JPH11312530A - Solid polymer electrolyte type fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damages to an electrode or the like due to, excessive increase of pressure applied between a separator and the electrode due to swelling of a membrane from being generated, and to facilitate pressure control. SOLUTION: This is a solid polymer electrolyte type fuel cell in which electrodes 103, 105 are arranged in both sides of a solid polymer electrolyte membrane 101, a fuel gas is supplied to one-side faces of the electrodes 103, 105, and in which unit cells comprising two separators 201, 202 for supplying an oxidant gas is plurally stacked in the other side faces of the electrodes 103, 105. Plate members 301, 302 comprising corrugated spring materials are interposed between both the separators 201, 202 and the fuel electrodes 103, 105, a plurality of the first free spaces 401 formed by one separator 201 and the electrode 103 is formed for fuel gas flow channels, and a plurality of the second free spaces 402 formed by the other separator 202 and the oxidant electrode 105 is formed for oxidant gas flow channels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art Various types of fuel cells, such as a solid polymer electrolyte type, a phosphoric acid type, a molten carbonate type, and a solid oxide type, are known depending on the type of electrolyte used. Among them, the solid polymer electrolyte fuel cell is a fuel cell utilizing the fact that a polymer electrolyte membrane having a proton exchange group in a molecule functions as a proton conductive electrolyte when saturated with water, and has a relatively low temperature. It operates in a wide range and has excellent power generation efficiency, and is expected to be used in various applications, including those used in electric vehicles.

In a polymer electrolyte fuel cell, a plurality of unit cells (unit cells) for generating electric power by an electrochemical reaction are stacked,
By holding it under pressure, a battery (stack) is formed. The unit cell is composed of a polymer electrolyte membrane, an anode (fuel electrode) and a cathode (oxidant electrode) joined to both sides thereof. For stacking, a member called a separator is provided between each unit cell. The separator is provided with a gas flow groove through which oxygen or hydrogen flows.

In a polymer electrolyte fuel cell, a mixed gas of hydrogen, carbon dioxide, nitrogen and water vapor is supplied to an anode side, and air and water vapor are supplied to a cathode side.

The temperature of each gas is in a high temperature state of 80 to 90 ° C., and the separator is required to have high heat resistance by being exposed to each gas.

In addition, since the separator electrically connects the cells, high electrical conductivity and low contact resistance with constituent materials are required.

As prior art 1, Japanese Patent Application Laid-Open No. 9-27492
No. 6 discloses a combination of a cell and a separator. In polymer electrolyte fuel cells, a polymer electrolyte membrane made of water absorption is used as the electrolyte.This membrane has the property of expanding due to water absorption, and excessive pressure is applied between the separator and the electrode, causing damage to the anode and cathode. However, in the prior art 1, there is a problem in that a pair of electrodes composed of an electrode catalyst layer and an electrode substrate are disposed on both main surfaces of the polymer electrolyte membrane. The joined body and the tips of the plurality of ribs formed on one main surface are disposed facing the outer surface of the electrode base material of the joined body, and a groove formed between the ribs serves as a gas flow groove. In a polymer electrolyte fuel cell provided with a separator, a technique is disclosed in which a conductive elastic structure made of conductive silicone rubber is provided at the tips of a plurality of ribs.

As prior art 2, Japanese Patent Application Laid-Open No. 9-22708
According to the publication, a unit cell of a polymer electrolyte fuel cell uses a separator having a flat body serving as a structure for stress relaxation on the top of each holder or the like. A structure is disclosed in which the flat body is manufactured using a stainless steel plate of the same type as the holding body or the like, and is fixed to the top of the holding body or the like using welding or the like.

As prior art 3, Japanese Patent Application Laid-Open No. Hei 9-11553
In Japanese Patent Application Publication No. 2001-139, an edge spring and a manifold spring interposed between a separator plate and an edge plate that is in surface contact with an electrolyte plate are formed by plate-like springs having substantially the same spring characteristics. Techniques are disclosed.

[0010]

However, the prior art 1 not only has the effect of securing the conductivity but also has the effect of relaxing the stress due to the swelling of the polymer electrolyte membrane. This leads to increased costs due to poor quality and material cost.

In the prior art 2, the pressure applied to the membrane is reduced in the outer peripheral holding portion. However, stress is applied to the electrode member, which may cause damage to the electrode member.

Further, the prior art 3 is not provided at the contact portion with the electrode material portion, and this technology also has a risk of damaging the electrode material.

As described above, as a whole of the prior art, as shown in FIG.
In order to keep the contact resistance between the cells 103 and 105 low, a certain pressing force (for example, 50 kg / cm 2, a pressing force of 1 ton for the entire fuel cell) is applied to the stacked cells 103 and 105 and the separators 901 and 902. . FIG. 4 shows a fuel cell in which a plurality of unit cells S are stacked, and the stacked fuel cells are fastened in multiple directions by bolts B at a plurality of angles A. Was a difficult task.

