Electrochemical activation fabrication towards high-capacity nickel hydroxide electrode

Highlights: • The electrochemical activation of Ni(OH)₂ was investigated. • A wet treatment was proposed to fabricate Ni(OH)₂/Ni foam. • The electrochemical performance of Ni(OH)₂ is mainly determined by activation process. • A high-capacity Ni(OH)₂/Ni electrode was fabricated by combining GCD activation and wet treatment. -- Abstract: Nickel hydroxide (Ni(OH)2), as a representative of highly active materials, has been widely studied and applied in the field of energy storage. However, a typical electrochemical activation process is often required before its practical application. Thus, exploring this key activation process is of great significance for the construction of high-capacity Ni(OH)2 electrodes. In this work, we find that the activation of galvanostatic charge-discharge (GCD) is apparently different from that of cyclic voltammetry (CV). After activation, the composition of Ni(OH)2 deposited on the surface of Ni foam prepared by GCD and CV process is the same, but the morphology is obviously different. The layered porous network Ni(OH)2 nanostructures can be prepared by GCD process, while the spherical stacking nanostructures can be formed by CV process. By combining a wet process, two adhesive Ni(OH)2-coated Ni foam (Ni(OH)2/Ni) electrodes can be successfully fabricated. The results exhibit that the Ni(OH)2/Ni electrode obtained by the GCD process shows super energy storage capacity (2338.9 μA h cm-2 (3402 F g-1)) at a high loading mass of Ni(OH)2, which is almost 1.7 times higher than that of the CV-activated electrode (1380.6 μA h cm-2 (2008 F g-1)).