Fig. 5. Crystallographic characteristics of zinc.

(A) Crystal model of HCP Zn metal. The red lattice denotes the primitive unit cells. The front, light blue layer and the back, dark blue layer are two close-packed layers that stack periodically (…ABABAB…) along the [002] direction (also called the c axis). (B) Weighted surface energy $\overline{\mathrm{\gamma }}$ and surface energy anisotropy α_γ of representative anode metals.$\overline{\mathrm{\gamma }}={\mathrm{\Sigma }}_{(\mathrm{hkl})}{\mathrm{\gamma }}_{\mathrm{hkl}}{f}_{\mathrm{hkl}}^{\mathrm{A}}$, where γ_hkl is the surface energy of (hkl), and $f_{\mathrm{hkl}}^{\mathrm{A}}$ is the area fraction of the (hkl) family in the Wulff shape. ${\mathrm{\alpha }}_{\mathrm{\gamma }}=\frac{\sqrt{{\Sigma }_{(\mathrm{hkl})}{({\mathrm{\gamma }}_{\mathrm{hkl}}-\overline{\mathrm{\gamma }})}^2{f}_{\mathrm{hkl}}^{\mathrm{A}}}}{\overline{\mathrm{\gamma }}}$. α_γ can be viewed as a normalized coefficient of variation of surface energy. A greater α_γ value implies a larger anisotropy in the surface energies of the crystal facets exposed in its Wulff shape. In an extreme case of a perfectly isotropic crystal, α_γ = 0. Plotted according to data reported in (125). (C) Wulff shapes for metals of contemporary interest as battery anode materials. They depict the shape of the crystals at thermodynamic equilibrium. Adapted with permission using the database reported in (125). (D) XRD analysis of the crystallographic texturing of Zn metal electrodeposits. (D-1) θ−2θ XRD line scans of Zn electrodeposits. (D-2) Peak intensity ratio I₀₀₂:I₁₀₁ of the scans shown in Fig. 5D-1. (D-3) 2D XRD of samples #3 and #4 shown in Fig. 5D-1. Adapted with permission from (28). A.U., arbitrary units.