Al含量对α-Ni(OH)_2结构及其电化学性能的影响

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

采用有机溶剂体系中的化学共沉淀法,制备了纳米尺度的、具有高电化学活性的Al取代α-Ni(OH)_2,并用XRD和FTIR光谱表征了它们的结构;通过考察样品在强碱性介质中的结构稳定性,探讨了Al含量对α-Ni(OH)_2结构及电化学性能的影响。结果表明:当Al含量为7.5％、13.2％和17.2％时,样品的晶粒度分别为5.4、6.9和11.0nm。Al含量为7.5％的样品为α-Ni(OH)_2和β-Ni(OH)_2的混合结构,而Al含量为13.2％和17.2％的样品则为纯α-Ni(OH)_2的单相结构。随着Al含量的增加,样品的结晶度增大,因而其稳定性增加,放电中点电位升高,电化学容量增大.

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.