Conductive member, cell, cell stack device, module, and module accommodating device

Abstract

A conductive member, a cell, a cell stack device, a module, and a module accommodating device that can reduce an increase in internal resistance are provided. The conductive member has a substrate and a coating portion located on the substrate and containing a first element. The substrate contains chromium. The first element has a first ionization energy and a free energy of formation of an oxide whose absolute values ​​are smaller than those of chromium.

Description

[Technical Field]

[0001] The present disclosure relates to a conductive member, a cell, a cell stack device, a module, and a module housing device. [Background technology]

[0002] In recent years, various fuel cell stack devices have been proposed as next-generation energy sources. These devices have multiple fuel cell units, which are a type of cell that can generate electricity 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] International Publication No. 2009 / 131180 Summary of the Invention

[0004] According to one embodiment, the conductive member includes a substrate and a coating portion located on the substrate and containing a first element. The substrate contains chromium. The first element has a first ionization energy and a free energy of formation of an oxide whose absolute values ​​are smaller than those of chromium.

[0005] The cell of the present disclosure includes an element portion and the conductive member described above. The conductive member is connected to the element portion.

[0006] The cell stack device of the present disclosure also includes a cell stack including a plurality of the above-described cells.

[0007] The module of the present disclosure also includes the cell stack device described above and a storage container that stores the cell stack device.

[0008] The module housing device of the present disclosure includes the module described above, an auxiliary device for operating the module, and an exterior case for housing the module and the auxiliary device. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1A is a cross-sectional view showing an example of a cell according to a first embodiment. [Figure 1B] FIG. 1B is a side view of an example of a cell according to the first embodiment, viewed from the air electrode side. [Figure 1C] FIG. 1C is a side view of an example of a cell according to the first embodiment, viewed from the interconnector side. [Figure 2A] FIG. 2A is a perspective view showing an example of a cell stack device according to the first embodiment. [Figure 2B] FIG. 2B is a cross-sectional view taken along line XX shown in FIG. 2A. [Figure 2C] FIG. 2C is a top view showing an example of the cell stack device according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing an example of a conductive member according to an embodiment. [Figure 4A] FIG. 4A is a cross-sectional view taken along the line AA shown in FIG. [Figure 4B] FIG. 4B is an enlarged view of region B shown in FIG. 4A. [Figure 5] FIG. 5 is an external perspective view showing an example of the module according to the first embodiment. [Figure 6] FIG. 6 is an exploded perspective view schematically illustrating an example of a module housing device according to the first embodiment. [Figure 7A] FIG. 7A is a cross-sectional view showing a cell according to the second embodiment. [Figure 7B] FIG. 7B is an enlarged cross-sectional view of the conductive member according to the second embodiment. [Figure 8A] FIG. 8A is a perspective view showing a flat cell according to a third embodiment. [Figure 8B] FIG. 8B is a partial cross-sectional view of the flat cell shown in FIG. 8A. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of a conductive member, a cell, a cell stack device, a module, and a module housing device disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the disclosure is not limited to the embodiments described below.

[0011] It should also be noted that the drawings are schematic and that the dimensional relationships and ratios of elements may differ from reality. Furthermore, the drawings may contain parts whose dimensional relationships and ratios differ from one another.

[0012] [First embodiment] <Cell configuration> First, with reference to FIGS. 1A to 1C, a cell according to the first embodiment will be described using an example of a solid oxide fuel cell.

[0013] Fig. 1A is a cross-sectional view showing an example of a cell 1 according to the first embodiment, Fig. 1B is a side view of the example of a cell according to the first embodiment as seen from the air electrode side, and Fig. 1C is a side view of the example of a cell 1 according to the first embodiment as seen from the interconnector side. Note that Figs. 1A to 1C show enlarged views of parts of each component of the cell 1.

[0014] 1A to 1C, cell 1 is a hollow, flat, elongated plate. As shown in Fig. 1B, the shape of the entire cell 1 as viewed from the side is, for example, a rectangle with a side length in the length direction L of 5 cm to 50 cm and a length in the width direction W perpendicular to the length direction L of 1 cm to 10 cm. The thickness of the entire cell 1 in the thickness direction T is, for example, 1 mm to 5 mm.

[0015] 1A, the cell 1 includes a conductive support substrate 2, an element section 3, and an interconnector 4. The support substrate 2 is columnar, having a pair of opposing flat surfaces n1, n2 and a pair of arc-shaped side surfaces m connecting the flat surfaces n1, n2.

[0016] The element section 3 is located on the flat surface n1 of the support substrate 2. The element section 3 has an anode 5, a solid electrolyte layer 6, and an cathode 8. In the example shown in FIG. 1A, the interconnector 4 is located on the flat surface n2 of the cell 1. The cell 1 may also have an intermediate layer 7 between the solid electrolyte layer 6 and the cathode 8.

