The present disclosure relates to a cell, a cell stack device, a module, and a module housing device.
In recent years, various fuel cell stack devices each including a plurality of fuel cells have been proposed as next-generation energy sources. A fuel cell is a type of cell capable of obtaining electrical power by using a fuel gas such as a hydrogen-containing gas and an oxygen-containing gas such as air.
In such a fuel cell stack device, for example, an intermediate layer may be provided between a solid electrolyte layer and an air electrode in an element portion in the fuel cell (see Patent Document 1).
Patent Document 1: JP 2015-35416 A
According to one aspect of the embodiments, a cell includes an element portion including a fuel electrode, a solid electrolyte layer, an air electrode, and an intermediate layer. The intermediate layer is located between the solid electrolyte layer and the air electrode. In a plan view, a porosity in an end portion of the air electrode is greater than a porosity in a center portion of the air electrode.
Also, a cell stack device of the present disclosure includes a cell stack including a plurality of the cells mentioned above.
Also, a module of the present disclosure includes the cell stack device mentioned above and a housing container that houses the cell stack device.
Also, a module housing device of the present disclosure includes the module mentioned above, an auxiliary device for operating the module, and an external case that houses the module and the auxiliary device.
Hereinafter, embodiments of a cell, a cell stack device, a module, and a module housing device disclosed in the present application will be described with reference to the accompanying drawings. The present invention is not limited by the following embodiments.
Note, further, that the drawings are schematic and that the dimensional relationships between elements, the proportions thereof, and the like may differ from the actual ones. There may be differences between the drawings in the dimensional relationships, proportions, and the like.
Referring to
In the example illustrated in
As illustrated in
The element portion 3 is located on the flat surface n1 of the support substrate 2. The element portion 3 such as that described above includes a fuel electrode 5, a solid electrolyte layer 6, an intermediate layer 7, and an air electrode 8. Also, in the example illustrated in FIG. 1A, the interconnector 4 is located on the flat surface n2 of the cell 1. The cell 1 may include a second intermediate layer 9, which will be described later, between the intermediate layer 7 and the air electrode 8.
As illustrated in
Hereinafter, each of constituent members constituting the cell 1 will be described.
The support substrate 2 includes gas-flow passages 2a in which gas flows. The example of the support substrate 2 illustrated in
The material of the support substrate 2 includes, for example, an iron group metal component and an inorganic oxide. For example, the iron group metal component may be Ni (nickel) and/or NiO. For example, the inorganic oxide may be a specific rare earth element oxide.
As the material of the fuel electrode 5, a commonly known material may be used. As the fuel electrode 5, porous conductive ceramics, for example, ceramics containing: ZrO2 in which a calcium oxide, a magnesium oxide, or a rare earth element oxide is solid-dissolved, and Ni and/or NiO may be used. As the rare earth element oxide, for example, Y2O3 or the like is used. Hereinafter, ZrO2 in which calcium oxide, magnesium oxide, or a rare earth element oxide is contained as a solid solution may be referred to as stabilized zirconia. The stabilized zirconia also includes partially stabilized zirconia.
The solid electrolyte layer 6 is an electrolyte and bridges ions between the fuel electrode 5 and the air electrode 8. At the same time, the solid electrolyte layer 6 has gas blocking properties, and makes leakage of the fuel gas and the oxygen-containing gas less likely to occur.
The material of the solid electrolyte layer 6 may be, for example, ZrO2 in which from 3 mole % to 15 mole % of a rare earth element oxide is contained as a solid solution. As the rare earth element oxide, for example, Y2O3 or the like is used. Note that another material may be used as the material of the solid electrolyte layer 6, as long as the material has the aforementioned characteristics.
The intermediate layer 7 functions as a diffusion prevention layer. The intermediate layer 7 makes strontium (Sr) contained in the air electrode 8, which will be described later, less likely to diffuse into the solid electrolyte layer 6, thereby making a resistive layer of SrZrO3 less likely to be formed on the solid electrolyte layer 6.
The material of the intermediate layer 7 is not particularly limited as long as generally used for the diffusion prevention layer of Sr. The material of the intermediate layer 7 includes, for example, cerium oxide (CeO2) in which a rare earth element except Ce (cerium) is in solid solution. As the rare earth element, gadolinium (Gd), samarium (Sm), or the like are used.
