Cell Stack Device, Module, and Module Housing Device

Abstract

A highly durable composite member, a cell stack device, a module, and a module housing device are provided. [Solution] The composite member includes a substrate and a coating layer. The substrate has a first surface that is not exposed to an oxidizing atmosphere and contains chromium. The coating layer covers the first surface and has a first outer surface that is not exposed to the oxidizing atmosphere. At least one of the substrate and the coating layer has an exposed surface that is exposed to the oxidizing atmosphere. The surface roughness of the exposed surface is different from the surface roughness of the first surface or the first outer surface.

Description

Technical Field

[0001] The present disclosure , ce relates to a stack device, a module, and a module housing device.

Background Art

[0002] In recent years, various fuel cell stack devices having a plurality of fuel cells have been proposed as next-generation energy. A fuel cell is a type of cell that can obtain electric power using a fuel gas such as a hydrogen-containing gas and an oxygen-containing gas such as air.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A composite member according to an aspect of an embodiment includes a base material and a coating layer. The base material has a first surface that is not exposed to an oxidizing atmosphere and contains chromium. The coating layer covers the first surface and has a first outer surface that is not exposed to an oxidizing atmosphere. At least one of the base material and the coating layer has an exposed surface that is exposed to an oxidizing atmosphere. The surface roughness of the exposed surface is different from the surface roughness of the first surface or the first outer surface.

[0005] Further, a cell stack device of the present disclosure includes a plurality of cells, the composite member described above, and a bonding material. The plurality of cells have an element portion and include a first cell. The bonding material is located between the element portion and the first outer surface of the coating layer. The base material has the first surface facing the first cell and a second surface that includes the exposed surface and does not face the first cell. The surface roughness of the second surface is smaller than the surface roughness of the first surface.

[0006] Further, a module of the present disclosure includes the cell stack device described above and a storage container that stores the cell stack device.

[0007] In addition, the module housing device of the present disclosure includes the module described above, auxiliary equipment for operating the module, and an exterior case for housing the module and the auxiliary equipment.

Brief Description of the Drawings

[0008]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 6C

Figure 7

Figure 8

Figure 9A

Figure 9B

Figure 10A

Figure 10B

Figure 10C

Figure 11

Figure 12

Figure 13A

Figure 13B

Figure 13C

Figure 13D

MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, with reference to the accompanying drawings, embodiments of the fuel stack device, modules, and module housing device of the present application will be described in detail. Note that the present disclosure is not limited by the embodiments shown below. ru ce

[0010] Also, note that the drawings are schematic, and it is necessary to be aware that the dimensional relationships of each element, the ratios of each element, etc. may differ from reality. Furthermore, there may be parts where the dimensional relationships and ratios between the drawings are different from each other.

[0011] <Cell Configuration> First, with reference to FIGS. 1A to 1C, as an example of a cell constituting the cell stack device according to the embodiment, an example of a solid oxide fuel cell is used for explanation.

[0012] FIG. 1A is a cross-sectional view showing an example of cell 1 according to the embodiment, FIG. 1B is a side view of cell 1 according to the embodiment as viewed from the air electrode 5 side, and FIG. 1C is a side view of cell 1 according to the embodiment as viewed from the interconnect 6 side. Note that FIGS. 1A to 1C show a partial enlargement of each configuration of cell 1.

[0013] In the example shown in FIGS. 1A to 1C, cell 1 is a hollow flat plate type and is an elongated plate shape. As shown in FIG. 1B, the shape of cell 1 as viewed from the side is, for example, a rectangle with a length of the side in the length direction L of 5 cm to 50 cm and a length of the width direction W orthogonal to this length direction L of 1 cm to 10 cm. The thickness of cell 1 in the overall thickness direction T is 1 mm to 5 mm.

[0014] As shown in FIG. 1A, cell 1 includes a conductive support substrate 2, an element portion, and an interconnect 6. The support substrate 2 is columnar and has a pair of opposing flat surfaces n1, n2, and a pair of arc-shaped side surfaces m connecting such flat surfaces n1, n2.

[0015] ​The element part is provided on the flat surface n1 of the support substrate 2. Such an element part has a fuel electrode 3, a solid electrolyte layer 4, and an air electrode 5. Also, in the example shown in FIG. 1A, an interconnector 6 is provided on the flat surface n2.

[0016] Also, as shown in FIG. 1B, the air electrode 5 does not extend to the lower end of the cell 1. At the lower end part of the cell 1, only the solid electrolyte layer 4 is exposed on the surface. Also, as shown in FIG. 1C, the interconnector 6 extends to the lower end of the cell 1. At the lower end part of the cell 1, the interconnector 6 and the solid electrolyte layer 4 are exposed on the surface. Note that, as shown in FIG. 1A, on the surface of the pair of arc-shaped side surfaces m of the cell 1, the solid electrolyte layer 4 is exposed.

[0017] Hereinafter, each component constituting the cell 1 will be described.

[0018] The support substrate 2 has a gas flow path 2a inside through which gas flows. The example of the support substrate 2 shown in FIG. 1A has six gas flow paths 2a. The support substrate 2 has gas permeability and permeates the fuel gas flowing through the gas flow path 2a to the fuel electrode 3. The support substrate 2 may have conductivity. The support substrate 2 having conductivity collects the electricity generated in the element part to the interconnector 6.

[0019] The material of the support substrate 2 contains, 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. The inorganic oxide may be, for example, a specific rare earth element oxide.

[0020] As the material of the fuel electrode 3, generally known materials can be used. The fuel electrode 3 may be made of, for example, porous conductive ceramics such as ZrO2 in which calcium oxide, magnesium oxide, or rare earth element oxides are solid-solved, and ceramics containing Ni and / or NiO. As this rare earth element oxide, for example, Y2O3 or the like is used. ZrO2 in which calcium oxide, magnesium oxide, or rare earth element oxides are solid-solved may also be referred to as stabilized zirconia. Stabilized zirconia includes partially stabilized zirconia.

[0021] The solid electrolyte layer 4 is an electrolyte that bridges ions between the fuel electrode 3 and the air electrode 5. At the same time, the solid electrolyte layer 4 has gas barrier properties and makes it difficult for fuel gas and oxygen-containing gas to leak.

[0022] The material of the solid electrolyte layer 4 may be, for example, ZrO2 in which 3 mol% to 15 mol% of rare earth element oxides are solid-solved. As this rare earth element oxide, for example, Y2O3 or the like is used. As long as the above characteristics are satisfied, other materials or the like may be used as the material of the solid electrolyte layer 4.

