JP2005116179A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell in which a drainage function can be improved in a gas diffusion electrode in addition to a reaction gas flow-passage. <P>SOLUTION: This is provided with the gas diffusion electrode arranged on both sides of an electrolyte film, a rib 6 arranged adjacent to the gas diffusion electrode and contacted with the gas diffusion electrode at its contact face 4a, and a separator 4 having a groove-shaped gas flow-passage 5 formed between the ribs 6. A hydrophilic part 21 is formed by communicating and applying a hydrophilic treatment to one part (hydrophilic part 21b) of a face 16 which contacts with the gas diffusion electrode of the rib 6, and to one part (hydrophilic part 21a) of a groove surface 17 forming the gas flow-passage 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell. In particular, the present invention relates to a polymer electrolyte fuel cell that requires water management in the fuel cell.

  As a conventional fuel cell, one having a configuration for suppressing clogging of a gas flow path as described below is known.

A separator equipped with a reaction gas flow groove on both outer surfaces of the fuel electrode and the oxidant electrode sandwiching the solid polymer electrolyte membrane is disposed so that the reaction gas flow groove faces the fuel electrode or the oxidant electrode, and the gas seal Hold the layer tightly and make up. At least a part of the inner surface of the separator is provided with a hydrophilic coating film made of, for example, (poly) amino acid or protein, and a cooling water circulation groove is provided in the separator to constitute a fuel cell (see, for example, Patent Document 1). ).
JP 2001-93539 A

  However, in the fuel cell as described in the above background art, blockage in the gas flow path can be prevented, but water in the gas diffusion electrode is hardly drained. For this reason, flooding occurs in the gas diffusion electrode, resulting in a problem that the diffusibility of the reaction gas is lowered and the power generation efficiency is lowered.

  In view of the above problems, an object of the present invention is to provide a fuel cell that can improve the drainage function in the gas diffusion electrode in addition to the reaction gas flow path.

  The present invention includes a gas diffusion electrode disposed on both sides of an electrolyte membrane, a gas diffusion electrode disposed adjacent to the gas diffusion electrode, a rib contacting the gas diffusion electrode on a contact surface thereof, and formed between the ribs. A separator having a groove-shaped reaction gas flow path. A hydrophilic portion is formed by performing a hydrophilic treatment in communication with a part of the surface of the rib contacting the gas diffusion electrode and a part of the groove surface forming the reaction gas flow path.

  A hydrophilic portion is formed by performing a hydrophilic treatment in communication with a part of the surface of the rib contacting the gas diffusion electrode and a part of the groove surface forming the reaction gas flow path. As a result, the water absorbed by a part of the surface in contact with the gas diffusion electrode moves to the groove surface through the hydrophilic portion, and is removed by evaporating or transporting to the reaction gas flowing in the reaction gas channel. It becomes possible. As a result, the drainage function of the gas diffusion electrode can be improved, and the decrease in the diffusibility of the reaction gas can be suppressed.

  A first embodiment will be described. A schematic configuration of a unit cell constituting the fuel cell is shown in FIG. A fuel cell is configured using a stack formed by stacking a plurality of unit cells. Or you may comprise using one unit cell.

  An electrolyte membrane 1 having a catalyst layer (not shown) is sandwiched between a pair of gas diffusion electrodes 2 and further sandwiched between two separators 4. The catalyst layer may be formed on the surface of the gas diffusion electrode 2 that contacts the electrolyte membrane 1. Alternatively, the electrolyte membrane 1, the catalyst layer, and the gas diffusion layer 2 may be formed independently and assembled at times. The separator 4 is formed of a dense material that does not have the permeability of the reaction gas and water. Further, a sealing material 3 is provided along the outer periphery of the separator 4 to close the space sandwiched between the separators 4. Gas leakage and short circuit are prevented by the sealing material 3.

  A plurality of groove-like gas flow paths 5 through which fuel gas or oxidant gas flows are formed on a surface 4 a of the separator 4 that contacts the gas diffusion electrode 2. The groove-like gas flow path 5 is formed into a groove bottom surface 11 parallel to the gas diffusion electrode 2, a groove surface 17 formed from groove side surfaces 12 a and 12 b perpendicular to the gas diffusion electrode 2, and a surface of the gas diffusion electrode 2. Formed by enclosed space. In addition, ribs 6 that partition the gas flow paths 5 are formed between the adjacent gas flow paths 5. Here, the rib 6 is formed by a convex region surrounded by the contact surface 16 that contacts the gas diffusion electrode 2 and the groove side surfaces 12a and 12b. The rib 6 has a function for maintaining mechanical strength and a current collecting function.

