JP2006032040A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell with a structure which can discharge carbon dioxide generated by electrochemical reaction effectively and can collect, discharge, or circulate water generated by the electrochemical reaction effectively. <P>SOLUTION: In the fuel cell, a power generating section 1, which is equipped with a cathode electrode 3, an anode electrode 5, an electrolyte membrane for insulating the cathode electrode 3 and the anode electrode 5, a hollow support body 2 for supporting the cathode electrode, the anode electrode 5, and the electrolyte membrane 4, and an oxygen supply means for supplying oxygen to the inside of the hollow support body 2, is immersed into a methanol water solution, and the oxygen and the cathode electrode 3 are in contact at the inside of the power generation section 1 and the methanol water solution and the anode electrode 5 are in contact at the outside of the power generation section 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell, and more particularly to a fuel cell that generates electricity by supplying an organic fuel such as methanol.

  A fuel cell is a cell that directly obtains electrical energy from the chemical energy of the fuel. For example, a direct methanol fuel cell (hereinafter referred to as DMFC: Direct Methanol Fuel) using a methanol aqueous solution composed of methanol and water (pure water) as fuel. Cell)) is known.

  In Japanese Patent Application Laid-Open No. 9-161822, a power generation unit (fuel cell structure, cell) in which an anode (anode electrode) and a cathode (cathode electrode) are opposed to each other with an electrolyte membrane (electrolyte) interposed therebetween is sandwiched by a separator. A stack-type fuel cell configured by stacking a plurality of layers is disclosed (see Patent Document 1).

Japanese Patent Laid-Open No. 2002-343378 discloses a fuel cell having a hollow support structure in which an anode is disposed inside a power generation unit, a cathode is disposed outside, and an electrolyte membrane is disposed between the anode and the cathode. A naturally aspirated fuel cell is disclosed in which a gas containing oxygen existing outside the unit comes into contact with the cathode electrode (see Patent Document 2).
JP-A-9-161822 JP 2002-343378 A

  For example, in a fuel cell using methanol aqueous solution as a fuel, that is, DMFC, the chemical energy possessed by methanol is directly converted into electrical energy by the following electrochemical reaction.

  On the anode electrode side, the supplied aqueous methanol solution reacts according to the equation (1) and dissociates into carbon dioxide, hydrogen ions (protons), and electrons.

CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (1)
The generated hydrogen ions move from the anode to the cathode in the electrolyte membrane, and react with oxygen gas and electrons on the electrode according to the formula (2) on the cathode electrode to generate water.

6H ⁺ + 3 / 2O ₂ + 6e ⁻ → 3H ₂ O (2)
Therefore, as shown in the formula (3), the total chemical reaction accompanying power generation is that methanol is oxidized by oxygen to generate carbon dioxide gas and water, and the chemical reaction formula is the same as that of combustion of methanol.

CH ₃ OH + 3 / 2O ₂ → CO ₂ + 3H ₂ O (3)
However, it is considered that the following problems are associated with the treatment of carbon dioxide gas and water, which are by-products.

  For example, when Pt (platinum) is used as an anode catalyst of DMFC, methanol shows a chemical reaction in the order of the following formulas (4) to (8).

Pt + CH ₃ OH → (Pt—CH ₂ OH) + H ⁺ + e ⁻ (4)
(Pt—CH ₂ OH) → (Pt—CHOH) + H ⁺ + e ⁻ (5)
(Pt—CHOH) → (Pt—COH) + H ⁺ + e ⁻ (6)
(Pt−COH) → (Pt−CO) + H ⁺ + e ⁻ (7)
(Pt-CO) + H ₂ O → Pt + CO ₂ + 2H ⁺ + 2e ⁻ (8)
In this way, carbon dioxide gas generated in the middle of the reaction, particularly carbon monoxide, poisons platinum, which is an anode catalyst, and the area of platinum that reacts with methanol is reduced, which is a cause of reducing the performance of DMFC. . Even if an alloy containing ruthenium or the like is used for the anode catalyst, it is not a sufficient measure.

