JP2012049007A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology to improve the power generation efficiency of a fuel cell system.SOLUTION: A fuel cell system 100 comprises a membrane electrode assembly 10 and separators 20 and 30 holding the membrane electrode assembly 10 therebetween. The separators 20 and 30 are provided with parallel supply channels 23 and 33 and parallel exhaust channels 25 and 35 in the form of covered channels spatially separated from each other. Electrode layers 2 and 3 of the membrane electrode assembly 10 contain gas diffusing layers 5. The gas diffusing layers 5 have channel regions GA overlapping the channels 23, 33, 25, or 35 and channel wall regions WA overlapping parallel channel walls 29 and 39 in the laminating direction in the fuel cell system 100. In the gas diffusing layers 5, the channel regions GA attain greater ability to diffuse gas than that of the channel wall regions WA with diffusion suppressing parts 6 provided to the channel wall regions WA.

Description

  The present invention relates to a fuel cell.

  Some fuel cells include a membrane electrode assembly that is a power generation body in which electrodes are arranged on both surfaces of an electrolyte membrane that exhibits good proton conductivity in a wet state. In general, the membrane electrode assembly is sandwiched between separators which are conductive and gas-impermeable plate-like members. In addition, the outer surface of the separator is provided with a channel groove that functions as a gas channel for the reactive gas, and the electrode of the membrane electrode assembly is a gas for diffusing the reactive gas over the entire electrode surface (power generation region). A diffusion layer is provided. As the separator channel groove, a supply side channel groove for supplying the reaction gas to the power generation region and a discharge side channel groove for discharging the exhaust gas from the power generation region are spatially sandwiching the channel wall. The one formed so as to be separated is proposed (Patent Document 1, etc.).

  In a fuel cell having such a channel groove, the downstream end of the supply side channel groove is closed, so that most of the reaction gas flowing into the supply side channel groove is diffused in the membrane electrode assembly. Can flow into the bed. Accordingly, it is possible to reduce the amount of unreacted gas that is discharged outside the fuel cell without being used for the power generation reaction. However, in such a fuel cell, there is a tendency that the supply amount distribution of the reactive gas and the power generation amount in the power generation region are not uniform, and the power generation performance has not been sufficiently improved.

JP 2004-079457 A Japanese Patent Laid-Open No. 2004-342483 JP 2005-116179 A

  An object of the present invention is to provide a technique for improving the power generation performance of a fuel cell.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A fuel cell, for supplying a membrane electrode assembly in which electrode layers are arranged on both sides of an electrolyte membrane, two separators sandwiching the membrane electrode assembly, and a reactive gas to the membrane electrode assembly A supply manifold and a discharge manifold for discharging exhaust gas from the membrane electrode assembly, wherein the electrode layer is provided on a side in contact with the electrolyte membrane, and a side in contact with the separator And at least one of the two separators for a reaction gas connected to the supply manifold on a surface in contact with the gas diffusion layer. A supply-side channel groove, a discharge-side channel groove for exhaust gas connected to the discharge manifold, and a channel partition wall that separates the supply-side channel groove and the discharge-side channel groove. The supply side channel groove and the front The discharge-side channel groove is spatially separated from each other across the channel partition when disposed on the outer surface of the gas diffusion layer, thereby causing the reaction gas in the supply-side channel groove to flow. The electrode layer is configured to flow into the gas diffusion layer, and the electrode layer has the supply-side flow channel groove or the discharge of the separator when the fuel cell is viewed along the stacking direction of the electrode layer. A channel groove region that overlaps with the side channel groove, and a channel wall region that overlaps with the channel partition wall, and the electrode layer includes the channel groove in at least one of the gas diffusion layer and the catalyst layer. A fuel cell configured such that the region has higher gas diffusibility than the flow path wall region.
According to this fuel cell, the reaction gas is prevented from flowing from the supply side channel groove to the discharge side channel groove via the gas diffusion layer without passing through the catalyst layer, The amount of reaction gas that reaches the catalyst layer in the groove region can be increased. In other words, by providing the separator with the supply-side channel groove and the discharge-side channel groove, in the fuel cell in which the reaction gas consumption efficiency is improved, the distribution property of the reaction gas to the catalyst layer in the power generation region can be improved. The power generation performance of the fuel cell can be improved.

[Application Example 2]
The fuel cell according to Application Example 1, wherein in the electrode layer, the content of the catalyst in the catalyst layer is higher in the flow channel wall region than in the flow channel groove region.
According to this fuel cell, by increasing the catalyst content in the channel wall region, the amount of power generation in the channel wall region is increased even when the flow rate of the reaction gas in the channel wall region is large. Thus, the amount of the reaction gas flowing out from the catalyst layer in the channel groove region without being used for the power generation reaction can be reduced. Therefore, the power generation performance of the fuel cell can be improved.

[Application Example 3]
The fuel cell according to Application Example 1 or Application Example 2, wherein the flow path wall region of the gas diffusion layer has a gas diffusibility lower than that of the flow channel region, A diffusion suppression member that suppresses diffusion is disposed at a portion in contact with the flow path wall of the separator, and the diffusion suppression member functions as a guide wall for guiding the reaction gas in the flow path groove to the catalyst layer. A fuel cell.
According to this fuel cell, since the reaction gas is guided to the lower layer region in the channel groove region by the diffusion suppressing member, the amount of the reaction gas reaching the catalyst layer in the channel groove region is increased. be able to.

  The present invention can be realized in various forms, for example, in the form of a fuel cell, a fuel cell system including the fuel cell, a vehicle equipped with the fuel cell system, and the like. .

Schematic which shows the structure of a fuel cell. Schematic for demonstrating the structure of a membrane electrode assembly. The schematic sectional drawing for demonstrating the structure of a membrane electrode assembly. Schematic which shows the structure of an anode separator. Schematic which shows the structure of a cathode separator. Schematic for demonstrating the structure of a spreading | diffusion suppression part, and its function. Schematic which shows the structure of the fuel cell as another structural example in 1st Example. Schematic which shows the structure of the fuel cell as another structural example in 1st Example. Schematic which shows the structure of the membrane electrode assembly used for the fuel cell of 2nd Example. Schematic which shows the structure of the fuel cell of 2nd Example. Schematic which shows the structure of the fuel cell as another structural example in 2nd Example. Schematic which shows the structure of the fuel cell as another structural example in 2nd Example. Schematic which shows the structure of the fuel cell as 3rd Example, and the schematic diagram which shows catalyst carrying | support carbon and a polymer electrolyte. The schematic diagram which shows an example of the formation process of the catalyst layer in 3rd Example in process order. The schematic diagram which shows the structure of the fuel cell as a 4th Example, and the schematic diagram which shows catalyst carrying | support carbon and a polymer electrolyte. Schematic which shows the structure of the fuel cell as another structural example in 4th Example. Schematic which shows the structure of the fuel cell as a 5th Example.

A. First embodiment:
FIG. 1 is a schematic diagram showing the configuration of a fuel cell as an embodiment of the present invention. The fuel cell 100 is a polymer electrolyte fuel cell that generates power by receiving supply of hydrogen and oxygen as reaction gases. The fuel cell 100 has a stack structure in which a plurality of single cells 110 that are power generators are stacked. The single cell 110 includes a membrane electrode assembly 10 and an anode separator 20 and a cathode separator 30 that sandwich the membrane electrode assembly 10 from both sides. In addition, on the surface of the two separators 20 and 30 on the membrane electrode assembly 10 side, a flow channel groove for reactive gas (illustrated by a broken line) is provided. The configuration of the channel groove will be described later.

