JP5237614B2 - Solid oxide fuel cell - Google Patents

Description

  The present invention relates to a solid oxide fuel cell (SOFC), and in particular, a (flat) stack structure in which thin plates and support members that support the thin plates are alternately stacked one by one. It is related with what has. The thin plate is also referred to as “single cell”, and the support member is also referred to as “interconnector”.

Conventionally, a solid oxide fuel cell having the above-described stack structure is known (see, for example, Patent Document 1). In this case, as a thin plate body, a solid electrolyte layer composed of zirconia, a fuel electrode layer formed on the upper surface of the solid electrolyte layer, and an air electrode layer formed on the lower surface of the solid electrolyte layer are laminated. The fired body can be used. Hereinafter, for each thin plate member, the support members adjacent to the upper and lower portions of the thin plate member are also referred to as “upper support member” and “lower support member”, respectively.
JP 2004-342584 A

  Further, the support member can be configured to have a flat surface portion and a frame body portion having a thickness larger than that of the flat surface portion provided on the entire outer periphery of the flat surface portion. In this case, for each thin plate body, the entire circumference of the outer peripheral portion of the thin plate body is sandwiched between the frame body portion of the upper support member and the frame body portion of the lower support member, so that the lower surface of the flat portion of the upper support member A fuel flow path to which fuel gas is supplied can be defined and formed by the inner wall surface of the frame portion of the upper support member and the upper surface of the fuel electrode layer of the thin plate member, and the upper surface of the lower support member and the lower support member An air flow path to which a gas (air) containing oxygen is supplied can be defined and formed by the inner wall surface of the frame body portion and the lower surface of the air electrode layer of the thin plate member.

  With such a configuration, fuel is supplied to the fuel channel and the air channel while the thin plate member is heated to the operating temperature of the solid oxide fuel cell (for example, 800 ° C., hereinafter simply referred to as “operating temperature”). By supplying gas and air, respectively, the fuel gas and air come into contact with the upper and lower surfaces of each thin plate member, and as a result, a power generation reaction occurs in each thin plate member.

  By the way, if there is a difference in pressure between the fuel gas and the air supplied to the fuel flow path and the air flow path (hereinafter simply referred to as “pressure difference”), the pressure difference is reduced in the plane direction of the thin plate (hereinafter referred to as “pressure difference”). It is also simply referred to as “planar direction”) and acts on the thin plate as an external force in the vertical direction. As a result, as the pressure difference increases, the thin plate (particularly, near the center) can be deformed more greatly.

  Here, in the stack structure, the pressure difference between the thin plate bodies may vary due to the variation in the flow rate of the gas supplied to the flow path between the thin plate bodies. Therefore, the amount of deformation of the thin plate (especially in the vicinity of the central portion) may vary between the thin plates.

  In addition, in recent years, attempts have been made to form a thin plate member and a support member (particularly, a thin plate member) extremely thin in order to achieve the objectives such as downsizing the SOFC and reducing the internal electric resistance. When the thin plate member is formed extremely thin in this manner, the support portion (layer that supports the thin plate member) in the thin plate member becomes thin, and thus the deformation amount of the thin plate member with respect to the pressure difference increases. That is, the variation of the deformation amount of the thin plate member with respect to the variation of the pressure difference becomes large.

  When the thin plate body (particularly, in the vicinity of the central portion thereof) is deformed, the pressure loss when the fluid flows through the flow path changes and the gas flow rate changes, so that the power generation characteristics of the thin plate body can change. Therefore, in order to stably obtain the desired power generation characteristics for the SOFC as a whole, it is preferable to suppress variations in the deformation amount of the thin plate members between the thin plate members due to variations in pressure difference. For this purpose, at the operating temperature, it is required to make it difficult to deform the thin plate against an external force based on the pressure difference.

  As described above, an object of the present invention is a (flat plate) stack in which a thin plate body in which a solid electrolyte layer, a fuel electrode layer, and an air electrode layer are stacked and fired and a support member are alternately stacked. It is an object of the present invention to provide a small solid oxide fuel cell having a structure in which a thin plate body is hardly deformed by an external force based on a pressure difference between a fuel gas and a gas containing oxygen at an operating temperature.

  In order to achieve the above object, a solid oxide fuel cell (SOFC) according to the present invention includes a solid electrolyte layer, a fuel electrode layer formed on the upper surface thereof, and an air electrode layer formed on the lower surface thereof, which are laminated and fired. The one or more thin plate members described above and the plurality of support members having the above-described flat portion and frame portion are alternately laminated one by one. Here, from the viewpoint of downsizing the entire SOFC, the thickness of each thin plate member is preferably 20 μm or more and 500 μm or less and is uniform over the entire thin plate member.

  Further, as described above, for each of the thin plate bodies, the entire circumference of the outer peripheral portion of the thin plate body is sandwiched between the frame body portion of the upper support member and the frame body portion of the lower support member (preferably, airtight Thus, a fuel flow path is defined and formed by the lower surface of the flat portion of the upper support member, the inner wall surface of the frame portion of the upper support member, and the upper surface of the fuel electrode layer of the thin plate member. And an air flow in which oxygen-containing gas (air or the like) is supplied from the upper surface of the flat portion of the lower support member, the inner wall surface of the frame portion of the lower support member, and the lower surface of the air electrode layer of the thin plate member. Roads are defined and formed.

  The feature of the SOFC according to the present invention is that each of the thin plate bodies is warped downward both at normal temperature and at the operating temperature of the solid oxide fuel cell higher than normal temperature, and in the plane direction of the thin plate body. The warp height of each thin plate member in the vertical direction is that the operating temperature is smaller than the normal temperature (in a state where no gas is supplied).

  As one specific configuration for realizing this configuration, for example, for each of the thin plate bodies, the thermal expansion coefficient of the fuel electrode layer is larger than the thermal expansion coefficient of the solid electrolyte layer, and the air electrode layer Examples include a configuration in which the thermal expansion coefficient is substantially equal to the thermal expansion coefficient of the solid electrolyte layer, and the thermal expansion coefficient of the support member is larger than the average thermal expansion coefficient of the thin plate member. Here, “the thermal expansion coefficient of the air electrode layer is substantially equal to the thermal expansion coefficient of the solid electrolyte layer” means, for example, that the thermal expansion coefficient of the air electrode layer is greater than or equal to the thermal expansion coefficient of the solid electrolyte layer and the fuel electrode layer. This means that it is less than the thermal expansion coefficient and is closer to the thermal expansion coefficient of the solid electrolyte layer than the thermal expansion coefficient of the fuel electrode layer.

