Fuel Cells : Materials and Technology Challenges
Session FA-1 - Solid Oxide (SOFCs) and Molten Carbonate (MCFCs) Fuel Cells
FA-1:IL01 New Generation Solid Oxide Fuel Cells
N. CHRISTIANSEN, Topsoe Fuel Cell A/S, Lyngby, Denmark
Major advances have been achieved over the last decade in SOFC R&D and technology. Attention to reliability and robustness of SOFC cells and stacks is increasing as the technology moves from laboratory and pilot scale to demonstration at real operation conditions. While conventional SOFCs operate at temperatures from 750 °C to as high as 950 °C, an increased focus on performance degradation and material cost has directed the development towards lower operation temperatures. The new generation of metal supported cells are expected to offer several potential advantages such as: Higher tolerance toward internal temperature gradients and temperature shock and improvements in cell material cost. Recently novel PVD thin film coating technologies have been introduced for manufacturing of thin dense cell layers and for continuous production of Co and Co/Ce thin film protective layers on metal interconnect strip steel. Infiltration techniques is used to obtain nanostructured highly active electrodes, to avoid undesirable decomposition of cathode materials, and to inhibit Ni coarsening, and interdiffusion between Ni catalyst and FeCr in the metal support. The metal supported cells and stacks developed in the EU project consortium METSAPP are intended for operation at lower temperatures in the range 600 - 700 ºC. The design is based on a multilayered structure consisting of optimal thin cell and stack components and represents a next generation SOFC concept regarding processing as well as materials.
FA-1:IL02 High Temperature Fuel Cell Electrodes: New Compositions, Microstructures and Systems for Efficient Utilisation of Renewable Fuels
J.T.S. IRVINE, University of St. Andrews, St. Andrews, UK
Fuel cells will undoubtedly find widespread use in this new millennium in the conversion of chemical to electrical energy, as they offer very high efficiencies and have unique scalability in electricity generation applications. The solid oxide fuel cell (SOFC) offers certain advantages over lower temperature fuel cells, notably its ability to utilise CO as a fuel rather than being poisoned and the availability of high-grade exhaust heat for combined heat and power or combined cycle gas turbine applications. Although cost is clearly a key barrier to widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or anode. In terms of mitigating global warming, the ability of the SOFC to utilise commonly available fuels at high efficiency, promises an effective and early reduction in carbon dioxide emissions and hence is one of the lead new technologies to improve the environment. In the longer term the ability to utilise waste derived fuels such as biogas will be of critical importance.
Here we describe a series of strategies involving modification of defect chemistry and composition to enhance the electrocatalytic performance of novel perovskite anode and cathode materials.
FA-1:IL03 Improvement of Durability of SOFC: Origin of Polarization at Cathode/Electrolyte Interfaces
T. HORITA, N. MINA, H. KISHIMOTO, K. YAMAJI, H. YOKOKAWA, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
One of the key issues of Solid Oxide Fuel Cells(SOFCs) is the degradation of cathode performance. During fabrication and operation, some elemental diffusion can occur at the La0.6Sr0.4Co0.2Fe0.8O3-d(LSCF)/Gd0.1Ce0.9O2-x (GDC)/Y0.15Zr0.85O2-y(YSZ) interfaces. Although the GDC layer is fabricated to protect the strontium (Sr) diffusion, small amounts of Sr can diffuse through the GDC layer from LSCF, and the SrZrO3 can be formed at the GDC/YSZ interfaces. The SrZrO3 formation can affect the oxide ionic diffusion at the interfaces, eventually affects the degradation and durability.
In this presentation, we report the effect of elemental diffusion on the durability and degradation at the La0.6Sr0.4Co0.2Fe0.8O3-d/Gd0.1Ce0.9O2-x (GDC)/Y0.15Zr0.85O2-y(YSZ) interfaces. We show the degradation phenomena at the practical flat tube SOFCs. Then we show our original method to visualize the oxide ionic diffusion at the interfaces. Stable isotope oxygen (18O2) has been applied to visualize the oxide ionic motions inside the ceramics. We applied this technique at the samples after long-term operation (more than 4000 hours operation), and found that the SrZrO3 formation made an obstacle for oxide ionic diffusion at the interfaces. We further report the diffusion mechanism of Sr at the LSCF/GDC.
FA-1:IL04 Reconstruction and Analysis of Solid Oxide Fuel Cell Electrodes with Nano-sized Structures
MENG NI, Department of Building and Real Estate, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
The microstructure of solid oxide fuel cell electrodes are reconstructed numerically by dropping spherical particles into computational domain. Kinetic Monte Carlo (KMC) simulations are performed to investigate the microstructure evolution in the sintering stage for SOFC fabrication. The important parameters, such as the triple-phase boundary (TPB) length, the tortuosity factor and the porosity are computed at different sintering temperature and sintering times. An optimal sintering time is found which can yield the highest TPB length.
Subsequently, the reconstruction techniques have been extended to reconstruct the nano-structured SOFC electrodes by a 3-step method: (1) the backbone is generated by random packing of spherical particles within a domain which is discretized in to pixels with a 5-nm resolution; (2) the nanosized particles are coated on the backbone surface randomly one-by-one; and (3) the infiltrated particles are enlarged to a designed size to simulate the sintering procedure. The TPB length, percolation behavior of the reconstructed SOFC electrodes are studied in detail. The study offers insights in properties of the SOFC electrode microstructures.
FA-1:IL05 Density Functional Theory Combined with Experiments to Study the Triple Phase Boundaries of Solid Oxide Fuel Cells
M. MALAGOLI1, M.L. LIU2, HYEON CHEOL PARKA3, A. BONGIORNO1, 1School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA; 2School of Material Science & Engineering, Georgia Institute of Technology, Atlanta, GA, USA; 3Advanced Materials Research Center Samsung Advanced Institute of Technology (SAIT), Yongin-si, Republic of Korea
In this work, we present a modeling study of triple phase boundary regions of solid oxide fuel cells (SOFCs) based on a density functional theory approach. In particular, we consider the following solid oxide electrolytes, yttrium-doped Y-doped BaZrO3 and yttrium-doped barium cerate (BCY), and the following metallic catalysts, palladium, nickel, and copper. Thus, we use density functional theory calculations to construct the energy landscape for a hydrogen species crossing triple phase boundaries based on the materials above. This study focuses, in particular, on the role played by the metal-oxide interface in controlling the proton transfer from the catalyst to the electrolyte component of triple phase boundaries. Our results are discussed in light of the hydrogen spilling process occurring at triple phase boundaries based on nickel and yttria-stabilized zirconia.
FA-1:L06 Effect of Annealing on Crystal Structure and Conductivity of Plasma-Sprayed Protective Oxide for SOFC Interconnects
KUAN-ZONG FUNG1, 2, SHU-YI TSAIA2, HSIN-CHIA HOAB, 1Research Center for Energy Technology and Strategy; 2Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan, ROC
Metallic interconnects have been used to replace ceramic interconnects because they are less expensive, more conductive and able to form complex shapes for intermediate temperature SOFC applications. Most metallic interconnects use chromium-containing alloy that form chromia scales at high temperatures. Since chromia may react with cathode and cause degradation, a protective oxide may be used to suppress the growth of chromia. In this study, conducting oxides were deposited on metallic interconnect using plasma spray technique. However, the deposition temperature for thermal spray coating may be high enough to change the crystal structure and conductivity of protective oxide. The post annealing at elevated temperature is found to be an appropriate method to obtain adequate properties for protective oxide. Thus, the objective of this work is to investigate the effect of annealing on the crystal structure and conductivity of the sprayed oxide. The crystal structure, mor phology and electrical conduction of interconnect with sprayed oxide films will be examined by using XRD, FESEM and resistance measurement.
FA-1:L07 Effect of Synthesis Methods on Catalytic and Structural Properties of SrTiO3 for applications in SOFC anodes
F. MARAZZI, A. PAPPACENA, M. BOARO, A. TROVARELLI, University of Udine, Udine, Italy
As component of SOFC anodes, SrTiO3 has demonstrated high electronic conductivity, carbon and sulphur poisoning resistance, and good structural stability, but poor catalytic activity. This study investigated the effect of different preparation methods on the structural and textural properties of SrTiO3 with the aim to develop materials with enhanced catalytic properties for further applications in SOFC electrodes.
SrTiO3 was prepared through two different co-precipitation (CP_01, CP_02) methods using oxalates as precipitant agent or with a Pechini modified approach (SG_P). All materials were extensively characterized with conventional techniques (XRD, BET) after calcination at different temperatures. The methane oxidation was choosen to compare the catalytic properties of Co impregnated oxides.
The method of synthesis affects textural and structural properties of SrTiO3: SG_P method allows obtaining a higher surface area; materials prepared via SG_P or via CP_02 show a pure cubic perovsikite phase, while the material pre-pared through the CP_01 synthesis presents also Ruddlesden_Popper phases. The best activity for methane oxidation was obtained with this latter oxide. This entails correlation between the structural caracteristics of the supports and their catalytic activity.
FA-1:L08 Self Repairable Glass Seals for Solid Oxide Fuel Cells
R.N. SINGH, School of Materials Science and Engineering, College of Eng., Architecture and Technology, Oklahoma State University, Tulsa, OK, USA
A novel concept of self-repairable glass useful as seals in Solid Oxide Fuel Cells (SOFC) is proposed, developed, and used for making metal-glass-ceramic seals for enhancing reliability and life. In this concept, cracks created during SOFC operation are repaired by the crack healing process driven by the viscous flow of the glass. An approach for studying the kinetics of crack-healing in glasses responsible for the self-repair is described and used to study the crack healing behavior. The cracks are created by a micro-indenter and the progression of healing of cracks thus created on a silicate glass surface is experimentally determined at different annealing temperatures and times. A crack healing model, based on the relationship among crack length, time, temperature, glass viscosity and its flow behavior is developed in order to describe and predict the time required for self repair on a glass surface. The developed model is then validated using the experimental data and approach.
