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

Abstract 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.