JP2001023662A - Humidifier member, solid polymer electrolyte fuel cell with this humidifier member, and fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove impurities in reaction gas and humidifying water, prevent drop in cell characteristics, omit an impurity removing device, and make a fuel cell system compact. SOLUTION: This humidifier member is constituted by stacking one or several numbers of a stack comprising a water permeable membrane 7 and a pair of porous supporters 8 for interposing the water permeable membrane; and a humidifying plate 1 comprising a pair of humidifying plate separators 9, 10 installed on the opposite sides of the stack, a pair of humidifying plate separators 9, 10 is composed of the humidifying plate separator 9 having a gas flow plate 11 and the humidifying plate separator 10 having a humidifying water flow plate 13, and activated carbon is contained in at least one of a pair of porous supporters 8, the gas flow plate 11, and the humidifying water flow plate 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid polymer electrolyte fuel cell in which a humidifier member and a laminated fuel cell member are integrated, and a fuel cell system provided with the fuel cell. In particular, the present invention relates to a solid polymer electrolyte fuel cell and a fuel cell system having a porous support of a humidifier and a separator for a humidifier improved to remove impurities in the humidified reaction gas and the humidified water.

[0002]

2. Description of the Related Art Solid polymer electrolyte fuel cells (PEF)
C (Polymer Electrolyte Fuel Cell) is a fuel cell using a polymer membrane as an electrolyte, and has features such as high output density and long battery life.

FIG. 4 shows a structure of a general cell unit cell constituting this polymer electrolyte fuel cell. A general battery unit cell includes an electrolyte membrane 18 made of a solid polymer electrolyte, a pair of electrodes 19 sandwiching the electrolyte, and a pair of current collectors sandwiching a laminate of the electrode 19 and the electrolyte membrane 18. 20 and a battery separator 21 provided on the outer surface of the current collector 20.
And Here, in the battery separator, a gas flow groove 22 is formed on a surface in contact with the current collector. The reaction gas passes through the gas flow groove 22. Further, a cooling water circulation groove 23 is formed on the other surface of the battery separator, that is, the surface that is not in contact with the current collector. This cooling water flow groove 23
Then, cooling water for cooling a member heated by power generation at the electrode is passed through.

A solid polymer electrolyte body 18 used in a solid polymer electrolyte fuel cell has high ionic conductivity in a wet state. Therefore, high battery characteristics can be obtained by humidifying the reaction gas with water.

As a means for humidifying the reaction gas, a method using a humidifier in which one or a plurality of humidifying plates are laminated has conventionally been adopted. One example of such a humidifying plate is shown in FIG. A conventionally used humidifying plate is a water-permeable membrane 7
With a humidifying plate separator 25 via a porous support 24.
And a humidifying plate separator 26. The gas flow groove 12 is formed on the surface of the humidifying plate separator 25 facing the porous support 24. On the other hand, the humidifying plate separator 26 has the humidifying water circulation groove 14 formed on the surface facing the porous support 24. The humidification water flowing through the humidification water flow grooves 14 passes through the water permeable membrane 7 and passes through the gas flow grooves 12.
The reaction gas is humidified by contact with the reaction gas flowing through the gas.

A polymer electrolyte fuel cell in which such a humidifier is integrated with the above-described cell stack is disclosed in, for example, JP-A-9-35737 and JP-A-9-9230.
No. 9 discloses this. Japanese Patent Application Laid-Open No. 9-35737 discloses that a reaction gas is provided on both sides of a stacked body in which a plurality of battery cells and a plurality of heat exchangers through which a heat medium for removing heat generated in the battery cells flows are stacked. There is disclosed a fuel cell having a humidifier for humidifying air. Further, Japanese Patent Application Laid-Open No. 9-9 / 1997
No. 2309 discloses a fuel cell having a humidifying section provided adjacent to each single cell, and having means for humidifying a gas flowing through a porous support and a water permeable membrane to a gas flowing section of a separator. .

[0007] However, it is known that the conventional fuel cell generally deteriorates in cell characteristics due to impurities contained in a reaction gas used for cell reaction. That is, as impurities of the anode gas, there are carbon dioxide gas, carbon monoxide gas, methane gas and the like contained in hydrogen. Air is usually used as the cathode gas, and carbon dioxide gas, carbon monoxide gas,
Examples include nitrogen oxides and sulfur oxides. In addition, impurities such as organic substances are mixed in the humidified water. These are adsorbed by the catalyst in the fuel cell and hinder the electrode reaction, thereby deteriorating the cell characteristics.

