WO2015045926A1

WO2015045926A1 - Solid oxide fuel cell stack

Info

Publication number: WO2015045926A1
Application number: PCT/JP2014/074307
Authority: WO
Inventors: 陽介朝重; 智昭平井; 和英高田
Original assignee: 株式会社村田製作所
Priority date: 2013-09-27
Filing date: 2014-09-12
Publication date: 2015-04-02
Also published as: JP6119869B2; JPWO2015045926A1

Abstract

Provided is a solid oxide fuel cell stack, which is capable of maintaining electrical connection between layers even if peeling between the layers is generated in the cases where heat cycle is applied, and which has improved electrical connection reliability. Disclosed is a solid oxide fuel cell stack (1) wherein: a plurality of solid oxide fuel cells (2) are laminated; at an area where the fuel cells (2, 2) are laminated to each other, a metal layer (10) is disposed between one of the fuel cells (2) and the other one of the fuel cells (2); conductive material layers (11) are disposed between the metal layer (10) and respective fuel cells (2) such that the metal layer (10) and the fuel cells (2) are electrically connected to each other; and conductive vias (3) are provided so as to be positioned between respective conductive material layers (11) and the metal layer (10) and/or between respective conductive material layers (11) and respective fuel cells (2) such that the conductive material layers (11) are electrically connected with the metal layer (10) and/or the fuel cells (2).

Description

Solid oxide fuel cell stack

The present invention relates to a solid oxide fuel cell stack in which a plurality of solid oxide fuel cells are stacked.

Conventionally, various solid oxide fuel cells using a solid oxide electrolyte have been proposed. In a solid oxide fuel cell, a plurality of fuel cells are stacked in order to obtain a sufficient voltage. Thereby, a fuel cell stack is configured. The following Patent Document 1 discloses a fuel cell stack formed by laminating a plurality of flat plate-type fuel cells using ceramics. When thermal stress is applied, in the fuel cell stack, there is a risk of poor conduction due to deformation of the fuel cell. In Patent Document 1, a cell following deformation portion is provided on at least one of the one end side and the other end side in the stacking direction. Thereby, the conduction failure when the thermal cycle is applied is suppressed.

WO2010 / 038869 JP 2006-310005 A

The thermal conductivity of ceramics is relatively low. Therefore, when the number of stacks of fuel cells using ceramics is increased, the heat generated by power generation tends to be trapped near the center of the fuel cell stack. For this reason, heat distribution is generated on the surface of the fuel cell, and there is a possibility that the cell is cracked by thermal stress.

On the other hand, as described in Patent Document 2, a method of reducing the nonuniformity of heat distribution by arranging a metal layer such as a metal film or a metal plate between cells is also known. In this case, the influence of thermal stress can be reduced. However, since the thermal expansion coefficients of the metal and the ceramic are considerably different, there is a possibility that separation between the metal and the ceramic occurs. Since the electrical connection was achieved by the direct contact between the metal and the ceramic, there was a problem that the electrical connection was broken when the above-described peeling occurred.

The object of the present invention is to maintain the electrical connection between the layers even when peeling between layers occurs when a thermal cycle is applied, etc., and the reliability of the electrical connection is improved. The object is to provide a physical fuel cell stack.

The solid oxide fuel cell stack according to the present invention has a structure in which a plurality of fuel cells are stacked. The solid oxide fuel cell stack according to the present invention includes a plurality of stacked solid oxide fuel cells, and a portion where the fuel cells are stacked, and one of the fuel cells and the other A metal layer disposed between the fuel cell and the metal layer and the fuel cell so as to electrically connect the metal layer and the fuel cell. The conductive material layer, the conductive material layer, and between the conductive material layer and the metal layer and the conductive material so as to electrically connect at least one of the metal layer and the fuel cell. A conductive via provided so as to be located in at least one of the layer and the fuel cell. The conductive via means a columnar conductor that electrically connects the layers.

In a specific aspect of the solid oxide fuel cell stack according to the present invention, the conductive via protrudes from the conductive material layer at the power generation temperature of the fuel cell.

