engleski

ELECTRODEPOSITION AND ELECTROCHEMICAL PROPRETIES OF NICKEL OXIDE ELECTRODES

Nickel oxide is commonly used in the form of nickel(III) oxyhydroxide, NiOOH, as active electrode material in secondary rechargeable batteries. Due to the fast charging/discharging reaction it is increasingly considered as a positive electrode in pseudo-supercapacitors. In this work nickel oxide electrodes of different thicknesses were electrochemically deposited and the mechanisms of electrochemical reactions were studied. The electrodes were prepared from NiSO4 solution onto Au substrate under catodic (galvanostatic) and anodic (potentiostatic) conditions. Electrochemical behaviour of nickel oxide electrodes was investigated in 0.1 M KOH solution by cyclic voltammetry, electrochemical quartz crystal microbalance, chronoamperometry and XPS measurement. The stability of prepared electrodes was investigated in 6M KOH solution. Results have been shown that depending on deposition method two structurally and electrochemically different forms of nickel oxide, α-Ni(OH)2 and β-Ni(OH)2, were obtained. Structural transformation of cathodic α-Ni(OH)2 into anodic β-Ni(OH)2 takes place by ageing of the cathodically prepared layer in 6M KOH solution as demonstrated by cyclic voltammetry, EQCM results, chronoamperometry and XPS spectra.

Nickel oxide electrodes; reaction mechanism; EQCM

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