Influence of Innovative Materials Incorporation in MEA during Its Conception on the Electrochemical and PEMFC Performances

Abstract

Hydrogen seems to be the most promising energetic vector in order to diversify the sources of energy production. To use this fuel, the Proton-Exchange Membrane Fuel Cell (PEMFC) appears to be one of the most viable and cost effective solution. The materials commonly used in this technology of energy conversion are well known, thus the solid electrolyte is a perfluorinated membrane composed of sulfonic acid groups (-SO3H) in order to permit proton migration through the membrane from one electrode side to the other and the electrodes are composed of platinum-based nanoparticles (NPs) dispersed on a high surface electron conductive substrates. Gas diffusion layer (GDL) is used to support electrode materials and allows the diffusion of the active gas species until the electroactive sites as well as the outlet flux of the generated species. Moreover, to improve the mechanical contacts and the proton migrations between the different elements of the PEMFC, a proton conducting ionomer is added. All these components are assembled in order to obtain Membrane Electrodes Assemblies (MEAs). Strong improvements of PEMFC performances and durability have been achieved with the emergence of new electrode and membrane materials, however due to the characteristics of these innovative components, MEAs conception have still to be improve or adapt in order to deliver the highest performances. In this context, the CEA develops innovative materials for PEMFC application. Thus, low cost membranes based on a hybrid nanocomposite material have been developed. This concept consists on the association of PVDF matrix and hybrid filler composed by silica nanoparticles grafted by sulfonic1 or phosphonic2 acid polymer. The matrix provides electrical insulation, chemical stability and mechanical strength, whereas the proton conductivity properties and the hydration of the membrane are associated to the acid functions. Similar composite material is also developed in order to be used as proton conducting ionomer in the MEA. Other works focus on the elaboration of novel cathodic electrocatalysts by grafting of ionic conducting polymer to the surface of platinum nanoparticles3. The architecture brought by the polymer conducts to an improvement of the proton conduction in the catalyst layer. The work here presented consisted in characterizing the influence of each innovative component of the MEA on the PEMFC performances. The final aim is to elaborate a MEA without Nafion® which is the actual reference as membrane and ionomer. In function of the material properties, MEA conception will be adapted from the most described techniques which are the catalyst-coated membranes (CCM), catalyst-coated backing (CCB) or “Decal method” which is a transfer of the catalytic layer on the membrane by hot pressing. Established MEA will permit to determine the performances brought by the innovative materials under PEMFC conditions as well as the benefit effects of the conception and the impact of the interfaces membrane/electrodes through cyclic voltammetry, electrochemical impedance spectroscopy and polarization measurements. Keywords: Electrochemical characterization, Fuel cell test, Membrane, Catalyst, Ionomer Acknowledgement: The research leading to these results has received funding from the ADEME (French Environment and Energy Management Agency) for its financial support through the MHYEL project. Niepceron F. et al., J. Memb. Science, 338, (2009), 100-110.Souquet-Grumey J. et al., J. Memb. Science, 466, (2014), 200-210.Dru D. et al., ACS Catal., 6, (2016), 6993-7001