JP2004158463A - Solid polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell with low cost, a compact size, improved mechanical strength and a simple structure. <P>SOLUTION: The solid polymer electrolyte fuel cell is composed of a plurality of unit cells formed by laminating an electrode having a pair of catalyst reaction layers interposing a solid polymer electrolyte film, a means supplying and distributing a mixed fuel gas containing hydrogen to one side of the electrode, and a means supplying and distributing oxidant gas including oxygen to the other side of the electrode through a separator. The separator is made of a metal plate having a gas flow groove, and the gas flow groove and the means of supplying and distributing fuel gas are connected to each other by an airtight non-metallic material. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a normal-temperature operation type fuel cell used for a portable power supply, an electric vehicle power supply, a home cogeneration system, and the like, and particularly to a solid polymer electrolyte fuel cell.

A solid polymer electrolyte fuel cell is a device in which a fuel gas such as hydrogen and an oxidizing gas such as air are electrochemically reacted by a gas diffusion electrode, and generates electricity and heat simultaneously.
An example of this type of polymer electrolyte fuel cell is shown in FIG.
On both surfaces of the solid polymer electrolyte membrane 3 for selectively transporting hydrogen ions, a catalytic reaction layer 2 mainly composed of a carbon powder carrying a platinum-based metal catalyst is arranged in close contact. Further, a pair of diffusion layers 1 having both gas permeability and conductivity are provided in close contact with the outer surface of the catalytic reaction layer 2. The electrode 23 is constituted by the diffusion layer 1 and the catalytic reaction layer 2.

  Outside the electrodes 23, a conductive material for mechanically fixing the electrodes 23 and the electrolyte membrane electrode assembly (MEA) 22 of the electrolyte membrane 3 and electrically connecting adjacent MEAs 22 to each other in series is provided. Are disposed. A gas flow path 5 for supplying a reaction gas to the electrode and carrying away a gas generated by the reaction or an excess gas is formed in a portion of the separator plate 4 which is in contact with the electrode 23. Although the gas flow path 5 can be provided separately from the separator plate 4, a method in which a groove is provided on the surface of the separator plate to form a gas flow path is generally used.

In order to supply the fuel gas to the groove, a pipe jig for dividing the pipe for supplying the fuel gas into the number of separators to be used and connecting the tip of the branched pipe directly to the separator-shaped groove is required. This jig is called a manifold, and the type directly connected to the fuel gas supply pipe as described above is called an external manifold.
On the other hand, there is an internal manifold type having a simpler structure. The internal manifold is a device in which a through-hole is provided in a separator plate having a gas flow path formed therein, an inlet / outlet of the gas flow path reaches the hole, and fuel gas is directly supplied from the hole.

On the other surface of the separator plate 4 arranged for every two cells, a cooling channel 24 for circulating cooling water for keeping the battery temperature constant is provided. The cooling water is circulated, and the heat energy generated by the reaction is used in the form of hot water or the like.
Further, the sealing material 17 and the O.sub.2 are sandwiched around the electrode 23 so that the hydrogen and air do not leak out of the battery or mix with each other, and further, the cooling water does not leak out of the battery. A ring 18 is arranged; The sealing member 17 and the gasket 19 may be assembled in advance integrally with the electrode 23 and the electrolyte membrane 3.

As another sealing method, as shown in FIG. 3, a gasket 19 having the same thickness as the electrode and made of a resin or a metal plate is arranged around the electrode, and the gasket 19 and the separator plate 4 are separated from each other. There is also a structure in which the gap is sealed with a sealing material 17 such as grease or an adhesive.
Further, in recent years, a method of using a MEA 22 using electrodes 23 of the same size as the electrolyte membrane 3 and injecting and solidifying a resin 21 having a sealing effect in advance in a portion requiring a gas seal as shown in FIG. Has also been proposed. That is, a method has been devised in which gas sealing between the separator plate 4 and the separator plate 4 is ensured by impregnation with the resin 21.

  Many fuel cells have a stacked structure in which many unit cells are stacked as described above. In a stacked battery, a cooling plate is provided for each of the unit cells 1 to 3 in order to discharge heat generated together with electric power to the outside of the battery during fuel cell operation. The cooling plate generally has a structure in which a heat medium such as cooling water flows through a space surrounded by a thin metal plate. As shown in FIGS. 2 to 4, there is also a method in which a cooling channel 24 is formed on the back surface of the separator plate 4 constituting the unit battery, that is, on the surface where cooling water is to flow, and the separator plate 4 itself functions as a cooling plate. is there. At that time, an O-ring and a gasket are also required to seal the heat medium such as cooling water, but this seal secures sufficient conductivity between the top and bottom of the cooling plate by completely crushing the O-ring. There is a need to.

Next, as for the above-mentioned manifold, an internal manifold type in which a gas supply hole, a gas discharge hole, and a cooling water supply / discharge hole for each unit battery are secured inside the stacked battery is generally used. Here, as an example of an internal manifold type polymer electrolyte fuel cell, FIG. 5 shows a perspective view with a part thereof cut away.
As in the structure shown in FIG. 2, the diffusion layer 1, the catalytic reaction layer 2, the electrolyte membrane 3, and the separator plate 4 are laminated to form a gas flow path 5. Further, a gas manifold 8 for supplying or exhausting gas to and from the battery, and a cooling water manifold 8 'for supplying and discharging water for cooling the battery to and from the battery are formed.

However, in such an internal manifold type, when the battery is operated using the reformed gas, the CO concentration increases in the downstream region of the fuel gas flow path of each battery, so that the electrode is poisoned and the temperature decreases, The temperature drop further promotes the poisoning of the electrode.
In order to suppress such a decrease in battery performance, an external manifold type has been reviewed as a structure in which a frontage of a gas supply / discharge unit from the manifold to each unit battery can be made as wide as possible.

  In the case of an internal manifold type fuel cell, since a constant tightening pressure is applied to the entire cell, the reliability of the gas seal is generally high. On the other hand, in the case of an external manifold type fuel cell, it is difficult to obtain a smooth sealing surface because the side surface of the laminated cell in contact with the flange surface of the manifold is a laminated body of thin plates such as MEAs and separators. That is, generally, the reliability of the gas seal is lower than that of the internal manifold system.

  However, in the case of the internal manifold system, when the number of stacked batteries and the power output increase, a large amount of fluid must be supplied and discharged through the internal manifold holes, and the pressure loss in the manifold section increases. Therefore, for a fuel cell with a small number of stacks, it is necessary to use a manifold hole with a small hole diameter in consideration of the compactness of the whole cell, and conversely, for a fuel cell with a large number of stacks, it is necessary to use a manifold hole with a large hole diameter to suppress pressure loss. is there. Therefore, in the internal manifold system, the number of layers must always be considered in the design of the separator and the MEA.

  In any case, it is necessary to stack a large number of unit batteries including the cooling unit in one direction, arrange two end plates at both ends thereof, and fix the two end plates between each other with a fastening rod. As a fastening method, it is desirable to fasten the unit batteries as uniformly as possible within the plane. From the viewpoint of mechanical strength, a metal material such as stainless steel is usually used for the end plates and the fastening rods. These end plates and fastening rods and the laminated battery are electrically insulated by an insulating plate or the like, and have a structure in which current does not leak outside through the end plates. As for the fastening rod, there has been proposed an improved system in which the fastening rod is passed through a through hole formed in a separator plate, or the entire stacked battery is tightened with a metal belt over an end plate.

