Nickel–Cobalt Hydroxide Nanosheets Coated on NiCo2O4 Nanowires Grown on Carbon Fiber Paper for High-Performance Pseudocapacitors

Abstract

A series of flexible nanocomposite electrodes were fabricated by facile electro-deposition of cobalt and nickel double hydroxide (DH) nanosheets on porous NiCo₂O₄ nanowires grown radially on carbon fiber paper (CFP) for high capacity, high energy, and power density supercapacitors. Among different stoichiometries of Co_xNi_1–xDH nanosheets studied, Co_0.67Ni_0.33 DHs/NiCo₂O₄/CFP hybrid nanoarchitecture showed the best cycling stability while maintaining high capacitance of ∼1.64 F/cm² at 2 mA/cm². This hybrid composite electrode also exhibited excellent rate capability; the areal capacitance decreased less than 33% as the current density was increased from 2 to 90 mA/cm², offering excellent specific energy density (∼33 Wh/kg) and power density (∼41.25 kW/kg) at high cycling rates (up to150 mA/cm²).