[0017] 1B, the air electrode 8 does not extend to the lower end of the cell 1. At the lower end of the cell 1, only the solid electrolyte layer 6 is exposed on the surface of the flat face n1. As shown in FIG. 1C, the interconnector 4 may extend to the lower end of the cell 1. At the lower end of the cell 1, the interconnector 4 and the solid electrolyte layer 6 are exposed on the surface. As shown in FIG. 1A, the solid electrolyte layer 6 is exposed on the surface of a pair of arc-shaped side faces m of the cell 1. The interconnector 4 does not have to extend to the lower end of the cell 1.

[0018] Each of the components that make up the cell 1 will be described below.

[0019] The support substrate 2 has gas flow channels 2a therein through which gas flows. The example of the support substrate 2 shown in FIG. 1A has six gas flow channels 2a. The support substrate 2 is gas permeable, and allows the gas flowing in the gas flow channels 2a to pass through to the anode 5. The support substrate 2 may be conductive. The conductive support substrate 2 collects electricity generated in the element section to the interconnector 4.

[0020] The material of the support substrate 2 includes, for example, an iron group metal component and an inorganic oxide. The iron group metal component may be, for example, Ni (nickel) and / or NiO. The inorganic oxide may be, for example, a specific rare earth element oxide. The rare earth element oxide may include, for example, one or more rare earth elements selected from Sc, Y, La, Nd, Sm, Gd, Dy, and Yb.

[0021] A commonly known material can be used for the anode 5. The anode 5 may be made of porous conductive ceramics, such as ceramics containing calcium oxide, magnesium oxide, or ZrO2 solid-solubilized with rare earth element oxides, and Ni and / or NiO. The rare earth element oxides may contain, for example, multiple rare earth elements selected from Sc, Y, La, Nd, Sm, Gd, Dy, and Yb. Calcium oxide, magnesium oxide, or ZrO2 solid-solubilized with rare earth element oxides is sometimes referred to as stabilized zirconia. Stabilized zirconia also includes partially stabilized zirconia.

[0022] The solid electrolyte layer 6 is an electrolyte and acts as a bridge for ions between the fuel electrode 5 and the air electrode 8. At the same time, the solid electrolyte layer 6 has gas barrier properties, making it difficult for leakage of fuel gas and oxygen-containing gas to occur.

[0023] The material of the solid electrolyte layer 6 may be, for example, ZrO2 with 3 mol % to 15 mol % of a rare earth element oxide dissolved therein. The rare earth element oxide may include, for example, one or more rare earth elements selected from Sc, Y, La, Nd, Sm, Gd, Dy, and Yb. The solid electrolyte layer 6 may include, for example, ZrO2 with Yb, Sc, or Gd dissolved therein, CeO2 with La, Nd, or Yb dissolved therein, BaZrO3 with Sc or Yb dissolved therein, or BaCeO3 with Sc or Yb dissolved therein.

[0024] The air electrode 8 is gas permeable. The open porosity of the air electrode 8 may be, for example, in the range of 20% to 50%, and particularly 30% to 50%. The open porosity of the air electrode 8 may also be referred to as the void ratio of the air electrode 8.

[0025] There are no particular restrictions on the material of the air electrode 8 as long as it is one that is generally used for air electrodes. The material of the air electrode 8 may be, for example, a conductive ceramic such as a so-called ABO3 type perovskite oxide.

[0026] The material of the air electrode 8 may be, for example, a composite oxide in which Sr (strontium) and La (lanthanum) 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, etc. Note that x is 0 <x<1、yは0<y<1である。

[0027] Furthermore, when the element section 3 has an intermediate layer 7, the intermediate layer 7 functions as a diffusion suppression layer. When Sr (strontium) contained in the air electrode 8 diffuses into the solid electrolyte layer 6, a resistive layer of SrZrO3 is formed in the solid electrolyte layer 6. The intermediate layer 7 makes it difficult for Sr to diffuse, thereby making it difficult for SrZrO3 to be formed.

[0028] There are no particular limitations on the material of the intermediate layer 7, as long as it is generally used as a diffusion suppression layer for Sr. The material of the intermediate layer 7 may include, for example, cerium oxide (CeO2) in which a rare earth element other than Ce (cerium) is dissolved. Examples of such rare earth elements include Gd (gadolinium) and Sm (samarium).

[0029] Furthermore, the interconnector 4 is dense and makes it difficult for leakage of the fuel gas flowing through the gas flow channel 2a located inside the support substrate 2 and the oxygen-containing gas flowing outside the support substrate 2 to occur. The interconnector 4 may have a relative density of 93% or more, particularly 95% or more.

[0030] Lanthanum chromite-based perovskite oxides (LaCrO3-based oxides), lanthanum strontium titanium-based perovskite oxides (LaSrTiO3-based oxides), etc. may be used as the material for the interconnector 4. These materials are conductive and are not reduced or oxidized even when in contact with fuel gases such as hydrogen-containing gases and oxygen-containing gases such as air.

[0031] <Configuration of cell stack device> Next, a cell stack device 10 according to this embodiment using the above-described cell 1 will be described with reference to Figures 2A to 2C. Figure 2A is a perspective view showing an example of a cell stack device according to the first embodiment, Figure 2B is a cross-sectional view taken along line XX shown in Figure 2A, and Figure 2C is a top view showing an example of a cell stack device according to the first embodiment.