  Furthermore, in any of the sealing methods shown in FIGS. 2 to 4, a constant tightening pressure is required in order to maintain the sealing performance and to keep the contact resistance between the electrode and the separator small, and the gap between the fastening rod and the end plate is required. It adopts a configuration such as inserting a screw spring or a disc spring into the device. Further, the tightening pressure secures electrical contact between members constituting the battery, such as a separator, an electrode, and an electrolyte membrane.

  On the other hand, the separator in such a polymer electrolyte fuel cell needs to have high conductivity, high gas tightness with respect to a fuel gas, and high corrosion resistance to a reaction when redoxing hydrogen / oxygen. For this reason, the conventional separator is usually made of a carbon material such as glassy carbon or expanded graphite, and the gas flow path is formed by cutting the surface of the separator or, in the case of expanded graphite, molding by a mold.

  However, in recent years, metal plates such as stainless steel have been used instead of conventionally used carbon materials. 6 and 7 are schematic plan views of a conventional metal separator plate 4. FIG. As shown in FIG. 6, ribs 6 are formed of resin or the like on the outer peripheral portion of the separator plate 4 or the outer peripheral portions of the holes of the internal manifold, and a metal mesh 7 or a corrugated fin made of metal is provided between the electrode and the metal plate. The gas flow path is formed by the insertion. Alternatively, as shown in FIG. 7, a single metal plate is processed by press molding or the like to form a valley fold 9 and a ridge fold 10, and the gas is formed at the valley fold 9 from the gas supply-side manifold to the gas discharge-side manifold. A method of forming a flow path is also conceivable.

  In the fuel cell described above, in order to seal a gas such as hydrogen gas or air, it is necessary to arrange a sealing material or an O-ring around the electrode. At this time, the MEA needs a margin of about 10 mm for installing the sealing material. Further, even in a method in which a resin having a sealing effect is immersed in the MEA to form a sealing portion, a sealing width of about 5 mm is required.

  In order to reduce the size and space of the fuel cell, it is necessary to make these seal widths as small as possible. Further, it is necessary to sandwich the seal material and the seal portion between the upper and lower separators, and a relatively large tightening force must always be applied. Therefore, the size and weight of the fastening jigs such as the end plates and the fastening rods are increased, and this is a problem for reducing the size and weight of the entire battery.

  In a method using a sealing material or an O-ring, or a method in which a resin is immersed in a MEA in advance to seal, a member and a step for sealing are required, and further measures are desired for cost reduction. I was Further, in the polymer electrolyte fuel cell, it is necessary that the electrolyte membrane and the electrode, and the electrode and the separator plate are sufficiently pressed against each other, but in these conventional methods, the tightening pressure from the end plate is applied to the electrode portion and the seal. There is also a problem that it is difficult to control the thickness and shape for applying a sufficient pressure contact force because it acts on both parts.

  In the internal manifold system, for fuel cells with a small number of stacks, use manifold holes with small holes in consideration of the compactness of the whole cell, and conversely, for fuel cells with large numbers of stacks, use manifold holes with large holes to suppress pressure loss. There is a need to. That is, in the design of the separator and the MEA, the number of layers must always be considered.

On the other hand, in the conventional method of cutting a carbon plate, it is difficult to reduce not only the material cost of the carbon plate but also the cost of cutting the carbon plate, and the method using expanded graphite has a high material cost, and this method has been put into practical use. Is considered an obstacle for
Further, in the method using a metal plate described above, for example, in the case of the separator shown in FIG. 6, if the gas flow rate is reduced and the gas utilization rate is increased in order to reduce the power of the fuel gas supply, the fuel on the electrode surface is increased. The flow velocity of the gas becomes small, and it becomes difficult to discharge the generated water vapor. It has also been difficult to flow gas uniformly between the supply-side manifold and the discharge-side manifold.

In the separator shown in FIG. 7, the gas flow rate is maintained, and the gas can be flowed uniformly. However, since the end face of the manifold portion has a wavy structure, it is difficult to seal the fuel gas. Also, there are many restrictions on the processing of the metal plate, and it is difficult to freely design the gas flow path.
Therefore, an object of the present invention is to provide a separator capable of solving such a problem.

In order to solve the above problems, in the present invention, an electrode having a pair of catalytic reaction layers sandwiching a solid polymer electrolyte membrane, means for supplying and distributing a fuel gas mixture containing hydrogen to one of the electrodes, and In a solid polymer electrolyte fuel cell, a plurality of unit cells each having a unit for supplying and distributing an oxidizing gas containing oxygen to the other surface are stacked with a plurality of layers interposed therebetween via a conductive separator.
The separator is constituted by a metal plate having a gas flow groove, and the gas flow groove and the means for supplying and distributing the fuel gas are connected by a gas-tight non-metallic material.

It is preferable that the gas flow grooves include a plurality of linear grooves parallel to each other.
Preferably, the gas flow groove formed on one surface of the metal plate forms a recess of the gas flow groove on the other surface of the metal plate.
Further, it is preferable that the separator is composed of a plurality of metal plates, and that at least one of the metal plates has a gas flow groove on the entire surface.
Further, when the gas-tight non-metallic material is pressed against the metal plate at a predetermined pressure or more, the contact surface between the metal plate and the gas-tight non-metallic material has gas tightness with respect to the fuel gas. It is preferred to have.

In the separator, a gas flow groove of the separator can be formed by press forming or bending a metal plate.
Furthermore, the separator is formed by pressing or bending the entire surface of the metal plate to form a gas flow groove having a plurality of linear shapes parallel to each other, and then forming a part of the metal plate subjected to the wave processing. It can be manufactured by flattening.
Further, the gas sealing material can be integrated with the metal plate having the gas flow grooves formed by bonding or baking to the metal plate.

  According to the present invention, a metal separator made of stainless steel or the like can be used without cutting, so that a significant cost reduction can be achieved during mass production. In addition, the thickness of the separator can be further reduced, which contributes to the miniaturization of the laminated battery.

  In the solid polymer electrolyte fuel cell according to the present invention, instead of the conventional sealing method in which a sealing material is sandwiched between battery components such as a separator to seal, a sealing material is provided on the side surface of the stacked battery components. A sealing method of disposing may be used. Further, a seal portion and a seal material around the electrode of the MEA (electrolyte membrane electrode assembly) are removed to form an electrode having basically the same area as the separator. In addition, a fibrous material or the like having higher tensile strength is disposed on a sealing material disposed on a side surface of the stacked battery. In addition, the production unit is divided into a separator and an electrode lamination portion sharing the MEA, and a manifold portion having a different design depending on the number of laminations and the battery output.

  Further, in the present invention, when manufacturing a polymer electrolyte fuel cell, a stacked battery in which a plurality of unit cells each including a battery constituent member such as a polymer electrolyte membrane, an electrode having a catalytic reaction layer, and a separator are stacked. Is preferably provided with a gas sealing property by covering the side surface with a gas-tight electric insulating material (hereinafter, also referred to as a “sealant”). This eliminates the need for a sealant around the electrodes of the MEA, and allows the electrodes to be configured up to the side surface of the stacked battery, resulting in a compact configuration as a whole.

Further, the composite material is obtained by coating the sealing material covering the side surface of the laminated battery with a material having a higher tensile strength than a sealing material such as a fiber, a woven fabric, a nonwoven fabric, and a net. And the structure which each battery component member mechanically fastens the peripheral part by this composite material can be used, and the required fastening force from both ends of the laminated battery can be minimized.
When a sealing material is provided on the side surface of the stacked battery, a so-called external manifold structure in which the electrode stacked portion and the manifold portion are separated easily becomes easy, and the design is made by the electrode stacked portion sharing the separator and the MEA as a manufacturing unit, the number of stacked layers, and the battery output. Can be divided into different manifold sections, and cost reduction can be achieved.

