) and exhibited higher electrochemical performance than that using the 70Li(2)S center dot 30P(2)S(5) glass-ceramic electrolyte.