JP2008243746A - Fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell device capable of stably generating power for a long period of time. <P>SOLUTION: The fuel cell device includes an electromotive part 32 having a laminated cell with a polymer film pinched by an anode 47 with an anode catalyst and a cathode 52 and generating power by chemical reaction, a fuel tank 22 housing fuel, a circulation system containing a fuel flow channel 36 circulating fuel supplied from the fuel tank through an anode of the electromotive part, and an air flow channel 38 supplying air through the cathode of the electromotive part, and a replenishment mechanism 60 for supplying catalyst solution of the anode catalyst to the anode and replenishing the anode catalyst to the anode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell device used as a power source for electronic devices and the like.

  Currently, secondary batteries such as lithium ion batteries are mainly used as power sources for portable notebook personal computers (hereinafter referred to as notebook PCs) and mobile devices. In recent years, a small fuel cell with high output and no need for charging has been expected as a new power source due to an increase in power consumption accompanying the enhancement of functions of these electronic devices and a request for longer use. There are various types of fuel cells. In particular, a direct methanol fuel cell using a methanol solution as a liquid fuel (hereinafter referred to as DMFC) handles fuel more than a fuel cell using hydrogen as a fuel. Since it is easy and the system is simple, it is expected to be applied in various fields including electronic equipment.

  Usually, the DMFC includes a fuel tank in which methanol is stored, a liquid feed pump that pumps methanol to the electromotive unit, an air pump that supplies air to the electromotive unit, and the like. The electromotive unit includes a cell stack in which a single cell or a plurality of single cells are stacked, and the single cell has a layer structure in which an anode (fuel electrode) and a cathode (air electrode) are stacked with a polymer film interposed therebetween. Yes. The DMFC extracts electric energy by oxidizing methanol at the anode and simultaneously reducing oxygen at the cathode.

Since such a redox reaction is difficult to proceed at room temperature, the anode and cathode of the cell are formed with a catalyst. For example, the anode and the cathode are formed of a mixture of a carbon carrier supporting a catalyst such as platinum (Pt), an electrolyte, and a binder. Here, platinum used as an anode catalyst has a problem in that CO generated during the methanol oxidation process is chemically adsorbed, and eventually the catalytic activity ability is lost. In order to suppress such poisoning of the catalyst by CO, an anode using a catalyst obtained by adding ruthenium to platinum is provided as an anode catalyst (for example, Patent Document 1).
JP 2006-269096 A

  In the DMFC configured as described above, there are several phenomena that are the cause of the decrease in output. Among them, the solute of ruthenium (Ru), which is a part of the catalyst constituting the anode catalyst, can be mentioned. . In general, the oxidation of methanol, which is an anodic reaction, is normally performed when appropriate amounts of Pt and Ru are present.

  However, Ru is ionized by a long-term power generation operation due to its metallic properties, and is peeled off and soluted from the anode catalyst layer. The solute Ru moves into the polymer membrane or the cathode catalyst layer. Due to this Ru movement phenomenon, the balance of the optimum Pt—Ru alloy is lost in the anode catalyst layer, and the Pt-rich alloy is lost, resulting in a decrease in chemical reactivity at the anode. This causes a reduction in the power generation capacity of the battery.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel cell device capable of stable power generation for a long time.

  A fuel cell device according to an embodiment of the present invention includes a cell in which an anode having an anode catalyst and a cathode are stacked with a polymer film sandwiched therebetween, an electromotive section that generates power by a chemical reaction, and a fuel A circulation system having a fuel tank, a fuel flow path for circulating the fuel supplied from the fuel tank through the anode of the electromotive section, and a gas flow path for supplying air through the cathode of the electromotive section; Replenishment means for supplying a catalyst solution of the anode catalyst to the anode and replenishing the anode catalyst to the anode.

  According to the above configuration, a fuel cell device capable of improving the power generation performance of the fuel cell by replenishing the anode with an anode catalyst for a long period of use and capable of stable power generation for a long time is provided. be able to.

Hereinafter, a fuel cell device according to a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 schematically shows the configuration of a circulation system of a fuel cell device. As shown in FIG. 1, the fuel cell device 10 is configured as a DMFC using methanol as a liquid fuel. The fuel cell device 10 includes a cell stack 12 that constitutes an electromotive unit, a fuel tank 22, a circulation system 34 that supplies fuel and air to the cell stack, and a battery control unit 50 that controls the operation of the entire fuel cell device. Yes.

