MoS2 loaded cotton stalk based porous carbon with high N content improves the electrochemical performance of Li-S batteries

The high-performance composite material of C/S with N-doping and MoS2 loaded is prepared using cotton stalks as precursors. The intrinsic mechanism of N doping and loaded MoS2 for improving battery performance was investigated. Both addition of N and MoS2 can increase the graphitization degree, reducing the specific surface area and pore volume of porous carbon. The combination of both has a synergistic effect on enhancing the graphitization degree and increasing the content of N and MoS2 in porous carbon. However, it also demonstrates a stronger inhibition for the specific surface area and pore volume by limiting the development of pore structure below 10 nm. In terms of electrochemical performance, co-addition of N and MoS2 can better improve the electrochemical performance, which further reduce the internal polarization and increase the diffusion rate of lithium ions. The specific capacity was retained of 694.8 mAhg-1 after 100 cycles at 0.5C, which increase 43.08 % and 27.60 % compared with single N doping and loaded MoS2, respectively. Even at a high current of 2C, it still shows a high specific capacity of 719.6 mAhg- 1 . By characterization the cathode after the cycle test completed, the porous carbon prepared by co-addition of N and MoS2 has higher catalytic activity for the conversion of polysulfide. Higher content of N and MoS2 and excellent degree of graphitization in porous carbon after co-addition are key factors for improved performance.