JP2010282940A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of effectively preventing different kinds of materials from adhering or the like to an electrolyte film in a cell of fuel cell, superior in efficiency in maintenance such as extracting and changing cells of the fuel cell with performance degraded in a fuel cell stack, and superior in fluid sealing properties. <P>SOLUTION: A plurality of cells 10 of fuel cell each composed of a membrane electrode assembly (electrode 4), gas-permeating layers 5, 6, and a separator 7 arranged at an either gas-permeating layer side, are laminated, and a gasket 8 is integrally formed at a peripheral edge of each laminated membrane electrode assembly or the like to have one module 100 composed of the plurality of cells 10 of fuel cell. The modules are laminated to form a fuel cell stack, or just one module 100 is to form the fuel cell stack for the fuel cell. On a surface of the separator 7 contacting the gasket 8, an adhesion area S adhering to the gasket 8 and a non-adhesion area HS not adhering to the gasket 8 are formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell in which a gasket is integrally formed with a plurality of fuel cells to form one module, and a plurality of the modules are stacked or a fuel cell stack is formed from the one module. is there.

  A fuel cell of a polymer electrolyte fuel cell has a membrane electrode assembly (MEA) formed from an ion-permeable electrolyte membrane and an anode-side and cathode-side catalyst layer sandwiching the electrolyte membrane. For example, an electrode body (MEGA: MEMBRANE ELECTRODE & GAS DIFFUSION LAYER ASSEMBLY) is formed from the MEA and the anode-side and cathode-side gas diffusion layers (GDL) sandwiching the MEA, and a fuel gas or an oxidant gas is formed in the electrode body. And a gas flow path layer made of a metal porous body for collecting electricity generated by an electrochemical reaction and a separator are arranged on both sides of the electrode body. In addition, the fuel cell in which the gas flow channel groove is formed in the separator is also a conventional one, and in this case, the metal porous body that becomes the gas flow channel layer is unnecessary. An actual fuel cell stack is formed by stacking and stacking a number of fuel cell cells according to required power.

  In the fuel cell having the above structure, the electrode body includes a gasket for sealing a fluid such as a fuel gas and an oxidant gas supplied to the membrane electrode assembly, and a cooling water for suppressing the temperature rise of the cell. It is formed at the periphery. This gasket is formed for each fuel cell, and stacking is performed after stacking a predetermined number of fuel cells each having a gasket on the periphery of the electrode body. This gasket molding is generally performed by injection molding or compression molding. For example, in the case of compression molding, a separator is accommodated in a cavity of a molding die, and then either a metal porous body on the anode side or cathode side serving as a gas flow path is accommodated, and then an electrode body or a membrane electrode assembly is mounted. Next, in a posture in which the other metal porous body on the anode side or the cathode side is accommodated, a relatively hard resin is injected into the mold, and the mold is compressed while maintaining a high-temperature atmosphere. A resin gasket is formed on the periphery.

  The separator described above has a three-layer structure in which a plate in which a flow path is formed between two plates made of titanium or stainless steel, for example, or an intermediate layer made of a resin frame material. There is a type in which a large number of dimples and ribs defining a flow path are projected from one side of a plate to form a cooling water flow path (a separator having such a structure is also included in a three-layered separator). The separator having such a structure is either the anode side or the cathode side separator of the cell itself, and at the same time the other separator on the anode side or the cathode side of the adjacent cell in the stacked posture. That is, the cell constituent member of the fuel cell having this three-layer structure separator includes one three-layer structure separator, a metal porous body (gas channel layer) on the anode side and the cathode side, and a membrane electrode assembly or electrode body. In a posture in which a plurality of fuel cells are stacked, an arbitrary fuel cell has anode-side and cathode-side separators at both ends thereof.

  As described above, the conventional fuel cell stack is stacked by stacking fuel cells in which gaskets are formed. For example, in the case where a fuel cell stack is formed by stacking about 200 to 400 fuel cells, each fuel cell is provided with a unique voltage sensor, and the cell voltage drops below a predetermined value. When the cell is specified, the fuel cell is extracted from the stack and replaced with another fuel cell.

