One-step synthesized CoNi-embedded N-doped carbon nanotubes as sulfur host to synergistically immobilize the discharge products in lithium-sulfur batteries

Abstract

Nanostructured hollow carbon materials could be used as sulfur host in the cathode of lithium-sulfur batteries (LSBs) to effectively enhance the electronic conductivity, and simultaneously provide sufficient space to accommodate the volume change. However, owing to poor interaction between carbon materials and solid lithium sulfides, the cycling stability is still the main issue for its application. Herein, cobalt-nickel-embedded nitrogen-doped hollow carbon nanotubes (CoNi@NCNTs) with a micro/mesoporous structure and high surface area were fabricated through a facile one-step template-free carbonization method, which showed high Li2S6 adsorption ability with a sulfur content as high as 69.94%. When this sulfur incorporated CoNi@NCNTs (CoNi@NCNTs/S) was used as the cathode of LSBs, a capacity of 676.8 mA h g−1 was delivered at 1 C in the first cycle. After 500 cycles, the CoNi@NCNTs/S electrode still remained a capacity of 486 mA h g−1 with a retention of 71.8%, equivalent to a capacity decay as low as 0.056% per cycle, indicating good cyclic stability. This work can provide a potential strategy to develop high-performance cathode materials for LSBs through embedding metal nanoparticles into nanostructured hollow carbon materials.