[0023] The material of the air electrode 5 is not particularly limited as long as it is generally used for air electrodes. The material of the air electrode 5 may be, for example, conductive ceramics such as so-called ABO3-type perovskite oxides.

[0024] The material of the air electrode 5 may be, for example, a composite oxide in which Sr and La coexist at the A site. Examples of such composite oxides include La x Sr 1-x Co y Fe 1-y O3, La x Sr 1-x MnO3, La x Sr 1-x FeO3, La x Sr 1-x CoO3 and the like. Here, x satisfies 0 < x < 1, and y satisfies 0 < y < 1.

[0025] Further, the air electrode 5 has gas permeability. The open porosity of the air electrode 5 may be, for example, 20% or more, particularly in the range of 30% to 50%.

[0026] As the material of the interconnector 6, 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 not reduced or oxidized even when they come into contact with fuel gases such as hydrogen-containing gases and oxygen-containing gases such as air.

[0027] Further, the interconnector 6 is dense and less likely to cause leakage of the fuel gas flowing through the gas flow path 2a located inside the support substrate 2 and the oxygen-containing gas flowing outside the support substrate 2. The interconnector 6 preferably has a relative density of 93% or more, particularly 95% or more.

[0028] <Configuration of the cell stack device> Next, the cell stack device 10 according to the present embodiment using the cell 1 described above will be described with reference to FIGS. 2A to 2C. FIG. 2A is a perspective view showing an example of the cell stack device 10 according to the embodiment, FIG. 2B is a cross-sectional view taken along line A-A shown in FIG. 2A, and FIG. 2C is a top view showing an example of the cell stack device 10 according to the embodiment.

[0029] As shown in FIG. 2A, the cell stack device 10 includes a cell stack 11 having a plurality of cells 1 arranged (stacked) in the thickness direction T (see FIG. 1A) of the cell 1, and a fixing member 12.

[0030] The fixing member 12 has a bonding material 13 and a support member 14. The support member 14 supports the cell 1. The bonding material 13 bonds the cell 1 and the support member 14. Further, the support member 14 has a support body 15 and a gas tank 16. The support body 15 and the gas tank 16, which are the support members 14, are made of, for example, metal.

[0031] As shown in FIG. 2B, the support 15 has insertion holes 15a into which the lower ends of the plurality of cells 1 are inserted. The lower ends of the plurality of cells 1 and the inner walls of the insertion holes 15a are joined by a joining material 13.

[0032] The gas tank 16 has an opening for supplying reaction gas to the plurality of cells 1 through the insertion holes 15a and a concave groove 16a located around such an opening. The end of the outer periphery of the support 15 is fixed to the gas tank 16 by a fixing material 21 filled in the concave groove 16a of the gas tank 16.

[0033] In the example shown in FIG. 2A, fuel gas is stored in an internal space 22 formed by the support 15, which is a support member 14, and the gas tank 16. A gas flow pipe 20 is connected to the gas tank 16. The fuel gas is supplied to the gas tank 16 through this gas flow pipe 20 and is supplied from the gas tank 16 to the gas flow path 2a (see FIG. 1A) inside the cell 1. The fuel gas supplied to the gas tank 16 is generated by a reformer 102 (see FIG. 11) described later.

[0034] A hydrogen-rich fuel gas can be generated by steam reforming or the like of a raw fuel. When generating a fuel gas by steam reforming, the fuel gas contains steam.

[0035] In the example shown in FIG. 2A, it includes two rows of cell stacks 11, two supports 15, and a gas tank 16. Each of the two rows of cell stacks 11 has a plurality of cells 1. Each cell stack 11 is fixed to each support 15. The gas tank 16 has two through holes on its upper surface. Each support 15 is disposed in each through hole. The internal space 22 is formed by one gas tank 16 and two supports 15.

[0036] The shape of the insertion hole 15a is, for example, oval in a top view. The insertion hole 15a is, for example, such that the length in the arrangement direction of the cells 1, that is, the thickness direction T, is larger than the distance between two end collector members 17 located at both ends of the cell stack 11. The width of the insertion hole 15a is, for example, larger than the length in the width direction W (see FIG. 1A) of the cell 1.

[0037] As shown in FIG. 2B, the joint portion between the inner wall of the insertion hole 15a and the lower end portion of the cell 1 is filled with the joining material 13 and solidified. Thereby, the inner wall of the insertion hole 15a and the lower end portions of the plurality of cells 1 are joined and fixed respectively, and the lower end portions of the cells 1 are joined and fixed to each other. The gas flow path 2a of each cell 1 communicates with the internal space 22 of the support member 14 at the lower end portion.

[0038] As the joining material 13 and the fixing material 21, those with low conductivity such as glass can be used. As specific materials for the joining material 13 and the fixing material 21, amorphous glass or the like may be used, and particularly, crystallized glass or the like may be used.

[0039] As the crystallized glass, for example, any of materials such as SiO2-CaO system, MgO-B2O3 system, La2O3-B2O3-MgO system, La2O3-B2O3-ZnO system, SiO2-CaO-ZnO system may be used, and particularly, a material of SiO2-MgO system may be used.

[0040] Also, as shown in FIG. 2B, a conductive member 18 is interposed between adjacent cells 1 among the plurality of cells 1. The conductive member 18 electrically connects the fuel electrode 3 of one adjacent cell 1 and the air electrode 5 of the other cell 1 in series. More specifically, it connects an interconnector electrically connected to the fuel electrode 3 of one adjacent cell 1 and the air electrode 5 of the other cell 1.

[0041] Also, as shown in FIG. 2B, an end collector member 17 is electrically connected to the cell 1 located at the outermost side in the arrangement direction of the plurality of cells 1. The end collector member 17 is connected to a conductive portion 19 protruding outside the cell stack 11. The conductive portion 19 collects the electricity generated by the power generation of the cell 1 and draws it out to the outside. In FIG. 2A, the illustration of the end collector member 17 is omitted.

[0042] Further, as shown in FIG. 2C, in the cell stack device 10, two cell stacks 11A and 11B are connected in series and function as one battery. Therefore, the conductive portion 19 of the cell stack device 10 is distinguished into a positive electrode terminal 19A, a negative electrode terminal 19B, and a connection terminal 19C.

[0043] The positive electrode terminal 19A is the positive electrode when the cell stack 11 outputs the generated power to the outside, and is electrically connected to the end collector member 17 on the positive electrode side in the cell stack 11A. The negative electrode terminal 19B is the negative electrode when the cell stack 11 outputs the generated power to the outside, and is electrically connected to the end collector member 17 on the negative electrode side in the cell stack 11B.

