The raw material selected for this research was Brazil chestnut shells (BCs), which were utilized to gain porous carbon as a positive electrode for lithium–sulfur batteries (LSBs). The effects of N/S co-doped on the electrochemical properties of porous carbon materials were studied using thiourea as nitrogen and sulfur sources. The experimental results indicate that the N/S co-doped carbon materials have a higher mesopore ratio than the undoped porous carbon materials. The porous carbon material NSPC-2 has a lotus-like structure with uniform pore distribution. The N and S doping contents are 2.5% and 5.4%. The prepared N/S co-doped porous carbon materials were combined with S, respectively, and three kinds of sulfur carbon composites were obtained. Among them, the composite NSPC-2/S can achieve the initial specific discharge capacity of 1018.6 mAh g− 1 at 0.2 C rate. At 1 C rate, the initial discharge capacity of the material is 730.6 mAh g− 1, and the coulomb efficiency is 98.6% and the capacity retention rate is 71.5% after 400 charge–discharge cycles.

The sulfur–nitrogen co-doped porous carbon material derived from biomass was employed as the anode of a lithium–sulfur battery
    Abstract
    1 Introduction
    2 Experiment
        2.1 Synthesis of carbon materials
        2.2 Preparation of sulfur–carbon composites
        2.3 Characterization
            2.3.1 Physical characterization
            2.3.2 Electrochemical characterization
    3 Results and discussion
        3.1 Physical characterization of OPC, NSPC-n, OPCS, and NSPC-nS (n = 1, 2, 3)
        3.2 Electrochemical performance of the OPCS and NSPC-nS
    4 Conclusion
    Acknowledgements 
    References

• Xiaobin Wang(School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China)
• Miaosen Niu(School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China)
• Chengwu Gao(School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China)
• Yu Li(School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China)
• Tao Li(School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China)
• Baozeng Ren(School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China)