Patent Description:
In recent years, various fuel cell stack devices each including a plurality of fuel cells have been proposed as next-generation energy, the plurality of fuel cells each being a type of cell capable of obtaining electrical power by using a fuel gas such as a hydrogen-containing gas; and an oxygen-containing gas such as air.

Moreover, <CIT>, <CIT>, <CIT>, and <CIT> also disclose solide oxide type cells.

The present invention provides a fuel cell or electrolytic cell according to claim <NUM>, a cell stack device according to claim <NUM>, a module according to claim <NUM>, and a module housing device according to claim <NUM>. Preferred embodiments are described in the dependent claims.

Hereinafter, embodiments of a conductive member, a cell, a cell stack device, a module, and a module housing device disclosed in the present specification will be described in detail with reference to the accompanying drawings. This disclosure is not limited by the following embodiments.

In addition, it should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, or the like may differ from reality. In addition, there may be differences between the drawings in the dimensional relationships, proportions, or the like.

First, with reference to <FIG>, an example of a solid oxide type fuel cell will be described as a cell according to a first embodiment.

<FIG> is a horizontal cross-sectional view illustrating an example of a cell <NUM> according to a first embodiment, <FIG> is a side view of an example of the cell according to the first embodiment when viewed from an air electrode side, and <FIG> is a side view of an example of the cell <NUM> according to the first embodiment when viewed from an interconnector side. <FIG> are enlarged views of a part of each configuration of the cell <NUM>.

In the example illustrated in <FIG>, the cell <NUM> has a hollow flat and elongated plate. As illustrated in <FIG>, the shape of the entire cell <NUM> when viewed from the side is a rectangle having a side length of, for example, <NUM> to <NUM> in a length direction L and a length of, for example, <NUM> to <NUM> in a width direction W orthogonal to the length direction L. The thickness of the entire cell <NUM> in a thickness direction T is, for example, <NUM> to <NUM>.

As illustrated in <FIG>, the cell <NUM> includes a support substrate <NUM> that is electrically conductive, an element unit <NUM>, and an interconnector <NUM>. The support substrate <NUM> is columnar with a pair of opposing flat surfaces n1 and n2, and a pair of circular arc shape side surfaces m connecting the flat surfaces n1 and n2.

The element unit <NUM> is located on the flat surface n1 of the support substrate <NUM>. The element unit <NUM> includes a fuel electrode <NUM>, a solid electrolyte layer <NUM>, and an air electrode <NUM>. Also, in the example illustrated in <FIG>, the interconnector <NUM> is located on the flat surface n2 of the cell <NUM>. The cell <NUM> includes an intermediate layer <NUM> between the solid electrolyte layer <NUM> and the air electrode <NUM>.

Also, as illustrated in <FIG>, the air electrode <NUM> does not extend to a lower end of the cell <NUM>. At the lower end of the cell <NUM>, only the solid electrolyte layer <NUM> is exposed on a surface of the flat surface n1. Also, as illustrated in <FIG>, the interconnector <NUM> may extend to the lower end of the cell <NUM>. At the lower end of the cell <NUM>, the interconnector <NUM> and the solid electrolyte layer <NUM> are exposed on the surface. As illustrated in <FIG>, the solid electrolyte layer <NUM> is exposed on the surfaces of the pair of circular arc shape side surfaces m of the cell <NUM>. The interconnector <NUM> may not extend to the lower end of the cell <NUM>.

Hereinafter, each of the components constituting the cell <NUM> will be described.

The support substrate <NUM> includes an internal gas-flow passage 2a through which gas flows. The example of the support substrate <NUM> illustrated in <FIG> includes six gas-flow passages 2a. The support substrate <NUM> has gas permeability, and allows the gas flowing in the gas-flow passage 2a to permeate to the fuel electrode <NUM>. The support substrate <NUM> may have conductivity. The support substrate <NUM>, which is electrically conductive, collects electricity generated in the element unit to the interconnector <NUM>.

The material of the support substrate <NUM> contains, for example, an iron group metal component and an inorganic oxide. For example, 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 contain, for example, one or more rare earth elements selected from Sc, Y, La, Nd, Sm, Gd, Dy, and Yb.

As the material of the fuel electrode <NUM>, generally known materials can be used. As the fuel electrode <NUM>, porous conductive ceramics, for example, ceramics containing: ZrO<NUM> in which a calcium oxide, a magnesium oxide, or a rare earth element oxide is solid-dissolved, and Ni and/or NiO may be used. This rare earth element oxide may contain a plurality of rare earth elements selected from, for example, Sc, Y, La, Nd, Sm, Gd, Dy, and Yb. ZrO<NUM> in which a calcium oxide, a magnesium oxide, or a rare earth element oxide is solid-dissolved may also be referred to as stabilized zirconia. The stabilized zirconia also includes partially stabilized zirconia.

The solid electrolyte layer <NUM> is an electrolyte and bridges ions between the fuel electrode <NUM> and the air electrode <NUM>. At the same time, the solid electrolyte layer <NUM> has a gas blocking property and prevents leakage between a fuel gas and an oxygen-containing gas.

