阅读说明：本技术 固体氧化物燃料电池互连件 (Solid oxide fuel cell interconnects ) 是由 S·R·沃尔蒂 P·希迪 J·R·郝克斯 S·C·埃默森 T·朱 于 2021-04-08 设计创作，主要内容包括：公开一种固体氧化物燃料电池,所述固体氧化物燃料电池包括电极-电解质组件以及与所述电极-电解质组件连通的互连件,其中所述互连件具有孔隙率梯度。(A solid oxide fuel cell is disclosed that includes an electrode-electrolyte assembly and an interconnect in communication with the electrode-electrolyte assembly, wherein the interconnect has a porosity gradient.)

1. A solid oxide fuel cell comprising an electrode-electrolyte assembly and an interconnect in communication with the electrode-electrolyte assembly, wherein the interconnect has a porosity gradient.

2. The solid oxide fuel cell of claim 1, wherein the interconnect has a lower porosity in a central region.

3. The solid oxide fuel cell of claim 1, wherein the interconnect has an inner region that is gas or fluid impermeable.

4. The solid oxide fuel cell of claim 1, wherein the interconnect comprises a carbon-based composite material.

5. The solid oxide fuel cell of claim 4, wherein the carbon-based composite material comprises carbon fibers, metal fibers, ceramic fibers, or a combination thereof.

6. The solid oxide fuel cell of claim 4, wherein the carbon-based composite material further comprises metal particles.

7. The solid oxide fuel cell of claim 4, wherein the carbon-based composite material comprises a fiber preform and a carbon matrix.

8. The solid oxide fuel cell of claim 4, wherein the carbon-based composite material comprises discontinuous carbon fibers dispersed in a carbon matrix.

9. The solid oxide fuel cell of claim 4, wherein the carbon-based composite material has a density of less than or equal to 3.4 grams per cubic centimeter.

10. An interconnect for a solid oxide fuel cell, the interconnect having a porosity gradient.

11. The interconnect of claim 10, wherein the interconnect has a lesser porosity in a central region.

12. The interconnect of claim 10, wherein the interconnect has an interior region that is air or fluid impermeable.

13. The interconnect of claim 10, wherein the interconnect comprises a carbon-based composite material.

14. The interconnect of claim 13, wherein the carbon-based composite material comprises carbon fibers, metal fibers, ceramic fibers, or a combination thereof.

15. The interconnect of claim 13, wherein the carbon-based composite further comprises metal particles.

16. The interconnect of claim 13, wherein the carbon-based composite material comprises a fiber preform and a carbon matrix.

17. The interconnect of claim 13, wherein the carbon-based composite material comprises discontinuous fibers dispersed in a carbon matrix.

18. The interconnect of claim 13, wherein the carbon-based composite is thermomechanically stable for greater than 100 hours at a temperature greater than 400 ℃.

19. The interconnect of claim 13, wherein the carbon-based composite material has an electrical resistivity of less than or equal to 0.1 milliohms/cm at 20 ℃.

Technical Field

Exemplary embodiments relate to the field of solid oxide fuel cells, and in particular to interconnects for solid oxide fuel cells.

Background

Electrochemical devices, such as fuel cells, convert chemical energy into electrical energy. Conversion involves the controlled oxidation of a fuel such as hydrogen, hydrocarbons or reformed hydrocarbons. The fuel cell assembly may comprise one or preferably a plurality of stacked cells. A fuel cell has an anode and a cathode separated by an electrolyte. The fuel cell may also include one or more interconnects.

Interconnects are typically made of metals such as stainless steel, which can make the fuel cell heavier than is desirable in some applications. Lighter weight interconnect materials are desired.

Disclosure of Invention

A solid oxide fuel cell is disclosed that includes an electrode-electrolyte assembly and an interconnect in communication with the electrode-electrolyte assembly, wherein the interconnect has a porosity gradient.

