Sulfonated Poly(arylene perfluoroalkylene) Terpolymers as Novel Proton Exchange Membranes for High Performance Fuel Cells

We herein report a series of sulfonated poly(arylene perfluoroalkylene) terpolymers (SPAF-P) containing sulfophenylene, perfluoroalkylene, and meta- or Para-phenylene groups in the main chain. The SPAF-P terpolymers with reasonable molecular weight and various ion exchange capacity (IEC = 1.85-3.18 meq g(-1)) provided transparent and flexible membranes. Compared with our previous membrane sharing the same perfluoroalkylene groups (SPAF-MM, IEC = 1.59 meq g(-1)), SPAF-P achieved higher proton conductivity over a wide range of humidity because of their higher IEC values. A fuel cell with SPAF-pP 1.85 membrane exhibited slightly higher performance than that of SPAF-MM at 30% RH with H-2/air because of the improved proton conductivity. After the open-circuit voltage (OCV) hold test for 1000 h, the SPAF-pP fuel cell retained high OCV value (>0.94 V), similar polarization curves, ohmic resistance curves, molecular weight and chemical structure, indicating the excellent chemical stability of the SPAF-pP 1.85 membrane.