Patent Application
20220311038
The present disclosure relates to a cell, a cell stack device, a module, and a module housing device.
In recent years, in fuel cell devices used as next-generation energy sources, for example, a cell in which a fuel electrode layer, a solid electrolyte layer, and an air electrode layer are layered on a porous support body is used. A ceramic material, a metal material, or the like is used for the support body. For the metal support body, a metal material such as ferritic stainless steel having high thermal resistance and corrosion resistance is used, and a metal sintered body obtained by sintering a powder of the metal material or a metal plate having through holes is used. For example, Patent Document 1 discloses a solid oxide fuel cell (SOFC) using a porous metal containing Fe and Cr as a support body.
A cell of the present disclosure includes a metal plate having a pair of surfaces, which are a first surface and a second surface that face each other, an element portion disposed on the first surface and including a first electrode layer, a solid electrolyte layer located on the first electrode layer, and a second electrode layer located on the solid electrolyte layer, and an intermediate layer located between the first surface and the first electrode layer. The intermediate layer has a plurality of first through holes passing through the intermediate layer in a thickness direction.
A cell stack device of the present disclosure includes a cell stack in which a plurality of the above-mentioned cells are disposed.
A module of the present disclosure includes a housing container and the above-mentioned cell stack device housed in the housing container.
A module housing device of the present disclosure includes an external case, the above-mentioned module housed in the external case, and an auxiliary device housed in the external case, and configured to operate the module.
The metal support body has a gas-flow passage 7 formed by the second surface 2b and the flow path member 8. The second surface 2b is on the opposite side to the first surface 2a of the metal plate 2 on which the element portion 6 is disposed.
The metal plate 2 has gas permeability that allows a gas flowing through the gas-flow passage 7 to permeate to the first electrode layer 3. The flow path member 8 has a gas blocking property that prevents gas from flowing between the gas-flow passage 7 and the outside of the cell 1, that is, prevents mixing of fuel gas and oxygen-containing gas such as air. In the example illustrated in
Hereinafter, the same members will be designated by the same reference numerals in other figures. Note that, in each figure, each layer is enlarged in the thickness direction for ease of explanation, and the actual thickness of each layer is very thin relative to the size of the cell 1. Further, in order to clarify the arrangement of each of the members constituting the cell 1, coordinate axes of xyz are set.
Hereinafter, unless otherwise specified, the first electrode layer 3 located between the metal plate 2 and the solid electrolyte layer 4 will be referred to as a fuel electrode, and the second electrode layer 5 located on the solid electrolyte layer 4 will be referred to as an air electrode. Fuel gas such as hydrogen-containing gas is supplied to the gas-flow passage 7, that is, the second surface 2b side, which is the lower side of the metal plate 2 illustrated in
The cell 1 may be, for example, a solid oxide cell 1. The solid oxide cell 1 has high power generation efficiency as a fuel cell, whereby the entire power generation device can be reduced in size. In addition, the solid oxide cell 1 can perform load following operation, and can follow the fluctuating load required for, for example, a household fuel cell.
As the fuel electrode, a material commonly known as a fuel electrode may be used. The fuel electrode may contain a porous conductive ceramic such as stabilized zirconia and Ni and/or NiO. Stabilized zirconia is, for example, ZrO2 in which magnesium (Mg), calcium (Ca), or a rare earth element is present in solid solution, and also includes partially stabilized zirconia. The rare earth element in the present disclosure includes yttrium (Y).
The solid electrolyte layer 4 is an electrolyte that transfers electric charges between the first electrode layer 3 and the second electrode layer 5. The solid electrolyte layer 4 has a gas blocking property so that the fuel gas and the oxygen-containing gas such as air do not mix with each other. The material of the solid electrolyte layer 4 is not limited as long as the material is an electrolyte having a gas blocking property, and may be ZrO2 in which, for example, 3 mol % to 15 mol % of a rare earth element oxide is present in solid solution. The solid electrolyte layer 4 may be dense or may have pores as long as the solid electrolyte layer 4 has a gas blocking property.
As the air electrode, a material commonly used as an air electrode may be used. The air electrode may be, for example, a so-called ABO3 perovskite oxide conductive ceramic. The air electrode has gas permeability. The open porosity of the air electrode may be 20% or more, in particular, in a range of from 30% to 50%.
The metal plate 2 has electrical conductivity. Since the metal plate 2 has electrical conductivity, electricity generated in the element portion 6 can be collected. The conductivity of the metal plate 2 may be, for example, 3.0 S/m or more, particularly 4.4 S/m or more.
