JP5727915B2 - Solid oxide fuel cell, solid oxide fuel cell main body, and method for producing solid oxide fuel cell - Google Patents

Description

  The present invention relates to a solid oxide fuel cell including a cell body formed by laminating and firing a fuel electrode layer, an air electrode layer, and a solid electrolyte layer.

  Conventionally, as a flat solid oxide fuel cell (SOFC), a fuel electrode layer in contact with fuel gas is disposed on one side of a solid electrolyte layer, and an air electrode in contact with air on the other side. A SOFC having a structure in which a cell body is formed by arranging layers and the cell body is bonded to a cell bonding member such as an isolation separator is known. When manufacturing an SOFC having such a structure, for example, an isolation separator provided with an opening is prepared, and the periphery of the cell body is integrally joined to the region surrounding the opening via a brazing material or the like. The In general, the cell body and the separator are formed in a square planar shape, but the separator separator is formed extremely thin for weight reduction and the like, and from the viewpoint of preventing breakage in the joint area with the cell body, the planar shape of the cell body The structure which chamfers each corner | angular part is proposed (for example, refer patent document 1). Further, from the viewpoint of preventing cracking of the cell body due to mechanical stress caused by thermal expansion during SOFC power generation operation, a structure in which the cell body is formed in a circular planar shape instead of a square planar shape has been proposed. (For example, refer to Patent Document 2).

JP 2006-4678 A JP 2009-245633 A

  The SOFC cell body can be formed, for example, using ceramic as a main component. In this case, at the time of manufacturing the SOFC, after forming a laminated body in which the sheets of the respective layers of the cell body are laminated, the laminated body is fired to form a cell fired body. In general, a cell body of SOFC is manufactured by firing a laminated body in which a solid electrolyte layer is laminated using a fuel electrode layer as a supporting electrode layer to form a cell fired body, and laminating an air electrode layer on the cell fired body. In the state where the cell body manufactured in this way is joined to the isolation separator, deformation in the stacking direction has occurred due to shrinkage during firing, whereas when an oxidation / reduction cycle or thermal cycle is applied during power generation operation The amount of deformation of the cell body changes. In particular, if it is assumed that the cell body when unfired has a square outer peripheral shape in plan view, the center is located at four sides rather than each corner when the flat cell body is likely to be warped in the approximate center of the flat cell body. The distance from is shortened, and each corner is curved downward. As a result, while the cell body is bonded to the flexible isolation separator, each corner portion comes into contact with a lower member such as an interconnector and approaches a four-point support structure (see FIG. 4). On the other hand, the cell body formed in the above-mentioned circular planar shape is uniform in distance from the center and can avoid the four-point support structure. However, the area of the cell body is limited, so that the power generation area is reduced. Unavoidable. As described above, when a cell main body having a square planar shape is employed to secure a power generation area, it becomes difficult to relieve stress due to the above-described deformation, and the cell main body is cracked by contact with a member such as an interconnector. It becomes a problem that the number of defects increases and the reliability of SOFC decreases.

  The present invention has been made to solve these problems, and while ensuring sufficient power generation performance, it is possible to suppress cracks and the like due to deformation in the stacking direction of the cell main body and ensure high reliability. An object is to provide an oxide fuel cell.

In order to solve the above problems, a solid oxide fuel cell of the present invention includes a fuel electrode layer, an air electrode layer, the fuel electrode layer disposed on one surface side, and the air electrode layer on the other surface side. In the solid oxide fuel cell having a cell body formed by laminating and firing a solid electrolyte layer on which is disposed, the cell body has a rectangular outer peripheral shape including four straight sides in a plan view. with the height in the stacking direction at the center of the square is higher than the height of the stacking direction of the four sides of the square has a convex cross-sectional shape in the stacking direction, the peripheral edge of the cell body, The four corners of the square and the whole or a part of the four sides have a structure that can be supported in a state of being in contact with a predetermined member.

