Sulfonated poly(phthalazinone ether ketone) for proton exchange membranes in direct methanol fuel cells

Sulfonated poly(phthalazinone ether ketone) (SPPEK) membranes were cast from N,N-dimethylacetamide (DMAc) solution and tested for their application as proton exchange membranes (PEMs) in direct methanol fuel cells (DMFCs). The methanol and water swelling uptake and several permeation tests indicated that SPPEK had a lower affinity to methanol than Nation and was less permeable than Nation. In a single cell DMFC test at 70 degrees C with the membrane electrode assembly (MEA) made of SPPEK, the maximum power density was 55 mW/cm(2) as the current density was 276 mA/cm(2) and the ultimate (limiting) current density was 360 mA/cm2. The lower permeability of SPPEK compared with Nation resulted in lower methanol crossover. Consequently, the optimal concentration of aqueous feed methanol Q M) for the SPPEK MEA was higher than that of Nafion (2 M) under the same operation conditions. (c) 2005 Elsevier B.V. All rights reserved.