NiO/Ni_xCo_3−xO₄ porous ultrathin nanosheet/nanowire composite structures as high-performance supercapacitor electrodes

Abstract

The demand for a new generation of high-safety, long-lifespan, and high-capacity power sources increases rapidly with the growth of energy consumption in the world. Here we report a facile method for preparing architecture materials made of NiO/Ni x Co 3Àx O 4 porous nanosheets coupled with NiO/Ni x Co 3Àx O 4 porous nanowires grown in situ on nickel foams using a hydrothermal method without any binder followed by a heat treatment process. The nanosheet-shaped NiO/Ni x Co 3Àx O 4 species in the nanosheet matrix function well as a scaffold and support for the dispersion of the Ni x Co 3Àx O 4 nanowires, resulting in a relatively loose and open structure within the electrode matrix. Among all composite electrodes prepared, the one annealed in air at 300 C displays the best electrochemical behavior, achieving a specific capacitance of 270 mF cm À2 at 5 mA cm À2 while maintaining excellent stability (retaining z 89% of the max capacitance after 20 000 cycles), demonstrating its potential for practical application in power storage devices. Fig. 2 (a) XPS survey spectrum, (b) the high-resolution XPS spectrum of Ni 2p, (c) the high-resolution XPS spectrum of Co 2p, and (d) XPS spectrum of O 1s for the NiO/Ni x Co 3Àx O 4 nanostructures.This journal is

One‐dimensional and two‐dimensional synergized nanostructures for high‐performing energy storage and conversion

“…As hydrothermal/solvothermal synthesis has been briefly introduced in Section 3.1, it will not be further discussed in detail. Briefly, for example, cactus‐like 1D‐2D synergized nanostructures have been grown on conductive substrates by hydrothermal preparations of Ni precursors, Co precursors, and NiCo precursors . Following proper posttreatments, the corresponding oxides, phosphides, and sulfides are synthesized.…”

“…Consequently, the unusual cactus‐like nanostructure showed a larger electroactive surface area and superior electrochemical properties, rendering the NiCo 2 S 4 nanosheet arrays with self‐decorated nanoneedles a promising electrode material for high‐performing SCs . Besides, binder‐free electrodes composed of Co(OH) 2 nanoflakes/nanorods, and cobalt‐doped nickel oxide nanosheets/nanowires composite also have been constructed successfully by the one‐step hydrothermal process. Such a simple and economical synthetic strategy would open new doors for the development of a series of high‐quality nickel/cobalt‐based materials and offer potential applications for SCs with high performance.…”