JP3064023B2 - Gas separator for fuel cells - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas separator for a fuel cell using an ion exchange membrane.

[0002]

2. Description of the Related Art Fuel cells do not need to use fossil fuels, which have a problem of resource depletion, and generate almost no noise.
Since it has excellent features such as an extremely high energy recovery efficiency as compared with other energy engines, it is used as a relatively small power plant, for example, in a building unit or a factory unit. In recent years, this fuel cell has been used as a power source for a motor that operates in place of a vehicle-mounted internal combustion engine,
It has been considered that a vehicle or the like is driven by this motor. In this case, it is important to recycle as much as possible the substances generated by the reaction. It is desirable that the size is as small as possible. From such a point, a fuel cell using an ion exchange membrane, in particular, a solid polymer electrolyte membrane fuel cell has attracted attention.

Here, as an example, the basic structure of a solid polymer electrolyte membrane fuel cell body will be described with reference to FIG.
As shown in the figure, a battery main body 01 is configured by joining gas diffusion electrodes 03A and 03B to both sides of a solid polymer electrolyte membrane 02. The joined body is provided on both sides of the solid polymer electrolyte membrane 02 with gas diffusion electrodes 03A and 03A.
It is manufactured by hot pressing or the like after combining B. The gas diffusion electrodes 03A and 03B are formed by bonding reaction films 04A and 04B and gas diffusion films 05A and 05B, respectively.
The surface of 4B is in contact. Therefore, the battery reaction mainly occurs at the contact surface between the electrolyte membrane 02 and the reaction membranes 04A and 04B. Further, on the surface of the gas diffusion electrode 03A,
A gas separator having an oxygen supply groove 06a is joined to a gas separator 07 having a hydrogen supply groove 07a on the surface of the other gas diffusion electrode 03B, and constitutes an oxygen electrode and a hydrogen electrode.

When oxygen and hydrogen are supplied to the oxygen supply groove 06a and the hydrogen supply groove 07a, respectively, oxygen and hydrogen are supplied to the reaction films 04A and 04B via the gas diffusion films 05A and 05B, respectively. Reaction membrane 04A, 04B
The following reaction occurs at the interface between the electrolyte membrane 02 and the electrolyte. Interface of the reaction film 04A: O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O Interface of the reaction film 04B: 2H ₂ → 4H ⁺ + 4e ⁻ Here, 4H ⁺ flows from the hydrogen electrode to the oxygen electrode through the electrolyte membrane 02, 4e ^- is will flow from the hydrogen electrode to the oxygen electrode through the load 08, electrical energy is obtained.

In such a fuel cell, gas separators for fuel cells such as gas separators 06 and 07 are
It is necessary that the fuel gas and the oxidizing gas are uniformly and completely separated and supplied to each back surface, and that the gas generated by the reaction is efficiently collected. Further, since heat generated by the battery reaction is large, it is necessary to dissipate the reaction heat through the gas separator in order to stabilize the operating conditions.

Therefore, in the prior art, a plurality of gas separators each having gas supply grooves formed on both surfaces thereof and a joined body of a solid polymer electrolyte membrane and a gas diffusion electrode are sequentially laminated to form a multiple battery cell. A cooling water jacket is provided in the periphery of the cell, or a cooling board is inserted at intervals of several cells. In addition, a cooling water supply groove is formed together with the gas supply groove on the gas supply groove forming surface of the gas separator, and the cooling water flows so as to directly contact the back surface of the gas diffusion electrode, thereby also serving as a direct humidifier for the electrolyte membrane. Is also known.

[0007]

The features of the solid polymer membrane fuel cell described above are compact and high performance. Considering that the thickness of the gas diffusion electrode is 1 to 1.5 mm, it can be said that the size of the fuel cell is determined by the structure and thickness of the gas separator.

On the other hand, in order to obtain the function of the gas separator described above, the gas supply groove for supplying gas to the gas diffusion electrode is made as small as possible so that the gas is supplied uniformly over the entire surface of the gas diffusion electrode. In addition, it is conceivable to reduce the interval between the supply grooves in order to minimize the current collecting distance. However, in the case of an integrated gas separator,
Conventionally, the 1mm pitch is the limit due to the limit of work,
In addition, there is a problem that it is not possible to obtain a structure that takes into account the control of the gas flow. Further, as described above, the separator having a structure in which the cooling water grooves are provided between the gas supply grooves has a problem that the gap between the supply grooves is small, so that the number of seal portions is small, and the gas supply portion and the cooling water supply portion cannot be sealed. . Further, if a cooling mechanism is provided in the gas separator, it is necessary to increase the wall thickness, which hinders downsizing.