  If the relationship between the thermal expansion coefficients of the layers in the thin plate is set as described above, the internal stress (thermal stress) generated based on the difference in the amount of shrinkage between the layers after firing can be used to lower the temperature at room temperature ( That is, a thin plate body warped toward the air electrode layer side) can be easily manufactured.

  In addition, if the magnitude relationship of the coefficient of thermal expansion between the support member and the thin plate member is set as described above, when the temperature of the SOFC is gradually raised from the normal temperature to the operating temperature by heating, the thin plate member is The tensile force in the direction along the planar direction received from the upper and lower support members gradually increases. As a result, the downward warping height of the thin plate member is gradually reduced. When the temperature of the SOFC is gradually increased from the normal temperature to the operating temperature, the lower part of the thin plate body is also affected by the difference in the amount of expansion between the layers due to the above-described relationship of the thermal expansion coefficient between the layers in the thin plate body. The warp height can be gradually reduced.

  Note that the entire circumference of the outer peripheral portion of the thin plate member may be bonded to the frame body portion of the upper and lower support members using a predetermined bonding agent or the like so as not to be relatively movable. Bonding may be performed using a predetermined bonding agent or the like so as to be relatively movable to some extent only at a temperature or higher.

  From the above, according to the above specific configuration, each thin plate body is warped downward (that is, on the air electrode layer side) at normal temperature or operating temperature (in a state where no gas is supplied). In addition, it is possible to easily realize the SOFC in which the warp height of each thin plate member is smaller at the operating temperature than at the normal temperature.

  According to the SOFC having such a configuration, at the operating temperature (and in a state where no gas is supplied), each thin plate body is warped downward (that is, on the air electrode layer side). Therefore, compared with an SOFC having a configuration in which each thin plate member is not warped at the operating temperature, the thin plate member is less likely to be deformed by an external force in a direction perpendicular to the plane direction based on the pressure difference at the operating temperature. . As a result, variations in the deformation amount of the thin plate members between the thin plate members due to variations in the pressure difference can be suppressed, and desired power generation characteristics can be stably obtained as a whole SOFC.

  In general, when the thin plate body (particularly, in the vicinity of the central portion) is warped, it is in a direction perpendicular to the planar direction rather than an external force in a direction perpendicular to the planar direction from the concave side to the convex side. Therefore, the thin plate member tends to be more difficult to deform with respect to the external force in the direction from the convex side to the concave side. That is, when the thin plate body is warped downward (that is, the air electrode layer side), when an external force that is directed upward (that is, an external force that is directed from the air electrode layer side to the fuel electrode layer side) is applied. The “deformation suppressing effect due to warping” is further exhibited.

  On the other hand, the molecular number ratio of oxygen and fuel (hydrogen) consumed in the power generation reaction of the solid oxide fuel cell (see chemical reaction formulas (1) and (2) described later), and oxygen in the air In general, the flow rate of air supplied to the air flow path is set to a value larger than the flow rate of fuel gas supplied to the fuel flow path. In this case, the pressure of the air supplied to the air flow path becomes larger than the pressure of the fuel gas supplied to the fuel flow path. As a result, each thin plate member has an external force directed upward due to the pressure difference. (In other words, an external force directed from the air electrode layer side to the fuel electrode layer side) acts. Therefore, when the flow rate of the air supplied to the air flow path is set to a value larger than the flow rate of the fuel gas supplied to the fuel flow path, the thin plate member is located below (that is, the air electrode layer) as in the above configuration. If it is warped toward the “side”, the “deformation suppressing effect by warping” can be further exhibited.

  In addition, when the thin plate body (particularly, in the vicinity of the central portion) is warped downward (that is, on the air electrode layer side), in the plan view (top view), in the vicinity of the central portion of the air flow path. The height of the air flow path becomes smaller than other parts. As a result, the air flow rate in the vicinity of the central portion of the air flow path can be lowered and the air flow rate in other portions can be increased in plan view. As a result, the air inflow hole and the air outflow hole are arranged so that the line connecting the air inflow hole and the air outflow hole of the air flow path passes through the central portion of the air flow path, particularly in plan view. In some cases, it has been found that the degree of non-uniformity of the air flow rate in the air flow path can be suppressed. Thereby, the utilization efficiency of the air with respect to a power generation reaction can be improved, and even if the utilization factor of air is high, the fall of the output of SOFC can be suppressed.

  In the SOFC according to the present invention, for each of the thin plate bodies, the height of the air flow path (T1) in the direction perpendicular to the plane direction of the thin plate body when the warp height of the thin plate body is assumed to be zero. The ratio of the warp height (X1) of the thin plate at normal temperature (X1 / T1, see FIG. 6, hereinafter referred to as “room temperature warp height ratio”) is 0.05 or more and 0.00. It is suitable that it is 8 or less.

  Here, the “height of the air flow path” specifically refers to, for example, a distance in a direction perpendicular to the plane direction between the upper surface of the flat surface portion and the upper surface of the frame body portion in the lower support member. is there. In addition, “the warp height of the thin plate member” specifically refers to, for example, the distance in the direction perpendicular to the planar direction between the outer peripheral portion of the thin plate member and the bottom located at the lowest point in the vicinity of the central portion of the thin plate member. Etc.

  Hereinafter, for convenience of explanation, the downward warping height (X1, see FIG. 6) of the thin plate at normal temperature is referred to as “normal temperature warping height”, and the downward warping height of the thin plate at the operating temperature. (X2, see FIG. 7) shall be referred to as “operating temperature warp height”.

  According to the study, if the room temperature warp height ratio is less than 0.05, the operating temperature warp height becomes very small, and the deformation suppressing effect of the thin plate against the external force based on the pressure difference cannot be sufficiently exhibited. Was found to occur. On the other hand, if the room temperature warp height ratio exceeds 0.8, the operating temperature warp height is still sufficiently large, and there is a problem that the pressure loss when air flows through the air flow path becomes very large. There was found. From the above, it is preferable that the normal temperature warp height ratio is 0.05 or more and 0.8 or less.

  When the normal temperature warp height ratio is within such a range, the height (T1) of the air channel is preferably 50 μm or more and 700 μm or less from the viewpoint of downsizing the entire SOFC.

  In addition, when the height (T) of the air flow path is within such a range, and the shape of the planar portion of the support member is a square, a rectangle, a circle, or an ellipse in plan view, The length of one square piece, the length of the short side of the rectangle, the diameter of the circle, or the short diameter of the ellipse is preferably 4 mm or more and 190 mm or less.

  According to this, at the operating temperature, the degree of curvature (curvature) of the thin plate member can be set to such an extent that the deformation suppressing effect can be sufficiently exhibited without generating excessive internal stress. The reason why the length of a square piece, the length of a short side of a rectangle, the diameter of a circle, or the short diameter of an ellipse is defined is as follows.

