Quantum beam techniques for synthesis and analysis of proton-exchange membranes for fuel cells

量子ビーム技術による燃料電池用プロトン伝導高分子電解質膜の合成と構造・機能解析

前川 康成

Maekawa, Yasunari

Radiation-induced grafting technique was applied to the development of polymer electrolyte membranes (PEMs) for hydrogen-fuel cells. Mechanically and thermally stable poly(ethylene-co-tetrafluoroethylene) (ETFE) films could be converted to graft-type PEMs (ETFE-PEMs). Compared with Nafion, the PEMs showed superior conductivity and tensile strength under low (30%) and high (100%) relative humidity conditions, respectively. Using SAXS and USAXS, the ETFE-PEMs with IECs 2.7 mmol/g were characterized as being composed of graft polymer domains around lamellar crystals with a period of 20-30 nm and well-connected crystallite network domains with a d-range of 200-300 nm. From the above analysis, it is revealed that well interconnected ion-channels around the crystallites and the remaining lamellar crystals and crystallites in the graft-type PEMs were the origins of higher conductivity and tensile strengths, respectively, compared with conventional PEMs.