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Engineered Nano-scale Ceramic Supports For PEM Fuel Cells

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Engineered Nano-scale Ceramic Supports for PEM Fuel CellsEric L. Brosha, Anthony Burrell, Neil Henson, Jonathan Phillips, andTommy RockwardLos Alamos National LaboratoryTimothy Ward, Plamen AtanassovUniversity of New MexicoKarren MoreOak Ridge National LaboratoryFuel Cell Technologies Program Kick-off MeetingSeptember 30 – October 1, 2009Washington DCFuel Cell TechnologiesOperated by Los Alamos National Security, LLC for NNSAUNCLASSIFIED

Objectives Develop a ceramic alternative to carbon material supports for a polymerelectrolyte fuel cell cathode that exhibits an enhanced resistance to corrosionand Pt coalescence while preserving positive attributes of carbon such ascost, surface area, conductivity, and a compatibility with present MEAarchitecture/preparation.Goals high Pt utilizationenhanced Pt – support interactionhigh surface areaadequate electronic conductivityresistance to corrosionsynthesis method designed for scale-upFuel Cell TechnologiesOperated by Los Alamos National Security, LLC for NNSAUNCLASSIFIED

Technical Targets and BarriersDOE Technical Targets1,* Precious metal loading: 0.25 mg/cm2(with 0.05 mg/cm2 anode) Cost: 5 /kW Activity (precious-metal based catalyst):0.44 A/mgPt @ 0.90 ViR-free720 µA/cm2 @ 0.90 ViR-free Electrocatalysis support loss: 30 mV after 100 hrs @1.2V Electrochemical surface area (ESA) loss: 40%Technical Barriers Addressed2,*A.Durability (Pt sintering, dissolution, corrosion loss, effects from load-cycling & high potential)B.Cost (Better Pt utilization balanced by cost difference of new support)C.Electrode Performance (Pt sintering, corrosion loss, and loss of ESA)1. (Multi-Year Research, Development and Demonstration Plan, Table 3.4.12)2. (Multi-Year Research, Development and Demonstration Plan, Section 3.4.4 “Technical Challenges”)*From ypp/pdfs/fuel cells.pdfFuel Cell TechnologiesOperated by Los Alamos National Security, LLC for NNSAUNCLASSIFIED

Approach This Project: a focus on 3 ceramic materials as possible supports Rare-earth Hexaborides Sub-stoichiometric titania (TiO2-x) : Ti4O7 (Magnéli phase) Low work function materialRefractory – withstand high temperaturesInsoluble in acid mediaPresent use: abrasives and thermionic emittersBulk e- conductivity exceeds graphitized carbonReports of strong metal-support interactions with noble metalsHigh resistances to dissolution in acid mediaResistance to oxidationDemonstrated electro-catalytic activity for both hydrogen and oxygen / PtConductive metal oxides : NbO2 and RuO2 (UNM) Demonstrated corrosion stability (UNM)Highly dispersed Pt on conductive mesoporous spheres can be synthesized in asingle step process (UNM)Fuel Cell TechnologiesOperated by Los Alamos National Security, LLC for NNSAUNCLASSIFIED

Approach/Relevant Prior WorkGlassy carbon disk electrodes: bare, coated withYB6, and after spontaneous deposition of Au.CV performed on 4 wt%Pt/EuB6 powder-coatedelectrode with 6µg Pt/cm2loading immersed in 0.5MH2SO4, sparged with Ar.Metal hexaborides spontaneouslydeposit noble metals from solution.Pt, Au, Pd, Os, Ag, Ru, Rh, Ir ontoCa, Ce, Eu, Gd, La, and YB6LANL prepared 1 m2/gr EuB6 using BC andEu-acetate, 6hr @ 1500 C/H2 .F.A. Uribe, F.H. Garzon, E.L. Brosha, C.M. Johnston, S.D. Conradson, and M.S. Wilson, J. Electrochem. Soc. 154 (11) (2007)D623.Fuel Cell TechnologiesOperated by Los Alamos National Security, LLC for NNSAUNCLASSIFIED

Approach Microwave aerosol-through-plasma (ATP)torch synthesis of (RE)B6 and TiO2-x Polymer assisted deposition (PAD) for (RE)B6 PAD precursor routes to produce catalystssupports.Films (CVs), powders (bulk catalysts, MEA prep)Methods developed to generate surface areahave been demonstrated.Theory/Modeling support to aid experimentaleffort to prov

Engineered Nano- scale Ceramic Supports for PEM Fuel Cells. Eric L. Brosha, Anthony Burrell, Neil Henson, Jonathan Phillips, and Tommy Rockward. Los Alamos National Laboratory. Timothy Ward, Plamen Atanassov . University of New Mexico. Karren More. Oak Ridge National Laboratory. Fuel Cell