JP5987759B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell.

  One cell (hereinafter also referred to as “unit cell”) constituting the fuel cell is configured, for example, by sandwiching a membrane electrode assembly between a gas diffusion layer and a separator. The membrane electrode assembly is a power generation module in which catalyst electrodes (anode and cathode) are joined to both surfaces of an electrolyte membrane. In addition, the gas flow path for flowing the reaction gas used for power generation is a groove flow path formed on the surface of the separator on the gas diffusion layer side, or a porous flow path member disposed between the gas diffusion layer and the separator. Consists of.

  Various techniques have been proposed for fuel cells. For example, in the following Patent Document 1, the separator-side surface of the anode-side gas diffusion layer has multi-row bottomed groove portions from the anode inflow side to the downstream side, and water components entering the groove portions are arranged downstream. A structure that wets the electrolyte membrane by carrying away is disclosed.

JP 2012-69260 A

  By the way, a seal portion (seal material) for sealing the anode side and the cathode side is provided around the membrane electrode assembly and the gas diffusion layer. This seal part provides fluidity around the membrane electrode assembly and the gas diffusion layer when the fuel cell unit cell is manufactured, for example, when the membrane electrode assembly and the gas diffusion layer are sandwiched between the separators and pressurized. It may be formed by drawing a liquid or gel-like sealing material (hereinafter referred to as “fluid sealing material”) and thermosetting it. In a unit cell having such a seal portion, a phenomenon called membrane thinning occurs in the electrolyte membrane at the outer peripheral portion of the membrane electrode assembly, and when the membrane thinning proceeds, the reaction gas crosses between the anode and the cathode. There was a problem that leakage increased and power generation performance decreased. However, Patent Document 1 does not have any description or suggestion regarding the membrane thinning of the electrolyte membrane generated at the outer peripheral portion of the membrane electrode assembly, and cannot solve the above problem. Further, in the conventional fuel cell, it has been desired to facilitate manufacture, reduce costs, and the like.

  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.

(1) According to one aspect of the present invention, a fuel cell is provided. The fuel cell includes a membrane electrode assembly in which an anode is formed on one surface of an electrolyte membrane and a cathode is formed on the other surface; an anode-side gas diffusion layer disposed on the surface of the anode; A cathode-side gas diffusion layer disposed on a surface; an anode-side separator and a cathode-side separator sandwiching the anode-side gas diffusion layer and the membrane-electrode assembly on which the cathode-side gas diffusion layer is disposed; and the anode-side gas And a seal part formed around the membrane electrode assembly in which the diffusion layer and the cathode side gas diffusion layer are disposed, and in the region including the cathode to the cathode side separator, An electrically insulating insulating region is formed in the outer peripheral region corresponding to the outer peripheral portion. There is a possibility that the supply amount may be insufficient if only the cathode gas is supplied by diffusion of the cathode side gas diffusion layer. On the outer periphery of the inside of the cathode, there is a possibility that the membrane of the electrolyte membrane may be thinned due to the electrochemical reaction of the cathode. On the other hand, in the fuel cell of this embodiment, since an electrically insulating insulating region is formed in the outer peripheral region corresponding to the outer peripheral portion inside the cathode, the electrochemical reaction in the outer peripheral portion inside the cathode By suppressing this, it is possible to suppress the thinning of the electrolyte membrane caused by the electrochemical reaction.

(2) In the fuel cell of the above aspect, the insulating region may be formed over the entire circumference of the outer peripheral portion inside the cathode. In the fuel cell of this embodiment, it is possible to suppress the electrochemical reaction over the entire circumference of the inner peripheral portion of the cathode, where supply amount may be insufficient only by supplying the cathode gas by diffusion of the cathode side gas diffusion layer. It becomes possible to suppress the thinning of the electrolyte membrane caused by the electrochemical reaction.

(3) In the fuel cell of the above aspect, the seal portion is formed by curing a fluid sealant having fluidity, and at least when the seal portion is formed in the outer peripheral region, The outer peripheral portion of the cathode-side gas diffusion layer includes a region sandwiched between regions in which the fluid sealing material flows inwardly from the outer periphery side and does not flow in the fluid sealing material. It may be. When the seal portion is formed by curing the fluid seal material, the outer periphery of the cathode-side gas diffusion layer is a region sandwiched by the region into which the fluid seal material flows, and the fluid seal material is In the outer peripheral part inside the cathode corresponding to the region that did not flow in, there is a possibility that the supply amount is insufficient only by the supply of the cathode gas by the diffusion of the cathode side gas diffusion layer, and the electrolyte is caused by the electrochemical reaction of the cathode. Film thinning may occur. On the other hand, in the fuel cell of this embodiment, since an electrically insulating insulating region is formed in the outer peripheral region including this region, the electric reaction is suppressed by suppressing the electrochemical reaction in the cathode disposed in this region. It is possible to suppress thinning of the electrolyte membrane caused by a chemical reaction.

(4) In the fuel cell of the above aspect, a cathode gas flow path for flowing a cathode gas along the surface of the cathode side gas diffusion layer and supplying the cathode gas to the cathode through the cathode side gas diffusion layer (I) formed on the surface of the cathode side separator on the cathode side gas diffusion layer side by a groove-like gas flow path, or (ii) between the cathode side separator and the cathode side gas diffusion layer. A conductive sealing plate for preventing the flowable sealing material from flowing into the cathode gas flow path when the seal portion is formed; Disposed between the seal portion and the cathode gas flow path; and the outer peripheral region includes at least a region where the sealing plate is disposed. It may be. In the outer peripheral part inside the cathode corresponding to the area where the sealing plate is arranged, there is a possibility that the supply amount is insufficient only by the supply of the cathode gas by the diffusion of the cathode side gas diffusion layer, which is caused by the electrochemical reaction of the cathode. As a result, the electrolyte membrane may become thin. On the other hand, in the fuel cell of this embodiment, an electrically insulating insulating region is formed in the outer peripheral region including this region, so that the electrochemical reaction at the cathode disposed in this region is suppressed. Therefore, it is possible to suppress the thinning of the electrolyte membrane caused by the electrochemical reaction.

