JP2008135195A - Cell stack, and fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cell stack that sufficiently supplies oxygen to an oxygen-electrode layer and achieves improvement in durability by suppressing current concentration while allowing sufficient securement of a junction area between a current-collecting member and the oxygen-electrode layer, and to provide a fuel battery. <P>SOLUTION: A plurality of cells 30 are arrayed at prescribed intervals so as to allow their flat face (A) to face each other. A current-collecting member 33 is arranged between the flat faces (A) of the cells 30 adjacent to each other. The current-collecting member 33 is joined to an oxygen-electrode layer 84 constituting the flat face (A) of one fuel-battery cell 30 and an inter-connector 85 constituting the flat face (A) of the other fuel-battery cell 30. The current-collecting member 33 is provided with a plurality of flat-plate like current-collecting pieces 33a on the oxygen-electrode side and a plurality of flat-plate like current-collecting pieces 33b on the inter-connector side respectively extending in a width direction of the cell 30. The current-collecting member is also provided with each connection part 33c, 33d to which both end parts of each current-collecting piece 33a on the oxygen-electrode side and those of each current-collecting piece 33b on the inter-connector side are respectively connected. Both end parts of each current-collecting piece 33a on the oxygen-electrode side are further externally extended than each oxygen-electrode layer 84. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cell stack and a fuel cell in which a plurality of hollow flat plate fuel cells are electrically connected by a current collecting member.

  In recent years, various fuel cells in which a fuel cell stack is accommodated in a storage container have been proposed as next-generation energy.

  The fuel cell stack described above is obtained by electrically connecting a plurality of adjacent fuel cells via a current collecting member. As such a current collecting member, an alloy having high electrical conductivity is employed, and since it is used at a high temperature, a heat resistant alloy is preferably employed.

  As for the shape of the current collecting member, as shown in FIG. 6A, a plurality of slits 81 are formed substantially in parallel at predetermined intervals on the right end of the rectangular plate, as shown in FIG. 6B. In this way, a flat current collecting piece 82 between the slits 81 is alternately projected on both sides of the plate current collecting member, and a plurality of current collecting pieces 82 are formed on the right side of the base 83. As shown in FIG. 7, a rectangular plate is formed by forming a plurality of slits substantially in parallel, and current collecting pieces 91 therebetween are alternately projected on both sides of the plate-like current collecting member. It is known that the current collecting piece group is formed with a predetermined interval in the length direction of the rectangular plate, and the base 92 and the current collecting piece 91 group are alternately formed (Patent Document 1, 2).

  For example, as shown in FIG. 8, such a current collecting member is accommodated between the hollow flat plate fuel cell 93, and a current collecting piece 82 of the current collecting member is joined to the fuel cell 93 to form a plurality of fuel cells. A cell stack is configured by electrically connecting the cells 93.

The fuel cell 93 has a flat surface on the opposite surface, and the flat surface is constituted by an oxygen electrode layer 93a and an interconnector 93b, and the current collecting member is disposed between adjacent fuel cells 93. One current collecting piece 82 of the current collecting member is housed in the oxygen electrode layer 93a of one fuel battery cell 93, and the other current collecting piece 82 of the current collecting member is connected to the interconnector 93b of the other fuel battery cell 93. Abutted and joined.
JP 2003-282101 A JP 2006-172742 A

  In the conventional cell stack shown in FIG. 8, in order to increase the amount of power generation, the oxygen electrode layer 93a tends to be formed as wide as possible to form a flat solid electrolyte layer of the hollow plate fuel cell 93. If the both ends of the current collecting member protrude outward from the width direction of the fuel cell, the end in the width direction of the current collecting member may come into contact with other members for some reason, and there is a risk that the insulation performance is reduced. As a result, the width of the current collecting member was made smaller than the width of the fuel battery cell 93.

  Accordingly, the flat plate-like current collecting piece 82 of the current collecting member can be joined only to a part of the oxygen electrode layer 93a, not the entire width direction of the oxygen electrode layer 93a, and when collecting current by the current collecting member, Current concentration occurs in the portion where the current collecting piece 82 of the current collecting member is joined, a partial temperature rise occurs in the oxygen electrode layer 93a, the deterioration of the oxygen electrode layer material proceeds, and the durability deteriorates. There was a problem.

  In addition, a base 83 that is not joined to the oxygen electrode layer 93a is present between the oxygen electrode layer 93a and the interconnector 93b that faces the oxygen electrode layer 93a, which inhibits the flow of air (oxygen) between the cells. Thus, there is a problem that sufficient oxygen cannot be supplied to the oxygen electrode layer 93a, and the power generation efficiency is low.

