JP2007149564A - Fuel cell - Google Patents

Abstract

The amount of vaporized fuel supplied to a membrane electrode assembly can be adjusted without changing the thickness of the fuel cell, and the amount of vaporized fuel supplied without changing the components of the electromotive unit. It is an object of the present invention to provide a fuel cell that can optimize the above.
An electromotive portion composed of a fuel electrode, an air electrode, and an electrolyte membrane 15 sandwiched between the fuel electrode and the air electrode, and provided on each surface of the fuel electrode and the air electrode of the electromotive portion. A liquid fuel tank 21 disposed on the fuel electrode side of the electromotive layer and containing the liquid fuel F and having an opening for deriving a vaporized component of the liquid fuel F; and an opening portion of the liquid fuel tank 21 The fuel supply amount adjustment layer 22 that adjusts the amount of vaporized component passing from the liquid fuel tank 21, and the fuel supply amount adjustment layer 22 is disposed between the fuel supply amount adjustment layer 22 and the conductive layer. The gas-liquid separation membrane 23 which permeate | transmits the vaporization component from is comprised.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell, and more particularly to a small passive fuel cell.

  In recent years, advances in electronic technology have led to downsizing, higher performance, and portability of electronic devices. In portable electronic devices, there is an increasing demand for higher energy density of batteries used. For this reason, there is a demand for a secondary battery having a high capacity while being lightweight and small.

  Under such circumstances, small fuel cells are attracting attention. In particular, direct methanol fuel cells (DMFC) using methanol as a fuel require more difficult handling of hydrogen gas and devices that produce hydrogen by reforming organic fuel compared to fuel cells using hydrogen gas. It is thought that it is excellent in miniaturization.

  In DMFC, methanol is oxidatively decomposed at the fuel electrode to generate carbon dioxide, protons and electrons. On the other hand, in the air electrode, water is generated by oxygen obtained from air, protons supplied from the fuel electrode through the electrolyte membrane, and electrons supplied from the fuel electrode through an external circuit. In addition, power is supplied by electrons passing through the external circuit.

In DMFCs, miniaturization is promoted by providing a gas-liquid separation membrane that permeates methanol molecules between the fuel tank and the membrane electrode assembly that is the electromotive unit, for example, and bringing the fuel tank close to the electromotive unit. (For example, refer to Patent Document 1). For intake of air, a small DMFC has been constructed by installing an intake port directly attached to the membrane electrode assembly.
Japanese Patent No. 3413111

  However, in the conventional small DMFC, when the mechanism is simplified, it is difficult to keep the amount of methanol supplied to the membrane electrode assembly constant when affected by external environmental factors such as temperature. Therefore, it may be difficult to stably maintain the battery output. It is also conceivable to change the supply amount of methanol by changing a laminate such as a gas-liquid separation membrane that permeates methanol molecules. For example, if the thickness in the vicinity of the gas-liquid separation membrane is changed, the thickness of the DMFC changes, and there is a problem that a DMFC having a predetermined thickness cannot be configured. In addition, the thickness of the gas-liquid separation membrane is changed, so that there is a problem that the sealing performance is lowered and the fuel and the oxidant leak.

  Therefore, the present invention has been made to solve the above problems, and it is possible to adjust the amount of vaporized fuel supplied to the membrane electrode assembly without changing the thickness of the fuel cell. Fuel that can optimize the amount of vaporized fuel supplied without changing the components of the electromotive unit when the output of the battery is different or when a fuel cell with a different electromotive unit area is required An object is to provide a battery.

  In order to achieve the above object, a fuel cell according to the present invention includes a fuel electrode, an air electrode, and an electromotive part composed of an electrolyte membrane sandwiched between the fuel electrode and the air electrode. Conductive layers provided on the respective surfaces of the fuel electrode and the air electrode, and openings provided on the fuel electrode side of the electromotive portion for accommodating the liquid fuel and deriving a vaporized component of the liquid fuel A fuel supply unit, a fuel supply amount adjustment layer that is disposed in an opening of the fuel supply unit and adjusts the amount of the vaporized component passing from the fuel supply unit, the fuel supply amount adjustment layer, and the conductive layer. And a gas-liquid separation membrane that permeates the vaporized component from the fuel supply amount adjustment layer.

