Preparation and characterization of SPEEK/SPVDF-co-HFP/LaCrO3 nanocomposite blend membranes for direct methanol fuel cells

Abstract

In this study, nanocomposite blend membrane comprised of the sulfonated poly (ether ether ketone) (SPEEK), sulfonated poly (vinilidinfluoride-co-hexaflourpropylen) (SPVDF-co-HFP) and lanthanum chromite (LaCrO3) was successfully prepared by the solvent casting method. The prepared membranes exhibit a variety of advantages, such as desirable proton conductivity, good thermal and mechanical stability, outstanding water and methanol retention and oxidative stability. The increase in proton conductivity from 32.7 mS cm−1 in SPEEK/SPVDF-co-HFP blend membrane to 75.3 mS cm−1 in nanocomposite membrane is achieved at the nanoparticle content of 1.5 wt% at 20 °C, stemming from enhanced connectivity of the ionic groups which facilitates the proton transportation through the membrane. Also, the methanol permeability of the nanocomposite membranes was altered from 2.11 × 10−7 to 1.90 × 10−7 cm2 s−1, by addition of 1.5 wt% LaCrO3 nanoparticles, which show this membrane can act as effective barrier against methanol permeation. Moreover, the maximum power density of blend membrane was increased from 43.0 to 61.5 mW cm−2 with addition of 1.5 wt% nanoparticles and this results show that the nanocomposite membranes could be applied as a promising candidate as a proton exchange membrane for direct methanol fuel cells (DMFCs).