揭示了超低温金属电池的离子溶剂相互作用
Jijian Xu1,2, Volodymyr Koverga3,4, An Phan1
1Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA.
Advanced materials (Deerfield Beach, Fla.)
|November 28, 2023
概括
研究电解质中的离子溶解表明,更强的相互作用,特别是与FTFSI等不对称离子相互作用,在低温下显著提高金属电池的性能. 这导致了涂/剥离效率的提高和稳定的循环.
科学领域:
- 电化学 电化学 电化学
- 材料科学 材料科学 材料科学
- 物理化学 物理化学
背景情况:
- 阳离子溶解显著影响电解质性能,但仍未得到充分研究.
- 了解离子-溶剂相互作用对于设计先进的电解质至关重要.
研究的目的:
- 系统地检查 bis{trifluoromethanesulfonyl}imide (TFSI),bis{fluorosulfonyl}imide (FSI) 和非对称的 (fluorosulfonyl) 的溶解行为.
- 阐明阴离子溶解在提高电化学性能,特别是在低温下发挥的作用.
主要方法:
- 在现场液态二次离子质谱 (LSIMS) 用于分析离子-溶剂相互作用.
- 分子建模以了解阴离子-溶剂相互作用的性质.
- 涂层/脱落和全细胞的电化学测试.
主要成果:
- 与TFSI-和FSI-离子不同的是,FTSI-和FSI-离子与3-烯乙烯 (BFPE) 溶剂有显著的关联,与TFSI-.
- 阳离子溶解增强了Li + 阴离子转移数,并减少了固体电解质介相 (SEI) 中的有机成分.
- 用FTFSI和FSI基的电解质,在-30°C的Coulombic效率从42.4%提高到97%以上.
结论:
- 较强的离子-溶剂相互作用,特别是与不对称的离子相互作用,加速Li+溶解动力学.
- 1.5米 LiFTFSI-BFPE 电解质在-40°C下显示了NMC811的稳定循环,在100个循环后保持了92%以上的容量.
- 对离子溶剂相互作用的洞察力使得高性能金属电池的合理电解质设计成为可能.
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