[0044] The connection terminal 19C electrically connects the end collector member 17 on the negative electrode side in the cell stack 11A and the end collector member 17 on the positive electrode side in the cell stack 11B.

[0045] <Bonding of the composite member and the cell> Next, the bonding of the composite member and the cell will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view taken along the line Y-Y shown in FIG. 2C.

[0046] As shown in FIG. 3, the support 15 is bonded to the cell 1 as the first cell via the bonding material 13.

[0047] The support 15 is a composite member having a base material 151 and a coating layer 152. The base material 151 has heat resistance. The base material 151 contains chromium. The base material 151 is, for example, stainless steel. The base material 151 may contain, for example, a metal oxide.

[0048] The coating layer 152 covers the base material 151. The coating layer 152 is located between the first surface 151a of the base material 151 and the bonding material 13.

[0049] The material of the coating layer 152 is, for example, an inorganic oxide. The inorganic oxide may be, for example, aluminum oxide (alumina), magnesium oxide (magnesia), silicon oxide (silica), zirconium oxide (zirconia), chromium oxide (chromia), titanium oxide (titania), and composite oxides thereof. The zirconia may be stabilized zirconia. The composite oxide may be selected from, for example, forsterite and cordierite. The material of the coating layer 152 may be a material with low conductivity or an insulating material. By the material of the coating layer 152 being a material with low conductivity or an insulating material, the cell stack device 10 having a high breakdown voltage and a high insulation resistance can be achieved.

[0050] In particular, alumina and forsterite have a small difference in the coefficient of thermal expansion from the base material 151, and when these are used for the coating layer 152, the thermal stress generated between the base material 151 due to the temperature difference becomes small. Therefore, the coating layer 152 can be firmly joined to the base material 151, and the coating layer 152 is less likely to peel off from the base material 151.

[0051] Also, the joining material 13 joins the cell 1 as the first cell and the support 15. The joining material 13 is located between the solid electrolyte layer 4 of the cell 1 and the coating layer 152 of the support 15, and joins the cell 1 and the first surface 152a of the coating layer 152. The first surface 152a is an example of the first outer surface.

[0052] By being located between the joining material 13 and the base material 151, the coating layer 152 relaxes the stress generated between the joining material 13 and the base material 151, for example, due to the difference in the coefficient of thermal expansion, and reduces the crack generation in the joining material 13.

[0053] However, the support 15 is made of a different material, and depending on the operating environment, cracks may occur in the coating layer 152, or the coating layer 152 may peel off from the base material 151. As a result, fuel gas may leak from the gap generated in the support 15, and there is still a risk of deterioration in the durability of the cell stack device 10. In addition, chromium (Cr) contained in the support 15 may desorb into the oxidizing atmosphere and reach the cell 1, resulting in a decrease in the performance of the cell 1 and a risk of deterioration in the durability of the cell stack device 10.

[0054] Therefore, in the embodiment, the surface roughness of the surface of the base material 151 exposed to the oxidizing atmosphere is made different from the surface roughness of the surface not exposed to the oxidizing atmosphere. In the embodiment, the first surface 151a of the base material 151 that does not face the coating layer 152 and is not exposed to the oxidizing atmosphere has a larger surface roughness than the surface of other portions of the base material 151 exposed to the oxidizing atmosphere, for example, the second surface 151b.

[0055] Thereby, the adhesion between the coating layer 152 and the base material 151 can be enhanced. For this reason, it becomes difficult for the coating layer 152 to peel off from the base material 151, or it is possible to make it difficult for the coating layer 152 to break and for fuel gas to leak. Therefore, according to the embodiment, the durability of the support 15 can be enhanced.

[0056] On the other hand, the second surface 151b of the base material 151 where the coating layer 152 is not located is exposed to the external space 23. Such an external space 23 is a space where the air electrode 5 (see FIG. 1) of the cell 1 is exposed and is filled with an oxygen-containing gas such as air. That is, the external space 23 is an oxidizing atmosphere.

[0057] The base material 151 used in such an environment may reduce the specific surface area by reducing the surface roughness of the second surface 151b exposed to the oxidizing atmosphere of the external space 23. For example, in the embodiment, the second surface 151b has a smaller surface roughness than the first surface 151a.

[0058] This makes it difficult for chromium (Cr) contained in the base material 151 to desorb into the external space 23 which is an oxidizing atmosphere during high-temperature operation. Therefore, according to the embodiment, the performance of the cell 1 is less likely to deteriorate, and the durability of the cell stack device 10 can be enhanced.

[0059] <Various Modification Examples> Next, the support 15 according to various modification examples of the embodiment will be described with reference to FIGS. 4A to 10C. FIGS. 4A and 4B are perspective views showing another example of the composite member.

[0060] When using the flat support 15 as shown in FIG. 4A, an internal space 22 (see FIG. 4C) is formed by joining the gas tank 16 (see FIG. 2A) to the lower surface of the flat support 15. Further, the support 15 shown in FIG. 4B has a plurality of insertion holes 15a. In this case, one cell 1 may be inserted into each of the plurality of insertion holes 15a of the support 15, or a plurality of cells 1 may be inserted into each of the plurality of insertion holes 15a of the support 15.

[0061] FIG. 4C is an enlarged cross-sectional view of the joint portion between another example of the composite member and the cell. As shown in FIG. 4C, the support 15 has a flat shape. The support 15 is joined to the cell 1 by the joining material 13.

[0062] The support 15 has a base material 151 and a coating layer 152. The base material 151 has a first surface 151a, a second surface 151b, and an inner surface 151e. The first surface 151a faces the coating layer 152. The second surface 151b is exposed to the oxidizing atmosphere of the external space 23. The inner surface 151e is exposed to the reducing atmosphere of the internal space 22.

[0063] The coating layer 152 covers the base material 151. The coating layer 152 is located between the first surface 151a of the base material 151 and the joining material 13.

[0064] Further, the bonding material 13 bonds the cell 1 and the support 15. The bonding material 13 is located between the solid electrolyte layer 4 (see FIG. 1A) of the cell 1 and the coating layer 152 of the support 15, and bonds the cell 1 and the first surface 152a as the first outer surface of the coating layer 152.

[0065] In the support 15 according to the embodiment, the surface roughness of the first surface 151a of the base material 151 is greater than that of the second surface 151b of the base material 151 that is exposed to the oxidizing atmosphere of the external space 23.