  An object of the present invention is to provide a cell stack and a fuel cell that can improve durability by suppressing current concentration and can sufficiently supply oxygen to an oxygen electrode layer.

  In the cell stack of the present invention, a plurality of hollow flat plate fuel cells are arranged at predetermined intervals so that the flat surfaces thereof face each other, and a current collecting member is disposed between the flat surfaces of the adjacent fuel cells. The current collecting member is bonded to the oxygen electrode layer constituting the flat surface of one of the fuel battery cells and the interconnector constituting the flat surface of the other fuel battery cell, and the plurality of fuel battery cells A plurality of plate-like oxygen electrode side current collecting pieces extending in the width direction of the fuel cell, and the width direction of the fuel cell. A plurality of planar interconnector-side current collecting pieces extending; and an oxygen electrode-side current collecting piece and a connecting portion to which both ends of the interconnector-side current collecting piece are connected, and the oxygen Both ends of the pole-side current collecting piece are the oxygen electrode layer Characterized in that it is extended to the remote outer.

  In such a cell stack, since both end portions of the oxygen electrode side current collecting piece are extended outside the oxygen electrode layer, it is possible to join the oxygen electrode side current collecting piece over the entire width direction of the oxygen electrode layer. The junction area between the current collecting member and the oxygen electrode layer is increased, and the current collecting member is joined to the oxygen electrode layer from the unjoined area where the current collecting member is not joined to the oxygen electrode layer. Can be shortened, and the current concentration of the cross-flow current in the oxygen electrode layer can be alleviated, whereby the durability deterioration due to the current concentration during power generation can be improved.

  Further, the connecting portion of the current collector is formed outside the oxygen electrode layer, and the oxygen-containing gas easily passes between the oxygen electrode layer and the interconnector, while the connecting portion, the oxygen electrode The oxygen-containing gas can be easily retained in the space formed by the side current collector piece and the interconnector side current collector piece, and the oxygen-containing gas can be sufficiently supplied to the oxygen electrode layer to improve power generation performance. Can do.

  The cell stack of the present invention is characterized in that the oxygen electrode layer is formed in the entire width direction of a flat solid electrolyte layer of the fuel cell. In such a cell stack, the power generation portion can be increased, and as described above, the oxygen-containing gas can be sufficiently supplied to the oxygen electrode layer, so that the power generation amount can be increased and the entire width direction of such an oxygen electrode layer can be increased. Since the oxygen electrode side current collecting pieces of the current collecting member are joined to each other, the current concentration of the transverse current in the oxygen electrode layer can be reduced.

  Furthermore, the cell stack of the present invention is characterized in that both end portions of the oxygen electrode side current collecting piece and the interconnector side current collecting piece are respectively extended outward from the fuel cell. In such a cell stack, both ends of the oxygen electrode side current collecting piece and the interconnector side current collecting piece are respectively extended outside the fuel cell, and the oxygen electrode side current collecting piece and the interconnector side current collecting piece Since the connecting portion is positioned outside the fuel cell, the distance that the oxygen electrode side current collecting piece and the interconnector side current collecting piece are not joined to the fuel cell can be increased, and the flexibility of the current collecting member can be increased. Can be improved. Thereby, since the deformation | transformation by the thermal expansion of a cell, etc. can be absorbed with a current collection member, it can be set as the cell stack excellent in connection reliability.

  Furthermore, in the cell stack of the present invention, the current collecting member is formed on a single alloy plate, and a plurality of slits are formed in parallel at a predetermined interval in the central portion of the alloy plate, and the alloy between adjacent slits. It is characterized by being formed by alternately protruding pieces on the opposite side.

  In such a cell stack, the current collecting member alternately protrudes the alloy pieces between the adjacent slits to the opposite side to form an oxygen electrode side current collecting piece and an interconnector side current collecting piece. An oxygen-containing gas passage can be formed between the side current collecting piece and the interconnector side current collecting piece, and oxygen can be easily and massively supplied to the oxygen electrode layer.

  The fuel cell of the present invention is characterized in that the cell stack is stored in a storage container. In such a fuel cell, durability deterioration due to current concentration during power generation in the cell stack can be improved, oxygen can be sufficiently supplied to the oxygen electrode layer, thereby improving the durability of the fuel cell, Power generation performance can be improved.

