New Li+ ion-conductive glasses Li2S-B2S3-Li4SiO4 were synthesized by rapid quenching, and they were transformed into glass ceramics by heat treatment. The heat treatment increased the ionic conductivities of the Li4SO4-doped glasses, and the highest ionic conductivity observed in the system was 1.0 x 10(-3) S cm(-1) at room temperature. The glass ceramics were highly stable against electrochemical oxidation with a wide electrochemical window of 10 V. (c) 2006 Elsevier B.V. All rights reserved.