WO2010073849A1 - Fuel cell system comprising heat generating source for heating water absorbing member, and electronic device comprising same - Google Patents

Abstract

A fuel cell system (10) which comprises a fuel cell stack (11) comprising two or more unit cells (101) each containing a cathode electrode, an electrolyte membrane and an anode electrode in this order, and also an electronic device comprising the fuel cell system (10).  Fuel cell systems recently have become the focus of increased attention as small-sized power supplies for portable electronic devices and the like.  Fuel cell systems, however, have a problem in that when much water is generated and condensed at the cathode electrode, the water leaks out of the system, and even if a water-absorbing member for preventing leakage is arranged, leakage occurs if the water absorption ability of the water-absorbing member becomes saturated.  The above-described problem has been solved by providing the fuel cell system (10) with a water-absorbing member (14) arranged on the outer surface of the fuel cell stack in such a manner that the water-absorbing member (14) spatially communicates with the cathode electrode and absorbs the water generated at the cathode electrode, and a heat generating source (12) for heating the water-absorbing member.

Description

FUEL CELL SYSTEM INCLUDING HEAT GENERATOR FOR HEATING WATER ABSORBING MEMBER AND ELECTRONIC DEVICE HAVING THE SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system and an electronic device including the same, and more particularly to a fuel cell system that is small in size and high in output and can prevent liquid leakage and an electronic device including the fuel cell system.

In recent years, there is an increasing expectation for a fuel cell as a small power source used in portable electronic devices that support the information society. A fuel cell utilizes an electrochemical reaction in which fuel (for example, hydrogen, methanol, ethanol, hydrazine, formalin, formic acid, etc.) is oxidized at an anode electrode and oxygen in the air is reduced at a cathode electrode. Such a fuel cell is a chemical cell that supplies electrons to a portable electronic device or the like, and high power generation efficiency can be obtained with a single power generation device.

Among various fuel cells, a polymer electrolyte fuel cell (PEMFC) using a proton exchanged ion exchange membrane as an electrolyte membrane can achieve high power generation efficiency even at low temperature operation of 100 ° C. or less. Because of this, compared to fuel cells that operate at high temperatures, such as phosphoric acid fuel cells and solid oxide fuel cells, there is no need to apply heat from the outside, and there is no need for large-scale accessories. Therefore, it is expected to be put into practical use as a small power source.

The fuel used for such a PEMFC is generally a hydrogen gas using a high-pressure gas cylinder, a mixed gas of hydrogen gas and carbon dioxide gas obtained by decomposing an organic liquid fuel with a reformer, or the like. .

On the other hand, a direct methanol fuel cell (DMFC: Direct Methanol Fuel Cell) needs to be equipped with a reformer to generate power by supplying a methanol aqueous solution to the anode electrode and extracting protons and electrons directly from the methanol aqueous solution. Absent. For this reason, the DMFC can be made smaller than the PEMFC. Therefore, DMFC is said to be a particularly effective fuel cell for practical use as a small power source.

Furthermore, DMFC uses an aqueous methanol solution that is liquid at atmospheric pressure as fuel. Therefore, a fuel having a high volumetric energy density can be handled with a small simple container without using a high-pressure gas cylinder, which is excellent in terms of safety when used as a small power source. Therefore, DMFC is attracting attention as an application to a small power source such as a portable electronic device, particularly as a secondary battery replacement application for a portable electronic device.

In DMFC, the following reactions occur at the anode and cathode, respectively.
Anode electrode: CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻
Cathode: O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O
Thus, in the DMFC, carbon dioxide is generated as a gas on the anode side, and water is generated on the cathode side. Usually, the water produced by the reaction at the cathode electrode is released as water vapor by diffusion into the air at the cathode electrode. However, when the amount of water vapor reaches the saturated vapor pressure, condensed water that cannot evaporate remains as droplets at the cathode electrode. This condensed water hinders the air supply path and reduces the output of the DMFC. Furthermore, when the dew condensation water generated at the cathode electrode increases, there is a problem that this dew condensation water leaks out of the fuel cell.

In response to this problem, Japanese Patent Laid-Open No. 2002-15763 (hereinafter referred to as “Patent Document 1”) is adjacent to the fuel cells (hereinafter also referred to as “unit cells”) that constitute the DMFC. A structure is disclosed in which a porous body for absorbing generated water is provided between two unit cells.

With such a structure, the porous body absorbs water generated by the unit battery, and the water evaporates from the porous body and is released outside the electronic device. For this reason, the liquid leak of the water produced | generated with the unit battery can be prevented. However, when the DMFC having this structure is used for a long period of time, there is a problem that the generated water leaks again after the water absorption capacity of the porous body reaches a saturated state.

Therefore, Japanese Patent Laid-Open No. 2003-331900 (hereinafter also referred to as “Patent Document 2”) discloses a technique in which a water absorption layer is provided in one of the layers constituting a unit battery. As described above, the water absorption layer absorbs the water generated at the cathode electrode, thereby preventing leakage of the generated water. According to this method, the output of the fuel cell is less likely to decrease and liquid leakage is less likely to occur. However, similarly to Patent Document 1, when the water absorption capacity of the water absorption layer reaches the limit, there still remains a problem that liquid leakage occurs.

In order to solve the above-described problem of liquid leakage, Japanese Patent Laid-Open No. 2006-179470 (hereinafter also referred to as “Patent Document 3”) discloses a structure in which a sheet-like water absorbing member is provided on one surface of a wall surface constituting a fuel cell. A fuel cell is disclosed. In this fuel cell, water generated by the unit cell is absorbed by a capillary action on one surface of the sheet-like water absorbing member. On the other hand, the other surface of the sheet-like water absorbing member has a structure for evaporating the absorbed water. According to such a structure, it is possible to further prevent leakage of produced water from the fuel cell, but particularly when the fuel cell is used for a long time, the liquid leakage occurs with a high probability.

JP 2002-15763 A JP 2003-331900 A JP 2006-179470 A

Summarizing the above Patent Documents 1 to 3, by providing a water absorbing member inside or outside the unit cell, it is possible to temporarily prevent leakage of generated water. However, when the amount of water absorbed per unit time of the water absorbing member exceeds the amount of water that can be discharged per unit time, the water absorbing capability of the water absorbing member reaches saturation after a certain period of time. And it had the subject that a liquid leak arises by subsequent use.

As a technique for preventing such liquid leakage, it is also conceivable to prevent liquid leakage by increasing the saturated water absorption capacity of the water absorbing member by increasing the volume of the water absorbing member itself. However, since this method increases the size of the fuel cell system itself, it cannot be said that the structure is suitable for use in a small portable electronic device.

The present invention has been made in order to solve the above-mentioned problems, and the object thereof is to increase the amount of water that can be released per unit time of the water absorbing member, thereby reducing the size and output. In addition, it is an object of the present invention to provide a fuel cell system in which liquid leakage hardly occurs and an electronic device equipped with the fuel cell system.

The fuel cell system of the present invention includes a fuel cell stack including two or more unit cells each including a cathode electrode, an electrolyte membrane, and an anode electrode in this order, and an outside of the fuel cell stack so as to be in spatial communication with the cathode electrode. A water-absorbing member that is disposed on the surface and absorbs water generated from the cathode electrode and a heat source that heats the water-absorbing member are provided.

It is preferable to further include a heat conducting member that is disposed so as to be in contact with the water absorbing member and the heat generating source and conducts heat from the heat generating source to the water absorbing member.

It is preferable to include a sheet-like heat conducting member, a sheet-like water absorbing member laminated on the heat conducting member, and a fuel cell stack disposed on the water absorbing member.

In the fuel cell stack, a fuel cell layer in which two or more unit cells are arranged with a gap in the same plane and a spacer layer composed of two or more spacers arranged so as to intersect the unit cell are alternately arranged. It is preferable to be laminated.

The unit cell preferably includes a cathode electrode, an electrolyte membrane, an anode electrode, and an anode current collecting layer in this order.

It is preferable to have a layer made of a water-absorbing material so as to cover a part of the surface of the spacer and to be in contact with the water-absorbing member.

The capillary force of the layer made of the water-absorbing material is preferably smaller than the capillary force of the water absorbing member.
The present invention is an electronic device having the above fuel cell system, and a heat source of the fuel cell system is an electronic component constituting the electronic device.

According to the present invention, it is possible to provide a fuel cell system that is small in size, has high output, and is less likely to cause liquid leakage even when used for a long time. In addition, the electronic device can be prevented from being damaged due to excessive temperature rise of the heat source of the electronic device, and an electronic device equipped with a highly reliable fuel cell system can be provided.

