JP4321038B2 - Polymer electrolyte fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a polymer electrolyte fuel cell having a polymer electrolyte membrane having ion conductivity, and more particularly to a polymer electrolyte fuel cell in which a gas flow path forming member for an oxidizer electrode is made porous.
[0002]
[Prior art]
  The polymer electrolyte fuel cell is advantageous in terms of energy and environment, and has been developed in recent years. A polymer electrolyte fuel cell includes a polymer electrolyte membrane having ion conductivity, a fuel electrode provided on one side of the polymer electrolyte membrane and supplied with fuel, and an oxidation provided on the other side of the polymer electrolyte membrane. It has a drug electrode. If the polymer electrolyte membrane is excessively dried, the ionic conductivity is lowered, so that sufficient power generation performance cannot be obtained.
[0003]
  Therefore, conventionally, a method has been adopted in which moisture is supplied to the oxidant-containing gas and fuel-containing gas before being supplied to the fuel cell, and the oxidant-containing gas and fuel-containing gas containing moisture are supplied to the fuel cell.
[0004]
  As another method, conventionally, a gas flow path forming member also called a separator provided outside at least one of the fuel electrode and the oxidant electrode is made porous, and the porous gas flow path forming member is made fine. A method of supplying water and water vapor to the polymer electrolyte membrane through the holes is employed (Patent Documents 1 to 3). According to this method, the porous gas flow path forming member has a large number of pores, and the pores communicate with each other in the thickness direction of the gas flow path forming member so that water and water vapor can pass therethrough. It is a communication hole.
[0005]
[Patent Document 1]
JP-A-6-338338
[Patent Document 2]
Patent Publication No. 2922132
[Patent Document 3]
JP-A-1-309263
[0006]
[Problems to be solved by the invention]
  By the way, according to the polymer electrolyte fuel cell adopting the latter method described above, as described above, the porous gas flow path forming member also called a separator has a large number of pores. The pores are communication holes that communicate in the thickness direction of the gas flow path forming member so that water and water vapor can permeate. Here, the diameter and porosity of the pores are basically uniform in each part of the gas flow path forming member. That is, the water permeability between the water passage and the oxidant electrode is basically uniform in each part of the gas flow path forming member. In the industry, there is a demand for further improvement in the power generation performance of the above-described polymer electrolyte fuel cell.
[0007]
  The present invention has been made in view of the above circumstances,Excessive drying in the upstream region of the oxidizer electrode, and consequently, excessive drying in the upstream region of the polymer electrolyte membrane can be suppressed,It is an object of the present invention to provide a polymer electrolyte fuel cell advantageous for further improving the power generation performance.
[0008]
[Means for Solving the Problems]
  Aspect 1The polymer electrolyte fuel cell according to the present invention is provided with a polymer electrolyte membrane having ion conductivity, a fuel electrode provided on one side of the polymer electrolyte membrane and supplied with fuel, and provided on the other side of the polymer electrolyte membrane. An oxidant electrode to which an oxidant-containing gas is supplied, a gas flow path forming member for the fuel electrode provided outside the fuel electrode, and provided outside the oxidant electrodeHas pores that can be communication holesA porous gas flow path forming member for the oxidant electrode, a water flow path forming member for forming a water flow path through which water flows outside the gas flow path forming member for the oxidant electrode, and supplying water to the water flow path A polymer electrolyte fuel cell comprising a water flow section for flowing water through the water flow path,
  In the porous gas flow path forming member for the oxidant electrode,
  When the downstream where the oxidant gas flows is defined as the downstream region and the upstream where the oxidant gas flows is defined as the upstream region,
  Between the water channel and the oxidizer electrodeIn the thickness direction, at least one of liquid phase water and water vapor permeates.The moisture permeability is set to be larger in the upstream region than in the downstream region.
  According to the polymer electrolyte fuel cell according to aspect 2, in the above-described aspect, in the gas flow path forming member for the porous oxidant electrode, at least one of the average pore diameter and the porosity is a downstream region. It is characterized in that it is set larger in the upstream region.
  According to the polymer electrolyte fuel cell according to aspect 3, in the above-described aspect, in the gas flow path forming member for the porous oxidant electrode, at least one of the average pore diameter and the porosity is the upstream region. Is set to be relatively large, is set to be relatively small in the downstream region, and is set to gradually decrease from the upstream region to the downstream region..
  According to the polymer electrolyte fuel cell according to aspect 4, in the above-described aspect, in the gas channel forming member for the porous oxidant electrode, the ratio of the water repellent per unit volume is higher than that in the downstream region. It is characterized by being set small in the upstream region. In this case, when the ratio of the water repellent is large, it is not easy to take in and out water. The ratio of the water repellent is set to be relatively large in the downstream region and relatively small in the upstream region. For this reason, it becomes advantageous to permeate | transmit the water of a water channel to the upstream area side of MEA, and it can contribute to suppression of the excessive drying in the upstream area of MEA.
[0009]
  Each aspectAccording to the polymer electrolyte fuel cell according to the present invention, in the porous gas flow path forming member for the oxidant electrode, the water permeability between the water passage and the oxidant electrode is higher in the upstream region than in the downstream region. It is set large in. For this reason, the water supplied to the water flow path by the operation of the water flow section can be permeated toward the oxidant electrode in the upstream region rather than in the downstream region. Therefore, excessive drying in the upstream region of the oxidizer electrode can be suppressed. As a result, excessive drying in the region corresponding to the upstream region of the polymer electrolyte membrane can be suppressed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
  BookAccording to a preferred embodiment of the polymer electrolyte fuel cell according to the invention, in the porous gas flow path forming member for the oxidant electrode, at least one of the average pore diameter and the porosity is downstream in the upstream region. A form that is set larger than the area can be adopted. Thereby, the moisture permeability between the water channel and the oxidant electrode is set relatively large in the upstream region and relatively small in the downstream region. In this case, the water supplied to the water passage by the operation of the water passage portion can be more effectively permeated toward the oxidant electrode in the upstream region than in the downstream region. Therefore, excessive drying in the upstream region of the oxidizer electrode, and hence excessive drying in the upstream region of the polymer electrolyte membrane can be suppressed.
[0011]
  Preferably, in the porous gas flow path forming member for the oxidant electrode, at least one of the average pore diameter and the porosity is set to be relatively large in the upstream region, and relatively in the downstream region. An example is shown in which it is set to be small and gradually decreases from the upstream region to the downstream region.