  The shape representing the mode of main warpage occurring in the thin plate body is various longitudinal sections of the same plane portion including the vicinity of the central portion of the plane portion of the support member (the same plane portion is cut along a plane perpendicular to the plane direction). The thin plate body is cut along a plane including a vertical section (hereinafter referred to as “minimum width vertical section”) having the shortest width (distance in the plane direction of the vertical section) among the obtained cross sections). There is a tendency to appear in the longitudinal section of the obtained thin plate. Therefore, the main degree of curvature (curvature) of the thin plate body greatly depends on the width of the minimum width longitudinal section. On the other hand, when the shape of the planar portion of the support member is square, rectangular, circular, or elliptical in plan view, the width of the minimum width longitudinal section is the length of one piece of the square and the short side of the rectangle, respectively. Matches the length, circular diameter, or elliptical minor axis. From the above, when the shape of the planar portion of the support member is a square, rectangle, circle, or ellipse in plan view, the degree of curvature (curvature) of the thin plate member is the length of one square piece, a rectangle, respectively. Depends largely on the length of the short side, the diameter of the circle, or the minor axis of the ellipse.

  Hereinafter, a solid oxide fuel cell according to an embodiment of the present invention will be described with reference to the drawings.

(Overall structure of fuel cell)
FIG. 1 is a cutaway perspective view of a solid oxide fuel cell (hereinafter simply referred to as “fuel cell”) 10 which is a device according to an embodiment of the present invention. FIG. 2 is a partially exploded perspective view of the fuel cell 10. The fuel cell 10 is formed by alternately laminating thin plate members 11 and support members 12. That is, the fuel cell 10 has a flat stack structure. The thin plate member 11 is also referred to as a “single cell” of the fuel cell 10. The support member 12 is also referred to as an “interconnector”.

  As shown in an enlarged circle A in FIG. 2, the thin plate member 11 includes an electrolyte layer (solid electrolyte layer) 11a, a fuel electrode layer 11b formed on the upper surface (upper surface), and an electrolyte layer. And an air electrode layer 11c formed on a surface (lower surface) opposite to the fuel electrode layer 11b on 11a. The planar shape of the thin plate member 11 is a square (length of one side = A) having sides along the x-axis and y-axis directions orthogonal to each other. The thin plate member 11 is a plate member having a thickness direction in the z-axis direction orthogonal to the x-axis and the y-axis.

  In this example, the electrolyte layer 11a is a dense fired body of YSZ (yttria stabilized zirconia). The fuel electrode layer 11b is a fired body made of Ni—YSZ and is a porous electrode layer. The air electrode layer 11c is a fired body made of LSM (La (Sr) MnO3: lanthanum strontium manganite) -YSZ, and is a porous electrode layer. The average thermal expansion coefficients of the electrolyte layer 11a, the fuel electrode layer 11b, and the air electrode layer 11c from room temperature to 1000 ° C. are approximately 10.8 ppm / K, 12.5 ppm / K, and 11 (10.8) ppm, respectively. / K.

  That is, the thermal expansion coefficient of the fuel electrode layer 11b is larger than the thermal expansion coefficient of the electrolyte layer 11a, and the thermal expansion coefficient of the air electrode layer 11c is substantially equal to the thermal expansion coefficient of the electrolyte layer 11a. Therefore, when the temperature of the fuel cell 10 changes, a difference in expansion and contraction occurs between the layers in the thin plate member 11.

  The thin plate member 11 includes a pair of cell through holes 11d and 11d. Each cell through hole 11d passes through the electrolyte layer 11a, the fuel electrode layer 11b, and the air electrode layer 11c. The pair of cell through holes 11d and 11d are formed in the vicinity of one side of the thin plate member 11 and in the vicinity of both ends of the side.

  FIG. 3 is a cross-sectional view of the support member 12 taken along the plane including the 1-1 line parallel to the x axis and parallel to the xz plane in FIG. 2.

  As shown in FIGS. 2 and 3, the support member 12 includes a flat surface portion 12 a, an upper frame portion 12 b, and a lower frame portion 12 c. The upper frame body portion 12b and the lower frame body portion 12c correspond to the “frame body portion”. The planar shape of the supporting member 12 is a square (side length = A) having sides along the x-axis and y-axis directions orthogonal to each other, and is the same shape as the planar shape of the thin plate member 11.

  The support member 12 is made of a Ni-based heat-resistant alloy (for example, ferrite-based SUS, Inconel 600, Hastelloy, etc.). For example, in the case of SUS430, which is a ferrite SUS, the average thermal expansion coefficient of the support member 12 from room temperature to 1000 ° C. is approximately 12.5 ppm / K. Therefore, the thermal expansion coefficient of the support member 12 is larger than the average thermal expansion coefficient of the thin plate member 11. Accordingly, when the temperature of the fuel cell 10 changes, a difference in expansion and contraction occurs between the thin plate member 11 and the support member 12.

  The flat surface portion 12a is a thin flat plate having a thickness direction in the z-axis direction. The planar shape of the flat surface portion 12a is a square (length of one side = L (<A)) having sides along the x-axis and y-axis directions.

  The upper frame body portion 12b is a frame body erected upward in the periphery of the flat surface portion 12a (a region near four sides, that is, a region near the outer periphery). The upper frame body portion 12b includes an outer peripheral frame portion 12b1 and a step forming portion 12b2.

  The outer peripheral frame portion 12 b 1 is located on the outermost peripheral side of the support member 12. The shape of the longitudinal section of the outer peripheral frame portion 12b1 (for example, a cross section obtained by cutting the outer peripheral frame portion 12b1 having a longitudinal direction in the y-axis direction along a plane parallel to the xz plane) is a rectangle (or a square).

  The step forming portion 12b2 is a portion that extends from the inner peripheral surface of the outer peripheral frame portion 12b1 toward the center of the support member 12 at one of the four corners of the flat surface portion 12a. The lower surface of the step forming portion 12b2 is connected to the flat portion 12a. The shape of the step forming portion 12b2 in plan view is substantially square. The upper surface (plane) of the step forming portion 12b2 is continuous with the upper surface (plane) of the outer peripheral frame portion 12b1. A through hole TH is formed in the step forming portion 12b2. The through hole TH also penetrates the flat surface portion 12a located below the step forming portion 12b2.

  The lower frame body portion 12c is a frame body erected downward around the flat surface portion 12a (a region near the four sides, that is, a region near the outer periphery). The lower frame part 12c has a symmetrical shape with the upper frame part 12b with respect to the center line CL in the thickness direction of the plane part 12a. Accordingly, the lower frame body portion 12c includes an outer peripheral frame portion 12c1 and a step forming portion 12c2 that have the same shape as the outer peripheral frame portion 12b1 and the step forming portion 12b2, respectively. However, the step forming portion 12c2 is arranged and formed at one corner portion of two corner portions adjacent to the corner portion where the step forming portion 12b2 is formed among the four corner portions of the flat surface portion 12a. .

