KR20070019648A - Electrochemical devices and components thereof - Google Patents

Abstract

At least one metal selected from the group consisting of copper, oxide dispersion strengthened copper, aluminum, titanium and alloys thereof, carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium diboride, hafnium Connecting material using a metal composite of at least one reinforcing material selected from the group consisting of diboride, tantalum diboride, titanium diboride, silicon dioxide, aluminum oxide, aluminosilicate, silicon nitride and aluminum nitride Is disclosed. The connecting material may be used as a component of the electrochemical device 1. The connecting member 14 may have a coefficient of thermal expansion within 10% of the coefficient of thermal expansion of the component or the assembly of the electrochemical device.

Description

ELECTROCHEMICAL EQUIPMENT AND THE COMPONENTS {ELECTROCHEMICAL DEVICES AND COMPONENTS THEREOF}

The present invention relates to an electrochemical device, and more particularly to an electrochemical device such as a fuel cell having a connecting material component including a metal composite material.

Electrochemical devices such as fuel cells can convert chemical energy into electrical energy. The conversion involves controlled oxidation of fuels such as hydrogen, hydrocarbons or modified hydrocarbons. The fuel cell assembly may comprise one or preferably a plurality of stacked cells. The fuel cell can isolate the anode and cathode with an electrolyte. The fuel cell may contain one or more connecting materials. Electrodes and electrolytes can be arranged in a conjugate. Such a conjugate is referred to as an electrode-electrolyte assembly (EEA), generally a solid oxide fuel cell, a cathode electrolyte cathode (PEN), and a membrane electrode assembly (MEA).

In particular, various approaches have been taken in attempts to develop components of these electrochemical devices, in particular connecting material. One approach relates to connecting materials containing ceramic materials and the other approach relates to connecting materials containing metallic materials. Some efforts have been made using metal composites.

US Patent No. 5,279,906 to Yoshimura et al. Discloses a connecting material for a solid oxide fuel cell. The connecting material consists of a mixture of a ceramic oxide and an alloy mainly composed of nickel and chromium in an amount of 50 to 85% by weight of the mixture.

US Patent No. 5,356,730 to Minh et al. Discloses a monolithic fuel cell. The interconnect layer composition comprises (i) a mixture of conductor and ceramic base material that can be sintered in an oxidizing atmosphere at temperatures below about 1500 ° C., (ii) a mixture of lanthanum chromium-based ceramics and yttrium chromium-based ceramics, or (iii) w About 0.9 to 1.1, x is about 0.1 to 0.3, y is about 0.001 to 0.1, z is about 0.1 to 0.3, and v is about 1 to 1.2 of Y _wxy Ca _x Zr _y Cr _vz Zn _z O ₃ Yttrium chromium-based ceramics may be mentioned.

Lessing's US Pat. No. 5,496,655 discloses a bipolar connector plate which is a catalyst for use in fuel cells. The plate is made from an intermetallic composition, examples of which include NiAl or Ni ₃ Al with ceramic fillers.

US Patent No. 6,051,330 to Fasano et al. Discloses a solid oxide fuel cell having a bias and a composite interconnect. The connecting material consists of a conductive alloy containing partially stable tetragonal zirconia and a superalloy resistant to redox conditions.

However, the related art has not gained the advantages and characteristics of the devices and methods of the present invention, and the components thereof.

According to one or more embodiments, the present invention relates to an electrochemical device. The device includes an electrode-electrolyte assembly and a connecting material in contact with the electrode-electrolyte assembly. The connecting material is at least one metal selected from the group consisting of copper, oxide dispersion strengthened copper, aluminum, titanium and alloys thereof, and carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium dibo At least one metal composite material of at least one reinforcing material selected from the group consisting of: lide, hafnium diboride, tantalum diboride, titanium diboride, silicon dioxide, aluminum oxide, aluminosilicate, silicon nitride, aluminum nitride and mixtures thereof Include.

According to one or more embodiments, the present invention relates to an electrochemical device. The electrochemical device includes a metal composite and an electrode-electrolyte assembly in contact with the metal composite. The metal composite material has a coefficient of thermal expansion of about 6 × 10 ⁻⁶ to 14 × 10 ⁻⁶ / ° C. and is within about 10% of the coefficient of thermal expansion of the electrode-electrolyte assembly.

According to one or more embodiments, the present invention relates to a method of generating electrical energy. This method comprises one or more metals selected from the group consisting of copper, oxide dispersion strengthened copper, aluminum, titanium and alloys thereof, carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium dibo Metal composites of at least one reinforcing material selected from the group consisting of: rides, hafnium diborides, tantalum diborides, titanium diborides, silicon dioxides, aluminum oxides, aluminosilicates, silicon nitrides, aluminum nitrides and mixtures thereof Providing a fuel and an oxidant to a fuel cell comprising a.

According to one or more embodiments, the present invention relates to a method for facilitating power generation. The method includes providing a fuel cell comprising an electrode-electrolyte assembly and a connector installed to contact the surface of the electrode-electrolyte assembly, the connector comprising copper or a copper alloy, silicon carbide, boron carbide, and aluminum. Metal composites of ceramics selected from the group consisting of oxides.

According to one or more embodiments, the present invention relates to a method of manufacturing a fuel cell. The method includes providing an electrode-electrolyte assembly and providing a coupling material comprising a metal composite having a coefficient of thermal expansion within about 10% of the coefficient of thermal expansion of the electrode-electrolyte assembly.

