Abstract: An interlayer made of a multi-wall carbon nanotube (MWCNT)/dithiothreitol (DTT) composite was placed between the positive electrode and the separator of a Li-S battery, where DDT was used as the reducing agent of lithium polysulfides, and MWCNTs as the reinforcement and diffusion barrier to inhibit the shuttling of lithium polysulfides. Results indicate that the formation of lithium polysulfides was inhibited and their diffusion to the negative electrode was reduced. The discharge capacity, utilization rate of the active substances, and rate and cycling performance of the Li-S battery were substantially improved. The initial discharge capacity of the battery was 1 674 mAh/g at 0.2 C and the utilization rate of active substances reached 99.9%. The initial discharge capacities were 1 094, 597 and 214 mAh/g at 1, 5 and 10 C, respectively. The discharge capacity was 780 mAh/g at 1 C after 300 cycles, which was 71.3% of its initial capacity.