  The fuel tank 22 has a sealed structure, and is formed as a fuel cartridge that is detachable from the fuel cell device 10. The fuel tank 22 contains high-concentration methanol as liquid fuel. When the fuel is consumed, the fuel tank 22 can be easily replaced. The fuel tank 22 has a fuel supply port 22a for supplying fuel and an air intake port 22b for taking air into the fuel tank. The fuel supply port 22 a and the air intake port 22 b are formed on the side surface of the fuel tank 22, for example. During operation of the fuel cell device, the fuel tank 22 takes air into the tank through the air intake port 22b by the volume of the fuel discharged from the fuel supply port 22a.

  The circulation system 34 is a fuel flow path (liquid flow path system) 36 that circulates fuel supplied from the fuel supply port 22 a of the fuel tank 22 through the cell stack 12, and an air flow that circulates gas including air through the cell stack 12. It has a plurality of auxiliary machines provided in the passage (gas passage system) 38, the fuel passage and the air passage. The fuel flow path 36 and the air flow path 38 are each formed by piping or the like. Further, the fuel flow path 36 also functions as a catalyst flow path 37 for circulating a catalyst solution described later.

  FIG. 2 shows the laminated structure of the cell stack 12, and FIG. 3 schematically shows the power generation reaction of each cell. As shown in FIG. 3 and FIG. 4, the cell stack 12 includes a laminate formed by alternately laminating a plurality of, for example, four single cells 140 and five rectangular plate-like separators 142, and a laminate. It has a frame 145 that supports the body. Each single cell 140 integrates a substantially rectangular sheet-like cathode 52 and anode 47 each composed of a catalyst layer and carbon paper, and a substantially rectangular polymer electrolyte membrane 144 sandwiched between the cathode and anode. The membrane-electrode assembly (MEA) is provided. The catalyst layer of the cathode 52 contains platinum (Pt) as a metal component that promotes the oxidation-reduction reaction. Similarly, the catalyst layer of the anode 47 contains, as an anode catalyst, substantially the same amount of Pt that promotes the redox reaction and ruthenium (Ru) that is a noble metal component. The polymer electrolyte membrane 144 is formed in a larger area than the anode 47 and the cathode 52.

Precious metal compounds as anode catalysts include Ru, ruthenium chloride hydrate (RuCl ₃ · xH ₂ O), osmium chloride hydrate (OsCl ₃ · xH ₂ O), palladium chloride (PdCl ₂ ), iridium chloride (InCl) ₃ ), gold chloride (AuCl ₃ ) and rhodium chloride hydrate (RhCl ₃ · xH ₂ O) can be used.

  The three separators 142 are stacked between two adjacent single cells 140, and the other two separators are stacked at both ends in the stacking direction. The separator 142 and the frame 145 are formed with a fuel flow path 146 that supplies fuel to the anode 47 of each single cell 140 and an air flow path 147 that supplies air to the cathode 52 of each single cell.

  As shown in FIG. 3, the supplied fuel (methanol aqueous solution) and air chemically react with the polymer electrolyte membrane 144 provided between the anode 47 and the cathode 52, whereby the anode and cathode are in contact with each other. Electric power is generated between them. The electric power generated in the cell stack 12 is supplied to an external device (not shown) via the battery control unit 50.

  As shown in FIG. 1, the auxiliary machine provided in the fuel flow path 36 is connected to the fuel pump 40 connected to the fuel supply port 22 a of the fuel tank 22 through the pipe, and to the output portion of the fuel pump 40 through the pipe. A fuel mixing section 42 and a liquid feed pump (not shown) connected to the output section of the fuel mixing section 42 are provided. The output part of the liquid feed pump is connected to the anode 47 of the cell stack 12 via the fuel flow path 36.

  The output part of the anode 47 of the cell stack 12 is connected to the input part of the fuel mixing part 42 via the fuel flow path 36 and the gas-liquid separator 44. The discharged fluid discharged from the anode 47 of the cell stack 12, that is, the unreacted aqueous methanol solution that has not been used for the chemical reaction and the generated carbon dioxide are sent to the gas-liquid separator 44, where the liquid and gas are separated. To be separated. The separated methanol aqueous solution is returned to the fuel mixing section 42 through the fuel flow path 36, and the carbon dioxide is discharged to the outside through the air flow path 38 and the exhaust filter 54.

