JP2008098181A - Solid polymer electrolyte fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid polymer electrolyte fuel cell system which prevents drying of a solid polymer electrolyte membrane even if the amount of water vapor in reactant gas to be fed is small in a non-humidifying operation, etc., by circulating water generated by an oxidant electrode within the cell without sacrificing not only the property of the cell but also the simplification and compaction of the system, to realize the excellent performance and the superior compactness, and reliably provides the actuation within a short time even if the ambient temperature is as low as not more than 0°C. <P>SOLUTION: The polymer electrolyte fuel cell system comprises a main cell body with a cell stack. The cell stack is constituted by a plurality of cells, each of which has a polymer electrolyte membrane, stacked with separators and cooling plates being selectively interposed therebetween. Each of the separators includes gas supply means for enabling two types of reactant gas to take place in counterflow with respect to each other, and each of the cooling plates includes coolant flow grooves. The coolant upstream side of the flow groove is disposed at inlet/outlet portions of the two types of reactant gas in the separator. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid polymer fuel cell system using a solid polymer as an electrolyte, and more particularly to a solid polymer fuel cell system having a mechanism for preventing drying of a solid polymer electrolyte membrane.

  The fuel cell system directly converts the chemical energy of the fuel into electric energy by electrochemically reacting a fuel gas such as hydrogen, which is a reaction gas, and an oxidant gas such as air.

  Such fuel cell systems are classified into various types depending on the difference in electrolytes, and one of them is a solid polymer fuel cell system using a solid polymer electrolyte membrane as an electrolyte. ing.

  FIG. 1 is a cross-sectional view showing a configuration example of this type of polymer electrolyte fuel cell system.

  In FIG. 1, a cell 4 includes a catalyst layer made of Pt or the like between a pair of gas diffusion electrodes made up of a fuel electrode (hereinafter referred to as an anode electrode) 1a and an oxidant electrode (hereinafter referred to as a cathode electrode) 1b. A solid polymer electrolyte membrane 3 having ion conductivity and gas separation function is sandwiched between 2a and 2b. The unit cell 4 generates electric power by generating an electric power by an electrochemical reaction between a fuel gas, which is a reaction gas, and an oxidant gas.

  The fuel cell system includes a unit cell 4 and a gas-impermeable separator 5 having a groove for supplying a reaction gas to each electrode of the unit cell 4.

  In such a fuel cell system, when a fuel gas such as hydrogen is supplied to the anode electrode 1a and an oxidant gas such as air is supplied to the cathode electrode 1b, an electromotive force is generated in the unit cell 4 by an electrochemical reaction. The electromotive force of the unit cell 4 is as low as about 1V at most. For this reason, in order to obtain a high output, a battery stack in which a plurality of single cells 4 are stacked is usually put to practical use as a fuel cell system.

  Since the electrochemical reaction in this fuel cell system is an exothermic reaction, it generates heat. In order to remove this excess heat, a cooling plate 7 in which a refrigerant is circulated is inserted into each unit cell stack 6 in which a plurality of unit cells 4 are stacked via separators 5.

  Further, if a gas leak occurs outside the system, there is a risk of a decrease in gas utilization rate or an explosion due to a combustible gas such as hydrogen. Therefore, a sealing material 8 is used between the solid polymer electrolyte membrane 3 and the separator 5. Gas sealed.

  Furthermore, water is generated in the cathode electrode 1b with the electrode reaction. When this water condenses in the electrode reaction part, gas diffusibility deteriorates, so this water is discharged out of the battery together with the unreacted gas.

  On the other hand, as the solid polymer electrolyte membrane 3, for example, a perfluorosulfonic acid membrane, which is a fluorine-based ion exchange membrane, is known. This solid polymer electrolyte membrane 3 has a hydrogen ion exchange group in the molecule. By functioning as saturated water, it functions as an ion conductive substance.

  However, when the solid polymer electrolyte membrane 3 is dried, the ionic conductivity is deteriorated and the battery performance is remarkably lowered. Therefore, various methods for preventing the solid polymer electrolyte membrane 3 from being dried are known. .

  For example, there is a technique in which a humidifier having a structure in which water and a reactive gas are circulated is provided on both surfaces of a water vapor permeable membrane such as the solid polymer electrolyte membrane 3 and the reactive gas is humidified and supplied in advance.

  In this case, the humidifier is usually integrated with the battery stack. In addition, if the reaction gas supplied to the anode electrode 1a and the cathode electrode 1b is circulated so as to face each other, the operating temperature is set to 60 ° C. or lower, and the relative humidity of the reaction gas is increased, power can be generated without humidifying the reaction gas. It is also known that there is.

  On the other hand, as shown in Patent Document 1, there has been proposed a method of humidifying an unreacted gas by introducing an already reacted gas and an unreacted gas into gas chambers separated by a water vapor permeable membrane.

  In this case, since water vapor is generated on the cathode electrode 1b side with the electrode reaction, the already-reacted gas contains saturated or near water vapor.

  On the other hand, since the amount of water vapor contained in the unreacted gas is small, a difference in water vapor partial pressure occurs in each gas, and the concentration of water vapor can be diffused using this as a driving force.

  Further, as shown in Patent Right 2, a hollow fiber membrane is used as a water vapor permeable membrane, and an unreacted gas is supplied to the inside of the hollow fiber membrane, and an already reacted gas is supplied to the outer peripheral portion thereof, thereby humidifying. The thing of the structure to do is also proposed.

By using this hollow fiber membrane, the contact area between the already reacted gas and the unreacted gas can be increased, so that a compact humidifier with high humidifying efficiency can be provided. In addition, since a hollow fiber membrane is used, a configuration in which the membrane is incorporated into the gas manifold of the battery stack is made possible.
JP-A-6-132038 JP-A-8-273687

  However, in the conventional polymer electrolyte fuel cell system as described above, when the reaction gas is humidified by a humidifier or humidity exchange, the system becomes complicated and it becomes difficult to make the system compact. Various problems arise in a low temperature environment such as 0 ° C. or lower.