  According to this fuel cell, by providing the fuel supply amount adjustment layer, a predetermined amount of vaporized component of the liquid fuel vaporized in the fuel supply unit can be supplied to the gas-liquid separation membrane side without being affected by external environmental factors such as temperature. And can be supplied to the fuel electrode.

  According to the fuel cell of the present invention, it is possible to adjust the supply amount of vaporized fuel supplied to the membrane electrode assembly without changing the thickness of the fuel cell. When a fuel cell having a different electrical area is required, the supply amount of vaporized fuel can be optimized without changing the components of the electromotive part.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram schematically showing a cross section of a direct methanol fuel cell 10 according to an embodiment of the present invention.

  As shown in FIG. 1, a fuel cell 10 includes a fuel electrode composed of a fuel electrode catalyst layer 11 and a fuel electrode gas diffusion layer 12, an air electrode composed of an air electrode catalyst layer 13 and an air electrode gas diffusion layer 14, and a fuel electrode. A membrane electrode assembly (MEA) 16 composed of a proton (hydrogen ion) conductive electrolyte membrane 15 sandwiched between the catalyst layer 11 and the air electrode catalyst layer 13 is configured as an electromotive unit. is doing.

  Examples of the catalyst contained in the fuel electrode catalyst layer 11 and the air electrode catalyst layer 13 include, for example, platinum group elements such as Pt, Ru, Rh, Ir, Os, and Pd, as well as alloys containing platinum group elements. And so on. Specifically, Pt—Ru or Pt—Mo having strong resistance to methanol or carbon monoxide is used as the fuel electrode catalyst layer 11, and platinum or Pt—Ni is used as the air electrode catalyst layer 13. Although preferable, it is not limited to these. Further, a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst may be used.

  Examples of the proton conductive material that constitutes the electrolyte membrane 15 include fluorinated resins having a sulfonic acid group, such as perfluorosulfonic acid polymer (Nafion (trade name, manufactured by DuPont), Flemion (trade name, Asahi Glass Co., Ltd.)), hydrocarbon resins having a sulfonic acid group, and inorganic substances such as tungstic acid and phosphotungstic acid, but are not limited thereto.

  The fuel electrode gas diffusion layer 12 stacked on the fuel electrode catalyst layer 11 serves to uniformly supply the fuel to the fuel electrode catalyst layer 11 and also serves as a current collector for the fuel electrode catalyst layer 11. Yes. On the other hand, the air electrode gas diffusion layer 14 laminated on the air electrode catalyst layer 13 serves to uniformly supply the oxidant to the air electrode catalyst layer 13 and at the same time functions as a current collector of the air electrode catalyst layer 13. Also has. A fuel electrode conductive layer 17 is stacked on the fuel electrode gas diffusion layer 12, and an air electrode conductive layer 18 is stacked on the air electrode gas diffusion layer 14. The fuel electrode conductive layer 17 and the air electrode conductive layer 18 are formed of a porous layer such as a mesh made of a conductive metal material such as gold. The fuel electrode conductive layer 17 and the air electrode conductive layer 18 are configured so that fuel and oxidant do not leak from their peripheral edges.

  The fuel electrode sealing material 19 has a rectangular frame shape, is positioned between the fuel electrode conductive layer 17 and the electrolyte membrane 15, and surrounds the fuel electrode catalyst layer 11 and the fuel electrode gas diffusion layer 12. On the other hand, the air electrode sealing material 20 has a rectangular frame shape, is positioned between the air electrode conductive layer 18 and the electrolyte membrane 15, and surrounds the air electrode catalyst layer 13 and the air electrode gas diffusion layer 14. Yes. The fuel electrode sealing material 19 and the air electrode sealing material 20 are composed of, for example, a rubber O-ring or the like, and prevent fuel leakage and oxidant leakage from the membrane electrode assembly 16. Note that the shapes of the fuel electrode sealing material 19 and the air electrode sealing material 20 are not limited to the rectangular frame shape, and are appropriately configured to correspond to the outer edge shape of the fuel cell 10.

