JPH0850903A - Solid polymer type fuel cell - Google Patents

Abstract

PURPOSE:To provide the structure of a compact solid polymer type fuel cell. CONSTITUTION:A pair of gas separating members 6 and 7 nippedly holding a power generation element 5 are provided with protruded parts 6a and 7a, alternately protruded in a direction vertical to a direction in which the power generation element 5 is extendedly provided, to nippedly hold the power generation element 5 by pushing the protruded parts 6a and 7a with each other to the surfaces 6b and 7b of the other side gas separating members. The power generating element 5 is extended in a zigzag in the extendedly provided direction of the gas separating members 6 and 7. Spaces 8 and 9, demarcated by the power generation element 5 obliquely extending and the respective gas separating members 6 and 7, constitute a gas passage for a fuel gas, that is, cathode side gas or an oxidant gas, that is, cathode side gas.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell is generally a power generating element, that is, a solid electrolyte fuel cell constructed by sandwiching a hydrogen ion conductive solid polymer between carbon electrodes carrying a platinum catalyst. It has a structure in which a molecule-electrode assembly and gas passages for supplying respective reaction gases to the respective electrode surfaces are defined and a gas separation member supporting the power generation element from both sides is laminated. Then, the fuel gas is supplied to one electrode, the oxidant gas is supplied to the other electrode, and the energy is extracted by directly converting the chemical energy involved in the oxidation of the fuel gas into electric energy. . By the way, in the polymer electrolyte fuel cell, when the number of stacked layers of one cell structure, that is, one cell structure composed of one power generation element and a pair of gas separation members forming a gas passage is increased, the voltage is increased. The current generated by increasing the effective reaction area of one cell increases. It is desired to achieve a high output of the cell while achieving a compact polymer electrolyte fuel cell. Although it has been proposed to reduce the thickness of the gas separation member in order to reduce the thickness of one layer of the cell in order to achieve compactness, the mechanical strength of the laminated structure of the battery is reduced. If the area of the power generation element supporting portion of the gas separation member is reduced in order to increase the effective reaction area, the following problems occur. That is, the gas separating member also functions as a current collecting member for recovering the electric energy generated through the polymer electrolyte membrane by coming into contact with the electrode surface, but if the contact area is too small, the current collecting resistance increases. Then
On the contrary, there arises a problem that energy efficiency is lowered.

Further, in the polymer electrolyte fuel cell, the fuel gas and the oxidant gas are oxidized in an ionized state, and the chemical energy at this time is taken out. In this case, the fuel gas is used. Is hydrogen and the oxidant gas is oxygen or air. The polymer electrolyte fuel cell has a structure in which this gas is opposed to each other via a power generation element, and these gases are allowed to flow from the main passage to each cell having a thin layer structure. As described above, in the polymer electrolyte fuel cell, it is necessary to maintain the non-contact state in the state where the fuel gas and the oxidant gas are extremely close to each other, and it is necessary to have a highly accurate sealing property in order to prevent the mixed state of both gases. To be done. In order to secure this sealing property, conventionally, a seal member is arranged in a manifold for distributing each fuel gas and an oxidant gas from each main passage to each cell, and the seal member is pressed against the gas separation member. The fuel gas and the oxidant gas are prevented from being mixed with each other. However, in such a sealing method, nonuniform stress is generated in the gas separation member, and the gas separation member that thins the gas separation member is deformed, so that the sealing performance cannot be maintained.

The present invention has been constructed in view of the above circumstances, and an object thereof is to provide a compact structure of a polymer electrolyte fuel cell while solving the above problems. Another object of the present invention is to provide a structure of a polymer electrolyte fuel cell capable of improving the sealing property of gas, cooling water, etc. flowing in the cell with a relatively simple structure.

