JP2008210679A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of improving output by preventing fuel from being discharged without going through a fuel battery cell, and supplying the fuel uniformly to the fuel battery cell. <P>SOLUTION: The fuel cell 1 is provided with the fuel battery cell 2 having a membrane electrode assembly 2 constructed of an anode 13, a cathode 16, and an electrolyte membrane 17 interposed between these. Furthermore, the fuel cell 1 is provided with a fuel distribution layer 30 having a plurality of apertures 31 provided opposed to the fuel battery cell 2, and the fuel supplied from a fuel supply mechanism 40 is supplied to the fuel battery cell 2 through the apertures 31. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell using liquid fuel.

  In recent years, attempts have been made to use a fuel cell as a power source for portable electronic devices such as notebook computers and mobile phones so that they can be used for a long time without being charged. A fuel cell is characterized in that it can generate electric power simply by supplying fuel and air, and can generate electric power continuously for a long time if fuel is replenished. For this reason, if the fuel cell can be reduced in size, it becomes a very advantageous system as a power source for portable electronic devices.

  The direct methanol fuel cell (DMFC) is promising as a power source for portable electronic devices because it can be miniaturized and the fuel can be easily handled. As the liquid fuel supply method in the DMFC, there are known an active method such as a gas supply type and a liquid supply type, and a passive method such as an internal vaporization type in which the liquid fuel in the fuel container is vaporized inside the cell and supplied to the fuel electrode. It has been.

  Among these, a passive system such as an internal vaporization type is particularly advantageous for downsizing of the DMFC. In the passive DMFC, for example, a structure is proposed in which a membrane electrode assembly (fuel cell) having a fuel electrode, an electrolyte membrane, and an air electrode is disposed on a fuel containing portion made of a resin box-like container ( For example, see Patent Document 1.) When the fuel vaporized from the fuel container is directly supplied to the fuel cell, it is important to improve the output controllability of the fuel cell, but the current passive DMFC does not always have sufficient output controllability. .

  On the other hand, it has been studied to connect a fuel cell of DMFC and a fuel storage part via a flow path (see, for example, Patent Documents 2-4). By supplying the liquid fuel supplied from the fuel storage unit to the fuel cell via the flow path, the supply amount of the liquid fuel can be adjusted based on the shape and diameter of the flow path. Patent Document 3 describes a fuel cell that supplies liquid fuel by a pump from a fuel storage portion to a flow path, and Patent Document 4 describes a fuel cell that supplies liquid fuel or the like using an electroosmotic flow pump. ing.

In the above-described conventional fuel cell, the liquid retaining sheet is impregnated with the supplied liquid fuel, and vaporized fuel is supplied to the fuel electrode side of the fuel cell through the opening provided in the fuel adjustment film and the fuel diffusion film. A fuel cell is disclosed (for example, see Patent Document 5).
International Publication No. 2005/112172 Pamphlet JP 2005-518646 A JP 2006-089552 A US Patent Publication No. 2006/0029851 JP 2006-196430 A

  In the conventional fuel cell described above, vaporized fuel is supplied to the fuel electrode side of the fuel cell through the opening provided in the fuel adjustment film. This opening has a uniform fuel concentration and the fuel electrode. To the side. For this reason, the fuel adjustment film is provided with an opening so that the fuel concentration is uniform, and therefore the opening is not necessarily provided at a position corresponding to the fuel electrode of the fuel cell. That is, an opening may be provided at a position not corresponding to the fuel electrode of the fuel cell, and the vaporized fuel that has passed through the opening is discharged without being supplied to the fuel cell. .

  Accordingly, the present invention has been made to solve the above-described problems, and prevents the fuel from being discharged without passing through the fuel cell, and by supplying the fuel to the fuel cell uniformly, the output It is an object of the present invention to provide a fuel cell capable of improving the efficiency.

  According to one aspect of the present invention, a membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode, and a fuel electrode side of the membrane electrode assembly A fuel distribution layer having a plurality of openings provided at positions opposed to the fuel electrode, and disposed on a side different from the fuel electrode side of the fuel distribution layer, and supplying liquid fuel to the fuel distribution layer There is provided a fuel cell, comprising: a fuel supply mechanism configured to store the liquid fuel; and a fuel storage unit connected to the fuel supply mechanism via a flow path.