  Next, an enlarged view of the separator 4 used in such a unit cell is shown in FIG.

  A hydrophilic treatment is applied to a part of the surface 4 a facing the gas diffusion electrode 2 of the separator 4. Here, a substantially L-shaped hydrophilic portion 21 is formed by performing a hydrophilic treatment in communication with a part of the contact surface 16 and each groove side surface 12 adjacent thereto. As shown in FIG. 2, the hydrophilic portion 21 x formed on the entire groove side surface 12 and a part of the contact surface 16 does not communicate with the adjacent hydrophilic portion 21 y via the rib 6, and is not part of the contact surface 16. Consecutive. That is, the groove side surface 12 becomes the hydrophilic portion 21 a, the groove bottom surface 11 becomes the non-hydrophilic portion 22, and the contact surface 16 has a hydrophilic portion 21 b at the end and a central portion at the non-hydrophilic portion 22 in the cross section perpendicular to the gas flow path 5. .

  By forming in this way, a part of the contact surface 16 between the separator 4 and the gas diffusion electrode 2 is subjected to a hydrophilic treatment, and a part thereof is not subjected to a hydrophilic treatment. Further, the groove surface 17 of the gas flow path 5 is also partially subjected to hydrophilic treatment (groove side surface 12) and partially not subjected to hydrophilic treatment (groove bottom surface 11).

  As another example of this embodiment, FIG. 3 shows a separator 4 having a gas flow path 5 having a curved cross section.

  A hydrophilic portion 21 that communicates from a part of the contact surface 16 to a part of the groove surface 17 that forms the gas flow path 5 is formed. For example, of the groove surface 17 that forms the gas flow path 5, the surface that forms an angle (45 ° to 90 °) that is nearly perpendicular to the gas diffusion electrode 2 is the groove side surface 12, and is parallel to the gas diffusion electrode 2. A surface forming an angle close to (0 ° to 45 °) is defined as a groove bottom surface 11. A substantially L-shaped hydrophilic portion 21 is formed on part of the groove side surface 12 and the contact surface 16. Thereby, a part of the contact surface 16 is formed in the hydrophilic part 21 b and a part is formed in the non-hydrophilic part 22. Further, a part of the groove surface 17 is formed in the hydrophilic part 21 a and a part is formed in the non-hydrophilic part 22.

  The hydrophilic portion 21 is preferably formed substantially symmetrically at both ends of the rib 6 in a cross section perpendicular to the flow path axis of the gas flow path 4.

  Next, the state of water when the hydrophilic portion 21 as described above is formed on the separator 4 will be described.

  Water generated by the electrochemical reaction and accumulated in the gas diffusion electrode 2 is absorbed by the hydrophilic portion 21 b formed on the contact surface 16. The water absorbed in the hydrophilic portion 21 b diffuses into the hydrophilic portion 21 a formed on the groove side surface 12 due to the difference in water concentration, and a water film is formed on the groove side surface 12. When the reaction gas flows through the gas flow path 5, the film-like water formed on the surface of the groove side surface 12 evaporates, or is discharged out of the fuel cell together with the reaction gas as small water droplets. Thereby, since the water stored in the gas diffusion electrode 2 can be removed, the gas diffusibility of the gas diffusion electrode 2 can be maintained and the performance and stability of the fuel cell can be improved.

  Next, the effect of this embodiment will be described.

  A gas diffusion electrode 2 disposed on both sides of the electrolyte membrane 1, a rib 6 disposed adjacent to the gas diffusion electrode 2, and in contact with the gas diffusion electrode 2, formed between the ribs 6. And a separator 4 having a groove-shaped gas flow path 5. A part of the surface 16 of the rib 6 that contacts the gas diffusion electrode 2 (hydrophilic part 21 b) and a part of the groove surface 17 that forms the gas flow path 5 (hydrophilic part 21 a) are communicated and subjected to a hydrophilic treatment. Thus, the hydrophilic portion 21 is formed.

