JP2016131085A - Fuel cell and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance fuel cell capable of preventing fuel gas and oxidizing gas from leaking through a gap by sealing the same.SOLUTION: The fuel cell includes: frame bodies 9a and 9b which are formed around a sticking out part of electrode layers 3a and 3b of a solid state high molecular electrolyte film 2. The frame bodies 9a and 9b are formed of a resin, which includes isolative fiber sheet filling the gaps between the fiber sheet and a separator while covering the outer periphery end part of the fiber sheet. With this, the fuel cell, which has the frame bodies 9a and 9b having a function of sealing to prevent leakage along the sheet, is achieved in a simple manner.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a solid polymer electrolyte type fuel cell and a method for producing the same.

  A solid polymer electrolyte fuel cell (hereinafter sometimes referred to as “PEFC”) uses a fuel gas containing hydrogen and an oxidant gas containing oxygen, such as air, to cause an electrochemical reaction. And a device that generates heat at the same time.

  Basic components of the PEFC include a polymer electrolyte membrane that selectively transports hydrogen ions, and an anode electrode and a cathode electrode formed on both surfaces of the polymer electrolyte membrane. These electrodes have a catalyst layer formed on the surface of the polymer electrolyte membrane, and a gas diffusion layer (GDL) that is disposed outside the catalyst layer and has both air permeability and electronic conductivity.

  The assembly in which the polymer electrolyte membrane and the electrode are integrally joined in this way is called an electrolyte membrane-electrode assembly (MEA).

  On both sides of the MEA, conductive separators are disposed for mechanically sandwiching and fixing the MEAs and electrically connecting adjacent MEAs in series. At the contact portion between the separator and the MEA, a gas flow path is formed for supplying a reaction gas to each electrode and carrying away generated water and surplus gas. A structure in which the MEA is sandwiched between the pair of separators is referred to as a fuel cell.

  The solid polymer electrolyte membrane is formed in a thin film in order to suppress a voltage drop due to its resistance. A solid polymer electrolyte membrane, which is a thin film, has almost no force to retain its shape, so it is easily deformed under the influence of temperature and humidity, and its handleability is poor.

  In the prior art that has addressed the problem, a reinforcing material is applied to the protruding portion of the solid polymer electrolyte membrane that protrudes from the outer peripheral edge of the gas diffusion layer to provide a frame, and the solid polymer electrolyte membrane is deformed. Some of them have a shape-retaining force to prevent, and further use a fluorine-based rubber or silicon-based rubber as a reinforcing material to provide a function as a seal that prevents gas leakage (see, for example, Patent Document 1).

  9a to 9c show a conventional MEA disclosed in Patent Document 1. FIG. 9a is a perspective view showing the solid polymer electrolyte membrane 20 in which the reinforcing portion 23 having a frame shape is formed, FIG. 9b is a sectional view taken along line 2B-2B of FIG. 9a, and FIG. It is sectional drawing of the fuel battery cell using a molecular electrolyte membrane.

  A fuel cell is used in the form of a fuel cell stack in which a large number of single cells 10 are stacked, for example, as a driving source for an automobile.

  The single cell 10 is a battery that can obtain electricity in the process of obtaining water by reacting hydrogen and oxygen by utilizing the reverse principle of electrolysis of water. The single cell 10 includes a solid polymer electrolyte membrane 20 as a cation exchange membrane, a pair of gas diffusion layers 31 and 32 functioning as electrodes, and a pair of separators 41 and 42.

The single cell 10 is configured such that the solid polymer electrolyte membrane 20 is sandwiched between a pair of gas diffusion layers 31 and 32 and the outside thereof is sandwiched between a pair of separators 41 and 42. The separator 41 on the gas diffusion layer 31 side is formed with a channel groove 43 for circulating cooling water and a channel groove 44 for circulating fuel gas (hydrogen).

  The separator 42 on the gas diffusion layer 32 side is formed with a channel groove 45 for circulating cooling water and a channel groove 46 for circulating oxidant gas (air). The shape and arrangement of the channel grooves 43 to 46 need to consider gas diffusibility, pressure loss, discharge of generated water, cooling performance, and the like, and have a fine and complicated configuration.

  The solid polymer electrolyte membrane 20 is a polymer membrane having a function of moving hydrogen ions. The solid polymer electrolyte membrane 20 is formed in a thin film (for example, about several tens of μm to 100 μm) in order to suppress a voltage drop due to its resistance.

  The formed solid polymer electrolyte membrane 20 is usually stored or stored in a state of being wound around a core material in a roll shape, and is used while being fed out sequentially when manufacturing a fuel cell.

  The solid polymer electrolyte membrane 20 includes a main body portion 21 that forms a region interposed between a pair of gas diffusion layers 31 and 32, a protruding portion 22 that protrudes from the outer peripheral edge of the gas diffusion layers 31 and 32, and a protruding portion. 22 and a reinforcing portion 23 having a frame shape formed by applying a reinforcing material so as to surround the outer peripheral edge portions of the gas diffusion layers 31 and 32.

  The reinforcing portion 23 is formed on both surfaces (upper surface and lower surface in FIG. 9b) of the protruding portion 22, and has a rectangular cross section. When assembling the unit cell 10, the main body 21 is sandwiched between the pair of gas diffusion layers 31 and 32, and the reinforcing portion 23 protrudes from the gas diffusion layers 31 and 32 and is disposed between the pair of separators 41 and 42. (See FIG. 9c). Note that the reinforcing portion 23 has a sealing function.

  Further, the reinforcing portion 23 gives the main body portion 21 a shape retention force that prevents the main body portion 21 from being rounded. That is, while the solid polymer electrolyte membrane 20 is stored in a state of being wound in a roll shape, the main body portion 21 has a curl. Further, since the solid polymer electrolyte membrane 20 has almost no force to maintain its shape, it is easily deformed under the influence of temperature and humidity.

