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It is important to develop new energy storage and conversion technology to mitigate the energy crisis for the sustainable development of human society. In this study, free-standing porous nitrogen-doped carbon fiber (PN-CF) membranes were obtained from the pyrolysis of Zn–MOF-74/polyacrylonitrile (PAN) composite fibers, which were fabricated in situ by an electrospinning technology. The resulting free-standing fibers can be cut into membrane disks and directly used as an anode electrode without the addition of any binder or additive. The PN-CFs showed great reversible capacities of 210 mAh g−1 at a current density of 0.05 A g−1 and excellent cyclic stability of 170.5 mAh g−1 at a current density of 0.2 A g−1 after 600 cycles in sodium ion batteries (SIBs). The improved electrochemical performance of PN-CFs can be attributed to the rich porous structure derived by the incorporation of Zn–MOF-74 and nitrogen doping to promote sodium ion transportation.

BACKGROUND Graphene and carbon nanofibers have shown outstanding advantages as anode materials in lithium‐ion batteries (LIBs) because of their prominent electronic conductivity, outstanding flexibility, high theoretical specific capacity, high specific surface, and chemical durability. Free‐standing nanocomposite mats from graphene and carbon nanofibers, without any conductive additive and binder, could improve the weight energy density of the LIBs. RESULTS Nitrogen‐doped carbon fiber‐reduced graphene oxide (NCNFs‐rGO) mats are fabricated by high‐temperature thermal treatment of graphene oxide/polyacrylonitrile (PAN‐GO) nanofiber composite mats via a simple electrospinning method. The resultant free‐standing NCNFs‐rGO mats which were systematically characterized by scanning electron microscopy, X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, and electrochemical properties as an anode for LIBs were also measured. Without any conductive additive and binder, the resultant free‐standing NCNFs‐rGO mats were directly used as an anode material in LIBs. CONCLUSION The LIBs with NCNFs‐rGO mats as anodes exhibited a high rate capability and long cycle stability owing to the structural integrity and highly electrical conductivity. © 2019 Society of Chemical Industry