JP2012182064A - Fuel cell separator and fuel cell using the same - Google Patents

Abstract

An object of the present invention is to provide a separator capable of preventing impurities contained in a seal member from poisoning an electrode and preventing a decrease in voltage and a decrease in durability of a fuel cell, and a fuel cell using the separator.
A seal member 13 has a configuration in which a groove portion 9 is provided on a peripheral edge side of a portion where seal members 13 and 14 disposed between a separator and a membrane electrode assembly are disposed when viewed from the thickness direction of a separator. , 14 generates a propulsive force that flows from the sealing members 13 and 14 toward the groove 9, so that a large amount of impurities are discharged into the groove 9 and the amount of impurities flowing to the electrode side is reduced. Therefore, it can suppress that an electrode is poisoned by an impurity, the voltage fall by the cause of an impurity can be suppressed, and durability of a fuel cell can be improved.
[Selection] Figure 2

Description

  The present invention relates to a fuel cell separator that supplies and discharges a fuel gas to an anode and an oxidant gas to a cathode in a fuel cell that generates power using a fuel gas and an oxidant gas, and a fuel cell using the same.

  Fuel cells are highly reactive because they produce electricity and heat by reacting a fuel gas containing at least hydrogen and an oxidant gas containing at least oxygen, and directly or indirectly convert the chemical energy of the fuel into electrical energy. Power generation efficiency can be obtained.

  FIG. 16 shows a cross-sectional view of a conventional general fuel cell seal structure. An anode 102 and a cathode 103 are formed on both surfaces of an electrolyte membrane 101 constituting a membrane electrode assembly (MEA) of the fuel cell, respectively, and the fuel cell is formed on both sides of the anode 102 and the cathode 103, respectively. Separators 104 and 105 are disposed. The fuel gas and the oxidant gas are supplied to the anode 102 and the cathode 103 through gas flow paths formed in the separators 104 and 105, respectively. Further, a seal member 106 is disposed between the MEA and the separators 104 and 105 in order to prevent the fuel gas and the oxidant gas from being mixed into the gas flow paths and leaking to the outside.

  In the compounding agents or impurities contained in the seal member 106 disposed between the MEA and the separators 104 and 105, there may be a substance that adversely affects the MEA. When these substances that adversely affect the anode 102 and the cathode 103 (electrode) of the MEA, the power generation reaction is hindered, which may lead to a decrease in battery voltage and a decrease in durability of the fuel cell. Therefore, conventionally, a material that does not elute (or does not easily elute) impurities from the seal member is selected for the seal member, or a configuration that does not poison (or hardly poison) the electrode by impurities that elute from the seal member is applied. It was. As an example, a sealing member made of a material such as a fluorine-based resin that is generally difficult to elute impurities can be cited.

  For example, Patent Document 1 discloses a conventional gas diffusion layer by providing a protrusion on a part of a resin frame, piercing the protrusion into the gas diffusion layer, and filling the space in the plane of the resin frame in the direction perpendicular to the surface. It is disclosed that the sealing member filled so as to be in contact with can be removed.

  Moreover, a method for dissolving and removing eluted impurities in water vapor in the fuel cell and condensed water obtained by condensing the water vapor is disclosed (for example, see Patent Document 2).

JP 2009-170273 A JP 2003-217613 A

  However, the conventional method using a sealing member made of a material that does not easily elute impurities has a problem that sealing performance is insufficient and a problem that a sufficient cost reduction cannot be performed because the material is expensive. It was.

  Further, in a conventional method of removing a seal member by providing a protrusion on a part of a resin frame and piercing the protrusion into a gas diffusion layer to suppress the movement of the resin frame, Due to insufficient adhesion, there are problems that leaks occur and impurities are eluted from the filler disposed between the separator and the resin frame.

  Further, in the conventional method of dissolving and removing eluted impurities in water vapor in the fuel cell or condensed water obtained by condensing the water vapor, the impurities are removed when the impurities are insoluble in water. There was a problem that it was difficult and a problem that the fuel cell had to be cooled in order to condense water vapor.

  The present invention solves the above-described conventional problems, and suppresses the impurities contained in the seal member from poisoning the electrode, and can prevent a decrease in voltage and a decrease in durability of the fuel cell. It aims at providing the separator used for it.

  In order to achieve the above object, a fuel cell separator of the present invention comprises a membrane electrode assembly having an electrolyte membrane and a pair of electrodes disposed on both sides of the electrolyte membrane so as to expose the peripheral portion of the electrolyte membrane, A unit cell having a pair of separators disposed so as to sandwich a membrane electrode assembly, and a sealing member disposed between a peripheral portion of the electrolyte membrane and the separator and sealing a region where the electrode and the separator face each other A separator for a fuel cell used for a cell, which has a groove portion on a peripheral edge side from a portion where a seal member is disposed when viewed from the thickness direction of the separator.

  Further, the fuel cell of the present invention is a membrane electrode joint comprising the fuel cell separator of the present invention, an electrolyte membrane, and a pair of electrodes disposed on both surfaces of the electrolyte membrane so as to expose the peripheral edge of the electrolyte membrane. A fuel cell including one or more unit cells each having a body, a sealing member disposed between a peripheral portion of the electrolyte membrane and the separator and sealing a region where the electrode and the separator face each other.

