70Li(2)S.(30-x)P2S5.xLi(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 Li7P3S11 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 Li3PO4 for P2S5, and the 70Li(2)S center dot 29P(2)S(5)center dot 1Li(3)PO(4) glass-ceramics exhibit the highest total conductivity of 1.87 x 10(-3) S cm(-1) at 25 degrees C and the lowest activation energy of 18 kJ mol(-1). The LiCoO2 in the all-solid-state cell of In-Lit 70Li(2)S center dot 29P(2)S(5)center dot 1Li(3)PO(4)/LiCoO2 exhibits a discharge capacity of 108 mAh g(-1), which is 20% higher than that in the In-Li/70Li(2)S center dot 30P(2)S(5)/LiCoO2 cell. The higher discharge capacity of the LiCoO2 electrode is attributed to the higher Li-Lion conductivity of the solid electrolyte and lower interface resistance of electrode-electrolyte. (C) 2015 Elsevier B.V. All rights reserved.