Coal‐Based Hierarchically Porous Carbon Nanofibers as High‐Performance Anode for Sodium‐Ion Batteries

Sodium-ion batteries (SIBs) are considered one of the most promising alternatives to lithium-ion batteries (LIBs) due to the abundance of sodium resources. However, the deployment of SIBs is hindered severely by the lack of advanced electrode materials, especially anode materials. Herein, coal-based hierarchically porous carbon nanofibers (HPCCNFs) are prepared by a simple electrospinning coupled with activation method. The chemical activation gives HPCCNF-1 a micro/mesoporous integrated structure and appropriate specific surface area (2236.43 m(2) g(-1)), while expanding the carbon layer spacing to 0.386 nm, which facilitates ion and electron transport. The N doping not only creates external defects and active sites, but also increases the electrical conductivity of the material. When used as an anode material for SIBs, the HPCCNFs-1 exhibits excellent cycling stability (up to 1000 cycles) and good rate performance (121.7 mA h g(-1) at 5 A g(-1)). This work demonstrates that the coal-based carbon nanofibers can be a promising anode for building high-performance batteries.