Advanced Nafion nanocomposite membrane embedded with unzipped and functionalized graphite nanofibers for high-temperature hydrogen-air fuel cell system: The impact of filler on power density, chemical durability and hydrogen permeability of membrane

Vinothkannan Mohanraj, Ae Rhan Kim, S. Ramakrishnan, Yeon-Tae Yu, Dong Jin Yoo

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)

Abstract

Nafion, a perfluorosulfonic acid (PFSA) polymer, is a key electrolyte that has contributed to commercialization of hydrogen-air fuel cells (HAFCs). However, adoption of Nafion membranes in high-temperature (HT) HAFCs remains an unsolved challenge. In this work, sulfonic acid-functionalized, unzipped graphite nanofiber (SO3H-UGNF) is explored as a potential filler for Nafion to create a composite membrane for HT-HAFCs. The presence of –SO3H groups in SO3H-UGNF permits better dispersion of filler and boosts physiochemical, thermomechanical, and electrochemical properties of Nafion/SO 3H-UGNF membrane compared to bare Nafion, Nafion/GNF, and Nafion/UGNF membranes. A range of concentrations of SO3H-UGNF (0.5, 1, or 1.5 wt%) are added to Nafion matrix to establish an optimal content for enhancing proton conductivity at 100, 50, and 18% relative humidity (RH). The optimized Nafion/SO3H-UGNF (1 wt%) membrane achieved a power output of 0.226 W cm-2 and durability of over 129 h at 120 °C with 18% RH, which represents one of the best performances among reported Nafion-based membranes in HT-HAFCs. The hydrogen permeability, mechanical strength, and morphology of Nafion/SO3H-UGNF membrane were retained reasonably after durability test in HT-HAFC. This study provides valuable insights for design and optimization of potential Nafion composites for HT-HAFCs.

Original languageEnglish
Article number108828
Number of pages15
JournalComposites Part B: Engineering
Volume215
Early online date26 Mar 2021
DOIs
Publication statusPublished - 15 Jun 2021
Externally publishedYes

Funder

This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20184030202210). This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF-2020R1A2B5B01001458).

Keywords

  • SO3H-UGNF
  • Nafion
  • High temperature
  • Low humidity
  • Proton conductivity
  • Gas crossover

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