(5) In the fuel cell of the above aspect, a space region independent of the cathode gas flow channel is formed on a surface on the cathode side gas diffusion layer side of the cathode side separator on the outer peripheral side of the cathode gas flow channel. And the outer peripheral region may include at least a region where the space region is formed. In the outer peripheral part inside the cathode located in the space region formed on the outer peripheral side of the cathode gas flow path, there is a possibility that the supply amount is insufficient only by the supply of the cathode gas by the diffusion of the cathode side gas diffusion layer. Due to the electrochemical reaction, the electrolyte membrane may become thin. On the other hand, in the fuel cell of this embodiment, since an electrically insulating insulating region is formed in the outer peripheral region including this region, the electrochemical reaction in the cathode disposed in this region is suppressed. It is possible to suppress the thinning of the electrolyte membrane caused by the electrochemical reaction.

(6) In the fuel cell of the above aspect, the insulating region may be formed by insulating at least one layer from the cathode side gas diffusion layer to the cathode side separator in the outer peripheral region. In this type of fuel cell, it is possible to easily form an insulating region in the outer peripheral region.

(7) In the fuel cell of the above aspect, the insulating region is formed by disposing an insulating member between any one of a plurality of layers from the cathode to the cathode-side separator in the outer peripheral region. You may be made to do. Even in this form of fuel cell, it is possible to easily form an insulating region in the outer peripheral region.

  The present invention can be implemented in various forms other than the above. For example, it can be realized in the form of a fuel cell in which a plurality of fuel cells are stacked.

It is a perspective view showing roughly the composition of the unit cell of the fuel cell as a 1st embodiment of the present invention. It is sectional drawing which shows the cross section of a unit cell roughly. It is the top view which looked at the cathode side gas diffusion layer and cathode of a unit cell from the cathode side separator side. It is explanatory drawing shown about the insulation area | region formed in the outer peripheral part of the cathode side gas diffusion layer corresponding to the outer peripheral part of the cathode in the BB cross section of FIG.2 (b). It is explanatory drawing shown about the insulation area | region formed in the outer peripheral part of the cathode side gas diffusion layer corresponding to the outer peripheral part of the cathode in CC cross section of FIG.2 (c). It is explanatory drawing which shows the modification at the time of making the gas flow path by the side of a cathode into a groove-shaped gas flow path. It is the top view which looked at the flow-path formation part, the cathode side gas diffusion layer, and cathode of the unit cell as 2nd Embodiment of this invention from the cathode side separator side. It is explanatory drawing shown about the insulation area | region formed in the outer peripheral part of a flow-path formation part. It is the top view which looked at the cathode side gas diffusion layer and cathode of a unit cell as a 3rd embodiment of the present invention from the cathode side separator side. It is explanatory drawing shown about the insulation area | region formed in the outer peripheral part of a cathode side separator. It is explanatory drawing shown about the unit cell as 4th Embodiment of this invention. It is explanatory drawing which shows the modification in case an insulation area | region is formed in a sealing plate. It is explanatory drawing shown about the unit cell as 5th Embodiment of this invention. It is explanatory drawing which shows the modification in case an insulation area | region is formed with an insulating film. It is a perspective view which shows roughly the structure of the unit cell as 6th Embodiment of this invention. It is sectional drawing which shows the AA cross section of FIG. 15 roughly. It is sectional drawing which shows the BB cross section of FIG. 15 roughly. It is the top view which looked at the cathode side gas diffusion layer and cathode of a unit cell from the cathode side separator side.

A. First embodiment:
A1. Schematic configuration of fuel cell:
FIG. 1 is a perspective view schematically showing a configuration of a unit cell 100 of a fuel cell as a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section of the unit cell 100. 2A, 2B, and 2C show the AA, BB, and CC sections of the unit cell 100 of FIG. 1, respectively. Normally, a stack type fuel cell is formed by stacking a plurality of unit cells 100.

  The unit cell 100 includes a membrane electrode assembly 10 (Membrane Electrode Assembly, MEA) as shown in FIG. The membrane electrode assembly 10 is a power generator module in which an anode 12 a and a cathode 12 c are formed on both surfaces of an electrolyte membrane 11. The unit cell 100 has a gas diffusion layer (hereinafter also referred to as “anode side gas diffusion layer”) 20a and a separator (hereinafter referred to as “anode side”) on the anode side so as to sandwich the membrane electrode assembly 10 from both sides. And a gas diffusion layer (hereinafter also referred to as “cathode side gas diffusion layer”) 20c, a flow path forming portion 30c, and a separator (hereinafter also referred to as “cathode side separator”). 40c). Further, as shown in FIGS. 2B and 2C, the unit cell 100 includes a membrane electrode assembly 10, gas diffusion layers 20a and 20c, and a flow path forming portion 30c between a pair of separators 40a and 40c. The sealing part 50 which covers the circumference | surroundings is provided.

  The schematic perspective view of the unit cell 100 in FIG. 1A shows a cathode-side separator 40c located on the upper side in order to mainly show an outline of the surface on the gas diffusion layer 20a side of the anode-side separator 40a located on the lower side. It is indicated by a broken line. Further, other elements (membrane electrode assembly 10, gas diffusion layers 20a and 20c, flow path forming portion 30c, and seal portion 50) sandwiched between the pair of separators 40a and 40c are omitted.

  The electrolyte membrane 11 is a proton-conductive ion exchange membrane formed of a solid polymer material such as a fluorine resin or a hydrocarbon resin. The anode 12a and the cathode 12c include a catalyst (for example, platinum or a platinum alloy), and are formed by supporting these catalysts on a conductive carrier (for example, carbon particles). In the present embodiment, the size of the anode 12a is substantially the same as that of the electrolyte membrane 11 as shown in FIGS. 2 (b) and 2 (c). In the present embodiment, the size of the cathode 12c is smaller than the size of the anode 12a and larger than the cathode-side gas diffusion layer 20c as shown in FIGS. 2 (b) and 2 (c).

  The anode side gas diffusion layer 20a is disposed on the surface of the anode 12a, and the cathode side gas diffusion layer 20c is disposed on the surface of the cathode 12c. As a member for forming the gas diffusion layers 20a and 20c, a gas permeable conductive member such as carbon paper or carbon cloth is used. In the present embodiment, the size of the anode-side gas diffusion layer 20a is approximately the same as the size of the anode 12a of the membrane electrode assembly 10, as shown in FIGS. Further, in the present embodiment, the size of the cathode side gas diffusion layer 20c is smaller than the electrolyte membrane 11 of the membrane electrode assembly 10 and larger than the size of the cathode 12c, as shown in FIGS. 2 (b) and 2 (c). It was big.

