As a promising anode for sodium-ion batteries (SIBs), cobalt sulfide ( CoS2) has attracted extensive attention due to its high theoretical capacity, easy preparation, and superior electrochemical activity. However, its intrinsic low conductivity and large volume expansion result in poor cycling ability. Herein, nitrogen-doped carbon-coated CoS2 nanoparticles (N–C@ CoS2) were prepared by a C3N4 soft-template-assisted method. Carbon coating improves the conductivity and prevents the aggregation of CoS2 nanoparticles. In addition, the C3N4 template provides a porous graphene-like structure as a conductive framework, affording a fast and constant transport path for electrons and void space for buffering the volume change of CoS2 nanoparticles. Benefitting from the superiorities, the Na-storage properties of the N–C@CoS2 electrode are remarkably boosted. The advanced anode delivers a long-term capacity of 376.27 mAh g− 1 at 0.1 A g− 1 after 500 cycles. This method can also apply to preparing other metal sulfide materials for SIBs and provides the relevant experimental basis for the further development of energy storage materials.

Soft-template-assisted synthesis of N-doping layered CoS2 nanoparticles as an advanced anode for sodium-ion batteries
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Materials preparation
        2.2 Structure and morphology characterization
        2.3 Electrochemical tests
    3 Result and discussion
        3.1 Characterization of N–C@CoS2 composite
        3.2 Sodium-ion storage performance
    4 Conclusions
    Anchor 12
    Acknowledgements 
    References

• Danyang Han(Hunan Institute of Science and Technology, Yueyang 414006, China, Key Laboratory of Hunan Province for Advanced Carbon‑Based Functional Materials, Hunan Institute of Science and Technology, Yueyang 414006, China)
• Guo Yu(Hunan Institute of Science and Technology, Yueyang 414006, China, Key Laboratory of Hunan Province for Advanced Carbon‑Based Functional Materials, Hunan Institute of Science and Technology, Yueyang 414006, China)
• An Liu(Hunan Institute of Science and Technology, Yueyang 414006, China)
• Gangyong Li(Hunan Institute of Science and Technology, Yueyang 414006, China, Key Laboratory of Hunan Province for Advanced Carbon‑Based Functional Materials, Hunan Institute of Science and Technology, Yueyang 414006, China)
• Wei Wang(Hunan Institute of Science and Technology, Yueyang 414006, China, Key Laboratory of Hunan Province for Advanced Carbon‑Based Functional Materials, Hunan Institute of Science and Technology, Yueyang 414006, China)
• Binhong He(Hunan Institute of Science and Technology, Yueyang 414006, China, Key Laboratory of Hunan Province for Advanced Carbon‑Based Functional Materials, Hunan Institute of Science and Technology, Yueyang 414006, China)
• Zhaohui Hou(Hunan Institute of Science and Technology, Yueyang 414006, China, Key Laboratory of Hunan Province for Advanced Carbon‑Based Functional Materials, Hunan Institute of Science and Technology, Yueyang 414006, China)
• Hong Yin(Hunan Institute of Science and Technology, Yueyang 414006, China, Key Laboratory of Hunan Province for Advanced Carbon‑Based Functional Materials, Hunan Institute of Science and Technology, Yueyang 414006, China,International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga, 4715‑330 Braga, Portugal)