JP2008218046A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell in which output can be improved by realizing efficiency of power generation reaction by uniformalizing supply state of a fuel to a membrane electrode assembly without impairing small size or the like of the fuel cell. <P>SOLUTION: The fuel cell is provided with a fuel battery cell 2 having a membrane electrode assembly, a fuel supply mechanism 30 which is arranged on a fuel electrode side of the membrane electrode assembly and supplies a fuel to the fuel electrode, and a support plate 40 which is arranged between the membrane electrode assembly and the fuel supply mechanism and has an aperture for supplying the fuel to the fuel electrode, and supports the membrane electrode assembly from the fuel electrode side. The support plate 40 has a rib R in contact with the fuel supply mechanism, and a space SC for diffusing the fuel supplied from the fuel supply mechanism is formed between the support plate and the fuel supply mechanism. <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 can be said that the system is extremely advantageous as a power source for portable electronic devices.

  A 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 Documents 1 and 2). 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 Patent Documents 3 to 5). 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. However, depending on the supply structure of the liquid fuel from the flow path, the supply state of the fuel to the fuel cells may become uneven, and the output of the fuel cell may be reduced. For example, when the liquid fuel is caused to flow along the groove-like flow path, the fuel concentration is decreased on the flow path outlet side because the fuel is sequentially consumed as the liquid fuel flows through the flow path. For this reason, power generation reaction falls in the part near the channel outlet of a fuel cell, and as a result, the output falls.

Moreover, in patent document 3, the liquid fuel is supplied with a pump from a fuel accommodating part to a flow path. Patent Document 4 also describes using an electric field forming means for forming an electroosmotic flow in the flow path instead of the pump. Patent Document 5 describes that liquid fuel or the like is supplied using an electroosmotic flow pump. Although a pump is effective in a fuel cell to which a fuel circulation structure is applied, if the fuel is not circulated as in the case of a passive DMFC, even if the pump is applied, the fuel consumption will only increase and the entire fuel cell It is difficult to generate a uniform power generation reaction in
International Publication No. 2005/112172 Pamphlet JP 2006-318712 A JP 2005-518646 A JP 2006-089552 A US Patent Publication No. 2006/0029851

  The object of the present invention is to make the power supply reaction more efficient and improve the output by equalizing the fuel supply state to the membrane electrode assembly without impairing the miniaturization of the fuel cell. It is to provide a fuel cell.

The fuel cell according to the first aspect of the present invention comprises:
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 supply mechanism that is disposed on the fuel electrode side of the membrane electrode assembly and supplies fuel to the fuel electrode;
A support plate disposed between the membrane electrode assembly and the fuel supply mechanism, having an opening for supplying fuel to the fuel electrode, and supporting the membrane electrode assembly from the fuel electrode side; With
The support plate includes a rib in contact with the fuel supply mechanism, and a space for diffusing the fuel supplied from the fuel supply mechanism is formed between the support plate and the fuel supply mechanism. To do.

A fuel cell according to a second aspect of the present invention comprises:
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 mechanism disposed on the fuel electrode side of the membrane electrode assembly and supplying fuel to a plurality of locations of the fuel electrode;
A support plate disposed between the membrane electrode assembly and the fuel distribution mechanism, having an opening for supplying fuel to the fuel electrode, and supporting the membrane electrode assembly from the fuel electrode side;
It is provided with.

  According to the present invention, it is possible to improve the efficiency of the power generation reaction and improve the output by uniformizing the fuel supply state to the membrane electrode assembly without impairing the miniaturization of the fuel cell. A fuel cell can be provided.

  A fuel cell according to an embodiment of the present invention will be described below with reference to the drawings.

  First, the fuel battery cell 2 which comprises the electromotive part of the fuel battery 1 which concerns on this embodiment is demonstrated. For example, in the fuel cell 1 as shown in FIG. 1, 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 catalyst layer 14, and a cathode gas diffusion layer 15. And a cathode electrode (air electrode / oxidant electrode) 16 and a proton (hydrogen ion) conductive electrolyte membrane 17 sandwiched between the anode catalyst layer 11 and the cathode catalyst layer 14 ( Membrane Electrode Assembly (MEA).