  In addition, in a humidifier with a structure in which water and reaction gas are circulated on both sides of the water vapor permeable membrane, freezing occurs in the water flow path when the outside air temperature decreases, causing the flow path to be blocked, and the film is broken due to volume expansion of ice. Or the separator 5 may be deformed.

  On the other hand, when performing a non-humidifying operation without using a humidifier, there is a problem in the long-term stability of the solid polymer electrolyte membrane 3 and battery characteristics. In addition to this problem, since the fuel is operated at 60 ° C. or lower, which is lower than the normal operating temperature of 70 to 90 ° C., a fuel gas containing CO in the fuel such as a reformed gas, the catalyst of the anode electrode 1a. As a result of CO poisoning, there is a problem that anode polarization is increased and battery characteristics are remarkably deteriorated.

  Furthermore, when humidification is performed by introducing the already reacted gas and the unreacted gas into the gas chambers separated by the water vapor permeable membrane, the moisture is moved only by the difference in water vapor partial pressure between the gases. For this reason, since the diffusion resistance of water vapor, such as the diffusion resistance due to the water vapor concentration gradient on the already reacted gas side, the diffusion resistance in the water vapor permeable membrane, and the diffusion resistance on the unreacted gas side is very large, a sufficient amount of humidification Was not obtained.

  In addition, when the battery stack and the humidifier are installed separately, a part of the water vapor in the already-reacted gas condenses in the piping for introducing the already-reacted gas discharged from the battery stack to the humidifier. There is a problem in that the water vapor partial pressure of the already-reacted gas supplied to the liquid is lowered, and the humidification performance is further lowered.

  On the other hand, when a hollow fiber membrane is used as the water vapor permeable membrane, the contact area can be increased, but the moisture is transferred only by the difference in water vapor partial pressure between the already reacted gas and the unreacted gas, so that sufficient humidification performance is obtained. I can't. Also, in this case, once water vapor is condensed in the hollow fiber membrane and liquid water is generated, it becomes difficult to discharge water at gas pressure due to capillary force. There is also the problem of reducing the overall efficiency.

  The object of the present invention is to circulate the water generated at the oxidizer electrode in the battery without sacrificing the battery performance and the simplification and compactness of the system. Even when the amount of water vapor is small, drying of the solid polymer electrolyte membrane is prevented, high performance and excellent compactness, and reliable start-up in a short time even at low temperatures where the ambient temperature is 0 ° C or less It is an object of the present invention to provide a polymer electrolyte fuel cell system that can be used.

In order to achieve the above object, the present invention includes a battery main body having a battery stack, and the battery stack is a solid polymer fuel cell system in which a plurality of single cells having a solid polymer electrolyte membrane are stacked. ,
The battery body is
A temperature / humidity exchanging means for contacting the already reacted gas that has passed through the battery stack and the unreacted gas before passing through the battery stack via a water-retaining porous body,
The temperature of the unreacted gas is set lower than the temperature of the already-reacted gas.

  According to the present invention, the low-temperature unreacted gas and the high-temperature pre-reacted gas are brought into contact with each other, thereby condensing water vapor contained in the pre-reacted gas in the water-retaining porous body. Due to the osmotic pressure inside the porous body, water penetrates to the vicinity of the interface contacting the unreacted gas. Therefore, since the partial pressure difference of water vapor at the interface in contact with the unreacted gas increases, the diffusion resistance of water vapor when the water vapor in the already reacted gas exchanges the temperature and humidity into the unreacted gas through the porous body is greatly reduced. be able to.

The present invention also includes a battery main body having a battery stack, and the battery stack is a solid polymer fuel obtained by laminating a plurality of unit cells each having a solid polymer electrolyte membrane through a separator and a cooling plate. In battery systems,
The separator is
Comprising gas supply means for allowing two systems of reaction gas to circulate so as to face each other;
The cooling plate is
A refrigerant flow groove is provided, and the upstream portion of the refrigerant in the flow groove is arranged at the inlet / outlet portion of the two systems of the reaction gas in the separator.

The present invention also includes a battery main body having a battery stack, and the battery stack is a solid polymer fuel obtained by laminating a plurality of unit cells each having a solid polymer electrolyte membrane through a separator and a cooling plate. In battery systems,
The separator is
Comprising gas supply means for allowing two systems of reaction gas to circulate so as to face each other;
The cooling plate is
A refrigerant flow groove is provided, and the interval between the flow grooves in the part corresponding to the inlet / outlet portion of the two systems of the reaction gas in the separator is set to be other than the inlet / outlet portion of the two systems of the reaction gas. It becomes narrower than the interval at the part.

The present invention also includes a battery main body having a battery stack, and the battery stack is a solid polymer fuel obtained by laminating a plurality of unit cells each having a solid polymer electrolyte membrane through a separator and a cooling plate. In battery systems,
The separator is
Gas supply means for circulating two systems of reaction gases so as to face each other;
It is arranged at the inlet / outlet part of each of the two systems of the reaction gas in the separator, and comprises a cooling means by heat radiation to the atmosphere.

  According to the present invention, the cooling efficiency is increased in the downstream portion of the reaction gas having a high water vapor partial pressure due to consumption of water and reaction gas generated at the oxidizer electrode in association with the electrode reaction. The surface located in the section becomes supersaturated and water is condensed. The water condensed on the surface of the fuel electrode or the oxidant downstream of the reactive gas is upstream of the reactive gas having a low partial pressure of water vapor at the oxidant or fuel electrode facing each other through the solid polymer film. Penetrates and evaporates. Therefore, the water vapor partial pressure in the upstream portion of the reaction gas can be increased.