  In the cell stack of the present invention, the area of the junction between the current collecting member and the oxygen electrode layer is increased, and the current concentration of the transverse current in the oxygen electrode layer can be alleviated. Durability deterioration can be improved. Further, the oxygen-containing gas can be sufficiently supplied to the oxygen electrode layer, and the power generation performance can be improved.

  The fuel cell of the present invention can improve the durability deterioration due to current concentration at the time of power generation in the cell stack, thereby improving the durability of the fuel cell and sufficiently supplying oxygen to the oxygen electrode layer. The power generation performance of the fuel cell can be improved.

  FIG. 1 shows an embodiment of a cell stack device, and the cell stack device is configured by standingly fixing a cell stack 25 to a manifold 27. The cell stack 25 is configured by arranging a plurality of plate-like rod-shaped solid electrolyte fuel cells 30 having gas flow paths in the length direction.

  The fuel battery cell 30 has a flat cross section (hollow flat plate type) and an elongated substrate shape, and a plurality of gas flow paths are formed through the fuel cell 30 in the length direction. The fuel cell will be described later.

  The cell stack is configured by arranging the fuel battery cells 30 at predetermined intervals in the cell thickness direction so that the flat faces thereof are opposed to each other. A current collecting member 33 that electrically connects the cells 30 in series is disposed. The current collecting member 33 is joined to the oxygen electrode layer of one fuel battery cell 30 and to the interconnector of the other fuel battery cell 30.

  The lower end of the cell stack is embedded and fixed in a top plate 27 a made of an inorganic material that forms the upper surface of the manifold 27. The manifold 27 is connected to a gas supply pipe 35 that supplies gas into the manifold.

  As shown in FIG. 1B, the periphery of the cell stack is surrounded by an insulating heat insulating material 36, so that an oxygen-containing gas can be forcibly supplied to the cell stack side. The insulating heat insulating material 36 presses and fixes the current collecting member 33 from the measuring method.

  The fuel battery cell 30 used in the present invention will be described. As shown in FIG. 2, the fuel battery cell 30 has a hollow flat plate shape, a cross section is flat, and includes a porous support substrate (support) 81 having a rod shape and an elongated substrate shape as a whole. Inside the support substrate 81, six fuel gas passages 81a (forming gas passages) are formed penetrating in the length direction (axial length direction) at appropriate intervals. The support substrate 81 has a structure in which various members are provided. A plurality of such fuel battery cells 30 can be arranged in a line as shown in FIG. 1 to form a cell stack.

  The support substrate 81 includes a flat surface A and arcuate portions B at both ends of the flat surface A, and the flat surface A constitutes a main surface. The flat surfaces A on both sides are formed substantially parallel to each other, and a fuel electrode layer 82 is provided so as to cover one flat surface A and the arcuate portions B on both sides. A solid electrolyte layer 83 is laminated, and an oxygen electrode layer having the same width as the flat surface A is formed on one flat surface A so as to face the fuel electrode layer 82 on the solid electrolyte layer 83. 84 are laminated. The oxygen electrode layer 84 is not necessarily formed to have the same width as that of the flat surface A, but is desirably formed over the entire width of the flat surface A from the viewpoint of improving the power generation performance. In the solid electrolyte layer 83, the oxygen electrode layer 84, and the interconnector 85, the support substrate 81 has a flat shape reflecting the shape of the flat surface A. The fuel electrode layer 82 and the solid electrolyte layer 83 are continuously formed on one flat surface A in the gas flow path forming direction G.

  An interconnector 85 is formed on the flat surface A of the support substrate 81 on the other side where the fuel electrode layer 82 and the solid electrolyte layer 83 are not stacked. Similarly to the oxygen electrode layer 84, the interconnector 85 is also formed with the same width as the flat surface A. The interconnector 85 is not necessarily formed to the same width as the flat surface A, but is formed on the flat surface A so as to face the oxygen electrode layer 84 from the viewpoint of improving the current collecting performance. It is desirable. As is clear from FIG. 2, the fuel electrode layer 82 and the solid electrolyte layer 83 extend to both sides of the interconnector 85, and are configured so that the surface of the support substrate 81 is not exposed to the outside.

  In the fuel cell having the above structure, the portion of the fuel electrode layer 82 facing the oxygen electrode layer 84 operates as a fuel electrode to generate electric power. That is, an oxygen-containing gas such as air is allowed to flow outside the oxygen electrode layer 84, and a fuel gas (hydrogen) is supplied to the gas passage 81a in the support substrate 81, and the oxygen electrode layer 84 is heated to a predetermined operating temperature. Then, an electrode reaction of the following formula (1) is generated, and power is generated by generating an electrode reaction of the following formula (2), for example, in the portion that becomes the fuel electrode of the fuel electrode layer 82.