  However, it is easy to understand that the task of releasing stacking from a fuel cell stack in which a large number of fuel cells are stacked, extracting only the fuel cells that need replacement and replacing them with separate cells is extremely complicated, Improvements are screamed in the field.

  By the way, the electrolyte membrane constituting the membrane electrode assembly is in fluid communication with the outside through a gas permeable layer such as a gas diffusion layer having a pore or a metal porous body. This electrolyte membrane greatly deteriorates its characteristics due to contamination of different materials. Therefore, in the present situation where all the fuel cells are injection-molded independently and then simply laminated, there is a risk that the electrolyte membranes of all the fuel cells are contaminated by different materials during this lamination. have.

  From this point of view as well, review and improvement of the manufacturing method of forming a fuel cell stack by forming a gasket by injection molding or the like for each fuel cell, and a fuel cell stack made by this manufacturing method Improvement of the structure is inevitable, and development for that is an urgent issue. In particular, as the stationary type of houses, etc., or the mobile type of hybrid vehicles, electric vehicles, etc., the spread of fuel cells has been steadily expanding, and it is necessary to satisfy both performance improvement and productivity improvement. In view of this, it is extremely important to develop a fuel cell that can effectively solve the aforementioned urgent problems.

  Therefore, as a result of earnest research, the present applicant has come up with a fuel cell having the following structure and has filed a separate patent application. This fuel cell is composed of an electrode body (MEGA), an anode-side and cathode-side porous body serving as a gas flow path for sandwiching the electrode body, and a separator on either the anode-side or cathode-side. A plurality of cells are stacked, and a gasket formed integrally with the periphery of each stacked electrode body and porous body is formed to form one module including a plurality of fuel battery cells, and the plurality of the modules are stacked. A fuel cell stack is formed.

  In this fuel cell, a plurality of fuel cells are stacked, and each fuel cell is connected by an integrally molded gasket to form one module (the gasket is a cell separator having the gasket as a constituent element) It is formed by stacking a plurality of modules and stacking them, so that it is referred to as a “multi-cell one-module fuel cell”. You can also According to this fuel cell, for example, since a plurality of fuel cells are laminated prior to gasket injection molding, the electrolyte membrane of most fuel cells constituting the fuel cell stack is manufactured in such a manufacturing process. Is effectively protected from contamination with dissimilar materials. Furthermore, the maintenance efficiency can be remarkably improved by extracting the fuel cell having a poor performance in units of modules including the cell.

  However, since a module is formed by integrating a plurality of fuel cells with a gasket as described above, the following new problem is assumed. The problem will be described with reference to FIG. In the illustrated fuel cell, two fuel cells CE, CE and a separator e at the upper end thereof are integrated by a gasket f to form a module MD, and a plurality of modules MD are stacked to form a fuel cell stack. To do. In the illustrated example, two of the modules MD are taken out, showing a state before stacking, and further cut by a cross section passing through the manifold M through which the fuel gas flows.

  In the fuel cell CE, an electrode body c is formed from a membrane electrode assembly a and cathode and anode gas diffusion layers b1 and b2 sandwiching the membrane electrode assembly a. Metal porous bodies d1 and d2 to be sandwiched are sandwiched, and a separator e having a three-layer structure is arranged on the metal porous body on the anode side to constitute one fuel cell CE. Here, the separator e having the three-layer structure is formed by plates e1 and e2 and an intermediate layer e3 interposed therebetween, and gas or cooling fluid (cooling water, cooling air, cooling ethylene glycol, etc.) is formed in the intermediate layer e3. ) Is formed.

