Ternary eutectic electrolytes attune the electrode/electrolyte interphase layer toward long-life zinc ion batteries

Abstract

• The favorable solvent shell structure and low viscosity are crucial for life improvement. • The esterification reaction of urea and ethylene glycol enriches the composition of solid-electrolyte interface membranes. • Adsorption of urea on the surface of Zn can inhibit the growth of dendrites. Eutectic electrolytes show promise for zinc-ion batteries due to their cost-effectiveness and eco-friendliness. However, the design of eutectic electrolytes is challenging due to their high viscosity, low solute solubility, and interface compatibility issues. A novel ternary eutectic electrolyte composed of choline chloride, ethylene glycol, urea and ZnCl 2 is proposed in the study, and the complex interactions and compatibility between these components, and the interface growth principles were revealed systematically through experiments and theoretic simulations. Our research demonstrates the well-designed eutectic electrolyte can integrate optimific solvent-shell structure, favorable electrolyte interface as well as low viscosity perfectly, and can thus improve zinc plating kinetics and suppress dendrite growth, resulting in a durable, dendrite-free zinc electrode lasting over 3000 h. Moreover, Zn||CEU1Zn||PANI full cells also surprisingly achieved over 90 % retention rate after 8000 cycles at a relatively high current density of 2A·g −1 . This multi-component eutectic electrolyte presents a promising solution for long-lasting metal-ion battery electrolytes. The ternary eutectic electrolyte composed of choline chloride, ethylene glycol, urea, and zinc chloride has a favorable solvation structure and a complex and stable solid-electrolyte interphase film, achieving reversible zinc deposition/stripping.