CN1691386A - Fuel cell power supply, method of operation thereof, and portable electronic device using the same - Google Patents

Abstract

The fuel cell is provided with a means of supplying liquid fuel and water supplied to an anode with one pump in time division manner. Thus, since a concentration control mechanism for detecting the concentration of the liquid fuel and maintaining a specified concentration is used in conventional fuel cells carrying out circulated use of fuel cell, a plurality of pumps, such as the pump to transport high concentration liquid fuel and the pump transporting water were necessary. Furthermore, the problem is solved, wherein the fuel cell power source itself being enlarged, due to the use of a plurality of pumps and having the occupancy space by auxiliary machinery, such as the pumps becoming large as a result.

Description

Fuel cell power supply, method of operation thereof, and portable electronic device using it

technical field

The present invention relates to a fuel cell power supply using liquid such as methanol in fuel, an operating method thereof, and a portable electronic device using the fuel cell power supply.

Background technique

A fuel cell is characterized by high energy efficiency because it directly converts the chemical energy of fuel into electrical energy by using an electrochemical reaction. In addition, because of the fuel cell, power generation can be continuously performed when only the fuel is replaced or replenished, and there is no need to temporarily stop the operation of the portable electronic device for charging as observed in the case of the secondary battery. Therefore, in recent years, it has attracted much attention as a power supply unit for portable electronic devices.

Among them, fuel cells using liquid fuels such as methanol, ethanol, propanol, dimethyl ether, and ethylene glycol, which have a higher volumetric energy density than gases such as hydrogen, are being studied, and power supply units for portable electronic devices are being developed.

In recent years, research and development of a so-called direct methanol fuel cell (DMFC) that uses methanol as a fuel cell as a liquid fuel has become increasingly active.

Among them, a fuel cell power generation device has been proposed that can increase fuel utilization efficiency and DMFC output by increasing the initial concentration of methanol aqueous solution in methanol aqueous solution to a high concentration (for example, refer to Patent Document 1). This Patent Document 1 is a fuel cell power generator that evaluates the concentration of methanol aqueous solution in a methanol aqueous solution container using the total electric power obtained from the battery, and controls the flow rate of methanol aqueous solution supplied to the battery in accordance with the evaluated methanol aqueous solution concentration. In addition, this patent document 1, as a device that can be driven for a long time, also has a second methanol aqueous solution container and a second liquid supply pump as a methanol replenishing unit for replenishing the methanol aqueous solution to the above methanol aqueous solution container to control the methanol aqueous solution supplied to the battery. The flow rate of the fuel cell power plant (fuel cell power supply).

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-22830 (page 2).

Contents of the invention

However, since a conventional fuel cell that circulates liquid fuel uses a concentration control structure that detects the concentration of liquid fuel and maintains a predetermined concentration, multiple pumps such as a pump that supplies high-concentration liquid fuel and a pump that supplies water is compulsory. The use of these multiple pumps increases the space occupied by auxiliary machines such as pumps in the fuel cell power supply, resulting in a problem that the size of the fuel cell power supply itself increases.

The object of the present invention is to make a fuel cell power supply smaller than a fuel cell power supply requiring a plurality of pumps.

The present invention provides a fuel cell having a unit that supplies liquid fuel and water to an anode in a time-division manner using one pump.

According to the present invention, the fuel cell can be miniaturized by reducing the number of pumps.

Description of drawings

FIG. 1 is a diagram for explaining the structure of a direct methanol fuel cell.

Fig. 2 is a structural diagram for explaining a fuel cell power supply.

FIG. 3 is a diagram for explaining the flow of liquid fuel and water of a fuel cell power source.

FIG. 4 is a flowchart of a processing routine I for adjusting the concentration of liquid fuel used in a fuel cell power supply.

FIG. 5 is a flowchart of a processing routine II for adjusting the concentration of liquid fuel used in a fuel cell power supply.

Fig. 6 is a diagram for explaining a schematic configuration of a liquid delivery pump used in a fuel cell power supply.

FIG. 7 is a diagram for explaining a schematic configuration of a time-divided liquid delivery pump used in a fuel cell power supply.

8 is a graph showing changes over time in the delivery amount and concentration of a liquid delivery pump capable of time division used in the fuel cell power supply of Example 5. FIG.

9 is a graph showing changes over time in the delivery amount and concentration of a liquid delivery pump that can be time-divided used in the fuel cell power supply of Embodiment 6. FIG.

FIG. 10 is a graph showing voltage-current characteristics of the fuel cell power supply of Embodiment 1. FIG.

11 is a graph showing the relationship between time and output voltage when the fuel cell power supply of Embodiment 1 continuously generates power.

12 is a graph showing voltage-current characteristics of a fuel cell power supply of Comparative Example 1. FIG.

13 is a graph showing the relationship between time and output voltage when the fuel cell power supply of Comparative Example 1 continuously generates power.

Fig. 14 is a diagram for explaining a schematic configuration of a notebook type personal computer of the present invention.

Fig. 15 is a photograph showing the appearance of the PDA of the present invention.

Fig. 16 is a diagram for explaining the schematic structure of the PDA of the present invention.

FIG. 17 is a diagram for explaining the structure of a fuel cell power source used in Comparative Example 1. FIG.

Detailed ways

Next, embodiments of the fuel cell power supply of the present invention and a portable electronic device using the fuel cell power supply will be described in detail. However, the present invention is not limited to the following

implementation.

First, a standard DMFC will be described as an example of a fuel cell using liquid fuel. FIG. 1 is a diagram showing a schematic structure of a DMFC. DMFC100 includes: a solid polymer electrolyte membrane 102; an electrolyte membrane/electrode assembly (MEA; membrane-electrode assembly) in which the anode catalyst layer 103 and the cathode catalyst layer 104 are joined together on both sides of the solid polymer electrolyte membrane 102 and an anode diffusion layer 105 and a cathode diffusion layer 106 that are in close contact with the outside of the anode catalyst layer 103 and the cathode catalyst layer 104, respectively. In addition, a fuel channel plate 107 is disposed outside the anode diffusion layer 105 . A fuel flow path 110 having a fuel supply port 108 and a fuel discharge port 109 is formed on the fuel flow path plate 107 .

A methanol aqueous solution is supplied to the fuel supply port 108 via a liquid delivery pump. In addition, similarly, an air flow channel plate 111 is disposed outside the cathode diffusion layer 106 . An air flow path 114 having an air supply port 112 and an air discharge port 113 is formed on the air flow path plate 111 . An oxidizing agent (here, oxygen) such as air is supplied to the air supply port 112 by a blower, an air blower, or the like. The methanol aqueous solution sent from the methanol aqueous solution container by the liquid delivery pump and the methanol aqueous solution supplied to the fuel supply port 108 of the fuel flow channel plate 107 flow through the groove portion of the fuel flow channel plate 107 (fuel flow channel 110 ). The methanol aqueous solution flowing through the fuel flow channel 110 is soaked into the anode diffusion layer 105 in contact with the fuel flow channel plate 107 , and the methanol aqueous solution is uniformly supplied to the anode catalyst layer 103 . In addition, the anode catalyst layer 103 and the anode diffusion layer 105 are collectively referred to as an anode electrode (negative electrode) or an anode gas diffusion electrode, here abbreviated as an anode electrode 120 . Similarly, the cathode catalytic layer 104 and the cathode diffusion layer 106 are collectively referred to as the cathode electrode (negative electrode) or the cathode gas diffusion electrode, here referred to as the cathode electrode 130 for short.

Next, the reaction of the methanol aqueous solution supplied to the anode catalyst layer 103 will be described. The methanol aqueous solution is decomposed into carbon dioxide gas (CO ₂ ), hydrogen ions (H ⁺ ) and electrons (e ^- ) by the reaction represented by the formula (1) as follows.

(1)

The generated protons move from the anode 120 side to the cathode 130 side in the solid polymer electrolyte membrane 102, and oxygen (O ₂ ) in the air reacts with electrons (e ^- ) on the cathode catalyst layer 104 according to formula (2) to generate water ( _H2O ).

(2)

According to above-mentioned reaction formula (1), the full chemical reaction formula of reaction formula (2) electrochemical reaction, with reaction formula (3) formula expression. DMFC converts chemical energy directly into electrical energy according to formula (3) to generate electromotive force.

(3)

However, the methanol aqueous solution flowing through the fuel channel plate 107 of the DMFC 100 cannot completely infiltrate into the anode diffusion layer 105 . Part of the aqueous methanol solution does not undergo the reaction of the reaction formula (1), and flows out from the fuel discharge port 109 of the fuel flow channel plate 107 as it is. Therefore, there is a problem that the utilization efficiency (reaction efficiency) of the methanol aqueous solution supplied to the DMFC is lowered. In order to improve this efficiency, attempts have been made to improve the structure of the fuel flow channel plate 107, but the present situation is that this utilization efficiency has not been improved. Therefore, in order to improve the utilization efficiency, once the methanol aqueous solution discharged from the fuel discharge port 109 of the fuel passage plate 107 is returned to the methanol aqueous solution container, reuse is attempted.

However, in the anode catalyst layer 103, since the aqueous methanol solution and water react with 1:1 (molar ratio) as shown in the above-mentioned formula (1), the consumption of the aqueous methanol solution (molecular weight=32) is About 1.8 times. Therefore, when the aqueous methanol solution discharged from the fuel passage plate 107 is returned to the aqueous methanol storage container as it is, the concentration of the aqueous methanol solution in the storage container gradually decreases. Therefore, when the methanol aqueous solution whose concentration has been reduced by recycling is used as it is, the reaction shown in the above reaction formula (1) cannot proceed sufficiently due to insufficient methanol inside the battery, and the generated electromotive force (output voltage) decreases sharply. The problem.

Methanol and water in the methanol aqueous solution supplied to the anode catalyst layer 103 in FIG. 1 generate protons (H ⁺ ), carbon dioxide gas (CO ₂ ) and electrons (e ^- ) according to the reaction formula shown in (1). The generated carbon dioxide gas is discharged from the anode catalyst layer 103 through the anode diffusion layer 105 along the fuel flow path 110 from the fuel discharge port 109 . This generated carbon dioxide gas sometimes grows into large bubbles from the state of tiny bubbles in methanol aqueous solution in the anode catalytic layer 103 or anode diffusion layer 105 in the anode, and the large bubbles of carbon dioxide gas often hinder the anode diffusion layer 105 in particular. The flow of liquid fuel in. Therefore, the methanol aqueous solution supplied to the anode catalyst layer 103 becomes insufficient, resulting in a decrease in power generation capability (decrease in output voltage).

Therefore, it is also necessary to smoothly discharge the generated carbon dioxide gas from the anode catalyst layer 103 or the cathode diffusion layer in the anode without hindering the supply of methanol aqueous solution to the anode catalyst layer 103 .

The structure of the fuel cell power supply of the present invention is shown in FIG. 2 .

