丙二醇电解液键结构调控及其水系锌离子电池稳定性研究

Modulated bonding interaction in propanediol electrolytes toward stable aqueous zinc-ion batteries

水系锌基电池具有低成本和高安全性的优点,是很有潜力的储能技术.然而,枝晶、副反应和较差的低温性能限制了其实际应用,这与电解液的溶液组成密切相关.在本工作中,我们通过调控丙二醇电解液的溶剂结构及键相互作用,有效抑制了锌枝晶和副反应.丙二醇具有较高的电子云密度和DN(Donor number)值,可以破坏水分子间和水分子与Zn^(2+)间的相互作用,从而提高H–O共价键的强度,降低水活性和冰点,改变Zn^(2+)的溶剂化结构.制备的电池器件表现出高的循环稳定性(Zn//Zn电池循环超过1000 h),高可逆性(库伦效率达到98.9%),高储锌性能(在5 Ag^(-1)下比容量为225 mA h g^(-1),循环5000圈容量保持率为92.6%)和优异的防冻性能(在-20℃下循环500圈比容量为190 mA h g^(-1)).本工作为高性能水系锌离子电池的发展提供了一种有前景的策略.

Aqueous Zn-based batteries are promising energy storage technology due to their low cost and high safety.However, the solvation structure of electrolyte leads to dendrite growth, parasitic reactions, and poor low-temperature properties, limiting their practical application. Here, we report 1,2-propanediol(PG) electrolyte with a modulated solvation structure, which can suppress Zn dendrite growth and parasitic reactions. PG can break the interaction between H_(2)O molecules and the interaction between H_(2)O and Zn^(2+) due to the higher electron density of O and higher Gutmann donor number of PG than those of H_(2)O, which increase the H–O covalent bond strength, decrease the water activity and freezing point, and change the solvation structure of Zn^(2+). As a result, the battery exhibits high cycling stability(Zn//Zn battery cycle over 1000 h), high reversibility(Coulombic efficiency of 98.9%), high capacity properties(specific capacity of225 m A h g^(-1)at 5 A g^(-1), and capacity retention of 92.6% for5000 cycles), and excellent anti-freezing properties(specific capacity of 190 m A h g^(-1) at-20℃ over 500 cycles). This work provides a promising strategy for the development of highperformance aqueous zinc-ion batteries.