  Furthermore, as a method of manufacturing the battery of the present invention, the components such as the MEA and the separator are stacked and fixed, and then a resin or a sealing material is applied to the side surface, thereby greatly simplifying the manufacturing process. it can.

Further, in the polymer electrolyte fuel cell according to the present invention, a gas manifold is provided via the gas-tight electric insulating material. With such a configuration, the side surface of the stacked battery in contact with the sealing surface of the external manifold can be smoothed, and the gas sealing between the external manifold and the side surface of the stacked battery can be improved.
Here, if the gas manifold is made of an elastic body, it absorbs the creep in the thickness of the laminated battery in the laminating direction and absorbs the unevenness on the side surface of the laminated battery in contact with the sealing surface of the external manifold. The sealing property between the manifold and the side surface of the stacked battery can be improved.

In addition, when the gas-tight electric insulating material is formed of a resin such as a thermoplastic resin such as a thermosetting resin such as a silicone resin or a phenol resin, or a rubber such as a silicone rubber or a butadiene rubber, the electric insulating property becomes high. Can be maintained, which is preferable.
In particular, when an elastomer is used, it absorbs the creep in the thickness of the laminated battery in the laminating direction, and absorbs the unevenness on the side surface of the laminated battery in contact with the sealing surface of the external manifold, thereby providing an overall seal. This is convenient because reliability can be improved.
Further, when the material constituting the gas manifold and the hermetic electric insulating material are the same material, the joining property between the external manifold and the side surface of the stacked battery in contact with the external manifold due to the difference in thermal expansion coefficient is not impaired. Therefore, the sealing property between the external manifold and the side surface of the laminated battery can be improved, which is preferable.

Since the method for producing a solid polymer electrolyte fuel cell includes a step of hermetically joining the external manifold and the electrically insulating material, the sealing property between the external manifold and the side surface of the stacked battery can be improved, which is preferable. is there. In particular, it is preferable that this step be performed by ultrasonic welding because the bonding property is improved.
In addition, when the side surfaces of the laminated battery and the external manifold are integrally molded by injection molding and molded, there is no joint surface between the external manifold and the side surface of the laminated battery, and the sealing property can be improved, which is preferable.

  Next, features of the solid polymer electrolyte fuel cell according to the present invention will be described. In the present invention, in order to solve the above-mentioned problem with respect to the separator, the present invention has made a significant improvement to the structure shown in FIG. That is, the gas flow groove forms a flow path by press molding or the like, but the manifold portion has a flattened structure. The gas flow grooves connecting the manifold and the gas flow grooves formed by press molding are made of a gas-tight non-metallic material which may be the same as the gas-tight electric insulating material.

A plurality of substantially parallel gas flow grooves formed by processing the metal plate are connected by curved gas flow grooves made of a gas-tight non-metallic material. Further, among the metal plates constituting the separator, a flow path is formed on the entire surface of one metal plate by a method not by cutting, and another one flat metal plate and a non-metallic material provided thereon are used. The separator may be configured in combination with the gas flow grooves and the projections.
A method of forming a gas flow groove on both surfaces by plastically deforming a single metal plate to form gas flow grooves on both surfaces can also be adopted.

In addition, as a method of forming a gas flow groove only in one portion of one metal plate, a corrugated process is once performed on the entire surface of the metal plate without using a cutting method, and then flatness such as a peripheral gas seal portion is required. May be flattened by press working or the like.
Further, when the gas-tight non-metal material forming the gas flow groove is compressed, the gas-tight non-metal material has a gas sealing property on the compressed surface, and the gas flow groove formed of the gas-tight non-metal material substantially corresponds to the metal plate. It may be integrated integrally.

  All the separators used in the polymer electrolyte fuel cell of the present invention are obtained by pressing or bending a flat plate of a metal such as stainless steel and combining a gas flow groove made of a gas-tight non-metallic material such as a resin. The direct material cost is low, the mass productivity is excellent, and the processing cost is extremely low.

  In order to keep the utilization rate of the supplied fuel gas high and to increase the gas flow rate, the gas flow groove must be narrowed and the cross-sectional area must be reduced. However, if a gas flow groove is formed by introducing a wave-like structure into the metal plate, the manifold end face of the gas flow groove has a wave-like structure, and it is difficult to maintain the gas sealing property at the manifold portion when the layers are stacked.

  Therefore, the central portion of the separator where most of the electrode substantially contacts is formed with a gas flow groove by corrugating the metal plate, thereby maintaining the conductivity between the electrode and the separator. On the other hand, if the metal plate around the manifold hole is flat, and a gas flow groove made of a gas-tight and non-conductive material such as resin is formed in that portion, the gas seal at the end of the manifold is maintained. Can be.

  In addition, forming a curved gas flow groove by press molding or the like has many problems because the shape that can be molded is limited, and distortion may remain even after molding. Therefore, the gas flow grooves formed on the metal plate were a plurality of straight and parallel grooves. Furthermore, at the end of the groove in contact with the peripheral portion of the electrode, a gas flow groove having a curved portion connecting the adjacent groove and the groove is formed of a resin or the like, and the gas flow rate can be maintained high even at the same gas utilization rate. did. Further, the gas flow velocity is changed by changing the design of the groove of the curved portion made of resin.

Further, if a large number of grooves are to be formed in a part of one metal plate, the shape that can be formed is limited. In view of this, a plurality of metal plates having a corrugated surface formed in advance on the entire surface are used as the metal plates for forming the gas flow grooves, and these are finally combined. This method greatly reduces processing problems.
Further, in a structure in which a gas flow groove portion of one metal plate is corrugated, and a gas flow groove is formed on both surfaces of the metal plate, a convex portion separating an adjacent gas flow groove on one surface has a gas flow groove on the back surface. Therefore, the thickness of the separator can be reduced to the sum of the depth of the gas flow groove on one side and the thickness of the metal plate.
Further, the material constituting the gas flow groove has a pressure sealing property, and if it is integrated with the metal plate, it is not necessary to newly provide a sealing material, and the assembly of the laminated battery is greatly facilitated.
Examples of the present invention will be described more specifically with reference to the drawings, but the present invention is not limited thereto.

<< Reference Example 1 >>
A carbon powder having a particle size of several microns or less was immersed in an aqueous chloroplatinic acid solution, and a platinum catalyst was supported on the surface of the carbon powder by a reduction treatment. At this time, the weight ratio of carbon to the supported platinum was 1: 1. Next, the carbon powder carrying platinum was dispersed in an alcohol solution of a polymer electrolyte to form a slurry.
On the other hand, a 400 μm-thick carbon paper serving as a diffusion layer of an electrode is impregnated with an aqueous dispersion of fluororesin (NEOFLON ND1 manufactured by Daikin Industries, Ltd.), which is then dried and heat-treated at 400 ° C. for 30 minutes. By doing so, water repellency was imparted. Next, the slurry containing carbon powder was uniformly applied to one surface of the water-repellent carbon paper to form a catalytic reaction layer, which was used as an electrode.

