Effect of ultrasonic on structure and electrochemical performance of α-Ni(OH)2 electrodes

Al/Co co-doped α-Ni(OH)2 samples were prepared by either ultrasonic co-precipitation method (Sample B) or co-precipitation method (Sample A). The crystal structure and particle size distribution of the prepared samples were examined by X-ray diffraction (XRD) and laser particle size analyzer, respectively. The results show that Sample B has more crystalline defects and smaller average diameter than Sample A. The cyclic voltammetry and electrochemical impedance spectroscopy measurements indicate that Sample B has better electrochemical performance than Sample A, such as better reaction reversibility, lower charge-transfer resistance and better cyclic stability. Proton diffusion coefficient of Sample B is 1.96×10−10cm2/s, which is two times as large as that (9.78×10−11cm2/s) of Sample A. The charge-discharge tests show that the discharge capacity (308 mA·h/g) of Sample B is 25 mA·h/g higher than that of Sample A (283 mA·h/g).