Synthesis of hollow S/FeS2@carbon nanotubes microspheres and their long-term cycling performances as cathode material for lithium-sulfur batteries

The lithium-sulfur batteries as a promising next-generation rechargeable battery are practically limited by their poor long-term cycling performance originating from the dissolution of lithium polysulfides. Combining physical and chemical interactions to trap lithium polysulfides is an effective way to improve the long-term cycling performance. Herein we have synthesized the hollow S/FeS2@Carbon nanotubes (S/FeS2@CNTs) microspheres by loading sulfur into FeS2@CNTs microspheres with carbon nanotubes entangling hollow FeS2 microspheres. The hollow S/FeS2@CNTs microspheres working as cathode for lithium-sulfur batteries have delivered initial discharge capacity of 1245 mA h g−1 at 0.2 C. Particularly, the long-term cycling performance has been achieved that the capacity beyond 440.2 mA h g-1 can maintain for 500 cycles at 1 C, with a low capacity decay rate of 0.024 % per cycle. The significantly improved cycling performance of S/FeS2@CNTs can be attributed to the synergistic effects that the dissolution of lithium polysulfides diminishes by combining the physical interaction of CNTs with chemical absorption of FeS2, as well as the volume expansion of the cathode can be alleviated by the internal void space.