  As described above, the flow path forming portion 30c is stacked on the surface of the cathode-side gas diffusion layer 20c. The flow path forming portion 30c is made of a porous material, and forms a gas flow path for flowing air as an oxidant gas (also referred to as “cathode gas”) along the surface of the cathode side gas diffusion layer 20c. As a member for forming the flow path forming portion 30c, a porous body having conductivity, for example, an expanded metal, a foamed metal sintered body, or the like is used.

  The cathode separator 40c is laminated on the surface of the flow path forming portion 30c and has a planar shape (see FIG. 2). The anode side separator 40a is laminated on the surface of the anode side gas diffusion layer 20a (see FIG. 2). The anode-side separator 40a has a gas flow path 42m for flowing hydrogen as a fuel gas (also referred to as “anode gas”) along the surface of the anode-side gas diffusion layer 20a, and a gas flow path 42m. A gas introduction passage 42i for introducing anode gas from the outside to the gas and a gas discharge passage 42o (not shown) for discharging exhaust gas (also referred to as “anode offgas”) to the outside from the gas passage 42m are configured. It has an uneven shape. The gas flow path 42m is divided into a plurality of groove-shaped flow paths 42mp. Similarly, the gas introduction channel 42i and the gas discharge channel 42o are divided into a plurality of groove-like channels. In addition, the uneven | corrugated shape which comprises a gas flow path comprises the cooling water path (not shown) for flowing cooling water along the surface between the cathode side separators 40c of the adjacent unit cell 100. FIG. As the structure of the flow path, various structures such as a serpentine type and a straight type are applied. As a member for forming the separators 40a and 40c, a gas impervious and conductive member, for example, a metal such as stainless steel, a dense carbon made by compressing carbon and impermeable to gas, or a baked carbon is used. And formed by press molding.

  As shown in FIG. 1, the separators 40a and 40c have a rectangular outer shape. The separators 40a and 40c are formed with a plurality of through holes penetrating in the thickness direction of the separators 40a and 40c. That is, the anode side separator 40a has a plurality of cathode gas introduction through holes 44ai for introducing the cathode gas (air) supplied from the outside of the unit cell 100 into the flow path forming portion 30c. It is formed along the lower left side of the figure. The separator 40a has a plurality of cathode offgas discharge through holes 44ao for discharging the cathode offgas discharged from the flow path forming portion 30c to the outside of the unit cell 100, and the other long side (upper right side in the figure). It is formed along. The separator 40a includes an anode gas introduction through hole 46ai for introducing the anode gas (hydrogen) supplied from the outside of the unit cell 100 into the gas passage 42m through the gas introduction passage 42i, and a unit cell. A plurality of cooling water introduction through holes 48ai for introducing cooling water supplied from outside 100 into the cooling water flow path are formed along one short side (lower right side in the figure). The separator 40a has an anode off-gas discharge through hole 46ao for discharging the anode off-gas discharged from the gas flow path 42m to the outside of the unit cell 100 through the gas discharge flow path 42o, and is discharged from the cooling water flow path. A plurality of cooling water discharge through holes 48ao for discharging the cooled water to the outside of the unit cell 100 are formed along the other short side (upper left side in the figure).

  Similarly, the cathode-side separator 40c has a plurality of cathode gas introduction through holes 44ci for introducing the cathode gas (air) supplied from the outside of the unit cell 100 into the flow path forming portion 30c. It is formed along (the lower left side of the figure). The separator 40c has a plurality of cathode offgas discharge through holes 44co for discharging the cathode offgas discharged from the flow path forming portion 30c to the outside of the unit cell 100, and the other long side (upper right side in the figure). It is formed along. The separator 40c includes an anode gas introduction through hole 46ci for introducing the anode gas (hydrogen) supplied from the outside of the unit cell 100 into the gas passage 42m through the gas introduction passage 42i, and the unit cell. A plurality of cooling water introduction through holes 48ci for introducing the cooling water supplied from outside 100 into the cooling water flow path are formed along one short side (lower right side in the figure). The separator 40a has an anode off-gas discharge through hole 46co for discharging the anode off-gas discharged from the gas flow path 42m to the outside of the unit cell 100 through the gas discharge flow path 42o, and is discharged from the cooling water flow path. A plurality of cooling water discharge through holes 48co for discharging the cooled water to the outside of the unit cell 100 are formed along the other short side (upper left side in the figure).

  The outer shapes of the separators 40a and 40c are actually in accordance with the space of the fastening members when the unit cells 100 are stacked to form a fuel cell having a stack structure, the shape of the fuel cell installation housing, and the like. Although it has a deformed outer shape, it has a rectangular shape because there is no particular relationship in the explanation of the invention.

Sealing portion 50, forming a pair of separators 40a, between the 40c, the outer peripheral portion of the gas diffusion layer 20a, the film 20c are stacked electrode assembly 10 and the flow path forming portion 30c, and, on the periphery of the through holes (See FIGS. 2B and 2C). The seal portion 50 is formed by curing a fluid sealant having fluidity (for example, liquid rubber).

  As the fluid sealing material, a thermosetting sealing material that always has fluidity before thermosetting, or a thermoplastic semi-cured sealing material that exhibits fluidity due to a decrease in viscosity during heating is used. For this reason, as shown in FIG. 2B, the gas introduction passage 42i is located between the seal portion 50 and the anode separator 40a on the gas passage 42m side of the anode gas introduction through hole 46ai. A sealing plate 60a for preventing inflow of the fluid sealant is disposed. Similarly, a sealing plate 60a is disposed on the gas flow path 42m side of the anode off gas discharge through hole 46ao and between the seal portion 50 and the anode separator 40a (not shown). Further, as shown in FIG. 2C, the fluidity sealing material is also provided between the seal portion 50 and the flow path forming portion 30c on the flow path forming portion 30c side of the cathode gas introduction through-hole 44ci. A sealing plate 60c for preventing inflow into the flow path forming portion 30c is disposed. Similarly, a sealing plate 60c (not shown) is disposed between the seal portion 50 and the flow path forming portion 30c on the flow path forming portion 30c side of the through-hole 44co for discharging the cathode off gas. As the sealing plates 60a and 60c, for example, conductive metal plates or carbon plates are used.

  In the present embodiment, the size of the flow path forming portion 30c is such that the long side is longer than the long side of the cathode-side gas diffusion layer 20c, as shown in FIGS. It is short and the length of the short side is longer than the distance between the cathode gas introduction through hole 44i and the cathode off gas discharge through hole 44o in the separator 40c.