The invention is not limited to the application to the details of the formulation and structure of the components described in the following description or the drawings. The present invention can be implemented and practiced in other embodiments and in various ways. Also, the phraseology and terminology used herein is for the purpose of description and not of limitation. "Include", "constitution", "containing", "containment", and other uses include the items listed below and are the same in addition to the additional items.

According to one or more embodiments, the present invention relates to an electrochemical device or a stack or conjugate of electrochemical devices. The electrochemical device of the present invention may generally be a fuel cell capable of converting chemical energy directly into electrical energy. The fuel cell may be a molten carbonate fuel cell (commonly referred to as MCFC), a solid oxide fuel cell (commonly referred to as SOFC), or a proton conductive ceramic electrolyte. The electrochemical device may be an electrolysis device or an electrochemical gas separation device. The electrochemical device of the present invention usually operates in a temperature range of about 200 ℃ to 900 ℃.

In accordance with one or more embodiments, the present invention relates to a method of generating electrical energy using one or more electrochemical devices of the present invention. The method includes providing fuel and oxidant to at least one electrochemical device, preferably at least one electrochemical device comprises a metal composite.

According to some embodiments of the invention, in the example shown in FIG. 1, the bipolar planar stack 1 comprises a plurality of electrochemical devices or fuel cells 10. One or more fuel cells 10, which are a stack 1, may include an electrode-electrolyte assembly (EEA) 12 and a connector 14 that is typically in electrical, thermal and / or structural contact with the EEA 12. Can be. The EEA 12 typically includes an electrolyte 16 installed in electrical and ionic contact with the anode 18 and the cathode 20.

The linker 14 typically includes features such as promoting or sending fuel or oxidant to react in the EEA 12 by the channel 22. The connecting member 14 may provide or send electrical energy generated by a current collector to a load (not shown) during operation of the electrochemical device 10. In this case, the connecting member 14 may have a sheath (not shown) installed on the surface adjacent to the interface 22 having the EEA 12. Lower or intermediate layers (not shown) may be used between the coating and the surface of the connecting material.

The connecting material is thermomechanically stable for its shape, typically at room temperature, or during its service life, for example at least about 5,000 hours, in some cases at least about 40,000 hours, in other cases at least about 80,000 hours, during initial startup or initial operation. Do. The connector is chemically stable and at least partially corrosion resistant in the working environment. The linking material is a material or mixture of materials, which provides an acceptable, preferably negligible creep, and which is electrically conductive, thermally conductive and does not penetrate chemical reactants and / or products, such as fuels, oxidants and water, or Alloys, preferably non-intermetallic materials. Typically, the linking material is at least 70%, at least in some cases at least about 80%, in other cases at least about 90%, and even other cases of at least a portion of the components or conjugates of the electrochemical device through the operating conditions or through the operating conditions thereof. Materials, mixtures of materials, alloys and / or composites that provide a coefficient of thermal expansion (CTE) of at least about 97.5% or about the same. In addition, the linker may have a CTE that is within about 20% of the CTE of the component or conjugate of the electrochemical device, usually within about 10%, preferably within about 10%, more preferably within 2.5%. According to one or more preferred embodiments, the connecting material has an electrical resistance of less than about 30 milliohms-cm in a temperature range of about 0 ° C., or more about-40 ° C. to about 900 ° C., typically between 200 ° C. and about 900 ° C., In some cases, it may include one or more materials of less than about 20 milliohms-cm, in other cases less than about 10 milliohms-cm, and in other cases less than about 5 milliohms-cm. According to a further embodiment, the connecting material may comprise a material having a lower density than steel, nickel alloys and / or superalloys. The linking material may comprise one or more materials having high thermal conductivity that reduce the likelihood or importance of thermal gradients in the electrochemical device or components thereof. For example, the connecting member may have a thermal conductivity of at least about 50 W / mK, in some cases at least about 100 W / mK, in other cases at least about 125 W / mK, in other cases at least 150 W / mK, Preferably it is 200W / m * K, More preferably, it is 220W / m * K.

The material composition of the linker may be chosen to match or have a matching CTE profile, temperature component of the electrochemical device, or CTE profile of the conjugate, for example to an acceptable or within a predetermined deviation or tolerance. The material composition can be selected by equally lowering or further eliminating relative motion, and by lowering the relative motion between adjacent components that may be related to or relative to the relative motion and which may reduce certain defects as a result of relative motion. As such, the material composition of the linker may choose to reduce or further eliminate any pressure or related modifications between components in the electrochemical device during operation and / or circulation thereof.

The material of the connecting material can be identified and selected by identifying the target CTE of the components of the connecting material, describing the relative amounts. Estimating the CTE of the composite material of the present invention includes, for example, the laws of the mixture and Schapery, Kerner and Turner (see, for example, RA Schapery, "Thermal expansion coefficients of composite materials based on energy principles", Journal of Composite Materials, 2, 380-404 (1968), by using a suitable model, including a model based on progress. The law of the mixture model is based on the assumption that two phases do not interact basically. Turner's model assumes that phase 2 can be the same local volumetric deformation. Lower and upper chapery (Kerner) models are based on elastic energy principles. The Kerner model achieves a complex action when segregated particles are surrounded by adjacent matrices when the two phases are elastically deformed. The composition of the material of the present invention can be derived by using these models to obtain a composite having a target or desired CTE. For example, referring to Figures 2A-2C, the composition of the Cu / SiC composites of the present invention having a target CTE of about 14x10 ^-6 / ° C ranges from about 65 to 80% by volume of copper and about 20% of silicon carbide. In the range of ˜35 volume percent (FIG. 2A); Similarly, the Cu / B ₄ C composite of the present invention has copper in the range of about 65 to 80% by volume and boron carbide in the range of about 20 to 35% by volume, and Cu / Al ₂ O ₃ of the present invention has about 55% of copper. It is in the range of -75% by volume and about 25-45% by volume of aluminum oxide (Figure 2C).

