Phase separation and ion conductivity in the bulk and at the surface of anion exchange membranes with different ion exchange capacities at different humidities

Taro Kimura, Ryo Akiyama, Kenji Miyatake*, Junji Inukai

*この研究の対応する著者

研究成果: Article査読

13 被引用数 (Scopus)

抄録

For higher performances of anion exchange membrane (AEM) fuel cells, understanding the phase-separated structures inside AEMs is essential, as well as those at the catalyst layer/membrane interfaces. The AEMs based on quaternized aromatic semi-block copolymers with different ion exchange capacities (IECs) were systematically investigated. With IECs of 1.23 and 1.95 mequiv g−1, the water uptakes at room temperature were 37% and 98%, and the anion conductivities 23.6 and 71.4 mS cm−1, respectively. The increases were not proportional to the IEC. Images obtained by transmission electron microscopy in vacuum were similar with both IEC values, but the development of a clear phase separation in humidified nitrogen was observed in the profiles only with 1.95 mequiv g−1obtained by small-angle X-ray scattering. At the temperature of 40 °C and the relative humidity (RH) of 30%, the average currents observed at the tip apex by current-sensing atomic force microscopy were <0.5 and 10 pA with 1.23 and 1.95 mequiv g−1, respectively, and those at 70% RH were 10 and 15 pA, respectively. The humidity gave a larger influence on the bulk structure with 1.95 mequiv g−1, whereas a larger influence on the surface conductivity with 1.23 mequiv g−1.

本文言語English
ページ(範囲)397-403
ページ数7
ジャーナルJournal of Power Sources
375
DOI
出版ステータスPublished - 2018 1 31
外部発表はい

ASJC Scopus subject areas

  • 再生可能エネルギー、持続可能性、環境
  • エネルギー工学および電力技術
  • 物理化学および理論化学
  • 電子工学および電気工学

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