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Solvation-protection-enabled high-voltage electrolyte for lithium metal batteries
Nano Energy ( IF 16.8 ) Pub Date : 2021-11-12 , DOI: 10.1016/j.nanoen.2021.106720
Chi-Cheung Su 1 , Meinan He 2 , Mei Cai 2 , Jiayan Shi 1, 3 , Rachid Amine 4 , Nancy Dietz Rago 1 , Juchen Guo 3 , Tomas Rojas 4, 5 , Anh T. Ngo 4, 5 , Khalil Amine 1, 6, 7
Affiliation  

To facilitate the practical application of lithium metal batteries (LMBs), stable interfaces between the electrolyte and the lithium metal must be achieved. Herein, we introduce a solvation protection strategy for designing a functional electrolyte for high-voltage LMBs. Fluoroethylene carbonate (FEC) was introduced as a solvation protection solvent for the difluoroethylene carbonate (DFEC)/trifluoroethyl methyl carbonate (FEMC) electrolyte system to enable the cycling of lithium metal anode. The addition of FEC alters the structures of lithium complexes in solution because of its relatively high solvating power. Through the precise control of the solvation number (> 1) of fluorinated cyclic carbonate (i.e., FEC:DFEC > critical ratio), lithium complexes with Li+ solvated solely by FEMC, which decompose on the lithium surface to form detrimental by-products, can be effectively eliminated. The new ternary FEC/DFEC/FEMC system not only maintains the beneficial effect of DFEC in forming a robust solid-electrolyte interphase on the lithium anode, but also confers outstanding anodic stability provided by FEMC, while eliminating detrimental FEMC decomposition through the solvation protection effect of FEC. Clearly, this ternary system outperforms the FEC/FEMC and DFEC/FEMC binary systems in facilitating the stable cycling of LMBs.



中文翻译:

用于锂金属电池的具有溶剂化保护功能的高压电解液

为了促进锂金属电池(LMB)的实际应用,必须在电解质和锂金属之间实现稳定的界面。在此,我们介绍了一种溶剂化保护策略,用于设计用于高压 LMB 的功能性电解质。氟代碳酸亚乙酯(FEC)被引入作为二氟碳酸亚乙酯(DFEC)/三氟乙基甲基碳酸酯(FEMC)电解质体系的溶剂化保护溶剂,以实现锂金属负极的循环。FEC 的添加改变了溶液中锂复合物的结构,因为它具有相对较高的溶剂化能力。通过精确控制氟化环状碳酸酯的溶剂化数(> 1)(即 FEC:DFEC > 临界比),锂与 Li +仅由 FEMC 溶剂化,在锂表面分解形成有害副产物,可以有效地消除。新的三元 FEC/DFEC/FEMC 体系不仅保持了 DFEC 在锂负极上形成坚固的固体电解质界面的有益效果,而且赋予了 FEMC 出色的阳极稳定性,同时通过溶剂化保护作用消除了有害的 FEMC 分解FEC 的。显然,这种三元系统在促进 LMB 的稳定循环方面优于 FEC/FEMC 和 DFEC/FEMC 二元系统。

更新日期:2021-12-01
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