[0005]

In order to achieve the above object, the present invention is configured as follows. That is, the polymer electrolyte fuel cell of the present invention comprises a power generating element in which electrode constituent members are arranged on both sides of a polymer electrolyte membrane, and a power generating element extending from both sides of the power generating element member and supported from both sides, and each of the electrodes. In a polymer electrolyte fuel cell configured by stacking a structure including a pair of gas separation members that define a passage of each reaction gas involved in the power generation element from the side of the constituent members,
A pair of gas separation members facing each other with the power generation element interposed therebetween have a protrusion that protrudes in a direction substantially perpendicular to the extending direction of the power generation element to form the reaction gas passage, and the protrusion Is provided so as to alternately project from both sides of the power generating element, and the power generating element is supported by the projecting portion so as to extend in a zigzag shape. The reaction gas passage is defined. In one preferable aspect, the protrusion is provided discontinuously in a lateral direction with respect to the extending direction of the power generation element. That is, each of the protrusions extends as a columnar protrusion and sandwiches and supports the power generation element between the protrusions and the surface of the other gas separation member.

Further, according to another feature of the present invention, a power generating element in which electrode constituent members are arranged on both sides of a polymer electrolyte membrane,
Power generation including a pair of gas separation members extending across the power generating element member, supporting the power generating element member from both sides, and defining passages of respective reaction gases involved in the power generating element from the respective electrode component members side. In a polymer electrolyte fuel cell configured by stacking cell structures, the polymer electrolyte membrane is disposed in a portion extending beyond the electrode constituent member, and the peripheral edge portion of the electrode constituent member faces the electrode constituent member. Further provided is a frame having at least a gas manifold that supports the reaction gas from the main gas passage and distributes the reaction gas from the main gas passage to the gas passages of the power generation cell structures, and the power generation element and the frame are bonded to each other. It is characterized by that. In this case, preferably, the contact portion between the polymer electrolyte membrane and the frame is bonded with an adhesive. In still another aspect, the contact portion between the polymer electrolyte fuel cell and the frame is heat-bonded to ensure the sealing property of the reaction gas.

[0007] In still another embodiment, a gas separation member that extends from both sides of the power generating element member, supports the power generating element member from both sides, and defines passages of respective reaction gases involved in the power generating element from the side of the respective electrode component members. A member is provided, and the polymer electrolyte membrane and the gas separation member are joined together. Further, according to another feature of the present invention, a power generating element in which electrode constituent members are arranged on both sides of a polymer electrolyte membrane, and extending from both sides of the power generating element member and supporting the power generating element member, and the respective electrode configurations. In a polymer electrolyte fuel cell constituted by stacking a power generation cell structure including a pair of gas separation members defining respective reaction gas passages involved in a power generation element from the member side, an electrode constituent member A frame disposed around the electrode constituent member so as to be flush with the electrode constituent member is further provided in the peripheral portion of the power generation element in which the polymer electrolyte membrane extends beyond the polyelectrolyte membrane. Are arranged on both sides of the polymer electrolyte membrane, and at least one of the frames has a joint surface with the gas separation member,
The coating material is arranged. The frame is preferably a gasket with a core material in which a core material such as metal, phenol resin, epoxy resin is arranged,
The electrode component is disposed in an electrode region of the electrode component, that is, in a peripheral region beyond the active region to support the electrode component.

The coating material is, for example, N
BR, fluororubber, silicone rubber, PTFE, etc. may be mentioned.

[0009]

In the structure of the present invention, the polymer electrolyte fuel cell is constructed by stacking cells including a power generating element and a gas separating member supporting the power generating element from both sides. A main passage for supplying the fuel gas, the oxidant gas, and the cooling water to the respective cells is provided in a direction that penetrates the cells in the stacked state. The main passage is provided around the cell,
It is provided in the frame area that supports it. And
Since the main passage needs to be paired with the supply passage and the return passage, at least six through holes are formed on the frame. Further, in the present invention, the pair of gas separation members that sandwich the power generation element are provided with the protruding portions that alternately project in the direction perpendicular to the direction in which the power generation element extends. The protrusion holds the power generating element by pressing the power generating element against the surface of the other gas separating member. Therefore, the power generation element is
It extends obliquely from the surface of one gas separation member toward the surface of the other gas separation member, and is pressed against and supported by the surface of the gas separation member by the protrusions, and then extends diagonally in the opposite direction. On the surface of one gas separation member,
The other gas separating member is pressed by the protruding portion. In this way, the power generation element extends in the zigzag extending direction of the gas separation members while contacting the surfaces of the pair of gas separation members at predetermined intervals.