FA-1:L09 Implications of Water-based Shaping Processing on the Properties of Gadolinium-doped Ceria
A. CALDARELLI, E. MERCADELLI, A. SANSON, CERTIMAC and ISTEC-CNR, Faenza, Italy; S. PRESTO, M. VIVIANI, IENI-CNR, Genova, Italy
Gadolinium doped ceria (GDC) has received a lot of attention as possible electrolyte material for Intermediate-Temperature (500-800°C) Solid Oxide Fuel Cells (IT-SOFC). The GDC electrolyte layer is commonly deposited on a supporting anode to obtain the so-called solid oxide half-cell. The ceramic deposition processes generally consider organic solvents and additives but water-based systems are preferred for low cost and health and safety reasons. In this work the effect of six different dispersants on the stability of Ce0,8Gd0,2O2 nanopowders water-based suspension was considered. The most effective dispersant was found to deeply affect not only the homogeneity of the dispersion but also the pH of the system. This pH change leads to a partial leaching of the Gd3+ from the powder surface improving the microstructure and the electrical properties of the electrolyte as a result of an higher grain boundary conductivity.
FA-1:IL10 High Temperature Fuel Cells: Materials Issues and New Concepts
M. CASSIR, Institut de Recherche de Chimie Paris, IRCP, UMR8247 Chimie ParisTech - CNRS, Paris, France
High-temperature fuel cells are strategic devices for co-generation, due to their efficiencies and flexibility, but there are still facing difficulties in view of their full commercialization, such as yields, durability and costs. The main issues are related to the selection of adapted materials in order to ensure chemical and mechanical stability, accelerated kinetics and degradation protection. After a rapid view on the state-of-the art materials in molten carbonate fuel cells, MCFC, and solid oxide fuel cells, SOFC, we will focus on the role of thin functional layers, which are becoming a key point for improving interface reactions. The role of micro- or nano-strutured thin films can be diverse: protective layers for MCFC (carbonate corrosion) and SOFC (diffusion or electronic barriers), bond layers between electrodes and interconnects and catalytic layers. Moreover for SOFCs, thin-layered electrolytes can be envisaged for micro fuel cells systems as well as active electrolyte or electrode layers to improve both charge and mass transport. Finally, we will introduce new concepts/materials related to high-temperature devices, such as Direct Carbon Fuel Cells, composite electrolyte oxide/carbonates combining MCFC/SOFC technologies and CO2 valorisation.
FA-1:L12 ETRERA_2020 - A project for an Euro-Mediterranean RES, Hydrogen and Fuel Cells Deployment
G. SQUADRITO1, A. NICITA1, A. SORACI2, P. MAZZUCCHELLI3, E. STAMATAKIS4, I. IBRIK5, R. SANDERS6, A. ZAKARYA7, M. MACHMOUM8, H. GORGUN9, B. DAG10, H. HAMDI11, D. MARTINEZ CALLEJA12, 1CNR - ITAE, Messina, Italy; 2INNOVA BIC, Messina, Italy (project coordinator); 3European Renewable Energy Centre Agency, Brussels, Belgium; 4Kemtro Ananeosimon Pigon Ke Exikonomisis Energeias - CRES, Pikermi/Athens, Grece; 5An-Najah National University, Omar Ibn Khatab Street Nablus Palestinian-Administered Areas; 6European Business and Innovation Network, Brussels, Belgium; 7Centre de Recherche et de Technologie de l'Energie, Technopole Borj Cedria, Tunis Hammam Lif, Tunisia; 8Université De Nantes, Saint Nazaire, France; 9Yildiz Technical University, Faculties of Electrical A 101, Esenler/Istabul, Turkey; 10Turkiye Bilimsel Ve Teknolojik Arastirma Kurumu TUBITAK, Odtu Kampus/Sogutozu, Ankara, Turkey; 11Université Cadi Ayyad, Bb Prince MY Abdellah, Marrakech, Morocco; 12Asociation Madrid Network, Madrid, Spain
ETRERA_2020 is a project funded by the EU call FP7-INCO-R2I, and aimed at improving S&T and entrepreneurial relationships between EU Member States and the Neighboring Mediterranean Countries in the strategic field of renewable energy production, storage and distribution by actions targeted to bridging the existing gap between research and innovation. ETRERA_2020 will address its efforts on secure, clean and efficient energy societal challenge with a focus on: wind, photovoltaic, solar thermal, hydrogen and fuel cells, smart grids.
The project is based on the creation of a research network involving primary actors across the research to innovation value chain consisting of 8 Research centres , 2 Intermediary organization providing innovation support services & technology transfer, 2 Business community & Entities managing industrial cluster and science park & incubator.
The project foresees a set of ambitious objectives to be reached within its conclusion both by improving human resources & know how of NPC centers, both by increasing the networking opportunity, the public - private partnership, the accessibility to research facilities, and the project/partners visibility.
The approach to the project and its preparation, management and implementation will be exposed.
Session FA-2 - Proton-conducting (PEFCs) and Alkaline (AFCs) Polymer Electrolyte Fuel Cells
FA-2:IL01 Activity and Durability of PEFCs Alloy Core-shell Catalysts: Role of Surface Oxidation
P.B. BALBUENA, G. RAMOS-SANCHEZ, Texas A&M University, College Station, TX, USA; F. GODINEZ, O. SOLORZA-FERIA, Centro de Investigacion y Estudios Avanzados de Instituto Politecnico Nacional, Mexico, D.F., Mexico
We evaluate the oxygen reduction reaction activity and durability behavior of core-shell alloy particles exposed to acid medium. We focus on particles with a Ni core and a shell of Pt, which are synthesized and characterized experimentally and analyzed with density functional theory (DFT) and Kinetic Monte Carlo (KMC) simulations. We are interested in determining the role of subsurface oxidation on particle degradation. Current experimental information suggests the presence of some form of Ni oxide in the core. Thus DFT calculations are implemented to verify the mechanical and chemical stability of Pt films on such structures and their activity and durability properties. In addition, we use KMC simulations to investigate the possibility of Pt migrating to the interior of the nanoparticle, and how the synthesis conditions may favor Pt diffusion to the core in galvanic displacement reactions.
FA-2:IL02 New Fuel Cell Electrocatalysts from South Africa - Variations of the Support and the Catalyst Composition
O. CONRAD, HySA/Catalysis, University of Cape Town, Cape Town, South Africa
More than 80% of the world's known reserves and resources of platinum group metal (PGM) minerals are in South Africa. The country's mining industry currently provides three quarters of the world's annual platinum metal consumption.
In 2007 the South African Department of Science and Technology initiated an ambitious 15-year programme to create a South African value-added manufacturing industry to supply materials and components into the global hydrogen and fuel cell markets. HySA/Catalysis was formed specifically to develop catalysts and catalytic devices for fuel cells, electrolysers and fuel processors.
In 2013 HySA/Catalysis introduced a 40% Pt/C catalyst at commercially relevant scale ready for validation with international industrial and academic partners.
This presentation will provide technical detail on some recent developments of advanced catalysts covering both variation of the catalyst support as well as the morphology and element composition of the catalytic particles.
HySA/Catalysis is following international trends in tackling the dual goal of decreasing the platinum content of fuel cells while simultaneously increasing their durability.
FA-2:IL03 Catalysts and Durability Issues of Polymer Electrolyte Fuel Cells
T.J. SCHMIDT, Electrochemistry Laboratory, Paul Scherrer Institut, Villigen PSI, Switzerland
Electrocatalysis in Polymer Electrolyte Fuel Cells (PEFCs) is a lively field in research since the cathodic oxygen reduction reaction is one of the reasons for PEFC efficiency limitations. In addition to the kinetic limitations, the durability and stability of specifically cathode catalysts and catalyst layers are imposing major challenges due to corrosion instabilities of both the catalyst support (predominantely carbon) and the active phase consisting typically of Pt or Pt-alloy based nanoparticles. In order to overcome these stability limitations, several mitigation strategies on the materials level exist:
i) Instead of carbon supports, transition metal oxide supports may be used which may not be further oxidized, i.e., metal oxides in their highest oxidation state ;
ii) un-supported catalysts forming extended structures of the active phase are widely described (e.g., Pt-black, NSTF-like structures as introduced by 3M , or metallic high surface are nanostructured catalysts .
In this contribution, there will be a discussion on the suitability of these aforementioned two approaches including their advantages and disadvantages.
 A. Rabis, et al. ACS Catal., 2012, 2 (5), pp 864-890
 W. Liu, et al. Angew. Chem. 2013, 52, pp. 9849-9852
FA-2:L04 Nitrogen-free Non-precious Metal Catalyst for Oxygen Reduction based on Iron Carbide Nanoparticles Confined in Curved Carbon Nanotubes
QINGFENG LI, YANG HU, J.O. JENSEN, WEI ZHANG, L.N. CLEEMANN, N.J. BJERRUM, Department of Energy Conversion and Storage, Technical University of Denmark, Kgs. Lyngby, Denmark
Highly active catalysts for the oxygen reduction reaction (ORR) are needed for fuel cells.The state-of-the-art catalyst is based on precious metals, whose prohibitive cost, limited resources and insufficient durability preclude commercialization of the technology. Development of non-precious metal catalysts (NPMCs) has been a foremost subject of the field. Among the investigated materials is the carbon-supported transition metal/nitrogen composite of most interest where the active sites are always involving the surface nitrogen coordinated with the metals. In this talk we report a new type of NPMCs with a microspherical morphology consisting of iron carbide nanoparticles confined in curved carbon nanotube networks. The catalyst is prepared by high pressure pyrolysis and contains little surface nitrogen nor iron elements but exhibits high ORR activity and stability in both acidic and alkaline media. Synergy of stabilizing carbon layers of the interconnected carbon nanotubes and the underneath activating carbide particles of the catalyst is proposed to be responsible for the catalytic performance.