  Examples of the catalyst contained in the anode catalyst layer 11 and the cathode catalyst layer 14 include platinum such as platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and palladium (Pd). Examples thereof include a group element simple substance and an alloy containing a platinum group element. For the anode catalyst layer 11, it is preferable to use Pt—Ru, Pt—Mo, or the like having strong resistance to methanol, carbon monoxide, or the like. Pt, Pt—Ni or the like is preferably used for 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 a sulfonic acid group, 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 mesh, a porous film, a thin film, or the like made of a conductive metal material such as gold (Au) is used.

(First embodiment)
Next, a first embodiment of the fuel cell 1 including the fuel cell 2 configured as described above will be described.

  As shown in FIG. 1, the fuel cell 1 includes a fuel cell 2, a fuel supply mechanism 30 that supplies fuel to the anode 13 of the fuel cell 2, and the fuel cell 2 and the fuel supply mechanism 30. It is mainly comprised from the support plate 40 arrange | positioned between and supporting the fuel cell 2 from the anode side.

  That is, the fuel battery cell 2 is held between the support plate 40 and the cover plate 18. The cover plate 18 has an opening 18A for taking in air as an oxidant. In the example shown in FIG. 1, the moisturizing layer 20 is disposed between the cover plate 18 and the cathode 16, but may be omitted. The moisturizing layer 20 has a function of impregnating a part of the water generated in the cathode catalyst layer 14 to suppress transpiration of water and promote uniform diffusion of air to the cathode catalyst layer 14. .

  Between the electrolyte membrane 17 and the cover plate 18 (between the electrolyte membrane 17 and the moisturizing layer 20 in the example shown in FIG. 1) and between the electrolyte membrane 17 and the support plate 40, rubber is used. A sealing material 19 such as an O-ring is interposed, and these prevent fuel leakage and oxidant leakage from the fuel cell 2.

  The fuel supply mechanism 30 is disposed on the anode (fuel electrode) 13 side of the fuel battery cell 2. The fuel supply mechanism 30 includes a fuel supply unit 31. The fuel supply mechanism 30 includes a fuel storage unit (not shown) that stores the liquid fuel supplied to the fuel supply unit 31. The fuel storage unit stores liquid fuel corresponding to the fuel battery cell 2, and examples of the liquid fuel include methanol fuels such as aqueous methanol solutions of various concentrations and pure methanol. The liquid fuel is not necessarily limited to methanol fuel. The liquid fuel 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 cell is used.

  The fuel supply unit 31 and the fuel storage unit are connected via a liquid fuel passage such as a pipe (not shown). That is, liquid fuel is introduced into the fuel supply unit 31 from the fuel storage unit via the flow path. The flow path is not limited to piping independent of the fuel supply unit 31 and the fuel storage unit. For example, when the fuel supply unit 31 and the fuel storage unit are stacked and integrated, a liquid fuel flow path connecting them may be used.

  The introduction of fuel from the fuel storage unit to the fuel supply unit 31 is performed using, for example, a pump. The pump is inserted in the middle of the flow path. The pump is not a circulation pump that circulates fuel, but is a fuel supply pump that sends liquid fuel from the fuel storage unit to the fuel supply unit 31 to the last. By supplying liquid fuel when necessary with such a pump, the controllability of the fuel supply amount can be improved.

  The fuel supplied from the fuel supply unit 31 to the fuel cells 2 is used for the power generation reaction, and is not circulated thereafter and returned to the fuel storage unit. Since the fuel cell of this embodiment does not circulate the fuel, it is different from the conventional active method and does not impair the downsizing of the apparatus. Further, the fuel cell uses a pump for supplying liquid fuel, and is different from a pure passive system such as a conventional internal vaporization type. For this reason, the fuel cell employs a system called a semi-passive system as described above.

  The type of pump is not particularly limited, but from the viewpoint that a small amount of liquid fuel can be sent with good controllability, and that further reduction in size and weight is possible, a rotary pump (rotary vane pump), electroosmotic flow pump, It is preferable to use a diaphragm pump, a squeezing pump or the like. 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.

  The pump is operated as necessary to supply liquid fuel from the fuel storage unit to the fuel supply unit 31. Thus, even when the liquid fuel is sent from the fuel storage unit to the fuel supply unit 31 by the pump, the fuel supply unit 31 functions effectively, so that the fuel supply amount to the fuel cells 2 can be made uniform. It becomes possible. In addition, if the fuel is supplied from the fuel supply unit 31 to the fuel battery cell 2, a fuel cutoff valve may be arranged instead of the pump. In this case, the fuel cutoff valve is provided to control the supply of liquid fuel through the flow path.

