JP7736802B2 - Conductive member, electrochemical cell, electrochemical cell device, module, and module housing device - Google Patents

Description

The present disclosure relates to conductive members, electrochemical cells, electrochemical cell devices, modules, and module housing devices.

In recent years, various fuel cell stack devices containing multiple fuel cell cells have been proposed as next-generation energy sources. A fuel cell is a type of electrochemical cell that can generate electricity using a fuel gas such as a hydrogen-containing gas and an oxygen-containing gas such as air.

WO 2009/131180

A conductive member according to one embodiment includes a substrate and a polycrystalline film. The substrate contains chromium. The polycrystalline film includes a plurality of chromium oxide particles and is located on the substrate. The polycrystalline film includes a first element. The first element is located between the chromium oxide particles and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium.

The electrochemical cell of the present disclosure also includes an element portion and the conductive member described above. The conductive member is connected to the element portion.

The electrochemical cell device disclosed herein also has a cell stack including the electrochemical cell described above.

The module of the present disclosure also includes the electrochemical cell device described above and a storage container for housing the electrochemical cell device.

The module housing device of the present disclosure also includes the module described above, auxiliary equipment for operating the module, and an outer case for housing the module and auxiliary equipment.

FIG. 1A is a cross-sectional view showing an example of an electrochemical cell according to a first embodiment. FIG. 1B is a side view of an example of the electrochemical cell according to the first embodiment, viewed from the air electrode side. FIG. 1C is a side view of an example of the electrochemical cell according to the first embodiment, viewed from the interconnector side. FIG. 2A is a perspective view showing an example of an electrochemical cell device according to the first embodiment. FIG. 2B is a cross-sectional view taken along line XX shown in FIG. 2A. FIG. 2C is a top view illustrating an example of the electrochemical cell device according to the first embodiment. FIG. 3 is a cross-sectional view illustrating an example of a conductive member according to the embodiment. FIG. 4A is a cross-sectional view taken along line AA shown in FIG. FIG. 4B is an enlarged view of region B shown in FIG. 4A. FIG. 4C is an enlarged view of the polycrystalline film shown in FIG. 4B. FIG. 5 is an external perspective view illustrating an example of a module according to the first embodiment. FIG. 6 is an exploded perspective view schematically illustrating an example of a module housing device according to the first embodiment. FIG. 7A is a cross-sectional view showing an electrochemical cell according to a second embodiment. FIG. 7B is an enlarged cross-sectional view of the conductive member according to the second embodiment. FIG. 8A is a perspective view showing an electrochemical cell according to a third embodiment. FIG. 8B is a partial cross-sectional view of the electrochemical cell shown in FIG. 8A. FIG. 8C is a partial cross-sectional view of the electrochemical cell shown in FIG. 8A. FIG. 9A is a cross-sectional view showing an example of an electrochemical cell according to a fourth embodiment. FIG. 9B is a cross-sectional view showing another example of the electrochemical cell according to the fourth embodiment. FIG. 9C is a cross-sectional view showing another example of the electrochemical cell according to the fourth embodiment. FIG. 9D is an enlarged cross-sectional view of region C shown in FIG. 9A.

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

It should also be noted that the drawings are schematic and that the dimensional relationships and proportions of each element may differ from reality. Furthermore, there may be parts in the drawings where the dimensional relationships and proportions differ.

[First embodiment]
<Electrochemical cell configuration>
1A to 1C, an electrochemical cell according to a first embodiment will be described using an example of a solid oxide fuel cell. The electrochemical cell device may include a cell stack having a plurality of electrochemical cells. An electrochemical cell device having a plurality of electrochemical cells will be simply referred to as a cell stack device.

Figure 1A is a cross-sectional view showing an example of an electrochemical cell according to the first embodiment, Figure 1B is a side view of an example of an electrochemical cell according to the first embodiment viewed from the air electrode side, and Figure 1C is a side view of an example of an electrochemical cell according to the first embodiment viewed from the interconnector side. Note that Figures 1A to 1C show enlarged views of portions of each component of the electrochemical cell. Hereinafter, the electrochemical cell may also be simply referred to as a cell.