FA-2:IL05 Development of Pt and Pt-Alloy Electrocatalysts for the Next Generation Polymer Electrolyte Fuel Cells
M. WATANABE, H. UCHIDA, M. WAKISAKA, S. YANO, Fuel Cell Nanomaterials Center, University of Yamanashi, Kofu, Japan
Development of highly active and durable electrocatalysts for the oxygen reduction reaction (ORR) are essential for polymer electrolyte fuel cells (PEFCs) as well as CO tolerant anode catalysts to achieve the reduction of Pt loading amounts currently used to less than 1/10 without loss of the performances for the wide commercializations. There are a couple of approaches to the goal, e.g., alloying Pt with the second metals M, nano-sizing the catalyst particles or effective use of them in the membrane-electrode assemblies. First, I will present the design of highly active alloy electrocatalysts using sputtered ones and single-crystals and discuss mechanism of the catalysis based on modern analysis tools. Then, we demonstrate the important discovery, i.e., there is no so-called "particle size effect" for the ORR at Pt catalysts supported on carbon black (CB) even at <2nm in diameter. Finally the preparation of monodispersed pure Pt and Pt−M alloy particles supported on CB or graphitized CB (GC) with well-controlled composition, extremely sharp size-distribution and the distinctive durability at the practical operation modes in comparison with the commercial catalysts will be presented.
FA-2:IL06 Electrocatalyst Stability under Dynamic and Stationary Operation of Polymer Electrolyte Fuel Cells
K.A. FRIEDRICH, S. HELMLY, German Aerospace Center, Institute of Technical Thermodynamics, Stuttgart, Germany; R. HIESGEN, T. MORAWIETZ, University of Applied Sciences Esslingen, Department of Basic Science, Esslingen, Germany
Durability and cost are two barriers recognized for the extensive application of proton exchange membrane (PEM) fuel cell as a promising clean energy technology. To date, considerable effort has been made to study the performance and component degradation via diverse methods and for accelerated degradation, routines have been developed. For instance, operation at open circuit voltage (OCV) is one of the most frequently employed high potential stressors for a PEM fuel cells leading to Pt electrocatalyst dissolution and membrane decomposition. Single cells as well as short stacks were aged under different operation conditions which are discussed in the literature to accelerate degradation of electrocatalyst and membranes. Numerous in-situ and ex-situ analysis is applied to understand the importance of different degradation mechanisms.
A general conclusion from these measurement is that Pt dissolution plays an important - perhaps even the crucial - role for the loss of electrochemical surface area and membrane decomposition. To demonstrate this aspect, membranes were first impregnated with Pt ions which were reduced and the fluoride emission rate was measured.
FA-2:IL07 Towards Fuel Cell Vehicle Commecialization
I. CERRI, Toyota Motor Europe, Zaventem, Belgium
In the transport sector, fuel cell technology represents one of the most effective strategies to dramatically reduce our global warming pollution and oil usage. Fuel cell is one the most promising future power sources because of its impressive efficiency; furthermore, when integrated with hybrid technology, fuel cell can yield higher system-level efficiencies. Toyota has been developing technologies for the Fuel Cell Hybrid Vehicle (FCHV) since 1992 and demonstrated its progress by being one of the first automakers to bring a fuel cell vehicle to market in December 2002. Since then, Toyota has continued to improve the vehicle's performance through detailed studies of data from customer use and testing.
Historically, the industry has identified several issues that must be solved prior to the widespread acceptance of the FCHV in the market, such as driving range, cold start capability, stack durability, cost reduction, and hydrogen infrastructure creation. In the FCV-R, Toyota's latest fuel cell based systemm, we significantly improved the driving range, cold start capability, and stack durability. We are aiming for commercialization by 2015 and we are tackling the cost reduction issue by design modification, advanced production methods and new materials.
FA-2:IL08 High Temperature Polymer Fuel Cell Membranes Based on PBI
E. QUARTARONE, Dept. of Chemistry, University of Pavia, and INSTM, Pavia Italy
Polymer electrolyte fuel cells (PEMFC) are leading-edge targets for what concerns the key technology of the next generation hydrogen-powered vehicles. However, the scale-up of PEMFCs is still limited by their incompatibility with the operating conditions of the automotive applications, namely working temperatures around 130°C and low humidification. Acid-doped Polybenzimidazoles are actually considered as promising electrolytes to replace Nafion in HT-PEMFCs. Nevertheless, some relevant questions are still open: under which operating conditions (chiefly temperature) are the acid-doped PBI systems a real alternative to Nafion? What is the real durability of the PBI cells/stacks?
Here we will report the state of the art and our most recent developments, which could make polybenzimidazole systems the market choice for high temperature (HT)-PEMFCs. Particular emphasis is given to problems such as acid leaching, membrane degradation and stack durability, as well as to the strategies adopted in our laboratory to properly address these issues.
FA-2:IL09 New Polymer Electrolyte Membranes for Fuel Cells
E.A. WEIBER, HAI-SON DANG, S. TAKAMUKU, P. JANNASCH, Department of Chemistry, Lund University, Lund, Sweden
Durable polymers functionalized with acidic or basic groups are currently developed for proton- or anion-exchange membrane (PEM or AEM) fuel cells, respectively. The properties of perfluorosulfinic acid PEMs restrict the conditions under which these fuel cells can be operated because of limitations conductivity and stability. We are presently pursuing different approaches to alternative membranes where sulfonic acid groups are concentrated to selected aromatic segments in the polymeric structure to induce a higher level of organization of the conducting phase domains in the PEM. This includes for example the preparation of various highly stable hydrophilic-hydrophobic multiblock copolymers with blocks having very high acid contents. This leads to excellent performance and high proton conductivity at low relative humidity. AEM fuel cells hold the promise of platinum free catalysis, but present critical challenges in terms of membrane conductivity and stability. Here, we are preparing and studying various aromatic AEMs which contain very high local concentrations of ammonium moieties for high anionic conductivity and enhanced durability. Macromolecular design principles, synthetic procedures and important structure-property relationships of these new materials will be discussed.
FA-2:L10 Functionalized Metal Oxide Particles: A Comparative Study on their Use as Additives in Polymer Electrolyte Membranes
M.A. NAVARRA, S. PANERO, I. PETTITI, M. SGAMBETTERRA, Sapienza University of Rome, Rome, Italy
Large scale research efforts are still needed to meet the efficiency, durability and cost requirements for polymer electrolyte membrane (PEM) fuel cells (FCs). Developing electrolyte membranes that tolerate a wide range of operating conditions is particularly challenging. Desirable PEM must not only be highly proton conductive under hot and dry conditions, it should be thermally and dimensionally stable, impervious to fuels, as well as to electrons.
We here propose strategic routes, based on the formulation of new organic-inorganic composite membranes to overcome the most stringent limitations of the existing polymer electrolytes. Also, powerful investigation tools for a deep understanding of both micro- and macroscopic characteristics of the proposed materials will be presented.
Inorganic additives, belonging to the family of sulfated metal oxides and differing from specific morphological and surface properties, have been investigated. Their use as fillers in Nafion-based PEMs has been considered. A deep evaluation of the intrinsic properties of the composite membranes under critical parameters, such as dry or low relative humidity conditions and temperatures ranging from subzero to 120 °C, helped in tailoring the desired systems for the successful application in hydrogen PEMFCs.
FA-2:L11 Water-free Proton-conducting Membranes at Elevated Temperature
J. JALILI, V. TRICOLI, Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy
Proton-conducting polymer membranes were made by incorporating a suitable organic compound into proton-exhange polymer matrices. The incorporated compound possesses a Bronsted-base moiety and also proton donor/acceptor terminals. The basic moiety captures the proton from the acid groups of polymer, thereby anchoring the incorporated compound to the polymer by ionic bond. The proton donor/acceptor terminals enable proton transport, under an applied electric field, by a hopping mechanism. This transport mechanism can occur even in the absence of water, as the proton jumps from one terminal to an adjacent one by hydrogen-bond formation and rupture. An extensive physico-chemical characterization of the composite membranes has been carried out. The membranes are homogeneous with the impregnating compound dispersed at the molecular level in the polymer matrix. They are also thermally stable up to 400°C. They are flexible and mechanically resistant. Most importantly, these membranes display proton conductivity in excess of 0.01 S/cm under fully anhydrous conditions at elevated temperature. Because of these characteristics, they appear attractive for high-temperature PEMFC application.
FA-2:IL14 Proton- and Hydroxide-conducting Polymer Electrolytes for Electrochemical Energy Technologies
M.L. DI VONA, Univ. Roma Tor Vergata, Dip. Scienze e Tecnologie Chimiche, Roma, Italy
Ionic conducting polymers are very versatile materials used in several applications such as proton and anion exchange membrane fuel cells or redox-flow batteries. The future of this type of technology depends greatly on the enhancement of membrane stability. The polymer electrolyte membrane must be improved in terms of durability; most importantly, it must operate in an aggressive environment and under harmful experimental conditions, and it must present a reduced permeability. In general, anion exchange membranes show lower permeability than cation exchange membranes. Unfortunately, most commercial anion exchange membranes do not have sufficient chemical stability and present a low conductivity.
The most promising group of exchange membranes, alternative to Nafion, is that of Aromatic Polymers (AP). We have in recent years concentrated on improvement of existing AP, introducing Van der Waals bonds (organic-inorganic hybrids) or covalent bonds ("cross-links").
In this invited talk, we will discuss how the synthesis conditions and the formation of cross-links can be used to obtain cationic and anionic ionomers with improved properties.
