JP2003303597A - Solid polymer type fuel cell, separator, and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid polymer type fuel cell achieving both high performance and low cost. <P>SOLUTION: The fuel cell uses a separator made of materials including at least a stamped metal material and a resin. The separator comprises electron- conductive ribs, with at least one dummy rib provided between adjacent ones of the electron-conductive ribs. The invention is advantageous for reducing cost because the separator can be fabricated through an inexpensive processing method using a conventional metal plate. Furthermore, the invention improves the linear velocity of a reaction gas by providing the dummy rib on the separator surface, and reduces resistance components by increasing the areas in which the separator is in contact with an electrode and a diffusion layer. The performance of the cell is thereby improved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel cell,
In particular, it relates to a solid polymer fuel cell using a solid polymer membrane.

[0002]

2. Description of the Related Art A separator that separates an anode gas and a cathode gas in a fuel cell (PEFC) to form a gas flow path in the fuel cell and constitutes an outer shell of a single cell is exposed to a corrosive atmosphere. Therefore, it is required to be a chemically stable material, high electronic conductivity and mechanical strength of the material itself, and in general, a carbon-based material such as dense carbon graphite is mainly used.

However, the carbon separator has a problem in that the cost for manufacturing the separator is high because of problems in manufacturing, molding and processing.

As a means for solving such a problem, a separator in which an anode gas flow path and a cathode gas flow path are formed by pressing a metal plate is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-18.
No. 0883 publication.

[0005]

However, the separator formed by pressing a metal plate has a problem that it is difficult to reduce the cross-sectional area of the gas flow path when compared with a cutting separator because of structural problems in the structure. With a separator made of a metal press plate, ribs are formed by pressing and a gas flow path is formed between adjacent ribs, so it is difficult to process the structure to narrow the gas flow path. Therefore, it is difficult to increase the gas linear velocity.

Further, it is difficult to secure the contact area between the electrode diffusion layer and the separator rib provided on the separator. This is because the electrode diffusion layer and the separator rib are brought into close contact with each other by tightening pressure from the outside in the battery, but the external tightening pressure is not directly transmitted to the electrode diffusion layer in the gas flow path part where the separator rib is not in close contact, The pressure is released locally. In such a non-adhered portion, there is a problem that the electrode and the electrode diffusion layer are not sufficiently adhered to each other and the flow of electrons becomes discontinuous and the resistance becomes high.

An object of the present invention is to use a metal plate as a separator material, which is one of the high cost factors for polymer electrolyte fuel cells, and to press the basic structure by a processing method that enables mass production. It is to provide a fuel cell including the produced separator.

Another object of the present invention is to provide a polymer electrolyte fuel cell using a separator made by press working, which has a separator shape and cell performance equivalent to those of a carbon plate machined product.

[0009]

In order to solve the above problems, a separator of the present invention or a fuel cell using the separator is provided with an electrolyte membrane having ion conductivity, an electrode in contact with the electrolyte membrane, and an anode gas. Alternatively, it has an electrode diffusion layer that guides the cathode gas, and a separator that prevents mixing of the feed gas of the anode gas or the cathode gas, and the separator is
It is characterized in that it has a wavy convex rib, and the convex rib is composed of a corrugated electron conductive plate having electronic conductivity and a resin rib covering the plate.

The separator of the present invention is characterized in that it has a convex dummy rib made of resin between the convex rib and another convex rib adjacent to the convex rib in the same plane. The surface of the convex rib having electron conductivity is covered with a uniform layer containing an electron conductive material.

Further, the gas passage groove provided in the separator of the present invention is characterized by being formed by a convex rib and a convex dummy rib adjacent thereto.

Further, the separator of the present invention is constituted by having a plurality of separator blocks in which convex ribs and convex dummy ribs are formed, and is planarly connected to form a bent gas flow path. To do.

The method for producing a separator or a fuel cell of the present invention comprises a first step of forming a metal plate into a corrugated shape by press working, and exposing at least a part of the convex surface of the formed metal plate to the rib surface. And a second step of forming a material containing at least a resin between the exposed ribs of the convex portion of the metal plate and the ribs adjacent to each other in the same plane, and the second step is a convex dummy rib. Third to place in a mold that can form
And a fourth step of compounding a resin material with the above-mentioned molded metal plate by injection molding.