In the example shown in Figures 1A to 1C, cell 1 is a hollow, flat, elongated plate. As shown in Figure 1B, the shape of cell 1 as a whole 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 width direction W perpendicular to this length direction L of, for example, 1 cm to 10 cm. The overall thickness of cell 1 in the thickness direction T is, for example, 1 mm to 5 mm.

As shown in Figure 1A, the cell 1 comprises a conductive support substrate 2, an element section 3, and an interconnector 4. The support substrate 2 is columnar, having a pair of opposing first and second surfaces n1 and n2, and a pair of arc-shaped side surfaces m connecting the first and second surfaces n1 and n2.

The element section 3 is located on the first surface n1 of the support substrate 2. The element section 3 has a fuel electrode 5, a solid electrolyte layer 6, and an air electrode 8. In the example shown in FIG. 1A, the interconnector 4 is located on the second surface n2 of the cell 1. The cell 1 may also have an intermediate layer 7 between the solid electrolyte layer 6 and the air electrode 8.

Also, as shown in Figure 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 first face n1. Also, as shown in Figure 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. Note that, as shown in Figure 1A, the solid electrolyte layer 6 is exposed on the surface of a pair of arcuate side faces m of the cell 1. The interconnector 4 does not have to extend to the lower end of the cell 1.

Below, we will explain each component that makes up cell 1.

The support substrate 2 has gas flow channels 2a therein through which gas flows. The example of the support substrate 2 shown in Figure 1A has six gas flow channels 2a. The support substrate 2 is gas permeable, allowing the gas flowing through the gas flow channels 2a to pass through to the fuel electrode 5. The support substrate 2 may be conductive. The conductive support substrate 2 collects electricity generated in the element section 3 to the interconnector 4.

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.

A commonly known material can be used for the fuel electrode 5. The fuel electrode 5 may be a porous conductive ceramic containing an electronically conductive material and an ionically conductive material. Examples of the conductive ceramic include ceramics containing calcium oxide, magnesium oxide, or _ZrO2 solid-solubilized with a rare earth element oxide, and Ni and/or NiO. The rare earth element oxide may contain, for example, a plurality of rare earth elements selected from Sc, Y, La, Nd, Sm, Gd, Dy, and Yb. Calcium oxide, magnesium oxide, or _ZrO2 solid-solubilized with a rare earth element oxide is sometimes referred to as stabilized zirconia. Stabilized zirconia also includes partially stabilized zirconia.

The solid electrolyte layer 6 is an electrolyte that transfers 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 less likely for fuel gas and oxygen-containing gas to leak.

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.

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%, particularly 30% to 50%. The open porosity of the air electrode 8 is sometimes referred to as the porosity of the air electrode 8.

There are no particular limitations 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 ABO ₃ type perovskite oxide.

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 LaxSr1 _{- xCoyFe1} - _yO3 , _{LaxSr1 -xMnO3} , _{LaxSr1 - xFeO3} , _{and LaxSr1 - xCoO3} , where x is 0<x< ₁ and y is 0<y< ₁ .

Furthermore, when the element unit 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.

There are no particular restrictions on the material of intermediate layer 7, as long as it is generally used as an element diffusion suppression layer between air electrode 8 and solid electrolyte layer 6. The material of intermediate layer 7 may include, for example, cerium oxide (CeO ₂ ) in which a rare earth element other than Ce (cerium) is dissolved. Examples of such rare earth elements that may be used include Gd (gadolinium) and Sm (samarium).

Furthermore, the interconnector 4 is dense, making it less likely for 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 to leak. The interconnector 4 may have a relative density of 93% or more, particularly 95% or more.

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 resistant to reduction and oxidation even when in contact with fuel gases such as hydrogen-containing gases and oxygen-containing gases such as air.

<Configuration of electrochemical cell device>
Next, an electrochemical cell device 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 the electrochemical cell device according to the first embodiment, Figure 2B is a cross-sectional view taken along line X-X shown in Figure 2A, and Figure 2C is a top view showing an example of the electrochemical cell device according to the first embodiment.

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

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 member 14, which is made of metal, has electrical conductivity.

As shown in Figure 2B, the support body 15 has insertion holes 15a into which the lower ends of the multiple cells 1 are inserted. The lower ends of the multiple cells 1 and the inner wall of the insertion holes 15a are joined with fixing material 13.