The space defined by the obliquely extending power generation element and each gas separation member constitutes a gas passage for the fuel gas or the oxidant gas. In this way, the power generating elements are arranged in a zigzag shape while forming the gas passage between the pair of gas separating members in this way, so that the power generating elements arranged per unit length in the extending direction of the gas separating members are zigzag. The length of the power generation element is increased as much as the shape of the power generation element is increased. That is, the output density with respect to the extended length of the gas separation member can be increased. Further, according to another feature of the present example, the structure for introducing gas from the main passage into the gas passage of each cell is such that the branch portion from the main passage, that is, the manifold, has a power generating element for sealing the gas. Since the adhering means for adhering the polymer electrolyte membrane to the frame is provided, it is possible to effectively prevent the fuel gas, the oxidant gas, and the cooling water from being mixed with each other through the surface of the frame.

[0011]

Embodiments of the present invention will be described below. FIG. 1 is a schematic sectional view showing a main part of a polymer electrolyte fuel cell according to one embodiment of the present invention, and FIG. 2 schematically shows one cell of the polymer electrolyte fuel cell of FIG. It is a perspective view. The cell 1 of the polymer electrolyte fuel cell of the present example is arranged on both sides of the polymer electrolyte membrane 2 which carries the reaction ions and causes the movement of the reaction ions to cause the reaction. It is configured by stacking a battery constituent body, that is, a cell, which includes a power generation element 5 including the electrode constituent members 3 and 4, and gas separation members 6 and 7 that sandwich the power generation element 5 from both sides. The electrodes are bonded to the polymer electrolyte membrane on both sides using a hot pressing method or the like. The gas separation members 6 and 7 are made of an electrically conductive and airtight material such as amorphous carbon. In the present invention, the pair of gas separation members 6 and 7 that sandwich the power generation element 5 therebetween.
Is provided with projecting portions 6a and 7a which alternately project in the direction perpendicular to the direction in which the power generation element 5 is extended. The protrusions 6a and 7a hold the power generating element 5 by pressing the power generating element 5 against the surfaces 6b and 7b of the other gas separating member. Therefore, the power generation element 5 extends obliquely from the surface 6b of the one gas separation member 6 toward the surface 7b of the other gas separation member, and is pressed against and supported by the surface 7b of the gas separation member 7 by the protrusion 6a, After this, this time, the projections 7a of the other gas separation member 7 are formed on the surface of the one gas separation member 6b extending diagonally in the opposite direction.
To force it. As described above, the power generation element 5 extends in the zigzag-shaped extending direction of the gas separation members 6 and 7 while contacting the surfaces 6b and 7b of the pair of gas separation members 6 and 7 at predetermined intervals.

Spaces 8 and 9 defined by the obliquely extending power generating element 5 and the gas separating members 6 and 7 constitute gas passages for fuel gas, that is, cathode side gas or oxidant gas, that is, cathode side gas. To do. Referring to FIG.
In the structure described above, a plan view of the gas separating member 6 is shown, and the protrusion 6a extends so as to form a rib in a direction transverse to the extending direction of the gas separating member 6. As described above, in this example, the power generation element 5 is arranged three-dimensionally, and the gas passages 8 and 9 are formed between the pair of gas separation members 6 and 7, so that the gas separation members 6 and 7 are arranged. The power generating elements 5 arranged per unit length in the extending direction of 7 are lengthened by the zigzag shape, so that the effective reaction area of the power generating elements 5 is increased. That is, the power density with respect to the extended length of the gas separation members 6 and 7 can be increased. 4 and 5, the structure of the cell 1 according to another embodiment of the present invention is shown. In the configuration of this example, the protrusion 6a extends laterally in a discontinuous state.
That is, each of the protruding portions independently extends in a columnar shape and reaches the surface of the other gas separating member.

