Ni(OH)2 particles synthesized by high energy ball milling

High energy ball milling(HEBM) method was applied to synthesize nickel hydroxide with and without partial substitution for Ni2+ sites by such metallic ions as Al3+, Al3+Zn2+ and Al3+Zn2+Co2+. The morphologies, structures, composition and thermal stability of the prepared powders were studied by SEM, XRD, FTIR and TG. The results reveal that all the synthesized Ni(OH)2 particles agglomerate in sub-micron sizes and the non-substituted Ni(OH)2 is composed of beta phase with a crystal interlayer distance of 4.64 Å, while the Al3+, Al3+Zn2+, Al3+Zn2+Co2+ substituted products are composed of alpha phase with 8.03 Å crystal interlayer space. Absorbed water molecule is found in all the synthesized Ni(OH)2 and the non-substituted particles are more thermally stable than substituted α-Ni(OH)2. The absorption peaks of inserted crystal anions of CO32− and SO42− are detected for metallic ion substituted α-Ni(OH)2. The specific capacity of Al3+ substituted Ni(OH)2 is 325 mA·h/g, 5 mA·h/g higher than Al3+Zn2+ substituted and non-substituted Ni(OH)2, but 25 mA·h/g greater than Al3+Zn2+Co2+ substituted Ni(OH)2. The electrochemical mechanism of synthesized Ni(OH)2 electrodes is discussed by EIS spectrum and Al3+ substituted Ni(OH)2 electrode shows a high electrochemical cyclic stability.