The structure shown in FIG. 5 was adopted, and two carbon paper electrodes produced by the above-described method were stacked with the surface on which the catalytic reaction layer 2 was formed facing inward with the electrolyte membrane 3 interposed therebetween, and then dried. The length and width of the carbon paper were 10 cm, and the carbon paper was disposed at the center of the electrolyte membrane 3 having a length and width of 12 cm. In order to prevent the supplied fuel gas from leaking or mixing with each other, a sheet of silicone rubber having a thickness of about 350 μm is provided as a sealing material with the electrolyte membrane 3 interposed between the electrodes, and hot pressed at 100 ° C. for 5 minutes. Then, MEA was obtained.
The MEA was sandwiched between both sides of a separator plate 4 made of airtight carbon to form a unit battery.

  The separator plate had a thickness of 4 mm, and a gas passage 5 having a width of 2 mm and a depth of 1 mm was cut on the surface by cutting, and a gas manifold 8 and a cooling water manifold 8 ′ were arranged around the periphery thereof. . When the MEA was sandwiched between the separators, a polyethylene terephthalate (PET) sheet having the same outer dimensions as the carbon separator was disposed around the electrodes. This PET sheet was used as a spacer between the carbon separator and the electrolyte membrane. After laminating two such unit batteries, the cooling section formed in the separator was laminated with the cooling channel through which the cooling water flows, and the pattern was repeated and laminated. No O-ring for sealing in the cooling section was used.

Fifty cells of such a battery constitutional unit were stacked, and a metal current collector plate and an insulating plate made of an electrically insulating material were fixed at both ends with an end plate and a fastening rod. The fastening pressure at this time was 10 kgf / cm ² per area of the separator. Although fuel gas and cooling water were passed through the 50-cell battery module, they leaked from the gap between the PET sheet and the separator, and battery performance was not obtained.

  Therefore, in this reference example, a solution obtained by dissolving a phenol resin powder in an organic solvent was applied to the side surface of a 50-cell battery module, and dried and solidified. A phenol resin solution was also injected into the inside of the manifold from a fluid supply / discharge port provided in the end plate, and a phenol resin was applied to the inside surface of the manifold and dried.

A battery test was performed by circulating cooling water through hydrogen and air through the 50-cell stacked battery. The battery output under the conditions of a hydrogen utilization rate of 70%, an oxygen utilization rate of 20%, a hydrogen humidifier bubbler temperature of 85 ° C., an oxygen humidifier bubbler temperature of 75 ° C., and a battery temperature of 75 ° C. was 1050 W (30 A-35 V).
In addition, there was no gas leak or cooling water leak to the battery side surface and the inside of the manifold. Further, even if the fastening pressure at the time of assembly was set to 5 kgf / cm ² , there was no effect on battery performance.

  After the above-described characteristics evaluation, the battery was disassembled and the internal state was observed. FIG. 8 shows a schematic cross-sectional view of the battery-side surface portion. It was sufficiently observed that the applied phenolic resin 11 covered the side surface and was bonded to the carbon separator plate 4 and the PET sheet 12 to maintain the sealing property. When butadiene rubber was dissolved in an ester solvent in addition to phenol resin as a resin to be applied to the side surface, a sealing effect almost equivalent to that of phenol resin was obtained. As described above, it goes without saying that many known resins can be used in addition to the phenol resin used in the present reference example.

<< Reference Example 2 >>
In the battery manufactured in Reference Example 1, it is necessary to prevent the resin application to the manifold from blocking the gas distribution supply port. Therefore, there are restrictions on the concentration and viscosity of the resin coating solution and the pore size of the gas distribution supply port. Therefore, in the battery of the present reference example, an external manifold system was adopted instead of the internal manifold system. The configuration of the separator used here is shown in FIG.

In FIG. 9, the manifold is not provided on the separator, and only the gas flow path 5 is disposed on the entire surface. The supply port and the discharge port of the gas flow path 5 were configured on sides facing each other. When the unit batteries were stacked, the hydrogen gas supply / discharge port 13, the air supply / discharge port 14, and the cooling water supply / discharge port 15 were arranged such that the external manifolds were located on the opposite side surfaces.
The configuration of the electrodes was the same as that shown in FIG. A PET sheet was placed as a spacer around the electrodes. After stacking two unit batteries, a battery module in which 50 cells were stacked in a pattern of stacking cooling units was assembled. No O-ring was used to seal the cooling section. Unlike the battery of Reference Example 1, the current collector plate, the insulating plate, and the end plate did not require a fluid supply / discharge port. The fastening rod portion for fastening the battery module was provided on a side different from the side where the gas supply / discharge port was open. Next, similarly to the battery of Reference Example 1, the phenol resin was covered from the side surface as a sealing material. At this time, the sealing material was not blocked at the gas supply / discharge port and the cooling water supply / discharge port.

Next, as shown in FIG. 1, a semi-cylindrical external manifold 25 made of a phenolic resin is supplied from the side of the battery module to an air supply port, a discharge port, a hydrogen supply port, a discharge port, a cooling water supply port, and a discharge port. Are provided so as to cover each row. This external manifold was fixed with screws 26 at the end plate. The seal between the external manifold and the sealing material covering the side surface of the battery was made with silicone resin.
A battery test was performed by circulating cooling water through hydrogen and air through the 50-cell stacked battery. The battery output under the conditions of a hydrogen utilization rate of 70%, an oxygen utilization rate of 20%, a hydrogen humidifier bubbler temperature of 85 ° C., an oxygen humidifier bubbler temperature of 75 ° C., and a battery temperature of 75 ° C. was 1020 W (30 A-35 V).

The same performance can also be obtained when the external manifold made of phenolic resin is fixed on the side surface of the battery before forming the sealing material, and then the sealing material is applied and dried to reduce the number of assembly steps. Was.
Further, in the battery of the present reference example, an external manifold made of resin was used. However, it is needless to say that a metal manifold can be used if the seal portion of the manifold that contacts the battery is electrically insulated.
In this reference example, by adopting a method of arranging a sealing material on the entire side surface of the polymer electrolyte fuel cell, the external manifold method conventionally used in a fuel cell such as a molten carbonate fuel cell can be easily realized. Indicated.

  Further, with the configuration of the present embodiment, the manifold section and the battery stack section can be manufactured separately. This makes it possible, for example, to mass-produce a large number of battery stacks consisting of separators, electrodes and electrolytes of the same shape regardless of the fuel cell application and output scale, and to manufacture the manifold part according to the application and output scale. And showed that it can contribute to cost reduction.

<< Reference Example 3 >>
In the batteries shown in Reference Examples 1 and 2, a PET sheet spacer was disposed around the electrode as the MEA structure. In this reference example, the PET sheet was discarded and the carbon paper electrode coated with the catalyst layer was replaced with a carbon paper electrode. A battery having the same outer dimensions as the separator and having a structure in which the electrode end reached the side surface of the battery during lamination was produced.

As in the battery of Reference Example 2, a sealing material was formed on the side surface of the battery stack, and an external manifold was joined. Other configurations were the same as the battery of Reference Example 2, and a 50-cell laminated battery was assembled. In addition, in the gas seal test before performing the battery test, it was confirmed that if the phenol resin solution to be applied was too thick and the viscosity was too high, the sealing property was deteriorated. Therefore, in this reference example, attention was paid to the viscosity of the resin solution.
The result of the battery test of the module was performed under the same conditions as in Reference Example 1, and 1080 W (30 A-36 V) was obtained. This result was higher than that of a spacer having a spacer such as a PET sheet. It is considered that the reason for this is that, as shown in FIG. 10, since the sealing material 17 is applied from the outside at the end of the electrode, an electrode having substantially the same area as the carbon separator can be formed.