  According to the solid oxide fuel cell of the present invention, the cell body in which the fuel electrode layer, the air electrode layer, and the solid electrolyte layer are stacked is formed into a cell fired body by firing the unfired laminate. At this time, the outer peripheral shape including the four sides maintains a square shape, and the central portion of the square has a convex cross-sectional shape higher than the four side portions. That is, assuming that a thermal cycle or the like is applied to the cell body in advance, depending on the amount of deformation when the cell body is deformed in the stacking direction, the four corners of the cell body and all or part of the four sides are predetermined. The planar shape of the laminate is appropriately set in advance so that it can be supported in contact with the surface of the member. As a result, even if the central part of the rectangular shape of the cell body is deformed in a convex shape in the stacking direction, only the curved four sides of the cell body are prevented from coming into contact with a predetermined member to form a four-point support structure. It is possible to reliably prevent cracking of the cell body due to stress concentration.

  Further, the solid oxide fuel cell of the present invention includes the cell body, and the cross-sectional shape assumes that the cell body has the above-described rectangular planar shape and the above-described convex cross-sectional shape. Among the included curves, a first curve that passes through the central portion and parallel to each side of the square in plan view is a second curve that passes through the vicinity of each side and is parallel to the first curve in plan view. It is characterized by having a long line length compared to the line length of the curve. Thus, in the cross-sectional shape of the unfired cell body, the line length (L2) of the first straight line passing through the center is longer than the line length (L1) of the second straight line passing through the vicinity of each side (L1 < L2) The amount of deformation decreases as it approaches the four sides of the square. In this case, considering that the four sides of the cell body are linear, the action of preventing the four sides of the cell body from floating from a predetermined member (for example, an interconnector) is as described above. It is possible to reliably prevent the cell body from being cracked due to concentration.

  In the present invention, the outer peripheral shape of the cell main body may include various structures within a square range including four sides that are linear in a plan view. For example, the cell body may have an outer peripheral shape that is chamfered at four corners of the square. Thereby, in the state which supported the said cell main body with the predetermined member, the damage in the vicinity of four corners can be prevented, and reliability can be improved further.

In order to solve the above-described problem, the method for manufacturing a solid oxide fuel cell according to the present invention includes stacking a plurality of flat sheets including at least a support base layer and bending or projecting outward in a plan view. A stacking step of forming a laminate having an outer peripheral shape including four sides, and a cell body forming step of firing the laminate to form a cell fired body and forming a cell body including the cell fired body. Yes. Through these series of steps, the cell body has a rectangular outer peripheral shape including four sides that are linear in a plan view, and the height in the stacking direction at the center of the square is the height in the stacking direction at the four sides of the square. higher than in the, has a convex cross section in the stacking direction, the peripheral edge of the cell body, the support and the four corners of the square, the entire or portions of the four sides, in contact with a predetermined member It is characterized by being formed into a possible structure. In addition, by the above series of steps, among the group of curves included in the cross-sectional shape of the cell body having the above-described rectangular planar shape and the above-described convex cross-sectional shape, each side of the square passes through the central portion. The parallel first curve has a line length that is longer than the line length of the second curve that passes through the vicinity of each side and is parallel to the first straight line.

  According to the method for producing a solid oxide fuel cell of the present invention, a cell body is formed after forming an outer circumferentially-shaped laminated body curved or protruded on the outer circumferential side in a plan view, and firing the laminated body to form a fired body. The cell body has the above-described outer peripheral shape and the above-described convex cross-sectional shape. Moreover, even after joining a cell joining member to the peripheral part of a cell main body, it has the convex cross-sectional shape. As a result, a structure in which the whole or part of the four sides of the cell body is supported by the surface of the predetermined member can be obtained, and the above structural effects can be easily realized without going through complicated steps.

  In the above-described manufacturing method of the present invention, the laminated body is chamfered in an arc shape with a first curvature radius at each of the four corners of the square, and a second curvature at which each of the four sides is larger than the first curvature radius. You may form in the circular-arc-shaped curve which has a radius. Thereby, the effect of preventing breakage in the vicinity of the four corners of the cell body can be enhanced.

  Moreover, in the above-described manufacturing method of the present invention, the cell body forming step may include a second stacking step in which a predetermined layer is stacked on the surface of the cell fired body to form the cell body. In this case, in the above manufacturing method of the present invention, the support base layer may be the fuel electrode layer, and the predetermined layer may be the air electrode layer.