In addition to one or more of the features described above, or as an alternative to any of the previous embodiments, the interconnect has a lower porosity in the central region.

In addition to one or more features described above, or as an alternative to any of the preceding embodiments, the interconnect has an inner region that is air-tight or fluid-tight.

In addition to one or more features described above, or as an alternative to any of the preceding embodiments, the interconnect includes a carbon-based composite.

In addition to or as an alternative to one or more of the features described above, the carbon-based composite material includes carbon fibers, metal fibers, ceramic fibers, or a combination thereof. The carbon-based composite material may further include metal particles.

In addition to one or more of the features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material includes a fiber preform and a carbon matrix.

In addition to one or more features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material includes discontinuous fibers dispersed in a carbon matrix.

In addition to one or more of the features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material has a density of less than or equal to 3.4 grams per cubic centimeter.

Also disclosed is an interconnect for a solid oxide fuel cell, the interconnect comprising a porosity gradient.

In addition to one or more of the features described above, or as an alternative to any of the previous embodiments, the interconnect has a lower porosity in the central region.

In addition to one or more features described above, or as an alternative to any of the preceding embodiments, the interconnect has an inner region that is air-tight or fluid-tight.

In addition to one or more features described above, or as an alternative to any of the preceding embodiments, the interconnect includes a carbon-based composite.

In addition to or as an alternative to one or more of the features described above, the carbon-based composite material includes carbon fibers, metal fibers, ceramic fibers, or a combination thereof. The carbon-based composite material may further include metal particles.

In addition to one or more of the features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material includes a fiber preform and a carbon matrix.

In addition to one or more features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material includes discontinuous fibers dispersed in a carbon matrix.

In addition to one or more of the features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material has a porosity gradient.

In addition to one or more of the features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material has a density of less than or equal to 3.4 grams per cubic centimeter.

In addition to one or more of the features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material is thermomechanically stable at a temperature of greater than 400 ℃ for greater than 100 hours.

In addition to one or more of the features described above, or as an alternative to any of the preceding embodiments, the carbon-based composite material has an electrical resistivity of less than or equal to 0.1 milliohms/cm at 20 ℃.

Drawings

The following description should not be considered limiting in any way.

Fig. 1 is a schematic diagram of a stack of solid oxide fuel cells.

Detailed Description

A detailed description of one or more embodiments of the disclosed apparatus and methods are presented herein by way of example and not limitation with reference to the accompanying drawings.

As shown in fig. 1, the fuel cell stack 1 includes a plurality of fuel cells 10. One or more fuel cells may include an electrode-electrolyte assembly (EEA)12 and an interconnect 14 that is typically in electrical, thermal, and/or structural communication with the EEA 12. The EEA 12 generally includes an electrolyte 16 disposed in electrical and ionic communication with an anode 18 and a cathode 20.

The interconnect 14 generally includes features, such as channels 22, that facilitate or direct the reaction of the fuel or oxidant in the EEA 12. The interconnect 14 may also serve as a current collector during operation of the electrochemical device 10 to provide or direct generated electrical energy to a load (not shown). In some cases, the interconnect 14 may have a coating (not shown) disposed on a surface adjacent to the interface 22 of the EEA 12. A sublayer or intermediate layer (not shown) may also be utilized between the coating and the surface of the interconnect. Although fig. 1 shows a general geometry of the interconnect, this should not be construed as limiting, and the interconnect described herein may have any geometry suitable for use in a solid oxide fuel cell.