  As shown in FIGS. 1 and 2, the fuel supply unit 31 includes a fuel injection port 32 through which liquid fuel stored in a fuel storage unit (not shown) is injected through a flow path, and a fuel injection port 32. It has a fuel supply port 33 for supplying injected liquid fuel and its vaporized components, and a narrow tube 34 connecting the fuel injection port 32 and the fuel supply port 33. In the example of the fuel supply unit 31 shown here, the fuel injection port 32 and the fuel supply port 33 are each one place. In the fuel supply unit 31 having such a configuration, the surface 35 on which the fuel supply port 33 is formed, that is, the bottom surface 35 on which the support plate 40 is disposed is formed substantially flat.

  The support plate 40 has an opening AP for supplying the fuel supplied from the fuel supply mechanism 30 to the anode 13 of the fuel battery cell 2 in a state where the support plate 40 is disposed between the fuel battery cell 2 and the fuel supply mechanism 30. Have. That is, the opening AP is a through-hole penetrating from the fuel supply mechanism 30 side to the fuel cell 2 side in the support plate 40.

  Further, in the support plate 40, the surface 41 on the fuel cell 2 side is formed substantially flat as shown in FIG. On the other hand, the support plate 40 includes a rib R on the fuel supply mechanism 30 side as shown in FIG. That is, such a rib R protrudes from the back surface 42 of the support plate 40 facing the fuel supply mechanism 30 toward the fuel supply mechanism 30 side. For this reason, when the support plate 40 is disposed between the fuel battery cell 2 and the fuel supply mechanism 30, the rib R of the support plate 40 contacts the fuel supply mechanism 30, and the gap between the support plate 40 and the fuel supply mechanism 30. A space SC is formed. More specifically, the support plate 40 is disposed so that the back surface 42 faces the bottom surface 35 of the fuel supply unit 31. At this time, when the rib R is in contact with the bottom surface 35, a space SC is formed between the bottom surface 35 and the back surface 42.

  With such a configuration, the fuel supplied from the fuel supply port 33 of the fuel supply unit 31 can be diffused in the space SC. In particular, even in the configuration in which one fuel supply port 33 is formed on the bottom surface 35 of the fuel supply unit 31, it is sufficient to promote the vaporization of the liquid fuel supplied from the fuel supply port 33 in the space SC. The capacity can be secured, and the fuel in the gaseous state can be diffused over a wide range. For this reason, it becomes possible to supply a fuel toward the whole surface of the fuel battery cell 2, and it becomes possible to equalize the fuel supply amount to the fuel battery cell 2.

  In the fuel cell 1 configured as described above, power is generated by the following process.

  That is, the liquid fuel introduced from the fuel injection port 32 to the fuel supply unit 31 is guided to the fuel supply port 33 via the narrow tube 34. The liquid fuel supplied from the fuel supply port 33 is vaporized in the space SC with the support plate 40 and diffuses over a wide range. As a result, the vaporized component of the liquid fuel that has passed through the opening AP of the support plate 40 is supplied to the anode 13 of the fuel battery cell 2.

  In the fuel cell 2, the fuel diffuses through the anode gas diffusion layer 12 and is supplied to the anode catalyst layer 11. When methanol fuel is used as the liquid fuel, the internal reforming reaction of methanol shown in the following formula (1) occurs in the anode catalyst layer 11. When pure methanol is used as the methanol fuel, the water generated in the cathode catalyst layer 14 or the water in the electrolyte membrane 17 is reacted with methanol to cause the internal reforming reaction of the formula (1). Alternatively, the internal reforming reaction is caused by another reaction mechanism that does not require water.

CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (1)
Electrons (e ⁻ ) generated by this reaction are guided to the outside through a current collector, and are guided to the cathode 16 after operating a portable electronic device or the like as so-called electricity. Further, protons (H ⁺ ) generated by the internal reforming reaction of the formula (1) are guided to the cathode 16 through the electrolyte membrane 17. Air is supplied to the cathode 16 as an oxidant. Electrons (e ⁻ ) and protons (H ⁺ ) that have reached the cathode 16 react with oxygen in the air in the cathode catalyst layer 14 according to the following equation (2), and water is generated with this reaction.

6e ⁻ + 6H ⁺ + (3/2) O ₂ → 3H ₂ O (2)
In the power generation reaction of the fuel cell 1 described above, in order to increase the power to be generated, it is important to make the catalyst reaction smoothly and to make the entire electrode of the fuel cell 2 more effectively contribute to power generation.

