JP6130575B1 - Fuel cell stack - Google Patents

Abstract

A fuel cell stack capable of further improving power generation efficiency is provided. A fuel cell stack includes a pair of fuel cell cells and a plurality of current collecting members. Each fuel cell 301 has a plurality of power generating element portions 10 arranged at intervals in the longitudinal direction. Each current collecting member 302 is disposed between the pair of fuel cells 301 with a space therebetween in the width direction of the fuel cells 301. Each current collecting member 302 electrically connects a pair of fuel cells 301. [Selection] Figure 7

Description

  The present invention relates to a fuel cell stack.

  The fuel cell stack includes a fuel manifold and a plurality of fuel cells extending from the fuel manifold (Patent Document 1). Specifically, the fuel manifold has a plurality of insertion holes, and each fuel cell is inserted into the insertion hole. Each fuel cell is fixed to the fuel manifold using a bonding material. Each fuel cell is electrically connected through a current collecting member. The current collecting member is joined to each fuel cell through a joining material.

Japanese Patent No. 5551803

  In the fuel cell stack as described above, it is required to improve the power generation efficiency. Therefore, an object of the present invention is to provide a fuel cell stack that can further improve power generation efficiency.

  A fuel cell stack according to an aspect of the present invention includes a pair of fuel cells and a plurality of current collecting members. Each fuel cell has a gas flow path extending in the longitudinal direction. Each fuel cell has a plurality of power generation element portions arranged at intervals in the longitudinal direction. Each current collecting member is disposed in the width direction of the fuel cell with a space between the pair of fuel cells. Each current collecting member electrically connects a pair of fuel cells.

  Compared to a fuel cell stack in which a pair of fuel cells are electrically connected by one current collecting member, the joint area is the same when the pair of fuel cells are electrically connected by a plurality of current collecting members. However, the power generation efficiency can be improved. Specifically, the current flowing from one fuel cell to the other fuel cell can be dispersed in the width direction of the fuel cell by electrically connecting the pair of fuel cells by a plurality of current collecting members. it can. As a result, the resistance overvoltage in the fuel cell stack can be reduced and the power generation efficiency of the fuel cell stack can be improved.

  Preferably, the current collecting members are arranged at intervals from each other in the width direction of the fuel cell. In this case, in the width direction of the fuel cell, the ratio (W2 / W1) of the total value (W2) of the lengths of the plurality of current collecting members to the length (W1) of the fuel cell is 0.2-0. 8 is preferable.

  Thus, the power generation efficiency of the fuel cell stack can be further improved by setting the ratio “W2 / W1” to 0.2 to 0.8. Specifically, by setting the ratio “W2 / W1” to 0.2 or more, current concentration in each current collecting member is alleviated. As a result, since the increase in electrical resistance in each current collecting member is suppressed, the power generation efficiency of the fuel cell can be further improved. Further, by setting the ratio “W2 / W1” to 0.8 or less, air easily flows in the longitudinal direction of the fuel cell through the interval between the current collecting members, and the uneven temperature distribution is suppressed. As a result, an increase in electric resistance in the current collecting member can be suppressed, and the power generation efficiency of the fuel cell stack can be improved.

  At least a pair of adjacent current collecting members may be arranged so as to overlap in a longitudinal view of the fuel cell. In this case, in the width direction of the fuel cell, the ratio (L / W2) of the total value (L) of the overlapping portions of the current collecting members to the total value (W2) of the plurality of current collecting members is , Preferably less than 0.5.

  As described above, by arranging at least a pair of adjacent current collecting members so as to overlap, even if a failure occurs in one of the current collecting members, the electric resistance of the current collecting member increases. Can alleviate this. Moreover, the power generation performance can be improved by setting the ratio “L / W2” to less than 0.5.

  Preferably, the current collecting member is formed of a fired body of oxide ceramics.

  Preferably, the fuel cell stack further includes a manifold that distributes gas to each fuel cell. Each fuel cell extends upward from the top plate of the manifold.

