Free-Standing N-Doped Porous Carbon Fiber Membrane Derived From Zn–MOF-74: Synthesis and Application as Anode for Sodium-Ion Battery With an Excellent Performance

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.