With this structure, the effective reaction area of the power generating element can be further increased, and the size reduction can be promoted. However, in this case,
Compared with the structure of the previous example, the contact area with the power generation element 5 at the tops of the protrusions 6a and 7a tends to decrease, so that the distance between the protrusions and the size of the protrusions can be increased so that a predetermined required contact area of the protrusions can be secured. It is necessary to set the number, etc. The structure of the peripheral portion of the power generation element will be described with reference to FIGS. 6, 7 and 8. As described above, the polymer electrolyte fuel cell of this example is configured by stacking the cells 1 including the power generation element 5 and the gas separation members 6 and 7 that support the power generation element 5 from both sides. As shown in FIG. 6 and FIG. 7, the power generation element forming a part of the stacked cells 1 has a rectangular shape when seen in a plan view, and the rectangular power generation element 5 is supported around the power generation element. A rectangular frame 10 having a rectangular shape is arranged. Further, a main passage 17 for supplying the fuel gas oxidant gas and the cooling water to each cell is provided in a direction that penetrates the cells in the stacked state. The main passage 17 is provided around the cell and is provided in a frame region that supports the cell. Since the main passage needs to be paired with the supply passage and the return passage, at least six through holes 11,
12, 13, 14, 15 and 16 will be formed on the frame 10. In this example, there are provided through-holes 11, 12 and 13, 14 which form a part of a pair of main passages through which hydrogen as a fuel gas and air as an oxidant gas flow. Further, through holes 15 and 16 for the cooling water passage are provided.

Since the introduction portion from the main passage toward each cell has the same structure for the oxidizing gas and the cooling water, the structure of the introduction portion for the fuel gas will be described below as a representative. A detailed description of those items is omitted. FIG. 8 shows a cross-sectional view of the main passage 17 and the manifold 18 of the fuel gas of the polymer electrolyte fuel cell of this example, in which the gas is passed from the main passage 17 to the fuel gas passage 8 of each cell. The structure to be introduced, that is, the branch portion from the main passage 17, that is, the manifold 18, has a seal portion for adhering the polymer electrolyte membrane of the power generation element to the frame 10 in order to seal gas. The seal portion 19 is provided in a rectangular shape so as to cover the periphery of the through hole 11 in FIG. The power generation element 5 including the electrodes 3 and 4 and the polymer electrolyte membrane 2 is sandwiched between the pair of gas separation members 6 and 7. At the end of the electrode 4, notches 6c and 7c are provided in the gas separating members 6 and 7 on one electrode side so as to be substantially flush with the edge of the electrode 3. Below the cutout 7, there is provided a space for an inlet, that is, a manifold 18 for introducing gas from the main passage 17. The intermediate layer of the power generation element 5, that is, the polymer electrolyte membrane layer 2 extends to the position of the main passage 17. On the other gas separation member side 6, a frame 10 is interposed between the peripheral edge of the electrode 3 and the main passage 17. In this way, in the introduction portion from the main passage 17 to the electrode surface of each power generation element 5, the gas introduction electrode 4 side is provided with the polymer electrolyte membrane 2 in which the manifold 18 is formed and the gas separation member. Voids are inevitably formed between them. Conventionally, the seal member 20 is sandwiched in this portion to prevent the polymer electrolyte membrane 2 from being separated from the other gas separation member 6. Otherwise, the other gas separating member 6 and the frame 1
A manifold (not shown) for introducing another gas (oxidant gas) to the other electrode surface at another position that is displaced in a plane is provided between 0 and 0, and another manifold is provided via this manifold. This is because there is a risk that the gas of (2) may leak into the main passage 17 through the gap between the frame 10 and the gas separating member 6 and mix with each other.