  According to the fuel cell of the present invention and the separator used therefor, an impurity contained in the seal member poisons the electrode due to the presence of one or more grooves on the peripheral edge side of the separator in which the seal member is disposed. And the voltage drop caused by the impurities can be suppressed, and the durability of the fuel cell can be improved.

The top view of the separator in Embodiment 1 of this invention Sectional drawing along line AA of the unit cell of the fuel cell using the separator of FIG. Top view of the separator according to Embodiment 2 of the present invention Sectional drawing along line BB of the single battery cell of the fuel cell using the separator of FIG. Top view of the separator according to Embodiment 3 of the present invention The top view of the separator in which the groove part in Embodiment 3 of this invention has another shape The top view of the separator in Embodiment 4 of this invention The top view of the separator in which the groove part in Embodiment 4 of this invention has another shape The top view of the separator in Embodiment 5 of this invention The top view of the separator in Embodiment 6 of this invention The top view of the separator in Embodiment 7 of this invention The top view of the separator provided with the discharge part in Embodiment 7 of this invention The top view of the separator in Embodiment 8 of this invention The top view of the separator provided with the discharge part in Embodiment 8 of the present invention The top view of the separator in Embodiment 9 of this invention Longitudinal sectional view of a conventional separator

  1st invention is arrange | positioned so that a membrane electrode assembly which has an electrolyte membrane and a pair of electrode arrange | positioned on both surfaces of an electrolyte membrane so that the peripheral part of an electrolyte membrane may be exposed, and a membrane electrode assembly is pinched | interposed A separator for a fuel cell used for a unit cell having a pair of separators and a seal member disposed between a peripheral edge of the electrolyte membrane and the separator and sealing a region where the electrode and the separator face each other. Then, as viewed from the thickness direction of the separator, the groove portion is provided on the peripheral side from the portion where the seal member is disposed.

  According to this configuration, since the impurities generated from the seal member are discharged into the groove formed in the separator, the amount of the impurities generated from the seal member flowing to the electrode side that generates power is reduced. Thereby, it can suppress that an electrode is poisoned by an impurity, the voltage fall by the cause of an impurity can be suppressed, and durability of a fuel cell can be improved.

  According to a second invention, in the first invention, the distance from the seal member to the groove is shorter than the distance from the seal member to the electrode in a direction orthogonal to the thickness direction of the separator.

  According to this configuration, in the gap between the separator and the electrolyte membrane, a propulsive force is generated in which the impurity flows from the seal member toward the groove, so that the impurity flows more to the groove than to the electrode and flows to the electrode. Is reduced. Therefore, the durability of the fuel cell can be improved by suppressing the poisoning of the electrode and the voltage drop due to impurities.

  A third invention is characterized in that, in the first invention, the distance from the seal member to the groove is 0 in a direction orthogonal to the thickness direction of the separator. According to this configuration, it is possible to generate a driving force in which impurities flow from the seal member toward the groove, and it is possible to discharge the impurities from the groove.

  According to a fourth invention, in any one of the first to third inventions, the distance between the bottom surface of the groove and the surface of the electrolyte membrane is a distance between the separator surface and the surface of the electrolyte membrane in the region from the seal member to the end of the electrode. It is characterized by being larger than the interval. According to this configuration, it is possible to further increase the driving force for the impurities to flow from the seal member to the groove, and to discharge more impurities from the groove.

  A fifth invention is characterized in that, in any one of the first to fourth inventions, the separator has a seal groove in which a seal member is disposed, and one end of the groove portion is connected to the seal groove. To do. According to this configuration, impurities generated from the seal member can be efficiently moved to the groove portion, and electrode poisoning due to the impurities can be suppressed.

  A sixth invention is characterized in that, in the invention of the fifth invention, the other end of the groove portion is disposed below the one end connected to the seal groove in the direction of gravity. According to this configuration, by using the gravity, not only the impurities can be efficiently moved from the top to the bottom, but also the grooves and the communication grooves, and the backflow to the electrodes can be further prevented.

  A seventh invention is characterized in that, in any one of the first to sixth inventions, one end of the groove portion communicates with the outside of the end face of the peripheral portion of the separator. According to this configuration, the impurities generated from the seal member can be discharged to the outside, and the impurities are isolated outside the fuel cell system, so that the impurities can be prevented from flowing back to the fuel cell.

  An eighth invention is characterized in that, in any one of the first to seventh inventions, the groove portion has a continuous shape extending along the seal member and communicating outward from the end face of the peripheral edge portion of the separator. To do. According to this configuration, the shape of the groove can be simplified, and the area from which impurities can be discharged increases, so that impurities can be removed more efficiently and electrode poisoning due to impurities can be prevented.

  A ninth invention is characterized in that, in any one of the first to sixth inventions, any end of the groove is disposed on an inner side than an end face of a peripheral edge of the separator. According to this configuration, the impurity is isolated from the electrode and is confined in the groove without flowing back to the electrode, so that the outer surface of the fuel cell can be prevented from being contaminated by the impurity.

  According to a tenth aspect of the present invention, in any one of the first to sixth and ninth aspects, the groove portion extends along the seal member and has a continuous shape disposed on the inner side of the end surface of the peripheral edge portion of the separator. It is characterized by. According to this configuration, not only can the shape of the groove be simplified, but the area from which impurities can be discharged increases, so that impurities can be removed more efficiently and electrode poisoning due to impurities can be prevented.