Furthermore, the present invention includes a battery body having a battery stack, and the battery stack selects a plurality of single cells having a pair of gas diffusion electricity and solid polymer electrolyte membranes, each comprising a fuel electrode and an oxidizer electrode, and a separator and a cooling plate. In the polymer electrolyte fuel cell system formed by stacking,
The separator is
Gas supply means for circulating two systems of reaction gases so as to face each other;
A downstream portion of the reaction gas in the gas diffusion electrode is subjected to a hydrophilic treatment.

  In general, according to the present invention, the gas diffusion layer is subjected to water repellency treatment to prevent poor gas diffusion due to water in which the water vapor in the reaction gas is partially condensed, but the reaction gas downstream of the gas diffusion electrode. By subjecting the part to hydrophilic treatment, water condensed downstream of the reaction gas is trapped without being discharged. That is, the water trapped at the downstream part of the reaction gas at the fuel electrode or the oxidant electrode is transferred to the upstream part of the reaction gas having a low water vapor partial pressure at the oxidant electrode or the fuel electrode facing each other through the solid polymer electrolyte membrane. Penetrate and evaporate. Therefore, the water vapor partial pressure in the upstream portion of the reaction gas increases.

The present invention also includes a battery main body having a battery stack, the battery stack comprising a plurality of unit cells each having a pair of gas diffusion electricity and solid polymer electrolyte membranes comprising a fuel electrode and an oxidant electrode, and a separator and a cooling plate. In the polymer electrolyte fuel cell system formed by selectively interposing,
The separator is
Gas supply means for circulating two systems of reaction gases so as to face each other;
A catalyst layer is provided in a portion of the pair of gas diffusion electrodes excluding the downstream portion in the reaction gas flow path.

  According to the present invention as described above, the catalyst layer is not provided in the reaction gas downstream portion where the water vapor partial pressure is high due to the consumption of water and reaction gas generated at the oxidant electrode in association with the electrode reaction. The temperature is low because no reaction heat is generated. Therefore, since the reaction gas is cooled on the surface located in the downstream portion of the reaction gas, it becomes supersaturated and water is condensed. The water condensed on the surface of the fuel electrode or the oxidant downstream of the reactive gas is upstream of the reactive gas having a low partial pressure of water vapor at the oxidant or fuel electrode facing each other through the solid polymer film. Penetrates and evaporates. Therefore, the water vapor partial pressure in the upstream portion of the reaction gas can be increased.

Further, the present invention includes a battery main body having a battery stack, and the battery stack is a solid polymer fuel cell system in which a plurality of single cells having a solid polymer electrolyte membrane are stacked.
The battery body is
Temperature / humidity exchanging means for contacting the already reacted gas that has passed through the battery stack and the unreacted gas before passing through the battery stack through a water-retaining porous body;
A means for condensing water vapor contained in the already-reacted gas is provided on the porous body.

  According to the present invention as described above, by removing the water contained in the already-reacted gas, it is possible to prevent water from staying in the discharge line of the already-reacted gas, and for example, air in the vehicle is used as the low-temperature air. In some cases, the efficiency of the system can be improved because it can be used for heating in winter. Further, the condensed water can be used for steam reforming of the fuel reformer.

  As described above, the amount of water vapor in the reaction gas supplied in a non-humidified operation or the like by circulating the water generated at the oxidizer electrode in the battery without sacrificing the battery performance and the simplification and compactness of the system. Even when there is a small amount of water, the polymer electrolyte membrane is prevented from drying, high performance and compactness, and it is possible to start up reliably in a short time even at low temperatures where the ambient environment temperature is 0 ° C or less. It becomes.

  According to the polymer electrolyte fuel cell system of the present invention, the water generated in the oxidizer electrode is circulated in the battery without sacrificing the battery performance, the simplification and the compactness of the system, so that no humidification is achieved. Even when the amount of water vapor in the reaction gas supplied during operation is small, the polymer electrolyte membrane is prevented from drying, and it has high performance, excellent compactness, and the ambient temperature is 0 ° C or less. However, it is possible to start up reliably in a short time, and at the same time, it is possible to operate at a temperature higher than the battery temperature when the conventional non-humidified gas is supplied. A compact system with high performance can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 2A is a conceptual diagram showing the principle of humidity exchange of the humidity exchange unit in the polymer electrolyte fuel cell system according to the present embodiment, and FIG. 2B is a configuration example of the cell stack and humidity exchange unit in the polymer electrolyte fuel cell system. FIG. 3A and FIG. 3B are exploded views showing the same humidity exchanging unit. The same parts as those in FIG. 1 are denoted by the same reference numerals, the description thereof is omitted, and only different parts are described here.

  2A, the polymer electrolyte fuel cell system of this embodiment includes a battery stack 9 and a humidity exchanging unit 10. Here, the high-temperature unreacted gas 100 discharged from the battery stack 9 is guided to the humidity exchanging unit 10 and passes through the gas groove 12 (12a, 12b) and the low-temperature unreacted gas 101 via the porous body 14. Contact with. As a result, water vapor contained in the already-reacted gas 100 is condensed in the porous body 14, penetrates into the unreacted gas 101 side, and evaporates with a partial pressure difference, thereby humidifying the unreacted gas 101. Here, the humidity exchanging unit 10 can be disposed in contact with the battery stack 9 or can be disposed separately. In FIG. 2A, for convenience of explanation, the two are illustrated as being separated from each other, but in the present embodiment, both are disposed in contact with each other.

  2B, in the polymer electrolyte fuel cell system, the battery unit 9 and the temperature / humidity exchange unit 10 are integrated by disposing the humidity exchange unit 10 in contact with the battery stack 9.

  Further, as shown in FIG. 3A, the temperature / humidity exchange unit 10 includes a carbon separator 5 having a gas groove 11a or 11b through which the unreacted gas 101 of the anode electrode 1a or the cathode electrode 1b before passing through the battery stack flows. And a carbon separator 5 having a gas groove 12a or 12b through which the reacted gas 100 of the anodic electrode 1a or the cathode electrode 1b that has passed through the battery stack circulates, and a water-retaining porous body through a sealing material 8 14 is sandwiched.