As shown in the present reference example, it was confirmed that sealing the battery components from the outside where they were stacked was extremely effective for reducing the size of the battery.
Further, the method of manufacturing a laminated battery carried out through the above-described Reference Examples 1 to 3, that is, a method of laminating battery constituent members in a predetermined order, fixing them with end plates or the like, and then disposing a sealing material on the side surface, The number of steps can be reduced drastically as compared with the method of sequentially arranging the sealing material on the side surface while stacking the members.
The carbon separator used in the present embodiment is of the external manifold type used in the embodiment 2, but the internal manifold type can be similarly configured.

<< Reference Example 4 >>
In order to put a polymer electrolyte fuel cell into practical use, reliability against various impact forces and thermal strain due to heat cycles is required. Therefore, in the present reference example, the following evaluation was performed.
The battery of this reference example was manufactured in the same manner as in Reference Example 3. However, after sealing the side surface with a phenol resin, it was covered with a cloth of glass fiber having a thickness of about 1 mm, and further impregnated with the phenol resin, and then solidified as a composite material.

When the laminated battery of Reference Example 3 was dropped from a height of 1 m, the laminated structure was displaced and gas leak occurred. However, in the battery of this Reference Example, since the sealing portion was reinforced with a glass fiber cloth, the height of the laminated battery from a height of 3 m was reduced. No gas leaked in the drop test.
Further, when a carbon fiber cloth having higher tensile strength was used instead of the glass fiber cloth, no gas leak was observed even in a drop test from 7 m.
The results of the battery test were performed under the same conditions as in Reference Example 1, and 1080 W (30 A-36 V) was obtained.

In the battery of the present reference example, a woven fabric was used as described above, but the same effect was obtained by using a nonwoven fabric or a net.
The reason for this is that, while the conventional battery applies the fastening pressure from two distant end plates, in this method, the fastening pressure from the end plates (5 kgf / cm ² ) and the adjacent battery configuration are added. This is because the members could be directly fixed.

  The sealing material used in the reference examples is a phenolic resin and has a certain degree of heat resistance, but becomes extremely hard after curing. When the heat cycle of the battery fabricated in this reference example was repeated about 5 times between 5 ° C. and 100 ° C., cracks probably appeared due to thermal strain occurred in the side sealing surface, and gas leak and cooling water leak occurred There has occurred. Therefore, when a silicone resin having more elasticity than the phenol resin is used for the sealing surface, and then molded with the phenol resin, the resin can withstand the above-mentioned heat cycle of 20 times or more. Furthermore, a battery having both durability against a heat cycle and mechanical strength was able to be produced by using it together with a fiber cloth.

  As described above, by using two or more materials having different mechanical properties such as Young's modulus and tensile strength in combination with the sealing material, a laminated battery module having high mechanical strength and heat cycle durability can be manufactured. .

<< Reference Example 5 >>
In long-term continuous operation of a polymer electrolyte fuel cell, a considerable fastening pressure must be constantly applied from both ends of the electrode. At this time, it becomes an obstacle that members such as the end plate and the fastening rod become long. Therefore, in the present reference example, the following evaluation was performed using a carbon fiber cloth.

The fastening pressure from the end plate fixed at the time of assembling the laminated battery was set to be as high as 10 kgf / cm ² , and the same phenolic resin and carbon fiber cloth as the battery of Reference Example 4 were used to form a sealing material on the side of the battery. After sufficiently solidifying the phenolic resin, the fastening rod was loosened to reduce the fastening pressure from the end plate. The other configuration was the same as the battery of Reference Example 4, and the battery of this Reference Example was produced.

When the same drop test as in the above reference example was performed on this battery, it was found that the battery could withstand a drop test of 5 m. Further, it was found that even when the fastening pressure from the end plate performed in the above process was reduced to 0.5 kgf / cm ² , the device could withstand a drop test of 5 m.
Although a stainless steel end plate having a thickness of 20 mm was used in the present reference example, the same strength was obtained even when a stainless steel end plate having a thickness of 5 mm was used at a fastening pressure of 0.5 kgf / cm ² . The same effect was obtained by using a lighter material such as reinforced plastic instead of metal such as stainless steel.

Further, the fastening pressure was set to 20 kgf / cm ^2, and after the phenol-based resin was sufficiently solidified similarly, the fastening rod was loosened to remove the end plate. Even in this state, it was confirmed that the stacked battery module had sufficient mechanical strength in the fastened state, and that no gas leak occurred even in a drop test from 3 m.
With the structure as in this reference example, the end plate could be removed, and the size and weight could be significantly reduced.

<< Example 1 >>
A carbon powder having a particle size of several microns or less was immersed in an aqueous chloroplatinic acid solution, and a platinum catalyst was supported on the surface of the carbon powder by a reduction treatment. At this time, the weight ratio of carbon to the supported platinum was 1: 1. Next, the carbon powder carrying platinum was dispersed in an alcohol solution of a polymer electrolyte to form a slurry.
On the other hand, a carbon paper having a thickness of 400 μm serving as an electrode is impregnated with an aqueous dispersion of a fluororesin (manufactured by Daikin Industries, Ltd., trade name: Neoflon ND1), which is dried and heat-treated at 400 ° C. for 30 minutes. This imparted water repellency.

As shown in FIG. 10, the slurry containing the carbon powder was uniformly applied to one surface of the carbon paper electrode subjected to the water-repellent treatment to form the catalytic reaction layer 2.
The carbon paper electrode and the electrolyte membrane 3 were cut into a size of 12 × 12 cm. Then, two carbon paper electrodes were arranged with the surface on which the catalyst layer 2 was formed facing up, and were overlapped with the electrolyte membrane 3 interposed therebetween, and then dried to produce the MEA 22.
The MEA 22 was sandwiched between both sides of the separator plate 4 made of airtight carbon to form a unit battery. The thickness of the separator plate 4 was 4 mm.

Two unit cells were stacked to obtain a battery constituent unit. No O-ring for sealing in the cooling section was used.
As shown in FIG. 9, the separator of the battery constituent unit has a cooling water passage 16 arranged on one surface, a separator plate 4a having a gas passage 5 arranged on the other surface, and a gas passage 5 arranged on one surface. And a separator plate 4b having the gas passage 5 arranged on the other surface and a separator 4c having the gas passage 5 arranged on one surface and the cooling water passage 16 arranged on the other surface. The hydrogen gas supply / discharge port 13 and the air supply / discharge port 5 and the cooling water supply / discharge port 15 of the cooling water channel 16 were provided on sides facing each other.
The gas passage 5 and the cooling water passage 16 are formed on the surface of the separator plate by cutting. For example, the gas flow path 5 of the present embodiment is formed by cutting a groove having a width of 2 mm and a depth of 1 mm into a shape shown in FIG.

In this way, 50 unit batteries are stacked, and a metal current collector and an insulating plate made of an electrically insulating material are laminated on both ends in order, and furthermore, an end plate is laminated in order, and bolts and nuts penetrating these are used. Then, both end plates were fastened to produce a laminated battery. The fastening pressure at this time was 10 kgf / cm ² per area of the separator. The fastening rod portion for fastening the battery module was provided on a side different from the side where the gas supply / discharge port was open.
Next, a phenol resin was used as a sealing material, and this solution was applied to the side surface of the laminated battery and dried to cover the side surface of the laminated battery to form a seal portion 20. At this time, the gas supply / discharge port and the cooling water supply / discharge port were not blocked by the sealing material. In addition, a phenol resin was applied to a portion of the external manifold that was in contact with the sealing surface so as to obtain a surface as smooth as possible.