  2 and 3 are schematic views for explaining the configuration of the membrane electrode assembly 10. FIG. 2 is a schematic view showing the configuration of the anode side surface of the membrane electrode assembly 10. The configuration of the cathode side surface of the membrane electrode assembly 10 is the same as the configuration on the anode side, and therefore illustration and description thereof are omitted. 3 is a schematic cross-sectional view of the membrane electrode assembly 10 taken along the line 3-3 shown in FIG.

  The membrane electrode assembly 10 includes a power generation region 11 to which a reaction gas is supplied and a power generation reaction is performed, and an outer peripheral seal portion 12 provided on the outer periphery of the power generation region 11 (FIG. 2). In the power generation region 11 of FIG. 2, for the sake of convenience, a projected image obtained by projecting the flow channel grooves provided in the anode separator 20 in the stacking direction of the fuel cell 100 is shown by broken lines.

  Here, the power generation region 11 includes an electrolyte membrane 1 that exhibits good proton conductivity in a wet state, and electrode layers (anode 2 and cathode 3) disposed on both sides of the electrolyte membrane 1 (FIG. 3). Each of the anode 2 and the cathode 3 has a laminated structure, and includes a catalyst layer 4 disposed on the electrolyte membrane 1 side and a gas diffusion layer 5 disposed on the catalyst layer 4. The electrolyte membrane 1 can be constituted by, for example, an ion exchange membrane having proton conductivity formed of a fluorine-based resin.

  The catalyst layer 4 is formed using a catalyst ink that is a mixed solution in which a catalyst-supporting carbon and a polymer electrolyte that is the same type of compound as the electrolyte membrane 1 are dispersed in a water-soluble solvent or an organic solvent. Specifically, the catalyst layer 4 can be formed by transferring a thin film layer formed by applying and drying the catalyst ink to the outer surface of the film substrate to the outer surface of the electrolyte membrane 1. Alternatively, the catalyst layer 4 may be formed by directly applying and drying the catalyst ink on the outer surface of the electrolyte membrane 1. For example, platinum (Pt) can be used as the catalyst.

  The gas diffusion layer 5 can be composed of a porous base material (for example, a carbon fiber base material or a graphite fiber base material) having conductivity and gas diffusibility. The gas diffusion layer 5 is formed by bonding such a porous base material to the catalyst layer 4 formed on the outer surface of the electrolyte membrane 1 by hot pressing or the like. A water repellent layer such as a microporous layer may be formed in advance on the surface of the base material constituting the gas diffusion layer 5 that is disposed on the catalyst layer 4 side.

  By the way, in the fuel cell 100 of the present embodiment, the base material 6 having a lower gas diffusibility than the base material constituting the gas diffusion layer 5 is provided on the outer surface of the gas diffusion layer 5. It is arrange | positioned in the position corresponding to this arrangement position. Hereinafter, the base material 6 having a low gas diffusibility is referred to as a “diffusion suppression unit 6”.

  Here, “gas diffusibility” in the present specification is a degree representing ease of gas movement inside a gas permeable member such as a porous member. The gas diffusibility can be adjusted by the porosity and the porosity of the porous member. The gas diffusivity can also be expressed by the air permeability of the porous member. Here, “air permeability” refers to a plate-like (film-like) fiber base material or porous base material, which gives a predetermined pressure difference between one surface side and the other surface side. Sometimes, the value can be obtained as the amount per unit time of the gas passing through the substrate in the thickness direction. The specific formation position and function of the diffusion suppressing unit 6 will be described later.

  The outer peripheral seal portion 12 is formed by disposing a resin member so that the outer peripheral end surfaces of the electrolyte membrane 1 and the electrode layers 2 and 3 are covered. The outer peripheral seal portion 12 is held between the separators 20 and 30 and suppresses leakage of the reaction gas to the outside of the fuel cell 100. Manifolds M <b> 1 to M <b> 4 for reaction gas are formed in the outer peripheral seal portion 12 as through holes that penetrate the thickness direction.

  The manifolds M <b> 1 to M <b> 4 are arranged such that the hydrogen flow direction and the oxygen flow direction in the power generation region 11 face each other and cross each other with the electrolyte membrane 1 interposed therebetween. Specifically, the hydrogen supply manifold M1 and the oxygen discharge manifold M4 are arranged on the same side (left side in the drawing) with respect to the power generation region 11, and the hydrogen discharge manifold M2 and the oxygen supply manifold M3 are They are arranged on the opposite side (right side of the page).

  The hydrogen supply manifold M1 and the hydrogen discharge manifold M2 are formed at positions diagonal to each other across the power generation region 11. The oxygen supply manifold M3 and the oxygen discharge manifold M4 have the same arrangement configuration. In addition, the arrangement configuration of each manifold M1-M4 may be another configuration. In addition to the manifolds M1 to M4 for the reaction gas, a manifold for the refrigerant may be formed in the outer peripheral seal portion 12.

  Here, in this specification, the hydrogen supply manifold M1 side in the anode power generation region 11 or the oxygen supply manifold M3 side in the cathode power generation region 11 is referred to as an “upstream side”, respectively. The hydrogen discharge manifold M2 side in the anode-side power generation region 11 or the oxygen discharge manifold M4 side in the cathode-side power generation region 11 is referred to as a “downstream side”, respectively. Further, in each of the power generation regions 11 on the anode side and the cathode side, the direction from the upstream side to the downstream side is referred to as “reactive gas flow direction”.

  FIG. 4 is a schematic diagram showing the configuration of the anode separator 20. FIG. 4 shows a surface of the anode separator 20 on the side in contact with the anode 2. FIG. 4 shows an arrow indicating the flow of hydrogen in the flow channel provided in the anode separator 20. Also, in FIG. 4, a region that overlaps the power generation region 11 of the membrane electrode assembly 10 when viewed along the stacking direction of the fuel cell 100 is illustrated by a one-dot chain line.

  The anode separator 20 can be composed of a conductive gas-impermeable plate member (for example, a metal plate). Similar to the membrane electrode assembly 10, manifolds M <b> 1 to M <b> 4 for reaction gases are formed as through holes in the anode separator 20. The anode separator 20 is formed with a flow channel for the reaction gas over the entire power generation region 11.

  The anode separator 20 has a “supply-side channel groove” (also referred to as a “primary channel groove”) for supplying hydrogen to the power generation region 11 as a channel groove for the reaction gas, and a hydrogen from the power generation region 11. And a “discharge-side channel groove” (also referred to as a “secondary channel groove”). Here, when the flow path groove of the anode separator 20 is assembled to the fuel cell 100, the opening above the groove (groove opening) is the gas diffusion layer 5 on the anode side of the membrane electrode assembly 10 and the diffusion suppression. Blocked by part 6. At this time, the supply-side channel groove and the discharge-side channel groove are spatially separated from each other with the channel partition wall interposed therebetween.

  The anode separator 20 is provided with a supply-side communication channel groove 21, a distribution channel groove 22, and a plurality of supply-side parallel channel grooves 23 as supply-side channel grooves. The supply side communication channel groove 21 is a channel groove that connects and communicates the hydrogen supply manifold M1 and the distribution channel groove 22 provided in the power generation region 11, and generates hydrogen from the hydrogen supply manifold M1. Inflow into region 11.