[0012]
  BookAccording to the polymer electrolyte fuel cell according to the invention, the moisture permeability means the permeability of at least one of water in a liquid phase and water vapor. The relatively large average pore diameter means that the pore diameter is relatively large among all the pores in the porous gas flow path forming member, and the average pore diameter is in the range of 10 to 1000 μm. it can. The relatively small average pore diameter means that the pore diameter is relatively small among all the pores in the porous gas flow path forming member, and the average pore diameter is in the range of less than 0.1 to 10 μm. The inside can be illustrated. Most of the pores are communication holes, and give water permeability to the gas flow path forming member.
[0013]
  The relatively high porosity means that the porosity is relatively high in the porous gas flow path forming member, and can be exemplified within the range of 40 to 95% porosity. The phrase “porosity is relatively small” means that the porosity of the porous gas flow path forming member is relatively small, and examples include a range of porosity of less than 0.1 to 40%. However, the average pore diameter and the porosity are not limited to the above ranges.
[0014]
  BookAccording to the polymer electrolyte fuel cell of the invention, in the porous gas flow path forming member for the oxidant electrode, the ratio of the water repellent per unit volume is set smaller in the upstream region than in the downstream region. The form currently used can be employ | adopted. When the ratio of the water repellent is large, it is not easy to put water in and out. In the above-described embodiment, the ratio of the water repellent is set relatively large in the downstream region and relatively small in the upstream region (including no water repellent). For this reason, it becomes advantageous to permeate | transmit the water of a water flow path to the upstream region of MEA, and it can contribute further to suppression of the excessive drying in the upstream region of MEA.
[0015]
  RepellentThe liquid medicine can be provided on the surface and / or in the pores of the porous gas flow path forming member.
[0016]
【Example】
  The concept of the first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 schematically shows the concept of a polymer electrolyte fuel cell according to this example. The polymer electrolyte fuel cell according to the present embodiment employs a system in which water is pumped through the first water passage 41. The MEA 1 (membrane / electrode assembly) according to the present embodiment is provided with a polymer electrolyte membrane 11 formed of a polymer electrolyte material having proton conductivity, and a fuel provided on one side of the polymer electrolyte membrane 11 in the thickness direction. The supplied fuel electrode 12 and the porous oxidant electrode provided on the other side in the thickness direction of the polymer electrolyte membrane 11 and supplied with an oxidant-containing gas (generally air) and having gas permeability. 15.
[0017]
  The oxidant electrode 15 is porous and has a first gas diffusion layer 16 formed of a carbon material such as carbon fiber so as to have gas permeability and conductivity, and a first gas diffusion layer 16 formed on the polymer electrolyte membrane 11 side. The catalyst layer 17 is formed. The fuel electrode 12 is porous and has a second gas diffusion layer 13 made of a carbon material such as carbon fiber so as to have gas permeability and conductivity, and a second catalyst formed on the polymer electrolyte membrane 11 side. And the layer 14. The first catalyst layer 17 and the second catalyst layer 14 are formed using, as main components, an aggregate of carbon fine particles supporting a catalyst metal such as platinum and an electrolyte polymer having proton conductivity.
[0018]
  As shown in FIG. 1, the gas flow path forming member 2 for the fuel electrode is provided outside the fuel electrode 12 in the thickness direction. The gas flow path forming member 2 for the fuel electrode is also called a separator, and is formed of a dense body. The gas flow path forming member 2 for the fuel electrode is made of a material having corrosion resistance and conductivity (generally a carbon material), and the fuel gas supplied to the second gas diffusion layer 13 of the fuel electrode 12 is A flowing groove-like gas flow path 21 is provided.
[0019]
  On the outer side of the oxidant electrode 15 in the thickness direction, a porous gas flow path forming member 3 for the oxidant electrode having a large number of pores that can be communication holes is provided. In the gas flow path forming member 3 shown in FIG. 1, the pores are schematically shown as ◯. In the gas flow path forming member 3, the pores communicate with each other and have moisture permeability in the thickness direction of the gas flow path forming member 3. The gas flow path forming member 3 for the oxidant electrode is also referred to as a separator, and is formed of a material having corrosion resistance and conductivity (generally a carbon material). It has a groove-like gas flow path 31 through which an oxidant-containing gas (generally air) supplied to the layer 16 flows. As shown in FIG. 1, the fuel electrode 12 and the oxidant electrode 15 are electrically connected via a conductive path 60 and a load 61.
[0020]
  In the gas flow path forming member 3 for the oxidant electrode, an upstream side in which the oxidant-containing gas flows is defined as an upstream region 91, and a downstream side in which the oxidant-containing gas flows is defined as a downstream region 93. On the outer side in the thickness direction of the gas flow path forming member 3 for the oxidizer electrode, a partition plate-shaped first passage that forms a first water passage 41 through which water for cooling and humidification supplied from the water supply source 40 flows. A water channel forming member 51 is provided. The first water passage 41 has a water supply port 43 and a water discharge port 44.
[0021]
  Furthermore, a water flow part 49 is provided for allowing water from the water supply source 40 to be pumped to the first water flow path 41 and passed therethrough. The water flow part 49 can be formed with a pump, for example. The water flow portion 49 is provided on the upstream side of the water supply port 43 of the first water flow channel 41, causes water to be pumped to the first water flow channel 41, and is directed from the water supply port 43 of the first water flow channel 41 toward the water discharge port 44. Let water through. The pressure Pm of water in the first water passage 41 exceeds 1 atm in absolute pressure, and the pressure Pm in the groove-like gas passage 31 through which the oxidant-containing gas (generally air) flows.₁(Pm> P)₁). Basically Pm and P₁Thus, the water in the first water passage 41 can be replenished toward the oxidant electrode 15 side of the MEA 1 in the direction of the arrow M1.
[0022]
  Now, according to the present embodiment, the average pore diameter and porosity of the porous gas flow path forming member 3 for the oxidant electrode change along the direction in which the oxidant-containing gas (generally air) flows. It is set to be. That is, in the porous gas flow path forming member 3 for the oxidizer electrode, both the average pore diameter and the porosity are set to be larger in the upstream region 91 than in the downstream region 93.