  Preferably, the fuel cell stack further includes a gas supply member. The gas supply member is configured to supply gas between each current collecting member and the top plate of the manifold between the pair of fuel cells.

  According to the fuel cell stack of the present invention, the power generation efficiency can be further improved.

The perspective view of a fuel cell stack. Sectional drawing of a fuel cell stack. The perspective view of a fuel manifold. The perspective view of a fuel cell. Sectional drawing of a fuel cell. Sectional drawing of a fuel cell. The front view of a fuel cell stack. The figure which shows the junction part of a fuel cell and a fuel manifold. The figure which shows the gas supply method to a fuel cell stack. The figure which shows the manufacturing method of a fuel cell stack. The figure which shows the manufacturing method of a fuel cell stack. Sectional drawing of the fuel cell stack which concerns on a modification. Sectional drawing of the fuel cell stack which concerns on a modification. Sectional drawing of the fuel cell stack which concerns on a modification. Sectional drawing of the fuel cell stack which concerns on a modification. Sectional drawing of the fuel cell stack which concerns on a modification. The front view of the fuel cell stack which concerns on a comparative example.

  Hereinafter, embodiments of a fuel cell stack according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the fuel cell stack 100 includes a fuel manifold 200, a plurality of fuel cells 301, and a plurality of current collecting members 302.

  As shown in FIG. 3, the fuel manifold 200 is configured to distribute the fuel gas to the fuel cells 301. The fuel manifold 200 is hollow and has an internal space. Fuel gas is supplied to the internal space of the fuel manifold 200 through the introduction pipe 201. The fuel manifold 200 has a plurality of through holes 202 arranged along the first direction (z-axis direction). In the present embodiment, the longitudinal direction of the fuel manifold 200 extends along the first direction. Each through hole 202 is formed in the top plate 203 of the fuel manifold 200. Each through hole 202 communicates the internal space of the fuel manifold 200 with the outside.

  As shown in FIG. 2, each fuel cell 301 extends from the fuel manifold 200. Specifically, each fuel cell 301 extends upward (in the x-axis direction) from the top plate 203 of the fuel manifold 200. That is, the longitudinal direction of each fuel cell 301 extends upward.

  As shown in FIG. 4, the fuel battery cell 301 includes a plurality of power generation element units 10 and a support substrate 20. Each power generating element unit 10 is supported on both surfaces of the support substrate 20. Each power generation element unit 10 may be supported only on one side of the support substrate 20. The power generation element units 10 are arranged at intervals in the longitudinal direction of the fuel cell 301. That is, the fuel cell 301 according to the present embodiment is a so-called horizontal stripe fuel cell. The power generating element units 10 are electrically connected to each other by an electrical connection unit 30 (see FIG. 5).

  The support substrate 20 has a plurality of gas passages 21 extending in the longitudinal direction of the support substrate 20 inside. Each gas channel 21 extends substantially parallel to each other. As shown in FIG. 5, the support substrate 20 has a plurality of first recesses 22. Each first recess 22 is formed on both surfaces of the support substrate 20. The first recesses 22 are arranged at intervals in the longitudinal direction of the support substrate 20. Each first recess 22 is not formed at both ends of the support substrate 20 in the width direction (y-axis direction).

The support substrate 20 is made of a porous material that does not have electronic conductivity. The support substrate 20 can be made of, for example, CSZ (calcia stabilized zirconia). Alternatively, the support substrate 20 may be composed of NiO (nickel oxide) and YSZ (8YSZ) (yttria-stabilized zirconia), or composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria). Alternatively, MgO (magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel) may be used. The porosity of the support substrate 20 is, for example, about 20 to 60%.

  Each power generation element unit 10 includes a fuel electrode 4, an electrolyte 5, and an air electrode 6. Each power generation element unit 10 further includes a reaction preventing film 7. The fuel electrode 4 is a fired body made of a porous material having electron conductivity. The fuel electrode 4 includes a fuel electrode current collector 41 and a fuel electrode active part 42.