  The distribution channel groove 22 is a channel groove formed at the upstream end of the power generation region 11 over the entire region in the direction orthogonal to the flow direction of the reaction gas in the power generation region 11. Each supply-side parallel flow channel 23 is connected to the distribution flow channel 22. The distribution channel groove 22 distributes the hydrogen flowing in from the supply side communication channel groove 21 in a direction orthogonal to the flow direction of the reaction gas in the power generation region 11 and branches to each supply side parallel channel groove 23. Let it flow.

  Each supply-side parallel flow channel 23 is a linear flow channel extending along the flow direction of the reaction gas, and is arranged in parallel at substantially equal intervals in the power generation region 11. The supply-side parallel flow channel 23 has an upstream end connected to the distribution flow channel 22 and a downstream end closed before the joining flow channel 26 of the discharge flow channel. That is, the supply side parallel flow channel 23 is configured as a so-called substantially comb-shaped flow channel.

  The anode separator 20 is provided with a plurality of discharge side parallel flow grooves 25, a merging flow path groove 26, and a discharge side communication flow path groove 27 as discharge side flow path grooves. Each discharge-side parallel flow channel 25 is a linear flow channel that runs in parallel with the supply-side parallel flow channel 23 in the power generation region 11, and reacts with the reaction gas from the upstream region to the downstream region. It extends along the flow direction and is connected to the merging channel groove 26. The upstream end of each discharge-side parallel flow channel 25 is closed at a position substantially the same as the upstream start end of the supply-side parallel flow channel 23.

  Here, the supply side parallel flow channel grooves 23 and the discharge side parallel flow channel grooves 25 are alternately arranged in a direction perpendicular to the flow direction of the reaction gas. That is, the supply-side parallel flow channel 23 and the discharge-side parallel flow channel 25 constitute a substantially comb-shaped flow channel that meshes with each other. In the present specification, the flow channel partitions sandwiched between the supply side parallel flow channel groove 23 and the discharge side parallel flow channel groove 25 are hereinafter referred to as “parallel flow channel partitions 29”, respectively.

  The merge channel groove 26 is a channel groove that extends over the entire region in the direction orthogonal to the flow direction of the reaction gas in the power generation region 11 at the downstream end of the power generation region 11. The discharge side communication flow channel groove 27 is a flow channel groove for connecting and connecting the merge flow channel groove 26 and the hydrogen discharge manifold M2. The exhaust gas in each discharge side parallel flow channel 25 joins in the merge flow channel groove 26 and is discharged to the hydrogen discharge manifold M2 through the discharge side communication flow channel groove 27.

  FIG. 5 is a schematic view showing the configuration of the cathode separator 30. FIG. 5 shows a surface of the cathode separator 30 on the side in contact with the cathode 3. Like FIG. 4, an arrow indicating the flow of oxygen in the cathode separator 30 and a point indicating an area overlapping the power generation area 11 are shown. A chain line is illustrated. Similarly to the anode separator 20, the cathode separator 30 is composed of a gas-impermeable plate member having conductivity, and manifolds M1 to M4 for reaction gas are formed.

  Further, similarly to the anode separator 20, the cathode separator 30 is formed with a supply-side flow channel and a discharge-side flow channel that are separated from each other. Specifically, the cathode separator 30 has oxygen as a supply-side flow channel having the same configuration as the supply-side communication flow channel 21, the distribution flow channel 22, and the supply-side parallel flow channel 23 of the anode separator 20. A supply-side communication channel groove 31, a distribution channel groove 32, and a supply-side parallel channel groove 33 are provided.

  Further, the cathode separator 30 has a discharge side parallel flow having the same configuration as the discharge side parallel flow channel 25, the merge flow channel groove 26, and the discharge side communication flow channel groove 27 of the anode separator 20 as a discharge side flow channel. A channel groove 35, a merging channel groove 36, and a discharge side communication channel groove 37 are provided. In the cathode separator 30, the flow path partition sandwiched between the supply side parallel flow path groove 33 and the discharge side parallel flow path groove 35 is similar to the parallel flow path partition 29 of the anode separator 20. 39 ".

  Thus, in the fuel cell 100 of the present embodiment, the flow channel grooves of the separators 20 and 30 are configured as closed flow channel grooves in which the supply side flow channel grooves and the discharge side flow channel grooves are separated from each other. . Accordingly, the reaction gas flowing from the manifolds M1 and M3 into the supply-side flow channel flows into the discharge-side flow channel through the electrode layers 2 and 3. That is, according to the fuel cell 100 of the present embodiment, most of the reaction gas in the supply-side flow channel can be allowed to flow into the electrode layers 2 and 3, so that it is not used for the reaction. The amount of unreacted gas discharged can be reduced.

  Furthermore, in the fuel cell 100 of the present embodiment, the gas diffusion layer 5 includes the diffusion suppressing unit 6 to increase the amount of the reaction gas used for the power generation reaction and improve the reaction gas consumption efficiency. Here, in this specification, “reaction gas consumption efficiency” means the ratio of the amount of reaction gas used in the fuel cell reaction to the amount of reaction gas supplied. Below, the specific structure and function of the diffusion suppressing unit 6 will be described.

  FIG. 6A is a schematic diagram for explaining the configuration and function of the diffusion suppressing unit 6 in the fuel cell 100 of the present embodiment. 6A shows a schematic cross section of an arbitrary unit cell 110 at the same cutting site as the 6-6 cutting shown in FIG. In FIG. 6A, arrows schematically showing the flow of the reaction gas flowing from the supply side parallel flow channel grooves 23 and 33 into the gas diffusion layer 5 are shown.

  Here, in the fuel cell 100 of the present embodiment, when the membrane electrode assembly 10 is sandwiched between the two separators 20 and 30, the parallel channel partition walls 29 and 39 of the separators 20 and 30 are membranes of each other. The electrode assemblies 10 are opposed to each other. The supply side parallel flow channel grooves 23 and 33 and the discharge side parallel flow channel grooves 25 and 35 face each other with the membrane electrode assembly 10 interposed therebetween. In this specification, when viewed along the stacking direction of the fuel cell 100, an area overlapping with the parallel flow path partition walls 29 and 39 is referred to as a “flow path wall area WA”, and the supply side parallel flow path grooves 23 and 33 or An area overlapping with the discharge side parallel flow grooves 25 and 35 is referred to as a “flow groove area GA”.

  The diffusion suppressing portion 6 is formed in the channel groove region GA in the gas diffusion layer 5 (FIG. 2), and contacts the parallel channel partition walls 29 and 39 and enters the gas diffusion layer 5. (FIG. 6A). In the fuel cell 100 of the present embodiment, the diffusion suppressing portion 6 is provided in the flow path wall area WA, so that the gas diffusibility in the electrode layers 2 and 3 is greater in the flow path groove area GA than in the flow path wall area WA. Is also high.

  The diffusion suppressing unit 6 may be formed by impregnating the resin member into the pores of the gas diffusion layer 5. Alternatively, the diffusion suppression unit 6 is provided by disposing a member having a lower gas diffusibility than the base material of the gas diffusion layer 5 in a recess formed in advance on the outer surface of the gas diffusion layer 5. Also good.

