MgO nanoparticles decorated in-situ nitrogen doping porous carbon hybrid materials as advanced sulfur host in Li-S batteries

Porous carbon combined with metal oxides modification shows great potential applications in lithium sulfur batteries due to these merits including high encapsulation capacity for active sulfur, short transport path for lithium ions and good trapping capability of lithium polysulfides. Herein, inspired by waste biomass passion fruit peels, an in-situ nitrogen doping porous carbon hybrid material with MgO nanoparticles decoration is designed and constructed via hydrothermal treatment and synchronous activation/carbonization method. The as-prepared porous carbon exhibits abundant pore structure with notably large specific surface area of 2221.8 m²·g^-1, mainly consisting of meso- and micro-pores. Even with the MgO nanoparticles modification, a high specific surface area of 1063.2 m²·g^-1 is still retained for sulfur loading and electrolyte penetration. Especially the combination of rich pores, moderate MgO nanoparticles and nitrogen doping exhibits good physicochemical synergistic effect for well alleviating the shuttle dissolution of polysulfides. When the carbon hybrid material is evaluated as sulfur host, the optimized battery delivers an initial discharge capacity of 792.5 mAh·g^-1 at 0.2 C and a high reversible capacity of 668 mAh g^-1 after 200 cycles. Besides, a stable long cycle performance upto 1000 cycles is also achieved at a high current rate of 1.0 C.