  As shown in FIG. 2C, the flow path forming portion 30c is formed in the cathode gas introduction through hole 44ci over the entire width direction along the long side of the separator 40c when viewed from the thickness direction of the separator 40c. , And is formed so as to project into the cathode offgas discharge through hole 44co. Further, the sealing plate 60c also has a cathode gas introduction through-hole 44ci and a cathode off-gas discharge through-hole 44co over the entire width direction along the long side of the separator 40c when viewed from the thickness direction of the separator 40c. It is formed to project inside. Furthermore, when viewed from the thickness direction of the separator 40c, the sealing plate 60c extends in the cathode gas introduction through-hole 44ci over the entire width direction along the long side of the separator 40c, and in the cathode gas introduction through-hole 44ci. The cathode off-gas discharge through-hole 44co is formed so as to protrude.

A2. Structural features of the unit cell:
FIG. 3 is a plan view of the cathode side gas diffusion layer 20c and the cathode 12c of the unit cell 100 as viewed from the cathode side separator 40c side. However, in FIG. 3, the flow path forming portion 30c is omitted, the cathode side separator 40c is indicated by a broken line, the outer peripheral end of the cathode side gas diffusion layer 20c is indicated by a solid line frame, and the outer peripheral end of the cathode 12c is indicated by a one-dot chain line frame. Show. The unit cell 100 is characterized in that it has a structure having an electrically insulating insulating region 22 that is insulated on the outer periphery of the cathode-side gas diffusion layer 20c. As the insulation treatment, various insulation treatments such as PTFE coating, transparent fluororesin “CYTOP (registered trademark of AGC Asahi Glass Co., Ltd.)”, and fluorine plasma treatment can be applied. In addition, the insulating region can be formed by not performing gold plating or carbon coating on the outer peripheral portion. Below, this structure is explained in full detail using FIG. 4 and FIG.

  FIG. 4 is an explanatory view showing an insulating region 22 formed on the outer peripheral portion of the cathode-side gas diffusion layer 20c corresponding to the outer peripheral portion of the cathode 12c in the BB cross section of FIG. FIG. 4A shows this embodiment, and FIG. 4B shows a structure without an insulating region in the outer peripheral portion of the cathode side gas diffusion layer 20c as a comparative example. 4A and 4B, the upper part shows a cross-sectional view, and the lower part shows a plan view including the upper cross-sectional area, omitting the cathode separator 40c and the flow path forming part 30c.

  First, a comparative example will be described. As described above, when the seal portion 50 is formed by curing the fluid sealing material, in the formation process, the fluid sealing material includes the membrane electrode assembly 10, the gas diffusion layers 20a and 20c, and the flow path formation. It flows into the part 30c. As a result, an ineffective area is formed in which the membrane electrode assembly 10 that is a power generation module cannot generate power. In addition, the inflow of the fluid sealing material is not uniform, and the portion where the fluid sealing material flows (hereinafter also referred to as “sealing material inflow portion”) and the portion where the fluid sealing material does not flow (hereinafter referred to as “seal”). A mixed region is also formed, which is also referred to as a “material non-inflow portion”. Therefore, in the unit cell 100, a mixed region and an invalid region are formed in order from the inside toward the outside in the outer peripheral region outside the effective region where sufficient power generation is possible.

On the anode side, hydrogen (H ₂ ) as the anode gas supplied to the groove-like flow path 42mp of the gas flow path 42m through the gas introduction flow path 42i with respect to the gas diffusion layer 20a in the seal material non-inflow portion. Then, hydrogen is sufficiently supplied to the corresponding anode 12a.

  On the other hand, the following problems occur on the cathode side. Normally, air (Air) as a cathode gas flows through the gas diffusion layer 20c along the direction of the arrow in the figure. At this time, the seal material non-inflow portion sandwiched between the seal material inflow portions of the gas diffusion layer 20c is a region where air stays and the inflow of air is insufficient (so-called air accumulation, also referred to as “air supply insufficient region”). Become. As a result, the air supplied to the outer peripheral portion of the cathode 12c corresponding to the non-inflow portion of the sealing material is insufficient, and the oxygen partial pressure, specifically oxygen, is introduced by the inflow of permeated hydrogen from the anode 12a through the electrolyte membrane 11. The concentration decreases. As a result, the generation of hydrogen peroxide is increased, and the OH radicals generated thereby cause the resin constituting the electrolyte membrane 11 to be destroyed, thereby causing deterioration of the electrolyte membrane 11 (so-called film thinning).

  In the present embodiment, as shown in FIG. 3, an insulating region 22 is formed on the outer peripheral portion of the cathode-side gas diffusion layer 20c corresponding to the outer peripheral portion of the cathode 12c. Specifically, as shown in FIG. 4 (a), in the cathode side gas diffusion layer 20c, a mixed region (air supply shortage region, FIG. 4 (b) where the seal material inflow region sandwiched between the seal material inflow portions exists. The insulating region 22 is formed in the outer peripheral portion including the reference). As a result, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region, and to suppress the above-described film thinning due to the increase in hydrogen peroxide.

  FIG. 5 is an explanatory view showing an insulating region 22 formed on the outer peripheral portion of the cathode-side gas diffusion layer 20c corresponding to the outer peripheral portion of the cathode 12c in the CC cross section of FIG. 2 (c). FIG. 5A shows this embodiment, and FIG. 5B shows a structure having no outer peripheral insulating region than the outer peripheral end of the cathode-side gas diffusion layer 20c as a comparative example.

  First, a comparative example will be described. As mentioned in the description of FIG. 2C, the fluidity seal is provided between the seal portion 50 and the flow passage forming portion 30c on the flow passage forming portion 30c side of the through hole 44ci for introducing the cathode gas. A sealing plate 60c for preventing the material from flowing into the flow path forming portion 30c is disposed. Accordingly, in the cathode gas diffusion layer 20c below the sealing plate 60c, air is not directly supplied from the flow path forming portion 30c, so that it is difficult for air to flow in, the oxygen partial pressure is reduced, and air supply is insufficient. It becomes an area. As a result, similarly to the air pool in FIG. 4, the generation of hydrogen peroxide is increased, and the membrane of the electrolyte membrane 11 is thinned.

  In the present embodiment, as shown in FIG. 3, an insulating region 22 is formed on the outer peripheral portion of the cathode-side gas diffusion layer 20c corresponding to the outer peripheral portion of the cathode 12c. Specifically, as shown in FIG. 5A, the insulating region 22 is formed on the outer peripheral portion of the cathode-side gas diffusion layer 20c including the air supply insufficient region where the sealing plate 60c is disposed. As a result, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region under the sealing plate 60c, and to suppress the above-described film thinning due to the increase in hydrogen peroxide. In addition, the air supply shortage region under the sealing plate 60c described above may include the air supply shortage region due to the air reservoir described in FIG. 4, and this region is also included in the insulating region 22. It is possible to suppress film thinning.