In FIG. 2 , the fuel cell power supply 1 mainly includes a fuel cell unit 10 , a liquid fuel supply unit 20 , a control unit 30 , a power storage unit 40 and an oxidant gas supply unit 50 .

The fuel cell unit 10 is constituted by the same liquid fuel cell as that of the DMFC 100 shown in FIG. 1 . The fuel cell unit 10 is an electric fuel cell using liquid fuel supplied from a liquid fuel supply unit 20 (hereinafter, methanol will be used as a representative example) and an oxidizing gas supplied from an oxidizing gas supply unit 50 (air will be described below as a representative example). The part of a chemical reaction that generates electricity. The liquid fuel supply unit 20 is composed of a tank 21 for storing water, a tank 22 for storing a high-concentration methanol aqueous solution, and a liquid delivery pump 23 for supplying the high-concentration methanol aqueous solution and water to the liquid fuel supply unit 20 . The control unit 30 is composed of a logic circuit centered on a microcomputer, and has a signal processing unit 31 that uses a CPU for signal processing; a storage unit 32 that uses a memory such as ROM or RAM for storing; and an input/output board that inputs and outputs various signals. (not shown), etc. The control unit 30 is a unit that controls the entire fuel cell power supply 1, and uses a microcomputer to control the supply amount of the high-concentration methanol aqueous solution and water supplied to the fuel cell unit 10 and the supply liquid delivery pump 23; control of the power storage unit 40 ; and control of an air blower supplied from the oxidant gas supply unit 50 to the fuel cell unit 10 . The power storage unit 40 is composed of a DC-DC converter (chopper) 41 and a power storage unit 42 (a rechargeable lithium ion secondary battery, a supercapacitor, etc.). The power storage unit 40 boosts the DC power obtained by the power generation of the fuel cell unit 10 by a DC-DC converter (chopper) 41, and uses the boosted DC power to charge and discharge the lithium ion batteries. The power storage unit 42 such as a secondary battery or a supercapacitor is charged, and the electric power charged in the power storage unit 42 is supplied to a portion for discharging to an external load. In addition, the lithium ion secondary battery and supercapacitor of the power storage unit 42 can be supplied by discharge when the fuel cell power supply 1 is started or when the power required by the external circuit is larger than the discharge power of the fuel cell unit 10. The required power. In addition, the lithium ion secondary battery and the supercapacitor of the power storage unit 42 can be applied to power sources (not shown) such as the control unit 30 , the liquid delivery pump 23 , and the air blower 51 . The oxidizing gas supply unit 50 is a unit for supplying an oxidizing gas such as air to the fuel cell unit 10 using an air blower 51 .

The implementation of the fuel cell power supply 1 of the present invention will be described in more detail below with reference to FIG. 3 .

First, the flow of an aqueous methanol solution as a liquid fuel will be described. The methanol aqueous solution supplied to the fuel cell unit 10 , that is, the DMFC 100 , is alternately supplied with water and methanol aqueous solution from the water container 21 and the methanol aqueous solution container 22 of the liquid fuel supply unit 20 by the liquid delivery pump 23 . The flow of water supplied from the water container 21 of the liquid fuel supply unit 20 and the flow path of the methanol aqueous solution supplied from the methanol aqueous solution container 22 alternately utilize the electromagnetic valve 24 provided on the inlet side of the liquid delivery pump 23 to control the flow of water. The flow path and the flow path of the aqueous methanol solution are switched to alternately supply the water and the aqueous methanol solution. In addition, the water and the aqueous methanol solution may be mutually supplied only by the liquid-feeding pump 23 without using the solenoid valve 24 . The alternately supplied water and aqueous methanol solution are supplied to the DMFC 100 from the fuel supply port 108 of the fuel flow channel plate 107 and discharged from the fuel discharge port 109 through the fuel flow channel 110 . Then, the discharged methanol aqueous solution, after removing the generated carbon dioxide gas in the gas-liquid separation unit 25, is mixed with the water or the methanol aqueous solution alternately supplied from the liquid delivery pump 23 in the outlet side pipe of the liquid delivery pump 23 and supplied again. The fuel supply port 108 of the fuel flow channel plate 107 . The methanol aqueous solution flowing through the fuel channel 110 penetrates into the anode diffusion layer 105 made of a porous material such as carbon paper, and is supplied to the anode catalyst layer 103 through the anode diffusion layer 105 . At this time, the aqueous methanol solution penetrates into the cathode diffusion layer in contact with the convex portion of the fuel flow channel plate 107 (a portion not corresponding to the fuel flow channel 110 ), and is supplied to the anode catalyst layer 103 . The aqueous methanol solution supplied to the anode catalyst layer 103 is dissociated into carbon dioxide gas, protons, and electrons according to the above-mentioned reaction formula (1). The generated protons move from the anode side to the cathode side in the solid polymer electrolyte membrane 102 . The protons react with the oxygen component in the air supplied to the cathode catalyst layer 104 and the electrons on the cathode catalyst layer 104 according to the above-mentioned reaction formula (2) to generate water. The generated water is recovered from the air in the gas-liquid separator 52 to the water container 21 to adjust the concentration of the aqueous methanol solution. In addition, the generated electrons pass through the anode catalyst layer 103 and the fuel channel plate 107 and are supplied to the power storage unit 40 . The air supplied to the cathode catalytic layer 104 is supplied to the supply port 112 of the air flow channel plate 111 by the air blower 51 of the oxidant gas supply unit 50, and passes through the cathode diffusion layer 106 by means of the air flow channel 114 provided on the air flow channel plate 111. , supplied to the cathode catalyst layer 104 . The supplied air reacts in the cathode catalyst layer 104 to generate water.

Next, the structure of DMFC 100 will be described in detail. DMFC100 comprises: on the two sides of the electrolytic membrane 102 of solid polymer, the MEA that joins as a whole; The anode diffusion layer 105 that is closely connected to the outside of the anode catalyst layer 103 and the cathode catalyst layer 104 respectively; The cathode diffusion layer 106 and the anode diffusion layer 106 The fuel flow channel plate 107 and the air flow channel plate 111 are also in close contact with each other on the outer sides of the layer 105 and the cathode diffusion layer 106 . A fuel flow path 110 having a fuel supply port 108 and a fuel discharge port 109 is formed on the fuel flow path plate 107 . An air flow path 114 having an air supply port 112 and an air discharge port 113 is formed on the air flow path plate 111 . The solid polymer electrolyte membrane 102 used in this embodiment is not particularly limited as long as it is a solid polymer electrolyte membrane having proton conductivity. Specifically, for example, there are polyperfluorosulfonic acid membranes known under the trade names of Nafion (registered trademark, DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Industries, Ltd.), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). The representative fluorine-based solid polymer electrolyte membrane; disclosed in Japanese Patent Application Laid-Open No. 9-102322, which is produced by copolymerization of fluorocarbon-based vinyl monomers and hydrocarbon-based vinyl monomers, has a main chain and sulfur Sulfonic acid type polystyrene grafted tetrafluoroethylene copolymer (ETFE) film composed of hydrocarbon side chains of acid groups; ETFE film; the membrane produced by the copolymerization of fluorocarbon vinyl monomer and hydrocarbon vinyl monomer disclosed in US Patent No. 4012303 and US Patent No. 4605485, graft polymerization of α, β, β-trifluoroethylene And the partial fluorinated solid polymer electrolyte membranes such as the sulfonic acid type poly(trifluoroethylene)-graft-ETFE film that introduces sulfonic acid group into the solid polymer electrolyte membrane of wherein making; The sulfonated polyether ketone ether solid polymer electrolyte membrane disclosed in the bulletin; the sulfonated polyether ether sulfone solid polymer disclosed in the Japanese Patent Application Laid-Open No. Electrolyte membrane; sulfonated acrylonitrile-butadiene-styrene polymer solid polymer electrolyte membrane disclosed in Japanese Patent Application Laid-Open No. 10-503788; disclosed in Japanese Patent Application Laid-Open No. 11-510198 Sulfonated polysulfide solid polymer electrolyte membrane, sulfonated polyphenylene solid polymer electrolyte membrane; and in Japanese Patent Application Laid-Open No. 2002-110174, in Japanese Patent Application Laid-Open No. 2003-100317 and in Japanese Patent Application Various hydrocarbon-based solid polymer electrolyte membranes, such as the aromatic hydrocarbon-based solid polymer electrolyte membrane disclosed in JP-A-2003-187826, in which alkylenated sulfonic acid groups are introduced. Among them, the aromatic hydrocarbon-based solid polymer electrolyte membrane is preferable from the viewpoint of methanol permeability. From the viewpoint of methanol permeability, swelling property, and durability, an aromatic hydrocarbon-based solid polymer electrolyte membrane into which alkylenated sulfonic acid groups are introduced is particularly preferable. In addition, by using proton conductive inorganic substances such as tungsten oxide hydrate, zirconium oxide hydrate, tin oxide hydrate, etc. or silicotungstic acid, silicomolybdic acid, tungstophosphoric acid, phosphomolybdic acid, etc. Microdispersed composite electrolyte membranes, etc., can produce fuel cells that can operate at higher temperatures. In addition, in these proton-conductive acid electrolyte membranes, protons and water are generally hydrated, and the hydrated acid electrolyte membrane is deformed when it is dry and when it is wet due to the swelling effect of water. Also, the ionic conductivity is sufficiently high.

Sometimes the mechanical strength of the film is insufficient. As a countermeasure in this case, use non-woven or woven fabrics of fibers with excellent mechanical strength, durability, and heat resistance as core materials, or add these fibers as fillers for reinforcement when manufacturing electrolyte membranes, and improve electrolyte performance. It is an effective method in terms of film and further improving reliability. A method of opening pores in the membrane and filling the spaces with an electrolyte is also effective. In addition, in order to reduce the fuel permeability (crossover) of the electrolyte membrane, it is also possible to use a membrane in which polybenzimidazoles are doped with sulfuric acid, phosphoric acid, sulfonic acids, and phosphonic acids.

The sulfonic acid equivalent (dried resin) of the solid polymer electrolyte membrane 102 is preferably in the range of 0.5 to 2.0 meq/g, more preferably in the range of 0.7 to 1.6 meq/g. When the sulfonic acid equivalent is less than this range, the ion conduction resistance of the membrane increases (the ionic conductivity decreases). On the other hand, when the sulfonic acid equivalent is larger than this range, it is easy to dissolve in water, which is not preferable.

The thickness of the solid polymer electrolyte membrane 102 is not particularly limited, but is preferably 10 to 200 μm. 30 to 100 μm is particularly preferable. In order to obtain a practically strong membrane, it is preferably thicker than 10 μm, and in order to reduce membrane resistance, that is, to improve power generation performance, it is preferably thinner than 200 μm. The thickness of the electrolyte membrane can be controlled by the concentration of the electrolyte solution or the thickness of the electrolyte solution coated on the substrate when the solution casting method is used. The thickness of the electrolyte membrane when it is formed from a molten state can be controlled by stretching a membrane of a predetermined thickness produced by a melt press method or a melt lay-up method at a predetermined ratio. In addition, when manufacturing the solid polymer electrolyte membrane 102 used in this embodiment, additives such as plasticizers, stabilizers, and release agents generally used in polymers can be used as long as they do not violate the purpose of this embodiment. .