  This facilitates the movement of the water present in the gas diffusion electrode 2 to the gas flow path 5 side, and the liquid gas, together with the reaction gas flowing through the gas flow path 5, remains in liquid water or is evaporated and discharged outside the cell. Therefore, the drainage function of the gas diffusion electrode 2 can be improved. As a result, performance degradation due to flooding or the like in the gas diffusion electrode 2 can be suppressed, and the durability and reliability of the fuel cell can be ensured. In addition, since only a part of the rib 6 is the hydrophilic portion 21b, water existing between the rib 6 and the diffusion electrode 2 receives driving force from both gas passages adjacent to the rib at the same time, and hardly moves on the contrary. While avoiding this state, it is easy to guide water to one of the adjacent gas flow paths 5 and suppress an increase in contact electrical resistance between the gas diffusion electrode 2 and the separator 4 due to the hydrophilic treatment. Can do. Further, in the upstream region of the gas flow path 5, the water absorbed by the gas diffusion electrode 2 is moved to the gas flow path 5 and evaporated into the reaction gas, whereby the reaction gas can be humidified.

  In addition, since only a part of the groove surface 17 is subjected to the hydrophilic treatment to form the hydrophilic portion 21a, the treatment area can be reduced and the liquid water can be concentrated in a relatively narrow region, so that a part of the groove surface 17 can be obtained. It is possible to easily form a water film and to easily remove the water film from the gas flow path 5 by the reaction gas.

  Next, a second embodiment will be described. A perspective enlarged view of the gas flow path 5 is shown in FIG. Hereinafter, a description will be given centering on differences from the first embodiment.

  A hydrophilic portion 21 is formed in communication with a part of the contact surface 16 and the groove side surface 12. It forms so that the area ratio of the hydrophilic part 21a formed in the groove | channel side surface 12 may change about the distribution direction of a reactive gas. Here, the area ratio of the hydrophilic portion 21a formed on the groove side surface 12 is changed according to the ease of water clogging based on the amount of liquid water produced. On the inlet 5i side of the gas flow path 5, the area of the hydrophilic portion 21a formed on each groove side surface 12 is the smallest, and is formed so as to increase toward the outlet 5o side of the gas flow path 5. Although the area ratio of the hydrophilic portion 21a is changed stepwise here, it may be changed continuously. Since part of the hydrophilic portion 21 communicates with the contact surface 16, the area is changed by changing the distance h to the groove bottom portion 11 of the hydrophilic portion 21 a formed on the groove side surface 12.

  Next, the effect of this embodiment will be described. Only the effects different from those of the first embodiment will be described below.

  Of the groove surface 17, the groove side surface 12 is subjected to a hydrophilic treatment, and the area ratio of the groove surface 17 to be subjected to the hydrophilic treatment is changed in the flow channel axial direction of the gas flow channel 5. Thereby, a drainage function can be set according to the ease of occurrence of water clogging.

  Here, the area ratio to which the hydrophilic treatment is performed is changed according to the ease of water clogging based on the amount of liquid water generated. When the humidity of the reaction gas supplied is approximately 100%, the water generated during the reaction exists in the form of liquid water. Therefore, the area of the hydrophilic portion 21a formed on the groove side surface 12 is increased toward the downstream side in the gas flow direction. Thereby, water absorption and water retention improve as it goes downstream in the gas flow path 5. As a result, the amount of water present as liquid water is large, and the drainage function can be improved on the downstream side where water clogging is relatively likely to occur, so flooding can be suppressed.

  Here, the area ratio is changed stepwise. Thereby, a hydrophilic process can be performed comparatively easily. In addition, you may change an area ratio continuously. In this case, the area of the hydrophilic portion 21 can be accurately set according to the amount of liquid water present.

  Further, the hydrophilic portion 21 is formed in communication from the upstream side to the downstream side of the gas flow path 5. As a result, water can move within the hydrophilic portion 21 in the entire flow channel axial direction of the gas flow channel 5, so that water clogging occurs even when the balance between the drainage function and the amount of liquid water is lost. Drainage can be performed without any problems.

  Next, a third embodiment will be described. A perspective enlarged view of the gas flow path 5 is shown in FIG. Hereinafter, a description will be given centering on differences from the first embodiment.

  A hydrophilic portion 21 is formed in communication with a part of the contact surface 16 and the groove side surface 12. It forms so that the area ratio of the hydrophilic part 21a formed in the groove | channel side surface 12 may change about the distribution direction of a reactive gas. Here, the area ratio of the hydrophilic portion 21a formed on the groove side surface 12 is set according to the power generation ratio of the power generation region. Since a large amount of water is required in the region where the power generation ratio is large, the amount of water that can be contained is increased by increasing the area ratio of the hydrophilic portion 21a. The area of the hydrophilic portion 21a formed on the groove side surface 12 is the largest on the inlet 5i side of the gas flow path 5, and is configured to become smaller toward the outlet 5o side of the gas flow path 5. Although the area of the hydrophilic portion 21a is changed stepwise here, it may be changed continuously. Since part of the hydrophilic portion 21 communicates with the contact surface 16, the area is changed by changing the distance h to the groove bottom portion 11 of the hydrophilic portion 21 a formed on the groove side surface 12.

