Preparation and Electrochemical Capacitance of α-Ni(OH)2 Synthesized by Microwave-assisted Hydrothermal Method

Ni(OH)2 particles were successfully prepared with Ni(NO3)2·6H2O as the raw material and CO(NH2)2 as the precipitation agent by microwave-assisted hydrothermal method. The obtained Ni(OH)2 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical measurements. XRD results showed that the as-prepared Ni(OH)2 particles had the typical α-phase. The SEM images revealed that the synthesized α-Ni(OH)2 particles were well dispersed and ball-flower like with diameters of 0.5-3 μm which consisted of the aggregated flakes. Electrochemical properties were studied by cyclic voltammograms (CV) and galvanostatic charge-discharge tests in 6 mol/L KOH electrolyte. All the tests showed that the reactants ratio affected the morphologies and the electrochemical capacitance of the materials. When the molar ratio of the CO(NH2)2 to Ni(NO3)2·6H2O was 3:1, the obtained α-Ni(OH)2 had the maximal initial special capacity; when the molar ratio was 2:1, the α-Ni(OH)2 had the best cycle storage performance.