  In addition, when the DMFC is installed and stored in a cold district environment, the following problems are considered. Since the solid polymer membrane used as the electrolyte membrane has water in the membrane, there is a problem that at the time of starting, the water in the membrane freezes and the starting cannot be performed smoothly. In addition, when the water generated by the electrochemical reaction is not sufficiently drained and remains after the driving is stopped, there is a problem that the water remaining in the apparatus freezes and cannot be restarted smoothly. In particular, in a stack type DMFC, water remaining in the piping system freezes and it is difficult to restart.

  Therefore, it is considered important to provide a new structure for solving the above problems.

  An object of the present invention is to provide a fuel cell having a novel structure.

  Another object of the present invention is to provide a fuel cell capable of effectively releasing carbon dioxide generated by an electrochemical reaction.

  Another object of the present invention is to provide a fuel cell that can effectively collect, discharge or circulate water generated by an electrochemical reaction.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  A fuel cell according to the present invention includes a cathode, an anode, an electrolyte membrane for insulating the cathode and the anode, a hollow support for supporting the cathode, the anode, and the electrolyte membrane, and the hollow support. A power generation unit including an oxygen supply means for supplying oxygen, wherein the power generation unit is immersed in liquid fuel, wherein the oxygen and the cathode are inside the power generation unit. The liquid fuel and the anode are in contact with each other outside the power generation unit.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  Carbon dioxide generated by the electrochemical reaction can be effectively released to the outside air (outside the fuel cell), and water generated by the electrochemical reaction can be effectively collected and circulated or discharged. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

(Embodiment 1)
A fuel cell of this embodiment, for example, DMFC, will be described with reference to FIGS. FIG. 1 is a cross-sectional view illustrating an outline of a power generation unit 1 of a DMFC. FIG. 2 is an explanatory diagram showing an outline of the DMFC 6 including the power generation unit 1.

  First, a schematic structure of the DMFC power generation unit 1 will be described. As shown in FIG. 1, the DMFC power generation unit 1 is formed by superposing a cathode electrode 3, an electrolyte membrane 4, and an anode electrode 5 in this order on the outer surface of a closed hollow support 2. Note that an oxygen supply means for supplying oxygen (a gas containing oxygen) to the power generation unit 1 to the hollow support 2 (for example, to the inside of the hollow support by a tube extending from the outside to the inside of the hollow support 2. When oxygen is supplied), oxygen supplied into the hollow support 2 by the oxygen supply means comes into contact with the cathode electrode 3. Further, when the power generation unit 1 is immersed in the liquid fuel, the liquid fuel and the anode electrode 5 are in contact with each other outside the power generation unit 1.

  The hollow support 2 has, for example, a cylindrical shape, and has a through-hole network shape or a through-type porous wall surface structure so that oxygen supplied into the hollow support 2 comes into contact with the cathode electrode 3. In the present embodiment, the hollow support 2 constituting the power generation unit 1 is a cylindrical shape, but the shape thereof is a rectangular parallelepiped shape, a conical shape, a polygonal column, a polygonal pyramid, a spherical shape, or other shapes. There is no particular limitation as long as the electrode (cathode / anode) area of the power generation unit 1 is sufficiently large. However, in order to immerse the power generation unit 1 in a specified container (tank), the cylindrical shape can be said to be a preferable shape in terms of processability and compactness.

  The material of the hollow support 2 is preferably a material that is electrochemically inactive, durable in the use environment, and has sufficient strength even when thin. For example, polyethylene, polypropylene, polyethylene terephthalate, vinyl chloride, polyacrylic resins, other engineering resins, and electrically insulating materials that are reinforced with various fillers, etc., and carbon materials with excellent corrosion resistance in the generated water atmosphere Further, there can be mentioned an electrically conductive material obtained by subjecting the surface of stainless steel, or ordinary iron, nickel, copper, aluminum and alloys thereof to corrosion resistance. It is also effective to use an insulating material obtained by coating a base metal having poor corrosion resistance with the above resin. In any case, the material is not particularly limited as long as the material supports the shape, the corrosion resistance, and the electrochemically inactive material.

  The cathode electrode 3 is formed from a carbon-based carrier in which platinum fine particles are dispersed and supported as a catalyst. The anode electrode 5 is formed of a carbon-based powder carrier in which platinum and ruthenium or platinum / ruthenium alloy fine particles are dispersed and supported as a catalyst. These catalysts are materials that can be easily manufactured and used. In addition, the catalyst of the cathode electrode 3 and the anode electrode 5 will not be restrict | limited especially if it is used for normal DMFC.