  In contrast, in the case where there is one fuel supply port for supplying fuel to the fuel cell 2, the fuel concentration in the vicinity of the fuel supply port is sufficient for power generation. The fuel concentration decreases rapidly as it moves away from 33 toward the periphery. For this reason, the average output when viewed as a whole of the fuel cell remains at a low value due to the influence of the portion where the supply of fuel is small.

  As a means for increasing the fuel concentration, it is conceivable to increase the supply amount of the liquid fuel. However, when the supply amount of liquid fuel is simply increased, the fuel concentration in the vicinity of the fuel supply port increases too much, and a phenomenon called crossover occurs in which the fuel flows to the air electrode without reacting. The crossover causes a decrease in fuel consumption, a voltage decrease due to direct reaction of fuel at the air electrode, and a decrease in output due to this.

  In addition, an attempt has been made to form a groove through which liquid fuel flows on the surface in contact with the fuel electrode, and to allow the liquid fuel to flow through the groove, which has been put to practical use in large fuel cells. However, in this method, as the liquid fuel flows through the groove, the fuel is sequentially consumed by the reaction, so that the fuel concentration is reduced and the output reduction cannot be sufficiently suppressed. Further, conventionally, since a circulation pump is used to flow the fuel at a high speed, it is inevitable to increase the size of the apparatus.

  In the fuel cell 1 of the first embodiment, as described above, the space SC for diffusing the fuel is formed between the fuel cell 2 and the fuel supply port 33, so that the in-plane of the anode 13 is formed. The fuel distribution can be leveled, and the fuel required for the power generation reaction in the fuel cell 2 can be supplied as a whole without excess or deficiency. Therefore, it is possible to efficiently generate a power generation reaction in the fuel cell 2 without causing an increase in size or complexity of the fuel cell 1. As a result, the output of the fuel cell 1 can be improved. In other words, the output and its stability can be improved without impairing the advantages of the fuel cell 1 that does not circulate the fuel.

  In the fuel cell 1 according to the first embodiment, the fuel cell 2 is supported by the support plate 40 and the fuel cell 2 is held between the support plate 40 and the cover plate 18. It is possible to suppress deformation such as bending of the cell 2, particularly the membrane electrode assembly, and it is possible to increase the adhesion between the electromotive portion and the current collector to suppress a decrease in output.

  In the first embodiment described above, a more detailed structure of the rib R will be described. That is, as shown in FIG. 4, the rib R is arranged in an island shape on the inner side surrounded by the frame-shaped first rib R1 arranged along the outer periphery of the support plate 40 and the first rib R1. A plurality of second ribs R2. The first rib R1 and the second rib R2 are formed so as to have the same height from the back surface 42, and come into contact with the fuel supply mechanism 30 when disposed on the fuel supply mechanism 30.

  More specifically, when the support plate 40 is disposed on the bottom surface 35 of the fuel supply unit 31, both the first rib R <b> 1 and the second rib R <b> 2 are in contact with the bottom surface 35, and the back surface 42 of the support plate 40 extends from the bottom surface 35. It is separated. Since the second ribs R2 are scattered on the back surface 42, the space SC surrounded by the first rib R1, the bottom surface 35, and the back surface 42 is not partitioned by the second rib R2. That is, the space SC is a single common space corresponding to the fuel battery cell 2. For this reason, even if it is the structure which supplies a fuel from the fuel supply port 33 of one place, it becomes possible to equalize the supply amount of the fuel supplied with respect to the fuel cell 2.

  Further, as shown in FIG. 4, the seal material SE is disposed on the first rib R1. The seal material SE is made of rubber, for example, and is in close contact with the fuel supply mechanism 30. Thereby, it becomes possible to prevent fuel leakage.

  Next, a modification of the first embodiment will be described.

  In this modification, in addition to the fuel supply unit 31 as shown in FIG. 2, the fuel supply mechanism 30 further includes at least a fuel supply port 33 disposed between the fuel supply port 33 and the support plate 40. A single porous body is provided. Other configurations are the same as those of the first embodiment described above, and detailed description thereof is omitted.

  That is, as shown in FIG. 5, the fuel supply mechanism 30 includes a fuel supply unit 31 and a porous body 36 disposed on the bottom surface 35 of the fuel supply unit 31. As the constituent material of the porous body 36, various resins or fiber materials are used, and a porous resin film, fiber material, or the like is used as the porous body 36. The surface of the porous body 36, that is, the surface in contact with the support plate 40 is formed to be substantially flat.