  The fuel electrode current collector 41 is disposed in the first recess 22. Specifically, the fuel electrode current collector 41 is filled in the first recess 22 and has the same outer shape as the first recess 22. Each fuel electrode current collector 41 has a second recess 41a and a third recess 41b. The anode active part 42 is disposed in the second recess 41a. Specifically, the fuel electrode active part 42 is filled in the second recess 41a.

The fuel electrode current collector 41 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, the fuel electrode current collector 41 may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). Also good. The thickness of the fuel electrode current collector 41 and the depth of the first recess 22 are about 50 to 500 μm.

  The fuel electrode active part 42 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, the fuel electrode active part 42 may be composed of NiO (nickel oxide) and GDC (gadolinium-doped ceria). The thickness of the fuel electrode active part 42 is 5 to 30 μm.

  The electrolyte 5 is disposed so as to cover the fuel electrode 4. Specifically, the electrolyte 5 extends in the longitudinal direction from one interconnector 31 to another interconnector 31. That is, the electrolyte 5 and the interconnector 31 are alternately arranged in the longitudinal direction of the fuel battery cell 301.

  The electrolyte 5 is a fired body made of a dense material having ionic conductivity and no electronic conductivity. The electrolyte 5 can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). Or the electrolyte 5 may be comprised from LSGM (lanthanum gallate). The thickness of the electrolyte 5 is, for example, about 3 to 50 μm.

The reaction preventing film 7 is a fired body made of a dense material and has substantially the same shape as the fuel electrode active portion 42 in a plan view. The reaction preventing film 7 is disposed at a position corresponding to the fuel electrode active part 42 through the electrolyte 5. The reaction preventing film 7 suppresses occurrence of a phenomenon in which YSZ in the electrolyte 5 and Sr in the air electrode 6 react to form a reaction layer having a large electric resistance at the interface between the electrolyte 5 and the air electrode 6. Is provided. The reaction preventing film 7 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 7 is, for example, about 3 to 50 μm.

The air electrode 6 is disposed on the reaction preventing film 7. The air electrode 6 is a fired body made of a porous material having electron conductivity. The air electrode 6 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode 6 has LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), or LSC = (La, Sr) CoO ₃ ( Lanthanum strontium cobaltite) or the like. The air electrode 6 may be composed of two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode 6 is, for example, 10 to 100 μm.

The electrical connection unit 30 is configured to electrically connect adjacent power generation element units 10. The electrical connection unit 30 includes an interconnector 31 and an air electrode current collector film 32. The interconnector 31 is disposed in the third recess 41b. Specifically, the interconnector 31 is embedded (filled) in the third recess 41b. The interconnector 31 is a fired body made of a dense material having electronic conductivity. The interconnector 31 can be made of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, the interconnector 31 may be made of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 31 is, for example, 10 to 100 μm.

  The air electrode current collector film 32 is disposed so as to extend between the interconnector 31 and the air electrode 6 of the adjacent power generation element units 10. For example, the air electrode current collector is configured to electrically connect the air electrode 6 of the power generation element unit 10 disposed on the left side of FIG. 5 and the interconnector 31 of the power generation element unit 10 disposed on the right side of FIG. A membrane 32 is disposed. The air electrode current collector film 32 is a fired body made of a porous material having electron conductivity.

The air electrode current collector film 32 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode current collector film 32 may be made of LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite). Or the air electrode current collection film | membrane 32 may be comprised from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 32 is, for example, about 50 to 500 μm.