  On the other hand, since the reinforcing portion 23 has a frame shape, the reinforcing portion 23 can withstand the force of curling the main body portion 21 due to the curl and the deformation force due to the influence of temperature and humidity. The force for holding a flat shape, that is, the shape holding force is strong. And as a result of the reinforcement part 23 providing shape retention power to the main-body part 21, it is prevented that the main-body part 21 curls or deform | transforms.

  The reinforcing part 23 having a frame shape is formed by applying a reinforcing material to the protruding part 22. Here, as a reinforcing material, an appropriate material can be selected as long as the reinforcing portion 23 can impart a shape retention force to the main body portion 21. As the reinforcing material, silicon rubber (Shore hardness of 25 or more) and fluorine rubber can be preferably used. A two-component curing type curing agent having quick drying properties can also be used.

JP-A-2005-243292

However, in the above-described conventional configuration, it is difficult to form the reinforcing member on the solid polymer electrolyte membrane with high accuracy, and a large tolerance must be taken. As a result, a gap is formed in a portion surrounded by the outer periphery of the GDL, the separator, the seal, and the solid polymer electrolyte membrane, and fuel gas and oxidant gas leak into the gap during fuel cell operation. The agent gas is discharged outside with little exposure to the MEA.

  As a result, there has been a problem that the utilization efficiency of the fuel gas and the oxidant gas is lowered, and the efficiency (power generation efficiency) of the PEFC is lowered. In addition, fluorine rubber and silicon rubber as a sealing material are expensive, and there is a problem that the cost of the fuel cell increases if it is formed on all the protruding portions of the solid polymer electrolyte membrane so as to serve as a frame. It was.

  The present invention solves the above-described conventional problems, and provides a fuel cell that can be produced at low cost by closing a gap with a simple structure and simplifying not only the material cost but also the manufacturing process. Objective.

  In order to solve the above conventional problems, a fuel cell of the present invention includes a polymer electrolyte membrane, a membrane electrode assembly having a pair of electrode layers sandwiching the polymer electrolyte membrane, and a pair of membrane electrode assemblies. A fuel cell comprising a cell having a plate-like separator and an annular frame provided on a peripheral edge of the polymer electrolyte membrane, the frame being sandwiched between the peripheral edges of the membrane electrode assembly Insulating fiber sheet disposed on both sides of the membrane electrode assembly so as to sandwich, and a resin containing the fiber sheet, the resin fills the gap between the fiber sheet and the separator, It has the structure that it is formed so that the outer peripheral edge part of the said fiber sheet may be covered.

  With this configuration, the fiber sheet and the separator, the solid polymer electrolyte membrane, and the electrode are filled with resin, so that leakage of gas to the outside is suppressed, and the fiber sheet-containing resin and separator, solid polymer It is possible to prevent gas wrap-around that gas passes through the gap between the electrolyte membrane and the electrode and is discharged to the gas outlet.

  In addition, as a degradation mode of resin with fiber sheet, there is a mechanism in which water vapor enters from the interface between the resin and the fiber sheet, and thus hydrolysis proceeds and deterioration is accelerated. In this configuration, the fiber sheet is covered with resin. Therefore, this deterioration can be suppressed. Furthermore, since the fiber sheet is encapsulated in the resin, the volume and height of the frame can be secured, and the material cost of the resin can be suppressed.

  The fuel cell manufacturing method of the present invention includes a polymer electrolyte membrane, a membrane electrode assembly having a pair of electrode layers sandwiching the polymer electrolyte membrane, and a pair of plate separators sandwiching the membrane electrode assembly, A fuel cell including a cell having an annular frame provided on a peripheral edge of the polymer electrolyte membrane, wherein a pair of frame pieces having an insulating fiber sheet in a resin And a step of arranging the pair of plate-shaped separators so as to sandwich the membrane electrode assembly and the pair of frame pieces. And a pressurizing step of pressing what is to be the cell in the thickness direction of the polymer electrolyte membrane and extruding a part of the softened resin to the outer peripheral side of the cell.

  According to the method for producing a fuel cell of the present invention, since the softened resin can be sealed by entering the gaps between the members, leakage of reaction gas to the outside, resin and separator with fiber sheet, solid polymer electrolyte The gas can pass through the gap between the membrane and the electrode and can be prevented from flowing out to the gas outlet, and since the outer end of the fiber sheet is covered with resin, Since it is possible to prevent water vapor from entering the interface, deterioration of the fiber-containing resin sheet can be suppressed.

  According to the present invention, it is possible to obtain a high-performance fuel cell that closes the gap with a simple structure and does not leak. In addition to the reduction in material cost, a fuel cell that can be produced at low cost can be provided by a manufacturing process with a small number of steps.

Sectional drawing of the fuel cell before pressurization in Embodiment 1 of this invention Sectional drawing of the fuel cell after pressure hardening in Embodiment 1 of this invention Sectional drawing of the fuel cell before pressurization in Embodiment 2 of this invention Sectional drawing of the fuel cell after pressure hardening in Embodiment 2 of this invention Sectional drawing of the fuel cell before pressurization in Embodiment 3 of this invention Sectional drawing of the fuel cell after pressure-curing in Embodiment 3 of this invention Sectional drawing of the fuel cell before pressurization in Embodiment 4 of this invention Sectional drawing of the fuel cell after pressure hardening in Embodiment 4 of this invention A perspective view of a conventional solid polymer electrolyte membrane with a frame Sectional view of a conventional solid polymer electrolyte membrane with a frame Cross section of conventional fuel cell

  The fuel cell of the first invention includes a polymer electrolyte membrane, a membrane electrode assembly having a pair of electrode layers sandwiching the polymer electrolyte membrane, a pair of plate separators sandwiching the membrane electrode assembly, A fuel cell including a cell having an annular frame provided at a peripheral portion of a molecular electrolyte membrane, wherein the frame body sandwiches the peripheral portion of the membrane electrode assembly. Insulating fiber sheets disposed on both sides of the fiber sheet and a resin containing the fiber sheet, the resin filling a gap between the fiber sheet and the separator, and forming an outer peripheral end of the fiber sheet. It is formed so as to cover it.

