To probe further into the early passivation of zinc, X-ray diffraction (XRD) studies are conducted with Zn electrodes discharged for the same capacity (2.5 mAh/cm 2 ) i.e. 30 minutes at a current density of 5 mA/cm 2 , in the anodic O2 and N2 environments. As shown in Fig. (110) planes, respectively, of hexagonal close packing structure in both the electrodes. Along with that, the diffraction peaks at 31.8, 34.5, 36.3, 45.9, 47.6, 56.7, 62.9 ⁰ corresponding to (100), (002), ( ), ( ), ( ), (103), and (112) planes, respectively, of wurtzite ZnO (ICDD file number 36-1451) are also present in both the samples indicating a similar phase of ZnO formed in both the environments. However, it is observed that the ratio of the highest intensity peak of ZnO (002) to the metallic Zn (101) is higher (~0.24) in O2 supplied Zn electrodes than that in the N2 influenced one (~0.06). This indicates that the increased oxygen pressure enhances the stoichiometry of ZnO by promoting growth along the c-axis. The decrease in full width and half maximum (FWHM) or the sharpening of the (002) peak suggest that the O2 rich environment leads to the formation of more crystalline ZnO, contributing to the development of a passivating layer. The XRD studies are also conducted for Zn electrodes discharged at different time intervals of N2 and O2 environments, SI Appendix, Fig. and.