A Stable Solid-Electrolyte Interphase Constructed by a Nucleophilic Molecule Additive for the Zn Anode with High Utilization and Efficiency

Abstract

The solid-electrolyte interphase (SEI) strongly determines the stability and reversibility of aqueous Zn-ion batteries (AZIBs). In traditional electrolytes, the nonuniform SEI layer induced by severe parasitic reactions, such as the hydrogen evolution reaction (HER), will exacerbate the side reactions on Zn anodes, thus leading to low zinc utilization ratios (ZURs). Herein, we propose to use methoxy ethylamine (MOEA) as a nucleophilic additive, which has a stronger nucleophilic characteristic than water, with the advantage of an abundance of nucleophilic atoms. The Helmholtz plane (HP) on the Zn anode can be manipulated via the adsorption of MOEA, which excludes free water from the HP due to its strong affinity with metallic Zn. Benefiting from the optimization of the HP, side reactions are greatly suppressed, and a smooth SEI layer can be constructed, enabling the Zn anode to work at high ZURs and high areal capacities. Consequently, the Zn||Cu asymmetric cell exhibits an extremely high cumulative plating capacity of 4 Ah cm^–2 at 10 mA cm^–2 with an average Coulombic efficiency (CE) of 99.8%. The Zn||Zn symmetric cell achieves a maximum ZUR of 80% at an areal capacity of 20 mAh cm^–2 for 130 h, accounting for the boosted reversibility of Zn||V₂O₅ and Zn||AC full cells under low N/P ratios. Our strategy with nucleophilic electrolyte additives opens a path for developing durable aqueous Zn batteries with high ZURs.