[0032] As shown in FIG. 2A, the cell stack device 10 includes a cell stack 11 having a plurality of cells 1 arranged (stacked) in a thickness direction T of the cells 1 (see FIG. 1A), and a fixing member 12.

[0033] The fixing member 12 has a fixing material 13 and a support member 14. The support member 14 supports the cell 1. The fixing material 13 fixes the cell 1 to the support member 14. The support member 14 also has a support 15 and a gas tank 16. The support 15 and gas tank 16, which are the support member 14, are made of metal and are electrically conductive.

[0034] 2B, the support body 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 wall of the insertion holes 15a are joined with a fixing material 13.

[0035] The gas tank 16 has an opening for supplying a reaction gas to the cells 1 through the insertion holes 15a, and a recessed groove 16a located around the opening. The outer peripheral edge of the support 15 is joined to the gas tank 16 by a bonding material 21 filled in the recessed groove 16a of the gas tank 16.

[0036] In the example shown in Fig. 2A, fuel gas is stored in an internal space 22 formed by a support 15, which is the support member 14, and a gas tank 16. A gas circulation pipe 20 is connected to the gas tank 16. The fuel gas is supplied to the gas tank 16 through this gas circulation pipe 20, and is supplied from the gas tank 16 to a gas flow path 2a (see Fig. 1A) inside the cell 1. The fuel gas supplied to the gas tank 16 is generated in a reformer 102 (see Fig. 5), which will be described later.

[0037] The hydrogen-rich fuel gas can be produced by steam reforming the raw fuel, etc. When the fuel gas is produced by steam reforming, the fuel gas contains water vapor.

[0038] The example shown in FIG. 2A 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 a corresponding support 15. The gas tank 16 has two through-holes on its top surface. A support 15 is disposed in each through-hole. An internal space 22 is formed by the one gas tank 16 and the two supports 15.

[0039] The shape of the insertion hole 15a is, for example, an oval shape when viewed from above. For example, the length of the insertion hole 15a in the arrangement direction of the cells 1, i.e., the thickness direction T, is greater than the distance between the two end current collecting members 17 located at both ends of the cell stack 11. For example, the width of the insertion hole 15a is greater than the length of the cell 1 in the width direction W (see FIG. 1A).

[0040] 2B, a fixing material 13 is filled in the joint between the inner wall of the insertion hole 15a and the lower end of the cell 1. This bonds and fixes the inner wall of the insertion hole 15a to the lower end of each of the multiple cells 1, and also bonds and fixes the lower ends of the cells 1 to each other. The gas flow path 2a of each cell 1 communicates with the internal space 22 of the support member 14 at its lower end.

[0041] A material with low conductivity, such as glass, can be used for the fixing material 13 and the bonding material 21. Specific materials for the fixing material 13 and the bonding material 21 include amorphous glass, and in particular, crystallized glass.

[0042] As the crystallized glass, for example, any of materials such as SiO2-CaO, MgO-B2O3, La2O3-B2O3-MgO, La2O3-B2O3-ZnO, and SiO2-CaO-ZnO may be used, and in particular, SiO2-MgO materials may be used.

[0043] 2B, a conductive member 18 is interposed between adjacent cells 1 among the plurality of cells 1. The conductive member 18 electrically connects the anode 5 of one adjacent cell 1 to the cathode 8 of the other cell 1 in series. More specifically, the conductive member 18 connects the interconnector 4 electrically connected to the anode 5 of one adjacent cell 1 to the cathode 8 of the other cell 1. Details of the conductive member 18 connected to adjacent cells 1 will be described later.

[0044] 2B, an end current collecting member 17 is electrically connected to the cell 1 located at the outermost position in the arrangement direction of the multiple cells 1. The end current collecting member 17 is connected to a conductive part 19 that protrudes to the outside of the cell stack 11. The conductive part 19 collects electricity generated by power generation in the cells 1 and extracts it to the outside. Note that the end current collecting member 17 is not shown in FIG. 2A.

[0045] 2C, the cell stack device 10 has two cell stacks 11A and 11B connected in series to function as a single battery. Therefore, the conductive part 19 of the cell stack device 10 is divided into a positive terminal 19A, a negative terminal 19B, and a connection terminal 19C.

[0046] The positive electrode terminal 19A is a positive electrode when the power generated by the cell stack 11 is output to the outside, and is electrically connected to the positive electrode side end current collecting member 17 of the cell stack 11A. The negative electrode terminal 19B is a negative electrode when the power generated by the cell stack 11 is output to the outside, and is electrically connected to the negative electrode side end current collecting member 17 of the cell stack 11B.

[0047] The connection terminal 19C electrically connects the end current collecting member 17 on the negative electrode side of the cell stack 11A and the end current collecting member 17 on the positive electrode side of the cell stack 11B.

[0048] <Details of conductive materials> Next, details of the conductive member 18 according to the first embodiment will be described with reference to Figures 3 to 4B. Figure 3 is a cross-sectional view showing an example of the conductive member according to the embodiment.