  Next, the effect of this embodiment will be described. Hereinafter, the effects different from those of the first or second embodiment will be mainly described.

  Of the groove surface 17, the groove side surface 12 is subjected to a hydrophilic treatment, and the area ratio of the hydrophilic treatment is changed in the flow channel axial direction of the gas flow channel 5. Thereby, a drainage function can be set according to the ease of occurrence of water clogging.

  Here, the area ratio to which the hydrophilic treatment is performed is changed according to the power generation ratio of the power generation region. A lot of water is needed in the upstream region where power generation is often performed. In the upstream region where the reaction gas is relatively dry, it is difficult to sufficiently supply water used for power generation from the reaction gas. Therefore, the area of the hydrophilic portion 21a formed on the groove side surface 12 is increased toward the upstream side in the gas flow direction. Thereby, water absorption and water retention improve as it goes to the upstream side in the gas flow path 5. As a result, the amount of water present as liquid water is large, and the water absorbed on the downstream side, which is relatively prone to clogging, can be moved upstream to be used for humidifying the reaction gas. As a result, a decrease in power generation efficiency due to drying of the reaction gas can be suppressed, and efficient and stable power generation can be performed.

  Here, the area ratio is changed stepwise. Thereby, a hydrophilic process can be performed comparatively easily. In addition, you may change an area ratio continuously. In this case, the area of the hydrophilic portion 21 can be accurately set according to the amount of water required for power generation.

  Next, a fourth embodiment will be described. A perspective enlarged view of the gas flow path 5 is shown in FIG. Hereinafter, a description will be given centering on differences from the first embodiment.

  A hydrophilic portion 21 is formed in communication with a part of the contact surface 16 and the groove side surface 12. It forms so that the area of the hydrophilic part 21a formed in the groove | channel side surface 12 may change about the distribution direction of a reactive gas. Here, the hydrophilic portion 21 formed in communication with the groove side surface 12 from a part of the contact surface 16 is intermittently formed in the flow direction of the reaction gas. For example, as shown in FIG. 6, the hydrophilic portions 21 are formed at equal intervals in the gas flow direction in the gas flow path 5, and the non-hydrophilic portion 22 is formed between them.

  Next, the effect of this embodiment will be described. Hereinafter, an effect different from the effects of the first to third embodiments will be mainly described.

  Of the groove surface 17, the groove side surface 12 is subjected to a hydrophilic treatment, and the area ratio of the hydrophilic treatment is changed in the flow channel axial direction of the gas flow channel 5. Thereby, a drainage function can be set according to the ease of occurrence of water clogging.

  Here, the hydrophilic portion 21 is intermittently formed in the flow channel axial direction of the gas flow channel 5. At the boundary surface between the hydrophilic portion 21 and the non-hydrophilic portion 22, the water film formed on the hydrophilic portion 21a is likely to change into water droplets, and as a result, is easily discharged from the fuel cell together with the reaction gas. In particular, among the boundary between the hydrophilic portion 21 and the non-hydrophilic portion 22, water contained in the hydrophilic portion 21 is easily discharged together with the reaction gas at the boundary 24 located on the downstream side of the hydrophilic portion 21. As a result, the drainage function can be improved, water clogging can be maintained, and gas diffusibility can be maintained.

  In FIG. 6, the number of the hydrophilic portions 21 is three. However, the present invention is not limited to this, and the hydrophilic portion 21 may be formed so as to balance the water holding function of the hydrophilic portion 21 and the excessive water drainage function. Moreover, each hydrophilic part 21 is not necessarily the same area. For example, the water retention function can be improved by increasing the area in the upstream region where the humidity of the reaction gas tends to be relatively low. Further, in the downstream region where the amount of water present as liquid water tends to be relatively large, by reducing the area and interval of each hydrophilic portion 21 and forming many boundaries between the hydrophilic portion 21 and the non-hydrophilic portion 22, The drainage function can be improved.

  Next, a fifth embodiment will be described. A schematic perspective view of the separator 4 is shown in FIG. Hereinafter, a description will be given centering on differences from the fourth embodiment.

