Identifying the Structural Evolution of the Sodium Ion Battery Na ₂ FePO ₄ F Cathode

Journal Article · 18 August 2018 · Angewandte Chemie

DOI: https://doi.org/10.1002/ange.201805555 · OSTI ID:1465217

Li, Qi ^[1]; Liu, Zigeng  ^[2]; Zheng, Feng ^[3]; Liu, Rui ^[1]; Lee, Jeongjae ^[4]; Xu, Gui‐Liang ^[5]; Zhong, Guiming ^[6]; Hou, Xu ^[1]; Fu, Riqiang  ^[7]; Chen, Zonghai ^[5]; Amine, Khalil ^[8]; Mi, Jinxiao ^[9]; Wu, Shunqing  ^[3]; Grey, Clare P. ^[4]; Yang, Yong  ^[1]

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1. State Key Lab of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials and Department of Chemistry Xiamen University Xiamen 361005 China
2. Department of Chemistry University of Cambridge Lensfield Rd Cambridge CB2 1EW UK, Current address: Max-Plank-Institut für Chemische Energiekonversion Stiftstr. 34–36 45470 Mülheim an der Ruhr Germany, Institut für Energie und Klimaforschung (IEK-9) Forschungszentrum Jülich GmbH 52425 Germany
3. Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices Department of Physics Xiamen University Xiamen 361005 China
4. Department of Chemistry University of Cambridge Lensfield Rd Cambridge CB2 1EW UK
5. Chemical Sciences and Engineering Division Argonne National Laboratory 9700 South Cass Avenue Argonne Illinois 60439 USA
6. State Key Lab of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials and Department of Chemistry Xiamen University Xiamen 361005 China, Xiamen Institute of Rare Earth Materials Chinese Academy of Sciences Xiamen 361021 China
7. National High Magnetic Field Laboratory 1800 E. Paul Dirac Drive Tallahassee Florida 32310 USA
8. Chemical Sciences and Engineering Division Argonne National Laboratory 9700 South Cass Avenue Argonne Illinois 60439 USA, Materials Science and Engineering Stanford University Stanford California 94305 USA
9. Department of Material Science and Engineering Xiamen University Xiamen 361005 China

Abstract Na ₂ FePO ₄ F is a promising cathode material for Na‐ion batteries owing to its relatively high discharge voltage and excellent cycling performance. Now, the long‐ and short‐range structural evolution of Na ₂ FePO ₄ F during cycling is studied by in situ high‐energy X‐ray diffraction (XRD), ex situ solid‐state nuclear magnetic resonance (NMR), and first‐principles DFT calculations. DFT calculations suggest that the intermediate phase, Na _1.5 FePO ₄ F, adopts the space group of P 2 ₁ / c , which is a subgroup ( P 2 ₁ / b 11, No. 14) of Pbcn (No. 60), the space group of the starting phase, Na ₂ FePO ₄ F, and this space group provides a good fit to the experimental XRD and NMR results. The two crystallographically unique Na sites in the structure of Na ₂ FePO ₄ F behave differently during cycling, where the Na ions on the Na2 site are electrochemically active while those on the Na1 site are inert. This study determines the structural evolution and the electrochemical reaction mechanisms of Na ₂ FePO ₄ F in a Na‐ion battery.

• Sponsoring Organization: USDOE
• Grant/Contract Number: NONE; SC0012704; AC02-06CH11357
• OSTI ID: 1465217
• Journal Information: Angewandte Chemie, Journal Name: Angewandte Chemie Journal Issue: 37 Vol. 130; ISSN 0044-8249
• Publisher: Wiley Blackwell (John Wiley & Sons)Copyright Statement
• Country of Publication: Germany
• Language: English