Further, the metal plate 2 is configured to allow gas to flow between the first surface 2a and the second surface 2b. In other words, the metal plate 2 has gas permeability between the first surface 2a and the second surface 2b. Since the metal plate 2 has gas permeability, the fuel gas supplied to the gas-flow passage 7 can reach the first electrode layer 3 which is the fuel electrode.
As illustrated in
The material of the metal plate 2 may be, for example, a conductive material such as a heat-resistant alloy. The metal plate 2 may contain Cr, and may contain, for example, from 4 atomic % to 30 atomic % chromium (Cr) with respect to the entire alloy. The Cr-containing alloy may be a nickel-chromium-based alloy, an iron-chromium-based alloy, or austenite-based, ferrite-based, or austenite-ferrite-based stainless steel. Additionally, the metal plate 2 may contain manganese (Mn) or aluminum (Al) as an element other than Cr.
The element portion 6 is manufactured by simultaneously sintering a laminate in which two or more layers of the fuel electrode layer, the solid electrolyte layer 4, and the air electrode layer are layered. The metal plate 2 is often bonded to the sintered laminate with an adhesive or the like. The solid electrolyte layer 4 is dense and does not have gas permeability; however, the first electrode layer 3 and the second electrode layer 5, that is, the fuel electrode and the air electrode are porous and permeable to gas. When the dense solid electrolyte layer 4 is fired simultaneously with the porous first electrode layer 3 or the second electrode layer 5, the sintered laminate often has warpage or deformation because the contraction factor at the time of firing differs for each layer. When the metal plate 2 and the laminate having warpage or deformation are bonded, peeling or cracking is likely to occur in the laminate. The solid electrolyte layer 4 may cover all the surfaces of the first electrode layer 3 that are not in contact with the metal plate 2. The solid electrolyte layer 4 and the flow path member 8 may form a tubular body. Further, a surface of the first electrode layer 3 that is not in contact with the metal plate 2 or the solid electrolyte layer 4 may be covered with another member having no gas permeability.
Each of the first through holes has a diameter of one half or more of the thickness of the intermediate layer 9. That is, the first through hole may have opening portions with a diameter of one half or more of the thickness of the intermediate layer 9 on two facing surfaces of the intermediate layer 9, that is, a surface facing the first electrode layer 3 and a surface facing the metal plate 2. The first through hole may have a diameter of one half or more of the thickness of the intermediate layer 9 in a cross section perpendicular to the thickness direction of the intermediate layer 9. Note that the diameter of the first through hole at the opening portions or in the cross section is the diameter when the area of the opening portion or cross section is converted into a circle. The first through hole may have, for example, a diameter of 0.01 mm or more and 1.0 mm or less in the cross section perpendicular to the thickness direction of the intermediate layer 9. The opening portions and the cross section perpendicular to the thickness direction of the intermediate layer 9 of the first through hole may have a circular shape, an elliptical shape, a polygonal shape such as a triangular shape or a quadrangular shape, or an irregular shape. The distance between adjacent ones of the first through holes may be, for example, 0.7 to 1.0 times the diameter of each of the first through holes. By having the first through holes having such a diameter at such distances, it is possible to form a laminate with little warpage or deformation, and it is possible to obtain high power generation efficiency by allowing gas to flow to the first electrode layer 3.
The intermediate layer 9 may have open pores or closed pores in addition to the first through holes, or may have a dense portion other than the first through holes. Hereinafter, the porosity of the intermediate layer 9 is the porosity of the portion other than the first through holes in the intermediate layer 9, and the denseness of the intermediate layer 9 is the denseness of the portion other than the first through holes in the intermediate layer 9. The intermediate layer 9 may have a porosity smaller than that of the first electrode layer 3. For example, the open porosity of the fuel electrode is 10% or more, in particular, from 20% to 50%, and the open porosity of the air electrode is 20% or more, in particular, from 30% to 50%. When the porosity of the intermediate layer 9 is smaller than that of the first electrode layer 3, that is, the fuel electrode or the air electrode, that is, the intermediate layer 9 has an open porosity of less than 10%, the warpage or deformation of the laminate of the intermediate layer 9, the first electrode layer 3, and the solid electrolyte layer 4 becomes small. The open porosity of the intermediate layer 9 may be, for example, 10% or less. The intermediate layer 9 need not have open pores. The intermediate layer 9 may have a porosity similar to that of the solid electrolyte layer 4, or the intermediate layer 9 may be dense.
The intermediate layer 9 has the first through holes, and even when the intermediate layer 9 is dense, the gas can be made to flow to the first electrode layer 3 through the first through holes.
