JP2006331916A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology of restraining widened fluctuation of local power generating volumes in an electrode. <P>SOLUTION: An electrode, gas diffusion layers 10, 50, and a flow channel forming layer are provided respectively at an anode side and a cathode side of the fuel cell. Each flow channel forming layer is provided with a first flow channel into which gas flows in, a second flow channel exhausting gas, and a barrier rib separating the first and the second flow channels. A downstream side of the first flow channel and an upstream side of the second flow channel are blocked by the barrier rib. The first flow channel 251 at the anode side and the second flow channel 352 at the cathode side are constructed so as to be opposed with an electrolyte layer in between. The second flow channel of the anode side and the first flow channel of the cathode side are also constructed opposed with an electrolyte layer in between. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure of a fuel cell.

  The fuel cell has an electrolyte layer, an anode, and a cathode. A fuel gas (for example, hydrogen gas) is supplied to the anode, and an oxidizing gas (for example, air containing oxygen) is supplied to the cathode. In addition, for example, a gas diffusion layer for diffusing gas to be supplied to the electrode and a gas flow path in contact with the gas diffusion layer may be provided on the anode side and the cathode side of the fuel cell. Here, in order to make the gas flow uniform in the gas diffusion layer, a method has been proposed in which the partition walls (also referred to as ribs) forming the gas flow paths are obliquely processed (see, for example, Patent Document 1). ).

JP 2004-47213 A

  By the way, water may accumulate in the gas diffusion layer. Examples of the water accumulated in the gas diffusion layer include water generated by electrochemical reaction, water contained in the gas supplied to the electrode, and water moved from the opposite electrode through the electrolyte layer. is there. The water accumulated in the gas diffusion layer moves downstream by the gas flow. Then, the variation in the local water content in the electrode may increase.

  Here, if the regions of the anode and the cathode that have a relatively large amount of local moisture or regions that have a relatively small amount of local moisture face each other across the electrolyte layer, the amount of local power generation at the electrode There were many cases where the variation of the size also increased. For example, consider a case where a solid polymer electrolyte layer is employed as the electrolyte layer. In the solid polymer electrolyte layer, the conductivity of hydrogen ions decreases as the water content of the electrolyte membrane decreases. Here, when the regions of the anode and the cathode having a large amount of local moisture or the regions having a small amount of local moisture are opposed to each other with the electrolyte layer interposed therebetween, there is a variation in the local moisture content of the electrolyte layer. As a result, local variations in power generation amount may increase.

  In addition, the problem that the variation in local power generation amount due to the variation in the local water amount between the anode and the cathode is not limited to the fuel cell using the solid polymer electrolyte, but other electrolytes. It was a problem common to fuel cells using

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a technique for suppressing an increase in local variation in the amount of power generation in an electrode.

  In order to solve at least a part of the above problems, a fuel cell according to the present invention sandwiches an electrolyte layer, an anode electrode and a cathode electrode arranged so as to sandwich the electrolyte layer, and the electrolyte layer and each electrode. The anode-side separator and the cathode-side separator, the anode-side gas diffusion layer arranged between the anode electrode and the anode-side separator, and the anode-side gas diffusion layer and the anode-side separator. An anode-side flow path forming layer disposed between the cathode electrode and the cathode-side separator, and a cathode-side gas diffusion layer disposed between the cathode-side gas diffusion layer and the cathode-side separator. Each of the anode-side flow path forming layer and the cathode-side flow path forming layer includes: A first flow path that faces the gas diffusion layer and into which a gas defined for each electrode flows; a second flow path that faces the gas diffusion layer and discharges the gas; A partition that contacts the gas diffusion layer and separates the first flow path and the second flow path, and each of the downstream side of the first flow path and the upstream side of the second flow path is the The anode-side first flow path and the cathode-side second flow path are configured to face each other with the electrolyte layer interposed therebetween, and the anode-side second flow path is The first flow path on the cathode side is configured so as to face the first electrolyte layer.

  According to this fuel cell, the flow direction of the gas under the partition wall of the gas diffusion layer can be reversed between the anode side and the cathode side. With respect to the position of this area, the position of the downstream area on the anode side and the position of the downstream area on the cathode side are arranged at positions shifted from positions facing each other with the electrolyte layer interposed therebetween. As a result, it is possible to prevent the regions having a large amount of local moisture and the regions having a small amount of local moisture from facing each other across the electrolyte layer in the gas diffusion layer. It becomes possible to suppress an increase in the amount of variation.

  In the fuel cell, the gas flow directions in the anode-side first flow path and the cathode-side second flow path that overlap each other are opposite to each other when viewed along the overlapping direction of the layers. In addition, it is preferable that the gas flows in the anode-side second flow path and the cathode-side first flow path that overlap each other in opposite directions.

  According to this configuration, the gas flow directions in the gas flow path pairs facing each other with the electrolyte layer interposed therebetween are opposite to each other. Therefore, even in the area under the gas flow path of the gas diffusion layer, the area having a large amount of moisture It is possible to prevent the regions having a small amount of water from facing each other across the electrolyte layer. As a result, it is possible to further suppress the local variation in the amount of power generation at the electrode.

  In the fuel cell, one end of the flow path forming layer on the anode side has an inflow opening of the first flow path on the anode side, and one end of the flow path forming layer on the cathode side is the cathode. The second flow passage on the side of the anode has a discharge opening, and when viewed along the direction in which the layers overlap, the end of the flow passage forming layer on the anode side provided with the inflow opening is on the cathode side. It is preferable that the flow path forming layer is located on the same side as the end provided with the discharge opening.