  When a plurality of fuel cells CE,... Are integrally connected by a gasket f to form one module MD, the number of cells in which the thickly designed gas diffusion layer constitutes the module MD before stacking. On the other hand, since the end portion of the module MD is fixed with a gasket, the central region of the module MD bulges outward (X direction), and a so-called drum shape is likely to be formed. This is particularly noticeable when the pressure during injection molding of the gasket is higher than the compression force during stacking.

  In a multi-cell, one-module type fuel cell, the above-described drum-shaped deformation of the cell must be allowed, but if a drum-shaped deformation is exhibited as shown, peeling occurs at the adhesive interface between the separator and the gasket, In some cases, this peeling progresses to a crack in the gasket, which may cause a problem that the sealing performance at the end of the module MD is not secured. Moreover, as shown in the illustrated example, the modules MD and MD are excessively deformed in a drum shape, so that it is difficult to ensure the sealing performance at the joint interface end portion (region A in the drawing) between the modules MD and MD. The problem can arise.

  Although illustration is omitted, if the pressure at the time of injection molding of the gasket is excessively low compared to the compression force at the time of stacking, the center of the module is at the end by the compression force at the time of stacking, contrary to the illustrated example. In this case, there is a problem that the center of the electrode body is dented and the compression force during stacking is not sufficiently applied to the entire surface of the electrode body.

  Turning now to the published technology by the present applicant, Patent Document 1 discloses a fuel cell formed by adhering a gasket to a separator, etc., with respect to the fuel cell of the multi-cell 1 module described above. Although this fuel cell is also excellent in maintainability, the above-mentioned problem, that is, peeling occurs at the adhesive interface between the separator and the gasket, and in some cases, this peeling progresses to a crack in the gasket, and the sealing performance at the end of the module However, it will not be possible to effectively solve the problem that is no longer secured.

JP 2006-244765 A

  The present invention has been made in view of the above-described problems, and can effectively prevent foreign materials from being contaminated (attached, etc.) to the electrolyte membrane in each fuel cell forming the fuel cell stack. It is an object of the present invention to provide a fuel cell that is excellent in efficiency in maintenance such as extracting and replacing a fuel cell whose performance has deteriorated from the fuel cell stack, and further excellent in fluid sealability.

  In order to achieve the above object, a fuel cell according to the present invention comprises a membrane electrode assembly, a gas permeable layer disposed on both sides thereof, and a separator disposed on at least one of the gas permeable layers. A plurality of battery cells are stacked, and each of the stacked membrane electrode assemblies and a gas gasket integrally formed on the periphery of the gas permeable layer are formed to form one module including a plurality of fuel battery cells. A fuel cell in which a fuel cell stack is formed by stacking or only one of the modules, and a surface of the separator that comes into contact with the gasket is bonded to the gasket, and the gasket is bonded to the gasket. A non-adhesive region is provided.

  The fuel cell of the present invention is formed by forming a plurality of fuel cells as one module and laminating a plurality of the modules, or only one module as a fuel cell stack. In one module, for example, Each fuel battery cell is bonded to an adjacent fuel battery cell in a stacking posture by a gasket, but exhibits a structure in which a non-adhesive region is provided at a part of the interface between the gasket and the separator, for example, injection molding. The deformation followability of the gasket at the time of releasing the load (stress) at the time of subsequent demolding can be improved, so that the module deforms excessively in a drum shape, the interface between the gasket and the separator peels, A fuel cell that can effectively eliminate the problem that the fluid sealability is hindered due to, for example, part of the gasket breaking. A.

  There are various scales of modules constituting the above-described fuel cell (fuel cell stack). For example, in the case where 300 fuel cells are stacked to constitute one fuel cell, there are about 2 to 50 units. One module can be configured with a range of cell radix. In the case where a single module is formed by a plurality of fuel cells and a plurality of the modules are stacked to form a single fuel cell stack, this module can also be referred to as a multi-cell 1-module fuel cell or the like. .

  For example, when one module is composed of 30 fuel cells, the membrane electrode assemblies of the 28 fuel cells inside other than both ends are completely cut off from the outside during injection molding or compression molding. In other words, it is possible to suppress contamination of the electrolyte membrane constituting the membrane electrode assembly with different materials.