  With this configuration, the gap between the fiber sheet and the separator, the solid polymer electrolyte membrane, and the electrode is filled with resin, so that leakage of gas leak to the outside is suppressed, and the fiber sheet-containing resin and separator, solid polymer electrolyte It is possible to prevent wraparound that is discharged to the gas outlet through the gap between the membrane and the electrode.

  In addition, as a degradation mode of resin with fiber sheet, there is a mechanism in which water vapor enters from the interface between the resin and the fiber sheet, and thus hydrolysis proceeds and deterioration is accelerated. In this configuration, the fiber sheet is covered with resin. Therefore, this deterioration can be suppressed. Moreover, since the fiber sheet is included in the resin, the volume as a frame can be gained, and the resin cost can be suppressed.

  In the second invention, in the fuel cell of the first invention, at least one convex portion formed on the separator is in contact with the fiber sheet.

  With this configuration, this convex part can be caught on the fiber sheet and fixed to the separator, so that the MEA and the fiber sheet-containing resin are sandwiched between the separators and compressed from above the separator to heat the resin to flow. However, the fiber sheet does not move, only the resin flows and the outer peripheral edge of the fiber sheet can be covered, and deterioration from the interface between the resin and the fiber sheet can be suppressed.

  According to a third invention, the resin in the fuel cell of the first invention or the second invention protrudes outside the outer peripheral surface of the separator.

  Since this structure can also prevent water vapor from entering from the interface between the separator and the resin, it is possible to more reliably suppress deterioration from the interface between the resin and the fiber sheet.

  According to a fourth invention, there is a portion in which the frame body in the fuel cell according to any one of the first to third inventions becomes thinner toward the inner periphery.

  With this configuration, since there is much resin near the outer periphery, the outer peripheral end of the fiber sheet can be reliably covered, and deterioration from the interface between the resin and the fiber sheet can be suppressed.

  According to a fifth aspect of the present invention, in the fuel cell according to any one of the first to third aspects, the average thickness of the inner peripheral portion is thinner than the average thickness of the outer peripheral portion. is there.

  With this configuration, since the resin near the outer periphery is larger than that near the inner periphery, the outer peripheral end of the fiber sheet can be reliably covered, and deterioration from the interface between the resin and the fiber sheet can be suppressed.

  According to a sixth aspect of the present invention, in the fuel cell according to any one of the first to third aspects, the portion between the innermost peripheral portion and the outermost peripheral portion is the thinnest.

  With this configuration, since the amount of resin is large not only in the outermost peripheral part but also in the innermost peripheral part, the end of the fiber sheet can be reliably covered with the resin, and deterioration from the interface between the resin and the fiber sheet is suppressed. be able to.

  According to a seventh invention, the fiber sheet in the fuel cell according to any one of the first to sixth inventions is a woven fabric or a non-woven fabric.

  This configuration facilitates handling of the fiber-containing resin sheet.

  According to an eighth aspect of the invention, in the fuel cell according to any one of the first to seventh aspects, the fibers of the fiber sheet are inorganic fibers, and the ninth aspect is the fuel cell according to the eighth aspect. The inorganic fiber in is a glass fiber.

  With this configuration, it is possible to reliably prevent the opposing separators from contacting each other and cause an electrical short, and the strength can be maintained without being softened even in a temperature environment where the resin is softened.

  According to a tenth aspect, the resin in the fuel cell according to any one of the first to ninth aspects includes a thermosetting resin.

  With this configuration, the resin can be cured in an optimal configuration state in which the resin melts to fill a gap or cover the outer peripheral portion, so that an optimal seal structure can be maintained.

  An eleventh invention includes a polymer electrolyte membrane, a membrane electrode assembly having a pair of electrode layers sandwiching the polymer electrolyte membrane, a pair of plate separators sandwiching the membrane electrode assembly, and the polymer electrolyte membrane And a pair of frame pieces each having an insulating fiber sheet in a resin, the pair of frame pieces being the film. The step of arranging the electrode assembly so as to sandwich the peripheral edge portion, the step of arranging the pair of plate-like separators so as to sandwich the membrane electrode assembly and the pair of frame pieces, and the cell. And pressurizing in the thickness direction of the polymer electrolyte membrane, and pressing a part of the softened resin to the outer peripheral side of the cell.

According to this manufacturing method, since the softened resin can be sealed by entering the gaps between the members, it is possible to prevent the reaction gas from leaking to the outside and the reaction gas from flowing around, and the outer end of the fiber sheet. Since the portion is covered with the resin, it is possible to prevent water vapor from entering from the outside air to the interface between the resin and the fiber, so that deterioration of the fiber-containing resin sheet can be suppressed.

  In a twelfth aspect of the invention, the separator according to the eleventh aspect includes a convex portion on a surface of the separator facing the frame piece, and the pressing step according to the eleventh aspect includes the convex portion on the fiber sheet. This is a step of pushing out a part of the softened resin to the outer peripheral side of the cell while abutting and restricting the fiber sheet from moving to the outer peripheral side.

