Selective control of sharp-edge zinc electrodes with (002) plane for high-performance aqueous zinc-ion batteries

Abstract

The surface properties and stability of the Zn anode are crucial for achieving high-performance aqueous zinc-ion batteries. Here, we applied etching to the Zn metal anode using the highly active H₂SO₅ etching solution to control the exposure level of the Zn (002) crystal plane. Etching for 2 min afforded Zn sharp-edge (ZnSE) structures with the predominant Zn (002) crystal plane on the Zn surface. The Zn (002) crystal plane hindered the growth of protruding Zn dendrites, minimized hydrogen generation, and enabled a high resistance against Zn metal corrosion and the various side reactions with the aqueous electrolyte ions. Consequently, the Zn anode symmetry cells exhibited excellent cyclability (>200 h) at current densities of 3 and 6 mA cm⁻². Furthermore, with the cell configuration of ZnSE‖α-MnO₂, the full cells exhibited a high capacitance of 306 mA h g⁻¹ at a current density of 0.2 A g⁻¹, with a good cycle retention of 94% for up to 300 cycles at 0.5 A g⁻¹. Our results will help resolve the surface and stability problems afflicting the Zn metal electrode, helping us achieve high-performance AZIBs. Furthermore, 3D phase-field simulations demonstrate the important role of (002) crystal plane orientation during Zn deposition. Specifically, a dendritic protrusion is formed in the film when the (002) plane orientation is normal, whereas a uniform deposition is observed when the (002) plane is parallel to the Zn film.