Study on PEFC Membrane Based on Crosslinked FEP Using EB‐Grafting

Abstract

Polymer electrolyte fuel cell (PEFC) membranes based on crosslinked tetrafluoroethylene-co-hexafluoropropylene (FEP) have been fabricated by preirradiation grafting method. The chemical structures of crosslinked materials have been analyzed by Differential Scanning Calorimeter (DSC) and 19 F solid-state Nuclear Magnetic Resonance (NMR) spectroscopy. The radical yields of irradiated samples were measued by Electron Spin Resonance (ESR), and the mechanism of grafting reaction has been discussed. The styrene grafted materials were sulfonated by chlorosulfonic acid. The ion exchange capacity of the obtained sulfonated crosslinked FEP (S-FEP-X) showed 2.0 to 2.4 meq/g, which were 2.2 to 2.7 times higher than that of Nafion 1 112. Glass transition temperatures (T g ) of S-FEP-X were almost independent on crosslinking dose of FEP, and show about 96 8C, which are slightly higher than that of Nafion 1 . The electrochemical properties of the membranes have been measured, and cell performances of them have been evaluated. Ionic conductivities (ICs) of S-FEP-X are 1.2 to 1.6 times higher than that of Nafion 1 . The higher network densities gave the higher open circuit voltage (OCV). The power density of S-FEP-600kGy was about 10% higher than that of Nafion 1 at 500mA/cm 2 . Thus, the obtained sulfonated membranes can be expected to apply for high efficiency PEFC.

Development of sulfonated FEP–Nafion hybrid proton exchange membranes for PEFC

“…Perfluorosulfonate membranes such as Nafion Ò (DuPont Co., Ltd.) are often used for PEMs owing to their chemical stability, however, they are still expensive [1]. Therefore, the partial-fluorinated sulfonic acid membranes have been fabricated by a radiation grafting method to obtain low cost PEMs [2][3][4][5][6]9]. Although ion exchange capacities (IEC) of obtained PEMs were 1.3-2.2 times higher than that of Nafion Ò 112, their cell performance were same or lower than Nafion Ò 112 [2,5].…”

Study on Functionally Gradient Proton Exchange Membrane fabricated by EB Irradiation with Heterogeneous Energy Deposition

“…The bottom layer was FEP sample (thickness: 300 µm, ρ: 2.15 g/cm 3 ). The simulation model of EB-ENGINE Ⓡ was composed by 3 layers.…”

“…Although the window material of EB-ENGINE Ⓡ is Beryllium, the information of thickness has not been disclosed. In this simulation, the thickness of top layer was 10.0 µm, ρ: 1.85 g/cm 3 . The middle layer was nitrogen atmosphere (thickness: 1.0 cm, ρ: 1.25 × 10 -3 g/cm 3 ).…”

“…In this simulation, the thickness of top layer was 10.0 µm, ρ: 1.85 g/cm 3 . The middle layer was nitrogen atmosphere (thickness: 1.0 cm, ρ: 1.25 × 10 -3 g/cm 3 ). The bottom layer was FEP sample (thickness: 300 µm, ρ: 2.15 g/cm 3 ).…”

“…The middle layer was nitrogen atmosphere (thickness: 1.0 cm, ρ: 1.25 × 10 -3 g/cm 3 ). The bottom layer was FEP sample (thickness: 300 µm, ρ: 2.15 g/cm 3 ). On the other hand, the ultra low energy EB (less than 110 keV) deposited much itself energy at near-surface regions.…”