  According to an eleventh aspect of the invention, in any one of the first to sixth, ninth, and tenth aspects, the separator communicates a plurality of groove portions and has a communication groove having a larger volume than the individual groove portions from an end surface of the peripheral edge portion of the separator. It is characterized by having inside. According to this configuration, since the impurity can be confined in the communication groove via the groove portion, the impurity can be held isolated from the electrode even when the amount is large.

  A twelfth invention is characterized in that in any one of the first to eleventh inventions, an impurity adsorbing member is provided which adsorbs impurities generated from a seal member which is disposed in the groove and enters the groove. According to this configuration, the impurities can be efficiently moved to the groove portion by the adsorption force of the impurity adsorption member, and are held by the impurity adsorption member, so that the impurities can be further prevented from flowing back to the electrode.

  A thirteenth invention is characterized in that in any one of the eleventh and twelfth inventions, there is provided an impurity adsorbing member that is arranged in the communication groove and adsorbs impurities generated from a seal member that enters the groove. . According to this configuration, the impurities can be efficiently moved to the communication groove by the adsorption force of the impurity adsorption member and are held by the impurity adsorption member, so that the impurities can be further prevented from flowing back to the electrode.

  A fourteenth invention is characterized in that, in any one of the first to thirteenth inventions, the seal member contains impurities generated from the seal member entering the groove portion. According to this configuration, it is possible to suppress poisoning of the electrode and voltage drop due to impurities, and to improve the durability of the fuel cell.

  A fifteenth invention includes the fuel cell separator according to any one of the first to fourteenth inventions, an electrolyte membrane, and a pair of electrodes disposed on both surfaces of the electrolyte membrane so as to expose a peripheral portion of the electrolyte membrane. A fuel cell including one or more unit cells each having a membrane electrode assembly and a sealing member that is disposed between a peripheral portion of the electrolyte membrane and the separator and seals a region where the electrode and the separator face each other. It is characterized by. According to this configuration, since the impurities are discharged into the groove, the amount flowing to the electrode side that generates power is reduced. As a result, electrode poisoning and voltage drop due to impurities can be suppressed, and the durability of the fuel cell can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same components as those of the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof will be omitted. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
A fuel cell is composed of a fuel cell stack formed by stacking a plurality of cells. FIG. 1 shows a configuration of a separator 1a according to Embodiment 1 of the present invention, and FIG. 2 shows a line AA (see FIG. 1) of one cell (single battery cell) of a fuel cell using the separator 1a. ) Is shown along the cross section. As shown in FIG. 2, the single battery cell includes an MEA (membrane electrode assembly), separators 1a and 1b arranged so as to sandwich the MEA, and a sealing member arranged between the MEA and the separators 1a and 1b. 13 and 14.

  First, the detailed configuration of the MEA will be described. As shown in FIG. 2, the MEA exposes the electrolyte membrane 10, the anode 11 disposed on one surface of the electrolyte membrane 10 so as to expose the peripheral portion of the electrolyte membrane, and also exposes the peripheral portion of the electrolyte membrane. And the cathode 12 disposed on the other surface of the electrolyte membrane 10.

  The electrolyte membrane 10 is made of a solid polymer electrolyte made of a perfluorocarbon sulfonic acid polymer having hydrogen ion conductivity, for example.

  The anode 11 and the cathode 12 were laminated on a catalyst layer made of a mixture of a catalyst in which a noble metal such as platinum is supported on porous carbon having high oxidation resistance and a polymer electrolyte having proton conductivity. It is comprised with the gas diffusion layer which has air permeability and electronic conductivity. As a general catalyst for the anode 11, a platinum-ruthenium alloy catalyst that suppresses poisoning by impurities (particularly carbon monoxide) contained in the fuel gas is used. As the gas diffusion layer, water-repellent carbon paper, carbon cloth, carbon non-woven fabric, or the like is used.

  Next, a detailed configuration of the separator 1 will be described. The separator 1 includes an anode side separator 1 a that supplies and discharges fuel gas to the anode 11 and a cathode side separator 1 b that supplies and discharges oxidant gas to the cathode 12. As shown in FIG. 2, in the single battery cell, the anode side separator 1a is disposed on the anode 11 side, and the cathode side separator 1b is disposed on the cathode 12 side so as to face each other.

  FIG. 1 shows an anode-side separator 1a. The anode separator 1a includes anode manifolds 2a and 2b, cathode manifolds 3a and 3b, cooling fluid manifolds 4a and 4b, a gas flow path 5, an anode seal groove 6, a cathode manifold seal groove 7, and a cooling fluid manifold. And a seal groove 8. The separator 1 is made of a conductive material such as carbon or metal.

  The anode manifolds 2a and 2b supply and discharge fuel gas to the anode 11, the cathode manifolds 3a and 3b supply and discharge oxidant gas to the cathode 12, and the cooling fluid manifolds 4a and 4b are generated simultaneously with power generation. Supply and discharge cooling fluid that heats and exchanges heat to cool the fuel cell.