The air electrode 8 has gas permeability. The open porosity (porosity) of the air electrode 8 may be, for example, in the range of from 20% to 50%, particularly from 30% to 50%.
The material of the air electrode 8 is not particularly limited, as long as the material is commonly used for the air electrode. The material of the air electrode 8 may be, for example, a conductive ceramic such as an ABO3 type perovskite oxide.
The material of the air electrode 8 may be, for example, a composite oxide in which strontium (Sr) and lanthanum (La) coexist at the A site. Examples of such a composite oxide include LaxSr1-xCoyFe1-yO3, LaxSr1-xMnO3, LaxSr1-xFeO3, and LaxSr1-xCoO3. Here, x is 0<x<1, and y is 0<y<1.
The interconnector 4 is dense, and makes the leakage of the fuel gas flowing through the gas-flow passages 2a located inside the support substrate 2, and of the oxygen-containing gas flowing outside the support substrate 2 less likely to occur. The interconnector 4 may have a relative density of 93% or more, particularly 95% or more.
As the material of the interconnector 4, a lanthanum chromite-based perovskite oxide (LaCrO3-based oxide), a lanthanum strontium titanium-based perovskite oxide (LaSrTiO3-based oxide), or the like may be used. These materials have conductivity, and are neither reduced nor oxidized even when in contact with a fuel gas such as a hydrogen-containing gas and an oxygen-containing gas such as air.
Next, a cell stack device 10 according to the present embodiment using the cell 1 described above will be described with reference to
As illustrated in
The fixing member 12 includes a fixing material 13 and a support member 14. The support member 14 supports the cells 1. The fixing material 13 fixes the cells 1 to the support member 14. Further, the support member 14 includes a support body 15 and a gas tank 16. The support body 15 and the gas tank 16, constituting the support member 14, are made of metal and electrically conductive.
As illustrated in
The gas tank 16 includes an opening portion through which a reaction gas is supplied to the plurality of cells 1 via the insertion hole 15a, and a recessed groove 16a located in the periphery of the opening portion. The outer peripheral end portion of the support body 15 is joined to the gas tank 16 by a jointing material 21 with which the recessed groove 16a of the gas tank 16 is filled.
In the example illustrated in
A hydrogen-rich fuel gas can be produced, for example, by steam reforming a raw fuel. When the fuel gas is produced by the steam reforming, the fuel gas contains steam.
In the example illustrated in
The insertion hole 15a has, for example, an oval shape in a top surface view. The length of the insertion hole 15a, for example, in an array direction of the cells 1, that is, the thickness direction T thereof, is greater than the distance between two end current collectors 17 located at two ends of the cell stack 11. The width of the insertion hole 15a is, for example, greater than the length of the cell 1 in the width direction W (see
As illustrated in
The fixing material 13 and the bonding material 21 may be of low conductivity, such as a glass. As the specific materials of the fixing material 13 and the jointing material 21, amorphous glass or the like may be used, and especially, crystallized glass or the like may be used.
As the crystallized glass, for example, any one of the group consisting of SiO2—CaO-based, MgO—B2O3-based, La2O3—B2O3—MgO-based, La2O3—B2O3—ZnO-based, and SiO2—CaO—ZnO-based materials may be used, or particularly, a SiO2—MgO-based material may be used.
As illustrated in
Further, as illustrated in
Further, as illustrated in
The positive electrode terminal 19A functions as a positive electrode when the electrical power generated by the cell stack 11 is output to the outside, and is electrically connected to the end current collector 17 on a positive electrode side in the cell stack 11A. The negative electrode terminal 19B functions as a negative electrode when the electrical power generated by the cell stack 11 is output to the outside, and is electrically connected to the end current collector 17 on a negative electrode side in the cell stack 11B.
The connection terminal 19C electrically connects the end current collector 17 on a negative electrode side in the cell stack 11A and the end current collector 17 on a positive electrode side in the cell stack 11B.
Details of the element portion 3 according to the first embodiment will be described with reference to
As illustrated in
Such non-film-forming portions A are located along at least two sides (top side and bottom side in the embodiment) of the cell 1. The non-film-forming portions A may have, for example, a predetermined width (for example, about 5 mm) from the sides, respectively. In the embodiment, the non-film-forming portions A have a substantially equal width along the top and bottom sides of the cell 1, respectively.