[0049] As shown in Fig. 3, the conductive member 18 has a connection portion 18a connected to one adjacent cell 1 and a connection portion 18b connected to the other adjacent cell 1. The conductive member 18 also has linking portions 18c at both ends in the width direction W, which connect the connection portions 18a and 18b. This allows the conductive member 18 to electrically connect the cells 1 adjacent to each other in the thickness direction T. Note that Fig. 3 shows a simplified shape of the cell 1.

[0050] Furthermore, the connection portions 18a and 18b have a first surface 181 facing the cell 1 and a second surface 182 facing the connection portions 18b and 18a.

[0051] Fig. 4A is a cross-sectional view taken along line AA shown in Fig. 3. Fig. 4B is an enlarged view of region B shown in Fig. 4A.

[0052] The conductive member 18 extends in the longitudinal direction L of the cell 1. As shown in Fig. 4A, a plurality of connection portions 18a, 18b of the conductive member 18 are alternately positioned along the longitudinal direction L of the cell 1. The conductive member 18 is in contact with the cell 1 at each of the connection portions 18a, 18b.

[0053] 4B, conductive member 18 has a base material 40, a covering portion 43, and a coating layer 44. Coating layer 44 is conductive. Conductive member 18 has a first surface 181 and a second surface 182 that face each other with base material 40 in between. Conductive member 18 also has third surfaces 183 and 184 that connect first surface 181 and second surface 182.

[0054] The conductive member 18 (connection portion 18b) is joined to the cell 1 via a joining material 50. The joining material 50 is located between the first surface 181 of the conductive member 18 and the cell 1, and joins the conductive member 18 to the cell 1. In addition, the second surface 182 and the third surfaces 183, 184 are exposed to an oxidizing atmosphere, such as air.

[0055] The substrate 40 has electrical conductivity and heat resistance. The substrate 40 contains chromium. The substrate 40 is, for example, stainless steel. The substrate 40 may contain, for example, a metal oxide.

[0056] The substrate 40 may also have a laminated structure. In the example shown in FIG. 4B , the substrate 40 has a first substrate layer 41 and a second substrate layer 42. The second substrate layer 42 may have a higher chromium content than the first substrate layer 41, for example. The second substrate layer 42 contains chromium oxide (Cr2O3), for example. When the substrate 40 has the second substrate layer 42 in this manner, the durability of the conductive member 18 is increased. The substrate 40 may partially have the second substrate layer 42, or may not have the second substrate layer 42. The substrate 40 may also have a further laminated structure.

[0057] The coating portion 43 is located on the substrate 40. The coating portion 43 is located between the substrate 40 and the coating layer 44. The coating portion 43 contains a first element 43a. The coating portion 43 contains, for example, Ce. The absolute values ​​of the first ionization energy and the free energy of formation of the oxide of the first element 43a are smaller than those of chromium. In addition to Ce, examples of the first element 43a include Eu, Pr, and Zr. The free energy of formation is also referred to as the Gibbs energy of formation. The free energy of formation can be confirmed in a thermodynamic database, such as the "Nuclear Fuel and Nuclear Materials Thermodynamics Database." The first element 43a may be located on the substrate 40 as an oxide of such an element. Examples of oxides of the first element 43a include CeO2, EuO, PrO2, and ZrO2. Hereinafter, the oxide of the first element 43a will be referred to as the "first oxide."

[0058] The coating portion 43 may be a plurality of particles located on the substrate 40 and containing the first element 43a. Alternatively, the coating portion 43 may be a coating containing the first element 43a and coating the substrate 40. The coating portion 43 may be a single coating covering the entire substrate 40, or may be a mesh-like coating or a plurality of island-like coatings spaced apart from one another and located on the substrate 40. The plurality of particles and coatings containing the first element 43a are collectively referred to as the coating portion 43. The coating portion 43 may contain, for example, one or more of the first elements 43a. The coating portion 43 may also contain an element other than the first element 43a. The coating portion 43 may contain, for example, CeO2 solid-solubilized with Gd (gadolinium) or ZrO2 solid-solubilized with Y (yttrium), Yb (ytterbium), or the like, known as stabilized zirconia or partially stabilized zirconia. That is, the coating 43 may have a plurality of particles and / or a coating containing the first element 43a. When the coating 43 has a plurality of particles and a coating containing the first element 43a, the plurality of particles may be located on the substrate 40 or on the coating.

[0059] The coating portion 43 can be formed on the surface of the substrate 40 by a film formation method such as IAD (Ion-beam Assisted Deposition), MOD (Metal Organic Decomposition), sputtering, AD (Aerosol Deposition), or PLD (Pulsed Laser Deposition).

[0060] The coating portion 43 containing the first element 43a may be crystalline or amorphous. Also, the coating portion 43 may contain a mixture of a crystalline phase and an amorphous phase.

[0061] In this way, the conductive member 18 has the coating portion 43 located on the substrate 40 and containing the first element 43a, which suppresses the growth of the second substrate layer 42, and therefore the conductive member 18 can suppress an increase in internal resistance that accompanies the growth of the second substrate layer 42. This can reduce the deterioration of the battery performance of the cell 1.

