An improvement on redox reversibility of cobalt oxyhydroxide in nickel hydroxide electrodes

In this paper, two kinds of cobalt oxyhydroxide conductive networks were introduced into nickel hydroxide electrodes by different methods—electrochemically-oxidized (EO) or chemically oxidized (CO) CoOOH on the surface of nickel hydroxide particles. The redox behaviors of them were studied by using cyclic voltammetry (CV) and X-ray diffraction (XRD) measurements. It shows that because CoOOH(CO) has better redox reversibility than CoOOH(EO), the structure of the former can be kept when nickel hydroxide electrodes are subjected to a negative potential. Thus, 98.5% capacity retention is demonstrated on nickel/metal-hydride (Ni–MH) batteries with CoOOH(CO) after being imposed over-discharge state storage; on the contrary, only 81.4% capacity retention is found on the batteries with CoOOH(EO).