  The gas flow path 5 includes a fuel gas flow path 5a and an oxidant gas flow path 5b. The fuel gas channel 5a is formed in the anode side separator 1a, and supplies and discharges the fuel gas to and from the anode 11 and the anode manifolds 2a and 2b. The oxidant gas flow path 5b is formed in the cathode side separator 1b, and supplies / discharges the oxidant gas to the cathode 12 and the cathode manifolds 3a and 3b. Further, a cooling fluid channel is formed in the anode side separator 1a or the cathode side separator 1b, and the cooling fluid channel supplies / discharges a cooling fluid for cooling the fuel cell.

  As shown in FIG. 1, the anode seal groove 6 is formed so as to surround the anode manifolds 2a and 2b and a portion (power generation portion) facing the anode 11 in the anode side separator 1a. Members 13 and 14 are arranged. Similarly, the cathode manifold seal groove 7 and the cooling fluid manifold seal groove 8 are formed around the cathode manifolds 3a and 3b and the cooling fluid manifolds 4a and 4b, respectively, and the seal members 13 and 14 are arranged. The

  Next, the sealing members 13 and 14 will be described. The seal members 13 and 14 are disposed in a seal groove between the peripheral edge of the electrolyte membrane 10 and the separators 1a and 1b. As shown in FIG. 2, on both surfaces of the electrolyte membrane 10, the anode seal member 13 is formed in the anode seal groove 6a formed in the anode side separator 1a, and the cathode seal member 14 is formed in the cathode side separator 1b. Each is disposed inside the cathode seal groove 6b. The anode seal member 13 seals the fuel gas by sealing the gap between the anode side separator 1a and the electrolyte membrane 10. Similarly, the cathode seal member 14 seals the gap between the cathode side separator 1b and the electrolyte membrane 10. To seal the oxidant gas. With such a configuration, mixing of fuel gas and oxidant gas and leakage to the outside are prevented. As these sealing members 13 and 14, rubber-like elastic bodies can be adopted, but the material is not particularly limited. Further, the seal members 13 and 14 include additives and softeners necessary for maintaining the function as a seal, and further, a plasticizer necessary for forming a seal shape by injection molding or the like, Additives, antioxidants, and these reactants and decomposition products remaining after molding are also included.

  These inclusions may contain impurities that are poisonous substances that inhibit the power generation reaction of the fuel cell, and these impurities may poison the electrodes and reduce power generation performance. In particular, an oily substance added as a softening agent to the sealing member may poison the anode 11 and the cathode 12 and cause a voltage drop in the fuel cell. The term “impurity” as used herein means a substance that inhibits the power generation reaction of the fuel cell, and refers to a compounding agent contained in the seal members 13 and 14 and impurities generated and mixed when forming the seal members 13 and 14. Point to.

  Next, the groove part 9 will be described. In the separators 1a and 1b, the groove portion 9 is formed on the peripheral side from the portion where the seal members 13 and 14 are disposed when viewed from the thickness direction of the separators 1a and 1b. The groove portion 9 allows impurities discharged from the seal members 13 and 14 disposed in the seal grooves 6a and 6b to enter the inside of the groove portion 9 and discharges the impurities to the outside of the separators 1a and 1b through the groove portion 9. Impurities contained in the sealing members 13 and 14 ooze out from the sealing members 13 and 14 and are then discharged into the groove portions 9 formed in the separators 1a and 1b. The discharge principle will be described later.

  Here, the principle of discharging impurities by the groove 9 will be described. As shown in FIG. 2, in the separators 1a and 1b according to the first embodiment, the distance d2 from the sealing members 13 and 14 to the grooves 9a and 9b is the distance d1 from the sealing members 13 and 14 to the anode 11 and the cathode 12. It is comprised so that it may become shorter. According to such a configuration, in the gaps between the seal members 13 and 14 and the anode 11, the cathode 12, and the grooves 9 a and 9 b, differences occur in capillary action, gravity, and intermolecular force that occur in the gaps. Propulsive force flows from the seal members 13 and 14 toward the grooves 9a and 9b. Therefore, more impurities flow to the groove portions 9a and 9b than to the anode 11 and cathode 12 side. Further, the distance t1 between the bottom surfaces of the grooves 9a and 9b and the surface of the electrolyte membrane 10 is such that the surfaces of the separators 1a and 1b and the surface of the electrolyte membrane 10 in the region from the seal members 13 and 14 to the ends of the anode 11 and cathode 12 This is also a factor that generates a propulsive force in which impurities flow from the seal members 13 and 14 to the grooves 9a and 9b.

  Further, by making the grooves 9a and 9b communicate with the outside, impurities generated from the seal members 13 and 14 can be discharged to the outside, and the impurities are isolated out of the fuel cell system, so that the impurities flow back to the fuel cell. Can be prevented.

  Next, the fuel cell stack and the reaction occurring there will be described. The fuel cell stack is formed by laminating a plurality of unit cells composed of the MEA and the separators 1a and 1b having the above-described configuration, disposing current collectors at both ends, disposing end plates via insulators, Created by fastening. A heat insulating material is disposed around the stack in order to prevent heat radiation to the outside and increase the exhaust heat recovery efficiency.