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

In the example shown in Figure 2A, fuel gas is stored in an internal space 22 formed by the support member 15, which is the support member 14, and the 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 the gas flow path 2a (see Figure 1A) inside the cell 1. The fuel gas supplied to the gas tank 16 is generated in a reformer 102 (see Figure 5), which will be described later.

Hydrogen-rich fuel gas can be produced by steam reforming the raw fuel. When fuel gas is produced by steam reforming, the fuel gas contains water vapor.

The example shown in Figure 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 respective support 15. The gas tank 16 has two through holes on its top surface. A respective support 15 is disposed in each through hole. The internal space 22 is formed by one gas tank 16 and two supports 15.

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, may be greater than the distance between the two end current collecting members 17 located at both ends of the cell stack 11. The width of the insertion hole 15a may be greater than the length of the cell 1 in the width direction W (see Figure 1A).

As shown in Figure 2B, the joint between the inner wall of the insertion hole 15a and the lower end of the cell 1 is filled with a fixing material 13 and solidified. 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.

The fixing material 13 and the bonding material 21 may be made of a low-conductivity material such as glass. Specific materials for the fixing material 13 and the bonding material 21 may include amorphous glass, and in particular, crystallized glass.

As the crystallized glass, for example, any of SiO ₂ —CaO-based, MgO—B ₂ O _3- based, La ₂ O ₃ —B ₂ O ₃ —MgO-based, La ₂ O ₃ —B ₂ O ₃ —ZnO-based, SiO ₂ —CaO—ZnO-based materials may be used, and in particular, SiO ₂ —MgO-based materials may be used.

As shown in Figure 2B, a conductive member 18 is interposed between adjacent cells 1 among the multiple cells 1. The conductive member 18 electrically connects the fuel electrode 5 of one adjacent cell 1 to the air electrode 8 of the other cell 1 in series. More specifically, it connects the interconnector 4 electrically connected to the fuel electrode 5 of one adjacent cell 1 to the air electrode 8 of the other cell 1. Details of the conductive member 18 connected to adjacent cells 1 will be described later.

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

As shown in Figure 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 portion 19 of the cell stack device 10 is divided into a positive terminal 19A, a negative terminal 19B, and a connection terminal 19C.

The positive terminal 19A is the positive electrode when the power generated by the cell stack 11 is output to the outside, and is electrically connected to the positive-side end current collector 17 of the cell stack 11A. The negative terminal 19B is the negative electrode when the power generated by the cell stack 11 is output to the outside, and is electrically connected to the negative-side end current collector 17 of the cell stack 11B.

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

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

As shown in Figure 3, the conductive member 18 has a connection portion 18a that connects to one adjacent cell 1 and a connection portion 18b that connects to the other cell 1. The conductive member 18 also has connecting 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 adjacent cells 1 in the thickness direction T. Note that Figure 3 shows a simplified shape of the cell 1.

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.

Figure 4A is a cross-sectional view taken along line A-A in Figure 3. Figure 4B is an enlarged view of region B in Figure 4A.

The conductive member 18 extends in the longitudinal direction L of the cell 1. As shown in Figure 4A, the connection portions 18a, 18b of the conductive member 18 are positioned alternately 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.

As shown in FIG. 4B, the conductive member 18 has a substrate 41, a polycrystalline film 42, and a coating layer 43. The conductive member 18 also has a first surface 181 and a second surface 182 located at both ends of the thickness direction T of the cell 1. The conductive member 18 also has third surfaces 183 and 184 connecting the first surface 181 and the second surface 182.

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

The substrate 41 is electrically conductive and heat resistant. The substrate 41 contains chromium. The substrate 41 is, for example, stainless steel. The substrate 41 may also contain, for example, a metal oxide.

Figure 4C is an enlarged view of the polycrystalline film shown in Figure 4B. The polycrystalline film 42 is located on a substrate 41. As shown in Figure 4C, the polycrystalline film 42 includes a plurality of chromium oxide particles 421 and first particles 422.

