Self-assembled nickel hydroxide three-dimensional nanostructures: A nanomaterial for alkaline rechargeable batteries

alpha- and beta-Ni(OH)(2) with three-dimensional (3D) nanostructures were synthesized in a water-in-oil reverse micelle/microemulsion system. The form and shape of Ni(OH)(2) can be readily tuned by adjusting experimental parameters of the reverse micelle/microemulsion system. alpha-Ni(OH)(2) with dandelion-like nanostructures was obtained in the reverse microemulsion of cetyltrimethylammonium bromide (CTAB)/water/cyclohexane/n-pentanol with a molar ratio of H2O to surfactant of 40; beta-Ni(OH)(2) phase with flower-like nanostructures was formed in the reverse micelles of the same composition with a molar ratio of H2O to surfactant of 10. Electrochemical measurements of the as-synthesized alpha-Ni(OH)(2) phase showed that the 3D alpha-Ni(OH)(2) nanostructures exhibited superior cycling reversibility and improved capacity compared with commercial Ni(OH)(2).