  Further, as shown in FIG. 1, a gas-liquid separation membrane 23 is laminated on the fuel supply amount adjustment layer 22 disposed so as to cover the opening of the liquid fuel tank 21 that stores the liquid fuel F. On the gas-liquid separation membrane 23, a frame 24 (here, a rectangular frame) configured in a shape corresponding to the outer edge shape of the fuel cell 10 is disposed. The membrane electrode assembly 16 including the fuel electrode conductive layer 17 and the air electrode conductive layer 18 is laminated and disposed so that the fuel electrode conductive layer 17 is in contact with one surface of the frame 24.

  The vaporized fuel storage chamber 25 surrounded by the fuel electrode conductive layer 17, the gas-liquid separation film 23, and the frame 24 temporarily stores the vaporized component of the liquid fuel F that has permeated through the gas-liquid separation film 23. It functions as a space that makes the fuel concentration distribution in the vaporized component uniform. Here, the frame 24 is made of an electrically insulating material, and is specifically formed of a thermoplastic polyester resin such as polyethylene terephthalate (PET). The fuel supply amount adjustment layer 22 and the gas-liquid separation membrane 23 are configured so that fuel or the like does not leak from their peripheral edges.

  The fuel supply amount adjustment layer 22 is for adjusting the amount of vaporized component of the liquid fuel F vaporized in the liquid fuel tank 21 through the gas-liquid separation film 23. FIG. 2 is a plan view of a specific fuel supply amount adjustment layer 22. As shown in FIG. 2, the fuel supply amount adjustment layer 22 is made of a material that does not allow the vaporized component of the liquid fuel F or the liquid fuel F to permeate, is formed in a thin plate shape, and has a plurality of passage holes 22a. Specific materials for forming the fuel supply amount adjusting layer 22 include, for example, thermoplastic polyester resins such as polyethylene terephthalate (PET), polyimide resins, and the like. In addition, the thickness of the fuel supply amount adjustment layer 22 is preferably in the range of 100 to 200 μm. This thickness range is preferable because when the thickness is less than 100 μm, the assembly accuracy at the time of lamination becomes difficult. When the thickness is greater than 200 μm, the thickness of the entire cell increases, Moreover, it is because a sealing performance falls.

  The opening area of the passage holes 22a is set so that the amount of vaporized components passing through all the passage holes 22a is 20 to 70% of the amount of vaporized components of the liquid fuel F vaporized in the liquid fuel tank 21. . Here, the amount of vaporized component passing through all the passage holes 22a is set to the above range when the amount of vaporized component is smaller than 20% of the amount of vaporized component of the liquid fuel F vaporized in the liquid fuel tank 21. This is because sufficient fuel necessary for power generation is not supplied, and when it is larger than 70%, surplus fuel that does not contribute to power generation is supplied.

  The perforation pattern of the passage holes 22a is not limited to the perforation pattern shown in FIG. 2, and a predetermined amount of vaporized components of the liquid fuel F vaporized in the liquid fuel tank 21 are uniformly distributed on the gas-liquid separation membrane 23 side. Any pattern may be used so long as it is allowed to pass through.

  The gas-liquid separation membrane 23 separates the vaporized component of the liquid fuel F and the liquid fuel F, and allows the vaporized component to permeate the fuel electrode catalyst layer 11 side. Specifically, the gas-liquid separation membrane 23 is made of a material such as silicone rubber or fluororesin.

  Here, the liquid fuel stored in the liquid fuel tank 21 is an aqueous methanol solution having a concentration exceeding 50 mol% or pure methanol. The purity of pure methanol is preferably 95% by weight or more and 100% by weight or less. The vaporized component of liquid fuel means vaporized methanol when liquid methanol is used as the liquid fuel, and vaporized component of methanol and water when aqueous methanol solution is used as the liquid fuel. It means an air-fuel mixture consisting of components.