  Also in such a modification, by applying the support plate 40 provided with the rib R on the fuel supply mechanism 30 side, when the support plate 40 is disposed between the fuel cell 2 and the fuel supply mechanism 30, The rib R of the support plate 40 is in contact with the fuel supply mechanism 30, and a space SC is formed between the support plate 40 and the fuel supply mechanism 30. More specifically, the support plate 40 is disposed such that the back surface 42 faces the porous body 36. At this time, a space SC is formed between the porous body 36 of the fuel supply mechanism 30 and the back surface 42 of the support plate 40 by the rib R being in contact with the porous body 36.

  By disposing such a porous body 36, the amount of fuel supplied to the anode 13 can be further averaged. That is, the liquid fuel supplied from the fuel supply port 33 of the fuel supply unit 31 is once absorbed by the porous body 36 and diffuses in the in-plane direction inside the porous body 36. Thereafter, fuel is supplied from the porous body 36 to the anode 13 via the space SC, so that the fuel supply amount can be further averaged.

  The porous body 36 may be arranged by laminating a plurality of porous films. That is, a porous body mainly having high diffusibility in one direction and a porous body having high diffusivity in a direction intersecting (or orthogonal to) the main body may be used in combination.

  According to the first embodiment described above, the fuel cell diffuses the liquid fuel supplied from the fuel supply mechanism in the space between the support plate supporting the fuel cell and the fuel supply mechanism, and the support plate Since the fuel cell is supplied from the opening, a power generation reaction can be efficiently generated in the entire membrane electrode assembly. This makes it possible to improve the output without impairing the miniaturization of the fuel cell.

(Second Embodiment)
Next, a second embodiment of the fuel cell 1 including the fuel cell 2 configured as described above will be described.

  As shown in FIG. 6, the fuel cell 1 according to the second embodiment includes a fuel cell 2, a fuel distribution mechanism 50 that supplies fuel to a plurality of locations of the anode 13 of the fuel cell 2, and a fuel cell. It is mainly comprised from the support plate 60 which is arrange | positioned between the cell 2 and the fuel distribution mechanism 50, and supports the fuel cell 2 from an anode side. In addition, about the structure same as 1st Embodiment, the same referential mark is attached | subjected and detailed description is abbreviate | omitted.

  The fuel cell 2 is held between the support plate 60 and the cover plate 18.

  The fuel distribution mechanism 50 disposed on the anode 13 side of the fuel cell 2 includes a fuel supply unit 51 and a fuel storage unit (not shown). As shown in FIGS. 6 and 7, the fuel supply unit 51 includes at least one fuel injection port 52 into which liquid fuel stored in a fuel storage unit (not shown) is injected through a flow path, A plurality of fuel supply ports 53 for supplying liquid fuel injected from the fuel injection port 52 and its vaporized components, and narrow tubes 54 connecting the fuel injection port 52 and each of the fuel supply ports 53 are provided. That is, one end (starting end) of the thin tube 54 corresponds to the fuel injection port 52. The narrow tube 54 is branched into a plurality of portions along the way, and each terminal portion of the branched thin tube 54 corresponds to the fuel supply port 53. The thin tube 34 is preferably a through hole having an inner diameter of 0.05 to 3 mm, for example.

  In the fuel distribution mechanism 50 having such a configuration, the liquid fuel injected from the fuel injection port 52 into the fuel supply unit 51 can be guided to the plurality of fuel supply ports 53 via the thin tubes 54 branched into a plurality of branches. Is possible. That is, by applying such a fuel distribution mechanism 50, the liquid fuel injected from the fuel injection port 52 can be evenly distributed to the plurality of fuel supply ports 53 regardless of the direction or position. Therefore, the uniformity of the power generation reaction in the plane of the fuel cell 2 can be further enhanced.

  Further, by connecting the fuel injection port 52 and the plurality of fuel supply ports 53 with the thin tubes 54, it is possible to design to supply more fuel to a specific location of the fuel cell 1. For example, in the case where the heat dissipation by half of the fuel cell 1 is improved due to the convenience of mounting the device, a temperature distribution is conventionally generated, and a decrease in average output is inevitable. On the other hand, by adjusting the formation pattern of the narrow tubes 54 and arranging the fuel supply ports 53 densely in advance in a portion where heat dissipation is good, heat generated by power generation in that portion can be increased. Thereby, the in-plane power generation degree can be made uniform, and it is possible to suppress a decrease in output.