The material of the intermediate layer 9 may be a material having a lower contraction factor at the time of firing than the material of the first electrode layer 3. Examples of the material of the intermediate layer 9 include yttrium-stabilized zirconia. The material of the intermediate layer 9 may be a ceramic material containing stabilized zirconia and Ni and/or NiO with a smaller open porosity than the fuel electrode. The material of the intermediate layer 9 may be a lanthanum chromite-based perovskite oxide (LaCrO3-based oxide) or a lanthanum strontium titanium-based perovskite oxide (LaSrTiO3-based oxide). The intermediate layer 9 may be electrically insulating or electrically conductive.
The material of the intermediate layer 9 may be a material similar to that of the solid electrolyte layer 4, for example, ZrO2 with 3 mol % to 15 mol % of a rare earth element oxide in solid solution. For example, when the material of the intermediate layer 9 is the same as the material of the solid electrolyte layer 4, that is, the main component of the intermediate layer 9 is the same as the main component of the solid electrolyte layer 4, the contraction factors of the intermediate layer 9 and the solid electrolyte layer 4 at the time of firing become substantially the same, and the warpage or deformation of the laminate becomes smaller.
A conductive member 10 may be disposed in the first through holes in the intermediate layer 9. The conductive member 10 electrically connects the metal plate 2 and the first electrode layer 3. The conductive member 10 may be an electrically conductive adhesive that bonds the metal plate 2 and the laminate described above. The conductive member 10 disposed in the first through holes in the intermediate layer 9 may be porous. When the intermediate layer 9 is dense, gas can be made to flow between the metal plate 2 and the first electrode layer 3 through the porous conductive member 10. The conductive member 10 may have, for example, an open porosity of 30% or more, in particular, in a range of from 35% to 50%.
The metal plate 2 may be a flat plate-shaped porous body having an open porosity of, for example, 30% or more, particularly in a range of from 35% to 50%. Further, as illustrated in
The dense metal plate 2 has a smaller surface area and higher corrosion resistance than the porous metal plate 2. Additionally, since the surface area of the dense metal plate 2 is small, an oxide film formed on the surface, that is, the content of the oxide is small. Therefore, the dense metal plate 2 has higher electrical conductivity.
When the metal plate 2 has the second through holes 11, the second through holes 11 may pass through the conductive member 10 in the thickness direction, or need not pass through the conductive member 10 as illustrated in
The conductive member 10 may contain conductive particles and inorganic oxides. The conductive particles may be, for example, metal or alloy particles, conductive oxide particles, or the like. The conductive particles may contain metals such as Ni, Cu, Co, Fe, and Ti or alloys thereof, or may contain oxides or composite oxides containing Ni, Fe, Mn, Co, Zn, Ti, In, Sn, and the like. Metals such as Ni, Cu, Co, Fe, and Ti or alloys thereof, and oxides or composite oxides containing Ni, Fe, Mn, Co, Zn, Ti, In, Sn, and the like have a high level of conductivity. Further, the conductive particles may contain a lanthanum chromite-based perovskite oxide (LaCrO3-based oxide) or a lanthanum strontium titanium-based perovskite oxide (LaSrTiO3-based oxide). These perovskite oxides have electrical conductivity, and are neither reduced nor oxidized even when the perovskite oxides come into contact with a fuel gas such as a hydrogen-containing gas and an oxygen-containing gas such as air. These metals or alloys and oxides have high electrical conductivity, so that the electricity generated in the element portion 6 can be easily collected by the metal plate 2. In particular, the metal Ni has high electrical conductivity, and can maintain the electrical conductivity even in a high temperature reaction atmosphere. Further, Ni is contained in the first electrode layer 3, which is the fuel electrode, and the joining properties between the conductive member 10 and the first electrode layer 3 can be enhanced.
The conductive member 10 may contain inorganic oxides. Examples of the inorganic oxides contained in the conductive member 10 include oxides of Ti, Zr, Al, Si, Mg, Ca, Sr, Ba, or the like, and rare earth oxides such as oxides of Y, Yb, Ce, and Gd. The inorganic oxide contained in the conductive member 10 may be, for example, stabilized zirconia, a rare earth oxide, an ABO3 perovskite oxide, or a titanium oxide. Note that an example of the rare earth oxide is yttrium oxide (Y2O3).
When the first electrode layer 3 is the fuel electrode, the conductive member 10 may contain stabilized zirconia or a rare earth oxide contained in the fuel electrode. When the first electrode layer 3 is the air electrode, the conductive member 10 may contain an electrically conductive ABO3 perovskite oxide contained in the air electrode. Since the conductive member 10 contains the same inorganic oxide as the inorganic oxide contained in the first electrode layer 3, the adhesive strength between the first electrode layer 3 and the metal plate 2 can be increased.