The catalyst layer of the electrode used in the MEA when used as a fuel cell is composed of conductive material and fine particles of catalytic metal supported by a highly conductive material, and may contain a hydrophobic agent and a binder as necessary. In addition, a layer composed of a catalyst-free conductive material and, if necessary, a water-repellent agent and a binder may be provided on the outside of the catalyst layer. As the catalytic metal used in the catalytic layer of this electrode, as long as it is a metal that can promote the oxidation reaction of hydrogen and the reduction reaction of oxygen, for example, platinum, gold, silver, palladium, iridium, rhodium, Ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, vanadium or their alloys. Among such catalysts, particularly platinum as a cathode catalyst and platinum-ruthenium alloy as an anode catalyst are often used. The particle size of the catalyst metal is usually 10 to 300 angstroms. Attaching these catalysts to a carrier such as carbon can reduce the amount of catalyst used, which is advantageous in terms of cost. In the formed state of the electrode, the amount of the anode catalyst used is 0.5-20 mg/cm ² , preferably 5-15 mg/cm ² , and the amount of the cathode catalyst used is 0.01-10 mg/cm ² , preferably 0.1-10 mg/cm 2 ² . It is preferred that the amount of catalyst at the anode is greater than the amount of catalyst at the cathode. The anode catalyst layer 103 is preferably thicker than the cathode catalyst layer 104 because the reaction of reaction formula (1) in which protons and electrons are generated from methanol and water in the anode catalyst is slow. The thickness of the anode catalyst layer 103 is preferably 20-300 μm, especially 50-200 μm. The thickness of the cathode catalyst layer 104 is preferably 3 to 150 μm, especially 5 to 50 μm. The anode catalyst layer 103 and the anode diffusion layer 105 are preferably subjected to a hydrophilic treatment in order to facilitate wettability with an aqueous fuel solution such as methanol. Conversely, in order to prevent stagnation of water generated in the cathode catalyst layer 104 and the cathode diffusion layer 106 , it is preferable to perform hydrophobic treatment.

The method for carrying out hydrophilic treatment to the anode catalyst layer 103 and the anode diffusion layer 105, for example, has the following method: at first, utilize from hydrogen peroxide, sodium hypochlorite, potassium permanganate, hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, fuming The oxidizing agent selected among sulfuric acid, hydrofluoric acid, acetic acid, ozone, etc. treats the carbon (carbon) material used in the anode catalyst layer 103 and the anode diffusion layer 105, and then the hydroxide group, sulfonic acid group, carboxylic acid Hydrophilic groups such as groups, phosphate groups, sulfate groups, carbonyl groups, and amino groups are introduced into carbon (carbon) materials. In addition, as a method of introducing a hydrophilic group into this carbon (carbon) material, methods such as electrolytic oxidation (anodic oxidation), activation treatment by water vapor oxidation, and addition of a hydrophilic surfactant can also be used.

Since the hydrophilization treatment of the anode catalyst layer 103 that is easy to wet with this methanol fuel and the reaction of the above-mentioned (1) formula dominate the speed of the entire reaction, the cathode catalyst layer 104 is placed in order to prolong the contact time and generate more reactions. Make it thicker; or carry out the hydrophilization treatment of the anode diffusion layer 105 and the hydrophobization of the cathode diffusion layer 106; the carbon dioxide gas generated by the reaction of the above-mentioned (1) formula on the anode and the water generated by the reaction in the cathode It can be discharged from the battery smoothly; and the output voltage of the battery can be made higher and other factors, so not only for the stacked dilution cycle fuel cell, but also for the fuel and air that do not use pumps and blowers and rely on All liquid fuel cells of the so-called passive planar type fed by natural diffusion are effective.

Any electroconductive material such as various metals and carbon (carbon) materials may be used as the electroconductive material for supporting the catalyst. Among them, examples of the carbon material include furnace black, channel black, acetylene black, amorphous carbon, carbon nanotubes, carbon nanohorns, activated carbon, and graphite. These materials can be used alone or in combination. The particle size of the carbon (carbon) particles is, for example, 0.01 μm or more and 0.1 μm or less, preferably 0.02 μm or more and 0.06 μm or less. As the hydrophobic agent for hydrophobic treatment, for example, fluorocarbons, polytetrafluoroethylene, and the like can be used. As a binding agent, the water/ethanol solution (solvent is water, isopropanol, n-propanol in a weight ratio of 20:40:40) of the 5wt% polyperfluorocarbon sulfonic acid electrolyte used for covering the electrode catalyst of the present embodiment Mixed use: It is preferable from the viewpoint of adhesiveness to use as it is (manufactured by Furuka Chemical Co., Ltd.), but various other resins may also be used. In this case, it is preferable to add a hydrophobic fluororesin, especially to use a material with excellent heat resistance and acid resistance, such as polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether Copolymers and tetrafluoroethylene-hexafluoropropylene copolymers.

The method of joining the electrolyte membrane and electrodes when used as a fuel cell is not particularly limited, and known methods disclosed in Japanese Patent Application Laid-Open No. 5-182672 and Japanese Patent Application Laid-Open No. 2003-187824 can be applied. As a method of producing MEA, for example, there is a method of mixing Pt catalytic powder supported on carbon and polytetrafluoroethylene suspension, coating on carbon paper, and heat-treating to form a catalytic layer. Next, the same electrolyte solution as that of the electrolyte membrane is applied on the catalyst layer, and it is integrated with the electrolyte membrane by hot pressing. In addition, there is a method of covering the same electrolyte solution as the electrolyte membrane on the Pt catalytic powder in advance; a method of coating the catalyst slurry on one side of the electrolyte membrane; using an electroless plating method to place the electrode on the electrolyte membrane. The method; the method of reducing the platinum group metal complex ions after being adsorbed on the electrolyte membrane, etc. The solid polymer fuel cell is constructed in such a way that grooved current collectors for the fuel flow path and the oxidant flow path are formed on the outside of the assembly of the electrolyte membrane and the gas diffusion electrode formed in the above-mentioned manner. The current collector consists of arranged fuel distribution plates and oxidant distribution plates, and the product thus formed is used as a battery cell, and a plurality of such battery cells are stacked with a cooling plate in between to form the above-mentioned solid polymer fuel cell. In order to connect battery cells, in addition to stacking, planar connection methods can also be used. The method for connecting the battery cells is not particularly limited. The fuel cell, when it is made to operate at a high temperature, reduces the electrode overvoltage due to the catalyst activation of the electrode, but there is no limitation on the operating temperature. It can also vaporize liquid fuel to work at high temperature.

Next, the concentration adjustment and supply method of the aqueous methanol solution supplied to the DMFC 100 will be described. First, the concentration of the methanol aqueous solution supplied to DMFC 100 will be described. When a fluorine-based solid polymer electrolyte membrane is used, the concentration of methanol aqueous solution supplied to DMFC 100 is controlled to be 3 to 15 wt%, preferably 5 to 10 wt%. At this time, when the concentration of the aqueous methanol solution is higher than 15% by weight, the amount of methanol passing through the electrolyte membrane tends to increase, and the utilization efficiency of methanol decreases, which is not preferable. Likewise, when the concentration of the methanol aqueous solution is lower than 3 wt%, it is not preferable because the output voltage of the DMFC 100 decreases. In addition, when the aromatic hydrocarbon solid polymer electrolyte membrane is used, because the amount of methanol passing through the electrolyte membrane is small, the suitable concentration range of methanol aqueous solution in DMFC100 is 5-64wt%, preferably 20-60wt%. Next, a method for adjusting the concentration of the methanol aqueous solution will be described. In the anode catalyst layer 103, the methanol in the methanol aqueous solution is consumed according to the above-mentioned reaction formula (1), so the concentration of methanol in the methanol aqueous solution gradually decreases. Therefore, when the aqueous methanol solution discharged from the fuel flow path 110 passes through the gas-liquid separator 25 to remove the carbon dioxide gas and then returns to the DMFC 100 as it is, there is a problem that methanol is insufficient inside the battery and the electromotive force decreases rapidly.

Then, the concentration of the methanol aqueous solution is detected by the methanol concentration sensor 240 provided in the DMFC 100 and the information is sent to the control unit 30 . The control unit 30 controls the concentration of methanol in the aqueous methanol solution to be the concentration previously set in the storage unit 32 by outputting a signal from the signal processing unit 31 . That is to say, the control unit 30 outputs a signal from the signal processing unit 31 when the liquid delivery pump 23 is used to transport methanol aqueous solution or water, so as to use the solenoid valve 24 arranged on the inlet side of the liquid delivery pump 23 to connect methanol in a time-division manner. The flow path between the outlet of the aqueous solution container 22 and the inlet of the liquid-feeding pump 23 and the flow path connecting the outlet of the water container 21 and the inlet of the liquid-feeding pump 23 are switched. In addition, the water and the aqueous methanol solution may be mutually supplied only by the liquid-feeding pump 23 without using the solenoid valve 24 .

4 and 5 show a method of adjusting the concentration of the methanol aqueous solution supplied to the DMFC 100 by the control unit 30 . FIG. 4 is a flowchart showing the concentration adjustment processing routine I of the methanol aqueous solution when the solenoid valve 24 is used. FIG. 5 is a flowchart showing the concentration adjustment processing routine II of the methanol aqueous solution when the solenoid valve 24 is not used. In FIG. 4, when this processing routine I starts, the control unit 30 performs the following execution steps. That is, the methanol concentration detected by the methanol concentration sensor 240 provided on the DMFC 100 is read (step S1). Afterwards, it is judged whether the concentration of the methanol aqueous solution of the DMFC 100 is in an appropriate range based on the detection signal from the methanol concentration sensor 240 (step S2). In step S2, when it is judged that the concentration of the aqueous methanol solution of the DMFC 100 is not within the proper range, the timing (the timing stored in advance in the memory) at which the flow path of the aqueous methanol solution and the flow path of water are switched by the solenoid valve 24 is changed (step S3) and end this processing routine 1. In step S2, when it is judged that the concentration of the aqueous methanol solution of DMFC 100 is within an appropriate range, the flow returns to step S1, and the methanol concentration is read again.

In FIG. 5, when this processing routine II is started, the control unit 30 performs the following execution steps. That is, the methanol concentration detected by the methanol concentration sensor 240 provided on the DMFC 100 is read (step S11).