  Hydrogen or oxygen in the supply side parallel flow channel grooves 23 and 33 is guided to the parallel flow channel partition walls 29 and 39 and the wall surface of the diffusion suppression unit 6 (the boundary surface between the gas diffusion layer 5 and the diffusion suppression unit 6), and gas It flows into the diffusion layer 5 and diffuses. That is, the diffusion suppressing unit 6 can be interpreted as a reaction gas guiding wall portion in which the parallel flow path partition walls 29 and 39 are extended to the inside of the gas diffusion layer 5.

  FIG. 6B is a schematic diagram showing a configuration of a fuel cell 100a as a comparative example of the present invention. FIG. 6B shows that the diffusion suppression unit 6 is omitted, the arrows indicating the flow of the reaction gas are different, and the region SA in which the supply amount of the reaction gas is relatively small is illustrated. Is substantially the same as FIG. That is, the configuration of the fuel cell 100a of the comparative example is substantially the same as that of the fuel cell 100 of the present embodiment except for the gas diffusion layer 5.

Here, it is known that the flow rate distribution of the reaction gas in the anode 2 and the cathode 3 follows Fick's first law expressed by the following equation (1).
J = −D × ΔC / Δx (1)
J is an amount called a flux and represents the amount of fluid passing through a unit area per unit time. D is a diffusion coefficient. ΔC indicates the concentration gradient of the fluid in a certain region. Δx represents the diffusion distance of the fluid in a certain region. That is, in the anode 2 and the cathode 3, the flow rate of the reaction gas increases as the reaction gas diffusion distance is shorter.

  That is, most of the reaction gas that has flowed into the gas diffusion layer 5 from the supply-side parallel flow channel grooves 23 and 33 flows along the upper surfaces of the parallel flow channel partition walls 29 and 39 through the gas diffusion layer 5 and is discharged adjacently. It flows out to the side parallel flow path grooves 25 and 35. And a part of it diffuses into the catalyst layer 4 and is used for the power generation reaction. Therefore, in the fuel cell 100a of the comparative example, in the catalyst layer 4, the amount of the reaction gas that reaches the area SA near the center in the flow path wall area WA tends to be smaller than in other areas.

  However, in the fuel cell 100 of this embodiment (FIG. 6A), the reaction gas is guided to a lower layer in the gas diffusion layer 5 by the diffusion suppressing unit 6 provided in the gas diffusion layer 5. Thus, it flows to the discharge side parallel flow channel grooves 25 and 35. Therefore, it is possible to suppress the reaction gas from flowing out to the discharge-side flow channel without passing through the catalyst layer 4, and to increase the amount of the reaction gas that reaches the catalyst layer 4 in the flow channel region GA. . Therefore, the amount of reaction gas used for the power generation reaction can be increased.

  Thus, according to the fuel cell 100 of the present embodiment, the closed channel separated into the supply-side channel groove and the discharge-side channel groove, and the gas diffusion layer 5 are provided in accordance with the blocked channel. In addition, since the diffusion suppression unit 6 is provided, the reaction gas consumption efficiency is improved. Therefore, the power generation performance of the fuel cell 100 is improved. Even in the configuration described below, the power generation performance of the fuel cell can be similarly improved.

  7 and 8 are explanatory diagrams for explaining another configuration example in the first embodiment. The fuel cell of each configuration example described below has the same configuration as the fuel cell 100 of the first embodiment except that the configurations of the electrode layers 2 and 3 are different. A closed channel groove in which the supply side channel groove and the discharge side channel groove are divided is provided (FIGS. 4 and 5).

  FIG. 7A is a schematic diagram showing the configuration of a fuel cell 100A as another configuration example in the first embodiment. FIG. 7A is substantially the same as FIG. 6A except that a gas diffusion layer 5 </ b> A is provided instead of the gas diffusion layer 5. In this fuel cell 100A, the gas diffusion layer 5A has a high diffusion layer 5Aa constituted by a base material having high gas diffusibility and a low diffusion layer 5Ab constituted by a base material having low gas diffusibility. .

  The high diffusion layer 5Aa is provided in the channel groove area GA, and the low diffusion layer 5Ab is provided in the channel wall area WA. In the gas diffusion layer 5A, two types of base materials having different air permeability and porosity are prepared in advance as a plurality of strip-shaped base materials in advance, and the strip-shaped base materials having different gas diffusivities are prepared as channel walls. It is good also as what is formed by arranging alternately for every area | region WA and channel groove area | region GA.

  Thus, in the fuel cell 100A of this configuration example, most of the reaction gas flowing into the high diffusion layer 5Aa of the gas diffusion layer 5A from the supply side parallel flow channel grooves 23, 33 is on the boundary surface with the low diffusion layer 5Ab. Along the catalyst layer 4. Therefore, similarly to the fuel cell 100 of the first embodiment, the amount of the reaction gas that reaches the catalyst layer 4 in the flow channel region GA can be increased, and the consumption efficiency of the reaction gas can be improved. . Therefore, the power generation performance of the fuel cell 100A can be improved.

  FIG. 7B is a schematic diagram showing a configuration of a fuel cell 100B as another configuration example in the first embodiment. FIG. 7B is almost the same as FIG. 7A except that the gas diffusion layer 5B is provided in place of the gas diffusion layer 5A and that the arrow indicating the flow of the reaction gas is omitted. The same. In the gas diffusion layer 5 </ b> B of the fuel cell 100 </ b> B, the diffusion suppression unit 6 is provided between the thinned low diffusion layer 5 </ b> Ab and the parallel flow path partition walls 29 and 39 of the separators 20 and 30.

  Even with such a configuration, similarly to the fuel cell 100 of the first embodiment, the amount of the reaction gas that reaches the catalyst layer 4 in the flow channel region GA can be increased. Therefore, the reaction gas consumption efficiency in the fuel cell 100B can be improved, and the power generation performance thereof can be improved.

  FIG. 8 is a schematic diagram showing a configuration of a fuel cell 100C as another configuration example in the first embodiment. In FIG. 8, the diffusion suppressing unit 6 is omitted, the gas diffusion layer 5 similar to that of the fuel cell 100 a of the comparative example (FIG. 6B) is provided, and the catalyst layer 4 </ b> C is replaced with the catalyst layer 4. Except for the difference between the provided point and the arrow indicating the flow of the reactive gas, it is substantially the same as FIG.

  In the fuel cell 100C of this configuration example, the diffusion suppression unit 6 is not provided in the gas diffusion layer 5 as in the fuel cell 100a of the comparative example. However, the catalyst layer 4C of the fuel cell 100C is provided with a high air permeability catalyst layer 4Ca having a high air permeability in the flow channel region GA, and a low air permeability catalyst having a low air permeability in the flow channel wall region WA. A layer 4Cb is provided. With this configuration, the reaction gas can be guided to the high air permeability catalyst layer 4Ca having a high air permeability, and the amount of the reaction gas used for the power generation reaction in the flow channel region GA can be increased.

  The high air permeability catalyst layer 4Ca and the low air permeability catalyst layer 4Cb are contained in a mass ratio (Ionomer / Carbon; I / C) of the polymer electrolyte and the carbon as the conductive carrier for each region of the catalyst layer 4C. It can be formed by adjusting. The high air permeability catalyst layer 4Ca can be formed as a region with low I / C, and the low air permeability catalyst layer 4Cb can be formed as a region with high I / C. More specifically, after forming a catalyst layer having a uniform air permeability for each of the areas GA and WA, the flow path wall area WA is coated and impregnated with a solution containing a polymer electrolyte, thereby providing a flow path. The I / C of the wall area WA may be increased. That is, the high air permeability catalyst layer 4Ca is configured as a catalyst layer having a relatively high gas diffusivity, and the low air permeability catalyst layer 4Cb is configured as a catalyst layer having a relatively low gas diffusivity.

