JP5233128B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidizing gas.

  In recent years, fuel cells that generate electricity using an electrochemical reaction between hydrogen and oxygen have attracted attention as energy sources. For example, in a polymer electrolyte fuel cell which is a kind of fuel cell, a solid polymer electrolyte membrane may be referred to as a hydrogen electrode (hereinafter sometimes referred to as “anode”) and an oxygen electrode (hereinafter referred to as “cathode”). ) And sandwiched from both sides. One unit of such a fuel cell is called a “cell”.

  In a practical fuel cell, a stack (fuel cell stack) is formed by stacking a plurality of cells in order to obtain a necessary voltage. However, if the number of stacked layers is increased, the supply of fuel gas and oxidizing gas to each cell will vary. This is because gas supply to each cell is performed in parallel via the manifold, but the flow rate decreases downstream of the flow path. Further, when the number of stacked layers is large, it may be difficult to secure a mounting space when the fuel cell is mounted on a vehicle or the like. Therefore, the stack is configured to have a two-stage configuration by folding the stack in half.

  FIG. 6 is a schematic view showing a conventional fuel cell. The fuel cell 90 includes stacks 90a and 90b in which a plurality of cells 900 are stacked. The stacks 90a and 90b are electrically connected by a current collector plate 902 disposed at the upper end thereof. In addition, current collector plates 901 and 903 are disposed at the lower ends of the stacks 90a and 90b, respectively. The fuel cell 90 is connected to various power consuming devices (for example, motors), or inverters or DC-DC converters that supply power to the power consuming devices via these current collecting plates 901 and 903.

  By the way, in the stacks 90a and 90b, the current normally flows in the stacking direction of the cells 900 (vertical direction in the figure). On the other hand, in the current collector plates 901 to 903, the current flows in those planes (the horizontal direction in the figure). Therefore, as shown in FIG. 6, when the stacks 90 a and 90 b are connected to each other or other devices by the current collector plates 901 to 903, regions 911 to 913 in which the direction of current is rapidly changed are generated. This causes a problem that current concentrates in these regions 911 to 913 to generate heat.

Further, when the current is concentrated on a part, a current density distribution as shown by an arrow (current density vector) in FIG. 6 is generated. Therefore, the current density distribution is uneven in each cell constituting the stacks 90a and 90b, and the power generation efficiency varies. In particular, in the cells 900 near the upper and lower ends of the stacks 90a and 90b, the area where power is effectively generated is greatly reduced. Moreover, since the region where the power generation efficiency is relatively high (the region where the current density is high) in these cells 900 is close to the regions 911 to 913 where the current is concentrated, the power generation efficiency may be lowered due to the influence of heat generation. There is.
Thus, according to the conventional stack connection method, the performance of the fuel cell cannot be exhibited sufficiently.

  In addition, as shown in FIG. 7, the two stacks 90 a and 90 b may be connected by a current collector plate 920 in which a manifold through-hole 921 for supplying fuel gas and oxidizing gas to each cell 900 is formed. is there. In this case, since the range in which current can pass through the current collector plate 920 is narrowed, the variation in current density distribution becomes large as shown by the arrows in the figure.

  In addition, in the vicinity of the through-hole 921, the temperature change becomes large due to the influence of gas supply, so that it becomes more difficult to maintain the stability of the power generation performance of the cell 900 near the through-hole 921. That is, when the balance of the power generation environment is slightly changed, the cell voltage is easily lowered.

As a related technique, in order to make the current distribution at the end of the stacked fuel cell uniform, Patent Document 1 discloses providing a plurality of terminals on the current collector plate, and Patent Document 2 discloses a plurality of terminals. It is disclosed that the current terminal is provided on the periphery of the current collector plate.
JP 58-128675 A Japanese Utility Model Publication No. 62-48664

  Accordingly, an object of the present invention is to suppress heat generation of a current collector plate and variation in current density distribution in a fuel cell formed by connecting a plurality of stacks.

In order to achieve the above object, a fuel cell according to one aspect of the present invention includes a fuel cell stack including a plurality of cells each having an anode electrode and a cathode electrode formed on both sides of an electrolyte. In the fuel cells arranged in parallel in the orthogonal direction, each of the plurality of fuel cell stacks is formed of a current collector plate disposed at an end on the anode electrode side and an end on the cathode electrode side, and a conductive material, One or a plurality of pad portions arranged in a region excluding the peripheral edge of the current collector plate , and the peripheral edge of the current collector plate on the anode electrode side of one fuel cell stack of the fuel cell stack adjacent to each other, formed of a conductive material It said pad portion disposed in a region excluding, were bridged and the pad portion arranged in a region excluding the periphery of the cathode electrode side of the current collector plate of the other fuel cell stack 1 Or comprising a plurality of column portions, the, on each of the collector plate, the manifold is formed a plurality of through holes to be connected, the girder section, arranged so as to pass between the through hole adjacent to each other a fuel cell which has been.

