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

Abstract

• The dissolution of lithium polysulfides is effectively alleviated. • CNTs improve the conductivity of S/FeS 2 @CNTs composites. • Low capacity decay rate of 0.024% per cycle for over 500 cycles is obtained. 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/FeS 2 @Carbon nanotubes (S/FeS 2 @CNTs) microspheres by loading sulfur into FeS 2 @CNTs microspheres with carbon nanotubes entangling hollow FeS 2 microspheres. The hollow S/FeS 2 @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/FeS 2 @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 FeS 2 , as well as the volume expansion of the cathode can be alleviated by the internal void space.