One-Step and Morphology-Controlled Synthesis of Ni-Co Binary Hydroxide on Nickel Foam for High-Performance Supercapacitors

Ni-Co binary hydroxide grown on nickel foam was synthesized through a facile one-step process for pseudocapacitive electrode application. The morphology of the fabricated binary hydroxide, evolving from nanosheet to nanowire, was highly controllable by tuning the Ni:Co ratio. In systematical electrochemical measurements, the prepared binary material on nickel foam could be employed as a binder-free working electrode directly. The optimal composition obtained at the Ni:Co ratio of 5:5 in integrated nanosheet/nanowire geometry exhibited high specific capacitances of 2807 and 2222 F/g at current densities of 1 and 20 A/g, equivalent to excellent rate capability. The capacitance loss was 19.8% after 2000 cycles, demonstrating good long-term cyclic stability. The outstanding supercapacitors behaviors benefited from unique structure and synergistic contributions, indicating the great potential of the obtained binary hydroxide electrode for high-performance energy storage devices.