Abstract: Proton exchange membrane is one of the key parts of direct methanol fuel cell (DMFC). Sulfonated poly(phthalazinones) membranes were prepared and the feasibility of applying these membranes in DMFC was studied. The thermal degradation temperature of sulfonated poly(phthalazinone ether sulfone keton) (SPPESK) membrane was about 100 ℃ lower than that of sulfonated poly(phthalazinone ether keton) (SPPEK) and sulfonated poly(phthalazinone ether sulfone) (SPPES) membranes with similar ion-exchange capacity (IEC). These new membranes showed high proton conductivity and their methanol permeability was lower than that of Nafion membrane. DMFC performance of these new membranes was also investigated. The DMFCs with sulfonated poly(phthalazinones) membranes showed higher open circuit voltage than that using Nafion membrane as electrolyte. However, the DMFC performance of these new membranes was lower than that of Nafion membrane at high current density.

Key words: Poly(phthalazinones), Direct methanol fuel cell (DMFC), Proton exchange membrane (PEM), Proton conductivity, Methanol permeability