  According to the fuel cell of the present invention, it is possible to improve the output by preventing the fuel from being discharged without passing through the fuel cell and uniformly supplying the fuel to the fuel cell.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of a fuel cell according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the fuel cell when the pump 80 is provided in the fuel cell of one embodiment. FIG. 3 is a perspective view showing the configuration of the fuel supply mechanism 40. FIG. 4 is a plan view showing the configuration of the fuel distribution layer 30. FIG. 5 is a cross-sectional view showing the configuration of the fuel cell including the fuel diffusion layer 70 in the fuel cell according to the embodiment of the present invention. FIG. 6 is a cross-sectional view showing a configuration of a fuel cell including a fuel supply mechanism of another configuration in the fuel cell of the first embodiment.

  As shown in FIG. 1, the fuel cell 1 includes a fuel cell 2 constituting an electromotive unit, a fuel distribution layer 30 having a plurality of openings 31 provided to face the fuel cell 2, A fuel supply mechanism 40 that supplies liquid fuel F to the fuel distribution layer 30, a fuel storage unit 50 that stores the liquid fuel F, and a fuel supply mechanism that are disposed on a side different from the fuel cell 2 side of the fuel distribution layer 30. 40 and the fuel storage part 50 are mainly provided.

  The fuel cell 2 includes an anode (fuel electrode) 13 having an anode catalyst layer 11 and an anode gas diffusion layer 12, a cathode (air electrode) 16 having a cathode catalyst layer 14 and a cathode gas diffusion layer 15, and an anode catalyst. It has a membrane electrode assembly (MEA) composed of an electrolyte membrane 17 having proton (hydrogen ion) conductivity sandwiched between the layer 11 and the cathode catalyst layer 14.

  Examples of the catalyst contained in the anode catalyst layer 11 and the cathode catalyst layer 14 include a simple substance of a platinum group element such as Pt, Ru, Rh, Ir, Os, and Pd, and an alloy containing the platinum group element. As the anode catalyst layer 11, for example, Pt—Ru, Pt—Mo, or the like having strong resistance to methanol, carbon monoxide, or the like is preferably used. For example, Pt or Pt—Ni is preferably used as the cathode catalyst layer 14. However, the catalyst is not limited to these, and various substances having catalytic activity can be used. The catalyst may be either a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst.

  Examples of the proton conductive material constituting the electrolyte membrane 17 include a fluorine-based resin (Nafion (trade name, manufactured by DuPont) or Flemion (trade name, manufactured by Asahi Glass Co., Ltd.) such as a perfluorosulfonic acid polymer having a sulfonic acid group. Etc.), organic materials such as hydrocarbon resins having sulfonic acid groups, or inorganic materials such as tungstic acid and phosphotungstic acid. However, the proton conductive electrolyte membrane 17 is not limited to these.

  The anode gas diffusion layer 12 laminated on the anode catalyst layer 11 serves to uniformly supply fuel to the anode catalyst layer 11 and also serves as a current collector for the anode catalyst layer 11. The cathode gas diffusion layer 15 laminated on the cathode catalyst layer 14 serves to uniformly supply the oxidant to the cathode catalyst layer 14 and also serves as a current collector for the cathode catalyst layer 14. The anode gas diffusion layer 12 and the cathode gas diffusion layer 15 are made of a porous substrate.

  A conductive layer is laminated on the anode gas diffusion layer 12 and the cathode gas diffusion layer 15 as necessary. As these conductive layers, for example, a thin film, mesh, porous film or the like made of a conductive metal material such as Au is used. Among these, it is preferable that the conductive layer is formed of a thin film having a plurality of openings opened corresponding to the fuel cells 2, and faces the fuel cells 2 through the openings. The fuel from the opening 31 of the provided fuel distribution layer 30 is guided to the fuel cell 2. Further, rubber O-rings 19 are interposed between the electrolyte membrane 17 and the fuel distribution layer 30 and the cover plate 18, respectively, thereby preventing fuel leakage and oxidant leakage from the fuel cell 2. ing.

