Honeycomb-like nitrogen and sulfur dual-doped hierarchical porous biomass carbon bifunctional interlayer for advanced lithium-sulfur batteries

Abstract The nitrogen and sulfur dual-doped hierarchical porous biomass carbon (NSHPC) is prepared by a simple and environment-friendly one-step method and employed as flexible interlayer for lithium-sulfur batteries (LSBs). The composition analysis and structure characteristic of NSHPC sample are measured by X-ray powder diffraction, scanning electron microscopy and Raman spectra. The electrochemical performances are measured by galvanotactic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurement. The results show that the NSHPC sample with unique honeycomb-like micro/mesoporous structure possesses high specific surface area of 2543.8 m2 g−1 and large pore volume of 2.14 cm3 g−1. The charge transfer resistance (Rct) of the LSBs with the NSHPC flexible interlayer is much smaller than that of the LSBs with only Celgard separator. The pure sulfur cathode using NSHPC flexible interlayer can exhibit a high initial discharge capacity of 1549 mAh g−1 at 0.1 C. The good cycle performance and high discharge capacity are mainly owing to the honeycomb-like porous structure and the electrostatic repulsion between lithium polysulfides (LiPSs) and nitrogen and sulfur dual-doping of NSHPC flexible interlayers. The using of NSHPC flexible interlayer to modify the Celgard separator can availably reduce the charge transfer resistance and increase electrostatic repulsion to LiPSs, and further enhancing the performance of LSBs.