[0023]
  Specifically, in the porous gas flow path forming member 3 for the oxidizer electrode, both the average pore diameter and the porosity are set relatively large in the upstream region 91, and in the downstream region 93. It is set relatively small. That is, in FIG. 2, the characteristic line A1 indicates the pore diameter, and the characteristic line A2 indicates the porosity. As shown by the characteristic lines A1 and A2 in FIG. 2, it is set so as to gradually and gradually decrease from the upstream region 91 to the downstream region 93. As a result, the moisture permeability between the first water passage 41 and the oxidant electrode 15 is relatively large in the upstream region 91 and relatively small in the downstream region 93.
[0024]
  In addition, that the average pore diameter is relatively large can be exemplified by an average pore diameter in the range of 10 to 1000 μm. The relatively small average pore diameter can be exemplified by the average pore diameter in the range of 0.1 to 10 μm. A relatively large porosity can be exemplified by a porosity in the range of 40 to 95%. That the porosity is relatively small can be exemplified by a range of porosity of 0.1 to less than 40%. However, the pore diameter and porosity are not limited to the above values.
[0025]
  When the fuel cell is operated, an oxidant-containing gas (generally air) is supplied from the carrier source 68 to the groove-shaped gas flow path 31 of the gas flow path forming member 3 for the oxidant electrode. This oxidant-containing gas flows into the first gas diffusion layer 16 and the first catalyst layer 17 of the oxidant electrode 15 from the groove-like gas flow path 31. Further, the fuel gas (hydrogen-containing gas) is supplied from the carrier source 69 to the groove-like gas flow path 21 of the fuel electrode gas flow path forming member 2. The fuel gas flows from the gas flow path 21 into the second gas diffusion layer 13 and the second catalyst layer 14 of the fuel electrode 12. Then, by the catalytic action of the second catalyst layer 14, protons (hydrogen ions) and electrons (e⁻) And are generated. The generated protons permeate the polymer electrolyte membrane 11 in the thickness direction and reach the oxidant electrode 15. The electrons flow through the conductive path 60, perform electrical work with the load 61 of the conductive path 60, and then reach the oxidizer electrode 15. In the oxidant electrode 15, the oxidant-containing gas (generally air) supplied to the oxidant electrode 15 reacts with protons and electrons due to the catalytic action of the first catalyst layer 17 of the oxidant electrode 15 to react with water. Is generated. Although heat is generated by such a power generation reaction, since the water from the water supply source 40 is passed through the first water passage 41 by the water passage portion 49, the fuel cell is cooled.
[0026]
  In the MEA 1 in which the power generation reaction is expressed, the generated water tends to be relatively more in the downstream region 93 than in the upstream region 91 of the oxidant-containing gas. Therefore, in such MEA 1, the relative humidity is generally relatively low in the upstream region 91 and relatively high in the downstream region 93. In the above-described MEA 1, drying may occur in the upstream region 91, and surplus water may stay in the downstream region 93.
[0027]
  In this regard, according to the present embodiment, the moisture permeability between the first water passage 41 and the oxidant electrode 15 is set to be relatively large in the upstream region 91 and relatively in the downstream region 93. Is set to a small value. That is, both the average pore diameter and the porosity in the porous gas flow path forming member 3 for the oxidant electrode are set to be relatively large in the upstream region 91 and relatively in the downstream region 93. It is set small. For this reason, when water is pumped and passed through the first water passage 41, the water in the first water passage 41 is larger in the MEA 1 than in the downstream region 93 in the upstream region 91 having a larger average pore diameter and porosity. It becomes easy to permeate in the direction of the arrow M1 relatively to the oxidant electrode 15 side. As a result, in the upstream region 91 that tends to dry, the amount of humidification with respect to the oxidizer electrode 15 can be relatively increased, and consequently, excessive drying in the upstream region 91 that tends to dry can be suppressed.
[0028]
  In contrast, in the downstream region 93 where water tends to be excessive based on the above-described power generation reaction, the humidification amount of the MEA 1 with respect to the polymer electrolyte membrane 11 can be made relatively smaller than that of the upstream region 91. . As a result, the flooding phenomenon in the downstream region 93 where moisture tends to be excessive can be suppressed. As a result, it can contribute to improving the power generation performance of the polymer electrolyte fuel cell. The flooding phenomenon means that the gas passage through which the gas passes is closed with excess water, and the passage area of the gas passage is reduced. When the flooding phenomenon occurs, it is disadvantageous to obtain sufficient power generation performance.
[0029]
  (Second embodiment)
  The second embodiment has basically the same configuration as the first embodiment, and basically has the same function and effect. In the following, the description will be focused on the differences from the first embodiment. According to the present embodiment, as shown by characteristic lines A1 and A2 in FIG. 3, in the porous gas flow path forming member 3 for the oxidant electrode, both the average pore diameter and the porosity are in the upstream region 91. Is set relatively large, and is set relatively small in the downstream region 93. Here, as shown by characteristic lines A1 and A2 in FIG. 3, both the average pore diameter and the porosity change discontinuously from the upstream region 91 to the downstream region 93.
[0030]
  (Third embodiment)
  FIG. 4 schematically shows the concept of the third embodiment. The third embodiment has basically the same configuration as the first embodiment, and basically has the same function and effect. In the following, the description will be focused on the differences from the first embodiment. According to the present embodiment, as shown in FIG. 4, in the porous gas flow path forming member 3B for the oxidizer electrode, the average pore diameter of each pore is basically substantially the same, about 5-10 micrometers can be illustrated.
[0031]
  The porosity of the gas channel forming member 3B for the oxidant electrode is set so as to change along the direction in which the oxidant-containing gas flows. That is, the porosity of the porous gas flow path forming member 3 </ b> B for the oxidant electrode is set to be larger in the upstream region 91 than in the downstream region 93.
[0032]
  As a result, in the porous gas flow path forming member 3B for the oxidant electrode, the moisture permeability between the first water passage 41 and the oxidant electrode 15 is set relatively large in the upstream region 91. And is set relatively small in the downstream region 93.
[0033]
  According to the present embodiment, the gas flow path forming member 2B for the fuel electrode is not a dense body but is formed of a porous body having a large number of pores. In the gas flow path forming member 2B for the fuel electrode, an upstream side in which the fuel gas flows is defined as an upstream region 91X, and a downstream side in which the fuel gas flows is defined as a downstream region 93X.
[0034]
  In the gas flow path forming member 3B and the gas flow path forming member 2B shown in FIG. 4, the pores are modeled as ◯. The pores communicate with each other in the gas flow path forming member 3B and the gas flow path forming member 2B, and each of the gas flow path forming member 3B and the gas flow path forming member 2B has moisture permeability in the thickness direction.