The conductive member 10 may contain at least one kind of inorganic oxide from among Ti, Al, and Si. When the conductive member 10 includes inorganic oxides of Ti, Al, and Si, the components of the conductive particles contained in the conductive member 10 are likely to dissolve or diffuse in the first surface 2a of the metal plate 2, and the electric resistance at the interface between the metal plate 2 and the conductive member 10 can be made smaller.
When the conductive member 10 contains the conductive particles and the inorganic oxide, with respect to the total amount of the elements contained in the conductive member 10 in terms of an oxide, the ratio of the conductive particles may be, for example, 40 mol % or more and 80 mol % or less, and the ratio of the inorganic oxide may be, for example, more than 20 mol % and less than 60 mol %.
The conductive member 10 may be disposed not only in the first through holes, but also between the metal plate 2 and the intermediate layer 9 as illustrated in
As illustrated in
When the metal plate 2 has the second through holes 11, at least some of the second through holes 11 may overlap with the first through holes in a plan view in the thickness direction. When at least some of the second through holes 11 overlap with the first through holes, the gas easily reaches the first electrode layer 3 through the second through holes 11 and the first through holes.
When the metal plate 2 has the second through holes 11, the second through holes 11 need not overlap with the first through holes in a plan view in the thickness direction. When the second through holes 11 do not overlap with the first through holes, the conductive member 10 located in the first through holes connects the first electrode layer 3 and the metal plate 2 at the shortest distance, and the electricity generated in the element portion 6 can be easily collected by the metal plate 2.
The metal plate 2 may have recessed portions or projecting portions on at least one of the first surface 2a and the second surface 2b.
As illustrated in
The cell 1 illustrated in
The presence or absence of the intermediate layer 9 and the porosity thereof and the presence or absence of the conductive member 10 and the porosity thereof can be confirmed, for example, by observing the cross section of the cell 1 with a scanning electron microscope (SEM), a scanning transmission electron microscope (STEM), a transmission electron microscope (TEM), or the like. The elements contained in the intermediate layer 9 and the conductive member 10 and the content ratios thereof can be analyzed with, for example, wavelength dispersive X-ray spectroscopy (WDS), energy dispersive X-ray spectroscopy (EDS), or an electron probe microanalyzer (EPMA).
A method of manufacturing the cell 1 provided with the intermediate layer 9 and the conductive member 10 when the first electrode layer 3 is used as the fuel electrode will be described. As the metal plate 2, a base member such as stainless steel is prepared. The base member may be an alloy plate or an alloy foil. When the metal plate 2 has gas permeability, the base member may be an alloy plate or an alloy foil having the second through holes 11, or may be a porous sintered body made of a metal powder.
Further, a laminate is prepared in which the fuel electrode containing Ni and/or NiO and stabilized zirconia is sandwiched between stabilized zirconia to be the solid electrolyte layer 4 and a material to be the intermediate layer 9.
The laminate in which the fuel electrode is sandwiched between the solid electrolyte layer 4 and the intermediate layer 9 may be produced by the following method. A fuel electrode precursor in which a binder is added to a slurry obtained by mixing a Ni or NiO powder and a stabilized zirconia powder with an organic solvent, and a solid electrolyte precursor in which a binder is added to a slurry obtained by mixing a stabilized zirconia powder with an organic solvent are prepared. The fuel electrode precursor may contain a pore-forming material. A sheet powder compact obtained by sheet-forming using the solid electrolyte precursor is perforated to obtain a sheet powder compact for the intermediate layer. A sheet powder compact for the fuel electrode is formed on the surface of the sheet powder compact of the intermediate layer using the fuel electrode precursor. Further, a sheet powder compact for the solid electrolyte is formed on the surface of the sheet powder compact for the fuel electrode using the solid electrolyte precursor to obtain a laminated powder compact. The obtained laminated powder compact is fired to obtain a laminate of the intermediate layer 9, the fuel electrode, and the solid electrolyte layer 4. The fuel electrode having a large contraction factor is sandwiched between the intermediate layer 9 and the solid electrolyte layer 4 that have a relatively low contraction factor and sintered so that the obtained laminate has little warpage or deformation.