  Here, as the porous body 14, a porous body is used in which a thin film having a pore size of 1 μm or less is attached to the surface of a nonwoven fabric subjected to hydrophilic treatment. In addition to this, as the porous body 14, for example, a carbon plate subjected to hydrophilic treatment, a sintered metal, a fluorine-based ion exchange membrane, a polymer layer on a fluorine-based porous membrane and a fibrous layer Various materials can be applied such as the composite film.

  The necessary functions here are that water in which water vapor contained in the already-reacted gas is condensed can be retained in the porous body 14, and the condensed water passes through the porous body 14 by osmotic pressure, and water vapor on the surface on the unreacted gas side. It is possible to evaporate due to the difference in partial pressure, and the permeability of gases other than water vapor is small.

  2B and 3A, the separator 5 includes an anode reaction gas inlet manifold 15a, an anode electrode reaction gas outlet manifold 15b, a cathode electrode reaction gas inlet manifold 15c, and a cathode electrode reaction gas outlet manifold 15d. A cooling water inlet manifold 15c and a cooling water outlet manifold 15f are provided.

  In the polymer electrolyte fuel cell system according to the present embodiment configured as described above, the temperature / humidity exchange unit 10 exchanges the temperature / humidity between the already-reacted gas 100 and the reaction gas 101, whereby the battery stack 9 is Since the water vapor contained in the passed high-temperature reacted gas 100 is condensed by the low-temperature unreacted gas 101, the vicinity of the interface of the porous body 14 in contact with the already-reacted gas 100 is covered with water. The condensed water permeates to the vicinity of the interface in contact with the unreacted gas 101 due to the osmotic pressure inside the porous body 14. Therefore, the diffusion resistance of water vapor when the water vapor in the unreacted gas 101 exchanges the temperature and humidity into the unreacted gas 101 through the porous body can be greatly reduced.

  Furthermore, since the temperature / humidity exchange unit 10 is arranged so as to be in contact with the battery stack 9, a conventional pipe for introducing the already-reacted gas 101 into a humidifier (not shown) can be omitted. For this reason, not only a compact system is possible, but also condensation of water vapor in the existing reaction gas due to heat dissipation loss in the piping part can be prevented, so that the amount of water vapor in the existing reaction gas 101 supplied to the temperature / humidity exchange unit 10 Can be prevented.

  FIG. 4 is a characteristic diagram showing the relationship between the area of the temperature / humidity exchange unit 10 and the relative humidity of the unreacted gas humidified by the humidity exchange. As shown in FIG. 4, the structure of the present embodiment allows the water vapor at the interface of the porous body 14 of the temperature / humidity exchanging portion 10 to be compared with a conventional humidification method in which water vapor permeates only by the difference in the water vapor partial pressure of the gas. Since the diffusion resistance of the water is reduced, the humidity exchange efficiency is greatly increased. Therefore, since the area of the temperature / humidity exchange unit 10 can be reduced, it is possible to reduce the size.

(Modification 1)
By providing the humidity exchanging unit 10 with a gas supply path in which the already reacted gas and the unreacted gas are opposed to each other through the porous body 14, a further compactness can be achieved.

(Modification 2)
As shown in FIG. 3B, by providing a groove 13c through which the refrigerant flows on the back surface of the separator 5, it is possible to further promote condensation of water vapor of the already-reacted gas, thereby further improving the humidity exchange efficiency. Improvements can be made.

  As described above, in the polymer electrolyte fuel cell system of the present embodiment, the water vapor of the already-reacted gas is condensed in the water-retaining porous body 14, so that the humidity exchange efficiency is improved and the size is reduced. Can be achieved.

  Further, since the already reacted gas and the unreacted gas are allowed to flow opposite to each other, it is possible to further reduce the size.

  Further, since the heat exchanging means is brought close to the humidity exchanging section 10, it is possible to further increase the condensation amount and further improve the humidity exchanging efficiency.

  The cooling means is not limited to the present embodiment, and the same effect can be obtained when a cooling passage through which a cooling medium such as an antifreeze liquid passes is provided in the vicinity of the porous body 14. Needless to say.

  As a result, the conventional humidification system using water has a problem of water freezing, but the solid polymer fuel cell system according to the present embodiment does not use water for humidification. In addition, it is possible to provide a highly reliable system that is free from the risk of freezing, film breakage, and deformation due to freezing, and it is possible to start up in a short time because no time is required for thawing ice.

(Second Embodiment)
FIG. 5 is an exploded view showing a configuration example of the polymer electrolyte fuel cell system according to the present embodiment, and FIG. 6 is a perspective view showing a configuration example of a single cell constituting a cell stack in the polymer electrolyte fuel cell system. is there. In addition, the arrow in a figure has shown the distribution direction of the reactive gas supplied to a battery.

  In FIG. 5, the unit cell 4 has ion conductivity and a gas separation function through a catalyst layer 2a, 2b made of Pt or the like between a pair of gas diffusion electrodes made up of an anode electrode 1a and a cathode electrode 1b. The solid polymer electrolyte membrane 3 is sandwiched. The unit cell 4 generates electric power by generating an electric power by an electrochemical reaction between a fuel gas, which is a reaction gas, and an oxidant gas. The unit cell 4 includes a gas-impermeable separator 5 having reaction gas grooves 13a and 13b for supplying a reaction gas to each electrode through a sealing material 8, and a cooling plate having a groove 13c through which a refrigerant flows. The groove 13c through which the refrigerant flows is arranged at the inlet / outlet portion of each reaction gas in the groove 13c through which the refrigerant flows.