  According to this manufacturing method, the resin moves to the outer peripheral side by softening and pressurizing the resin. However, since the fiber sheet is caught by the convex portion and fixed and does not move, only the resin moves to the outer peripheral side and surely moves. The end of the fiber sheet can be covered with resin.

  The thirteenth invention has a curing step of curing the resin in a pressurized state after the pressing step in the eleventh or twelfth invention. In the curing step, for example, thermosetting The resin containing the functional resin is heated to a temperature at which the resin is cured to cure the resin.

  According to this manufacturing method, since the resin can be cured in an optimal configuration state in which the resin is melted to fill a gap or cover the outer peripheral portion, an optimal seal structure can be maintained.

  In a fourteenth invention, the curing step according to the thirteenth invention is a softened state in which a plurality of the cells that become the cells are stacked in the thickness direction of the polymer electrolyte membrane and a predetermined load is applied in the stacking direction. After extruding a part of the resin to the outer peripheral side of the cell, the resin is cured.

  According to this manufacturing method, since the pressurization process and the curing process of a plurality of cells can proceed simultaneously, the manufacturing time can be shortened.

  In a fifteenth aspect, the curing step in the thirteenth aspect or the fourteenth aspect is performed by heating the resin including a thermosetting resin to a temperature at which the resin is cured to cure the resin.

  According to the present manufacturing method, the resin can be cured only by applying heat, so that no special device or material is required, and the curing process can be performed in a simple process.

  In a sixteenth aspect, the pressing step in any one of the eleventh to fifteenth aspects includes a step of heating the resin so that the resin is in a softened state.

  According to this manufacturing method, since the resin sheet containing hard fibers can be used at room temperature until the separator and MEA are set, the sheet is easy to handle.

  According to a seventeenth aspect, in the frame piece before the pressurizing step in any one of the eleventh to sixteenth aspects, the outer peripheral end of the fiber sheet is not covered with a resin.

  Even with this manufacturing method, the outer peripheral edge can be covered with the resin by softening the resin and pressurizing and flowing the resin, so that the fiber end does not protrude from the resin and deteriorates from the interface between the resin and the fiber. Can be prevented from accelerating.

In an eighteenth aspect of the invention, in the frame piece before the pressurizing step according to any of the eleventh aspect to the seventeenth aspect of the invention, an outer peripheral end of the fiber sheet is covered with a resin.

  By this manufacturing method, the fibers are more reliably covered with the resin, so that the acceleration of deterioration from the interface between the resin and the fibers can be suppressed, and the resin in the gaps between the respective members by pressurizing the softened resin. Thus, a fuel cell free from leaks can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a fuel cell before pressurization according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view of the fuel cell after pressure cure according to Embodiment 1 of the present invention.

  As shown in FIG. 2, the fuel cell 100 according to Embodiment 1 includes an electrode-membrane assembly (hereinafter referred to as MEA) 1 that is a pair of conductive separators and a surface on which the cooling water channel 12 is formed. An anode-side separator 7a on which the fuel gas flow path is formed on the opposite surface, and a cathode-side separator 7b on which the oxidant gas flow path is formed on the surface opposite to the surface on which the cooling water flow path 12 is formed. It is configured integrally with the shape sandwiched between.

  More specifically, in the electrode layer composed of the catalyst layers 4a and 4b and the gas diffusion layers 5a and 5b, the gas diffusion layers 5a and 5b of the MEA 1 are in contact with the surfaces of the anode-side separator 7a and the cathode-side separator 7b. In contact with each other, the anode-side reaction gas flow path 11a of the anode-side separator 7a, the cathode-side reaction gas flow path 11b of the cathode-side separator 7b, and the gas diffusion layers 5a and 5b of the MEA 1 respectively. Is confirmed.

  As a result, the fuel gas contacts the gas diffusion layer 5a on the anode-side separator 7a side, and the oxidant gas contacts the gas diffusion layer 5b on the cathode-side separator 7b side to cause an electrochemical reaction.

  The anode-side separator 7a, the cathode-side separator 7b, and the peripheral edges of the MEA 1 are bonded and integrally joined by frame bodies 9a and 9b made of a resin containing an insulating fiber sheet at least partially. . Furthermore, the end part of the insulating reinforcing fiber is wrapped in resin, and the fiber end part has a structure that does not come into contact with the outside air.

  A method for producing the fuel cell will be described with reference to FIG. First, portions of the anode-side separator 7a and the cathode-side separator 7b that are not in direct contact with the electrodes of the MEA 1 on the side facing the MEA 1 are molded so that the average thickness of the separator 7a decreases toward the outer periphery. This molding may be performed when the separators (the anode-side separator 7a and the cathode-side separator 7b) are formed, or may be shaved later.

  Next, a resin containing an insulating fiber sheet, for example, a prepreg sheet in which a glass fiber is impregnated with an epoxy resin is cut into a shape that can be arranged around the electrode, and the frame piece (the anode side frame piece 8a, the cathode side). Frame piece 8b) and arranged around the electrode layers 3a and 3b of MEA1 and at positions on the anode side and cathode side of the solid polymer electrolyte membrane 2, and MEA1 and the frame piece (anode side frame piece 8a, The cathode-side frame piece 8b) is sandwiched between a pair of separators (anode-side separator 7a, cathode-side separator 7b).

This fuel cell is set in a pressurizing device with a heater or a pressurizing device in a thermostatic bath, and the temperature is raised to a temperature at which the resin softens. When the resin is softened, the pressure at which the fuel cell can exert its power generation performance, that is, the electrode layers 3a and 3b can contact the ribs between the flow paths of the separators (the anode side separator 7a and the cathode side separator 7b) without any gap. A predetermined time is applied by applying a predetermined pressure.