  On the other hand, a moisturizing layer 27 is laminated on the air electrode conductive layer 18 via a frame 26 (here, a rectangular frame) configured in a shape corresponding to the outer edge shape of the fuel cell 10. On the moisturizing layer 27, a surface layer 28 in which a plurality of air introduction ports 29 for taking in air as an oxidant is formed is laminated. The surface layer 28 also serves to pressurize the laminated body including the membrane electrode assembly 16 and enhance its adhesion, and is formed of a metal such as SUS304, for example. Similarly to the frame 24 described above, the frame 26 is made of an electrically insulating material. Specifically, the frame 26 is formed of, for example, a thermoplastic polyester resin such as polyethylene terephthalate (PET).

  The moisturizing layer 27 impregnates part of the water generated in the air electrode catalyst layer 13 to suppress water evaporation, and uniformly introduces an oxidant into the air electrode gas diffusion layer 14. Therefore, it also has a function as an auxiliary diffusion layer that promotes uniform diffusion of the oxidant into the air electrode catalyst layer 13. The moisturizing layer 27 is made of, for example, a material such as a polyethylene porous film. Here, the movement of water from the air electrode catalyst layer 13 side to the fuel electrode catalyst layer 11 side due to the osmotic pressure phenomenon changes the number and size of the air inlets 29 of the surface layer 28 installed on the moisturizing layer 27. It can be controlled by adjusting the opening area and the like.

  Next, the operation of the fuel cell 10 described above will be described.

The liquid fuel (for example, aqueous methanol solution) in the liquid fuel tank 21 is vaporized, and a predetermined amount of the vaporized mixture of methanol and water vapor passes through the passage hole 22 a of the fuel supply amount adjustment layer 22. The air-fuel mixture that has passed through the passage hole 22a passes through the gas-liquid separation membrane 23, and is once stored in the vaporized fuel storage chamber 25, so that the concentration distribution is made uniform. The air-fuel mixture once stored in the vaporized fuel storage chamber 25 passes through the fuel electrode conductive layer 17, is further diffused in the fuel electrode gas diffusion layer 12, and is supplied to the fuel electrode catalyst layer 11. The air-fuel mixture supplied to the fuel electrode catalyst layer 11 causes an internal reforming reaction of methanol represented by the following formula (1).
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ Formula (1)

  Note that when pure methanol is used as the liquid fuel, there is no supply of water vapor from the liquid fuel tank 21, so that water generated in the air electrode catalyst layer 13, water in the electrolyte membrane 15 and the like are described as methanol. The internal reforming reaction of the formula (1) is generated, or the internal reforming reaction is generated by another reaction mechanism that does not require water, regardless of the internal reforming reaction of the above formula (1).

Protons (H ⁺ ) generated by the internal reforming reaction are conducted through the electrolyte membrane 15 and reach the air electrode catalyst layer 13. The air taken in from the air inlet 29 of the surface layer 28 diffuses through the moisturizing layer 27, the air electrode conductive layer 18, and the air electrode gas diffusion layer 14 and is supplied to the air electrode catalyst layer 13. The air supplied to the air electrode catalyst layer 13 causes the reaction shown in the following formula (2). By this reaction, water is generated and a power generation reaction occurs.
(3/2) O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O Formula (2)