  4 shows the thin plate body 11 and the pair of support members 12 in a state of supporting (holding) the thin plate body 11 in a plane that includes a 2-2 line parallel to the y axis in FIG. 2 and is parallel to the yz plane. It is the longitudinal cross-sectional view cut | disconnected along. As described above, the fuel cell 10 is formed by alternately laminating the thin plate members 11 and the support members 12.

  Here, of the pair of support members 12, those adjacent to the thin plate member 11 below and above are respectively referred to as a lower support member 121 and an upper support member 122 for convenience. As shown in FIG. 4, the lower support member 121 and the upper support member 122 are coaxial with each other so that the lower frame body portion 12 c of the upper support member 122 faces the upper frame body portion 12 b of the lower support member 121. Placed in.

  The entire periphery of the thin plate member 11 is sandwiched between the upper frame portion 12 b of the lower support member 121 and the lower frame portion 12 c of the upper support member 122. At this time, the thin plate member 11 is disposed so that the air electrode layer 11 c faces the upper surface of the flat portion 12 a of the lower support member 121, and the fuel electrode layer 11 b faces the lower surface of the flat portion 12 a of the upper support member 122. Placed in.

  The lower surface of the outer peripheral portion of the thin plate member 11 (that is, the lower surface of the outer peripheral portion of the air electrode layer 11c) is the upper surface of the upper frame portion 12b of the lower support member 121 (specifically, the upper surfaces of the outer peripheral frame portion 12b1 and the step forming portion 12b2). ) And is bonded and fixed to the upper frame 12b by a predetermined conductive bonding agent or the like. Similarly, the upper surface of the outer peripheral portion of the thin plate member 11 (that is, the upper surface of the outer peripheral portion of the fuel electrode layer 11b) is the lower surface of the lower frame body portion 12c of the upper support member 122 (specifically, the outer peripheral frame portion 12c1 and the step forming portion). 12c2 and the lower frame portion 12c is bonded and fixed to the lower frame portion 12c by a predetermined conductive bonding agent or the like.

  In other words, the thin plate member 11 is joined and fixed to the lower frame portion 12c of the upper support member 122 and the upper frame portion 12b of the lower support member 121 on the upper and lower surfaces of the entire outer periphery. Note that the joining / fixing may be such that the thin plate member 11 is completely immovable relative to the support member 11 or may be relatively movable only at a predetermined temperature or higher.

  As described above, as shown in FIG. 4, the upper surface of the flat portion 12a of the lower support member 121, the inner wall surface of the upper frame body portion 12b (the outer peripheral frame portion 12b1 and the step forming portion 12b2) of the lower support member 121, and the thin plate An air flow path 21 to which a gas containing oxygen is supplied is formed by the lower surface of the air electrode layer 11 c of the body 11. The gas containing oxygen flows into the air flow path 21 through the through hole TH of the upper support member 122 and the cell through hole 11d of the thin plate member 11 as indicated by the dashed arrows in FIG.

  Further, the lower surface of the flat portion 12 a of the upper support member 122, the inner wall surface of the lower frame portion 12 c (the outer peripheral frame portion 12 c 1 and the step forming portion 12 c 2) of the upper support member 122, and the upper surface of the fuel electrode layer 11 b of the thin plate member 11. Thus, a fuel flow path 22 to which a fuel containing hydrogen is supplied is formed. The fuel flows into the fuel flow path 22 through the through hole TH of the lower support member 121 and the cell through hole 11d of the thin plate member 11 as indicated by the solid arrow in FIG.

The fuel cell 10 configured as described above includes, for example, a fuel flow path formed between the fuel electrode layer 11b of the thin plate member 11 and the lower surface of the flat surface portion 12a of the support member 12, as shown in FIG. The fuel is supplied to 22 and air is supplied to the air flow path 21 formed between the air electrode layer 11c of the thin plate member 11 and the upper surface of the flat surface portion 12a of the support member 12, and the following is shown. Power generation based on chemical reaction formulas (1) and (2) is performed.
(1/2) · O ₂ +2 ^e− → O ²⁻ (at: air electrode layer 11c) (1)
H ₂ + O ²⁻ → H ₂ O + 2 ^e− (in the fuel electrode layer 11b) (2)

(War of thin plate 11)
Next, the warp of the thin plate member 11 will be described. 6 shows the thin plate member 11 and the pair of support members 12 in a state of supporting (holding) the thin plate member 11 at room temperature, including a 3-3 line parallel to the x axis in FIG. 2 and parallel to the xz plane. It is a schematic diagram of the longitudinal cross-section cut | disconnected along the flat plane. A line 3-3 is a line passing through the center of the planar shape (= square) of the support member 12 (= center of the planar shape (= square) of the thin plate member 11).

  In this example, the length A of one side of the planar shape (= square) of the thin plate member 11 is not less than 5 mm and not more than 200 mm. The thickness t of the thin plate member 11 is uniform throughout, and is 20 μm or more and 500 μm or less in this example. The thicknesses of the electrolyte layer 11a, the fuel electrode layer 11b, and the air electrode layer 11c are, for example, 1 μm to 50 μm, 5 μm to 500 μm, and 5 μm to 200 μm, respectively.

  The height T1 of the air flow path 21 in the direction perpendicular to the planar direction of the thin plate member 11 (hereinafter also simply referred to as “planar direction”) is the upper surface of the planar portion 12a of the lower support member 121 and the upper frame body. It is equal to the distance in the direction perpendicular to the planar direction between the upper surface of the portion 12b and in this example, it is 50 μm or more and 700 μm or less. In this example, the height T2 of the fuel flow path 22 (that is, the distance in the direction perpendicular to the plane direction between the lower surface of the flat portion 12a and the lower surface of the lower frame portion 12c in the upper support member 122) is It is smaller than the height T1 of the air flow path 21. Further, the length L of one side of the planar shape (= square) of the planar portion 12a of the support member 12 is 4 mm or more and 190 mm or less in this example.

  As can be understood from FIG. 6, the thin plate member 11 is positioned downward (that is, the center of the planar shape (square) is the lowest point (bottom) at room temperature (and no gas is supplied) (that is, the bottom). The air electrode layer 11c side). Hereinafter, the downward warping height of the thin plate member 11 at room temperature (specifically, the distance in the direction perpendicular to the planar direction between the outer peripheral portion of the thin plate member 11 and the bottom portion) is referred to as “normal temperature warp height X1”. (Refer to FIG. 6, X1> 0).