  The fuel battery cell 301 configured as described above is electrically connected to adjacent fuel battery cells 301 by a plurality of current collecting members 302. As shown in FIG. 2, each current collecting member 302 is disposed between a pair of fuel cells 301. The current collecting member 302 electrically connects the fuel cells 301 adjacent in the thickness direction (z-axis direction). Specifically, the current collecting member 302 connects adjacent fuel cells 301 on the proximal end portion 303 side of the fuel cells 301. The current collecting member 302 is disposed on the proximal side of the power generation element portion 10 </ b> A located on the most proximal side (fuel manifold 200 side) among the plurality of power generation element portions 10. Specifically, as shown in FIG. 6, the current collecting member 302 is disposed on the air electrode current collecting film 32 extending from the power generating element portion 10 </ b> A located on the most proximal side. Note that “proximal” and “distal” indicate the positional relationship in the longitudinal direction of the fuel cell 301 with respect to the fuel manifold 200.

  As shown in FIG. 7, the respective current collecting members 302 arranged between the pair of fuel cells 301 are arranged at intervals from each other in the width direction (y-axis direction) of the fuel cells 301. The intervals between the current collecting members 302 may be equal intervals or may vary. In addition, it is only necessary that at least a pair of current collecting members 302 is disposed with a gap in the width direction among the current collecting members 302, and the adjacent current collecting members 302 are spaced from each other among the current collecting members 302. There may be things arranged without.

  The ratio (W2 / W1) of the total value W2 of the lengths (w1, w2,..., Wn) of the n current collecting members 302 to the length W1 of the fuel battery cell 301 in the width direction of the fuel battery cell 301. ) Is preferably 0.2 to 0.8. The length W1 of the fuel battery cell 301 in the width direction of the fuel battery cell 301 refers to a length measured along the width direction of the fuel battery cell 301. Further, the length wn of the current collecting member 302 in the width direction of the fuel battery cell 301 means a length measured along the width direction of the fuel battery cell 301. Although not particularly limited, the length W1 of the fuel cell 301 is preferably about 20 to 200 mm, and the length wn of each current collecting member 302 is about 1.0 to 20 mm. It is preferable. Moreover, it is preferable that the number n of each current collection member 302 arrange | positioned between a pair of fuel cell 301 is about 2-20 pieces, for example.

The current collecting member 302 has a block shape. For example, the current collecting member 302 has a rectangular parallelepiped shape or a cylindrical shape. In the present embodiment, the current collecting members 302 have the same size, but the current collecting members 302 may have different sizes. For example, the areas of the current collecting members 302 viewed along the first direction (z-axis direction) may be different from each other. The current collecting member 302 is made of, for example, a fired body of oxide ceramics. Examples of such oxide ceramics include perovskite oxide and spinel oxide. Examples of the perovskite oxide include (La, Sr) MnO ₃ , (La, Sr) (Co, Fe) O _{3, and the} like. Examples of the spinel oxide include (Mn, Co) ₃ O ₄ , (Mn, Fe) ₃ O _{4, and the} like. For example, the current collecting member 302 does not have flexibility.

The current collecting member 302 is joined to each fuel cell 301 by the first joining material 101. That is, the first bonding material 101 joins each current collecting member 302 and each fuel cell 301. The first bonding material 101 is, for example, at least one selected from the group consisting of (Mn, Co) ₃ O ₄ , (La, Sr) MnO _3, (La, Sr) (Co, Fe) O _{3, and the} like. .

  As shown in FIG. 2, each fuel cell 301 is supported by the fuel manifold 200. Specifically, each fuel cell 301 is fixed to the top plate 203 of the fuel manifold 200 by the second bonding material 102. More specifically, as shown in FIG. 8, each fuel cell 301 is inserted into the through hole 202 of the fuel manifold 200. The fuel cell 301 is fixed to the fuel manifold 200 by the second bonding material 102 in a state of being inserted into the through hole 202.