In another manufacturing method, a preliminarily formed dummy rib, a rib piece made of a material containing at least a plurality of resins having a plurality of gas passage grooves, and a flat or corrugated metal plate are pressure-bonded. The first step,
A second step of exposing a part of the surface of the metal plate to the rib surface and forming at least one or more resin dummy ribs between the adjacent exposed ribs in the same plane of the exposed ribs; Characterize.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A separator that separates an anode gas and a cathode gas in a fuel cell (PEFC) to form a gas flow path in the fuel cell and constitutes an outer shell of a unit cell is exposed to a corrosive atmosphere. Therefore, a chemically stable material is required. Furthermore, the high electronic conductivity of the material itself,
It must also have some mechanical strength. Considering these restrictions, carbonaceous materials such as dense carbon graphite are mainly used for the current PEFC separator.

However, the carbon separator has the following problems in production, molding, and processing, so that the separator production cost becomes high.

(1) The carbon-based material is obtained by firing a resin or the like, but the temperature is a thousand and several hundred degrees, and it is necessary to input a large amount of energy, and the raw material inevitably becomes expensive.

(2) The separator requires a passage for gas and water vapor, but it is difficult to cut and process because the carbonaceous material has a high hardness.

(3) In order to prevent the anode gas and the cathode gas of adjacent cells from being mixed with each other and the anode gas containing hydrogen from leaking out of the cell, the separator itself must not allow the gas to pass therethrough. The gas separation ability of is not perfect. For this reason, a step of impregnating the voids of the carbon separator with a phenolic resin or the like is necessary after the separator shape is formed.

Therefore, it is effective to use a metal material as a material for producing a separator at low cost. Particularly, a separator in which an anode gas flow path and a cathode gas flow path are formed by pressing a metal plate is effective in reducing materials and processing cost. As an example of a separator using a metal plate, Japanese Patent Application Laid-Open No. 8-180883 can be cited.

However, it is difficult to improve the battery performance of a separator formed by pressing a metal plate, as compared with a cutting separator, because of structural problems in forming. The problem is shown below.

First, it may be difficult to reduce the cross-sectional area of the gas passage. That is, in the polymer electrolyte fuel cell, water is produced by the cathode reaction. The generated water maintains the low ionic conductivity of the membrane by wetting the electrolyte membrane, but if it stays in the electrode or diffusion layer, it will impede the diffusion of the feed gas and prevent the chemical reaction from proceeding smoothly, thus limiting the current density of the battery. Lower. In order to suppress this phenomenon, a method of increasing the gas linear velocity of the supply gas in the battery and carrying the generated water away from the battery system is effective. Structurally, it is common to bend the gas flow path in the plane of the cell to reduce the cross-sectional area of the flow path, for example, a serpentine shape.

In a separator made of a metal press plate, ribs are formed by pressing and a gas flow path is formed between adjacent ribs. Since the ribs provided on the metal plate are required on the anode side and the cathode side, the protrusions are periodically repeated on the front and back sides. If it is a convex portion on the front surface, it functions as a concave portion on the back surface, that is, as a gas flow passage, and it is difficult in terms of processing to realize a structure for narrowing this gas flow passage. That is, it is difficult to increase the gas linear velocity in the battery.

Second, it is difficult to secure the contact area between the electrode diffusion layer and the separator rib. This is because the electrode diffusion layer and the separator rib are in close contact with each other in the battery due to external tightening pressure. Electrons involved in the reaction at the electrode pass through the electrode, the electrode diffusion layer and the separator rib in the battery thickness direction.
At this time, the external tightening pressure is not directly transmitted to the electrode diffusion layer in the portion where the separator ribs are not in close contact, that is, in the gas flow passage portion, and the pressure is locally released. In this portion, the adhesion between the electrode and the electrode diffusion layer is insufficient and the electron flow becomes discontinuous, that is, the resistance becomes high.

One way to secure the battery performance is to reduce such a portion in the battery as much as possible.
In the case of a metal press plate separator, it is difficult to increase the contact area between the electrode diffusion layer and the separator rib because of the above-mentioned difficulty of processing.

Further, when the convex rib is formed by pressing the metal plate, the end of the convex portion cannot be formed at a right angle, resulting in a round shape having some radius. Since the area of the flat portion of the tip is limited with a round rib, the press working is also disadvantageous in this respect as compared with the cutting work capable of forming a rib having a substantially right angle.

In order to achieve the above object, the inventors of the present invention will describe a method of forming a fuel cell separator by a simple processing method of an inexpensive metal-based material, a separator using a metal plate and a fuel cell using the same. Explained.

In the present invention, the gas flow is made of a material containing at least the resin 1 while ensuring the electron conductivity of the corrugated electron conductive plate 7 formed by corrugating a metal plate or the like and the convex ribs of the corrugated electron conductive plate. The above-mentioned problems can be achieved by the composite separator having the anode gas flow channel 5 and the cathode gas flow channel 6 which are the channel grooves.

