Hybrid Composite Ni(OH)₂@NiCo₂O₄ Grown on Carbon Fiber Paper for High-Performance Supercapacitors

We have successfully fabricated and tested the electrochemical performance of supercapacitor electrodes consisting of Ni­(OH)₂ nanosheets coated on NiCo₂O₄ nanosheets grown on carbon fiber paper (CFP) current collectors. When the NiCo₂O₄ nanosheets are replaced by Co₃O₄ nanosheets, however, the energy and power density as well as the rate capability of the electrodes are significantly reduced, most likely due to the lower conductivity of Co₃O₄ than that of NiCo₂O_4. The 3D hybrid composite Ni­(OH)₂/NiCo₂O₄/CFP electrodes demonstrate a high areal capacitance of 5.2 F/cm² at a cycling current density of 2 mA/cm², with a capacitance retention of 79% as the cycling current density was increased from 2 to 50 mA/cm². The remarkable performance of these hybrid composite electrodes implies that supercapacitors based on them have potential for many practical applications