A long term highly reversible zinc metal anode regulated by polar molecular interface adsorption

Abstract

Rechargeable aqueous zinc-ion batteries (AZIBs) are gaining recognition as a promising next-generation energy storage solution due to their intrinsic safety and low cost. Nevertheless, the advancement of AZIBs is greatly limited by the abnormal growth of zinc dendrites during cycling. Here, we propose an organic molecule, methyl acetate, as an additive containing polar functional groups that can promote the formation of a water-shielding electric double layer while disrupting the existing hydrogen bonding network. The preferential adsorption of methyl acetate on the Zn anode has been demonstrated, with a water-shielding layer being spontaneously formed to suppress competitive side reactions caused by active water and induce uniform deposition induced by Zn²⁺. At the same time, its polar functional group CO can also interact with Zn²⁺, replacing some of the water in solvation, promoting the solid electrolyte interface derived from anions, and achieving highly ordered deposition and stripping. Therefore, for Zn‖Zn electrolytes containing methyl acetate, a long cycle life of 4000 h can be achieved at 2 mA cm⁻² and 2 mA h cm⁻², and a highly reversible zinc plating/stripping battery in Zn‖Cu can achieve over 1000 cycles with a coulombic efficiency close to 100%. The full battery paired with a load of 12 mg cm⁻² KVO provides higher discharge specific capacity and cycling stability, with a capacity retention rate of 88.5% after 1000 stable cycles at 1 A g⁻¹.