  In addition, as shown in FIG. 6, the reaction gas supplied to the anode electrode 1 a and the cathode electrode 1 b is circulated through the unit cell 4 so as to face each other.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, the inlet of the cooling plate 7 is formed by the consumption of water and reaction gas generated at the cathode electrode 1b due to the electrode reaction. Since it arrange | positions in the reactive gas downstream part with high water vapor partial pressure, since the cooling efficiency with respect to the reactive gas downstream part becomes high, in the surface located in the reactive gas downstream part, it will become supersaturated and water will condense. The water condensed on the surface of the anode electrode 1a or the cathode electrode 1b located downstream of the reaction gas has a low water vapor partial pressure of the anode electrode 1a or the cathode electrode 1b facing each other through the solid polymer film 3. It permeates upstream of the reaction gas and evaporates. Therefore, the water vapor partial pressure in the upstream portion of the reaction gas can be increased.

  Furthermore, since the inlet of the cooling plate 7 is arranged in the downstream portion of the reaction gas, the relative humidity increases or the water condenses in the downstream portion of the reaction gas. Accordingly, the water vapor relative to the cathode electrode 1b or the anode electrode 1a facing each other through the solid polymer electrolyte membrane 3 from the downstream portion of the reaction gas having a relatively high water vapor partial pressure of the anode electrode 1a or the cathode electrode 1b. The amount of water vapor that permeates to the upstream portion of the reaction gas having a low partial pressure can be increased.

  In addition, according to the present embodiment, it is confirmed that when non-humidified reaction gas is supplied, battery characteristics almost equivalent to those of the conventional battery can be obtained at 80 ° C., which is about 25 ° C. higher than the operating temperature of the conventional battery. I was able to. Moreover, since the operating temperature is higher than that of the conventional battery, the voltage drop due to CO poisoning could be improved.

  As described above, in the polymer electrolyte fuel cell system of the present embodiment, even if a reaction gas having a low relative humidity is supplied to the battery stack, the water vapor content of the reaction gas supplied to the battery stack by the humidity exchanging unit 10. Since the pressure increases, it is possible to obtain good battery characteristics without lowering the battery temperature even in a non-humidified operation.

  As a result, the use of a humidifier can reduce the size and cost, and at the same time, it can be operated at a temperature higher than the battery temperature when the conventional non-humidified gas is supplied. Can be suppressed.

(Third embodiment)
FIG. 7 is an exploded view showing a configuration example of the polymer electrolyte fuel cell system according to the present embodiment, and FIG. 8 is a perspective view showing a configuration example of a unit cell constituting a cell stack in the polymer electrolyte fuel cell system. is there. In addition, the arrow in a figure has shown the distribution direction of the reactive gas supplied to a battery.

  In FIG. 7, the unit cell 4 has an ion conductivity and a gas separation function through a catalyst layer 2a, 2b made of Pt or the like between a pair of gas diffusion electrodes made up of an anode electrode 1a and a cathode electrode 1b. The solid polymer electrolyte membrane 3 is sandwiched. The unit cell 4 generates electric power by generating an electric power by an electrochemical reaction between a fuel gas, which is a reaction gas, and an oxidant gas. This single cell 4 has a gas-impermeable separator 5 having reaction gas grooves 13a and 13b for supplying a reaction gas to each electrode through a sealing material 8, and a cooling having a groove 13c through which a refrigerant flows. A plurality of grooves 13c sandwiched between the plates 7 and in which the refrigerant flows in the cooling plate 7 are relatively narrow at the inlet / outlet portion of each reaction gas.

  Further, as shown in FIG. 8, in the unit cell 4, the reaction gases supplied to the anode electrode 1a and the cathode electrode 1b are circulated so as to face each other.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, the same operations and effects as in the case of the second embodiment described above can be obtained.

(Fourth embodiment)
FIG. 9 is a perspective view showing a configuration example of a cell stack in the polymer electrolyte fuel cell system according to the present embodiment, and arrows in the figure indicate the flow of wind by the cooling fan. FIG. 10 is a perspective view showing a configuration example of a unit cell constituting a battery stack in the solid polymer fuel cell system, and arrows in the figure indicate a flow direction of a reaction gas supplied to the battery.

  In FIG. 9, heat radiation fins 16 and cooling fans 17 are provided on the top and bottom surfaces of the battery stack 9 located at the inlet / outlet portion of the reaction gas. Thereby, the battery stack 9 is forcibly cooled.

  Also, as shown in FIG. 10, the reaction gases supplied to the anode electrode 1a and the cathode electrode 1b are circulated so as to face each other.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, the same operations and effects as those of the third embodiment described above can be obtained.

  In particular, when the cooling water is not used for cooling the battery unit, a system that does not use the cooling water can be realized, so that the convenience of handling can be improved.

(Fifth embodiment)
FIG. 11 is a cross-sectional view showing a configuration example of a unit cell constituting a battery stack in the polymer electrolyte fuel cell system according to the present embodiment, and arrows in the figure indicate a flow direction of a reaction gas supplied to the battery. ing.

  In FIG. 11, the unit cell 4 has ion conductivity and gas separation function via a catalyst layer 2a, 2b made of Pt or the like between a pair of gas diffusion electrodes made of an anode electrode 1a and a cathode electrode 1b. The solid polymer electrolyte membrane 3 having the structure is sandwiched. The anode electrode 1a and the cathode electrode 1b in the unit cell 4 are preliminarily coated with an ink made of carbon powder (Vulcan XC-72R), a surfactant, and pure water (solid content 67). %), A hydrophilic treatment section 25 dried at 120 ° C. is provided.

  Here, in the anode electrode 1a and the cathode electrode 1b, the gas diffusion layer is subjected to water repellent treatment other than the hydrophilic treatment portion 25 in order to prevent gas diffusion failure due to condensed water.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, the end of the gas diffusion electrode located downstream of the reaction gas is obtained by applying and impregnating the ink made of carbon. By performing the hydrophilic treatment, the condensed water is trapped without being discharged because the gas diffusion layer is subjected to the hydrophilic treatment downstream of the reaction gas. That is, the water trapped at the downstream portion of the reaction gas of the anode electrode 1a or the cathode electrode 1b has a low water vapor partial pressure of the cathode electrode 1b or the anode electrode 1a facing each other through the solid polymer electrolyte membrane 3. It permeates upstream of the reaction gas and evaporates. Therefore, the water vapor partial pressure in the upstream portion of the reaction gas increases.