As the metal used here, a material having high electron conductivity and easy to process is desirable. For example, iron, copper,
Aluminum, tin, nickel, titanium, lead, chromium,
Examples of usable materials include silver, gold, platinum, palladium, cobalt and zinc.

Further, alloy materials based on the above materials,
Materials obtained by doping the above materials with various transition metals such as tungsten can also be used.

Since the internal resistance of the battery increases when corrosion products are generated on the metal plate, it is desirable that the material used has high corrosion resistance. From this point of view, stainless steel materials, various clad materials, and surface-treated steel sheets are particularly preferable. It is particularly preferred to use.

The resin material to be combined with the metal corrugated plate is epoxy resin, polyimide resin, polyamide resin, phenol resin, polyolefin resin, polyester resin, polycarbonate resin, polystyrene resin, polysulfone resin, acrylic resin, polyphenylene ether resin. , Polyphenylene sulfide resin, polyether ether ketone resin, etc. can be used. These resins can be used alone or in combination of two or more.

In the above separator, the corrugated electron conductive plate 7 is used.
At least a convex dummy rib 9 made of a material containing at least a resin is provided between the convex ribs having electron conductivity formed on the surface of and the adjacent convex ribs having electron conductivity in the same plane. It is desirable to arrange one or more.

By forming the dummy ribs, it is possible to reduce the cross-sectional area of the gas passage and increase the gas linear velocity in the battery, and as a result, it is possible to improve the diffusivity of the reaction gas.

Further, since the contact area between the separator rib and the electrode 3 and the diffusion layer 2 is increased, the tightened state is improved and the contact resistance is reduced.

The separator of the present invention has conductivity in the thickness direction by ensuring the electronic conductivity of the tip surfaces of the convex ribs formed on the front and back surfaces thereof. However, due to long-term power generation,
Corrosion products may be formed on the tip surfaces of the convex ribs to increase resistance.

It has been found that in order to suppress this phenomenon, the tip end surface of the convex rib should be covered with the protective uniform layer 10 having corrosion resistance and electron conductivity. By adopting the protective uniform layer, it becomes possible to manufacture a stable battery in which the internal resistance does not increase even in the long-term power generation test.

The separator of the present invention can reduce the gas flow passage cross-sectional area by forming dummy ribs. Further, by changing the shape of the dummy rib, it becomes easy to control the parameters related to the gas flow path. It is desirable that the width of the gas flow channel groove be smaller from the viewpoint of increasing the contact area between the separator rib, the electrode and the diffusion layer. The depth of the gas passage groove is preferably shallow because it increases the linear velocity of the gas.

According to the study by the inventors, a separator designed by designing a gas channel groove width of 1.2 mm or less and a channel depth of 1.0 mm or less has improved performance and life during power generation. Became clear.

When the fuel cell is used as a small distributed power source or a power source for an electric vehicle, a compact size is required from the viewpoint of space utility for arranging the cell.

For this purpose, it is necessary to improve the battery performance to increase the output density and to make the constituent materials thinner.

The separator of the present invention can be made thinner by designing a corrugated metal plate, but if the thickness of the metal plate is large, the radius of the bent portion will be large, and the thickness of the corrugated plate will increase. It has been found that it is possible to achieve a separator thickness of 2.5 mm or less by using a corrugated metal plate of 0.4 mm or less. The use of such a thin metal plate is also desirable from the viewpoint of reducing the weight of the separator.

The protective uniform layer having corrosion resistance and electron conductivity on the tip surface of the convex rib is effective for suppressing an increase in resistance, but since the manufacturing cost of the separator is reduced, an inexpensive material can be manufactured by a simple process. It is necessary to form a layer with.

It has been found that a carbon paste is prepared by using carbon powder as an electron conductive filler, a fluororesin material and an organic solvent as a binder, and the paste is applied to the tip surface of the convex rib. It was found that the separator manufactured by this method showed almost no increase in the resistance of the electron conducting portion with the passage of time.

A separator block, which is a constituent part of a separator having a wavy metal plate and a convex dummy rib formed of a material containing at least a resin, is produced, and the block is arranged in a plane without discontinuity of gas flow paths. As a result, a serpentine (bellows) type separator having a gas flow channel bent in the plane of the battery can be manufactured.

In order to improve the limiting current density of the battery, the separator of the present invention employs a serpentine type gas passage which can greatly reduce the cross-sectional area of the gas passage.