The chromium oxide particles 421 contain, for example, chromium oxide (Cr ₂ O ₃ ). When the base material 41 contains the chromium oxide particles 421 in this manner, the durability of the conductive member 18 is improved. The chromium oxide particles 421 may have, for example, an average particle size (circle equivalent diameter) of 500 nm or less, particularly 100 nm to 350 nm. The chromium oxide particles 421 may also contain components other than chromium oxide. The chromium oxide particles 421 may not contain the first element. Details of the first element will be described later.

The first particles 422 are located between the chromium oxide particles 421. The first particles 422 contain a first element. The first element has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium. Examples of the first element include Y, Ce, Eu, Gd, Pr, Yb, and Zr. The free energy of formation is also referred to as the Gibbs energy of formation. The free energy of formation can be found in a thermodynamic database, such as the "Nuclear Fuel and Nuclear Materials Thermodynamics Database." The first element may be, in particular, any of Ce, Eu, Pr, and Zr. The first _element may be located in the first particles 422 as an oxide _of such an element. Examples of such oxides of the first element include _Y2O3 , _CeO2 , EuO, _Gd2O3 , _PrO2 , _Yb2O3 , _{and ZrO2} .

The first particles 422 may contain, for example, one or more of the first elements. The first particles 422 may also contain elements other than the first element. The first particles 422 may contain, for example, _CeO2 solid-solubilized with Sm (samarium) or Gd (gadolinium), or may contain _ZrO2 solid-solubilized with Sc (scandium), Y (yttrium), Yb (ytterbium), or the like, so-called stabilized zirconia or partially stabilized zirconia. The first particles 422 may also contain a composite oxide containing the first _{element ,} such as _Ce2Ti2O7 .

The polycrystalline film 42 may have, for example, a grain boundary phase containing the first element between the chromium oxide particles 421. The grain boundary phase containing the first element may contain, for example, 0.1 atomic % or more of the first element.

The polycrystalline film 42 may, for example, have a flat interface with the substrate 41, or may have an uneven, wavy interface with the substrate 41.

The polycrystalline film 42 may also contain, for example, Si. For example, if the polycrystalline film 42 has irregularities at the interface with the substrate 41, such Si may be located at the tips of the protrusions that protrude toward the substrate 41.

In this way, since the polycrystalline film 42 of the conductive member 18 contains the first element, the Cr in the substrate 41 is less likely to diffuse, making it more difficult for the polycrystalline film 42 to grow. This reduces the deterioration of the power generation performance of the cell 1.

The thickness of the polycrystalline film 42 may be, for example, 20 nm or more and 5 μm or less, or even 200 nm or more and 1.5 μm or less. When the polycrystalline film 42 has such a thickness, for example, the effect of the polycrystalline film 42 on the internal resistance is reduced, making the internal resistance of the conductive member 18 less likely to increase. This reduces the deterioration of the power generation performance of the cell 1.

The conductive member 18 may have an oxide of the first element located on the polycrystalline _film 42. The oxide of the first element may be, for example, _Y2O3 , _CeO2 , _EuO , _Gd2O3 , _PrO2 , _Yb2O3 , _{or ZrO2} .

The presence or absence of the first element and the size of the first particles 422 containing the first element can be confirmed, for example, by mapping the first element on a cross section of the conductive member 18 using a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM), a focused ion beam scanning electron microscope (FIB-SEM), or an electron probe microanalyzer (EPMA). The average thickness of the polycrystalline film 42 can be obtained, for example, by using a HAADF-STEM with an acceleration voltage of 200 kV to map chromium and the first element 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 chromium and the first element are detected, and calculating the average value.

Such a conductive member 18 can be obtained by forming a coating containing the first element on the surface of a chromium-containing substrate 41 and then heat-treating the coating containing the first element and the substrate 41. The coating containing the first element may be, for example, an oxide coating of the first element. The coating containing the first element may be formed, for example, by a physical vapor deposition method such as IAD (Ion Assisted Deposition) or by applying a slurry containing an oxide of the first element. The thickness of the coating containing the first element may be, for example, 1 nm to 1000 nm. The thickness of the coating containing the first element may be, for example, 5 nm to 150 nm, or even 10 nm to 100 nm. The coating containing the first element may contain oxide particles of the first element having a diameter of, for example, 30 nm or less. The coating containing the first element may contain, for example, acicular or dendritic oxide particles of the first element. The acicular or dendritic oxide particles of the first element may have a minor axis of 30 nm or less. Oxide particles of the first element having such a diameter or minor axis are likely to be arranged between particles of the polycrystalline film 42 by heat treatment. The heat treatment of the coating containing the first element and the substrate 41 may be carried out, for example, in air at a temperature of 50° C. to 1100° C. The substrate 41 does not necessarily need to contain the first element.