  According to this configuration, since the inflow opening of the first flow path on the anode side and the discharge opening of the second flow path on the cathode side are located on the same side, the anode side facing each other with the electrolyte layer interposed therebetween In order to reverse the direction of gas flow in each of the first flow path and the second flow path on the cathode side, the structures of the flow path forming layers on the anode side and the cathode side are excessively complicated. Can be prevented.

  In each of the fuel cells, in each of the anode-side channel forming layer and the cathode-side channel forming layer, the first channel and the second channel are formed to run in parallel, The partition includes a main wall sandwiched between the first flow path and the second flow path that run in parallel, and an average value of the width of the main wall is equal to a width of the first flow path adjacent to the main wall. It is preferable that the average value and the average value of the width of the second flow path adjacent to the main wall are set to a value wider than both.

  According to this configuration, since the region under the main wall in the gas diffusion layer can be made wider than the region under the gas flow path, the gas diffusion by the gas diffusion layer can be made more effective. it can.

  In each fuel cell, the electrolyte layer may be formed using a solid polymer electrolyte.

  According to this configuration, it is possible to suppress an increase in local water content variation in the electrolyte layer, and thus it is possible to suppress an increase in local power generation variation in the electrode.

  The present invention can be realized in various forms. For example, the invention can be realized in the form of a fuel cell, a vehicle on which the fuel cell is mounted as a driving power source, and the like.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
B. Second embodiment:
C. Variations:

A. First embodiment:
FIG. 1 is a perspective view showing the structure of a fuel cell 100 (also referred to as “single cell 100”) as an embodiment of the present invention. The single cell 100 includes an electrolyte membrane 30 and an anode assembly 70 and a cathode assembly 80 that are provided in contact with both sides of the electrolyte membrane 30. The electrolyte membrane 30 is made of, for example, a solid polymer electrolyte.

  The anode assembly 70 is an anode catalyst layer 20 (corresponding to an electrode on the anode side) provided in contact with the electrolyte membrane 30, and the anode diffusion layer 10 provided in contact with the anode catalyst layer 20. And a separator 60 provided in contact with the anode diffusion layer 10. Similarly, the cathode assembly 80 includes a cathode catalyst layer 40 (corresponding to a cathode side electrode, also referred to as “cathode electrode 40” hereinafter) provided in contact with the electrolyte membrane 30, and a cathode provided in contact with the cathode catalyst layer 40. A diffusion layer 50 and a separator 60 provided in contact with the cathode diffusion layer 50 are included.

  The anode catalyst layer 20 and the cathode catalyst layer 40 are formed of a material including a catalyst and good conductivity. For example, a carbon powder carrying platinum as a catalyst and an electrolyte used for the electrolyte membrane 30 are mixed. A resin formed into a film is used.

  The anode diffusion layer 10 and the cathode diffusion layer 50 are formed of a material having good gas diffusibility and conductivity. For example, carbon cloth, carbon paper, or carbon felt is used.

  The separator 60 is sandwiched between the anode diffusion layer 10 and the cathode diffusion layer 50 when the single cells 100 are stacked. The separator 60 has a plurality of grooves on the surface in contact with the anode diffusion layer 10 (not shown). When the separator 60 is in contact with the anode diffusion layer 10, this groove forms a gas flow path through which fuel gas (for example, hydrogen gas) flows (details will be described later). Similarly, the separator 60 has a plurality of grooves on the surface in contact with the cathode diffusion layer 50 (not shown). When the separator 60 is in contact with the cathode diffusion layer 50, this groove forms a gas flow path through which an oxidizing gas (for example, air containing oxygen) flows (details will be described later). The separator 60 is made of a material having low hydrogen permeability and good conductivity. For example, a separator formed by mixing a conductive material into a resin is used. The surface of the separator 60 in contact with the anode diffusion layer 10 corresponds to the “anode-side flow path forming layer” in the present invention. The surface of the separator 60 in contact with the cathode diffusion layer 50 corresponds to the “cathode side flow path forming layer” in the present invention.

  The “z direction” in FIG. 1 indicates the stacking direction from the anode diffusion layer 10 to the cathode diffusion layer 50 in one single cell 100. The “x direction” indicates a direction perpendicular to the z direction, and the “y direction” indicates a direction perpendicular to each of the x direction and the z direction.

  FIG. 2 is a cross-sectional view of the single cell 100 as viewed along the x direction. First grooves 251 and second grooves 252 are alternately provided on the surface of the separator 60 in contact with the anode diffusion layer 10. The grooves 251 and 252 are separated by the main wall 222. The white arrow indicates the flow of the fuel gas in the anode diffusion layer 10. The fuel gas flows from the first groove 251 to the second groove 252 through the anode diffusion layer 10 (details will be described later).

  Further, the first groove 351 and the second groove 352 are alternately provided on the surface of the separator 60 in contact with the cathode diffusion layer 50. The grooves 351 and 352 are separated by the main wall 322. The hatched arrows indicate the flow of oxidizing gas in the cathode diffusion layer 50. The oxidizing gas flows from the first groove 351 to the second groove 352 through the cathode diffusion layer 50 (details will be described later).

  2, illustration of the cathode side of the upper separator 60 (the side opposite to the side in contact with the anode diffusion layer 10) is omitted, and the anode side of the lower separator 60 (side in contact with the cathode diffusion layer 50). The illustration on the opposite side) is omitted. Further, illustration of the left and right (directions along the y direction) ends is also omitted.

  FIG. 3 is a III-III cross section of FIG. FIG. 3 is a cross-sectional view of the anode side of the separator 60 as viewed along the direction opposite to the z direction, and shows the shape of the groove on the anode side of the separator 60. The separator 60 has an inner wall 220 and an outer wall 240. The II-II line indicates the position of the cross section of FIG.