  The electrolyte membrane 4 is formed from, for example, a solid polymer membrane that exhibits hydrogen ion conductivity. Examples of such materials include sulfonated fluoropolymers such as polyperfluorostyrene sulfonic acid and perfluorocarbon sulfonic acid, and sulfonated hydrocarbon polymers such as polystyrene sulfonic acid and sulfonated polyether sulfonates. Can be used. If these materials are used as the electrolyte membrane 4, the fuel cell can generally be operated at a temperature of 80 ° C. or lower. In addition, by using a composite electrolyte membrane, etc., in which hydrogen ion conductive inorganic substances such as tungsten oxide hydrate, zirconium oxide hydrate, tin oxide hydrate and the like are micro-dispersed in a heat resistant resin, etc. It can also be a working fuel cell. In any case, when an electrolyte membrane having high hydrogen ion conductivity and low methanol permeability is used, the power generation utilization rate of fuel can be increased. For example, Nafion (registered trademark) can be used.

  Heretofore, the structure in which the power generation unit 1 of the DMFC is formed by superposing the cathode electrode 3, the electrolyte membrane 4 and the anode electrode 5 in this order on the outer surface of the closed hollow support 2 has been described. Even if the power generation unit 1 of the DMFC has a structure in which the anode electrode 5, the electrolyte membrane 4 and the cathode electrode 3 are stacked in this order on the inner side instead of the outer side of the closed hollow support 2 Good. In any case, the oxygen present inside the power generation unit 1 and the cathode electrode 3 inside the power generation unit 1 are in contact with each other, the liquid fuel existing outside the power generation unit 1, and the anode electrode outside the power generation unit 1 What is necessary is just to become the structure which 5 contacts.

  Here, the manufacturing method of the power generation unit 1 of the DMFC shown in FIG. 1 is (a1) a paste prepared by kneading a solution prepared by previously dissolving the same material as the cathode catalyst and the electrolyte membrane 4 in a volatile organic solvent as a binder. Is applied to the porous portion of the hollow support 2 at a constant thickness of about 10 to 50 μm to form the cathode electrode 3 on the outer periphery of the hollow support 2, (b1) previously dissolved in a volatile organic solvent A step of applying an electrolyte solution on the cathode electrode 3 so that the thickness after forming the electrolyte membrane 4 is about 20 to 50 μm; (c1) dissolving the anode catalyst and the same material as the electrolyte membrane 4 in a volatile organic solvent in advance A step of forming the anode electrode 5 by applying a paste obtained by kneading the obtained solution as a binder onto the electrolyte membrane 4 to a constant thickness of about 10 to 50 μm.

  In another manufacturing method, a module in which a cathode electrode 3 and an anode electrode 5 are formed on each side of the electrolyte membrane 4 and a mesh current collector plate for lowering electrical resistance is stacked on the electrodes is separately prepared. And a step of attaching the module to the outer wall portion of the closed hollow support 2.

  In addition, the power generation unit 1 of the DMFC is not the outer side surface of the closed hollow support 2 but the power generation unit 1 formed by superposing the anode electrode 5, the electrolyte membrane 4 and the cathode electrode 3 in this order on the inner side surface. The manufacturing method is as follows: (a2) A paste prepared by kneading a solution prepared by previously dissolving the same material as the anode catalyst and the electrolyte membrane 4 in a volatile organic solvent as a binder into a porous portion of the hollow support 2 to 10 to 50 μm. (B2) An electrolyte solution previously dissolved in a volatile organic solvent is applied on the anode electrode 5 to the electrolyte membrane 4. A step of coating so that the thickness after formation is about 20 to 50 μm, (c2) a paste prepared by kneading a solution prepared by previously dissolving the same material as the cathode catalyst and the electrolyte membrane 4 in a volatile organic solvent as a binder A step of coating the electrolyte film 4 on the electrolyte membrane 4 to a constant thickness of about 10 to 50 μm to form the cathode electrode 3.

  In any case, the cathode electrode 3, the electrolyte membrane 4, and the anode electrode 5 are overlapped and joined from the inside to the outside of the power generation unit 1, and between the cathode electrode 3 and the electrolyte membrane 4 and between the anode electrode 5 and the electrolyte membrane 4. The manufacturing method is not particularly limited as long as a sufficient reaction interface is formed therebetween, and a fuel cell having a novel structure can be manufactured.