The coating layer 43 is located on the polycrystalline film 42. The coating layer 43 coats the polycrystalline film 42 throughout the thickness direction T and length direction L of the cell 1. The coating layer 43 contains an element different from that of the polycrystalline film 42. The coating layer 43 is, for example, conductive. By being located between the polycrystalline film 42 and the oxidizing atmosphere, the coating layer 43 can, for example, suppress the release of chromium contained in the substrate 41 and/or the polycrystalline film 42. This improves the durability of the conductive member 18, thereby improving the durability of the cell 1.

The coating layer 43 may also contain an oxide containing, for example, Mn (manganese) and Co (cobalt). The coating layer 43 may also be porous. The coating layer 43 may also have a layered structure containing different elements.

<Module>
Next, a module according to an embodiment of the present disclosure using the electrochemical cell device described above will be described with reference to Fig. 5. Fig. 5 is an external perspective view showing the module according to the first embodiment. Fig. 5 shows a state in which the front and rear surfaces, which are parts of the storage container 101, have been removed and the cell stack device 10 of the fuel cell stored inside has been removed to the rear.

As shown in Figure 5, the module 100 comprises a storage container 101 and a cell stack device 10 housed within the storage container 101. In addition, a reformer 102 is disposed above the cell stack device 10.

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 vaporization section 102a that vaporizes water, and a reforming section 102b. The reforming section 102b is equipped with 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.

The fuel gas produced in the reformer 102 is then supplied to the gas flow path 2a (see Figure 1A) of the cell 1 through the gas flow pipe 20, the gas tank 16, and the support member 14.

In addition, in the module 100 configured as described above, the temperature inside the module 100 during normal power generation reaches approximately 500°C to 1000°C due to the combustion of gas and the generation of power by cell 1.

As described above, such a module 100 is configured to house a cell stack device 10 having multiple cells 1 whose internal resistance is less likely to increase, thereby making it possible to create a module 100 that reduces the decline in power generation performance.

<Module housing 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 Fig. 6 omits some components.

The outer case 111 of the module accommodating device 110 shown in Figure 6 has support posts 112 and an outer plate 113. A partition plate 114 divides the interior of the outer case 111 into upper and lower sections. The space above the partition plate 114 in the outer case 111 is a module accommodating chamber 115 that accommodates the module 100, and the space below the partition plate 114 in the outer case 111 is an auxiliary equipment accommodating chamber 116 that accommodates the auxiliary equipment that operates the module 100. Note that in Figure 6, the auxiliary equipment accommodated in the auxiliary equipment accommodating chamber 116 is omitted.

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.

In such a module accommodation device 110, as described above, by providing a module 100 that reduces the decline in power generation performance in the module accommodation chamber 115, it is possible to create a module accommodation device 110 that reduces the decline in power generation performance.

In the above embodiment, a hollow flat support substrate is used as an example, but it can also be applied to a cell stack device using a cylindrical support substrate.

Second Embodiment
Next, an electrochemical cell and an electrochemical cell device according to a second embodiment will be described with reference to FIGS. 7A and 7B.

In the above-described embodiment, a so-called "vertical stripe type" electrochemical cell device was exemplified, in which only one element unit including a fuel electrode, a solid electrolyte layer, and an air electrode is provided on the surface of a support substrate. However, the present invention can also be applied to a horizontal stripe type electrochemical cell device in which so-called "horizontal stripe type" electrochemical 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.

Figure 7A is a cross-sectional view showing an electrochemical cell according to a second embodiment. In the cell stack device 10A, multiple cells 1A extend in the 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, electrically connecting 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 fuel electrode of the element unit 3A of the other cell 1A.

