Selectively etching-off the highly reactive (002) Zn facet enables highly efficient aqueous zinc-metal batteries

Abstract

Due to their high safety, considerable capacity, environmental friendliness and low price, aqueous zinc metal batteries (AZMBs) show promising prospects in promoting future global electrification. However, the high reactivity of zinc (Zn) in aqueous electrolytes leads to dendrite growth and water-induced side reactions, which in turn lead to poor stability and low reversibility of Zn, greatly limiting the practical application of AZMBs. In this work, we originally found that selectively etching-off the reactive (002) Zn facet within common Zn foil would effectively passivate zinc-metal, consequently suppress the formation of dendritic Zn and water-induced byproducts, and finally remarkably enhance Zn-metal's stability and reversibility. As a result, the average coulombic efficiency (CE) of the etched Zn during ultra-long cycling (4500 cycles) is improved to a high level of 99.94% even under an aggressive condition of 10 mA cm⁻². The NH₄V₄O₁₀//Zn pouch-cell based on etched Zn delivers a high specific capacity of 317.3 mA h g⁻¹ and preserves 85.2% of its capacity even after 350 cycles. A more practical 0.124 A h NH₄V₄O₁₀//Zn pouch-cell with a high capacity retention of 91.23% after 80 cycles is also achieved. We believe that the method reported in this work will bring new insight into enhancing Zn-metal's stability and reversibility, and accelerate the commercialization of AZMBs.