[0035]
  As shown in FIG. 4, the 2nd water flow path formation member 52 which forms the 2nd water flow path 42 is provided in the outer side of the gas flow path formation member 2B for fuel electrodes. The second water passage 42 has a water supply port 43 and a water discharge port 44. Similarly to the first water passage 41, the water from the water supply source 40 flows through the second water passage 42 by being pumped by the operation of the water passage portion 49.
[0036]
  The porosity of the gas flow path forming member 2B for the fuel electrode is set so as to change along the direction in which the fuel gas flows. That is, the porosity of the gas flow path forming member 2B for the porous fuel electrode is set larger in the upstream region 91X than in the downstream region 93X. Specifically, the porosity in the gas flow path forming member 2B for the porous fuel electrode is set to be relatively large in the upstream region 91X, and is set to be relatively small in the downstream region 93X. . Accordingly, the moisture permeability between the second water passage 42 and the fuel electrode 12 is set to be relatively large in the upstream region 91X and relatively small in the downstream region 93X.
[0037]
  As described above, according to the present embodiment, the porosity of the porous gas flow path forming member 3B for the oxidant electrode is set to be relatively large in the upstream region 91 and the downstream side. The area 93 is set relatively small. Similarly, for the gas flow path forming member 2B for the fuel electrode, the porosity is set relatively large in the upstream region 91X and relatively small in the downstream region 93X.
[0038]
  For this reason, when water is pumped and passed through the first water passage 41 and the second water passage 42, the water in the first water passage 41 and the second water passage 42 has upstream areas 91 and 91X having a large porosity. Then, it becomes relatively easier to transmit in the direction of the arrow M1 toward the MEA1 side than the downstream regions 93 and 93X. As a result, the humidification amount for MEA 1 can be relatively increased in the upstream regions 91 and 91X that tend to dry. Furthermore, in the downstream regions 93 and 93X where water tends to be excessive, the humidification amount for the MEA 1 can be made relatively small.
[0039]
  (Fourth embodiment)
  FIG. 5 schematically shows the concept of the fourth embodiment. The fourth embodiment has basically the same configuration as the third embodiment shown in FIG. 4, and basically has the same function and effect. Hereinafter, a description will be given focusing on the differences from the third embodiment shown in FIG. In the gas flow path forming member 3 </ b> B and the gas flow path forming member 2 </ b> B shown in FIG. 5, the pores are modeled as ◯. The pores communicate with each other in the gas flow path forming member 3B and the gas flow path forming member 2B, and the gas flow path forming member 3B and the gas flow path forming member 2B are each permeable in the thickness direction.
[0040]
  According to the present embodiment, the water repellent 8 is attached to the surface of the gas flow path forming member 3B for the oxidant electrode and the surface of the pores. FIG. 5 schematically shows the strength of the water repellent 8 and does not indicate the thickness of the water repellent 8. Examples of the water repellent 8 include perfluorocarbon and fluorocarbon. In the gas flow path forming member 3B for the oxidant electrode, when the ratio of the water repellent 8 per unit volume is large, water is repelled, so that it becomes difficult to take in and out the MEA1. Further, if the ratio of the water repellent 8 is small or the water repellent 8 is not present, the water can be easily taken in and out of the MEA 1 as compared with the case where the ratio of the water repellent 8 is large.
[0041]
  According to the present embodiment, the ratio of the water repellent 8 in the porous gas flow path forming member 3B for the oxidant electrode is set so as to change along the direction in which the oxidant gas flows. That is, the ratio of the water repellent 8 in the porous gas flow path forming member 3 </ b> B for the oxidant electrode is set in the upstream region 91 or less than the downstream region 93. Specifically, the ratio of the water repellent 8 in the gas flow path forming member 3B for the oxidant electrode is set to be relatively small in the upstream region 91 (including no water repellent), and The downstream area 93 is set relatively large. For this reason, the moisture permeability between the first water passage 41 and the oxidant electrode 15 is set relatively large in the upstream region 91 in the gas flow path forming member 3B for the oxidant electrode, and The downstream region 93 is set to be relatively small.
[0042]
  Further, as shown in FIG. 5, a water repellent 8 is attached to the surface of the gas flow path forming member 2B for the fuel electrode. The ratio of the water repellent 8 in the gas flow path forming member 2B for the porous fuel electrode is set so as to change along the direction in which the fuel gas flows. That is, the ratio of the water repellent 8 in the porous gas flow path forming member 2B for the fuel electrode is set to be none or less in the upstream region 91X than in the downstream region 93X. Specifically, the ratio of the water repellent 8 in the gas flow path forming member 2B for the oxidant electrode is set to be relatively small in the upstream region 91X and relatively large in the downstream region 93X. Is set. For this reason, the water permeability between the second water passage 42 and the fuel electrode 12 is set to be relatively large in the upstream region 91X in the gas flow path forming member 2B for the fuel electrode, and downstream. The side region 93X is set to be relatively small.
[0043]
  According to such a present Example, when water is pumped and passed through the first water passage 41 and the second water passage 42 by the operation of the water passage portion 49, the first water passage 41 and the second water passage. In the upstream areas 91 and 91X where the ratio of water repellent 8 is absent or relatively small, 42 water is directed toward MEA 1 rather than the downstream areas 93 and 93X where the ratio of water repellent 8 is relatively large. It becomes relatively easy to transmit in the direction of the arrow M1. As a result, the humidification amount in the upstream regions 91 and 91X can be increased, and excessive drying in the upstream regions 91 and 91X can be suppressed.
[0044]
  As described above, in changing the ratio of the water repellent 8 along the direction in which the oxidant-containing gas and the fuel gas flow, for example, the water repellent 8 is used as the gas flow path forming member 3B for the oxidant electrode and the fuel electrode. When the gas flow path forming member 2B is attached to the surface of the gas flow path forming member 2B, the gas flow path forming member 3B and the gas flow path forming member 2B are covered with a masking member, and the masking member is moved relative to each other, thereby making the masking time variable. Can be performed.
[0045]
  In some cases, in the embodiment shown in FIG. 5, either the water repellent 8 attached to the gas flow path forming member 3B or the water repellent 8 attached to the gas flow path forming member 2B may be eliminated. it can.