  In the fuel cell of the present invention, in each fuel cell constituting the fuel cell having the multi-cell one-module structure described above, an arbitrary fuel cell gasket is provided on the surface of the three-layer structure separator constituting the fuel cell. A non-adhesive region between the fuel cell and the three-layer structure separator adjacent to each other in the stacking posture. The stress is released at the time of demolding after the injection molding, and the deformation followability of the gasket is enhanced when a tensile force is applied to the gasket.

  For example, by providing the non-adhesion region, the adhesion region at the contact interface between the separator and the gasket becomes narrow, and as a result, the deformation followability of the gasket in the vicinity of the interface is improved. Therefore, the drum-shaped deformation mode described above is relaxed, and each joint surface of each constituent member of the cell structure at the time of demolding after injection molding assumes as flat a posture as possible. In this way, the excessive deformation mode is alleviated, and each joint surface of each component member assumes a flat as much as possible, so that the peeling does not progress from the non-adhesive region, and the gasket may be cracked. As a result, a fuel cell having a multi-cell one-module structure having high sealing properties can be obtained.

  It should be noted that a non-adhesive region is provided at the interface between the gasket and the separator. Therefore, when the adhesive region is reduced, the gasket and the separator are sufficiently bonded in the narrowed adhesive region against the tensile force acting when the stress is released. Needless to say, it is necessary to maintain the bonding posture. In other words, the range of the non-adhesion region and the formation site are determined within a range in which such an adhesion posture can be maintained.

  Here, the specific form of the non-adhesive region is not particularly limited, but the non-adhesive sheet or non-adhesive formed on a part of the contact surface of either the gasket or the separator. Any one of the coating layers can be mentioned. For example, a non-adhesive sheet or a non-adhesive seal is adhered to a facing surface on the side of a fuel battery cell adjacent to each other in a stacking posture, or a non-adhesive coating layer is applied. And a form in which these non-adhesive sheets and non-adhesive coating layers are provided on both the upper and lower separators sandwiching the gasket.

  As an example, a sheet (or seal) made of perfluorosulfonic acid or Teflon (registered trademark), which is excellent in non-adhesiveness with a rubber gasket and is a constituent material of a fuel cell, is bonded. Or the form etc. with which the solution which used these as a raw material was coated can be mentioned.

  The non-adhesive sheet and coating layer forming material, the contact surface part of the separator that provides the non-adhesive area, and its range are both the separator and gasket against the tensile force that acts on the gasket during demolding after injection molding. This is set as appropriate in consideration of the fact that the bonding posture is maintained and that a sufficient non-adhesive effect can be exhibited.

  Further, the structure of the fuel cell forming the module is such that a gas diffusion layer comprising a diffusion layer base material and a current collecting layer is provided on both the anode side and the cathode side of the membrane electrode assembly, and the anode side and the cathode side. Any one of them includes both of the forms including only the current collecting layer (the diffusion layer base material is discarded). In the present specification, any of these forms is referred to as an electrode body. In addition, in the fuel cell comprising this component unit, in addition to the structure in which a gas flow path layer (metal porous body such as expanded metal) is arranged between a so-called flat type separator and an electrode body, It includes a conventional general cell structure in which separators having gas flow channel grooves formed on both sides of the body are directly arranged.

  Furthermore, the “gas permeable layer” is meant to include both a gas diffusion layer and a gas flow path layer. Therefore, in a cell configuration that does not include a gas flow path layer, a “gas permeable layer” means a “gas diffusion layer”, and in a cell configuration that includes both a gas diffusion layer and a gas flow path layer, The “permeation layer” means either or both of “gas diffusion layer” and “gas flow path layer”. Further, in the form in which the gas permeable layer is formed of a laminate of the gas diffusion layer and the gas flow path layer made of the metal porous body, there is a form in which only the metal porous body protrudes laterally from the electrolyte membrane.

