Leaf-like interconnected network structure of MWCNT/Co9S8/S for lithium-sulfur batteries

Lithium-sulfur batteries have several disadvantages, such as intrinsic insulation of sulfur and Li2S, large volume expansion, and inevitable shuttle effect, which lead to low utilization of active materials and rapid capacity decay. Herein, leaf-like interconnected network structure of MWCNT/Co9S8 was synthesized by a simple hydrothermal method. The MWCNT/Co9S8/S delivers a high specific capacity and good cycling stability. The initial discharge capacity of MWCNT/Co9S8/S is 1124 mAh g−1 and retains at 503 mAh g−1 after 100 cycles at 0.1 C. The improved electrochemical performance of MWCNT/Co9S8/S could be attributed to the interconnected network MWCNT and polar Co9S8. As conductive skeletons, the interconnected network structure of MWCNT midribs provide fast conduction paths for electron and additional space for volume expansion of sulfur. Furthermore, sulfur particles well-distributed on the MWCNT/Co9S8 scaffold facilitate Li+ ions storage and release for energy delivery, which is beneficial to excellent activation of sulfur and high rate capacity. In addition, the polar Co9S8 leaves provide strong binding sites to trap polar polysulfide intermediates, which can suppress the shuttle effect effectively.