In still another specific aspect of the solid oxide fuel cell stack according to the present invention, the conductive via penetrates the conductive material layer, and the conductive material layer, the metal layer, and the fuel cell. And are electrically connected.

In still another specific aspect of the solid oxide fuel cell stack according to the present invention, the conductive via is formed in the metal layer side of the conductive material layer and the surface layer on the fuel cell side, and The conductive material layer is electrically connected to the metal layer and the fuel cell.

In still another specific aspect of the solid oxide fuel cell stack according to the present invention, the conductive via extends from the metal layer side of the conductive material layer and the fuel cell side to the inside of the conductive material layer. The conductive material layer is electrically connected to the metal layer and the fuel battery cell.

In still another specific aspect of the solid oxide fuel cell stack according to the present invention, the conductive via is formed on a surface layer of either the metal layer side or the fuel cell side of the conductive material layer. And the said electrically-conductive material layer and either the said metal layer or the said fuel cell are electrically connected.

In still another specific aspect of the solid oxide fuel cell stack according to the present invention, the conductive via is mainly composed of Pt, Pd, Ag, Au, Ru, Rh, Ni, Fe, Cr and these metals. And at least one metal selected from the group consisting of alloys.

According to the solid oxide fuel cell stack according to the present invention, the conductive material layer is electrically connected to the metal layer and / or the fuel battery cell by the conductive via made of metal. Therefore, even if a thermal cycle is applied and peeling occurs between the conductive material layer and the metal layer and / or the fuel cell, the electrical connection is maintained between the conductive material layer and the metal layer and the fuel cell. can do. Therefore, the reliability of electrical connection can be improved.

FIG. 1A and FIG. 1B are schematic front cross-sectional views showing the main parts of a fuel cell stack according to the first embodiment of the present invention. FIG. 2 is an exploded perspective view of one fuel cell used in the fuel cell stack according to the first embodiment of the present invention. FIG. 3 is a plan view of one fuel cell used in the fuel cell stack according to the first embodiment. FIG. 4 is a perspective view schematically showing a part of the fuel cell stack of the first embodiment. FIG. 5 shows the relationship between the fuel cell / metal interlayer resistance and the number of thermal cycles in the first embodiment of the present invention, and the fuel cell / metal interlayer resistance and thermal cycle in a comparative example in which no conductive via is provided. It is a graph which shows the relationship with the frequency | count. FIG. 6 is a schematic front sectional view showing a main part of the fuel cell stack of the second embodiment. FIG. 7 is a schematic front sectional view showing the main part of the fuel cell stack of the third embodiment. FIG. 8 is a schematic front sectional view showing the main part of the fuel cell stack of the fourth embodiment. FIG. 9 is a schematic front sectional view showing the main part of the fuel cell stack of the fifth embodiment.

Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

FIG. 1A is a schematic front sectional view of a fuel cell stack according to a first embodiment of the present invention. In the fuel cell stack 1, the upper fuel cell 2 and the lower fuel cell 2 are joined via a joint 4. In FIG. 1 (a), two

fuel cells

2 and 2 are shown, but in this embodiment, a structure in which the

fuel cells

2 and 2 on both sides are stacked via the joint 4 is further provided. It is lined up.

In FIG. 1 (a), only the positions where the

fuel cells

2 and 2 are provided are schematically shown. Details of one fuel cell 2 will be described with reference to FIGS. 2 and 3.

As shown in FIG. 2, the fuel cell 2 has a solid oxide electrolyte layer 7. The solid oxide electrolyte layer 7 is made of a ceramic having high ionic conductivity. Examples of such materials include stabilized zirconia and partially stabilized zirconia. More specifically, zirconia stabilized by Y or Sc is mentioned. Examples of the stabilized zirconia include 10 mol% yttria stabilized zirconia (10YSZ) and 11 mol% scandia stabilized zirconia (11ScSZ). Examples of the partially stabilized zirconia include 3 mol% yttria partially stabilized zirconia (3YSZ).

