Fishnet-like double active layer-loaded carbon fiber for electrical double-layer capacitors

The rational design and controllable synthesis of high-performance energy storage materials are important measures to address the growing demand for energy storage devices. This work involves the growth of a fishnet-like Fe₂O₃ nanorod@oxygen-rich carbon layer structure directly onto carbon fiber cloth as a binder-free electrode for symmetric capacitors. The growth of Fe₂O₃ nanorods provided a large specific surface area, and the coating of an oxygen-rich carbon layer protected the Fe₂O₃ nanorods as an active substance. Furthermore, oxidation treatment created rich electrochemically active sites by loading oxygen-containing functional groups onto the composite surface. As a result, the optimal OC@Fe₂O₃-ACC sample exhibited a high areal specific capacitance of 1687 mF cm⁻² at a current density of 1 mA cm⁻². Meanwhile, an excellent capacity retention rate of 58.7% was achieved at 15 mA cm⁻². Finally, the long-term cycling stability was verified with an 80% retention rate of the initial capacitance after 12 000 cycles.