Figure 7B is an enlarged cross-sectional view of a conductive member according to the second embodiment. As shown in Figure 7B, the conductive member 18 is bonded to each of the adjacent cells 1A via a bonding material 50. The conductive member 18 also has a first surface 181 and a second surface 182 that face each other across the substrate 41. The conductive member 18 also has third surfaces 183 and 184 that connect the first surface 181 and the second surface 182.

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

The conductive member 18 has a substrate 41, a polycrystalline film 42, and a coating layer 43. Each part of the conductive member 18 can be made of a material similar to that of the conductive member 18 according to the first embodiment described above.

The polycrystalline film 42 is located on the substrate 41. The polycrystalline film 42 is located between the substrate 41 and the coating layer 43. The polycrystalline film 42 includes a plurality of chromium oxide particles 421 and a first element (see FIG. 4C). The first element is located between the chromium oxide particles 421 and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium.

In this way, by having the first element in a specific position of the polycrystalline film 42, the conductive member 18 makes it difficult for the polycrystalline film 42 to grow, and therefore the conductive member 18 is less likely to experience an increase in internal resistance due to the growth of the polycrystalline film 42. This reduces the deterioration in the power generation performance of the cell 1A, and therefore reduces the deterioration in the power generation performance of the cell stack device 10A.

[Third embodiment]
8A and 8B are perspective and partial cross-sectional views of an electrochemical cell according to a third embodiment of the present invention;

As shown in Figure 8A, cell 1B, which is a flat-plate electrochemical cell, has an element portion 3B in which a fuel electrode 5, a solid electrolyte layer 6, and an air electrode 8 are stacked. In an electrochemical cell device in which multiple flat-plate cells are stacked, for example, multiple 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 and have gas flow paths that supply gas to the fuel electrode 5 or the air electrode 8.

As shown in FIG. 8B, in this embodiment, the conductive member 92 has a gas flow path 94 that supplies gas to the air electrode 8. The conductive member 92 is bonded to the element portion 3B (air electrode 8) via a bonding material 50. Note that the conductive member 92 may also be in direct contact with the element portion 3B without the bonding material 50. In other words, in this embodiment, the conductive member 92 may be connected directly to the element portion 3B without using the bonding material 50.

The conductive member 92 has a substrate 41, a polycrystalline film 42, and a coating layer 43. Each part of the conductive member 92 can be made of a material such as the conductive member 18 described above.

The polycrystalline film 42 is located on the substrate 41. The polycrystalline film 42 is located between the substrate 41 and the coating layer 43. The polycrystalline film 42 includes a plurality of chromium oxide particles 421 and a first element (see FIG. 4C). The first element is located between the chromium oxide particles 421 and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium.

In this way, by having the first element in a specific position of the polycrystalline film 42, the conductive member 18 makes it difficult for the polycrystalline film 42 to grow, and therefore the conductive member 18 is less likely to experience an increase in internal resistance due to the growth of the polycrystalline film 42. This reduces the deterioration in the power generation performance of the cell 1B, thereby reducing the deterioration in the power generation performance of a cell stack device having multiple cells 1B.

As shown in FIG. 8C, the conductive member 91 has a gas flow path 93 that supplies fuel gas to the fuel electrode 5. The conductive member 91 is bonded to the element portion 3B (fuel electrode 5) via a bonding material 50. Note that the conductive member 91 may be in direct contact with the element portion 3B without the bonding material 50. In other words, the conductive member 91 may be directly connected to the element portion 3B without using the bonding material 50.

The conductive member 91 has a substrate 41, a polycrystalline film 42, and a coating layer 43. Each part of the conductive member 91 can be made of a material such as the conductive member 92 (conductive member 18) described above.

The polycrystalline film 42 is located on the substrate 41. The polycrystalline film 42 is located between the substrate 41 and the coating layer 43. The polycrystalline film 42 includes a plurality of chromium oxide particles 421 and a first element (see FIG. 4C). The first element is located between the chromium oxide particles 421 and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium.

In this way, by having the first element in a specific position of the polycrystalline film 42, the conductive member 91 makes it difficult for the polycrystalline film 42 to grow, and therefore the conductive member 91 is less likely to experience an increase in internal resistance due to the growth of the polycrystalline film 42. This reduces the deterioration in the power generation performance of the cell 1B, thereby reducing the deterioration in the power generation performance of an electrochemical cell device having multiple cells 1B.