  The outer wall 240 is formed so as to surround the periphery of the rectangular separator 60. An inflow opening 262 is provided in the outer wall 240 at the left end (opposite to the x direction) of the separator 60, and a discharge opening 264 is provided in the outer wall 240 at the right end (x direction). Fuel gas is supplied to the inflow opening 262, and exhaust gas is discharged from the discharge opening 264.

  The inner wall 220 has a pattern shape in which a rectangular wave shape is periodically repeated. The inner wall 220 is formed so as to extend from the outer wall 240 at the upper end (y direction) of the separator 60 to the outer wall 240 at the lower end (opposite direction of the y direction). As a result, the inflow opening 262 and the discharge opening 264 are separated by the inner wall 220.

  The inner wall 220 includes a plurality of (four in the example of FIG. 3) folded walls 228, a plurality of (five in the example of FIG. 3) main walls 222, and protruding walls 224 and 226. The folded wall 228 constitutes a rectangular wave-shaped mountain portion and a valley portion. The main wall 222 constitutes a portion that connects the rectangular wave-shaped peaks and valleys. The protruding wall 224 connects the upper outer wall 240 and the uppermost main wall 222, and the protruding wall 226 connects the lower outer wall 240 and the lowermost main wall 222.

  Each main wall 222 has a linear shape extending along the left and right (x direction), and is arranged at equal intervals in the y direction. The main walls 222 are arranged in parallel to each other. A first groove 251 is formed on one side of each main wall 222, and a second groove 252 is formed on the other side. That is, the main wall 222 is sandwiched between the first groove 251 and the second groove 252 formed in parallel. The first grooves 251 and the second grooves 252 are alternately arranged one by one with the main wall 222 interposed therebetween.

  An end portion on the right side (x direction) of each first groove 251 is closed by either the folded wall 228 or the protruding wall 226. A first opening 251o communicating with the inflow opening 262 is formed at the left end (the direction opposite to the x direction).

  On the other hand, the left end (opposite direction of the x direction) of each second groove 252 is closed by either the folded wall 228 or the protruding wall 224. A second opening 252o communicating with the discharge opening 264 is formed at the right end (x direction).

  As described above, the first groove 251 and the second groove 252 are partitioned by the inner wall 220. Therefore, gas cannot move directly between the first groove 251 and the second groove 252. As a result, the fuel gas supplied from the inflow opening 262 is supplied to the anode diffusion layer 10 through each first groove 251. Further, the exhaust gas flowing through the anode diffusion layer 10 is discharged to the discharge opening 264 through each second groove 252. That is, the gas flows from the first groove 251 to the second groove 252 through a portion below the main wall 222 of the anode diffusion layer 10. The white arrows in FIG. 3 indicate the direction of gas flow in the portion below the main wall 222 of the anode diffusion layer 10. Hereinafter, the first groove 251 is also referred to as “first anode channel 251”. The second groove 252 is also referred to as “second anode channel 252”.

  In FIG. 3, the outer wall 240, the protruding wall 224, the main wall 222, and the protruding wall 226 are provided with different types of hatching, but these are continuous walls of the same material. Is formed.

  4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 4 is a cross-sectional view of the cathode side of the separator 60 as seen along the direction opposite to the z direction, and shows the shape of the groove on the cathode side of the separator 60. The separator 60 has an inner wall 320 and an outer wall 340. The II-II line indicates the position of the cross section of FIG.

  The shape of the outer wall 340 is the same as the shape of the outer wall 240 on the anode side in FIG. Further, the inner wall 320 has the same shape as the shape of the inner wall 220 on the anode side in FIG. As a result, similar to the anode side in FIG. 3, each main wall 322 is sandwiched between the first groove 351 and the second groove 352 formed in parallel. The first grooves 351 and the second grooves 352 are alternately arranged with the main wall 322 interposed therebetween. The first groove 351 and the second groove 352 are partitioned by the inner wall 320.

  An end portion on the right side (x direction) of each first groove 351 is closed by either the folded wall 328 or the protruding wall 324. A first opening 351o communicating with the inflow opening 362 is formed at the left end (the direction opposite to the x direction).

  On the other hand, the left end (opposite direction in the x direction) of each second groove 352 is closed by either the folded wall 328 or the protruding wall 326. A second opening 352o that communicates with the discharge opening 364 is formed at an end on the right side (x direction).

  The oxidizing gas supplied from the inflow opening 362 is supplied to the cathode diffusion layer 50 through each first groove 351. The exhaust gas flowing through the cathode diffusion layer 50 is discharged to the discharge opening 364 through each second groove 352. That is, the gas flows from the first groove 351 to the second groove 352 through a portion below the main wall 322 of the cathode diffusion layer 50. The hatched arrows in FIG. 4 indicate the direction of gas flow in the portion below the main wall 322 of the cathode diffusion layer 50. Hereinafter, the first groove 351 is also referred to as a “first cathode channel 351”. The second groove 352 is also referred to as a “second cathode channel 352”.

  FIG. 5 is a perspective view of the single cell 100 as seen along the direction opposite to the z direction. FIG. 5 shows the anode side (cross-sectional view of FIG. 3) and the cathode side (cross-sectional view of FIG. 4) of the separator 60 in an overlapping manner. The white arrow in the figure indicates the direction of gas flow in the anode diffusion layer 10. The hatched arrows indicate the direction of gas flow in the cathode diffusion layer 50. Further, in FIG. 5, illustration of left and right (directions along the x direction) end portions is omitted.

  In the example of FIG. 5, the anode-side main wall 222 and the cathode-side main wall 322 overlap each other. In addition, the first anode channel 251 and the second cathode channel 352 overlap, and the second anode channel 252 and the first cathode channel 351 overlap. As a result, in each of the diffusion layers 10 and 50, the flow direction of the gas flowing under the main walls 222 and 322 facing (overlapping) with the electrolyte membrane 30 interposed therebetween is opposite between the anode side and the cathode side.