  According to the present invention, a cell body obtained by firing a laminate having a predetermined outer peripheral shape with respect to a cell body of a solid oxide fuel cell has a convex shape in which a central portion of a square is higher than a portion of four sides. It is possible to maintain a structure in which the whole or part of the peripheral portion of the cell body supported by a predetermined member can be supported by a member such as an interconnector. Therefore, even if the square center of the cell body is deformed in a convex shape in the stacking direction due to a thermal cycle applied to the cell body, the cell body is stabilized by a member such as an interconnector without using a four-point support structure. Can be supported. Therefore, it is possible to reliably prevent cracking due to stress concentration on the cell body, and to improve the reliability on the structure of the cell body without reducing the power generation area.

1 is a schematic cross-sectional structure diagram of a state in which each component is disassembled with respect to a unit cell of a solid oxide fuel cell according to an embodiment. It is the typical top view and sectional side view of the laminated body 30a before baking the cell main body 30 of a comparative example. It is the typical top view and side sectional view of the cell baking body 30b after baking the laminated body 30a of FIG. 2 of a comparative example. FIG. 4 is a perspective view schematically showing a structure when a cell body 30 reflecting the structure of the cell fired body 30 b of FIG. 3 of the comparative example is joined to a contact surface 40. It is the typical top view and sectional side view of the laminated body 10a before baking the cell main body 10 of this embodiment. It is the typical top view and side sectional view of cell calcination object 10b after calcination of layered product 10a of Drawing 5 of this embodiment. It is a perspective view showing typically the structure when the cell body 10 reflecting the structure of the cell fired body 10b of this embodiment is joined to the contact surface 40. It is the typical top view and side sectional view of layered product 10a corresponding to Drawing 5 about cell main part 10 concerning the modification of this embodiment.

  Preferred embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below is an example of a form to which the technical idea of the present invention is applied, and the present invention is not limited by the content of the present embodiment.

  First, the basic structure of a solid oxide fuel cell to which the present invention is applied will be described. FIG. 1 shows a state in which each component is disassembled with respect to a solid oxide fuel cell 1 (hereinafter referred to as “unit cell 1”) which is a basic structural unit of the solid oxide fuel cell of the present embodiment. The schematic cross-sectional structure of is shown. A unit cell 1 shown in FIG. 1 includes a cell body 10 that performs a power generation function, a pair of upper and lower interconnectors 20 and 21, and a fuel electrode side disposed between a lower interconnector 20 and a fuel electrode layer 11. The current collector 22, the air electrode side current collector 23 disposed between the upper interconnector 21 and the air electrode layer 13, the metal frame 24 surrounding the side surface of the cell body 10, and the cell body 10 are integrated. Between the metal frame 24 and the lower interconnector 20. The separator 25 is joined to the fuel electrode layer 11 to separate the fuel gas flow path Fp on the fuel electrode layer 11 side and the air flow path Ap on the air electrode layer 13 side. And a gas seal member 27 disposed between the isolation separator 25 and the upper interconnector 21.

  A cell body 10 shown in FIG. 1 is formed by firing a laminated body composed of a fuel electrode layer 11, a solid electrolyte layer 12, and an air electrode layer 13 in order from the lower layer side, and has a rectangular outer peripheral shape in plan view. Have. The fuel electrode layer 11 is in contact with a fuel gas serving as a hydrogen source and functions as an anode of the unit cell 1. Since the fuel electrode layer 11 serves as a support base layer that supports the cell body 10, it is desirable to form the fuel electrode layer 11 with a sufficient thickness to ensure mechanical strength. For example, as the material of the fuel electrode layer 11, cermet made of metal particles such as Ni and ceramic particles can be used. The solid electrolyte layer 12 is made of various solid electrolytes having ionic conductivity. For example, as the material of the solid electrolyte layer 12, YSZ, ScSZ, SDC, GDC, perovskite oxide, or the like can be used. The air electrode layer 13 is in contact with air gas serving as an oxygen source and functions as a cathode of the unit cell 1. For example, as the material of the air electrode layer 13, perovskite oxides, various noble metals, and cermets of noble metals and ceramics can be used.

  The lower interconnector 20 is responsible for electrical connection with the unit cell 1 adjacent to the lower layer, and the upper interconnector 21 is responsible for electrical connection with the unit cell 1 adjacent to the upper layer. The interconnectors 20 and 21 are thin metal plates made of, for example, ferritic stainless steel. The fuel electrode side current collector 22 joined to the lower interconnector 20 is made of, for example, Ni felt having air permeability, and the air electrode side current collector 23 joined to the upper interconnector 21 is For example, it consists of a metal and a conductive ceramic.

