Structure and electrochemical properties of nickel hydroxide electrodes with cobalt additives

摘要

In this article,cobalt additives are introduced into nickel hydroxide electrodes by two incorporation methods__co-precipitated cobalt hydroxide during the nickel hydroxide synthesis or post-added CoO with nickel hydroxide. The results of X-ray diffraction, cyclic vol_tammetry, electrochemical impedance spectroscopy, and charge-discharge tests indicate that (i) the diffraction peaks show a decrease in intensity and increase in the half peak breadths for Ni(OH)_2 with co-precipitated cobalt hydrox_ide; (ii) the electrochemical activity of nickel hydroxide can be improved by both incorporated cobalt and the effects of post-added CoO are more notable; (iii) CoOOH derived from post-added CoO is not stable in the KOH electrolyte when the potential of the Ni(OH)_2 electrode is lowered and its reduction product may be inactive, thus results in an irreversible capacity loss of nickel-metal_hydride battery after over-discharge-state storage.