The material of the solid electrolyte layer <NUM> may be, for example, ZrO<NUM> in which <NUM> mol% to <NUM> mol% of a rare earth element oxide is solid-dissolved. The rare earth element oxide may contain, for example, one or more rare earth elements selected from Sc, Y, La, Nd, Sm, Gd, Dy, and Yb. The solid electrolyte layer <NUM> may contain, for example, ZrO<NUM> in which Yb, Sc, or Gd is solid-dissolved, CeO<NUM> in which La, Nd, or Yb is solid-dissolved, BaZrO<NUM> in which Sc or Yb is solid-dissolved, or BaCeO<NUM> in which Sc or Yb is solid-dissolved.

The air electrode <NUM> has gas permeability. The open porosity of the air electrode <NUM> may be, for example, in the range of <NUM>% to <NUM>%, particularly <NUM>% to <NUM>%. The open porosity of the air electrode <NUM> may also be referred to as the porosity of the air electrode <NUM>.

The material of the air electrode <NUM> is not particularly limited as long as it is generally used for the air electrode. The material of the air electrode <NUM> may be, for example, conductive ceramics such as a so-called ABO<NUM> type perovskite oxide.

The material of the air electrode <NUM> may be, for example, a composite oxide in which strontium (Sr) and lanthanum (La) coexist at the A site. Examples of such a composite oxide include LaxSr<NUM>-xCoyFe<NUM>-yO<NUM>, LaxSr<NUM>-xMnO<NUM>, LaxSr<NUM>-xFeO<NUM>, and LaxSr<NUM>-xCoO<NUM>. Here, x is <NUM> < x < <NUM> and y is <NUM> < y < <NUM>.

Also, when the element unit <NUM> has the intermediate layer <NUM>, the intermediate layer <NUM> has a function as a diffusion prevention layer. When strontium (Sr) contained in the air electrode <NUM> diffuses into the solid electrolyte layer <NUM>, a resistance layer of SrZrO<NUM> is formed in the solid electrolyte layer <NUM>. The intermediate layer <NUM> makes it difficult for Sr to diffuse, thereby making it difficult for SrZrO<NUM> to be formed.

The material of the intermediate layer <NUM> is not particularly limited as long as it is generally used for the diffusion prevention layer of Sr. The material of the intermediate layer <NUM> may contain, for example, a cerium oxide (CeO<NUM>) in which rare earth elements other than cerium (Ce) are solid-dissolved. As such rare earth elements, for example, gadolinium (Gd), samarium (Sm), or the like may be used.

Also, the interconnector <NUM> is dense and prevents leakage of the fuel gas flowing through the gas-flow passage 2a located inside the support substrate <NUM> and the oxygen-containing gas flowing outside the support substrate <NUM>. The interconnector <NUM> may have a relative density of <NUM>% or more, particularly <NUM>% or more.

As the material of the interconnector <NUM>, a lanthanum chromite-based perovskite oxide (LaCrO<NUM>-based oxide), a lanthanum strontium titanium-based perovskite oxide (LaSrTiO<NUM>-based oxide), or the like may be used. These materials are electrically conductive and are not reduced or oxidized even in contact with a fuel gas such as a hydrogen-containing gas and an oxygen-containing gas such as air.

Next, a cell stack device <NUM> according to the present embodiment using the cell <NUM> mentioned above will be described with reference to <FIG>. <FIG> is a perspective view illustrating an example of a cell stack device according to the first embodiment, <FIG> is a cross-sectional view taken along line X-X illustrated in <FIG>, and <FIG> is a top view illustrating an example of the cell stack device according to the first embodiment.

As illustrated in <FIG>, the cell stack device <NUM> includes a cell stack <NUM> including a plurality of cells <NUM> arranged (stacked) in a thickness direction T (see <FIG>) of the cell <NUM>, and a fixing member <NUM>.

The fixing member <NUM> includes a fixing material <NUM> and a support member <NUM>. The support member <NUM> supports the cell <NUM>. The fixing material <NUM> fixes the cell <NUM> to the support member <NUM>. The support member <NUM> includes a support body <NUM> and a gas tank <NUM>. The support body <NUM> and the gas tank <NUM>, as the support member <NUM>, are made of metal and electrically conductive.

As illustrated in <FIG>, the support body <NUM> includes an insertion hole 15a into which the lower ends of the plurality of cells <NUM> are inserted. The lower ends of the plurality of cells <NUM> and the inner wall of the insertion hole 15a are joined by a fixing material <NUM>.

The gas tank <NUM> includes an opening for supplying a reactive gas to the plurality of cells <NUM> through the insertion hole 15a, and a recessed groove 16a located around the opening. The outer peripheral end portion of the support body <NUM> is joined to the gas tank <NUM> by a jointing material <NUM> with which the recessed groove 16a of the gas tank <NUM> is filled.

In the example illustrated in <FIG>, a fuel gas is stored in an internal space <NUM> formed by the support body <NUM> and the gas tank <NUM>, which constitute the support member <NUM>. A gas flow pipe <NUM> is connected to the gas tank <NUM>. A fuel gas is supplied to the gas tank <NUM> through the gas flow pipe <NUM>, and supplied from the gas tank <NUM> to the gas-flow passage 2a (see <FIG>) inside the cell <NUM>. The fuel gas supplied to the gas tank <NUM> is generated by a reformer <NUM> (see <FIG>) to be described later.