  Further, in the fuel supply unit 51 having such a configuration, the surface on which the fuel supply port 53 is formed, that is, the bottom surface 55 on which the support plate 60 is disposed is formed substantially flat. According to the fuel cell 1 to which such a fuel distribution mechanism 50 is applied, it is possible to supply liquid fuel by diffusing, so that the support plate disposed between the fuel cell 2 and the fuel supply mechanism 30. 60 should just be comprised so that it may have a function which supports the fuel cell 2 at least.

  That is, in the state where this support plate 60 is disposed between the fuel cell 2 and the fuel distribution mechanism 50, the fuel supplied from the fuel distribution mechanism 50 is the same as the support plate 40 shown in FIGS. Is provided to the anode 13 of the fuel cell 2, while the rib 42 is not provided on the back surface 42. That is, since the fuel can be supplied by being diffused by the fuel distribution mechanism 50, the support plate 60 diffuses the fuel supplied from one fuel supply port 33 as in the example shown in FIG. It is not necessary to have a function of forming a space for making them.

  In such a fuel cell 1 of the second embodiment, the same effect as that of the first embodiment described above can be obtained.

  Of course, also in the second embodiment, the same support plate 40 as applied in the first embodiment can be applied. That is, as shown in FIG. 8, in Modification 1 of the second embodiment, the support plate 40 disposed between the fuel cell 2 and the fuel distribution mechanism 50 has a surface 41 on the fuel cell 2 side. While being formed to be substantially flat, a rib R is provided on the fuel distribution mechanism 50 side. For this reason, the rib R of the support plate 40 contacts the fuel distribution mechanism 50, and a space SC is formed between the support plate 40 and the fuel distribution mechanism 50. More specifically, the support plate 40 is disposed with the back surface 42 facing the bottom surface 55 of the fuel supply unit 51. At this time, when the rib R is in contact with the bottom surface 55, a space SC is formed between the bottom surface 55 and the back surface 42.

  With such a configuration, the fuel supplied from each fuel supply port 53 of the fuel supply unit 51 can be diffused in the space SC. That is, in the space SC, it is possible to secure a sufficient capacity to promote the vaporization of the liquid fuel supplied from each fuel supply port 53, and it is possible to diffuse the fuel in a gaseous state over a wide range. . For this reason, it becomes possible to supply a fuel toward the whole surface of the fuel battery cell 2, and it becomes possible to equalize the fuel supply amount to the fuel battery cell 2.

  Next, another modification of the second embodiment will be described.

  The fuel cell 1 according to the modified example 2 is disposed between the fuel supply port 53 of the fuel supply unit 51 constituting the fuel distribution mechanism 50 and the support plate 60 having no rib in the fuel cell 1 shown in FIG. And at least one porous body. That is, as shown in FIG. 9, the fuel distribution mechanism 50 includes a fuel supply unit 51 and a porous body 56 disposed on the bottom surface 55 of the fuel supply unit 51. As a constituent material of the porous body 56, various resins are used, and a porous resin film or the like is used as the porous body. The surface of the porous body 56, that is, the surface in contact with the support plate 60 is formed to be substantially flat.

  In the second modification, by applying the fuel distribution mechanism 50 including the plurality of fuel supply ports 53 and the porous body 56, it becomes possible to further improve the diffusibility of the fuel, and the fuel cell 2 It becomes possible to further average the amount of fuel supplied to the fuel.

  The fuel cell 1 according to the modified example 3 is disposed between the fuel supply port 53 of the fuel supply unit 51 constituting the fuel distribution mechanism 50 and the support plate 40 having the rib R in the fuel cell 1 shown in FIG. And at least one porous body. That is, as shown in FIG. 10, the fuel distribution mechanism 50 includes a fuel supply unit 51 and a porous body 56 disposed on the bottom surface 55 of the fuel supply unit 51.

  In the third modified example, the support plate 40 is disposed between the fuel cell 2 and the fuel distribution mechanism 50 by applying the fuel distribution mechanism 50 including the plurality of fuel supply ports 53 and the porous body 56. At this time, the rib R of the support plate 40 contacts the fuel distribution mechanism 50, and a space SC is formed between the support plate 40 and the fuel distribution mechanism 50. More specifically, the support plate 40 is arranged with the back surface 42 facing the porous body 56. At this time, the rib R is in contact with the porous body 56, so that a space SC is formed between the porous body 56 of the fuel distribution mechanism 50 and the back surface 42 of the support plate 40.