FA-2:L15 Influence of Acid Loss in PBI-based HT-PEM Fuel Cells during Long-term Operation
N. BRUNS, M. RASTEDT, F.J. PINAR PÉREZ, P. WAGNER, NEXT ENERGY- EWE Research Centre for Energy Technology, Oldenburg, Germany
Fuel cell technology is acknowledged as an important contribution to research on the efficient use of energy for mobile and stationary applications. Improved reaction kinetics, better tolerance to fuel impurities and simple design are the main advantages of the high temperature polymer electrolyte membrane fuel cell (HT-PEMFC). However, PBI-based fuel cell technology still suffers from high costs and low durability, which hinders commercialization.
Loss of phosphoric acid (PA) has been proposed as one of the major degradation mechanisms that influence durability of PBI-based PEM fuel cells. In this study, the leaching of acid in a PBI-based single cell was investigated during long-term operation. Ion chromatography, ICP-MS, REM-EDX and titration have been used as analytical methods to detect the loss of PA. Additionally, electrochemical characterization methods were performed in a fuel cell station to understand the relationship between fuel cell degradation and PA loss rate. The investigation of HT-PEMFCs was carried out with commercial MEAs (25 cm2) from different suppliers.
FA-2:L17 Hydration and Proton Conductivity of Proton-conducting Ionomers
P. KNAUTH, Aix Marseille University, CNRS, UMR 7246, Marseille, France
We have worked recently on the hydration and conduction properties of hydrated acidic ionomers for applications in electrochemical energy technologies, including polymer electrolyte membrane fuel cells.
Our main objective is the improvement of sulfonated aromatic polymers by cross-linking treatments that impact both hydration and conductivity [1,2]. The studied ionomers include Sulfonated Poly-Ether-Ether-Ketone (SPEEK) and Sulfonated Poly-Phenyl-Sulfone (SPPSU).
We will discuss models allowing to describe, but also to predict, these properties [3,4] and to optimize the performances in fuel cells, but also the membrane durability .
1. P. Knauth et al. Fuel Cells, 13, 79 (2013)
2. H. Hou et al. J. Membr. Sci, 423, 113 (2012)
3. P. Knauth et al. J. Power Sources, 243, 488 (2013)
4. P. Knauth et al., Solid State Ionics, 225, 255 (2012)
5. H. Hou, ChemSusChem, 4, 1526 (2011)
FA-2:L18 Evaluation of Titanium Oxide in the Electrode Structure for Portable PEFCs Applications
I. GATTO, A. CARBONE, A. SACCÀ, R. PEDICINI, E. PASSALACQUA, CNR-ITAE, Messina, Italy
Polymer electrolyte fuel cells (PEFCs) are the best candidates to power a variety of devices, especially for portable applications. But restrictive operative conditions such as low pressure and low humidification are required to minimize the size and weight of auxiliaries, to improve the total efficiency of the system. Hence, the optimization of the electrodes structure to operate in such conditions is necessary to improve the performance. In this work, the influence of the titanium oxide presence in the catalytic layer on the MEA performance was evaluated. Titanium oxide was selected as a good candidate due to its dual property: it can acts as mechanical reinforcement for the Pt catalyst; it can represents a good catalyst for the decomposition of hydrogen peroxides, forming in fuel cell operations. Composite electrodes containing different amount of commercial titania were developed, with a Pt loading of 0.3-0.6 mg/cm2 at anode and cathode, respectively. The electrodes were assembled to a commercial NR212 to obtain the MEAs. The electrochemical studies, in terms of I-V curves, EIS spectra and cyclic voltammetries, were carried out in a 25cm2 single cell. The cell temperature ranging between 60-80°C, low pressure and low relative humidity were used as operative conditions.
FA-2:IL19 Kinetics of the Hydrogen Oxidation in Alkaline and Acid Environment
H.A. GASTEIGER, H. BEYER, C. DENK, J. DURST, H. EL-SAYED, T. GEPPERT, T. GREESE, F. HASCHE, J. HERRANZ, P. MADKIKAR, M. PIANA, P. RHEINLÄNDER, A. SIEBEL, X. WANG, Technical Electrochemistry, Chemistry Department, Technische Universität München, Garching, Germany
The development of alkaline membrane fuel cells based on alkaline membranes is one of the options to reduce the required amount of platinum, whereby the strong CO2 sensitivity of alkaline membranes is a significant challenge. While there are several non-noble metal catalysts for the oxygen reduction reaction in alkaline electrolytes which match the activity of platinum, the only currently known hydrogen oxidation catalysts are based on platinum or palladium. Furthermore, the activity of platinum is orders of magnitude lower than in acidic electrolytes, so that ultra-low platinum loading anodes which can be used in acidic electrolytes are not feasible in alkaline electrolytes. Therefore, the challenge to catalysis research for AMFCs is to develop more active hydrogen oxidation catalysts.
In our presentation, we will examine the kinetics of the hydrogen oxidation reaction (HOR) on platinum and palladium-based catalysts in alkaline electrolytes, determined by rotating disk electrode and by hydrogen pump measurements using alkaline membrane based MEAs. These data will be compared to the HOR kinetics obtained in the acidic environment.
This research was partially funded by the Fuel Cells and Hydrogen Joint Undertaking (FP7/2007-2013; Duramet) and by CellEra (Israel).
FA-2:IL20 Nitrogen-doped Carbon Materials as Catalysts Supports for the Electro-oxidation of Metanol
M.J. LAZARO, M.J. NIETO, D. SEBASTIÁN, C. ALEGRE, M.E. GÁLVEZ, I. SUELVES, R. MOLINER, Instituto de Carboquímica, CSIC, Zaragoza, Spain
Carbon materials such as carbon nanofibers and carbon xerogels were functionalized and doped (respectively) with nitrogen. The aim of the present work was using such doped-carbon materials as catalysts supports for the electro-oxidation of methanol. These carbon materials present several characteristics that make them suitable supports for catalyst for fuel cells.
Several functionalization treatments were assessed: ammonia (25%), urea (98%), melamine (99%) y ethylenediamine (99.5%), with a carbon: nitrogen molar ratio 1:0.6. These treatments were also carried out in a commercial carbon black support, Vulcan XC-72R, usually employed as supports for fuel cells catalysts, for the sake of comparison.
Nitrogen-doped carbon xerogels were synthesized by using melamine as nitrogen precursor. Resorcinol, melamine and formaldehyde were mixed in basic medium, followed by curing and pyrolysis.
Carbon materials were characterized by elemental analysis, nitrogen adsorption, XRD, XPS, SEM-EDX and TEM. After that, Pt-nanoparticles were supported on previously obtained carbon materials, by means of a microemulsion method. The influence of the nitrogen in the carbon materials had been compared to the properties and the behaviour in the electrochemical oxidation of methanol.
FA-2:L22 Non-noble Metal Catalysts for Fuel Cell Applications
E.E. WESTSSON, G.J.M KOPER, Technical University of Delft, Delft, The Netherlands
Up until today the number one option for catalyzing the oxygen reduction reaction taking place on the cathode in a PEM fuel cell, has been platinum supported on high surface area carbon. However, the low abundance of platinum and high costs hampers large scale application of fuel cell technologies.
As for alternative materials to platinum, a lot of attention has also been drawn to transition metal containing organic molecules - inherently cheap and abundant material. Materials like phthalocyanine and porphyrine have been potential candidates due to their relatively high stability in acidic conditions. Following on the discovery of graphene and carbon nanotubes, the possibility of introducing similar moieties into graphitic lattices opens up great opportunities. Here, two novel nitrogen-containing organic structures are being evaluated; one imidazole-analogue of porphyrine representing the Me-N4 case and the other being a polymeric structure with bipyridinic-like coordination sites (Me-N2).
Further a systematic study is being carried out addressing the incorporation of nitrogen into sp2-hybridized carbon lattices. In order to optimize the catalytic properties of graphitic materials it is of greatest importance that the configuration of the introduced nitrogen can be tailored.
FA-2:IL24 Pt-Ru Electrocatalysts for CO and Methanol Oxidation Supported on Carbon Nanofibers: Influence of Synthesis Methods on Activity
J.C. CALDERÓN1, L. CALVILLO2, M.J. LÁZARO2, G. GARCÍA1, J.L. RODRÍGUEZ1, E. PASTOR1, 1Dpto. Química Física, Instituto Universitario de Materiales y Nanotecnología, Universidad de La Laguna, La Laguna, Tenerife, Spain; 2Instituto de Carboquímica (CSIC), Zaragoza, Spain
Pt-Ru electrocatalysts supported on carbon nanofibers were prepared using different synthesis routes. Physicochemical characterization was performed employing energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), photoelectron X-ray spectroscopy (XPS) and transmission electron microscopy (TEM). Results showed that Pt-Ru catalysts with similar metal content (20%) and atomic ratio (Pt:Ru 1:1) were obtained for all methods. These materials were studied for CO and methanol electro-oxidation reactions in acid media, applying cyclic voltammetry and differential electrochemical mass spectroscopy (DEMS), as well as chronoamperometry in the case of methanol. Activation energies were determined from experiments at different temperatures and the rate determining step in the oxidation mechanism established. Activation energy values, CO2 conversions and oxidation activities were discussed in terms of crystallite sizes and surface composition.
FA-2:L25 Combination of Stochastic and Numeric Modeling of Fibrous Microstructures of HT-PEFC Gas Diffusion Layers
D. FRONING1, J.P. BRINKMANN1, G. GAISELMANN2, U. REIMER1, V. SCHMIDT2, W. LEHNERT1, 1Forschungszentrum Jülich GmbH, Jülich, Germany; 2Ulm University, Germany
The gas diffusion layer (GDL) connects the electrodes with the feeding channels in fuel cells of the type PEFC, DMFC and HT-PEFC. Efficient operation of fuel cells requires that the electrodes are sufficiently supplied by fuels from the channels, and reaction products must be transported away from the electrodes. The mass transport of these fluids is one major task for the GDL, which also has to provide electric contact to the bipolar plates. The GDL itself is composed of materials based on carbon fibers, e.g. paper, woven and non-woven textiles.
