Super-Hydrophilic Coal-Based Carbon Fibers as Flexible Electrodes for Supercapacitors

Carbon nanofibers (CNFs) are a popular choice for independent electrode materials in supercapacitors (SCs) because of their high conductivity, chemical resistance, and exceptional electrochemical stability. However, these fibers often lack surface area and activity due to their inert surfaces. This study introduces a facile method for synthesizing an oxygen-rich coal-based carbon fiber film (OCNFs-x) using electrospinning and HNO3-assisted treatment, which addresses these issues. The resulting materials have an optimal distribution of pore structure and oxygen-containing functional groups, which gives rise to a remarkable capacitance of 252 F/g at a current density of 1 A/g and an excellent cycling performance. For a current density of 2 A/g, the rate of capacity retention is almost 100% over the course of 10,000 cycles. In addition, the assembled symmetric SC shows a remarkable energy density of 6.8 Wh/kg for a power density of 125 W/kg. OCNFs-2 has impressive electrochemical performance that can guide the design of superior electrode materials for high-performance SCs by improving the pore architecture and surface modifications in active carbon fibers.