Covalent-ionically cross-linked polyetheretherketone proton exchange membrane for direct methanol fuel cell

Abstract

In this paper, the proton exchange membrane prepared by covalent-ionically crosslinking water soluble sulfonated-sulfinated poly(oxa-p-phenylene-3,3-phthalido-pphenylene- oxa-p-phenylene-oxy-phenylene) (SsPEEK-WC) is reported. Compared with covalent cross-linked PEEK-WC membrane, this covalent-ionically cross-linked PEEK-WC membrane exhibits extremely reduced water uptake and methanol permeability, but just slightly sacrificed proton conductivity. The proton conductivity of the covalent-ionically cross-linked PEEK-WC membrane reaches to 2.1×10- 2 S cm-1 at room temperature and 4.1×10-2 S cm-1 at 80 °C. The methanol permeability is 1.3×10-7 cm2 s-1, ten times lower than that of Nafion 117 membrane. The results suggest that the covalent-ionically cross-linked PEEK-WC membrane is a promising candidate for direct methanol fuel cell because of low methanol permeability and adequate proton conductivity.