  The lower gas seal member 26 is made of an insulating material such as mica, for example, and serves to seal the fuel gas flow path Fp in the unit cell 1. Similarly, the upper gas seal member 27 is made of an insulating material such as mica and serves to seal the air flow path Ap in the unit cell 1. Each gas seal member 26, 27 has an opening at the center for smoothly supplying fuel gas and air to the cell body 10.

  The metal frame 24 is made of a metal material such as ferritic stainless steel, for example, and serves to fix the cell body 10 and the separator 25 to the unit cell 1. Therefore, the metal frame 24 has an opening of a size that can surround the side surface of the cell body 10 at the center.

  The isolation separator 25 is formed in a frame-like thin plate having a thickness of about 0.02 to 0.3 mm using a metal material such as ferritic stainless steel as a flexible metal material. The isolation separator 25 functions as a cell joining member of the present invention and is joined to the peripheral edge of the cell body 10. The isolation separator 25 has a rectangular opening that is smaller in size than the outer peripheral shape of the cell body 10 and larger in size than the air electrode layer 13, and the air electrode layer 13 can be exposed from the opening. ing.

  Next, a characteristic structure of the unit cell 1 of the present embodiment will be described. In the present embodiment, a shape change of a cell fired body formed by firing the cell body 10 is assumed in advance, and a predetermined shape is defined for the laminate before firing the cell body 10. First, as a comparative example for comparison with the structure of the present embodiment, a cell body 30 (FIG. 4) having a conventional structure will be described along with an outline of the manufacturing method. FIG. 2 shows a schematic plan view and a side sectional view of the laminate 30a before firing the cell body 30 of the comparative example, and FIG. 3 shows a cell fired body 30b after firing the laminate 30a of FIG. The schematic top view and side sectional drawing of are shown. In addition, regarding the direction of the laminated body 30a of FIG. 2 and the cell baking body 30b of FIG. 3, the top view shown to the upper part of each figure respond | corresponds when the cell main body 10 of FIG.

  The laminated body 30a in FIG. 2 is prepared by preparing a rectangular fuel electrode green sheet and a rectangular solid electrolyte green sheet, and integrating them by press molding in a state where the green sheets are stacked. Therefore, at this time, the air electrode layer 13 is not formed on the stacked body 30a. In FIG. 2, the distinction between the fuel electrode layer 11 and the solid electrolyte layer 12 is not shown, and is represented as an integral laminate 30a. As shown in the top plan view of FIG. 2, the stacked body 30a has a square shape in plan view, is surrounded by four side surfaces Sa having four sides, and four corners Ca where the side surfaces Sa intersect. Is chamfered. Further, in the lower part of FIG. 2, a side sectional view of the a-a ′ section and a side sectional view of the b-b ′ section in the laminate 30 a in a plan view are shown. The a-a ′ cross section is a cross section passing through the vicinity of the outer edge portion of the rectangular stacked body 30 a, and the b-b ′ cross section is a cross section passing through the center of the square stacked body 30 a. Both the a-a ′ cross section and the b-b ′ cross section have a flat linear cross section. This is because, as described above, the laminate 30a is not fired, so that deformation in the stacking direction due to heating during firing does not occur.

  Next, the cell fired body 30b in FIG. 3 is produced by firing the laminated body 30a in FIG. 2 at a predetermined temperature. In this case, the cell fired body 30b is deformed (warped) in the stacking direction due to heating during firing and oxidation / reduction cycles or thermal cycles during power generation. In the cell fired body 30b, the cell body 30 described later is obtained by laminating and forming the air electrode layer 13 at a predetermined position. As shown in the top plan view of FIG. 3, the cell fired body 30b is surrounded by four side surfaces Sb of the four sides in a plan view, but these side surfaces Sb are not linear but like the side surface Sa of FIG. It has a concave curved shape on the circumferential side. In addition, in the lower part of FIG. 3, a side sectional view of the a-a ′ section and a side sectional view of the b-b ′ section of the cell fired body 30 b in plan view are shown. Each position in the a-a ′ cross section and the b-b ′ cross section is the same as that in FIG. 2. Moreover, the position of the contact surface 40 when the cell baking body 30b contacts the surface of the interconnector 20 of FIG. Both the a-a ′ cross section and the b-b ′ cross section have a curved cross-sectional shape in which the vicinity of the center of the cross section protrudes upward, not a flat straight line shape, due to the deformation in the stacking direction. Further, it can be seen that both ends of the a-a ′ section are substantially in contact with the contact surface 40, whereas both ends of the b-b ′ section are located above the contact surface 40.