  Although not shown, the cover plate 18 has an opening for taking in air as an oxidizing agent. A moisture retaining layer and a surface layer are disposed between the cover plate 18 and the cathode 16 as necessary. The moisturizing layer is impregnated with a part of the water generated in the cathode catalyst layer 14 to suppress the transpiration of water and promote uniform diffusion of air to the cathode catalyst layer 14. The surface layer adjusts the amount of air taken in, and has a plurality of air inlets whose number, size, etc. are adjusted according to the amount of air taken in.

  The fuel storage unit 50 stores liquid fuel F corresponding to the fuel battery cell 2. Examples of the liquid fuel F include methanol fuels such as methanol aqueous solutions having various concentrations and pure methanol. The liquid fuel F is not necessarily limited to methanol fuel. The liquid fuel F may be, for example, an ethanol fuel such as an ethanol aqueous solution or pure ethanol, a propanol fuel such as a propanol aqueous solution or pure propanol, a glycol fuel such as a glycol aqueous solution or pure glycol, dimethyl ether, formic acid, or other liquid fuel. In any case, liquid fuel corresponding to the fuel cells 2 is stored in the fuel storage unit 50.

  The fuel supply mechanism 40 is connected to the fuel storage unit 50 via the flow path 60 of the liquid fuel F configured by piping or the like. Liquid fuel F is introduced into the fuel supply mechanism 40 from the fuel storage unit 50 via the flow path 60. The flow path 60 is not limited to piping independent of the fuel supply mechanism 40 and the fuel storage unit 50. For example, when the fuel supply mechanism 40 and the fuel storage unit 50 are laminated and integrated, a flow path of the liquid fuel F that connects them may be used. The fuel supply mechanism 40 only needs to communicate with the fuel storage unit 50 through a flow path or the like.

  The liquid fuel F accommodated in the fuel accommodating part 50 can be dropped and sent to the fuel supply mechanism 40 via the flow path 60 using gravity. Alternatively, the flow path 60 may be filled with a porous body or the like, and the liquid fuel F stored in the fuel storage unit 50 may be fed to the fuel supply mechanism 40 by capillary action. Further, as shown in FIG. 2, the liquid fuel F accommodated in the fuel accommodating portion 50 may be forcibly fed to the fuel supply mechanism 40 by interposing a pump 80 in a part of the flow path 60. The pump 80 functions as a supply pump that simply supplies the liquid fuel F from the fuel storage unit 50 to the fuel supply mechanism 40, and is a circulation pump that circulates excess liquid fuel F supplied to the fuel cells 2. It does not have the function as. Since the fuel cell provided with the pump 80 does not circulate the fuel, the configuration is different from the conventional active method, and the configuration is different from the pure passive method such as the conventional internal vaporization method. It corresponds to. The type of the pump 80 is not particularly limited, but a rotary vane pump, an electroosmotic flow pump can be used from the viewpoint that a small amount of liquid fuel F can be fed with good controllability and can be reduced in size and weight. It is preferable to use a diaphragm pump, a squeezing pump or the like. The rotary vane pump feeds liquid by rotating wings with a motor. The electroosmotic flow pump uses a sintered porous body such as silica that causes an electroosmotic flow phenomenon. A diaphragm pump drives a diaphragm with an electromagnet or piezoelectric ceramics to send liquid. The squeezing pump presses a part of a flexible fuel flow path and squeezes the fuel. Among these, it is more preferable to use an electroosmotic pump or a diaphragm pump having piezoelectric ceramics from the viewpoint of driving power, size, and the like.

  Further, if the fuel is supplied from the fuel supply mechanism 40 to the fuel cell 2, a fuel cutoff valve may be arranged instead of the pump 80. This fuel cutoff valve is provided to control the supply of liquid fuel through the flow path.