  By the way, in the cathode electrode 20, water is produced | generated by an electrochemical reaction. A part of the generated water is accumulated in the cathode diffusion layer 50. The accumulated water moves in the cathode diffusion layer 50 to the downstream side by the gas flow. Therefore, the amount of moisture under the main wall 322 in the cathode diffusion layer 50 tends to increase as the downstream cathode flow path 352 is closer.

  On the other hand, water is also accumulated in the anode diffusion layer 10. Examples of such water include water contained in the gas supplied to the anode diffusion layer 10 and water that has moved from the cathode assembly 80 to the anode assembly 70 via the electrolyte membrane 30. The accumulated water moves in the anode diffusion layer 10 to the downstream side by the gas flow. Therefore, the amount of water under the main wall 222 in the anode diffusion layer 10 tends to increase as the downstream anode flow path 252 is closer.

  Here, the single cell 100 of the first embodiment has the following various features and advantages. The first feature is that the arrangement of the gas flow paths adjacent to the main walls 222 and 322 (FIGS. 2 and 5) opposed to each other with the electrolyte membrane 30 in between is the supply flow path (the first anode flow path 251 and the first flow path). The cathode channel 351) and the discharge channel (second anode channel 252 and second cathode channel 352) are set so as to face each other with the electrolyte membrane 30 interposed therebetween. As a result, in each of the diffusion layers 10 and 50, the flow direction of the gas flowing under the main walls 222 and 322 facing each other is opposite between the anode side and the cathode side. Therefore, the tendency of the local water content bias under the main walls 222 and 322 is opposite between the anode side and the cathode side. Specifically, a region having a relatively large amount of moisture in the anode diffusion layer 10 (FIG. 2: second region A2) and a region having a relatively small amount of moisture in the cathode diffusion layer 50 (FIG. 2: first region C1) are present. , Opposite each other with the electrolyte membrane 30 in between. Similarly, the anode diffusion layer 10 has a relatively small amount of water (FIG. 2: first region A1) and the cathode diffusion layer 50 has a relatively large amount of moisture (FIG. 2: second region C2). Opposite across the membrane 30. That is, it is possible to balance the local moisture distribution on the anode side and the local moisture distribution on the cathode side.

  By the way, in the first embodiment, a solid polymer electrolyte membrane is used as the electrolyte membrane 30. The conductivity of hydrogen ions in the solid polymer electrolyte membrane decreases as the water content of the electrolyte membrane decreases. Therefore, when the moisture content of the electrolyte membrane 30 is reduced, the power generation efficiency may be reduced. However, in the first embodiment, as described above, the first region A1 having a relatively small amount of water on each of the anode side and the cathode side, and the second region A2 having a relatively large amount of moisture on the opposite side of C1, C2 is located. Then, the partial region of the electrolyte membrane 30 facing the first regions A1 and C1 having a relatively small amount of moisture can be supplied with moisture from the second regions A2 and C2 having a relatively large amount of moisture on the opposite electrode. It becomes possible. Therefore, in the single cell 100 of the first embodiment, it is possible to suppress the local water content variation of the electrolyte membrane 30 from increasing. As a result, the single cell 100 of the first embodiment has an advantage that it is possible to suppress an increase in variation in local power generation amount (current density) in the electrodes 20 and 40.

  In general, in a fuel cell, if the variation in local power generation amount at the electrodes 20 and 40 increases, the power generation efficiency of the entire fuel cell may also decrease. In addition, since the electrochemical reaction is concentrated in a partial region of the electrodes 20 and 40 (unit cell 100), deterioration of the partial region between the assemblies 70 and 80 and the electrolyte membrane 30 is likely to proceed. In addition, the durability of the single cell 100 may be reduced. In the first embodiment, as described above, it is possible to suppress the local variation in the amount of power generation in the electrodes 20 and 40, and thus it is possible to suppress the occurrence of such a problem.

  In addition, in the fuel cell electrode and gas diffusion layer, if excessive water accumulates in a part of the region, the part of the region is likely to deteriorate, and as a result, the durability of the single cell 100 may decrease. is there. In the first embodiment, as described above, the position of the second region A2 on the anode side and the position of the second region C2 on the cathode side are arranged at positions that deviate from the facing position across the electrolyte membrane 30. It can suppress that such a problem arises.

  The second feature point is that the width W222 (FIG. 2) of the main wall 222 is larger than both the width W251 of the first anode channel 251 and the width W252 of the second anode channel 252. With this configuration, the area under the main wall 222 in the anode diffusion layer 10 where the fuel gas can be forced to flow can be made wider than the areas under the gas flow paths 251 and 252. Then, the diffusion of the fuel gas by the anode diffusion layer 10 becomes more effective. As a result, the single cell 100 of the first embodiment has an advantage that an excessive decrease in power generation efficiency can be prevented.

  In the first embodiment, the electric current generated by power generation is supplied to an external load (not shown) by flowing through the anode diffusion layer 10, the separator 60, and the cathode diffusion layer 50. Here, since the width W222 is wider than both the width W251 and the width W252, a contact area between the anode diffusion layer 10 and the separator 60 is reduced, that is, an increase in electrical resistance can be suppressed. As a result, there is also an advantage that an excessive decrease in power generation efficiency can be prevented.

  Similarly, on the cathode side, the width W322 of the main wall 322 is set to a value larger than both the width W351 of the first cathode channel 351 and the width W352 of the second cathode channel 352. Accordingly, the cathode side of the separator 60 has the same advantages as the above-described anode side.

