Carbonate electrolytes are the primary determinant for the development of low-temperate lithium metal batteries (LT-LMBs). However, conventional ethyl carbonate (EC)-based electrolytes with solvent-dominated solvation configuration suffer from sluggish reaction kinetics, severe interfacial side reactions and high Li+ desolvation energy under low temperature. Herein, an EC-free and weakly solvated electrolyte consisting of LiDFOB and mixed solvents including dimethyl sulfite (DMS), ethyl trifluoroacetate (ETFA) and fluoroethylene carbonate (FEC) was designed to facilitate the reaction kinetics and stabilize the interfaces of LT-LMBs, where a fluoride-rich solvation structure including FEC, ETFA and DFOB- is formed in the designed electrolyte. Such solvation configuration could significantly facilitate the desolvation process and induce the homogeneous Li deposition by forming high ionic conductive and inorganics-rich protective film on the electrode surfaces. With such electrolyte, the Li||NCM811 cell retains a high capacity retention of 81.7% after 1000 cycles, which is far superior to the 31.3% for EC-based electrolyte. Even at −40°C, the cell exhibits a capacity of 125.7 mAh g-1 with almost no capacity attenuation after 200 cycles. This work confirms the necessity of fluoride-dominated solvation structure in decreasing the desolvation energy and accelerating the ionic transfer, contributing a promising solution to the development of low-temperature LMBs.

中文翻译：

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通过电解质工程定制氟化物为主的亚硫酸二甲酯的电解质溶剂化，以实现低温电池


碳酸盐电解质是低温带锂金属电池 （LT-LMB） 发展的主要决定因素。然而，传统的基于碳酸乙酯 （EC） 的电解质具有溶剂为主的溶剂化构型，在低温下反应动力学缓慢、界面副反应严重和 Li+ 脱溶剂能量高。在此，设计了一种由 LiDFOB 和包括亚硫酸二甲酯 （DMS）、三氟乙酸乙酯 （ETFA） 和氟乙烯酸乙烯酯 （FEC） 在内的混合溶剂组成的无 EC 和弱溶剂化电解质，以促进反应动力学并稳定 LT-LMBs 的界面，其中在设计的电解质中形成包括 FEC、ETFA 和 DFOB- 在内的富氟溶剂化结构。这种溶剂化构型可以显着促进脱溶剂化过程，并通过在电极表面形成高离子导电和富含无机物的保护膜来诱导均匀的锂沉积。有了这样的电解质，Li||NCM811 电池在 1000 次循环后仍能保持 81.7% 的高容量保持率，远优于 EC 基电解液的 31.3%。即使在 −40°C 下，该电池的容量也为 125.7 mAh g-1，并且在 200 次循环后几乎没有容量衰减。这项工作证实了氟化物为主的溶剂化结构在降低脱溶剂能量和加速离子转移方面的必要性，为低温 LMB 的开发提供了有前途的解决方案。