[0066] Since the surface roughness of the first surface 151a facing the coating layer 152 is greater than that of the second surface 151b, the coating layer 152 can be made less likely to peel from the base material 151, or the coating layer 152 can be made less likely to break and cause fuel gas leakage. Therefore, according to the embodiment, the durability of the support 15 can be enhanced.

[0067] Furthermore, since the surface roughness of the second surface 151b is smaller than that of the first surface 151a, chromium (Cr) contained in the base material 151 during high-temperature operation can be made less likely to desorb into the oxidizing atmosphere of the external space 23. Therefore, according to the embodiment, the performance of the cell 1 is less likely to deteriorate, and the durability of the cell stack device 10 can be enhanced.

[0068] FIGS. 5A and 5B are enlarged cross-sectional views of the joint between the composite member and the cell according to Modifications 2 and 3 of the embodiment. FIGS. 6A and 6B are enlarged cross-sectional views of the joint between another example of the composite member and the cell according to Modifications 4 and 5 of the embodiment.

[0069] As shown in FIGS. 5A and 6A, the base material 151 of the support 15 may further have an intermediate surface 151c located between the first surface 151a and the second surface 151b. The intermediate surface 151c is an example of the third surface.

[0070] The intermediate surface 151c faces the coating layer 152. The intermediate surface 151c has, for example, a smaller surface roughness than the first surface 151a.

[0071] The intermediate surface 151c is located at a site closer to the oxidation atmosphere than the first surface 151a. For example, during high-temperature operation, chromium (Cr) contained in the base material 151 may desorb into the oxidation atmosphere of the external space 23 through the interface between the coating layer 152 and the base material 151 and the vicinity thereof. By making the surface roughness of the intermediate surface 151c smaller than that of the first surface 151a, which is located at a site away from the oxidation atmosphere, among the portions of the base material 151 facing the coating layer 152, for example, chromium (Cr) contained in the base material 151 during high-temperature operation can be made less likely to desorb into the oxidation atmosphere of the external space 23. Therefore, according to the embodiment, the performance of the cell 1 is less likely to deteriorate, and the durability of the cell stack device 10 can be enhanced. Note that the surface roughness of the intermediate surface 151c may be the same as, for example, the surface roughness of the second surface 151b. Also, the intermediate surface 151c may have, for example, a surface roughness intermediate between the first surface 151a and the second surface 151b.

[0072] On the other hand, as shown in FIGS. 5B and 6B, the base material 151 of the support 15 may further have an intermediate surface 151d located between the first surface 151a and the second surface 151b. The intermediate surface 151d is an example of the third surface.

[0073] The intermediate surface 151d is exposed to the oxidation atmosphere of the external space 23. The intermediate surface 151d may have, for example, a larger surface roughness than the second surface 151b. Note that the surface roughness of the intermediate surface 151d may be the same as, for example, the surface roughness of the first surface 151a. Also, the intermediate surface 151d may have, for example, a surface roughness intermediate between the first surface 151a and the second surface 151b.

[0074] Also, in each of the modification examples of FIGS. 5A to 6B, although an example having only one of the intermediate surfaces 151c and 151d is shown, both the intermediate surfaces 151c and 151d may be provided.

[0075] FIG. 6C is an enlarged cross-sectional view of a joint portion between another example of a composite member according to Modification Example 5 of the embodiment and a cell.

[0076] As shown in FIG. 6C, the coating layer 152 of the support 15 has the same configuration as the support 15 shown in FIG. 6A, except that it is located closer to the oxidizing atmosphere of the external space 23 than the first surface 152a and has a surface 152c facing the bonding material 13.

[0077] The surface 152c may have, for example, a smaller surface roughness than the first surface 152a. By making the surface roughness of the surface 152c smaller than that of the first surface 152a in the coating layer 152 facing the bonding material 13, at a site farther from the oxidizing atmosphere, for example, chromium (Cr) contained in the base material 151 during high-temperature operation can be made less likely to further desorb into the oxidizing atmosphere of the external space 23. Therefore, according to the embodiment, the performance of the cell 1 is less likely to deteriorate, and the durability of the cell stack device 10 can be enhanced.

[0078] Also, the surface 152c may have, for example, a larger surface roughness than the first surface 152a. By making the surface roughness of the surface 152c larger than that of the first surface 152a in the coating layer 152 facing the bonding material 13, for example, the adhesion between the bonding material 13 and the coating layer 152 of the support 15 located at a site closer to the oxidizing atmosphere can be enhanced. For this reason, the bonding material 13 and the coating layer 152 of the support 15 are less likely to peel off, or the bonding material 13 or the coating layer 152 is less likely to break, and as a result, leakage of the fuel gas can be made less likely to occur. Therefore, according to the embodiment, the durability of the support 15 can be enhanced.

[0079] FIG. 7 is an enlarged cross-sectional view of the joint portion between the composite member and the cell according to Modification 6 of the embodiment. FIG. 8 is an enlarged cross-sectional view of the joint portion between another example of the composite member according to Modification 7 of the embodiment and the cell.

[0080] As shown in FIGS. 7 and 8, the coating layer 152 of the support 15 has the same configuration as the support 15 shown in FIGS. 3 and 4C, except that it further covers the second surface 151b of the base material 151.

[0081] The coating layer 152 has a first surface 152a facing the bonding material 13 and a second surface 152b exposed to the oxidizing atmosphere of the external space 23. The first surface 152a is an example of the first outer surface. The second surface 152b is an example of the second outer surface.

[0082] In the support 15 according to Modifications 6 and 7 of the embodiment, the surface roughness of the surface of the coating layer 152 exposed to the oxidizing atmosphere is different from the surface roughness of the surface of the base material 151 not exposed to the oxidizing atmosphere. For example, the surface roughness of the second surface 151b of the base material 151 that is not exposed to the oxidizing atmosphere is greater than the surface roughness of the second surface 152b of the coating layer 152 that is exposed to the oxidizing atmosphere.

[0083] Since the surface roughness of the second surface 151b facing the coating layer 152 is greater than the surface roughness of the second surface 152b, the adhesion between the coating layer 152 and the base material 151 is enhanced. For this reason, the coating layer 152 is less likely to peel off from the base material 151, or the coating layer 152 is less likely to break, and as a result, it is possible to make it less likely for fuel gas to leak. Therefore, according to the embodiment, the durability of the support 15 can be enhanced. In addition, it is possible to make it difficult for chromium (Cr) contained in the base material 151 during high-temperature operation to desorb into the oxidizing atmosphere of the external space 23 from the peeled or broken portion. Therefore, according to the embodiment, since the performance of the cell 1 is less likely to deteriorate, the durability of the fuel cell stack device 10 can be enhanced.