  The water generated in the air electrode catalyst layer 13 by this reaction diffuses in the air electrode gas diffusion layer 14 and reaches the moisturizing layer 27, and a part of the water in the surface layer 28 provided on the moisturizing layer 27. Although transpiration is conducted from the air inlet 29, the remaining water is inhibited from transpiration by the surface layer 28. In particular, when the reaction of formula (2) proceeds, the amount of water whose transpiration is inhibited by the surface layer 28 increases, and the amount of water stored in the air electrode catalyst layer 13 increases. In this case, the water storage amount of the air electrode catalyst layer 13 becomes larger than the water storage amount of the fuel electrode catalyst layer 11 as the reaction of the formula (2) proceeds. As a result, a reaction in which water generated in the air electrode catalyst layer 13 moves to the fuel electrode catalyst layer 11 through the electrolyte membrane 15 by the osmotic pressure phenomenon is promoted. Therefore, as compared with the case where the supply of moisture to the fuel electrode catalyst layer 11 is dependent only on water vapor evaporated from the liquid fuel tank 21, the supply of moisture is promoted, and the internal reforming reaction of methanol in the above-described equation (1) is performed. Can be promoted. As a result, the output density can be increased and the high output density can be maintained for a long period of time.

  Further, even when a methanol aqueous solution with a methanol concentration exceeding 50 mol% or pure methanol is used as the liquid fuel, the water that has moved from the air electrode catalyst layer 13 to the fuel electrode catalyst layer 11 is used for the internal reforming reaction. Therefore, it is possible to stably supply water to the fuel electrode catalyst layer 11. Thereby, the reaction resistance of the internal reforming reaction of methanol can be further reduced, and the long-term output characteristics and load current characteristics can be further improved. Further, the liquid fuel tank 21 can be downsized.

  As described above, according to the direct methanol fuel cell 10 of the embodiment, the vaporization in the liquid fuel tank 21 is achieved by adjusting the area of the passage hole 22a and the perforation pattern of the fuel supply amount adjustment layer 22. A predetermined amount of vaporized component of the liquid fuel F can be passed to the gas-liquid separation membrane 23 side. Accordingly, since a predetermined amount of vaporized component of the liquid fuel F can be supplied to the fuel electrode without being affected by external environmental factors such as temperature, a stable battery output can be obtained.

  Further, by adjusting the area of the passage holes 22a and the perforation pattern of the fuel supply amount adjustment layer 22, the amount of vaporized component of the liquid fuel F to be passed can be adjusted, so that the thickness of the fuel cell 10 changes. There is no. As a result, sealing properties and the like can be maintained, the occurrence of leakage of fuel, oxidant, and the like can be prevented, and an advantage that a predetermined thickness can be maintained can be obtained.

  In each of the above embodiments, a direct methanol fuel cell using a methanol aqueous solution or pure methanol as the liquid fuel has been described. However, the liquid fuel is not limited to these. For example, ethanol fuel such as ethanol aqueous solution or pure ethanol, dimethyl ether, formic acid, or other liquid fuel may be used. In any case, liquid fuel corresponding to the fuel cell is accommodated.

  Further, in order to obtain a predetermined battery output, a plurality of fuel cells 10 shown in FIG. 1 are arranged in parallel, and the fuel cells 10 are electrically connected in series to constitute a fuel cell. In this case, for example, it can be configured to share one liquid fuel tank 21.

  Next, it will be described in the following examples that excellent output characteristics can be obtained by providing the fuel cell 10 with the fuel supply amount adjustment layer 22.

Example 1
The fuel cell according to the present invention used in Example 1 was produced as follows. FIG. 3 is a plan view of a fuel supply amount adjusting layer having a plurality of passage holes used in the first embodiment.

  First, a perfluorocarbon sulfonic acid solution, water and methoxypropanol were added to platinum-supported carbon black, and the platinum-supported carbon black was dispersed to prepare a paste. The obtained paste was applied to porous carbon paper which is an air electrode gas diffusion layer. And this was dried at normal temperature and the air electrode which consists of an air electrode catalyst layer and an air electrode gas diffusion layer was produced.

  A perfluorocarbon sulfonic acid solution, water and methoxypropanol were added to carbon particles carrying platinum ruthenium alloy fine particles, and the carbon particles were dispersed to prepare a paste. The obtained paste was applied to porous carbon paper which is a fuel electrode gas diffusion layer. And this was dried at normal temperature and the fuel electrode which consists of a fuel electrode catalyst layer and a fuel electrode gas diffusion layer was produced.