B. Second embodiment:
FIG. 6 is a cross-sectional view of the fuel cell (single cell) 100b according to the second embodiment when viewed in the x direction. Similar to the single cell 100 of the first embodiment shown in FIG. 2, the single cell 100b has a configuration in which the electrolyte membrane 30 is sandwiched between an anode assembly 70b and a cathode assembly 80b. The difference from the single cell 100 of the first embodiment is that the configuration of the separator 60b on the cathode side is different, and the direction of gas flow in the cathode-side grooves 351b and 352b is reversed. The configuration on the anode side of the separator 60b is the same as that of the separator 60 of the first embodiment. Other configurations are the same as those of the first embodiment.

  FIG. 7 is a VII-VII cross section of FIG. FIG. 7 is a sectional view of the cathode side of the separator 60b as seen along the direction opposite to the z direction, and shows the shape of the groove on the cathode side of the separator 60b. The separator 60b has an inner wall 320b and an outer wall 340b. In addition, the VI-VI line has shown the position of the cross section of FIG.

  The outer wall 340b is formed so as to surround the periphery of the rectangular separator 60b. The difference from the outer wall 340 of the first embodiment shown in FIG. 4 is that each of the inflow opening 362b and the discharge opening 364b is provided at the opposite end. Specifically, the inflow opening 362b is provided at an end portion on the right side (x direction), and the discharge opening 364b is provided at an end portion on the left side (opposite direction in the x direction).

  The inner wall 320b has the same shape as the inner wall 220 on the anode side of the first embodiment shown in FIG. Each main wall 322b is sandwiched between a first cathode channel 351b and a second cathode channel 352b formed in parallel. Further, the first cathode channel 351b and the second cathode channel 352b are alternately arranged with the main wall 322b interposed therebetween.

The end of each first cathode channel 351b on the left side (the direction opposite to the x direction) is blocked by either the folded wall 328b or the protruding wall 324b. On the right (x direction) end,
A first opening 351bo communicating with the inflow opening 362b is formed.

  On the other hand, the right end (x direction) end of each second cathode channel 352b is closed by either the folded wall 328b or the protruding wall 326b. A second opening 352bo that communicates with the discharge opening 364b is formed at the left end (the direction opposite to the x direction).

  The oxidizing gas supplied from the inflow opening 362b flows into the cathode diffusion layer 50 through each first cathode channel 351b, and the exhaust gas flowing through the cathode diffusion layer 50 flows into the discharge opening through each second cathode channel 352b. It is discharged to 364b. The hatched arrows in FIG. 7 indicate the direction of gas flow in the portion below the main wall 322b of the cathode diffusion layer 50.

  FIG. 8 is a perspective view of the single cell 100b as seen along the direction opposite to the z direction. In FIG. 8, the anode side (cross-sectional view of FIG. 3) and the cathode side (cross-sectional view of FIG. 8) of the separator 60b are shown in an overlapping manner. Open arrows indicate the direction of gas flow in the anode diffusion layer 10, and hatched arrows indicate the direction of gas flow in the cathode diffusion layer 50. The solid line arrows indicate the direction of gas flow in the anode-side gas flow paths 251 and 252, and the broken line arrows indicate the direction of gas flow in the cathode-side gas flow paths 351b and 352b.

  In the single cell 100b of the second embodiment, the anode-side main wall 222 and the cathode-side main wall 322b overlap each other as in the single cell 100 of the first embodiment shown in FIG. In addition, the second anode channel 252 and the first cathode channel 351b overlap, and the first anode channel 251 and the second cathode channel 352b overlap. Accordingly, in each of the diffusion layers 10 and 50, the direction of the flow of the gas flowing under the main walls 222 and 322 b facing (overlapping) with the electrolyte membrane 30 in between is the anode side (open arrow) and the cathode side (hatching) The direction of the arrow is reversed. As a result, the region with a relatively small amount of water (FIG. 6: first regions A1 and C1b) and the region with a relatively large amount of moisture (second regions A2 and C2b) face each other across the electrolyte membrane 30. It becomes. That is, it is possible to balance the local moisture distribution on the anode side and the local moisture distribution on the cathode side.

  On the cathode side of the single cell 100b, the width W322b (FIG. 6) of the main wall 322b is larger than both the width W351b of the first cathode channel 351b and the width W352b of the second cathode channel 352b.

  As described above, the single cell 100b of the second embodiment has various features similar to those of the single cell 100 of the first embodiment described above, and as a result, has various advantages similar to those of the first embodiment. is doing. In addition to the same features as the first embodiment, the following features are provided. The first characteristic point is that the gas flow direction is opposite between the second anode channel 252 and the first cathode channel 351b facing (overlapping) with the electrolyte membrane 30 interposed therebetween (FIG. 6). FIG. 8).

  By the way, the local water content in the anode diffusion layer 10 is higher in the second region A22 facing the downstream side than in the first region A21 (FIG. 8) facing the upstream side of the second anode channel 252. Tend to be more. Similarly, the local water content in the cathode diffusion layer 50 is larger in the second region C12b facing the downstream side than in the first region C11b facing the upstream side of the first cathode channel 351b. There is a tendency. Here, the direction of gas flow is opposite between the second anode channel 252 and the first cathode channel 351b. Accordingly, the second regions A22 and C12b having a relatively large amount of water in the diffusion layers 10 and 50 and the first regions A21 and C11b having a relatively small amount of water face each other with the electrolyte membrane 30 interposed therebetween. That is, it is possible to further improve the balance between the local moisture content distribution on the anode side and the local moisture content distribution on the cathode side. Then, in the single cell 100b, it is further suppressed that the variation in the local moisture content of the electrolyte membrane 30 becomes large. As a result, the single cell 100b of the second embodiment has an advantage that it is possible to further suppress the local variation in the amount of power generation in the electrodes 20 and 40.