A reinforcing layer 23 is provided between the solid electrolyte layer 6 and the intermediate layer 7 above the non-film-forming portion A at the lower end portion of the cell 1. When the lower end portion of the cell 1 is fixed by a fixing member 12 (see
When the interconnector 4 does not extend to the lower end portion of the cell 1, the reinforcing layer 23 may be located on the flat surface n2 (see
The reinforcing layer 23 may be, for example, ZrO2 in which from 3 mole % to 15 mole % of a rare earth element oxide is contained as a solid solution. As the rare earth element oxide, for example, Y2O3 or the like may be used. As long as the reinforcing layer 23 has the above characteristics, the reinforcing layer 23 using other materials or the like may be disposed.
The air electrode 8 is located on the surface of the intermediate layer 7 in a region between the non-film-forming portion A on the upper side of the cell 1 and the reinforcing layer 23. As illustrated in
The end portions 8a are regions including a first end portion 8a1 and a second end portion 8a2 located at both ends in the width direction W when the air electrode 8 is viewed in plan view. The center portion 8b is a region sandwiched between the first end portion 8a1 and the second end portion 8a2 of the end portions 8a.
As illustrated in
In the embodiment, the distance X1 is, for example, 25% of a length W1 in the width direction W of the air electrode 8. The distance X2 is, for example, 25% of the length W1 in the width direction W of the air electrode 8.
In the present embodiment, the porosities of the end portions 8a and the center portion 8b described above are controlled to improve the battery performance of the cell 1.
That is, in the present embodiment, the porosity in the end portions 8a of the air electrode 8 is greater than the porosity in the center portion 8b.
As described above, by making the porosity in the end portions 8a of the air electrode 8 greater than the porosity in the center portion 8b, the end portions 8a of the air electrode 8 function as stress relaxation portions. This makes the air electrode 8 less likely to peel off from the intermediate layer 7. This can enhance the durability of the cell 1.
Additionally, by making the porosity in the end portions 8a of the air electrode 8 greater than the porosity in the center portion 8b, the oxygen-containing gas introduced from the end portion 8a sides of the air electrode 8 is easily transferred to the center portion 8b. This improves the power generation efficiency of the cell 1.
By making the porosity in the center portion 8b of the air electrode 8 smaller than the porosity in the end portions 8a, ionic conductivity in the center portion 8b of the air electrode 8, which has a greater contribution to power generation than the end portions 8a, is improved. This improves the power generation efficiency of the cell 1.
That is, in the element portion 3 according to the present embodiment, the porosity is increased in the end portion 8a of the air electrode 8 having a smaller contribution to power generation than the center portion 8b, emphasizing a stress relaxation effect rather than the power generation efficiency, while the porosity is decreased in the center portion 8b, emphasizing the power generation efficiency. This improves the battery performance of the cell 1.
On the other hand, when the porosity in the end portions 8a of the air electrode 8 is smaller than the porosity in the center portion 8b, the air electrode 8 may easily peel off from the intermediate layer 7, and the durability of the cell 1 may decrease.
When the porosity in the end portions 8a of the air electrode 8 is smaller than the porosity in the center portion 8b, the oxygen-containing gas is hardly introduced from the end portion 8a sides of the air electrode 8, and thus the oxygen-containing gas is not sufficiently supplied to the center portion 8b and is exhausted, i.e., so-called air shortage is likely to occur, and the power generation efficiency in the cell 1 may be reduced.
When the porosity in the center portion 8b of the air electrode 8 is greater than the porosity in the end portions 8a, the ionic conductivity in the center portion 8b of the air electrode 8 may be reduced, and the power generation efficiency of the cell 1 may be reduced.
Here, the porosity of the air electrode 8 can be, for example, in the range of from 20% to 50%, particularly from 30% to 50%. When the porosity of the air electrode 8 is smaller than 20%, the relaxation effect of stress due to voids decreases, and thus, the air electrode 8 may peel off when a temperature cycle is applied to the cell 1 and thermal stress is applied to the air electrode 8, for example.
The porosity in the end portions 8a of the air electrode 8 can be, for example, in the range of from 30% to 50%, particularly from 35% to 50%. However, the porosity in the end portions 8a of the air electrode 8 is not limited to the range described above, and may be greater than the porosity in the center portion 8b.
The porosity in the center portion 8b of the air electrode 8 can be, for example, in the range of from 20% to 40%, particularly from 20% to 35%. However, the porosity in the center portion 8b of the air electrode 8 is not limited to the range described above, and may be smaller than the porosity in the end portions 8a.