[0062] The thickness of the coating portion 43 may be, for example, 5 nm to 150 nm, or 10 nm to 130 nm, or even 20 nm to 100 nm. Having such a thickness for the coating portion 43 can, for example, suppress growth of the second substrate layer 42. Furthermore, even if the coating portion 43 has low conductivity, the effect of the coating portion 43 on the internal resistance can be minimized, thereby enabling the conductive member 18 to suppress an increase in internal resistance. This reduces degradation of the battery performance of the cell 1. For example, the conductivity of Cr2O3 is 1.5 S / m, and the conductivity of CeO2 is 0.07 S / m. When a conductive member consisting of the substrate 40 alone or a conductive member with a coating layer 44 (described below) formed directly on the substrate 40 is used at the operating temperature of the fuel cell, the thickness of the second substrate layer 42 is approximately several μm, for example, 4 μm. On the other hand, when a conductive member 18 having the coating portion 43 on the substrate 40 is used at the operating temperature of the fuel cell, the thickness of the second substrate layer 42 is 1 μm or less. Specifically, for example, in a conductive member 18 having a CeO2 coating with a thickness of 10 nm, the thickness of the second base layer is about 0.8 μm, and the internal resistance can be made smaller than when no coating is provided.

[0063] The presence or absence of the first element 43a and the size of the coating portion 43 containing the first element 43a can be confirmed by, for example, mapping the first element 43a using an HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope), a FIB-SEM (focused ion beam scanning electron microscope), or an EPMA (electron probe microanalyzer) on a cross section of the conductive member 18. The average thickness of the coating shown below can be obtained by, for example, using an HAADF-STEM with an acceleration voltage of 200 kV to map the elements on a cross section of the conductive member 18 at a magnification of 1,000,000 times, measuring the thickness of 10 or more points where the first element 43a is detected, and calculating the average value.

[0064] The average thickness t1 of the coating between the first surface 181 of the conductive member 18 and the substrate 40 may be the same as or different from the average thickness t3 of the coating between the third surface 183 and the substrate 40 and the average thickness t4 of the coating between the third surface 184 and the substrate 40. The average thickness t1 as the first average thickness may be greater than the average thicknesses t3 and t4 as the second average thicknesses. By making the average thickness t1 greater than the average thicknesses t3 and t4, growth of the second substrate layer 42 near the first surface 181 through which current flows is suppressed. The average thicknesses t3 and t4 may be less than 5 nm, for example. The conductive member 18 may not have a coating between the third surface 183 and the substrate 40 or between the third surface 184 and the substrate 40. Since current may flow less easily near the third surfaces 183 and 184, the second substrate layer 42 may be thicker than near the first surface 181. The conductive member 18 has the second base material layer 42 that is thicker near the third surfaces 183, 184 than near the first surface 181, thereby suppressing oxidation of the base material 40. This can reduce deterioration in the battery performance of the cell 1.

[0065] The average thicknesses t3 and t4 may be larger than the average thickness t1, for example, larger than 150 nm. Since current may flow less easily near the third surfaces 183 and 184, the average thicknesses t3 and t4 may be larger in this manner. By making the average thicknesses t3 and t4 larger than the average thickness t1, the growth of the second substrate layer 42 is suppressed on the third surfaces 183 and 184, and the release of chromium contained in the substrate 40 can be suppressed. The average thickness t2 of the coating located between the second surface 182 of the conductive member 18 and the substrate 40 may be larger or smaller than the average thicknesses t3 and t4.

[0066] Furthermore, the first area ratio, which is the area ratio of the covering portion 43 located between the first surface 181 and the substrate 40, may be the same as or different from the second area ratio, which is the area ratio of the covering portion 43 located between the third surfaces 183, 184 and the substrate 40. The first area ratio may be larger than the second area ratio. In this way, by making the first area ratio larger than the second area ratio, growth of the second substrate layer 42 at a location close to the first surface 181 through which current flows is suppressed. The first area ratio may be, for example, 20 area% or more and 100 area% or less. The second area ratio may be, for example, 0 area% or more and 100 area% or less. The area ratio of the covering portion 43 located between the second surface 182 and the substrate 40 may be larger or smaller than the second area ratio.

[0067] The above-mentioned area ratios can be calculated, for example, as follows. First, the cross section of the conductive member 18 is polished, and the first element 43a on the substrate 40 is mapped using an HAADF-STEM, a FIB-SEM (focused ion beam scanning electron microscope), or an EPMA (electron probe microanalyzer). Specifically, a mapping image of the first element 43a is obtained at a magnification of, for example, 3000 to 5000 times on the cross section of the conductive member 18 using an HAADF-STEM with an acceleration voltage of, for example, 200 kV. The obtained mapping image is analyzed using Igor, an analysis software manufactured by Hulinks Corporation, to calculate the area ratio of the first element 43a overlapping with the substrate 40 as viewed from the normal direction of each surface. The obtained area ratio of the first element 43a is defined as the area ratio of the coating portion 43.

