Fuel Cell Characteristics of the Membrane Electrode Assemblies using Phosphoric Acid-doped Poly[2,2’-(p-oxydiphenylene)-5,5’-bibenzimidazole] Membranes

Abstract

The membrane electrode assemblies (MEAs) based on phosphoric acid (PA)-doped poly[2,2’-(p-oxydiphenylene)-5,5’-bibenzimidazole] (OPBI) membranes were prepared for the high temperature polymer electrolyte membrane fuel cells, and the moderate molecular weight poly[2,2’-(m-phenylene)-5,5’-bibenzimidazole] (mPBI) with good solubility in aprotic solvents was synthesized and utilized as the binder in catalyst layers for the first time. The hot press and the components in catalyst layers that affected the performances of MEAs were studied. The cell performance evaluation and electrochemical impedance spectroscopy were carried out at temperatures ranging from 80 to 160 °C in a single cell setup. It was found that the prepared OPBI and the moderate molecular weight mPBI with high solubilities of polybenzimidazole could facilitate and simplify the preparation of MEAs. The novel MEAs using the PA-doped OPBI membranes and moderate molecular weight mPBI exhibited good performances in the polarization tests, constant current tests, and temperature cycle tests, which were comparable with those traditional MEAs using the PA-doped mPBI.