  Thus, by configuring the air permeability in the catalyst layer 4C so that the flow path wall area WA is lower than the flow path groove area GA, the amount of reaction gas consumed in the flow path groove area GA can be reduced. Can be increased. Therefore, the reaction gas consumption efficiency in the fuel cell 100C can be improved, and the power generation performance can be improved. In the fuel cell 100 of the first embodiment and the fuel cells 100A and 100B in other configuration examples, the catalyst layer 4C of the fuel cell 100C may be provided instead of the catalyst layer 4.

B. Second embodiment:
9 and 10 are schematic views for explaining the configuration of a fuel cell 100D as a second embodiment of the present invention. FIG. 9 is a schematic view showing a configuration of a membrane electrode assembly 10D used in the fuel cell 100D of the second embodiment. FIG. 9 is substantially the same as FIG. 2 except that the position of the diffusion suppressing unit 6 is different. The fuel cell 100D of the second embodiment, like the fuel cell 100 of the first embodiment, includes a plurality of membrane electrode assemblies 10D and two separators 20 and 30 (FIGS. 4 and 5). It has a stack structure in which single cells 110 are stacked (FIG. 1).

  FIG. 10 is a schematic diagram showing the configuration of an arbitrary unit cell 110 in the fuel cell 100D of the second embodiment. FIG. 10 is substantially the same as FIG. 6A except that the position of the diffusion suppressing unit 6 is different and the arrow indicating the flow of the reaction gas is different.

  In this fuel cell 100D, the diffusion suppressing portion 6 is provided in the flow channel region GA. The diffusion suppressing unit 6 is configured to have a width smaller than the groove width of the supply-side parallel flow channel grooves 23 and 33 or the discharge-side parallel flow channel grooves 25 and 35, and the supply-side parallel flow channel grooves 23 and 33 or the discharge side. The side parallel flow grooves 25 and 35 are disposed at substantially the center. Therefore, the groove openings of the supply-side parallel flow channel grooves 23 and 33 or the discharge-side parallel flow channel grooves 25 and 35 are closed at the center by the diffusion suppressing unit 6 and are adjacent to the two side portions. Is opened (opened) toward the gas diffusion layer 5.

  That is, in the fuel cell 100D, the opening area of the groove opening for the reaction gas to flow into the gas diffusion layer 5 from the supply side parallel flow channel grooves 23, 33 is reduced by the diffusion suppressing unit 6, and the gas diffusion The pressure loss of the reaction gas when flowing into the layer 5 is increased. Therefore, the flow rate of the reaction gas flowing into the gas diffusion layer 5 can be increased, and the amount of the reaction gas reaching the catalyst layer 4 can be increased.

  Further, in the fuel cell 100D, the opening area of the groove opening for the reaction gas to flow out from the gas diffusion layer 5 to the discharge side parallel flow channel grooves 25 and 35 is also reduced by the diffusion suppressing unit 6. Accordingly, the diffusion of the reaction gas flowing into the gas diffusion layer 5 in the direction other than the outlet direction is promoted, and the amount of the reaction gas used for the reaction in the catalyst layer 4 can be increased.

  As described above, according to the fuel cell 100D of the second embodiment, the diffusion suppressing portion 6 having a low gas diffusibility is provided in a part of the flow path groove region GA of the gas diffusion layer 5, thereby providing the catalyst layer 4. And the amount of reaction gas used for the power generation reaction can be increased. Therefore, the reaction gas consumption efficiency in the fuel cell 100D can be improved, and the power generation performance can be improved.

  The diffusion suppressing unit 6 may not be provided corresponding to all the supply side parallel flow channel grooves 23 and 33 and all of the discharge side parallel flow channel grooves 25 and 35. That is, the diffusion suppressing unit 6 may be provided corresponding to some of the supply side parallel flow channel grooves 23 and 33 and some of the discharge side parallel flow channel grooves 25 and 35. Further, even in the fuel cell having the configuration described below, the power generation performance can be improved as in the fuel cell 100D of the second embodiment.

  FIGS. 11 to 13 are explanatory diagrams for explaining another configuration example in the second embodiment. The fuel cell of each configuration example described below is the same as the fuel cell 100D of the second embodiment except that the configurations of the electrode layers 2 and 3 are different. A channel groove in which the groove and the discharge side channel groove are divided is provided.

  FIG. 11A is a schematic diagram showing a configuration of a fuel cell 100E as another configuration example in the second embodiment. FIG. 11A is different from FIG. 11 except that the diffusion suppressing portion 6 that blocks a part of the groove opening portions of the supply side parallel flow channel grooves 23 and 33 is omitted and the arrow indicating the flow of the reaction gas is different. It is almost the same as FIG.

  As described above, even when the diffusion suppressing portion 6 in the channel groove region GA overlapping the supply side parallel channel grooves 23 and 33 is omitted, the groove opening portions of the discharge side parallel channel grooves 25 and 35 are omitted. A part is blocked by the diffusion suppressing unit 6. Accordingly, diffusion of the reaction gas that has flowed into the gas diffusion layer 5 in the direction other than the outlet direction (the direction toward the discharge-side parallel flow channel grooves 25 and 35) is promoted, and the amount of the reaction gas that reaches the catalyst layer 4 is increased. be able to.

  FIG. 11B is a schematic diagram showing a configuration of a fuel cell 100F as another configuration example in the second embodiment. FIG. 11 (B) is different from FIG. 11 except that the diffusion suppressing portion 6 that blocks a part of the groove opening portions of the discharge side parallel flow channel grooves 25 and 35 is different from the arrow indicating the flow of the reaction gas. It is almost the same as FIG.

  In the fuel cell 100F, the diffusion suppressing portion 6 in the flow channel region GA that overlaps the discharge-side parallel flow channels 25 and 35 is omitted, and part of the groove openings of the supply-side parallel flow channels 23 and 33 are diffused. It is blocked by the suppression unit 6. Even with such a configuration, the flow rate of the reaction gas flowing into the gas diffusion layer 5 can be increased, so that the amount of the reaction gas reaching the catalyst layer 4 can be increased.

  FIG. 12A is a schematic diagram showing a configuration of a fuel cell 100G as another configuration example in the second embodiment. FIG. 12A is substantially the same as FIG. 6A except that a gas diffusion layer 5G is provided instead of the gas diffusion layer 5. The gas diffusion layer 5G of the fuel cell 100G has a high diffusion layer 5Ga constituted by a base material having high gas diffusibility and a low diffusion layer 5Gb constituted by a base material having low gas diffusibility.

  The low diffusion layer 5Gb is provided in a part of the flow channel region GA. More specifically, the low diffusion layer 5Gb is provided in an area similar to the arrangement area of the diffusion suppressing portion 6 in the fuel cell 100D of the second embodiment. On the other hand, the high diffusion layer 5Ga is disposed in the flow path wall area WA and in areas other than the arrangement area of the low diffusion layer 5Gb in the flow path groove area GA. The gas diffusion layer 5G is prepared by preparing two types of base materials having different air permeability and porosity as a plurality of strip base materials in advance, and alternately switching the strip base materials having different gas diffusivities. Can be formed.