  As described above, in FIG. 4, the cross section of the region of the sealing plate 60 a disposed in the anode gas introduction passage 42 i connected to the anode gas introduction through hole 46 ai has been described as an example. Although not shown, the same applies to the region of the sealing plate 60a disposed in the gas discharge passage 42o connected to the anode off-gas discharge through hole 46ao. In FIG. 5, the cross section of the portion where the sealing plate 60c is disposed between the flow path forming portion 30c and the cathode side gas diffusion layer 20c on the cathode gas introduction through hole 44ci side is described as an example. Although not shown, the same applies to the portion where the sealing plate 60c is disposed between the flow path forming portion 30c and the cathode side gas diffusion layer 20c on the cathode offgas discharge through hole 44co side. Although not shown, in other parts in the short side direction other than the part of the sealing plate 60a disposed on the anode side and in other parts in the long side direction other than the part of the sealing plate 60c disposed on the cathode side. Similarly, since the insulating region 22 is formed in the outer peripheral portion of the cathode-side gas diffusion layer 20c, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c and to suppress the film thinning.

A3. Modified configuration:
FIG. 6 is an explanatory view showing a modification in the case where the gas flow path on the cathode side is a groove-shaped gas flow path. 6A shows a cross section corresponding to FIG. 4, and FIG. 6B shows a cross section corresponding to FIG. In the above embodiment, the cathode-side gas flow path is formed by the flow path forming portion 30c. However, as with the anode side, the gas flow path 42cm having a plurality of groove-shaped flow paths 42cmp in the cathode-side separator 40c ′, the gas introduction The same applies to the case where the flow path 42ci and the gas discharge flow path 42co (not shown) are formed. Also in this case, as shown in FIG. 6A, in the outer peripheral portion of the cathode-side gas diffusion layer 20c, there is a mixed region (air supply shortage region, FIG. 4) where the seal material inflow region sandwiched between the seal material inflow portions exists. An insulating region 22 is formed on the outer periphery including (b). Further, as shown in FIG. 6B, an insulating region 22 is formed on the outer periphery of the cathode side gas diffusion layer 20c including the air supply insufficient region where the sealing plate 60c is disposed.

  In this embodiment, the case where the insulating region 22 is formed on the entire outer peripheral portion of the cathode-side gas diffusion layer 20c has been described as an example. However, the outer peripheral portion corresponding to the air supply shortage region where film thinning occurs is described. The insulating region may be formed so as to include at least the portion.

B. Second embodiment:
FIG. 7 is a plan view of the flow path forming portion 30c, the cathode side gas diffusion layer 20c, and the cathode 12c of the unit cell 100B as the second embodiment of the present invention as seen from the cathode side separator 40c side. In FIG. 7, as in FIG. 3, the cathode separator 40c is indicated by a broken line, the outer peripheral end of the flow path forming portion 30c is indicated by a two-dot chain line frame, and the outer peripheral end of the cathode side gas diffusion layer 20c is indicated by a solid line frame. The outer peripheral end of the cathode 12c is indicated by a one-dot chain line frame. The unit cell 100B of the present embodiment is characterized in that it has a structure having an electrically insulating insulating region 32 that is insulated on the outer periphery of the flow path forming portion 30c. As the insulation treatment, various insulation treatments such as PTFE coating, transparent fluororesin “CYTOP (registered trademark of AGC Asahi Glass Co., Ltd.)”, and fluorine plasma treatment can be applied. However, at the outer peripheral portion of the flow path forming portion 30c, if liquid water stays, it may freeze below freezing point and close the gas flow path to generate a gas shortage. It is desirable to insulate so that the contact angle becomes smaller, that is, the water repellency becomes higher.

  FIG. 8 is an explanatory diagram showing the insulating region 32 formed on the outer periphery of the flow path forming portion 30c. FIG. 8A shows a cross section corresponding to FIG. 4 of the unit cell 100 of the first embodiment, that is, the BB cross section of FIG. FIG. 8B shows a CC cross section of FIG. 7, that is, a cross section corresponding to FIG. 5 of the unit cell 100 of the first embodiment.

  In the unit cell 100B of the present embodiment, as shown in FIG. 8A, an insulating region 32 is formed in the outer peripheral portion of the flow path forming portion 30c corresponding to the outer peripheral portion of the cathode 12c including the air supply insufficient region in FIG. Has been. Further, as shown in FIG. 8B, an insulating region 32 is formed on the outer peripheral portion of the flow path forming portion 30c corresponding to the outer peripheral portion of the cathode 12c including the air supply shortage region of FIG. As a result, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region, and to suppress the above-described film thinning due to the increase in hydrogen peroxide.

  In the present embodiment, the case where the insulating region 32 is formed on the entire outer peripheral portion of the flow path forming portion 30c has been described as an example. However, the portion of the outer peripheral portion corresponding to the insufficient air supply region where film thinning occurs It suffices if the insulating region is formed so as to include at least.

C. Third embodiment:
FIG. 9 is a plan view of the cathode side gas diffusion layer 20c and the cathode 12c of the unit cell 100C according to the third embodiment of the present invention as viewed from the cathode separator 40c side. In FIG. 9, the flow path forming portion 30c is omitted, the outer peripheral end of the cathode side gas diffusion layer 20c is indicated by a solid line frame, and the outer peripheral end of the cathode 12c is indicated by a one-dot chain line frame. The unit cell 100C of this embodiment is characterized in that it has a structure having an electrically insulating insulating region 41 that is insulated on the outer periphery of the cathode separator 40c. As the insulation treatment, various insulation treatments such as PTFE coating, transparent fluororesin “CYTOP (registered trademark of AGC Asahi Glass Co., Ltd.)”, and fluorine plasma treatment can be applied. In the case of a separator using a metal material, a gold plating process or a carbon coating process is performed for the purpose of improving the corrosion resistance and reducing the contact resistance, but these processes can be performed by not performing these processes. Since the electric resistance is higher than that in the case where it is performed, it is possible to form an insulating region by not performing these treatments on the outer peripheral portion. However, in the flow path forming portion 30c adjacent to the outer peripheral portion of the cathode separator 40c, if liquid water stays, it may freeze below freezing point to close the gas flow path and generate gas shortage. It is desirable to insulate so that the corner has a smaller contact angle than that of the inner peripheral portion, that is, the water repellency is increased. Note that the process for increasing the water repellency is particularly important in the case of the groove-shaped gas flow path shown in FIG.