A hydrogen-rich fuel gas can be produced by, for example, steam reforming the raw fuel. When the fuel gas is produced by steam reforming, the fuel gas contains steam.

The example illustrated in <FIG> includes two rows of cell stacks <NUM>, two support bodies <NUM>, and the gas tank <NUM>. Two rows of cell stacks <NUM> each have a plurality of cells <NUM>. Each cell stack <NUM> is fixed to each support body <NUM>. The gas tank <NUM> includes two through holes on its upper surface. Each support body <NUM> is disposed in each through hole. The internal space <NUM> is formed by one gas tank <NUM> and two support bodies <NUM>.

The shape of the insertion hole 15a has, for example, an oval shape in a top surface view. The insertion hole 15a is configured, for example, to have a length in the array direction or thickness direction T of the cell <NUM> is greater than the distance between the two end current collectors <NUM> located at the both ends of the cell stack <NUM>. The width of the insertion hole 15a is, for example, greater than the length in the width direction W of the cell <NUM> (see <FIG>).

As illustrated in <FIG>, the joined portion between the inner wall of the insertion hole 15a and the lower end of the cells <NUM> is filled with the fixing material <NUM>. Thus, the inner wall of the insertion hole 15a and each of the lower ends of the plurality of cells <NUM> are joined and fixed, and the lower ends of the cells <NUM> are joined and fixed to each other. The gas-flow passage 2a of each cell <NUM>, at its lower end, communicates with the internal space <NUM> of the support member <NUM>.

The fixing material <NUM> and the jointing material <NUM> may be made of a material having low conductivity such as glass. As the specific materials of the fixing material <NUM> and the jointing material <NUM>, amorphous glass or the like may be used, and especially, crystallized glass or the like may be used.

As the crystallized glass, for example, any of SiO<NUM>-CaO-based, MgO-B<NUM>O<NUM>-based, La<NUM>O<NUM>-B<NUM>O<NUM>-MgO-based, La<NUM>O<NUM>-B<NUM>O<NUM>-ZnO-based, and SiO<NUM>-CaO-ZnO-based materials may be used, or particularly, a SiO<NUM>-MgO-based material may be used.

Also, as illustrated in <FIG>, conductive members <NUM> are each interposed between the adjacent cells <NUM> among the plurality of cells <NUM>. The conductive member <NUM> electrically connects, in series, the fuel electrode <NUM> of one of the adjacent cells <NUM> and the air electrode <NUM> of the other one of the adjacent cells <NUM>. More specifically, the conductive member <NUM> electrically connects the interconnector <NUM> electrically connected to the fuel electrode <NUM> of the one of the adjacent cells <NUM> and the air electrode <NUM> of the other one of the adjacent cells <NUM>. The conductive member <NUM> connected to the adjacent cells <NUM> will be described in detail later.

As illustrated in <FIG>, the end current collector <NUM> is electrically connected to each of the outermost cells <NUM> in the array direction of the plurality of cells <NUM>. The end current collectors <NUM> are each connected to a conductive portion <NUM> protruding outside the cell stack <NUM>. The conductive portions <NUM> collect and draw out the electricity generated due to power generation by the cells <NUM>. In <FIG>, the end current collectors <NUM> are not illustrated.

As illustrated in <FIG>, in the cell stack device <NUM>, two cell stacks 11A and 11B are connected in series and function as one battery. Therefore, a conductive portion <NUM> of the cell stack device <NUM> is divided into a positive terminal 19A, a negative terminal 19B, and a connection terminal 19C.

The positive terminal 19A is a positive electrode for outputting the electrical power generated by the cell stack <NUM> to the outside, and is electrically connected to the end current collector <NUM> on the positive electrode side in the cell stack 11A. The negative terminal 19B is a negative electrode for outputting the electrical power generated by the cell stack <NUM> to the outside, and is electrically connected to the end current collector <NUM> on the negative electrode side in the cell stack 11B.

The connection terminal 19C electrically connects the end current collector <NUM> on the negative electrode side in the cell stack 11A and the end current collector <NUM> on the positive electrode side in the cell stack 11B.

Subsequently, details of the conductive member <NUM> according to the first embodiment will be described in detail with reference to <FIG>, <FIG>, and <FIG>. <FIG> is a horizontal cross-sectional view illustrating an example of a conductive member according to an embodiment.

As illustrated in <FIG>, the conductive member <NUM> includes connection portions 18a connected to one of the adjacent cells <NUM> and connection portions 18b connected to the other one of the adjacent cells <NUM>. Also, the conductive member <NUM> includes connecting portions 18c at both ends in the width direction W to connect the connection portions 18a and 18b. This enables the conductive member <NUM> to electrically connect the cells <NUM> adjacent to each other in the thickness direction T. In <FIG>, the shape of the cell <NUM> is illustrated by simplification.

