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Journal Articles Energy Storage Materials Year : 2023

Mastering the synergy between Na 3 V 2 (PO 4 ) 2 F 3 electrode and electrolyte: A must for Na-ion cells

Parth Desai
Juan Forero-Saboya
  • Function : Author
Valentin Meunier
  • Function : Author
Gwenaëlle Rousse
  • Function : Author
Michael Deschamps
  • Function : Author
Artem Abakumov
  • Function : Author

Abstract

Sodium-ion batteries are emerging as suitable energy storage devices for special applications such as high-power devices with the advantages of being cheaper and more sustainable than the Li-ion equivalents. The sodium ion cells consisting of polyanionic Na 3 V 2 (PO 4) 2 F 3-hard carbon electrodes exhibit high power rate capabilities but limited cycle life, especially at high temperatures. To circumvent this drawback we herein conducted in-depth analyses of the origins of structural degradations occurring in Na 3 V 2 (PO 4) 2 F 3 electrodes upon long cycling. Vanadium dissolution with associated parasitic reactions is identified as one of the major reasons for cell failure. Its amount varies depending on the electrolyte, with NaTFSI-based electrolyte showing the least vanadium dissolution as the TFSI-anion decomposes without producing acidic impurities, in contrast to the Na-PF 6-based electrolyte. The dissolved vanadium species undergoes oxidation and reduction processes at the Na 3 V 2 (PO 4) 2 F 3 and HC electrodes, respectively, with the electrochemical signature of these processes being used as a fingerprint to identify state of health of the 18650 cells. Having found that surface reactivity is the primary cause of vanadium dissolution we provide methods to mitigate it by combining surface coating and optimized electrolyte formulation.
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hal-04047176 , version 1 (27-03-2023)

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Parth Desai, Juan Forero-Saboya, Valentin Meunier, Gwenaëlle Rousse, Michael Deschamps, et al.. Mastering the synergy between Na 3 V 2 (PO 4 ) 2 F 3 electrode and electrolyte: A must for Na-ion cells. Energy Storage Materials, 2023, 57, pp.102-117. ⟨10.1016/j.ensm.2023.02.004⟩. ⟨hal-04047176⟩
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