Li3PO4-doped Li7P3S11 glass-ceramic electrolytes with enhanced lithium ion conductivities and application in all-solid-state batteries

70Li 2 S·(30- x )P 2 S 5 · x Li 3 PO 4 (mol%) amorphous powders are prepared by a high-energy ball milling technique, and the glass-ceramics are obtained by the crystallization of as-prepared amorphous samples. The XRD patterns show that a crystalline phase with a Li 7 P 3 S 11 structure is obtained for x  ≤ 3, while a structure change is observed for x  = 5. The Li + -ion conductivity is enhanced by the substitution of Li 3 PO 4 for P 2 S 5 , and the 70Li 2 S·29P 2 S 5 ·1Li 3 PO 4 glass-ceramics exhibit the highest total conductivity of 1.87 × 10 −3  S cm −1  at 25 °C and the lowest activation energy of 18 kJ mol −1 . The LiCoO 2 in the all-solid-state cell of In-Li/70Li 2 S·29P 2 S 5 ·1Li 3 PO 4 /LiCoO 2 exhibits a discharge capacity of 108 mAh g −1 , which is 20% higher than that in the In-Li/70Li 2 S·30P 2 S 5 /LiCoO 2 cell. The higher discharge capacity of the LiCoO 2 electrode is attributed to the higher Li + -ion conductivity of the solid electrolyte and lower interface resistance of electrode–electrolyte.