Ni–Co-Based Nanowire Arrays with Hierarchical Core–Shell Structure Electrodes for High-Performance Supercapacitors

Pseudocapacitors and redox capacitors have become the most promising candidates for high-energy and high-power energy storage applications due to their excellent quick charge/discharge capacity and cyclic stability. Because the controllable construction of hierarchical structures would promote the single contribution of pure materials, and the formation of an interface between structures can enhance the electrochemical performance of supercapacitors, a high-performance nickel foam@NiCo2O4@Ni(OH)2 supercapacitor electrode has been fabricated via a facile hydrothermal route in this work. Besides, density functional theory calculations were performed to explore the distinct diffusion and binding capabilities between the cobalt and nickel species. The as-prepared NiCo2O4@Ni(OH)2 electrode possesses unexceptionable electrochemical pseudocapacitive performance including a remarkable specific capacitance (3.5 F cm–2 at a current density of 1 mA cm–2 or 2356 F g–1 at a current density of 0.67 A g–1), high rate performance (64.0% retention at a current density of 20 mA cm–2), and high cycling stability (94.1% retention after 5000 cycles). This study developed a method for designing a high-performance nickel foam@NiCo2O4@Ni(OH)2 supercapacitor electrode, which has certain guiding significance for the research of electrochemical energy storage and conversion.