It is a figure which shows typically a preferable example of the fuel cell system of this invention. It is a figure which shows typically a preferable example of the fuel cell system of this invention. It is sectional drawing which shows typically the structure of the unit cell which comprises the fuel cell stack of the fuel cell system of this invention. It is a figure which shows typically a preferable example of the fuel cell system of this invention. (A) is a figure which shows typically an example of the electronic device by which the fuel cell system of this invention is mounted, (b) is a schematic when the electronic device of (a) is seen from another one side. It is a simple figure. It is a figure which shows typically an example of the electronic device by which the fuel cell system of this invention is mounted. It is a figure which shows typically an example when a part of fuel cell system of this invention is covered with the housing | casing.

Hereinafter, embodiments of the present invention will be described. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

(First embodiment)
<Fuel cell system>
FIG. 1 is a diagram schematically showing a preferred example of the fuel cell system of the present invention. As shown in FIG. 1, the fuel cell system 10 of the present invention includes a fuel cell stack 11 including two or more unit cells 101 including a cathode electrode, an electrolyte membrane, and an anode electrode in this order, and an outside of the fuel cell stack 11. The water-absorbing member 14 is disposed on the surface so as to spatially communicate with the cathode electrode and absorbs water generated at the cathode electrode, and a heat source 12 for heating the water-absorbing member 14.

Here, “spatially communicating” means that the cathode electrode and the water absorbing member may be in contact with each other, or the cathode electrode and the water absorbing member may not be in contact with each other. When the cathode electrode and the water absorbing member are not in contact with each other, the space between the cathode electrode and the water absorbing member is filled with space (that is, there is no member between them) and is generated at the cathode electrode. It means that the water absorbing member exists in a positional relationship in which when the water falls due to gravity, the water directly falls on the water absorbing member without contacting any member other than the water absorbing member. However, when the cathode electrode and the water absorbing member are not in contact with each other, it is assumed that the water absorbing member is provided within a distance range in which water generated at the cathode electrode can be absorbed by the water absorbing member.

In the fuel cell system 10 of the present invention, when the heat generating source 12 raises the temperature of the water absorbing member 14, the evaporation rate of water contained in the water absorbing member 14 is increased. Thereby, the water absorption capability of the water absorbing member 14 is enhanced, and liquid leakage of the fuel cell stack can be prevented.

Although FIG. 1 shows an example of the fuel cell stack 11 including two unit cells 101, the effect of the present invention can be achieved even in the case of the fuel cell stack 11 including three or more unit cells 101. Needless to say, is shown.

As shown in FIG. 1, it is preferable to further include a heat conducting member 13 that is disposed so as to be in contact with the water absorbing member 14 and the heat generating source 12 and conducts heat from the heat generating source 12 to the water absorbing member 14. By providing the heat conducting member 13 in this way, the heat generated from the heat source 12 can be efficiently conducted to the water absorbing member 14. As a result, the evaporation rate of the water contained in the water absorbing member 14 can be increased, and liquid leakage from the fuel cell stack 11 can be prevented.

In addition, as shown in FIG. 1, the fuel cell system of the present invention is arranged on a sheet-like heat conducting member 13, a sheet-like water absorbing member 14 laminated on the heat conducting member 13, and the water absorbing member 14. It is preferable that the fuel cell stack 11 is provided. The fuel cell stack 11 having such a configuration can conduct the heat of the heat source 12 to the water absorbing member 14 through the heat conducting member 13. Thereby, the water contained in the water absorbing member 14 is further easily evaporated, and the water absorbing ability of the water absorbing member 14 can be enhanced.

In addition, the "sheet shape" here means a long shape, and can include any shape as long as the thickness is sufficiently small with respect to the front and back areas. .

<Fuel cell stack>
The fuel cell stack 11 used in the fuel cell system 10 of the present invention includes two or more unit cells 101 including a cathode electrode, an electrolyte membrane, and an anode electrode in this order.

<Water absorption member>
The water absorbing member 14 used in the fuel cell system of the present invention is provided to absorb the water generated at the cathode electrode of the unit cell 101 so as not to leak outside as shown in FIG. For this reason, in the fuel cell system 10 of the present invention, it is preferable to dispose the water absorbing member 14 on the outer surface of the fuel cell stack 11 so as to spatially communicate with the cathode electrode. Furthermore, from the viewpoint of efficiently absorbing the water generated by the unit cell 101 into the water absorbing member 14, the water absorbing member 14 is preferably provided downward in the gravity direction at the position where the fuel cell stack 11 is disposed.

By disposing the water absorbing member 14 in such a positional relationship, among the water generated at the cathode electrode of the unit cell 101, the dew condensation water that has not been released into the atmosphere as water vapor moves downward due to gravity and moves to the water absorbing member 14. Water is absorbed.

Here, the material used for the water absorbing member 14 is not particularly limited as long as it does not dissolve in water and liquid fuel, but any material such as an inorganic substance such as a metal or a polymer material can be used. It is preferable to use a porous body made of an organic substance. Examples of such a porous body include foams, fiber bundles, woven fibers, non-woven fibers, porous sintered bodies, and combinations of these materials. By using a porous body of such a material, water is absorbed and held in the pores of the porous body. Then, the porous body holding water is heated by a heat generation source, so that the efficiency of vaporizing water from the pores of the porous body to the atmosphere can be increased, and thus liquid leakage from the fuel cell stack can be achieved. Can be prevented.

When a porous body made of an inorganic substance such as a metal is used as the water absorbing member 14, it is preferable to combine an insulating material so as to block the conductivity of the porous body made of an inorganic substance such as a metal. By using such an insulating material, it is possible to prevent the cathode electrode and the anode electrode of the unit cell 101 from being short-circuited. Here, as the insulating material combined with the water absorbing member 14, polyester, polycarbonate, polyethylene, acrylic, or the like is preferably used from the viewpoint of being hydrophilic and having chemical resistance.

When a porous body made of an organic substance such as a polymer material is used as the water absorbing member 14, examples of the porous body include natural fibers, polyester, polyethylene, polyurethane, acrylic, polyamide, polyolefin, polyacetal, polyvinyl, and polycarbonate. It is more preferable to use a fiber bundle, a woven fiber, or a non-woven fiber composed of one or a combination of two or more selected from the group consisting of styrene, polyether, and polyphenylene.

<Heat source>
The heat source 12 used in the fuel cell system of the present invention is provided directly with the water absorbing member 14 or via a heat conducting member 13 described later in order to vaporize the water absorbed by the water absorbing member 14 to the atmosphere. The heat source 12 itself becomes a high temperature.

Such a heat source 12 may be any one as long as it itself becomes a high temperature, and may be included in the fuel cell system in any form. When the fuel cell system of the present invention is mounted on an electronic device, the heat source 12 is preferably an electronic component provided inside the casing of the electronic device. The electronic component herein may be any electronic component that becomes high temperature due to the use of the electronic device, such as a central processing unit (CPU: Central Processing Unit) for electronic devices, a power amplifier, a wireless circuit, and the like. It is done.

By using an electronic component of an electronic device as a heat source, it is not necessary to separately provide the heat source 12 of the fuel cell system, and power used to drive the heat source 12 can be saved. For this reason, a fuel cell system can be reduced in size. In addition, since the heat of the electronic component of the electronic device (meaning “the heat generation source 12” of the fuel cell system 10) is radiated to the atmosphere as the heat of vaporization of the water absorbing member 14, the excessive temperature rise of the electronic component provided in the electronic device This also has the effect of suppressing the operation of the electronic device from becoming unstable.

<Heat conduction member>
As shown in FIG. 1, the fuel cell system of the present invention further includes a heat conducting member 13 that is disposed so as to contact the water absorbing member 14 and the heat source 12 and conducts heat from the heat source 12 to the water absorbing member 14. It is preferable. By providing such a heat conducting member 13, heat from the heat source 12 can be efficiently conducted to the water absorbing member 14, moisture contained in the water absorbing member 14 can be efficiently vaporized, and the water absorbing member The water absorption capacity of 14 can be increased.

Here, the material and shape of the heat conducting member 13 are not particularly limited as long as they have heat conductivity, but are preferably in the form of a sheet from the viewpoint of conducting heat to the water absorbing member 14 with high efficiency. Moreover, it is preferable that the heat conductive member 13 is a composite sheet including at least one selected from the group consisting of carbon black, metal, metal oxide, metal nitride, and metal carbide having high heat conductivity. The heat conduction member 13 is a composite sheet comprising, for example, a filler containing a filler selected from carbon nanotubes, vapor grown carbon fibers (VGCF), etc., in an alloy containing aluminum, copper, or the like as a main component. Alternatively, a composite sheet is used in which a matrix material made of at least one selected from the group consisting of silicone resin, high-density polyethylene, low-density polyethylene, and polypropylene is filled with a filler made of a material having high thermal conductivity. It is more preferable.