  During this time, the resin of the frame pieces (the anode-side frame piece 8a and the cathode-side frame piece 8b) flows to fill various gaps with the members in contact with the frame pieces. For example, there are a gap between the separator and the frame piece, and a gap between the frame piece and the solid polymer electrolyte membrane. This prevents gas from leaking outside. Further, the resin at the innermost peripheral portion flows also into the gaps (the gap 16a on the anode side and the gap 16b on the cathode side) between the frame piece, the electrode, the separator, and the solid polymer electrolyte membrane, and the gap (the gap 16a on the anode side). The gap 16b) on the cathode side can be filled with resin. As a result, the gap around which the gas flows is closed, so that it is possible to obtain a fuel cell with little reduction in the gas utilization rate.

  Further, in the portion where the thickness of the separator becomes thinner toward the outer periphery, the volume in which the resin can flow is increased toward the outer periphery, so that the resin flows toward the outer periphery. The fluidized resin may protrude slightly from the outer end face of the separator.

  Next, after the resin has sufficiently flowed, the set temperature is changed to a temperature at which the resin is cured while a predetermined pressure is applied, and a predetermined time is set. This curing temperature may be the same as or higher than the softening temperature of the resin. By this step, the inside of the fuel cell can be held in the best condition, and the assembly of the fuel cell is completed.

  Thus, according to the fuel cell of the first embodiment, the resin sheet containing reinforcing fibers plays the role of a frame and a seal, so there is no need to use a large amount of expensive seals, and the resin flows into the gaps. Therefore, the gaps and tolerances during assembly can be greatly eliminated, and fuel cells can be created in a simple process.

(Embodiment 2)
FIG. 3 is a cross-sectional view of the fuel cell before pressurization according to Embodiment 2 of the present invention, and FIG. 4 is a cross-sectional view of the fuel cell after pressurization curing according to Embodiment 2 of the present invention. The same reference numerals are used for the same components as those in the first embodiment shown in FIGS.

  Compared with the fuel cell of Embodiment 1, the fuel cell of Embodiment 2 has a configuration that more reliably prevents gas wraparound.

  As shown in FIG. 4, the fuel cell 100 of the second embodiment includes an electrode-membrane assembly (hereinafter referred to as MEA) 1 that is a pair of conductive separators and an anode-side separator 7a that forms a fuel gas path. Are integrally formed with a shape sandwiched between cathode-side separators 7b forming an oxidant gas path.

  More specifically, in the electrode layers 3a and 3b, the gas diffusion layers 5a and 5b of the MEA 1 are in contact with the surfaces of the anode-side separator 7a and the cathode-side separator 7b, and the reaction on the anode side of the anode-side separator 7a. Each gas flow path is determined by the gas flow path 11a, the reaction gas flow path 11b on the cathode side of the separator 7b on the cathode side, and the gas diffusion layers 5a and 5b of the MEA 1.

  As a result, the fuel gas contacts the gas diffusion layer 5a on the anode-side separator 7a side, and the oxidant gas contacts the gas diffusion layer 5b on the cathode-side separator 7b side to cause an electrochemical reaction.

The anode-side separator 7a, the cathode-side separator 7b, and the peripheral edges of the MEA 1 are bonded and integrally joined by frame bodies 9a and 9b made of a resin containing an insulating fiber sheet at least partially. . Furthermore, the end part of the insulating reinforcing fiber is wrapped in resin, and the fiber end part has a structure that does not come into contact with the outside air.

  A method for producing the fuel cell will be described with reference to FIG. First, the thickness of the separator is the thickest between the innermost peripheral portion and the outermost peripheral portion of the anode-side separator 7a and the cathode-side separator 7b that are not in direct contact with the electrode of the MEA1 on the side facing the MEA1. It forms so that the average thickness of the separator 7a may become thin, so that it goes to an inner periphery and an outer periphery. This molding may be performed at the time of producing the separator or may be shaved later.

  Next, a resin containing an insulating fiber sheet, for example, a prepreg sheet in which a glass fiber is impregnated with an epoxy resin is cut into a shape that can be arranged around the electrode, and the frame piece (the anode side frame piece 8a, the cathode side). Frame piece 8b) and arranged around the electrode layers 3a and 3b of MEA1 and at positions on the anode side and cathode side of the solid polymer electrolyte membrane 2, and MEA1 and the frame piece (anode side frame piece 8a, The cathode-side frame piece 8b) is sandwiched between a pair of separators (anode-side separator 7a, cathode-side separator 7b).

  This fuel cell is set in a pressurizing device with a heater or a pressurizing device in a thermostatic bath, and the temperature is raised to a temperature at which the resin softens. When the resin is softened, the pressure at which the fuel cell can exert its power generation performance, that is, the electrode layers 3a and 3b can contact the ribs between the flow paths of the separators (the anode side separator 7a and the cathode side separator 7b) without any gap. A predetermined time is applied by applying a predetermined pressure.

  During this time, the resin of the frame pieces (the anode-side frame piece 8a and the cathode-side frame piece 8b) flows to fill various gaps with the members in contact with the frame pieces. For example, there are a gap between the separator and the frame piece, and a gap between the frame piece and the solid polymer electrolyte membrane. This prevents leakage of gas to the outside.

  Also, in the part where the thickness of the separator is thinner toward the inner periphery, the volume of the resin that can flow is increased toward the inner periphery. The gaps between the electrode, the separator, and the solid polymer electrolyte membrane (the anode side gap 16a and the cathode side gap 16b) can be more reliably filled with the resin.

  As a result, the gap around which the gas flows is closed, so that it is possible to obtain a fuel cell with little reduction in gas utilization. Further, in the portion where the thickness of the separator becomes thinner toward the outer periphery, the volume in which the resin can flow is increased toward the outer periphery, so that the resin flows toward the outer periphery. The fluidized resin may protrude slightly from the outer end face of the separator.