  Further, as shown in FIG. 3, the fuel supply mechanism 40 includes at least one fuel inlet 41 through which the liquid fuel F flows through the flow path 60, and a fuel outlet through which the liquid fuel F and its vaporized components are discharged. And a fuel supply plate 43 having 42. Further, as shown in FIG. 1, the fuel injection port 41 and the fuel discharge port 42 are communicated with each other by a narrow flow path 45. Further, the fuel distribution layer 30 may be disposed directly on the fuel discharge port 42, but as shown in FIG. 3, the supplied liquid fuel F is introduced into the region corresponding to the fuel distribution layer 30 of the fuel supply plate 43. It is preferable to form a recess 44 for evenly spreading. When the fuel distribution layer 30 is laminated on the fuel supply plate 43 to configure the fuel cell 1, the concave portion 44 becomes a gap, and in addition to the function of spreading the liquid fuel F uniformly corresponding to the fuel distribution layer 30, It also functions as a flow path and buffer for the liquid fuel F. The liquid fuel F introduced into the fuel supply plate 43 from the fuel inlet 41 passes through the flow path 45, is guided to the recess 44 from the fuel outlet 42, and spreads evenly in a region corresponding to the fuel distribution layer 30. As a result, the liquid fuel F and the vaporized fuel vaporized from the liquid fuel F are uniformly supplied to the fuel distribution layer 30.

  The fuel distribution layer 30 is provided on the anode (fuel electrode) 13 side of the fuel cell 2 and is sandwiched between the fuel supply mechanism 40 and the fuel cell 2 described above. The fuel distribution layer 30 is made of a material that does not allow the vaporized component of the liquid fuel F or the liquid fuel F to permeate. Specifically, for example, a polyethylene terephthalate (PET) resin, a polyethylene naphthalate (PEN) resin, or a polyimide resin. Etc.

  Further, as shown in FIG. 4, the fuel distribution layer 30 has a plurality of openings 31 provided so as to face the fuel cells 2. The opening 31 is preferably provided corresponding to the shape of the anode gas diffusion layer 12 so that fuel can be supplied over the entire area of the anode gas diffusion layer 12 of the fuel cell 2. For example, when the fuel cell 2 is vertically long and the anode gas diffusion layer 12 has a vertically long shape, a plurality of openings are formed along the longitudinal direction of the anode gas diffusion layer 12 corresponding to the vertically long shape. It is preferable to provide the part 31. The arrangement configuration of the openings 31 shown in FIG. 4 is an example of the arrangement configuration when four vertically long fuel cells 2 are provided. In this case, the fuel cells 2 are arranged along the respective rows in the openings 31 provided in the four rows. As a result, the opening 31 does not exist in a region where the fuel cell 2 is not disposed. In other words, all the openings 31 face the fuel battery cell 2, and the fuel discharged from the openings 31 is all supplied to the anode gas diffusion layer 12 of the fuel battery cell 2. Here, an example is shown in which a plurality of openings 31 are provided at a predetermined interval in one row for one fuel cell 2, but in two or more rows for one fuel cell 2. A plurality of openings 31 may be provided at predetermined intervals.

  Moreover, the opening area of the opening 31 may be the same, or when the number of the fuel discharge port 42 of the fuel supply mechanism 40 is one, the opening area may be changed depending on the position where the opening 31 is formed. For example, when there is one fuel discharge port 42, the difference in fuel supply amount, that is, the fuel supply amount in the vicinity of the fuel discharge port 42 is large and the fuel supply amount in the distance is small, in other words, the fuel discharge port 42 In order to avoid the difference in the fuel concentration that the fuel concentration of the fuel that has passed through the opening 31 around 42 is high and the fuel concentration of the fuel that has passed through the opening 31 farther than that decreases, Centering on 42, the opening area of the opening 31 may be gradually increased as the distance from the center increases. In addition, although the shape of the opening part 31 is not specifically limited, For example, you may form circularly, a triangle, a rectangle, a polygon, etc., or a slit shape.

  Here, the ratio of the total opening area obtained by adding the opening areas of all the openings 31 to the area of the plane when the openings 31 are not formed, that is, the opening ratio of all the openings 31 is 3 to 15%. It is preferable to do. Here, it is preferable to set the aperture ratio within this range because when the aperture ratio is less than 3%, the fuel necessary for power generation cannot be sufficiently supplied, and the output is reduced. This is because when the amount exceeds 50%, the fuel becomes excessive, the heat generation of the fuel cell increases, and the output decreases. Here, the area of the plane when the opening 31 is not formed is the same area as the opposing fuel cell, and when a plurality of fuel cells are arranged, adjacent fuel cells An area equivalent to the maximum area of the fuel cell array configuration including the area between the two.