Incidentally, the material constituting the solid oxide electrolyte layer 7 is not limited to the above, Sm and Gd-doped ceria-based oxide _{_{_{_{and, La 0.8 Sr 0.2 Ga 0.8 Mn}}}} 0.2 O _It may be formed of a perovskite oxide such as _(3-δ) . Δ represents a positive number less than 3.

The solid oxide electrolyte layer 7 is provided with a through hole 7a and a through hole 7b. The through hole 7a constitutes a fuel gas flow path. The through hole 7b constitutes an air flow path through which air as an oxidant gas passes.

The fuel electrode layer 6 is laminated above the solid oxide electrolyte layer 7. The fuel electrode layer 6 can be composed of yttria-stabilized zirconia containing Ni, scandia-stabilized zirconia containing Ni, or the like. The fuel electrode layer 6 is provided with a slit 6a constituting a fuel gas flow path and a slit 6b constituting an air flow path.

The separator 5 is laminated on the fuel electrode layer 6. The separator 5 can be formed of stabilized zirconia, partially stabilized zirconia, or the like. Through

holes

5 a and 5 b are formed in the separator 5. The through hole 5a constitutes a fuel gas flow path. The through hole 5b constitutes an air flow path.

On the other hand, the separator 5 is provided with a plurality of interconnectors 5c for taking out electricity so as to penetrate the lower surface from the upper surface of the separator 5. That is, each interconnector 5c is formed by a via-hole conductor. The plurality of interconnectors 5 c are electrically connected to the fuel electrode layer 6.

On the other hand, an air electrode layer 8 and a separator 9 are laminated below the solid oxide electrolyte layer 7. The air electrode layer 8 is provided with a slit 8a that constitutes a fuel gas passage and a slit 8b that constitutes an air passage. The air electrode layer 8 is preferably made of a porous material having high electron conductivity. Such an air electrode layer 8 includes, for example, scandia-stabilized zirconia (ScSZ), ceria doped with Gd, indium oxide doped with Sn, PrCoO ₃ oxide, LaCoO ₃ oxide, or LaMoO ₃ oxide. It can be formed of an oxide or the like. Examples of the LaMoO ₃ oxide include La _0.8 Sr _0.2 MnO ₃ (hereinafter abbreviated as LSM) and La _0.6 Ca _0.4 MnO ₃ .

The separator 9 is configured in the same manner as the separator 5. Therefore, it has the through-hole 9a which comprises a fuel gas flow path, the through-hole 9b which comprises an air flow path, and the several interconnector 9c.

FIG. 3 shows a plan view of the single fuel cell 2. As shown in FIG. 3, the fuel battery cell 2 has a cross-shaped flow path component 2a and four

power generation units

2b, 2c, 2d, and 2e partitioned by the flow path component 2a when viewed in plan. . The interconnector 5c is exposed on the upper surfaces of the power generation units 2b to 2e.

Referring back to FIG. 1A, in the fuel cell stack 1 of the present embodiment, a plurality of such fuel cells 2 are stacked. FIG. 4 is a perspective view showing a part of the fuel cell stack 1. The part corresponds to a portion where one

power generation section

2b, 2c, 2d or 2e divided by the cross-shaped flow path constituting section 2a shown in FIG. 3 is laminated. As shown in FIG. 4, the

fuel cells

2, 2, 2 are stacked via the

joints

4, 4. In practice, as shown in FIG. 3, the power generation units 2b and 2c are located on both sides of the flow path component 2a.

Referring back to FIG. 1A, the fuel cell stack 1 according to this embodiment is characterized by the structure of the joint 4 that joins the fuel cell 2 and the fuel cell 2 to each other.

The joint 4 physically joins and integrates the upper fuel cell 2 and the lower fuel cell 2 and electrically connects the upper fuel cell 2 and the lower fuel cell 2 in series. Connected.

In FIG. 1 (a), a metal layer 10 is provided in order not to concentrate heat in the center and to electrically connect the upper fuel cell 2 and the lower fuel cell 2 to each other.

