Ma Shunchao, Cong Lina, Fu Fang, Rumesh Madhusanka Suwanda Arachchige Don, Wang Hongyu, Xie Haiming
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
National & Local United Engineering Laboratory for Power Battery, Department of Chemistry, Northeast Normal University, Changchun, 130024, P. R. China.
Small. 2024 Aug;20(32):e2308959. doi: 10.1002/smll.202308959. Epub 2024 Mar 19.
Hitherto, highly concentrated electrolyte is the overarching strategy for revitalizing the usage of amide - in lithium-metal batteries (LMBs), which simultaneously mitigates the reactivity of amide toward Li and regulates uniform Li deposition via forming anion-solvated coordinate structure. However, it is undeniable that this would bring the cost burden for practical electrolyte preparation, which stimulates further electrolyte design toward tailoring anion-abundant Li solvation structure in stable amide electrolytes under a low salt content. Herein, a distinct method is conceived to design anions-enriched Li solvation structure in dilute amide-electrolyte (1 m Li-salt concentration) with the aid of integrating perfluoropolyethers (PFPE-MC) with anion-solvating ability and B/F-involved additives. The optimized electrolyte based on N,N-Dimethyltrifluoroacetamide (FDMAC) exhibits outstanding compatibility with Li and NCM622 cathode, facilitates uniform Li deposition along with robust solid electrolyte interphase (SEI) formation. Accordingly, both the lab-level LMB coin cell and practical pouch cell based on this dilute FDMAC electrolyte deliver remarkable performances with improved capacity and cyclability. This work pioneers the feasibility of diluted amide as electrolyte in LMB, and provides an innovative strategy for highly stable Li deposition via manipulating solvation structure within diluent electrolyte, impelling the electrolyte engineering development for practical high-energy LMBs.
迄今为止，高浓度电解质是恢复酰胺类电解质在锂金属电池（LMBs）中应用的总体策略，它既能降低酰胺对锂的反应活性，又能通过形成阴离子溶剂化配位结构来调节锂的均匀沉积。然而，不可否认的是，这会给实际电解质的制备带来成本负担，从而促使人们进一步设计电解质，以在低盐含量下的稳定酰胺电解质中定制富含阴离子的锂溶剂化结构。在此，我们构思了一种独特的方法，借助具有阴离子溶剂化能力的全氟聚醚（PFPE-MC）和含硼/氟添加剂，在稀酰胺电解质（锂盐浓度为1 m）中设计富含阴离子的锂溶剂化结构。基于N,N-二甲基三氟乙酰胺（FDMAC）的优化电解质与锂和NCM622正极具有出色的兼容性，有助于锂的均匀沉积以及坚固的固体电解质界面（SEI）的形成。因此，基于这种稀FDMAC电解质的实验室级LMB硬币电池和实际软包电池均表现出卓越的性能，容量和循环稳定性得到了提高。这项工作开创了稀酰胺作为LMB电解质的可行性，并通过在稀释电解质中操控溶剂化结构为高度稳定的锂沉积提供了一种创新策略，推动了实用高能LMB电解质工程的发展。