With such a configuration, the current flowing from one fuel cell stack to the current collector plate flows into the pad portion while maintaining its direction in general, and after passing through the girder portion, from the other pad portion, its direction. Is generally maintained and flows into the other fuel cell stack. This makes it difficult for a current direction change in the current collector plate to occur, so that it is possible to suppress heat generation and variation in current density distribution due to current concentration. Further, each of the current collector plates is formed with a plurality of through holes to which a manifold is connected, and the beam portions are arranged so as to pass between adjacent through holes. Thereby, a plurality of fuel cell stacks can be connected without affecting the arrangement of the manifolds.

  The fuel cell includes one or a plurality of girders spanned over the pad portion provided on the current collector plate on the anode electrode side of the fuel cell stack located at one end in the substantially orthogonal direction; You may further provide the 1 or several girder part spanned over the said pad part provided in the collector plate by the side of the cathode electrode of the fuel cell stack located in the other end of the substantially orthogonal direction.

  By adopting such a configuration, even in the stacks located at both ends of the fuel cell stacks arranged side by side, it is possible to make it difficult for the current collector to suddenly change the direction of current. Variations in current density distribution can be suppressed.

Here, the current density distribution in the fuel cell stack can be prevented from being biased toward the end portions by arranging the one or more pad portions at substantially the center of each current collector plate.
Moreover, the current density distribution in the fuel cell stack can be made more uniform by arranging the plurality of pad portions in a distributed manner in the surface of each current collector plate.

  According to the present invention, since the two fuel cell stacks are electrically connected by the pad portion and the girder portion, the current is concentrated on a part of the current collector plate, thereby generating heat and variation in the current density distribution. Can be suppressed. Therefore, in the fuel cell, the power generation performance can be exhibited stably and sufficiently.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a schematic diagram showing a fuel cell according to a first embodiment of the present invention.
The fuel cell 10 shown in FIG. 1 is an in-vehicle power generation system for a fuel cell vehicle, a power generation system for any moving body such as a ship, an aircraft, a train, or a walking robot, and further as a power generation facility for a building (house, building, etc.). Although it is applicable to the stationary power generation system used, etc., in this embodiment, it is for automobiles.

  The fuel cell 10 includes two fuel cell stacks (hereinafter simply referred to as “stacks”) 10a and 10b. Each of the stacks 10a and 10b is formed by stacking a plurality of cells 1 including an electrolyte, an anode electrode arranged on one side thereof, and a cathode electrode arranged on the other side. Further, a current collector plate 11a is disposed on the anode electrode side (lower side in the figure) of the stack 10a, and a current collector plate 12a is disposed on the cathode electrode side (upper side in the figure). On the other hand, a current collector plate 11b is disposed on the anode electrode side (upper side in the figure) of the stack 10b, and a current collector plate 12b is disposed on the cathode electrode side (lower side in the figure).

  Each of the current collector plates 11a, 12a, 11b, and 12b is provided with two pad portions 101 made of a conductive material. Further, a girder 102 made of a conductive material is bridged over the pad 101 provided on the current collector plates 12a and 11b. Thereby, the stacks 10a and 10b are electrically connected.

  Further, a girder 103 formed of a conductive material is hung on the pad 101 provided on each of the current collector plates 11a and 12b. The fuel cell 10 is connected to an external device (for example, an inverter or a DC / DC converter that supplies power to a power consuming device such as a motor) through these girders 103. In FIG. 1, a state in which the beam portion 103 is connected to the electrode pad 15 is shown.

  The pad portion 101 may be provided by bonding a pad-shaped conductive material to the current collector plates 11a, 12a, 11b, and 12b. Alternatively, the pad portion 101 and the current collector plates 11a, 12a, 11b, and 12b may be provided. It may be formed integrally in advance. Similarly, the girder portions 102 and 103 may be provided by joining a bar-like or plate-like member to the pad portion 101, or both may be integrally formed in advance.

2A is a plan view showing the fuel cell 10 shown in FIG. 1, and FIG. 2B is a side view showing a part of the fuel cell 10.
The shape of the pad portion 101 may be an ellipse as shown in FIG. 2A, a circle, or any other shape. In any case, it is desirable to increase the contact area between the pad portion 101 and the current collector plates 12a and 11b as much as possible. From the viewpoint of the installation space of the fuel cell, as shown in FIG. 2B, the height h (the rising portion from the current collector plate) of the pad portion 101 and the girder portion 102 is as low as possible. It is desirable to make it flat as a whole. The height h may be about 1 mm to 2 mm, for example.

Such a pad part 101 is arrange | positioned in the area | region except the periphery of each collector plate 11a, 12a, 11b, 12b. This is to prevent the current density distribution from being biased to a part of the fuel cell stacks 10a and 10b (particularly the end portions). Specifically, as shown in FIG. 2, the distances d ₁ and d ₂ between the pad portion 101 and the end of the current collector plate 12a, and the distance d ₃ between the pad portions 101 are substantially equal. The two pad portions 101 may be dispersed, or the two pad portions 101 may be arranged substantially at the center of the current collector plate 12a. In FIG. 2, the two pad portions 101 are arranged on the left and right, but may be staggered to the left and right.