The joint surface between the water absorbing member 14 and the heat conducting member 13 is preferably located at the lower part of the fuel cell stack 11 in the gravitational direction. By providing the joint surface at a position below the gravitational direction of the fuel cell stack 11, the warm air vaporized at the joint surface between the water absorbing member 14 and the heat conducting member 13 is stacked from the lower part of the fuel cell stack 11. Ascending airflow occurs due to the chimney effect. By generating the upward airflow in this way, air can be taken in from the lower part of the fuel cell stack 11 without using power.

By adopting such a structure, even when no power is used to supply air to the cathode electrode as in a passive cell, it is possible to efficiently supply air to the fuel cell stack, and stably achieve high output. Obtainable. Moreover, it becomes easy to take in the dry air at a low temperature into the fuel cell stack 11 from the outside. For this reason, heat exchange in the fuel cell stack becomes active between the water absorbing member 14 and the surrounding air, and the vaporization of water contained in the water absorbing member 14 is also promoted. Hereinafter, unit cells constituting the fuel cell stack will be described.

<Unit battery>
FIG. 3 is a schematic cross-sectional view showing a preferred example of the unit battery 101 of FIG. In the present invention, the unit cell 101 is a unit constituting a fuel cell stack, and as shown in FIG. 3, a membrane electrode assembly 106 including an anode electrode 103, an electrolyte membrane 102, and a cathode electrode 104 in this order. (MEA: Membrane Electrode Assembly). The unit battery 101 may include other components in addition to the membrane electrode assembly 106 as necessary for the purpose of imparting a power generation function or other purposes. For example, the unit battery 101 may include an anode current collecting layer 105, a cathode current collecting layer, and the like. A layer (not shown), a separator (not shown), or the like may be provided.

That is, when the unit cell 101 constituting the fuel cell layer of the fuel cell stack 11 of the present invention includes the anode current collecting layer 105, the unit cell 101 includes the cathode electrode 104, the electrolyte membrane 102, and the like, as shown in FIG. It is preferable to include the anode electrode 103 and the anode current collecting layer 105 in this order. By including the anode current collecting layer 105 in this manner, electrons generated at the anode electrode 103 can be exchanged efficiently.

Here, when the anode current collecting layer 105 is provided in the unit cell 101, it is preferable that the anode current collecting layer includes a fuel flow path 107 which is a space for fuel transportation as shown in FIG. In the case of using an aqueous methanol solution as the fuel in the unit cell 101 of FIG. 3, the aqueous methanol solution is supplied to the anode electrode 103 through the fuel flow path 107, and CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ at the anode electrode 103. Reacts to generate hydrogen ions and electrons.

The hydrogen ions generated here move to the cathode electrode 104 through the electrolyte membrane 102. On the other hand, air is supplied from the atmosphere as an oxidant to the cathode electrode 104 and reacts with O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O at the cathode electrode 104 to generate water. Thus, by extracting the flow of electrons generated at the anode electrode 103 to the cathode electrode 104 as a current through an external circuit, electric energy can be obtained from the unit cell 101.

<Fuel>
As the fuel supplied to the unit cell 101 of the present invention, either gaseous fuel or liquid fuel may be used as long as electric power can be obtained by electrolysis. Examples of the gaseous fuel include hydrogen, DME, methane, butane, and ammonia. Examples of the liquid fuel include alcohols such as methanol and ethanol, acetals such as dimethoxymethane, carboxylic acids such as formic acid, esters such as methyl formate, and hydrazine. In addition, although the above-mentioned liquid fuel mentions the fuel which is a liquid at normal temperature, you may vaporize liquid fuel and may supply a gaseous phase. The gas fuel and liquid fuel described above are not limited to one type, and may be a mixture of two or more types. From the viewpoint of energy density per volume, it is preferable to use methanol.

<Oxidizing agent>
As the oxidant supplied to the fuel cell stack of the present invention, it is preferable to use oxygen, hydrogen peroxide, and nitric acid. From the viewpoint of the cost of the oxidizing agent, it is more preferable to use oxygen in the air. In the following description of each layer constituting the unit cell 101, for convenience of explanation, a case where methanol is used as a fuel and air is used as an oxidizer may be described, but the case where these materials are used is limited. is not.

<Electrolyte membrane>
In the present invention, the electrolyte membrane 102 constituting the unit cell 101 conducts protons generated at the anode electrode 103 and transmits the protons to the cathode electrode 104, and any material having electrical insulating properties can be used. Any known material can be used. The electrolyte membrane 102 can be formed of, for example, a polymer film, an inorganic film, or a composite film.

Examples of polymer membranes used for the electrolyte membrane 102 include perfluorosulfonic acid electrolyte membranes (Nafion (NAFION (registered trademark): manufactured by DuPont)), Dow membranes (manufactured by Dow Chemical), and Aciplex (ACIPLEX (registered). (Trademark): manufactured by Asahi Kasei Co., Ltd., Flemion (registered trademark): manufactured by Asahi Glass Co., Ltd.), and hydrocarbon electrolyte membranes such as polystyrene sulfonic acid and sulfonated polyether ether ketone.

Examples of the inorganic film used for the electrolyte membrane 102 include phosphate glass, cesium hydrogen sulfate, polytungstophosphoric acid, ammonium polyphosphate, and the like.

Examples of the composite membrane used for the electrolyte membrane 102 include Gore Select membrane (Gore Select (registered trademark): manufactured by Japan Gore-Tex Co., Ltd.).

Also, in order that the fuel cell stack (or unit cell 101) can cope with temperatures near 100 ° C. or higher, it is preferable to use a material for the electrolyte membrane 102 having high ionic conductivity even when the water content is low. Examples of the material for the electrolyte membrane 102 include sulfonated polyimide, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), sulfonated polybenzimidazole, and phosphonated polybenzimidazole. It is preferable to use cesium hydrogen sulfate, ammonium polyphosphate, ionic liquid (room temperature molten salt) or the like as a film.

Such an electrolyte membrane 102 preferably has a proton conductivity of 10 ⁻⁵ S / cm or more, and has a proton conductivity of 10 like a polymer electrolyte membrane such as a perfluorosulfonic acid polymer or a hydrocarbon polymer. It is more preferable to use a material of ⁻³ S / cm or more.

<Anode and cathode>
The anode electrode 103 of the unit cell 101 used in the fuel cell system of the present invention includes at least an anode catalyst layer (not shown) including an anode catalyst that promotes fuel oxidation. Then, the fuel causes an oxidation reaction on the anode catalyst to generate protons and electrons. The anode electrode 103 preferably has a structure in which an anode porous substrate (not shown) is laminated on the anode current collecting layer 105 side (the side opposite to the electrolyte membrane 102) separately from the anode catalyst layer.

On the other hand, the cathode electrode 104 of the unit cell 101 used in the fuel cell system of the present invention includes at least a cathode catalyst layer (not shown) including a cathode catalyst that promotes reduction of the oxidant. Then, the oxidant takes in protons and electrons on the cathode catalyst to generate a reduction reaction, thereby generating water. The cathode electrode 104 preferably has a structure in which a cathode porous substrate (not shown) is further laminated on the side opposite to the electrolyte membrane 102 in addition to the cathode catalyst layer.

<Anode catalyst layer and cathode catalyst layer>
The anode catalyst layer preferably includes at least an anode catalyst that promotes oxidation of the fuel, and further includes an anode support and an anode electrolyte. On the other hand, the cathode catalyst layer preferably includes at least a cathode catalyst that promotes a reaction rate for generating water from oxygen, protons, and electrons, and further includes a cathode support and a cathode electrolyte.

The thickness of each of the anode catalyst layer and the cathode catalyst layer is preferably 0.1 μm or more and 0.2 mm or less. If the thickness of the anode catalyst layer and the cathode catalyst layer is less than 0.1 μm, the anode catalyst layer and the cathode catalyst layer may not be able to carry a catalyst amount sufficient to improve the output of the fuel cell stack (or unit cell). If it exceeds 0.2 mm, the resistance of proton conduction and the resistance of electron conduction may increase, or the diffusion resistance of liquid fuel or oxidant may increase.

In the following (1) to (3), what is included in the anode catalyst layer and the cathode catalyst layer will be described.

(1) Anode catalyst and cathode catalyst The anode catalyst has a function of accelerating the reaction rate of producing protons and electrons from methanol and water when using an aqueous methanol solution as a fuel. On the other hand, the cathode catalyst has a function of accelerating the reaction rate of the reaction for generating water from oxygen, protons and electrons.