  As can be understood from the above description, according to the fuel cell of the present invention, a plurality of fuel cells are integrated with a gasket to form a module, and a plurality of modules are stacked to form a fuel cell stack. By forming the fuel cell stack from only one module, most of the electrolyte membranes of the fuel cell constituting the fuel cell stack are effectively protected from being contaminated with different materials during the manufacturing process of the fuel cell. can do. In addition, the presence of a non-adhesive region on a part of the separator surface that comes into contact with the gasket can enhance the deformation followability of the gasket against the tensile force acting when releasing the stress at the time of demolding after injection molding. Therefore, a fuel cell excellent in sealing performance can be obtained.

It is a longitudinal cross-sectional view of one embodiment of the fuel cell of the present invention. It is the enlarged view of one Embodiment which expanded II area | region of FIG. (A) is the schematic diagram explaining the deformation | transformation aspect of the gasket of the conventional structure when tensile force acted by the stress release at the time of the demolding after injection molding, (b) comprises the fuel cell of this invention. It is the schematic diagram explaining the deformation | transformation aspect of the gasket to do. It is the enlarged view of other embodiment which expanded the II area | region of FIG. It is the longitudinal cross-sectional view explaining the state which is related to the module by which a gasket is integrally molded by the peripheral edge of the electrode body of a some fuel cell, and this module is exhibiting the drum shape which protruded up and down in the center.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of a module in which a plurality of fuel cells are integrated with a gasket formed integrally. In this module 100, for example, 10 to 50 fuel cells 10,... Are stacked, and the gasket 8 is integrally formed.

  Each fuel cell 10 includes a separator 7 having a three-layer structure (in the figure, a separator on the anode side), a metal porous body 6 (gas permeable layer, gas flow path layer) on the anode side, and a membrane electrode assembly. 1 and an electrode body 4 composed of gas diffusion layers 2 and 3 (gas permeable layer) on the cathode side and anode side, and a metal porous body 5 (gas permeable layer and gas flow path layer) on the cathode side. . In addition to the illustrated example, a fuel cell that does not include the gas diffusion layers 2 and 3 may be used.

  Here, the electrolyte membrane constituting the membrane electrode assembly 1 is, for example, a fluorine ion exchange membrane having a sulfonic acid group or a carbonyl group, a substituted phenylene oxide, a sulfonated polyaryletherketone, a sulfonated polyarylethersulfone, a sulfone. It is formed from a non-fluorine polymer such as fluorinated phenylene sulfide.

  The catalyst layer is a mixture of a conductive carrier (particulate carbon carrier, etc.) on which a catalyst is supported, an electrolyte, and a dispersion solvent (organic solvent) to produce a catalyst solution (catalyst ink). A catalyst layer is formed by stretching a film on a substrate such as an electrolyte membrane or a gas diffusion layer in a layer shape with a coating blade to form a coating film, and drying in a hot air drying furnace or the like. Here, the electrolyte forming the catalyst solution is a proton conductive polymer, an ion exchange resin having a skeleton of an organic fluorine-containing polymer, such as a perfluorocarbon sulfonic acid resin, a sulfonated polyether ketone, a sulfonated polyether. Sulfonated plastic electrolytes such as sulfone, sulfonated polyetherethersulfone, sulfonated polysulfone, sulfonated polysulfide, sulfonated polyphenylene, sulfoalkylated polyetheretherketone, sulfoalkylated polyethersulfone, sulfoalkylated polyetherethersulfone And sulfoalkylated plastic electrolytes such as sulfoalkylated polysulfone, sulfoalkylated polysulfide, and sulfoalkylated polyphenylene. Examples of commercially available materials include Nafion (registered trademark, manufactured by DuPont) and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.).

  Examples of the dispersion solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, and diethylene glycol, acetone, methyl ethyl ketone, dimethylformamide, dimethylimidazolidinone, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone. , Propylene carbonate, esters such as ethyl acetate and butyl acetate, and various aromatic or halogen solvents, and these can be used alone or as a mixed solution.