  Here, the pad part 101 should just be arrange | positioned at least 1 each at each current collecting plate 11a, 12a, 11b, 12b. For example, when only one pad portion 101 is provided, it is desirable to dispose it at the approximate center of each current collector plate. Further, when three or more pad portions 101 are provided, they are evenly distributed in the plane while avoiding the peripheral edge portion of each current collector plate, or arranged substantially in the center. In any case, the number and position of the pad portions 101 are not limited as long as the pad portions 101 are not biased and arranged in any region (particularly the peripheral portion) in the surface of the current collector plate.

FIG. 3 is a schematic diagram showing a current density distribution in the fuel cell 10. In addition, the arrow in a figure has shown the current density vector.
In the present embodiment, the pads 101 and the girders 102 and 103 are used to connect the stacks 10a and 10b or between the stacks 10a and 10b and another device, so that the current collector plates 11a, 12a, 11b, At 12b, there is no sudden turn of current. Therefore, it can suppress that an electric current concentrates on a part of current collector plates 11a, 12a, 11b, and 12b. Thereby, heat generation of the current collector plate can be suppressed, and a uniform current density distribution can be generated in the stacks 10a and 10b. As a result, variation in power generation efficiency in each cell 1 can be suppressed, and the performance of the fuel cell can be sufficiently exhibited.

Next, a fuel cell according to a second embodiment of the present invention will be described with reference to FIG.
In this embodiment, instead of the current collector plates 11a, 12a, 11b, and 12b shown in FIG. 1, a current collector plate 20 having a manifold through-hole 21 formed as shown in FIG. 4 is used. In this case, the girder 102 is disposed between the adjacent through holes 21 when the fuel cell is viewed from above so as not to block the through holes 21. The same applies to the digit portion 103.

  According to the present embodiment, by using the pad portion 101 and the girder portions 102 and 103, the stacks 10a and 10b can be connected without affecting the arrangement of the manifold. Further, by connecting in such a manner, variation in power generation efficiency within each cell 1 (FIG. 1) is suppressed, so that power generation performance can be improved even in a cell in the vicinity of the region where the manifold through holes 21 are concentrated. It becomes easy to maintain stability.

  When the fuel cells according to the first and second embodiments described above are mounted on a vehicle or the like, as shown in FIG. 5, the surfaces of the pad portion 101, the girder portion 102, and the current collector plates 12a and 11b After the insulating member 30 is disposed in the stack, the stacks 10a and 10b are stored in the case. As shown in FIG. 4, when using the current collector plate 20 provided with the through hole 21, the through hole is also formed at the corresponding position of the insulating member 30.

  In the above description, the fuel cell including two fuel cell stacks has been described. However, the present invention relates to a fuel cell in which three or more fuel cell stacks are arranged in parallel in a direction substantially perpendicular to the cell stacking direction. Can also be applied. That is, in the adjacent fuel cell stack, the current collector plate on the anode electrode side of one fuel cell stack and the current collector plate on the cathode electrode side of the other fuel cell stack are sequentially connected via the pad portion and the girder portion. Just do it.

1 is a schematic diagram showing a fuel cell according to a first embodiment of the present invention. It is the top view and side view which show the fuel cell shown in FIG. It is a figure which shows the current density distribution in the fuel cell shown in FIG. It is a top view which shows the fuel cell which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows a part of fuel cell by which the insulating member is arrange | positioned. It is a schematic diagram which shows the conventional fuel cell. It is a top view which shows the current collection board in which the through-hole for manifolds was formed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cell, 10a, 10b ... Fuel cell stack, 11a, 11b, 12a, 12b, 20 ... Current collecting plate, 21 ... Through-hole, 101 ... Pad part, 102, 103 ... Girder part

Claims (4)

In a fuel cell in which a plurality of fuel cell stacks each including a plurality of cells each formed with an anode electrode and a cathode electrode on both sides of an electrolyte are arranged in a direction substantially perpendicular to the stacking direction of the cells,
A current collector plate disposed at an anode electrode side end and a cathode electrode side end of each of the plurality of fuel cell stacks;
One or a plurality of pad portions formed of a conductive material and disposed in a region excluding the peripheral edge of the current collector plate;
The pad portion formed of a conductive material and disposed in a region excluding the peripheral edge of the current collector plate on the anode electrode side of one fuel cell stack of fuel cell stacks adjacent to each other, and on the cathode electrode side of the other fuel cell stack One or a plurality of girders that span the pad portion disposed in the region excluding the peripheral edge of the current collector plate ,
Each of the current collector plates is formed with a plurality of through holes to which a manifold is connected,
The said beam part is a fuel cell arrange | positioned so that it may pass between the mutually adjacent through-holes . One or a plurality of girders disposed on the pad portion provided on the current collector plate on the anode electrode side of the fuel cell stack located at one end in the substantially orthogonal direction;
One or a plurality of girders disposed on the pad portion provided on the current collector plate on the cathode electrode side of the fuel cell stack located at the other end in the substantially orthogonal direction;
The fuel cell according to claim 1, further comprising: The one or more pad portions are arranged at substantially the center of each current collector plate.
The fuel cell as described. 3. The fuel cell according to claim 1, wherein the plurality of pad portions are arranged in a distributed manner in a surface of each current collecting plate.

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