Afterwards, it is determined whether the concentration of the methanol aqueous solution of the DMFC 100 is in an appropriate range based on the detection signal from the methanol concentration sensor 240 (step S12 ). In step S2, when it is judged that the concentration of the aqueous methanol solution of DMFC 100 is not within the appropriate range, the time allocation timing of the liquid delivery pump 23 for supplying the aqueous methanol solution and water (the timing previously stored in the memory) is changed (step S13) to End this processing routine II. In step S12, when it is judged that the concentration of the aqueous methanol solution of DMFC 100 is within an appropriate range, the flow returns to step S11, and the methanol concentration is read again.

The concentration control carried out in this way is to use the solenoid valve 24 arranged on the inlet side of the liquid delivery pump 23 to connect the methanol aqueous solution in a time-division manner according to the timing stored in the memory in advance when utilizing the liquid delivery pump 23 to deliver methanol aqueous solution or water. The flow path between the outlet of the container 22 and the inlet of the liquid-feeding pump 23 and the flow path connecting the outlet of the water container 21 and the inlet of the liquid-feeding pump 23 are switched so that the concentration falls within the above-mentioned appropriate concentration range. There is no particular limitation on the timing at which the flow path of the aqueous methanol solution and the flow path of water are switched by the above-mentioned solenoid valve 24 . However, for the purpose of smoothly discharging carbon dioxide gas from the fuel flow path 110 in the DMFC 100 by pulsation, the timing of switching the flow path of the methanol aqueous solution and the flow path of water by the solenoid valve 24 is easily activated 100 times to 100 times per second. A timing of pulsation of 0.001, preferably 50 to 0.2, is suitable. The concentration of the methanol aqueous solution in the methanol aqueous solution container 22 is not particularly limited, but because the concentration of the methanol aqueous solution is high, the amount of methanol contained is large, and when the volume is the same, the continuous use time is prolonged, so the concentration of the methanol aqueous solution is high. The concentration of the aqueous methanol solution is generally 30 to 100 wt%, and 90 wt% or more is particularly preferred. In addition, when the time-division type pump is used as the liquid feeding pump 23, since the ratio of liquid feeding is determined by the volume of the left and right partitions, the concentration of the aqueous methanol solution in the methanol aqueous solution container 22 is determined by the volume ratio of the left and right partitions.

Next, a method of separately feeding liquid fuel (aqueous methanol) or water by using one liquid feeding pump 23 in a time-division manner will be described. This method is not particularly limited as long as it is a method in which methanol aqueous solution or water is separately transported in a time-division manner by one liquid transport pump 23 . As this specific method, there is the following method.

(1) When utilizing the liquid-feeding pump 23 to convey methanol aqueous solution or water, the flow path connecting the outlet of the methanol-water solution container 22 and the inlet of the liquid-feeding pump 23 and the flow connecting the outlet of the water container 21 and the inlet of the liquid-feeding pump 23 A method of transporting methanol aqueous solution or water in a time-division manner using the timing of switching by the solenoid valve 24 provided on the inlet side of the liquid-sending pump 23 .

(2) When a piezoelectric pump, a plunger pump, etc. having two or more volumes are used at the inlet of the pump, the methanol aqueous solution and water supplied to the inlet of the pump having two or more volumes at each timing The method of delivery in a time-division manner.

The liquid delivery pump used in the method (1) can be used without particular limitation if it is a pump that can deliver liquid fuel. As such pumps, there are: (A) turbine type pumps: (A-1) vortex pumps; centrifugal pumps such as diffusion pumps; (A-2) turbo diagonal flow pumps; diagonal flow pumps such as diagonal flow pumps; (A-3 ) axial flow pump; (B) volumetric pump: (B-1) piston pump; piezoelectric pump; plunger pump; diaphragm pump and other reciprocating pumps; (B-2) gear pump; screw pump and other rotary pumps; (C ) Special pumps: vortex gear pumps (cascade pumps); air bubble pumps (air lift liquid pumps); jet pumps, etc.

In addition, the method (2) is a method using a piezoelectric pump and a plunger pump. Piezoelectric pumps and plunger pumps, which usually suck liquid in one pump body and discharge the same liquid in the other pump body, are designed so that they can always deliver the same amount of liquid evenly. This method (2), for example, is to use a pump body inlet of a piezoelectric pump and a plunger pump to be connected to a flow path for supplying liquid fuels such as methanol aqueous solution, while the other pump body inlet is connected to a flow path for supplying water. , the water is discharged during the inhalation of methanol aqueous solution, conversely, the methanol aqueous solution is discharged during the inhalation of water. That is, it is a liquid feeding method in which the timings when methanol aqueous solution and water are fed to the DMFC 100 are respectively time-divided.

6 and 7 show the schematic structure of the piezoelectric liquid-feeding pump. Fig. 6 is a piezoelectric liquid delivery pump used in method (1), and Fig. 7 is a piezoelectric liquid delivery pump used in method (2). This piezo pump is used because it is most suitable for DMFC100, which needs to feed a small amount of liquid with a high pressure head at low power consumption. First, the principle of operation of the conventional piezoelectric liquid-feeding pump shown in FIG. 6 will be described. The backflow prevention valve 304 is a one-way valve that can only be opened in one direction. In FIG. 6, when the bimorph vibrator 301 made of polyvinylidene fluoride changes to the right position in FIG. The backflow prevention valve 304C is closed. At this time, the fluid is sucked into the left partition chamber from the fluid inlet 303 . And at this time, the backflow prevention valve 304B on the fluid inlet side on the right side is closed, the backflow prevention valve 304D on the fluid outlet side is opened, and the fluid existing in the partition chamber on the right side is sent out. Conversely, when the bimorph vibrator 301 moves to the left, the fluid existing in the partition chamber on the right is sent out from the partition chamber, and conversely, the fluid enters the partition chamber on the left. Because the bimorph vibrator 301 moves left and right with the amplitude 306 according to the frequency, the amount of liquid to be sent in one direction changes according to the frequency through this repeated operation, and the amount of liquid to be sent is large at high frequencies.

Next, the principle of operation of the piezoelectric liquid-feeding pump of this embodiment shown in FIG. 7 will be described. In FIG. 7, when the bimorph vibrator 401 made of polyvinylidene fluoride changes to the right position in FIG. into the next room on the left. On the other hand, the backflow prevention valve 402-A2 of the inlet 405 of the fluid A on the right is opened, and the fluid A existing in the partition chamber on the right is sent out. Conversely, when the bimorph vibrator 401 moves to the left, the fluid B existing on the left is sent out from the partition chamber, and the fluid A enters the partition chamber on the right. Because the bimorph vibrator 401 moves from left to right with the amplitude 403 according to the frequency, the fluid A and the fluid B are alternately fed through this repeated operation. The amount of liquid to be sent changes according to the frequency, and the amount of liquid to be sent is large at high frequencies. FIG. 8 shows the relationship between the amount of liquid delivered by the time-division type piezoelectric liquid-feeding pump and the concentration over time. A in the figure shows the supply of methanol aqueous solution, and b in the figure shows the supply of water. This FIG. 8 shows that there are pulsations and concentration gradients in the liquid sent to the DMFC 100 by the time-division type piezoelectric liquid-sending pump. In addition, by changing the left and right volumes of the partition chambers of the piezoelectric liquid-feeding pump, it is possible to change the ratio of the amount of the liquid to be fed. Specifically, FIG. 9 shows the time-dependent changes in the liquid delivery amount and concentration when the volume of the partition chamber through which water flows is set to be twice the volume of the partition chamber through which methanol aqueous solution flows. When comparing Fig. 9 with Fig. 8, the amount of water sent (b in the figure) is compared with that of Fig. 8, and Fig. 9 conveys about twice as much as Fig. 8 . Therefore, changing the volume ratio in the partition chamber is also effective in the time-division type piezoelectric liquid-feeding pump.

Hereinafter, the characteristics of the present invention will be described by way of examples and comparative examples, but the present invention is not limited thereto.

(1) Structure

<Example 1>

The structure of the fuel cell power supply of this embodiment used in Example 1 is the same as that of the fuel cell power supply shown in FIG. 2 . Here, it was specifically used in Example 1.

The solid polymer electrolyte membrane 102, anode catalyst layer 103, cathode catalyst layer 104, anode diffusion layer 105, cathode diffusion layer 106, fuel channel plate 107, and air channel plate 111 constituting the DMFC 100 will be described in detail below. As the solid polymer electrolyte membrane 102, a polyperfluorocarbon sulfonic acid membrane (trade name: Nafion 117; DuPont) was used. The anode catalyst layer 103 is made of platinum/ruthenium alloy particles that adjust the atomic ratio of platinum and ruthenium to 1/1 on a carbon carrier, with 50 wt% dispersed catalyst powder and a concentration of 5 wt% used as a binder. The water/ethanol mixed solution (solvent is water, isopropanol, n-propanol mixed with weight ratio 20:40:40 of water, isopropanol, and n-propanol: made by Flukmic) of dissolved polyperfluorocarbon sulfonic acid electrolyte , obtained by forming a porous catalyst layer with a width of 10 mm×20 mm and a thickness of about 80 μm on a polytetrafluoroethylene membrane by screen printing, and obtained by drying. At this time, the adhesion amount of the catalyst was 6 mg/cm ² . Negative catalyst layer 104 is to utilize the water/ethanol mixed solution (solvent) of dissolving the polyperfluorocarbon sulfonic acid electrolyte of the 5wt% concentration that utilizes by the catalyst powder of carrying 30wt% platinum particles on the carbon support body and utilizing as binding agent In order to mix water, isopropanol, and n-propanol at a weight ratio of 20:40:40: a slurry made by Flukemik Co., Ltd.) was formed on a polytetrafluoroethylene film with a width of 10 mm × A porous catalytic layer of 20 mm and a thickness of about 50 μm was obtained by drying. At this time, the adhesion amount of the catalyst was 3 mg/cm ² .

Next, a method of manufacturing an MEA electrode will be described. MEA electrode, utilize (1) anode catalytic layer 103 is bonded to the face of one side of solid polymer electrolyte membrane 102; Layer 104 is made. The bonding of the anode catalyst layer 103 and the solid polymer electrolyte membrane 102 is to use a water/ethanol mixed solution of 5wt% Nafion117 on the surface of the anode catalyst layer 103 (the solvent is water, Virahol, n-propanol in a weight ratio of 20 : 40: 40 mixed use: manufactured by Flukmik Co., Ltd.) After soaking with about 0.5ml, stack it on the power generation (electrode) part of the solid polymer electrolyte membrane 102, add a load of about 1kg, and heat at 80°C achieved in 3 hours. The junction of cathode catalyst layer 104 and solid polymer electrolyte membrane 102 is to use the water/ethanol mixed solution of 5wt% Nafion117 on the cathode catalyst layer 104 surface (solvent is water, isopropanol, n-propanol with weight ratio 20 : 40: 40 mixed use: Flukemik Co., Ltd.) about 0.5ml soaked, this cathode catalytic layer 104 is stacked on the opposite side of the side of the solid polymer electrolyte membrane 102 and the anode catalytic layer 103 joint side. This is achieved by adding a load of about 1 kg to the power generation (electrode) part and drying at 80°C for 3 hours.