[0084] Furthermore, since the surface roughness of the second surface 152b exposed to the oxidizing atmosphere of the external space 23 is smaller than the surface roughness of the second surface 151b covered by the coating layer 152, it is possible to make it difficult for chromium (Cr) contained in the base material 151 during high-temperature operation to desorb into the oxidizing atmosphere of the external space 23 through the second surface 152b of the coating layer 152. Therefore, according to the embodiment, since the durability of the support 15 can be enhanced, the durability of the fuel cell stack device 10 can be enhanced.

[0085] On the other hand, in the support 15 according to Modifications 6 and 7 of the embodiment, for example, the surface roughness of the first surface 152a of the coating layer 152 that is not exposed to the oxidizing atmosphere may be greater than the surface roughness of the second surface 152b of the coating layer 152 that is exposed to the oxidizing atmosphere.

[0086] Since the surface roughness of the first surface 152a facing the bonding material 13 is greater than the surface roughness of the second surface 152b exposed to the oxidizing atmosphere of the external space 23, the adhesion between the coating layer 152 and the bonding material 13 is enhanced. For this reason, the bonding material 13 is less likely to peel from the base material 151, or the coating layer 152 is less likely to break, and as a result, leakage of the fuel gas can be made less likely to occur. Therefore, according to the embodiment, the durability of the support 15 can be enhanced.

[0087] Furthermore, since the surface roughness of the second surface 152b is smaller than the surface roughness of the first surface 152a, chromium (Cr) contained in the base material 151 during high-temperature operation can be made less likely to desorb into the oxidizing atmosphere of the external space 23 through the coating layer 152. Therefore, according to the embodiment, since the performance of the cell 1 is less likely to deteriorate, the durability of the fuel cell stack device 10 can be enhanced.

[0088] In the support 15 shown in FIGS. 7 and 8, the surface roughness of the second surface 151b of the base material 151 may be greater than that of the first surface 151a, or they may be the same. However, if the surface roughness of the second surface 151b is made smaller than that of the first surface 151a, chromium (Cr) contained in the base material 151 during high-temperature operation can be made even less likely to desorb into the oxidizing atmosphere of the external space 23. Therefore, according to the embodiment, since the performance of the cell 1 is even less likely to deteriorate, the durability of the fuel cell stack device 10 can be enhanced.

[0089] Also, in the modification shown in FIG. 8, the end face 131a of the bonding material 13 exposed to the oxidizing atmosphere of the external space 23 and the second surface 152b of the coating layer 152 are flush with each other. However, the present invention is not limited to this, and for example, the second surface 152b may be positioned so as to protrude from the end face 131a toward the external space 23, which is an oxidizing atmosphere.

[0090] FIG. 9A and FIG. 9B are enlarged cross-sectional views of the joint between the composite member and the cell according to Modifications 8 and 9 of the embodiment. FIG. 10A and FIG. 10B are enlarged cross-sectional views of the joint between another example of the composite member and the cell according to Modifications 10 and 11 of the embodiment.

[0091] As shown in FIGS. 9A and 10A, the coating layer 152 of the support 15 may further have a surface 152c which is an intermediate surface located between the first surface 152a and the second surface 152b. The surface 152c is an example of a third outer surface.

[0092] The surface 152c faces the bonding material 13. The surface 152c has, for example, a smaller surface roughness than the first surface 152a.

[0093] Also, the surface 152c is located at a site closer to the oxidation atmosphere than the first surface 152a. For example, during high-temperature operation, chromium (Cr) contained in the base material 151 may desorb into the external space 23 which is an oxidation atmosphere through the interface between the bonding material 13 and the coating layer 152 and the vicinity thereof. By making the surface roughness of the surface 152c smaller than that of the first surface 152a at the site of the coating layer 152 facing the bonding material 13 and located away from the oxidation atmosphere of the external space 23, for example, it is possible to suppress chromium (Cr) contained in the base material 151 from desorbing into the oxidation atmosphere through the interface between the bonding material 13 and the coating layer 152 and the vicinity thereof during high-temperature operation. Therefore, according to the embodiment, since the performance of the cell 1 is less likely to deteriorate, the durability of the cell stack device 10 can be enhanced. Note that the surface roughness of the surface 152c may be the same as, for example, the surface roughness of the second surface 152b. Also, the surface 152c may have, for example, an intermediate surface roughness between the first surface 152a and the second surface 152b.

[0094] On the other hand, as shown in FIGS. 9B and 10B, the coating layer 152 of the support 15 may further have an intermediate surface 152d located between the first surface 152a and the second surface 152b. The intermediate surface 152d is an example of a third outer surface.

[0095] The intermediate surface 152d is exposed to the oxidizing atmosphere of the external space 23. The intermediate surface 152d has, for example, a larger surface roughness than the second surface 152b. Even in the case of having such an intermediate surface 152d, chromium (Cr) contained in the base material 151 can be made less likely to desorb into the oxidizing atmosphere of the external space 23 during high-temperature operation. Therefore, according to the embodiment, since the performance of the cell 1 is less likely to deteriorate, the durability of the cell stack device 10 can be enhanced. Note that the surface roughness of the intermediate surface 152d may be the same as, for example, the surface roughness of the first surface 152a. Also, the intermediate surface 152d may have, for example, a surface roughness intermediate between the first surface 152a and the second surface 152b.

[0096] Also, in each of the modification examples of FIGS. 9A to 10B, an example having the surface 152c or the intermediate surface 152d has been shown, but it may have both the surface 152c and the intermediate surface 152d.

[0097] FIG. 10C is an enlarged cross-sectional view of a composite member according to Modification Example 12 of the embodiment. As shown in FIG. 10C, the coating layer 152 may have one or a plurality of particulate bodies P. When defining an intermediate portion cp located between the first surface 152a and the inner surface 152e of the coating layer 152, the particulate body P is located in an internal region 152g from the intermediate portion cp to the inner surface 152e.

[0098] Also, the material of the particulate body P is, for example, alumina or silicon carbide. The material of the particulate body P is not located in the external region 152f from the first surface 152a to the intermediate portion cp and the base material 151. When the distance between the first surface 152a and the inner surface 152e is t, the particulate body P is located in the internal region 152g which is a portion within t / 2 from the inner surface 152e. That is, the particle size of the particulate body P is t / 2 or less.

