Superior electrocatalytic activity of a robust carbon-felt electrode with oxygen-rich phosphate groups for all-vanadium redox flow batteries

Ki Jae Kim, Heon Seong Lee, Jeonghun Kim, Min Sik Park, Jung Ho Kim, Young Jun Kim, Maria Skyllas-Kazacos

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59 Citations (Scopus)

Abstract

A newly prepared type of carbon felt with oxygen-rich phosphate groups is proposed as a promising electrode with good stability for all-vanadium redox flow batteries (VRFBs). Through direct surface modification with ammonium hexafluorophosphate (NH4PF6), phosphorus can be successfully incorporated onto the surface of the carbon felt by forming phosphate functional groups with -OH chemical moieties that exhibit good hydrophilicity. The electrochemical reactivity of the carbon felt toward the redox reactions of VO2+/VO2+ (in the catholyte) and V3+/V2+ (in the anolyte) can be effectively improved owing to the superior catalytic effects of the oxygen-rich phosphate groups. Furthermore, undesirable hydrogen evolution can be suppressed by minimizing the overpotential for the V3+ /V2+ redox reaction in the anolyte of the VRFB. Cell-cycling tests with the catalyzed electrodes show improved energy efficiencies of 88.2 and 87.2% in the 1st and 20th cycles compared with 83.0 and 81.1 %, respectively, for the pristine electrodes at a constant current density of 32 mAcm-2. These improvements are mainly attributed to the faster charge transfer allowed by the integration of the oxygen-rich phosphate groups on the carbon-felt electrode.

Original languageEnglish
Pages (from-to)1329-1338
Number of pages10
JournalChemSusChem
Volume9
Issue number11
DOIs
Publication statusPublished - 2016 Jun 8

Bibliographical note

Funding Information:
This work was partially supported by the Energy Efficiency & Resources Core Technology Program (Project No. 20132020000340) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), and the Korea Evaluation Institute of Industrial Technologies R&D Program (Project No. 10041942, KEIT) of the Ministry of Trade, Industry, and Energy, Republic of Korea.

Publisher Copyright:
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Chemical Engineering(all)
  • Materials Science(all)
  • Energy(all)

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