Next, a method of manufacturing the anode diffusion layer 105 and the cathode diffusion layer 106 will be described. According to the standard weight of 40wt% of the weight of the carbon powder after firing, add a water-based dispersion of polytetrafluoroethylene particles (fluororesin dispersion D-1, manufactured by Daken (Daykin) Co., Ltd.) and mix to form a slurry The carbon mixture is coated on one side of a carbon cloth carrier with a thickness of about 350 μm and a porosity of 87%, with a thickness of about 20 μm. After drying at room temperature, it is fired at 270° C. for about 3 hours to make a carbon sheet. The produced carbon sheet was cut into a shape having the same size as the anode electrode of the above-mentioned MEA as the anode diffusion layer 105 . According to the weight of the carbon powder fired after becoming 40wt% standard, add the water-based dispersion liquid (fluorine resin dispersion D-1, made by Daken Company) of water-repellent agent polytetrafluoroethylene microparticles and mix the slurry-like mixture formed, Coated on one side of a carbon cloth carrier with a thickness of about 350 μm and a porosity of 87%, with a thickness of about 20 μm, dried at room temperature and fired at 270° C. for about 3 hours to make a carbon sheet. The obtained carbon sheet was cut into a shape having the same size as the cathode electrode of the above-mentioned MEA as the cathode diffusion layer 106 .

The anode catalyst layer 103 of the MEA formed by integrally joining the anode catalyst layer 103 on one side of the solid polymer electrolyte membrane 102 and the cathode catalyst layer 104 on the opposite side is in close contact with the anode diffusion layer 105. The cathode catalytic layer 104 is in close contact with the cathode diffusion layer 106 . The air flow channel plate 111 is arranged outside the cathode diffusion layer 106 and is provided with an air flow channel 114 having an air supply port 112 and an air discharge port 113 . Air is supplied by the blower 51 of the oxidizing gas supply unit 50 . On the other hand, the fuel flow channel plate 107 is arranged outside the anode diffusion layer 105 and is provided with a fuel flow channel 110 having a fuel supply port 108 and a fuel discharge port 109 . The concentration of the aqueous methanol solution supplied to the fuel passage plate 107 is controlled by the control unit 30 within an appropriate concentration range. This control is performed on the flow path connecting the outlet of the methanol aqueous solution container 22 and the inlet of the liquid-feeding pump 23 and the outlet of the water container 21 and the liquid-feeding valve in a time-division manner using the solenoid valve 24 provided on the inlet side of the liquid-feeding pump 23. The flow path of the inlet of the pump 23 is controlled by switching. In addition, in order to smoothly discharge the carbon dioxide gas generated on the anode due to the reaction of formula (1), the switching of the solenoid valve 24 is performed at a timing of 50 to 0.2 times per second as a timing that is prone to pulsation.

In addition, in the description of the fuel cell power source used in the following <Example 2> to <Example 14> and <Comparative Example 1>, the characteristic parts different from the fuel cell power source used in this Example 1 are given. description, and descriptions of common parts are omitted.

<Example 2>

20 g of the carbon powder used in Example 1 and 200 ml of oleum (concentration 60%) were mixed in a 300 ml flask, and kept at 60° C. for 2 days under a nitrogen stream to react. The reacted liquid changed from black to brown. Thereafter, the temperature of the flask was cooled to room temperature, and the reaction liquid was slowly added to a flask containing 600 ml of distilled water while stirring while cooling with ice, and filtered after all the reaction liquid was added. Then, the precipitate after filtration is fully washed with distilled water, and the precipitate is washed with distilled water until the washing solution becomes neutral. After that, it was washed successively with methanol and diethyl ether, and then vacuum-dried at 40° C. to obtain a derivative of carbon powder. As a result of infrared spectroscopic absorption spectrum measurement of this carbon powder, it was confirmed that there were absorptions at 1225 cm ^-1 and 1413 cm ^-1 due to -OSO ₃ H groups. In addition, absorption due to -OH group was confirmed at 1049 cm ^-1 . This indicates that -OSO ₃ H groups and -OH groups were introduced into the surface of the carbon powder treated with this oleum. The contact angle of the methanol aqueous solution of the carbon powder treated with this oleum is smaller than that of the methanol aqueous solution of the carbon powder not treated with oleum, and is hydrophilic. In addition, the electrical conductivity of the carbon powder treated with the oleum is better than that of the carbon powder not treated with the oleum. Add the carbon powder treated with this fuming sulfuric acid to the water/ethanol mixed solution of 5wt% Nafion117 (the solvent is to mix water, isopropanol, and n-propanol with a weight ratio of 20:40:40: Frew Comic Co., Ltd.) is coated on one side of the carbon cloth carrier of the anode diffusion layer 105 with a thickness of about 350 μm and a porosity of 87%, with a thickness of about 20 μm, and dried at 100° C. into carbon sheets. An experiment was conducted using a fuel cell power supply having exactly the same structure as in Example 1, except that the obtained carbon sheet was cut into the same shape as the anode electrode of the above-mentioned MEA as the anode diffusion layer 105 .

<Example 3>

The carbon cloth of about 350 μm used in Example 1 and a porosity of 87% was immersed in a flask filled with oleum (concentration 60%) and carried out the same as the carbon powder treated with oleum in Example 2. deal with. As a result, the carbon cloth treated with this oleum was excellent in hydrophilicity and conductivity by introducing -OSO ₃ H groups and -OH groups on the surface. An experiment was conducted using a fuel cell power supply having exactly the same structure as in Example 2, except that the carbon cloth treated with this oleum was used as the anode diffusion layer 105 .

<Example 4>

The polyperfluorocarbonsulfonic acid membrane of the solid polymer electrolyte membrane 102 in Example 1 was changed to a sulfomethylated polyethersulfone hydrocarbon electrolyte membrane. In addition, an experiment was conducted using a fuel cell power supply having exactly the same structure as in Example 2, except that 30 wt % of sulfomethylated polyethersulfone hydrocarbon electrolyte was used as the binder for the anode catalyst layer 103 . In this case, the anode catalyst layer 103 is fabricated as follows. First, a catalyst powder was prepared in which 50% by weight of a platinum/ruthenium alloy fine-particle catalyst in which the atomic ratio of platinum and ruthenium was 1/1 was dispersed and supported on carbon powder used as a carrier of the anode catalyst layer 103 . Afterwards, this catalyst powder and the water/ethanol mixed solution (for water, isopropanol, n-propanol are mixed with weight ratio 20:40:40 by the water/ethanol mixed solution of the sulfomethylated polyethersulfone hydrocarbon electrolyte of 30wt% Solvent), dispersant and water-repelling agent were adjusted to form a porous catalyst layer with a thickness of about 80 μm on the polytetrafluoroethylene membrane by screen printing, and this porous catalyst layer was used as the anode catalyst layer 103.

<Example 5>

Exactly the same structure as in Example 4 was used except that the concentration of the aqueous methanol solution supplied to the DMFC 100 used in Example 4 was adjusted, and only the time-division type piezoelectric liquid-feeding pump shown in FIG. 7 was used instead of the solenoid valve 24. The fuel cell power supply was tested.

<Example 6>

In addition to changing the left and right volumes of the partition chambers of the time-division type piezoelectric liquid-feeding pump used in Example 5, the volume of the partition chamber through which the water flows is twice the volume of the partition chamber through which the methanol aqueous solution flows. Experiments were carried out using a fuel cell power supply having exactly the same structure as in Example 5, except for the time-division piezoelectric liquid-feeding pump.

<Example 7>

Except that the thickness of the anode catalyst layer 103 was increased from 80 μm to 150 μm, and the thickness of the cathode catalyst layer 104 was decreased from 50 μm to 25 μm, experiments were carried out using a fuel cell power supply with exactly the same structure as in Example 5.

<Embodiment 8>

Except that the hydrophilic carbon powder obtained by treating the carbon powder used in Example 1 with the same fuming sulfuric acid as in Example 2 was used for the anode diffusion layer 105, the same structure as in Example 7 was used. The fuel cell power supply was tested.

<Example 9>

Except that the carbon cloth used in Example 3 was treated with the same fuming sulfuric acid as in Example 3 and the obtained hydrophilic carbon cloth was used in the anode diffusion layer 105, a carbon cloth with exactly the same structure as in Example 8 was used. A fuel cell power supply was experimented with.

<Example 10>

An experiment was carried out using a fuel cell power source having exactly the same structure as in Example 8, except that carbon paper was used instead of the carbon cloth used as the carrier of the anode diffusion layer 105 .

<Example 11>

The cathode catalyst layer 104 used in Example 7 was produced in the following manner. First, a catalyst powder was prepared in which 50% by weight of a platinum/ruthenium alloy fine-particle catalyst having an atomic ratio of platinum and ruthenium of 1/1 was carried on carbon powder used as a carrier of the cathode catalyst layer 104 . Afterwards, this catalyst powder and the water/ethanol mixed solution (for water, isopropanol, n-propanol are mixed with weight ratio 20:40:40 by the water/ethanol mixed solution of the sulfomethylated polyethersulfone hydrocarbon electrolyte of 30wt% solvent) and a dispersant and a hydrophobic agent to adjust the slurry, and form a porous catalytic layer with a thickness of about 25 μm on the polytetrafluoroethylene membrane by means of screen printing. This porous catalyst layer was used as the cathode catalyst layer 104 . In addition, carbon paper carrying carbon is used for the cathode diffusion layer 106 . An experiment was carried out using a fuel cell power supply with exactly the same structure as in Example 10 except that the cathode catalyst layer 104 and the cathode diffusion layer 106 were changed.

<Example 12>

Except changing the thickness of the anode catalyst layer 103 from 150 μm to 200 μm, and the thickness of the cathode catalyst layer 104 from 25 μm to 15 μm, experiments were carried out using a fuel cell power supply with exactly the same structure as in Example 11.

<Example 13>

Except that the thickness of the anode catalyst layer 103 was changed from 200 μm to 100 μm, the thickness of the cathode catalyst layer 104 was changed from 15 μm to 10 μm and the carbon powder used in Example 1 was treated with the same oleum as in Example 2 Except that the obtained hydrophilic carbon powder was used as a carrier of the anode catalyst layer 103, an experiment was carried out using a fuel cell power source having exactly the same structure as in Example 12.

<Example 14>

Except changing the thickness of the anode catalyst layer 103 from 100 μm to 50 μm and the thickness of the cathode catalyst layer 104 from 10 μm to 5 μm, experiments were carried out using a fuel cell power supply with exactly the same structure as in Example 13.