  The fuel cell 10 configured as described above generates power using a chemical reaction according to the above formulas (1) and (2). However, since the fuel cell (SOFC) 10 generates power using the oxygen conductivity of the solid electrolyte layer 11a, the operating temperature of the fuel cell 10 is generally at least 600 ° C. or higher. For this reason, the fuel cell 10 has an external heating mechanism (for example, a resistance heater type heating mechanism or a heating mechanism that uses heat obtained by burning fuel gas) from normal temperature to an operating temperature (for example, 800 ° C.). ).

  Here, as described above, there is a relationship between the thermal expansion coefficients between the layers in the thin plate member 11 (thermal expansion coefficient of the fuel electrode layer 11b> thermal expansion coefficient of the electrolyte layer 11a≈thermal expansion coefficient of the air electrode layer 11c). Exists. For this reason, in the above temperature rising process, the extension amount of the thin plate member 11 in the direction along the plane direction is larger on the upper side surface (fuel electrode layer 11b side surface) of the thin plate member 11 than on the lower side surface (air electrode layer 11c side surface). Become. As a result, an upward force is generated inside the thin plate member 11 due to a change in internal stress (thermal stress) as shown by a black arrow in FIG. Thereby, the downward warping height of the thin plate member 11 is gradually reduced.

  In addition, as described above, a thermal expansion coefficient magnitude relationship (the thermal expansion coefficient of the support member 12> the thermal expansion coefficient of the thin plate member 11) also exists between the support member 12 and the thin plate member 11. For this reason, in the above temperature rising process, the extension amount of the support member 12 in the direction along the plane direction is larger than the extension amount of the thin plate member 11 in the direction along the plane direction. However, the thin plate member 11 is joined and fixed to the support member 12 in the entire outer periphery. As a result, as indicated by white arrows in FIG. 7, the thin plate member 11 receives a tensile force in the direction along the plane direction from the support member 12. Also by this, the downward warp height of the thin plate member 11 is gradually reduced.

  That is, in the above temperature rising process, the thin plate body 11 is caused by the relationship between the thermal expansion coefficients between the layers in the thin plate body 11 and the thermal expansion coefficient between the support member 12 and the thin plate body 11. The downward warp height gradually decreases. However, even if the temperature of the fuel cell 10 reaches the operating temperature, the thin plate member 11 still warps downward (in a state where no gas is supplied). That is, assuming that the height of warping of the thin plate member 11 at the operating temperature (and the state where no gas is supplied) is referred to as “operating temperature warp height X2” (see FIG. 7), 0 <X2 <X1 holds.

  Thus, in this example, as shown in FIG. 7, the thin plate body 11 warps downward (that is, on the air electrode layer 11c side) at the operating temperature. As a result, as shown in FIG. 8, the thin plate member 11 received an external force in a direction perpendicular to the plane direction at the operating temperature, as compared with the fuel cell having a configuration in which the thin plate member 11 is not warped at the operating temperature. In this case, the thin plate member 11 is hardly deformed (deformation suppressing effect by warping).

  Therefore, even if a pressure difference is generated between the air flowing through the air flow path 21 and the fuel gas flowing through the fuel flow path 22, the pressure difference acts as an external force on the thin plate body 11. The body 11 is difficult to deform.

  Here, in view of the molecular number ratio of oxygen and hydrogen consumed in the above chemical reaction formulas (1) and (2) and the molecular number ratio of oxygen in the air, Since the flow rate of the supplied air is set to a value larger than the flow rate of the fuel gas supplied to the fuel flow path 22, the pressure of the air supplied to the air flow path 21 is the fuel supplied to the fuel flow path 22. It becomes larger than the gas pressure. In this case, an external force directed upward due to the pressure difference (that is, an external force directed from the air electrode layer 11c side to the fuel electrode layer 11b side) acts on the thin plate member 11.

  On the other hand, when the thin plate member 11 is warped downward (that is, on the air electrode layer 11c side) as in this example, the thin plate member 11 is directed upward as compared with the case where an external force directed downward is applied to the thin plate member 11. When the applied external force is applied, the “deformation suppressing effect by warping” can be further exhibited. As described above, in this example, when the flow rate of the air supplied to the air flow path 21 is set to a value larger than the flow rate of the fuel gas supplied to the fuel flow path 22, the “deformation suppressing effect due to warpage” is further increased. It can be further demonstrated.

  As a result, even if the pressure difference varies among the plurality of thin plate bodies 11 in the fuel cell 10 having the stack structure, the variation in the deformation amount of the thin plate bodies 11 between the thin plate bodies 11 due to the pressure difference variation. Can be suppressed. Therefore, the desired power generation characteristics can be stably obtained for the fuel cell 10 as a whole.

  Next, a preferable relationship between the room temperature warp height X1 and the height T1 of the air flow path 21 will be described. For this study, a value (X1 / T1) is introduced. Hereinafter, this value is referred to as “room temperature warp height ratio”.

  The room temperature warp height ratio is preferably 0.05 or more and 0.8 or less. This is based on the following reason. That is, when the room temperature warp height ratio is less than 0.05, the operating temperature warp height X2 becomes very small, and the effect of suppressing the deformation of the thin plate member 11 against the external force based on the pressure difference cannot be sufficiently exhibited. found. On the other hand, when the room temperature warp height ratio exceeds 0.8, the operating temperature warp height X2 is still sufficiently large, and the cross-sectional area of the air channel 21 is reduced, so that air flows through the air channel 21. It has been found that the pressure loss of becomes very large.

  Hereinafter, an experiment for confirming this will be described. In this experiment, a square thin plate body (electrolyte-supported type) having a side length A = 30 mm and the thicknesses of the electrolyte layer, the fuel electrode layer, and the air electrode layer being 30 μm, 15 μm, and 15 μm, respectively. A plurality of samples having different ratios of room temperature warp height were used. In addition, the adjustment of the room temperature warp height ratio is the property of the bonding agent used for joining / fixing the outer peripheral part of the thin plate member and each frame part of the upper and lower support members (viscosity characteristics with respect to temperature, thermal expansion coefficient, (Thickness, Young's modulus, etc.)

  When the room temperature warp height ratio is less than 0.05, the deformation suppression effect due to the convex shape of the thin plate member is insufficient, so the gas flow rate is changed rapidly (that is, when the pressure difference changes rapidly). The deformation amount of the thin plate member in) was large, and the thin plate member was damaged. On the other hand, at a room temperature warp height ratio of 0.05 or more, the deformation suppressing effect due to the convex shape of the thin plate member was confirmed without causing damage or the like of the thin plate member.