Also, the connection portions 18a and 18b each include a first surface <NUM> facing the cell <NUM> and a second surface <NUM> facing the connection portions 18b and 18a.

<FIG> is a cross-sectional view taken along line A-A illustrated in <FIG>. <FIG> is an enlarged view of region B illustrated in <FIG>.

The conductive member <NUM> extends in the length direction L of the cell <NUM>. As illustrated in <FIG>, a plurality of the connection portions 18a and 18b of the conductive member <NUM> are alternately located along the length direction L of the cell <NUM>. The conductive member <NUM> is in contact with the cell <NUM> at each of the connection portions 18a and 18b.

Also, as illustrated in <FIG>, the conductive member <NUM> includes a base material <NUM>, a covering part <NUM>, and a coating layer <NUM>. The coating layer <NUM> has conductivity. Also, the conductive member <NUM> has the first surface <NUM> and the second surface <NUM> that face each other with the base material <NUM> interposed therebetween. Also, the conductive member <NUM> has third surfaces <NUM> and <NUM> that connect the first surface <NUM> and the second surface <NUM>.

The conductive member <NUM> (connection portion 18b) is joined to the cell <NUM> via a jointing material <NUM>. The jointing material <NUM> is located between the first surface <NUM> of the conductive member <NUM> and the cell <NUM>, and joins the conductive member <NUM> and the cell <NUM>. Also, the second surface <NUM> and the third surfaces <NUM> and <NUM> are exposed to, for example, an oxidizing atmosphere such as air.

The base material <NUM> has electrical conductivity and heat resistance. The base material <NUM> contains chromium. The base material <NUM> is, for example, stainless steel. The base material <NUM> may contain, for example, a metal oxide.

Also, the base material <NUM> may also have a laminated structure. In the example illustrated in <FIG>, the base material <NUM> includes a first base material layer <NUM> and a second base material layer <NUM>. The second base material layer <NUM> may have a higher chromium content than the first base material layer <NUM>, for example. The second base material layer <NUM> contains, for example, a chromium oxide (Cr<NUM>O<NUM>). In this way, as the base material <NUM> has the second base material layer <NUM>, the durability of the conductive member <NUM> is enhanced. The base material <NUM> may or may not have the second base material layer <NUM> partially. Also, the base material <NUM> may have a further laminated structure.

The covering part <NUM> is located on the base material <NUM>. The covering part <NUM> is located between the base material <NUM> and the coating layer <NUM>. The covering part <NUM> contains a first element 43a selected from Ce, Eu, Pr, and Zr. The first element 43a has a smaller value of first ionization energy and a smaller absolute value of free energy formation of oxide than chromium. The free energy of formation is also called Gibbs energy of formation. The free energy of formation can be confirmed in, for example, a thermodynamic database such as "Thermodynamic Database for Nuclear Fuels and Reactor Materials". The first element 43a may be located on the base material <NUM> as an oxide of such an element. Examples of the oxide of the first element 43a include CeO<NUM>, EuO, PrO<NUM>, and ZrO<NUM>. Hereinafter, the oxide of the first element 43a is referred to as a first oxide.

The covering part <NUM> may be a plurality of particles located on the base material <NUM> and containing the first element 43a. Also, the covering part <NUM> may be a coating film containing the first element 43a and covering the base material <NUM>. The covering part <NUM> may be one coating film covering the entire base material <NUM>, or may be located on the base material <NUM> as a mesh-like coating film or a plurality of island-like coating films separated from each other. The plurality of particles and coating films containing the first element 43a are collectively referred to as the covering part <NUM>. The covering part <NUM> may contain, for example, one or more of the first elements 43a. The covering part <NUM> may contain elements other than the first element 43a. The covering part <NUM> may contain, for example, CeO<NUM> in which gadolinium (Gd) is solid-dissolved, or ZrO<NUM> in which yttrium (Y), ytterbium (Yb), and the like are solid-dissolved, so-called stabilized zirconia or partially stabilized zirconia. That is, the covering part <NUM> may include a plurality of particles and/or coating films containing the first element 43a. When the covering part <NUM> has the plurality of particles and coating films containing the first element 43a, the plurality of particles may be located on the base material <NUM> or may be located on the coating film.

The covering part <NUM> can be formed on the surface of the base material <NUM> by, for example, a film formation method such as an ion-beam assisted deposition (IAD) method, a metal organic decomposition (MOD) method, a sputtering method, an aerosol deposition (AD) method, and a pulsed laser deposition (PLD) method.

The covering part <NUM> containing the first element 43a may be crystalline or amorphous. Also, a crystalline phase and an amorphous phase may be mixed in the covering part <NUM>.

In this way, since the conductive member <NUM> includes the covering part <NUM> located on the base material <NUM> and containing the first element 43a, the growth of the second base material layer <NUM> is suppressed, so that the conductive member <NUM> can suppress an increase in internal resistance due to the growth of the second base material layer <NUM>. This can reduce a decrease in the battery performance of the cell <NUM>.