Next, as shown in FIG. 1, a row of a hydrogen gas supply / discharge port 13, an air supply / discharge port 14, and a cooling water supply / discharge port 15 which expose a semi-cylindrical external manifold 25 made of stainless steel to the side surface of the stacked battery is formed. A manifold was provided to cover. These external manifolds 25 were fixed with screws 26 at the end plates.
In addition, a seal between the external manifold and a sealing material covering a side surface of the battery is provided with a ethylene-propylene-diene terpolymer copolymer (EPDM) sheet having closed cells on a predetermined external manifold sealing surface. The gasket 27 cut in the shape of was used.

A battery test was performed by circulating cooling water through hydrogen and air through the laminated battery. The battery output under the conditions of a hydrogen utilization rate of 70%, an oxygen utilization rate of 20%, a hydrogen humidifier bubbler temperature of 85 ° C., an oxygen humidifier bubbler temperature of 75 ° C., and a battery temperature of 75 ° C. was 1020 W (30 A-35 V).
Gas leakage from the seal portion of the external manifold was also measured, but no leak was detected, indicating that good sealing properties were obtained.
In this embodiment, by adopting a method of arranging a sealing material on the entire side surface of the polymer electrolyte fuel cell, an external manifold system conventionally used in a fuel cell such as a molten carbonate fuel cell can be easily realized.

  Further, when the configuration shown in this embodiment is adopted, the manifold section and the battery stack section can be manufactured separately. This makes it possible, for example, to mass-produce battery stacks consisting of separators, electrodes, and electrolyte bodies of the same shape regardless of the fuel cell application and output scale, and manufacture the manifold section according to the application and output scale. And can contribute to cost reduction.

<< Example 2 >>
In this example, an external manifold fuel cell was manufactured in the same manner as in Example 1, except that the viscosity of the phenol resin solution was changed in various ways. Then, before performing the battery test, a gas seal test was performed. As a result, when the phenol resin solution to be applied was too thick and the viscosity was too high, the sealing property was deteriorated.
As a result of performing a battery test of the module under the same conditions as in Example 1, 1080 W (30 A-36 V) was obtained. This value was higher than that of a conventional fuel cell using a spacer such as a PET sheet. It is considered that the reason for this is that, as shown in FIG. 8, since the electrode end is sealed from the outside, an electrode configuration having substantially the same area as the carbon separator plate can be realized.

Further, a test for starting and stopping simultaneously with a heat cycle from room temperature to 80 ° C. was performed on the laminated battery 10 times continuously. As a result, no gas leak from the external manifold seal portion was detected, and it was found that even when creep occurred in the thickness direction of the laminated battery, the sealability of the external manifold could be maintained.
As shown in this example, sealing the stacked batteries from the outside was extremely effective in reducing the size of the batteries.
Further, the method of manufacturing a laminated battery carried out through Example 1 described above, that is, a method of laminating battery constituent members in a predetermined order, fixing them with end plates or the like, and then arranging a sealing material on a side surface, is a method of manufacturing the battery constituent members. While stacking, the man-hour was reduced dramatically compared to the method of sequentially arranging the sealing material on the side surface.

<< Example 3 >>
In order to put a polymer electrolyte fuel cell into practical use, reliability against various impact forces and thermal strain due to heat cycles is required. Therefore, in this example, the following battery was manufactured.
A laminated battery was produced in the same manner as in Example 1. Then, instead of sealing the side surface with a phenol resin, it was sealed with a polyisobutylene rubber, and then a liquid crystal polymer as an engineering plastic was covered with a thickness of about 1 mm and solidified.

When the laminated battery prepared in Example 2 was dropped from a height of 1 m, the laminated structure was displaced, and gas leak occurred. In the battery manufactured in this example, the sealing portion was reinforced with engineering plastic, so that there was no gas leak even in a drop test from a height of 5 m.
Further, when the battery test was performed under the same conditions as in Example 1, it was 1080 W (30 A-36 V).

Further, the phenol resin of the sealing material used in Examples 1 and 2 has a certain degree of heat resistance, but becomes extremely hard after curing.
When the batteries produced in this example and Example 2 were subjected to 10 heat cycles between room temperature and 80 ° C., gas leakage from the sealing surface of the external manifold was not detected in Example 2, Cracks presumably due to thermal strain entered the sealing surface on the side of the battery, causing gas leakage and cooling water leakage.
The battery manufactured in this example used isobutylene rubber, which has elasticity as compared with the phenol resin, for the sealing surface, and was molded with engineering plastic from above. Therefore, the battery could withstand the above-mentioned heat cycle of 100 times or more.
Thus, by using two or more materials having different mechanical properties such as Young's modulus and tensile strength in combination with the sealing material, a laminated battery module having high mechanical strength and heat cycle durability could be manufactured. .

<< Example 4 >>
In long-term continuous operation of a polymer electrolyte fuel cell, a considerable fastening pressure must be constantly applied from both ends of the electrode. At this time, it becomes an obstacle that members such as the end plate and the fastening rod become long. Therefore, in this example, a fuel cell in which a gas seal portion on the side surface of the cell and an external manifold were joined with an adhesive was manufactured and evaluated.
The fastening pressure from the end plate fixed at the time of assembling the stacked battery was set to be as high as 10 kgf / cm ^2, and the sealing material on the side of the battery was formed using polyisobutylene rubber and engineering plastic in the same manner as in the battery of Example 3. An external manifold was constructed, and the gas seal surface was joined with a silicone rubber-based adhesive.
Then, after the adhesive was sufficiently solidified, the fastening rod was loosened to reduce the fastening pressure from the end plate. The other configuration was the same as that of the battery of Example 3 to produce the battery of this example.

When a drop test was performed on this battery, it was found that the battery could withstand a drop test of 5 m. Further, it was found that even when the fastening pressure from the end plate performed in the above process was reduced to 0.5 kgf / cm ² , the device could withstand a drop test of 5 m.
In this example, a stainless steel end plate having a thickness of 20 mm was used, but the same strength was obtained by using a stainless steel end plate having a thickness of 5 mm at a fastening pressure of 0.5 kgf / cm ² . The same effect was obtained by using a lighter material such as reinforced plastic instead of metal such as stainless steel.
The fastening pressure was set to 20 kgf / cm ² , the fastening rod was loosened, and the end plate was removed. Even in this state, the stacked battery module has sufficient mechanical strength in the fastened state, and it has been confirmed that a gas leak does not occur even in a drop test from 3 m.
By adopting the structure as in the present embodiment, the conventional end plate can be omitted, and a significant reduction in size and weight can be achieved.

<< Example 5 >>
A battery was manufactured in the same manner as in Example 4, except that the gas seal surface between the sealing material on the side surface of the battery and the external manifold was joined by ultrasonic welding.
When the same drop test as in Example 4 was performed on this battery, it was found that the battery could withstand a drop test of 5 m. Further, it was found that even when the fastening pressure from the end plate performed in the above process was reduced to 0.5 kgf / cm ² , the device could withstand a drop test of 5 m.

<< Example 6 >>
Using a polyisobutylene rubber and an engineering plastic, the side surface of the fuel cell produced in Reference Example 4 was integrally molded by injection molding.
When the same drop test as in Example 4 was performed on this battery, it was found that the battery could withstand a drop test of 5 m. Further, it was found that even when the fastening pressure from the end plate performed in the above process was reduced to 0.5 kgf / cm ² , the device could withstand a drop test of 5 m.

