Nitrogen-doped carbon–cobalt-modified MnO nanowires as cathodes for high-performance lithium sulfur batteries

Abstract

The shuttle effect and slow redox reaction kinetics of Li–S batteries due to the dissolution of lithium polysulfides (LiPSs) during charging and discharging lead to a remarkable decrease in the cycle life and sulfur utilization of Li–S batteries. In this paper, MnO 2 nanowires were embedded in ZIF-67 by polyvinylpyrrolidone modification and then carbonized at high temperature to obtain N -doped carbon (NC)-Co@MnO composites with high specific surface area and mesoporous structure for high sulfur loading. This conductive network structure provides a strong conductive pathway for LiPSs, promotes the adsorption of LiPSs, effectively facilitates electron transport, and enhances the trapping ability of LiPSs in the cathode. The prepared NC-Co@MnO@S cathode has excellent electrochemical performance and stable charge–discharge performance because of the combination of the high conductivity of NC-Co with high specific surface area, as well as the strong interaction between MnO and polysulfide. The initial discharge specific capacity was 1175 mAh/g. The NC-Co@MnO@S composite can still maintain a stable discharge capacity of 700 mAh/g after 200 cycles at a current density of 0.2 C with a capacity retention rate of 72%. This composite material has great promise for application as a low-cost, high-performance electrode for Li–S batteries.