Fabrication of an ultra-thin and ordered SPEEK proton exchange membrane by a Langmuir-Blodgett self-assembly process

Abstract

In proton exchange membrane fuel cell (PEMFC), a sulfonated poly (ether ether ketone) (SPEEK) membrane plays a crucial role in transporting H+ through hydrophilic channels. However, when the proton exchange membrane (PEM) is prepared by solution casting, its randomly connected channels will lead to low proton conductivity in the hydrated state. Herein, The Langmuir-Blodgett (LB) self-assembly process was used to create the ordered and controllable SPEEK membrane at the molecular level. Π-A isotherms are used to determine the subphase, spread amount, and slip speed of LB membranes, and the force of –SO3- and H+ (pH = 2) is calculated to be 39.31 kJ/mol. Well-ordered channels dramatically suppress the membrane water uptake and swelling rate, FPS#1 enhancing three times in the proton conductivity (0.384 S/cm) compared to conventional SPEEK membranes. Highly ordered ultrathin SPEEK membranes with high proton conductivity could offer a practically applicable low-cost, yet high-performance membrane for PEMFC.