<Comparative example 1>

The structure of the fuel cell power source used in Comparative Example 1 is shown in FIG. 17 . The structure of the fuel cell power supply used in Comparative Example 1 is completely the same as that of the fuel cell power supply in Example 1 except that the structure of the liquid fuel supply unit 20 is different. That is to say, in the structure of the liquid fuel supply part 20, the fuel cell power supply used in Comparative Example 1, compared with Embodiment 1, only the water supply pump 210, the high-concentration methanol aqueous solution supply pump 220, and the concentration adjustment of the methanol aqueous solution are also used. The container 230, the methanol concentration sensor 240, and the DMFC supply pump 250 are different. As the pump used in Comparative Example 1, the piezoelectric pump shown in FIG. 6 was used. The method of adjusting the concentration of the methanol aqueous solution supplied to the fuel flow path plate 107 of the DMFC 100 is based on the detection concentration of the methanol concentration sensor 240, using the water supply pump 210 and the high-concentration methanol aqueous solution supply pump directly connected to the water container 21 and the methanol aqueous solution container 22 respectively. 220 is a method of controlling the supply amount of the methanol aqueous solution concentration adjustment container 230 .

(2) Experimental method

The fuel cell power sources used in <Example 15> to <Example 28> and <Comparative Example 2> were tested and evaluated under the following conditions. First, the aqueous methanol solution supplied to the anode was supplied at a flow rate of 0.2 ml/min so as to maintain a concentration of 2M. The air supplied to the cathode was supplied at a flow rate of 500 ml/min. Secondly, the evaluation of the above-mentioned fuel cell power supply is based on (i) voltage-current characteristics (the set temperature of DMFC is 70°C); (ii) continuous output characteristics (the set temperature of DMFC is 70°C, and the set current density is 100 mA/cm ² ).

(3) Results

The results of the characteristic evaluations of (i) and (ii) above are shown below in order from <Example 1> to <Example 14> and <Comparative Example 1>.

(Example 1)

The results of voltage-current characteristics of DMFC are shown in FIG. 10 . As shown in Figure 10, the output voltage of the DMFC at a current density of 100 mA/cm ² is 450 mV. FIG. 11 shows the change in output voltage with time at the time of continuous power generation at a current density of 100 mA/cm ² . According to Fig. 11, the output voltage of this DMFC remained constant even after 5 hours of continuous operation, and the output voltage did not drop even once.

In addition, from <Example 2> to <Example 14>, because the result of the voltage-current characteristics of DMFC and the state of the output voltage change with time at the time of continuous power generation at a current density of 100mA/ ^cm2 are different from < Figure 10 and Figure 11 of Example 1> show almost the same state, so these diagrams are omitted from <Example 2> to <Example 14> and are respectively shown at a current density of 100 mA/cm ² The output voltage of DMFC and the time it can continuously generate electricity at a current density of 100mA/ ^cm2 .

(Example 2)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 470mV. The time for continuous power generation at a current density of 100mA/cm ² is 8 hours, during which the output voltage remains constant and the output voltage does not drop once.

(Example 3)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC is 480mV at the current density of 100mA/cm ² . The time for continuous power generation at a current density of 100mA/cm ² is 8 hours, during which the output voltage remains constant and the output voltage does not drop once.

(Example 4)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC is 480mV at the current density of 100mA/cm ² . The time for continuous power generation at a current density of 100mA/cm ² is 16 hours, during which the output voltage remains constant and the output voltage does not drop once.

(Example 5)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC is 480mV at the current density of 100mA/cm ² . The time for continuous power generation at a current density of 100mA/cm ² is 16 hours, during which the output voltage remains constant and the output voltage does not drop once.

(Example 6)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC is 480mV at the current density of 100mA/cm ² . The time for continuous power generation at a current density of 100mA/cm ² is 16 hours, during which the output voltage remains constant and the output voltage does not drop once.

(Example 7)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 530mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(Embodiment 8)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 550mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(Example 9)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 570mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(Example 10)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 570mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(Example 11)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 580mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(Example 12)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 620mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(Example 13)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 640mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(Example 14)

According to the voltage-current characteristics of DMFC, the output voltage of DMFC at the current density of 100mA/cm ² is 650mV. The time for continuous power generation at a current density of 100mA/cm ² was 14.4 hours, during which the output voltage remained constant and the output voltage did not drop once.

(comparative example 1)

The results of voltage-current characteristics of DMFC are shown in FIG. 12 . As shown in the figure, the output voltage of the DMFC at a current density of 100 mA/cm ² is 450 mV. FIG. 13 shows the change with time of the output voltage at the time of continuous power generation for 5 hours at a current density of 100 mA/cm 2 . According to FIG. 13 , the output voltage of the DMFC has a problem that the output voltage temporarily drops due to the carbon dioxide gas generated 36 minutes and 63 minutes after the start of the operation of the power supply, which makes the supply of the fuel methanol aqueous solution to the anode unstable. In addition, after 300 minutes, large bubbles of carbon dioxide gas were generated to hinder the supply of methanol fuel, resulting in a significant drop in output voltage. Here, for the results obtained from Example 1 to Example 14 and Comparative Example 1, Table 1 summarizes (i) the output voltage of the DMFC at a current density of 100mA/cm ² ; (ii ) The time for continuous power generation at a current density of 100mA/cm ² .

<table 1>

Table 1 Output voltage (mV) Can it run continuously for 5 hours? Continuous running time (hr) Example 15 450 yes 5 Example 16 470 yes 8 Example 17 480 yes ↑ Example 18 480 yes 16 Example 19 480 yes ↑ Example 20 480 yes ↑ Example 21 530 yes 14.4 Example 22 550 yes ↑ Example 23 570 yes ↑ Example 24 570 yes ↑ Example 25 580 yes ↑ Example 26 620 yes ↑ Example 27 640 yes ↑ Example 28 650 yes ↑ Comparative example 2 450 no 5 or less

Note: The output voltage is the value when the current density is 100mA/cm ² .

From the results in Table 1 and FIGS. 10 to 13 , the following effects shown in the above-mentioned Examples 1 to 14 can be obtained, respectively.

In Example 1, when comparing the results of the voltage-current characteristics of the DMFC of Example 1 shown in FIG. 10 with the results of the voltage-current characteristics of the DMFC of Comparative Example 1 shown in FIG. The voltage-current characteristics are approximately the same, and the output voltages are both 450mV at a current density of 100mA/cm ² .

Next, when comparing the relationship between the time of continuous power generation and the output voltage of the DMFC of Example 1 shown in Figure 11 and the relationship between the time of continuous power generation and the output voltage of the fuel cell power supply of Comparative Example 1 shown in Figure 13, the implementation In Example 1, the output voltage was stable during 5 hours of continuous power generation, and the output voltage did not drop even once. On the other hand, in Comparative Example 1, the output voltage was not stable during 5 hours of continuous power generation, and the output voltage decreased. Its reason is because when embodiment 1 supplies methanol aqueous solution to DMFC, gives pulsation, so the carbon dioxide gas that produces on the anode can be removed from DMFC smoothly, on the other hand, because comparative example 1 supplies methanol aqueous solution to DMFC When the pulsation is not given, the carbon dioxide gas generated on the anode cannot be smoothly removed from the DMFC. As mentioned above, as a result of comparing Example 1 and Comparative Example 1, the fuel cell power supply of Example 1 can be used in Comparative Example 1 by sending methanol aqueous solution and water in a time-division manner by using a solenoid valve. One less pump for three delivery pumps, so space and weight can be saved. In addition, because the fuel cell power supply of Example 1 can smoothly remove the carbon dioxide gas generated on the anode from the DMFC by giving pulsation when the methanol aqueous solution is supplied to the DMFC, it can continuously generate electricity with a stable output voltage (450mV).

When the voltage-current characteristic result of the DMFC of embodiment 2 is compared with the voltage-current characteristic result of the DMFC of embodiment 1, the output voltage of the DMFC of the 100mA/cm current density of embodiment ² is 470mV, this The output voltage was about 20 mV higher than that of Example 1. Secondly, when comparing the relationship between the time and output voltage of the DMFC of Example 2 when it continuously generates power and the relationship between the time and output voltage of the fuel cell power supply of Example 1, the fuel cell power supply of Example 2 can be stabilized The continuous power generation time of the output voltage (470mV) is 8 hours, which is about 3 hours longer than the 5 hours of continuous power generation in Example 1. As mentioned above, the results of comparing Example 1 and Comparative Example 1, Example 2, in addition to the effect obtained by Example 1 on Comparative Example 1, the output voltage of the DMFC with a current density of 100mA/cm ² is the same as that of Example 2. 1 is about 20mV higher than that of Example 1, and the time for continuous power generation at a stable output voltage is about 3 hours longer than that of Example 1. This effect should be caused by the hydrophilic treatment of the carbon powder in the anode diffusion layer. That is to say, because through this hydrophilization treatment, the anode diffusion layer becomes easy to be wetted by methanol aqueous solution, and a larger amount of methanol aqueous solution can successfully penetrate the anode catalytic layer 103, so the reaction can be further carried out and the output voltage becomes lower. bigger. And, because the bubbles of carbon dioxide gas generated on the anode do not grow into large bubbles in the anode diffusion layer 105 by this hydrophilic treatment, but leave the anode diffusion layer 105 in a minute state without change, so The methanol aqueous solution can be smoothly supplied to the anode, and continuous power generation can be performed at a stable voltage for a long time.

When comparing the voltage-current characteristic result of the DMFC of embodiment 3 and the voltage-current characteristic result of the DMFC of embodiment ² , the output voltage of the DMFC of the 100mA/cm current density of embodiment 3 is 480mV, this The output voltage was about 10 mV higher than that of Example 2. Next, the relationship between the time and the output voltage during continuous power generation by the DMFC in Example 3 is the same as the relationship between the time and output voltage in the continuous power generation of the fuel cell power supply in Example 2. As mentioned above, the result of comparing Example 3 with Example 2, Example 3, in addition to the effect obtained by Example 2 on Example 1, the output voltage of the DMFC with a current density of 100mA/cm ² is the same as that of Example 2. 2 about 10mV higher than that. This effect should be due to the hydrophilization treatment of the carbon cloth of the anode diffusion layer used in Example 2 in Example 3. That is to say, because through this hydrophilization treatment, the anode diffusion layer becomes easy to be wetted by methanol aqueous solution, and a larger amount of methanol aqueous solution can successfully penetrate the anode catalytic layer 103, so the reaction can be further carried out and the output voltage becomes lower. bigger. And, because the bubbles of carbon dioxide gas generated on the anode do not grow into large bubbles in the anode diffusion layer 105 by this hydrophilization treatment, but leave the anode diffusion layer 105 in a minute state without change. The methanol aqueous solution can be smoothly supplied to the anode, and continuous power generation can be performed at a stable voltage for a long time.

