Fluorinated Rocksalt Cathode with Ultra-high Active Li Content for Lithium-ion Batteries

Yi Pei; Qing Chen; Yang Ha; Dong Su; Hua Zhou; Shuang Li; Zhenpeng Yao; Lu Ma; Kevin J Sanders; Chuanchao Sheng; Gillian R Goward; Lin Gu; Aiping Yu; Wanli Yang; Zhongwei Chen

doi:10.1002/anie.202212471

Fluorinated Rocksalt Cathode with Ultra-high Active Li Content for Lithium-ion Batteries

Angew Chem Int Ed Engl. 2022 Nov 21;61(47):e202212471. doi: 10.1002/anie.202212471. Epub 2022 Oct 20.

Authors

Yi Pei¹, Qing Chen¹, Yang Ha², Dong Su³, Hua Zhou⁴, Shuang Li⁵, Zhenpeng Yao⁶, Lu Ma⁷, Kevin J Sanders⁸, Chuanchao Sheng⁹, Gillian R Goward⁸, Lin Gu³, Aiping Yu¹, Wanli Yang², Zhongwei Chen¹

Affiliations

¹ Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2 L 3G1, Canada.
² Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA.
³ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
⁴ Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA.
⁵ Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA.
⁶ Department of Chemistry and Department of Computer Science, University of Toronto, Toronto, Ontario, M5S 3H6, Canada.
⁷ National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.
⁸ Department of Chemistry, McMaster University, Hamilton, ON L8S 4 L8, Canada.
⁹ Center of Energy Storage Materials & Technology, College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.

PMID: 36265124
DOI: 10.1002/anie.202212471

Abstract

The key to increasing the energy density of lithium-ion batteries is to incorporate high contents of extractable Li into the cathode. Unfortunately, this triggers formidable challenges including structural instability and irreversible chemistry under operation. Here, we report a new kind of ultra-high Li compound: Li_4+x MoO₅ F_x (1≤x≤3) for cathode with an unprecedented level of electrochemically active Li (>3 Li⁺ per formula), delivering a reversible capacity up to 438 mAh g^-1 . Unlike other reported Li-rich cathodes, Li_4+x MoO₅ F_x presents distinguished structure stability to immunize against irreversible behaviors. Through spectroscopic and electrochemical techniques, we find an anionic redox-dominated charge compensation with negligible oxygen release and voltage decay. Our theoretical analysis reveals a "reductive effect" of high-level fluorination stabilizes the anionic redox by reducing the oxygen ions in pure-Li conditions, enabling a facile, reversible, and high Li-portion cycling.

Keywords: Anionic Redox; High Fluorination Level; Reductive Effect; Ultra-High Li Cathode.

Abstract

Grants and funding