  In the fuel cell 100G of this configuration example, most of the reaction gas in the supply side parallel flow channel grooves 23 and 33 flows into the high diffusion layer 5Ga. That is, also in this configuration example, since the groove openings of the supply side parallel flow channel grooves 23 and 33 are narrowed by the low diffusion layer 5Gb, the flow rate of the reaction gas flowing into the high diffusion layer 5Ga is correspondingly increased. Can be increased. Therefore, similarly to the fuel cell 100D of the second embodiment, the amount of the reaction gas that reaches the catalyst layer 4 can be increased.

  Moreover, the pressure loss in the region near the outlet in the gas diffusion layer 5G is increased by the low diffusion layer 5Gb that blocks part of the groove openings of the discharge side parallel flow channel grooves 25 and 35. Therefore, similarly to the fuel cell 100D of the second embodiment, the diffusion of the reactive gas in the gas diffusion layer 5G in the direction other than the outlet direction is promoted, and the amount of the reactive gas used for the reaction in the catalyst layer 4 can be increased. .

  In this configuration example, the low diffusion layer 5Gb provided corresponding to the supply side parallel flow channel grooves 23 and 33 and the low diffusion layer 5Gb provided corresponding to the discharge side parallel flow channel grooves 25 and 35 are provided. Any one of them may be omitted. The low diffusion layer 5Gb may be omitted for some of the supply-side parallel flow grooves 23 and 33 or some of the discharge-side parallel flow grooves 25 and 35.

  FIG. 12B is a schematic diagram showing a configuration of a fuel cell 100H as another configuration example in the second embodiment. FIG. 12B is substantially the same as FIG. 12A except that a gas diffusion layer 5H is provided instead of the gas diffusion layer 5G. In the gas diffusion layer 5H of the fuel cell 100H, the low diffusion layer 5Gb is thinned, and a diffusion suppressing portion having a width similar to that of the low diffusion layer 5Gb is provided between the low diffusion layer 5Gb and the parallel flow path partition walls 29 and 39. 6 is arranged.

  Even with such a configuration, the amount of the reaction gas reaching the catalyst layer 4 can be increased as in the fuel cell 100D of the second embodiment. Therefore, the reaction gas consumption efficiency in the fuel cell 100H can be improved, and the power generation performance can be improved.

C. Third embodiment:
FIG. 13 (A) is a schematic diagram showing the configuration of a fuel cell 100I as a third embodiment of the present invention. FIG. 13A is substantially the same as FIG. 8 except that the catalyst layer 4I is provided in place of the catalyst layer 4C and that the arrow indicating the flow of the reaction gas is omitted. That is, the fuel cell 100I of the third embodiment has the same configuration as the fuel cell 100C described as another configuration example of the first embodiment except that the configuration of the catalyst layer 4I is different. Each of the catalyst layers 4I includes first and second catalyst layers 4Ia and 4Ib having different catalyst contents.

  FIG. 13B is a schematic diagram showing the catalyst-supporting carbon 91 and the polymer electrolyte 93 in the first catalyst layer 4Ia. FIG. 13C is a schematic diagram showing the catalyst-supporting carbon 91 and the polymer electrolyte 93 in the second catalyst layer 4Ib. In the fuel cell 100I, the second catalyst layer 4Ib is configured to have a larger amount of the catalyst 92 supported on the catalyst-supported carbon 91 than the first catalyst layer 4Ia. The first catalyst layer 4Ia is provided in the flow path wall area WA, and the second catalyst layer 4Ib is provided in the flow path groove area GA.

  FIGS. 14A to 14D are schematic views illustrating an example of a process of forming the anode-side catalyst layer 4I in the order of processes. In the first step, the first and second catalyst layers 4Ia and 4Ib are coated and dried on the outer surfaces of the two film bases Fa and Fb, respectively, by applying and drying catalyst inks containing catalyst-carrying carbons having different catalyst loadings. Is formed (FIG. 14A). Then, the film bases Fa and Fb on which the first and second catalyst layers 4Ia and 4Ib are formed are cut, and a plurality of first strip bases 41 and a plurality of second strip bases 42 are obtained. And form.

  In the second step, the first and second strip-shaped base materials 41 and 42 prepared in the first step are alternately arranged (FIG. 14B). In the third step, the arranged first and second strip-shaped base materials 41 and 42 are arranged on the outer surface of the electrolyte membrane 1 and pressed by the roller 200 or the like, so that the first and second catalyst layers are arranged. 4Ia and 4Ib are transferred to the electrolyte membrane 1 (FIG. 14C). After the transfer of the first and second catalyst layers 4Ia and 4Ib, the film bases Fa and Fb are removed (FIG. 14D). The cathode-side catalyst layer 4I can also be formed by the same formation process as described above.

  As described above, according to the fuel cell 100I of the third embodiment, the second catalyst layer 4Ib having a large catalyst content in the flow channel region GA where the amount of the reaction gas reaching the catalyst layer 4I is relatively small. Is provided. As a result, the effective catalyst surface area in the channel groove area GA is increased, and the amount of reaction gas consumed in the channel groove area GA can be improved. Therefore, the reaction gas consumption efficiency in the fuel cell 100I is improved, and the power generation performance can be improved.

D. Fourth embodiment:
FIGS. 15A to 15C are schematic views for explaining the configuration of a fuel cell 100J as the fourth embodiment of the present invention. FIG. 15 (A) is substantially the same as FIG. 13 (A) except that the catalyst layer 4J in which the formation positions of the first and second catalyst layers 4Ia and 4Ib are switched is provided. FIG. 15B is a schematic view similar to FIG. 13C, and shows the catalyst-supporting carbon 91 and the polymer electrolyte 93 in the second catalyst layer 4Ib. FIG. 15C is a schematic view similar to FIG. 13B, and shows the catalyst-supporting carbon 91 and the polymer electrolyte 93 in the first catalyst layer 4Ia.

  In the fuel cell 100J of the fourth embodiment, the first catalyst layer 4Ia with a small amount of catalyst is provided in the flow path groove region GA, and the second catalyst layer 4Ib with a large amount of catalyst is provided in the flow channel wall region WA. It has been. That is, in the fuel cell 100J, the power generation amount in the region is increased by increasing the effective catalyst surface area in the flow path wall region WA where the supply amount of the reaction gas increases. Further, in the channel groove area GA where the supply amount of the reaction gas is reduced, the catalyst utilization efficiency is reduced in the area by reducing the amount of catalyst supported.

  As described above, according to the fuel cell 100J in the fourth embodiment, the reaction gas consumption efficiency is improved in the region where the supply amount of the reaction gas is relatively large, and the supply amount of the reaction gas is relatively small. The utilization efficiency of the catalyst can be improved. Therefore, the power generation performance of the fuel cell 100J is improved. In addition, it is possible to reduce the manufacturing cost of the fuel cell 100J by reducing the amount of catalyst used.

  FIG. 16 is a schematic diagram showing a configuration of a fuel cell 100Ja as another configuration example in the fourth embodiment. FIG. 16 is substantially the same as FIG. 17A except that the gas diffusion layer 5 is provided with a diffusion suppressing portion 6 similar to that described in the first embodiment (FIG. 6A). . In this fuel cell 100Ja, since the reaction gas in the supply side parallel flow grooves 23 and 33 is guided to the lower layer of the electrode layers 2 and 3 by the diffusion suppressing unit 6, the reaction gas that reaches the catalyst layer 4J. The amount of can be increased.