  The second feature point is that the end part of the second cathode channel 352b (FIG. 7) provided with the second opening 352bo and the first anode channel 251 (FIG. 3) in the four ends of the separator 60b. ) In which the first opening 251o is provided is located on the same side (in the example of FIGS. 3 and 7, on the left side (opposite to the x direction)). As a result, the gas flow directions in the flow paths 251 and 352b can be opposite to each other when viewed from the direction in which the layers overlap without complicatedly bending the two types of flow paths 251 and 352b. There is.

  As described above, the features and advantages of the second anode channel 252 and the first cathode channel 351b have been described. However, both the first anode channel 251 and the second cathode channel 352b have the same features and advantages. Yes. For example, the first region A11 on the upstream side of the first anode channel 251 (FIG. 8) and the second region C22b on the downstream side of the second cathode channel 352b face each other, and the downstream side of the first anode channel 251. The second region A12 and the first region C21b on the upstream side of the second cathode channel 352b face each other.

  In the second embodiment, in the separator 60b, the first opening 251o (FIG. 3) into which the anode-side gas flows and the second opening 352bo (FIG. 7) from which the cathode-side gas is discharged are divided into the separator 60b. (In the example of FIGS. 3 and 7, the end on the left side (the direction opposite to the x direction)). Further, the second opening 252o (FIG. 3) through which the anode side gas is discharged and the first opening 351bo (FIG. 7) through which the cathode side gas flows are provided at the end on the same side of the separator 60b. (In the example of FIGS. 3 and 7, the end on the right side (x direction)). That is, the upstream end portion (the left end portion (reverse direction in the x direction)) of the anode assembly 70b (FIG. 3) and the downstream end portion (left side (reverse direction in the x direction) of the cathode assembly 80b (FIG. 7) ) With the electrolyte membrane 30 in between. Also, the downstream end (right side (x direction) end) of the anode assembly 70b (FIG. 3) and the upstream end (right side (x direction) end) of the cathode assembly 80b (FIG. 7). Opposite to each other with the electrolyte membrane 30 interposed therebetween. As a result, it is possible to suppress a local variation in the water content of the electrolyte membrane 30 between the upstream side and the downstream side of the assemblies 70b and 80b. That is, there is an advantage that it is possible to suppress a local variation in the amount of power generation between the upstream side and the downstream side of the assemblies 70b and 80b.

C. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

Modification 1:
In each of the above embodiments, the “anode-side flow path forming layer” and the “cathode-side flow path forming layer” are formed integrally with one separator 60, 60b, 60c, but formed separately from each other. May be. Further, in each of the above embodiments, the electric power generated by the power generation is supplied to the external load via the separators 60, 60b, and 60c, but may be supplied without the separators 60, 60b, and 60c. That is, the flow path forming layer may be formed of an electrically nonconductive material. The same applies to the separator. Further, the separator may be provided with a cooling medium flow path through which a cooling medium (for example, cooling water) for cooling the fuel cell 100 flows. Further, the anode side separator and the cathode side separator may be formed separately. In this case, a cooling medium flow path may be provided between the anode-side separator and the cathode-side separator.

Modification 2:
FIG. 9 is an explanatory diagram showing a modification of the single cell. FIG. 9 shows a cross-sectional view of the single cell 100c similar to FIG. This single cell 100c has a configuration in which the electrolyte membrane 30 is sandwiched between an anode assembly 70c and a cathode assembly 80c, similarly to the second embodiment 100b shown in FIG. The only difference from the single cell 100b of the second embodiment is that the width of the second gas channel is set to a value wider than the width of the first gas channel on each of the anode side and the cathode side. is there. Specifically, the width W252c of the second anode channel 252c is set to a value wider than the width W251c of the first anode channel 251c. The width W352c of the second cathode channel 352c is set to a value wider than the width W351c of the first cathode channel 351c. Thus, if the width of the discharge flow path (second gas flow path) is made wider than the width of the inflow flow path (first gas flow path), the gas flow in the single cell 100c should be smooth. Can do.

  In the example of FIG. 9, the width W222c of the main wall 222c is set to a value wider than both the width W251c of the first flow path 251c and the width W252c of the second flow path 252c adjacent to the main wall 222c. Has been. Similarly, the width W322c of the main wall 322c is set to a value wider than both the width W351c of the first flow path 351c adjacent to the main wall 322c and the width W352c of the second flow path 352c. Therefore, as in the above embodiments, gas diffusion by the gas diffusion layers 10 and 50 can be made more effective. In addition, the contact area between the gas diffusion layers 10 and 50 and the separator 60c can be prevented from becoming excessively small.

  As in the example of FIG. 9, when the widths of the gas channel pairs facing each other across the electrolyte membrane 30 are different on the anode side and the cathode side, when viewed from the overlapping direction of the layers In addition, it is preferable that the centers of the respective flow paths overlap (coincide). For example, in the example of FIG. 9, the center C252c of the second anode channel 252c and the center C351c of the first cathode channel 351c overlap. Further, the center C251c of the first anode channel 251c and the center C352c of the second cathode channel 352c overlap. In this way, it is possible to balance the arrangement of the gas flow path on the anode side and the arrangement of the gas flow path on the cathode side, so that the local moisture content distribution on the anode side and the local distribution on the cathode side It is possible to improve the balance with the distribution of a proper amount of water.

