The passivity breakdown of zinc antimony alloy as an anode in the alkaline batteries
Abd El‐Rahman El‐Sayed, Hoda Abdel Shafy Shilkamy, Mahmoud Elrouby
Abstract
Zn is utilized as an anode in alkaline batteries because of its propensity to produce a passive colloidal layer on its surface. Then the surface should be reactivated in the passive region. Therefore, the passive state on the surface can be significantly hindered by utilizing a tiny percentage of Sb alloyed with Zn. Accordingly, the effect of minor Sb alloying with Zn on the performance of anodic dissolution and passivation in concentrated alkaline media (6 M KOH, which is used in the batteries) was studied using potentiodynamic and potentiostatic techniques. Besides, the passive layers formed at various anodic potentials were characterized utilizing scanning electron microscopy (SEM) and X-ray diffraction (XRD). The data of potentiodynamic measurements exhibited the active-passive transition curve of all studied specimens. All obtained results revealed that passivation is gradually hindered with increasing Sb content in the alloy, and less passivity was obtained at 1% Sb. Along this, a dramatic rise in current density at a particular positive potential (+ 2.0 V vs. SCE) to markedly higher values only of the electrodes containing Sb is observed.