The anode catalyst and the cathode catalyst are not necessarily limited to the same type, and different types of materials can be used. Examples of such anode catalyst and cathode catalyst include noble metals such as Pt, Ru, Au, Ag, Rh, Pd, Os, Ir, Ni, V, Ti, Co, Mo, Fe, Cu, Zn, Sn, W, and the like. Base metals such as Zr, oxides of these noble metals or base metals, carbides and carbonitrides, or one or a combination of two or more materials selected from the group consisting of carbon can be used as the catalyst.

(2) Anode carrier and cathode carrier The anode carrier has a function of conducting electrons generated at the anode electrode 103 to the anode porous substrate. On the other hand, the cathode carrier has a function of conducting electrons from the cathode porous substrate to the cathode catalyst layer.

Any material may be used for the anode carrier and the cathode carrier as long as they have electrical conductivity. However, it is preferable to use a carbon-based material having high electrical conductivity, and a carbon-based material having high electrical conductivity. Examples of the material include acetylene black, ketjen black (registered trademark), amorphous carbon, carbon nanotube, and carbon nanohorn. In addition to these carbon-based materials, noble metals such as Pt, Ru, Au, Ag, Rh, Pd, Os, Ir, Ni, V, Ti, Co, Mo, Fe, Cu, Zn, Sn, W, Base materials such as Zr, oxides of these noble metals or base metals, carbides, nitrides, and carbon nitrides may be used as the support.

Further, the anode carrier and the cathode carrier may be a material imparted with proton conductivity. Examples of the material imparted with proton conductivity in this way include sulfated zirconia and zirconium phosphate.

Also, the surface of the anode carrier is preferably hydrophilic. By making the surface of the anode carrier hydrophilic, the fuel (methanol aqueous solution) can be easily held in the pores of the anode catalyst layer, and the diffusibility of fuel and protons in the anode catalyst layer is improved. Here, examples of the method for hydrophilizing the surface of the anode carrier include a method of modifying the surface of the anode carrier with a hydrophilic functional group such as a carboxyl group or a hydroxyl group.

Examples of the method for hydrophilizing the surface of the anode carrier include surface modification by graft polymerization of the carbon surface, surface modification with a silane coupling agent, and the like. Since both the anode catalyst and the cathode catalyst have electron conductivity, the anode carrier and the cathode carrier need not be provided.

(3) Anode electrolyte and cathode electrolyte The anode electrolyte has a function of conducting protons generated at the anode electrode 103 to the electrolyte membrane 102. On the other hand, the cathode electrolyte has a function of conducting protons permeated from the electrolyte membrane 102 to the vicinity of the cathode catalyst layer.

The anode electrolyte and the cathode electrolyte are not particularly limited as long as they are materials having proton conductivity and electrical insulation, and any materials can be used. The anode electrolyte and cathode electrolyte are preferably solids or gels that are not dissolved by a fuel such as methanol. Such an anode electrolyte and cathode electrolyte are preferably organic polymers having strong acid groups such as sulfonic acid and phosphoric acid groups and weak acid groups such as carboxyl groups. For example, perfluorocarbon (Nafion (registered trademark) (DuPont) Co.)), carboxyl group-containing perfluorocarbon (Flemion (registered trademark) (manufactured by Asahi Kasei Corporation)), polystyrene sulfonic acid copolymer, polyvinyl sulfonic acid copolymer, ionic liquid (room temperature molten salt), sulfonation Examples thereof include imide and AMPS.

In addition, when using what has proton conductivity as an anode support body and a cathode support body, since it can conduct a proton by these, it is not necessary to provide an anode electrolyte and a cathode electrolyte separately.

<Anode porous substrate and cathode porous substrate>
The anode porous substrate forms a void that allows methanol and water to be supplied to the anode catalyst layer, and has a function of conducting electrons from the anode carrier to the anode current collecting layer 105. On the other hand, the cathode porous substrate forms a void that allows oxygen in the atmosphere to be supplied to the cathode catalyst layer and allows the generated water to be efficiently discharged to the outside, and from the cathode carrier to external wiring (not shown). ) Has the function of conducting electrons.

The anode porous substrate and the cathode porous substrate are preferably made of a conductive material. For example, carbon paper, carbon cloth, metal foam, metal sintered body, metal fiber nonwoven fabric, and the like can be used. Here, as a metal used for a metal foam, a metal sintered body, and a nonwoven fabric of metal fiber, noble metals such as Pt, Ru, Au, Ag, Rh, Pd, Os, Ir, Ni, V, Ti, Co, Examples include base metals such as Mo, Fe, Cu, Zn, Sn, W, and Zr, and materials containing one or more of these noble metals, base metal oxides, carbides, nitrides, and carbonitrides. . The anode porous substrate is preferably disposed on the anode current collecting layer 105 side (the side opposite to the electrolyte membrane 102 side) of the anode electrode 103. Further, the cathode porous substrate is preferably disposed outside the unit cell in the cathode electrode 104 (on the side opposite to the electrolyte membrane 102 side).

Note that the anode porous substrate and the cathode porous substrate are not necessarily provided. That is, for example, the anode catalyst layer may be formed directly on the electrolyte membrane 102 such that the anode catalyst layer exchanges electrons with the anode current collecting layer, or the cathode catalyst layer exchanges electrons with the external wiring. In addition, the cathode catalyst layer may be formed directly on the electrolyte membrane 102.

<Anode current collecting layer>
In the present invention, the unit cell 101 constituting the fuel cell layer preferably further includes an anode current collecting layer 105 having a function of transferring electrons generated in the anode electrode 103.

Such an anode current collecting layer 105 preferably has a fuel flow path 107 in which one or two or more grooves are formed on the surface of the front and back in contact with the anode electrode 103. The shape of the fuel flow path 107 provided in the anode current collecting layer 105 is not particularly limited, and any shape can be used. The shape of the fuel flow path 107 is preferably determined in consideration of the electrical resistance of the anode current collecting layer 105, the contact area between the anode current collecting layer 105 and the anode electrode 103, and the like. For example, as shown in FIG. 3, the fuel channel 107 may have a quadrangular cross-sectional shape with respect to the direction in which the fuel flows in the fuel channel 107.

If section relative to the direction through which fuel flows in the fuel passage 107 is a square shape, it is preferred that the rectangular area is 0.01 mm ² or more 1 mm ² or less. If this area is less than 0.01 mm ² , there is a problem that the pressure loss for flowing the liquid increases, so that the fuel supply device becomes large. If it exceeds 1 mm ² , the fuel cell stack becomes large. .

Further, when the length of the portion in contact with the anode electrode 103 in the quadrangular shape of the cross section of the fuel flow path is defined as the width of the fuel flow path, the width of the fuel flow path may be 0.1 mm or more and 1 mm or less. preferable. If the width of the fuel flow path is less than 0.1 mm, there is a problem in that the efficiency of fuel supply from the fuel flow path to the anode electrode 103 decreases. If the width exceeds 1 mm, the anode current collector layer in contact with the anode electrode Since the edge width becomes short, the structural stability becomes poor.

Further, it is preferable that 20% or more of the area of the surface in contact with the anode current collecting layer 105 of both the front and back surfaces of the anode electrode 103 is in contact with the anode current collecting layer 105. Note that, even when another layer is interposed between the anode electrode 103 and the anode current collecting layer 105 and the anode electrode 103 and the anode current collecting layer 105 are not in contact with each other, the above-described area relationship is the same. . When this area is less than 20%, there is a problem that ohmic resistance increases due to a decrease in the contact area between the anode current collecting layer 105 and the anode electrode 103.

The material used for the anode current collecting layer 105 may be any material as long as it exhibits conductivity. However, carbon materials, conductive polymers, noble metals such as Au, Pt, and Pd, Ti, Ta , W, Nb, Ni, Al, Cr, Ag, Cu, Zn, Su, and other metals, Si, and their nitrides, carbides, carbonitrides, etc., stainless steel, Cu—Cr, Ni—Cr, Ti— An alloy such as Pt can be used.

Here, the material used for the anode current collecting layer 105 is preferably a material having a small specific resistance, and includes at least one element selected from the group consisting of Pt, Ti, Au, Ag, Cu, Ni, and W. It is more preferable. By using such a material for the anode current collecting layer 105, voltage drop due to the resistance of the anode current collecting layer 105 can be reduced, and higher power generation characteristics can be obtained.

In addition, as a material used for the anode current collecting layer 105, when using a metal that is easily corroded in an acidic atmosphere such as Cu, Ag, or Zn, a noble metal or metal material having corrosion resistance such as Au, Pt, or Pd is used. It is preferable to coat the surface with a conductive polymer, a conductive nitride, a conductive carbide, a conductive carbonitride, a conductive oxide, or the like. By coating the surface in this way, corrosion of the surface of the anode current collecting layer 105 can be prevented, and the life of the unit cell and the fuel cell stack using the unit cell can be extended.