The thickness of the covering part <NUM> is <NUM> or less, for example, <NUM> or more and <NUM> or less, <NUM> or more and <NUM> or less, or further <NUM> or more and <NUM> or less. When the covering part <NUM> has such a thickness, for example, the growth of the second base material layer <NUM> is suppressed, and even though the conductivity of the covering part <NUM> is small, the influence of the covering part <NUM> on the internal resistance is suppressed, so that the conductive member <NUM> can suppress an increase in the internal resistance. This can reduce a decrease in the battery performance of the cell <NUM>. For example, the conductivity of Cr<NUM>O<NUM> is <NUM>/m and the conductivity of CeO<NUM> is <NUM>/m. When a conductive member of the base material <NUM> alone or a conductive member forming the coating layer <NUM>, which will be described later, directly formed on the base material <NUM> is used at the operating temperature of the fuel cell, the thickness of the second base material layer <NUM> is about several µm, for example, <NUM>. On the other hand, when the conductive member <NUM> having the covering part <NUM> on the base material <NUM> is used at the operating temperature of the fuel cell, the thickness of the second base material layer <NUM> is <NUM> or less. Specifically, for example, in the conductive member <NUM> including CeO<NUM> having a thickness of <NUM> as a coating film, since the thickness of the second base material layer is about <NUM>, the internal resistance can be made smaller than when there is no coating film.

The presence or absence of the first element 43a and the size of the covering part <NUM> containing the first element 43a can be confirmed, for example, by mapping the first element 43a in the cross-section of the conductive member <NUM> by using a high angle annular dark field scanning transmission electron microscope (HAADF-STEM), a focus ion beam scanning electron microscope (FIB-SEM), or an electron probe microanalyzer (EPMA). Also, an average thickness of the following coating films is obtained, for example, by mapping the above element in the cross-section of the conductive member <NUM> at a magnification of <NUM> million times by using the HAADF-STEM with an accelerating voltage of <NUM> kV, measuring the thickness of a portion, where the first element 43a is detected, at <NUM> points, and calculating an average value of the thicknesses.

Also, an average thickness t1 of coating films located between the first surface <NUM> and the base material <NUM> of the conductive member <NUM> may be the same as or different from an average thickness t3 of coating films located between the third surface <NUM> and the base material <NUM> and an average thickness t4 of coating films located between the third surface <NUM> and the base material <NUM>. The average thickness t1 as a first average thickness may be greater than the average thicknesses t3 and t4 as second average thicknesses. In this way, the average thickness t1 is made greater than the average thicknesses t3 and t4, resulting in the suppression of the growth of the second base material layer <NUM> at a place close to the first surface <NUM> through which the current flows. The average thicknesses t3 and t4 may be less than <NUM>, for example. Also, the conductive member <NUM> may have no coating film in at least one of between the third surface <NUM> and the base material <NUM> and between the third surface <NUM> and the base material <NUM>. Since current may not flow easily at a place close to the third surfaces <NUM> and <NUM>, the second base material layer <NUM> may be thicker than at the place close to the first surface <NUM>. The conductive member <NUM> includes the second base material layer <NUM> that is thicker at the place close to the third surfaces <NUM> and <NUM> than the place close to the first surface <NUM>, resulting in the suppression of the oxidation of the base material <NUM>. This can reduce a decrease in the battery performance of the cell <NUM>.

The average thicknesses t3 and t4 may be greater than the average thickness t1, for example, greater than <NUM>. Since current may not flow easily at the place close to the third surfaces <NUM> and <NUM>, the average thickness t3 and t4 may be large in this way. When the average thicknesses t3 and t4 are greater than the average thickness t1, the growth of the second base material layer <NUM> is suppressed on the third surfaces <NUM> and <NUM>, and the release of chromium contained in the base material <NUM> can be suppressed. The average thickness t2 of the coating film located between the second surface <NUM> and the base material <NUM> of the conductive member <NUM> may be greater or smaller than the average thicknesses t3 and t4.

Also, a first area ratio, which is an area ratio of the covering part <NUM> located between the first surface <NUM> and the base material <NUM>, may be the same as or different from a second area ratio which is an area ratio of the covering part <NUM> located between the third surfaces <NUM> and <NUM> and the base material <NUM>. The first area ratio may be greater than the second area ratio. In this way, the first area ratio is made greater than the second area ratio, resulting in the suppression of the growth of the second base material layer <NUM> at the place close to the first surface <NUM> through which current flows. The first area ratio may be, for example, <NUM> area% or more and <NUM> area% or less. The second area ratio may be, for example, <NUM> area% or more and <NUM> area% or less. An area ratio of the covering part <NUM> located between the second surface <NUM> and the base material <NUM> may be greater than or smaller than the second area ratio.

Each of the area ratios mentioned above can be calculated as follows, for example. First, it can be confirmed by polishing the cross-section of the conductive member <NUM>, and mapping the first element 43a on the base material <NUM> by using the HAADF-STEM, the focus ion beam scanning electron microscope (FIB-SEM), or the electron probe microanalyzer (EPMA). Specifically, for example, using the HAADF-STEM with an accelerating voltage of <NUM> kV, a mapping image of the first element 43a is obtained in the cross-section of the conductive member <NUM> at a magnification of, for example, <NUM> times to <NUM> times. The obtained mapping image is image-analyzed by using the analysis software Igor manufactured by Hulinks Co. , Ltd to calculate the area ratio of the first element 43a overlapping the base material <NUM> when viewed from the normal direction of each surface. The obtained area ratio of the first element 43a is the area ratio of the covering part <NUM>.