  On the other hand, when the room temperature warp height ratio exceeded 0.8, the minimum value of the cross-sectional area of the air channel was reduced, and the pressure loss in the air channel was significantly increased. In addition, since the difference between the maximum and minimum values of the cross-sectional area of the air flow path becomes large, the air flow in the air flow path becomes uneven, and the power generation efficiency per unit area in plan view It was also found that was significantly reduced. On the other hand, when the room temperature warp height ratio was 0.8 or less, neither a significant increase in pressure loss nor a significant decrease in power generation efficiency occurred in the air flow path. From the above, the normal temperature warp height ratio is preferably 0.05 or more and 0.8 or less.

  The above experiment is performed under the condition that the thickness of the thin plate member is constant. On the other hand, when the thickness of the thin plate member is in the range of 20 μm to 500 μm, it has also been found that for the same reason, it is preferable that the normal temperature warp height ratio is 0.05 or more and 0.8 or less. . Hereinafter, an experiment for confirming this will be described. This experiment was performed using an electrolyte support cell and a fuel electrode support cell as the thin plate, and the thickness of the thin plate as a parameter.

  This experiment was performed by creating a stack of one layer (one thin plate) while varying the thickness of the thin plate. For bonding (seal) between the thin plate and the support member, softened glass is used for the joint surface between the outer periphery of the thin plate and the frame of the support member, and crystallized glass is used for covering the outer surface of the stack. The heat treatment was performed at 850 ° C.

  The room temperature warp height X1 of the thin plate after completion of the stack is determined based on the glass bonding conditions, and the current collector disposed in the two gas flow paths (fuel flow path and air flow path) formed in the single-layer stack. It was adjusted by changing the shape and hardness of the mesh. Confirmation of the room temperature warp height X1 of the thin plate is done by pouring the cured resin into the two gas flow paths in the completed stack to hold and restrain the shape of the thin plate, and the stack in a plane along the vertical plane. This was done by observing the cross section of the thin plate obtained by cutting.

  In this experiment, the shape stability of the thin plate against the above “pressure difference” was evaluated. This evaluation method is as follows. That is, the flow rate of the gas flowing through the fuel flow path is kept constant. In this state, the flow rate of the gas flowing through the air flow path is changed, and the change in the pressure difference (pressure loss) between the inflow hole and the outflow hole of the fuel flow path is monitored. The small change in the pressure loss means that the change in the deformation amount of the thin plate body with respect to the change in the “pressure difference” is small and the shape stability of the thin plate body with respect to the “pressure difference” is high. It means "effective").

  This evaluation was performed at room temperature, and nitrogen was used as the gas used for the evaluation in both the fuel flow path and the air flow path. In the actual use environment of SOFC, as described above, the operating temperature is high (about 600 to 800 ° C.), hydrogen gas is flowed through the fuel flow path, and air is flowed through the air flow path. However, in this experiment, in consideration of the convenience of the experiment, a method of reproducing the actual use environment of the above SOFC at normal temperature was adopted.

  In other words, in order to reproduce the pressure loss in the flow path at high temperatures at room temperature, multiply the value obtained by multiplying the viscosity coefficient and flow rate of the gas in the actual use environment by the viscosity coefficient and flow rate of the simulated gas (nitrogen) at room temperature. The gas flow rate conditions were determined so that the values were the same.

  Specifically, the pressure loss of the fuel flow path is changed while the flow rate of nitrogen on the air flow path side is changed in the range of 250 to 2000 sccm while the flow rate of nitrogen on the fuel flow path side is constant at 250 sccm at normal temperature. Change (stability) was evaluated. The evaluation results are shown in Table 1.

  As can be understood from Table 1, when the room temperature warp height ratio is less than 0.05, the pressure loss fluctuates greatly and the “deformation suppressing effect due to warp” is insufficient. On the other hand, it was confirmed that when the normal temperature warp height ratio is 0.05 or more, the fluctuation of the pressure loss is small and the pressure loss is stable, and the “deformation suppressing effect due to warp” can be sufficiently exhibited.

  On the other hand, when the room temperature warp height ratio exceeded 0.8, the pressure loss on the air flow path side was significantly increased. On the other hand, it was confirmed that when the room temperature warp height ratio was 0.8 or less, no significant increase in pressure loss on the air flow path side was observed. From the above, when the thickness of the thin plate member is in the range of 20 μm to 500 μm, it can be said that the room temperature warp height ratio is preferably 0.05 or more and 0.8 or less.

  By the way, as shown in FIG. 9, in plan view, the air flow path is square (square), and the inflow holes and outflow holes (corresponding to the above-mentioned through holes TH and the like) are at the corners corresponding to the opposite ends of the diagonal line. Consider a case in which the inflow hole and the outflow hole are arranged so that the line connecting the inflow hole and the outflow hole passes through the central portion of the air flow path. In the example shown in FIG. 9, the thin plate member 11 is not warped, and therefore the height of the air flow path is uniform in the air flow path. In FIG. 9, the thickness of the arrow represents the magnitude of the air flow rate (and hence the air flow rate) (the same applies to FIG. 10).

  In this case, as shown in FIG. 9, in plan view, the air flow velocity is greatest at the central portion of the air flow path, and the air flow velocity decreases as the distance from the central portion increases. That is, nonuniformity in the air flow rate can occur in the air flow path. When the degree of non-uniformity in the flow velocity is large, as shown by the characteristic line L1 in FIG. 11, there is no effect on the SOFC output density in a situation where the air utilization rate Ua is small, but the air utilization rate Ua is large. It turned out that the power density of SOFC tends to decrease in the situation. This is considered to be due to the low efficiency of air utilization for power generation reaction when the degree of non-uniformity of the air flow rate is large.

  On the other hand, as shown in FIG. 10, a case is considered where the thin plate member 11 is warped downward (air electrode layer side) and the height of the air flow path becomes smaller as it approaches the center. In this case, as compared with the case where the thin plate member 11 shown in FIG. 9 is not warped, the air flow velocity at the central portion of the air flow path is lowered and the air flow velocity at the surrounding portions is increased in a plan view. Can occur. As a result, as shown in FIG. 10, the degree of non-uniformity of the air flow rate in the air flow path can be suppressed.

  When the non-uniformity of the flow velocity is small in this way, as shown by the characteristic line L2 in FIG. 11, even if the air utilization rate Ua is large in addition to the small air utilization rate Ua, the SOFC output It was found that the density was difficult to decrease. In other words, when the thin plate member 11 is warped downward (air electrode layer side), the output density of the SOFC when the air utilization rate Ua is large is improved. This effect is referred to as “output improvement effect due to warpage”. This seems to be due to the fact that when the degree of non-uniformity in the air flow rate is reduced, the efficiency of using air for the power generation reaction increases.

