Hence, in order to avoid the limited O2 availability at the cathode and study the role of O2 at the anodic process, the further charge-discharge and full discharge studies are conducted in a customized decoupled split cell where anodic and cathodic sides are separated using an anion (hydroxide) exchange membrane (FAS-50), Fig. (inset shows blockage of oxygen transfer from cathode to anode only permeating OH -ion). Separate gas inlet and outlet are made for both the cathodic and anodic sides. The decoupled split cell locks the supplied gas environment on each side without affecting the other. Hence, the further experiments are performed by varying the anodic environment (O2 and N2) while keeping a constant O2 supply at the cathode. The galvanostatic charge-discharge cyclability at a current density of 5 mA/cm², is shown in Fig. Furthermore, the effect of O2 in early passivation of the Zn (Fig. ) is also reflected by fulldischarge study of the cell. The cells are completely discharged at a current density of 5 mA/cm 2 by varying anodic environment as N2 and O2, keeping the cathodic feed same as O2. The first discharge plot, Fig. , indicates an approximately sevenfold increase in the discharge time with anodic N2 in comparison to that of O2. This indicates an extended time taken for Zn passivation in presence of N2, whereas a complete passivation of Zn surface (with ZnO) in O2 leading to the early cell failure. Moreover, to test the negative influence of O2 in the discharge capacity retention of the cell, firstly, the cells are fully discharged in different gaseous environment [N2 (Fig. ), O2 (Fig. )] followed by the charging for the same time period and repeated for several cycles until the anode is completely passivated and failed. From the data (Fig. , Fig. ), it is inferred that the discharge capacity is retained by nearly 40 % for the second cycle in the N2 environment in comparison to mere 8 % in the O2 environment. The trend remains the same with a 22 %, 5 %, and 3 % capacity retention in the consecutive cycles for the N2 environment compared to the negligible retention of 1 %, 0.3 %, and 0.1 % respectively, in the O2 environment. This shows the nature of the ZnO formed is more passivating in the O2 environment than in the N2 that results in almost 5 times low discharge capacity even in the second discharge. The discharge capacity of the cell having N2 supply is found to be higher than that of the O2 indicating the significant reversibility of the reaction (Zn + 4 OH -→ [Zn(OH)4] 2-+2 e -) in the former.