  Here, as shown in the lower part of FIG. 3, the line length along the curve of the aa ′ section is L1 ′, the maximum height is H1 ′, and the line along the curve of the bb ′ section. The length is L2 ′ and the maximum height is H2 ′. In this case, the line lengths L1 'and L2' satisfy the relationship L1'≈L2 '. This is because in FIG. 2, the a-a ′ section and the b-b ′ section have the same line length, and the relationship is maintained even after firing. On the other hand, both heights H1 'and H2' satisfy the relationship H1 '<H2'. That is, the height H2 ′ that is the amount of warpage of the bb ′ section is larger than the height H1 ′ that is the amount of warpage of the aa ′ section, and the cell fired body 30b protrudes in a convex shape at the center. The substantially same line length (L1, L2) is maintained from the relationship of the formula. Therefore, both end portions of the bb ′ cross section are reduced to the inner peripheral side from the positions of both end portions of the aa ′ cross section in the lateral direction, and are lifted upward from the contact surface 40 in the stacking direction. .

  FIG. 4 is a perspective view schematically showing the structure when the cell main body 30 reflecting the structure of the cell fired body 30b of FIG. 3 contacts the contact surface 40 (the surface of the interconnector 20). It can be seen that the cell main body 30 shown in FIG. 4 has a structure in which the central portion protrudes upward and is supported by the contact surface 40 with the four corners as contact points (four-point support). In FIG. 4, for ease of understanding, the deformation amount that the cell body 30 protrudes in the stacking direction is emphasized, but the actual deformation amount is sufficiently smaller than the size of the cell body 30. As a result of the cell main body 30 having the structure shown in FIG. 4, when stress is applied to the cell main body 30 in the stacking direction, the area of the contact is extremely small, so that there is a possibility of causing defects such as cracking of the cell main body 30.

  Next, the structure of the cell body 10 adopting the structure of the present embodiment will be described. FIG. 5 shows a schematic plan view and a side sectional view of the laminate 10a before firing the cell body 10 of the present embodiment, and FIG. 6 shows a cell fired body after firing the laminate 10a of FIG. 10b shows a schematic plan view and a side sectional view of 10b. In addition, the direction of the laminated body 10a of FIG. 5 and the cell baking body 10b of FIG. 6 is the same as FIG. 2 and FIG. 3 of a comparative example. Moreover, since the outline of each manufacturing method of the laminated body 10a and the cell fired body 10b is also as described in the comparative example, the description is omitted.

  As shown in the top plan view of FIG. 5, the laminated body 10a is surrounded by four side surfaces S1 having an arc shape in plan view, and four corners C1 where the side surfaces S1 intersect are chamfered. The four corners C1 have an arc shape with a radius of curvature R1 in a plan view, and the four side surfaces S1 have an arc shape with a radius of curvature R2 in a plan view, and have a relationship of R1 <R2. Further, in the lower part of FIG. 5, a side sectional view of the a-a ′ section and a side sectional view of the b-b ′ section in the laminate 10 a in a plan view are shown. Each position in the a-a ′ cross section and the b-b ′ cross section is the same as that in FIG. 2. Although both the a-a ′ section and the b-b ′ section of the unfired laminated body 10a have the same flat cross-sectional shape, they are the same as those in FIG. That is, corresponding to the shape of each side surface S1 in FIG. 5, the line length along the straight line of the aa ′ cross section of the outer edge part is L3, and the line length along the straight line of the bb ′ cross section of the center part. Is L4, which satisfies the relationship L3 <L4.