The interconnect includes a carbon-based composite material. The carbon-based composite material includes a carbon matrix and a reinforcing material. Exemplary reinforcing materials include carbon fibers, metal fibers such as tungsten fibers, ceramic fibers, and combinations thereof. Exemplary ceramic fibers include silicon carbide fibers, alumina fibers, boron nitride fibers, and combinations thereof. The fibers may optionally be combined with particulate materials such as metal particles. Exemplary metal particles include transition metals such as titanium, chromium, iron, cobalt, nickel, copper, and corrosion resistant alloys such as stainless steel, iron-based alloys, nickel-based alloys, and cobalt-based alloys. The metal particles may be a mixture of any of the foregoing. The reinforcing material may be continuous fibers or discontinuous (chopped) fibers. The continuous fibers may be unidirectional, woven, or non-woven in the fabric. The discontinuous (chopped) fibers may be dispersed, aligned, or randomly oriented in the woven or nonwoven fabric. The reinforcing material may be a preform. The fibrous preform may comprise a woven preform or a non-woven preform. The fibers may have an average diameter of 5 to 20 microns.

The carbon-based composite material may have a density of less than or equal to 3.4 grams per cubic centimeter. The carbon-based composite is thermomechanically stable, e.g., at least about 100 hours, in some cases at least about 5,000 hours, and in other cases at least about 40,000 hours, at an operating temperature greater than 400 ℃ over the lifetime of the interconnect relative to its configuration at room temperature or initial start-up or initial commissioning. Carbon-based composites may also be chemically stable and corrosion resistant in their operating environment.

The carbon-based composite may have an electrical resistivity of less than 0.1 milli-ohm/cm, or less than 0.05 milli-ohm/cm, or less than 0.025 milli-ohm/cm at a temperature of 20 ℃.

The porosity of the carbon-based composite material may vary throughout the thickness of the interconnect layer. For example, porosity may vary as a function of distance from the interconnect surface. Accordingly, the interconnect may have less porosity toward the center of the interconnect. Likewise, the interconnect may have varying porosity with respect to the distance from its outer edge to its core. For example, the interconnect may have less porosity toward the center of the interconnect. The change may be continuous, providing a gradual change, or the change may be discrete, providing a step or incremental change. The porosity may vary from greater than or equal to 30%, or greater than or equal to 40%, or greater than or equal to 50% at the surface and outer edge to less than 10% at the core. It is further contemplated that higher porosity may be incorporated in the location of the channels 22, giving the interconnect a continuous structure.

The carbon-based composite material may be prepared by any known technique. For example, the carbon-based composite may be prepared by densifying a porous preform, which may include one or more infiltrations of the porous material preform with a liquid or vapor component. The liquid component may comprise a carbon-containing resin, or an aqueous or non-aqueous slurry filled with particles, which provides a matrix of the carbon-based composite material after sintering, hot pressing or other high temperature treatment. In some embodiments, chemical vapor infiltration of a preform is used to provide a matrix in a carbon-based composite. When a porosity gradient is desired, chemical vapor infiltration is used, and the pressure and/or flow of reactants is controlled from different sides of the preform to create regions of higher density and less porosity. In some embodiments, the interconnect has a region that is impermeable to gas or fluid flow.

The interconnect may have one or more coatings or layers on at least a portion of one or more surfaces thereof. Thus, for example, an interconnect can include a carbon-based composite having a coating on at least a portion of a surface thereof. The coating may comprise any suitable material that renders the coating substantially non-porous or impermeable, electrically conductive, and preferably provides oxidation or degradation protection. Preferably, the coating is impermeable to the oxidizing agent and/or the reducing agent at the operating or use temperature of the interconnect. The coating may be selected to provide an area specific resistance between the electrode-electrolyte assembly and the coated interconnect of less than about 0.1 ohm/cm. Thus, for example, the coating can be one or more materials or compounds having an electrical conductivity of at least about 1S/cm; a CTE within about 35%, preferably within about 10%, more preferably within about 5% of the CTE of the interconnect material; and/or a thermal conductivity of at least about 5W/m.K, preferably at least about 10W/m.K, more preferably at least about 100W/m.K. Non-limiting examples of materials or compounds that may include a coating include, but are not limited to, conductive oxides, chromites, nickel oxides, doped or undoped lanthanum chromite, manganese chromite, yttrium oxide, strontium lanthanum manganate (LSM), strontium lanthanum chromite, noble metals (e.g., platinum, gold, and silver) and nickel and copper, doped or undoped conductive perovskites, manganese chromite and lanthanum strontium cobalt oxide, zirconium diboride, silicon titanium carbide, and mixtures or combinations thereof. Typically, the coating is applied as thin as possible while maintaining full density and provides the desired protective ability and/or reduces any adverse or undesirable properties, such as resistivity. For example, the thickness of the coating can be less than about 50 μm, in some cases less than about 25 μm, in other cases less than about 10 μm, and in other cases less than about 5 μm. Coating Materials are available from, for example, NexTech Materials, Ltd, of Liu Yi Sistenet, Ohio, Praxair Specialty Ceramics, Wu Dingville, Washington, and Trans-Tech, Inc, of Adonis, Maryland.

