Electrodeposition of Cobalt in an Ionic Liquid Electrolyte at Ambient Temperature

Abstract

AbstractThe codeposition behavior of Co and Zn in an ionic liquid was investigated. In the cyclic voltammogram of a ZnCl2‐EMIC‐CoCl2 ionic liquid, three reduction peaks appeared at 250 mV (peak c1), 50 mV (peak c2) and −200 mV (peak c3) (vs. Zn2+/Zn). According to the component analysis by means of EDS (energy disperse spectroscopy), peaks c1, c2 and c3 correspond to the electrodeposition of Co, the underpotential deposition of Zn on the electrodeposited Co coating and the codeposition of Co‐Zn alloy, respectively. The potentiostatic deposition showed that the electrodeposited coating of high‐pure Co was obtained when the cathodic potential was controlled at 100 mV (vs. Zn/Zn2+). The electrodeposition was carried out at a galvanostatic mode, and when the current density was controlled at about 85 µA/cm2, the electrodeposited coating of high‐pure Co was also obtained. Studies on the mechanism of codeposition of Co and Zn showed that the electrodeposition process of Co and the underpotential deposition process of Zn on the electrodeposited Co coating were all diffusion controlled.