Hierarchical Ni(OH)2/Cu7S4@CuO heterostructure with enhanced conductivity for efficient hybrid supercapacitor

The high energy density and exceptional stable cyclicity are essential for practical applications of supercapacitors (SCs), which are extremely dependent on the electrode materials. In consideration of the large theoretical specific capacitance of Ni(OH)2 and its poor conductivity, herein, we constructed Ni(OH)2/Cu7S4 @CuO heterostructure (denoted as NCC) to make up for the imperfection and get the utmost out of the Ni(OH)2 material. The obtained Ni(OH)2/Cu7S4 @CuO heterostructure possesses a hierarchical topology and significantly lower charge transfer resistance compared with pristine Ni(OH)2, which undoubtedly offers a larger amount of active substances to participate in the charge-storing, thereby exhibiting superior energy-storage performance. The Ni(OH)2/Cu7S4 @CuO with 20 mg of Cu7S4 @CuO added in the preparation process (NCC-20) exhibits a marvelous specific capacity of 211.7 mA h g–1 (762.2 C g–1 or 1524.3 F g–1), superior to pristine Ni(OH)2 (101.4 mA h g–1, 365.0 C g–1 or 730.1 F g–1) at 1 A g–1. The NCC-20-containing hybrid supercapacitor (HSC) supplies an impressive energy density of up to 44.1 W h kg–1 at a high power density of 375.0 W kg–1 and maintains a capacity retention of 94.7% after 5000 cycles, demonstrating its promising applicability in supercapacitors. This research offers a rational way to make the utmost of the potential material in the energy-storage devices.