In situ growth of hexagonal prism-like Ni(OH)2 microrods on nickel foam as binder-free electrodes

In this paper, we report in situ growth of hexagonal prism-like Ni(OH)2 microrods via one-step hydrothermal process, where nickel foam is directly oxidized in a high concentration hydrogen peroxide (H2O2) solution without additional nickel sources, surfactant, or post-treatment. The nickel foam not only serves as a nickel source but also as 3D scaffold for Ni(OH)2 growth to form binder-free electrodes. The in situ growth can ensure close contact between conductive Ni foam substrate and as-formed Ni(OH)2 microrods, providing efficient electron collection paths and electrochemical stability. Mass loading of Ni(OH)2 on nickel foam could be tailored by adjusting the concentration H2O2. Possible growth mechanism of hexagonal prism-like Ni(OH)2 microrods is discussed to understand the morphologies under various H2O2 concentrations. When works as a binder-free electrode, the Ni(OH)2-coated nickel foam exhibits a remarkable areal capacitance ~ 1.598 C cm−2 (560 C g−1) at a current density of 1 mA cm−2, relatively high rate capability with 57.14% areal capacitance retained at 10 mA cm−2, as well as better cycling stability with 72.9% areal capacitance remained after 3000 charge-discharge cycles. Such superior performance demonstrates that Ni(OH)2 microrods in situ grown on metallic nickel foam substrate might be a potential electrode material for electrochemical capacitors.