  Next, the operation of the fuel cell 1 described above will be described.

The liquid fuel F supplied from the fuel storage unit 50 to the fuel supply mechanism 40 via the flow path 60 remains as a liquid fuel, or in a state where liquid fuel and vaporized fuel vaporized from the liquid fuel are mixed. To be supplied to the anode gas diffusion layer 12 of the fuel battery cell 2. The fuel supplied to the anode gas diffusion layer 12 is diffused in the anode gas diffusion layer 12 and supplied to the anode catalyst layer 11. When methanol fuel is used as the liquid fuel, an internal reforming reaction of methanol represented by the following formula (1) occurs in the anode catalyst layer 11.
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ Formula (1)

  When pure methanol is used as the methanol fuel, is methanol reformed by water generated in the cathode catalyst layer 14 or water in the electrolyte membrane 17 and the internal reforming reaction of the above formula (1)? Or other reaction mechanisms that do not require water.

Electrons (e ⁻ ) generated by this reaction are guided to the outside through a current collector, and are operated to a cathode (air electrode) 16 after operating a portable electronic device or the like as so-called electricity. Proton (H ⁺ ) generated by the internal reforming reaction of the formula (1) is guided to the cathode 16 through the electrolyte membrane 17. Air is supplied to the cathode 16 as an oxidant. The electrons (e ⁻ ) and protons (H ⁺ ) that have reached the cathode 16 cause a reaction shown in the following equation (2) with oxygen in the air at the cathode catalyst layer 14, and water is generated along with this power generation reaction. .
(3/2) O ₂ + 6e ⁻ + 6H ⁺ → 3H ₂ O Formula (2)

  By supplying the fuel of the uniform predetermined concentration to the whole fuel cell 2 by the fuel distribution layer 30 described above, the above-described internal reforming reaction is smoothly performed, and the fuel cell 1 has a high output and a stable output. Can be obtained in

  According to the fuel cell 1 according to the embodiment of the present invention described above, the plurality of openings 31 provided to face the fuel cell 2 are provided between the fuel supply mechanism 40 and the fuel cell 2. By providing the fuel distribution layer 30, the fuel discharged from the opening 31 is supplied to the anode gas diffusion layer 12 of the opposing fuel cell 2. In other words, all the fuel discharged from the opening 31 is supplied to the anode gas diffusion layer 12 of the fuel cell 2. As a result, it is possible to prevent the fuel from being discharged without passing through the fuel battery cell 2, and the fuel can be used effectively.

  Further, the opening 31 of the fuel distribution layer 30 is provided corresponding to the shape of the anode gas diffusion layer 12 so that fuel can be supplied over the entire area of the anode gas diffusion layer 12 of the fuel cell 2. The entire area of the anode catalyst layer 11 can be used effectively, and a fuel cell with high output and stable output can be obtained. Further, by discharging the fuel from the plurality of openings 31 provided in the fuel distribution layer 30, it is possible to supply the fuel with a uniform concentration over the entire area of the anode gas diffusion layer 12. As a result, a fuel cell having a stable output can be obtained.

  The configuration of the fuel cell 1 is not limited to the above-described embodiment, and can be variously changed without departing from the gist thereof.

  For example, as shown in FIG. 5, a fuel diffusion layer 70 may be provided between the fuel supply plate 43 of the fuel supply mechanism 40 and the fuel distribution layer 30. The fuel diffusion layer 70 is made of a hydrophilic material that can be impregnated with the liquid fuel F. Specific examples of the material constituting the fuel diffusion layer 70 include porous materials such as foamed polyethylene and polyurethane, nonwoven fabrics, and woven fabrics such as polyester. In addition, as a specific material constituting the fuel diffusion layer 70, a material that is permeable to gaseous methanol can be cited. A specific material constituting the fuel diffusion layer 70 is, for example, silicone rubber. The liquid fuel F supplied from the fuel discharge port 42 is impregnated in the fuel diffusion layer 70 and diffuses uniformly into the fuel diffusion layer 70. The vaporized fuel obtained by vaporizing the liquid fuel F is supplied to the anode gas diffusion layer 12 of the fuel cell 2 from the plurality of openings 31 provided in the fuel distribution layer 30. In this case, even if the recess 44 is not provided in the fuel supply plate 43, the fuel diffusion layer 70 can achieve uniform fuel distribution.

