Anhydrous elevated-temperature polymer electrolyte membranes based on ionic liquids

Composite membranes based on sulfonated poly(ether ether ketone) and imidazolium type ionic liquids were prepared and characterized as potential electrolytes for elevated-temperature anhydrous polymer electrolyte membrane fuel cell applications. Atomic force microscopy and electrostatic force microscopy revealed that the hydrophilic ionic domains were formed in the membrane and the ionic domains were connected by small ionic channels that facilitate proton transporting process. The formed composite membranes were thermally stable up to 340 °C. With the increase in temperature, the maximum ionic conductivity of the formed membrane reached 8.3 × 10−3 S cm−1 at 170 °C and under anhydrous conditions.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (135 K)Download as PowerPoint slideResearch highlights▶ Ionic cluster formation in the formed SPEEK/ionic liquids composite membrane. ▶ Ionic conductivity depends on the type of ionic liquids applied. ▶ The incorporated ionic liquids improve thermal stability of the composite membrane. ▶ Leaching of the ionic liquids from membrane depends on the hydrophobicity of ionic liquids.