Nafion membranes with a sulfonated organic additive for the use in vanadium redox flow batteries

Yona Lee, Sangwon Kim, Rolf Hempelmann, Jong Hyun Jang, Hyoung Juhn Kim, Jonghee Han, Jihyun Kim, Dirk Henkensmeier

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Sulfonated copper phthalocyanine (CuPCSA) was embedded into Nafion membranes in ratios of 0, 1.25, 2.5, 5, and 7.5 wt %. The absence of CuPCSA related peaks in WAXS patterns indicated that CuPCSA did not form crystalline phases during membrane formation. Tensile strength and Young's modulus were highest in the range of 2.5–5 wt % CuPCSA. As demonstrated for Nafion 212, the weight gain and swelling in water-based solutions decreases when the sulfuric acid concentration increases from 0 to 2 M. In 2 M sulfuric acid, addition of CuPCSA increases the weight gain. In contact with VO 2 + , blue CuPCSA is oxidatively hydrolyzed to form colorless sulfonated phthalimide. XPS analysis showed that (1) this reaction is quantitative and (2) that the sulfonated phthalimide does not leach out from the membrane during operation in the flow battery. The coulomb efficiency increases with the amount of phthalimide. This affects the energy efficiency so strongly, that it follows the same trend as the coulomb efficiency. During cycling, the cell with Nafion/7.5 wt % filler showed the highest discharge capacity and the lowest difference between charge and discharge capacity.

Original languageEnglish
Article number47547
JournalJournal of Applied Polymer Science
Issue number21
Publication statusPublished - 2019 Jun 5

Bibliographical note

Funding Information:
This work was supported by the German-Korean joint SME R&D projects program of MOTIE/KIAT (No. 20151732).

Publisher Copyright:
© 2019 Wiley Periodicals, Inc.


  • Nafion
  • membranes
  • sulfonated copper phthalocyanine
  • sulfonated phthalimide
  • vanadium redox flow battery (VRFB)

ASJC Scopus subject areas

  • General Chemistry
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry


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