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Carbon-based materials/metal hydroxide composite materials are one type of the most promising electrode materials for improving the performance of supercapacitors. They have the advantages of low cost, controllable morphology, high theoretical capacity, and excellent stability. In this study, nickel hydroxide nanosheets were grown vertically on the surface of carbon nanotubes (Ni(OH)2@CNTs) by a wet chemical method at low temperatures. The unique spatial configuration provides a larger specific surface area and exposes more electrochemically active sites, which is more conducive to improving electrochemical performance. The prominent conductivity of carbon nanotubes can quickly transfer electrons and improve the electrochemical cycling stability of the composite. The Ni(OH)2@CNTs composite exhibits excellent electrochemical performance with a specific capacitance of 1234 F g−1 at a current density of 1 A g−1 under a three-electrode system. In addition, an asymmetric supercapacitor (ASC) assembled using Ni(OH)2@CNTs as a cathode material shows an energy density of 65.63 W h kg−1 at a power density of 752.39 W kg−1 and a capacity retention rate of 85.9% after 10 000 cycles at a current density of 2 A g−1. The results indicate that Ni(OH)2@CNTs has prospects for application as a cathode material in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]