Modification 3:
In each of the above embodiments, on each of the anode side and the cathode side, each of the main wall and the first gas channel and the second gas channel sandwiching the main wall is formed in a straight line, It may be bent along the way. Further, the first gas channel and the second gas channel may not be parallel. Further, the plurality of first gas flow paths may not be parallel to each other, and the plurality of second gas flow paths may not be parallel to each other. However, it is preferable that the first gas channel and the second gas channel are formed so as to be lined up with a wall (main wall) interposed therebetween. That is, it is preferable that the first gas channel and the second gas channel are formed so as to run side by side with the main wall interposed therebetween. Here, “two flow paths run in parallel” is not limited to the case where the flow paths extend in parallel to each other, but the case where one flow path extends obliquely with respect to the other flow path, Means a broad concept including a case where the channel has a curved shape and a case where each channel extends while changing its width. The angle formed between the direction in which the first gas channel extends and the direction in which the second gas channel extends is preferably small, and the first gas channel and the second gas channel are formed in parallel to each other. It is particularly preferable. By so doing, it is possible to suppress an increase in local flow rate variation of the gas flowing under the main wall of the gas diffusion layer, and to suppress an increase in local power generation amount variation. Note that “the first gas flow path and the second gas flow path are formed in parallel” means that the gas flow direction in each gas flow path is the same or opposite, It is not limited to the case where the gas flow paths are formed in a straight line and in parallel.For example, it means a broad concept including cases where both of them meander or bend, and the width of each gas flow path changes along the path. ing.

Modification 4:
In the first embodiment and the second embodiment, the widths of the first gas flow paths 251, 351, 351 b and the second gas flow paths 252, 352, 352 b are the same in the same electrode, but are different. Also good. Further, in the same electrode, the width of each first gas channel may be different for each channel, and the width of each second gas channel may be different for each channel. Further, the width of the first gas channel may be different between the anode side and the cathode side, and the width of the second gas channel may be different between the anode side and the cathode side. Moreover, each gas flow path may be bent in the middle, and the width of each gas flow path may be changing along the path | route.

  In general, as the configuration of the first anode channel and the second cathode channel, any configuration that is opposed to each other with the electrolyte layer interposed therebetween can be adopted. Here, it is preferable that the first anode channel and the second cathode channel are formed so as to run in parallel at positions facing each other with the electrolyte layer interposed therebetween. Note that the fact that the gas flow paths run parallel to each other across the electrolyte layer is not limited to the case where the gas flow paths overlap exactly when viewed along the overlapping direction of the layers. This means a broad concept including a case where only a part of each gas flow path is overlapped in the route to be traced. The same applies to the configurations of the second anode channel and the first cathode channel.

  Here, the first and second anode flow paths and the first and second cathode flow paths are preferably formed as follows. That is, the first and second anode flow paths are formed in parallel, the first and second cathode flow paths are formed in parallel, and the first anode flow path and the second cathode flow path are formed of an electrolyte layer. Preferably, the second anode flow path and the first cathode flow path are formed so as to run in parallel at positions facing each other with the electrolyte layer interposed therebetween. If each flow path is formed in this manner, the main wall on the anode side sandwiched between the first and second anode flow paths and the main wall on the cathode side sandwiched between the first and second cathode flow paths. Has the following configuration. In other words, the main wall on the anode side and the main wall on the cathode side run side by side at opposite positions across the electrolyte. Here, the fact that the main walls run parallel to each other across the electrolyte layer is not limited to the case where the main walls overlap exactly when viewed along the overlapping direction of the layers, but the path that the main walls follow This means a broad concept including a case where there is a portion where only a part of each main wall overlaps.

  Here, the width of the main wall may be different between the anode side and the cathode side. In the same electrode, the width of the main wall may be different for each main wall. Further, the main wall may be bent halfway. For example, in the first embodiment shown in FIG. 2, each main wall 222 may be displaced in the y direction by a length of 1/3 of the width W352.

  As in the above embodiments, the main wall and the first gas flow path and the second gas flow path adjacent to the main wall are formed linearly on each of the anode side and the cathode side. Is preferred. By doing so, the flow path forming layer can be easily processed. Further, as in the above embodiments, it is preferable to provide a plurality of combinations of the main wall and the first gas channel and the second gas channel adjacent to the main wall on each of the anode side and the cathode side. . In this way, the supply and discharge of the gas to and from the gas diffusion layer are performed by a plurality of flow paths. Therefore, it is possible to suppress the local variation in the amount of moisture in the gas diffusion layer and to reduce the local power generation amount. Increase in variation can be suppressed.

Modification 5:
In each of the anode side and the cathode side, the width of the main wall is set to a value narrower than at least one of the width of the first gas passage and the width of the second gas passage adjacent to the main wall. Also good. However, if the width of the main wall is set to a value wider than any of the widths of the gas flow paths on both sides of the main wall as in the above embodiments, the gas diffusion effect by the gas diffusion layer can be reduced. It becomes possible to raise more. Furthermore, it is possible to prevent the contact area between the gas diffusion layer and the flow path forming layer (in the above embodiments, the separators 60, 60b, and 60c) from becoming excessively small.

  In addition, when at least one of the width of the main wall and the width of the gas flow path changes along the path, the average value of the width of the main wall is the width of the first gas flow path adjacent to the main wall. It is preferable that the average value of the second gas flow path and the average value of the width of the second gas flow path adjacent to the main wall be set to a value wider than both. Here, as the average value of the width of the first gas flow path, for example, the area of the first gas flow path when viewed along the direction in which the gas diffusion layer and the flow path forming layer overlap is the first gas flow path. The value divided by the length of the road can be adopted. Here, as the length of the flow path, for example, the length of the core wire (thin line) obtained by the core line processing (also referred to as thinning process) of the flow path can be employed. The same applies to the average value of the width of the second gas flow path and the average value of the width of the main wall. In addition, it is preferable to calculate the average value of the width | variety of a 1st gas flow path using only the part in parallel with the 2nd gas flow path in a 1st gas flow path. As the parallel running part of the first gas channel, for example, from the part closest to the upstream end of the second gas channel to the downstream end of the first gas channel in the first gas channel Part can be adopted. The same applies to the average value of the width of the second gas flow path. As the parallel running part of the second gas flow path, for example, from the part closest to the downstream end of the first gas flow path to the upstream end of the second gas flow path in the second gas flow path Part can be adopted. The average value of the width of the main wall is preferably calculated using only the portion of the main wall sandwiched between the parallel portion of the first gas flow path and the parallel portion of the second gas flow path. . On the other hand, the width of the main wall at an arbitrary position on the path of the main wall may be set to a value wider than any of the widths of the gas flow paths on both sides at the position.