  A hydrophilic portion 21 c is formed on a part of the groove bottom surface 11. Here, at least the non-hydrophilic portion 22 of the groove side surface 22 in the fourth embodiment and the hydrophilic portion 21 are formed in a region larger than a region overlapping in the flow path axis direction. That is, the hydrophilic part 21c has a length in the flow path axis direction that is greater than the distance between the adjacent hydrophilic parts 21a in the flow path axis direction formed on the groove side surface 12, and between the adjacent hydrophilic parts 21a. Be placed. By forming the hydrophilic portion 21 in this manner, in the fourth embodiment, the hydrophilic portion 21a that is intermittently formed in the flow path axis direction is formed in communication with the hydrophilic portion 21c.

  Next, the effect of this embodiment will be described. Hereinafter, the effects different from the first to fourth embodiments will be mainly described.

  The hydrophilic portion 21 is formed in communication with the gas flow path 5 in the flow path axial direction. By forming in this way, the continuous hydrophilic part 21 can be formed from the inlet 5i of the gas flow path 5 to the outlet 5o. Therefore, the movement of the water absorbed in the hydrophilic portion 21 in the direction of the flow path axis can be promoted, and the reaction gas can be locally dried or flooding can be suppressed in the flow path axis direction.

  Next, a sixth embodiment will be described. A plan view of the surface 4a of the separator 4 that contacts the gas diffusion electrode 2 is shown in FIG.

  A plurality of serpentine gas flow paths 5 formed in parallel are formed in the separator 4. Between adjacent gas flow paths 5, ribs 6 that partition the flow paths are formed. One end of the gas flow path 5 communicates with a supply side manifold 7 that penetrates the fuel cell in the stacking direction, and the other end communicates with a discharge side manifold 8 that also penetrates the fuel cell in the stacking direction.

  The reaction gas supplied to the fuel cell from the outside is distributed from the supply side manifold 7 to the gas flow path 5 of each unit cell stacked. When the reaction gas flows through the gas flow path 5, a part of the reaction gas diffuses into the gas diffusion electrode 2 and is used for the reaction. The reacted gas after the reaction is collected in the discharge side manifold 8 penetrating the fuel cell in the stacking direction and discharged outside the fuel cell.

  In such a separator 4, the hydrophilic portion 21 is formed in the downstream region A of the gas flow path 5. Here, the hydrophilic portion 21 is formed only in the most downstream stage of the meandering shape. As shown in FIG. 8, the gas flow path 5 is formed in a three-stage meandering shape, and the hydrophilic portion 21 is formed only in the third stage. As the shape of the hydrophilic portion 21, any of those shown in the first to fifth embodiments may be used.

  Next, the effect of this embodiment will be described. Hereinafter, the effects different from the effects of the first to fifth embodiments will be mainly described.

  The hydrophilic portion 21 is formed only in the downstream region A of the entire gas channel 5. In this way, by forming the hydrophilic portion 21 only in the downstream area A where flooding is likely to occur, the area to be treated can be reduced, so that the treatment cost is reduced and an efficient drainage function is formed. can do.

  Next, a seventh embodiment will be described. A plan view of the surface 4a of the separator 4 that contacts the gas diffusion electrode 2 is shown in FIG. Hereinafter, a description will be given centering on differences from the sixth embodiment.

  Similar to the sixth embodiment, a meandering gas flow path 5 is formed in the separator 4. However, an intermediate manifold 9 that penetrates the fuel cell in the stacking direction is formed at the folded portion of the gas flow path 5. Here, since the gas flow path 5 is formed in a three-stage meandering shape, the intermediate manifold 9a is formed in the folded portion that folds back from the first stage to the second stage, and the intermediate manifold 9b is formed in the folded portion that folds back from the second stage to the third stage. Form.

  In such a separator 4, the hydrophilic portion 21 is formed in the downstream region A of the gas flow path 5 as in the sixth embodiment. Here, the hydrophilic portion 21 is formed only in the third stage which is the most downstream stage of the meandering shape. As the shape of the hydrophilic portion 21, any of those shown in the first to fifth embodiments may be used. By configuring in this way, the same effect as in the sixth embodiment can be obtained.

  Next, an eighth embodiment will be described. A plan view of the surface 4a of the separator 4 that contacts the gas diffusion electrode 2 is shown in FIG.