The coating layer <NUM> covers the covering part <NUM> over the thickness direction T and the length direction L of the entire cell <NUM>. The coating layer <NUM> contains an element different from that of the covering part <NUM>. The coating layer <NUM> is located between the base material <NUM> and the oxidizing atmosphere, which makes it possible to suppress the release of chromium contained in the base material <NUM>, for example. Therefore, the durability of the conductive member <NUM> is improved, so that the durability of the cell <NUM> can be improved.

Also, the coating layer <NUM> may contain an oxide containing, for example, manganese (Mn) and cobalt (Co). Hereinafter, the oxide containing Mn and Co is referred to as a second oxide. The second oxide has electron conductivity. The second oxide has higher conductivity than Cr<NUM>O<NUM> and the first oxide. The second oxide may have higher conductivity than Cr<NUM>O<NUM> by <NUM> times, for example. A molar ratio of Mn contained in the second oxide may be greater than that of Co. The coating layer <NUM> may contain, for example, a second oxide having a molar ratio of Mn, Co, and O of <NUM> : <NUM> : <NUM>. When the coating layer <NUM> contains the second oxide having such a composition, for example, the durability of the conductive member <NUM> can be increased as compared with the coating layer <NUM> containing a second oxide having a molar ratio of Mn, Co, and O of <NUM> : <NUM> : <NUM>. The molar ratio of Mn, Co, and O can be calculated on the basis of the identification of a crystal phase using an X-ray diffractometer (XRD). Also, the second oxide may contain elements other than Mn and Co, for example, zinc (Zn), iron (Fe) and aluminum (Al). The coating layer <NUM> may or may not contain the first element 43a. When the coating layer <NUM> contains the first element 43a, the content of the first element 43a in the coating layer <NUM> is smaller than that of the first element 43a in the covering part <NUM>.

Also, the coating layer <NUM> may be porous. The coating layer <NUM> may have a porosity of <NUM>% or more and <NUM>% or less, for example. When the conductive member <NUM> includes the porous coating layer <NUM> in this way, stress applied to the conductive member <NUM> from the outside can be relieved. Therefore, the durability of the conductive member <NUM> is improved, so that the durability of the cell <NUM> can be improved.

The coating layer <NUM> can be formed by, for example, a thermal spraying method, a vapor deposition method, an electrodeposition method, a sputtering method, or the like. For example, a coating material may be coated on the covering part <NUM> or the surface of the coating film, and then fired to form the coating layer <NUM>.

Next, a module <NUM> according to an embodiment of the present disclosure using the cell stack device <NUM> mentioned above will be described with reference to <FIG> is an external appearance perspective view illustrating a module according to the first embodiment, and illustrates a state in which a front surface and a rear surface, which are a part of a housing container <NUM> are removed and the cell stack device <NUM> of the fuel cell housed therein is taken out rearward.

As illustrated in <FIG>, the module <NUM> includes the housing container <NUM> and the cell stack device <NUM> housed in the housing container <NUM>. Also, the reformer <NUM> is disposed above the cell stack device <NUM>.

The reformer <NUM> generates a fuel gas by reforming a raw fuel such as natural gas and kerosene, and supplies the fuel gas to the cell <NUM>. The raw fuel is supplied to the reformer <NUM> through the raw fuel supply pipe <NUM>. The reformer <NUM> may include a vaporizing unit 102a for vaporizing water and a reforming unit 102b. The reforming unit 102b includes a reforming catalyst (not illustrated) for reforming the raw fuel into a fuel gas. Such a reformer <NUM> can perform steam reforming, which is a highly efficient reforming reaction.

Then, the fuel gas generated by the reformer <NUM> is supplied to the gas-flow passage 2a (see <FIG>) of the cell <NUM> through the gas flow pipe <NUM>, the gas tank <NUM>, and the support member <NUM>.

Also, in the module <NUM> having the configuration mentioned above, the temperature in the module <NUM> during normal power generation is about <NUM> to <NUM> due to combustion of gas and power generation by the cell <NUM>.

In such a module <NUM>, as mentioned above, it is configured to house the cell stack device <NUM> including the plurality of cells <NUM> for reducing the deterioration of battery performance, so that the module <NUM> that reduces the decrease in the battery performance can be provided.

<FIG> is an exploded perspective view illustrating an example of a module housing device according to the first embodiment. A module housing device <NUM> according to the present embodiment includes an external case <NUM>, the module <NUM> illustrated in <FIG>, and an auxiliary device (not illustrated). The auxiliary device operates the module <NUM>. The module <NUM> and the auxiliary device are housed in the external case <NUM>. In <FIG>, a partial configuration is omitted.

