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

He, Ruiqi; Yu, Fangfang; Wu, Kuan; Liu, Hao-Xuan; Li, Zhen; Liu, Hua Kun; Dou, Shi-Xue; Wu, Chao · Nano Lett · 2023

basic_science · Level V

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Abstract

Aqueous zinc (Zn) batteries have been regarded as an alternative to lithium-ion batteries due to their high abundance, low cost, and higher intrinsic safety. However, the low Zn plating/stripping reversibility, Zn dendrite growth, and continuous water consumption have hindered the practical application of aqueous Zn anodes. Herein, a hydrous organic Zn-ion electrolyte based on a dual organic solvent, namely hydrated Zn(BF<sub>4</sub>)<sub>2</sub> zinc salt dissolved in dimethyl carbonate (DMC) and vinyl carbonate (EC) solvents [denoted as Zn(BF<sub>4</sub>)<sub>2</sub>/DMC/EC], can address these problems, which not only inhibits the side reactions but also promotes uniform Zn plating/stripping through the formation of a stable solid state interface layer and Zn<sup>2+</sup>-EC/2DMC pairs. This electrolyte enables the Zn electrode to stably undergo >700 cycles at a rate of 1 mA cm<sup>-2</sup> with a Coulombic efficiency of 99.71%. Moreover, the full cell paired with V<sub>2</sub>O<sub>5</sub> also demonstrates excellent cycling stability without capacity decay at 1 A g<sup>-1</sup> after 1600 cycles.