  Furthermore, regarding a conductive carrier carrying a catalyst, examples of the conductive carrier include carbon materials such as carbon black, carbon nanotubes, and carbon nanofibers, and carbon compounds typified by silicon carbide. As this catalyst (metal catalyst), for example, any one of platinum, platinum alloy, palladium, rhodium, gold, silver, osmium, iridium, etc. can be used, preferably platinum or platinum alloy is used. It is good to do. Furthermore, as this platinum alloy, for example, platinum, aluminum, chromium, manganese, iron, cobalt, nickel, gallium, zirconium, molybdenum, ruthenium, rhodium, palladium, vanadium, tungsten, rhenium, osmium, iridium, titanium and lead An alloy with at least one of them can be mentioned.

  The gas diffusion layers 2 and 3 are each composed of a diffusion layer base material and a current collecting layer (MPL). The diffusion layer base material is not particularly limited as long as it has a low electrical resistance and can collect current. For example, those mainly composed of conductive inorganic substances can be mentioned. Examples of the conductive inorganic substances include calcined bodies from polyacrylonitrile, calcined bodies from pitch, graphite and expanded graphite. Examples thereof include carbon materials, nanocarbon materials thereof, stainless steel, molybdenum, and titanium.

  Further, the form of the conductive inorganic substance of the diffusion layer base material is not particularly limited. For example, the conductive inorganic substance is used in the form of fibers or particles, but is an inorganic conductive fiber from the viewpoint of gas permeability, and particularly carbon fiber. Is preferred. As the diffusion layer substrate using inorganic conductive fibers, a woven fabric or non-woven fabric structure can be used, and examples thereof include carbon paper and carbon cloth. The woven fabric is not particularly limited, such as plain weave and crest weave, and examples of the nonwoven fabric include those made by a papermaking method and a water jet punch method.

  Further, examples of the carbon fiber include phenol-based carbon fiber, pitch-based carbon fiber, polyacrylonitrile (PAN) -based carbon fiber, and rayon-based carbon fiber. Furthermore, the current collecting layer plays the role of an electrode that collects electrons from the catalyst layer on the anode side and the cathode side, and also has a water repellency action. It can be formed from gold, silver, copper and their compounds or alloys, conductive carbon materials, and the like.

  Although not shown, in the exposed area where the electrolyte membrane is not in close contact with the catalyst layer at the periphery of the catalyst layer, fuzz protruding from the gas diffusion layer is prevented from sticking into the electrolyte membrane, Furthermore, the protective polymer film which has the effect which reinforces an electrolyte membrane with respect to the gasket by which injection molding is carried out is adhere | attached. This protective polymer film is made of polytetrafluoroethylene, PVDF (polyvinyl difluoride), polyethylene, polyethylene naphthalate (PEN), polycarbonate, polyphenylene ether (PPE), polypropylene, polyester, polyamide, copolyamide, polyamide elastomer, polyimide, It is formed from polyurethane, polyurethane elastomer, silicone, silicon rubber, silicon-based elastomer or the like.

  Further, the porous metal bodies 5 and 6 which are gas flow path layers can be formed from expanded metal or metal foam sintered body, for example, foam sintering of metal materials having excellent corrosion resistance such as titanium, stainless steel, copper and nickel. A porous metal body made of a body forms a gas flow path layer.

  In the illustrated module 100, for example, a number of constituent fuel cells 10,... Are accommodated in a mold (not shown), and a resin 8 is injected into the cavity in that posture to form a gasket 8. The module 100 is integrally formed by bonding to the separators 7 and 7.

  The gasket 8 is formed of a resin material such as butyl rubber, urethane rubber, silicone RTV rubber, methanol-resistant epoxy resin, epoxy-modified silicone resin, silicone resin, fluorine resin, or hydrocarbon resin.

