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Ordered LiNi0.5Mn1.5O4 Cathode in Bis(fluorosulfonyl)imide-Based Ionic Liquid Electrolyte: Importance of the Cathode-Electrolyte Interphase

preprint
submitted on 25.09.2020 and posted on 25.09.2020 by Hyeon Jeong Lee, Zachary Brown, Ying Zhao, Jack Fawdon, Weixin Song, Ji Hoon Lee, Mauro Pasta

The high voltage (4.7 V vs. Li+ /Li) spinel lithium nickel manganese oxide (LiNi0.5 Mn1.5 O4 , LNMO) is a promising candidate for the next-generation of lithium ion batteries due to its high energy density, low cost and environmental impact. However, poor cycling performance at high cutoff potentials limits its commercialization. Herein, hollow structured LNMO is synergistically paired with an ionic liquid electrolyte, 1M lithium bis(fluorosulfonyl)imide (LiFSI) in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (Pyr1,3 FSI) to achieve stable cycling performance and improved rate capability. The optimized cathode-electrolyte system exhibits extended cycling performance (>85% capacity retention after 300 cycles) and high rate performance (106.2mAhg–1 at 5C) even at an elevated temperature of 65 ◦C. X-ray photoelectron spectroscopy and spatially resolved x-ray fluorescence analyses confirm the formation of a robust, LiF-rich cathode electrolyte interphase. This study presents a comprehensive design strategy to improve the electrochemical performance of high-voltage cathode materials.

Funding

ISCF Faraday Challenge project SOLBAT [grant number FIRG007]

Henry Royce Institute (through UK Engineering and Physical Science Research Council grant EP/R010145/1)

Diamond Light Source under proposal MG22264

APS Contract No. DE-AC02-06CH11357

National Research Foundation of Korea (NRF-2019R1A6A3A03031343)

History

Email Address of Submitting Author

mauro.pasta@materials.ox.ac.uk

Institution

University of Oxford

Country

United Kingdom

ORCID For Submitting Author

0000-0002-2613-4555

Declaration of Conflict of Interest

No conflict of interest

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