Ion track grafting: A way of producing low-cost and highly proton conductive membranes for fuel cell applications

Abstract

International audienceKeywords: Ion track grafting Radiografting Swift heavy ions Proton conductivity Polymer electrolyte membrane Proton exchange membrane fuel cell a b s t r a c t Proton conductive individual channels through a poly(vinyl di-fluoride) PVDF matrix have been designed using the ion track grafting technique. The styrene molecules were radiografted and further sulfonated leading to sulfonated polystyrene (PSSA) domains within PVDF. The grafting process all along the cylindrical ion tracks creates after functionalisation privileged paths perpendicular to the membrane plane for proton conduction from the anode to the cathode when used in fuel cells. Such ion track grafted PVDF-g-PSSA membranes have low gas permeation properties against H 2 and O 2. A degree of grafting (Y w) of 140% was chosen to ensure a perfect coverage of PSSA onto PVDF-g-PSSA surface minimizing interfacial ohmic losses with the active layers of the Membrane Electrolyte Assembly (MEA). A three-day fuel cell test has been performed feeding the cell with pure H 2 and O 2 , at the anode and cathode side respectively. Temperature has been progressively increased from 50 to 80 • C. Polarisation curves and Elec-trochemical Impedance Spectroscopy (EIS) at different current densities were used to evaluate the MEA performance. From these last measurements, it has been possible to determine the resistance of the MEA during the fuel cell tests and, thus the membrane conductivity. The proton conductivities of such membranes estimated during fuel cell tests range from 50 mS cm −1 to 80 mS cm −1 depending on the operating conditions. These values are close to that of perfluorosulfonated membrane such as Nafion ® in similar conditions

Radiation-grafted materials for energy conversion and energy storage applications

“…Another proton conducting membrane was also prepared by ion-track grafting of PVDF films [90]. The 9 µm thick PVDF films were irradiated in He atmosphere with 78 Kr 31+…”

Differences in fundamental reaction mechanisms between high and low-LET in recent advancements and applications of ionizing radiation

“…Application of ion track grafting was found in Polymer Electrolyte Membranes (PEMs) for fuel cells, where the production of proton conductive channels through a fluoropolymer significantly enhances the proton conductivity and diminishes the water uptake of the membrane during tests of the fuel cells. 28 The latent tracks can be etched, and pores of different geometries can be obtained in a polymer depending on the ratio between the track etch rate and the bulk etch rate. For instance, cylindrical or biconical geometries may be produced.…”

Fabrication and Properties of Hybrid Membranes Based on Poly (Vinyl Alcohol), Sulfosuccinic Acid and Salts of Heteropolyacid with or without Silica for Fuel Cells Applications

“…The perfluorosulfonated membrane, Nafion produced by Dupont is the most used as a polymer in PEMFCs because of its combined chemical, electrochemical, and mechanical stabilities with high proton conductivity (~0.1 S.cm -1 ) at ambient temperature [5]. However, it possesses some drawbacks, and especially its high cost; presents a high water swelling characteristic which reduces the lifespan of the membrane and decrease in conductivity at elevated temperature [6]. So, the utilization of Nafion membrane in fuel cell is limited.…”