The passivation of pure zinc surface can be considered a problem of Zn utilization as an anode in alkaline batteries due to its small capacity. Therefore, to improve the discharge capacity of the Zn anode, minor Sb alloying with Zn was investigated. The impact of trace Sb alloyed with Zn on the passivity and the breakdown of the colloidal passive film on the surface was studied in concentrated KOH solution utilizing galvanostatic, electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge measurements at the passivated area. The galvanostatic data show that the required time of passivation (tpass.) is greater with increasing small Sb content in the alloy. The obtained results from electrochemical impedance spectroscopy (EIS) reveal that magnitudes of both resistivities of charge transfer (Rct.) and the impedance of Warburg (Zw) decrease, while the magnitude of capacitance of double layer (Cdl.) increases gradually with the increase in addition of small Sb to zinc metal. The evaluated data from the charging-discharging process show that the greatest value of potential height (ΔV) is for Zn-0.5%Sb alloy. Therefore, 0.5%Sb alloying with Zn can increase energy efficiency to a large extent than Zn and alloy II.