  The upstream end 38a and the downstream end 38b of the air flow path 38 communicate with the atmosphere. The auxiliary equipment provided in the air flow path 38 is connected to the air flow path between the intake filter 46 provided near the upstream end of the air flow path 38 on the upstream side of the cell stack 12 and between the cell stack 12 and the intake filter. And an exhaust filter 54 provided near the downstream end of the air flow path 38 on the downstream side of the cell stack 12.

  The intake filter 46 captures and removes dust, impurities, and the like in the air sucked into the air flow path 38. The exhaust filter 54 detoxifies by-products in the gas exhausted from the air flow path 38 to the outside, and captures the fuel gas and the like contained in the exhaust.

  On the other hand, the fuel cell device 10 includes a replenishment mechanism 60 that supplies a catalyst solution of the anode catalyst to the anode 47 and replenishes the anode with the anode catalyst. As shown in FIG. 1, the replenishing mechanism 60 includes a replenishing tank 62 that contains a fuel (methanol) mixed with an anode catalyst, for example, a catalyst solution containing Ru. The replenishment tank 62 is configured as a replenishment cartridge that is detachable from the fuel cell device 10. The replenishment tank 62 is configured to be attachable to the fuel cell device 10 in place of the fuel tank 22.

  The replenishing tank 62 is formed to have substantially the same size and structure as the fuel tank 22, and has a catalyst supply port 62a for supplying a mixed solution of the catalyst solution and the fuel and an air intake port 62b for taking air into the replenishing tank. ing. In a state where the replenishing tank 62 is mounted, the catalyst supply port 62 a of the replenishing tank 62 is connected to the fuel flow path 36 that also serves as the catalyst flow path 37 of the fuel cell device 10. When replenishing the catalyst, the replenishing tank 62 takes air into the tank from the air intake port 62b by the volume of the liquid mixture discharged from the catalyst supply port 62a.

  The replenishment mechanism 60 includes a battery control unit 50 and a display unit 64 connected to the battery control unit 50. The display unit 64 is configured by, for example, a liquid crystal display panel, an LED, or the like. The battery control unit 50 detects the generated power of the electromotive unit 32, and when the generated power is reduced to a predetermined value, the battery control unit 50 stops the power generation operation of the electromotive unit and causes the display unit 64 to reduce the generated power, or Information indicating the mounting of the replenishing tank 62 is displayed. When the replenishment tank 62 is installed instead of the fuel tank 22, the battery control unit 50 operates the fuel pump 40 to supply the fuel mixed with the catalyst solution from the replenishment tank 62 to the anode 47 of the cell stack 12. Time supply. At this time, the fuel mixed with the catalyst solution is circulated through the catalyst flow path 37 through the fuel mixing section 42, the anode 47, and the gas-liquid separator 44.

  Ru as an anode catalyst contained in the supplied catalyst solution is supplied to the catalyst layer of the anode 47 and taken into the catalyst layer. As a result, Ru that is lost due to long-term use of the fuel cell device 10 is replenished to the anode layer. For example, when the fuel cell device 10 is operated for about 500 hours, the Ru content in the catalyst layer of the anode 47 is reduced by about 1% compared to the initial content, and the generated power is reduced accordingly. To do. Thus, when the generated power is reduced by a predetermined value, the replenishment mechanism 60 replenishes Ru by 1%, whereby the power generation capability of the fuel cell device 10 can be recovered.

  The battery control unit 50 automatically suggests that the replenishment tank 62 is attached after a predetermined power generation time has elapsed, and when the replenishment tank is attached, the battery control unit 50 removes the catalyst solution and the fuel from the replenishment tank. The mixed solution may be supplied to the anode 47.