[0068] The coating layer 44 covers the covering portion 43 over the entire thickness direction T and length direction L of the cell 1. The coating layer 44 contains an element different from that of the covering portion 43. The coating layer 44 is located between the substrate 40 and the oxidizing atmosphere, and thus can suppress the release of chromium contained in the substrate 40, for example. This improves the durability of the conductive member 18, and therefore the durability of the cell 1.

[0069] The coating layer 44 may also contain an oxide containing, for example, Mn (manganese) and Co (cobalt). Hereinafter, the oxide containing Mn and Co is referred to as the second oxide. The second oxide has electronic conductivity. The second oxide has higher electrical conductivity than Cr2O3 and the first oxide. The second oxide may have, for example, a conductivity 100 times higher than that of Cr2O3. The molar ratio of Mn contained in the second oxide may be greater than the molar ratio of Co. The coating layer 44 may contain, for example, a second oxide having a molar ratio of Mn, Co, and O of 1.66:1.34:4. By containing a second oxide having such a composition, the durability of the conductive member 18 can be improved compared to a coating layer 44 containing a second oxide having a molar ratio of Mn, Co, and O of 1.5:1.5:4. The molar ratio of Mn, Co, and O can be calculated based on the identification of crystalline phases using an X-ray diffractometer (XRD). The second oxide may also contain elements other than Mn and Co, such as Zn (zinc), Fe (iron), and Al (aluminum). The coating layer 44 may or may not contain the first element 43a. When the coating layer 44 contains the first element 43a, the content of the first element 43a in the coating layer 44 is lower than the content of the first element 43a in the covering portion 43.

[0070] Furthermore, the coating layer 44 may be porous. The coating layer 44 may have a porosity of, for example, 5% or more and 40% or less. When the conductive member 18 has the porous coating layer 44 in this way, it is possible to alleviate the stress that the conductive member 18 receives from the outside. This improves the durability of the conductive member 18, and therefore the durability of the cell 1 can be improved.

[0071] The coating layer 44 can be formed by methods such as thermal spraying, vapor deposition, electrodeposition, sputtering, etc. Alternatively, the coating layer 44 may be formed by applying a coating material to the surface of the coating portion 43 or the coating film, and then baking the applied coating material.

[0072] <module> Next, a module 100 according to an embodiment of the present disclosure using the above-described cell stack device 10 will be described with reference to Fig. 5. Fig. 5 is an external perspective view showing the module according to the first embodiment, with the front and rear surfaces, which are part of the storage container 101, removed and the cell stack device 10 of the fuel cell stored inside removed to the rear.

[0073] 5, the module 100 includes a storage container 101 and a cell stack device 10 housed in the storage container 101. A reformer 102 is disposed above the cell stack device 10.

[0074] The reformer 102 reforms raw fuel such as natural gas or kerosene to generate fuel gas, which is then supplied to the cell 1. The raw fuel is supplied to the reformer 102 through a raw fuel supply pipe 103. The reformer 102 may also include a vaporizer 102a that vaporizes water, and a reformer 102b. The reformer 102b includes a reforming catalyst (not shown) and reforms the raw fuel into fuel gas. Such a reformer 102 can perform steam reforming, a highly efficient reforming reaction.

[0075] The fuel gas produced in the reformer 102 is supplied to the gas flow channel 2a of the cell 1 (see FIG. 1A) through the gas distribution pipe 20, the gas tank 16, and the support member 14.

[0076] Furthermore, in the module 100 having the above-described configuration, the temperature inside the module 100 during normal power generation becomes approximately 500°C to 1000°C due to the combustion of gas and the power generation of the cells 1.

[0077] In such a module 100, as described above, the module 100 is configured to house a cell stack device 10 having a plurality of cells 1 that reduce the degradation of battery performance, thereby making it possible to make the module 100 reduce the degradation of battery performance.

[0078] <Module storage device> Fig. 6 is an exploded perspective view showing an example of a module housing device according to the first embodiment. The module housing device 110 according to this embodiment includes an outer case 111, the module 100 shown in Fig. 5, and auxiliary equipment (not shown). The auxiliary equipment operates the module 100. The module 100 and the auxiliary equipment are housed in the outer case 111. Note that some components are omitted in Fig. 6.

[0079] An exterior case 111 of a module accommodating device 110 shown in Fig. 6 has support columns 112 and an exterior plate 113. A partition plate 114 divides the interior of the exterior case 111 into upper and lower sections. The space above the partition plate 114 in the exterior case 111 is a module accommodating chamber 115 that accommodates the module 100, and the space below the partition plate 114 in the exterior case 111 is an accessory accommodating chamber 116 that accommodates accessory equipment for operating the module 100. Note that in Fig. 6, the accessory equipment accommodated in the accessory accommodating chamber 116 is omitted.

[0080] The partition plate 114 also has an air flow port 117 for allowing air from the auxiliary equipment housing chamber 116 to flow toward the module housing chamber 115. The exterior plate 113 that constitutes the module housing chamber 115 has an exhaust port 118 for exhausting air from within the module housing chamber 115.

[0081] In such a module accommodating device 110, as described above, the module 100 that reduces the degradation of battery performance is provided in the module accommodating chamber 115, thereby making it possible to make the module accommodating device 110 reduce the degradation of battery performance.