(Second embodiment)
FIG. 2 is a diagram schematically showing a preferred example of the fuel cell system of the present invention. As shown in FIG. 2, the fuel cell system of the present embodiment includes a fuel cell stack including two or more unit cells 201 and an outer surface of the fuel cell stack so as to be in spatial communication with the cathode electrode of the unit cell 201. The water absorbing member 24 that absorbs water generated from the cathode electrode, the heat generating source 22 that heats the water absorbing member 24, the water absorbing member 24, and the heat generating source 22 are disposed in contact with each other. A heat conducting member 23 that conducts heat to the water absorbing member 24 is provided.

As shown in FIG. 2, the fuel cell stack used in the fuel cell system 20 of the present invention includes a fuel cell layer 21 in which one or two or more unit cells 201 are arranged with a gap in the same plane. It is preferable that the spacer layer 26 composed of one or two or more spacers 206 arranged so as to intersect with the unit battery 201 is alternately laminated.

In FIG. 2, the spacer layer 26 is formed between the two fuel cell layers 21. However, the present invention is not limited to this mode, and the fuel cell layer 21 and the spacer layer are further limited. 26 are alternately stacked, they are included in the scope of the present invention, and the maximum number of stacked layers is not particularly limited.

By providing the spacer 206 between the fuel cell layers 21 in this way, the gap 214 provided in the same plane of the fuel cell layer 21 and the space portion 210 between the fuel cell layers 21 communicate three-dimensionally. Thus, the diffusibility of air in the fuel cell stack can be improved. That is, the air that has entered the fuel cell stack is naturally convected through the communicating gap 214 and the space portion 210, and air is easily supplied to the cathode electrode of the unit cell 201 included in the fuel cell stack. Moreover, the effect of promoting the evaporation of water contained in the water absorbing member 24 is also obtained by improving the air diffusibility.

In FIG. 2, the fuel cell layer 21 in which five unit cells 201 are arranged with a gap in the same plane so that the unit cell 201 intersects between two layers and the two fuel cell layers 21. Although the structure of the fuel cell stack including the spacer layer 26 including the four spacers 206 disposed is shown, both the number of unit cells and the number of spacers in FIG. It is not limited.

<Unit battery>
In the present invention, the unit cell 201 preferably has a strip shape having a long side and a short side from the viewpoint of ensuring the thickness of the gap 214 uniformly. It is preferable that it is a strip shape which has the length of at least one side. If the unit battery 201 has a rectangular column shape, the cross-sectional shape of the unit battery 201 is not particularly limited, and may be, for example, an ellipse or a square.

In the present invention, the fuel cell layer 21 of the fuel cell stack is arranged such that the unit cells 201 are provided with a gap 214 in the same plane and the long sides face each other. Each unit cell 201 has a cathode electrode and an anode electrode arranged in the same direction. That is, the cathode electrode of the unit cell 201 included in one fuel cell layer 21 of the adjacent fuel cell layers 21 and the anode electrode included in the other fuel cell layer 21 are arranged to face each other.

In the fuel cell stack shown in FIG. 2, dew condensation water generated on the surface of the cathode of the unit cell 201 falls as a droplet in the direction of gravity and is held by the water absorbing member 24 or is connected to the wall surface of the spacer 206. Accordingly, the water absorbing member 24 absorbs water.

<Spacer layer>
In the present invention, the spacer layer 26 is included in the cathode electrode of the unit cell 201 included in one fuel cell layer 21 of the fuel cell layers 21 arranged in contact with the front and back surfaces thereof, and in the other fuel cell layer 21. It arrange | positions between the anode current collection layers of the unit cell 201. FIG.

The positional relationship between the spacer layer 26 and the water absorbing member 24 is not particularly limited as long as the space 210 is formed in the fuel cell layer 21, and the spacer layer 26 may be provided at any position. It is preferable that the members 24 are arranged so as to be orthogonal to each other. By disposing in this way, the condensed water generated at the cathode electrode of the unit cell 201 can efficiently absorb water into the water absorbing member 14 that covers the wall surface of the spacer 206. The spacer layer 26 and the water absorbing member 24 do not necessarily have to be in contact with each other, and the effect of the present invention is exhibited even if the spacer layer 26 is provided separately from the water absorbing member 24.

The spacer layer 26 is formed by arranging one or more spacers 206 in the same plane. The number of the spacers 206 is not particularly limited as long as the spacer layer 26 can secure the space 210 between the fuel cell layers 21. The spacer layer 26 is configured by one or two or more spacers 206. be able to. However, from the viewpoint that the gap 214 of the unit battery 201 can be communicated three-dimensionally, the spacer layer 26 is preferably composed of two or more spacers 206.

Further, when two or more spacers 206 are provided in the spacer layer 26, it is preferable that the spacers 206 are arranged at intervals as shown in FIG. By arranging the spacer 206 in this way, the gap 214 provided in the same plane and the space 210 between the fuel cell layers 21 communicate three-dimensionally, and air diffusion in the fuel cell stack. Can be improved. That is, the air located in the gap 214 and the space part 210 in the fuel cell stack is naturally convected or diffused through the communicating gap 214 and the space part 210 and is easily supplied to the inside of the fuel cell stack. Then, oxygen in the atmosphere can be supplied to the cathode electrode of the unit cell 201 of the fuel cell layer 21 through the space portion 210.

Furthermore, the structure of the fuel cell stack as shown in FIG. 2 allows the air located in the space 210 and the gap 214 in the fuel cell stack to be warmed by the heat generated by the power generation of the unit cell. As a result, thermal convection is generated in the direction opposite to the direction of gravity in the communicating gap 214 and space 210 and released to the outside. In addition, an effect of promoting the reduction reaction at the cathode electrode by supplying air so as to be efficiently sucked from the side surface and the lower surface of the fuel cell stack is also obtained.

It is possible to supply air to the inside of the fuel cell stack by generating such heat convection. Therefore, it is not necessary to separately provide auxiliary equipment such as an air pump and a fan for supplying air as in the conventional fuel cell system, and the fuel cell system can be downsized. Moreover, even if auxiliary equipment such as an air pump and a fan is provided, the air volume from the auxiliary equipment such as an air pump and a fan can be reduced. Therefore, the fuel cell system can be reduced in size as well as contributing to the reduction in power consumption of the fuel cell system.

<Spacer>
The spacer 206 forming the spacer layer 26 is preferably a porous one having openings for air circulation. By using a porous spacer 206, air circulation in the fuel cell stack can be activated and air can be easily taken into the fuel cell stack. Moreover, if the spacer 206 is porous, the effect of increasing the water evaporation rate of the water absorbing member 24 can also be obtained.

Further, when the porous spacer 206 is used, the porous spacer 206 is preferably water-repellent. By using the water-repellent spacer 206, it is possible to prevent the air circulation opening in the spacer 206 from being buried in water, and the effect of using a porous spacer 206 can be maintained. At this time, it is preferable that the spacer 206 does not touch the water absorbing member 24.

The spacer 206 disposed in the spacer layer 26 is preferably integrated with the anode current collecting layer adjacent to the spacer 206. Examples of a method for integrating the spacer 206 and the anode current collecting layer include adhesion using an adhesive such as a thermosetting resin, diffusion bonding, ultrasonic bonding, and laser welding. Here, “integration” refers to a state in which separation does not occur even if pressure is not applied from the outside. Specifically, it means a state in which the anode current collecting layer and the spacer 206 are bonded together by a chemical bond, an anchor effect, an adhesive force, or the like.

Any spacer 206 can be used without any particular limitation as long as it maintains a strength that can secure the space 210 between the fuel cell layers even when an external force is applied to the fuel cell stack. It is preferable to use a conductive material. By using a conductive material, the anode current collecting layer of the unit cell of one fuel cell layer and the other fuel cell layer of two adjacent fuel cell layers without providing any other external wiring The unit cells can be connected in series by being electrically connected to the cathode electrode. Thereby, a fuel cell stack can be reduced in size.

The material used for the spacer 206 is preferably the same material as the anode current collecting layer. Such materials include carbon materials, conductive polymers, noble metals such as Au, Pt and Pd, metals such as Ti, Ta, W, Nb, Ni, Al, Cr, Ag, Cu, Zn and Su, Si And nitrides, carbides, carbonitrides thereof, and the like, and alloys such as stainless steel, Cu—Cr, Ni—Cr, and Ti—Pt.

Here, the material used for the spacer 206 is preferably a material having a small specific resistance from the viewpoint of reducing voltage drop due to the resistance of the spacer and obtaining higher power generation characteristics. More preferably, it contains at least one element selected from the group consisting of Pt, Ti, Au, Ag, Cu, Ni, and W.