  Next, after the resin has sufficiently flowed, the set temperature is changed to a temperature at which the resin is cured while a predetermined pressure is applied, and a predetermined time is set. This curing temperature may be the same as or higher than the softening temperature of the resin. By this step, the inside of the fuel cell can be held in the best condition, and the assembly of the fuel cell is completed.

  Thus, according to the fuel cell of the second embodiment, the resin sheet containing reinforcing fibers plays the role of a frame and a seal, so there is no need to use a large amount of expensive seals, and the resin flows into the gaps. Therefore, the gaps and tolerances during assembly can be greatly eliminated, and fuel cells can be created in a simple process.

(Embodiment 3)
FIG. 5 is a cross-sectional view of the fuel cell before pressurization according to Embodiment 3 of the present invention, and FIG. 6 is a cross-sectional view of the fuel cell after pressurization curing according to Embodiment 3 of the present invention. The same components as those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.

  The fuel cell according to the third embodiment has a configuration in which the fiber sheet is more reliably included in the resin than the fuel cell according to the first embodiment.

  As shown in FIG. 6, the fuel cell 100 includes an electrode-membrane assembly (hereinafter referred to as MEA) 1 that is a pair of conductive separators, an anode-side separator 7a that forms a fuel gas path, and an oxidant gas. It is configured integrally with a shape sandwiched between cathode-side separators 7b forming a path.

  More specifically, in the electrode layers 3a and 3b, the gas diffusion layers 5a and 5b of the MEA 1 are in contact with the surfaces of the anode-side separator 7a and the cathode-side separator 7b, and the reaction on the anode side of the anode-side separator 7a. Each gas flow path is determined by the gas flow path 11a, the reaction gas flow path 11b on the cathode side of the separator 7b on the cathode side, and the gas diffusion layers 5a and 5b of the MEA 1.

  As a result, the fuel gas contacts the gas diffusion layer 5a on the anode-side separator 7a side, and the oxidant gas contacts the gas diffusion layer 5b on the cathode-side separator 7b side to cause an electrochemical reaction.

  The anode-side separator 7a, the cathode-side separator 7b, and the peripheral edges of the MEA 1 are bonded and integrally joined by frame bodies 9a and 9b made of a resin containing an insulating fiber sheet at least partially. . Furthermore, the end part of the insulating reinforcing fiber is wrapped in resin, and the fiber end part has a structure that does not come into contact with outside air.

  As the resin containing at least a part of the insulating reinforcing fiber, a prepreg obtained by impregnating glass fiber with an epoxy resin is preferable in terms of heat-resistant temperature, linear expansion coefficient, etc., and FR-4 generally known as a substrate material is used. Various physical properties can be selected at first, but insulating reinforcing fibers and resins are not limited thereto.

  For example, the reinforcing fiber may use other reinforcing fibers such as an aramid fiber depending on the strength, thickness, linear expansion coefficient, and contained material, and the resin may be other resin such as phenol resin, unsaturated polyurethane resin, polyurethane resin, etc. It may be a thermosetting resin or a thermoplastic resin, and may have a structure in which a resin containing reinforcing fibers and another resin are laminated in a multilayer structure or a partially different composition. Further, a resin containing a reinforcing fiber may be used in at least a part of a configuration different between the anode surface side and the cathode surface side.

  A method for producing the fuel cell will be described with reference to FIG. First of all, the average thickness of the separator 7a toward the outer periphery of the portions of the anode-side separator 7a and the cathode-side separator 7b that are not in direct contact with the MEA1 electrodes on the side facing the MEA1 is increased toward the outer periphery. Mold so that is thin. This molding may be performed at the time of producing the separator or may be shaved later.

Next, a resin containing an insulating fiber sheet, for example, a prepreg sheet in which a glass fiber is impregnated with an epoxy resin is cut into a shape that can be arranged around the electrode, and the frame piece (the anode side frame piece 8a, the cathode side). Frame piece 8b) and arranged around the electrode layers 3a and 3b of MEA1 and at positions on the anode side and cathode side of the solid polymer electrolyte membrane 2, and MEA1 and the frame piece (anode side frame piece 8a, The cathode-side frame piece 8b) is sandwiched between a pair of separators (anode-side separator 7a, cathode-side separator 7b).

  This fuel cell is set in a pressurizing device with a heater or a pressurizing device in a thermostatic bath, and the temperature is raised to a temperature at which the resin softens. When the resin is softened, the pressure at which the fuel cell can exert its power generation performance, that is, the electrode layers 3a and 3b can contact the ribs between the flow paths of the separators (the anode side separator 7a and the cathode side separator 7b) without any gap. A predetermined time is applied by applying a predetermined pressure.

  During this time, the resin of the frame pieces (the anode-side frame piece 8a and the cathode-side frame piece 8b) flows to fill various gaps with the members in contact with the frame pieces. For example, the gap between the unevenness of the separator and the frame piece, and the gap between the frame piece and the solid polymer electrolyte membrane. This prevents leakage of gas to the outside. In addition, the gaps between the frame piece, the electrode, the separator, and the solid polymer electrolyte membrane (the gap 16a on the anode side and the gap 16b on the cathode side) can be filled with the resin as the innermost resin flows. it can.

  As a result, the gap around which the gas flows is closed, so that it is possible to obtain a fuel cell with little reduction in gas utilization. Further, in the portion where the thickness of the separator becomes thinner toward the outer periphery, the volume in which the resin can flow is increased toward the outer periphery, so that the resin flows toward the outer periphery. The fluidized resin may protrude slightly from the outer end face of the separator.