The connecting material is at least one continuous phase, usually a metal, and the reinforcement phase may typically comprise a ceramic or metal composite of the metal. The reinforcement phase may be continuous or discontinuous. The metal may be selected from the group consisting of copper, aluminum, titanium and alloys thereof. In some cases, the metal may be a tempered metal, such as an oxide dispersed tempered glass, but is not limited thereto. Reinforcement phases are carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium diboride, hafnium diboride, tantalum diboride, titanium diboride, silicon dioxide, aluminum oxide, aluminium No silicate, silicon nitride, aluminum nitride and mixtures thereof. In some cases, the linker material is characterized by a metal / ceramic composite distinguishable from those containing ceramics, usually metals, with conductive inclusions or vias, the latter containing no thermo-mechanical functions. . The metal connecting material having the ceramic protective film can be distinguished from the metal / ceramic composite of the present invention because the composition cannot be matched in obtaining the target physical properties such as electrical, chemical, thermal and / or mechanical properties of the bulk substrate.

According to a further embodiment of the invention, the material of the composition may vary with respect to the geometric arrangement. For example, the amount of reinforced ceramic material dispersed in a metal or metal alloy continuous phase may vary depending on the relationship of distance from the surface of the connecting material. As such, the linker can increase or further reduce the ceramic component density toward the center of the linker in the metal composite. Similarly, it may have a density of various ceramic components with respect to the distance from the outer end to the center. For example, the connecting material may have a higher ceramic component for the area facing the center of the connecting material. Changes may be continuous in the case of providing gradual changes, eg ceramic component contributions, and discontinuous in the case of providing stepwise or gradual changes.

According to further embodiment of this invention, a connection material can use a 1st metal, a 2nd metal, and its alloy. For example, the connecting material may be substantially along the first metal in the first region, for example along its outer end, in the second region in the second metal, for example its center, and between the first region and the second region. It may have an alloy of the first and the second metal.

According to a further embodiment of the present invention, the connecting material may comprise one or more types of ceramic components having a plurality of types of ceramic components, a plurality of geometric arrangements, a plurality of metal components or a combination thereof. As such, for example, the connecting member may have a metal alloy having a first metal or first metal component along or in the region of the outer end, or a metal alloy having a second metal or second ceramic component in the center or middle third region. have. Likewise, the connecting member may have a first ceramic component, a conventional metal or a metal alloy along or near the outer end and have a second ceramic component in its central region.

According to some embodiments, the metal composite of the present invention comprises about 20-80% by volume copper or copper alloy and about 20-80% by volume silicon carbide, in some cases about 40-60% copper and about 40-60% silicon carbide. %, In other cases about 45% copper and about 55% silicon carbide. According to another embodiment, the metal composite of the present invention comprises 20 to 80% by volume copper or copper alloy and 20 to 80% by volume boron carbide, in some cases 45% by volume copper and about 55% by volume boron carbide. According to a still further embodiment, the metal composite of the present invention may comprise 20 to 80% by volume of copper or copper alloy and about 20 to 80% by volume of aluminum oxide.

According to one or more preferred embodiments of the present invention, the linker comprises about 30-80 volume percent copper / silicon carbide, boron carbide, or about 20-70 volume percent alumina. Copper includes, but is not limited to, substantially pure copper, oxide dispersed strengthening copper, highly conductive copper or copper alloys free of oxygen, such as Cu—Ni, Cu—Si, and Cu—Fe alloys. Reinforcing materials such as silicon carbide, boron carbide and / or alumina may be present in particles, aggregates, aggregates, continuous and / or discontinuous fibers, polymeric structures, nanotubes or combinations thereof. In addition, the reinforcement may have a suitable or desired size. For example, the particles may have a largest size of less than about 1 μm, or even less than about 10 μm, and in other cases the particles have a size of about 40-60 μm, and in other cases about 100 μm. In addition, the particles may have a variety of size gradients, for example the particle size gradient may be polymodal, such as bimodal, trimodal or modal of 4 or more, wherein the statistical gradient of particle size is determined by a particular peak. It can be characterized.

The present invention shows a material having a high thermal conductivity while matching a coefficient of thermal expansion so as to have a difference within an acceptable tolerance with a component or a conjugate of an electrochemical device such as an EEA of SOFC. Thus, for example, the material of the invention can be used in consolidated having a CTE in the range of about 9.5 × 10 ^-6 /℃~12.5×10 ^-6 / ℃ by matching the CTE of the EEA. In some cases, the material may have high conductivity compared to conventional materials of the compositions used in fuel cells. As shown in Table 1, the representative metal composites (Cu / SiC having different compositions) of the present invention have excellent thermal conductivity. As such, for example, the CTE of a Cu / SiC composite can be selected to match the amount of copper and the amount of silicon carbide to be within the desired range.