The second bonding material 102 is filled in the through hole 202 in a state where the fuel battery cell 301 is inserted. That is, the second bonding material 102 is filled in a gap between the outer peripheral surface of the fuel cell 301 and the wall surface that defines the through hole 202. The second bonding material 102 is, for example, crystallized glass. As the crystallized glass, for example, a SiO ₂ —B ₂ O ₃ system, a SiO ₂ —CaO system, or a SiO ₂ —MgO system may be employed. In this specification, crystallized glass means that the ratio (crystallinity) of “volume occupied by crystal phase” to the total volume is 60% or more, and “volume occupied by amorphous phase and impurities relative to the total volume”. "Indicates a glass having a ratio of less than 40%. As the material of the second bonding material 102, amorphous glass, brazing material, ceramics, or the like may be employed. Specifically, the second bonding material 102 is at least one selected from the group consisting of SiO ₂ —MgO—B ₂ O ₅ —Al ₂ O ₃ and SiO ₂ —MgO—Al ₂ O ₃ —ZnO. .

  The length of each fuel cell 301 protruding from the fuel manifold 200 in the longitudinal direction (x-axis direction) can be about 100 to 300 mm. Further, the fuel battery cells 301 are arranged at intervals in the first direction. The interval between the fuel cells 301 in the first direction can be about 1 to 5 mm.

The fuel cell stack 100 configured as described above generates power as follows. A fuel gas (hydrogen gas or the like) is caused to flow through the fuel manifold 200 into the fuel gas channel 21 of each fuel cell 301 and the both surfaces of the support substrate 20 are exposed to a gas (air or the like) containing oxygen, thereby allowing the electrolyte to flow. An electromotive force is generated due to the difference in oxygen partial pressure generated between the two side surfaces of 5. When this fuel cell stack 100 is connected to an external load, a chemical reaction represented by the following formula (1) occurs in the air electrode 6, a chemical reaction represented by the following formula (2) occurs in the fuel electrode 4, and a current flows.
(1/2) · O ₂ + 2e ⁻ → O ₂ ⁻ (1)
H ₂ + O ₂ ⁻ → H ₂ O + 2e ⁻ (2)

  For example, as shown in FIG. 9, the gas containing oxygen is supplied to the space between the current collecting member 302 and the fuel manifold 200 so as to flow along the width direction. Specifically, the fuel cell stack 100 further includes a gas supply member 400. The gas supply member 400 is configured to supply a gas such as air between the current collecting members 302 and the top plate 203 of the fuel manifold 200 between the fuel cells 301. Note that the guide plate 401 may be installed on the opposite side of the gas supply member 400 so that the gas supplied from the gas supply member 400 efficiently flows upward. The guide plate 401 has a flat plate shape and extends in the longitudinal direction of the fuel cell 301 and also extends in the thickness direction of the fuel cell 301.

  Next, a method for manufacturing the fuel cell stack configured as described above will be described.

  First, a fuel manifold 200 and a plurality of fuel cells 301 are prepared. Then, as shown in FIG. 10, each fuel battery cell 301 is connected by a current collecting member 302 and a first bonding material 101 to produce a cell assembly 300. At this stage, the first bonding material 101 is not fired, and the fuel cells 301 are temporarily attached to each other.

  Next, as shown in FIG. 11, the end of each fuel cell 301 of the cell assembly 300 is inserted into each through hole 202 of the fuel manifold 200. In addition, you may use the jig | tool for each fuel battery cell 301 holding a predetermined space | interval along a 1st direction.

  Next, as shown in FIG. 2, the second bonding material 102 is filled into the through hole 202 in a state where the fuel cell 301 is inserted. The second bonding material 102 is preferably filled to the extent that it protrudes upward from the surface of the support plate.

  Next, heat treatment is applied to the first bonding material 101 and the second bonding material 102. By this heat treatment, the first bonding material 101 and the second bonding material 102 are solidified, and the fuel cell stack 100 is completed. Specifically, the first bonding material 101 is fired by being subjected to heat treatment. As a result, each fuel cell 301 and the current collecting member 302 are fixed. Further, the second bonding material 102 is subjected to heat treatment, so that the temperature of the amorphous material reaches the crystallization temperature. Then, a crystal phase is generated inside the material at the crystallization temperature, and crystallization proceeds. As a result, the amorphous material is solidified and ceramicized to become crystallized glass. As a result, the second bonding material 102 made of crystallized glass functions, and the proximal end portion of each fuel cell 301 is fixed to the fuel manifold 200. Thereafter, a predetermined jig is removed from the fuel cell stack 100.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention.

