Influence of Al Content on the Structure and Electrochemical Performance of Al-substituted α-Ni(OH)_2

Nano-sized Al-substituted α-Ni(OH)_2 with high electrochemical performance was syn- thesized through a chemical co-precipitation method in organic solvent and characterized by means of X-ray diffraction and infrared spectroscopy. Sample's structure stability in concentrated alkaline solution was investigated and the relationship between structure and electrochemical performance was studied. The experimental results show that the mean crystal sizes of samples containing 7.5%,13.2%and 17.2%(molar ratio)Al are 5.4, 6.9 and 11.0 nm respectively. The structure of the sample with 7.5% Al is of the mixture of α-Ni(OH)_2 and β-Ni(OH)_2, whereas the structurers of the samples respectively with 13.2% and 17.2% Al are of pure α-Ni(OH)_2. Structure stability increases with Al content increasing due to gradually increased crystallinity and so do its discharge mediate potential and specific electrochemical capacity.