A Dual Organic Solvent Zn-Ion Electrolyte Enables Highly Stable Zn Metal Batteries

Aqueous zinc (Zn) batteries have been regarded as analternativeto lithium-ion batteries due to their high abundance, low cost, andhigher intrinsic safety. However, the low Zn plating/stripping reversibility,Zn dendrite growth, and continuous water consumption have hinderedthe practical application of aqueous Zn anodes. Herein, a hydrousorganic Zn-ion electrolyte based on a dual organic solvent, namelyhydrated Zn(BF4)(2) zinc salt dissolved in dimethylcarbonate (DMC) and vinyl carbonate (EC) solvents [denoted as Zn(BF4)(2)/DMC/EC], can address these problems, which notonly inhibits the side reactions but also promotes uniform Zn plating/strippingthrough the formation of a stable solid state interface layer andZn(2+)-EC/2DMC pairs. This electrolyte enables the Zn electrodeto stably undergo >700 cycles at a rate of 1 mA cm(-2) with a Coulombic efficiency of 99.71%. Moreover, the full cell pairedwith V2O5 also demonstrates excellent cyclingstability without capacity decay at 1 A g(-1) after1600 cycles.

Automated summary

A hydrous organic Zn-ion electrolyte based on a dual organic solvent has been developed to address the challenges of aqueous Zn anodes, such as low reversibility, dendrite growth, and water consumption. This electrolyte not only inhibits side reactions, but also promotes uniform Zn plating/stripping by forming a stable solid state interface layer and Zn(2+)-EC/2DMC pairs. The electrolyte enables the Zn electrode to undergo over 700 cycles with a high Coulombic efficiency, and the full cell paired with V2O5 exhibits excellent cycling stability.