  Further, in the fuel cell 100Ja, the flow path wall area WA has a higher catalyst content. Therefore, in the catalyst layer 4J, even when a large amount of reaction gas flows through the flow path wall area WA, the amount of reaction gas that passes through the second catalyst layer 4Ib without being used in the power generation reaction is reduced. It is possible to improve the reaction gas consumption efficiency. In the fuel cell 100Ja, the gas diffusion layers 5A and 5B described with reference to FIGS. 7A and 7B may be provided instead of the gas diffusion layer 5.

E. Example 5:
FIG. 17 is a schematic diagram showing the configuration of a fuel cell 100K as a fifth embodiment of the present invention. FIG. 17 is substantially the same as FIG. 8 except that the catalyst layer 4K is provided instead of the catalyst layer 4C and that the arrows indicating the flow of the reaction gas are different. The catalyst layer 4K of the fuel cell 100K has a high air permeability catalyst layer 4Ka with high air permeability in the flow path wall area WA, and a low air permeability catalyst layer 4Kb with low air permeability in the flow path groove area GA. have. With this configuration, the reaction gas that reaches the catalyst layer 4K is guided to the high air permeability catalyst layer 4Ka having high air permeability. That is, the amount of the reactive gas flowing to the flow path wall area WA can be increased, and the power generation amount in the flow path wall area WA can be increased.

  The high air permeability catalyst layer 4Ka and the low air permeability catalyst layer 4Kb can be formed by adjusting the I / C for each area of the catalyst layer 4K, as described in FIG. That is, after a catalyst layer having a uniform air permeability for each region is formed, a solution containing a polymer electrolyte is applied and impregnated in the flow channel region GA. Thereby, the I / C of the flow channel region GA can be increased, and the high air permeability catalyst layer 4Ka and the low air permeability catalyst layer 4Kb can be formed.

  As described above, by configuring the air permeability in the catalyst layer 4K so that the flow path wall area WA is higher than the flow path groove area GA, the amount of reaction gas flowing in the flow path wall area WA is increased. Thus, the amount of power generation in the flow path wall area WA can be increased. Therefore, the amount of power generation in the fuel cell 100K can be increased, and the power generation performance can be improved.

  Note that, in this fuel cell 100K, as in the fuel cell 100J of the fourth embodiment, the flow path wall area WA may be configured to have a larger amount of catalyst supported than the flow path groove area GA. That is, the catalyst loading amount of the high air permeability catalyst layer 4Ka may be larger than the catalyst loading amount of the low air permeability catalyst layer 4Kb. Thereby, the power generation amount in the flow path wall area WA can be further increased. Further, in the fuel cell 100D of the second embodiment and the fuel cells 100E, 100F, 100G, and 100H in the other configuration examples of the second embodiment, the catalyst layer 4K of the fuel cell 100C is used instead of the catalyst layer 4. May be provided.

F. 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.

F1. Modification 1:
In the above embodiment, both the anode separator 20 and the cathode separator 30 are provided with flow channel grooves divided into supply side flow channel grooves and discharge side flow channel grooves. However, both the anode separator 20 and the cathode separator 30 may not be provided with such a channel groove. The channel groove divided into the supply side channel groove and the discharge side channel groove may be provided in at least one of the anode separator 20 and the cathode separator 30. For example, the flow channel groove of the anode separator 20 is replaced with the above-described flow channel structure, and the distribution flow channel groove 22 and each discharge side parallel flow channel groove 25 are connected to each other. It is good also as what is set as the flow path groove with which the path groove 23 was connected. Note that the configuration of the anode 2 in this case may be the same as the configuration of the anode 2 in the fuel cell 100a of the comparative example (FIG. 6B).

F2. Modification 2:
In the above embodiment, the supply-side channel groove and the discharge-side channel groove are substantially comb-like channel grooves in which the supply-side parallel channel grooves 23 and 33 and the discharge-side parallel channel grooves 25 and 35 mesh with each other. Was configured. However, the supply-side flow channel and the discharge-side flow channel do not need to form such a substantially comb-shaped flow channel that meshes with each other. The supply-side channel groove and the discharge-side channel groove are closed so as to be spatially separated from each other across the channel partition when arranged on the outer surface of the electrode layers 2 and 3. What is necessary is just to be comprised as a groove | channel. For example, the supply-side channel groove and the discharge-side channel groove may be configured as closed channel grooves that fold back in a so-called serpentine shape and run side by side.

F3. Modification 3:
In the first embodiment, the diffusion suppressing portion 6 is formed so as to substantially overlap the supply side parallel flow channel grooves 23 and 33 and the discharge side parallel flow channel grooves 25 and 35. That is, the diffusion suppressing part 6 is formed so as to cover the entire flow path groove area GA. However, the diffusion suppressing part 6 may be formed only in a part of the channel groove area GA. For example, the diffusion suppressing unit 6 may be formed with a width narrower than the groove widths of the supply side parallel flow channel grooves 23 and 33 and the discharge side parallel flow channel grooves 25 and 35. The groove region GA may be formed only on the upstream side. Similarly, in the fuel cells 100A, 100B, and 100C as other configuration examples in the first embodiment, the diffusion suppressing unit 6, the high diffusion layer 5Aa, and the high air permeability catalyst layer 4Ca are provided in the flow path groove region GA. It is good also as what is formed only in part. In other words, in the first embodiment, the electrode layers 2 and 3 only need to be configured such that the flow channel region GA has higher gas diffusibility than the flow channel wall region WA.

F4. Modification 4:
In the second embodiment, the diffusion suppressing portion 6 is provided at substantially the center of the supply side parallel flow channel grooves 23 and 33 and the discharge side parallel flow channel grooves 25 and 35. However, the diffusion suppressing unit 6 may be provided at a position deviated from the center of each of the supply side parallel flow channel grooves 23 and 33 and each of the discharge side parallel flow channel grooves 25 and 35. The diffusion suppressing unit 6 has groove openings in the supply side parallel flow channel grooves 23 and 33 so that the flow velocity of the reaction gas flowing from the supply side parallel flow channel grooves 23 and 33 into the gas diffusion layer 5 is improved. What is necessary is just to arrange | position so that it may be squeezed moderately. Alternatively, the diffusion suppressing unit 6 is configured so that the outflow of the reaction gas from the gas diffusion layer 5 to the discharge side parallel flow channel grooves 25 and 35 is not blocked. What is necessary is just to arrange | position so that a part may be in the open state.

F5. Modification 5:
In the third and fourth embodiments, the first and second catalyst layers 4Ia and 4Ib have a boundary between the first and second catalyst layers 4Ia and 4Ib and the flow channel region GA when viewed in the stacking direction of the fuel cell 100I. It was formed so as to substantially coincide with the boundary of the road wall area WA. However, the boundary between the first and second catalyst layers 4Ia and 4Ib and the boundary between the channel groove region GA and the channel wall region WA do not have to coincide with each other. The fuel cell 100I only needs to be configured so that the ratio of the catalyst content to the area of the channel groove area GA is different from the ratio of the catalyst content to the area of the channel wall area WA.