Returning to
The second intermediate layer 9 is a so-called Ce—Zr solid solution including Ce and Zr. The second intermediate layer 9 is interposed between the solid electrolyte layer 6 and the intermediate layer 7, and thus adhesiveness between the intermediate layer 7 as the first intermediate layer and the solid electrolyte layer 6 is further improved. Thus, the air electrode 8 together with the intermediate layer 7 is further less likely to peel off from the solid electrolyte layer 6. This can enhance the durability of the cell 1.
The second intermediate layer 9 is located so as to at least partially overlap the end portions 8a of the air electrode 8 in plan view. The second intermediate layer 9 functions as the diffusion prevention layer. The second intermediate layer 9 makes Sr and other components contained in the air electrode 8 less likely to diffuse into the solid electrolyte layer 6 via the intermediate layer 7, thereby reducing the problem that a resistive layer is formed on the solid electrolyte layer 6.
On the other hand, the second intermediate layer 9 has a side surface as a resistive layer having low conductivity. Thus, the second intermediate layer 9 can be located not on the entire element portion 3, but along each side of the air electrode 8 in plan view, which has a limited contribution to power generation efficiency.
That is, in the example illustrated in
In the example illustrated in
An end portion of the second intermediate layer 9 need not be located so as to overlap an end portion of the element portion 3 illustrated in
A module 100 according to an embodiment of the present disclosure using the cell stack device 10 described above will be described with reference to
As illustrated in
The reformer 102 generates a fuel gas by reforming a raw fuel such as natural gas and kerosene, and supplies the fuel gas to the cell 1. The raw fuel is supplied to the reformer 102 through the raw fuel supply pipe 103. The reformer 102 may include a vaporizing unit 102a for vaporizing water and a reforming unit 102b. The reforming unit 102b includes a reforming catalyst (not illustrated) for reforming the raw fuel into a fuel gas. Such a reformer 102 can perform steam reforming, which is a highly efficient reforming reaction.
Then, the fuel gas generated by the reformer 102 is supplied to the gas-flow passage 2a (see
In the module 100 having the configuration mentioned above, the temperature in the module 100 during normal power generation is about from 500° C. to 1000° C. due to combustion of gas and power generation by the cell 1.
With the module 100 having such a configuration, as described above, the module 100 can be obtained that is improved in battery performance by being configured to house the cell stack device 10 that is improved in battery performance.
The external case 111 of the module housing device 110 illustrated in
The dividing plate 114 includes an air circulation hole 117 for causing air in the auxiliary device housing room 116 to flow into the module housing room 115 side. The external plates 113 constituting the module housing room 115 includes an exhaust hole 118 for discharging air inside the module housing room 115.
With the module housing device 110 having such a configuration, as described above, the module housing device 110 can be obtained that is improved in battery performance by including, in the module housing room 115, the module 100 improved in battery performance.
In the example illustrated in
As illustrated in
As illustrated in
As illustrated in
In the present variation, the distance X1 is, for example, 25% of the length W1 in the width direction W of the air electrode 8. The distance X2 is, for example, 25% of the length W1 in the width direction W of the air electrode 8. The distance X3 is, for example, 15% of the length L1 of the length direction L of the air electrode 8. The distance X4 is, for example, 15% of the length L1 of the length direction L of the air electrode 8.
Subsequently, a cell stack device and a cell according to the second embodiment will be described with reference to
In the embodiment described above, a so-called “vertically striped type” cell stack device, in which only one element portion including a fuel electrode, a solid electrolyte layer, and an air electrode is provided on the surface of the support substrate, is exemplified. However, the present disclosure can be applied to a horizontally striped type cell stack device with an array of so-called “horizontally striped type” cells, in which a plurality of element portions are provided on the surface of a support substrate at mutually separated locations, and adjacent element portions are electrically connected to each other.
The cell 1A has a shape that is vertically symmetric with respect to a plane that passes through a center in the thickness direction (Z-axis direction) and parallel to a main surface of the support substrate 2.
The element portion 3 includes the fuel electrode 5, the solid electrolyte layer 6, the intermediate layer 7, and the air electrode 8 layered in this order. The connection layers 8A for electrically connecting the element portions 3 adjacent to each other in the X axis direction are located on the surface of the air electrode 8. Further, a fuel electrode current collecting portion 5A having electron conductivity is located on the surface of the fuel electrode 5.