The metal layer 10 is made of a metal plate in the present embodiment. The material constituting the metal plate is not particularly limited, but it is desirable to use a metal having a thermal expansion coefficient close to that of the ceramic constituting the fuel cell 2. As such a material, preferably, ferritic stainless steel can be used. The thermal expansion coefficient of ferritic stainless steel is close to that of zirconia. Ferritic stainless steel has excellent heat resistance. Accordingly, ferritic stainless steel is preferred.

But the material which comprises the said metal layer 10 is not specifically limited, You may use another metal.

A conductive material layer 11 is provided on each of the upper and lower surfaces of the metal layer 10.

In this embodiment, the conductive material layer 11 is made of LSM, which is a conductive ceramic material.

But the material which comprises the said electrically-conductive material layer 11 is not specifically limited, What is necessary is just to have favorable electroconductivity. For example, LaSrCoO ₃ , LaSrCoFeO ₃ , MnCoO ₃ , SmSrCoO ₃ , LaCaMnO ₃ , LaCaCoO ₃ , LaCaCoFeO ₃ , LaNiFeO ₃ , (LaSr) ₂ NiO _{4, and the} like can be used for conductive ceramic materials. In general, other refractory metals can be used.

Further, in the present embodiment, the bonding portion 4 is a laminated structure of the adhesive layer 12 and the spacer 13 in a region different from the bonding portion that electrically connects the

power generation portions

2b, 2c, 2d, and 2e. Have Here, the spacer 13 does not necessarily have to be provided, but it is desirable to use the spacer 13 for facilitating adhesion when the distance between the

fuel cells

2 and 2 is large. The material constituting the spacer 13 is not particularly limited, but a material having a thermal expansion coefficient close to that of the ceramic constituting the fuel cell 2 is desirable. Although the material which comprises the said adhesive bond layer 12 is not specifically limited, The material which expresses favorable adhesiveness between the said

fuel cell

2 and 2 or between the said fuel cell and the said spacer 13 is desirable.

As shown in FIG. 1B, the conductive via 3 is provided so as to penetrate the conductive material layer 11 and protrude toward the metal layer 10 side and the fuel cell 2 side. The conductive via 3 has a columnar shape in this embodiment. One end of the conductive via 3 is provided in contact with the metal layer 10, and the other end is provided in contact with the fuel cell 2. In the present embodiment, the conductive via 3 electrically connects the conductive material layer 11, the metal layer 10, and the fuel cell 2.

The conductive via 3 is made of metal in the present embodiment. Although it does not specifically limit as this metal, It is desirable that it is a metal which has heat resistance and electroconductivity. It is particularly preferable that the main component is at least one kind of metal selected from the group consisting of Pt, Pd, Ag, Au, Ru, Rh, Ni, Fe, Cr and alloys mainly composed of these metals. In this specification, “mainly” means to occupy 1/2 or more.

The

gaps

14a and 14b as shown in FIG. 1 (b) are caused by separation between the conductive material layer 11, the metal layer 10 and the fuel cell 2 when, for example, a thermal cycle is applied. Arise. When the

gaps

14a and 14b are generated, if the conductive via 3 is not provided between the conductive material layer 11 and the metal layer 10 and the fuel cell 2, the electrical connection is cut off. . On the other hand, in the present embodiment, even if the

gaps

14a and 14b are generated, the conductive material layer 11, the metal layer 10, and the fuel cell 2 are electrically connected by the conductive via 3. Maintained. Therefore, in the fuel cell stack 1, the reliability of electrical connection can be effectively increased.

The conductive via 3 of the present embodiment can be formed, for example, by making a through hole in the conductive material layer 11 and pouring metal therethrough. The above is an example of a method for forming the conductive via 3, and the conductive via 3 may be formed by other methods.

The fact that the reliability of electrical connection can be improved according to the present embodiment will be described based on a specific experimental example.

FIG. 5 is a diagram showing the relationship between the resistance of the fuel cell according to the embodiment and the fuel cell of the comparative example and the metal layer, and the number of thermal cycles. The fuel cell of the comparative example was manufactured in the same manner as in the above embodiment except that the conductive via 3 was not provided.