  As described above, in the polymer electrolyte fuel cell system of the present embodiment, even if a reaction gas having a low relative humidity is supplied to the battery stack, the water vapor content of the reaction gas supplied to the battery stack by the humidity exchanging unit 10. Since the pressure increases, it is possible to obtain good battery characteristics without lowering the battery temperature even in a non-humidified operation.

  As a result, the use of a humidifier can reduce the size and cost, and at the same time, it can be operated at a temperature higher than the battery temperature when the conventional non-humidified gas is supplied. Can be suppressed.

  In the present embodiment, the same effect can be obtained by impregnating ink or solid polymer electrolyte solution using SiC, SiO2, TiO2, or SnO2 fine powder instead of carbon powder. it can.

(Sixth embodiment)
FIG. 12 is a cross-sectional view showing a configuration example of a unit cell constituting the battery stack in the polymer electrolyte fuel cell system according to the present embodiment, and the arrows in the figure indicate the flow direction of the reaction gas supplied to the battery. ing.

  In FIG. 12, the unit cell 4 has ion conductivity and gas separation function via a catalyst layer 2a, 2b made of Pt or the like between a pair of gas diffusion electrodes made up of an anode electrode 1a and a cathode electrode 1b. The solid polymer electrolyte membrane 3 is sandwiched. In the unit cell 4, the anode electrode 1a and the cathode electrode 1b are provided with a polymer electrolyte press-fitting portion 26 formed by hot pressing the solid polymer electrolyte membrane 3 in the vicinity of the glass transition temperature at a portion located downstream of the reaction gas. Provided.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, the end portion of the gas diffusion electrode located downstream of the reaction gas is subjected to a hydrophilic treatment at the position where the solid polymer electrolyte membrane 3 is press-fitted. As a result, the condensed water is trapped without being discharged. That is, the water trapped in the downstream portion of the reaction gas of the anode electrode 1a or the cathode electrode 1b is the reaction gas having a low partial pressure of water vapor of the cathode electrode 1b or the anode electrode 1a facing each other through the solid polymer electrolyte membrane 3. It penetrates upstream and evaporates. Therefore, the water vapor partial pressure in the upstream portion of the reaction gas increases.

  As described above, in the polymer electrolyte fuel cell system of the present embodiment, even if a reaction gas having a low relative humidity is supplied to the battery stack, the water vapor content of the reaction gas supplied to the battery stack by the humidity exchanging unit 10. Since the pressure increases, it is possible to obtain good battery characteristics without lowering the battery temperature even in a non-humidified operation.

  As a result, the use of a humidifier can reduce the size and cost, and at the same time, it can be operated at a temperature higher than the battery temperature when the conventional non-humidified gas is supplied. Can be suppressed.

(Seventh embodiment)
FIG. 13 is a cross-sectional view showing a configuration example of a unit cell constituting the battery stack in the polymer electrolyte fuel cell system according to the present embodiment, and the arrows in the figure indicate the flow direction of the reaction gas supplied to the battery. ing.

  In FIG. 13, the cell 4 has ion conductivity and gas separation function through a catalyst layer 2a, 2b made of Pt or the like between a pair of gas diffusion electrodes made up of an anode electrode 1a and a cathode electrode 1b. The solid polymer electrolyte membrane 3 is sandwiched. In the unit cell 4, the anode layer 1 a and the cathode electrode 1 b are not provided with the catalyst layers 2 a and 2 b in the vicinity of the reaction gas downstream.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, reaction heat due to electrode reaction does not occur in the portion where the catalyst layers 2a and 2b in the downstream portion of the reaction gas are not provided. The temperature is lower than that of the electrode reaction portion, and the effect of increasing the relative humidity or condensing water is increased in the downstream portion of the reaction gas. Therefore, water vapor is condensed on the already reacted gas side downstream of the anode electrode 1a or the cathode electrode 1b, and permeates into the unreacted cathode electrode 1b or the anode electrode 1a facing each other through the solid polymer electrolyte membrane 3, respectively. The water vapor diffuses to the unreacted side due to the difference in water vapor partial pressure, and humidification can be performed.

  Accordingly, the cathode electrode 1b or the anode electrode 1a facing each other through the solid polymer electrolyte membrane 3 from the downstream portion of the reaction gas having a relatively high water vapor partial pressure of the anode electrode 1a or the cathode electrode 1b, respectively. It is possible to increase the amount of water vapor that permeates to the upstream portion of the reaction gas having a low water vapor partial pressure.

  In addition, according to the present embodiment, when non-humidified reaction gas is supplied, it is confirmed that substantially the same battery characteristics as the conventional battery can be obtained at 85 ° C., which is about 30 ° C. higher than the operation temperature of the conventional battery. I was able to. Moreover, since the operating temperature is higher than that of the conventional battery, the voltage drop due to CO poisoning could be improved.

(Modification)
As shown in FIG. 14, the catalyst layer 2 a may be omitted only in a portion of the unit cell 4 located near the outlet of the reactive gas of the anode electrode 1 a.

  As described above, in the polymer electrolyte fuel cell system of the present embodiment, even if a reaction gas having a low relative humidity is supplied to the battery stack, the water vapor content of the reaction gas supplied to the battery stack by the humidity exchanging unit 10. Since the pressure increases, it is possible to obtain good battery characteristics without lowering the battery temperature even in a non-humidified operation.

  As a result, the use of a humidifier can reduce the size and cost, and at the same time, it can be operated at a temperature higher than the battery temperature when the conventional non-humidified gas is supplied. Can be suppressed.

(Eighth embodiment)
FIG. 15 is a cross-sectional view showing a configuration example of a unit cell constituting the cell stack in the polymer electrolyte fuel cell system according to the present embodiment.