  Next, as described above, the cell fired body 10b in FIG. 6 is deformed (warped) in the stacking direction due to heating during firing of the laminated body 10a, oxidation / reduction cycle or thermal cycle during power generation operation. . As shown in the top plan view of FIG. 6, in the cell fired body 10 b, the four side surfaces S <b> 1 on the four sides change from the curved shape of FIG. 5 to a linear shape in plan view. Further, in the lower part of FIG. 6, a side sectional view of the a-a ′ section and a side sectional view of the b-b ′ section of the cell fired body 10 b in plan view are shown. The positions of the a-a ′ and b-b ′ sections and the position of the contact surface 40 are the same as those in FIG. 3. First, the b-b ′ cross-section has a curved cross-sectional shape in which the vicinity of the center of the cross-section protrudes upward, not due to the deformation in the stacking direction. On the other hand, the a-a ′ cross section has a cross-sectional shape that is slightly flat near the center but is nearly flat. Further, it can be seen that both ends of the a-a ′ cross section and the b-b ′ cross section are in contact with the contact surface 40.

  Here, as shown in the lower part of FIG. 6, the line length along the curve of the aa ′ cross section is L1, the maximum height is H1, and the line length along the curve of the bb ′ cross section is Let L2 be the maximum height. In this case, unlike FIG. 3, the line lengths L1 and L2 in FIG. 6 satisfy the relationship of L1 <L2. This is because the bb ′ section has a longer line length than the aa ′ section when unfired as shown in FIG. 5 (L3 <L4), so that the relationship is maintained even after firing. . On the other hand, both heights H1 and H2 have a relationship of H1 <H2, and H1 in FIG. 6 is extremely smaller than the height H1 ′ in FIG. The difference between FIG. 3 and FIG. 6 as described above is based on the fact that the four side surfaces S1 in the laminated body 10a of FIG.

  FIG. 7 is a perspective view schematically showing the structure when the cell body 10 reflecting the structure of the cell fired body 10b of FIG. 6 of the present embodiment contacts the contact surface 40 (the surface of the interconnector 20). It can be seen that the cell body 10 shown in FIG. 7 has a structure in which the central portion protrudes upward, and the corners and sides of the four corners of the outer edge are supported by the contact surface 40 over the entire circumference. That is, not the four-point support as shown in FIG. 4, but the contact area (contact length) with the contact surface 40 can be sufficiently maintained. It should be noted that the ideal contact state is that each corner of the cell body 10 and all the regions on each side are supported by the contact surface 40 as shown in FIG. A structure in which the portion and each side are partially supported by the contact surface 40 may be used. As described above, by adopting the structure of the present embodiment, even if stress is applied to the cell body 10 in the stacking direction, defects such as cracking of the cell body 10 which are problematic in the structure of FIG. There is an effect to prevent.

  5 to 7, the laminated body 10a is surrounded by the arc-shaped side surface S1 in a plan view. However, the side surface S1 constituting the outer peripheral shape of the laminated body 10a is not limited to the arc shape, and may be a plane. It can be formed in various shapes visually. However, it is a premise that each side of the cell fired body 10b obtained by firing the laminate 10a is at least partially supported by the contact surface 40. Further, in the laminated body 10a in FIG. 5, each corner C1 is chamfered in an arc shape in a plan view (R chamfering), but may be chamfered in a straight line (C chamfering) or not chamfered. However, the present invention can be applied.

  Hereinafter, specific examples of dimensions of the cell body 10 having the structure of FIGS. 5 and 6 will be described. First, the lengths L3 and L4 of the outer edge part and the center part of the laminated body 10a of FIG. 5 are set to L3 = 150 mm and L4 = 150.008 mm, for example. Moreover, the lengths L1 and L2 of the outer edge part and the center part of the cell fired body 10b of FIG. 6 are set to L1 = 120 mm and L2 = 1200.06 mm, for example. Moreover, the curvature radius R1 of each corner | angular part C1 of the laminated body 10a of FIG. 5 and the curvature radius R2 of each side surface S1 are set to R1 = 3 mm and R2 = 60.003 mm, for example. In this case, the difference between the maximum heights H2 and H1 in the cell fired body 10b of FIG. 6 is, for example, about H2−H1 = 0.6 mm. Note that the ratio of the lengths L3 and L4 of the laminated body 10a and the ratio of the lengths L1 and L2 of the cell fired body 10b are emphasized in FIGS. 5 and 6, but only a slight difference is actually given. Thus, the effect of this embodiment can be obtained.