  FIG. 10 is an explanatory diagram showing the insulating region 41 formed on the outer peripheral portion of the cathode-side separator 40c. FIG. 10A shows a cross section corresponding to FIG. 4 of the unit cell 100 of the first embodiment, that is, the BB cross section of FIG. FIG. 10B shows a CC cross section of FIG. 9, that is, a cross section corresponding to FIG. 5 of the unit cell 100 of the first embodiment.

  In the unit cell 100C of this embodiment, as shown in FIG. 10A, an insulating region 41 is formed on the outer peripheral portion of the cathode-side separator 40c corresponding to the outer peripheral portion of the cathode 12c including the air supply shortage region of FIG. ing. Further, as shown in FIG. 10B, an insulating region 41 is formed on the outer peripheral portion of the cathode-side separator 40c corresponding to the outer peripheral portion of the cathode 12c including the air supply shortage region of FIG. As a result, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region, and to suppress the above-described film thinning due to the increase in hydrogen peroxide.

  In the present embodiment, the case where the insulating region 41 is formed on the entire outer peripheral portion of the cathode separator 40c has been described as an example. However, the outer peripheral portion corresponding to the air supply shortage region where film thinning occurs is used. It is only necessary that the insulating region is formed so as to include at least.

D. Fourth embodiment:
FIG. 11 is an explanatory diagram showing a unit cell 100D as the fourth embodiment of the present invention. FIG. 11 shows a cross section corresponding to FIG. 5 of the unit cell 100 of the first embodiment. In the unit cell 100D of the present embodiment, as shown in FIG. 11, an electrically insulating insulating region 61 that is insulated is formed on the entire conductive sealing plate 60c that is a cause of the air supply shortage region. It has a feature in that. As the insulation treatment, various insulation treatments such as PTFE coating, transparent fluororesin “CYTOP (registered trademark of AGC Asahi Glass Co., Ltd.)”, and fluorine plasma treatment can be applied. As a result, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region under the sealing plate 60c, and to suppress the above-described film thinning due to the increase in hydrogen peroxide.

  In the present embodiment, the case where the insulating region 61 is formed on the entire sealing plate 60c has been described as an example. However, the insulating region includes at least a portion corresponding to the air supply shortage region where film thinning occurs. It only has to be formed.

  FIG. 12 is an explanatory view showing a modification in the case where an insulating region is formed on the sealing plate. FIG. 12 corresponds to FIG. 5 of the unit cell 100 of the first dismantling as in FIG. 11, and the upper part shows a cross section and the lower part shows a plane including the upper cross-sectional area. The sealing plate 60Dc in the unit cell 100D ′ of the modified example includes portions corresponding to the cathode gas introduction through hole 44ci and the cathode off gas discharge through hole 44co of the cathode side separator 40DC formed of a conductive member such as a metal member. It is formed by bending the slit 49 inward along the flow path forming portion 30c. The insulating region 61 is formed by performing an insulating process on the bent portion of the sealing plate 60Dc.

  The supply of air as the cathode gas to the flow path forming unit 30c and the discharge of the cathode off gas from the flow path forming unit 30c are executed through the slit 49 portion.

  Also in this modification, the region where the insulating region 61 is formed does not need to be the entire sealing plate 60Dc, and the insulating region is formed so as to include at least a portion corresponding to the air supply shortage region where film thinning occurs. It only has to be.

E. Fifth embodiment:
FIG. 13 is an explanatory diagram showing a unit cell 100E as the fifth embodiment of the present invention. FIG. 13 shows a cross section corresponding to FIG. 4 of the unit cell 100 of the first embodiment. In the unit cell 100E of the present embodiment, as shown in FIG. 13, in the region including the air supply shortage region in the outer peripheral portion of the cathode 12c, the outer peripheral portion of the flow path forming portion 30c and the outer peripheral portion of the cathode side gas diffusion layer 20c. An electrically insulating insulating region is formed by the insulating film 70 therebetween. As the insulating film 70, for example, various insulating members such as a polyimide film such as a Kapton (trademark of Toray DuPont) film are used. The thickness is appropriately selected and set based on the relationship with the thickness of other layers. For example, an insulating member having a thickness of about 12.5 μm is used. As a result, also in the unit cell 100E of the present embodiment, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region, and to suppress the above-described film thinning due to the increase in hydrogen peroxide. Become.

  FIG. 14 is an explanatory view showing a modification in the case where the insulating region is formed of an insulating film. A unit cell 100E 'of FIG. 14A shows a case where an insulating film 70 is disposed between the cathode 12c and the gas diffusion layer 20c. Further, the unit cell 100E ″ of FIG. 14B shows a case where the insulating film 70 is disposed between the flow path forming portion 30c and the cathode side separator 40c. In any case, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region, and to suppress the above-described film thinning due to the increase in hydrogen peroxide.

  In the present embodiment and the modification, the case where the insulating region is formed by the insulating film 70 covering the inner peripheral side of the air supply shortage region to the outer peripheral end of the flow path forming portion 30c has been described. It suffices that the insulating region is formed by an insulating film disposed so as to include at least a portion corresponding to the air supply shortage region in which the thinning occurs.

F. Sixth embodiment:
FIG. 15 is a perspective view schematically showing a configuration of a unit cell 100F as the sixth embodiment of the present invention. 16 is a cross-sectional view schematically showing the AA cross section of FIG. 15, and FIG. 17 is a cross-sectional view schematically showing the BB cross section of FIG.

As shown in FIGS. 16 and 17, the unit cell 100F is different from the unit cells 100 to 100E (see FIGS. 1 to 5 and 7 to 14) of the first to fifth embodiments, and the flow path forming part 30c on the cathode side. Is omitted, and both the cathode side separator 40Fc and the anode side separator 40Fa have a structure in which a groove-like gas flow path is formed. However, the unit cell 100F is the same as the unit cells 100 to 100E of the other embodiments in that the membrane electrode assembly 10 and the gas diffusion layers 20a and 20c are sandwiched between a pair of separators 40Fa and 40Fc. The unit cell 100F is sealed around the membrane electrode assembly 10 between the pair of separators 40Fa and 40Fc, the outer periphery of the gas diffusion layers 20a and 20c, and the periphery of each through hole between the pair of separators 40Fa and 40Fc. The point where the part 50 is formed is the same as that of the unit cells 100 to 100E of the other embodiments. Furthermore, the unit cell 100F is the same as the unit cell 100 of the first embodiment in that the insulating region 22 is formed on the outer peripheral portion of the cathode-side gas diffusion layer 20c .

