Delphi Technologies, Inc.

Battelle Memorial Institute

Joseph M Keller

Rick Daniel Kerr

William J LaBarge

Kailash Chandra Jain

Karl Jacob Haltiner, Jr

Subhasish Mukerjee

Robert J Svoboda

Gary F Reisdorf

Vincent L Sprenkle

Haskell Simpkins

Kerry D Meinhardt

Walter Thomas Symons

Su-Chee Simon Wang

Joseph V Bonadies

Diane M England

Kenneth Scott Weil

Bryan A Gillispie

Richard Frederick Beckmeyer

Nathan L Canfield

John S Hardy

David Thompson

Anthony J Derose

Carolyn D Fleming

Mohammad Parsian

Stefan M Maczynski

Steven L Cooper

Willem Vilders, Iii

A cathode of a solid-oxide fuel cell includes a first ionic conducting layer, a second layer deposited over the first layer and formed from a mixed ionic and electronic conductor layer including an oxygen ion conducting phase, and a third layer deposited over the second layer and formed from a mixed ionic and electronic conductor layer. A sintering aid and pore formers are added to the second layer and the third layer to establish ionic, electronic, and gas diffusion paths that are contiguous. By adjusting the microstructure of the second and the third layer, a high performance low resistance cathode is formed that bonds well to the electrolyte, is highly electro-catalytic, and has a relatively low overall resistance. By using inexpensive and readily available substances as sintering aid and as pore formers, a low-cost cathode is provided.

Low-temperature bonding of refractory ceramic layers

A solid state sintered material is described that includes a mixed oxide of lanthanum, strontium, cobalt, iron and oxygen, and CaCOinclusions. The solid state sintered material can also include calcium oxide, which can form from thermal composition of calcium carbonate. The solid state sintered material can also include a pore-forming particulate material such as carbon black and/or a doped ceramic metal oxide ionic conductor such as Sm-doped ceria uniformly dispersed in the solid state sintered material. The solid state sintered material can be formed from a two-step process in which a portion of the CaCOis mixed with the mixed oxide materials and heated to form porous agglomerates, and the remaining CaCOis added during the formation of a sintering paste. The solid state sintered material described herein can be used as a cathode material for solid oxide fuel cell.

Material for solid state sintered material

An improved LSCF 6428 perovskite material of the type LaSrCoFeOwherein x=0.4, z=(0-0.1), a=(0.01-0.04), and b=(0.05-0.15) for use as an SOFC cathode having increased electronic and ionic conductivity. The general formula is similar to the prior art formulae (LaSr)CoFeOand LaSrCoFeObut applies the z term to La and Sr independently as well as reducing the overall content of La. Further, by adding a small amount (a) of extra Co ions, catalytic activity, conductivity, and sinterability are further enhanced. Adding small amounts (b) of Fe and/or Fe and Co moderates the thermal expansion coefficient with no adverse effect on crystal structure or fuel cell performance. Improved sinterability, microstructure, and reduced film cracking result in high power density of fuel cells. An inherently low-cost solid state reaction method is described.

Perovskite materials for solid oxide fuel cell cathodes

A method for improving performance of an SOFC by impregnation of the cathode with metallic silver. A solution of AgNOin acetonitrile is imbibed into a perovskite cathode fabricated on a electrolyte layer supported by an anode, defining an SOFC cell. The cathode imbibition may be repeated a plurality of times as may be needed depending upon the thickness of the cathode. The amount of solution soaked into the cathode results a total final weight percent of Ag in the cathode between about 0.5% and about 10%. The cathode is then fired in air at high temperature to drive off the acetonitrile and to reduce the silver ions to metallic silver. In this way, cathode electrical resistance may be reduced by as much as 52%.

Method for impregnating a solid oxide fuel cell cathode with silver to reduce electrical resistance

During manufacture of an SOFC assembly, an inhibitor is included to prevent migration of silver braze during subsequent use of the SOFC assembly. The inhibitor may take any of several forms, either individually or in combination. Inhibitors comprehended by the present invention include, but are not limited to: a) a mechanical barrier that can be printed or dispensed onto one or more SOFC stack elements around the braze areas to prevent mechanically-driven migration; b) an electrically insulating feature in the electrolyte or interlayer over the electrolyte layer in the seal margins to prevent electrical potential-driven migration; and 3) chemical modification of the braze itself as by addition of an alloying metal such as palladium.