  Next, a schematic structure of the DMFC 6 shown in the present embodiment will be described. As shown in FIG. 2, the DMFC 6 has an oxygen supply pipe 8 and a water discharge pipe 9 arranged in a power generation unit 1 in which a water reservoir 7 is processed and formed at the bottom of a hollow support 2, and generates power in a methanol aqueous solution in a tank 10. This is a structure in which the part 1 is immersed. The oxygen supply pipe 8 is provided with a filter 11 and an air pump 12. In FIG. 2, the hollow support 2, the cathode electrode 3, the electrolyte membrane 4, and the anode electrode 5 constituting the power generation unit 1 are not shown because FIG. 1 can be referred to.

  The water reservoir 7 is a portion formed to store water generated by an electrochemical reaction inside the power generation unit 1 (hollow support 2). The oxygen supply pipe 8 is used as an oxygen supply means for supplying oxygen into the hollow support 2, and gas containing oxygen sucked from the outside air through the filter 11 by the air pump 12 is introduced into the hollow support 2. It is a pipe | tube for supplying, The one end is arrange | positioned inside the electric power generation part 1 (hollow support body 2).

  The water discharge pipe 9 is a pipe for discharging the water accumulated in the water reservoir 7 to the outside of the power generator 1, and from the vicinity of the bottom inside the power generator 1 (hollow support 2) where the water reservoir 7 is provided. The power generation unit 1 is arranged to extend to the outside.

  The tank 10 is a container for storing an aqueous methanol solution, and an opening 13 for releasing the carbon dioxide gas generated by the anode electrode 5 is provided at the upper part thereof. That is, in order to effectively release the carbon dioxide gas generated by the electrochemical reaction to the outside air, the liquid fuel is put in the tank 10 which is an open container.

  It should be noted that one end of the oxygen supply pipe 8 disposed inside the hollow support 2 is preferably installed at a position higher than the discharge port of the water discharge pipe 9 inside the hollow support 2. This is to efficiently discharge the water accumulated in the water reservoir 7 and to prevent water from entering the oxygen supply pipe 8 and being unable to supply oxygen to the hollow support 2 during freezing.

  In the DMFC 6 shown in the present embodiment, the aqueous methanol solution supplied to the anode electrode 5 reacts according to the equation (1) to dissociate into carbon dioxide, hydrogen ions (protons), and electrons. The generated hydrogen ions move in the electrolyte membrane 4 from the anode electrode 5 to the cathode electrode 3 side, and react with oxygen and electrons on the electrode on the cathode electrode 3 to generate water. . Therefore, as shown in the above formula (3), the total chemical reaction associated with power generation is such that methanol is oxidized by oxygen to produce carbon dioxide and water, and the chemical energy of methanol is directly converted into electrical energy. Power is generated.

  Thus, the DMFC 6 shown in the present embodiment does not require a fuel pump or the like required for the stack type DMFC as in the above-mentioned Patent Document 1, and the material cost and processing cost are suppressed because the configuration is easy. be able to. Regarding the fuel pump, in the DMFC 6 shown in the present embodiment, since the power generation unit 1 is immersed in an aqueous methanol solution, the fuel can be oxidized at the anode electrode without the need for supply by the fuel pump.

  Further, in the stack type DMFC as in the above-mentioned Patent Document 1, in order to join the power generation unit and the power generation unit, both joints are screwed. However, since the electrode area is large and the surface pressure is not constant, the joining is performed. There is a problem that fuel leakage occurs in the part. In this respect, the DMFC 6 shown in the present embodiment does not have such a joint portion, and therefore it is possible to avoid the occurrence of fuel leakage.

  Further, in the naturally aspirated DMFC such as Patent Document 2, the outside air (gas containing oxygen) is in contact with the cathode electrode disposed on the outer periphery of the power generation unit, and oxygen is supplied to the cathode electrode. In this structure, the electrode is exposed to the outside. In this regard, in the DMFC 6 shown in the present embodiment, since the power generation unit 1 is immersed in the aqueous methanol solution in the tank 10, the electrode is not exposed to the outside and high reliability can be ensured.

