Modified Nafion polymer electrolyte membranes by γ-ray irradiation used in direct methanol fuel cells

Modification of the commercial polymer electrolyte membrane (PEM) Nafion 117 by γ-ray irradiation to produce an improved proton exchange membrane for direct methanol fuel cells (DMFCs) was described. The Nafion 117 membrane was exposed under γ-ray irradiation circumstance with the irradiation doses from 103 to 105 Gy. Subsequently the properties of the membrane itself, in terms of swelling ratio, water uptake rate, proton conductivity and methanol permeability, together with the performance of its membrane electrode assembly (MEA) in DMFC were analyzed and contrasted with the untreated material. When the Nafion 117 membrane was exposed under γ-ray irradiation circumstance, the degradation and crosslinking reactions occurred at the same time. Specific scopes of the γ-ray irradiation dose may cause the membrane crosslinking, thus reduce the membrane swelling ratio and decrease the methanol crossover. By reducing the membrane swelling ratio and methanol permeation, the single DMFC with the modified Nafion 117 membrane produced reasonable power density performance as high as 32W/m2 under 2mol/L methanol solution at room temperature.