  FIG. 15 shows a perspective view of the cathode side separator 40Fc on the lower side and the anode side separator 40Fa on the upper side, contrary to FIG. FIG. 15 shows the anode-side separator 40Fa by a broken line and mainly shows other elements (membrane electrode assembly 10) in order to mainly show the outline of the gas flow path on the surface of the cathode-side separator 40Fc on the gas diffusion layer 20c side. The gas diffusion layers 20a and 20c and the seal portion 50) are omitted.

  The cathode side separator 40Fc is laminated on the surface of the cathode side gas diffusion layer 20c (see FIGS. 16 and 17). Further, the cathode side separator 40Fc has a gas flow path 42cm for flowing air as an oxidant gas (cathode gas) along the surface thereof on the cathode side gas diffusion layer 20c side, and the gas flow path 42cm from the outside. It has a concavo-convex shape constituting a gas introduction flow path 42ci for introducing a cathode gas and a gas discharge flow path 42co (not shown) for discharging the cathode off-gas from the gas flow path 42cm to the outside. The gas flow path 42 cm is divided into a plurality of groove-shaped flow paths 42 cmp. The gas introduction flow path 42ci and the gas discharge flow path 42co may or may not be divided into a plurality of groove-shaped flow paths.

  The anode side separator 40Fa is laminated on the surface of the anode side gas diffusion layer 20a (see FIGS. 16 and 17). The anode-side separator 40Fa has a gas channel 42am for flowing hydrogen as a fuel gas (anode gas) along the surface thereof on the anode-side gas diffusion layer 20a side, and a cathode from the outside to the gas channel 42am. It has a concavo-convex shape constituting a gas introduction flow path 42ai (not shown) for introducing gas and a gas discharge flow path 42ao (not shown) for discharging anode off gas from the gas flow path 42am to the outside. Yes. The gas flow path 42am is also divided into a plurality of groove-shaped flow paths 42amp, like the cathode-side gas flow path 42cm. The gas introduction flow path 42ai and the gas discharge flow path 42ao may also be divided into a plurality of groove-like flow paths as in the cathode gas introduction flow path 42ci and the gas discharge flow path 42co. Good.

  Adjacent unit cells 100C are stacked on the surface of the anode separator 40Fa opposite to the surface where the gas flow path is formed and the surface of the cathode side separator 40Fc opposite to the surface where the gas flow path is formed. The groove-shaped cooling water flow paths 43a and 43c for flowing the cooling water are respectively provided at the positions where they are combined with each other. The cooling water flow paths 43a and 43c are divided into a plurality of groove-shaped flow paths 43ap and 43cp, respectively.

  In addition, various structures, such as a serpentine type and a straight type, are applied as a structure of a gas flow path and a cooling water flow path. The separators 40Fa and 40Fc are made of gas-impermeable and conductive members, such as metal such as stainless steel, and dense carbon, baked carbon, or the like that is compressed by gas and impermeable to gas. It is formed by molding, cutting molding or the like.

  As shown in FIG. 15, the separators 40Fa and 40Fc have a rectangular outer shape. The cathode separator 40Fc includes a plurality of cathode gas introduction through holes 44ci, a cooling water introduction through hole 48ci, and an anode off gas discharge through hole 46co along one short side (lower right side in the figure). Is formed. Further, in the separator 40Fc, a cooling water discharge through hole 48co, an anode gas introduction through hole 46ci, and a cathode off gas discharge through hole 44co are formed along the other short side (upper left side in the figure). . Similarly, the anode separator 40Fa has a plurality of cathode gas introduction through holes 44ai, cooling water introduction through holes 48ai, and anode off gas discharge through holes 46ao along one short side (lower right side in the figure). Is formed. Further, in the separator 40Fa, a cooling water discharge through hole 48ao, an anode gas introduction through hole 46ai, and a cathode off gas discharge through hole 44ao are formed along the other short side (upper left side in the figure). .

  FIG. 18 is a plan view of the cathode-side gas diffusion layer 20c and the cathode 12c of the unit cell 100F as viewed from the cathode-side separator 40Fc side. 18 omits the flow path forming portion 30c, shows the cathode-side separator 40F with a broken line, shows the outer peripheral end of the cathode-side gas diffusion layer 20c with a solid line frame, and shows the outer periphery of the cathode 12c. The end is shown with the dashed-dotted line frame. Similar to the unit cell 100 of the first embodiment (see FIG. 3), the unit cell 100F has a structure having an electrically insulating insulating region 22 that is insulated on the outer periphery of the cathode-side gas diffusion layer 20c. It has a feature in that.

  As shown in FIG. 16, also in the unit cell 100F of the present embodiment, as in the first embodiment (see FIG. 5), sealing is performed at a position corresponding to the gas introduction flow path 42cmi that guides the cathode gas to the gas flow path 42cm. Since the plate 60c is disposed, an air supply insufficient region is generated below the sealing plate 60c. However, also in the unit cell 100F of the present embodiment, the insulating region 22 is formed on the outer peripheral portion of the cathode side gas diffusion layer 20c including the air supply insufficient region where the sealing plate 60c is disposed. As a result, it is possible to suppress the electrochemical reaction in the outer peripheral portion of the cathode 12c corresponding to the air supply shortage region under the sealing plate 60c, and to suppress the above-described film thinning due to the increase in hydrogen peroxide. In FIG. 16, the cross section of the gas introduction flow path 42 cmi portion of the cathode gas has been described as an example. Although not shown, the same applies to the cathode discharge gas discharge channel 42 cmo. In addition, the air supply shortage region under the sealing plate 60c described above may include the air supply shortage region due to the air reservoir described in FIG. 4, and this region is also included in the insulating region 22. It is possible to suppress film thinning.

  Further, as shown in FIG. 17, in the unit cell 100F of the present embodiment, a closed space region 42ca that is not directly connected to the gas flow path may be formed on the outer peripheral side of the effective region. The effective region is a region where the anode gas (hydrogen) and the cathode gas (air) are sufficiently supplied via the cathode-side gas flow channel 42 cm and the anode-side gas flow channel 42 am. This is a region that functions as a power generation unit.