[0082] In the above embodiment, a case where a hollow flat plate-type support substrate is used is exemplified, but the present invention can also be applied to a cell stack device that uses a cylindrical support substrate.

[0083] [Second embodiment] Next, a cell and a cell stack device according to a second embodiment will be described with reference to FIGS. 7A and 7B.

[0084] In the above-described embodiment, a so-called "vertical stripe type" was exemplified, in which only one element unit including a fuel electrode, a solid electrolyte layer, and an air electrode was provided on the surface of a support substrate. However, the present invention can also be applied to a horizontal stripe type cell stack device in which so-called "horizontal stripe type" cells are arranged, in which element units are provided at multiple locations spaced apart from each other on the surface of a support substrate, and adjacent element units are electrically connected.

[0085] FIG. 7A is a cross-sectional view showing a cell according to a second embodiment. In a cell stack device 10A, multiple cells 1A extend in a longitudinal direction L from a pipe 73 through which fuel gas flows. Each cell 1A has multiple element units 3A on a support substrate 2. A gas flow path 2a through which gas flows from the pipe 73 is provided inside the support substrate 2. The element units 3A on the support substrate 2 are electrically connected by a connecting layer (not shown). The multiple cells 1A are electrically connected to each other via conductive members 18. The conductive members 18 are located between the element units 3A of each cell 1A and electrically connect adjacent cells 1A. Specifically, the conductive members 18 electrically connect the current collector or interconnector electrically connected to the air electrode of the element unit 3A of one of the adjacent cells 1A to the current collector or interconnector electrically connected to the anode of the element unit 3A of the other cell 1A.

[0086] 7B is an enlarged cross-sectional view of a conductive member according to the second embodiment. As shown in FIG. 7B, conductive member 18 is bonded to adjacent cells 1A via bonding material 50. Conductive member 18 has first surface 181 and second surface 182 that face each other with base material 40 interposed therebetween. Conductive member 18 also has third surfaces 183 and 184 that connect first surface 181 and second surface 182.

[0087] The conductive member 18 is bonded to the cell 1A via a bonding material 50. The bonding material 50 is located between a first surface 181 of the conductive member 18 and the element unit 3A of one of the cells 1A, and between a second surface 182 of the conductive member 18 and the element unit 3A of the other cell 1A, and bonds the pair of cells 1A and the conductive member 18 facing each other across the conductive member 18. In addition, the third surfaces 183 and 184 are exposed to an oxidizing atmosphere, such as air.

[0088] The conductive member 18 has a substrate 40, a covering portion 43, and a coating layer 44. The substrate 40 also has a first substrate layer 41 and a second substrate layer 42. Each part constituting the conductive member 18 can be made of, for example, the same materials as those used for the conductive member 18 according to the first embodiment described above.

[0089] The coating portion 43 is located on the substrate 40. The coating portion 43 is located between the substrate 40 and the coating layer 44. The coating portion 43 contains a first element 43a. The first element 43a has a first ionization energy and an absolute value of the free energy of formation of an oxide that are smaller than those of chromium. The coating portion 43 may contain, for example, a plurality of first elements 43a. The coating portion 43 may contain a first oxide that is an oxide of the first element 43a. The coating portion 43 may be a plurality of particles located on the substrate 40 and / or a coating that coats the substrate 40. The coating portion 43 may contain, for example, CeO2.

[0090] In this way, the conductive member 18 is positioned on the substrate 40 and has the coating portion 43 containing the first element 43a, which suppresses the growth of the second substrate layer 42, and therefore the conductive member 18 can suppress an increase in internal resistance that accompanies the growth of the second substrate layer 42. This reduces the deterioration of the battery performance of the cell 1A, and therefore reduces the deterioration of the battery performance of the cell stack device 10A.

[0091] [Third embodiment] Fig. 8A is a perspective view showing a flat cell according to a third embodiment, and Fig. 8B is a partial cross-sectional view of the flat cell shown in Fig. 8A.

[0092] 8A, cell 1B has an element portion 3B in which an anode 5, a solid electrolyte layer 6, and an air electrode 8 are stacked. In a cell stack device in which a plurality of flat-type cells are stacked, for example, the plurality of cells 1B are electrically connected by conductive members 91, 92, which are adjacent metal layers. The conductive members 91, 92 electrically connect adjacent cells 1B to each other and have gas flow paths that supply gas to the anode 5 or the air electrode 8.

[0093] 8B, in this modification, the conductive member 92 has a gas flow path 93 that supplies gas to the air electrode 8. The conductive member 92 is bonded to the element section 3B (air electrode 8) via a bonding material 50. The conductive member 92 may be in direct contact with the element section 3B without the bonding material 50. In other words, in this modification, the conductive member 92 may be directly connected to the element section 3B without using the bonding material 50.

[0094] The conductive member 92 has a substrate 40, a coating portion 43 containing a first element 43a, and a coating layer 44. The substrate 40 also has a first substrate layer 41 and a second substrate layer 42. Each part constituting the conductive member 92 can be made of, for example, the same materials as those used for the conductive member 18 described above.