Modification 6:
In each of the above-described embodiments, a solid polymer electrolyte was used as the electrolyte. In addition to this, various types of electrolytes such as a solid oxide electrolyte, a phosphate electrolyte, an alkaline aqueous electrolyte, and a molten carbonate electrolyte were used. Can be adopted. However, if an electrolyte that uses water for power generation (for example, a solid polymer electrolyte) is employed, it is possible to prevent the variation in local water content of the electrolyte layer from becoming excessively large. Therefore, the effect of suppressing the local variation in the amount of power generation at the electrode is significant.

The perspective view which shows the structure of the fuel cell (single cell) 100 as one Example of this invention. Sectional drawing which looked at the single cell 100 along the x direction. The sectional view which looked at the anode side of separator 60 along the direction opposite to the z direction. Sectional drawing which looked at the cathode side of the separator 60 along the direction opposite to z direction. The perspective view which looked at the single cell 100 along the direction opposite to z direction. Sectional drawing which looked at the fuel cell (single cell) 100b in 2nd Example along the x direction. Sectional drawing which looked at the cathode side of the separator 60b along the direction opposite to z direction. The perspective view which looked at the single cell 100b along the direction opposite to z direction. Explanatory drawing which shows the modification of a single cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Anode diffusion layer 20 ... Anode catalyst layer 30 ... Electrolyte membrane 40 ... Cathode catalyst layer 50 ... Cathode diffusion layer 60, 60b, 60c ... Separator 70, 70b, 70c ... .Anode assembly 80, 80b, 80c ... Cathode assembly 100, 100b, 100c ... Fuel cell (single cell)
220 ... Inner wall 222, 222c ... Main wall 224,226 ... Projecting wall 228 ... Folding wall 240 ... Outer wall 251,251c ... First anode flow path 251o ... First opening 252, 252c ... second anode flow path 252o ... second opening 262 ... inflow opening 264 ... discharge opening 320, 320b ... inner wall 322, 322b, 322c ... main wall 324, 324b ... projecting walls 326, 326b ... projecting walls 328, 328b ... folded walls 340, 340b ... outer walls 351, 351b, 351c ... first cathode flow paths 351o, 351bo ... first openings 352, 352b, 352c ... second cathode flow path 352o, 352bo ... second opening 362,362b ... inflow opening 364,364b ... discharge opening

Claims (5)

A fuel cell,
An electrolyte layer;
An anode electrode and a cathode electrode arranged so as to sandwich the electrolyte layer;
An anode-side separator and a cathode-side separator disposed so as to sandwich the electrolyte layer and the electrodes,
An anode-side gas diffusion layer disposed between the anode electrode and the anode-side separator;
An anode-side flow path forming layer disposed between the anode-side gas diffusion layer and the anode-side separator;
A cathode-side gas diffusion layer disposed between the cathode electrode and the cathode-side separator;
A cathode-side flow path forming layer disposed between the cathode-side gas diffusion layer and the cathode-side separator;
With
Each of the anode side flow path forming layer and the cathode side flow path forming layer is
A first flow path that is formed facing the gas diffusion layer and into which a gas defined for each electrode flows;
A second flow path formed facing the gas diffusion layer and exhausting the gas;
A partition that contacts the gas diffusion layer and separates the first flow path and the second flow path;
Each of the downstream side of the first channel and the upstream side of the second channel is closed by the partition wall,
The first flow path on the anode side and the second flow path on the cathode side are configured to face each other with the electrolyte layer interposed therebetween,
The second flow path on the anode side and the first flow path on the cathode side are configured to face each other with the electrolyte layer interposed therebetween.
Fuel cell. The fuel cell according to claim 1,
When viewed along the overlapping direction of the layers,
The flow directions of the gas in each of the first flow path on the anode side and the second flow path on the cathode side that overlap each other are opposite to each other,
The flow directions of the gas in each of the anode-side second flow path and the cathode-side first flow path that overlap each other are opposite to each other.
Fuel cell. The fuel cell according to claim 2, wherein
One end of the flow path forming layer on the anode side has an inflow opening of the first flow path on the anode side,
One end of the flow channel forming layer on the cathode side has a discharge opening of the second flow channel on the cathode side,
When viewed along the overlapping direction of the layers, the end of the anode-side channel forming layer provided with the inflow opening is the end of the cathode-side channel forming layer provided with the discharge opening. Located on the same side as the
Fuel cell. A fuel cell according to any one of claims 1 to 3,
In each of the anode side flow path forming layer and the cathode side flow path forming layer,
The first flow path and the second flow path are formed to run in parallel,
The partition includes a main wall sandwiched between the first flow path and the second flow path that run in parallel,
The average value of the width of the main wall is greater than the average value of the width of the first flow path adjacent to the main wall and the average value of the width of the second flow path adjacent to the main wall. Set to a wide value,
Fuel cell. The fuel cell according to any one of claims 1 to 4, wherein
The fuel cell is a fuel cell, wherein the electrolyte layer is formed using a solid polymer electrolyte.

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