The geometry of the GDL is described by a 3D stochastic simulation model, with its parameters fitted from a 2D SEM image. Based on the stochastically generated microstructure, transport processes are numerically modeled by the Lattice Boltzmann technique.
In real fuel cells, different local compressions influenced by the applied flow fields lead to different microstructures in regions under the land and under the channels. The effect of compression is discussed in detail. The mathematical model provides the opportunity to simulate transport processes in virtual structures, to detect quantitative relationships between functionality and microstructure and to design virtual GDL materials with improved transport properties.
Session FA-3 - State-of-the-art Application Engineering and Demonstrations
FA-3:IL01 Perspectives for Fuel Cells and Hydrogen in Europe
B. DE COLVENAER, FUEL CELLS AND HYDROGEN JOINT UNDERTAKING, Brussels, Belgium
The Fuel Cell and Hydrogen Joint Undertaking (FCH JU) was established by Council Regulation (EC) 521/2008 of the 30th May 2008 as a Community Body on the basis of Article 171 of the EC Treaty , with the European Commission and the Industry Grouping as founding members. The Research Grouping joined shortly after. The FCH JU is considered as one of the European Industrial Initiatives under the SET Plan and was created with the mission to reach a new level of coordination, joint agenda setting, cooperation and commitment including co-financing. The FCH JU aims at placing Europe at the forefront of fuel cell and hydrogen technologies worldwide and enabling the market breakthrough of fuel cell and hydrogen technologies, thereby allowing commercial market forces to drive the substantial potential public benefits. In terms of direct support by the FCH JU, the main instrument for achieving this goal from the period of 2008-2013 has been the award of research, demonstration and support projects following competitive annual calls for proposals.
The purpose of this presentation is to highlight the first results achieved in the projects supported by the FCH JU and to present the FCH 2 JU under the Horizon 2020, the new Framework Program of the European Commission.
FA-3:IL02 Materials and Concepts for Full Ceramic SOFCs with Focus on Carbon Containing Fuels
P. HOLTAPPELS, B.R. SUDIREDDY, S. VELTZÉ, T. RAMOS, Departament of Energy Conversion and Storage, Technical University of Denmark, Roskilde, Denmark
Todays' solid oxide fuels cells based on composite Ni-cermet anodes have been developed op to reasonable levels of performance and durability. However, especially for small combined heat and power supply systems, known failure mechanisms e.g. re-oxidation, sulfur tolerance and coking have stimulated the development for full ceramic anodes based on strontium titanates. Furthermore, the Ni-cermet is primarily a hydrogen oxidation electrode and efficiency losses might occur when operating on carbon containing fuels.
In a recent European project full ceramic cells comprising CGO/Ni infiltrated Nb-doped SrTiO3 anodes, and LSM/YSZ cathodes have been developed and tested as single 5 x 5 cm2 cells. The initial performance reached 0.4 W/cm2 at 850 °C and redox tolerance has been proven. The cell concept provides flexibility with respect to the used electro catalysts and their impact on power output, stability, and S- tolerance has been investigated. These results and an assessment on a 1 kW system level using CPOX reformed natural gas will be reviewed and further perspectives of the cell concept discussed, especially with respect to efficient operation on high carbon containing fuels.
Special Session FA-4 - DURAMET Workshop on Direct Alcohol Fuel Cells (DAFCs)
FA-4:IL01 The Long Way of Achieving a Durability of 20,000 h in a DMFC System
M. MÜLLER, N. KIMIAIE, A. GLÜSEN, Institute of Energy and Climate Research, Juelich Research Center, Germany; D. Stolten, Director Institute for Electrochemical Process Engineering, Juelich Research Center & Chair for Fuel Cells, Aachen University, Germany
Direct Methanol Fuel Cells are an attractive power source for applications in the low kW-range like pallet trucks or uninterruptable power supply. A significant problem during the past years, however, was the limited durability of DMFC systems. While single cells could be operated for thousands of hours, DMFC systems degraded significantly often after less than 1,000 hours.
In an evolution of six generations of DMFC systems in the kW power range over the past decade, we identified the main reasons for degradation. Causes for fast degradation had to be removed first in order to identify what leads to slower degradation over several hundreds or thousands of hours. Interactions of cells and system components also had to be considered.
As a result, the operating conditions of all cells must be carefully controlled by suitabl e operating algorithms and reproducible manufacturing technologies, in order to avoid high potentials on the anode, which would lead to ruthenium corrosion and subsequent poisoning of the cathode catalyst. All components of the stack and the peripheral system must be corrosion-proof and free from contaminants that might leach into the membranes. Finally, a DMFC system for a pallet truck was operated in a realistic load cycle for 20,000 hours.
FA-4:L02 Improved Durability and Cost-effective Components for New Generation Direct Methanol Fuel Cells - DURAMET Project
A.S. ARICO', CNR-ITAE, Messina, Italy
The aim of DURAMET project is to develop cost-effective components for direct methanol fuel cells (DMFCs) with enhanced activity and stability. The project regards the development of DMFCs for application in auxiliary power units (APU) as well as for portable systems. The efforts are focused on cost-effective membranes with better resistance than Nafion to methanol cross-over and to the drag of Ru ions. Improved durability electro-catalysts are developed with the aim to reduce costs, degradation and noble metals content. To validate the new membranes and electro-catalysts materials, specific development of membrane-electrode assembly with tailored hydrophobic-hydrophilic electrode characteristics is carried out. The new developed components are validated in short stacks to assess performance and durability under practical operation.
The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2011-2014) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement Duramet n°278054).
FA-4:L03 DMFC Degradation and Lifetime Studies
J.L. BONDE, IRD Fuel Cells, Svendborg, Denmark
The step from small-scale prototype manufacturing to the commercialization of fuel cells is a major challenge. The direct methanol fuel cell system, directly converting methanol to power, water and CO2 is one of the potential future substitutes for power generators. The potential applications range from stationary power sources to mobile battery chargers or range extenders.
IRD is participating in several national and international projects ranging from MEA development to field test of DMFC systems.
Durability studies and impact of the various operating conditions on catalyst stability and study of components integrity is mandatory to tailor the right approach leading to further performance and lifetime enhancement. The presentation will include the status and latest results from the development and test of cells and systems. Durability and performance of the MEAs in commercial fuel cell applications will also be discussed.
FA-4:IL05 Methanol-tolerant Cathode Catalysts for DMFC
J. MA, A. HABRIOUX, C. MORAIS, N. ALONSO-VANTE, IC2MP, UMR-CNRS 7285, University of Poitiers, Poitiers, France
The direct methanol fuel cells (DMFCs) have attracted much attention as an alternative power source for portable applications. Technically, there are still various critical issues, including the sluggish kinetics of both cathode and anode reactions and the fuel cross-over effect. These difficulties have to be overcome before developing successful commercial applications. The development of highly active catalysts toward the oxygen reduction reaction (ORR) in the presence of methanol is needed. The research efforts have been devoted to the development of advanced nanocatalysts to accomplish such expectations. Different nanomaterials have been proposed in order to overcome the ORR activity loss in the presence of methanol. Cathodes with chalcogenide metallic centers of Ru, Ir, and Co, have proven to be very tolerant to methanol. The addition of a chalcogenide element indeed improves the activity of the metal towards ORR in electrolyte solutions containing methanol. In this work, we address our discussion on the use of tolerant cathode catalysts such as carbon supported PtxTiy and/or PtxSey nanomaterials in an air-breathing methanol microfluidic fuel cell.
FA-4:L06 DECORE: A New European Project Aiming at Innovative DEFCs Operating at Intermediate Temperatures
G. GRANOZZI, Department of Chemical Sciences, University of Padova, Italy
DECORE started its activity from January 2013 (four years project). It is a Small-scale (7 partners) project financed by the EC within the call: NMP.2012.1.1-1.
The main goal of DECORE is to achieve the fundamental knowledge needed for the development of a fuel cell (FC) electrode in acidic ambient, which can operate efficiently as the anode of a direct ethanol (EOH) FC (DEFC) in the temperature range between 150-200 °C (intermediate-T). The intermediate-T is required for an efficient and selective total conversion of EOH to CO2. DECORE will explore the use of fully innovative supports (oxycarbides) and nano-catalysts (metal carbides, MCx), never tested in literature as anodes for DEFCs. The new supports are expected to be more durable than standard carbon supports at the targeted temperature. The innovative nano-catalysts would be noble-metal free, so reducing Europe's reliance on imported precious metals. To tailor the needed materials, the active role of the support and nano-catalyst will be studied at atomic level. The Consortium is composed by 5 academic groups (Padova, Coordinator, TUM, Milano-Bicocca, Copenhagen, Laguna, Tenerife), one group from CNR (ICCOM) and one industrial partner (Elcomax GmbH).
The main outcomes from the first year of project will be outlined.
FA-4:L07 3D Direct Methanol Fuel Cell (DMFC) Validation Model for Analyzing New Materials and Components
N.S. VASILE, A.H.A. MONTEVERDE VIDELA, S. SPECCHIA, Politecnico di Torino, Department of Applied Science and Technology, Torino, Italy
DMFCs are seen as promising devices for portable applications and stationary backup units. Modeling together with experimental testing can provide an understanding tool for analyzing and comparing designed new materials. This study proposes a 3D vectorial model for predicting and optimizing materials for MEAs. The model considers Maxwell-Stefan, Flory-Huggens, Maxwell-Stefan and Butler-Volmer equations computed in Comsol® software.
All experiments used for the model validation were carried out using a small-scale laboratory single DMFC with an external area of 25 cm2. The cell was fitted with a MEA sandwiched between two graphite blocks with parallel channels for oxygen and methanol flows. As an example, the distribution of O2 mole fraction during the reaction along the cathode side at 0.4 V using standard catalysts (Pt, Pt/Ru carbon based, 2.0 mg/cm2 lined on a Nafion® 117 membrane), is not homogeneous: the reaction performs in a fast way on the inlet part, suggesting a fast starting kinetic. The current density produced on the membrane, in fact, is not homogeneously distributed along the membrane, suggesting fluid dynamics problems or catalyst diffusion obstruction.