[0095] The coating portion 43 is located on the substrate 40. The coating portion 43 is located between the substrate 40 and the coating layer 44. The first element 43a has a first ionization energy and an oxide formation free energy whose absolute values ​​are smaller than those of chromium. The coating portion 43 may contain, for example, a plurality of the first elements 43a. The coating portion 43 may contain a first oxide which is an oxide of the first element 43a. The coating portion 43 may be a plurality of particles located on the substrate 40 and / or a coating that coats the substrate 40. The coating portion 43 may contain, for example, CeO2.

[0096] In this way, since the conductive member 18 is located on the substrate 40 and has the coating portion 43 containing the first element 43a, the growth of the second substrate layer 42 is suppressed, and the conductive member 18 can suppress an increase in internal resistance that accompanies the growth of the second substrate layer 42. This reduces the deterioration of the battery performance of the cell 1B, and therefore reduces the deterioration of the battery performance of the cell stack device.

[0097] <Other variations> Next, a cell stack device according to another modified example of the embodiment will be described.

[0098] In the above embodiments, a fuel cell, a fuel cell stack device, a fuel cell module, and a fuel cell device are shown as examples of a "cell," a "cell stack device," a "module," and a "module accommodating device," but other examples may be an electrolytic cell, an electrolytic cell stack device, an electrolytic module, and an electrolytic device, respectively.

[0099] The present disclosure has been described in detail above, but the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure.

[0100] As described above, the conductive member 18 according to the embodiment includes the base material 40 and the coating portion 43 located on the base material 40 and containing the first element 43a. The base material 40 contains chromium. The first element 43a has a first ionization energy and an oxide formation free energy whose absolute values ​​are smaller than those of chromium. This can reduce an increase in the internal resistance of the conductive member 18.

[0101] The cell 1 according to the embodiment includes the element section 3 and the conductive member 18 described above. The conductive member 18 is connected to the element section 3. This allows the cell 1 to reduce the degradation of battery performance that accompanies an increase in internal resistance.

[0102] Furthermore, the cell stack device 10 according to the embodiment has a cell stack 11 including a plurality of the above-described cells 1. This makes it possible to provide a cell stack device 10 that reduces the degradation of battery performance that accompanies an increase in internal resistance.

[0103] Furthermore, 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. This allows the module 100 to reduce the degradation of battery performance that accompanies an increase in internal resistance.

[0104] Furthermore, the module housing device 110 according to the embodiment includes the above-described module 100, accessories for operating the module 100, and an exterior case for housing the module 100 and the accessories. This allows the module housing device 110 to reduce the degradation of battery performance due to an increase in internal resistance.

[0105] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0106] 1,1A,1B cells 3,3A,3B element part 5 Fuel electrode 6 Solid electrolyte layer 7. Middle class 8 Air electrode 10 Cell stack device 11 Cell stack 12 Fixing member 13 Fixing material 14 Support member 15 Support 16 Gas Tank 17 End current collecting member 18 Conductive material 40 Base material 43 Covering part 100 modules 110 Module storage device

Claims

1. a chromium-containing substrate; a coating portion located on the substrate and containing a first element having a first ionization energy and an absolute value of a free energy of formation of an oxide that are smaller than those of chromium; a coating layer located on the substrate and having a composition different from that of the coating portion; and the covering portion is located between the substrate and the coating layer, the coating layer contains a second oxide containing Mn (manganese) and Co (cobalt), A conductive member, wherein the second oxide contained in the coating layer has a molar ratio of Mn greater than a molar ratio of Co.

2. the coating portion contains a first oxide which is an oxide of the first element; The conductive member according to claim 1 .

3. The coating layer is porous. The conductive member according to claim 1 or 2.

4. The coating portion has a plurality of particles containing the first element. The conductive member according to any one of claims 1 to 3.

5. The coating portion includes the first element and has a coating that covers the base material. The conductive member according to any one of claims 1 to 4.

6. an element portion; The conductive member according to any one of claims 1 to 5, which is connected to the element portion. A cell comprising:

7. the conductive member includes a first surface connected to the element portion, a second surface positioned away from the element portion, and a third surface connecting the first surface and the second surface; A first area ratio of the covering portion located between the first surface and the substrate is different from a second area ratio of the covering portion located between the third surface and the substrate. The cell of claim 6.

8. The first area ratio is greater than the second area ratio. The cell of claim 7.

9. an element portion; The conductive member according to claim 5 connected to the element portion. Equipped with the conductive member includes a first surface connected to the element portion, a second surface positioned away from the element portion, and a third surface connecting the first surface and the second surface; A first average thickness of the covering portion located between the first surface and the substrate is different from a second average thickness of the covering portion located between the third surface and the substrate. cell.

10. The first average thickness is greater than the second average thickness. The cell of claim 9.

11. A cell stack device having a cell stack comprising a plurality of cells according to any one of claims 6 to 10.

12. The cell stack device according to claim 11; a storage container for storing the cell stack device; A module comprising:

13. A module according to claim 12; Auxiliary equipment for operating the module; an exterior case that houses the module and the auxiliary equipment; A module housing device comprising:

Images