[0099] By positioning the particulate P in the internal region 152g of the coating layer 152 in this manner, for example, the adhesion between the coating layer 152 and the base material 151 is improved. Therefore, according to the embodiment, since the durability of the support 15 can be enhanced, the durability of the cell stack device 10 can be enhanced. In FIG. 10C, an example in which the particulate P is positioned between the inner surface 152e facing the base material 151 and the first surface 152a is illustrated, but the present invention is not limited thereto, and for example, it may be positioned between the inner surface 152e and the second surface 152b.

[0100] (Evaluation method) Here, the magnitudes of the surface roughnesses of the above-described respective surfaces (the first surface 151a, the second surface 151b, the intermediate surfaces 151c and 151d, the first surface 152a, the second surface 152b, the surface 152c, and the intermediate surface 152d) and the respective surfaces to be described later can be determined based on the arithmetic mean roughness Ra defined in JIS B0633; 2001. The arithmetic mean roughness Ra is calculated by image analysis of a cross-section perpendicular to each surface. First, the support 15 and the bonding material are cut out, embedded in resin, and polished using abrasive grains, a lapping film (about #8000), etc. for a cross-section perpendicular to the surface whose surface roughness is to be measured to obtain a mirror-like cross-section. The obtained cross-section is photographed using a scanning electron microscope, an optical microscope, etc., and the arithmetic mean roughness Ra of each surface can be calculated by image analysis of the obtained image.

[0101] (Surface roughness of each surface) Each surface (the first surface 151a, the second surface 151b, the intermediate surfaces 151c, 151d, the first surface 152a, the second surface 152b, the surface 152c, and the intermediate surfaces 152d) calculated as described above and the surface roughness (arithmetic mean roughness Ra) of each surface described below may be, for example, 0.1 μm to 30 μm. Of the first surface 151a and the second surface 151b, the surface roughness (arithmetic mean roughness Ra) of one of them may be, for example, 0.1 μm to 30 μm. Also, of the first surface 152a and the second surface 152b, the surface roughness (arithmetic mean roughness Ra) of one of them may be, for example, 0.1 μm to 30 μm. Also, of the second surfaces 151b, 152b, the surface roughness (arithmetic mean roughness Ra) of one of them may be, for example, 0.1 μm to 30 μm. Further, for each surface described below, the surface roughness (arithmetic mean roughness Ra) may be set to be the same as that of each surface described above.

[0102] (Manufacturing method) For the first surface 151a and the second surface 151b of the base material 151 according to the embodiment, for example, the first surface 151a can be formed by performing a roughening treatment such as sandblasting on the portion corresponding to the first surface 151a of the surface of the base material 151 located on the external space 23 side which is an oxidation atmosphere, and the remaining portion can be made the second surface 151b. Also, for example, the second surface 151b can be formed by performing a polishing treatment on the portion corresponding to the second surface 151b of the surface of the base material 151 located on the external space 23 side which is an oxidation atmosphere, and the remaining portion can be made the first surface 151a. Also, for example, the first surface 151a and the second surface 151b can be formed by performing different surface treatments on the portions corresponding to the first surface 151a and the second surface 151b of the surface of the base material 151 located on the external space 23 side which is an oxidation atmosphere, respectively. Further, for the intermediate surfaces 151c, 151d located between the first surface 151a and the second surface 151b, they can be formed by appropriately combining the manufacturing methods of the first surface 151a and the second surface 151b described above.

[0103] In addition, the coating layer 152 according to the embodiment can be positioned by methods such as a spraying method, a vapor deposition method, an electrodeposition method, a sputtering method, etc. Further, for example, a coating material may be applied to the surface of the base material 151 and then fired to form the coating layer 152.

[0104] Also, the first surface 152a and the second surface 152b of the coating layer 152 can be formed, for example, based on the difference in surface roughness between the first surface 151a and the second surface 151b of the base material 151 corresponding to the first surface 152a and the second surface 152b. Further, it may be formed by making the thickness of the portion corresponding to the second surface 152b larger than the thickness of the portion corresponding to the first surface 152a. Also, for example, the second surface 152b may be formed by performing a polishing process on the portion corresponding to the second surface 152b of the surface of the coating layer 152, and the remaining portion may be used as the first surface 152a. Furthermore, the first surface 152a and the second surface 152b may be formed by changing various conditions during the formation of the above-described coating layer 152. Furthermore, with respect to the surface 152c and the intermediate surface 152d located between the first surface 152a and the second surface 152b, the manufacturing methods of the above-described first surface 152a and second surface 152b can be appropriately combined to form them.

[0105] <Module> Next, the module 100 according to the embodiment of the present disclosure using the above-described cell stack device 10 will be described with reference to FIG. 11. FIG. 11 is an external perspective view showing the module according to the embodiment, and shows a state in which a part of the front surface and the rear surface of the storage container 101 is removed and the cell stack device 10 of the fuel cell stored inside is taken out backward.

[0106] As shown in FIG. 11, the module 100 is configured by storing the cell stack device 10 in the storage container 101. Further, above the cell stack device 10, a reformer 102 for generating fuel gas to be supplied to the cell 1 is arranged.

[0107] In such a reformer 102, raw fuel such as natural gas or kerosene supplied through the raw fuel supply pipe 103 is reformed to generate fuel gas. The reformer 102 preferably has a structure capable of performing steam reforming, which is an efficient reforming reaction. The reformer 102 can perform steam reforming by including a vaporization unit 102a for vaporizing water and a reforming unit 102b in which a reforming catalyst (not shown) for reforming the raw fuel into fuel gas is disposed.

[0108] Then, the fuel gas generated by the reformer 102 is supplied to the fixing member 12 through the gas flow pipe 20, and is supplied from the fixing member 12 to a gas flow path 2a (see FIG. 1A) provided inside the cell 1.

[0109] Also, in the module 100 having the above-described configuration, during normal power generation, due to the above-described combustion and power generation of the cell 1, the temperature inside the module 100 becomes about 500 to 1000°C.

[0110] In such a module 100, as described above, by housing the cell stack device 10 that reduces the degradation of battery performance, the module 100 that reduces the degradation of battery performance can be achieved.

[0111] <Module housing device> FIG. 12 is an exploded perspective view showing an example of a module housing device according to an embodiment. The module housing device 110 according to the embodiment includes an exterior case, the module 100 shown in FIG. 11, and auxiliary equipment (not shown). The auxiliary equipment operates the module 100. The module 100 and the auxiliary equipment are housed inside the exterior case. Note that a part of the configuration is omitted in FIG. 12.

