Design of carbon@WS₂ host with graham condenser-like structure for tunable sulfur loading of lithium-sulfur batteries

Despite significant progress has been achieved regarding the shuttle-effect of lithium polysulfides, the suppressed specific capacity and retarded redox kinetics under high sulfur loading still threat the actual energy density and power density of lithium-sulfur batteries. In this study, a graham condenser-inspired carbon@WS₂ host with coil-in-tube structure was designed and synthesized using anodic aluminum oxide (AAO) membrane with vertically aligned nanopores as template. The vertical array of carbon nanotubes with internal carbon coils not only leads to efficient charge transfer across through the thickness of the cathode, but also provides significant confinement to polysulfide diffusion towards both the lateral and longitudinal directions. Few-layer WS₂ in the carbon coils perform a synergistic role in suppressing the shuttle-effect as well as boosting the cathodic kinetics. As a result, high specific capacity (1180 mAh/g at 0.1 C) and long-cycling stability at 0.5 C for 500 cycles has been achieved at 3 mg_S/cm². Impressive areal capacity of 7.4 mAh/cm² has been demonstrated when the sulfur loading reaches 8.4 mg/cm². The unique coil-in-tube structure developed in this work provides a new solution for high sulfur loading cathode towards practical lithium-sulfur batteries.