We report the template-directed synthesis of sulphur–carbon nanotubes and their use to form a membrane that is binder-free, highly conductive and flexible. This nanostructured membrane is used as a self-supporting cathode without metal current-collectors for Li-S batteries. The membrane cathode has a high electrical conductivity and renders a long life of sulphur of over 100 charge–discharge cycles. High discharge capacity of sulphur was attained at 712 mA h gsulphur−1 (23 wt% S) and 520 mA h gsulphur−1 (50 wt% S) at a high current density (6 A gsulphur−1). The overall capacity of the flexible cathode correspondingly reaches 163 mA h g−1 (23 wt% S) and 260 mA h g−1 (50 wt% S). These results demonstrate the great potential of this nanostructured flexible membrane as a cathode for Li-S batteries with fast charge–discharge performance and long life.