Potentiometric Study to Reveal Reaction Entropy Behavior of Biphasic Na1+2xV2(PO4)3 Electrodes

Satoshi Kajiyama, Kazuhiko Kai, Masashi Okubo, Atsuo Yamada*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Sodium-ion batteries potentially provide the opportunities to realize the energy storage system beyond the stateof- the-art lithium-ion batteries, though at present their performance is limited partly due to lack of suitable positive electrode materials. NASICON-type Na3V2(PO4)3 is a promising candidate for the positive electrode materials because of its high capacity and high operating potential, however, the electrode reaction of Na1+2xV2(PO4)3 (0 : x : 1) including a biphasic region is not yet fully understood. Here, in order to clarify the microscopic mechanism of the biphasic reaction, the reaction entropy of the electrochemical cell including the Na1+2xV2(PO4)3 positive electrode was measured using the potentiometric method. The temperature-dependent open-circuitvoltage reveals that the reaction entropy is almost constant for 0.1 : x : 0.9. The constant reaction entropy of the electrochemical cell suggests that the electrode reaction proceeds through the boundary migration between the Na-rich and -poor phases without substantial change in the configurational entropy.

Original languageEnglish
Pages (from-to)234-237
Number of pages4
Issue number4
Publication statusPublished - 2016 Apr
Externally publishedYes


  • NaV(PO)
  • Reaction Entropy
  • Sodium-ion Battery

ASJC Scopus subject areas

  • Electrochemistry


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