In view of such circumstances, an object of the present invention is to provide a gas separator for a fuel cell which is compact and has a high performance and which can make the fuel cell compact and improve its performance.

[0010]

A gas separator for a fuel cell according to the present invention, which achieves the above object, is sandwiched between gas diffusion electrodes of a fuel cell and diffuses fuel gas to one gas diffusion electrode on the other side. A gas separator for supplying an oxidizing gas to the electrode, wherein a fuel gas supply groove for flowing a fuel gas is formed by etching on one surface in contact with the gas diffusion electrode on one side, and has a thickness of about 1 mm. Stainless
And less steel or copper fuel gas supply plate, the other side oxidizing gas supplying groove for flowing the oxidizing agent gas to the one surface in contact with the gas diffusion electrode is formed by etching a thickness of 1
The oxidizing gas supply plate made of stainless steel or copper of about mm, and the cooling water supply groove for flowing the cooling water in a state of being in contact with the other surfaces of the fuel gas supply plate and the oxidizing gas supply plate by etching. Formed , 0.5m thick
m and a cooling water plate made of stainless steel or copper .

[0011]

The gas separator for a fuel cell having the above-mentioned structure is obtained by joining a fuel gas supply plate and an oxidizing gas supply plate to both sides of a cooling water plate, and the three members can be individually processed. In addition, the supply groove can be subdivided by fine processing such as etching, and an arbitrary groove shape can be obtained. Therefore, compactness can be achieved. Further, the fuel gas and the oxidizing gas can be completely separated, and moreover, the performance can be improved by making the supply uniform and improving the current collection efficiency.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIG. 1 is an exploded perspective view of a gas separator for a fuel cell according to one embodiment, FIG.
Shows the front and back planes of each part and the manufacturing process.

As shown in these drawings, the gas separator 10 of the present embodiment comprises a fuel gas supply plate 20, a cooling water plate 3.
0 and the oxidizing gas supply plate 40 are joined and integrated. The four corners of the gas separator 10 are provided with a fuel gas supply hole 11, an oxidant gas supply hole 12, a fuel gas discharge hole 13, and an oxidant gas discharge hole 14 penetrating in the thickness direction. The fuel gas discharge holes 13 and the oxidizing gas supply holes 12 and the oxidizing gas discharge holes 14 are respectively arranged at diagonal positions.
Similarly, a cooling water supply hole 15 and a cooling water discharge hole 16 are also provided between the supply holes 11 and 12, that is, at the center in the width direction.

On the surface of the fuel gas supply plate 20, a number of fuel gas supply grooves 21 extending in the width direction (vertical direction in FIG. 3) are formed at a constant pitch. The fuel gas supply groove 20 is provided at both ends in the width direction of the back surface of the fuel gas supply plate 20.
A fuel gas supply header 22 and a fuel gas discharge header 23 are formed at positions corresponding to both ends of the fuel gas supply groove 21 and include a plurality of grooves extending in a direction orthogonal to the fuel gas supply groove 21. As shown in FIG. 2, the fuel gas supply header 22 and the fuel gas discharge header 23 communicate with the fuel gas supply groove 21 on the bottom side. Also, the fuel gas supply header 2
Reference numeral 2 denotes a fuel gas supply hole 11 at one end thereof, and a fuel gas discharge header 23 communicates with the fuel gas discharge hole 13 at one end thereof. Further, a cooling water supply header 24 composed of a plurality of grooves communicating with the cooling water supply holes 15 and the cooling water discharge holes 16 is provided at both ends in the longitudinal direction (left and right directions in FIG. 3) of the back surface of the fuel gas supply plate 20. And cooling water discharge header 2
5 are formed.

The oxidant gas supply plate 40 has the same structure as the fuel gas supply plate 20, and has an oxidant gas supply groove formed on the front surface and an oxidant gas supply header 42 on the back surface. Agent gas discharge header 43, cooling water supply header 4
4 and a cooling water supply header 45 are formed respectively. The oxidizing gas supply groove, the oxidizing gas supply header 42, and the oxidizing gas discharge header 43 communicate with each other at the bottom, and the oxidizing gas supply header 42, the oxidizing gas supply hole 12, and the oxidizing gas supply header. The discharge header 43 communicates with the oxidant gas discharge hole 14, the cooling water supply header 44 communicates with the cooling water supply hole 15, and the cooling water discharge header 45 communicates with the cooling water discharge hole 16, respectively.