In addition, as a material used for the spacer 206, when using a metal which is easily corroded in an acidic atmosphere such as Cu, Ag, Zn, etc., a noble metal and metal material having corrosion resistance such as Au, Pt, Pd, etc., conductivity By coating the surface with a polymer, conductive nitride, conductive carbide, conductive carbonitride, conductive oxide or the like, corrosion of the spacer 206 can be prevented. Thereby, the lifetime of the unit cell 201 and the fuel cell stack using the unit cell 201 can be extended.

The shape of the spacer 206 is not particularly limited as long as the space 210 for supplying oxygen can be secured between the stacked fuel cell layers, and any shape can be used. From the viewpoint of ensuring a uniform thickness of the space portion 210 and increasing the volume of the space portion 210, the spacer 206 is preferably a strip shape having a long side and a short side. A strip shape having a length of at least one side of the laminated surface is preferable. If the shape of the spacer 206 is a rectangular column, the cross-sectional shape of the spacer 206 is not particularly limited, and may be, for example, an ellipse or a square.

When the spacer 206 includes a conductive material that plays a role of electrical connection between adjacent fuel cell layers, the shape of the spacer 206 is preferably a rectangular parallelepiped shape. By making the spacer 206 into a rectangular parallelepiped shape, the front and back fuel cell layers adjacent to the spacer 206 can be brought into contact with each other, so that the electrical contact resistance can be reduced.

When the spacer 206 has a rectangular parallelepiped shape, the width of the spacer 206 is preferably 0.5 mm or more and 5 mm or less. If the spacer width is less than 0.5 mm, the structural strength of the fuel cell stack may be insufficient, and if it exceeds 5 mm, oxygen may not be sufficiently supplied to the cathode electrode of the unit cell 201.

Further, the thickness of the spacer 206 is preferably 0.1 mm or more and 5 mm or less, and more preferably 0.2 mm or more and 1 mm or less. If the thickness of the spacer is less than 0.1 mm, it is difficult to supply oxygen into the space 210 formed by the spacer (the cathode electrode of the unit cell 201). If the thickness exceeds 5 mm, the fuel cell stack becomes large. There is a tendency to become.

The number of the spacers 206 arranged between the two adjacent fuel cell layers 21 is not particularly limited as long as the space 210 between the two fuel cell layers 21 can be secured. You can select the quantity. From the viewpoint of stably securing the space 210 between the fuel cell layers 21 even when an external force is applied to the fuel cell stack, the spacer layer 26 composed of two or more spacers 206 is preferable.

(Third embodiment)
FIG. 4 is a diagram schematically showing another preferred example of the fuel cell system of the present invention. As shown in FIG. 4, the fuel cell system 30 of the present invention may include a water absorbing member 34 on the side surface as well as the bottom surface of the fuel cell stack. In this case, a heat source 32 is provided so as to be in contact with a part of these water absorbing members 34.

FIG. 4 shows a structure in which the water absorbing members 34 are provided on the bottom and side surfaces of the fuel cell stack and the water absorbing members 34 are joined to each other, but only when the water absorbing members 34 are joined together in this way. The present invention is not limited, and the case where they are provided separately is also included in the scope of the present invention. However, when each water absorbing member 34 is provided separately, the effect of the present invention cannot be sufficiently obtained unless a heat generation source is provided so as to be in contact with each water absorbing member.

FIG. 4 shows a structure in which three fuel cell layers 31 and two spacer layers are alternately stacked. Each fuel cell layer 31 includes four unit cells 301, and each spacer layer has three layers. Although a fuel cell system 30 including one spacer is shown, the present invention is not limited to this structure.

In the fuel cell stack of the present embodiment, the dew condensation water generated at the cathode electrode of the unit cell 301 is absorbed by the water absorbing member 34 provided at the lower part of the fuel cell stack by gravity, or a spacer 306 is used. It is either absorbed by the water absorbing member 34 provided on the side surface of the fuel cell stack.

<Layer made of water-absorbing material>
As in the fuel cell stack of the present embodiment, a layer 35 made of a water-absorbing material that covers a part of the surface of the spacer 306 and is in contact with the water-absorbing member 34 (hereinafter referred to as “produced water Part ”). By providing the generated general water portion in this way, the condensed water generated at the cathode electrode can be held on the water absorbing member 34 via the generated general water portion of the spacer 306. For this reason, even if the condensed water generated at the cathode electrode is difficult to fall due to gravity, the condensed water can be absorbed by the water absorbing member 34, and the power generation characteristics of the unit cell 301 can be stabilized.

The contact between the layer 35 made of the water-absorbing material and the water-absorbing member 34 means that a part of the layer made of the water-absorbing material is in contact with the water-absorbing member 34, as shown in FIG. The end portion of the layer made of may be in contact with the water absorbing member 34.

The layer 35 made of a water-absorbing material is preferably provided on the surface of the spacer 306 that is not in contact with the unit cell 301 from the viewpoint of ensuring electrical conductivity between the spacer 306 and the unit cell 301. Further, from the viewpoint of facilitating delivery of generated water from the layer 35 made of the water absorbing material to the water absorbing member 34, the capillary force of the layer 35 made of the water absorbing material may be smaller than the capillary force of the water absorbing member 34. preferable.

As the material used for the layer 35 made of such a water-absorbing material, it is necessary to use a material that does not dissolve in water and liquid fuel, like the material used for the water-absorbing member 34. As such a material, a porous body made of an inorganic substance such as a metal or an organic substance such as a polymer material is preferably used. Examples of such a porous body include foams, fiber bundles, woven fibers, non-woven fibers, porous sintered bodies, and combinations of these materials.

When a porous body made of an organic substance such as a polymer material is used for the layer 35 made of a water-absorbing material, for example, natural fiber, polyester, polyethylene, polyurethane, acrylic, polyamide, polyolefin, polyacetal, polyvinyl, polycarbonate, poly It is more preferable to use a fiber bundle, woven fiber, or non-woven fiber composed of one or a combination of two or more selected from ether, polyphenylene, and the like.

<Electronic equipment>
FIG. 5 is a diagram schematically illustrating a preferred example of an electronic device equipped with the fuel cell system according to the first embodiment. 5 schematically illustrates a mobile phone, FIG. 5A is a rear view of the mobile phone, and FIG. 5B is a side view of the mobile phone.

As shown in FIG. 5, the electronic device 110 on which the fuel cell system 10 of the present invention is mounted includes a fuel cell stack 11, a water absorbing member 14, a heat generating source 12, and a heat conducting member 13. The heat source 12 is in contact with the heat source 12 via the heat conducting member 13. The openings for supplying air to the fuel cell stack 11 are provided on the three side surfaces and the upper surface that do not face the casing of the electronic device 110 in FIG.

In the fuel cell stack 11, the water generated by the chemical reaction at the cathode electrode of the unit cell 101 is held by the water absorbing member 14, and the water absorbed by the water absorbing member 14 is vaporized by the heat of the heat generating source 12, and the fuel cell stack. 11 is discharged to the outside, the water absorbing member 14 is saturated and the occurrence of liquid leakage can be prevented.

Here, it is preferable that the heat source 12 used in the electronic device of the present invention is an electronic component essential for use of the electronic device. As shown in FIG. 5, by using an electronic component essential for using the electronic device 110 as the heat source 12 of the fuel cell system, the water absorbed by the water absorbing member 14 can be efficiently vaporized. Moreover, since it is possible to prevent an excessive temperature rise of the electronic component of the electronic device 110, the driving of the electronic device 110 can be stabilized.

FIG. 6 is a diagram schematically showing a preferred example of an electronic device equipped with the fuel cell system of the third embodiment. The electronic device in FIG. 6 schematically represents a notebook personal computer, and includes the fuel cell system 30 of the third embodiment. The electronic device 310 includes a fuel cell stack, a heat generation source 32, and a heat conduction member 33, and a water absorbing member 34 of the fuel cell system is in contact with the heat generation source 32 through the heat conduction member 33.

As shown in FIG. 6, the water produced by the chemical reaction of the unit potential in the fuel cell stack is held by the water absorbing member 34 provided on the bottom or side surface of the fuel cell stack. And since the water | moisture content absorbed by the water absorption member 34 is vaporized with the heat | fever of the heat-generation source 32, and it discharge | releases to the exterior of a cell, it can prevent that the water absorption member 34 will be saturated and a liquid leak will arise. .

Here, the heat source 32 of the fuel cell system shown in FIG. 6 is preferably an electronic component essential for the use of electronic equipment. In FIG. 6, a CPU used for driving a notebook personal computer is used as the heat source 32. As described above, by using the electronic component essential for the use of the electronic device 310 as the heat generation source 32 of the fuel cell system, the water absorbed by the water absorbing member 34 can be efficiently vaporized. In addition, it is possible to prevent overheating of the electronic components of the electronic device 310, and to stabilize the driving of the electronic device 310.