Modification 1
For example, in the above embodiment, the current collecting members 302 are aligned along the width direction (y-axis direction), but there may be variations. As shown in FIG. 12, the adjacent current collecting members 302 may be arranged so as to overlap in the longitudinal direction of the fuel cell 301. In this case, in the width direction of the fuel cell 301, the sum of the lengths l1, l2,... Lm of the overlapping portions of the current collecting members 302 with respect to the total length (W2) of the plurality of current collecting members 302 The ratio (L / W2) of the value L (= l1 + l2 +... + Lm) is preferably less than 0.5.

Modification 2
As shown in FIG. 13, each current collecting member 302 may not be arranged in parallel to the width direction of the fuel cell 100. In this case, the length wn of each current collecting member in the width direction of the fuel cell 301 is measured by a dimension parallel to the width direction of the fuel cell 100.

Modification 3
It suffices that the current collecting members 302 that join at least the pair of fuel cells 301 are arranged at intervals in the width direction. For example, current collecting members that join some of the fuel cells 301 do not have to be spaced apart in the width direction.

Modification 4
In the said embodiment, although each current collection member 302 has connected the adjacent fuel battery cells 301 in the proximal end part 303 side of each fuel battery cell 301, a connection location is not limited to this. For example, as shown in FIG. 14, each current collecting member 302 may connect adjacent fuel cells 301 at the distal end 304 of each fuel cell 301.

Modification 5
In the above embodiment, all the power generation element portions 10 of each fuel battery cell 301 are connected in series, but may be connected in parallel. For example, as shown in FIG. 15, each power generation element portion 10 formed in the upper region R <b> 1 of each fuel cell 301 and each power generation element portion 10 formed in the lower region R <b> 2 of each fuel cell 301 are arranged in parallel. It may be connected to. In this case, each current collecting member 302 that electrically connects adjacent fuel cells 301 in the upper region R1 and each current collecting member 302 that electrically connects adjacent fuel cells 301 in the lower region R2 are formed. Has been.

  For example, at each of the proximal end portion 303 and the distal end portion 304 between the pair of fuel cells 301, each current collecting member 302 electrically connects the pair of fuel cells 301. And the front-back connection member 305 is provided in each of upper area | region R1 and lower area | region R2. The front-back connection member 305 electrically connects the power generation element portion 10 formed on one surface of the support substrate 20 and the power generation element portion 10 formed on the other surface of the support substrate 20.

  In addition, each power generation element part 10 may be connected in parallel by only some fuel battery cells 301, and each power generation element part 10 may be connected in series in other fuel battery cells 301.

Modification 6
As shown in FIG. 16, the power generation element units 10 of the fuel cells 301 may be connected in parallel. That is, each current collecting member 302 electrically connects adjacent fuel cells 301 at the center in the longitudinal direction (x-axis direction) of the fuel cells 301. A front-back connection member 305 is provided at each of the proximal end portion 303 and the distal end portion 304 of each fuel cell 301. Each front-back connection member 305 electrically connects the power generation element portion 10 formed on one surface of the support substrate 20 and the power generation element portion 10 formed on the other surface of the support substrate 20.

Modification 7
In the above-described embodiment, each current collecting member 302 is disposed on the air electrode current collecting film 32 extending from the power generation element unit 10, but the place where each current collecting member 302 is disposed is not limited thereto. For example, each current collecting member 302 may be disposed on the power generation element unit 10 or may be disposed on the interconnector 31. Thus, each current collecting member 302 may be disposed on any member as long as adjacent fuel cells 301 are electrically connected.

  The present invention will be described more specifically with reference to the following examples and comparative examples. In addition, this invention is not limited to the following Example.

[Test A]
(Example)
As an example, sample no. Fuel cell stacks according to 1 to 9 were produced as follows.

