Synergetic modulation on ionic association and solvation structure by electron-withdrawing effect for aqueous zinc-ion batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 37023128.
- Also identified by DOI 10.1073/pnas.2221980120 and PMC identifier 10104530.
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Abstract
Aqueous zinc-ion batteries are emerging as one of the most promising large-scale energy storage systems due to their low cost and high safety. However, Zn anodes often encounter the problems of Zn dendrite growth, hydrogen evolution reaction, and formation of by-products. Herein, we developed the low ionic association electrolytes (LIAEs) by introducing 2, 2, 2-trifluoroethanol (TFE) into 30 m ZnCl<sub>2</sub> electrolyte. Owing to the electron-withdrawing effect of -CF<sub>3</sub> groups in TFE molecules, in LIAEs, the Zn<sup>2+</sup> solvation structures convert from larger aggregate clusters into smaller parts and TFE will construct H-bonds with H<sub>2</sub>O in Zn<sup>2+</sup> solvation structure simultaneously. Consequently, ionic migration kinetics are significantly enhanced and the ionization of solvated H<sub>2</sub>O is effectively suppressed in LIAEs. As a result, Zn anodes in LIAE display a fast plating/stripping kinetics and high Coulombic efficiency of 99.74%. The corresponding full batteries exhibit an improved comprehensive performance such as high-rate capability and long cycling life.