[0046]
  (No.1 referenceExample)
  Hereinafter, the present invention1 referenceThe concept of the example will be described with reference to FIG.. SolidThe polymer electrolyte fuel cell is a system in which water is caused to flow through the first water passage 41 by sucking the water through the first water passage 41.. MThe EA 1 includes a polymer electrolyte membrane 11 formed of a polymer material having proton conductivity, a fuel electrode 12 provided on one side of the polymer electrolyte membrane 11 in the thickness direction, to which fuel is supplied, and the polymer electrolyte membrane 11. And an oxidant electrode 15 which is provided on the other side in the thickness direction and is supplied with an oxidant-containing gas (generally air) and has gas permeability.
[0047]
  The oxidant electrode 15 is formed of a first gas diffusion layer 16 made of a carbon material so as to be porous and gas permeable, and a first catalyst layer 17 formed on the polymer electrolyte membrane 11 side. ing. The fuel electrode 12 is formed of a second gas diffusion layer 13 made of a carbon material so as to be porous and gas permeable, and a second catalyst layer 14 formed on the polymer electrolyte membrane 11 side. Yes.
[0048]
  As in the first embodiment, the fuel electrode gas flow path forming member 2 is provided outside the fuel electrode 12 in the thickness direction. The gas flow path forming member 2 for the fuel electrode is also called a separator, and is formed not by a porous body but by a dense body. The gas flow path forming member 2 for the fuel electrode is made of a material having corrosion resistance and conductivity (generally a carbon material), and the fuel gas supplied to the second gas diffusion layer 13 of the fuel electrode 12 is A flowing groove-like gas flow path 21 is provided.
[0049]
  As shown in FIG. 6, a porous gas flow path forming member 3E for the oxidant electrode having a large number of pores is provided outside the oxidant electrode 15 in the thickness direction. In the gas flow path forming member 3E shown in FIG. 6, the pores are schematically shown as ◯. In the gas flow path forming member 3E, the pores communicate with each other, and the gas flow path forming member 3E has permeability in the thickness direction.
[0050]
  The gas flow path forming member 3E for the oxidant electrode is also called a separator, is formed of a material having corrosion resistance and conductivity (generally a carbon material), and the first gas diffusion of the oxidant electrode 15 It has a groove-like gas flow path 31 through which an oxidant-containing gas (generally air) supplied to the layer 16 flows. The oxidant electrode 15 and the fuel electrode 12 are electrically connected through a conductive path 60 and a load 61.
[0051]
  As shown in FIG. 6, a partition plate-like first passage that forms a first water passage 41 through which water for cooling and humidification flows is provided on the outer side in the thickness direction of the gas flow path forming member 3E for the oxidant electrode. A water channel forming member 51 is provided.
  Further, a water passage portion 49 </ b> E that allows water to flow through the first water passage 41 is provided. The water flow portion 49E is provided on the downstream side of the first water flow channel 41, and by sucking the water in the first water flow channel 41 in the direction of the arrow W2, the water supply port 43 of the first water flow channel 41 is connected to the water discharge port 44. Allow water to pass. The water flow part 49E can be formed with a suction pump. The pressure Pm of water in the first water passage 41 is less than 1 atm in absolute pressure, and the pressure Pm in the groove-like gas passage 31 through which the oxidant-containing gas (generally air) flows.₁(Pm <P₁). Basically Pm and P₁The excess water staying at the oxidizer electrode 15 of the MEA 1 can be sucked into the first water passage 41 in the direction of the arrow M2.
[0052]
  Now bookreferenceAccording to the example, the average pore diameter and the porosity in the porous gas flow path forming member 3E for the oxidant electrode are set so as to change along the direction in which the oxidant-containing gas flows. That is, both the average pore diameter and the porosity of the porous gas flow path forming member 3E for the oxidant electrode are set to be larger in the downstream region 93 than in the upstream region 91. Specifically, both the average pore diameter and the porosity in the porous gas flow path forming member 3E for the oxidant electrode are set to be relatively large in the downstream region 93, and relatively in the upstream region 91. 7 and is set so as to gradually and gradually increase from the upstream region 91 to the downstream region 93 as indicated by characteristic lines E1 and E2 in FIG. In FIG. 7, a characteristic line E1 indicates the pore diameter, and a characteristic line E2 indicates the porosity.
[0053]
  As a result, the moisture permeability between the first water passage 41 and the oxidant electrode 15 is set relatively large in the downstream region 93 and relatively small in the upstream region 91.
[0054]
  When the fuel cell is operated, as in the first embodiment, fuel gas (hydrogen-containing gas) is supplied to the groove-like gas flow path 21 by the transport source 69 and oxidant-containing gas (generally, Is supplied to the groove-like gas flow path 31 by the conveyance source 68. The fuel gas reaches the second gas diffusion layer 13 of the fuel electrode 12 from the groove-shaped gas flow path 21 and is further contained in the fuel gas by the catalytic action of the second catalyst layer 14 contained in the fuel electrode 12. Hydrogen to proton (hydrogen ion) and electron (e⁻) And are generated. Protons permeate the polymer electrolyte membrane 11 in the thickness direction and reach the oxidizer electrode 15. The electrons flow through the conductive path 60. The electrons reach the oxidant electrode 15 after performing electrical work with the load 61 of the conductive path 60. In the oxidant electrode 15, the oxidant-containing gas (generally air) supplied to the oxidant electrode 15 reacts with protons and electrons due to the catalytic action of the first catalyst layer 17 of the oxidant electrode 15 to react with water. Is generated. In MEA1 in which such a power generation reaction is expressed, the generated water is relatively more in the downstream region 93 than in the upstream region 91 of the oxidant-containing gas. Therefore, in such MEA 1, the relative humidity is relatively low in the upstream region 91 and relatively high in the downstream region 93.
[0055]
  This scriptreferenceAccording to the example, as described above, for the porous gas flow path forming member 3E for the oxidant electrode, both the average pore diameter and the porosity are set relatively small in the upstream region 91. In addition, the downstream region 93 is set to be relatively large. That is, in the porous gas flow path forming member 3E for the oxidizer electrode, both the average pore diameter and the porosity are set relatively large in the downstream region 93 and relatively small in the upstream region 91. As shown by characteristic lines E1 and E2 in FIG. 7, it is set so as to gradually and gradually increase from the upstream region 91 to the downstream region 93.
