Hybrid SPEEK/Phosphonatedsilsesquioxanes membranes for PEMFC

Abstract

In this work, the production and characterization of hybrid membranes of sulfonated poly(ether-ether-ketone; SPEEK) and phosphonated copolysilsesquioxanes (PCs) and its application in proton exchange membrane fuel cell (PEMFC) were studied. To improve the proton conduction and thermal stability of the polymer SPEEK, PCs were synthesized from diethylphosphatoethyltriethoxysilane (Ph-TEOS) and phenyltriethoxysilane (PTES), 90/10 mol/mol, by a hydrolysis/condensation procedure. The PCs were characterized by infrared thermal analysis. Hybrids membranes produced from SPEEK and 20 wt% PC were submitted to further hydrolysis to give semiinterpenetrating copolysilsesquioxanes networks. The hybrid membranes were also characterized according to their thermal behavior, proton conductivity, electrochemical performance in fuel cell, and oxidative stability. The proton conductivities (σ) of the membranes in the hydrated state at room temperature were determined by electrochemical impedance spectroscopy. It was verified that the proton conductivities of the hydrolyzed hybrid membranes were about 370% higher than the σ of plain SPEEK. The hydrolyzed membranes with 20% (90:10) PC showed the best performance in a PEMFC working with H2/O2 at 60°C.