  It has also been found that the room temperature warp height ratio is preferably 0.05 or more and 0.8 or less also from the viewpoint of the “output improvement effect due to warp”. Hereinafter, an experiment for confirming this will be described.

  In this experiment, the fuel utilization rate is fixed at 5%, which is sufficiently low, with abundant fuel gas flowing through the fuel flow path. In this state, the output characteristic of SOFC was evaluated by changing the utilization factor Ua of the air flowing through the air flow path. Specifically, the SOFC output voltage is measured by changing the air supply amount in a state where the current is constantly adjusted at 5 A, and the output voltage at the air utilization rate Ua = 50% obtained from the measurement result is calculated. The output characteristics of SOFC were evaluated. This small output voltage (that is, a small SOFC output (= voltage × current)) means that the “output improvement effect due to warping” is small.

  This evaluation was performed in an environment of 800 ° C. using a fuel electrode-supporting cell having a constant thickness as a thin plate body and variously changing the room temperature warp height ratio. The evaluation results are shown in Table 2.

  As can be understood from Table 2, when the room temperature warp height ratio is less than 0.05, no improvement in output is observed, and the “output improvement effect due to warp” is insufficient. On the other hand, when the room temperature warp height ratio is 0.05 or more, the output is sufficiently improved, and the degree of the decrease in the output with respect to the increase in the air utilization rate Ua is small (the output is stable). It was confirmed that the “output improvement effect due to warping” can be sufficiently exhibited.

  On the other hand, when the room temperature warp height ratio exceeded 0.8, the pressure loss on the air flow path side was significantly increased as described above. On the other hand, it was confirmed that when the room temperature warp height ratio was 0.8 or less, no significant increase in pressure loss on the air flow path side was observed. From the above, it is preferable that the room temperature warp height ratio is preferably 0.05 or more and 0.8 or less from the viewpoint of the “output improvement effect by warping” in addition to the “deformation suppressing effect by warping”. it can.

  Next, an example of a method for manufacturing the thin plate member 11 warped downward (at the air electrode layer 11c side) at normal temperature as described above will be briefly described. When an electrolyte-supporting cell is manufactured as the thin plate member 11, a sheet (a layer that becomes the fuel electrode layer 11 b) is formed on the upper surface of a ceramic sheet (YSZ tape) prepared by the green sheet method, and then 1400 ° C. It is formed by firing in 1 hour and, further, by firing a sheet (a layer to be the air electrode layer 11c) on the lower surface of the fired body by the same printing method and firing at 1200 ° C. for 1 hour. When a fuel electrode supporting cell is manufactured as the thin plate member 11, a ceramic sheet (YSZ tape) is laminated and integrated on the lower surface of a sheet (layer that becomes the fuel electrode layer 11 b) prepared by the green sheet method. It is formed by firing at 1400 ° C. for 1 hour, and further forming a sheet (a layer that becomes the air electrode layer 11c) on the lower surface of the fired body by a printing method and then firing at 1200 ° C. for 1 hour. .

  Here, as described above, there is a relationship between the thermal expansion coefficients between the layers in the thin plate member 11 (thermal expansion coefficient of the fuel electrode layer 11b> thermal expansion coefficient of the electrolyte layer 11a≈thermal expansion coefficient of the air electrode layer 11c). Exists. For this reason, in the temperature lowering process at the time of firing, the contraction amount of the thin plate member 11 in the direction along the plane direction is larger on the upper side surface (fuel electrode layer 11b side surface) than the lower side surface (air electrode layer 11c side surface). Become. By utilizing this principle, it is possible to easily manufacture the thin plate 11 that warps downward (that is, on the air electrode layer 11c side) at room temperature after the temperature lowering process during firing.

  As described above, in the solid oxide fuel cell 10 according to the embodiment of the present invention, the thin plate member 11 warps downward (that is, on the air electrode layer 11c side) at the operating temperature (FIG. 7). See). Therefore, as compared with a fuel cell having a configuration in which the thin plate member 11 is not warped at the operating temperature (see FIG. 8), even when the thin plate member 11 receives an external force in a direction perpendicular to the plane direction at the operating temperature. The thin plate 11 is not easily deformed. As a result, even if the pressure difference between the air flowing through the air flow path 21 and the fuel gas flowing through the fuel flow path 22 varies between the plurality of thin plate bodies 11 in the fuel cell 10 having the stack structure, Variations in the deformation amount of the thin plate members 11 between the thin plate members 11 due to the variation in the difference can be suppressed. Therefore, the desired power generation characteristics can be stably obtained for the fuel cell 10 as a whole. In addition, since the thin plate member 11 is warped downward (that is, on the air electrode layer 11c side), the output of the SOFC is increased even when the air utilization rate is high due to the “output improvement effect due to warpage”. There is also an effect that it is difficult to decrease.

  In addition, this invention is not limited to the said embodiment and modification, A various modification can be employ | adopted within the scope of the present invention. For example, the fuel electrode layer 11b can be composed of platinum, platinum-zirconia cermet, platinum-cerium oxide cermet, ruthenium, ruthenium-zirconia cermet, or the like.

  The air electrode layer 11c can be made of, for example, a perovskite complex oxide containing lanthanum (for example, lanthanum cobaltite in addition to the lanthanum manganite described above). Lanthanum cobaltite and lanthanum manganite may be doped with strontium, calcium, chromium, cobalt (in the case of lanthanum manganite), iron, nickel, aluminum or the like. Further, palladium, platinum, ruthenium, platinum-zirconia cermet, palladium-zirconia cermet, ruthenium-zirconia cermet, platinum-cerium oxide cermet, palladium-cerium oxide cermet, ruthenium-cerium oxide cermet may be used.

  The planar shape of the thin plate member 11 and the support member 12 may be a rectangle, a circle, an ellipse, or the like. For example, FIG. 12 is a partially exploded perspective view of the fuel cell 30 when the planar shape of the thin plate member 11 and the support member is a rectangle having a short side length A and a long side length B. . In the fuel cell 30, the planar shape of the planar portion 12 a of the support member 12 is a rectangle having a short side length L and a long side length M.

  In the fuel cell 30, the thin plate member 11 and the pair of support members 12 in a state of supporting (holding) the thin plate member 11 at normal temperature include a 4-4 line parallel to the x axis in FIG. The warp of the thin plate 11 appearing in the longitudinal section cut along the parallel plane is similar to the warp of the thin plate 11 in the fuel cell 10 shown in FIG. The line 4-4 is a line passing through the center of the planar shape (= rectangle) of the support member 12 (= the center of the planar shape (= rectangle) of the thin plate member 11). This corresponds to the above-mentioned “minimum width longitudinal section” in the flat surface portion 12a of the support member 12 described above, and the shape representing the main warpage that occurs in the thin plate member 11 is the longitudinal section including the line 4-4. This is because there is a tendency to appear in the longitudinal section of the thin plate body 11 obtained by cutting the thin plate body 11 along the plane including the “minimum width longitudinal section”.

