Three-dimensional Co₉S₈ nanotube network/sulfur composite cathode with enhanced lithium-sulfur battery performance

The poor conductivity of sulfur and the 'shuttle effect' of polysulfide intermediates have hindered the development of next generation lithium-sulfur (Li-S) batteries with high energy and low consumption. Herein, novel Co₉S₈-S composite nanotubes are developed to efficiently alleviate the above-mentioned problems. Experiments and theoretical calculations show that Co₉S₈ has strong adsorption on soluble polysulfides. This not only restrains polysulfides diffusion and ensures their utilization, but also enhances the intimate contact between the active materials and the conductive substrates to promote the kinetics of conversion reactions. The three-dimensional (3D) conductive network with a high surface area formed by interlinking Co₉S₈ nanotubes further improves the electronic conductivity of the composite cathode. As a result, the Co₉S₈-S cathode shows a high capacity of 1153 mAh g^-1. After 500 cycles, a high capacity of 462 mAh g^-1 (2 C) is demonstrated with a negligible capacity decay of ~0.04% per cycle.