Oxygen electrode: 1 / 2O ₂ + 2e ⁻ → O ²⁻ (solid electrolyte) (1)
Fuel electrode: O ²⁻ (solid electrolyte) + H ₂ → H ₂ O + 2e ⁻ (2)
The current generated by such power generation is collected via an interconnector 85 attached to the support substrate 81.

  In the cell stack of the present invention, as shown in FIG. 3, the current collecting member 33 has a plurality of flat plate-like shapes extending in the width direction of the fuel cell 30, in other words, in the direction orthogonal to the gas flow path forming direction G. 3A and 3B, the oxygen electrode side current collecting piece 33a and the interconnector side current collecting piece 33b are provided with connecting portions 33c and 33d to which both ends thereof are connected. As described above, the flat oxygen electrode side current collecting piece 33a and the interconnector side current collecting piece 33b are formed by using a conductive material such as an oxygen electrode material for the flat oxygen electrode layer 84 and the interconnector 85 of the fuel cell 30. It is joined. Both end portions in the width direction of the oxygen electrode side current collecting pieces 33 a are extended outward from both ends in the width direction of the oxygen electrode layer 84.

  In other words, as shown in FIG. 3C, the current collecting member 33 includes the connecting portions 33c and 33d and the flat oxygen electrode side current collecting pieces 33a formed substantially parallel to the flat surface of the fuel cell. An inclined portion 33e is formed between the interconnector-side current collecting piece 33b, and both ends of the flat plate-like oxygen electrode-side current collecting piece 33a and the interconnector-side current collecting piece 33b in the width direction are oxygen electrode layers 84. The central portions of the flat plate-like oxygen electrode side current collecting piece 33a and the interconnector side current collecting piece 33b are located outside the both ends in the width direction of the fuel cell 30 as a flat surface (oxygen electrode layer 84, interconnector 85). The both ends are not joined to the fuel cell 30.

  As shown in FIG. 4, such a current collecting member 33 has a single rectangular plate-like alloy plate 41 with a plurality of slits 43 at the center of the alloy plate 41, in other words, the alloy plate 41 faces. A unit 45 formed in the center between both end portions and in parallel with a predetermined interval in the cell length direction, and formed by alternately protruding current collecting pieces 33a, 33b between adjacent slits 43 to the opposite side. Are connected together.

  Thereby, between the oxygen electrode side current collecting piece 33a, the interconnector side current collecting piece 33b, and the connecting portions 33c and 33d can be an oxygen-containing gas passage, and nothing exists in the oxygen-containing gas passage. Oxygen can be supplied to the polar layer 84 easily and in large quantities.

  Further, in such a cell stack, since both end portions of the oxygen electrode side current collecting piece 33 a are extended outward from the oxygen electrode layer 84, the oxygen electrode side current collecting piece extends over the entire width direction of the oxygen electrode layer 84. 33a can be joined, the area of the joined portion between the current collecting member 33 and the oxygen electrode layer 84 is increased, and the oxygen electrode side current collecting piece 33a is not joined to the oxygen electrode layer 84 until the unjoined portion. The distance can be shortened, and the current concentration of the transverse current in the oxygen electrode layer 84 can be alleviated, whereby the durability deterioration due to the current concentration during power generation can be improved.

  In the cell stack of the present invention, the oxygen electrode layer 84 is formed over the entire width direction of the flat solid electrolyte layer 83 of the fuel cell 30. In such a cell stack, the power generation portion can be increased, so that the power generation amount can be improved, and the oxygen electrode side current collecting piece 33a of the current collecting member 33 extends over the entire width direction of the oxygen electrode layer 84. Because of the bonding, the current concentration of the transverse current in the oxygen electrode layer 84 can be relaxed.

  FIG. 5 shows a cell stack according to another embodiment of the present invention, in which both ends of the flat oxygen electrode side current collecting piece 33 a and the interconnector side current collecting piece 33 b are extended outward from the fuel cell 30. Has been. In such a cell stack, the oxygen-containing gas supply path formed by the oxygen electrode-side current collecting piece 33a, the interconnector-side current collecting piece 33b, and the connecting portions 33c and 33d can be enlarged, which is sufficient for power generation. Oxygen can be supplied around the oxygen electrode layer 84, and the power generation efficiency can be improved.

