Structural and spectroscopic properties of metal-urea complexes

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 ZnCl2 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.