[0056]
  Book for thisreferenceAccording to the example, as can be understood from FIG. 6, when the water supplied from the water supply source 40 is sucked in the direction of the arrow W <b> 2 in the first water passage 41, the water is collected in the downstream region 93 of the oxidant electrode 15. Excess water is more likely to be sucked in the direction of the arrow M <b> 2 toward the first water passage 41 than the upstream region 91. As a result, excess water in the downstream region 93 where moisture tends to be excessive is removed by suction, and as a result, the flooding phenomenon in the downstream region 93 can be suppressed. As a result, it can contribute to improving the power generation performance of the polymer electrolyte fuel cell.
[0057]
  (No.2 ReferenceExample)
  Figure 8 shows the first2 ReferenceThe concept of an example is shown typically. BookreferenceAn example is shown in FIG.referenceThe configuration is basically the same as the example, and basically the same operational effects are achieved. The following is shown in FIG.referenceThe explanation will focus on the differences from the example.. acidIn the porous gas flow path forming member 3E for the agent electrode, the porosity is set relatively large in the downstream region 93 and relatively small in the upstream region 91. And as shown by the characteristic line E1 of FIG. 8, the pore diameter is set so as to increase discontinuously from the upstream region 91 to the downstream region 93. Further, as shown by the characteristic line E2 in FIG. 8, the porosity is set to increase discontinuously from the upstream region 91 to the downstream region 93.
[0058]
  (No.3 ReferenceExample)
  FIG.3 ReferenceThe concept of an example is shown typically. BookreferenceAn example is shown in FIG.referenceThe configuration is basically the same as the example, and basically the same operational effects are achieved. The following is shown in FIG.referenceThe description will focus on the differences from the example. In the gas flow path forming members 3F and 2F shown in FIG. 9, the pores are schematically shown as ◯. In the gas flow path forming members 3F and 2F, the pores communicate with each other, and the gas flow path forming members 3F and 2F have moisture permeability in the thickness direction. BookreferenceAccording to the example, as shown in FIG. 9, the average pore diameter is basically uniform in the porous gas flow path forming member 3F for the oxidant electrode. However, the moisture permeability between the first water passage 41 and the oxidant electrode 15 in the porous gas flow path forming member 3F for the oxidant electrode, specifically, the porosity is relative in the downstream region 93. The upstream area 91 is set relatively small.
[0059]
  BookreferenceAccording to the example, as is clear from FIG. 9, the gas flow path forming member 2F for the fuel electrode is not a dense body but is formed of a porous body having a large number of pores. The water permeability between the first water passage 41 and the fuel electrode 12 in the gas flow path forming member 2F for the fuel electrode, that is, the porosity in the gas flow path forming member 2F for the porous fuel electrode, is downstream. The side area 93X is set larger than the upstream area 91X.
[0060]
  Specifically, in the gas flow path forming member 2F for the porous fuel electrode, the porosity is set relatively small in the upstream region 91X and relatively large in the downstream region 93X. . That is, the porosity of the fuel electrode gas flow path forming member 2F is set so as to gradually and gradually increase from the upstream region 91X to the downstream region 93X.
[0061]
  A second water passage forming member 52 that forms a second water passage 42 is provided outside the gas flow passage forming member 2F for the fuel electrode. The second water passage 42 has a water supply port 43 and a water discharge port 44. By the suction operation of the water flow portion 49F, the cooling water from the water supply source 40 is sucked and flows into the second water flow path 42 in the same manner as the first water flow path 41.
[0062]
  BookreferenceAccording to the example, as shown in FIG. 9, for the porous gas flow path forming member 3 </ b> F for the oxidant electrode, the porosity is set relatively small in the upstream region 91, and the downstream side The area 93 is set relatively large. Similarly, the porosity of the gas flow path forming member 2F for the fuel electrode is set to be relatively small in the upstream region 91X and relatively large in the downstream region 93X.
[0063]
  For this reason, when the water from the water supply source 40 is sucked into the first water passage 41 and the second water passage 42 by the suction operation of the second water passage portion 49F, the excess water remaining on the MEA 1 side is The downstream regions 93 and 93X having a large average pore diameter and porosity are more easily sucked in the direction of the arrow M2 toward the first water passage 41 and the second water passage 42 than the upstream regions 91 and 91X. As a result, the amount of excess water sucked and removed can be relatively increased in the downstream regions 93 and 93X where the excess water tends to stay, which can contribute to suppressing flooding in the downstream regions 93 and 93X. .
[0064]
  (No.4 ReferenceExample)
  FIG.4 ReferenceThe concept of an example is shown typically. BookreferenceAn example is shown in FIG.referenceThe configuration is basically the same as the example, and basically the same operational effects are achieved. The following is shown in FIG.referenceThe description will focus on the differences from the example. In the gas flow path forming members 3F and 2F shown in FIG. 10, the pores are schematically shown as ◯. In the gas flow path forming members 3F and 2F, the pores communicate with each other, and the gas flow path forming members 3F and 2F have moisture permeability in the thickness direction.
[0065]
  BookreferenceAccording to the example, as shown in FIG. 10, the water repellent 8 is attached to the surface of the gas flow path forming member 3F for the oxidant electrode and the inner wall surface of the pore. The water repellent 8 is also attached to the surface of the gas flow path forming member 2F for the fuel electrode and the inner wall surface of the pore. FIG. 10 schematically illustrates the strength of the water repellent 8 and does not indicate the thickness of the water repellent 8. When the ratio of the water repellent 8 is large per unit volume of the gas flow path forming member 3F for the oxidant electrode and the gas flow path forming member 2F for the fuel electrode, water is repelled, so that water can be taken in and out of the MEA 1. It becomes difficult to do. In addition, if the ratio of the water repellent 8 is small or there is no water repellent, water can be taken in and out of the MEA 1 more easily than when the ratio of the water repellent 8 is large.
[0066]
  BookreferenceAccording to the example, the ratio of the water repellent 8 in the porous gas flow path forming member 3F for the oxidant electrode is set so as to change along the direction in which the oxidant-containing gas flows. Similarly, the ratio of the water repellent 8 in the gas flow path forming member 2F for the porous fuel electrode is set so as to change along the direction in which the fuel gas flows.
[0067]
  That is, the ratio of the water repellent 8 in the porous gas flow path forming member 3 </ b> F for the oxidant electrode is set so as not to be present in the downstream region 93 or relatively smaller than that in the upstream region 91. In addition, the ratio of the water repellent 8 in the gas flow path forming member 2F for the porous fuel electrode is set so as not to be present in the downstream region 93X or relatively smaller than that in the upstream region 91X.