  Then, a fuel gas supply means for supplying a fuel gas containing hydrogen to the anode 11 side, an oxidant gas supply means for supplying air (oxidant gas) containing oxygen in the atmosphere to the cathode 12 side, and the stack are cooled. The cooling fluid supply means for supplying the cooling fluid that exchanges heat with the heat generated in the stack is connected. Thereby, a fuel cell power generation system in which a plurality of unit cells are stacked is completed.

  Here, the configuration of the fuel gas supply means will be described. The fuel gas supply means includes a desulfurization unit that removes a sulfur compound that becomes a catalyst poison contained as an odorant from a source gas such as city gas, a source gas supply unit that controls the flow rate of the desulfurized source gas, and a desulfurization unit. A reforming section for steam-reforming the raw material gas to produce a fuel gas containing hydrogen, a CO conversion section for modifying the carbon monoxide generated in the reforming section to reduce the concentration of carbon monoxide, and It is comprised with the CO removal part which selectively oxidizes and removes the carbon monoxide contained in fuel gas. Air in the atmosphere is supplied to the CO removal unit.

Here, for example, when methane is used as the raw material gas, the reaction shown in Chemical Formula 1 and Chemical Formula 2 occurs with water vapor in the reforming unit, and hydrogen is generated.

In addition, when all the reactions that occur in the reforming part are summarized, the reaction shown in Chemical Formula 3 is performed.

  However, the reformed gas generated in the reforming section contains about 10% carbon monoxide in addition to hydrogen. Carbon monoxide poisons the catalyst contained in the anode 11 in the operating temperature range of the fuel cell, and reduces its catalytic activity. Therefore, as shown in the reaction formula of Chemical Formula 2, carbon monoxide generated in the reforming section is converted to carbon dioxide in the CO conversion section. This reduces the concentration of carbon monoxide to about 5000 ppm.

Further, the carbon monoxide having a reduced concentration is selectively oxidized at the CO removal unit using oxygen taken from the atmosphere by the reaction represented by Chemical Formula 4. As a result, the concentration of carbon monoxide can be reduced to about 10 ppm or less that can suppress a decrease in the catalytic activity of the catalyst of the anode 11.

  Further, during power generation, air taken from the atmosphere is supplied to the anode 11, and about 1-2% of air is mixed with the hydrogen gas generated by the fuel gas supply means (air bleed), so that a slight amount of carbon monoxide remains. Can be further reduced.

  Next, the oxidant gas supply means will be described. The oxidant gas supply unit includes an oxidant gas flow rate control unit that controls the flow rate of the oxidant gas, an impurity removal unit that removes impurities in the oxidant gas, and a humidifier that humidifies the oxidant gas. .

  Here, the oxidant gas is a general term for gases containing at least oxygen (or capable of supplying oxygen). For example, the atmosphere (air) is used.

  Next, the cooling means will be described. The cooling means includes a cooling fluid tank that stores a cooling fluid that cools the stack, a cooling fluid pump that supplies the cooling fluid, a cooling fluid flow path, and a cooling fluid that exchanges heat with the heat generated in the fuel cell and further heat. It is comprised with the heat exchanger which exchanges and produces | generates hot water.

Next, an operation during power generation of the fuel cell power generation system using the separator having the above-described configuration will be described. First, fuel gas is supplied to the anode 11 and oxidant gas is supplied to the cathode 12, and a load is connected to the fuel cell. As a result, the hydrogen in the fuel gas emits electrons at the interface between the catalyst layer of the anode 11 and the electrolyte membrane 10 and becomes hydrogen ions, as shown in Chemical Formula 5.

The released hydrogen ions move to the cathode 12 through the electrolyte membrane 10 and receive electrons at the interface between the catalyst layer of the cathode 12 and the electrolyte membrane 10. At this time, it reacts with oxygen in the oxidant gas supplied to the cathode 12 to generate water as shown in Chemical Formula 6.

Summarizing the above reactions, the reaction shown in Chemical Formula 7 is carried out.

  The flow of electrons flowing through the load can be used as direct current electric energy. In addition, since the series of reactions described above is an exothermic reaction, the heat generated in the fuel cell is used as heat energy such as hot water by collecting and exchanging heat with the cooling fluid supplied from the cooling fluid flow path. be able to.

(Example)
Next, a confirmation test was performed on the behavior of the fuel cell in which impurities are contained in the seal members 13 and 14 during power generation. Specifically, a voltage detection means for detecting the battery voltage of the fuel cell was connected, and the following examples and comparative examples 1 and 2 were compared. As an example, the result of actually generating power in the fuel cell power generation system using the separator 1 in which the groove portion 9 of the first embodiment of the present invention is formed and measuring the cell voltage by the voltage detection means will be described. Further, in order to investigate the influence of impurities contained in the seal members 13 and 14 on the power generation performance, as a comparative example 1, a fuel cell power generation system equipped with a stack prepared using the separator 1 in which the groove 9 is not formed is mounted. Describe the measurement results. Similarly, as Comparative Example 2, a measurement result of a fuel cell power generation system equipped with a stack created using seal members 13 and 14 made of a fluororesin with less impurity elution is described.

At this time, the utilization rate of the fuel gas supplied to the anode 11 side was 70%, the dew point was about 55 ° C., the utilization rate of the oxidant gas supplied to the cathode 12 side was 50%, and the dew point was about 0 ° C. In order to make the flowing current constant, the load was controlled so that the current density was 0.2 A / cm ² with respect to the electrode areas of the anode 11 and the cathode 12. The flow rate of the cooling fluid for cooling the fuel cell was controlled to be about 60 ° C. near the fuel cell cooling fluid flow path inlet manifold and about 70 ° C. near the fuel cell cooling fluid flow path outlet manifold.

