Fluorinated High-Voltage Electrolytes To Stabilize Nickel-Rich Lithium Batteries

Journal Article · Mon Sep 11 00:00:00 EDT 2023 · ACS Applied Materials and Interfaces

DOI:https://doi.org/10.1021/acsami.3c06586· OSTI ID:2352213

Poches, Christopher ^[1]; Razzaq, Amir Abdul ^[1]; Studer, Haiden ^[1]; Ogilvie, Regan ^[1]; Lama, Bhubnesh ^[1]; Paudel, Tula R. ^[1]; Li, Xuguang ^[2]; Pupek, Krzysztof ^[3]; Xing, Weibing ^[1]

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1. South Dakota School of Mines and Technology, Rapid City, SD (United States)
2. Lynntech Inc., College Station, TX (United States)
3. Argonne National Laboratory (ANL), Argonne, IL (United States)

As state-of-the-art (SOA) lithium-ion (Li-ion) batteries approach their specific energy limit (~250 Wh kg^-1), layer-structured, nickel-rich (Ni-rich) lithium transition metal oxide-based cathode materials, e. g., LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811), have attracted great interest owing to their practical high specific capacities (>200 mAhg^-1). Coupled with their high average discharge voltages (~4 V vs Li/Li⁺), Ni-rich cathode-based lithium batteries possess a great potential to achieve much higher specific energies (>350 Wh kg^-1 at the cell level) than the SOA Li-ion counterparts. In addition, Ni-rich oxides are low-cost battery cathode materials due to their low cobalt contents. However, Ni-rich cathode-based lithium batteries suffer quick capacity degradations upon cycling, particularly at high upper cutoff voltages (e.g., ≥= 4.5 V vs Li/Li⁺), due to crystal structure changes of the active cathode materials and parasitic side reactions at the electrolyte/electrode interfaces. In this study, a fluorinated-solvent-based, high-voltage stable electrolyte (HVE), i.e., 1 M Li bis(trifluoromethanesulfonyl)imide (LiTFSI) in fluoroethylene carbonate (FEC), bis(2,2,2-trifluoroethyl) carbonate (FDEC), and methyl (2,2,2-trifluoroethyl) carbonate (FEMC) with Li difluoro(oxalate)borate (LiDFOB) additive, was formulated and evaluated in Li/NMC811 battery cells. Further, to the best of our knowledge, this class of electrolyte has not been investigated for Ni-rich cathode-based lithium batteries. Li/NMC811 cells with HVE exhibited a superior long-term cycle performance stability, maintaining ~80% capacity after ~500 cycles at a high cutoff voltage of 4.5 V (vs Li/Li⁺) than a baseline carbonate-solvent-based electrolyte (BE). The superior cycle stability of the Li/NMC811 cells is attributed to the inherently high-voltage stability of HVE, supported by the physical and electrochemical analyses. This conclusion is supported by our density functional theory (DFT) modeling where HVE shows a less tendency of deprotonation/oxidation than BE, leading to the observed cycle stability. The findings in this study are important to help tackle the technical challenges facing Ni-rich cathode-based lithium batteries to realize their high energy density potentials with a long cycle life.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Vehicle Technologies Office (VTO); Naval Air Warfare Center Weapons Division (NAWCWD)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 2352213
• Journal Information: ACS Applied Materials and Interfaces, Journal Name: ACS Applied Materials and Interfaces Journal Issue: 37 Vol. 15; ISSN 1944-8244
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
density functional theory modeling
fluorinated high-voltage electrolytes
fluorinated solvents
lithium-ion batteries
nickel-rich cathodes