Molecular key tuned steric-hindrance effect toward Zn (100) facet texture anode

Abstract

Electrolyte additive is one of the most effective strategies to optimize Zn anode in aqueous zinc ion batteries. Few reports are available on the influence of spatial-hindrance effect on Zn²⁺ deposition behavior. Herein, the environmentally safe aspartame and neotame are selected to finely tune the molecular structure, thereby affecting molecular adsorption behavior as well as Zn²⁺ diffusion and deposition behavior, and the molecular structure regulation strategy is proposed to achieve the optimization of Zn anode. According to theoretical calculations and experimental conclusions, aspartame, as the molecular robot, uniformly adsorbs on Zn anode surface via oxygen-containing functional groups, captures Zn²⁺ via −NH₂, homogenizes Zn²⁺ flux, and catalyzes Zn²⁺ desolvation, resulting in Zn²⁺ oriented deposition to form Zn (100) facet texture. Benefited from the molecular structure regulation strategy, Zn anode exhibits an ultra-long lifespan of more than 4600 h and an extremely high cumulative plated capacity of 11.7 Ah cm⁻². Furthermore, Zn anode operates stably for more than 270 h under 80 % depth of discharge and possesses a high coulombic efficiency of 99.8 % in Zn||Cu half cells. This strategy provides a new perspective on selecting additives.