  First, the power generation performance of the fuel cell power generation system of the example was almost the same as that of the fuel cell power generation system of Comparative Example 2, and no significant voltage drop was observed.

  Next, the power generation performance of the fuel cell power generation system of Comparative Example 1 was lower than that of the fuel cell power generation system of the example, and the power generation efficiency was reduced.

  Here, the stack mounted on the fuel cell power generation system in which the power generation efficiency was lowered was disassembled, and the separator 1, the MEA, and the seal members 13 and 14 having no groove 9 were observed. As a result, it was found that oily mineral oil contained in the seal members 13 and 14 permeates the peripheral portions of the gas diffusion layers of the anode 11 and the cathode 12 constituting the MEA. If the oil-like mineral oil covers the gas diffusion layer, it becomes difficult for the fuel gas and the oxidant gas to diffuse, and the catalyst layer in the lower layer may be poisoned. From this, it can be inferred that the effective power generation area of the anode 11 and the cathode 12 is reduced due to the oily mineral oil which is an impurity, and that a voltage drop has occurred due to this.

  As described above, according to the separator of Embodiment 1 of the present invention and the fuel cell using the separator, by providing the plurality of groove portions 9 on the peripheral edge side from the portion where the seal members 13 and 14 are disposed, Since the propulsion force that the impurities generated from the members 13 and 14 flow from the seal members 13 and 14 toward the grooves 9a and 9b is generated, a large amount of impurities are discharged from the grooves 9a and 9b, and impurities are generated on the electrode side that generates power. The amount of flow is reduced. Further, the distance between the bottom surfaces of the grooves 9a and 9b and the surface of the electrolyte membrane 10 is such that the surfaces of the separators 1a and 1b and the surface of the electrolyte membrane 10 in the region from the sealing members 13 and 14 to the ends of the anode 11 and the cathode 12 The propulsive force is further increased because of the larger interval. By these things, it can suppress that an electrode is poisoned with an impurity, the voltage fall by the cause of an impurity can be suppressed, and durability of a fuel cell can be improved.

  Further, according to the separator of Embodiment 1 of the present invention and the fuel cell using the separator, even if the seal member contains a certain amount of impurities, the influence of the impurities can be reduced, and the seal of the seal member can be reduced. Impurities contained in the seal member poison the electrode with a very simple configuration in which the groove portion is provided in the seal groove without increasing the pressure loss of the fluid or cooling the temperature of the fuel cell while maintaining the properties. And the cost of the fuel cell power generation system can be reduced.

(Embodiment 2)
FIG. 3 shows a separator 1a according to Embodiment 2 of the present invention. FIG. 4 is a cross-sectional view taken along line BB (see FIG. 3) of the unit cell of the fuel cell using the separator 1a of the second embodiment. In the first embodiment, the separators 1a and 1b exist between the groove portions 9a and 9b and the seal grooves 6a and 6b. In the second embodiment, as shown in FIG. 3, the groove portions 9a and 9b There is no intermediate between the seal grooves 6a and 6b, and one ends of the groove portions 9a and 9b are connected to the seal grooves 6a and 6b. Since other components are the same as those in the first embodiment, description thereof is omitted.

  Here, the principle of discharging impurities by the grooves 9a and 9b will be described. In the first embodiment, the distance from the seal members 13 and 14 to the groove portions 9a and 9b is d2. In the second embodiment, one end of the groove portions 9a and 9b is connected to the seal grooves 6a and 6b. Therefore, d2 is 0. According to such a configuration, it is possible to generate a driving force in which impurities flow from the seal members 13 and 14 toward the grooves 9a and 9b, and the impurities easily flow into the grooves 9a and 9b.

  According to the separator of Embodiment 2 and the fuel cell using the separator, since one end of the groove portion 9 is connected to the seal groove 6, impurities generated from the seal members 13 and 14 are efficiently introduced into the groove portion 9. It can move and can suppress the poisoning of the electrode by an impurity.

(Embodiment 3)
FIG. 5 shows a separator 1a according to Embodiment 3 of the present invention. The separator 1a of the third embodiment is different from that of the second embodiment in that the groove 9 extends along the seal member and is continuous from the end surface of the peripheral edge of the separator 1a. Different. Since other components are the same as those in the first embodiment, the description thereof is omitted. Further, the cross-sectional view of the fuel cell using the separator 1a is also the same as that of the first embodiment, and is omitted.

  In the separator 1a according to the third embodiment, since the groove 9 is continuous along the seal member, the area where impurities can be discharged is larger than that in the second embodiment. Therefore, the amount of impurities discharged from the groove 9 increases.

  According to the separator of the third embodiment and the fuel cell using the same, the shape of the groove 9 can be further simplified than those of the first and second embodiments, and the area where impurities can be discharged increases, so that the impurities can be more efficiently produced. The electrode can be prevented from being poisoned by impurities.

  Moreover, as shown in FIG. 6, the structure by which the groove part 9 is arrange | positioned over the perimeter of the seal groove 6 may be sufficient. In this case, the same effect as the separator 1a of FIG.

