Step-Edge Guided Homoepitaxy Enables Highly Reversible Zn Plating/Stripping

Metal anodes are of profound impact towards the realization of energy-dense rechargeable batteries. However, the "hostless" metal redox always presents the disordered plating/stripping, aggravated by the side reactions and local anisotropy that cause the formation of excessive dendrites/voids and quickly lead to battery failure. Here we report step-edge guided homoepitaxy enabling ordered layer-by-layer Zn plating/stripping regardless of the (dis)charging conditions. Through engineering the atomic terrace height on the mono-oriented Zn(0002) foil anodes, both in-plane and out-of-plane epitaxy aligned to the underlying Zn lattice are demonstrated via the favored edge nucleation and strong interfacial interaction driven by the surface/interface energy minimization, achieving the electrochemical homoepitaxy of continuous, submillimeter-scale Zn(0002) crystal with nearly 100 % theoretical density. Accordingly, we achieve a high Coulombic efficiency of 99.8 %, high depths of discharge exceeding 51 % and 82 % along with record-high lifetimes of over a thousand and hundreds of hours, respectively, in zinc metal batteries. The breakthrough results provide new insights on the intrinsic metal plating/stripping from the view of reversible homoepitaxy for rechargeable energy-dense metal batteries.