In the separator of the present invention, the resistivity of the separator itself is reduced by adding the conductive filler to the resin which is a part of the separator forming material.

As a result, a battery having a small internal resistance and good performance can be realized.

The conductive filler added to the resin is preferably 5 wt% or more and 55 wt% or less with respect to the amount of resin. This is because if the amount of the filler is less than 5 wt%, the effect of lowering the resistance cannot be obtained, and conversely, if an excessive amount of more than 55 wt% is added, the hydrogen separation characteristic as the separator deteriorates.

In contrast to the cutting separator of a dense graphite plate, which has conventionally been expensive in terms of both raw material and processing cost, the raw material cost of a composite separator mainly made of a corrugated metal plate and a resin and having convex ribs of the metal plate and resin dummy ribs. Is significantly lower.

However, in order to reduce the total cost as a separator, a continuous manufacturing method with high productivity is required.

In the separator of the present invention, one or a plurality of corrugated metal plates are set in a mold corresponding to the shape of the rib prepared in advance, and the resin is injected to form the gas flow channel groove. At the same time, the formation of the gas seal frame located outside the electrode surface is completed at the same time, so that efficient production is possible.

As yet another manufacturing method, a plurality of resin rib piece pieces made of a material containing at least a resin having dummy ribs and one or more gas flow passage grooves are prepared in advance and processed into a flat plate shape or a wavy metal shape. By performing pressure bonding with the plate, the separator of the present invention can be efficiently manufactured.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Example 1) SUS304 having a thickness of 0.5 mm
By pressing, a 7 mm pitch wavy unevenness is formed, and an electrode area with a wavy projection in the center of the flat plate is 9.8 cm ×
A 9.8 cm specification separator substrate was produced.

Separately from this, polyphenylene sulfide
The (PPS) resin was processed to produce 28 resin pieces each having one gas flow channel groove having a length of 9.8 cm and a depth of 1.2 mm.

Epoxy adhesive was evenly applied to the surface of the separator substrate other than the tip surface of the convex portion, and a corrugated metal was formed on 14 resin pieces arranged with the adhesive surface facing upward with a spacing of 2.9 mm. The plate was left stationary and pressure-bonded to form an anode gas flow channel.

After the completion of the pressure bonding, another 14 resin pieces were arranged in the same manner, and the metal plate which was turned upside down was pressure bonded and bonded to form a cathode gas flow path on the opposite surface of the metal.

A frame-shaped seal frame having an internal manifold hole around the wavy convex portion of the separator substrate was bonded to each of the anode side and the cathode side to form a gas seal frame, an anode manifold, a cathode manifold, and a cooling water hole in the separator substrate.

The produced separator has a gas channel length of 9.8 cm, gas channel groove width of 3.5 mm and gas channel groove depth of 1.2.
mm, equipped with 14 channels on the anode and cathode sides,
Its thickness was 5.0 mm.

Anode (platinum-ruthenium alloy-supported carbon, 0.5 mg Pt-Ru / cm ² ) and cathode (platinum-supported carbon, 0.3 mg / cm ² ) were formed on the surface of a DuPont Nafion membrane (ion exchange capacity 0.91 meq / g). ² ) The electrolyte membrane / electrode assembly formed with ² ) is impregnated with a polytetrafluoroethylene (PTFE) dispersion aqueous solution and dried to disperse water-repellent carbon paper having a thickness of 0.4 mm so as to overlap the electrodes. Two sheets of the separator of the present invention were arranged on the outside.

Further, a copper current collector plate having a surface subjected to anticorrosion treatment, a PTFE insulating sheet, and a stainless steel end plate were sequentially laminated, and finally tightened with bolts and nuts to prepare a test cell.

The test cell was set in a constant temperature bath, and an anode / cathode gas supply line having a heater function for heating, a gas outlet line having an outlet pressure adjusting valve and a temperature keeping heater were connected to each other.

A liquid mass flow controller was used for humidifying the supply gas. An electronic load was connected to this test cell, the temperature was 70 ° C, the fuel utilization rate was 0.75, and the oxygen utilization rate was 0.7.
Current-voltage data at 4 was collected. In addition, the change with time of voltage under a rated load with a current density of 0.2 A / cm ² was measured.

FIG. 2 is a partial sectional view of a test cell assembled by using the first embodiment. Electrons generated / consumed by the electrode reaction have a structure of flowing in the thickness direction of the corrugated metal plate.