Table 1. Consideration of physical properties and expected range of physical properties of common connecting materials (E-excellent, M-suitable, P-bad)

material CTE × 10 ^-6 / ℃ Electrical resistance μohm-cm Thermal Conductivity W / mK La _0.8 Ca _0.2 CrO ₃ La _0.7 Sr _0.3 CrO ₃ E 9.5-10.5 M 40-60 P 2-4 Ni superalloy P 14-19 E 100-130 M 17-30 Ferrite steel M 11.5-14.5 E 60-120 M 20-40 High CrODS Alloy E 11-12.5 E ~ 30 M to 40 Cu / SiC composites (expected range of 30 to 60% by volume copper) E 9-15 E 5.3 to 2.3 E 100-220

Metal composites can be prepared by known methods that can provide a metal matrix having at least one continuous phase and at least one discontinuous phase. Typically the continuous phase comprises one or more metals or metal alloys. The discontinuous phase typically comprises one or more reinforcing materials, such as one or more ceramics. For example, the metal composite material can be produced by a liquid phase method such as impregnating casting of a porous material preform by a solid metal process, powder metallurgy such as forging, or a molten component. In the forging process, the homogeneous mixture, for example the powder particles of the metallic matrix and the reinforcing material, is cold pressed to a thermally metallized green portion at an appropriate high temperature and under pressure to form a dense composite. Typically this method is carried out at a temperature below the solidus temperature of the metal matrix. Forging is preferably performed at low or minimum exposure temperatures to reduce the possibility of interfacial reactions between the ceramic particles and the metal matrix. As such, according to one or more embodiments of the present invention, a Cu / SiC composite may be produced by forging at less than about 900 ° C. in a uniform or homogeneous microstructure with little or no pores. In the liquid impregnation casting method for liquid metal or pressure impregnation method, stable preforms such as porous ceramics are usually formed and machined as necessary. Molten metal can be introduced into the preform under pressure. This facilitates the liquid metal impregnation into the ceramic to produce the pore free component. For example, the components of the present invention can be prepared by infiltrating SiC preforms into liquid copper.

Porous ceramic preforms are harder or denser by sintering to create a lattice network of strongly bonded ceramic particles. Composites prepared by suction casting of the sintered preforms may be expected to have better creep resistance compared to conventional green grain preforms. The sintering time and temperature depend on various factors such as, but not limited to, the ceramic form, the size of the preform, and / or the degree of material rearrangement desired. The sintering method can be carried out on a ceramic material such as SiC at a temperature in the range of 1700 ° C to 2300 ° C. Sintering can be carried out at a sintering temperature for a sufficient duration. For example, sintering may be performed for about 1 hour to about 12 hours.

The connecting material may have one or more coatings or layers on at least a portion of one or more surfaces. As such, for example, the connecting member of the present invention may comprise a metal composite material having a coating on at least a portion of its surface. The coating can comprise a suitable material that can provide substantially pore or impermeable, conductivity, and preferably provide oxidation or degradation protection. Preferably the coating does not penetrate the oxidizing agent and / or reducing agent at the operating or service temperature of the connecting material. The sheath may be chosen to provide an Area Specific Resistance (ASR) between the EEA and the sheathed connection material of less than about 0.1 ohm-cm ² . As such, for example, the coating may have a conductivity of at least about 1 S / cm; The CTE is within about 80%, preferably within about 10%, more preferably within about 5% of the CTE of the interconnect material; And / or the thermal conductivity may be at least one material or compound of at least about 5 W / m · K, preferably at least about 10 W / m · K, more preferably at least about 100 W / m · K. Non-limiting examples of materials or compounds that may include coatings include conductive oxides, chromite, nickel oxides, doped or undoped lanthanum chromite, manganese chromite, yttria, lanthanum strontium manganite (LSM), In addition to noble metals such as lanthanum strontium chromite, platinum, gold and silver, mixtures other than nickel and copper, doped or undoped conductive perovskite, manganese chromite, lanthanum strontium cobalt oxide, zirconium diboride, titanium silicon carbide Or combinations thereof, but is not limited thereto. Usually, the coating is applied to be as thin a film as possible while maintaining sufficient density to provide the desired protective ability and / or to deteriorate adverse or undesirable properties such as resistance. For example, the coating may be less than about 50 μm thick, in some cases less than 25 μm, in other cases less than 10 μm, and in other cases less than 5 μm. Coating materials are commercially available from NextTech Materials, Ltd., Lewis Center, Ohio, Praxair Specialty Ceramics, Woodinville, Washington and Trans-Tech, Inc., Adamstown Maryland, for example.

The coating can be applied by any suitable method, such as, but not limited to, deposition, screen printing, fluid bed immersion, plasma coating, spray coating, magnetron sputtering, and / or dip coating. For example, the coating may be coated with a (La _0.8 Sr _0.2 ) _0.9 MnO ₃ powder having a particle size of less than 25 μm to a thin film while providing the desired protective performance by means of plasma spraying with an Ar flame. It can be coated on the surface.

According to a further embodiment of the invention, the underlayer can be disposed between the coating and the surface of the connecting material. The underlayer may be at least partially disposed, preferably via the interface between the sheath of the connecting material and the contact surface. In some cases, the underlayer may serve as an additional barrier layer between the metal composite of the connecting material and the environment of the electrochemical cell. Desirably, if the underlying layer is not separated, it may interfere with the undesirable or undesirable reaction between the connecting material and the coating. It is contemplated that the present invention uses one or more underlayers disposed on one or more portions or regions between the sheath and the interconnect material surface. As such, one or more regions may or may not have an underlayer or one or more regions may differ from the underlayer composition. The underlayer may have a desired thickness to provide conductivity and / or thermal conductivity. Usually, the underlayer is applied so as to be as thin as possible while maintaining sufficient density to provide the desired protective ability and / or to deteriorate adverse or undesirable properties such as resistance. For example, the lower layer may have a thickness of less than about 1 μm, in some cases less than 0.5 μm, and in other cases less than 0.1 μm. The underlayer can be applied by any suitable method such as physical or chemical vapor deposition, fluidized bed immersion, plasma coating or the like, but is not limited thereto. The underlayer includes, but is not limited to, titanium nitride, titanium aluminum nitride, titanium silicon carbide, or mixtures thereof.

