Influence of MgO on the Electrochemical Performance of Nickel Electrode in Alkaline Aqueous Electrolyte

Abstract

β-nickel hydroxide (β-Ni(OH)2) was prepared using precipitation method. Magnesium oxide (MgO) was synthesized by solu-tion combustion method using magnesium nitrate as oxidizer and urea as a fuel. The effects of MgO additive on the structure and electro-chemical performance of β-Ni(OH)2 electrode are examined. The structure and property of the MgO added β-Ni(OH)2 were characterized by X-ray diffraction (XRD), thermal gravimetric-differential thermal analysis (TG-DTA), Scanning electron microscopy (SEM), and Energy Dispersive X-ray (EDX) analysis. The results of the TG-DTA studies indicate that the MgO added β-Ni(OH)2 contains adsorbed water mol-ecules and anions. Partial substitution of MgO for graphite to β-nickel hydroxide is found to exhibit improvement in the electrochemical activity. Anodic peak potential (Epa) and cathodic peak potential (Epc) values are found to decrease remarkably after the incorporation of MgO into the β-Ni(OH)2 electrode. Further, addition of MgO is found to enhance the reversibility of the electrode reaction. Compared with β-Ni(OH)2 electrode, MgO substituted β-Ni(OH)2 electrode is found to exhibit higher proton diffusion coefficient. These findings suggest that the MgO substituted β-Ni(OH)2 electrode possess improved electrochemical properties such as enhanced reversibility of electrode reaction and higher proton diffusion coefficient and thus can be recognized as a promising candidate for the battery electrode applications.