[0112] The exterior case of the module housing device 110 shown in FIG. 12 has a support column 111 and an exterior plate 112. A partition plate 113 vertically divides the interior of the exterior case. The space above the partition plate 113 inside the exterior case is a module housing chamber 114 for housing the module 100, and the space below the partition plate 113 inside the exterior case is an auxiliary machine housing chamber 115 for housing auxiliary machines that operate the module 100. Note that in FIG. 12, the auxiliary machines housed in the auxiliary machine housing chamber 115 are shown omitted.

[0113] Further, the partition plate 113 has an air circulation port 116 for flowing the air in the auxiliary machine housing chamber 115 to the module housing chamber 114 side. The exterior plate 112 constituting the module housing chamber 114 has an exhaust port 117 for exhausting the air in the module housing chamber 114.

[0114] In such a module housing device 110, as described above, by providing the module 100 for reducing the degradation of battery performance in the module housing chamber 114, the module housing device 110 for reducing the degradation of battery performance can be obtained.

[0115] <Other Modification Examples> Next, a cell stack device according to another modification example of the embodiment will be described with reference to FIGS. 13A to 13D.

[0116] In the above-described embodiment, the so-called "vertical stripe type" 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 element portions are provided at a plurality of locations separated from each other on the surface of the support substrate, and the so-called "horizontal stripe type" cells in which adjacent element portions are electrically connected are stacked. It can be applied to a horizontal stripe type cell stack device.

[0117] Further, in the present embodiment, the case where a hollow flat plate type support substrate is used is exemplified, but it can also be applied to a cell stack device using a cylindrical support substrate. Further, as will be described later, it can also be applied to a flat plate type cell stack device in which so-called "flat plate type" cells are stacked in the thickness direction.

[0118] In the above embodiment, an example in which the fuel electrode is provided on the support substrate and the air electrode is disposed on the surface of the cell has been shown. However, the present invention can also be applied to a cell stack device in which the air electrode is provided on the support substrate and the fuel electrode is disposed on the surface of the cell, which is the reverse arrangement.

[0119] In the above embodiment, fuel cell, fuel cell stack device, fuel cell module, and fuel cell device are shown as examples of "cell", "cell stack device", "module", and "module housing device". However, as other examples, electrolytic cell, electrolytic cell stack device, electrolytic module, and electrolytic device may be used respectively.

[0120] FIG. 13A is a perspective view showing a flat cell according to Modification 13 of the embodiment. FIG. 13B is a partial cross-sectional view of the flat cell shown in FIG. 13A. FIG. 13C is an enlarged view of region A shown in FIG. 13B.

[0121] As shown in FIG. 13A, the cell stack device has a cell 1A in which a fuel electrode 3, a solid electrolyte layer 4, and an air electrode 5 are laminated. Further, as shown in FIG. 13B, the cell 1A has an element portion 90 in which the solid electrolyte layer 4 is sandwiched between the fuel electrode 3 and the air electrode 5. In a cell stack device in which a plurality of flat cells are laminated, for example, each element portion 90 included in the plurality of cells 1A is electrically connected by conductive members 91 and 92 which are metal layers adjacent to each other. The conductive members 91 and 92 electrically connect the element portions 90 of adjacent cells 1A and have gas flow paths for supplying gas to the fuel electrode 3 or the air electrode 5.

[0122] As shown in FIG. 13B, the flat cell stack has a sealing material that hermetically seals the fuel gas flow path 98 and the oxygen-containing gas flow path 97. The sealing material is a fixing member 96 of the cell and has a joining material 93 and support members 94 and 95 which are frames. The joining material 93 may be glass or a metal material such as silver solder.

[0123] The support member 94 may be a so-called separator that partitions the fuel gas flow path 98 and the oxygen gas flow path 97. The materials of the support members 94 and 95 may be, for example, a conductive metal or an insulating ceramic. When the bonding material 93 is an insulating material such as glass, both of the support members 94 and 95 may be made of metal, or either one of them may be made of an insulating material. When the bonding material 93 is a conductive metal, both or either one of the support members 94 and 95 may be made of an insulating material. When the support members 94 and 95 are made of metal, the support members 94 and 95 may be integrated with the conductive member 92.

[0124] Either one of the bonding material 93 and the support members 94 and 95 is insulating, and electrically insulates the two conductive members 91 and 92 sandwiching the flat plate type cell from each other.

[0125] As shown in FIG. 13C, the flat plate type cell according to this modification includes a support member 94 and a bonding material 93. The support member 94 has a base material 941 and a coating layer 942. The base material 941 has a first surface 941a and a second surface 941b and contains chromium. The coating layer 942 covers the first surface 941a of the base material 941. The bonding material 93 is located between the solid electrolyte layer 4 of the element portion 90 and the first surface 942a of the coating layer 942.

[0126] The second surface 941b of the base material 941 has a smaller surface roughness than the first surface 941a and is exposed to the oxidizing atmosphere (flow path 97).

[0127] Since the surface roughness of the first surface 941a facing the coating layer 942 is larger than the surface roughness of the second surface 941b, it is possible to suppress the coating layer 942 from peeling off from the base material 941 or the coating layer 942 from breaking and causing fuel gas leakage. Therefore, according to the embodiment, the durability of the support member 94 can be enhanced.

[0128] Furthermore, since the surface roughness of the second surface 941b is smaller than that of the first surface 941a, it is possible to suppress the chromium (Cr) contained in the base material 941 from desorbing into the oxidizing atmosphere (flow path 97) during high-temperature operation. Therefore, according to the embodiment, since the durability of the support member 94 can be enhanced, the durability of the cell stack device can be enhanced.

[0129] FIG. 13D is an enlarged view of region A according to a modified example of the flat plate type cell. As shown in FIG. 13D, it is different from the flat plate type cell shown in FIG. 13C in that the coating layer 942 further covers the second surface 941b of the base material 941. And, the second surface 942b of the coating layer 942 has a smaller surface roughness than the first surface 941a facing the bonding material 93 and is exposed to the oxidizing atmosphere (flow path 97).

[0130] Since the surface roughness of the first surface 942a facing the bonding material 93 is larger than that of the second surface 942b, the adhesion between the bonding material 93 and the coating layer 942 is improved. For this reason, it is possible to suppress the bonding material 93 and the coating layer 942 from peeling off, or the coating layer 942 from breaking and causing a fuel gas leak. Therefore, according to the embodiment, the durability of the support member 94 can be enhanced.