The metal composite may have one or more surfactants that can promote or provide for forming a bridge between the discontinuous phase reinforcement component and the metal or metal alloy continuous phase. The surfactant can be coated as an interfacial layer that facilitates adhesion of ceramic particles to the metal or metal alloy matrix. In some cases, the surfactant or interfacial layer may wet the surface of one or more fillers or additives or the like blended into the metal or metal alloy matrix. Metal composites can be prepared by exposing the ceramic filler to one or more species or reactants capable of forming carbide, nitride, oxide or combinations thereof. In some cases, the surfactant may include, but is not limited to, reactive metals such as titanium, lanthanum, cerium, yttrium, silicon, vanadium, iron, and combinations thereof. The interfacial layer formed can form a bond between a continuous phase, such as a metal or metal alloy matrix, and a discontinuous phase, such as a filler, to minimize defects present or created at this interface. Typically, the reactive metal chooses to react or to form an alloy with one or more components of the metal composite and / or coating. The amount of surfactant is usually as low as possible to provide wetting, control of the chemistry of the interface and optimization of the composite properties, and less than about 5% by volume, less than about 2%, and in some cases about 1% of the metal composite or metal in the metal composite. Can be less than%.

According to one or more embodiments of the present invention, it consists essentially of or consists of a copper or copper alloy and a ceramic selected from the group consisting of silicon carbide, carbon, graphite, titanium boride, titanium carbide, boron carbide, aluminum oxide, or mixtures thereof. Can be.

According to another embodiment of the present invention, the electrochemical device may contain a connecting material including a metal composite material. The metal composite may consist essentially of the continuous phase metal and the ceramic in discontinuous phase. The ceramic may basically consist of carbide, diboride, oxide, dioxide, silicate and nitride. For example, ceramics are carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium diboride, hafnium diboride, tantalum diboride, titanium diboride, silicon dioxide, aluminum oxide , Aluminosilicate, silicon nitride and aluminum nitride.

However, according to another embodiment of the present invention, the connecting member is made of or consists essentially of a ceramic selected from the group consisting of nonmetals or metal alloys and silicon carbide, carbon, titanium boride, titanium carbide, boron carbide, and aluminum oxide. Also good. The coating is a group of doped or undoped conductive perovskite, lanthanum chromite, manganese chromite, yttria, lanthanum strontium cobalt oxide, lanthanum strontium manganite, lanthanum strontium chromite, precious metals, nickel and copper It may consist of or necessarily consist of a compound selected from. The lower layer may consist essentially of or consist of a compound selected from the group consisting of titanium nitride, titanium aluminum nitride, titanium silicon carbide or mixtures thereof.

EEA can be used in the present invention. For example, the EEA can include an anode, an electrolyte and a cathode. The anode may include materials that support or promote fuel oxidation, such as a ceramic alloy having a continuous phase ceramic phase and a discontinuous metal phase such as Ni / YSZ (nickel / yttria stabilized zirconia) and usually having about 40% pores. have. The electrolyte may comprise an oxygen conductive ceramic such as dense YSZ having less than about 1% of pores. The cathode may comprise a material that promotes oxidant reduction, such as lanthanum strontium manganite, which typically has about 40% of pores. Electrode-electrolyte conjugates are commercially available, for example, Innovative Dutch Electro Ceramics (InDEC B.V.), Netherlands and NexTech Materials, Ltd., Lewis Center, Ohio.

The present invention may use one or more binders to ensure or at least facilitate structural support between electrical and / or heat transfer, and / or components of the stack. For example, a binder may be placed on the EEA / connector surface 22 to reduce separability. Examples of binders include, but are not limited to, Ag / CuO / TiO ₂ , Ag / CuO, Ag / TeO ₃ , Pt / Nb ₂ O ₅ (pastes) and Ag (pastes). The choice of form of binder may depend on a variety of factors, such as chemical or thermo-mechanical stability, desired mechanical and thermal properties, for other component materials.

According to one or more embodiments, the present invention relates to a method for facilitating power generation. The method includes providing a fuel cell comprising an EEA and a connector disposed in contact with the surface of the EEA, the connector being a ceramic selected from the group consisting of copper or copper alloys and silicon carbide, boron carbide and aluminum oxide. Metal composite material.

The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component described in various figures is represented by the same numeral. For clarity, not all components may be shown in all figures. In the drawing:

1 is a schematic diagram of a stack including a plurality of electrochemical devices having components in accordance with one or more embodiments of the present invention.

Figures 2A-2C show the coefficient of thermal expansion (CTE) for the particle or reinforcement volume fractions of Cu / SiC composites (Figure 2A), Cu / B ₄ C composites (Figure 2B), and Cu / Al ₂ O ₃ composites (Figure 2C). It is a graph which shows, and the CTE value of the sample manufactured in heating "▲" and cooling "●" is measured.

Figure 3 shows the SiC particle size in the range of about 10 to 20 μm (left), about 40 to 60 μm (right), about 40% by volume (bottom), about 47.5% by volume (middle), and 55% by volume (top) A photomicrograph of the Cu / SiC composite sample of the present invention is shown.