As the electrolyte membrane, a perfluorocarbon sulfonic acid membrane having a thickness of 80 μm (Nafion membrane, manufactured by DuPont) was used. MEA) was prepared. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  Subsequently, the membrane electrode assembly was sandwiched between gold foils having a plurality of perforations for taking in air and vaporized methanol to form a fuel electrode conductive layer and an air electrode conductive layer.

  A laminate in which the above-described membrane electrode assembly (MEA), fuel electrode conductive layer, and air electrode conductive layer were laminated was sandwiched between two resin-made frames. A rubber O-ring was sandwiched between the electrolyte membrane and the fuel electrode conductive layer, and between the electrolyte membrane and the air electrode conductive layer, respectively.

  Also, the laminated body sandwiched between two frames is fixed to the liquid fuel tank by screwing through a fuel supply amount adjustment layer and a gas-liquid separation membrane laminated so that the liquid fuel tank side becomes the fuel supply amount adjustment layer did. At this time, the laminate was fixed so that the fuel electrode side of the membrane electrode assembly (MEA) was on the gas-liquid separation membrane side.

  For the fuel supply amount adjustment layer, a polyethylene terephthalate (PET) sheet having a thickness of 100 μm was used, and through holes having a hole diameter of 3 mm were evenly drilled at 9 locations (3 vertical × 3 horizontal). In this case, the amount of vaporized component passing through all the passage holes was 40% of the amount of vaporized component of the liquid fuel vaporized in the liquid fuel tank. In addition, a silicone sheet having a thickness of 100 μm was used for the gas-liquid separation membrane.

  On the other hand, a porous plate was disposed on the air electrode side frame to form a moisture retention layer. Further, a surface layer is formed by placing a stainless steel plate (SUS304) having a thickness of 2 mm on which an air inlet (air diameter: 3 mm, number of holes: 50) for air intake is formed on the moisture retaining layer. Fixed with a stop.

10 ml of pure methanol was injected into the liquid fuel tank of the fuel cell formed as described above, and the maximum value of the output was measured by changing the current value in an environment of a temperature of 25 ° C. and a relative humidity of 50%. Then, the relative maximum output value was obtained when the maximum output value in Comparative Example 1 described later was 100. Further, the thickness of the fuel cell was measured, and the relative thickness of the fuel cell was determined when the thickness of the fuel cell in Comparative Example 1 described later was 100.
As a result of the measurement, the maximum value of the relative output was 140. The relative fuel cell thickness was 100.

(Example 2)
The fuel cell used in Example 2 uses a polyethylene terephthalate (PET) sheet having a thickness of 100 μm for the fuel supply amount adjustment layer, and has a passage hole (4 vertical × 3 horizontal) having a hole diameter of 3 mm. The configuration of the fuel cell used in Example 1 is the same as that of Example 1 except that 12 holes are evenly drilled. In this case, the amount of vaporized component passing through all the passage holes was 60% of the amount of vaporized component of the liquid fuel vaporized in the liquid fuel tank.

The measurement method and measurement conditions for the maximum output value and the thickness of the fuel cell are the same as the measurement method and measurement conditions in Example 1.
As a result of the measurement, the maximum relative output was 120. The relative fuel cell thickness was 100.

(Example 3)
The fuel cell used in Example 3 uses a polyimide sheet with a thickness of 100 μm for the fuel supply amount adjustment layer, and has nine passage holes with a diameter of 3 mm (3 vertical × 3 horizontal). The configuration of the fuel cell used in Example 1 is the same as that of Example 1 except that it is perforated. In this case, the amount of vaporized component passing through all the passage holes was 40% of the amount of vaporized component of the liquid fuel vaporized in the liquid fuel tank.

The measurement method and measurement conditions for the maximum output value and the thickness of the fuel cell are the same as the measurement method and measurement conditions in Example 1.
As a result of the measurement, the maximum value of the relative output was 140. The relative fuel cell thickness was 100.