  In the illustrated example, an endless rib 8a for sealing that surrounds the manifold M is provided at the upper end of the gasket 8, and when the modules 100 are stacked and stacked, the rib 8a can be crushed to form a sealing structure. It has become.

  FIG. 1 is a cross section taken through a fuel gas supply manifold M and an exhaust manifold M, for example, and each fuel cell 10 constituting the module 100 is fluid in the stacking direction in a stacking posture. A communicating manifold M is formed. FIG. 1 shows a structure in which the fuel gas supplied from the manifold M is provided to the anode-side porous body 6 via the gas flow path 7a in the separator 7 having a three-layer structure. Therefore, in another cross section, a manifold for providing the oxidizing gas to the porous body 5 on the cathode side is formed.

  The separator 7 having a three-layer structure is formed by interposing an intermediate layer 73 in which a cooling water passage is formed of a metal material between metal plates 71 and 72 made of stainless steel or titanium. It is also possible to adopt a form in which a frame material made of a resin material is used as an intermediate layer, and a large number of dimples or ribs for channel definition protrude from one of the two metal plates.

  For example, when the module 100 shown in FIG. 1 is composed of 20 fuel cells 10,... And the fuel cell stack is composed of 300 fuel cells 10,. A fuel cell stack is formed by stacking 15 illustrated modules 100 and stacking them.

  As is apparent from the figure, for example, in injection molding, most of the electrolyte membranes of the fuel cells 10,... Constituting the module 100 are made in contact with an external dissimilar material because a plurality of cells are laminated. Therefore, it is possible to prevent volatile gases and the like from being contaminated particularly during injection molding, and further prevent contamination of foreign materials and the like floating during the process of stacking cells.

  2 and 3 are enlarged views of the II region of FIG. 1, and schematically show the bonding interface between the gasket 8 and the separator 7.

  First, at the joining interface shown in FIG. 2, in any fuel cell 10, either the surface of the gasket 8 that comes into contact with another adjacent fuel cell 10 or the surface of the separator 7 of the separate fuel cell 10. On the other hand, in addition to the bonding area S where both are bonded, the non-bonding area HS where both are not bonded is provided.

  For example, a sheet HS made of perfluorosulfonic acid or Teflon (registered trademark) having non-adhesiveness with rubber or the like is adhered to the surface of the separator 7 prior to gasket molding, or these Since the separator 7 is coated on the surface of the separator 7 to form the coating layer HS, when the gasket 8 is formed by injection molding, the sheet HS or the coating layer HS is a non-adhesive layer at the interface. HS.

  Since a non-adhesive region HS is formed in a desired range at a desired portion of the adhesive interface between the gasket 8 and the separator 7, stress at the time of demolding after injection molding is applied to the entire contact interface between the gasket 8 and the separator 7 shown in the figure. Even when the tensile force is generated by the release, the deformation followability of the gasket 8 in the vicinity of the interface is reduced by the amount of the bonded region of the gasket 8 as compared with the case where the entire surface of the entire contact interface is bonded. improves.

  The contrast of this action will be described with reference to FIGS. 3a and 3b. FIG. 3a is a schematic diagram for explaining a deformation mode of a gasket having a conventional structure when a tensile force is applied by releasing stress at the time of demolding after extrusion, and FIG. 3b shows a fuel cell of the present invention. It is the schematic diagram explaining the deformation | transformation aspect of the gasket to comprise.

  In the separator of the fuel cell having the conventional structure shown in FIG. 3a, since the entire surface of the contact interface between the separator e and the gasket f is adhered, when the tensile force P is applied at the time of stress release, the separator between the separator e and the gasket f is used. The deformation performance of the gasket f in the vicinity of the interface could not be sufficiently expected. For this reason, a drum-shaped deformation mode bulging excessively in the center as shown in FIG. 5 occurred. For this reason, there is a risk that peeling occurs in the illustrated adhesive region S, which develops into the interface, or develops a crack in the gasket itself.

