Ionic liquid-integrated aqueous electrolyte regulation on solvation chemistry and electrode interface for reversible dendrite-free zinc anodes

Abstract

Zn anodes suffer from poor reversibility and stability owing to nonuniform dendrite growth and self-corrosion. Here, 1-ethyl-3-methylimidazolium acetate (EMImAc) is introduced to reconstruct interfacial electrical double layer with simultaneously manipulating the solvation environment and the adsorption situation on Zn anode. The acetate anions with high nucleophilicity can effectively alter the solvation shell around Zn2+ ions and immobilize the H2O molecules, thus weakening water activity and alleviating water-related parasitic reactions. Concomitantly, both the imidazolium cation and acetate anion are inclined to gather on Zn anode surface for constructing an electrostatic shielding layer, and meanwhile the chemisorbed acetate anions also contribute to accelerate the Zn(H2O)62+ desolvation process. Such a synergistic effect enables uniform electric field distribution and facilitates Zn ion flux, which mitigates the random diffusion of Zn2+ and finally promotes the dendrite-free deposition. As a result, the Zn/Zn symmetric cells with EMImAc-integrated aqueous electrolyte realize an excellent cycling lifespan of 7000 h (0.5 mA cm−2/0.25 mAh cm−2) and high Zn utilization of 61.3 % (15 mA cm−2/20 mAh cm−2). Furthermore, the effective of EMImAc additive is demonstrated in Zn/V2O5 cells. This work offers insights into the ionic liquid-integrated aqueous electrolytes to enhance the interface stability of Zn anode for rechargeable zinc batteries.