  As described above, by providing the fuel diffusion layer 70, the fuel can be evenly distributed, and more uniformly throughout the anode gas diffusion layer 12 of the fuel cell 2 via the fuel distribution layer 30. It is possible to supply a fuel with a proper concentration.

  Further, as shown in FIG. 6, the fuel supply plate 43 may be provided with a plurality of fuel discharge ports 42 communicating with the fuel injection port 21 via the flow path 45. This makes it easier for the liquid fuel F to spread more uniformly in the recess 44. Also in this case, the same configuration as the fuel diffusion layer 70 described above may be provided between the fuel supply plate 43 of the fuel supply mechanism 40 and the fuel cell 2. In the case where the fuel diffusion layer is provided, even if the fuel supply plate 43 is not provided with the recess 44, the fuel diffusion layer can achieve uniform dispersion of the fuel.

  Next, it will be described based on Examples 1 to 5 and Comparative Examples 1 to 2 that the fuel cell according to the present invention has excellent output characteristics.

(Example 1)
FIG. 7 is a plan view showing the configuration of the fuel distribution layer 100 used in the fuel cell of Example 1. FIG. In FIG. 7, the arrangement positions of the fuel cells arranged corresponding to the openings 101 of the fuel distribution layer 100 are indicated by dotted lines.

  In the first embodiment, as shown in FIG. 7, a fuel cell having a fuel distribution layer 100 having four rows of apertures each having 15 apertures 101 each having a diameter of 2 mm arranged in a row at a predetermined interval. Was made. The opening ratio of all openings 101 in the fuel distribution layer 100 was 6%. Further, similarly to the fuel cell 1 shown in FIG. 1, a fuel distribution layer 100 is provided between the fuel supply plate of the fuel supply mechanism and the fuel cells. The shape of the fuel cell 2 was 50 mm × 120 mm, and pure methanol was used as the liquid fuel. Further, an electroosmotic pump is interposed in a part of the passage communicating with the fuel storage portion of the fuel cell and the fuel supply mechanism, and the liquid fuel stored in the fuel storage portion is forcibly sent to the fuel supply mechanism.

  Using the fuel cell described above, changes in output characteristics were measured when power generation was continuously performed at a constant voltage for 1000 hours under an environment of a temperature of 25 ° C. and a relative humidity of 50%. Then, the output value after the lapse of 10 hours was calculated, and the relative output value when the output value after the lapse of the same time of the fuel cell in Comparative Example 1 described later was set to 100 was obtained. Further, the output maintenance rate after 1000 hours was calculated. The output maintenance ratio is a ratio of the output after 1000 hours to the output immediately after the start of power generation, that is, a value obtained by dividing the output after 1000 hours by the output immediately after the start of power generation in percentage. As a result of the measurement, the relative output value was 121, and the output maintenance rate was 89.5%.

(Example 2)
The fuel cell used in Example 2 is the same as that in Example 1 except that a fuel diffusion layer is provided between the fuel supply plate of the fuel supply mechanism and the fuel distribution layer in the fuel cell used in Example 1. 1 is the same as that of the fuel cell used in 1. As the fuel diffusion layer, a foamed polyethylene material (porosity 30%) having a thickness of 0.3 mm was used.

  Further, the measurement method and measurement conditions for the relative output value and the output retention rate are the same as the measurement method and measurement conditions in Example 1. As a result of the measurement, the relative output value was 129, and the output maintenance ratio was 93.7%.

(Example 3)
The fuel cell used in Example 3 is the same as the above example except that the shape of the opening 101 of the fuel distribution layer 100 used in Example 2 is a 1.8 mm × 1.8 mm rectangular opening. The configuration of the fuel cell used in 2 is the same. The opening ratio of all openings in the fuel distribution layer was 6%.