In a polymer electrolyte fuel cell, a polymer electrolyte membrane is used as an electrolyte constituting the cell. This membrane is hygroscopic and exhibits good proton conductivity in a state containing water. For this reason, humidified hydrogen gas flows through the anode side to give moisture to the membrane. It is also humidified by the reaction water on the anode side. However, the polymer electrolyte membrane expands due to moisture absorption and the thickness increases.

For example, as a polymer electrolyte type membrane, a perfluorocarbon polymer membrane having a sulfonic acid group (trade name;
(Nafion 112, DuPont Co., Ltd.) and the film thickness was measured at a water absorption of 100%.
The thickness of 0 μm increased to 60 μm, and the pressing force of one ton increased to 2-3 times. As described above, in the fuel cell having the stacked and pressurized configuration,
The film thickness increases due to moisture absorption in the polymer electrolyte membrane, and the pressing force between the cell and the separator further increases, thereby causing damage to the electrode material of the cell.

The present invention has solved the above-mentioned problems, and solves the problem that the pressure applied between the separator and the electrodes (anode and cathode) is excessively increased due to the swelling of the membrane, causing damage to the electrodes and the like. A polymer electrolyte fuel cell that facilitates management is provided.

[0017]

Means for Solving the Problems In order to solve the above technical problems, the technical means (hereinafter referred to as first technical means) taken in claim 1 of the present invention is a solid polymer electrolyte. An electrode is arranged on both sides of the membrane, a fuel gas is supplied to one side of the electrode, and a plurality of unit cells composed of two separators are supplied to the other side of the electrode to supply an oxidizing gas. In a polymer electrolyte fuel cell, a plate member made of a wavy spring material is interposed between the two separators and a fuel electrode, and a plurality of first separators formed by the one separator and the fuel electrode are provided. The gap is formed as a fuel gas passage groove, and the plurality of second gaps formed by the other separator and the oxidant electrode are formed as oxidant gas passage grooves. It is a molecular electrolyte fuel cell.

The effects of the first technical means are as follows.

That is, the pressure applied between the separator and the electrodes (anode, cathode) excessively increases due to swelling of the membrane,
This has the effect of solving problems such as the occurrence of electrode damage and facilitating pressure management.

In order to solve the above technical problem, the technical means (hereinafter referred to as first technical means) taken in claim 2 of the present invention is that the spring material is an iron-based spring material, 2. The solid polymer electrolyte fuel cell according to claim 1, wherein the solid polymer electrolyte fuel cell is made of a stainless spring material or a conductive resin material obtained by mixing a metal with a resin.

The effects of the second technical means are as follows.

That is, by using the above-mentioned material, there is an effect that the pressurization between the electrode and the separator can be efficiently absorbed.

In order to solve the above-mentioned technical problem, the technical means (hereinafter referred to as third technical means) taken in claim 3 of the present invention is that the surface of the spring material has gold,
The solid polymer electrolyte fuel cell according to claim 1, wherein a noble metal plating coating such as platinum or palladium is applied.

The effects of the third technical means are as follows.

That is, by this means, the plate material can have heat resistance and moisture resistance under an environment where the temperature is around 80 ° C. and the humidity is high.

In order to solve the above technical problem, the technical means taken in claim 4 of the present invention (hereinafter, referred to as fourth technical means) is that the surface of the spring material is made of Cr
The solid polymer electrolyte fuel cell according to claim 1, wherein a coating of N, TiN, ZrN, or the like is applied.

The effects of the fourth technical means are as follows.

That is, similar to the third aspect, this means enables
The plate material can have heat resistance and moisture resistance under an environment where the temperature is about 0 ° C. and a high humidity environment is set.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

FIG. 1 shows a unit cell 100 of a fuel cell according to the present invention.
FIG. The unit cell 100 has a structure in which a solid polymer electrolyte membrane 101 is sandwiched between a fuel electrode 103 and an oxidant electrode 105 and is sandwiched between separators 201 and 202. A plurality of the unit cells are stacked to form a fuel cell.

Between the separators 201 and the fuel electrode, plate members 301 and 302 made of a spring material having a wavy cross section are interposed, and a plurality of first voids formed by one of the separators 201 and the oxidant electrode 103 are provided. 401 is formed as a fuel gas passage groove, and the other separator 202 and a plurality of second void portions 402 formed in a wavy cross section are formed as oxidant gas passage grooves. FIG. 2 shows a plate material 3 made of a spring material.
It is a perspective view of No. 01.

The first gap 401 has a fuel electrode 10
3 is a passage through which the fuel gas supplied to the fuel cell 3 passes. The second gap 402 is a passage through which the oxidizing gas supplied to the oxidizing electrode 105 passes.

The separators 201 and 202 are connected to the electrode 10
3, 105 has electric conductivity and a current collecting function, and has a partitioning function for preventing mixing of the oxidizing gas and the fuel gas.

