Highly Reversible Zn Metal Anode with V-Shaped Valley-Like Nanoarray Structure for Rechargeable Zn-Ion Aqueous Batteries

Zn metal is one of the highest capacity anodes for aqueous rechargeable batteries. However, the serious issue of dendrite growth during Zn plating/stripping must be addressed on Zn metal electrode. Sculpting three-dimensional nanostructure patterns on the Zn anode surface is a method to achieve high stability and reversibility. We demonstrate the surface modification of Zn metal foil into a well-arranged V-shaped valley-like Zn nanoarray surface using the laminar flow of an etchant solution, based on a mechanism that mimics the formation of valleys in nature. The improved accessible surface area reduces the local current density, resulting in uniform Zn nucleation, thereby inhibiting dendrite growth. The surface alternation was also found to unveil crystallographic orientations that promote planar growth, further limiting dendrite growth. Such surface-modified Zn anodes demonstrate excellent reversibility, with a 4-fold increase in cycle-life compared to bare Zn. A full cell with a V2O5 cathode and a surface-modified Zn anode delivered a capacity of 175 mAh g–1 and retained 80 percent of its capacity after >500 cycles, compared to only 30% with an unmodified Zn anode. Overall, this work highlights a method to improve the reversibility of ZIBs through surface modification of the Zn anode.