In the electronic device of FIG. 6, two of the six surfaces of the fuel cell stack are open as air intake supply openings, and the water absorbing member 34 located on the side surface of the fuel cell stack is an air intake supply opening. It is provided on one side of the fuel cell stack.

<Example>
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

A fuel cell stack having the same structure as the fuel cell stack 11 having the structure shown in FIG. 1 was produced. Hereinafter, a method for producing the fuel cell stack of Example 1 will be described.

First, as an electrolyte membrane used in the unit cell 101 constituting the fuel cell stack 11, an electrolyte membrane having a width of 25 mm × a length of 25 mm and a thickness of about 175 μm (trade name: Nafion (registered trademark) 117 (manufactured by DuPont) ) Was prepared. Next, catalyst-carrying carbon particles (trade name: TEC66E50 (Tanaka Kikinzoku Kogyo Co., Ltd.) consisting of Pt and Ru particles having a Pt-carrying amount of 32.5% by mass and a Ru-carrying amount of 16.9% by mass and carbon particles. Company)), an alcohol solution containing 20% by mass of Nafion (registered trademark) (manufactured by Sigma-Aldrich Japan Co., Ltd.), isopropanol, and alumina balls in a mass ratio of 0.5: 1.5: 1. An anode catalyst paste was prepared by placing in a Teflon (registered trademark) container at a ratio of 6: 100 and mixing at 500 rpm for 50 minutes using a stirrer.

Further, the catalyst support carbon particles (trade name: TEC10E50E (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.)) composed of Pt particles having a Pt support amount of 46.8% by mass and carbon particles were used. The cathode catalyst paste was prepared by the method.

Next, a carbon paper (trade name: 25BC (manufactured by SGL Carbon Japan Co., Ltd.)) having an outer diameter of 23 mm × 23 mm as a base of the anode electrode and water-repellent treatment with a layer composed of a fluorine-based resin and carbon particles on one side Was used. Then, a square opening having a width of 23 mm and a length of 23 mm is formed on the surface of the carbon paper that has been subjected to the water-repellent treatment so that the amount of the catalyst supported on the anode catalyst paste prepared above is 2 mg / cm ^2. Screen printing was performed on the entire surface of the carbon paper on which the microporous layer was formed. Thereafter, the screen-printed anode catalyst paste was dried at room temperature to produce an anode electrode having an anode catalyst layer having a thickness of about 50 μm.

Further, by the same method as that for the anode electrode, the cathode catalyst paste obtained above was screen-printed using the same carbon paper as described above to form a cathode electrode having a cathode catalyst layer having a thickness of about 50 μm. Through the above steps, an electrolyte membrane, an anode electrode, and a cathode electrode constituting the unit cell were produced.

Next, as shown in FIG. 2, the anode electrode 103 and the cathode electrode 104 overlap at the center of the electrolyte membrane 102 with the electrolyte membrane 102 obtained above sandwiched therebetween, and the anode catalyst layer and the cathode catalyst layer are connected to the electrolyte membrane 102. The anode electrode 103, the electrolyte membrane 102, and the cathode electrode 104 are laminated in this order so as to be in contact with each other, and this is a 100 mm × 100 mm frame-shaped Teflon having a 50 mm × 50 mm square through hole (thickness 0.30 mm). (Registered trademark) installed in the through hole of the spacer. Then, after sandwiching between 100 mm × 100 mm and a stainless steel plate having a thickness of 3 mm, thermocompression bonding was performed at 130 ° C. and 5 kgf / cm ² for 2 minutes in the thickness direction of the stainless steel plate, and anode electrode 103, electrolyte membrane 102, and cathode electrode A membrane electrode assembly 106 in which 104 was integrated was produced.

Next, a flat plate made of sulfate-resistant stainless steel SUS316L having an outer shape of 25 mm × 25 mm and a thickness of 300 μm was used as the anode current collecting layer 105. The flat plate was etched to form a fuel flow path 107 having a groove width of 500 μm and a depth of 200 μm.

Then, the anode current collecting layer 105, the anode electrode 103, and the like from below into the through hole of the frame-shaped Teflon (registered trademark) spacer having a square through hole of 50 mm × 50 mm and a thickness of 0.6 mm, A laminate in which the electrolyte membrane 102 and the cathode electrode 104 were laminated in this order was installed. This was sandwiched between stainless steel plates of 100 mm × 100 mm and thickness 3 mm, and then united by thermocompression bonding at 130 ° C. for 2 minutes at 5 kgf / cm ² in the thickness direction of the stainless steel plate to produce unit battery 101. Another unit cell 101 was manufactured by the same method, and the fuel cell stack 11 was formed by arranging the interlayer distance between the unit cells 101 as shown in FIG.

Next, the water absorbing member 14 of the fuel cell system was produced. The material of the water absorbing member 14 was a polyester nonwoven fabric (manufactured by Bell Development Co., Ltd.) having a basis weight of 600 g / cm ² and containing a low boiling point polyester binder and a water absorbing polymer. Then, the polyester nonwoven fabric was sandwiched between stainless plates using a 3 mm spacer, hot-pressed at 100 ° C. and 100 kN for 1 minute, naturally cooled to 70 ° C. while maintaining a pressure of 100 kN, A porous material having a thickness of 3 mm and a specific gravity of 0.19 g / cm ³ was formed. And what cut out the said porous material to the magnitude | size of 3 cm x 2 cm was used as the water absorption member 14. FIG.

Next, a silicon rubber heater was used as the heat source 12. And the heat conductive member 13 was formed by apply | coating the 100-micrometer-thick epoxy-type heat conductive adhesive (made by 3M company) on the said silicon rubber heater using a bar coater. The heat conducting member 13 also has a bonding function. The water absorbing member 14 is laminated on the heat conducting member 13 and dried at 80 ° C. for 60 minutes, whereby the heat conducting member 13 and the water absorbing member 14 are obtained. And glued together.

While monitoring the temperature near the heat conducting member 13 with a K thermocouple, feedback was performed by PID control, and a silicon rubber heater was set to 50 ° C. and used as a simulated heat source 12.

Next, a Teflon (registered trademark) tube having an outer diameter of 360 μm (inner diameter: 150 μmφ) is inserted from the end of the fuel flow path 107 into the fuel flow path, and a gap between the Teflon (registered trademark) tube and the end of the fuel flow path 107 is inserted. Was filled with epoxy resin and dried to prepare a fuel supply connection. Thus, the fuel cell system shown in FIG. 1 was produced.

FIG. 7 is a view showing the fuel cell system when the fuel cell stack 11 and the water absorbing member 14 of the fuel cell system 10 of FIG. As shown in FIG. 7, the fuel cell stack and the water absorbing member of the fuel cell system were covered with an acrylic casing 100. This acrylic casing 100 has an outer width of 3 cm × depth of 2 cm × height of 4 cm, and has an air intake and supply opening 15 formed on the three horizontal surfaces and the upper surface. Then, power generation evaluation was performed by supplying a 3M aqueous methanol solution to the fuel flow path of the fuel cell stack using a pump at a speed of 0.5 cc / min to generate power. As a result of this power generation evaluation, the power density after 5 minutes of the fuel cell stack was 40 mW / cm ² , and the power density after continuous use for 1 hour was 30 mW / cm ² . Furthermore, no liquid leakage was confirmed even after 5 hours of continuous use.

(Comparative Example 1)
The fuel cell system of Comparative Example 1 has a structure in which the heat conducting member and the heat source of the fuel cell system of Example 1 are excluded, and the fuel of Comparative Example 1 is the same as in Example 1 except for the above. A battery system was fabricated.

That is, the fuel cell system of Comparative Example 1 includes the fuel cell stack of Example 1 and a water absorbing member. When power generation was evaluated under the same conditions as in Example 1, an output density of 35 mW / cm ² was obtained after 5 minutes. However, the power density after 1 hour of continuous use decreased to 12 mW / cm ² , and after 5 hours of continuous use, liquid leakage occurred from the water absorbing member.

In the fuel cell systems of Example 1 and Comparative Example 1, it was found that Example 1 was superior to 5 mW / cm ² by comparing the power density after 5 minutes from the start of use. From this, it was found that the fuel cell system of Example 1 was superior in maximum power density.

Further, in the fuel cell systems of Example 1 and Comparative Example 1, when comparing the power density after one hour has elapsed since the start of use, the power density of Example 1 is about three times the power density of Comparative Example 1. Are better. From this, it was found that the fuel cell system of Example 1 was superior in terms of output stability.

Further, in the fuel cell systems of Example 1 and Comparative Example 1, when the state after 5 hours from the start of use is compared, the fuel cell system of Example 1 is not leaked. In the fuel cell system of Example 1, liquid leakage occurred. This is considered to be due to the fact that the fuel cell system of Comparative Example 1 does not include a heat generation source and a heat conduction member.