  A cell body 10 having the structure shown in FIGS. 5 and 6 was produced and a reliability test was performed. That is, after performing the oxidation / reduction cycle and thermal cycle tests on the plurality of unit cells 1 each including the cell body 10 having the conventional structure and the cell body 10 having the structure of the present embodiment under predetermined conditions. The ratio of occurrence of defects due to cracking of the cell body 10 was determined. As a result, in the case of the cell body 10 having the conventional structure, the defect ratio was 9.1% (out of the total 2299, 210 defects), whereas the cell body 10 having the structure of the present embodiment. In this case, the defect ratio was 2.0% (20 defects out of the total 1023), and it was confirmed that the defect ratio can be greatly reduced.

  In the present embodiment, the structure of the above-described cell body 10 has been specifically described. However, the present invention is not limited to the above-described structure, and can be applied to various modifications. FIG. 8 is a schematic plan view of a stacked body 10a corresponding to FIG. 5 with respect to the cell body 10 according to the modified example of the present embodiment. In the modification of FIG. 8, the stacked body 10 a is surrounded by eight straight side surfaces S <b> 2 instead of a curved shape in plan view. That is, one arcuate side surface S1 in FIG. 5 corresponds to the two linear side surfaces S2 in FIG. 8, and the outer peripheral shape of the laminate 10a is formed by a total of eight side surfaces S2. These eight side surfaces S2 have the same length in plan view. In the modification of FIG. 8, two side surfaces S2 intersect at a position P corresponding to the center of each side in FIG. 5, and the angle at which the two side surfaces S2 intersect at the position P is set appropriately. The effect similar to the structure of FIGS. 5-7 can be acquired. In the cell fired body 10b obtained by firing the laminated body 10a of FIG. 8, the eight side surfaces S2 in addition to the corner portion C1 are partially formed even when the entire eight side surfaces S2 are not supported by the contact surface 40. In other words, it may be supported by the contact surface 40. Although not shown in the modified example of FIG. 8, each corner C1 may be chamfered by R chamfering, C chamfering, or the like.

  Next, the steps related to the characteristic structure of the present embodiment in the method for manufacturing the unit cell 1 of the present embodiment will be supplementarily described. First, the production of the laminate 10a and the cell fired body 10b corresponding to the cell body 10 is as described with reference to FIGS. 2 to 7 (cell body forming step). On the other hand, an isolation separator 25 having an opening at the center is manufactured by a known technique by punching a thin metal plate. Then, the cell body 10 is aligned with respect to the separator 25 as a cell joining member in the positional relationship shown in FIG. 3, and the bottom surface of the separator 25 and the upper surface of the outer edge of the cell body 10 are, for example, using brazing material. Join (joining process). Thereafter, the integrated cell body 10 and isolation separator 25 are attached to the metal frame 24, and the gas seal members 26 and 27, the fuel electrode side current collector 22, the air electrode side current collector 23, and the interconnector shown in FIG. 20 and 21 are integrally laminated to form the unit cell 1.

  In the above description, the case where the unit cell 1 which is a basic structural unit of the solid oxide fuel cell is manufactured has been described. However, the fuel cell stack manufactured by stacking a plurality of unit cells 1 is used. Also, the present invention can be applied.

  The contents of the present invention have been specifically described above based on the present embodiment, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, in the unit cell 1 of the present embodiment, the cell body 10 includes the fuel electrode layer 11, the solid electrolyte layer 12, and the air electrode layer 13, but the cell body 10 includes functional layers different from these layers. May be. Further, the unit cell 1 of the present embodiment has a structure that can be supported on the surface of the interconnector 20 whose four corners and four sides of the cell body 10 are predetermined members, but the predetermined member is not limited to the interconnector 20. Other members that can be arranged may be used. Further, the contents of the present invention are not limited to the above-described embodiments by other embodiments, and the present invention is not limited to the contents disclosed in the above-described embodiments within the range where the effects of the present invention can be obtained. Can be changed.