(Comparative Example 1)
The fuel cell used in Comparative Example 1 did not have a fuel supply amount adjustment layer, and was used in Example 1 described above except that a 100 μm thick silicone sheet was used for the gas-liquid separation membrane. The configuration is the same as that of the fuel cell.

The measurement method and measurement conditions for the maximum output value and the thickness of the fuel cell are the same as the measurement method and measurement conditions in Example 1.
Here, as described above, the maximum value of the output measured in Comparative Example 1 was set to 100, and the thickness of the fuel cell was set to 100.

(Comparative Example 2)
The fuel cell used in Comparative Example 2 did not have a fuel supply amount adjustment layer and was used in Example 1 described above except that a 100 μm thick silicone sheet was used for the gas-liquid separation membrane. The configuration is the same as that of the fuel cell.

The measurement method and measurement conditions for the maximum output value and the thickness of the fuel cell are the same as the measurement method and measurement conditions in Example 1.
As a result of the measurement, the maximum relative output was 120. The relative fuel cell thickness was 110.

(Examination of measurement results of Examples and Comparative Examples)
As described above, the maximum output value in Examples 1 to 3 using the fuel cell according to the present invention was higher than the maximum output value in Comparative Example 1 and Comparative Example 2. From this result, it was found that excellent output characteristics can be obtained by providing the fuel supply amount adjustment layer. Further, as is clear from the comparison of the results of Example 2 and Comparative Example 2, by providing the fuel supply amount adjustment layer, the thickness of the gas-liquid separation membrane is doubled without increasing the thickness of the fuel cell. It was found that the maximum output value equivalent to that of Comparative Example 2 in which the fuel permeation amount was adjusted could be obtained.

  Therefore, it is possible to adjust the amount of vaporized fuel supplied to the membrane electrode assembly without changing the thickness of the fuel cell, and when the required battery output is different or the fuel cell has a different electromotive part area It has been found that the supply amount of the vaporized fuel can be optimized without changing the constituent members of the electromotive unit, for example. Therefore, it has been found that there is no need to change the overall structure of the fuel cell such as a seal structure.

1 is a cross-sectional view of a direct methanol fuel cell according to an embodiment. The top view of a fuel supply amount adjustment layer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Fuel electrode catalyst layer, 12 ... Fuel electrode gas diffusion layer, 13 ... Air electrode catalyst layer, 14 ... Air electrode gas diffusion layer, 15 ... Electrolyte membrane, 16 ... Membrane electrode assembly, 17 ... Fuel Electrode conductive layer, 18 ... Air electrode conductive layer, 19 ... Fuel electrode sealing material, 20 ... Air electrode sealing material, 21 ... Liquid fuel tank, 22 ... Fuel supply amount adjusting layer, 22a ... Passing hole, 23 ... Gas-liquid separation membrane 24, 26 ... Frame, 25 ... Vaporized fuel storage chamber, 27 ... Moisturizing layer, 28 ... Surface layer, 29 ... Air inlet.

Claims (4)

An electromotive part composed of a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A conductive layer provided on each surface of the fuel electrode and the air electrode of the electromotive unit;
A fuel supply unit disposed on the fuel electrode side of the electromotive unit, containing liquid fuel and having an opening for deriving a vaporized component of the liquid fuel;
A fuel supply amount adjusting layer that is disposed in an opening portion of the fuel supply unit and adjusts a passing amount of the vaporized component from the fuel supply unit;
A fuel cell comprising: a gas-liquid separation membrane disposed between the fuel supply amount adjustment layer and the conductive layer and allowing the vaporized component from the fuel supply amount adjustment layer to pass therethrough.   2. The fuel cell according to claim 1, wherein the fuel supply amount adjusting layer is formed of a sheet-like member having a plurality of perforations.   3. The fuel cell according to claim 1, wherein the fuel supply amount adjustment layer is formed of a material that is impermeable to the vaporized component.   3. The fuel cell according to claim 2, wherein the plurality of perforations are formed so as to pass 20 to 70% of the vaporized component amount of the liquid fuel vaporized in the fuel supply unit.

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