The performance of all-solid-state lithium sulfur (Li/S) batteries is investigated for some types of conductive materials. The surface area of the conductive material is found to have a greater influence on the battery performance compared with its electronic conductivity. All-solid-state Li/S cells prepared using a positive activated-carbon-based composite electrode exhibit an excellent cycling performance with a reversible capacity of over 1600 mAh g−1 after 100 cycles at 1.3 mA cm−2 (1C) at 25 °C. Furthermore, the positive composite electrode exhibits a high power density of over 11000 W kg−1 at 50% state of charge.