  For this reason, in addition to being able to further improve the diffusibility of the fuel, a sufficient capacity is secured in the space SC to promote the vaporization of the liquid fuel supplied from each fuel supply port 53. It is possible to diffuse a gaseous fuel over a wide range. For this reason, it becomes possible to further average the amount of fuel supplied to the fuel cells 2.

  Therefore, in any of the configurations of the first to third modifications of the second embodiment, the same effect as that of the first embodiment described above can be obtained.

  In the first embodiment and the second embodiment described above, the mechanism for sending the liquid fuel from the fuel storage unit to the fuel supply unit 31 is not particularly limited. For example, when the installation location at the time of use is fixed, the liquid fuel can be dropped from the fuel storage unit to the fuel supply unit 31 and fed using gravity. Further, by using a flow path filled with a porous body or the like, liquid can be fed from the fuel storage portion to the fuel supply portion 31 by a capillary phenomenon.

  Furthermore, liquid feeding from the fuel storage unit to the fuel supply unit 31 may be performed by a pump. In this case, for example, a configuration in which a pump is inserted in the middle of the flow path between the fuel storage unit and the fuel supply unit 31 is applicable. The pump in this case is not a circulation pump that circulates fuel, but a fuel supply pump that sends liquid fuel from the fuel storage unit to the fuel supply unit 31 to the last. By supplying liquid fuel when necessary with such a pump, the controllability of the fuel supply amount can be improved.

  The type of pump is not particularly limited, but a rotary vane pump, an electroosmotic pump, a diaphragm pump, It is preferable to use an ironing pump or the like. A rotary vane pump feeds liquid by rotating a wing with a motor. The electroosmotic flow pump uses a sintered porous material such as silica that causes an electroosmotic flow phenomenon. The diaphragm pump is a pump that feeds liquid by driving the diaphragm with an electromagnet or piezoelectric ceramics. The squeezing pump presses a part of the 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.

  When such a pump is applied, a control circuit for controlling the operation of the pump may be added. That is, it is preferable to control the fuel supply (liquid feeding) pump with reference to the output of the fuel cell 1. For this reason, the output of the fuel cell 1 is detected by the control circuit, and a control signal is sent from the control circuit to the pump based on the detection result. The pump is controlled to be turned on / off based on a control signal sent from the control circuit. More stable operation can be achieved by controlling the operation of the pump based on temperature information, operation state information of an electronic device that is a power supply destination, and the like in addition to the output of the fuel cell 1.

  Furthermore, in order to improve the stability and reliability of the fuel cell 1, a fuel cutoff valve may be arranged in series with the pump. In this case, a configuration in which a fuel cutoff valve is inserted in the flow path between the pump and the fuel supply unit 31 is applicable. However, even if the fuel cutoff valve is installed between the pump and the fuel supply unit 31, There is no hindrance. As the fuel cutoff valve, an electrically driven valve capable of controlling the opening / closing operation with an electric signal using an electromagnet, a motor, a shape memory alloy, piezoelectric ceramics, bimetal or the like as an actuator is used. As the fuel cutoff valve, it is preferable to use an electrically driven valve using an electromagnet or a piezoelectric ceramic from the viewpoint of its size, drive power and the like. Furthermore, it is preferable to use a latch type valve having a state maintaining function as the fuel cutoff valve.

  In addition, a balance valve that balances the pressure in the fuel storage portion with the outside air may be attached to the fuel storage portion or the flow path.

  According to the second embodiment described above, the fuel cell supplies the liquid fuel distributed and supplied by the fuel distribution mechanism to the fuel cell through the opening of the support plate that supports the fuel cell. The power generation reaction can be efficiently generated as a whole. This makes it possible to improve the output without impairing the miniaturization of the fuel cell.

  The fuel cell 1 of each embodiment described above is effective when various liquid fuels are used, and the type and concentration of the liquid fuel are not limited. The fuel cell 1 of each embodiment can particularly exhibit its performance and effects when methanol having a concentration of 80 wt% or more is used as the liquid fuel. Therefore, each embodiment is preferably applied to the fuel cell 1 using a methanol aqueous solution or pure methanol having a concentration of 80 wt% or more as a liquid fuel.

