Spherical clusters of β-Ni(OH)2 nanosheets supported on nickel foam for nickel metal hydride battery

Spherical clusters of Ni(OH)2 nanosheets are directly grown on skeletons of nickel foam via a facile template-free spontaneous growth method. The obtained electrode (β-Ni(OH)2/Ni-foam) is characterized by X-ray diffractometry, scanning and transmission electron microscopy and thermal analysis. Results show that Ni(OH)2 has a β-phase structure and presents on the nickel foam skeleton mostly as spherical clusters with a diameter of ∼10 μm. The spheres are composed of nanosheets with thickness of ∼60 nm, width of ∼230 nm and length up to ∼2 μm, and the nanosheets are assembled by nanoparticles with diameter of ∼20 nm. The electrochemical performance of the β-Ni(OH)2/Ni-foam electrode is evaluated by cyclic voltammetry and galvanostatic charge–discharge tests. The difference between the oxygen evolution reaction onset potential and the anodic peak potential for this electrode (∼100 mV) is larger than that for β-Ni(OH)2 nanosheets and nanotubes powder electrode (∼65–77 mV) and much larger than that for commercial spherical β-Ni(OH)2 powder electrode (∼25–47 mV), indicating that the β-Ni(OH)2/Ni-foam electrode can be fully charged. The specific discharge capacity of β-Ni(OH)2 in the β-Ni(OH)2/Ni-foam electrode reaches 275 mAh g−1, which is close to the theoretical value, lower than that of β-Ni(OH)2 nanotubes (315 mAh g−1), but higher than that of nanosheets (219.5 mAh g−1), commercial micrometer grade spherical powders (265 mAh g−1) and microtubes (232.4 mAh g−1).

• Facile one-step preparation of Ni foam supported β-Ni(OH)2 nanosheets.
• Nanosheets have porous structure and large electrochemical active surface area.
• Nanosheets have large high rate discharge capacity and superior cycling stability.