(Embodiment 4)
As shown in FIG. 7, in the separator 1a according to the fourth embodiment of the present invention, a groove 9 for discharging impurities to the outside is formed inside the end surface of the peripheral edge of the separator 1a, and the seal groove 6 It is different from the first embodiment in that it is not connected, that is, any end of the groove 9 is arranged on the inner side of the end face of the peripheral edge of the separator 1a. Since other components are the same as those in the first embodiment, the description thereof is omitted.

  Here, as shown in FIG. 8, the groove portion 9 of the fourth embodiment may be formed integrally and continuously along the end surface.

  According to the separator of the fourth embodiment and the fuel cell using the same, any end of the groove 9 is disposed inside the end face of the peripheral edge of the separator 1a. Is isolated and is confined in the groove without flowing back to the anode 11 or the cathode 12, so that the outer surface of the fuel cell can be prevented from being contaminated by impurities.

  In addition, by making the entire volume of the groove 9 sufficient to retain impurities, the impurities can be retained and retained inside the groove 9 without leaking outside, so that the outside of the fuel cell is contaminated by impurities. Can be prevented.

(Embodiment 5)
As shown in FIG. 9, the separator 1a according to the fifth embodiment of the present invention has one end of the groove portion 9 connected to the seal groove 6 and the other end formed inside the end surface of the peripheral edge of the separator 1a. This is different from the first embodiment. Since other components are the same as those in the first embodiment, the description thereof is omitted.

  According to the separator of the fifth embodiment and the fuel cell using the same, any end of the groove 9 is disposed on the inner side of the end face of the peripheral edge of the separator 1a, so that the impurities are the anode 11 and the cathode 12. Is isolated and is confined in the groove 9 without flowing back to the anode 11 or the cathode 12, so that the outer surface of the fuel cell can be prevented from being contaminated by impurities generated from the seal member.

  In addition, since one end of the groove 9 is connected to the seal groove 6, impurities generated from the seal member can be efficiently moved to the groove 9, thereby further suppressing electrode poisoning due to the impurities. it can.

(Embodiment 6)
As shown in FIG. 10, the separator 1 a according to the sixth embodiment of the present invention has a continuous shape in which the groove portion 9 extends along the seal member and is arranged on the inner side of the end surface of the peripheral portion of the separator 1 a. It is different from the first embodiment in that it is arranged. Since other components are the same as those in the first embodiment, the description thereof is omitted.

  According to the separator of Embodiment 6 and the fuel cell using the separator, not only can the shape of the groove 9 be simplified, but the area from which impurities can be discharged increases, so that impurities can be removed more efficiently. Electrode poisoning due to impurities can be prevented.

  Further, by setting the entire volume of the groove 9 to a volume sufficient to retain the impurities, the impurities can be retained and retained inside the groove 9 without leaking outside, so that the outside of the fuel cell is contaminated by the impurities. Can be prevented.

(Embodiment 7)
In the present embodiment, the separator 1a has a communication groove for accumulating impurities. Hereinafter, the buffer unit 15 as an example of the communication groove will be described. As shown in FIG. 11, the separator 1 a according to the seventh embodiment of the present invention includes a buffer portion 15 that communicates a plurality of groove portions 9 and has a larger volume than each groove portion 9, and one end of the groove portion 9 is The embodiment is different from the first embodiment in that it communicates with the buffer portion 15 disposed on the inner side of the end face of the peripheral portion of the separator 1a. Since other components are the same as those in the first embodiment, the description thereof is omitted.

  According to the separator of Embodiment 7 and the fuel cell using the separator, since the impurities can be confined in the buffer part 15 via the groove part 9, even if the amount is large, the impurities are separated from the anode 11 and the cathode 12. Can be kept isolated.

  Here, the capacity of the buffer unit 15 was set to a capacity sufficient to retain impurities. In this way, by setting the volume of the entire buffer unit 15 to a volume sufficient to retain the impurities, the impurities are retained and held inside the buffer unit 15 without leaking to the outside. It is possible to prevent contamination by impurities.

  Further, as shown in FIG. 12, in order to discharge impurities accumulated in the buffer unit 15 to the outside, a discharge unit 16 communicating with the outside may be provided at the end of the buffer unit 15. By providing the discharge part 16, it is possible to isolate impurities out of the fuel cell system and prevent them from flowing back to the fuel cell.

(Embodiment 8)
FIG. 13 is a top view of the direction of gravity. As shown in FIG. 13, the separator 1 a according to the eighth embodiment of the present invention is different from the first embodiment in that the other end of the groove portion 9 is disposed below the one end connected to the seal groove 6 in the gravity direction. Is different. Since other components are the same as those in the first embodiment, the description thereof is omitted.

  According to the separator of the eighth embodiment and the fuel cell using the separator, not only the impurities can be efficiently moved from the top to the bottom and efficiently into the groove 9 and the buffer 15 by using gravity. Back flow to the anode 11 and the cathode 12 can be further prevented.

  Further, as shown in FIG. 14, a discharge portion 16 may be provided at the end of the buffer portion 15 in order to discharge impurities accumulated in the buffer portion 15 to the outside. By providing the discharge part 16, it is possible to further isolate impurities from the fuel cell system and prevent them from flowing back to the fuel cell.