  On the other hand, in the fuel cell of the present invention shown in FIG. 3b, the non-adhesion region HS is provided on the surface of the separator 7, and the deformation performance near the interface of the gasket 8 is improved by reducing the range of the adhesion region S. It is easy to understand. Accordingly, when the tensile force P is applied in the same manner as described above, the bonded region S of the gasket 8 is deformed (deformation amount: δ), and the air gap G is formed between the gasket 8 and the non-bonded region HS during the deformation. Is formed. Then, the gasket 8 is deformed as shown in the figure, so that the joining interfaces of the separators, gaskets, electrode bodies, etc. of the respective fuel cells, which are module constituent members, can be maintained substantially flat. The deformation mode is effectively eliminated.

  However, only the adhesive region S whose range is reduced by the non-adhesive region HS has an adhesive force that can resist the acting tensile force P, that is, the adhesive posture between the separator 7 and the gasket 8 is maintained. It goes without saying that you need to do it.

  On the other hand, the joining interface of the form shown in FIG. 3 has an adhesive region S where the separator 7 and the gasket 8 are bonded to both surfaces of the upper and lower separators 7 and 7 where the gasket 8 constituting the arbitrary fuel cell 10 contacts. In addition, there is a non-bonding region HS in which both are not bonded.

  That is, in this embodiment, since the non-adhesive regions HS exist on the upper and lower surfaces of the gasket 8, an interface structure between the gas flow path and the separator 7 having higher deformation followability is formed. A fuel cell system that is actually mounted on an electric vehicle or the like includes a fuel cell 100 (fuel cell stack) shown in the figure, various tanks that contain hydrogen gas and air, a blower and fuel for providing these gases to the fuel cell. It is mainly composed of a radiator for cooling the battery, a battery for storing electric power generated by the fuel cell, a drive motor driven by this electric power, and the like.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Membrane electrode assembly, 2 ... (Cathode side) Gas diffusion layer (gas permeable layer), 3 ... (Anode side) Gas diffusion layer (gas permeable layer), 4 ... Electrode body, 5 ... (Cathode side) Metal porous (Gas permeable layer), 6 ... (anode side) porous metal body (gas permeable layer), 7 ... separator, 71, 72 ... metal plate, 73 ... intermediate layer for channel formation, 7a ... gas channel, 8 ... Gasket, 8a ... Endless rib for sealing, 10 ... Fuel cell, 100 ... Module, M ... Manifold, S ... Adhesion area, HS ... Non-adhesion area (sheet, coating layer)

Claims (5)

A plurality of fuel cell units each including a membrane electrode assembly, a gas permeable layer disposed on both sides of the membrane electrode assembly, and a separator disposed on at least one of the gas permeable layers are stacked, and the stacked membrane electrodes A gasket integrally formed on the periphery of the joined body and the gas permeable layer is formed to form one module composed of a plurality of fuel cells, and a plurality of the modules are stacked, or a fuel cell is formed from only one of the modules. A fuel cell in which a stack is formed,
A fuel cell, wherein a surface of the separator that contacts the gasket is provided with an adhesion region that adheres to the gasket and a non-adhesion region that does not adhere to the gasket.   2. The fuel cell according to claim 1, wherein the non-adhesion region is provided only on a surface of a separator that comes into contact with a gasket of a separate fuel cell adjacent to the fuel cell in a stacked posture.   The non-adhesion region is a surface of the fuel cell in which the separator constituting the fuel cell contacts the gasket, and a surface of the separator that contacts the gasket of another fuel cell adjacent in the stacking posture. The fuel cell according to claim 1, which is provided on both sides.   The fuel cell according to any one of claims 1 to 3, wherein the non-adhesive region is made of any one of a non-adhesive sheet and a non-adhesive coating layer having non-adhesiveness with the gasket.   The fuel cell according to any one of claims 1 to 3, wherein the gas permeable layer is composed of any one of a gas diffusion layer, a gas flow path layer made of a metal porous body, or a laminate thereof.

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