Funding of the DURAMET project (FP7 FCH-JTI grant n. 278054) is gratefully acknowledged.
FA-4:L08 Impact of N/Zr Atomic Ratio on the Oxygen Reduction Reaction Activity of Heat-treated Carbon-supported Zr-oxyphthalocyanine
T. MITTERMEIER, C. DENK, XIAODONG WANG, H. BEYER, P. MADKIKAR, M.PIANA, H.A. GASTEIGER, Technische Universität München, Garching, Germany
Organometallic complexes like phthalocyanines have been studied as non-noble metal catalysts for the oxygen reduction reaction (ORR) for several decades. More recently, valve metal oxides formed by heat treatment (HT) of such complexes have been investigated for their good chemical stability in acidic environment and for their superior methanol tolerance compared to commercially available Pt-based catalysts. In this study, a systematic variation of nitrogen residues from the Zr oxyphthalocyanine precursor relative to the transition metal atomic content was achieved, depending on the HT parameters such as time and temperature based on TGA analysis. The electrochemical ORR activity of the catalyst over the various resulting N/Zr atomic ratios was evaluated in a thin-film rotating disk electrode configuration. A further comparison of the ORR activity of a pure N-based catalyst produced from metal-free complex was carried out in order to gain knowledge about the electro-active center.
The research leading to these results receives funding from the Fuel Cells and Hydrogen Joint Undertaking under Grant Agreement Duramet n°278054 as part of the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (FP7/2007-2013).
FA-4:L09 Direct Methanol Fuel Cell Stack Design and Test in the framework of DURAMET Project
O. BARBERA, A. STASSI, V. BAGLIO, D. SEBASTIAN, A.S. ARICO', CNR- ITAE, Messina, Italy
Direct methanol fuel cell stacks, with different architecture have been developed. A fuel cell planar stack, operating in passive mode, has been designed for portable application. The device consists of 10 cells, with nominal power of 1.00 - 2.42 W, single cell active area of 4.85 cm2, nominal current of 1.00 A, at room pressure and temperature. Two printed circuit boards have been chosen to clamp and support the MEA and to electrically connect the active areas by conductive pathways. To investigate the stack performance, 4 different boards with different feeding holes shape have been designed. For high temperature operation purpose, a device with "stacked" configuration has been designed. Operating parameters are: nominal power of 150W, single cell active area of 100 cm2, nominal current of 25 A, cell number of 10. The stack performance has been investigated in different operative conditions. Promising results have been obtained for portable and APU applications.
The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2011 - 2014) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement Duramet n°278054).
FA-4:L10 Enhanced Proton Transport and Water Retention in Nanocomposite Membranes for HT-PEMFCs using Organo-Modified Layered nanostructures
I. NICOTERA, I. NICOTERA, K. ANGJELI, C. SIMARI, L. COPPOLA, G.A. RANIERI, University of Calabria, Rende (CS), Italy
High-temperature PEM fuel cells are considered to be the next generation of fuel cells. Several polymers and membranes have been proposed to work at temperatures above 80°C, and composite Nafion membranes containing ceramic oxides have received much attention. In this work, a new class of layered fillers composed of Mg-Al hydroxides (layered double hydroxides- LDH) and novel organo-modified clays were prepared and tested as fillers for the creation of hybrid Nafion nanocomposites. LDHs, of anionic clay family, consist of stacks of positively charged mixed metal hydroxide layers that require the presence of interlayer anions to maintain overall charge neutrality. and our study was focused on the preparation of LDH with Mg2+/Al3+ metal cations (with metal ratio 2:1 and 3:1) and countervailing anions (CO32-, ClO4-, NO3- ) in the interlayer space. Smectite clays are a class of layered aluminosilicate minerals with a unique combination of swelling, intercalation, and ion exchange properties. In this study, two smectite clays (Laponite and montmorillonite) were loaded with various cationic organic molecules bearing several hydrophilic functional groups. The resulted hybrid membranes were characterize in terms of chemical-physical properties, while the water-transport properties were investigated by NMR spectroscopy. The results demonstrate a considerable effect on the Nafion polymer in terms both of water absorption/retention and water mobility with a remarkable behavior in the region of high temperatures (100-130 °C). Concerning LDH-composites, fuel cell tests performed in drastic conditions highlighted the influence of the different interlayer anions in composite membranes and a good performance was obtained for membranes with the cations ratio (Mg-Al) of 2:1.
FA-4:L11 Synthesis and Characterization of ZrO2 Nanoparticles from an Organometallic Precursor as ORR-Selective Catalysts for DMFCs
P. MADKIKAR, T. MITTERMEIER, C. DENK, X. WANG, M. PIANA, H.A. GASTEIGER, Technische Universität München, Institute of Technical Electrochemistry, Garching, Germany
Presently, Pt based materials have their place as ORR catalysts in DMFCs. However, they are facing various problems viz. cost, stability and methanol (MeOH) intolerance, which cannot be neglected in mass-scale commercialization of DMFCs. Our study is based on bottom-up synthesis and subsequent characterization of supported ZrO2 nanoparticles (NPs) on Ketjenblack carbon (KB) as ORR catalysts. They were prepared by organic synthesis of Zr-phthalocyanine as precursor, which was subsequently supported on KB and calcined. The loading of ZrO2 on KB was varied in order to understand its effect on particle size and dispersion of ZrO2. Physico-chemical characterization of the NPs was performed by XRD, SEM, TEM and elemental analyses. Electrochemical characterization was conducted at 20 °C by thin-film RDE technique in 0.1 M HClO4 electrolyte. They were tested for their stability and MeOH tolerance. The impact of ZrO2 loading on the electrochemical performance of the catalysts was also evaluated.
The research leading to these results receives funding from the Fuel Cells and Hydrogen Joint Undertaking under Grant Agreement Duramet n°278054 as part of the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (FP7/2007-2013)
FA-4:IL12 Degradation of Direct Methanol Fuel Cell: Analysis of Temporary and Permanent Phenomena and their Effects on Components
A. CASALEGNO, F. BRESCIANI, M. ZAGO, R. MARCHESI, Department of Energy, Politecnico di Milano, Italy
Degradation is one of the critical issues of Direct Methanol Fuel Cells (DMFC). The investigations found in the literature do not characterize systematically such complex phenomenon. The experimental activities carried out within the FCH-JU FP7 project Premium Act permit to identify and characterize temporary and permanent degradation phenomena at both anode and cathode electrodes. The most relevant results are here presented. The anode temporary degradation can be attributed mainly to the reduction of methanol and water concentrations in the electrode, due to carbon dioxide accumulation. The cathode temporary degradation is most probably caused by platinum oxides formation that hinders catalyst activity and can be recovered with a suitable procedure. An experimental characterization of mass transport through the DMFC evidences an evolution of methanol crossover during operation. Also methanol crossover reduction presents both temporary and permanent contributions. Finally permanent degradation of DMFC components is characterized, thanks to the development of a suitable methodology. The most affected component results to be the cathode electrode, due to a relevant decrease of the electrochemical active area, while the anode and the membrane exhibit a more stable behaviour.
FA-4:L13 The Use of Different Types of Reduced Graphene Oxide (rGO) on the Reduction Oxygen Reaction (ORR) under Alkaline Conditions
A.H.A. MONTEVERDE VIDELA, L. OSMIERI, S. SPECCHIA, Politecnico di Torino, Department of Applied Science and Technology, Torino, Italy
The high cost of Pt-based noble metal catalysts in PEMFCs hindered the commercialization of this technology. Here the attention is focuses on FeNx non-noble metal catalysts deposited over reduced graphene oxide (rGO) as promising catalysts for ORR.
Graphene nanosheets were prepared by the modified Hummer's method followed by a thermal exfoliation process under N2 or N2/H2 atmosphere at 500 or 700 °C. rGO samples were characterized by SEM, EDX, TEM and BET. Iron was used as complexing metal agent for producing the nitrogen doped catalyst. The FeNx/rGO catalysts were electrochemically characterized by LSV, CV, and RDE. Stability tests were conducted considering that carbon supported catalysts can suffer corrosion due to a weak interaction between metal and the carbon support. The use of nitrogen as a doping agent should increase the energy bonding of the metal to the support.
The support exfoliated under N2 atmosphere at 700 °C showed better electro-activity than the support synthesized under H2/N2 atmosphere, under kinetics control conditions (0.9-0.7 V). Moreover, an higher double layer capacitance is present, confirming more electro-activity.
Funding of the NAMED-PEM project from the Italian MIUR is gratefully acknowledged.
FA-4:L15 Composite Anode Catalysts based on PtRu and Metal Oxides for DMFCs
D. SEBASTIAN, V. BAGLIO, C. D'URSO, A. STASSI, A.S. ARICO', CNR-ITAE, Messina, Italy
Composite anodes were developed to increase the performance of a direct methanol fuel cell (DMFC). Fine metal oxide nanoparticles were synthesized by a sulfite complex method. These metal oxides (MO2) were mixed with a 50% PtRu/C catalyst prepared by the same procedure. A catalytic ink, composed of PtRu/C catalyst, MO2 (M = Ir, Ti, etc.) and Nafion ionomer, was deposited on a carbon-cloth-based backing layer and used as composite anode in a DMFC. A significantly higher performance was recorded for the composite electrode-based MEAs compared to the bare one based only on PtRu/C. The results confirm that the electrocatalytic activity is related to the characteristics of water displacement prompt by the additive, which acts as a co-catalyst for this reaction. The improvement was significantly higher by using high methanol concentration in water as the fuel, which means promising utilization in DMFC systems for prolonged operation. These results evidence that a multifunctional catalyst can operate better than PtRu for methanol oxidation since this multi-step process requires different functionalities to speed up the reaction rate.