The coating may be applied by any suitable technique, including but not limited to vapor deposition (including atomic layer deposition and chemical vapor deposition), slurry or solution based methods (including screen printing and fluidized bed immersion), spray or dip coating, thermal spraying, and/or physical vapor deposition methods such as magnetron sputtering.

A sub-layer may be disposed between the coating and the surface of the interconnect material. The sub-layer may be disposed at least partially, preferably entirely, at the interface between the coating and any contacting surface of the interconnect material. In some cases, the sub-layer may serve as an additional barrier between the carbon-based composite and the solid oxide fuel cell environment. Preferably, the sub-layer may isolate or otherwise interfere with any unwanted or undesirable reactions between the carbon-based composite and the coating. The present invention also contemplates the use of one or more sub-layers disposed on one or more portions or regions between the coating and the interconnect material surface. Thus, one or more regions may or may not have any sublayers, or one or more regions may have different sublayer compositions. The sub-layers may have any desired thickness that provides electrical and/or thermal conductivity. Typically, the sub-layers are applied as thin as possible while maintaining full density and provide the desired protective ability and/or reduce any adverse or undesirable properties, such as resistivity. For example, the sub-layer may have a thickness of less than about 1 μm, in some cases less than about 0.5 μm, and in other cases less than about 0.1 μm. The sub-layers may be applied by any suitable technique, including but not limited to vapor deposition (including atomic layer deposition and chemical vapor deposition), slurry or solution based methods (including screen printing and fluidized bed immersion), spray or dip coating, thermal spraying, and/or physical vapor deposition methods such as magnetron sputtering. The sub-layers may include, but are not limited to, titanium nitride, titanium aluminum nitride, silicon titanium carbide, or mixtures thereof.

The carbon-based composite may have one or more surfactants that may promote or act to form a bridge between the reinforcing component and the carbon matrix. The surfactant may be deposited as an interfacial layer that aids in adhering the reinforcing component to the substrate.

Any EEA may be used. For example, the EEA may include an anode, an electrolyte, and a cathode. The anode may comprise any material that supports or promotes fuel oxidation, typically having a porosity of 20% to 40%, such as a cermet having primarily a continuous ceramic phase and a discontinuous metal phase, for example, Ni/YSZ (nickel/yttrium stabilized zirconia) or Ni/BYZ (nickel/yttrium doped barium zirconate). The electrolyte may include an oxygen conducting ceramic, such as dense YSZ or a proton conducting ceramic, such as BYZ, typically having a porosity of less than about 1%. The cathode may comprise any material that catalyzes or promotes redox, such as lanthanum strontium manganate, typically having a porosity of 20% to 40%. Electrode-electrolyte assemblies are available from, for example, Innovative Dutch Electro Ceramics (InDEC BV) in the Netherlands and NexTech Materials, Ltd., Liu Yi Si.

The term "about" is intended to include the degree of error associated with a particular number of measurements based on the equipment available at the time of filing the application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. It is further contemplated that the terms "comprises" and/or "comprising" include embodiments in which "comprises" and/or "comprising" may be substituted for "consisting of" and/or "consisting of … ….

While the disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the claims.