[0068]
  For this reason, when the water from the water supply source 40 is sucked into the first water passage 41 and the second water passage 42 by the suction operation of the water passage portion 49F, the excess water stayed on the MEA 1 side. Is likely to be sucked out in the direction of the arrow M2 toward the first water passage 41 and the second water passage 42 in the downstream regions 93 and 93X in which the ratio of the water repellent 8 is relatively small. Therefore, the retention of excess water in the downstream regions 93 and 93X can be suppressed. As a result, the downstream region 93 where excess water tends to stay.,The flooding phenomenon in 93X can be suppressed. As a result, it can contribute to improving the power generation performance of the polymer electrolyte fuel cell.
[0069]
  (Production example)
  FIG.11 and FIG.12 shows typically the cross section of the porous body 200 which concerns on the manufacture example 1 which can become the porous gas flow path formation member 3 for oxidant electrodes. According to Production Example 1, in the first step, as shown in FIG. 11, a porous body 200 in which one end 201 side is thick and the other end 203 side is thin is produced. The porous body 200 has a large number of pores. The pores can be formed by using a moderately erasable material such as a vaporizable sublimation material or a erasable burnt material and embedding the lost material, and then erasing the lost material by sublimation, burning, or the like. In the multi-body 200 that has undergone the first step, the average pore diameter and porosity are basically the same from one end 201 side to the other end 203 side.
[0070]
  Next, in the second step, the porous body 200 is compressed in the thickness direction based on the press pressure by the press die 100. As shown in FIG. 12, according to the porous body 200 after being compressed by the press die 100, the thickness is basically the same from the one end 201 side to the other end 203 side.
[0071]
  According to the porous body 200 after compression, the compression rate is set high on the one end 201 side, and the compression rate is set low on the other end 203 side. As a result, according to the compressed porous body 200, the density on the one end 201 side is high, and the density on the other end 203 side is low. Therefore, the average pore diameter and the porosity on the one end 201 side are set to be relatively small, and the average pore diameter and the porosity on the other end 203 side are set to be relatively large.
[0072]
  When the porous body 200 according to Production Example 1 is applied to the gas flow path forming member 3 for the oxidant electrode according to the embodiment shown in FIG. 1, the average pore diameter and pores of the compressed porous body 200 Since the rate is set small, the one end 201 side having a relatively high density can be set in the downstream region 93 of the gas flow path forming member 3 for the oxidant electrode. Further, since the average pore diameter and the porosity are set large, the other end 203 side having a relatively low density can be set as the upstream region 91 of the gas flow path forming member 3 for the oxidant electrode.
[0073]
  Also shown in FIG.referenceWhen the porous body 200 according to Production Example 1 is applied to the gas flow path forming member 3 for the oxidant electrode according to the example, the average pore diameter and the porosity of the compressed porous body 200 are relatively The one end 201 side having a relatively high density because it is set to be small can be set in the upstream region 91 of the gas flow path forming member 3 for the oxidant electrode. Further, since the average pore diameter and the porosity are set relatively large, the other end 203 side having a relatively low density is set as the downstream region 93 of the gas flow path forming member 3 for the oxidant electrode. Can do. The same applies to the gas flow path forming member 2 for the porous fuel electrode.
[0074]
  (Production Example 2)
  13 and 14 schematically show a cross section of a porous body 300 according to Production Example 2 that can be a porous gas flow path forming member 3 for an oxidant electrode. According to Production Example 2, in the first step, as shown in FIG. 13, a porous body 300 having basically the same thickness is produced from one end 301 side to the other end 303 side. The porous body 300 has a large number of pores. In this porous body 300, the average pore diameter and the porosity are set small on the one end 301 side and set large on the other end 303 side.
[0075]
  Next, in the second step, as shown in FIG. 14, the porous body 300 is compressed in the thickness direction based on the press pressure by the press die 100. According to the porous body 300 after compression, the average pore diameter and porosity on the one end 301 side are set small, and the average pore diameter and porosity on the other end 303 side are set large.
[0076]
  When the porous body 300 according to Production Example 2 is applied to the gas flow path forming member 3 for the oxidant electrode according to the embodiment shown in FIG. 1, the average pore diameter and pores in the compressed porous body 300 The one end 301 side where the rate is set small can be set in the downstream region 93 of the gas flow path forming member 3 for the oxidant electrode. Moreover, the other end 303 side where the average pore diameter and the porosity are set large can be set in the upstream region 91 of the gas flow path forming member 3 for the oxidant electrode.
[0077]
  Also shown in FIG.referenceWhen the porous body 300 according to Production Example 2 is applied to the gas flow path forming member 3B for the oxidant electrode according to the example, the average pore diameter and the porosity of the compressed porous body 300 are relatively The one end 301 side set to be small can be set in the downstream region 93 of the gas flow path forming member 3B for the oxidant electrode. Further, the other end 303 side where the average pore diameter and the porosity are set relatively large can be set in the upstream region 91 of the gas flow path forming member 3B for the oxidant electrode. The same applies to the gas flow path forming member 2 for the porous fuel electrode.
[0078]
  (Production Example 3)
  The porous body that can be the porous gas flow path forming member 3 for the oxidant electrode can be formed as follows. A matrix forming process for forming a matrix in which a disappearance substance is embedded using a disappearance substance of an appropriate size such as a vaporizable sublimation substance and a lossable burnout substance; The porous body forming step for forming the material can be performed in order. The disappearance trace of the disappearing substance becomes pores in the matrix. In the matrix forming step, by changing at least one of the size and the amount of the disappearing substance embedded in the matrix from one end to the other end of the matrix, at least one of the pore diameter and the porosity in the porous body. One can be changed.
[0079]
  (Others) The first catalyst layer 17 and the second catalyst layer 14 may be laminated on the front and back of the polymer electrolyte membrane 11. In addition, the present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications within a range not departing from the gist.
[0080]
  The following technical idea can also be grasped from the above description.
(Additional Item 1) A polymer electrolyte membrane having ion conductivity, a fuel electrode provided on one side of the polymer electrolyte membrane and supplied with fuel, and an oxidant-containing gas provided on the other side of the polymer electrolyte membrane A supplied oxidant electrode, a gas flow path forming member for the fuel electrode provided outside the fuel electrode, and a porous gas flow path forming member for the oxidant electrode provided outside the oxidant electrode; A solid passage comprising a water passage forming member that forms a water passage through which water flows outside the gas flow passage forming member for the oxidant electrode, and a water passage portion that pumps water through the water passage and flows water through the water passage. A polymer fuel cell,
  In the porous gas flow path forming member for the oxidant electrode, when the downstream where the oxidant gas flows is defined as a downstream region and the upstream where the oxidant gas flows is defined as an upstream region, a water repellent Is set to be smaller in the upstream region than in the downstream region.
