Porous PTFE reinforced SPEEK proton exchange membranes for enhanced mechanical, dimensional, and electrochemical stability

The pores of polytetrafluoroethylene (PTFE) film were filled with the sulfonated poly (ether ketone) (SPEEK) electrolyte molecules to prepare the proton exchange membrane with the enhanced mechanical, dimensional and electrochemical stability for fuel cell application. Catechol/polyethyleneimine was co-deposited on the PTFE pore surface as an adhesive mediator for the feasible impregnation of SPEEK. The chemical composition, morphology, and wettability of the porous PTFE film were investigated by electron spectroscopy for chemical analysis, scanning electron microscope, mercury porosimetry, and water contact angle measurements. After pore filling with SPEEK electrolytes, several essential properties of membranes (e.g. water uptake, proton conductivity, mechanical property) and wet/dry cyclic cell performance were examined. The prepared pore-filled electrolyte membranes showed the superior mechanical and dimensional stability at the reduced water uptake to the pristine SPEEK membrane. Those excellent properties of the electrolyte membranes are reflected in the stable electrochemical cell performance over the repeated wet/dry cycles with suppression of crack/void formation and edge breakdown.