Therefore, it is necessary to remove the above-mentioned impurities before supplying the reaction gas and the humidified water to the fuel cell. That is, as in the conventional fuel cell system shown in FIG. 7, in order to remove the impurities before the reaction gas and the humidifying water are introduced into the fuel cell, the reaction gas and the humidifying water are required to be removed in the course of the reaction gas and the humidifying water. It was necessary to install an impurity remover. This impurity remover has a structure filled with activated carbon particles that adsorb the impurities, and when the reaction gas and the humidified water flow therethrough, the impurities are adsorbed and removed.

[0009]

However, since the conventional fuel cell system has the above configuration, the fuel cell system becomes complicated and costly. Therefore, a fuel cell system with a simpler structure and less cost is required. The present invention provides the humidifier with a function of removing impurities in the reaction gas and the humidifying water, and can prevent a decrease in cell characteristics by removing impurities in the reaction gas and the humidifying water. It is an object of the present invention to provide a solid polymer electrolyte fuel cell in which a remover can be omitted and the fuel cell system can be made compact.

[0010]

In order to solve the above problems, a humidifier member according to the present invention comprises a laminate comprising a water permeable membrane and a pair of porous supports sandwiching the water permeable membrane. A humidifier member configured by laminating one or a plurality of humidifying plates composed of a pair of humidifying plate separators provided on both surfaces of the laminate, wherein the pair of humidifying plate separators is a gas flow plate. A humidifying plate separator having a humidifying plate separator having a humidifying water flow plate,
At least one of the pair of porous supports, the gas flow plate, and the humidified water flow plate contains activated carbon.

Further, the solid polymer electrolyte fuel cell of the present invention is obtained by integrating the above-mentioned humidifier member and the laminated fuel cell member.

Here, the above-mentioned laminated fuel cell member is composed of a laminated body comprising a solid polymer electrolyte body and a pair of electrodes sandwiching the solid polymer electrolyte body, and a pair of batteries provided on both sides of the laminated body. It is preferable to laminate a plurality of battery single cells each including a battery separator.

Further, the fuel cell system of the present invention comprises the above-mentioned solid polymer electrolyte fuel cell, a hydrogen supply source, an air supply source, and a humidified water supply source communicating with the solid polymer electrolyte fuel cell. Is provided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solid polymer electrolyte fuel cell according to the present invention will be described in detail.

FIG. 1 is a schematic view showing an example of a solid polymer electrolyte fuel cell according to the present invention. The illustrated solid polymer electrolyte fuel cell includes a humidifier member 2 formed by stacking one or more humidifying plates 1 and a stacked fuel cell member 4 formed by stacking a plurality of battery single cells 3. This is an integrated solid polymer electrolyte fuel cell. The humidifier member 2 is
A current collector plate 5 is provided on both sides of the stacked fuel cell member 4 in the stacking direction, and a pressure plate 6 is provided outside each humidifier member 2. The humidifier member 2 has a function of removing impurities of the reaction gas and the humidified water.

Here, the humidifier member 2 and the stacked fuel cell member 4 have a structure in which the humidifier member 2 sandwiches the stacked fuel cell member 4 in FIG. 1, but the invention is not limited to this.

FIG. 2 shows an example of the humidifying plate 1 used in the present invention. The humidifying plate 1 includes a water permeable membrane 7, a porous support 8,
And humidifying plate separators 9 and 10. The water permeable membrane 7 is sandwiched between a pair of porous supports 8, and the water permeable membrane 7 sandwiched between the porous supports 8 is provided.
Is further sandwiched by a pair of humidifying plate separators 9 and 10. Here, the humidifying plate separator 9 has a dent on the surface in contact with the porous support 8, and the gas flow plate 11 is arranged in this dent. Further, the gas flow plate 11 has a plurality of gas flow grooves 12 for flowing a reaction gas on a surface in contact with the porous support 8.
Further, the humidifying plate separator 10 has a dent on the surface in contact with the porous support 8, and the humidifying water flow plate 1
3 are arranged. Further, the humidification water distribution plate 13
Has a plurality of humidification water circulation grooves 14 for circulating humidification water on the surface in contact with the porous support 8.

In the present invention, activated carbon is used for the porous support 8 in order to remove the reaction gas and impurities during humidification. As the activated carbon used in the present invention,
Examples include powdered / granular activated carbon, fibrous activated carbon, sheet activated carbon, paper activated carbon, felt activated carbon, and activated superporous carbon molded product.

