Influence of TiO2 on the electrochemical performance of pasted type β-nickel hydroxide electrode in alkaline electrolyte

Abstract

Nickel hydroxide was used as the positive electrode material in rechargeable alkaline batteries, which plays a significant role in the field of electric energy storage devices. β-nickel hydroxide (β-Ni(OH)2) was prepared from nickel sulphate solution using potassium hydroxide as a precipitating agent. Pure β-phase of nickel hydroxide was confirmed from XRD and FT-IR studies. The effects of TiO2 additive on the β-Ni(OH)2 electrode performance are examined. The structure and property of the TiO2 added β-Ni(OH)2 were characterized by XRD, TG-DTA and SEM analysis. A pasted–type electrode is prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry and electrochemical impedance spectroscopy studies were performed to evaluate the electrochemical performance of the β-Ni(OH)2 and TiO2 added β-Ni(OH)2 electrodes in 6 M KOH electrolyte. Anodic (Epa) and cathodic (Epc) peak potentials are found to decrease after the addition of TiO2 into β-Ni(OH)2 electrode material. Further, addition of TiO2 is found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. Compared with pure β-Ni(OH)2 electrode, TiO2 added β-Ni(OH)2 electrode is found to exhibit higher proton diffusion coefficient (D) and lower charge transfer resistance. These findings suggest that the TiO2 added β-Ni(OH)2 electrode possess improved electrochemical properties and thus can be recognized as a promising candidate for the battery electrode applications.