8B and 8C, the conductive members 91 and 92 are described as having a coating layer 43, but one or both of the conductive members 91 and 92 may not have a coating layer 43. That is, the polycrystalline film 42 may come into contact with the gas supplied to the fuel electrode 5 or the air electrode 8. Also, in this embodiment, the conductive members 91 and 92 are described as both having a polycrystalline film 42, but one of the conductive members 91 and 92 may not have a polycrystalline film 42.

[Fourth embodiment]
Fig. 9A is a cross-sectional view showing an example of an electrochemical cell according to the fourth embodiment. Fig. 9B and Fig. 9C are cross-sectional views showing other examples of the electrochemical cell according to the fourth embodiment. Fig. 9D is an enlarged view of region C shown in Fig. 9A. Note that Fig. 9D can also be applied to the examples of Fig. 9B and Fig. 9C.

As shown in FIG. 9A, cell 1C has an element section 3C in which an anode 5, a solid electrolyte layer 6, and an air cathode 8 are stacked, and a support substrate 2. The support substrate 2 has through-holes or pores at the portion of the element section 3 that contacts the anode 5, and has a member 120 located outside the gas flow path 2a. The support substrate 2 allows gas to flow between the gas flow path 2a and element section 3C. The support substrate 2 may be composed of, for example, one or more metal plates. The material of the metal plate may contain chromium. The metal plate may have a conductive coating layer. The support substrate 2 is a conductive member that electrically connects adjacent cells 1C. The element section 3C may be formed directly on the support substrate 2, or may be bonded to the support substrate 2 with a bonding material.

In the example shown in Figure 9A, the side of the fuel electrode 5 is covered with a solid electrolyte layer 6, which airtightly seals the gas flow path 2a through which the fuel gas flows. As shown in Figure 9B, the side of the fuel electrode 5 may be covered and sealed with a dense sealing material 9. The sealing material 9 covering the side of the fuel electrode 5 may have electrical insulating properties. The material of the sealing material 9 may be, for example, glass or ceramics.

Also, as shown in Figure 9C, the gas flow path 2a of the support substrate 2 may be formed by a member 120 having an uneven surface.

In the fourth embodiment, the member 120 is joined to the air electrode 8 of another adjacent cell 1C via other conductive members such as the inter-cell connection member 60 and the bonding material 50. Note that the member 120 may also be in direct contact with the air electrode 8 of another cell 1C without the intervention of other conductive members.

As shown in FIG. 9D, member 120 has a substrate 41, a polycrystalline film 42, and a coating layer 43. Each part constituting member 120 can be made of a material such as the conductive member 18 described above. Although detailed illustrations are omitted, inter-cell connection member 60 may also be a conductive member 18 having a substrate 41, a polycrystalline film 42, and a coating layer 43.

The polycrystalline film 42 is located on the substrate 41. The polycrystalline film 42 is located between the substrate 41 and the coating layer 43. The polycrystalline film 42 includes a plurality of chromium oxide particles 421 and a first element (see FIG. 4C). The first element is located between the chromium oxide particles 421 and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium.

In this way, by having the first element at a specific position in the polycrystalline film 42, the polycrystalline film 42 is less likely to grow in the member 120, and the member 120 is less likely to experience an increase in internal resistance due to the growth of the polycrystalline film 42. This reduces the deterioration in the power generation performance of the cell 1C, and therefore reduces the deterioration in the power generation performance of an electrochemical cell device having multiple cells 1C.

In this embodiment, the polycrystalline film 42 may be formed only on a portion of the member 120. For example, in the example shown in Figure 9C, the polycrystalline film 42 and the coating layer 43 may be formed only on the first portion 120a facing the air electrode 8 of another cell 1C and the second portion 120b facing the support substrate 2. The support substrate 2 may have the polycrystalline film 42 on the portion facing the fuel electrode 5 of the cell 1C.

<Other embodiments>
Next, electrochemical cell devices according to other embodiments will be described.