As is apparent from FIG. 5, the thermal cycle characteristics of the resistance between the fuel cell and the metal layer in the fuel cell stack of the above embodiment are dramatically improved as compared with the comparative example in which the conductive via 3 is not provided. I understand that.

FIG. 6 is a schematic front sectional view of a fuel cell stack according to the second embodiment of the present invention. In the second embodiment, the

conductive vias

3 a and 3 b are formed in the surface layer on the metal layer 10 side and the surface layer on the fuel cell 2 side of the conductive material layer 11. The

conductive vias

3a and 3b correspond to a shape obtained by dividing the conductive via 3 of the first embodiment. The conductive vias 3a and the conductive vias 3b forming a pair are arranged so as to overlap in the vertical direction. The

conductive vias

3a and 3b are provided so as to protrude toward the metal layer 10 side and the fuel cell 2 side. The

conductive vias

3 a and 3 b electrically connect the conductive material layer 11, the metal layer 10, and the fuel cell 2. Since the other configuration is the same as that of the first embodiment, the detailed description is omitted by using the description of the first embodiment. Note that the

conductive vias

3a and 3b may not be arranged so as to overlap in the vertical direction.

In the second embodiment, even if

gaps

14 a and 14 b are generated between the conductive material layer 11, the metal layer 10, and the fuel cell 2, the conductive material layer is formed by the

conductive vias

3 a and 3 b. 11, the metal layer 10 and the fuel cell 2 are electrically connected. Therefore, the electrical connection is not broken. Furthermore, compared with the first embodiment, the material constituting the conductive via can be reduced.

FIG. 7 is a schematic front sectional view of a fuel cell stack according to the third embodiment of the present invention. In the third embodiment, the

conductive vias

3 a and 3 b are formed so as to reach the inside of the conductive material layer 11 from the metal layer 10 side and the fuel cell 2 side of the conductive material layer 11. The

conductive vias

3a and 3b have a large depth which is a degree reaching the inside of the conductive material layer 11. The conductive via 3a and the conductive via 3b are arranged so as not to overlap in the vertical direction. The

conductive vias

3 a and 3 b electrically connect the conductive material layer 11, the metal layer 10, and the fuel cell 2.

In the third embodiment, even if

gaps

14a and 14b are generated between the metal layer 10 and the fuel cell 2, the electrical connection can be maintained by the

conductive vias

3a and 3b. Furthermore, compared to the first embodiment, the material constituting the conductive via can be reduced. The

conductive vias

3 a and 3 b are formed so as to reach the inside of the conductive material layer 11. Therefore, in this embodiment, compared to the second embodiment, when the peeling occurs in at least one of the conductive material layer 11 and the metal layer 10 or the fuel cell 2, the conductive material is used. The

vias

3a and 3b are unlikely to rise. Therefore, the reliability of electrical connection can be further improved.

In the second and third embodiments, the

conductive vias

3a and 3b were formed in the same manner on the metal layer 10 side and the fuel cell 2 side of the conductive material layer 11. However, the

conductive vias

3a and 3b may be formed differently on the metal layer 10 side and the fuel cell 2 side of the conductive material layer 11. For example, the conductive via 3 a is formed on the surface layer of the conductive material layer 11 on the metal layer 10 side, and the conductive via 3 b is formed on the conductive material layer 11 from the fuel cell 2 side of the conductive material layer 11. It may be formed so as to reach the inside.

FIG. 8 is a schematic front sectional view of a fuel cell stack according to the fourth embodiment of the present invention. In the fourth embodiment, the conductive via 3 b is formed on the surface layer of the conductive material layer 11 on the fuel cell 2 side. The conductive via 3b is provided so as to protrude toward the fuel cell 2 side. The conductive via 3 b electrically connects the conductive material layer 11 and the fuel battery cell 2.

In the fourth embodiment, even if delamination occurs between the conductive material layer 11 and the fuel cell 2, the conductive material layer 11, the metal layer 10, and the fuel cell 2 The electrical connection between the two can be maintained.