  A plurality of linear gas flow paths 5 are provided in the separator 4 in parallel. Between adjacent gas flow paths 5, ribs 6 that partition the flow paths are formed. One end of each gas flow path 5 is connected to the supply side manifold 7 in parallel, and the other end is connected to the discharge side manifold 8 in parallel.

  The reaction gas supplied from the outside to the fuel cell is distributed to the gas flow path 5 of each unit cell from a supply-side manifold 7 formed through the fuel cell in the stacking direction. When the reaction gas flows through the gas flow path 5, a part of the reaction gas diffuses into the gas diffusion electrode 2 and is used for the reaction. The reacted gas after the reaction is collected in the discharge side manifold 8 penetrating the fuel cell in the stacking direction and discharged outside the fuel cell.

  In the separator 4 thus formed, the hydrophilic portion 21 is provided only in the downstream region B of the linear gas flow path 5. As the shape of the hydrophilic portion 21, any of those shown in the first to fifth embodiments may be used.

  By configuring in this way, similarly to the sixth embodiment, it is possible to reduce the area to be processed while suppressing flooding, so that the processing cost can be reduced and an efficient drainage function can be formed. .

  Next, a ninth embodiment will be described. A cross section of the separator 4 in a direction perpendicular to the flow path axis of the gas flow path 5 is shown in FIG. Hereinafter, a description will be given centering on differences from the first embodiment.

  Similarly to the first embodiment, an L-shaped hydrophilic portion 21 is formed on the groove side surface 12 and the contact portion 16. In addition, the water repellent portion 23 is formed by subjecting the region of the groove surface 17 that was the non-hydrophilic portion 22 to water repellent treatment. Here, the groove bottom surface 11 is subjected to water repellent treatment to form the water repellent portion 23. Therefore, the corner portion 10 formed by the groove side surface 12 and the groove bottom surface 11 serves as a boundary between the hydrophilic portion 22 and the water repellent portion 23. In the cross section perpendicular to the flow path axis, a hydrophilic portion 21 a and a water repellent portion 23 are formed on the groove surface 17.

  In the present embodiment, the water-repellent portion 23 is formed in which at least a part of the groove surface 17 that has not been subjected to the hydrophilic treatment (non-hydrophilic region 22) is subjected to the water-repellent treatment. As a result, liquid water is more likely to concentrate on the hydrophilic portion 21, so that a water film is easily formed on the surface of the hydrophilic portion 22, and as a result, is easily removed with the flow of the reaction gas. As a result, since the drainage function of the gas diffusion electrode 2 and the gas flow path 5 is improved, the occurrence of flooding can be suppressed. Further, since water that is not contained in the hydrophilic portion 21 exists in the form of water droplets on the surface of the gas flow path 5 in the water repellent portion 23, it is easily discharged by the flow of the reaction gas.

  Further, water can be prevented from staying at the boundary portion between the hydrophilic portion 21 and the water repellent portion 23, and water can be prevented from staying in the gas flow path 5. In particular, the boundary portion between the hydrophilic portion 21 and the water repellent portion 23 was formed to be the corner portion 10 of the gas flow path 5. Thereby, since the drainage function of the corner | angular part 10 in which water stays comparatively easily can be improved, water can be made hard to stay in the gas flow path 5.

  In addition to the first embodiment, the water-repellent portion 23 can be formed similarly in any of the second to fifth embodiments. For example, the water repellent portion 23 may be formed by performing a water repellent treatment on the entire region of the groove surface 17 where the hydrophilic treatment is not performed. Alternatively, the water repellent portion 23 may be formed by performing water repellent treatment on a region of the groove bottom surface 11 that has not been subjected to hydrophilic treatment. Furthermore, such a water-repellent part 23 can be applied to the gas flow path 5 formed in any separator 4 described in the sixth to eighth embodiments.

  Next, a tenth embodiment will be described. A cross section of the separator 4 in a direction perpendicular to the flow path axis of the gas flow path 5 is shown in FIG. Hereinafter, a description will be given centering on differences from the ninth embodiment.

  The separator 4 is made of a water repellent material and other materials. A flat plate 41 is used as the water repellent material. Further, as other materials, columnar rib members 42 having no water repellency are used. The rib member 42 forms the rib 6 in the first embodiment after the separator 4 is assembled. Therefore, the rib member 42 is formed with the hydrophilic portion 21b in a part of the surface that becomes the contact surface 16 during assembly, and the hydrophilic portion 21a that communicates with the hydrophilic portion 21b in at least a part of the surface that becomes the groove side surface 12. Form.