  In addition, in the stack type DMFC as in the above-mentioned Patent Document 1, in order to obtain a large output, a stacked structure is formed in order to connect the power generation units in series. Necessary. In this regard, in the DMFC 6 shown in the present embodiment, a large output can be obtained simply by connecting the power generation unit 1 in series in an aqueous methanol solution.

  Further, in the natural intake type DMFC as in Patent Document 2, oxygen is supplied to the cathode electrode without providing a filter outside the power generation unit in order to efficiently intake air from the outside. There is a problem of getting dirty. In this regard, in the DMFC 6 shown in the present embodiment, a gas (air) containing oxygen can be sucked from the outside through the filter 11 and can be supplied to the cathode electrode 3 by the air pump 12, so that dust can be removed. It is possible to prevent the cathode electrode 3 from becoming dirty. In addition, by using an oxygen-enriched film instead of the filter 11, the oxygen concentration of the cathode electrode 3 can be increased and the power generation efficiency can be further improved.

  Further, when oxygen is supplied from the oxygen supply pipe 8 to the cathode electrode 3 inside the power generation unit 1 and water is generated by an electrochemical reaction, the water is collected in the water reservoir 7 at the bottom of the hollow support 2. It becomes. Thus, by providing the water reservoir 7, the generated water can be collected effectively. Moreover, since the inside of the hollow support 2 has a closed structure in which the gas containing oxygen supplied from the oxygen supply pipe 8 is confined, the collected water is separated by the pressure of the gas containing oxygen. It can be pushed up and effectively discharged from the water discharge pipe 9 to the outside of the hollow support 2. As described above, since water is effectively discharged, even if the DMFC 6 is installed in a cold region environment, it is possible to prevent icing and to easily perform restart. The water discharged from the power generation unit 1 can be used not only by draining but also circulating.

  In addition, in the stack type DMFC as in Patent Document 1, power generation cannot be stopped unless the water supplied to the anode electrode or the water generated at the cathode electrode is drained. Further, in the naturally aspirated DMFC as in Patent Document 2, power generation cannot be stopped until the aqueous methanol solution supplied into the hollow support is consumed. In this regard, in the DMFC 6 shown in the present embodiment, when oxygen is supplied from the oxygen supply pipe 8 to the inside of the hollow support 2 at the start, an electrochemical reaction occurs in the power generation unit 1 and the methanol has. Electricity is generated in the form of chemical energy converted directly into electrical energy. On the other hand, when the DMFC 6 is stopped, the supply of oxygen from the oxygen supply pipe 8 into the hollow support 2 is stopped. Therefore, on / off control of power generation can be easily performed only by the presence or absence of oxygen supply to the cathode electrode 3 (inside the hollow support 2).

  Since the opening 13 is provided in the upper part of the tank 10 containing the methanol aqueous solution, the carbon dioxide gas generated by the electrochemical reaction is generated at the anode electrode 5 of the power generation unit 1 immersed in the methanol aqueous solution. It can be released from the inside to the outside air. Therefore, even if platinum is used for the anode catalyst, for example, platinum poisoning by carbon dioxide gas can be prevented, and deterioration of the performance of the fuel cell can be prevented. In addition, when the DMFC 6 is stopped, natural evaporation of fuel can be prevented by attaching a shutter (valve) to the opening 13 for releasing carbon dioxide gas.

  Further, in the DMFC 6 shown in the present embodiment, the methanol aqueous solution (liquid fuel) need only be replenished to the tank 10 as appropriate, so that the amount of liquid fuel can be easily managed. If the tank 10 is transparent, the amount can be determined visually.

  In addition, since the pressure of oxygen supplied from the oxygen supply pipe 8 applies pressure from the inside to the outside of the hollow support 2, a part of methanol supplied to the anode electrode 5 permeates the electrolyte membrane 4. Thus, it can be considered that the phenomenon of reaching the cathode electrode 3 (crossover phenomenon) can be suppressed. Therefore, if the crossover phenomenon can be suppressed, the output and efficiency of the DMFC 6 can be improved.