The plate members 301 and 302 made of the above-mentioned spring material
By interposing between the fuel electrode 103 and the separator 201 and between the oxidant electrode 105 and the separator 202, respectively, has a gas passage function and makes contact with the electrodes. Due to the resiliency of the plate members 301 and 302 made of the spring material, an increase in the thickness of the solid polymer electrolyte membrane 101 due to moisture absorption can be absorbed to prevent an excessive pressing force from being generated.

Plates 301 and 302 made of this spring material
Is required to have electrical conductivity, heat resistance and moisture resistance, and is made of a heat-resistant material from a room temperature to around 100 ° C. as an operating temperature of a solid polymer electrolyte fuel cell. The spring material is made of an iron spring material, a stainless steel spring material (such as a SUS material), or a conductive resin material.

The conductive resin material has its own elasticity and is effective as a spring material. Further, for example, as the conductive resin material, there are roughly classified into a mixture with a conductive resin and a resin showing the conductivity of the polymer compound itself. The former is a resin in which a conductive filler is connected to a resin obtained by mixing a resin, a metal, and carbon as ultrafine particles, respectively. As the latter, by heating polyacrylonitrile in the presence of air, it changes into a polymer compound with a long conjugated system, which itself has the properties of a semiconductor, and becomes conductive when treated with a metal salt. It is.

Further, a noble metal plating coating of gold, platinum, palladium or the like is applied to the surface of the spring material. Alternatively, a coating of CrN, TiN, ZrN, or the like is applied to the surface of the spring material.

The plating process for forming the surface coating of the plating on the plate materials 301 and 302 is performed by a conventional electrolytic plating method or an electroless plating method to a thickness of 10 μm.

By the above-mentioned means, the plate material can have heat resistance and moisture resistance under an environment where the temperature is around 80 ° C. and the humidity is high.

The plate member 3 made of a spring material having the above structure
01 and 302 to the electrodes 103 and 105 and the separator 20
1 and 202, the unit cell 10
When the pressure is applied to the fuel cell in which
Due to the spring characteristics of the electrodes 1 and 302, even if excessive pressure is applied to the electrodes 103 and 105, the stress can be reduced by the plate material, and the pressure due to swelling by the polymer electrolyte membrane can be absorbed.

As a result, damage to the electrodes 103 and 105 can be prevented beforehand, and the management of pressurization becomes easy.

Further, the first gap portion 40 formed from the separators 201 and 202 and the corrugated plate members 301 and 302
The first and second gap portions 402 have a function as a fuel gas flow passage and an oxidizing gas flow passage, respectively, and are more cost-effective than forming a flow groove in the separator.

[0043]

As described above, according to the present invention, the electrodes are arranged on both sides of the solid polymer electrolyte membrane, the fuel gas is supplied to one side of the electrodes, and the oxidized surface is supplied to the other side of the electrodes. A solid polymer electrolyte fuel cell in which a plurality of unit cells each composed of two separators for supplying an agent gas are stacked, wherein a plate member made of a wavy spring material is interposed between the separators and the fuel electrode. The plurality of first gaps formed by the one separator and the fuel electrode are formed as fuel gas flow grooves, and the plurality of second gaps formed by the other separator and the oxidant electrode are Since the solid polymer electrolyte fuel cell is formed as an oxidant gas flow channel, the pressure applied between the separator and the electrode is excessively increased due to the swelling of the membrane, and the electrode is damaged. Solves the problem of It can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a unit cell according to an embodiment of the present invention.

FIG. 2 is a perspective view of a wavy plate member having a spring property according to the present invention.

FIG. 3 is a cross-sectional view of a conventional unit cell.

FIG. 4 is a perspective view of a fuel cell in which a plurality of unit cells are stacked and fastened by angles, bolts, and the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Solid polymer electrolyte membrane 103 ... Electrode (anode) 105 ... Electrode (cathode) 201, 202 ... Separator 301, 302 ... Plate material 401 ... 1st cavity 402 ... 2nd cavity

Claims (4)

[Claims] An electrode is disposed on both sides of a solid polymer electrolyte membrane, a fuel gas is supplied to one side of the electrode, and an oxidant gas is supplied to the other side of the electrode from two separators. A solid polymer electrolyte fuel cell in which a plurality of unit cells are laminated, wherein a plate member made of a wavy spring material is interposed between the separators and the fuel electrode, and the one separator and the fuel electrode are interposed. A plurality of first formed by
The cavity is formed as a fuel gas passage groove, and the plurality of second gaps formed by the other separator and the oxidant electrode are formed as oxidant gas passage grooves. Molecular electrolyte fuel cell. 2. The spring material is made of an iron-based spring material, a stainless-based spring material, or a conductive resin material obtained by mixing a metal with a resin.
The solid polymer electrolyte fuel cell according to the above. 3. The solid polymer electrolyte fuel cell according to claim 1, wherein a surface of the spring material is coated with a noble metal plating such as gold, platinum or palladium. 4. The method according to claim 1, wherein the surface of the spring material is CrN, Ti
The solid polymer electrolyte fuel cell according to claim 1, wherein a coating of N, ZrN, or the like is applied.