  In FIG. 15, the unit cell 4 has ion conductivity and a gas separation function between a pair of gas diffusion electrodes composed of an anode electrode 1 a and a cathode electrode 1 b via catalyst layers 2 a and 2 b composed of Pt or the like, respectively. The solid polymer electrolyte membrane 3 is sandwiched. In the unit cell 4, the reaction gas flowing through the anode electrode 1 a and the cathode electrode 1 b flows opposite to each other, and a portion of the anode electrode 1 a and the cathode electrode 1 b near the reaction gas inlet / outlet has a catalyst layer. 2a and 2b are not provided.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, if gas diffusion is poor downstream of the reaction gas, supply of protons is hindered, which may cause corrosion. is there.

  For example, a carbon electrode corrodes due to the following reaction.

C + 2H ₂ O → CO ₂ + 4H ⁺ + 4e ⁻
In this regard, in the configuration of the present embodiment, the catalyst layers 2a and 2b are not provided in the portions of the anode electrode 1a and the cathode electrode 1b located in the vicinity of the reaction gas inlet / outlet, so that the anode electrode 1a is generated by the anode electrode 1a. It is possible to prevent the supply of protons to the cathode electrode 1b from being hindered and to prevent corrosion.

  In the present embodiment, power generation was performed under operating conditions that deteriorated gas diffusion during high loads, low temperature operation, and the like, but no corrosion was confirmed.

  As described above, in the polymer electrolyte fuel cell system of the present embodiment, corrosion can be prevented, so that the reliability of the cell can be improved.

(Modification)
As shown in FIG. 16, the catalyst layer 2b may be omitted from only the portion of the unit cell 4 located near the outlet of the reaction gas of the cathode electrode 1b.

(Ninth embodiment)
FIG. 17 is a schematic diagram showing a configuration example of the polymer electrolyte fuel cell system according to the present embodiment.

  In the polymer electrolyte fuel cell system of the present embodiment, the already-reacted gas that has passed through the cell stack is brought into contact with air having a temperature lower than that of the already-reacted gas through the water-retaining porous body, and the water-retaining porous The body is provided with a humidity exchanging section for exchanging humidity by condensing water vapor contained in the already-reacted gas.

  That is, in FIG. 17, the present system has a battery stack 30 and a humidity exchange unit 3. Here, the already-reacted gas discharged from the battery passes through the already-reacted gas channel 34 of the humidity exchanging unit 31 and passes through the unreacted gas channel 33 through the water-retaining porous body 35. Contact with. Thereby, water vapor is condensed in the porous body 35, and the condensed water penetrates the porous body 35 and reaches the unreacted gas flow path 33. The condensed water evaporates and diffuses due to the difference in water vapor partial pressure on the unreacted gas side. At the same time, the water that has not been partially evaporated is pushed out by the flow and is carried to the reformer 31 arranged on the downstream side thereof so as to be used as the water for reforming.

  In the present embodiment, unreacted gas is used. However, the present invention is not limited to this, and a part thereof may be used for heating such as in-vehicle use.

  Next, in the polymer electrolyte fuel cell system according to the present embodiment configured as described above, water vapor permeates through the porous body 35 because water vapor is condensed into the porous body 35 to form water. Since it reaches the unreacted gas side, the surface of the porous body 35 on the unreacted gas side is also wetted, the water vapor partial pressure difference is maximized, and the unreacted gas can be humidified effectively. Moreover, the water that could not be absorbed as water vapor by the unreacted gas on the low temperature side can be supplied as reforming water for the reformer 31 located downstream of the humidifying section.

  As described above, in the polymer electrolyte fuel cell system of the present embodiment, the water vapor contained in the already reacted gas can be efficiently transferred to the unreacted gas, so there is no need to provide a water supply path for humidification. Even at extremely low temperatures, there are no problems such as freezing.

  Moreover, by removing the water contained in the already reacted gas, it is possible to prevent water from remaining in the already reacted gas discharge line and freeze it, and to use some unreacted gas, for example, air in the vehicle. In some cases, since it can be used for heating in winter, the efficiency of the system can be improved.

  Furthermore, the condensed water can also be used for steam reforming of the reformer 31, and in this case, a water tank for reforming is not required, and further downsizing can be achieved.

  As described above, according to the polymer electrolyte fuel cell system of the present invention, the already-reacted gas and the unreacted gas are brought into contact with each other through the water-retaining porous body. Can be moved to the already reacted gas efficiently, so even if unreacted gas with a low surface relative humidity is supplied to the battery stack, the diffusion resistance of water vapor can be reduced and more moisture can be moved. Thus, it becomes possible to sufficiently humidify the unreacted gas, and it is possible to generate electric power without lowering the battery temperature even when the unreacted unreacted gas is operated.

  This eliminates the need for a humidifier that has previously used water, so there is no risk of freezing even when the ambient environment temperature is 0 ° C. or lower. Therefore, since the process of melting frozen water is not required even at low temperatures, the fuel cell can be started up in a shorter time and with a simple system.

  In addition, the system can be made compact by simplifying the system, and at the same time, it can be operated at a temperature higher than the battery temperature when the conventional non-humidified gas is supplied. It is possible to obtain a solid polymer type fuel cell system with performance and compactness.

