High-Performance Lithium Metal Batteries Enabled by a Fluorinated Cyclic Ether with a Low Reduction Potential

Min Wu; Zeyi Wang; Weiran Zhang; Chamithri Jayawardana; Yue Li; Fu Chen; Bo Nan; Brett L Lucht; Chunsheng Wang

doi:10.1002/anie.202216169

High-Performance Lithium Metal Batteries Enabled by a Fluorinated Cyclic Ether with a Low Reduction Potential

Angew Chem Int Ed Engl. 2023 Feb 13;62(8):e202216169. doi: 10.1002/anie.202216169. Epub 2023 Jan 18.

Authors

Min Wu¹, Zeyi Wang¹, Weiran Zhang², Chamithri Jayawardana³, Yue Li⁴, Fu Chen⁴, Bo Nan⁴, Brett L Lucht³, Chunsheng Wang^{1

2}

Affiliations

¹ Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA.
² Department of Materials Science & Engineering, University of Maryland, College Park, MD 20742, USA.
³ Department of Chemistry, University of Rhode Island, Kingston, RI 02881, USA.
⁴ Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.

Abstract

Electrolyte engineering is crucial for developing high-performance lithium metal batteries (LMB). Here, we synthesized two cosolvents methyl bis(fluorosulfonyl)imide (MFSI) and 3,3,4,4-tetrafluorotetrahydrofuran (TFF) with significantly different reduction potentials and add them into LiFSI-DME electrolytes. The LiFSI/TFF-DME electrolyte gave an average Li Coulombic efficiency (CE) of 99.41 % over 200 cycles, while the average Li CEs for MFSI-based electrolyte is only 98.62 %. Additionally, the TFF-based electrolytes exhibited a more reversible performance than the state-of-the-art fluorinated 1,4-dimethoxylbutane electrolyte in both Li||Cu half-cell and anode-free Cu||LiNi_0.8 Mn_0.1 Co_0.1 O₂ full cell. More importantly, the decomposition product from bis(fluorosulfonyl)imide anion could react with ether solvent, which destroyed the SEI, thus decreasing cell performance. These key discoveries provide new insights into the rational design of electrolyte solvents and cosolvents for LMB.

Keywords: Anode-Free; Electrolyte Engineering; Fluorinated Ether; Reduction Potential; Solubility.

Grants and funding

DE-AC05-76RL01830/Vehicle Technologies Office