Poly(ether ether ketone) (PEEK)-based graft-type polymer electrolyte membranes having high crystallinity for high conducting and mechanical properties under various humidified conditions

Takashi Hamada, Shin Hasegawa, Hideyuki Fukasawa, Shin Ichi Sawada, Hiroshi Koshikawa, Atsumi Miyashita, Yasunari Maekawa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Poly(ether ether ketone)-based graft-type polymer electrolyte membranes (PEEK-PEMs) with wide ion exchange capacity (IEC) ranges were prepared by radiation-induced graft polymerization for investigating the relative humidity (RH) dependence of their electrochemical and mechanical properties at 80 °C for fuel cell applications. The proton conductivity ranges of 1.73-3.08 mmol g-1 IECs at 30% and 95% RH were 0.001-0.009 and 0.108-0.431 S cm-1, respectively. Unlike aromatic hydrocarbon-type PEMs, PEEK-PEMs' conductivity exhibited less dependence on RH. PEEK-PEMs with IECs > 3.08 mmol g-1 exhibited a similar conductivity (0.009 S cm-1) under 30% RH and showed 1.4 times higher tensile strength (14 MPa) under 100% RH at 80 °C in comparison to Nafion 212. The MEA fabricated by the PEEK-PEM with IEC = 2.45 mmol g-1 showed the maximum power densities (Emax) of 860 and 826 mW cm-2 at 2140 and 2180 mA cm-2 under 100% and 30% RH, respectively. In particular, PEEK-PEM showed low RH dependence for Emax, which was 2.5 times higher than that of Nafion 212 at 30% RH. The X-ray scattering analyses revealed that the crystallinity of approximately 28-32% was maintained and propagated during the graft polymerization of graft-type PEEK-PEMs. The abovementioned unique structures were the origins of higher conductivity and tensile strengths compared with conventional PEMs.

Original languageEnglish
Pages (from-to)20983-20991
Number of pages9
JournalJournal of Materials Chemistry A
Volume3
Issue number42
DOIs
Publication statusPublished - 2015
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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