The authors acknowledge the financial support from the European Community's Seventh Framework Programme (FP7/2011-2014) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement DURAMET no. 278054.
FA-4:L16 Pd-based Electrocatalysts as Cost-effective Cathodes for Direct Methanol Fuel Cells
V. BAGLIO, C. D'URSO, D. SEBASTIÁN, A. STASSI, A.S. ARICO', CNR-ITAE, Messina, Italy
Among the various categories of fuel cells, Direct Methanol Fuel Cells (DMFCs) working at low temperatures (up to 90°C) and employing proton exchange membranes have been postulated as suitable systems for power generation in the field of portable power sources, remote and micro-distributed energy generation as well as for auxiliary power units (APU) in stationary and mobile applications. In order to be competitive, the DMFCs must be reasonably cheap, they should be characterised by high durability and capable of delivering high power densities. Despite these advantages, technical barriers still need to be overcome for their large scale commercialization. It is well known that one of the problems affecting DMFCs is the poisoning of the cathode surface in the presence of methanol cross-over.
Although a Pt/C electrocatalyst is the most widely used cathode material, there is a great interest in the development of cost-effective, active and methanol tolerant electrocatalysts for the ORR. Promising results have been achieved by alloying Pt with non noble metals or by using Palladium. In the transition process from Pt to cheaper non Pt-group (NPG) metals or non-precious catalysts, Pd-based electrocatalysts appear as a proper compromise. Pd shows a suitable electrocatalytic activity for the oxygen reduction reaction, even though lower than Pt, whereas its cost is at present significantly lower than Pt and its reserves much wider. In this work, Pt-Co alloys and composite Pd-based electrocatalysts consisting of a surface layer of Pt (5% wt.) supported on a core Pd3Co1 alloy were prepared and investigated as cathode catalysts in direct methanol fuel cells.
The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2011-2014) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement DURAMET n°278054.
FA:P02 Spin-coated La0.8Sr0.2Ga0.8Mg0.2O3 Electrolyte on Infiltrated anodes for Biogas Utilization
Z. SALEHI1, I. LUISETTO2, F. BASOLI1, A. D'EPIFANIO1, S. LICOCCIA1, S. TUTI2, E. DI BARTOLOMEO1, 1Department of Chemical Science and Technology and NAST Center, University of Rome Tor Vergata, Rome, Italy; 2Department of Science, University of Rome "Roma Tre", Rome, Italy
Dense micrometric La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) films were deposited by spin-coating on porous LSGM scaffolds characterized by homogeneous pore structure. Porous anodes were infiltrated with aqueous nickel and nickel/copper nitrate solutions, dried and fired at 700°C. Homogeneous metal coating with proper interconnection was observed by SEM, chemical stability confirmed by XRD, and electrical characterization of anodic substrates was performed. Catalytic activity of different anodes was evaluated ex-situ in a quartz micro-reactor fed with CH4:CO2 mixture at range 650 and 700 °C. To investigate the redox properties of the metallic phases, the anodic substrates were subjected to redox ageing cycles and characterized by H2-TPR. Fuel cell tests and electrochemical impedance spectroscopy (EIS) were performed and discussed.
Acknowledgements: The financial support of the Italian Ministry for Education, University and Research (PRIN- 2010-2011-Prot. 2010KHLKFC) is gratefully acknowledged.
FA:P03 Copper Doped Lanthanum Strontium Ferrite as Cathode for La0.8Sr0.2Ga0.8Mg0.2O3
F. ZURLO1, E. DI BARTOLOMEO1, A. D'EPIFANIO1, V. FELICE2, I. NATALI SORA2, S. LICOCCIA1, 1Department of Chemical Science and Technologies & NAST Center University of Rome "Tor Vergata", Italy; 2INSTM R.U. and Department of Engineering, University of Bergamo, Dalmine, BG, Italy
A novel "cobalt free" cathode material with stoichiometric composition of La0.8Sr0.2Fe0.8Cu0.2O3 (LSFCu) specifically developed for La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) electrolyte was investigated.
LSFCu was prepared by sol-gel synthesis and its chemical stability in the presence of LSGM electrolyte was investigated by structural and morphological analysis.
The conductivity properties of LSFCu and LSGM dense pellets were investigated in the temperature range 500-750 °C by Van der Pauw dc measurements (four-probe technique) and electrochemical impedance spectroscopy (EIS).
LSFCu/LSGM/LSFCu symmetrical cells were prepared and Area Specific Resistance (ASR) values evaluated. Fuel cell tests and electrochemical impedance spectroscopy (EIS) were performed in the 500 - 750 °C temperature and compared to the results obtained for similar fuel cells prepared by using commercial La0.6Sr0.4Fe0.8Cu0.2O3 as cathode material.
Acknowledgements: The financial support of the Italian Ministry for Education, University and Research (PRIN- 2010-2011-Prot. 2010KHLKFC) and the support and collaboration of INSTM and of the Lombardy Region of 13-11-2012 (Project "Ferriti di lantanio per nuove Fonti di Energia", Ferriti-NFE) are gratefully acknowledged.
FA:P04 Biogas Reforming for Hydrogen Production for SOFCs Applications: Performance of Ni/La-C-O Catalysts
L. PINO, A. VITA, M. LAGANÀ, V. RECUPERO, CNR Institute of Advanced Technology for Energy "Nicola Giordano", Messina, Italy
Biogas, a renewable source of CH4 and CO2, was used for hydrogen generation by tri-reforming reaction. The reaction is a combination of CO2 reforming, steam reforming and partial oxidation of CH4 in a single catalytic step; the presence of steam can promote steam reforming and water gas shift reaction, reducing the problem of carbon deposition, occurring in dry reforming reaction, while the addition of O2 can make less endothermic the total process. Besides, the H2/CO ratio in the reformed gas can be ruled by altering the relative amount of reagents.
Several Ni/La-Ce-O mixed oxides, prepared by combustion synthesis were used as catalysts. The experimental tests, carried out with synthetic biogas at 800°C with a gas hourly space velocity (GHSV) of 30000 h-1, were aimed to study the influence of different parameters (amount of La doping, Ni load and feed composition) on the catalysts activity and stability. The synergic effect of nickel-lanthana-surface oxygen vacancies of ceria influences the samples activity.
FA:P05 Porous/Dense YSZ Layers for Prospective SOFC Processing
N. VITORINO1, C. FREITAS2, J.C.C. ABRANTES1, 2, J.R. FRADE1, 1DeMAC, CICECO, University of Aveiro, Aveiro, Portugal; 2UIDM, ESTG, Polytechnic Institute of Viana do Castelo, Viana do Castelo, Portugal
Solid oxide fuel cells and other multilayer systems require combinations of highly porous electrodes and dense electrolyte layers to promote triple phase electrochemical reactions. However, direct processing of those porous/dense interfaces may be prevented by reactivity between cell materials, decomposition or microstructural instabilities; this stimulated alternative approaches based on processing porous/dense bi- or multilayers of the solid electrolyte, for subsequent impregnation with the required electrocatalysts. The actual work relies on emulsification of YSZ suspensions to process highly porous layers with controlled and reproducible porosity, whereas highly concentrated suspensions are used for the dense layers. One adjusts relevant emulsification parameters and subsequent steps of drying and controlled conditions for elimination of the oil phase (during early stages of heat treatment) to match the sintering compatibility between porous and dense layers, and to design the microstructural characteristics of the highly porous cellular layer.
FA:P14 Electrical and Electrochemical Properties of La2-xCaxNiO4 and La2-xCaxNiO4-Ce0.8Sm0.2O1.9 as Cathode Materials for Intermediate Temperature SOFCs
E.YU. PIKALOVA1, A.A. KOLCHUGIN1, 2, N.M. BOGDANOVICH1, D.I. BRONIN1, 1Institute of High Temperature Electrochemistry, UB RAS, Yekaterinburg, Russia; 2Vitus Bering Kamchatka State University, Petropavlovsk-Kamchatskiy, Russia
Doped ceria based materials have been attracting increasing interest as electrolytes in intermediate temperature solid oxide fuel cells (IT-SOFC) due to their high ionic conductivity and catalytic activity to direct methane oxidation. Reduction operating temperature results in a decrease in the performance of cells, mainly due to relatively high resistance at the cathode-electrolyte interface. Ni-based layered perovskite compounds with considerable high mixed ionic-electronic conductivity and good mechanical compatibility with conventional electrolytes are promising candidates as cathode for IT-SOFC. The present work focuses on the electrochemical performance of La2-xCaxNiO4 (x=0-0.4) and La2-xCaxNiO4-Ce0.8Sm0.2O1.9 composites in contact with Ce0.8Sm0.2O1.9 electrolyte. Influence of the sintering temperature and introduction of the activating additives both into electrolyte and cathode material on the in-plane and polarization resistances was studied by the dc four-probe technique and impedance spectroscopy. The composite electrodes possess higher polarization resistance in comparison with basic nikelates. Application of a current collector made of LаNi0.6Fe0.4O3 substantially reduces polarization resistance facilitating more uniform current distribution along the electrodes.
FA:P15 Carbon Nanotubes Supported Iron Phthalocyanine- and Based Polyindole-based Electrocatalysts for Oxygen Reduction in DMFCs
M.T. NGUYEN, A. D'EPIFANIO, B. MECHERI, A. IANNACI, S. LICOCCIA, Dept. Chemical Science and Techology& NAST Center, University of Rome Tor Vergata, Italy
Novel electrocatalysts from iron phthalocyanine (FePc) and polyindole (PID) supported on carbon nanotubes (CNTs) have been synthesized for oxygen reduction reaction (ORR) in Direct Methanol Fuel Cell (DMFC).