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 an "electrochemical cell," "electrochemical cell device," "module," and "module housing device." However, other examples may be an electrolysis cell, an electrolysis cell stack device, an electrolysis module, and an electrolysis device, respectively. An electrolysis cell has a first electrode layer and a second electrode layer, and decomposes water vapor into hydrogen and oxygen, or carbon dioxide into carbon monoxide and oxygen, when supplied with electric power. Furthermore, in the above embodiments, an oxide ion conductor or a hydrogen ion conductor is shown as an example of the electrolyte material of the electrochemical cell, but a hydroxide ion conductor may also be used. Such electrolysis cells, electrolysis cell stack devices, electrolysis modules, and electrolysis devices can improve electrolysis performance.

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.

As described above, the conductive member 18 according to the embodiment has a substrate 41 and a polycrystalline film 42 containing a plurality of chromium oxide particles 421 and positioned on the substrate 41. The substrate 41 contains chromium. The polycrystalline film 42 contains a first element. The first element is positioned between the chromium oxide particles 421, and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium. This reduces the increase in internal resistance of the conductive member 18.

The electrochemical cell according to the embodiment also includes an element section 3 and the conductive member 18 described above. The conductive member 18 is connected to the element section 3. This allows for an electrochemical cell that reduces the degradation of cell performance associated with increased internal resistance.

Furthermore, the electrochemical cell device according to the embodiment has a cell stack 11 including a plurality of the electrochemical cells described above. This allows for an electrochemical cell device that reduces performance degradation associated with increased internal resistance.

Module 100 according to the embodiment includes the electrochemical cell device described above and a storage container 101 for storing the electrochemical cell device. This allows module 100 to reduce performance degradation due to increased internal resistance.

The module housing device 110 according to the embodiment includes the module 100 described above, accessories for operating the module 100, and an exterior case for housing the module 100 and accessories. This allows the module housing device 110 to reduce performance degradation due to increased internal resistance.

The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in a variety of 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.

REFERENCE SIGNS LIST 1, 1A, 1B, 1C Cell 3, 3A, 3B, 3C Element section 5 Anode 6 Solid electrolyte layer 7 Intermediate layer 8 Cathode 10 Cell stack device 11 Cell stack 12 Fixing member 13 Fixing material 14 Support member 15 Support body 16 Gas tank 17 End current collecting member 18 Conductive member 41 Substrate 42 Polycrystalline film 43 Coating layer 100 Module 110 Module accommodating device

Claims (13)

a chromium-containing substrate;
a polycrystalline film disposed on the substrate, the polycrystalline film including a plurality of chromium oxide particles;
the polycrystalline film includes a first element;
the first element is located between the chromium oxide particles and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium;
the polycrystalline film has a grain boundary phase located between the chromium oxide grains,
The grain boundary phase has a higher content of the first element than the chromium oxide particles . a chromium-containing metal substrate;
a polycrystalline film disposed on the substrate, the polycrystalline film including a plurality of chromium oxide particles;
the polycrystalline film includes a first element;
the first element is located between the chromium oxide particles and has a first ionization energy and a free energy of formation of an oxide per mole of oxygen that are smaller than those of chromium;
The substrate is a conductive member that does not contain the first element . The conductive member according to claim 1 or 2 , wherein the first element is one or more elements selected from the group consisting of Ce, Eu, Pr, and Zr. The conductive member according to claim 1 , wherein the first element contained in the chromium oxide particles is less than 0.1 atomic %. The conductive member according to claim 1 , wherein the grain boundary phase contains 0.1 atomic % or more of the first element. the polycrystalline film has a grain boundary phase located between the chromium oxide grains,
The conductive member according to claim 2 , wherein the grain boundary phase contains 0.1 atomic % or more of the first element. The conductive member according to claim 1 or 2 , wherein the polycrystalline film includes first particles that contain the first element and are located between the chromium oxide particles. The conductive member according to claim 1 , further comprising an oxide of the first element located on the polycrystalline film. The conductive member according to claim 1 or 2 , further comprising a conductive coating layer located on the polycrystalline film. an element portion;
An electrochemical cell comprising: the conductive member according to claim 1 or 2 connected to the element portion. An electrochemical cell device having a cell stack including the electrochemical cell of claim 10 . The electrochemical cell device according to claim 11 ;
a container for housing the electrochemical cell device. A module according to claim 12 ;
Auxiliary equipment for operating the module;
an outer case that houses the module and the auxiliary equipment.