A high donor co-solvent for dendrite-free and long-cycling zinc ion batteries

Zinc ion batteries are considered one of the most promising next-generation energy storage systems due to their high energy density, excellent safety and low cost. However, dendrite growth and side reactions, including passivation and the hydrogen evolution reaction, significantly reduce cycle life and hinder practical application. In this study, a high donor co-solvent of 1,3-dimethyl-2-imidazolidinone (DMI) is applied in an aqueous electrolyte to enhance the performance of the Zn anode. The DMI co-solvent effectively regulates hydrogen bonds in the aqueous electrolyte, modifies the solvation structure of Zn 2+ , and promotes uniform zinc deposition. As a result, the Zn‖Zn symmetrical cells demonstrate a long cycle life, and the Zn‖Cu cell exhibits a high Coulombic efficiency of 99.3%. Additionally, the full battery with V 2 O 5 · x H 2 O as cathode delivers a high capacity of 170 mAh g -1 and a capacity retention of 73% after 2500 cycles at a current density of 5 A g -1 .