MgO nanoparticle-decorated <i>in situ</i> nitrogen-doped porous carbon hybrid materials as advanced sulfur hosts in Li–S batteries

Porous carbon combined with metal oxide modification shows great potential applications in lithium-sulfur batteries owing to various merits, including high encapsulation capacity for active sulfur, short transport path for lithium ions and good trapping capability of lithium polysulfides. Herein, inspired from waste biomass from passion fruit peels, an <i>in situ</i> nitrogen-doped porous carbon hybrid material decorated with MgO nanoparticles was designed and constructed <i>via</i> hydrothermal treatment and synchronous activation/carbonization method. The as-prepared porous carbon exhibited abundant pore structure with a notable large specific surface area of 2221.8 m² g^-1, mainly consisting of meso- and micro-pores. Even after modification with MgO nanoparticles, a high specific surface area of 1063.2 m² g^-1 was retained for sulfur loading and electrolyte penetration. In particular, the combination of rich pores, moderate MgO nanoparticles and nitrogen doping exhibited a good physicochemical synergistic effect for alleviating the shuttle dissolution of polysulfides. When the carbon hybrid material was evaluated as a sulfur host, the optimized battery delivered an initial discharge capacity of 792.5 mA h g^-1 at 0.2 C and a high reversible capacity of 668 mA h g^-1 after 200 cycles. Moreover, a stable long cycle performance of up to 1000 cycles was achieved at a high current rate of 1.0 C.