High‐Temperature Proton‐Exchange‐Membrane Fuel Cells Using an Ether‐Containing Polybenzimidazole Membrane as Electrolyte

Abstract Herein, poly[2,2′‐(p‐oxydiphenylene)‐5,5′‐benzimidazole] (PBI) is synthesized from 3,3′‐diaminobenzidine and 4,4′‐oxybisbenzoic acid, and the membrane is prepared by solvent casting. The main characteristics of PBI are studied. In the preparation of the PBI/H 3 PO 4 composite membrane, the absorbing temperature of H 3 PO 4 is 120 °C, which leads to a membrane with a high content of H 3 PO 4 . Membrane electrode assemblies (MEAs) are fabricated from PBI/H 3 PO 4 membranes with the catalyst layer made of Pt/C, PBI, and polyvinylidene fluoride (230:12:7 w/w). The fabricated MEA is tested at 150 °C with dry hydrogen and oxygen gas at 0.2 M Pa for both anode and cathode feeds. No degradation of voltage is seen during stability testing of the PBI/H 3 PO 4 membrane at a constant current for 100 h. The maximum power density is 1.17 W cm −2 , and the maximum current density is 6.0 A cm −2 with a Pt loading of 0.5 mg cm −2 . The high performance of these membrane materials demonstrates that PBI can be regarded as an alternative membrane material for high‐temperature proton‐exchange‐membrane fuel cells.