The cooling water plate 30 has a longitudinal direction (FIG. 3).
A cooling water groove 31 extending in the middle and left and right directions and penetrating in the thickness direction is formed. And these cooling water grooves 31
Both ends of the fuel gas supply plate 20 and the oxidant supply plate 40
Cooling water supply headers 24 and 44 and cooling water discharge header 2
5, 45.

The gas separator 10 of the present embodiment comprises a fuel gas supply plate 20 and an oxidant gas supply plate 4 having such a structure.
The cooling water plate 30 is sandwiched and joined on the back surface side of the reference numeral 0. The gas separator 10 is used while being sandwiched between gas diffusion electrodes. The fuel gas supplied from the fuel gas supply hole 11 is supplied to the fuel gas supply header 2.
After flowing through each fuel gas supply groove 21 from 2, the fuel gas is discharged from the fuel gas discharge hole 13 via the fuel gas discharge header 23. The oxidizing gas supplied from the oxidizing gas supply hole 12 flows through each oxidizing gas supply groove from the oxidizing gas supply header 42, and then passes through the oxidizing gas discharge header 43. It is discharged from 14. Accordingly, the gas flowing through the fuel gas supply groove 21 and the gas flowing through the oxidant gas supply groove 41 are supplied through the gas diffusion electrode. The cooling water supplied from the cooling water supply hole 15 is
The fuel gas is supplied to the cooling water groove 31 via the cooling water supply headers 24 and 44, and the fuel gas supply plate 20 and the oxidizing gas supply plate 4 are supplied.
After flowing in contact with the back surface of the cooling water discharge header 25,
The cooling water is discharged from the cooling water discharge hole 16 via 45. Thereby, the fuel gas supply plate 20 and the oxidant gas supply plate 40
The heat generated in the fuel cell can be removed via the fuel cell.

Next, a specific example of the production of the gas separator 10 will be described. As the fuel gas supply plate 20 and the oxidant gas supply plate 40, a pure copper plate (phosphorous deoxidized copper) having a thickness of 1 mm was used. Gas supply grooves 21 and 41 are 0.5mm pitch and 0.5mm
Gas supply headers 22, 42 and gas discharge headers 23, 43 and cooling water supply headers 24, 4 on the back surface.
4 and the cooling water discharge headers 25 and 45 were also set to a depth of 0.5 mm, and both surfaces were simultaneously processed by half etching. The gas supply holes 11 and 12 and the gas discharge holes 13 and 14 and the cooling water supply hole 15 and the cooling water discharge hole 16 penetrate, and the gas supply grooves 21 and 41 and the gas supply header 22
The point in time when the 42 and the gas discharge headers 23 and 43 respectively communicated was regarded as the end point of the processing. In addition, the cooling water plate 30 includes
Using a pure copper plate having a thickness of 0.5 mm, processing was performed again by etching until it penetrated in the thickness direction to form a cooling water supply groove 31 and holes 11 to 16. Next, 5 to 7 .mu.Ag plating was applied to the entire front and back surfaces of the cooling water plate 30, sandwiched between the back surfaces of the fuel gas supply plate 20 and the oxidant gas supply plate 40, and integrally joined by a vacuum diffusion welding device. This vacuum diffusion bonding
In a vacuum of 5 × 10 ^-4 Torr, a temperature of 950 ° C. and a surface pressure of 0.1
After maintaining the pressurizing time at 3 kg / mm ² for 3 hours, the mixture was gradually cooled to obtain a gas separator 10 having a thickness of 2.5 mm.

The gas separator 10 described above includes a fuel gas supply plate 20, a cooling water plate 30, and an oxidizing gas supply plate 40.
Can be easily processed, and can be made compact. In addition, when the etching process is employed as in the embodiment, the size and shape of the groove can be arbitrarily changed, so that each groove can be expanded or contracted according to the pressure loss. Uniformity can be achieved. Further, since such gas separators are individually cooled, the reaction heat of the fuel cell can be controlled, and excellent power generation performance as described later can be obtained. Further, each groove constituting the separator of the present invention,
Since it is formed by etching,
Can be machined easily with a stable groove depth,
A thinner plate can be used.