(Comparative Example 1) A SUS304 plate having a height of 13.5 cm and a thickness of 5 mm was prepared, and the central portion was 9.8 cm ×
Considering the electrode part as 9.8 cm, gas channel groove depth 1.2 mm,
A gas separator having a groove width of 3.5 mm and a length of 9.8 cm was formed by cutting to prepare a metal separator.

The shape of this separator is the same as that of the first embodiment. Using this separator, a test cell was prepared and set in the same device as in Example 1, and the current-voltage data and the voltage aging at a rated load of a current density of 0.2 A / cm ² were measured.

FIG. 3 shows the results of measuring the change with time in voltage under rated load in Example 1 and Comparative Example 1. 5 in Comparative Example 1
While the cell voltage sharply decreased after about 00 hours, in Example 1, the cell voltage could be kept constant up to about 2000 hours. In Comparative Example 1, since the gas flow path in the battery is entirely made of metal, metal ions are eluted under a corrosive atmosphere during power generation and ion exchange with the electrolyte membrane material increases the internal resistance of the battery. This is to allow it. On the other hand, in Example 1, the metal portion other than the surface in contact with the diffusion layer is covered with the resin, and the eluted metal ions can be suppressed, so that the cell voltage can be stabilized.

(Example 2) PPS resin was processed to form two gas flow channels having a length of 9.8 cm, a depth of 1.2 mm and a groove width of 1.35 mm, and a length of 9.8 cm and a depth of 1. Twenty-eight resin pieces having one dummy rib having a width of 2 mm and a width of 0.8 mm were manufactured.

A resin piece was pressure-bonded along the anode and cathode side projections of a separator substrate manufactured in the same manner as in Example 1, and a gas seal frame was bonded to form a separator.

This separator has a length of 9.
8 cm, gas channel groove width 1.35 mm, gas channel groove depth 1.2
mm, equipped with 28 channels on the anode and cathode sides,
Its thickness was 5.0 mm.

A test cell was prepared using this separator,
The device was set in the same device as in Example 1 and current-voltage data was measured under the same conditions.

FIG. 4 shows current-voltage curves of Example 1 and Example 2. It can be seen that the voltage decrease with respect to the current density is small in Example 2 as compared with Example 1. This is presumed to be because the dummy ribs formed in Example 2 could adjust the cross-sectional area of the gas flow path, and the reaction resistance of the electrode reaction could be reduced by increasing the linear velocity of the gas flowing in the battery. It

Example 3 A gold paste was screen-printed on the tip ends of the ribs of the bipolar plate having electron conductivity of the separator prepared in the same manner as in Example 2 and naturally dried for 1 hour. The gold paste layer after drying was measured to be about 30 μm.

Current-voltage data of a test cell manufactured using this separator was collected.

Further, the change with time of voltage under a rated load with a current density of 0.2 A / cm ² was measured.

FIG. 5 shows the results of measuring the change with time of the voltage under rated load in Examples 1 and 3. In Example 3, the surface of the separator rib having electron conductivity is coated with a gold paste layer to suppress the dissolution reaction of SUS304. As a result, in Example 1, a decrease in cell voltage was observed after 2000 hours, whereas in Example 3, performance could be maintained up to about 4000 hours.

(Example 4) A PPS resin was processed into a gas passage 2 having a length of 9.8 cm, a depth of 1.0 mm and a groove width of 1.35 mm.
Twenty-eight resin rib pieces 17 having one book and one dummy rib having a length of 9.8 cm, a depth of 1.2 mm and a width of 0.8 mm were produced.

A resin piece was pressure-bonded along the protrusions on the anode and cathode sides of a separator substrate manufactured in the same manner as in Example 1, and a gas seal frame was further adhered to form a separator. Further, a gold paste was screen-printed on the tip ends of the ribs having both electronic conductivity, and naturally dried for 1 hour to form a uniform layer.

This separator has a length of 9.
8 cm, gas channel groove width 1.35 mm, gas channel groove depth 1.0
mm, equipped with 28 channels on the anode and cathode sides,
Its thickness was 5.0 mm.

A test cell was prepared using this separator,
The device was set in the same device as in Example 1 and current-voltage data was measured under the same conditions.

(Embodiment 5) A resin obtained by processing a PPS resin and having two gas flow passages each having a length of 9.8 cm, a depth of 1.0 mm and a groove width of 1.2 mm, and one dummy rib having a width of 1.1 mm. Twenty eight pieces were produced.

A resin piece was pressure-bonded along the protrusions on the anode and cathode sides of a separator substrate manufactured in the same manner as in Example 1, and a gas seal frame was further adhered to form a separator. Further, a gold paste was screen-printed on the tip ends of the ribs having both electronic conductivity, and naturally dried for 1 hour to form a uniform layer.