The external case <NUM> of the module housing device <NUM> illustrated in <FIG> includes columns <NUM> and external plates <NUM>. A dividing plate <NUM> vertically partitions the interior of the external case <NUM>. The space above the dividing plate <NUM> in the external case <NUM> is a module housing room <NUM> that houses the module <NUM>, and the space below the dividing plate <NUM> in the external case <NUM> is an auxiliary device housing room <NUM> that houses the auxiliary device that operates the module <NUM>. In <FIG>, the auxiliary device housed in the auxiliary device housing room <NUM> is omitted.

Additionally, the dividing plate <NUM> includes an air vent <NUM> for allowing the air to flow in the auxiliary device housing room <NUM> toward the module housing room <NUM>. The external plate <NUM> constituting the module housing room <NUM> includes an exhaust opening <NUM> for exhausting air in the module housing room <NUM>.

In such a module housing device <NUM>, as mentioned above, since the module housing room <NUM> includes a module <NUM> for reducing the deterioration of the battery performance, the module housing device <NUM> that reduces the decrease in the battery performance can be provided.

Also, in the embodiment mentioned above, the case where the support substrate having the hollow flat plate type is used has been exemplified; however, the embodiment can also be applied to a cell stack device using a cylindrical support substrate.

Subsequently, a cell and a cell stack device according to the second embodiment will be described with reference to <FIG> and <FIG>.

In the embodiment mentioned above, a so-called "vertical stripe type", in which only one element unit including a fuel electrode, a solid electrolyte layer, and an air electrode is provided on the surface of the support substrate, has been exemplified; however, the embodiment can be applied to a horizontal stripe type cell stack device with an arrangement of a so-called "horizontal stripe type" cell in which element units are provided at a plurality of places separated from each other on the surface of the support substrate and adjacent element units are electrically connected to each other.

<FIG> is a cross-sectional view illustrating the cell according to the second embodiment. In a cell stack device 10A, a plurality of cells A extend in the length direction L from a pipe <NUM> through which a fuel gas flows. The cell 1A includes a plurality of element units 3A on the support substrate <NUM>. the gas-flow passage 2a through which a gas from the pipe <NUM> flows is provided inside the support substrate <NUM>. The element units 3A on the support substrate <NUM> are electrically connected by a connection layer (not illustrated). The plurality of cells 1A are electrically connected to each other via the conductive member <NUM>. The conductive member <NUM> is located between the element units 3A of each cell 1A and electrically connects adjacent cells 1A to each other. Specifically, a current collector or an interconnector electrically connected to an air electrode of the element unit 3A of one of the adjacent cells 1A is electrically connected to a current collector or an interconnector electrically connected to a fuel electrode of the element unit 3A of the other one of the adjacent cells 1A.

<FIG> is an enlarged cross-sectional view of the conductive member according to the second embodiment. As illustrated in <FIG>, the conductive member <NUM> is joined, via the jointing material <NUM>, to each of the cells 1A adjacent to each other. Also, the conductive member <NUM> has the first surface <NUM> and the second surface <NUM> that face each other with the base material <NUM> interposed therebetween. Also, the conductive member <NUM> has the third surfaces <NUM> and <NUM> that connect the first surface <NUM> and the second surface <NUM>.

The conductive member <NUM> is joined to the cell 1A via the jointing material <NUM>. The jointing material <NUM> is positioned between the first surface <NUM> of the conductive member <NUM> and the element unit 3A of one cell 1A and between the second surface <NUM> of the conductive member <NUM> and the element unit 3A of the other cell 1A, and joins a pair of the cells 1A facing each other with the conductive member <NUM> interposed therebetween and the conductive member <NUM>. Also, the third surfaces <NUM> and <NUM> are exposed to, for example, an oxidizing atmosphere such as air.

The conductive member <NUM> includes the base material <NUM>, the covering part <NUM>, and the coating layer <NUM>. Also, the base material <NUM> includes the first base material layer <NUM> and the second base material layer <NUM>. Each part constituting the conductive member <NUM> can be made of, for example, a material as used for the conductive member <NUM> mentioned above according to the first embodiment mentioned above.

The covering part <NUM> is located on the base material <NUM>. The covering part <NUM> is located between the base material <NUM> and the coating layer <NUM>. The covering part <NUM> contains the first element 43a. The first element 43a has a smaller value of first ionization energy and a smaller absolute value of free energy formation of oxide than chromium. The covering part <NUM> may contain, for example, a plurality of the first elements 43a. The covering part <NUM> may contain a first oxide that is an oxide of the first element 43a. The covering part <NUM> may be a plurality of particles located on the base material <NUM> and/or a coating film covering the base material <NUM>. The covering part <NUM> may contain, for example, CeO<NUM>.

In this way, since the conductive member <NUM> is located on the base material <NUM> and includes the covering part <NUM> containing the first element 43a, the growth of the second base material layer <NUM> is suppressed, so that the conductive member <NUM> can suppress an increase in internal resistance due to the growth of the second base material layer <NUM>. This can reduce the deterioration of the battery performance of the cell 1A, which can reduce a decrease in the battery performance of the cell stack device 10A.

<FIG> is a perspective view illustrating a flat plate cell according to a third embodiment. <FIG> is a partial cross-sectional view of the flat plate cell illustrated in <FIG>.