<< Example 7 >>
A carbon powder having a particle size of several microns or less was immersed in an aqueous chloroplatinic acid solution, and a platinum catalyst was supported on the surface of the carbon powder by a reduction treatment. At this time, the weight ratio of carbon to the supported platinum was 1: 1. Next, the carbon powder carrying platinum was dispersed in an alcohol solution of a polymer electrolyte to form a slurry.
On the other hand, carbon paper having a thickness of 400 μm serving as an electrode is impregnated with an aqueous dispersion of a fluororesin (NEOFLON ND1 manufactured by Daikin Industries, Ltd.), and then dried and heat-treated at 400 ° C. for 30 minutes. Water repellency was imparted. Next, the slurry containing carbon powder was uniformly applied to one surface of the water-repellent carbon paper to form a catalytic reaction layer, which was used as an electrode.

  The two carbon paper electrodes produced by the above-described method were stacked with the surface on which the catalyst layer was formed facing inward, sandwiching the solid polymer electrolyte membrane therebetween, and then dried. The above carbon paper electrode had a length and width of 10 cm, and was disposed at the center of an electrolyte membrane having a length and width of 12 cm. In order to prevent the supplied fuel gas from leaking or mixing with each other, a silicon rubber sheet having a thickness of about 350 μm is placed around the electrodes with a polymer electrolyte membrane interposed therebetween, and hot-pressed at 100 ° C. for 5 minutes. An MEA (electrode electrolyte membrane assembly) was obtained.

  As the metal plate for the separator, a SUS316 plate having a thickness of 0.3 mm is used, and a 5.6 mm pitch (groove width of about 2.8 mm) corrugated portion is formed in the central area of 10 cm × 9 cm by press working. did. At this time, the depth of the groove 29 (the height of the peak 3) was about 1 mm.

  As shown in FIG. 11A, manifold holes 28 for supplying and discharging hydrogen gas, cooling water, and air are provided on two opposing sides, respectively. FIG. 11B is a schematic enlarged view of a dashed-dotted line portion in FIG. As shown in FIG. 12A, the separator on the hydrogen side was provided with a groove 29 for guiding gas by a rib 31 made of a phenol resin, from the manifold hole to the gas flow groove formed by processing a metal plate. In addition, a rib 31 made of phenol resin is provided so that the two grooves are adjacent to each other and are curved and connected.

  The projection made of phenolic resin had a thickness of about 1 mm and was the same as the height of the groove of the metal plate. A gasket corresponding to the shape of the metal plate is formed in the same manner on the outer peripheral portion of the SUS316 metal plate and around the manifold hole. In the separator on the air side, as shown in FIG. 12B, six adjacent grooves are curved to form a continuous gas flow groove. The structure is changed between the air side and the hydrogen gas side because the gas flow rate differs between the air side and the hydrogen gas side by about 25 times. Conversely, in such a structure, it is possible to obtain the optimum gas flow velocity and gas pressure loss by changing the shape of the resin gas flow groove according to the gas flow rate.

  In FIG. 13, the MEA 22 was sandwiched by these two types of separators and gaskets to form a structural unit of the battery. As shown in FIG. 13, the positions of the hydrogen gas flow grooves 33 and the air flow grooves 34 were configured to correspond to each other so that excessive shearing force was not applied to the electrodes. A cooling unit 35 for flowing cooling water was provided for every two unit batteries. A metal mesh 7 made of SUS316 was used for the cooling section to ensure conductivity and cooling water flow, and a gasket 19 made of phenol resin was provided on the outer peripheral portion and the gas manifold portion to form a seal portion. Grease 36 is applied thinly to portions requiring gas sealing, such as gaskets and MEAs, metal plates and metal plates, and gaskets and metal plates, so that the sealing properties are secured without significantly lowering the conductivity.

After laminating 50 cells of the above-mentioned MEA, the MEA was fastened to a stainless steel veneer with a fastening rod at a pressure of 20 kgf / cm ² via a current collecting plate and an insulating plate. If the fastening pressure is too small, gas will leak and the contact resistance will be large, so the battery performance will be low.On the other hand, if the fastening pressure is too large, the electrodes will be damaged or the stainless steel plate will be deformed. It was important to change the fastening pressure.
A performance test was performed on the polymer electrolyte fuel cell of this example manufactured by the above-described method by flowing hydrogen and air at a hydrogen utilization rate of 70% and an oxygen utilization rate of 20% as fuel gas. At this time, the battery temperature was 75 ° C., the humidification temperature on the hydrogen side was 80 ° C., and the humidification temperature on the air side was 75 ° C. As a result, a power output of 1050 W (35 V-30 A) was obtained.

  In this embodiment, the gas flow groove is constituted by a plurality of parallel straight lines. However, as shown in FIG. 14, a manifold hole for discharging gas from a manifold for supplying gas through two curved portions 37 is formed by the gas flow groove. Various structures are also possible, such as a structure for connecting a gasket or a structure for connecting a central manifold hole and an outer manifold hole with a gas flow groove like a snail shell.

<< Embodiment 8 >>
In the seventh embodiment, the gas flow grooves are formed using a phenol resin as a material having no gas permeability to the fuel gas. However, a carbon material or a rubber-like material which can be easily molded may be used. Therefore, in this example, a prototype was manufactured using a rubber-like material.

  An isobutylene rubber sheet having a thickness of about 1 mm was cut into the same shape as the phenolic resin gasket used in Example 7, and used as a separator together with a stainless steel plate. The phenolic gasket used in Example 7 required grease to be used in many seal portions, but in this example, grease was unnecessary except for the seal portions between the metal plates. In the case of a phenolic gasket, gas tends to leak from the seam (32 in FIG. 12) between the gas flow groove made of a metal plate and the gas flow groove made of a phenol resin. When a rubber sheet was used, almost no gas leak occurred in that portion.

As a result of trial production using a resin sheet such as a silicone rubber sheet or a Teflon (polyethylene fluoride fiber) sheet, a material that retains gas sealing properties when pressed against a metal surface at a pressure of 30 kgf / cm ² is: Generally, no gas leak occurred. In addition, if a gasket made of an isobutylene rubber sheet was fixed in advance with an adhesive and integrated with a SUS metal plate, assembly of the laminated battery could be performed easily.

  A performance test was performed on the polymer electrolyte fuel cell of this example manufactured by the above-described method by flowing hydrogen and air at a hydrogen utilization rate of 70% and an oxygen utilization rate of 20% as fuel gas. At this time, the battery temperature was 75 ° C., the humidification temperature on the hydrogen side was 80 ° C., and the humidification temperature on the air side was 75 ° C. As a result, a power output of 1040 W (35 V-30 A) was obtained.

<< Example 9 >>
In Examples 7 and 8, the gas flow grooves were formed in the center of one metal plate by press molding. However, even if the conditions of press molding changed even a little, warping and distortion occurred, and the processing yield was reduced. It was about 50%. Therefore, a trial experiment was conducted in which a metal plate requiring press forming and a flat metal plate for gas sealing were separated.
That is, a SUS316 plate having a thickness of 0.3 mm and a width of 9 cm was bent into a trapezoidal fin structure from one direction. The bending cycle was 5.6 mm (groove width 2.8 mm), the same as in Example 7. As shown in FIG. 15, the tip of the rubber-like rib 31 constituting the gas flow groove of the curved portion 37 is partially inserted into the back surface of the convex portion 30 of the SUS316 plate, so that the sealing property can be maintained.

