Hierarchical CoO@Ni(OH) ₂ core–shell heterostructure arrays for advanced asymmetric supercapacitors

Abstract

Abstract Constructing multicomponent electrode materials with a rational structure is an effective route to develop high-performance supercapacitors. We herein report a novel nickel-foam-supported hierarchical CoO@Ni(OH) 2 nanowire-nanosheet core–shell heterostructure array synthesized by a facile hydrothermal-electrodeposition strategy. The core CoO nanowire arrays with good electrical conductivity and shell Ni(OH) 2 nanosheets with thickness of ∼ 2 nm synergistically contributes to increased active sites, fast mass transfer, and improved structural stability. Consequently, the optimal CoO@Ni(OH) 2 –400 s architecture delivers a high specific capacitance of 1418.2 F g −1 at 1 A g −1 and 93.7% retention after 5000 cycles. Furthermore, the CoO@Ni(OH) 2 //activated carbon asymmetric supercapacitor could achieve an outstanding energy density of up to 92.47 W h kg −1 at 800 W kg −1 . This simple but effective strategy provides insight into the development of core–shell hierarchical architectures for constructing high-performance supercapacitors.