As illustrated in <FIG>, a cell 1B includes an element unit 3B in which the fuel electrode <NUM>, the solid electrolyte layer <NUM>, and the air electrode <NUM> are laminated. In a cell stack device in which a plurality of flat plate cells are laminated, for example, a plurality of cells 1B are electrically connected by conductive members <NUM> and <NUM> which are metal layers each adjacent to the cells 1B. The conductive members <NUM> and <NUM> electrically connect adjacent cells 1B to each other, and each include a gas-flow passage for supplying gas to the fuel electrode <NUM> or the air electrode <NUM>.

As illustrated in <FIG>, in the present embodiment, the conductive member <NUM> includes a gas-flow passage <NUM> for supplying a gas to the air electrode <NUM>. The conductive member <NUM> is joined to the element unit 3B (air electrode <NUM>) via the jointing material <NUM>. The conductive member <NUM> may be in direct contact with the element unit 3B without the intervention of the jointing material <NUM>. In other words, in the present embodiment, the conductive member <NUM> may be directly connected to the element unit 3B without using the jointing material <NUM>.

The conductive member <NUM> includes the base material <NUM>, the covering part <NUM> containing the first element 43a, and the coating layer <NUM>. Also, the base material <NUM> includes the first base material layer <NUM> and the second base material layer <NUM>. Each part constituting the conductive member <NUM> can be made of, for example, a material as used for the conductive member <NUM> mentioned above.

The covering part <NUM> is located on the base material <NUM>. The covering part <NUM> is located between the base material <NUM> and the coating layer <NUM>. Also, the first element 43a has a smaller value of the first ionization energy and a smaller absolute value of the free energy formation of oxide than chromium. The covering part <NUM> may contain, for example, the plurality of the first elements 43a. The covering part <NUM> may contain a first oxide that is an oxide of the first element 43a. The covering part <NUM> may be a plurality of particles located on the base material <NUM> and/or a coating film covering the base material <NUM>. The covering part <NUM> may contain, for example, CeO<NUM>.

In this way, since the conductive member <NUM> is located on the base material <NUM> and includes the covering part <NUM> containing the first element 43a, the growth of the second base material layer <NUM> is suppressed, so that the conductive member <NUM> can suppress an increase in internal resistance due to the growth of the second base material layer <NUM>. This can reduce the deterioration of the battery performance of the cell 1B, which can reduce a decrease in the battery performance of the cell stack device.

Subsequently, a cell stack device according to other modifications of the embodiment 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 the "cell", the "cell stack device", the "module", and the "module housing device"; they may also be an electrolytic cell, an electrolytic cell stack device, an electrolytic module, and an electrolytic device, respectively, as another example.

As mentioned above, the conductive member <NUM> according to the embodiment includes the base material <NUM> and the covering part <NUM> located on the base material <NUM> and containing the first element 43a. The base material <NUM> contains chromium. The first element 43a has a smaller value of first ionization energy and a smaller absolute value of free energy formation of oxide than chromium. This can reduce an increase in internal resistance of the conductive member <NUM>.

Also, the cell <NUM> according to the embodiment includes the element unit <NUM> and the conductive member <NUM> mentioned above. The conductive member <NUM> is connected to the element unit <NUM>. Thus, the cell <NUM> that reduces a decrease in battery performance due to an increase in internal resistance can be provided.

Also, the cell stack device <NUM> according to the embodiment includes the cell stack <NUM> including the plurality of cells <NUM> mentioned above. Thus, the cell stack device <NUM> that reduces a decrease in battery performance due to an increase in internal resistance can be provided.

The module <NUM> according to the embodiment includes the cell stack device <NUM> described above, and a housing container <NUM> for housing the cell stack device <NUM>. Thus, the module <NUM> that reduces a decrease in battery performance due to an increase in internal resistance can be provided.

The module housing device <NUM> according to the embodiment includes the module <NUM> mentioned above, the auxiliary device for operating the module <NUM>, and the external case for housing the module <NUM> and the auxiliary device. Thus, the module housing device <NUM> that reduces a decrease in battery performance due to an increase in internal resistance can be provided.

Claim 1:
A fuel cell or electrolytic cell (<NUM>) comprising:
an element unit (<NUM>); and
a conductive member (<NUM>), the conductive member (<NUM>) being connected to the element unit (<NUM>) and comprising:
a base material (<NUM>) containing chromium; and
a covering part (<NUM>) located on the base material (<NUM>), containing a first element (43a) selected from Ce, Eu, Pr, and Zr, and having a thickness of <NUM> or less,
the conductive member (<NUM>) comprising a first surface connected to the element unit (<NUM>), a second surface located away from the element unit (<NUM>), and a third surface that connects the first surface and the second surface,
(i) wherein a first area ratio of the covering part (<NUM>) located between the first surface and the base material (<NUM>) is greater than a second area ratio of the covering part (<NUM>) located between the third surface and the base material (<NUM>) or
(ii) wherein a first average thickness of the covering part (<NUM>) located between the first surface and the base material (<NUM>) is greater than a second average thickness of the covering part (<NUM>) located between the third surface and the base material (<NUM>).