Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, United States.
Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States.
J Am Chem Soc. 2020 Dec 23;142(51):21404-21409. doi: 10.1021/jacs.0c09794. Epub 2020 Dec 8.
Aqueous Zn batteries are promising energy storage devices for large-scale energy-storage due to low cost and high energy density. However, their lifespan is limited by the water decomposition and Zn dendrite growth. Here, we suppress water reduction and Zn dendrite growth in dilute aqueous electrolyte by adding dimethyl sulfoxide (DMSO) into ZnCl-HO, in which DMSO replaces the HO in Zn solvation sheath due to a higher Gutmann donor number (29.8) of DMSO than that (18) of HO. The preferential solvation of DMSO with Zn and strong HO-DMSO interaction inhibit the decomposition of solvated HO. In addition, the decomposition of solvated DMSO forms Zn(SO)Cl(OH)·5HO, ZnSO, and ZnS enriched-solid electrolyte interphase (SEI) preventing Zn dendrite and further suppressing water decomposition. The ZnCl-HO-DMSO electrolyte enables Zn anodes in Zn||Ti half-cell to achieve a high average Coulombic efficiency of 99.5% for 400 cycles (400 h), and the Zn||MnO full cell with a low capacity ratio of Zn:MnO at 2:1 to deliver a high energy density of 212 Wh/kg (based on both cathode and anode) and maitain 95.3% of the capacity over 500 cycles at 8 C.
水系锌电池由于成本低、能量密度高，是一种很有前途的大规模储能设备。然而，其使用寿命受到水分解和锌枝晶生长的限制。在这里，我们通过在 ZnCl-HO 中添加二甲基亚砜（DMSO）来抑制稀水电解质中的水还原和锌枝晶生长，由于 DMSO 的古特曼给体数（29.8）高于 HO 的古特曼给体数（18），因此 DMSO 取代了 Zn 溶剂化鞘中的 HO。DMSO 与 Zn 的优先溶剂化作用和强 HO-DMSO 相互作用抑制了溶剂化 HO 的分解。此外，溶剂化 DMSO 的分解形成 Zn(SO)Cl(OH)·5HO、ZnSO 和富含 ZnS 的固态电解质中间相（SEI），防止锌枝晶的形成并进一步抑制水的分解。ZnCl-HO-DMSO 电解液使 Zn||Ti 半电池中的 Zn 阳极能够在 400 个循环（400 小时）内实现高达 99.5%的平均库仑效率，而容量比为 Zn:MnO 的 2:1 的 Zn||MnO 全电池在 8 C 下能够提供 212 Wh/kg 的高能量密度（基于正极和负极），并在 500 个循环中保持 95.3%的容量。
