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Corresponding Author

Yong YANG(yyang@xmu.edu.cn)

Abstract

The Na2MnPO4F is one of the promising cathode materials for the sodium ion batteries. In the paper, we employed the ex situ X-ray diffraction and solid state NMR techniques to study the charge and discharge processes of this material, including the crystal structure and sodium sites changes. The ex situ x-ray diffraction patterns showed that two new diffraction peaks could be observed at 31o and 36o indicating an intermediate phase formed with the extraction of Na+. From the 23Na MAS NMR spectrum of the material, three peaks were seen at -209 ppm,-258 ppm and -295 ppm, which can be assigned to Na1 + Na2, Na3 and Na4 sites in the crystal structure, respectively. The ex situ solid state NMR study demonstrated that the Na+ in Na1 and Na2 sites deintercalated firstly compared to Na3 and Na4 sites. The signal peaks of intermediate phase appeared at -132 ppm and -330 ppm when charging to 4.2 V. The opposite phenomenon occurred during the discharge process.

Graphical Abstract

Keywords

sodium ion batteries, cathode material, Na2MnPO4F, 23Na MAS NMR

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Publication Date

2014-06-28

Online Available Date

2014-04-21

Revised Date

2014-04-14

Received Date

2014-04-01

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