When the voltage-current characteristic result of the DMFC of embodiment 4 is compared with the voltage-current characteristic result of the DMFC of embodiment 1, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 4 is 480mV, this The output voltage was about 30 mV higher than that of Example 1. The difference between Example 4 and Example 1 is that Example 4 uses a hydrocarbon-based electrolyte as the electrolyte membrane and adhesive, whereas Example 1 uses a fluorine-based electrolyte membrane as the electrolyte membrane and adhesive. This is because the ionic conductivity of the hydrocarbon-based electrolyte used in Example 4 is greater than that of the fluorine-based electrolyte used in Example 3, that is, the internal resistance of DMFC is smaller. When comparing the relationship between the time and output voltage of the DMFC of embodiment 4 when it continuously generates power and the relationship between the time and output voltage of the fuel cell power supply of embodiment 1 when it continuously generates electricity, the fuel cell power supply of embodiment 4 can have a stable output The time for continuous power generation by voltage is 16 hours, which is more than twice the continuous power generation time of Example 1 of 5 hours.

Secondly, when comparing the relationship between the time and output voltage of the DMFC of Example 4 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Example 1 when it continuously generates electricity, the fuel cell power supply of Example 4 can be stabilized The continuous power generation time of the output voltage is 16 hours, and this time is more than twice the time length of the continuous power generation time of embodiment 1. As mentioned above, the result of comparison between Example 4 and Example 1 shows that the time that Example 4 can continuously generate electricity with a stable output voltage is more than twice the time length of Example 1 that can continuously generate electricity. This effect is due to changing the binder of the solid polymer electrolyte membrane and the anode to a hydrocarbon-based electrolyte membrane. Compared with the fluorine-based electrolyte membrane used in Example 1, this hydrocarbon-based electrolyte membrane passes through (crossover ) has less methanol. Since less methanol passes through the solid polymer electrolyte membrane, the concentration of methanol in the methanol aqueous solution changes little, which contributes to increased stability of the fuel cell and improved fuel utilization efficiency.

When the voltage-current characteristic result of the DMFC of embodiment 5 is compared with the voltage-current characteristic result of the DMFC of embodiment 4, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 5 is 480mV, this The output voltage is the same as that of Example 4. When comparing the relationship between the time of continuous power generation and the output voltage of the DMFC of Embodiment 5 and the relationship between the time and output voltage of the fuel cell power source of Embodiment 4, the continuous power generation of the fuel cell power source of Embodiment 5 Time is identical with embodiment 4. As mentioned above, as a result of comparison between Example 5 and Example 4, in Example 5, the concentration adjustment of the aqueous methanol solution supplied to the DMFC does not use a solenoid valve but only uses a time-divided piezoelectric liquid-feeding pump to obtain the same result as in Example 5. 4 to the same effect.

When the voltage-current characteristic result of the DMFC of embodiment 6 is compared with the voltage-current characteristic result of the DMFC of embodiment 5, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 6 is 480mV, this The output voltage is the same as that of Example 5.

Secondly, when comparing the relationship between the time and output voltage of the DMFC of embodiment 6 when it continuously generates power and the relationship between the time and output voltage of the fuel cell power source of embodiment 5, the fuel cell power source of embodiment 6 can be continuously The time of power generation is the same as in Example 5. As mentioned above, the result of comparison between Example 6 and Example 5, Example 6, does not use a solenoid valve in the concentration adjustment of the methanol aqueous solution supplied to the DMFC, but only changes the left and right of the partition chamber of the time-division type piezoelectric liquid-feeding pump. The volume of liquid delivery can also be obtained with

Embodiment 5 has the same effect.

When the result of the voltage-current characteristic of the DMFC of embodiment 7 is compared with the result of the voltage-current characteristic of the DMFC of embodiment 5, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 7 is 530mV, This output voltage is about 50 mV higher than that of Example 5.

Secondly, when comparing the relationship between the time and the output voltage of the DMFC of Example 7 when it continuously generates electricity and the relationship between the time and the output voltage of the fuel cell power supply of Example 5, the fuel cell power supply of Example 7 can be stabilized The continuous power generation time of the output voltage is 14.4 hours, which is shorter than the continuous power generation time of Embodiment 5. As mentioned above, the result of comparing the difference between Example 7 and Example 5, Example 7, in addition to the effect obtained by Example 5 on Examples 1 to 4, the output voltage of the DMFC with a current density of 100mA/cm ² is the same as Compared with Example 5, it is about 50 mV higher, and the time for continuous power generation at a stable output voltage is slightly shorter than that of Example 5. This effect increases the thickness of the anode catalytic layer 103 from 80 μm to 150 μm and reduces the thickness of the cathode catalytic layer 104 from 50 μm to 25 μm. Because by increasing the thickness of the anode catalytic layer 103, the contact area between the methanol aqueous solution and the anode catalyst increases, and the reaction between the methanol aqueous solution and water in the anode catalytic layer 103 can proceed further, which can help improve fuel utilization efficiency. In addition, the reason why the thickness of the cathode catalytic layer 104 is thinned to effectively use air, that is, oxygen, and the DMFC is not thick, is that the cost of catalysts such as platinum is high, and it should be reduced as much as possible without reducing the output of the fuel cell. The amount of cathode catalyst can reduce the total amount of platinum used, which can reduce the overall cost. In particular, reducing the thickness of the cathode can effectively use oxygen, which is effective for improving battery performance.

When the voltage-current characteristic result of the DMFC of embodiment 8 is compared with the voltage-current characteristic result of the DMFC of embodiment 7, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 8 is 550mV, this The output voltage was about 20 mV higher than that of Example 7. Secondly, when comparing the relationship between the time and output voltage of the DMFC of Embodiment 8 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Embodiment 8 when it continuously generates electricity, the fuel cell power supply of Embodiment 7 can generate electricity continuously The time is the same as in Example 7. As mentioned above, the result of embodiment 8 and embodiment 7 comparison, embodiment 8, except the effect that embodiment 7 obtains to embodiment 5, the output voltage of the DMFC of the current density of 100mA/cm ² is similar to embodiment 7. 20mV higher than approx. This output voltage becomes larger because the carbon powder of the anode diffusion layer is hydrophilized, that is, because the anode diffusion layer becomes susceptible to The wetting of the aqueous methanol solution allows a larger amount of the aqueous methanol solution to successfully penetrate the anode catalyst layer 103 . Therefore, the reaction of methanol and water in the anode catalyst layer 103 further proceeds, and the output voltage becomes larger.

When the voltage-current characteristic result of the DMFC of embodiment 9 is compared with the voltage-current characteristic result of the DMFC of embodiment 8, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 9 is 570mV, this The output voltage was about 20 mV higher than that of Example 8. Secondly, when comparing the relationship between the time and output voltage of the DMFC of Embodiment 9 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Embodiment 8 when it continuously generates electricity, the fuel cell power supply of Embodiment 9 can generate electricity continuously The time is the same as in Example 8. As mentioned above, the result of embodiment 9 and embodiment 8 comparison, embodiment 9, except the effect that embodiment 8 obtains to embodiment 7, the output voltage of the DMFC of the current density of 100mA/cm ² is similar to embodiment 8. 20mV higher than approx. The effect of making the output voltage higher should be to carry out hydrophilic treatment on the carbon cloth carrier of the anode diffusion layer 105, so that the anode diffusion layer becomes easy to be wetted by methanol aqueous solution, and a larger amount of methanol aqueous solution can be further improved. Smoothly penetrate the anode catalyst layer.

When the voltage-current characteristic result of the DMFC of embodiment 10 is compared with the voltage-current characteristic result of the DMFC of embodiment 8, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 10 is 570mV, this The output voltage was about 20 mV higher than that of Example 8.

Secondly, when comparing the relationship between the time and output voltage of the DMFC of Example 10 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Example 8, the fuel cell power supply of Example 10 can generate electricity continuously The time is the same as in Example 8. As mentioned above, as a result of comparing Example 10 with Example 8, due to the effect of changing the anode diffusion layer from carbon cloth to carbon paper, the output voltage can be further improved. This shows that, as an anode diffusion layer, carbon paper is more effective than carbon cloth.

When comparing the voltage-current characteristic result of the DMFC of embodiment 11 and the voltage-current characteristic result of the DMFC of embodiment 10, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 10 is 580mV, this The output voltage was about 10 mV higher than that of Example 10. Secondly, when comparing the relationship between the time and output voltage of the DMFC of Example 11 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Example 10 when it continuously generates electricity, the fuel cell power supply of Example 11 can generate electricity continuously The time is the same as in Example 10.

As mentioned above, the result of embodiment 11 and embodiment 10 comparison, embodiment 11, except the effect that embodiment 10 obtains to embodiment 9, the output voltage of the DMFC of the current density of 100mA/cm ² is similar to embodiment 10. 10mV higher than approx. This effect of increasing the output voltage is due to the fact that the binder of the cathode catalyst layer was changed from a fluorine-based electrolyte to a hydrocarbon-based electrolyte, further improving ion conductivity, reducing internal resistance, and increasing output voltage.

When the result of the voltage-current characteristic of the DMFC of embodiment 12 is compared with the result of the voltage-current characteristic of the DMFC of embodiment 11, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 12 is 620mV, this The output voltage was about 50 mV higher than that of Example 11. Secondly, when comparing the relationship between the time and output voltage of the DMFC of Example 12 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Example 11 when it continuously generates electricity, the fuel cell power supply of Example 12 can be stabilized The time of continuous power generation of the output voltage is the same as that of embodiment 11. As mentioned above, the result of embodiment 12 and embodiment 11 comparison, embodiment 12, except the effect that embodiment 11 obtains to embodiment 10, the output voltage of the DMFC of the current density of 100mA/cm ² is similar to embodiment 11. 40mV higher than approximately. For this effect, by increasing the thickness of the anode catalyst layer 103 from 150 μm to 200 μm, the contact area between the methanol solution and the anode catalyst is further increased, and the reaction between the methanol solution and water in the anode catalyst layer 103 can be further carried out, so the output voltage increased. In addition, the thickness of the cathode catalytic layer 104 is reduced from 25 μm to 15 μm, and the increase in the utilization efficiency of oxygen also contributes to the improvement of the output voltage.

When the result of the voltage-current characteristic of the DMFC of embodiment 13 is compared with the result of the voltage-current characteristic of the DMFC of embodiment 11, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 13 is 640mV, this The output voltage was about 60 mV higher than that of Example 11.

Secondly, when comparing the relationship between the time and output voltage of the DMFC of Example 13 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Example 11 when it continuously generates electricity, the fuel cell power supply of Example 13 can generate electricity continuously The time is the same as in Example 11. As mentioned above, the result of embodiment 13 and embodiment 11 comparison, embodiment 13, except the effect that embodiment 11 obtains to embodiment 10, the output voltage of the DMFC of the current density of 100mA/cm ² is similar to embodiment 11. 60mV higher than approximately. This effect reduces the thickness of the anode catalyst layer 103 from 150 μm to 100 μm, although the contact area between the methanol aqueous solution and the anode catalyst decreases, because the carbon of the anode diffusion layer 103 is hydrophilized to make the methanol aqueous solution and the anode catalyst hydrophilized. The contact chance of the anode catalyst increases, and by reducing the thickness of the cathode catalyst layer 104 from 25 μm to 10 μm, oxygen can diffuse into the cathode, which can improve the utilization efficiency of oxygen and increase the output voltage.