  Further, the measurement method and measurement conditions for the relative output value and the output retention rate are the same as the measurement method and measurement conditions in Example 1. As a result of the measurement, the relative output value was 131, and the output maintenance rate was 93.1%.

Example 4
In the fuel cell used in Example 4, instead of the fuel distribution layer 100 used in Example 2, seven openings each having a diameter of 3 mm are provided in a row at predetermined intervals. The fuel cell has the same configuration as that of the fuel cell used in Example 2 except that a fuel distribution layer having four rows is used. The opening ratio of all openings in the fuel distribution layer was 6%.

  Further, the measurement method and measurement conditions for the relative output value and the output retention rate are the same as the measurement method and measurement conditions in Example 1. As a result of the measurement, the relative output value was 125, and the output maintenance rate was 90.4%.

(Example 5)
The fuel cell used in the fifth embodiment is the same as the fuel supply mechanism 40 shown in FIG. 6 in the fuel cell used in the second embodiment, that is, the fuel supply plate 43 has a fuel inlet 21. The configuration of the fuel cell used in the second embodiment is the same as that of the second embodiment except that a plurality of fuel discharge ports 42 communicating with each other via the flow path 45 are provided.

  Further, the measurement method and measurement conditions for the relative output value and the output retention rate are the same as the measurement method and measurement conditions in Example 1. As a result of the measurement, the relative output value was 133, and the output maintenance rate was 94.1%.

(Comparative Example 1)
FIG. 8 is a plan view showing the configuration of the fuel distribution layer 200 used in the fuel cell of Comparative Example 1. FIG. In FIG. 8, the arrangement positions of the fuel cells arranged with respect to the fuel distribution layer 200 are indicated by dotted lines. The fuel cell used in Comparative Example 1 is the fuel cell used in Example 1 described above except that the fuel distribution layer 200 shown in FIG. 8 is used instead of the fuel distribution layer 100 used in Example 1. The configuration is the same.

  In Comparative Example 1, as shown in FIG. 8, four opening rows each having 10 openings 201 each having a diameter of 2 mm provided in a row at a predetermined interval are provided, and further, between these opening rows. A fuel distribution layer 200 provided with an opening row in which seven openings 202 each having a diameter of 2 mm were provided in a row at predetermined intervals was produced. In addition, the opening row | line | column comprised by the opening part 202 is not provided in the position facing the fuel cell. The opening ratio of all openings (all openings 201 and 202) in the fuel distribution layer 200 was 6%.

  Further, the measurement method and measurement conditions for the relative output value and the output retention rate are the same as the measurement method and measurement conditions in Example 1. As a result of the measurement, the relative output value was 100, and the output maintenance ratio was 80.2%.

(Comparative Example 2)
The fuel cell used in Comparative Example 2 is the same as that of the fuel cell used in Comparative Example 1, except that a fuel diffusion layer is provided between the fuel supply plate of the fuel supply mechanism and the fuel distribution layer. 1 is the same as that of the fuel cell used in 1. As the fuel diffusion layer, a foamed polyethylene material (porosity 30%) having a thickness of 0.3 mm was used.

  Further, the measurement method and measurement conditions for the relative output value and the output retention rate are the same as the measurement method and measurement conditions in Example 1. As a result of the measurement, the relative output value was 105, and the output maintenance ratio was 82.3%.

(Summary of Examples 1 to 5 and Comparative Examples 1 to 2)
Table 1 shows the measurement results of the relative output value and the output retention rate in Examples 1 to 5 and Comparative Examples 1 to 2.

  From the measurement results of the relative output values and output retention rates in Examples 1 to 5 and Comparative Examples 1 and 2 described above, both the relative output values and the output retention rates in Examples 1 to 5 are both Comparative Example 1. A value higher than the relative output value and the output retention rate in Comparative Example 2 was obtained. From this result, when a fuel distribution layer provided with a plurality of openings facing the fuel cells is used (Examples 1 to 5), the fuel is discharged without passing through the fuel cells. Therefore, it is considered that a higher value than the case of Comparative Example 1 and Comparative Example 2 was obtained together with the relative output value and the output retention rate.