F6. Modification 6:
In the fourth embodiment, the first catalyst layer 4Ia having a small catalyst loading is provided in the flow channel region GA. However, the catalyst may be omitted in the channel groove area GA. That is, in the catalyst layer forming step, a thin film layer formed by using a mixed solution of carbon particles not supporting a catalyst and a polymer electrolyte is disposed in the channel groove area GA in place of the catalyst ink. It may be a thing.

F7. Modification 7:
In the first embodiment, in order to increase the amount of reaction gas flowing into the flow channel region GA, materials having different air permeabilities are disposed in the flow channel region GA and the flow channel wall region WA. However, it is also possible to increase the amount of reaction gas flowing into the flow channel region GA by other configurations. For example, the gas diffusion layer 5 and the catalyst layer 4 may be formed using members having different porosities in the flow channel region GA and the flow channel wall region WA, or the flow channel region GA and the flow channel wall region. The thickness of the gas diffusion layer 5 and the catalyst layer 4 may be changed depending on the WA. When a water repellent layer is formed between the gas diffusion layer and the catalyst layer, the air permeability in the water repellent layer may be changed. That is, in the electrode layers 2 and 3, a material having a lower gas diffusibility in the flow path wall area WA than in the flow path groove area GA may be used.

F8. Modification 8:
In the second embodiment, in order to increase the amount of the reaction gas that reaches the catalyst layer 4, a material having low air permeability such as the diffusion suppressing portion 6 is disposed in a part of the channel groove region GA. It was. However, a material having a low porosity may be disposed instead of a material having a low air permeability. That is, in order to increase the amount of the reaction gas that reaches the catalyst layer 4, a material having a lower gas diffusibility than that used for the flow path wall area WA is used for a part of the flow path groove area GA. It is also good.

F9. Modification 9:
In the third embodiment, the first catalyst layer 4Ia having a large amount of catalyst is provided in the flow channel region GA in order to increase the power generation amount in the flow channel region GA. However, in order to increase the power generation amount in the channel groove area GA, the catalyst layer may be configured as follows. That is, a catalyst having a high catalytic activity may be used in the flow channel region GA. Alternatively, a catalyst having a small particle diameter may be used to increase the total catalyst surface area.

F10. Modification 10:
In the fourth embodiment, in order to increase the power generation amount in the flow path wall area WA, the first catalyst layer 4Ia having a large catalyst loading amount is provided in the flow path wall area WA. However, in order to increase the power generation amount in the flow path wall area WA, the catalyst layer may be configured as follows. That is, a catalyst having a high catalytic activity may be used in the flow path wall area WA. Alternatively, a catalyst having a small particle diameter may be used to increase the total catalyst surface area.

F11. Modification 11:
In the fifth embodiment, in order to increase the power generation amount in the flow path wall area WA, the high air permeability catalyst layer 4Ka is provided in the flow path wall area WA, and the low air permeability catalyst layer 4Kb is provided in the flow path groove area GA. And the reactive gas was guided to the flow path wall area WA. However, the catalyst layer may be configured as follows in order to induce more reaction gas in the flow path wall area WA. That is, the porosity of the catalyst layer in the flow path wall area WA may be higher than the porosity of the catalyst layer in the flow path groove area GA. The thickness of the gas diffusion layer and the catalyst layer in the flow path wall area WA may be made thinner than the thickness of the gas diffusion layer and the catalyst layer in the flow path groove area GA.

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane 2 ... Anode (electrode layer)
3 ... Cathode (electrode layer)
4 ... Catalyst layer 4C ... Catalyst layer 4Ca ... High air permeability catalyst layer 4Cb ... Low air permeability catalyst layer 4I ... Catalyst layer 4Ia ... First catalyst layer 4Ib ... Second catalyst layer 4J ... Catalyst layer 4K ... Catalyst layer 4Ka ... High air permeability catalyst layer 4Kb ... Low air permeability catalyst layer 5 ... Gas diffusion layer 5A ... Gas diffusion layer 5Aa ... High diffusion layer 5Ab ... Low diffusion layer 5B ... Gas diffusion layer 5G ... Gas diffusion layer 5Ga ... High diffusion Layer 5Gb ... Low diffusion layer 5H ... Gas diffusion layer 6 ... Diffusion suppression part 10 ... Membrane electrode assembly 10D ... Membrane electrode assembly 11 ... Power generation region 12 ... Outer peripheral seal part 20 ... Anode separator 21 ... Supply side communication channel groove 22 ... distribution channel groove 23 ... supply side parallel channel groove 25 ... discharge side parallel channel groove 26 ... confluence channel groove 27 ... discharge side communication channel groove 29 ... parallel channel partition wall 30 ... cathode separator 31 ... supply side communication Channel groove 32 ... Distribution channel groove 33 ... Supply side parallel flow channel 35 ... Discharge side parallel flow channel 36 ... Merge flow channel 37 ... Discharge side communication flow channel 39 ... Parallel flow channel partition 41 ... First strip base material 42 ... Second strip shape Substrate 91 ... Catalyst-supported carbon 92 ... Catalyst 93 ... Polymer electrolyte 100-100K ... Fuel cell 100a ... Fuel cell (comparative example)
110 ... single cell 200 ... roller Fa, Fb ... film substrate GA ... channel groove area M1 ... hydrogen supply manifold M2 ... hydrogen discharge manifold M3 ... oxygen supply manifold M4 ... oxygen discharge manifold SA ... area WA ... flow Road wall area

Claims (3)

A fuel cell,
A membrane electrode assembly in which electrode layers are arranged on both sides of the electrolyte membrane;
Two separators sandwiching the membrane electrode assembly;
A supply manifold for supplying a reaction gas to the membrane electrode assembly;
A discharge manifold for discharging exhaust gas from the membrane electrode assembly;
With
The electrode layer has a catalyst layer provided on the side in contact with the electrolyte membrane and a gas diffusion layer provided on the side in contact with the separator;
At least one of the two separators is connected to a supply-side flow channel for a reactive gas connected to the supply manifold on a surface in contact with the gas diffusion layer, and to the discharge manifold. A discharge side channel groove for the exhaust gas, and a channel partition wall separating the supply side channel groove and the discharge side channel groove,
The supply-side flow channel and the discharge-side flow channel are spatially separated from each other with the flow channel partition interposed therebetween when disposed on the outer surface of the gas diffusion layer. The reaction gas in the side flow channel is configured to flow into the gas diffusion layer,
The electrode layer includes a channel groove region that overlaps the supply-side channel groove or the discharge-side channel groove of the separator when the fuel cell is viewed along the stacking direction of the electrode layer, and the channel A channel wall region that overlaps the partition wall,
The fuel cell, wherein the electrode layer is configured such that at least one of the gas diffusion layer and the catalyst layer has a gas diffusibility higher in the flow channel region than in the flow channel wall region. The fuel cell according to claim 1, wherein
The electrode layer is a fuel cell in which the flow path wall region has a higher catalyst content in the catalyst layer than the flow path groove region. The fuel cell according to claim 1 or 2, wherein
The flow passage wall region of the gas diffusion layer has a gas diffusibility lower than the gas diffusibility of the flow channel groove region, and a diffusion suppression member that suppresses diffusion of a reaction gas is provided in the flow channel of the separator. Placed in contact with the wall,
The fuel cell, wherein the diffusion suppressing member functions as a guide wall for guiding the reaction gas in the flow channel to the catalyst layer.

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