  In the space region 42ca, in the membrane electrode assembly 10 and the gas diffusion layers 20a and 20c, the fluid sealing material forming the seal portion 50 is not flowed in, and a portion where an electrochemical reaction occurs due to gas supply. May be included. Air flows into the reaction portion by diffusion of the gas diffusion layer 20c on the cathode side, and hydrogen flows in by diffusion of the gas diffusion layer 20a on the anode side. Hydrogen and air flowing in by diffusion are not sufficient, but when hydrogen and air are compared, hydrogen flows more easily than air. For this reason, the space region 42 ca, particularly the reaction portion, becomes a region where air supply is insufficient, and the membrane failure of the electrolyte membrane 11 occurs.

  However, in the unit cell 100F of the present embodiment, as shown in FIG. 17, the insulating region 22 is formed in the cathode-side gas diffusion layer 20c included in the space region 42ca. As a result, the electrochemical reaction is suppressed in the space region 42ca that is the air supply shortage region, and the above-described film thinning due to the increase in hydrogen peroxide can be suppressed. In addition, although illustration is abbreviate | omitted, it is the same also in other parts of the short side direction other than the part of the sealing plate 60c arrange | positioned at the cathode side.

  Further, in the present embodiment, the case where the insulating region 22 is formed in the outer peripheral portion of the cathode side gas diffusion layer is described as an example. However, as in the unit cell 100C of the third embodiment, the insulating region is provided in the cathode side separator 40FC. 41 may be formed. Further, an insulating region may be formed on a conductive sealing plate as in the unit cell 100D of the fourth embodiment. Moreover, you may make it form an insulation area | region with the insulating film 70 like the unit cell 100E of 5th Embodiment.

F. Variations:
F1. Modification 1:
In the above embodiment, the case where the anode-side gas flow path is a groove-shaped gas flow path and the cathode-side gas flow path is a flow path forming portion or a groove-shaped gas flow path made of a porous body has been described as an example. The gas flow path on the anode side may also be a flow path forming section made of a porous material.

F2. Modification 2:
In the above embodiment, the case where an insulating region is formed by insulating one of the layers from the cathode side gas diffusion layer to the cathode side separator has been described as an example. However, a plurality of layers are insulated. Thus, an insulating region may be formed.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Membrane electrode assembly 11 ... Electrolyte membrane 12a ... Anode 12c ... Cathode 20a, 20c ... Gas diffusion layer 22 ... Insulation region 30c ... Channel formation part 32 ... Insulation region 40a, 40c ... Separator 40Fa, 40Fc ... Separator 41 ... Insulation Area 42m ... Gas flow path 42cmi ... Gas introduction flow path 42cmo ... Gas discharge flow path 42amp ... Groove-shaped flow path 42cmp ... Groove-shaped flow path 42i ... Gas introduction flow path 42o ... Gas discharge flow path 42ca ... Spatial area 42ai ... Gas introduction Channel 42ci ... Gas inlet channel 42am ... Gas channel 42ao ... Gas outlet channel 42co ... Gas outlet channel 42mp ... Groove channel 43a, 43c ... Cooling water channel 43ap, 43cp ... Groove channel 44i ... Cathode gas Through hole for introduction 44o ... Through hole for discharging cathode off gas 44ai, 44ci ... Cathode gas Inlet through holes 44ao, 44co ... Cathode off gas discharge through holes 46ai, 46ci ... Anode gas introduction through holes 46ao, 46co ... Anode off gas discharge through holes 48ai, 48ci ... Cooling water introduction through holes 48ao, 48co ... Cooling water Discharge through-hole 49 ... Slit 50 ... Seal part 60a, 60c ... Sealing plate 60Dc ... Sealing plate 61 ... Insulating region 70 ... Insulating film 100 ... Unit cell 100B ... Unit cell 100C ... Unit cell 100D, 100D '... Unit cell 100E , 100E ', 100E''... unit cell 100F ... unit cell

Claims (7)

A fuel cell,
A membrane electrode assembly in which an anode is formed on one surface of an electrolyte membrane and a cathode is formed on the other surface;
An anode-side gas diffusion layer disposed on the surface of the anode;
A cathode-side gas diffusion layer disposed on the surface of the cathode;
An anode separator and a cathode separator that sandwich the membrane electrode assembly in which the anode gas diffusion layer and the cathode gas diffusion layer are disposed;
A seal portion formed around the membrane electrode assembly in which the anode-side gas diffusion layer and the cathode-side gas diffusion layer are disposed;
With
An electrically insulating insulating region is formed in an outer peripheral region corresponding to an inner peripheral portion of the cathode in a region including the cathode to the cathode separator. The fuel cell according to claim 1,
The fuel cell according to claim 1, wherein the insulating region is formed over the entire circumference of the outer peripheral portion inside the cathode. The fuel cell according to claim 1 or 2, wherein
The seal part is formed by curing a fluid sealant having fluidity,
In the outer peripheral region, at least when the seal portion is formed, in the outer peripheral portion of the cathode-side gas diffusion layer, the region sandwiched by the region into which the fluid sealing material flows inward from the outer peripheral side And a region where the fluid sealing material has not flowed is included. The fuel cell according to claim 3 , wherein
A cathode gas flow path for flowing a cathode gas along the surface of the cathode side gas diffusion layer and supplying the cathode gas to the cathode through the cathode side gas diffusion layer includes: (i) the cathode side separator; Formed on the surface of the cathode side gas diffusion layer by a groove-like gas flow path, or (ii) formed by a flow path forming member disposed between the cathode side separator and the cathode side gas diffusion layer Has been
A conductive sealing plate for preventing the flowable sealing material from flowing into the cathode gas flow path when the seal part is formed is disposed between the seal part and the cathode gas flow path. Has been
The fuel cell, wherein the outer peripheral region includes at least a region where the sealing plate is disposed. The fuel cell according to claim 4 , wherein
The cathode gas channel is formed by the groove-shaped gas channel,
On the cathode side gas diffusion layer side surface of the cathode side separator, a space region independent of the cathode gas channel is formed on the outer peripheral side of the cathode gas channel,
The fuel cell, wherein the outer peripheral region includes at least a region where the space region is formed. A fuel cell according to any one of claims 1 to 5, wherein
The insulating region is formed by insulating at least one layer from the cathode side gas diffusion layer to the cathode side separator in the outer peripheral region. A fuel cell according to any one of claims 1 to 5, wherein
The insulating region is formed by disposing an insulating member between any one of a plurality of layers from the cathode to the cathode-side separator in the outer peripheral region.

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