4 shows micrographs of the Cu / SiC composite (top), Cu / Al ₂ O ₃ composite (middle) and Cu / B ₄ C composite (bottom) of the present invention.

5 is a graph showing measured CTE (about 200-800 ° C.) of the forged Cu / SiC composite of the present invention against theoretical CTE values.

6 is a schematic diagram of a simulated SOFC to analyze the effect of thermal conductivity of a material on system performance.

7 is a graph showing simulation results for estimating power density by the action of the thermal conductivity of the connecting member of the present invention.

The functions and advantages of these and other embodiments of the present invention can be further understood from the following examples. The examples may illustrate the advantages and / or advantages of the articles, components, systems and methods of the invention, but do not exemplify the full scope of the invention.

Example 1 Preparation of Cu / SiC Materials by Solid Powder Forging

The metal composite material of the Cu / SiC sample was produced at a temperature of 20 to 800 ° C. with a high-molecular powder forged to have a target CTE of about 12.1 × 10 ⁻⁶ / ° C. In FIG. 2A, the target composition range of Cu / SiC is described as about 40 to 60 volume percent copper and about 40 to 60 volume percent silicon carbide. Thus, with respect to the amount of copper (about 60% by volume, about 52.5% by volume, about 45% by volume), silicon carbide contained about 40% by volume, about 47.5% by volume and about 55% by volume (about 19.3% by weight, about 24.5% by weight). And about 30.5% by weight). In addition, silicon carbide having particle sizes of about 10 μm to about 20 μm, about 40 to 60 μm, and about 100 μm was used for each of the three silicon carbide content levels. Copper having a particle size of about 10-15 μm was used for a 15 μm (10-20 μm) SiC sample; Particle size copper of about 30-35 μm was used for a 50 μm (40-60 μm) SiC sample; Copper with a particle size of about 75 to about 100 μm was used for the 100 μm SiC sample.

SiC particles were coated with a thin film layer of copper through a vapor phase process. The coated SiC particles are combined with the copper particles to homogeneously disperse, cold compress the plate, and then forge at a temperature of less than about 900 ° C. for less than about 1 minute.

3 is a micrograph of some of the prepared samples; Micrographs can be made by forging a Cu / SiC composite to have a continuous phase (bright area) that is reinforced with discontinuous phase (dark area).

Example 2. Fabrication of Cu / SiC, Cu / B ₄ C, Cu / Al ₂ O ₃ , Materials by Impregnation Casting

Metal composite samples of Cu / SiC, Cu / B ₄ C, and Cu / Al ₂ O ₃ were prepared by impregnation casting. Each sample had about 55% reinforcement, SiC, B ₄ C or Al ₂ O ₃ . Porous preforms were prepared by slurry casting or injection molding. Suction casting of this preform was carried out in molten copper under an inert atmosphere (argon).

4 is a micrograph of the prepared sample; The micrograph shows that Cu / SiC, Cu / B ₄ C, and Cu / Al ₂ O ₃ composites are produced by casting to have a uniform gradient of reinforcement on a continuous metal phase (bright areas).

Example 3 Analysis of Cu / SiC, Cu / B ₄ C, Cu / Al ₂ O ₃ Materials

CTE measurements (ASTM E228) were performed with each impregnated cast sample prepared as substantially described in Example 2. CTE measurements were performed by heating to about 20-800 ° C. and cooling to about 20 ° C. The measured heating cycle CTE and the measured cooling cycle CTE are shown in FIGS. 2A-2C for Cu / SiC, Cu / B ₄ C and Cu / Al ₂ O ₃ samples.

The results shown in FIGS. 2A-2C show that the measured CTE correlates closely with the law of the mixture model (CTE measured during heating "▲" and cooling """). The measured CTE value was obviously within about 2.5% of the target CTE (12.1 × 10 ⁻⁶ / ° C.).

Some formed Cu / SiC samples show interfacial layers not observed in Cu / Al ₂ O ₃ samples. The thermal aging test was performed by thermal immersion of Cu / SiC, Cu / B ₄ C and Cu / Al ₂ O ₃ samples at about 800 ° C. for about 100 hours in an inert atmosphere. SEM observations of the absorbed samples show no degradation at the metal-ceramic interface.

Example 4. Effect of Particle Size

Forged Cu / SiC composite samples (47.5% by volume of SiC) were prepared using SiC having a particle size of about 15 μm and about 50 μm substantially by the forging method described in Example 1.

The CTE of the sample was measured and is shown in FIG. 5 (target CTE between about 20 ° C. and about 800 ° C.). This result closely matches the EEA target CTE (approximately 12.1 × 10 ⁻⁶ / ° C.), but samples with smaller particle sizes than the reinforcement particles correlate more closely than samples with larger particle sizes. Indicates.

Example 5. Expected SOFC Performance

The advantage of connecting materials comprising high thermal conductivity, material of at least about 100 W / mK is that the components of the electrochemical device have a more uniform temperature gradient, which improves the power density of the stack and the thermo-mechanical pressure associated with the electrode electrolyte assembly. Can be reduced. By using a connector material having high thermal conductivity, it is possible to provide an SOFC power system having a high energy conversion efficiency and a low cost as compared to a system similar to that of a connector material having low thermal conductivity. In addition, materials with high thermal conductivity can reduce the required airflow to cool the stack and consequently reduce the power loss of the associated vortex. High stack power density can reduce the cost associated with the stack material because the amount of stack material required is typically approximately inversely proportional to the stack power density.

