Bio-inspired hydroxyl-rich electrolyte additive for highly reversible aqueous Zn-ion batteries with strong coordination chemistry†

A highly reversible Zn metal anode is the prerequisite for realizing the practical applications of aqueous Zn ion batteries (ZIBs), which are limited by severe zinc dendrites and corrosion. Herein, bio-inspired hydroxyl-rich l-ascorbic acid (vitamin C, l-Aa) was employed to regulate coordination chemistry via the strong interaction between –OH and H₂O with dual remodeling functions and further improve the reversibility of Zn anodes. Specifically, l-Aa not only reconstructs the Zn²⁺ solvation shell, thus reducing Zn²⁺ desolvation energy, but also forms a molecular adsorption interface via excellent zincophilicity to improve zinc redox kinetics and suppress Zn anode corrosion. Meanwhile, the molecular adsorption interface facilitates the homogenization of the interfacial electric field, thereby promoting the predominant deposition of Zn(002). Consequently, the Zn//Cu asymmetric cell presents a low overpotential for zinc nucleation and exceptional average coulombic efficiency (CE) of 99.6% over 1200 cycles at a high current density of 20 mA cm⁻². The Zn//Zn cell also delivers excellent cycling stability for over 1400 h at 5 mA cm⁻². In addition, the Zn//MnO₂ full cell exhibits a robust long-term cycling performance of 1000 cycles at 1 A g⁻¹. This strategy of simultaneously regulating coordination chemistry and further constructing molecular interfaces may boost the applications of highly reversible ZIBs.