  Further, both end portions in the width direction of the oxygen electrode side current collecting piece 33a and the interconnector side current collecting piece 33b are respectively extended outward from the fuel cell 30, and the oxygen electrode side current collecting piece 33a and the interconnector side current collecting piece are provided. Since the connecting portions 33c and 33d to the fuel cell 33 are located outside the fuel cell 33, the distance that the oxygen electrode side current collecting piece 33a and the interconnector side current collecting piece 33b are not joined to the fuel cell 30 is increased. It is possible to improve the flexibility of the current collecting member 33. Thereby, since the deformation | transformation by the thermal expansion of a cell, etc. can be absorbed, it can be set as the cell stack excellent in connection reliability.

  In addition, this invention is not limited to the said form, A various change is possible in the range which does not change the summary of invention.

  For example, in the above embodiment, the embodiment in which the fuel electrode layer 82 is provided on the support substrate 81 has been described. However, the fuel cell using the fuel electrode layer itself as a support without providing the support substrate 81 is similar to the above embodiment. An effect can be obtained. Moreover, although the said form demonstrated the case where the current collection member 33 as shown in FIG.3 (c) was used, in this invention, it is not limited to a current collection member as shown in FIG.3 (c).

  Furthermore, although the case where the interconnector-side current collecting piece 33b is joined to the interconnector 85 has been described in the above embodiment, for example, a P-type semiconductor layer made of an oxygen electrode material is provided in the interconnector, and the interconnector is provided on the P-type semiconductor layer. Even when the side current collecting pieces are joined, the same effect as in the above embodiment can be obtained.

1 shows an embodiment of a cell stack of the present invention, (a) a cross-sectional view showing a state in which the cell stack is erected on a manifold, and (b) is a side view of (a) as viewed from a measuring method. is there. The fuel cell is shown, (a) is a cross-sectional view, (b) is a vertical cross-sectional view. (A) is a top view of the cell stack of this invention, (b) is a side view which shows the state which the oxygen electrode side current collection piece has joined to the oxygen electrode layer, (c) is a perspective view of a current collection member. . It is a top view which shows the alloy plate for producing a current collection member. It is a top view which shows the state which the width direction both ends of the oxygen electrode side current collection piece and the interconnector side current collection piece are located outside the width | variety of a fuel cell. An example of the conventional current collection member is shown, (a) is a front view, (b) is a top view. It is a perspective view which shows the other example of the conventional current collection member. It is a top view which shows the state by which the current collection member of FIG. 6 is interposed between the fuel cells.

Explanation of symbols

30 ... Fuel cell 33 ... Current collecting member 33a ... Oxygen electrode side current collecting piece 33b ... Interconnector side current collecting piece 33c, 33d ... Connection part 41 ... Alloy plate 43 .... Slit 84 ... Oxygen electrode layer 85 ... Interconnector A ... Flat surface

Claims (5)

A plurality of hollow flat plate fuel cells are arranged at predetermined intervals so that the flat surfaces thereof are opposed to each other, a current collecting member is disposed between the flat surfaces of the adjacent fuel cells, and the current collecting members The oxygen electrode layer constituting the flat surface of one of the fuel cells and the interconnector constituting the flat surface of the other fuel cell, and electrically connecting the plurality of fuel cells. The current collecting member includes a plurality of plate-like oxygen electrode side current collecting pieces extending in the width direction of the fuel cell and a plurality of plate-like interfaces extending in the width direction of the fuel cell. A connector-side current collecting piece, and a connecting portion to which both ends of the oxygen electrode-side current collecting piece and the interconnector-side current collecting piece are connected, and both ends of the oxygen electrode-side current collecting piece Part extends outside the oxygen electrode layer Cell stack, characterized in that. The cell stack according to claim 1, wherein the oxygen electrode layer is formed in the entire width direction of the flat solid electrolyte layer of the fuel cell. 3. The cell stack according to claim 1, wherein both end portions of the oxygen electrode side current collecting piece and the interconnector side current collecting piece are extended outward from the fuel battery cell, respectively. The current collecting member is formed on a single alloy plate, and a plurality of slits are formed in parallel at a predetermined interval in the central portion of the alloy plate, and alloy pieces between adjacent slits are alternately projected to the opposite side. The cell stack according to claim 1, wherein the cell stack is formed. 5. A fuel cell comprising the cell stack according to claim 1 stored in a storage container.

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