High-Polarity Fluoroalkyl Ether Electrolyte Enables Solvation-Free Li+ Transfer for High-Rate Lithium Metal Batteries

Liwei Dong; Yuanpeng Liu; Kechun Wen; Dongjiang Chen; Dewei Rao; Jipeng Liu; Botao Yuan; Yunfa Dong; Ze Wu; Yifang Liang; Mengqiu Yang; Jianyi Ma; Chunhui Yang; Chuan Xia; Baoyu Xia; Jiecai Han; Gongming Wang; Zaiping Guo; Weidong He

doi:10.1002/advs.202104699

High-Polarity Fluoroalkyl Ether Electrolyte Enables Solvation-Free Li⁺ Transfer for High-Rate Lithium Metal Batteries

Adv Sci (Weinh). 2022 Feb;9(5):e2104699. doi: 10.1002/advs.202104699. Epub 2021 Dec 19.

Authors

Liwei Dong^{1

2

3}, Yuanpeng Liu¹, Kechun Wen¹, Dongjiang Chen⁴, Dewei Rao⁵, Jipeng Liu^{1

2}, Botao Yuan¹, Yunfa Dong¹, Ze Wu², Yifang Liang^{1

2}, Mengqiu Yang^{1

2}, Jianyi Ma⁶, Chunhui Yang^{2

3}, Chuan Xia⁷, Baoyu Xia⁸, Jiecai Han¹, Gongming Wang⁹, Zaiping Guo¹⁰, Weidong He^{1

4}

Affiliations

¹ National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, and Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150080, China.
² MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150080, China.
³ State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150080, China.
⁴ School of Mechanical Engineering, Chengdu University, Chengdu, 610106, China.
⁵ School of Material Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013, China.
⁶ Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, China.
⁷ School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu, 611731, China.
⁸ Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), Hubei Key Laboratory of Material Chemistry and Service Failure, Wuhan National Laboratory for Optoelectronics, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan, 430074, China.
⁹ Department of Chemistry and Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Anhui, 230026, China.
¹⁰ School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA, 5005, Australia.

Abstract

Lithium metal batteries (LMBs) have aroused extensive interest in the field of energy storage owing to the ultrahigh anode capacity. However, strong solvation of Li⁺ and slow interfacial ion transfer associated with conventional electrolytes limit their long-cycle and high-rate capabilities. Herein an electrolyte system based on fluoroalkyl ether 2,2,2-trifluoroethyl-1,1,2,3,3,3-hexafluoropropyl ether (THE) and ether electrolytes is designed to effectively upgrade the long-cycle and high-rate performances of LMBs. THE owns large adsorption energy with ether-based solvents, thus reducing Li⁺ interaction and solvation in ether electrolytes. With THE rich in fluoroalkyl groups adjacent to oxygen atoms, the electrolyte owns ultrahigh polarity, enabling solvation-free Li⁺ transfer with a substantially decreased energy barrier and ten times enhancement in Li⁺ transference at the electrolyte/anode interface. In addition, the uniform adsorption of fluorine-rich THE on the anode and subsequent LiF formation suppress dendrite formation and stabilize the solid electrolyte interphase layer. With the electrolyte, the lithium metal battery with a LiFePO₄ cathode delivers unprecedented cyclic performances with only 0.0012% capacity loss per cycle over 5000 cycles at 10 C. Such enhancement is consistently observed for LMBs with other mainstream electrodes including LiCoO₂ and LiNi_0.5 Mn_0.3 Co_0.2 O₂ , suggesting the generality of the electrolyte design for battery applications.

Keywords: Li+ solvation structure; fluoroalkyl ether; high rate; lithium metal batteries; long cycle.

Abstract

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