Cobalt nanoparticles inlayed N-doped mesoporous carbon microspheres for high performance Lithium-Selenium battery

•NMC-Co is a mesoporous carbon microsphere consisting of carbon nanosheets.•Co nanoparticles obviously limited the dissolution and generation of polyselenide.•Carbon nanosheets can shorten ion transport and enhance electrochemical kinetics.•Se@NMC-Co has excellent rate capability of 462.0 mA h g−1 at 2C. To solve the volume expansion and the dissolution of high-order polyselenide of selenium cathode during discharge process, herein, a cobalt nanoparticles inlayed N-doped mesoporous carbon material (NMC-Co) consisting of carbon nanosheets was synthesized to apply as a selenium host for high performance Lithium-Selenium (Li-Se) battery. The obtained material with high specific surface area and high porosity has an excellent structure combining mesopores and inlayed cobalt nanoparticles, which provides favorable conditions for electrolyte infiltration and alleviation of cathode volume expansion, and also effectively restricts the generation and dissolution of polyselenide. As expected, when using NMC-Co as a host for the selenium cathode, Se50@NMC-Co loading with 50% of Se can deliver a high reversible capacity of 419.1 mA h g−1 at a current rate of 0.2C after 100 cycles (1C = 675 mA h g−1) and an excellent cycling stability of only 0.024% capacity decay per cycle after 200 cycles at 1C is demonstrated.