When the result of the voltage-current characteristic of the DMFC of embodiment 14 is compared with the result of the voltage-current characteristic of the DMFC of embodiment 13, the output voltage of the DMFC of the 100mA/ ^cm current density of embodiment 14 is 650mV, this The output voltage was about 10 mV higher than that of Example 13. Secondly, when comparing the relationship between the time and output voltage of the DMFC of Example 14 when it continuously generates electricity and the relationship between the time and output voltage of the fuel cell power supply of Example 13 when it continuously generates electricity, the fuel cell power supply of Example 14 can generate electricity continuously The time is the same as in Example 13. As mentioned above, as a result of the comparison between Example 14 and Example 13, in Example 14, the effect obtained in Example 13 on Example 12 becomes larger, and the output voltage of the DMFC with a current density of 100mA/cm ² is similar to that of Example 13. than about 10mV higher. In particular, reducing the thickness of the cathode catalyst layer 104 is effective in improving the utilization efficiency of oxygen and increasing the output voltage.

(3) Application example

<Application example 1>

FIG. 14 shows a schematic configuration of a fuel cell power supply of a notebook personal computer using a fuel cell power supply and a storage container for a high-concentration methanol aqueous solution. The fuel cell power supply 501 of this notebook type personal computer 500 uses the fuel cell power supply shown in the twelfth embodiment. In addition, as the storage container for the high-concentration methanol aqueous solution, a cartridge-type fuel cartridge 502 that can replace the container of the high-concentration methanol aqueous solution that becomes empty after use with a full one is used. This notebook personal computer 500 can be used continuously for 8 hours at an average output of 12W.

<Application example 2>

15 and 16 show a PDA (an abbreviation for Personal Digital Assistant, also called a portable information terminal) using a fuel cell power source. Fig. 16 shows a photograph of the appearance of this PDA (portable information terminal).

FIG. 16 shows a schematic structure of a fuel cell power supply of this PDA (portable information terminal) 600 and a storage container for a high-concentration methanol aqueous solution. As the fuel cell power source 601, the fuel cell power source shown in the thirteenth embodiment is used. In addition, as the storage container of the high-concentration methanol aqueous solution, a cartridge-type fuel cartridge 602 that can replace the container of the high-concentration methanol aqueous solution that becomes empty after use with a full container is used. This PDA (portable information terminal) 600 can be used continuously for 8 hours. In addition, a mobile phone (not shown) using the fuel cell power source of the thirteenth embodiment can operate continuously for 50 hours. At this time, when the output of the fuel cell decreases, the vibration function attached to the method mode of the mobile phone can be used to vibrate the mobile phone to increase the output of the fuel cell again, and the output will also be stabilized. This is because the carbon dioxide gas generated on the anode does not grow into large bubbles due to the vibration, but can be discharged as tiny bubbles as it is, so that the fuel in the anode can be supplied uniformly.

Fuel cells using liquid fuels have the following problems (1) to (5).

(1) In a conventional fuel cell that circulates liquid fuel, since a concentration control structure that detects the concentration of liquid fuel and maintains a predetermined concentration is used, it is necessary to have multiple pumps for delivering high-concentration liquid fuel and pumps for delivering water. Pump. The use of such a plurality of pumps increases the space occupied by auxiliary machines such as pumps in the fuel cell power supply, resulting in an increase in the size of the fuel cell power supply itself.

(2) When the carbon dioxide gas generated on the anode cannot be smoothly discharged from the anode by the reaction of the above chemical formula (1), the output of the battery will be unstable or reduced because a sufficient amount of liquid fuel such as methanol cannot be supplied to the anode.

(3) Since the liquid fuel such as methanol supplied to the anode cannot sufficiently penetrate into the cathode diffusion layer, the output and fuel utilization efficiency are lowered.

(4) Since the liquid fuel such as methanol supplied to the anode cannot react smoothly with the anode, the output and the utilization rate of the fuel are lowered.

(5) Since the oxygen supplied to the cathode cannot reach the inside of the cathode catalyst layer, the oxidation of protons does not occur, and the output and fuel utilization efficiency decrease.

The above (2)-(5) are common problems not only for the dilution cycle type laminated fuel cell power source but also for the naturally exhaling plate (planar) type fuel cell power source.

The effects of this embodiment obtained from Examples 1 to 14 and Application Examples 1 to 2 can be summarized as follows:

(1) Since there is no need to install a plurality of pumps required to maintain the concentration of liquid fuels such as methanol at a predetermined concentration, it is possible to provide a fuel cell power supply and its operating method that can realize compactness and light weight, and a portable electronic device using a fuel cell power supply .

(2) In addition, since the carbon dioxide gas in the anode can be smoothly discharged and liquid fuel such as methanol can be uniformly supplied to the anode, a fuel cell power supply capable of increasing output, an operating method thereof, and a portable electronic device using a fuel cell power supply can be provided.

(3) In addition, since the liquid fuel such as methanol supplied to the anode can sufficiently penetrate into the anode diffusion layer, it is possible to provide a fuel cell power supply that can increase the output and fuel utilization efficiency of a portable electronic device using the fuel cell power supply. A fuel cell power supply, method of operating the same, and a portable electronic device using the fuel cell power supply.

(4) In addition, since the amount of catalyst for the reaction of methanol and water is increased by thickening the anode catalyst layer, it is possible to provide a fuel cell power supply and a fuel cell power supply capable of promoting the reaction of liquid fuels such as methanol to increase output and fuel utilization efficiency. Its method of operation and a portable electronic device using fuel cell power.

(5) In addition, by making the cathode catalyst layer thinner, oxygen can be sufficiently diffused all the way to the cathode catalyst layer so that oxygen can be effectively utilized, so it is possible to provide a fuel cell power supply capable of increasing output and its operating method and the use of a fuel cell Power supply for portable electronic devices.

(6) In addition, because the carbon dioxide gas generated by the reaction of the fuel cell can be smoothly discharged forever, it is possible to provide a fuel cell power supply and its operating method that can be used continuously for a long time, and a portable electronic device using the fuel cell power supply.

(7) Since the fuel cell power supply and its operation method of this embodiment and the portable electronic device using the fuel cell power supply can be used continuously for a long time, portable telephones, portable personal computers, portable audio and video The attached charger and the secondary battery in the machine and other portable information terminals no longer need to be loaded, and the original built-in power supply can be used.

An object of the present embodiment is to provide a fuel cell power supply that can be reduced in size and weight without requiring a plurality of pumps, an operating method thereof, and a portable electronic device using the fuel cell power supply. Another object of the present embodiment is to provide a fuel cell power supply, an operating method thereof, and a portable electronic device using the fuel cell power supply, which can smoothly discharge carbon dioxide gas generated by the reaction from the anode to increase output.

In addition, another object of this embodiment is to provide a fuel cell power supply, an operating method thereof, and a fuel cell power supply using a fuel cell power supply that can sufficiently infiltrate liquid fuel such as methanol supplied to the battery into the anode diffusion layer to increase output and fuel utilization efficiency. Portable Electronic Devices.

In addition, another object of this embodiment is to provide a fuel cell power supply capable of promoting the reaction of liquid fuel such as methanol supplied to the anode to increase output and fuel utilization efficiency, an operating method thereof, and a portable electronic device using the fuel cell power supply. device.

In addition, another object of this embodiment is to provide a fuel cell power supply that can be used continuously for a long time with a stable output and an operating method thereof, as well as a portable battery using the fuel cell power supply, which can smoothly discharge carbon dioxide gas generated by the reaction of the fuel cell. electronic device. The carbon dioxide gas produced by the reaction of the fuel cell can be smoothly discharged, and it can be used continuously for a long time with a stable output. In addition, liquid fuel such as methanol supplied to the battery can be sufficiently infiltrated into the anode diffusion layer to increase output and fuel utilization efficiency. In addition, the reaction of liquid fuel such as methanol supplied to the anode can be promoted to increase the output and fuel utilization efficiency.

Claims (13)

1. A fuel cell power plant comprising: a fuel cell unit having an anode, a cathode disposed to face the anode, and a solid polymer electrolyte membrane interposed between the anode and the cathode; and a liquid fuel supply unit that supplies liquid fuel and water to the anode, characterized in that:

the liquid fuel supply unit is a unit configured to supply the liquid fuel and the water to the anode in a time-division manner by one pump.

2. The fuel cell power plant as defined in claim 1, wherein: the liquid fuel supply unit supplies the liquid fuel and water to the anode in a time-division manner by one pump using an electromagnetic valve.

3. The fuel cell power plant as defined in claim 1, wherein: the liquid fuel supply unit is a unit configured to supply the liquid fuel and the water to the anode in a time-division manner by one pump using a piezoelectric pump.

4. The fuel cell powerplant as defined in claim 1, wherein: the liquid fuel supply unit is a unit configured to supply the liquid fuel and the water to the anode in a time-division manner by one pump using a plunger pump.

5. The fuel cell power plant as defined in claim 1, wherein:

an anode having an anode catalyst layer on a surface thereof which is in contact with the solid polymer electrolyte membrane, an anode diffusion layer on a surface thereof which is not in contact with the solid polymer electrolyte membrane, and a liquid fuel flow path plate outside the anode diffusion layer;

a cathode having a cathode catalyst layer on a surface of the cathode catalyst layer which is in contact with the solid polymer electrolyte membrane, a cathode diffusion layer on a surface of the cathode catalyst layer which is not in contact with the solid polymer electrolyte membrane, and an oxidant gas flow field plate outside the cathode diffusion layer;

the anode diffusion layer is subjected to hydrophilization treatment.

6. The fuel cell power plant as defined in claim 1, wherein:

the carbon support used for the anode catalyst layer is subjected to hydrophilization treatment.

7. The fuel cell power plant as defined in claim 1, wherein:

the solid polymer electrolyte membrane is an aromatic hydrocarbon electrolyte membrane into which an alkylene sulfonic acid group is introduced; the binder used for the anode catalyst layer is an aromatic hydrocarbon electrolyte into which an alkylene sulfonate group is introduced.

8. The fuel cell power plant as defined in claim 5, wherein:

the thickness of the anode catalyst layer is larger than that of the cathode catalyst layer.

9. The fuel cell power plant as defined in claim 5, wherein:

the binder used for the cathode catalyst layer is an aromatic hydrocarbon electrolyte into which an alkylene sulfonate group is introduced.

10. A portable electronic device, characterized in that: a fuel cell power plant as claimed in claim 1 is used in a mobile device.

11. The portable electronic device of claim 10, wherein: the portable electronic device is a notebook personal computer.

12. The portable electronic device of claim 10, wherein: the portable electronic device is a portable information terminal.

13. The portable electronic device of claim 10, wherein: the portable electronic device is a portable telephone.

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