This separator has a length of 9.
8 cm, gas channel groove width 1.2 mm, gas channel groove depth 1.0 mm
The number of flow paths was 28 on the anode and cathode sides, and the thickness was 5.0 mm.

A test cell was prepared using this separator,
The device was set in the same device as in Example 1 and current-voltage data was measured under the same conditions.

FIG. 6 shows the current density values at the cell voltage of 0.7 V in Examples 3, 4, and 5. It was confirmed that the battery performance was improved in Example 4 in which the channel groove depth was 1.0 mm, as compared with Example 3 in which the channel groove depth was 1.2 mm. Further, in Example 5 in which the channel width was reduced from 1.3 mm to 1.2 mm, a further increase in current density was measured. This is considered to be the effect of increasing the gas linear velocity, as in the consideration in FIG.

Example 6 In the same manner as in Example 5, 28 resin pieces were prepared.

By pressing SUS304 having a thickness of 0.3 mm, corrugated irregularities having a thickness of 2.5 mm are formed at a pitch of 7 mm, and an electrode area having a corrugated protrusion at the center of the flat plate is 9.8c.
A separator substrate having m × 9.8 cm specifications was produced.

A resin piece was pressure-bonded along the respective protrusions on the anode and cathode sides of a separator substrate manufactured in the same manner as in Example 1, and a gas seal frame was further adhered to form a separator. Further, a gold paste was screen-printed on the tip ends of the ribs having both electronic conductivity, and naturally dried for 1 hour to form a uniform layer.

This separator has a length of 9.
8 cm, gas channel groove width 1.2 mm, gas channel groove depth 1.0 mm
The number of flow channels was 28 on the anode and cathode sides, and the thickness was 2.5 mm.

A test cell was prepared using this separator,
The device was set in the same device as in Example 1, and the current density was 0.2 A / c.
The change in voltage with time at a rated load of m ² was measured.

FIG. 7 shows the thickness of the separators of Example 5 and Example 6. It can be seen that the thickness of the whole separator can be remarkably reduced by reducing the thickness of the corrugated metal plate.

Example 7 As in Example 6, the separator substrate and the resin piece were pressure-bonded to each other to produce a separator.

15 wt% of carbon black having a particle size of less than 20 nm as a conductive filler, 20 wt% of PVDF as a binder, and 65 wt% of N-methylpyrrolidone as a solvent were mixed and stirred at room temperature for 3 hours.
A carbon paste was prepared.

A carbon paste was screen-printed on the tip surfaces of the ribs of both electrodes having electronic conductivity, and dried under reduced pressure at 140 ° C. for 3 hours to form a uniform layer. The thickness of the carbon layer at this time was 33 μm.

This separator has a length of 9.
8 cm, gas channel groove width 1.2 mm, gas channel groove depth 1.0 mm
The number of flow channels was 28 on the anode and cathode sides, and the thickness was 2.5 mm.

A test cell was prepared using this separator,
The device was set in the same device as in Example 1, and the current-voltage data and the change with time in voltage at a rated load of current density of 0.2 A / cm ² were measured. Further, the sheet resistance in the thickness direction of the separator was measured.

FIG. 1 shows a partial sectional view of a test cell using Example 7 and a sectional view of a resin rib used. Since the rib tip end surface in contact with the diffusion layer is coated with a uniform layer containing carbon and a binder, it is particularly excellent in suppressing elution of metal ions and its durability.

FIG. 8 shows the results of measuring the change with time in voltage at the rated load of the test cells using Examples 7 and 6. Since the uniform layer on the rib tip surface used in Example 6 is a layer in which gold paste is applied and dried, the gold paste layer itself gradually dissolves with the lapse of power generation time, and finally SUS304 forming a separator. It becomes impossible to suppress the elution of metal ions from the solution. As a result, the battery performance deteriorates after about 4000 hours, but in Example 7 in which the highly stable carbon paste layer was used as the uniform layer, the elution of metal ions was suppressed for a long period of time, and therefore the life was improved up to about 8000 hours. Was confirmed.

(Embodiment 8) SUS having a plate thickness of 0.3 mm, which is roughly processed into two triangles, one parallelogram and two trapezoids.
304 was pressed to form wavy unevenness with a pitch of 7 mm and a thickness of 2.5 mm on each plate (12, 13, 14, 1).
5, 16). When these corrugated sheets are combined, 9.8x9.
The structure is a square of 8 cm ² , and the structure is such that the reaction gas supplied into the cell surface from the gas internal manifold arranged in the diagonal position turns twice in the direction of 180 degrees.
As shown in.

