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Ordered LiNi0.5Mn1.5O4 cathode in bis(fluorosulfonyl)imide-based ionic liquid electrolyte: importance of the cathode–electrolyte interphase

DOI: 10.1021/acs.chemmater.0c04014 DOI Help

Authors: Hyeon Jeong Lee (University of Oxford) , Zachary Brown (University of Oxford) , Ying Zhao (Tongji University) , Jack Fawdon (University of Oxford) , Weixiao Song (University College London) , Ji Hoon Lee (Kyungpook National University) , Johannes Ihli (University of Oxford) , Mauro Pasta (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry Of Materials

State: Published (Approved)
Published: February 2021
Diamond Proposal Number(s): 22264

Abstract: The high-voltage (4.7 V vs Li+/Li) spinel lithium nickel manganese oxide (LiNi0.5Mn1.5O4, LNMO) is a promising candidate for the next generation of lithium-ion batteries due to its high energy density, low cost, and low 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, 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (Pyr1,3FSI), to achieve stable cycling performance and improve the rate capability. The optimized cathode–electrolyte system exhibits extended cycling performance (>85% capacity retention after 300 cycles) and high rate performance (106.2 mAh g–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.

Journal Keywords: Layers; Electrodes; Electrochemical cells; Transition metals; Electrolytes

Subject Areas: Materials, Chemistry, Energy

Instruments: I14-Hard X-ray Nanoprobe

Other Facilities: 17-BM-B beamline at Advanced Photon Source

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