Two synthetic strategies are proposed: i) preparation of PID on CNTs (PID/CNTs) through indole polymerization followed by the mechanical mixing of PID/CNTs with FePc (FePc_PID/CNTs); ii) dispersion of polymerized PID, FePc, and CNTs in methanol and subsequent drying (FePc/PID/CNTs). FePc/CNTs catalysts (without PID) were also prepared and used as reference.
The morphology of the prepared catalysts was examined by SEM, and electrochemical activity towards ORR was evaluated by cyclic voltammetry. PID-based catalysts showed a more positive ORR peak potential compared to that of reference FePc/CNTs, due to the presence of nitrogen heteroatom in PID which enhanced ORR activity. FePc/PID/CNTs catalysts were found to have higher activity than that of FePc_PID/CNTs, due to a better dispersion of PID and FePc on carbon support, as demonstrated by SEM.
Furthermore, the prepared PID-based catalysts exhibited a stable ORR potential in both H2SO4 and H2SO4/MeOH solution. These new iron-based catalysts are thus promising to substitute platinum/carbon black at the cathode side of DMFC.
The authors thank Ms C. D'Ottavi for her valuable technical support. The financial support of the Italian Ministry for Environment (MATTM, Project MECH2), the Ager Consortium (Project AGER, grant n° 2011-0283) is gratefully acknowledged
FA:P16 SPEEK / Functionalized Titanium Oxide Nanocomposite Proton Exchange Membranes
C. DE BONIS1, A. D'EPIFANIO1, B. MECHERI1, D. COZZI1, I. NICOTERA2, S. LICOCCIA1, 1University of Rome Tor Vergata, Rome, Italy; 2Department of Chemistry and Chemical Technologies, University of Calabria, Rende (CS), Italy
During the last decades, a wide range of hygroscopic metallic oxides have been embedded in polymer matrices with the aim to obtain composite membranes with improved performance in fuel cells, but the presence of scarcely conductive inorganic species can entail a decrease of the overall proton conductivity of the electrolyte.
In this work, two types of organically modified nanometric titania, TiO2_RSO3H and TiO2_ArSO3H, in which aliphatic or arylene chains bearing sulfonic acid groups are covalently bound to the oxide surface, were synthesized and used as fillers in sulfonated polyetherehterketone (SPEEK) nanocomposites to increase the proton conductivity of membranes avoiding their excessive swelling in fuel cell operative conditions.
The fillers were characterized by elemental analysis, Fourier transform infrared spectroscopy and thermogravimetric and differential thermal analysis. Ion exchange capacity and electrochemical impedance spectroscopy measurements demonstrated the effectiveness of the functionalization in producing species with increased proton conductivity.
Nanocomposites containing different amounts of TiO2_RSO3H or TiO2_ArSO3H and pure SPEEK membranes were prepared and characterized in terms of thermal stability, ion exchange capacity and electrochemical performance. Water and methanol transport behaviour of the membranes are also investigated using NMR methods conducted under variable temperatures.
The financial support of the Italian Ministry for University and Research under the framework of the PRIN 2010-11 project "Advanced nanocomposite membranes and innovative electrocatalysts for durable polymer electrolyte membrane fuel cells, NAMED-PEM"
FA:P17 Hydrogen Electrooxidation on PdM (M= Rh, Sn, Ru) Electrocatalysts for PEM Fuel Cells
F. TZORBATZOGLOU, A. BROUZGOU, P. TSIAKARAS, Department of Mechanical Engineering, School of Engineering, University of Thessaly, Volos, Greece
Τhe most commonly adopted electrocatalysts in H2-proton exchange membrane fuel cells (PEMFCs) are based on Pt. Due to its scarce world reserves and its high price, last decade many efforts have been made in eliminating the Pt of PEMFCs' electrocatalysts, focusing on the utilization of Pd based catalysts. In this study, (20 wt.%) PdM (M=Rh, Sn, Ru) electrocatalysts supported on Vulcan-72 were synthesized by a modified microwave assisted polyol method and tested towards H2 electrooxidation. The examined electrocatalysts were characterized by XRD, TEM, CV and RDE. According to CV, the electrocatalytic activity's order is: PdRh/C>Pd/C>PdSn/C>PdRu. According to RDE measurements the current density's order is: PdRh/C(3.0 mAcm-2)>Pd/C(2.7mA cm-2)>PdSn/C (2.4 mAcm-2)>PdRu/C(1.4 mAcm-2). The effect of temperature is also investigated. All the samples are compared with Pt/C similarly prepared.
F. Tzorbatzoglou, is grateful to the Research Funding Program: Heracleitus II, co-financed by the E.U (ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the NSRF. A.Brouzgou and P.Tsiakaras are grateful to the Research Program: R&D cooperation (Greece-China) 2012-2014.
FA:P18 Anionic Exchange Membranes for Fuel Cells Applications
L. PASQUINI1, 2, R. NARDUCCI1, 2, P. KNAUTH1, M.L. DI VONA2, 1Aix Marseille Univ., UMR 7246, Marseille, France; 2Univ. Roma Tor Vergata, Roma, Italy
The need for reduction of pollution has reinforced in the last 150 years the interest for Fuel Cells(FCs) as efficient and clean systems for the conversion of fuels into energy.
Especially polymer electrolyte alkaline fuel cells are very promising devices with fast fuel cell reaction kinetics and low expensive metal electrodes. Unfortunately anionic exchange membranes show low ionic conductivity and low stability. Furthermore the relations between conductivity, stability, ion exchange capacity (IEC) and water uptake have not been well clarified yet.
This poster will report the synthesis and the characterization of anionic membranes with different IEC based on PSU quaternized with various amines (trimethylamine, 1,5-diazabicyclo-[4,3,0]-non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,4-diazabicyclo[2.2.2]octane). By introducing a small percentage of PEEK, we also stabilized them via cross-linking reaction by simple thermal treatments.
The membranes were characterized by different techniques. TGA analysis showed that anionic exchange groups are stable until 300°C, while stability tests, water uptake and conductivity measurements, evidenced that the amines utilized, the degree of chloromethylation of the polymer and the presence of cross-link strongly influence the final result.
FA:P21 Development of a Subscale Hydrogen Generator Unit for SOFC as APU for Naval Applications
V. RECUPERO, L. PINO, A. VITA, C. ITALIANO, M. LAGANÀ, CNR Institute of advanced Technology for Energy "Nicola Giordano", Messina, Italy
This paper covers the activities performed at the CNR-ITAE aimed to develop a subscale hydrogen generator unit, in a power range until 1 kWe. The goal includes: develop fundamental understanding and technology in diesel fuel reforming for the production of hydrogen and support the development of auxiliary power units (APUs) in commercial diesel for naval applications.
The processing unit is able to convert dodecane as a diesel surrogate in syngas mixture, it is an integrated packed bed catalytic tubular reactor, filled with pellet catalysts; the Steam Reforming (SR) catalyst is a proprietary CNR-ITAE catalyst.
The experiments will regard the analysis of the followings:
- heat and mass balance of the prototype;
- optimization of start-up and shut down methodology (light-off temperature, start-up time, etc.);
- SR catalytic activity ( dodecane conversion, products distribution);
- SR catalytic stability (steady state regime, influence of frequent start-up and shut down cycles, etc.);
- carbon deposition phenomena;
- by-products formation;
- correct working of the control and check systems.
In the present paper the preliminary results of the unit are presented.
FA:P22 Ab-initio Simulation of Beta-Ta2O5 as a Catalyst for Oxygen Reduction Reaction
M.F. SGROI, V. DELLACÀ, Group Materials Labs, Centro Ricerche FIAT, Orbassano (TO), Italy
Cost and durability are key parameters for the development of cost effective and reliable commercial fuel cell systems. The widely applied catalyst employed in hydrogen fuel cells for the anode and cathode reactions is Pt, sometimes in combination with a second metal. Only a few elect-rocatalyst formulations, alternative to Pt, have been proposed for methanol electro-oxidation in acidic environment in the case of direct methanol fuel cells. Alternatively to platinum, organic transition metal complexes are known to be good electro-catalysts for the oxygen reduction reaction (ORR), and a promising noble metal free catalysts for oxygen reduction reaction (ORR) is partially oxidized tantalum carbo-nitride .
The present theoretical study is devoted to the ab-initio atomistic simulations of the electronic and catalytic properties of Ta-CNO. The computations were performed using Density Functional Theory with the QUANTUM ESPRESSO. Hybrid functionals were employed to correctly describe the electronic structure of the material. The presence of defects in the crystal was simulated to understand the effects of oxygen vacancies on the catalytic activity of the material.
 A. Ishihara et. Al, ECS Trans. (2008), 16 (2), 449-457.
FA:P23 Nobel-metal-free Anode Catalysts for Direct Methanol Fuel Cells
XIAODONG WANG, P. MADKIKAR, T. MITTERMEIER, M. PIANA, H.A. GASTEIGER, Institute of Technical Electrochemistry, Technical University of Munich, Garching, Germany
Transition metal carbides have been investigated as noble-metal-free electrocatalysts for methanol oxidation reaction (MOR) in acidic media, because of their Pt-like electronic properties and the possible resemblance to Pt as electrocatalysts. However, regarding the stability in acidic media, metal silicides are more promising materials. In this work, commercially available WSi2, MoSi2, TaSi2, NbSi2 and Ni2Si powders were used as starting materials for the potential anode catalysts. Prior to studies on catalysis, the size of the hard materials was reduced to the nanoscale by high-energy ball milling, and the resulted nanopowders were characterized in detail. The stability of the silicides in perchloric acid was investigated. An electrochemical cell was assembled for evaluation of the properties of the MOR catalysts in hot concentrated H3PO4, close to DMFC operating conditions (100 °C). First activity studies on the novel materials in comparison to Pt and WC were carried out.
The research leading to these results receives funding from the Fuel Cells and Hydrogen Joint Undertaking under Grant Agreement Duramet n°278054 as part of the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (FP7/2007-2013).