  Further, since the DMFC 6 shown in the present embodiment has a structure in which a power generation unit is immersed in liquid fuel and generates power, the stack type DMFC as in Patent Document 1 can be reduced in size. Therefore, it can be used as a generator motor, a generator for automobiles, and the like. When used as an automobile generator, the heat generated by the DMFC 6 can be used as heating in the vehicle.

(Embodiment 2)
The fuel cell of this embodiment, for example, DMFC will be described with reference to FIGS. 3 and 4 are explanatory views showing an outline of the DMFC 21 shown in the present embodiment. The present embodiment is different from the first embodiment in that the replacement fluids 22a (see FIG. 3) and 22b (see FIG. 4) are arranged in the power generation unit 1 of the DMFC 6 shown in the first embodiment. The power generation unit 1 according to the present embodiment is the same as the power generation unit 1 according to the first embodiment, and the description thereof is omitted.

  As shown in FIG. 3, the replacement fluid 22 a is disposed throughout the tank 10 containing the aqueous methanol solution so as to cover the power generation unit 1. The replenisher 22a is a material that is disposed so that an aqueous methanol solution is always supplied to the anode electrode provided in the power generation unit 1, and is made of, for example, a material that is sucked up by capillary force. Therefore, even if the DMFC 6 is tilted due to vibration or the like, the methanol aqueous solution sucked up by the replacement fluid 22a is supplied to the anode electrode, and the efficiency of the DMFC 21 can be prevented from being lowered. Further, by driving the DMFC 21, even if the methanol aqueous solution is reduced and the liquid level thereof is lowered, the methanol aqueous solution is supplied to the anode electrode through the replacement fluid 22a, thereby preventing a decrease in power generation efficiency of the DMFC 21. Can do.

  Moreover, the electric power generation part 1 can be stabilized by satisfy | filling the tank 10 whole with the replacement fluid 22a rather than the case where the replacement fluid 22a is not used.

  Next, as shown in FIG. 4, unlike the replacement fluid 22 a that fills the tank 10, a thin replacement fluid 22 b is disposed on the outer peripheral surface of the power generation unit 1. Similar to the replacement fluid 22a, the replacement fluid 22b is a material that is disposed so that a methanol aqueous solution is always supplied to the surface of the anode electrode 5. For example, the replacement fluid 22b is made of a material that is sucked up by capillary force. Therefore, as shown in FIG. 4, even if the water surface of the methanol aqueous solution is inclined and the cathode electrode 5 is exposed outside the liquid surface, the methanol aqueous solution is supplied to the anode electrode 5 through the replacement fluid 22b. A decrease in efficiency can be prevented. Further, by driving the DMFC 21, even if the methanol aqueous solution is reduced and the liquid level thereof is lowered, the methanol aqueous solution is supplied to the anode electrode 5 through the replacement fluid 22b, thereby preventing a decrease in power generation efficiency of the DMFC 21. be able to.

  Moreover, since the thickness of the replacement fluid 22b covering the power generation unit 1 is thinner than the case where the replacement fluid 22a is disposed in the entire tank 10, the carbon dioxide generated by the electrochemical reaction at the cathode electrode can be released more effectively. it can.

  As described above, the anode electrode of the DMFC 21 shown in the present embodiment is covered with the replacement fluid 22a or the replacement fluid 22b for always supplying the aqueous methanol solution, so that the place (bicycle) is vibrated when installing, arranging, or the like. , Motorcycles, automobiles, etc.).

(Embodiment 3)
The fuel cell of this embodiment, for example, DMFC will be described with reference to FIG. FIG. 5 is an explanatory diagram showing an outline of the DMFC 31 in the present embodiment.

  The DMFC 31 includes a power generation unit 1 having a puddle unit 7, an oxygen supply unit for supplying oxygen to the power generation unit 1, and a discharge circulation for discharging or circulating water generated by an electrochemical reaction in the power generation unit 1. Means, fuel supply means for supplying fuel to the power generation unit 1, and temperature raising means for increasing the temperature of the fuel supplied to the power generation unit 1. In addition, since this electric power generation part 1 and the puddle part 7 are the same as that of the power generation part 1 and the puddle part 7 which were shown in the said Embodiment 1 or 2, the description is abbreviate | omitted.

  The oxygen supply means uses an oxygen supply pipe 32, a filter 33, a manual air pump 34 for start-up, an electric air pump 35, an emergency oxygen discharge pipe 36 and an oxygen discharge valve 37 to generate power from the outside. Oxygen is supplied to the cathode electrode constituting part 1.