(Embodiment 9)
The separator 1a according to the ninth embodiment of the present invention is different from the first embodiment in that an impurity adsorbing member 17 is disposed in the groove portion 9 and the buffer portion 15 as shown in FIG. Since other components are the same as those in the first embodiment, the description thereof is omitted.

  Here, the material of the impurity adsorbing member 17 is not particularly limited, and is preferably optimized according to the impurity to be removed. For example, when the impurity to be removed is an oily substance, a member containing an oil absorbing agent. Is preferably used.

  The impurity adsorbing member 17 may be disposed only in a part of the groove 9 or the buffer part 15, and may be a part of the groove 9 or the buffer part 15 in the thickness direction. The impurity adsorbing member 17 is preferably set to have a thickness according to the estimated impurity discharge amount, and the shape is preferably a sheet.

  According to the separator of Embodiment 9 of the present invention and the fuel cell using the separator, the impurities can be efficiently moved to the groove 9 or the buffer portion 15 by the adsorption force of the impurity adsorption member 17 and also retained by the impurity adsorption member 17. Therefore, it is possible to further prevent the impurities from flowing back to the anode 11 and the cathode 12.

  In addition, this invention is not limited to the above-mentioned structure, It can implement in another various aspect. For example, the depth of the groove 9 may be shallower or deeper than the depth of the seal groove 6, and even in this case, the same effect can be exhibited.

  It is to be noted that, by appropriately combining arbitrary embodiments of the various embodiments described above, the effects possessed by them can be produced.

  As described above, the separator according to the present invention and the fuel cell using the separator can be applied to uses such as a fuel cell, a fuel cell device, and a fuel cell power generation system using a sealing member containing impurities.

DESCRIPTION OF SYMBOLS 1 Separator 2a, 2b Anode manifold 3a, 3b Cathode manifold 4a, 4b Cooling fluid manifold 5 Gas flow path 6, 7, 8 Seal groove 9 Groove part 10 Electrolyte membrane 11 Anode 12 Cathode 13, 14 Seal member 15 Buffer part 16 Exhaust part 17 Impurity adsorption member

Claims (15)

A membrane electrode assembly having an electrolyte membrane and a pair of electrodes disposed on both sides of the electrolyte membrane so as to expose a peripheral portion of the electrolyte membrane;
A pair of separators arranged so as to sandwich the membrane electrode assembly;
A separator for a fuel cell used in a unit cell having a seal member disposed between a peripheral portion of an electrolyte membrane and a separator and sealing a region where the electrode and the separator face each other,
A separator for a fuel cell, which has a groove portion on a peripheral side from a portion where a seal member is disposed when viewed from the thickness direction of the separator.   2. The fuel cell separator according to claim 1, wherein a distance from the seal member to the groove is shorter than a distance from the seal member to the electrode in a direction orthogonal to the thickness direction of the separator.   2. The fuel cell separator according to claim 1, wherein a distance from the seal member to the groove is 0 in a direction orthogonal to the thickness direction of the separator.   The distance between the bottom surface of the groove and the surface of the electrolyte membrane is larger than the distance between the separator surface and the surface of the electrolyte membrane in the region from the seal member to the end of the electrode. Fuel cell separator.   The separator for a fuel cell according to any one of claims 1 to 4, wherein the separator has a seal groove in which a seal member is disposed, and one end of the groove portion is connected to the seal groove.   The fuel cell separator according to claim 5, wherein the other end of the groove portion is disposed below the one end connected to the seal groove in the direction of gravity.   The separator for a fuel cell according to any one of claims 1 to 6, wherein one end of the groove portion communicates with an outer side from an end face of a peripheral portion of the separator.   The fuel cell separator according to any one of claims 1 to 7, wherein the groove portion has a continuous shape extending along the seal member and communicating outward from the end surface of the peripheral portion of the separator.   The fuel cell separator according to any one of claims 1 to 6, wherein any end portion of the groove portion is disposed on an inner side than an end face of a peripheral portion of the separator.   10. The fuel cell separator according to claim 1, wherein the groove portion has a continuous shape extending along the seal member and disposed on the inner side of the end surface of the peripheral portion of the separator. .   11. The separator according to claim 1, wherein the separator has a communication groove that communicates with the plurality of groove portions and has a volume larger than that of each groove portion on the inner side of the end surface of the peripheral edge portion of the separator. Fuel cell separator.   The fuel cell separator according to any one of claims 1 to 11, further comprising an impurity adsorbing member that is disposed in the groove and adsorbs impurities generated from a seal member that enters the groove.   The fuel cell separator according to claim 11 or 12, further comprising an impurity adsorbing member that is disposed in the communication groove and adsorbs impurities generated from a seal member that enters the groove.   The fuel cell separator according to any one of claims 1 to 13, wherein the seal member includes impurities generated from the seal member that enters the groove. A fuel cell separator according to any one of claims 1 to 14,
A membrane electrode assembly having an electrolyte membrane and a pair of electrodes disposed on both sides of the electrolyte membrane so as to expose a peripheral portion of the electrolyte membrane;
A fuel cell including one or more unit cells each having a sealing member disposed between a peripheral portion of an electrolyte membrane and a separator and sealing a region where the electrode and the separator face each other.

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