  In addition, a rubber sheet 38 was inserted and closed on the back surface of the convex portion of the SUS316 plate, which is inconvenient for the passage of fuel gas. Thus, the same configuration as the separator of Example 7 was made possible. The results of the battery test were performed under the same conditions as in Example 7, and an output of 1020 W (34 V-30 A) was obtained with a battery in which 50 cells were stacked.

<< Example 10 >>
In the case where the gas flow grooves were formed in the center of the metal plate of Example 8 by press molding, warping and distortion occurred when the press molding conditions were changed even a little, and the processing yield was poor. Therefore, a method of press forming a metal plate as in Example 8 was studied.

First, the same trapezoidal fin structure as in Example 9 was obtained by bending or press molding. Next, the part except for the central part of 10 cm × 9 cm was flattened by pressing (〜500 kgf / cm ² ). Planarization was facilitated by raising the temperature. Finally, the manifold holes on both sides were opened. The processing of a metal plate by this method was very effective when using a material which is easily plastically deformed such as aluminum, but in that case, it was necessary to take measures against corrosion and the like.
The result of the battery test was performed under the same conditions as in Example 7, and an output of 1010 W (34 V-30 A) was obtained with a battery in which 50 cells were stacked.

<< Example 11 >>
In the above embodiment, either the air side or the hydrogen side gas flow groove is formed by forming a groove without cutting. In this embodiment, a method of using the grooves on both the front and back surfaces, which can be formed by a single groove formation, as the gas circulation grooves was studied.

  That is, as shown in FIG. 16, a groove was formed by press working so that the peripheral portion 39 of the SUS316 metal separator plate 4 had an intermediate height between the convex portion and the concave portion, and a manifold hole was formed. Further, as a rib, a rubber sheet 38 made of isobutylene rubber was set at the same height as the metal convex portion 30 and disposed on both the front and back surfaces, thereby forming gas circulation grooves similar to those in Examples 7 and 8 on the front and back surfaces. Also in this case, when the battery is configured as a stacked battery, the positions of the grooves correspond to the air side and the hydrogen gas side as shown in FIG. Correspondence of the position of this groove | channel was performed also in the cooling part 35 shown in FIG. The cooling unit had the same configuration as that of the seventh embodiment.

The result of the battery test was performed under the same conditions as in Example 7, and an output of 1050 W (34 V-31 A) was obtained from a battery in which 50 cells were stacked.
As described above, when the gas flow grooves are formed on both surfaces of one metal plate, the protrusions separating the adjacent grooves of the gas flow grooves on the hydrogen gas side form the gas flow grooves on the air side on the back surface, Since a configuration shared in the vertical direction can be adopted, the thickness per separator can be extremely reduced. Since the groove depth was 0.8 mm and the plate thickness was 0.3 mm, a 1.1 mm thick separator could be realized.

  Further, different materials can be used for the convex portion made of a non-metallic material forming the gas flow groove, the convex portion arranged at the peripheral end of the separator, and the convex portion forming the seal around the manifold hole. For example, when it is necessary to more precisely adjust the thickness of one cell, the peripheral end of the separator may be formed of phenol resin, and the other parts having strict sealing properties may be formed of silicon rubber.

  Although SUS316 was used here as the metal plate, it was effective to use SUS316L, SUS304, or another metal plate that is easier to process. Regarding durability, which is a concern, the voltage drop after continuous operation for 2,000 hours in SUS316L was about 2 V in a battery having 50 cells stacked.

  According to the present invention, a metal separator such as stainless steel can be used without cutting, so that the cost can be significantly reduced during mass production. In addition, the thickness of the separator can be further reduced, which contributes to the miniaturization of the laminated battery.

1 is a schematic perspective view of a polymer electrolyte fuel cell according to a reference example of the present invention. FIG. 2 is a partial schematic cross-sectional view showing the structure of a conventional polymer electrolyte fuel cell. FIG. 9 is a partial schematic cross-sectional view showing the structure of another conventional polymer electrolyte fuel cell. FIG. 10 is a partial schematic cross-sectional view showing the structure of another conventional polymer electrolyte fuel cell. FIG. 2 is a partially cutaway perspective view of an internal manifold type solid polymer fuel cell. It is a schematic plan view of the conventional metal separator plate. It is a schematic plan view of another conventional metal separator plate. FIG. 1 is a partial schematic cross-sectional view illustrating a structure of a polymer electrolyte fuel cell in an example of the present invention. FIG. 2 is a schematic exploded perspective view showing a configuration of a separator plate used in an example of the present invention. FIG. 1 is a partial schematic cross-sectional view illustrating a structure of a polymer electrolyte fuel cell in an example of the present invention. It is a schematic perspective view of the separator plate used in the Example of this invention. It is a schematic plan view of the separator plate used in the Example of this invention. FIG. 1 is a partial schematic cross-sectional view illustrating a structure of a polymer electrolyte fuel cell in an example of the present invention. It is a schematic plan view of the separator plate used in the Example of this invention. FIG. 2 is a schematic perspective view illustrating a structure of a separator used in an example of the present invention. FIG. 1 is a partial schematic cross-sectional view illustrating a structure of a polymer electrolyte fuel cell in an example of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Diffusion layer 2 Catalytic reaction layer 3 Electrolyte membrane 4 Separator plate 5 Gas flow path 6 Rib 7 Metal mesh 8 Manifold for gas 8 'Manifold for cooling water 9 Valley bent part 10 Mountain bent part 11 Phenolic resin 12 PET sheet 13 Hydrogen gas supply Discharge port 14 Air supply / discharge port 15 Cooling water supply / discharge port 16 Cooling water path 17 Seal material 18 O-ring 19, 27 Gasket 20 Seal part 21 Resin 22 Electrode electrolyte assembly (MEA)
23 Electrode 24 Cooling Channel 25 External Manifold 26 Screw 28 Manifold Hole 29 Groove 30 Convex Part 31 Rib 32 Rib-Protrusion Connection 33 Hydrogen Gas Flow Groove 34 Air Flow Port 35 Cooling Part 36 Grease 37 Curved Part 38 Rubber Sheet

Claims (5)

An electrode having a pair of catalytic reaction layers sandwiching a solid polymer electrolyte membrane, a means for supplying and distributing a fuel gas mixture containing hydrogen to one of the electrodes, and an oxidizing gas containing oxygen on the other surface of the electrode. A solid polymer electrolyte fuel cell in which a plurality of unit cells provided with a means for supplying and distributing are stacked via a conductive separator,
A solid polymer electrolyte fuel cell, wherein the separator is formed of a metal plate having a gas circulation groove, and the gas circulation groove and a means for supplying and distributing the fuel gas are connected by a gas-tight non-metallic material.   2. The solid polymer electrolyte fuel cell according to claim 1, wherein the gas flow grooves are formed of a plurality of linear grooves parallel to each other.   3. The solid polymer electrolyte fuel cell according to claim 2, wherein the gas flow groove formed on one surface of the metal plate forms a recess of the gas flow groove on the other surface of the metal plate.   The solid polymer electrolyte fuel cell according to any one of claims 1 to 3, wherein the separator comprises a plurality of metal plates, and has a gas flow groove on at least one entire surface of the metal plates.   When the gas-tight non-metallic material is pressed against the metal plate at a predetermined pressure or higher, a contact surface between the metal plate and the gas-tight non-metallic material has gas tightness with respect to the fuel gas. Item 5. The solid polymer electrolyte fuel cell according to any one of Items 1 to 4.

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