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SMAllinOneSmart Membrane for hydrogen energy conversion:

All fuel cell functionalities in One material

Context and project objectivesA breakthrough of Proton Exchange Membrane Fuel Cells (PEMFC) requires a radical performancesimprovement of the key fuel cell material components (catalysts and protonic membrane) as well ashighly innovative solutions to overcome the membrane assembly and integration limitations. ActualPEM fuel cells presents Membrane Electrode Assembly (MEA) architecture corresponding to a protonconductive membrane hot pressed between two catalytic electrodes. However, the MEA performanceis limited by the interface effect between catalytic layer and membrane.

To overcome this problem, the SmAllInOne project introduces a Smart All in One membraneconcept. In this approach, a catalytic network is directly implanted in the thin film protonic membrane.

This novel composite material is particularly well adapted for fuel cell technologies as there is noboundary between the membrane and the electrodes. Moreover, several functionalities will be addedto this material in order to confer it smart properties such as water and crossover management,tailored porosity and 3D conformability.

The scientific and technological objectives of the project are: To synthesize bifunctional polymerizable and volatile precursors (alkenyl & sulfonyl) to prevent thedestruction of the acidic functions during the thin film membrane realization To create a network of percolated platinum nano-particles inside both faces of the membrane toensure simultaneously a good catalytic efficiency and electronic conductivity To enhance electronic conductivity by a tailored doping of material with gold particles by the surface To study and propose a water and crossover management solution by adding functional hydrophilicparticles to keep the membrane wet and Pt particles to getter hydrogen linkage To avoid the fuel depletion by controlling the porosity using a porogen approach. The consortiumconsists of seven partners from five European countries including two SMEs.

Work performedDuring this first year, the work was mainly focused on the synthesis of the basic materials for therealization of the Allinone membrane. Volatile precursors suitable for the deposition of protonconductive membranes with vacuum techniques were synthesized (mainly persylilated precursorsand perfluorinated esters precursors. The potential of these precursors as well as of somecommercial precursors was evaluated via various deposition techniques: PECVD, ICVD, ASPD. Inorder to synthesize catalytic layers with a growth process compatible with the deposition process of

the proton conductive membrane various techniques were screened (MOCVD, Co-depositionPECVD-PVD). In addition, a characterization procedure was set up in order to optimize the materialsevaluation and various low cost flexible substrates were screened.

Results achieved, intentions for use and impactRegarding the precursors, an interesting precursor was elaborated by UNIBA (See figure). Thevolatility was checked and it was successfully deposited by means of PECVD. Actually, the processparameters needs to be adjusted in order to enhanced the proportion of SO 3CH3 functions in the asdeposited layers. Regarding the persylilated precursors, various precursors were tested but theypresent either a low volatility or deterioration during injection.

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SO3CH3

F

F

FPrecursor synthesised by UNIBA, withphysical properties suitable forvacuum deposition

For the deposition of a proton conductive membrane, iCVD gave some preliminary results sinceproton conductive membranes were deposited from the polymerization of methacrylic acid and1H,1H,2H-Perfluoro-1-decene. For the moment, the conductivity are quite low (1-2mS/cm), but thetechnique seems promising since the chemical structure of the precursors is well preserved. WithPECVD, proton conductive carboxylic membranes were deposited. Conductivity between 10 and200mS/cm are measured by impedance spectroscopy. In parallel, PECVD sulfonic membranes werealso obtained, from the plasma polymerization of C4F8 and the Perfluoro-2-(2-fluorosulfonylethoxy)propyl vinyl ether. Low plasma powers are required to preserve the sulfonyl group from beingdestructed and consequently, low growth rates are found (around 20nm/min). A hydrolysis procedure

was found in order to transform the sulfonyl fluoride group in a sulfonic acid group. Considering thesynthesis of catalytic membranes, two approaches have been adopted. The co deposition of Pt/CF xfilms was tested: the plasma polymerization of a fluorinated gas occurs concomitantly with thesputtering of a Platinum target. The as deposited layers showed specific surfaces from 17 m2/g to 26m2/g and for the moment, for Pt content around 0.2-0.5mg/cm2. Simultaneously, MOCVD depositionof Pt cluster was examined. This process seems well compatible with the deposition by PECVD oriCVD since the working pressures are of the same order (0.1-1mBar). Depending from the substrateand it surface state, layers with Pt contents between 0.06 and 0.9 mg/cm2 and specific surfaces ashigh as 85m2/g were reached.

Expected end results, intentions for use and impactFuture energy systems such as hydrogen and fuel cells are needed to face the increasing worldwide

demand for energy (estimated to rise by more than 50% by the year 20301

) shadowed by theincreasing oil prices, as well as to permit the achievement of recently updated energy and climatechange strategic policy objectives2.

Expected result of the SMAllinone project is a reduction of the material and the fabrication costs.Material costs reduction: the membrane material is a major contributor to the PEMFC cost (Nafion212 (50m):~160 /30cmx30cm)3. In addition, we target a reduction of the Platinum concentration:Concentration of expensive platinum (~47/g)4 catalyst needs to be decreased without performanceslosses: the classical wet chemical approach (enduction) leads to Pt particles fairly evenly distributedthrough out the catalyst layer, the particles being active only when in contact with the provided gassupply and the proton conductive membrane (three phase contact). In the Allinone membrane, the Ptparticulates will be localized near the active surface.

The MEA is nowadays fabricated by blending the proton exchange membrane with the electrodesbetween two current collectors i.e. bipolar plates for the gas supply and electrons collection, in a hotpress procedure. This technique, involving many unit operations and low thickness control, does notaddress low cost mass production requirements. Integration of MEA needs to be carried out by a waythat is compatible with large scale production like roll to roll. In addition, the monolithic integration offuel cell directly connected in series may allow a reduction in the assembly time and costs.

Developing 3D compatible techniques, we expect also an increase in power density: The steadyincrease in power needs for current active systems is nowadays fulfilled by continually increasing the

1 http://portland.indymedia.org/en/2006/08/343668.shtml2 European Council : An Energy Policy for Europe- SET Plan 2007 COM(2007)13 http://www.quintech.de/englisch/pdf/catalog/fuel-cells-components-applications.pdf4 http://ec.europa.eu/enterprise/automotive/directives/proposals.htm

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fuel cell size and so its cost. By increasing power density, thanks to 3D architecture of the core fuelcell, once can produce smaller and cheaper components.

Consortium

CoordinatorDr. Jessica THERY, jessica.thery@cea.fr, www.smallinone.euCommissariat l'Energie Atomique France

Partners Universita degli Studi di Bari Italy

Surface Innovations Ltd United Kingdom

Bar-Ilan University Israel Federal Mogul Systems Protection France

IRD Fuel Cells A/S Denmark ALMA Consulting Group SAS France

The research leading to these results has received funding from the European UnionSeventh Framework Programme (FP7/2007-2013) under grant agreement nNMP3-SL-2009-227177 SMAllinOne.