The base member and the laminate of the intermediate layer 9, the fuel electrode, that is, the first electrode layer 3, and the solid electrolyte layer 4 are bonded with an adhesive. As the adhesive, a paste is used containing at least one of the conductive particles of Ni, NiO, Cu, Co, and Zn, and as the inorganic oxide, at least one of oxides such as oxides of Ti, Zr, Al, Si, Mg, Ca, Sr, and Ba and rare earth oxides such as oxides of Y and Yb. The adhesive may contain not only one kind of conductive particles but also two or more kinds, and may contain not only one kind of inorganic oxide but also two or more kinds. Further, the inorganic oxide may be a composite oxide of two or more kinds of elements.
The adhesive is applied to the first surface 2a of the base member, and the first surface 2a of the base member to which the adhesive is applied is bonded to the surface of the intermediate layer 9 of the laminate. The bonded base member and the laminate are thermally treated in a nitrogen atmosphere or in the air, for example, in a range of 1000° C. to 1200° C. for 0.5 hours to 2 hours. In the obtained joint body of the base member and the laminate, since the warpage or deformation of the laminate is small, peeling or cracking is unlikely to occur in the laminate.
Note that in the above description, the intermediate layer 9, the fuel electrode, and the solid electrolyte layer 4 are sequentially sheet-formed to form a laminate. However, the sheet powder compact for the intermediate layer 9 and a laminate of the sheet powder compacts for the fuel electrode and the solid electrolyte layer 4 may be individually prepared, and the sheet powder compact for the intermediate layer 9 and the sheet powder compact for the fuel electrode of the laminate may be bonded together. In addition, the solid electrolyte layer 4 may be sheet-formed on one surface of the sheet powder compact for the fuel electrode, and the pattern of the intermediate layer 9 having the first through holes may be printed on another surface.
As illustrated in
The cell stack 21 includes the plurality of cells 1 disposed or stacked in the thickness direction of the cells 1, and current collection members 23a that electrically connect adjacent ones of the cells 1 in series. The direction in which the plurality of cells 1 are disposed is referred to as an arrangement direction x.
The current collection members 23a may also be disposed on the two ends of the cell stack 21 in the arrangement direction x. The current collection members 23a may be bonded to the cells 1 with a conductive adhesive. As a material of the current collection members 23a, an elastic metal or alloy may be used, or felt made of metal fiber or alloy fiber may be used. The felt made of metal fiber or alloy fiber may be surface-treated as needed.
As illustrated in
The lower end portions of the current collection members 23a and the end current collection members 23b may be fixed to the gas tank 22 with the sealing member S. The end current collection members 23b may be integrated with the cell stack 21.
A module 30 includes a rectangular parallelepiped-shaped housing container 31 and the above-mentioned cell stack device 20 housed inside the housing container 31. A reformer 32 is disposed above the cell stack 21. The reformer 32 is connected to the gas tank 22 by a gas flow pipe 33. The reformer 32 reforms raw fuel such as natural gas or kerosene supplied via a raw fuel supply pipe 34 to produce fuel gas. The gas flow pipe 33 supplies the fuel gas reformed by the reformer 32 to the gas tank 22. The fuel gas is supplied from the gas tank 22 to the gas-flow passage 7 of the cell 1.
The housing container 31 includes an oxygen-containing-gas inlet member 35 therein. The oxygen-containing-gas inlet member 35 in
A module housing device 40 illustrated in
The dividing plate 43 has an air flow port 46 for allowing the air in the auxiliary device housing chamber 45 to flow into the module housing chamber 44. One of the exterior plates 42 forming the module housing chamber 44 has an exhaust hole 47 for exhausting the air in the module housing chamber 44. The air in the module housing chamber 44 is exhausted from the exhaust hole 47.
Since the module 30 described above is provided in the module housing chamber 44, the module housing device 40 can be made highly durable.
The present disclosure has been described in detail above. However, the present disclosure is not limited to the embodiments described above. The cell, the cell stack device, the module, and the module housing device of the present disclosure may be variously modified, improved, and the like without departing from the gist of the present disclosure.
For example, in the cell stack device 20 described above, an example is illustrated in which the fuel gas is supplied to the gas-flow passage 7 in the cell 1 and the oxygen-containing gas is supplied to the outside of the cell 1. However, the oxygen-containing gas may be supplied to the gas-flow passage 7, and the fuel gas may be supplied to the outside of the cell 1.
Further, in the above description, the fuel cell, the fuel cell stack device, the fuel cell module, and the fuel cell device are respectively illustrated as one example of the “cell”, the “cell stack device”, the “module”, and the “module housing device”. However, in another example, the “cell”, the “cell stack device”, the “module”, and the “module housing device” may be an electrolysis cell, an electrolysis cell stack device, an electrolysis module, and an electrolysis device, respectively.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-083011 | Apr 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/017331 | 4/22/2020 | WO |