  When the fuel cell device 10 configured as described above is used as a power source, first, a fuel tank 22 containing methanol is attached and connected to the circulation system 34 of the fuel cell device 10. In this state, power generation of the fuel cell device 10 is started. In this case, the fuel pump 40 and the intake pump 48 are operated under the control of the battery control unit 50. High-concentration methanol is supplied from the fuel tank 22 to the fuel mixing section 42 through the fuel flow path 36 by the fuel pump 40, and water is mixed in the fuel mixing section to be diluted to a predetermined concentration. The aqueous methanol solution diluted in the fuel mixing unit 42 is supplied to the anode 47 of the cell stack 12 through the fuel flow path 36.

  On the other hand, the air, that is, air is sucked into the air flow path from the upstream end 38 a of the air flow path 38 by the intake pump 48. This air passes through the intake filter 46, where impurities in the air are removed. After passing through the intake filter 46, the air is supplied to the cathode 52 of the cell stack 12 through the air flow path 38.

  The aqueous methanol solution and air supplied to the cell stack 12 undergo an electrochemical reaction at the polymer electrolyte membrane 144 provided between the anode 47 and the cathode 52, whereby electric power is transferred between the anode 47 and the cathode 52. appear. The electric power generated in the cell stack 12 is supplied to an external device via the battery control unit 50.

  Along with the electrochemical reaction, carbon dioxide is generated on the anode 47 side and water is generated on the cathode 52 side as reaction products in the cell stack 12. The carbon dioxide generated on the anode 47 side and the methanol aqueous solution not subjected to the chemical reaction are sent to the gas-liquid separator 44 through the fuel flow path 36, where they are separated into carbon dioxide and methanol aqueous solution. The aqueous methanol solution is sent from the gas-liquid separator 44 through the fuel flow path 36 to the fuel mixing unit 42 and is used again for power generation. The separated carbon dioxide and splashed methanol are sent together with air to the exhaust filter 54 through the air flow path 38, where toxic substances are removed, and then exhausted from the downstream end 38b of the air flow path 38 to the outside. The

  The water vapor generated on the cathode 52 side of the cell stack 12 is sent to the exhaust filter 54 through the air flow path 38 and further exhausted to the outside from the downstream end of the air flow path 38.

  On the other hand, during operation of the fuel cell device 10, fuel is supplied from the fuel tank 22, and the fuel in the fuel tank decreases. Accordingly, air is taken into the fuel tank 22 from the air intake port 22b by the volume of the fuel, and the reduced volume of the fuel is replaced with air. At this time, air is taken in from the circulation system 34 of the fuel cell device 10.

  During the operation of the fuel cell device 10, the battery control unit 50 detects the generated power of the electromotive unit 32, and when the generated power is reduced to a predetermined value, stops the power generation operation of the electromotive unit and displays on the display unit 64. Information indicating a decrease in power generation or mounting of the replenishing tank 62 is displayed. When the replenishment tank 62 is installed instead of the fuel tank 22, the battery control unit 50 operates the fuel pump 40, and converts the catalyst solution supplied from the replenishment tank 62 into the fuel mixing unit 42, the anode 47, the gas liquid. Circulate through the separator 44 for a predetermined time. Thereby, Ru as an anode catalyst contained in the catalyst solution is replenished to the anode 47, and the power generation capability of the fuel cell device 10 is recovered.

  According to the fuel cell device 10 configured as described above, even when the anode catalyst is lost due to the long-term power generation operation and the generated power is reduced, the anode catalyst is replenished so that the power generation capacity of the electromotive unit is increased. Can be recovered. As a result, a fuel cell device that improves power generation performance and can stably generate power over a long time can be obtained. And it becomes possible to improve the commercial value of a fuel cell apparatus by extending battery life.

  Next explained is a fuel cell apparatus according to the second embodiment of the invention. As shown in FIG. 4, according to the second embodiment, the replenishment tank 62 is not a detachable cartridge type, but is permanently installed in the fuel cell device 10. In the replenishing tank 62, an anode catalyst, for example, a catalyst solution containing Ru is stored. The replenishment tank 62 is connected between the fuel tank 22 and the fuel pump 40 via the open / close valve 66 to the fuel flow path 36.