To analyze the effect of thermal conductivity on stack power density, numerical simulations were performed. Specifically, the performance of the anode supported SOFCs schematically shown in FIG. 6 was simulated (FIG. 6 shows the geometry of the simulated SOFCs, the coflow rearrangement of the reactant gases). The simulation model used software developed using finite element analysis principles. The simulation model is described in the report "Structural Limitations in the Scale-up of Anode Supported SOFCs," published in the US Department of Energy, NETL, October 2002. This model was developed in anticipation of the temperature gradient, current density, species concentration, and thermo-mechanical pressure of the operating SOFC space.

SOFC is modeled to operate at 0.7V, about 85% of natural gas fuel reformed to inert gas temperature of 550 ° C and exhaust gas of about 700 ° C, the contact resistance at the connector / EEA interface is about 0.1ohm-cm ² , In order to maintain the exhaust gas temperature at about 700 ℃, the air flow rate required for the electrochemical reaction was evaluated to 700% or more.

It has been found that the injection and exhaust gas temperatures are consistent with system level energy balance issues. The results shown in Figure 7 represent the associated expected power densities. The model results are higher power density because they find that by increasing the thermal conductivity of the interconnect material, the temperature gradient through the cell is reduced, and that more effective cell temperatures improve conversion dynamics and reduce resistive losses.

As such, the use of metal matrix components with high thermal conductivity in the present invention increases power generation. In addition, the modeling results confirmed that the use of high thermal conductivity interconnect materials in SOFC applications improves the overall system efficiency, since the flow loss associated with cooling airflow can be reduced in high power density systems.

Since the described embodiments of the present invention have been described, it is obvious to those skilled in the art only by way of example and not by way of limitation. Numerical limitations and other described embodiments are contemplated within the scope of this invention and are within the scope of common knowledge.

While the embodiments shown herein relate to particular combinations of method acts or system elements, it should be understood that acts and elements may be combined in other ways that perform the same purpose. The actions, elements, and features described for one embodiment are not intended to be excluded from similar roles in the other embodiments. Various changes, modifications, and improvements may be readily made by those skilled in the art, and such changes, modifications, and improvements are within the scope of the description and are within the spirit and scope of the invention. For example, using other models may be used in the present invention to provide a composition for estimating CTE and / or obtaining a target CTE. Moreover, the present invention is directed to the combination of two or more of each feature, system, subsystem, or method, feature, system, subsystem, or method described herein, provided that these features, systems, subsystems, and methods do not match each other. Combinations of two or more of the features, systems, subsystems, and / or methods are considered and are considered within the scope of the invention as set forth in the claims. The use of common terms such as "first", "second", "third", etc. in a claim to modify the elements of a claim is itself a claim over the superiority, precedence or other in which the method is practiced. It does not imply an order of elements or a temporary order, but is used only as a label to distinguish one claim element with a particular name from another element with the same name (usually in terminology) to distinguish the claim element. In addition, "plurality" as used herein means two or more. As used herein, “set” includes one or more such items.

Those skilled in the art should appreciate that the variables and arrangements described herein are exemplary and that actual variables and / or arrangements may vary depending upon the particular use of the systems and methods of the present invention. Those skilled in the art can recognize or confirm that they are only regular experiments and correspond to specific embodiments of the invention. The embodiments described herein are merely within the scope of the appended claims and represented by the corresponding examples, and the invention may be practiced otherwise than as specifically described.

Claims (42)