FIG. 1 is a cross-sectional view showing a configuration example of a conventional polymer electrolyte fuel cell system. FIG. 2A is a conceptual diagram showing a first embodiment of a polymer electrolyte fuel cell system according to the present invention. FIG. 2B is an exploded view showing a first embodiment of a polymer electrolyte fuel cell system according to the present invention. FIG. 3A is an exploded view showing a humidity exchanging unit in the polymer electrolyte fuel cell system according to the first embodiment. FIG. 3B is an exploded view showing a humidity exchanging unit in the polymer electrolyte fuel cell system according to the first embodiment. FIG. 4 is a characteristic diagram for explaining operational effects of the polymer electrolyte fuel cell system according to the first embodiment. FIG. 5 is a perspective view showing a second embodiment of the polymer electrolyte fuel cell system according to the present invention. FIG. 6 is a perspective view showing a configuration example of a unit cell constituting a cell stack in the polymer electrolyte fuel cell system according to the second embodiment. FIG. 7 is a perspective view showing a third embodiment of a polymer electrolyte fuel cell system according to the present invention. FIG. 8 is a perspective view showing a configuration example of a unit cell constituting a cell stack in the polymer electrolyte fuel cell system according to the third embodiment. FIG. 9 is a perspective view showing a fourth embodiment of a polymer electrolyte fuel cell system according to the present invention. FIG. 10 is a perspective view showing a configuration example of a unit cell constituting a cell stack in the polymer electrolyte fuel cell system according to the fourth embodiment. FIG. 11 is a sectional view showing a fifth embodiment of a polymer electrolyte fuel cell system according to the present invention. FIG. 12 is a sectional view showing a sixth embodiment of a polymer electrolyte fuel cell system according to the present invention. FIG. 13 is a sectional view showing a seventh embodiment of the polymer electrolyte fuel cell system according to the present invention. FIG. 14 is a cross-sectional view showing a modification of the seventh embodiment of the polymer electrolyte fuel cell system according to the present invention. FIG. 15 is a sectional view showing an eighth embodiment of a polymer electrolyte fuel cell system according to the present invention. FIG. 16 is a cross-sectional view showing a modified example of the eighth embodiment of the polymer electrolyte fuel cell system according to the present invention. FIG. 17 is a cross-sectional view showing a ninth embodiment of a polymer electrolyte fuel cell system according to the present invention.

Explanation of symbols

1a ... anode electrode, 1b ... cathode electrode,
2a, 2b ... catalyst layer, 3 ... solid polymer electrolyte membrane, 4 ... single cell,
5 ... separator, 7 ... cooling plate,
8 ... sealing material,
9 ... Battery stack (battery part),
10 ... temperature / humidity exchange part,
11a, 11b, 12a, 12b ... gas grooves,
13c: groove through which refrigerant flows,
14 ... porous body,
15a, 15b, 15c, 15d, 15e, 15f ... manifold
30 ... Battery stack,
31 ... reformer,
33 ... unreacted gas flow path,
34 ... Existing reaction gas flow path,
35 ... porous body,
100 ... Already reacted gas,
101: Unreacted gas.

Claims (9)

A solid polymer type fuel cell system comprising a battery body having a battery stack, wherein the battery stack is formed by laminating a plurality of unit cells having a solid polymer electrolyte membrane selectively through a separator and a cooling plate;
The separator is
Comprising gas supply means for allowing two systems of reaction gas to circulate so as to face each other;
The cooling plate is
A solid polymer fuel cell system comprising a refrigerant flow groove, wherein an upstream portion of the refrigerant in the flow groove is arranged at an inlet / outlet portion of each of the two systems of reaction gas in the separator. A solid polymer type fuel cell system comprising a battery body having a battery stack, wherein the battery stack is formed by laminating a plurality of unit cells having a solid polymer electrolyte membrane selectively through a separator and a cooling plate;
The separator is
Comprising gas supply means for allowing two systems of reaction gas to circulate so as to face each other;
The cooling plate is
A refrigerant flow groove is provided, and the interval between the flow grooves in the part corresponding to the inlet / outlet portion of the two systems of the reaction gas in the separator is set to be other than the inlet / outlet portion of the two systems of the reaction gas in the separator. A polymer electrolyte fuel cell system that is narrower than the interval between parts. A solid polymer type fuel cell system comprising a battery body having a battery stack, wherein the battery stack is formed by laminating a plurality of unit cells having a solid polymer electrolyte membrane selectively through a separator and a cooling plate;
The separator is
Gas supply means for circulating two systems of reaction gases so as to face each other;
A polymer electrolyte fuel cell system, comprising: a cooling unit disposed at an inlet / outlet portion of each of the two systems of the reaction gas in the separator and radiating heat to the atmosphere. A battery body having a battery stack, wherein the battery stack is formed by laminating a plurality of unit cells each having a pair of gas diffusion electrode and solid polymer electrolyte membrane, each including a fuel electrode and an oxidant electrode, with a separator and a cooling plate interposed therebetween. In the polymer electrolyte fuel cell system,
The separator is
Gas supply means for circulating two systems of reaction gases so as to face each other;
A polymer electrolyte fuel cell system, wherein a downstream portion of a reaction gas in the gas diffusion electrode is subjected to a hydrophilic treatment. 5. The polymer electrolyte fuel cell system according to claim 4, wherein the hydrophilic treatment is performed by impregnating at least one kind of fine powder of carbon, SiC, SiO2, TiO2 or SnO2 in the downstream portion in advance. The solid polymer fuel cell system according to claim 4, wherein the hydrophilic treatment is to impregnate the downstream portion with a solid polymer electrolyte solution. The solid polymer fuel cell system according to claim 4, wherein the hydrophilic treatment is to press-fit a solid polymer electrolyte membrane into the downstream portion. A battery body having a battery stack, wherein the battery stack is formed by laminating a plurality of unit cells each having a pair of gas diffusion electrode and solid polymer electrolyte membrane, each including a fuel electrode and an oxidant electrode, with a separator and a cooling plate interposed therebetween. In the polymer electrolyte fuel cell system,
The separator is
Gas supply means for circulating two systems of reaction gases so as to face each other;
A solid polymer fuel cell system in which a catalyst layer is provided in a portion of the pair of gas diffusion electrodes except for a downstream portion in a reaction gas flow path. 9. The polymer electrolyte fuel cell system according to claim 8, wherein at least a part of the fuel electrode facing the catalyst layer of the oxidant electrode is provided with a catalyst layer among the pair of gas diffusion electrodes.

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