Modified SPEEK membranes for direct ethanol fuel cell

Membranes with low ethanol crossover were prepared aiming their application for direct ethanol fuel cell (DEFC). They were based on (1) sulfonated poly(ether ether ketone) (SPEEK) coated with carbon molecular sieves (CMS) and (2) on SPEEK/PI homogeneous blends. The membranes were characterized concerning their water and ethanol solution uptake, water and ethanol permeability in pervaporation experiments and their performance in DEFC tests. The ethanol permeabilities for the CMS-coated (180 nm and 400 nm thick layers) SPEEK were 8.5 and 3.1 × 10−10 kg m s−1 m−2 and for the homogeneous SPEEK/PI blends membranes with 10, 20 and 30 wt.% of PI were 4.4, 1.0 and 0.4 × 10−10 kg m s−1 m−2 respectively, which is 2- to 50-fold lower than that for plain SPEEK (19 × 10−10 kg m s−1 m−2). Particularly the SPEEK/PI membranes had substantially better performance than Nafion 117® membranes in DEFC tests at 60 °C and 90 °C.