First, a pair of fuel cells 301 configured as described above were produced. Each fuel cell 301 has five power generation element portions 10 arranged at intervals in the longitudinal direction. Two to 20 current collecting members 302 are arranged between the fuel cells 301, and each current collecting member 302 is connected to each pair of the current collecting members 302 via (Mn, Co) ₃ O ₄ and (La, Sr) MnO ₃ . The fuel cell 301 was joined. The current collecting members 302 are arranged at intervals in the width direction of the fuel battery cell 301. The intervals between the current collecting members 302 were set to be approximately equal.

Each current collecting member 302 has a rectangular parallelepiped shape. Each current collecting member 302 was formed of (La, Sr) MnO ₃ . Table 1 shows the length W1 of the fuel cell 301 and the total length W2 of the current collectors 302 in each sample. The length W1 of the fuel cell 301 was measured in the width direction (y-axis direction) at the position where each current collecting member 302 was formed in the longitudinal direction. The length wn of each current collecting member 302 was measured in the width direction (y-axis direction) of the cross-sectional shape by cutting each current collecting member 302 at an arbitrary position in the thickness direction (z-axis direction). When the current collecting members 302 are not arranged in the width direction of the fuel cell 301, the length W1 of the fuel cell 301 is measured at an arbitrary position where at least one current collecting member 302 is formed. That's fine.

  In each sample, the configuration other than the length W1 in the width direction of the fuel cell 301 and the total value W2 of the length in the width direction of each current collecting member 302 is the same.

(Comparative example)
As a comparative example, a fuel cell stack 100 in which a pair of fuel cells 301 were connected by one current collecting member as shown in FIG. In addition, other configurations in the comparative example are the same as those of the samples of the examples.

(Evaluation method)
A 62 ° C. humidified hydrogen gas was supplied to each sample produced as described above through the fuel manifold 200. Further, air was supplied between the top plate 203 of the fuel manifold 200 and each current collecting member 302 along the width direction. And resistance overvoltage was measured in each sample, and each sample was evaluated. The evaluation results are shown in Table 1. In Table 1, a sample having a resistance overvoltage of 2.0 V or less is evaluated as “◯”, a sample having a resistance overvoltage of 2.1 to 2.9 V is evaluated as “Δ”, and a resistance overvoltage is 3.0 V. The above samples were evaluated as “x”. The evaluation conditions for each sample were as follows.
・ Atmosphere temperature: 750 ℃
Current density: 0.003 A / mm ² energized (Note that the current density is a value corresponding to the measurement result of the air electrode area of one power generation element portion 10 formed on the xy plane when viewed from the z-axis direction.)
-The resistance overvoltage of the entire pair of fuel cells 301 in each sample is measured.

  As shown in Table 1, the comparative example and sample No. When comparing with Example 4 of Example 4, it was found that, although W2 / W1 was the same, the Example had a lower resistance overvoltage than the Example. This is considered to be due to the following reason. That is, by disposing a plurality of current collecting members 302 at intervals in the width direction, the current flowing from one fuel cell 301 to the other fuel cell 301 is dispersed in the width direction of the fuel cell 301. Can do. As a result, it is considered that the resistance overvoltage of the fuel cell stack 100 is reduced. From this result, if the joint area is the same, the power generation efficiency of the fuel cell stack 100 is improved by dividing the current collectors 302 into a plurality of current collectors 302 and arranging the current collectors 302 at intervals in the width direction. I found out that I could do it.

  Sample No. 1 in Table 1 From the results of 3 to 9, it was found that the evaluation becomes “◯” by setting the ratio “W2 / W1” to 0.2 to 0.8. The reason that the evaluation becomes “◯” by setting the ratio “W2 / W1” to 0.2 or more is that the current concentration in each current collecting member 302 is alleviated and the electrical resistance in each current collecting member 302 is increased. This is considered to be suppressed. Further, the reason that the evaluation becomes “O” by setting the ratio “W2 / W1” to 0.8 or less is that air easily flows in the longitudinal direction of the fuel cell 301 through the interval between the current collecting members 302. This is considered to be because the bias of the temperature distribution is suppressed, and as a result, an increase in electrical resistance of each current collecting member 302 can be suppressed.