  Further, from the results in Example 1 and Example 2, the case where the fuel diffusion layer is provided between the fuel supply plate and the fuel distribution layer of the fuel supply mechanism is relatively less than the case where the fuel diffusion layer is not provided. It was found that high values were obtained for both the output value and the output maintenance rate.

  The present invention can be applied to various fuel cells using liquid fuel. Further, the specific configuration of the fuel cell, the supply state of the fuel, etc. are not particularly limited. All of the fuel supplied to the fuel cell is liquid fuel vapor, all is liquid fuel, or part is liquid. The present invention can be applied to various forms such as liquid fuel vapor supplied in a state. In the implementation stage, the constituent elements can be modified and embodied without departing from the technical idea of the present invention. Furthermore, various modifications are possible, such as appropriately combining a plurality of components shown in the above embodiment, or deleting some components from all the components shown in the embodiment. Embodiments of the present invention can be expanded or modified within the scope of the technical idea of the present invention, and these expanded and modified embodiments are also included in the technical scope of the present invention.

Sectional drawing which shows the structure of the fuel cell of one Embodiment which concerns on this invention. Sectional drawing which shows the structure of the fuel cell at the time of providing the pump in the fuel cell of one Embodiment which concerns on this invention. The perspective view which shows the structure of a fuel supply mechanism. The top view which shows the structure of a fuel distribution layer. In the fuel cell of one Embodiment concerning this invention, sectional drawing which shows the structure of a fuel cell provided with a fuel diffusion layer. Sectional drawing which shows the structure of a fuel cell provided with the fuel supply mechanism of another structure in the fuel cell of 1st Embodiment. FIG. 2 is a plan view showing a configuration of a fuel distribution layer used in the fuel cell of Example 1. FIG. 3 is a plan view showing a configuration of a fuel distribution layer used in the fuel cell of Comparative Example 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Fuel cell, 11 ... Anode catalyst layer, 12 ... Anode gas diffusion layer, 13 ... Anode (fuel electrode), 14 ... Cathode catalyst layer, 15 ... Cathode gas diffusion layer, 16 ... Cathode (air) Electrode), 17 ... electrolyte membrane, 19 ... O-ring, 30 ... fuel distribution layer, 40 ... fuel supply mechanism, 41 ... fuel inlet, 42 ... fuel outlet, 43 ... fuel supply plate, 45, 60 ... flow path, 50: Fuel container, F: Liquid fuel.

Claims (7)

A membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A fuel distribution layer disposed on the fuel electrode side of the membrane electrode assembly and having a plurality of openings provided at positions facing the fuel electrode;
A fuel supply mechanism that is disposed on a side different from the fuel electrode side of the fuel distribution layer and supplies liquid fuel to the fuel distribution layer;
A fuel cell comprising: a fuel storage unit configured to store the liquid fuel and connected to the fuel supply mechanism via a flow path.   The fuel supply mechanism includes a fuel supply plate having a fuel inlet through which the liquid fuel flows through the flow path, and a fuel discharge port connected to the fuel inlet through a fuel passage. The fuel cell according to claim 1.   The opening area of the opening of the fuel distribution layer increases as the distance from the fuel discharge port of the fuel supply mechanism provided on the side different from the fuel electrode side of the fuel distribution layer increases. The fuel cell according to claim 1 or 2.   The fuel supply mechanism includes a fuel supply plate having a fuel inlet through which the liquid fuel flows through the flow path, and a plurality of fuel outlets connected to the fuel inlet through a fuel passage. The fuel cell according to claim 1.   The fuel cell according to any one of claims 1, 2, and 4, wherein the opening of the fuel distribution layer is formed with the same opening area.   The fuel according to any one of claims 1 to 5, further comprising a fuel diffusion layer provided on the fuel distribution layer on a side different from the fuel electrode side, the fuel diffusion layer being stacked on the fuel distribution layer. battery.   The fuel cell according to any one of claims 1 to 6, wherein the liquid fuel is an aqueous methanol solution or pure methanol.

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