However, the seal member 2 is attached to the manifold 18.
In the structure in which 0 is arranged, pressure is applied to the gas separating members 6 and 7, so that it is necessary to give rigidity to the gas separating members 6 and 7. If the rigidity is insufficient, this deforms and gas leakage occurs. There was a problem that it could not be prevented.
Further, in order to secure the rigidity, the thickness of the gas separation member is increased, so that there is a problem that the polymer electrolyte fuel cell becomes thick as a whole. In the structure of this example, in view of this problem,
The frame 10, the power generating element 5 (polymer electrolyte membrane 2), and the frame 1 are provided at corresponding positions of the manifold 18.
0 and the gas separation member 6 are configured to adhere to each other. For the adhesion between the electrolytic membrane 2 and the frame, thermocompression bonding is effective when the frame is a polymer member. Further, as shown in FIG. 9, an adhesive 21 may be arranged between the polymer electrolyte membrane 2 and the frame 10 and the both may be adhered by the adhesive to ensure the sealing property. As the adhesive, for example, phenol resin, epoxy resin, metal, NBR, fluororubber or the like can be used. As described above, in the structure of this example, since the bonding means is provided in the region of the manifold in the peripheral portion of the gas separation member 7 and the power generation element 5,
It is possible to effectively prevent the fuel gas, the oxidant gas, and the cooling water from entering a mixed state via the surface of the frame.

Referring to FIGS. 10, 11 and 12,
Yet another embodiment of the invention is shown. The frame of this example is arranged on both sides so as to sandwich the polymer electrolyte membrane 2, and is arranged in a portion where the polymer electrolyte membrane 2 extends beyond the active region defined by the electrode constituting members 3 and 4. In this case, since the frame 10 is configured to have substantially the same thickness as the electrode constituent members 3 and 4, the portion of the portion functioning as the power generation element 5 including the electrode constituent members 3 and 4 in the central portion and the polymer electrolyte membrane 2 is formed. The surrounding frame 10 and the portion including the polymer electrolyte membrane 2 have almost the same thickness. Therefore, since the structure sandwiched between the gas separation members 6 and 7 has almost the same thickness from the active portion to the peripheral portion, the structure sandwiched between the gas separation members 6 and 7 from both sides is supported. Is clamped with uniform pressure over the entire surface. This makes it possible to make the adhesion between the gas separation members 6 and 7 and the power generation element (polymer electrolyte membrane-electrode component member assembly) and the frame-polymer electrolyte membrane assembly uniform, and the gas from the gas passages. Helps prevent leaks. In the configuration of this example, three parallel grooves 22 are provided in the gas separation member, and when the frame-polymer electrolyte membrane assembly and the gas separation member are joined, the main passage and the gas passage in the active region are connected. A gas passage is formed. By branching from the main passage with a plurality of elongated gas passages, the tightening force between the gas separation member at the branched portion and the frame-polymer electrolyte membrane assembly can be reduced, so that the single manifold can be used. As compared with the branched structure, it is possible to obtain better adhesion between the frame-polymer electrolyte membrane assembly and the gas separation member at the branch portion from the main passage.

Further, in the structure of this embodiment, a coating material is applied to the joint surface of the frame 10 with the gas separating members 6 and 7, whereby the frame-polymer electrolyte membrane assembly is made into the gas separating member 6. , 7 are joined together to form a power generation cell, there is an effect of enhancing the adhesion between the two. As a result, gas leakage from the gas passage can be effectively prevented.

[0018]

As described above, according to one feature of the present invention, the arrangement structure of the power generating elements is three-dimensionally arranged in a zigzag shape, so that the effective reaction area is increased and the solid height is increased. The molecular fuel cell can be downsized. Also,
It is possible to effectively prevent mixing of the fuel gas and the oxidant gas in the manifold region with a simple configuration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a single-layer cell of a polymer electrolyte fuel cell according to an embodiment of the present invention,

2 is a perspective view showing a layout of a power generation element of the cell of FIG.

3 is a partial plan view of the gas separation member of FIG.

