Electrochemical performance of mixed valence Na3V 2O2x(PO4)2F3-2x/C as cathode for sodium-ion batteries

Paula Serras, Verónica Palomares, Aintzane Goñi, Pierre Kubiak, Teófilo Rojo

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59 Citations (Scopus)


A composite made of a mixed-valence sodium-vanadium fluorophosphate and 6.4% wt. carbon, Na3V2O2x(PO4) 2F3-2x/C (0 < x < 1), has been prepared. Structural and magnetic characterization confirmed the +3/+4 oxidation state of vanadium in the phase. Morphological and texture analyses showed that carbon forms a network surrounding the particles, leading to a mesoporous composite with a high specific area of 67 m2 g-1. Electrochemical characterization conducted in Swagelok cells by cyclic voltammetry and galvanostatic cycling indicated that sodium extraction/insertion proceeds through a complex mechanism in two voltage pseudo-plateaux at 3.6 and 4.1 V vs. Na/Na+. Rate capability of the material ranges from specific capacities of 100 mAh g-1 at C/20 to 75 mAh g-1 at 5C. Cycling stability at 1C showed coulombic efficiency higher than 99% and capacity retention of 95% after 200 cycles.

Original languageEnglish
Pages (from-to)56-60
Number of pages5
JournalJournal of Power Sources
Publication statusPublished - 27 May 2013



  • Electrochemistry
  • Mixed-valence
  • Na-ion batteries
  • Sodium vanadium fluorophosphates

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

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