Three-dimensionally interconnected Co9S8/MWCNTs composite cathode host for lithium–sulfur batteries

Several challenging issues, such as the poor conductivity of sulfur, shuttle effects, large volume change of cathode, and the dendritic lithium in anode, have led to the low utilization of sulfur and hampered the commercialization of lithium–sulfur batteries. In this study, a novel three-dimensionally interconnected network structure comprising Co9S8 and multiwalled carbon nanotubes (MWCNTs) was synthesized by a solvothermal route and used as the sulfur host. The assembled batteries delivered a specific capacity of 1154 mA h g−1 at 0.1 C, and the retention was 64% after 400 cycles at 0.5 C. The polar and catalytic Co9S8 nanoparticles have a strong adsorbent effect for polysulfide, which can effectively reduce the shuttling effect. Meanwhile, the three-dimensionally interconnected CNT networks improve the overall conductivity and increase the contact with the electrolyte, thus enhancing the transport of electrons and Li ions. Polysulfide adsorption is greatly increased with the synergistic effect of polar Co9S8 and MWCNTs in the three-dimensionally interconnected composites, which contributes to their promising performance for the lithium–sulfur batteries.