Inhibitor for prevention of braze migration in solid oxide fuel cells

In a solid-oxide fuel cell assembly comprising a plurality of components having electrically-conductive mating surfaces therebetween, the surfaces are sealed by an electrically insulating gasket that include a mineral composition comprising about 66 mol % MgO and about 33 mol % SiO, the mineral composition being known mineralogically as forsterite. A brazing alloy may be applied to enhance bonding of the gasket into place. The gasket composition may include additions of AlOto enhance electrical resistivity while having little to no impact of matching expansion coefficients of the gasket and metal mating surfaces. Also, additions such as titania or zirconia to inhibit glassy phase grain boundaries and the formation of impurities and pores in the ceramic grain boundaries may be used. A recommended particle size distribution of precursor powders is disclosed that leads to an optimum microstructure of the sintered gasket.

Compound for a solid oxide fuel cell stack gasket

An electrical interconnect for a solid-oxide fuel cell stack assembly, including a novel sintering paste and an improved manufacturing process for an anode and cathode electrical contacts is disclosed. On the anode side, the paste contains a metallic oxide such as NiO, and an amount of sacrificial pore-forming particles, such as carbon particles or polymer spheres, which are vaporized during sintering of the paste, resulting in a very porous connection having good electrical conductivity and good adhesion. A preferred level of pore-former in the paste is about 40 volume percent. On the cathode side, the paste contains a noble metal such as for example, gold, platinum, palladium or rhodium, and an amount of the sacrificial pore-forming particles. The paste may be applied to the surfaces in a grid pattern or, because the resulting contact is porous after sintering, it may be applied as a continuous layer.

Method and apparatus for forming electrode interconnect contacts for a solid-oxide fuel cell stack

In one embodiment, the method of producing a ceramic assembly includes: disposing an electrode precursor on an electrolyte precursor having an electrolyte sintering shrinkage, disposing a stabilizer precursor having a stabilizer sintering shrinkage on the electrode precursor on a side opposite the electrolyte precursor to form a precursor assembly, and sintering the precursor assembly to form the ceramic assembly comprising a stabilizer layer, electrode, and electrolyte. The difference between the electrolyte sintering shrinkage and the stabilizer sintering shrinkage is less than or equal to &#xb1;1% and a surface of the ceramic assembly has less than or equal to about 5.0 degrees camber, as measured from the horizontal plane.

Ceramic assembly with a stabilizer layer

In assembling an SOFC fuel cell stack from a plurality of cassettes, the mounting plate of one cassette is attached to, and insulated from, the separator plate of the next-adjacent cassette by a peripheral dielectric seal consisting of a ceramic coating and a metal braze. Materials suitable for the ceramic coating include yttrium stabilized zirconia (YSZ), zirconia toughened alumina, magnesium silicates such as the mineral forsterite, magnesium aluminates, magnesium aluminosilicates and lanthanum zirconate. The ceramic coating may be applied to the cassette's outer surface in known fashion as by physical vapor deposition, chemical vapor deposition, sputtering, and various methods of plasma spray. An underlayer of alumina may also be used to provide a redundant layer of electrical insulation.

Ceramic coatings for insulating modular fuel cell cassettes in a solid-oxide fuel cell stack

A catalyst for preferentially reducing carbon monoxide in a hydrogen stream. The catalyst is formed from a chemical composition including a hexaaluminate, a metal hydroxide and a precious metal. The composition may be disposed on a support or may be extruded or cast into or onto a support. Incorporation of hexaaluminates allows inclusion of metal hydroxides that flux the active precious metal surface at higher temperatures than can aluminum oxide-based catalytic compositions, thereby enhancing resistance of the catalyst and monolithic support and increasing the durability and thermal range of the PROX catalyst. An additional advantage is that lesser amounts of precious metal oxides need be deposited onto the hexaaluminate, while retaining activity similar to aluminum oxide compositions.

PROX catalyst for oxidizing carbon monoxide

A resistor seal composition useful in resistor spark plugs, comprises glass, at least one metal oxide, at least one filler material, and a branched or straight chained zirconium carboxylate. The glass comprises a strontium borate glass and/or a borosilicate glass. Metal oxides include aluminum oxide, zinc oxide, and zirconium oxide. Filler materials include silicon dioxide and mullite.

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Grand Blanc, MI, United States of America

Joseph M Keller