The resin pieces were pressure-bonded along the respective protrusions on the anode and cathode sides of the plurality of separator substrates thus produced. The resin piece was rough-processed in advance according to the shape of the corrugated plate, then subjected to a pressure bonding step, and then subjected to final shape finishing.

Five separator substrates were bonded in a square shape, and a gas seal frame was further bonded to form a separator. A carbon paste prepared in the same manner as in Example 7 was screen-printed on the tip ends of the ribs of both electrodes, and dried under reduced pressure at 140 ° C. for 3 hours to form a uniform layer. The thickness of the carbon layer was 31 μm.

This separator has a length of 3 as a gas flow path.
The gas channel groove width was 0.39 cm, the gas channel groove depth was 1.0 mm, and the number of channel channels was 10 on the anode and cathode sides, and the thickness was 2.5 mm.

A test cell was prepared using this separator,
The same device as in Example 1 was set and the current-voltage data was measured.

FIG. 9 shows a plan view of the separator electrode surface produced in Example 8. This separator is composed of five partial blocks, and has a structure in which the reaction gas turns twice in the direction of 180 degrees. As a result, the number of gas flow paths can be reduced from 28 to 10, so that the gas linear velocity can be increased. Further, according to the structure in which the separator is divided into block parts like this, the number of gas flow paths can be reduced and the workability can be improved.

FIG. 10 shows the results of measuring the current-voltage curves of the test cells produced using Example 7 and Example 8. In Example 8 in which the gas flow passage cross-sectional area was greatly reduced, the cell voltage decrease was small even at high current densities, and it was confirmed that the limiting current density was significantly improved.

(Example 9) The particle size was 20 with respect to the PPS resin.
45 wt% of carbon black of nm or less was added, and a resin piece was prepared by using these as raw materials, and the separator substrate and the resin piece were pressure-bonded in the same manner as in Example 7 to produce a separator.

A carbon paste was screen-printed on the tip surfaces of the ribs of both electrodes having electronic conductivity in the same manner as in Example 7, and dried under reduced pressure at 140 ° C. for 3 hours to form a uniform layer. The thickness of the carbon paste layer was 32 μm.

This separator has a length of 9.
8 cm, gas channel groove width 1.2 mm, gas channel groove depth 1.0 mm
The number of flow channels was 28 on the anode and cathode sides, and the thickness was 2.5 mm.

This separator is sandwiched between two silver plates to make 1.0M.
The resistance between the silver plates is 1KH while applying a tightening load of Pa.
It was measured with a z AC resistance measuring device.

FIG. 11 shows the relative comparison values of the separator resistance values of Example 7 and Example 9. In Example 9, it was confirmed that the resistance of the separator itself was reduced. This is because the addition of carbon black to the resin increased the paths of electrons flowing through the separator. If the resistance of the separator decreases, the internal resistance of the battery also decreases, so that improvement in battery performance can be expected.

[0112]

According to the present invention, the cell voltage can be kept constant for a long time.

Further, according to the present invention, since the portion of the metal separator other than the surface in contact with the diffusion layer is covered with the resin, the elution of metal ions can be suppressed, the internal resistance can be hardly increased, and the durability is improved. Can be made.

Further, in the present invention, it is possible to adjust the cross-sectional area or surface area of the gas flow passage to be small, and the linear velocity of gas can be increased. by this,
The reaction resistance of the electrode reaction can be reduced, and the voltage reduction with respect to the current density can be reduced. It also increases the current density, thus improving battery performance.

According to the present invention, it becomes possible to keep the thickness of the entire separator, and consequently the size of the battery cell and the size of the fuel cell small.

According to the present invention, it is possible to reduce the number of gas flow paths and improve workability. Further, according to this, even when the current density is high, the cell voltage decrease is small, and the limiting current density can be greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic structure of a battery of the present invention and a sectional view of a resin rib used.

FIG. 2 is a diagram showing a schematic structure of a battery which is another embodiment of the present invention.

FIG. 3 is a graph comparing changes in cell voltage with time of Example 1 of the present invention and Comparative Example 1.

FIG. 4 is a diagram comparing current-voltage curves of Examples 1 and 2 of the present invention.

FIG. 5 is a diagram comparing changes in cell voltage with time in Examples 1 and 3 of the present invention.

FIG. 6 is a table comparing the current densities of Examples 3, 4 and 5 of the present invention at 0.7V.

