Physically stable proton exchange membrane with ordered electrolyte for elevated temperature PEM fuel cell

Dimensional change and humidity-induced stress of the proton exchange membrane were demonstrated to be main reasons for membrane physical failure during the long-term fuel cell operation. In this work, UV laser ablation was proposed to prepare physically stable polyimide supports to reduce the dimensional swelling and humidity-induced stress of the proton exchange membrane under variable humidities. Long-range ordered straight holes with definable open pattern and diameter of 50–200 μm were formed through the polyimide support. Composite proton exchange membrane prepared from the straight-hole polyimide support presented desirable performance and high durability in fuel cells. When Nafion fraction in the composite membrane increased to 48.67%, the proton conductivities of the composite membranes were equal to or greater than that of the conventional Nafion membrane with activation energies lower than that of the Nafion 211 membrane. The dimensions of the composite membranes are very stable in both low and elevated temperature conditions. The proportion of humidity-induced stress to the yield strength for the composite membrane is 0.20%–0.21%, much lower than that of the conventional Nafion membrane (24.77%). As a result, the composite proton exchange membrane prepared from the straight-hole polyimide presented high durability in the fuel cell operation. In the open circuit voltage accelerated test under in situ accelerating RH cyclic test, the irreversible OCV reduction rate of the composite membranes was 2.41–2.72 × 10−5 V/cycle, 37.1%–41.8% lower than that of the conventional Nafion 211 membrane.