Hierarchical Carbon Nanofibers®Nickel Phosphide Nanoparticles for High-Performance Supercapacitors

The design and synthesis of novel active materials as the capacitor electrodes is of great significance to fabricate high-performance supercapacitors, namely those with large and stable capacitances as well as high power and energy densities. Herein, binder-free and hierarchical carbon nanofibers@nickel phosphide nanoparticles are grown in a chemical vapor deposition reactor, where Ni5TiO7 nanowires and a TiO2 outer layer are in situ converted into interconnected nickel phosphide nanoparticles and a TiC layer, respectively. The initially formed hierarchical nickel phosphide nanoparticles boost the catalytic growth of CNFs, leading to the generation of a 3D interconnected texture, which features a high specific surface area and excellent conductivity. The combination of this nanocomposite as a capacitor electrode with redox electrolyte of 0.05 M Fe(CN)(6)(3-/4-) generates a specific capacitance of 59.3 mF cm(-2) at a current density of 5 mA cm(-2) . This capacitor electrode exhibits 95% of its initial capacitance even after 10 000 charging/discharging cycles. The asfabricated supercapacitor device offers an energy density of as high as 27.4 Wh kg(-1) accompanied with a power density of 7.25 kW kg(-2). The proposed method thus provides an approach to produce binder-/current-collector-free capacitor electrodes, which can be utilized to fabricate high-performance supercapacitors.