In Example 2, a fuel cell stack having the same structure as the fuel cell stack having the structure shown in FIG. 2 was produced. Hereinafter, a method for producing the fuel cell stack of Example 2 will be described. First, a membrane electrode assembly composed of a cathode electrode, an electrolyte membrane, and an anode electrode produced by the same method as in Example 1 was cut with a trimming knife so that the outer shape was 2 mm × 25 mm and the electrode portion was 2 mm × 23 mm, A strip-shaped membrane electrode assembly was prepared.

Next, a flat plate made of sulfuric acid-resistant stainless steel SUS316L having an outer shape of 2 mm × 25 mm and a thickness of 300 μm was used as the anode current collecting layer. The flat plate was etched to form a fuel flow path having a groove having a width of 800 μm and a depth of 200 μm.

Then, an anode current collecting layer, an anode electrode, and an electrolyte membrane are inserted into the through holes of the frame-shaped Teflon (registered trademark) spacer having a square through hole of 50 mm × 50 mm and a thickness of 0.6 mm from below. The cathode electrodes were stacked in this order. This was sandwiched between 100 mm × 100 mm and 3 mm thick stainless steel plates, and then set to 130 ° C. and integrated by thermocompression bonding at 5 kgf / cm ² for 2 minutes in the thickness direction of the stainless steel plates to produce unit cells. A total of ten unit cells 201 were produced by the same method.

The spacer 206 was produced by press-molding a titanium fiber sintered body (manufactured by Bekinit Co., Ltd.) having an outer shape of 1 × 14 mm, a thickness of 600 μm, and a porosity of 80% so as to have a thickness of 400 μm.

Next, the long sides of the unit cell 201 were opposed to each other, a gap 214 of 1 mm was provided between the opposed long sides, and five pieces were arranged on a plane to produce one fuel cell layer 21.

Next, a conductive paste (trade name: CARBOLLOID MRX-713J (manufactured by Tamura Kaken Co., Ltd.)) was applied to one surface of the spacer 206 using a screen printing method so as to have a coating thickness of 30 μm. Then, four spacers 206 were arranged at a pitch of 2 mm so as to be orthogonal to the unit cell 201 of the fuel cell layer 21 to form the spacer layer 26, and laminated on the fuel cell layer 21 produced above.

The fuel cell layer 21 and the four spacers 206 were installed in the through holes of a 100 mm × 100 mm frame-shaped Teflon (registered trademark) spacer having a square through hole of 50 mm × 50 mm. After these were sandwiched between stainless steel plates of 100 mm × 100 mm and thickness 3 mm, the fuel cell layer 21 and the spacer 206 were integrated by thermocompression bonding at 130 ° C. and 5 kgf / cm ² for 30 minutes in the thickness direction of the stainless steel plate, A stack of fuel cell layer 21 and spacer layer 26 was produced.

Subsequently, a fuel cell layer 21 was further produced on the spacer layer 26 of the laminate. Hereinafter, for convenience of explanation, the fuel cell layer 21 formed first is referred to as a “first fuel cell layer”, and the fuel cell layer 21 formed in the following process is referred to as a “second fuel cell layer”. However, the first fuel cell layer and the second fuel cell layer do not distinguish the performance as the fuel cell layer.

On the surface of the spacer 206 opposite to the surface in contact with the first fuel cell layer, a conductive paste (made by Tamura Kaken: CARBOLLOID MRX-713J) is applied by screen printing so that the coating thickness becomes 30 μm. Applied.

Next, the first fuel cell is inserted into the through hole of the frame-shaped Teflon (registered trademark) spacer having a square through hole of 50 mm × 50 mm and a thickness of 1.5 mm through the spacer 206. The unit cell of the layer and the unit cell 201 of the second fuel cell layer are at the same position, and the cathode of the unit cell 201 constituting the second fuel cell layer and the spacer 206 are opposed to each other Was installed.

These were sandwiched between 100 mm × 100 mm and 3 mm thick stainless steel plates, and then integrated by thermocompression bonding at 130 ° C. for 30 minutes with a pressure of 5 kgf / cm ^{2 in} the thickness direction of the stainless steel plates, and the first fuel cell layer from above A laminated body in which the spacer 206 and the second fuel cell layer were laminated in order was produced.

Next, when power generation evaluation was performed under the same conditions as in Example 1, the power density after 5 minutes of the fuel cell stack according to the present embodiment was 44 mW / cm ² , and after the continuous use for 1 hour. The power density was 41 mW / cm ² . Furthermore, no liquid leakage was confirmed even after 5 hours of continuous use.

In the fuel cell systems of Example 1 and Example 2, it was found that Example 2 was superior to 4 mW / cm ² by comparing the power density after 5 minutes from the start of use. From this, it can be said that the fuel cell system of Example 2 is superior in maximum power density.

Further, in the fuel cell systems of Example 1 and Example 2, it was found that Example 2 was superior to 11 mW / cm ^{2 when} the output density after 1 hour had elapsed since the start of use was compared. From this, it can be said that the fuel cell system of Example 2 is superior in terms of output stability.

As described above, the fuel cell system of Example 2 is superior in terms of maximum power density and output stability because the fuel cell stack used in the fuel cell system of Example 2 has the spacer layer 26. By including the space 210 and the gap 214 in the fuel cell stack, it is considered that the air could be circulated more efficiently.

Although the embodiments of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments.

It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

According to the present invention, a notebook computer, a mobile phone, an electronic notebook, a portable game device, a mobile TV device, a handy terminal, a PDA, a mobile DVD player, a notebook computer, a video device, a camera device, a ubiquitous device, a mobile generator, etc. A fuel cell system for electronic equipment can be provided.

10, 20, 30 fuel cell system, 11 fuel cell stack, 12, 22, 32 heat source, 13, 23, 33 heat conduction member, 14, 24, 34 water absorption member, 15 opening, 21, 31 fuel cell layer, 26 spacer layer, 35 layer made of water-absorbing material, 100 acrylic casing, 101, 201, 301 unit cell, 102 electrolyte membrane, 103 anode electrode, 104 cathode electrode, 105 anode current collecting layer, 106 membrane electrode composite, 107 Fuel flow path, 110, 310 electronic device, 206, 306 spacer, 210 space, 214 gap.

Claims (8)

A fuel cell stack (11) including two or more unit cells (101, 201, 301) each including a cathode electrode (104), an electrolyte membrane (102), and an anode electrode (103) in this order;
A water absorbing member (14, 24, 34) that is disposed on the outer surface of the fuel cell stack (11) so as to be in spatial communication with the cathode electrode (104) and absorbs water generated from the cathode electrode (104). When,
A fuel cell system (10, 20, 30) comprising a heat source (12, 22, 32) for heating the water absorbing member (14, 24, 34). It arrange | positions so that the said water absorption member (14,24,34) and the said heat-generation source (12,22,32) may be contacted, and the heat from the said heat-generation source (12,22,32) is transmitted to the said water-absorption member (14,24,32). 34. The fuel cell system (10, 20, 30) according to claim 1, further comprising a heat conducting member (13, 23, 33) conducting to 34). A sheet-like heat conducting member (13, 23, 33);
A sheet-like water absorbing member (14, 24, 34) laminated on the heat conducting member (10, 20, 30);
The fuel cell system (10, 20, 30) according to claim 2, further comprising a fuel cell stack (11) disposed on the water absorbing member (14, 24, 34). The fuel cell stack (11, 21, 31) includes one or more unit cells (101, 201, 301) and a fuel cell layer (21, 31) in which a gap is provided in the same plane. The spacer layer (26) composed of two or more spacers (206, 306) arranged so as to intersect with the unit cells (101, 201, 301) is alternately stacked. Fuel cell system (10, 20, 30). The unit battery (101, 201, 301) includes a cathode electrode (104), an electrolyte membrane (102), an anode electrode (103), and an anode current collecting layer (105) in this order. The fuel cell system described (10, 20, 30). A layer (35) made of a water-absorbing material is formed so as to cover a part of the surface of the spacer (206, 306) and to be in contact with the water-absorbing member (14, 24, 34). 5. The fuel cell system (10, 20, 30) according to item 4. The fuel cell system (10, 20, 30) according to claim 6, wherein the capillary force of the layer (35) made of the water absorbing material is smaller than the capillary force of the water absorbing member (14, 24, 34). . An electronic device (110, 310) comprising the fuel cell system (10, 20, 30) according to claim 1.
The heat source (12, 22, 32) of the fuel cell system (10, 20, 30) is an electronic device (110, 310), which is an electronic component constituting the electronic device (110, 310).

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