  On the other hand, since the convex part formed in the separator surface bites into resin inside and the glass fiber which exists in resin inside is caught in a convex part, there exists an effect which suppresses that a glass fiber moves on the flow of resin.

  Here, the glass fiber may be a woven fabric or a non-woven fabric, but the woven fabric has a stronger force for fixing the entire woven fabric when caught by the convex portion. In addition, the woven fabric is less likely to pierce the membrane by the fibers extending in the direction perpendicular to the membrane. Thus, the edge part of the glass fiber which exists in resin inside can be reliably covered with resin, and the deterioration which arises from the interface of a fiber and resin can be prevented.

  Next, after the resin has sufficiently flowed, the set temperature is changed to a temperature at which the resin is cured while a predetermined pressure is applied, and a predetermined time is set. This curing temperature may be the same as or higher than the softening temperature of the resin. By this step, the inside of the fuel cell can be held in the best condition, and the assembly of the fuel cell is completed.

  Thus, according to the fuel cell of the third embodiment, the resin sheet containing reinforcing fibers plays a role of a frame and a seal, so there is no need to use a large amount of expensive seals, and the resin flows into the gaps. Therefore, the gaps and tolerances during assembly can be greatly eliminated, and fuel cells can be created in a simple process.

(Embodiment 4)
FIG. 7 is a cross-sectional view of the fuel cell before pressurization according to Embodiment 4 of the present invention, and FIG. 8 is a cross-sectional view of the fuel cell after pressurization curing according to Embodiment 4 of the present invention. The same components as those in FIGS. 1 to 6 are denoted by the same reference numerals, and description thereof is omitted.

  Compared with the fuel cell of Embodiment 1, the fuel cell of Embodiment 4 is configured to prevent the gas from wrapping around more reliably and to enclose the fiber sheet in the resin more reliably.

  As shown in FIG. 8, the fuel cell 100 of the fourth embodiment includes an electrode-membrane assembly (hereinafter referred to as MEA) 1 that is a pair of conductive separators and an anode-side separator 7a that forms a fuel gas path. Are integrally formed with a shape sandwiched between cathode-side separators 7b forming an oxidant gas path.

  More specifically, in the electrode layers 3a and 3b, the gas diffusion layers 5a and 5b of the MEA 1 are in contact with the surfaces of the anode-side separator 7a and the cathode-side separator 7b, and the reaction on the anode side of the anode-side separator 7a. Each gas flow path is determined by the gas flow path 11a, the reaction gas flow path 11b on the cathode side of the separator 7b on the cathode side, and the gas diffusion layers 5a and 5b of the MEA 1.

  As a result, the fuel gas contacts the gas diffusion layer 5a on the anode-side separator 7a side, and the oxidant gas contacts the gas diffusion layer 5b on the cathode-side separator 7b side to cause an electrochemical reaction.

  The anode-side separator 7a, the cathode-side separator 7b, and the peripheral edges of the MEA 1 are bonded and integrally joined by frame bodies 9a and 9b made of a resin containing an insulating fiber sheet at least partially. . Furthermore, the end part of the insulating reinforcing fiber is wrapped in resin, and the fiber end part has a structure that does not come into contact with the outside air.

  A method for producing the fuel cell will be described with reference to FIG. First, the portions of the anode-side separator 7a and the cathode-side separator 7b that are not in direct contact with the electrodes of the MEA 1 on the side facing the MEA 1 are provided with irregularities on the surface, and the innermost and outermost portions The separator is formed so that the thickness of the separator becomes the largest during this period, and the average thickness of the separator 7a becomes thinner toward the inner periphery and the outer periphery. This molding may be performed at the time of producing the separator or may be shaved later.

  Next, a resin containing an insulating fiber sheet, for example, a prepreg sheet in which a glass fiber is impregnated with an epoxy resin is cut into a shape that can be arranged around the electrode, and the frame piece (the anode side frame piece 8a, the cathode side). Frame piece 8b) and arranged around the electrode layers 3a and 3b of MEA1 and at positions on the anode side and cathode side of the solid polymer electrolyte membrane 2, and MEA1 and the frame piece (anode side frame piece 8a, The cathode-side frame piece 8b) is sandwiched between a pair of separators (anode-side separator 7a, cathode-side separator 7b).

  This fuel cell is set in a pressurizing device with a heater or a pressurizing device in a thermostatic bath, and the temperature is raised to a temperature at which the resin softens. When the resin is softened, the pressure at which the fuel cell can exert its power generation performance, that is, the electrode layers 3a and 3b can contact the ribs between the flow paths of the separators (the anode side separator 7a and the cathode side separator 7b) without any gap. A predetermined time is applied by applying a predetermined pressure.

  During this time, the resin of the frame pieces (the anode-side frame piece 8a and the cathode-side frame piece 8b) flows to fill various gaps with the members in contact with the frame pieces. For example, the gap between the unevenness of the separator and the frame piece, and the gap between the frame piece and the solid polymer electrolyte membrane.

  This prevents leakage of gas to the outside. Also, in the part where the thickness of the separator is thinner toward the inner periphery, the volume of the resin that can flow is increased toward the inner periphery. The gaps between the electrode, the separator, and the solid polymer electrolyte membrane (the anode side gap 16a and the cathode side gap 16b) can be more reliably filled with the resin.

  As a result, the gap around which the gas flows is closed, so that it is possible to obtain a fuel cell with little reduction in gas utilization. Further, in the portion where the thickness of the separator becomes thinner toward the outer periphery, the volume in which the resin can flow is increased toward the outer periphery, so that the resin flows toward the outer periphery. The fluidized resin may protrude slightly from the outer end face of the separator.