  By arranging the rib members 42 on the flat plate 41 at equal intervals, the gas flow path 5 is formed between the adjacent rib members 42. With this configuration, the groove bottom surface 11 of the groove surface 17 is formed by the flat plate 41, and thus the groove bottom surface 11 becomes the water repellent portion 23. Further, the groove side surface 12 becomes a hydrophilic portion 21 a formed in the rib member 42, and the hydrophilic portion 21 and the water repellent portion 23 are formed in the gas flow path 5.

  In this way, the separator 4 is configured by disposing the rib member 42 that has been subjected to hydrophilic treatment on at least a part of the flat plate 41 having water repellency. Thereby, the hydrophilic part 21 and the water repellent part 23 can be easily formed on the groove surface 17 as compared with the ninth embodiment.

  In addition to the first embodiment, the water repellent part 23 can be formed in any of the second to fourth embodiments. Moreover, it can be applied to the gas flow path 5 formed in any separator 4 described in the sixth to eighth embodiments.

  Next, an eleventh embodiment will be described. FIG. 13 shows a cross section of the separator 4 and the gas diffusion electrode 2 in a direction perpendicular to the flow path axis of the gas flow path 5. Hereinafter, a description will be given centering on differences from the first embodiment.

  In the first embodiment, the gas diffusion electrode 2 that contacts the separator 4 is subjected to a hydrophilic treatment. Here, the entire gas diffusion electrode 2 is subjected to a hydrophilic treatment, but this is not a limitation. As described above, the hydrophilic treatment is performed on the gas diffusion electrode 2 so that the water generated in the reaction region easily moves in the gas diffusion electrode 2. Therefore, the generated water generated by the power generation reaction easily moves to the contact surface 16 with the rib 5 in the gas diffusion electrode 2 and eventually to the hydrophilic portion 21, so that water is easily discharged from the gas diffusion electrode 2. As a result, it reaches the groove surface 17 through the hydrophilic portion 21 and is easily discharged out of the fuel cell together with the reaction gas.

  In addition to the first embodiment, in any of the second to tenth embodiments, the gas diffusion electrode 2 can be similarly subjected to a hydrophilic treatment.

  Next, a twelfth embodiment will be described. A plan view of the surface 4a of the separator 4 that contacts the gas diffusion electrode 2 is shown in FIG. Hereinafter, a description will be given centering on differences from the sixth embodiment.

  As the gas flow path 5, a comb-shaped flow path is used. A supply side gas flow path 5a having one end communicating with the supply side manifold 7 and the other end dead end 13a, and a discharge side gas flow path 5b having one end communicating with the discharge side manifold 8 and the other end dead end 13b. The gas flow path 5 is formed by alternately forming them. The supply side gas flow path 5a and the discharge side gas flow path 5b are not communicated with each other, and the flow path axes are formed to be parallel to each other. A rib 6 that partitions the flow path is formed between the adjacent supply-side gas flow path 5a and the discharge-side gas flow path 5b.

  The reaction gas supplied from the supply side manifold 7 is distributed to a plurality of supply side gas flow paths 5a formed in parallel. Since the supply-side gas flow path 5a has a dead end 13a at the downstream end, the reaction gas is forcibly diffused to a gas diffusion electrode 2 (not shown) adjacent to the separator 4. The reaction gas that has permeated through the gas diffusion electrode 2 is used for the power generation reaction, and then discharged to the discharge-side gas flow path 5b whose upstream end is a dead end 13b. The reaction gas passes through the discharge side gas flow path 5b, is collected in the discharge side manifold 8, and is discharged to the outside of the fuel cell. In such comb-shaped alternating gas flow paths 5, the hydrophilic portion 21 is formed only in the discharge-side gas flow path 5b. Since the reaction gas diffused in the gas diffusion electrode 2 is consumed by the power generation reaction, the gas flow rate in the discharge side gas passage 5b is smaller than that in the supply side gas passage 5a. Therefore, the flow rate of the reaction gas in the discharge side gas flow path 5b becomes small, and water is hardly discharged. Therefore, by providing the hydrophilic portion 21 in the discharge side gas flow path 5b, even when the flow rate of the reaction gas is low, water is easily moved to prevent the flow path from being blocked.

  Next, the effect of this embodiment will be described. Hereinafter, only effects different from the effects of the first to eleventh embodiments will be described.