FIG. 7 is a table comparing separator thicknesses for Examples 5 and 6 of the present invention.

FIG. 8 is a diagram comparing changes in cell voltage with time in Examples 6 and 7 of the present invention.

FIG. 9 is a plan view of an electrode portion of the separator according to the eighth embodiment of the present invention.

FIG. 10 is a diagram comparing current-voltage curves of Examples 7 and 8 of the present invention.

FIG. 11 is a table showing relative resistance values in the thickness direction of the separators of Examples 7 and 9 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Resin or resin rib or separator rib, 2 ... Diffusion layer, 3 ... Electrode, 4 ... Electrolyte membrane, 5 ... Anode gas flow path, 6 ... Cathode gas flow path, 7 ... Corrugated electron conductive plate, 8
... Separator, 9 ... Dummy rib, 10 ... Uniform coating layer, 1
DESCRIPTION OF SYMBOLS 1 ... Rib tip surface having electronic conductivity, 12 ... Trapezoid separator part A, 13 ... Trapezoid separator part B, 14 ... Triangle separator part C, 15 ... Triangle separator part D,
16 ... Parallelogram separator parts, 17 ... Resin rib pieces.

Claims (11)

[Claims] 1. A separator for preventing mixing of an electrolyte membrane having ion conductivity, an electrode in contact with the electrolyte membrane, an electrode diffusion layer for guiding an anode gas or a cathode gas, and a supply gas of the anode gas or the cathode gas. And a sealing material for preventing leakage of the anode gas or the cathode gas and cooling water, and the separator covers the corrugated electron conductive plate having a corrugated convex rib and the electron conductive plate. A fuel cell comprising resin ribs, wherein convex ribs on the front and back surfaces of the corrugated electron conductive plate have electron conductivity with each other. 2. The separator has a rib having an electron conductivity, which is formed on the surface of the wavy electron conductive plate.
The at least one convex dummy rib made of a resin-containing material is arranged between adjacent convex ribs having electron conductivity in the same plane. Fuel cell. 3. A convex rib formed on the corrugated electron conductive plate, wherein at least a surface of the convex rib having electron conductivity is covered with a uniform layer containing an electron conductive material. The fuel cell according to claim 1 or 2, characterized in that. 4. A gas channel groove formed by a convex rib of the corrugated electron conductive plate and a convex dummy rib adjacent to the convex rib and made of a material containing at least a resin, or
The gas passage groove formed by a plurality of convex dummy ribs made of a material containing at least a resin is characterized in that the passage width at half the depth of the gas passage groove is smaller than 1.2 mm. The fuel cell according to claim 2 or 3. 5. A gas flow path groove formed by a convex rib of the corrugated electron conductive plate and a convex dummy rib adjacent to the convex rib and made of a material containing at least a resin, or containing at least a resin. The depth of the gas channel groove formed by a plurality of convex dummy ribs made of a material is 1.0 mm
It is smaller than 4.
The fuel cell described. 6. The fuel cell according to claim 5, wherein the corrugated electron conductive plate has a plate thickness of 0.4 mm or less. 7. The electron conductive material forming the uniform layer for covering the convex ribs formed on the wavy electron conductive plate contains at least a carbon material. The fuel cell according to item 1. 8. The separator is formed of a material containing at least a convex rib formed on the surface of the corrugated electron conductive plate, having electron conductivity, and having a surface coated with an electron conductive uniform layer. It is configured to have a plurality of separator blocks formed with the convex dummy ribs formed, the plurality of separator blocks are planarly connected to form a bent gas flow path. 7. The fuel cell according to 7. 9. A resin to be combined with the corrugated electron conductive plate, wherein the resin has an electron conductive filler in a resin weight ratio of 5 w.
The fuel cell according to claim 7, wherein the fuel cell contains t% or more. 10. A first step of forming a metal plate into a corrugated shape by press working, and exposing at least a part of the convex surface of the molded metal plate to the rib surface to expose the convex portion of the metal plate. A second step of forming a material containing at least a resin between the rib and an adjacent rib in the same plane, and the second step is a third step of arranging in a mold capable of forming a convex dummy rib. And a fourth step of compounding a resin material with the above-mentioned molded metal plate by injection molding. 11. A first step of crimping a preformed dummy rib, a rib piece made of a material containing at least a plurality of resins having a plurality of gas flow channels, and a flat or corrugated metal plate. A second step of exposing a part of the surface of the metal plate to the rib surface and forming at least one or more resin dummy ribs between the adjacent exposed ribs in the same plane of the exposed ribs; A method for manufacturing a characteristic separator.