FIG. 4 is a perspective view of a cell according to another embodiment of the present invention,

5 is a plan view of the cell in the embodiment of FIG. 4,

FIG. 6 is a plan view showing the mechanism of the periphery of the cell of the polymer electrolyte fuel cell,

7 is a partial cross-sectional view showing a peripheral portion of the polymer electrolyte fuel cell of FIG. 6,

FIG. 8 is an exploded perspective view showing a laminated state of the power generating element,

FIG. 9 is a partial cross-sectional view showing another example of the bonding structure of the peripheral portion of the cell.

FIG. 10 is a partial plan view of the cell showing the periphery of the gas main passage,

11 is a cross-sectional view taken along the line AA of FIG.

12 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

1 cell, 2 polymer electrolyte membrane, 3, 4 electrode, 5 power generating element, 6 and 7 gas separating member, 8 and 9 gas passage, 10 frame, 11, 12, 13, 14, 15, 16 gas and cooling water Through hole. 17 main passages, 22 grooves.

Claims (7)

[Claims] 1. A power generating element in which electrode constituent members are arranged on both sides of a polymer electrolyte membrane, and extending from both sides of the power generating element member to support the power generating element member, and a power generating element from each of the electrode constituent member sides. In a polymer electrolyte fuel cell constituted by stacking a power generation cell structure including a pair of gas separation members that define respective reaction gas passages involved, a pair of fuel cell elements facing each other with the power generation element sandwiched therebetween. The gas separation member has a protrusion that protrudes in a direction substantially perpendicular to the extending direction of the power generating element to form the reaction gas passage, and the protrusions alternate with respect to the power generating element from both sides thereof. The power generation element is provided so as to project in the direction of the zigzag by the projecting portion, and the passages of the respective reaction gases are defined between the gas separation members on both sides of the power generation element. Featuring Polymer electrolyte fuel cell. 2. The polymer electrolyte fuel cell according to claim 1, wherein the projecting portion is provided discontinuously in the lateral direction with respect to the extending direction of the power generation element. 3. A power generating element in which electrode constituent members are disposed on both sides of a polymer electrolyte membrane, and extending from both sides of the power generating element to support the power generating element, and to participate in the power generating element from the side of each of the electrode constituent members. In a solid polymer electrolyte fuel cell configured by stacking a power generation cell structure including a pair of gas separation members that define respective reaction gas passages, the polymer electrolyte membrane exceeds an electrode constituent member. Gas that is disposed in a portion that extends so as to support the peripheral portion of the electrode component member so as to be flush with the electrode component member, and distributes and supplies the reaction gas from the main gas passage to the gas passages of the power generation cell structures. A polymer electrolyte fuel cell, further comprising a frame including at least a manifold, wherein the power generation element and the frame are bonded to each other. 4. The polymer electrolyte fuel cell according to claim 3, wherein a contact portion between the polymer electrolyte membrane and the frame is adhered with an adhesive. 5. The polymer electrolyte fuel cell according to claim 3, wherein a contact portion between the polymer electrolyte fuel cell and the frame is heat-bonded. 6. The power generating element member according to claim 3, further extending and sandwiching the power generating element member from both sides to support the power generating element member, and to define passages of respective reaction gases involved in the power generating element from the side of the respective electrode constituent members. A solid polymer electrolyte fuel cell, comprising a gas separation member, wherein the polymer electrolyte membrane and the gas separation member are joined together. 7. A power generating element in which electrode constituent members are arranged on both sides of a polymer electrolyte membrane, and extending from both sides of the power generating element member and supported from both sides, and the power generating element is involved from the side of each of the electrode constituent members. In a polymer electrolyte fuel cell constituted by stacking a power generation cell structure including a pair of gas separation members that define respective reaction gas passages, a polymer electrolyte membrane is formed across electrode members. A frame disposed around the electrode constituent member so as to be flush with the electrode constituent member is further provided at the peripheral portion of the extending power generating element, and the frame has the polymer electrolyte membrane on both sides of the polymer electrolyte membrane. A polymer electrolyte fuel cell, characterized in that a coating material is arranged on both sides of at least one of the frames, which is sandwiched, and is joined to the gas separation member.