  One end of the gas flow path 5 communicates with the supply-side manifold 7 and the other end communicates with the supply-side gas flow path 5a having a dead end 13a, and the other end communicates with the discharge-side manifold 8 and the other end has a dead end 13b. The gas flow paths 5b are arranged alternately. The hydrophilic portion 21 is formed only in the discharge side gas flow path 5b. As a result, flooding can be suppressed and power generation efficiency can be maintained in the discharge-side gas flow path 5b where the flow rate of the reaction gas flowing is small.

  Note that any of the first to fifth, ninth, and tenth embodiments may be used as the shape of the gas flow path 5 used in the present embodiment. Further, similarly to the eleventh embodiment, the gas diffusion electrode 2 may be subjected to a hydrophilic treatment.

  Further, here, the gas flow path 5 is not limited to the anode gas flow path for flowing the fuel gas or the cathode gas flow path for flowing the oxidant gas. Only the above-described configuration may be used, or both the flow paths may be configured as described above.

  Thus, the present invention is not limited to the best mode for carrying out the invention, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims. .

  The present invention can be applied to a polymer electrolyte fuel cell.

It is a schematic block diagram of the unit cell of the fuel cell used for 1st Embodiment. It is sectional drawing of the separator used for 1st Embodiment. It is sectional drawing of another example of the separator used for 1st Embodiment. It is a perspective schematic diagram of the separator used for a 2nd embodiment. It is a perspective schematic diagram of the separator used for a 3rd embodiment. It is a perspective schematic diagram of the separator used for a 4th embodiment. It is a perspective schematic diagram of the separator used for a 5th embodiment. It is a top view of the separator used for a 6th embodiment. It is a top view of the separator used for a 7th embodiment. It is a top view of the separator used for an 8th embodiment. It is sectional drawing of the separator used for 9th Embodiment. It is sectional drawing of the separator used for 10th Embodiment. It is sectional drawing of the separator and gas diffusion electrode which are used for 11th Embodiment. It is a top view of the separator used for a 12th embodiment.

Explanation of symbols

1 Solid polymer electrolyte membrane (electrolyte membrane)
2 Gas diffusion electrode 4 Separator 5 Gas flow path (reaction gas flow path)
5a Supply side gas flow path 5b Discharge side gas flow path 6 Rib 7 Supply side manifold 8 Discharge side manifold 11 Groove bottom surface 12 Groove side surface 16 Contact surface 21 Hydrophilic portion 22 Non-hydrophilic portion 23 Water repellent portion

Claims (10)

A gas diffusion electrode disposed on both sides of the electrolyte membrane;
A separator having a rib disposed adjacent to the gas diffusion electrode and having a rib in contact with the gas diffusion electrode and a groove-shaped reaction gas channel formed between the ribs on the contact surface;
A hydrophilic portion is formed by performing a hydrophilic treatment in communication with a part of a surface of the rib that contacts the gas diffusion electrode and a part of a groove surface that forms the reaction gas flow path. Fuel cell.   2. The fuel cell according to claim 1, wherein the groove side surface of the groove surface is subjected to a hydrophilic treatment, and an area ratio of the groove surface subjected to the hydrophilic treatment is changed in a flow axis direction of the reaction gas flow channel.   The fuel cell according to claim 2, wherein the area ratio to which the hydrophilic treatment is performed is changed according to the power generation ratio of the power generation region or the ease of water clogging based on the amount of liquid water generated.   4. The fuel cell according to claim 2, wherein the hydrophilic portion is formed intermittently in the flow axis direction of the reaction gas flow channel.   The fuel cell according to claim 1, wherein the hydrophilic portion is formed so as to communicate with each other in a flow axis direction of the reaction gas flow channel.   The fuel cell according to claim 1, wherein the hydrophilic portion is formed only in a downstream region of the entire reaction gas channel.   2. The fuel cell according to claim 1, wherein a water repellent portion subjected to a water repellent treatment is formed on at least a part of a region of the groove surface not subjected to a hydrophilic treatment.   2. The fuel cell according to claim 1, wherein the separator is configured by disposing the rib having a hydrophilic treatment at least partially on a flat plate having water repellency.   The fuel cell according to claim 1, wherein the gas diffusion electrode is subjected to a hydrophilic treatment. A supply side gas flow path having one end communicating with the supply side manifold and the other end formed of a dead end;
One end communicates with the discharge side manifold, and the other end is constituted by alternately arranging the discharge side gas flow path consisting of a dead end,
The fuel cell according to claim 1, wherein a hydrophilic portion is formed only in the discharge side gas flow path.

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