A High-Energy-Density Hybrid Supercapacitor with P-Ni(OH)2@Co(OH)2Core-Shell Heterostructure and Fe2O3Nanoneedle Arrays as Advanced Integrated Electrodes

Transition metal hydro/oxides (TMH/Os) are treated as the most promising alternative supercapacitor electrodes thanks to their high theoretical capacitance due to the various oxidation states and abundant cheap resources of TMH/Os. However, the poor conductivity and logy reaction kinetics of TMH/Os severely restrict their practical application. Herein, hierarchical core-shell P-Ni(OH)(2)@Co(OH)(2)micro/nanostructures are in situ grown on conductive Ni foam (P-Ni(OH)(2)@Co(OH)(2)/NF) through a facile stepwise hydrothermal process. The unique heterostructure composed of P-Ni(OH)(2)rods and Co(OH)(2)nanoflakes boost the charge transportation and provide abundant active sites when used as the intergrated cathode for supercapacitors. It delivers an ultrahigh areal specific capacitance of 4.4 C cm(-2)at 1 mA cm(-2)and the capacitance can maintain 91% after 10 & x202f;000 cycles, showing an ultralong cycle life. Additionally, a hybrid supercapacitor composed with P-Ni(OH)(2)@Co(OH)(2)/NF cathode and Fe2O3/CC anode shows a wider voltage window of 1.6 V, a remarkable energy density of 0.21 mWh cm(-2)at the power density of 0.8 mW cm(-2), and outstanding cycling stability with about 81% capacitance retention after 5000 cycles. This innovative study not only supplies a newfashioned electronic apparatus with high-energy density and cycling stability but offers a fresh reference and enlightenment for synthesizing advanced integrated electrodes for high-performance hybrid supercapacitors.