When powdered or granular activated carbon is used, the structure of the porous support 8 containing the activated carbon includes a binder and a carbon substrate in addition to the powdered and granular activated carbon. Fluororesin or the like is used as the binder. As the carbon substrate, fibers (fibers), cloths, sheets, papers, and felts are used.

When fibrous activated carbon is used as the activated carbon, the porous support 8 containing the activated carbon contains a binder in addition to the fibrous activated carbon. As described above, a fluororesin or the like is used as the binder.

When sheet activated carbon, paper activated carbon, felt activated carbon, or activated superporous carbon molded article is used as the activated carbon, they can be used alone.

FIG. 3 specifically shows the structure of a porous support containing activated carbon used in the present invention. The porous support containing activated carbon shown in FIG.
And a structure in which activated carbon particles 16 are dispersed and fixed in carbon fibers with a binder 17. FIG. 3 (b)
The activated carbon-containing porous support shown in FIG.
6 is mixed with a binder 17.

In the present invention, activated carbon can also be used for the gas flow plate 11 or the humidified water flow plate 13 instead of the porous support. Preferably, activated carbon is used for the porous support, the gas flow plate, and the humidified water flow plate. The configuration of the gas distribution plate 11 and the humidification water distribution plate 13 containing the activated carbon can be the same as that of the porous support 8 described above.

The gas flow grooves 1 of the humidifying plate 1 of the present invention described above.
The reaction gas flowing through 2 comes into contact with gas flow plate 11 made of activated carbon and porous support 8 made of activated carbon. Then, impurities in the reaction gas are adsorbed on the activated carbon and removed. The humidification water flowing through the humidification water flow groove 14 and passing through the water permeable membrane 7 contacts the humidification water flow plate 13 made of activated carbon and the porous support 8 made of activated carbon. Then, impurities in the humidified water are adsorbed on the activated carbon and removed.

The single battery cell 3 used in the present invention has, for example, a generally used structure shown in FIG. The single battery cell 3 includes an electrolyte membrane 18 made of a solid polymer electrolyte, an electrode 19, a current collector 20, and a battery separator 21. The electrolyte membrane 18 is a pair of electrodes 1
9 and a pair of current collectors 2
Hold at 0. Further, a pair of battery separators 21 is provided on both sides of the laminate. Each of the battery separators 21 is provided with a plurality of gas flow grooves 22 for flowing a reaction gas on a surface in contact with the current collector 20. Further, the battery separators 21 are respectively provided with gas flow grooves 22.
A plurality of cooling water flow grooves 23 for flowing cooling water are formed on the surface opposite to the surface on which is formed.

By integrating the humidifier member 2 and the laminated fuel cell member 4 described above, the reaction gas, which is humidified by passing through the humidifier member 2 and from which impurities have been removed, is supplied to the gas flow grooves of the single battery cell. Distribute. Therefore, adsorption of undesired impurities on the catalyst in the fuel cell,
In addition, the deterioration of the battery characteristics caused by the inhibition of the electrode reaction caused thereby is prevented.

Further, a fuel cell system according to the present invention comprises a solid polymer electrolyte fuel cell in which the above-described humidifier member and the stacked fuel cell member are integrated, and a hydrogen gas communicating with the solid polymer electrolyte fuel cell. A supply source, an air supply source, and a humidification water supply source. FIG. 5 shows a fuel cell system of the present invention. In the solid polymer electrolyte fuel cell in which the humidifier member and the stacked fuel cell member shown in FIG. 5 are integrated, the humidifier also has an impurity removing function. Therefore,
The reaction gas, that is, the hydrogen supply source and the air supply source and the humidification water supply source do not pass through the impurity remover,
It can be sent to a solid polymer electrolyte fuel cell. Therefore, a miniaturized fuel cell system can be provided.

[0028]

[Example 1] As shown in FIG. 2, a sheet-like activated carbon was used for a porous support 8 of a humidifying plate, and a gas flow plate 1 was used.
A humidified plate 1 having a structure as shown in FIG. 2 was manufactured by using the activated superporous carbon molded body for No. 1 and the activated superporous carbon molded body for the humidification water flowing plate. This humidifying plate
Zero pieces were laminated to form a humidifier member. Next, a single fuel cell having a structure as shown in FIG. 4 was manufactured, and 50 fuel cells were stacked to obtain a stacked fuel cell member. A solid polymer electrolyte fuel cell was manufactured by laminating the humidifier member and the laminated fuel cell member as shown in FIG.