1. Solid oxide fuel cell (unit cell)
DESCRIPTION OF SYMBOLS 10 ... Cell main body 10a ... Laminated body 10b ... Cell sintered body 11 ... Fuel electrode layer 12 ... Solid electrolyte layer 13 ... Air electrode layer 20, 21 ... Interconnector 22 ... Fuel electrode side collector 23 ... Air electrode side collector 24 ... metal frame 25 ... isolation separators 26, 27 ... gas seal member 40 ... contact surface

Claims (10)

A cell body formed by laminating and firing a fuel electrode layer, an air electrode layer, and a solid electrolyte layer in which the fuel electrode layer is disposed on one side and the air electrode layer is disposed on the other side In a solid oxide fuel cell comprising:
The cell body has a rectangular outer peripheral shape including four sides that are linear in a plan view, and the height in the stacking direction at the center of the square is higher than the height in the stacking direction at the four sides of the square. Has a convex cross-sectional shape in the direction,
Peripheral edge, and four corners of the square, and all or part of the four sides, the solid oxide fuel cell characterized by having a support structure capable in contact with the predetermined member and the cell body. A cell body formed by laminating and firing a fuel electrode layer, an air electrode layer, and a solid electrolyte layer in which the fuel electrode layer is disposed on one side and the air electrode layer is disposed on the other side In a solid oxide fuel cell comprising:
The cell body has a rectangular outer peripheral shape including four sides that are linear in a plan view, and the height in the stacking direction at the center of the square is higher than the height in the stacking direction at the four sides of the square. Has a convex cross-sectional shape in the direction,
Of the group of curves included in the cross-sectional shape, a first curve that passes through the central portion and is parallel to the sides of the square in plan view passes through the vicinity of the sides and is parallel to the first curve in plan view. A solid oxide fuel cell having a long line length compared to the line length of the second curve.   3. The solid oxide fuel cell according to claim 1, wherein the cell body has an outer peripheral shape chamfered at four corners of the square. The solid oxide fuel cell according to any one of claims 1 to 3, further comprising a plate-shaped cell joining member joined to a peripheral edge of the cell body. A laminating step of laminating a plurality of flat sheets including at least a support base layer, and forming a laminate having an outer peripheral shape including four sides curved or protruded on the outer peripheral side in plan view;
A cell body forming step of firing the laminate to form a cell fired body, and forming a cell body including the cell fired body,
Including
The cell body has a rectangular outer peripheral shape including four sides that are linear in a plan view, and the height in the stacking direction at the center of the square is higher than the height in the stacking direction at the four sides of the square. Has a convex cross-sectional shape in the direction,
Peripheral edge of the cell body, and the four corners of the square, and all or part of the four sides, the solid oxide fuel, characterized in that it is formed in the support structure capable in contact with a predetermined member Battery manufacturing method. A laminating step of laminating a plurality of flat sheets including at least a support base layer, and forming a laminate having a flat cross-sectional shape with an outer peripheral shape including four sides curved or protruded on the outer peripheral side in plan view;
A cell body forming step of firing the laminate to form a cell fired body, and forming a cell body including the cell fired body,
The cell body has a rectangular outer peripheral shape including four straight sides in plan view, and the height in the stacking direction at the center of the square is higher than the height in the stacking direction at the four sides of the square. , Having a convex cross-sectional shape in the stacking direction,
Of the group of curves included in the cross-sectional shape of the cell body, a first curve that passes through the central portion and is parallel to each side of the square is a second curve that passes through the vicinity of each side and is parallel to the first straight line. A method for producing a solid oxide fuel cell, characterized by having a long line length compared to the line length of the curve.   The laminated body is an arcuate curve in which each of the four corners of the square is chamfered in an arc shape with a first radius of curvature, and each of the four sides has a second radius of curvature larger than the first radius of curvature. The method for producing a solid oxide fuel cell according to claim 5 or 6.   The said cell main body formation process includes the 2nd lamination process of laminating | stacking a predetermined layer on the surface of the said cell baking body, and forming the said cell main body, It is any one of Claim 5 to 7 characterized by the above-mentioned. The manufacturing method of the solid oxide fuel cell of description. 9. The method for manufacturing a solid oxide fuel cell according to claim 8 , wherein the support base layer is the fuel electrode layer, and the predetermined layer is the air electrode layer. Solid oxidation formed by laminating and firing a fuel electrode layer, an air electrode layer, and a solid electrolyte layer in which the fuel electrode layer is disposed on one surface side and the air electrode layer is disposed on the other surface side In the body fuel cell body,
The cell body has a rectangular outer peripheral shape including four sides that are linear in a plan view, and the height in the stacking direction at the center of the square is higher than the height in the stacking direction at the four sides of the square. A solid oxide fuel cell main body having a convex cross-sectional shape in a direction.