  The present invention can be applied to various fuel cells using liquid fuel. In addition, the specific configuration of the fuel cell, the supply state of the fuel, and the like are not particularly limited, and all of the fuel supplied to the MEA is liquid fuel vapor, all is liquid fuel, or part is liquid state. The present invention can be applied to various forms such as a vapor of supplied liquid fuel. 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 constituent elements shown in the above embodiment, or deleting some constituent elements from all the constituent elements 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.

FIG. 1 is a cross-sectional view schematically showing the configuration of the fuel cell according to the first embodiment of the present invention. FIG. 2 is a perspective view showing the structure of a fuel supply unit applicable to the fuel cell of the first embodiment. FIG. 3 is a perspective view showing the structure of the surface of the support plate applicable to the fuel cell according to the embodiment of the present invention. FIG. 4 is a perspective view showing the structure of the back surface of the support plate applicable to the fuel cell according to the embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing a configuration of a fuel cell according to a modified example of the first embodiment. FIG. 6 is a cross-sectional view schematically showing the configuration of the fuel cell according to the second embodiment of the present invention. FIG. 7 is a perspective view showing a structure of a fuel supply unit applicable to the fuel cell of the second embodiment. FIG. 8 is a cross-sectional view schematically showing a configuration of a fuel cell according to Modification 1 of the second embodiment. FIG. 9 is a cross-sectional view schematically showing a configuration of a fuel cell according to Modification 2 of the second embodiment. FIG. 10 is a cross-sectional view schematically showing a configuration of a fuel cell according to Modification 3 of the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell 2 ... Fuel cell 13 ... Anode 16 ... Cathode 17 ... Electrolyte membrane 18 ... Cover plate 30 ... Fuel supply mechanism 31 ... Fuel supply part 36 ... Porous body 40 ... Support plate AP ... Opening SE ... Sealing material R ... ribs (R1 ... first rib, R2 ... second rib) SC ... space 50 ... fuel distribution mechanism 60 ... support plate

Claims (12)

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 supply mechanism that is disposed on the fuel electrode side of the membrane electrode assembly and supplies fuel to the fuel electrode;
A support plate disposed between the membrane electrode assembly and the fuel supply mechanism, having an opening for supplying fuel to the fuel electrode, and supporting the membrane electrode assembly from the fuel electrode side; With
The support plate includes a rib in contact with the fuel supply mechanism, and a space for diffusing the fuel supplied from the fuel supply mechanism is formed between the support plate and the fuel supply mechanism. Fuel cell.   The rib includes a frame-shaped first rib disposed along the outer periphery of the support plate, and a plurality of second ribs disposed in an island shape on the inner side surrounded by the first rib. The fuel cell according to claim 1, wherein   The fuel cell according to claim 2, wherein a sealing material is disposed on the first rib.   2. The fuel supply mechanism according to claim 1, further comprising a fuel supply unit having a fuel injection port through which fuel is injected and a fuel supply port through which fuel injected from the fuel injection port is supplied to the fuel electrode. 2. The fuel cell according to 1.   The fuel cell according to claim 4, wherein the fuel supply mechanism further includes at least one porous body disposed between the fuel supply port of the fuel supply unit and the support plate. 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 mechanism disposed on the fuel electrode side of the membrane electrode assembly and supplying fuel to a plurality of locations of the fuel electrode;
A support plate disposed between the membrane electrode assembly and the fuel distribution mechanism, having an opening for supplying fuel to the fuel electrode, and supporting the membrane electrode assembly from the fuel electrode side;
A fuel cell comprising:   The support plate includes a rib in contact with the fuel distribution mechanism, and a space for diffusing the fuel supplied from the fuel distribution mechanism is formed between the support plate and the fuel distribution mechanism. The fuel cell according to claim 6.   The fuel distribution mechanism includes a fuel supply unit having a fuel injection port into which fuel is injected and a plurality of fuel supply ports for supplying fuel injected from the fuel injection port to the fuel electrode. The fuel cell according to claim 6 or 7.   The fuel cell according to claim 8, wherein the fuel distribution mechanism further includes at least one porous body disposed between the fuel supply port of the fuel supply unit and the support plate. Furthermore, an exterior case disposed on the air electrode of the membrane electrode assembly,
The fuel cell according to any one of claims 1 to 9, wherein the membrane electrode assembly is held between the support plate and the cover plate.   The fuel cell according to claim 1, wherein the fuel is methanol fuel.   The fuel cell according to claim 11, wherein the methanol fuel is a methanol aqueous solution or pure methanol having a methanol concentration of 80 wt% or more.

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