Al-substituted α-nickel hydroxide prepared by homogeneous precipitation method with urea

Al-substituted alpha-nickel hydroxide was prepared by homogeneous precipitation from nickel nitrate solution in the presence of urea. The experimental results of XRD and FTIR show that the Ni(OH)(2) samples prepared by this method are typical a-phase. The 0% Al-containing alpha-Ni(OH)(2) is labile in alkaline media and easily converted to beta-Ni(OH)(2). The stability of the samples increases with increase in Al content. The SEM results show that the 0% Al-containing sample contain spherical particles with some degree of agglomeration, while the 16.8% Al-containing sample displays an irregular shape. The galvanostatic charge-discharge experiments show that the discharge potential of Al-substituted alpha-Ni(OH)(2) increases with increase in Al content. However, the maximum discharge capacities decrease slightly with increasing Al content at the 0.1 C rate. The Al-substituted alpha-Ni(OH)(2) samples have better activation performance than the 0% Al-containing sample at the 0.1 C rate. At the 1.0 C rate, the 19.5% Al-containing sample has the highest discharge capacity and relatively better cycle stability. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.