  When the ratio of the water repellent is large, it is not easy to put water in and out. The ratio of the water repellent is set to be relatively large in the downstream region and relatively small in the upstream region. For this reason, it becomes advantageous to permeate | transmit the water of a water channel to the MEA side, and it can contribute to suppression of the excessive drying in the upstream area | region of MEA.
(Additional Item 2) A polymer electrolyte membrane having ion conductivity, a fuel electrode provided on one side of the polymer electrolyte membrane and supplied with fuel, and an oxidant-containing gas provided on the other side of the polymer electrolyte membrane A supplied oxidant electrode, a gas flow path forming member for the fuel electrode provided outside the fuel electrode, and a porous gas flow path forming member for the oxidant electrode provided outside the oxidant electrode; A water flow path forming member that forms a water flow path through which water flows outside the gas flow path forming member for the oxidant electrode, and a water flow section that sucks water from the water flow path and flows water through the water flow path. A polymer electrolyte fuel cell,
  In the porous gas flow path forming member for the oxidant electrode, when the downstream where the oxidant gas flows is defined as a downstream region and the upstream where the oxidant gas flows is defined as an upstream region, The ratio is set larger in the upstream region than in the downstream region. When the ratio of the water repellent is large, it is not easy to put water in and out. The ratio of the water repellent is set to be relatively large in the upstream region and relatively small in the downstream region. For this reason, it becomes advantageous to attract the surplus water in the downstream area of the MEA to the water channel, and can contribute to suppressing the retention of surplus water in the downstream area.
[0081]
【The invention's effect】
  BookAccording to the polymer electrolyte fuel cell of the invention, in the porous gas flow path forming member for the oxidant electrode, between the water channel and the oxidant electrode.In the thickness directionThe moisture permeability is set larger in the upstream region than in the downstream region. For this reason, in the upstream region which tends to be dried, the water supplied to the water passage can be effectively permeated toward the oxidizer electrode. Therefore, excessive drying in the upstream region of the oxidizer electrode, and hence excessive drying in the upstream region of the polymer electrolyte membrane can be suppressed. For this reason, it can contribute to equalizing the relative humidity in the MEA, which is advantageous for improving the power generation performance.The
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing the concept of a fuel cell according to a first embodiment.
FIG. 2 is a graph schematically showing changes in pore diameter and porosity according to the first example.
FIG. 3 is a graph schematically showing changes in pore diameter and porosity according to a second example.
FIG. 4 is a cross-sectional view schematically showing the concept of a fuel cell according to a third embodiment.
FIG. 5 is a cross-sectional view schematically showing the concept of a fuel cell according to a fourth embodiment.
FIG. 61 referenceIt is sectional drawing which shows typically the concept of the fuel cell which concerns on an example.
FIG. 71 referenceIt is a graph which shows typically change of a pore diameter and a porosity concerning an example.
FIG. 82 ReferenceIt is a graph which shows typically change of a pore diameter and a porosity concerning an example.
FIG. 93 ReferenceIt is sectional drawing which shows typically the concept of the fuel cell which concerns on an example.
FIG. 104 ReferenceIt is sectional drawing which shows typically the concept of the fuel cell which concerns on an example.
FIG. 11 is a cross-sectional view schematically showing the concept of the gas flow path forming member in a state before final compression according to Production Example 1 of the gas flow path forming member.
FIG. 12 is a cross-sectional view schematically showing the concept of the gas flow path forming member in a state after being finally compressed, according to Production Example 1 of the gas flow path forming member.
FIG. 13 is a cross-sectional view schematically showing the concept of the gas flow path forming member in a state before final compression according to Production Example 2 of the gas flow path forming member.
FIG. 14 is a cross-sectional view schematically showing the concept of the gas flow path forming member in a state after being finally compressed, according to Production Example 2 of the gas flow path forming member.
[Explanation of symbols]
  In the figure, 1 is an MEA, 11 is a polymer electrolyte membrane, 12 is a fuel electrode, 15 is an oxidant electrode, 2 is a gas flow path forming member for the fuel electrode, 3 is a gas flow path forming member for the oxidant electrode, Reference numeral 41 denotes a first water passage, 42 denotes a second water passage, 49 denotes a water passage, 51 denotes a water passage forming member, 91 denotes an upstream region, 93 denotes a downstream region, and 8 denotes a water repellent.

Claims (4)

A polymer electrolyte membrane having ion conductivity, a fuel electrode provided on one side of the polymer electrolyte membrane and supplied with fuel, and an oxidant-containing gas provided on the other side of the polymer electrolyte membrane An oxidant electrode, a gas flow path forming member for the fuel electrode provided on the outside of the fuel electrode, and a porous material for the oxidant electrode having a pore provided on the outside of the oxidant electrode and serving as a communication hole . A gas flow path forming member, a water flow path forming member that forms a water flow path through which water flows outside the gas flow path forming member for the oxidant electrode, and water is supplied to the water flow path to supply water to the water flow path A polymer electrolyte fuel cell comprising a flowing water flow portion,
In the porous gas flow path forming member for the oxidant electrode,
When the downstream where the oxidant gas flows is defined as a downstream region, and the upstream where the oxidant gas flows is defined as an upstream region,
At least moisture permeability one passes is set larger in the upstream region than the downstream region of the water and steam in the liquid phase state to Oite thickness direction between the water conduit and the oxidizing agent electrode A solid polymer fuel cell, characterized in that The porous gas channel forming member for the oxidant electrode according to claim 1, wherein at least one of the average pore diameter and the porosity is:
The polymer electrolyte fuel cell is characterized in that it is set larger in the upstream region than in the downstream region. In Claim 1 or Claim 2, in the gas channel forming member for the porous oxidant electrode, at least one of the average pore diameter and the porosity is:
It is set to be relatively large in the upstream region, is set to be relatively small in the downstream region, and is set to gradually decrease from the upstream region to the downstream region. Solid polymer fuel cell. 4. The porous gas flow path forming member for the oxidant electrode according to claim 1, wherein a ratio of the water repellent per unit volume is higher than the downstream region. The polymer electrolyte fuel cell is characterized by being set small in size.

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