Electrode-electrolyte conjugates; And A connecting material in contact with said electrode-electrolyte assembly; The connecting material is at least one metal selected from the group consisting of copper, oxide dispersion strengthened copper, aluminum, titanium and alloys thereof, and carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium dibo At least one metal composite material of at least one reinforcing material selected from the group consisting of: lide, hafnium diboride, tantalum diboride, titanium diboride, silicon dioxide, aluminum oxide, aluminosilicate, silicon nitride, aluminum nitride and mixtures thereof Electrochemical equipment comprising a. The electrochemical device of claim 1, further comprising a coating on the surface of the connecting material. 3. The electrochemical device of claim 2, wherein the coating comprises a conductive material free of pores. 3. The electrochemical device of claim 2, wherein the coating comprises at least one material selected from the group consisting of lanthanum strontium manganite, lanthanum strontium chromite, precious metals, nickel and copper. 5. The electrochemical device of claim 4, further comprising a lower layer disposed between the sheath and the surface of the connecting material. 6. The electrochemical device of claim 5, wherein the lower layer comprises a conductive material selected from the group consisting of titanium nitride, titanium aluminum nitride, or mixtures thereof. The electrochemical device according to claim 1, wherein the connecting material has a coefficient of thermal expansion within 20% of the coefficient of thermal expansion of the electrode-electrolyte assembly. 8. The electrochemical device of claim 7, wherein the connecting material has a coefficient of thermal expansion within about 10% of the coefficient of thermal expansion of the electrode-electrolyte assembly. 9. The electrochemical device of claim 8, wherein the linking member has a coefficient of thermal expansion within about 5% of the coefficient of thermal expansion of the electrode-electrolyte assembly. 10. The electrochemical device of claim 9, wherein the connector has a coefficient of thermal expansion within about 2.5% of the coefficient of thermal expansion of the electrode-electrolyte assembly. The electrochemical device of claim 1, further comprising an interface agent disposed between the metal and the reinforcement material. The electrochemical device of claim 11, wherein the surfactant comprises a reactive metal selected from the group consisting of titanium, lanthanum, cerium, yttrium, silicon, vanadium, iron, and combinations thereof. The electrochemical device of claim 1, wherein the connecting member has a thermal conductivity of at least about 50 W / m · K. The electrochemical device of claim 13, wherein the connecting member has a thermal conductivity of at least about 100 W / m · K. 15. The electrochemical device of claim 14, wherein the connecting member has a thermal conductivity of at least about 150 W / mK. 16. The electrochemical device of claim 15, wherein said linking member has a thermal conductivity of at least about 220 W / mK. The electrochemical device of claim 1, wherein the electrochemical device is a solid oxide fuel cell. Metal composites; And an electrode-electrolyte assembly in contact with the metal composite material, The metal composite material is within about 10% of the thermal expansion coefficient of the electrode-electrolyte assembly and has a thermal expansion coefficient of about 6 × 10 ⁻⁶ to 14 × 10 ⁻⁶ / ° C. ² . 19. The electrochemical device of claim 18, wherein the metal composite has a coefficient of thermal expansion of about 10x10 ^-6 to ^{13x10 -6} / ° C. 20. The electrochemical device of claim 19, wherein the metal composite has a coefficient of thermal expansion of about 11.5 × 10 ⁻⁶ to 12.5 × 10 ⁻⁶ / ° C. 20. 19. The electrochemical device of claim 18, wherein the metal composite is about 20% to 80% by volume of copper or a copper alloy and about 20% to 80% by volume of silicon carbide. The electrochemical device of claim 21, wherein the metal composite material is about 40% to 60% by volume copper and about 40% to 60% by volume silicon carbide. 23. The electrochemical device of claim 22, wherein the metal composite material is about 45 vol.% Copper and about 55 vol.% Silicon carbide. 19. The electrochemical device of claim 18, wherein the metal composite material comprises about 20% to 80% by volume of copper or a copper alloy and about 20% to 80% by volume of boron carbide. 25. The electrochemical device of claim 24, wherein the metal composite material is about 45% by volume copper and about 55% by volume boron carbide. 19. The electrochemical device of claim 18, wherein the metal composite material comprises about 20% to 80% by volume of copper or a copper alloy and about 20% to 80% by volume of aluminum oxide. 19. The electrochemical device of claim 18, further comprising an interface agent disposed between the metal and the reinforcement material of the metal composite material. 28. The electrochemical device of claim 27, wherein the surfactant comprises a reactive metal selected from the group consisting of titanium, lanthanum, cerium, yttrium, silicon, vanadium, iron, and combinations thereof. At least one metal selected from the group consisting of copper, oxide dispersion strengthened copper, aluminum, titanium and alloys thereof, carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium diboride, hafnium Fuel comprising metal composites of at least one reinforcing material selected from the group consisting of diboride, tantalum diboride, titanium diboride, silicon dioxide, aluminum oxide, aluminosilicate, silicon nitride, aluminum nitride and mixtures thereof Providing fuel and oxidant to the cell. Providing a fuel cell comprising an electrode-electrolyte assembly and a connection material disposed in contact with the surface of the electrode-electrolyte assembly; The connecting material includes copper or a copper alloy and a metal composite material of a ceramic selected from the group consisting of silicon carbide, boron carbide and aluminum oxide. Providing an electrode-electrolyte assembly; And A method of fabricating a fuel cell, comprising providing a connecting material comprising a metal composite having a coefficient of thermal expansion within about 10% of the coefficient of thermal expansion of the electrode-electrolyte assembly. 3. The electrochemical device of claim 2, wherein said coating comprises lanthanum nickel oxide. 19. The electrochemical device of claim 18, wherein the metal composite material comprises at least one metal selected from the group consisting of pure nickel, copper, copper alloy, aluminum, aluminum alloy, titanium and titanium alloy. 19. The electrochemical device of claim 18, wherein the metal composite material comprises a coating on its surface. 35. The electrochemical device of claim 34, wherein the metal composite material comprises a metal selected from the group consisting of nickel, copper, titanium, aluminum, and alloys thereof. 28. The electrochemical device of claim 27, wherein the metal comprises nickel, copper or alloys thereof. 37. The method of claim 36, wherein the reinforcing material is carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium diboride, hafnium diboride, tantalum diboride, titanium diboride, silicon dioxide, aluminum oxide An electrochemical device comprising a material selected from the group consisting of aluminosilicate, silicon nitride, aluminum nitride and mixtures thereof. 32. The method of claim 31, wherein the metal composite material comprises at least one metal selected from the group consisting of pure nickel, copper, copper alloy, aluminum, aluminum alloy, titanium, and titanium alloy. 32. The method of claim 31, wherein the metal composite material has a coating on its surface and comprises a metal selected from the group consisting of nickel, copper, titanium, aluminum, and alloys thereof. Electrode-electrolyte conjugates; And A connecting material in contact with the electrode-electrolyte assembly, the connecting material comprising pure nickel, carbon, boron carbide, silicon carbide, zirconium carbide, hafnium carbide, tantalum carbide, titanium carbide, zirconium diboride, hafnium diboride, tantalum An electrochemical device comprising a metal composite of at least one reinforcing material selected from the group consisting of diboride, titanium diboride, silicon dioxide, aluminum oxide, aluminosilicate, silicon nitride, aluminum nitride and mixtures thereof. 41. The method of claim 40, further comprising a sheath on the surface of the connecting material; And said coating comprises a conductive material. 43. The electrochemical device of claim 41, wherein the coating comprises at least one material selected from the group consisting of lanthanum strontium manganite, lanthanum strontium chromite, precious metals, nickel, copper, and lanthanum nickel oxide.

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