[0131] Furthermore, since the surface roughness of the second surface 942b is smaller than that of the first surface 942a, it is possible to suppress the chromium (Cr) contained in the base material 941 from desorbing into the oxidizing atmosphere (flow path 97) through the coating layer 942 during high-temperature operation. Therefore, according to the embodiment, since the durability of the support member 94 can be enhanced, the durability of the cell stack device can be enhanced.

[0132] In addition, in the examples shown in FIGS. 13C and 13D, the coating layer 942 is positioned to cover the surface 941e of the base material 941 facing the reducing atmosphere (flow path 98), but the present invention is not limited to this, and the surface 941e may be exposed to the reducing atmosphere (flow path 98).

[0133] As described above, the present disclosure has been described in detail. However, the present disclosure is not limited to the above-described embodiments, and various changes, improvements, etc. are possible without departing from the gist of the present disclosure.

[0134] As described above, the composite member (support 15) according to the embodiment includes a base material 151 and a coating layer 152. The base material 151 has a first surface 151a that is not exposed to an oxidizing atmosphere and contains chromium. The coating layer 152 covers the first surface 151a and has a first outer surface (first surface 152a) that is not exposed to an oxidizing atmosphere. At least one of the base material 151 and the coating layer 152 has an exposed surface that is exposed to an oxidizing atmosphere. The surface roughness of the exposed surface is different from the surface roughness of the first surface 151a or the first outer surface (first surface 152a). Thereby, the durability of the composite member (support 15) can be enhanced.

[0135] Further, the cell stack device 10 according to the embodiment includes a plurality of cells 1, the composite member (support 15) described above, and a bonding material 13. The plurality of cells 1 have an element portion and include a first cell. The bonding material 13 is located between the element portion and the first outer surface (first surface 152a) of the coating layer 152. The base material 151 has a first surface 151a facing the first cell and a second surface 151b that includes an exposed surface and does not face the first cell. The surface roughness of the second surface 151b is smaller than that of the first surface 151a. Thereby, a decrease in the battery performance of the cell stack device 10 can be reduced.

[0136] Further, the module 100 according to the embodiment includes the cell stack device 10 described above and a storage container 101 that stores the cell stack device 10. Thereby, the module 100 can be configured to reduce a decrease in battery performance.

[0137] Further, the module housing device 110 according to the embodiment includes the module 100 described above, auxiliary equipment for operating the module 100, and an exterior case that houses the module 100 and the auxiliary equipment. Thereby, the module housing device 110 can be configured to reduce a decrease in battery performance.

[0138] The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. Indeed, the above-described embodiments can be embodied in various forms. Also, the above embodiments may be omitted, substituted, or changed in various forms without departing from the scope and spirit of the appended claims.

Description of Reference Numerals

[0139] 1 cell 10 cell stack device 11 cell stack 12 fixing member 13 bonding material 14 supporting member 15 support 16 gas tank 17 end current collecting member 18 conductive member 23 external space 100 module 110 module housing device

Claims

1. a plurality of cells having an element part and including a first cell; a composite member including a base material having a first surface not exposed to an oxidizing atmosphere and containing chromium, and a coating layer covering the first surface and having a first outer surface not exposed to the oxidizing atmosphere; a bonding material positioned between the element part and the first outer surface of the coating layer and comprising at least one of the base material and the coating layer has an exposed surface exposed to an oxidizing atmosphere, the surface roughness of the exposed surface is different from the surface roughness of the first surface or the first outer surface, the base material has the first surface facing the first cell and a second surface including the exposed surface and not facing the first cell, the surface roughness of the second surface is smaller than that of the first surface, the coating layer has a second outer surface exposed to the oxidizing atmosphere and a third outer surface positioned between the first outer surface and the second outer surface, and further covers the second surface, the third outer surface is exposed to the oxidizing atmosphere and has a larger surface roughness than the second outer surface a cell stack device.

2. The first outer surface has a larger surface roughness than the second outer surface. The cell stack device according to Claim 1.

3. a plurality of cells having an element part and including a first cell; a composite member including a base material having a first surface not exposed to an oxidizing atmosphere and containing chromium, and a coating layer covering the first surface and having a first outer surface not exposed to the oxidizing atmosphere; a bonding material positioned between the element part and the first outer surface of the coating layer and comprising at least one of the base material and the coating layer has an exposed surface exposed to an oxidizing atmosphere, the surface roughness of the exposed surface is different from the surface roughness of the first surface or the first outer surface, the base material has the first surface facing the first cell and a second surface not facing the first cell, the coating layer covers the second surface and further has a second outer surface including the exposed surface, and the second outer surface has a smaller surface roughness than the first outer surface, the first surface has a smaller surface roughness at a portion closer to the oxidizing atmosphere than at a portion farther from the oxidizing atmosphere, the second surface has a larger surface roughness than the second outer surface a cell stack device.

4. The second surface has a larger surface roughness than the second outer surface. The cell stack device according to Claim 1 or 2.

5. a plurality of cells having an element part and including a first cell; a composite member including a base material having a first surface not exposed to an oxidizing atmosphere and containing chromium, and a coating layer covering the first surface and having a first outer surface not exposed to the oxidizing atmosphere; A bonding material positioned between the element portion and the first outer surface of the coating layer and comprising at least one of the base material and the coating layer has an exposed surface exposed to an oxidizing atmosphere, the surface roughness of the exposed surface is different from the surface roughness of the first surface or the first outer surface, the base material has a first surface facing the first cell and a second surface not facing the first cell, the coating layer covers the second surface and further has a second outer surface including the exposed surface, and the second outer surface has a smaller surface roughness than the first outer surface, the coating layer has a third outer surface positioned between the first outer surface and the second outer surface, the third outer surface is exposed to the oxidizing atmosphere and has a larger surface roughness than the second outer surface cell stack device.

6. The third outer surface faces the bonding material and has a smaller surface roughness than the first outer surface The cell stack device according to claim 5.

7. The base material has a third surface positioned between the first surface and the second surface The cell stack device according to any one of claims 1 to 6.

8. The first surface has a smaller surface roughness in a portion closer to the oxidizing atmosphere than in a portion farther from the oxidizing atmosphere The cell stack device according to any one of claims 1, 2, 5, and 6.

9. A cell stack device according to any one of claims 1 to 8, and a storage container for storing the cell stack device module comprising.

10. The module according to claim 9, auxiliary equipment for operating the module, and an exterior case for housing the module and the auxiliary equipment module housing device comprising.

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