  In the fuel cell 30, as in the fuel cell 10, the normal temperature warp height ratio is 0.05 or more and 0.8 or less, and the height T of the air channel 21 is 50 μm or more and 700 μm or less. think of. In this case, it is preferable that the length L of the short side of the rectangle corresponding to the width of the “minimum width longitudinal section” is 4 mm or more and 190 mm or less. According to this, the width of the “minimum width longitudinal section” that greatly affects the degree of main warpage (curvature) of the thin plate member 11 can be made the same as that of the fuel cell 10 according to the above-described embodiment. Therefore, at the operating temperature, the degree of curvature (curvature) of the thin plate member 11 can be made the same as that of the fuel cell 10 according to the above embodiment.

  Similarly, in the case where the normal temperature warp height ratio is 0.05 or more and 0.8 or less and the height T of the air channel 21 is 50 μm or more and 700 μm or less, the thin plate member 11 and the support member 12 When the planar shape of the planar portion 12a is circular or elliptical, the diameter of the circle that matches the width of the “minimum width longitudinal section” or the length of the minor axis of the elliptical is 4 mm or more and 190 mm or less. It is preferable. This also allows the width of the “minimum width longitudinal section” to be the same as that of the fuel cell 10, and the degree of curvature (curvature) of the thin plate member 11 at the operating temperature is the same as that of the fuel cell 10. Can be about.

1 is a cutaway perspective view of a solid oxide fuel cell according to an embodiment of the present invention. FIG. 2 is a partially exploded perspective view of the fuel cell shown in FIG. 1. It is sectional drawing of the supporting member which cut | disconnected the supporting member along the plane parallel to an xz plane while including the 1-1 line | wire shown in FIG. It is the longitudinal cross-sectional view which cut | disconnected the support member in the state which supported the thin plate body shown in FIG. 1 and a thin plate body along the 2-2 plane shown in FIG. 2, and parallel to a yz plane. It is a figure explaining the distribution | circulation of the fuel and air in the fuel cell shown in FIG. FIG. 5 is a schematic view corresponding to FIG. 4 showing a state of warping of the thin plate at the normal temperature of the fuel cell shown in FIG. 1. FIG. 5 is a schematic view corresponding to FIG. 4 showing a state of warping of the thin plate at the operating temperature of the fuel cell shown in FIG. 1. FIG. 5 is a schematic diagram corresponding to FIG. 4 illustrating a case where the thin plate member is not warped at the operating temperature as a comparative example. It is the schematic diagram which showed the flow velocity distribution of the air in an air flow path in case the thin plate body is not warped. It is the schematic diagram which showed the flow velocity distribution of the air in an air flow path in case the thin plate body is curving. It is the graph which showed the relationship between an air utilization factor and the output of SOFC. It is a partial exploded perspective view of the solid oxide fuel cell concerning the modification of one embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Thin plate body, 11a ... Zirconia solid electrolyte layer, 11b ... Fuel electrode layer, 11c ... Air electrode layer, 11d ... Cell through-hole, 12 ... Support member, 12a ... Planar part, 12b ... Upper frame Part, 12b1 ... outer peripheral frame part, 12b2 ... step forming part, 12c ... lower frame body part, 12c1 ... outer peripheral frame part, 12c2 ... step forming part, 21 ... air flow path, 22 ... fuel flow path, 121 ... lower support member 122 upper support member

Claims (5)

One or a plurality of thin plate bodies formed by laminating and firing a solid electrolyte layer, a fuel electrode layer formed on the upper surface of the solid electrolyte layer, and an air electrode layer formed on the lower surface of the solid electrolyte layer;
A plurality of support members having a flat surface portion and a frame body portion having a thickness larger than that of the flat surface portion provided on the entire circumference of the outer peripheral portion of the flat surface portion, and supporting the one or more thin plate members,
A solid oxide fuel cell in which the thin plate member and the support member are alternately stacked one by one,
For each of the thin plate bodies, the entire circumference of the outer peripheral portion of the thin plate body is a frame body portion of an upper support member that is the support member adjacent to the upper side of the thin plate body and the support member adjacent to the lower side of the thin plate body. By being sandwiched between the frame portion of the lower support member, the lower surface of the flat portion of the upper support member, the inner wall surface of the frame portion of the upper support member, and the upper surface of the fuel electrode layer of the thin plate member A fuel flow path for supplying fuel gas is defined and formed, and the upper surface of the flat portion of the lower support member, the inner wall surface of the frame portion of the lower support member, and the lower surface of the air electrode layer of the thin plate member An air flow path to which a gas containing oxygen is supplied is defined and formed.
Each of the thin plate bodies is warped downward both at normal temperature and at an operating temperature of the solid oxide fuel cell that is higher than normal temperature, and each of the thin plate bodies in a direction perpendicular to the planar direction of the thin plate body. The warp height of the solid oxide fuel cell is smaller at the operating temperature than at normal temperature ,
For each of the thin plate bodies, the thin plate body at normal temperature with respect to the height (T1) of the air flow path in the direction perpendicular to the plane direction of the thin plate body when the warp height of the thin plate body is assumed to be zero. The ratio (X1 / T1) of the warp height (X1) of the solid oxide fuel cell is 0.05 or more and 0.8 or less . The solid oxide fuel cell according to claim 1 , wherein
The solid oxide fuel cell, wherein the height (T1) of the air flow path is 50 μm or more and 700 μm or less. The solid oxide fuel cell according to claim 2 , wherein
The shape of the planar portion of the support member in plan view is a square, a rectangle, a circle, or an ellipse, and the length of one piece of the square, the length of the short side of the rectangle, the diameter of the circle, or The elliptical minor axis (L) is a solid oxide fuel cell having a length of 4 mm or more and 190 mm or less. The solid oxide fuel cell according to any one of claims 1 to 3 ,
The thickness of each thin plate member is a solid oxide fuel cell having a thickness of 20 μm or more and 500 μm or less. The solid oxide fuel cell according to any one of claims 1 to 4 , wherein
For each thin plate, the thermal expansion coefficient of the fuel electrode layer is larger than the thermal expansion coefficient of the solid electrolyte layer, and the thermal expansion coefficient of the air electrode layer is substantially equal to the thermal expansion coefficient of the solid electrolyte layer,
A solid oxide fuel cell in which a thermal expansion coefficient of the support member is larger than an average thermal expansion coefficient of the thin plate member.

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