The air electrode 8 according to the present embodiment has different porosities for each portion as in the air electrode 8 according to the first embodiment.
The end portions 8a are regions constituted by a first end portion 8a1 and a second end portion 8a2 located at both ends in a Y-axis direction when the air electrode 8 is viewed in plan view. The center portion 8b is a region sandwiched between the first end portion 8a1 and the second end portion 8a2 of the end portions 8a.
As illustrated in
Note that in
As described above, by making the porosity in the end portions 8a of the air electrode 8 greater than the porosity in the center portion 8b, the end portions 8a of the air electrode 8 function as stress relaxation portions. This makes the air electrode 8 less likely to peel off from the intermediate layer 7. Thus, the durability of the cell 1A can be enhanced.
By making the porosity in the end portions 8a of the air electrode 8 greater than the porosity in the center portion 8b, the oxygen-containing gas introduced from the end portion 8a sides of the air electrode 8 is easily transferred to the center portion 8b. Thus, the power generation efficiency in the cell 1A is improved.
By making the porosity in the center portion 8b of the air electrode 8 smaller than the porosity in the end portions 8a, ionic conductivity in the center portion 8b of the air electrode 8, which has a greater contribution to power generation than the end portions 8a, is improved. Thus, the power generation efficiency in the cell 1A is improved.
That is, in the element portion 3 according to the present embodiment, the porosity is increased in the end portion 8a of the air electrode 8 having a smaller contribution to power generation than the center portion 8b, emphasizing a stress relaxation effect rather than the power generation efficiency, while the porosity is decreased in the center portion 8b, emphasizing the power generation efficiency. This improves the battery performance of the cell 1A.
Subsequently, a cell stack device according to other modifications of the embodiment will be described.
In the embodiments mentioned above, the case where a support substrate of the hollow flat plate type is used has been exemplified; however, the embodiments can also be applied to a cell stack device using a cylindrical support substrate or a cell stack device of the flat plate type.
In the above embodiments, an example in which a fuel electrode is provided on a support substrate and an air electrode is disposed on a surface of a cell, is illustrated. However, the present disclosure can also be applied to a cell stack device that has an opposite arrangement to the above, that is, an arrangement in which an air electrode is provided on a support substrate and a fuel electrode is disposed on a surface of a cell.
Further, in the aforementioned embodiments, the “cell”, the “cell stack device”, the “module”, and the “module housing device” are exemplified by the fuel cell, a fuel cell stack device, a fuel cell module, and a fuel cell device, respectively, but they may also be exemplified by an electrolytic cell, an electrolytic cell stack device, an electrolytic module, and an electrolytic device, respectively.
While the present disclosure has been described in detail, the present disclosure is not limited to the aforementioned embodiments, and various changes, improvements, and the like can be made without departing from the gist of the present disclosure.
As described above, the cell 1 according to the embodiments includes the element portion 3 that includes the fuel electrode 5, the solid electrolyte layer 6, the air electrode 8, and the intermediate layer 7. The intermediate layer 7 is provided between the solid electrolyte layer 6 and the air electrode 8. The porosity in the end portions 8a of the air electrode 8 in plan view is greater than the porosity in the center portion 8b of the air electrode 8. This can improve the battery performance of the cell 1.
Also, the cell stack device 10 according to the embodiments includes the cell stack 11 including the plurality of cells 1 mentioned above. As a result, the cell stack device 10 can be obtained that is improved in battery performance.
Further, the module 100 according to the embodiments includes the cell stack device 10 described above, and the housing container 101 that houses the cell stack device 10. As a result, the module 100 can be obtained that is improved in battery performance.
Further, the module housing device 110 according to the embodiments includes the module 100 described above, the auxiliary device for operating the module 100, and the external case that houses the module 100 and the auxiliary device. As a result, the module housing device 110 can be obtained that is improved in battery performance.
Noted that the embodiments disclosed herein are exemplary in all respects and not restrictive. Indeed, the aforementioned embodiments can be embodied in a variety of forms. Furthermore, the aforementioned embodiments may be omitted, replaced, or changed in various forms without departing from the scope of the appended claims and the purpose thereof.
Number | Date | Country | Kind |
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2020-140866 | Aug 2020 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2021/031007 | 8/24/2021 | WO |