A fuel cell was obtained by alternately stacking 30 sheets (hereinafter referred to as "cells") of a solid polymer electrolyte membrane and two sheets of gas diffusion electrodes (hereinafter referred to as cells) and 31 sheets of the above separators. This fuel cell is supplied with H ₂ (water vapor humidified) as a fuel gas.
30 l / min at 5 kg / cm ² G, O as oxidizing gas
₂ 2.5 kg / cm ² G, 30 l / min respectively,
The power generation performance was measured at a cell temperature of 70 ° C. This result is shown in FIG.
Shown in On the other hand, for comparison, as a conventional gas separator, it has a gas supply groove of 1 mm pitch and 1 mm depth, which is the limit of electric discharge machining, and a gas supply / discharge header for gas supply is provided at the center in the plate thickness direction. A fuel cell was composed of the same 30 cells (thickness: 8 mm), and the power generation performance was measured in the same manner. In this case, cooling was performed by installing a water cooling plate (thickness: 8 mm) at a pitch of three sheets. This result is also shown in FIG. The reaction area of both was 168 cm ^2, which was the same. From this result, it was confirmed that the fuel cell using the gas separator of the present invention can obtain more excellent power generation performance. It should be noted that the fuel cell of the conventional comparative example is instantaneous data because it is difficult to remove local heat and reaction heat in the cell and operation stability is poor.

The dimensions of the cell portions of the fuel cell of the above-described embodiment and the fuel cell of the comparative example were compared. In the fuel cell of the embodiment, since one cell is 1.1 mm, the total thickness is 1.1 mm.
× 30 + 2.5 × 31 = 110.5 mm. On the other hand, the fuel cell of the comparative example was 1.1 × 30 + 8 × 31 + 8 mm × 1
0 (water cooling plate) = 361 mm. Thus, by using the gas separator of the present invention, a remarkable downsizing of the fuel cell can be realized.

In the embodiment described above, the material of the separator is pure copper. However, the material is not limited to this, and stainless steel or the like may be used.

[0024]

As described above, the gas separator of the present invention can achieve a uniform supply of gas and an improvement in current collection efficiency, control the amount of heat generated by power generation, and stabilize operating conditions. In addition, the fuel cell can be significantly reduced in size.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a gas separator according to one embodiment.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is an explanatory view showing a component structure of the separator of FIG.

FIG. 4 is a graph showing a battery performance curve as a test result.

FIG. 5 is a configuration diagram showing a solid polymer electrolyte membrane fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas separator 11 Fuel gas supply hole 12 Oxidant gas supply hole 13 Fuel gas discharge hole 14 Oxidant gas discharge hole 20 Fuel gas supply plate 21 Fuel gas supply groove 22 Fuel gas supply header 23 Fuel gas discharge header 24 Cooling water supply header 25 cooling water discharge header 30 cooling water plate 31 cooling water supply groove 40 oxidant gas supply plate 41 oxidant gas supply groove 42 oxidant gas supply header 43 oxidant gas discharge header 44 cooling water supply header 45 cooling water discharge header

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-140559 (JP, A) JP-A-59-31568 (JP, A) JP-A-60-236459 (JP, A) JP-A-60-1985 241658 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 8/00-8/24

Claims (1)

(57) [Claims] 1. A gas separator sandwiched between gas diffusion electrodes of a fuel cell for supplying a fuel gas to one gas diffusion electrode and an oxidizing gas to the other gas diffusion electrode. A fuel gas supply groove for flowing a fuel gas is formed on one surface in contact with the gas diffusion electrode by etching, and a fuel gas supply plate made of stainless steel or copper having a thickness of about 1 mm, and a gas on the other side. An oxidizing gas supply groove for flowing an oxidizing gas on one surface in contact with the diffusion electrode is formed by etching , and a stainless steel or copper oxidizing gas supply plate having a thickness of about 1 mm , A cooling water supply groove for flowing cooling water in a state of being in contact with the other surfaces of the fuel gas supply plate and the oxidizing gas supply plate is formed by etching , and has a thickness of about 0.5 mm.
A gas separator for a fuel cell, comprising a stainless steel or copper cooling water plate joined and integrated.