Preparation, structure and electrochemical performances of nanosized cathode active material Ni(OH)2

Nanosized cathode material Ni(OH)(2) was prepared by aqueous solution precipitation reaction under ultrasonic dispersing condition. The Ni(OH)(2) products were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM). The electrochemical performances of the Ni(OH)(2) samples were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscope (EIS). The charge-discharge tests were conducted on the batteries with the sample as the positive electrode active material. The XRD and SEM results shows that nano-sized Ni(OH)(2) prepared in this study is beta-type crystal with the particle size range from 10-40nm with regular spherical shapes. The results from CV and EIS measurement indicate that the nano-sized Ni(OH)(2) exhibits excellent electrochemical performance, e.g., batter electrochemical reversibility and higher proton diffusion rate, smaller polarization and better discharge property than that of usual spherical Ni(OH)(2); and the measured apparent diffusion coefficiency of proton is 1.8 x 10(-12) cm(2) s(-1); and the specific discharge capacity of the nano-sized Ni(OH)(2) electrode is 381 mAh/g. (c) 2005 Elsevier B.V. All rights reserved.