  An oxygen supply pipe 32 for supplying air containing oxygen from the outside to the power generation unit 1 extends from the outside of the power generation unit 1 to the inside. A filter 33 is disposed on the outside air side of the oxygen supply pipe 32, and the dust in the gas containing oxygen can be removed by the gas containing oxygen passing through the filter 33.

  In the section from the filter 33 to the power generation unit 1, the oxygen supply pipe 32 branches and a starting manual air pump 34 and an electric air pump 35 are arranged, respectively. The gas containing oxygen that has passed through the filter 33 is supplied to the power generation unit 1 by the manual air pump 34 for starting at the time of startup and by the electric air pump 35 at the time of driving. Therefore, in the present embodiment, the manual air pump 34 supplies a gas containing oxygen to the power generation unit 1 at the start before power generation, and the electric air pump 35 is switched after the power generation. The DMFC 31 can be configured to require no power other than the power generated by the power generation unit 1.

  In the section between the starting air pump 34 or the electric air pump 35 and the power generation unit 1, a part of the oxygen supply pipe 32 is disposed so as to be immersed in the aqueous methanol solution, for example, in the form of a snake tube. . For this reason, when the gas containing oxygen passes through the oxygen supply pipe 32 immersed in the aqueous methanol solution heated by the heat during power generation, the gas containing oxygen is also warmed and supplied to the power generation unit 1. Power generation efficiency can be improved.

  Further, in the power generation unit 1, an oxygen discharge pipe 36 is disposed so as to extend from the inside of the power generation unit 1 to the outside, and an oxygen discharge valve 37 is disposed in the oxygen discharge pipe 36. For example, when the DMFC 31 is installed and stored in a cold region, water remaining after power generation stops freezes in the power generation unit 1 and various pipes, and even if oxygen-containing gas is supplied, power generation does not occur. There is. In such an emergency, power can be generated by supplying a gas containing oxygen to the power generation unit 1 by the manual air pump 34 until the ice melts due to heat generated by the power generation. That is, an emergency situation can be avoided by opening the oxygen discharge valve 37 and discharging the oxygen-containing gas that was not involved in the power generation from the oxygen discharge pipe 36.

  The discharge circulation means uses the water discharge pipe 38 and the water diverter 39 to collect the water generated by the electrochemical reaction in the power generation unit 1 in the water reservoir 7 and then discharges the water to the outside of the power generation unit 1 for discharge. Part of the collected water is circulated continuously or intermittently to the liquid fuel.

  A water discharge pipe 38 for discharging water generated by an electrochemical reaction in the power generation unit 1 to the outside of the power generation unit 1 is disposed so as to extend from the vicinity of the bottom inside the power generation unit 1 to the outside. Therefore, water accumulated at the bottom of the power generation unit 1 from one end of the water discharge pipe 38 disposed near the bottom of the power generation unit 1 is generated by the pressure of the gas containing oxygen supplied into the power generation unit 1. It is discharged outside the unit 1.

  The water discharge pipe 38 is provided with a water diverter 39 for separating the water discharged from the power generation unit 1. A part of the water separated by the water separator 39 is sent as circulating water to a tank 40 in which an aqueous methanol solution is stored, and the remainder of the separated water is discharged outside the DMFC 31. Accordingly, if the amount of water is adjusted by the water diverter 39 so that the water generated by the power generation is circulated and the aqueous methanol solution has an optimal concentration, it can be mixed with the high-concentration methanol aqueous solution described later.

  The fuel supply means supplies fuel to the anode electrode constituting the power generation unit 1 by using a tank 40 in which a methanol aqueous solution is placed and a tank 41 in which a methanol aqueous solution having a higher concentration than the methanol aqueous solution is placed. The fuel supply means has replenishing means for replenishing the tank 40 with a high-concentration methanol aqueous solution when the methanol aqueous solution in the tank 40 is reduced by power generation or the like.