  On the other hand, since the convex part formed in the separator surface bites into resin inside and the glass fiber which exists in resin inside is caught in a convex part, there exists an effect which suppresses that a glass fiber moves on the flow of resin.

  Here, the glass fiber may be a woven fabric or a non-woven fabric, but the woven fabric has a stronger force for fixing the entire woven fabric when caught by the convex portion. In addition, the woven fabric is less likely to pierce the membrane by the fibers extending in the direction perpendicular to the membrane. Thus, the edge part of the glass fiber which exists in resin inside can be reliably covered with resin, and the deterioration which arises from the interface of a fiber and resin can be prevented.

  Next, after the resin has sufficiently flowed, the set temperature is changed to a temperature at which the resin is cured while a predetermined pressure is applied, and a predetermined time is set. This curing temperature may be the same as or higher than the softening temperature of the resin. By this step, the inside of the fuel cell can be held in the best condition, and the assembly of the fuel cell is completed.

  Thus, according to the fuel cell of the fourth embodiment, the resin sheet containing reinforcing fibers plays the role of a frame and a seal, so there is no need to use a large amount of expensive seals, and the resin flows into the gaps. Therefore, the gaps and tolerances during assembly can be greatly eliminated, and fuel cells can be created in a simple process.

  As described above, the present invention can provide a high-performance fuel cell that closes the gap with a simple structure and does not leak, and is manufactured at a low cost not only by the material cost but also by a manufacturing process with a small number of steps. Therefore, it can be applied to the production of a fuel cell for a polymer electrolyte fuel cell.

1 MEA
2 Solid polymer electrolyte membrane 3a, 3b Electrode layer 4a, 4b Catalyst layer 5a, 5b Gas diffusion layer 7a, 7b Separator 8a, 8b Frame piece 9a, 9b Frame body 11a, 11b Reaction gas flow path 16a, 16b Gap

Claims (18)

A polymer electrolyte membrane, a membrane electrode assembly having a pair of electrode layers sandwiching the polymer electrolyte membrane, and
A pair of plate-like separators sandwiching the membrane electrode assembly;
An annular frame provided on a peripheral edge of the polymer electrolyte membrane;
A fuel cell comprising a cell having
The frame body is composed of an insulating fiber sheet disposed on both sides of the membrane electrode assembly so as to sandwich a peripheral edge portion of the membrane electrode assembly, and a resin containing the fiber sheet,
The resin is formed so as to fill a gap between the fiber sheet and the separator and cover an outer peripheral end of the fiber sheet.
Fuel cell.   The fuel cell according to claim 1, wherein at least one convex portion formed on the separator is in contact with the fiber sheet. The resin protrudes outward from the outer peripheral surface of the separator,
The fuel cell according to claim 1 or 2. The frame body has a portion that is thinner toward the inner periphery,
The fuel cell according to any one of claims 1 to 3. In the frame, the average thickness of the inner peripheral side portion is thinner than the average thickness of the outer peripheral side portion.
The fuel cell according to any one of claims 1 to 3. The frame has the thinnest part between the innermost peripheral part and the outermost peripheral part,
The fuel cell according to any one of claims 1 to 3. The fiber sheet is a woven fabric or a nonwoven fabric.
The fuel cell according to any one of claims 1 to 6. The fibers of the fiber sheet are inorganic fibers.
The fuel cell according to any one of claims 1 to 7. The inorganic fiber is a glass fiber.
The fuel cell according to claim 8. The fuel cell according to claim 1, wherein the resin includes a thermosetting resin. A polymer electrolyte membrane, a membrane electrode assembly having a pair of electrode layers sandwiching the polymer electrolyte membrane, and
A pair of plate-like separators sandwiching the membrane electrode assembly;
An annular frame provided on a peripheral edge of the polymer electrolyte membrane;
A method of manufacturing a fuel cell including a cell having the following:
Arranging a pair of frame pieces having an insulating fiber sheet in the resin so that the pair of frame pieces sandwich the peripheral edge of the membrane electrode assembly,
Arranging the pair of plate-like separators so as to sandwich the membrane electrode assembly and the pair of frame pieces;
Pressurizing the cell in the thickness direction of the polymer electrolyte membrane, and pressurizing a part of the softened resin to the outer peripheral side of the cell;
A method for producing a fuel cell, comprising: The separator includes a convex portion on a surface of the separator facing the frame piece,
The pressurizing step is a step of extruding a part of the resin in the softened state to the outer peripheral side of the cell while restricting the convex portion from contacting the fiber sheet and moving the fiber sheet to the outer peripheral side. The method for producing a fuel cell according to claim 11.   The method for manufacturing a fuel cell according to claim 11, further comprising a curing step of curing the resin in a pressurized state after the pressurizing step.   In the curing step, a plurality of the cells to be the cells are stacked in the thickness direction of the polymer electrolyte membrane, and a part of the resin in the softened state is applied to the outer peripheral side of the cells in a state where a predetermined load is applied in the stacking direction. The method of manufacturing a fuel cell according to claim 13, wherein the resin is cured after being extruded.   The method for manufacturing a fuel cell according to claim 13 or 14, wherein, in the curing step, the resin including a thermosetting resin is heated to a temperature at which the resin is cured to cure the resin.   The fuel cell manufacturing method according to claim 11, wherein the pressurizing step includes a step of heating the resin so that the resin is in a softened state.   The method of manufacturing a fuel cell according to any one of claims 11 to 16, wherein the frame piece before the pressurizing step has an outer peripheral end portion of the fiber sheet not covered with a resin.   18. The fuel cell manufacturing method according to claim 11, wherein an outer peripheral end of the fiber sheet is covered with a resin in the frame piece before the pressurizing step.

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