[Test B]
(Example)
As an example of the first modification, sample no. Fuel cell stacks according to 10 to 19 were produced as follows.

First, a pair of fuel cells 301 configured as described above were produced. Each fuel cell 301 has five power generation element portions 10 arranged at intervals in the longitudinal direction. 3 to 20 current collecting members 302 are arranged between the fuel cells 301, and each current collecting member 302 is connected to each pair of the current collecting members 302 via (Mn, Co) ₃ O ₄ and (La, Sr) MnO ₃ . The fuel cell 301 was joined. In each sample, at least a pair of adjacent current collecting members 302 are arranged so as to overlap in the longitudinal direction of the fuel cell 301 as shown in FIG.

Each current collecting member 302 has a rectangular parallelepiped shape. Each current collecting member 302 was formed of (La, Sr) MnO ₃ . Table 2 shows the total value W2 of the lengths of the respective current collecting members 302 in each sample and the total value L of the lengths of the overlapping portions. Note that the length wn of each current collecting member 302 and the length lm of the overlapping portion were measured by cutting each current collecting member 302 at an arbitrary position in the thickness direction (z-axis direction).

  In each sample, the configurations other than the total value W2 of the lengths of the current collecting members 302 in the width direction and the total value L of the lengths of the overlapping portions are the same.

(Evaluation method)
A 62 ° C. humidified hydrogen gas was supplied to each sample produced as described above through the fuel manifold 200. Further, air was supplied between the top plate 203 of the fuel manifold 200 and each current collecting member 302 along the width direction. And resistance overvoltage was measured in each sample, and each sample was evaluated. The evaluation results are shown in Table 2. In Table 2, samples having a resistance overvoltage of 1.3 V or less were evaluated as “◯”, and samples having a resistance overvoltage of 1.4 V to 2.0 V were evaluated as “Δ”. The evaluation conditions for each sample were as follows.
・ Atmosphere temperature: 750 ℃
Current density: 0.003 A / mm ² energized (Note that the current density is a value corresponding to the measurement result of the air electrode area of one power generation element portion 10 formed on the xy plane when viewed from the z-axis direction.)
-The resistance overvoltage of the entire pair of fuel cells 301 in each sample is measured.

  As shown in Table 2, it was found that when the ratio “L / W2” was less than 0.5, the evaluation was “◯”. This is because by setting the ratio “L / W2” to be less than 0.5, current concentration in each current collecting member 302 is alleviated and an increase in electrical resistance in each current collecting member 302 is suppressed. Conceivable.

10: Power generation element section 21: Gas flow path 100: Fuel cell stack 203: Top plate 301: Fuel cell 302: Current collecting member 400: Gas supply member

Claims (5)

A pair of fuel cells having a gas flow path extending in the longitudinal direction and a plurality of power generation element portions arranged at intervals in the longitudinal direction;
A plurality of current collecting members arranged in the width direction of the fuel cells with a space between the pair of fuel cells, and electrically connecting the pair of fuel cells,
Equipped with a,
At least a pair of adjacent current collecting members are arranged so as to overlap in a longitudinal view of the fuel cell,
Fuel cell stack. In the width direction of the fuel cell, the ratio (L / W2) of the total value (L) of the overlapping portions of the current collecting members to the total value (W2) of the plurality of current collecting members is , Less than 0.5,
The fuel cell stack according to claim 1 . The current collecting member is composed of a sintered body of oxide ceramics,
The fuel cell stack according to claim 1 or 2 . A manifold for distributing gas to each of the fuel cells,
Each of the fuel cells extends upward from the top plate of the manifold.
The fuel cell stack according to any one of claims 1 to 3 . A gas supply member configured to supply gas between each of the current collecting members and the top plate of the manifold between the pair of fuel cells;
The fuel cell stack according to claim 4 .

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