  As shown in FIG. 5, since the power generation unit 1 is immersed in the aqueous methanol solution stored in the tank 40, the anode electrode of the power generation unit 1 and the aqueous methanol solution are in contact with each other. Here, when the methanol aqueous solution in the tank 40 is reduced by power generation, a high-concentration methanol aqueous solution is supplied from the tank 41 into the tank 40 and can be mixed with the circulating water so as to be an optimal methanol aqueous solution. The tank 40 is provided with an opening 42 for discharging the carbon dioxide gas generated by the anode electrode.

  The temperature raising means raises the temperature of the aqueous methanol solution using the temperature raising tool 43. The temperature raising tool 43 increases the temperature of the aqueous methanol solution so that the low temperature aqueous methanol solution efficiently generates power when the DMFC 31 is placed and stored in a cold region environment. Therefore, if the temperature raising device 43 is an electrical temperature raising device, for example, a temperature-controllable heater, the aqueous methanol solution can be adjusted to a temperature most suitable for power generation (about 80 ° C.). Can be improved. The temperature raising tool 43 may be a chemical temperature raising tool that does not require electric power, such as a heater, such as one that generates heat by a chemical reaction between calcium oxide and water. Such a chemical heating device is particularly effective when warming an aqueous methanol solution or the like in order to start the DMFC 31 in a place where there is no electric power.

  Further, the DMFC 31 shown in the present embodiment can be used, for example, as an emergency power source or a monitor / sensor power source in remote areas. Moreover, since the startability at a low temperature is good, it can also be used for automobile fuel cells.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, since the fuel cell shown in the above embodiment is a fuel cell having a novel structure, its function as a single unit has been described. However, a motor generator, an automobile and a motorcycle, an emergency power source, a remote monitor / Can be widely used for power supplies for sensors.

  The present invention is widely used in the manufacturing industry for manufacturing fuel cells.

It is sectional drawing which shows the outline of the electric power generation part of DMFC in Embodiment 1 of this invention. 2 is an explanatory diagram showing an outline of a DMFC shown in Embodiment 1. FIG. It is explanatory drawing which shows the outline of DMFC in Embodiment 2 of this invention. 6 is an explanatory diagram showing an outline of a DMFC shown in Embodiment 2. FIG. It is explanatory drawing which shows the outline of DMFC in Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generation part 2 Hollow support body 3 Cathode electrode 4 Electrolyte membrane 5 Anode electrode 6 DMFC
7 Water reservoir 8 Oxygen supply pipe 9 Water discharge pipe 10 Tank 11 Filter 12 Air pump 13 Opening 21 DMFC
22a, 22b Fluid replacement material 31 DMFC
32 Oxygen supply pipe 33 Filter 34 Manual air pump 35 Electric air pump 36 Oxygen discharge pipe 37 Oxygen discharge valve 38 Water discharge pipe 39 Divider 40 Tank 41 Tank 42 Opening 43 Heating tool

Claims (5)

A cathode, an anode, an electrolyte membrane for insulating the cathode and the anode, a hollow support for supporting the cathode, the anode and the electrolyte membrane, and supplying oxygen into the hollow support A fuel cell having a power generation unit provided with oxygen supply means, wherein the power generation unit is immersed in liquid fuel,
The fuel cell, wherein the oxygen and the cathode are in contact with each other inside the power generation unit, and the liquid fuel and the anode are in contact with each other outside the power generation unit. The fuel cell according to claim 1, wherein
The liquid fuel is a methanol aqueous solution composed of methanol and water,
Discharge / circulation means for discharging water generated by an electrochemical reaction inside the power generation unit from the inside of the power generation unit to the outside and circulating a part of the discharged water continuously or intermittently to the aqueous methanol solution A fuel cell comprising: The fuel cell according to claim 2, wherein
Replenishment means for replenishing a high-concentration methanol aqueous solution having a higher concentration than the methanol aqueous solution;
A fuel cell, wherein the aqueous methanol solution having a low concentration by water circulated by the drainage circulation means is supplemented with the aqueous high-concentration methanol solution to adjust the aqueous methanol solution to a constant concentration. In the fuel cell as described in any one of Claims 1-3,
The fuel cell according to claim 1, wherein the oxygen supply means includes a filter or an oxygen-enriched film for removing dust and takes in the oxygen. In the fuel cell as described in any one of Claims 1-4,
The fuel cell according to claim 1, wherein the oxygen supply means supplies the oxygen to the hollow support body after being heated by the heat of the liquid fuel.

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