In the fourth embodiment, the conductive via 3b is formed in the surface layer of the conductive material layer 11. However, the conductive via 3b is connected to the conductive battery layer 11 from the fuel cell 2 side. It may be formed so as to reach the inside of the material layer 11.

FIG. 9 is a schematic front sectional view of a fuel cell stack according to a fifth embodiment of the present invention. In the fifth embodiment, the conductive via 3 a is formed on the surface layer of the conductive material layer 11 on the metal layer 10 side. The conductive via 3a is provided so as to protrude toward the metal layer 10 side. The conductive via 3 a electrically connects the conductive material layer 11 and the metal layer 10.

In the fifth embodiment, even if delamination occurs between the conductive material layer 11 and the metal layer 10, the conductive material layer 11, the metal layer 10, and the fuel cell 2 are separated from each other. The electrical connection between them can be maintained.

In the fifth embodiment, the conductive via 3 a is formed on the surface of the conductive material layer 11. However, the conductive via 3 a is connected to the conductive material layer 11 from the metal layer 10 side. It may be formed so as to reach the inside of the layer 11.

In the first to fifth embodiments, the conductive via 3 may be in contact with the surface of the metal layer 10 or in a state of being formed so as to reach the inside of the metal layer 10. Also good. Further, the conductive via 3 may be in contact with the surface of the fuel cell 2 or may be in a state of being formed so as to reach the inside of the fuel cell 2.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack 2 ... Fuel cell 2a ... Flow

path structure part

2b, 2c, 2d, 2e ... Electric

power generation part

3, 3a, 3b ... Conductive via 4 ... Joint part 5 ...

Separator

5a, 5b ... Through-hole 5c ... Inter Connector 6 ...

Fuel electrode layer

6a, 6b ... Slit 7 ... Solid

oxide electrolyte layer

7a, 7b ... Through hole 8 ...

Air electrode layer

8a, 8b ... Slit 9 ...

Separator

9a, 9b ... Through hole 9c ... Interconnector 10 ... Metal Layer 11 ... Conductive material layer 12 ... Adhesive layer 13 ... Spacers 14a, 14b ... Gaps

Claims

A solid oxide fuel cell stack having a structure in which a plurality of fuel cells are stacked,
A plurality of solid oxide fuel cells stacked;
In the portion where the fuel cells are stacked, a metal layer disposed between one of the fuel cells and the other fuel cell,
A conductive material layer disposed between the metal layer and the fuel cell so as to electrically connect the metal layer and the fuel cell;
The conductive material layer and at least one of the metal layer and the fuel battery cell are electrically connected between the conductive material layer and the metal layer and between the conductive material layer and the fuel battery cell. And a conductive via provided so as to be located in at least one of them.
2. The solid oxide fuel cell stack according to claim 1, wherein the conductive via protrudes from the conductive material layer at a power generation temperature of the fuel cell.
3. The solid oxide according to claim 1, wherein the conductive via penetrates the conductive material layer, and electrically connects the conductive material layer, the metal layer, and the fuel cell. Fuel cell stack.
The conductive via is formed on the metal layer side and the fuel cell side surface of the conductive material layer, and electrically connects the conductive material layer, the metal layer and the fuel cell. The solid oxide fuel cell stack according to claim 1 or 2.
The conductive via is formed so as to extend from the metal layer side and the fuel cell side of the conductive material layer to the inside of the conductive material layer, and the conductive material layer, the metal layer, and the fuel cell. The solid oxide fuel cell stack according to claim 1 or 2, wherein the cell is electrically connected to the cell.
The conductive via is formed in one surface layer of the conductive material layer on the metal layer side or the fuel battery cell side, and the conductive material layer, the metal layer, or the fuel battery cell. The solid oxide fuel cell stack according to claim 1 or 2, wherein one of them is electrically connected.
The conductive via is mainly composed of at least one metal selected from the group consisting of Pt, Pd, Ag, Au, Ru, Rh, Ni, Fe, Cr, and alloys mainly composed of these metals. 7. The solid oxide fuel cell stack according to any one of 1 to 6.