  The battery control unit 50 constituting the replenishing mechanism 60 detects the generated power of the electromotive unit 32, and when the generated power is reduced to a predetermined value, or when a predetermined power generation time has passed, The power generation operation of the electric unit 32 is stopped, the opening / closing valve 66 is opened, and the fuel pump 40 is operated for a predetermined time. As a result, the catalyst solution is supplied from the replenishing tank 62 to the fuel mixing section 42 through the fuel flow path 36. The catalyst solution is mixed with the methanol aqueous solution in the fuel mixing unit 42 and then circulated through the anode 47 of the electromotive unit 32, the gas-liquid separator 44, and the fuel mixing unit 42. Therefore, Ru is supplemented to the catalyst layer of the anode 47, and the power generation output of the electromotive unit 32 is recovered.

  In the second embodiment, the other configuration of the fuel cell apparatus is the same as that of the first embodiment described above, and the same reference numerals are given to the same portions, and detailed description thereof is omitted. Also in the second embodiment, the same operational effects as those of the first embodiment described above can be obtained.

  In the second embodiment, a mixed solution of the catalyst solution and the fuel may be stored in the replenishment tank. Further, the catalyst solution may be directly supplied from the replenishing tank to the anode of the electromotive unit.

  The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  For example, the catalyst added to the anode and the cathode is not limited to Pt and Ru, and can be variously selected according to the intended function. The form of the fuel cell is not limited to DMFC, but may be other forms such as PEFC (Polymer Electrolyte Fuel Cell).

FIG. 1 is a block diagram schematically showing the configuration of a fuel cell device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a DMFC stack of the fuel cell device. FIG. 3 schematically shows a single cell of the DMFC stack. FIG. 4 is a block diagram schematically showing a configuration of a fuel cell device according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell apparatus, 22 ... Fuel tank, 22a ... Fuel supply port, 32 ... Cell stack,
32 ... Electromotive unit, 34 ... Circulation system, 36 ... Fuel flow path, 38 ... Air flow path, 47 ... Cathode,
52 ... Anode, 50 ... Battery controller, 60 ... Replenishment mechanism, 62 ... Replenishment tank

Claims (9)

An electromotive unit having a cell in which an anode and a cathode having an anode catalyst are stacked with a polymer film interposed therebetween, and generating power by a chemical reaction;
A fuel tank containing fuel;
A circulation system having a fuel flow path for circulating the fuel supplied from the fuel tank through the anode of the electromotive section, and a gas flow path for supplying air through the cathode of the electromotive section;
Replenishment means for supplying a catalyst solution of the anode catalyst to the anode and replenishing the anode catalyst to the anode;
A fuel cell device comprising:   2. The fuel cell device according to claim 1, wherein the replenishing unit contains a fuel mixed with a catalyst solution containing the anode catalyst and includes a replenishing tank connected to the fuel flow path.   The fuel cell device according to claim 2, wherein the replenishing tank is a detachable cartridge, and is provided so as to be connectable to the fuel flow path instead of the fuel tank.   The replenishing means detects the generated power of the electromotive unit, and stops the power generation operation of the electromotive unit when the generated power decreases to a predetermined value, and the catalyst solution is supplied from the replenishing tank to the anode. The fuel cell device according to claim 2, further comprising a control unit that supplies the mixed fuel for a predetermined time.   The replenishing means detects the generated power of the display unit and the electromotive unit, and when the generated power is reduced to a predetermined value, stops the power generation operation of the electromotive unit and instructs to install the replenishing tank. The fuel cell device according to claim 3, further comprising a control unit that displays the display unit.   2. The fuel cell device according to claim 1, wherein the replenishing unit stores a catalyst solution containing the anode catalyst and includes a replenishing tank connected to the electromotive unit.   The replenishment means detects the generated power of the electromotive unit, and stops the power generation operation of the electromotive unit when the generated power is reduced to a predetermined value, and also supplies the catalyst solution from the replenishment tank to the anode. The fuel cell device according to claim 6, further comprising a supply control unit.   The fuel cell device according to any one of claims 1 to 7, wherein the catalyst solution is a solution in which a noble metal compound is dissolved in pure water or a methanol aqueous solution. The noble metal compounds include ruthenium chloride hydrate (RuCl ₃ · xH ₂ O), osmium chloride hydrate (OsCl ₃ · xH ₂ O), palladium chloride (PdCl ₂ ), iridium chloride (InCl ₃ ), gold chloride (AuCl ₃ ). ₉ ) The fuel cell device according to claim 8, comprising any one of rhodium chloride hydrate (RhCl ₃ · xH ₂ O).

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