Next, in order to examine the cell characteristics of the solid polymer electrolyte fuel cell, a small amount of impurities was added to the air (or hydrogen) supplied to the obtained solid polymer electrolyte fuel cell. Of the cell voltage was measured.
As the impurity gas, carbon monoxide, sulfur dioxide, and nitrogen dioxide are used.
0 ppm was added at a time, and the change in cell voltage was measured.

FIG. 8A shows the result. No change in cell voltage due to the influence of impurities was measured.

Example 2 Except that paper activated carbon was used for the porous support 8 of the humidifying plate, sheet activated carbon was used for the gas distribution plate 11, and sheet activated carbon was used for the humidified water distribution plate 13. A solid polymer electrolyte fuel cell was manufactured in the same manner as in Example 1.

Next, an experiment was conducted in the same manner as in Example 1 to examine the cell characteristics of this solid polymer electrolyte fuel cell. Also in the solid polymer electrolyte fuel cell obtained in this example, no change in cell voltage due to the influence of impurities was measured as in the case of Example 1.

Comparative Example 1 The same cell characteristics as in Example 1 were examined using a conventional solid polymer electrolyte fuel cell. As can be seen from the results shown in FIG. 8B, a decrease in cell voltage was observed after the addition of carbon monoxide, the addition of sulfur dioxide, and the addition of nitrogen dioxide.

As described above, in the solid polymer electrolyte fuel cell of the present invention, even if the impurity remover is not provided between the fuel cell and the reaction gas source and the humidified water supply source, the cell characteristics do not deteriorate. You can see that.

[0035]

According to the present invention, the porous support in the humidifying plate contains activated carbon and / or at least one of the gas distribution plate and the humidification water distribution plate of the pair of humidifying plate separators contains activated carbon. Thereby, the impurities in the reaction gas and the impurities in the humidified water can be adsorbed on the activated carbon to remove the impurities. As a result, there is no need to provide an impurity removing device required for the conventional fuel cell system, and the solid oxide fuel cell system can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of the solid polymer electrolyte fuel cell of the present invention.

FIG. 2 is a schematic cross-sectional view of a humidifying plate used in the solid polymer electrolyte fuel cell of the present invention.

FIG. 3 is a schematic cross-sectional view of a porous support, a gas flow plate, or a humidified water flow plate containing activated carbon of the solid polymer electrolyte fuel cell of the present invention.

FIG. 4 is a schematic cross-sectional view of a unit cell of a commonly used laminated fuel cell member.

FIG. 5 is a schematic diagram of a fuel cell system of the present invention.

FIG. 6 is a schematic sectional view of a conventional humidifying plate.

FIG. 7 is a schematic diagram of a conventional fuel cell system.

FIG. 8A is a diagram showing the cell characteristics of a solid polymer electrolyte fuel cell of the present invention, and FIG. 8B is a diagram showing the cell characteristics of a conventional solid polymer electrolyte fuel cell. .

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 humidifying plate 2 humidifier member 3 single battery cell 4 laminated fuel cell member 5 current collector plate 6 pressure plate 7 water permeable membrane 8, 24 porous support 9, 10, 25, 26 separator for humidifying plate 11 gas distribution plate 12 Gas circulation groove 13 Humidification water circulation plate 14 Humidification water circulation groove 15 Carbon fiber 16 Activated carbon particle 17 Binder 18 Electrolyte membrane 19 Electrode 20 Current collector 21 Battery separator 22 Gas circulation groove 23 Cooling water circulation groove

Claims (4)

[Claims] 1. A humidifying plate comprising a laminate comprising a water permeable membrane and a pair of porous supports sandwiching the water permeable membrane, and a pair of humidifying plate separators provided on both sides of the laminate. Or a humidifier member configured by laminating a plurality of, the pair of humidifying plate separators, a humidifying plate separator having a gas flow plate, and a humidifying plate separator having a humidifying water flow plate. A humidifier member, wherein at least one of the pair of porous supports, the gas flow plate, and the humidification water flow plate contains activated carbon. 2. A solid polymer electrolyte fuel cell, wherein the humidifier member according to claim 1 and a laminated fuel cell member are integrated. 3. The laminate fuel cell member comprises a laminate comprising a solid polymer electrolyte body and a pair of electrodes sandwiching the solid polymer electrolyte body, and a pair of battery separators provided on both sides of the laminate. 3. The solid polymer electrolyte fuel cell according to claim 2, wherein a plurality of battery single cells comprising: 4. The solid polymer electrolyte fuel cell according to claim 2, and a hydrogen supply source, an air supply source, and a humidified water supply communicating with the solid polymer electrolyte fuel cell. And a fuel cell system.