JP5062392B2 - Polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a fuel cell using a liquid fuel such as methanol as a fuel, and more particularly to a planar stack type solid polymer fuel cell in which a plurality of power generating elements are arranged on the same plane.

  A solid polymer fuel cell is composed of an electrode-electrolyte assembly (hereinafter referred to as MEA) having a structure in which a solid polymer electrolyte membrane is sandwiched between a fuel electrode and an oxidant electrode. In this device, hydrogen, alcohol, or the like is supplied as a fuel, and air or oxygen is supplied to the oxidant electrode to cause an electrochemical reaction, thereby extracting electric power.

Among solid polymer fuel cells, a type of fuel cell that supplies liquid fuel such as alcohol directly to the fuel electrode without reforming is called a direct fuel cell. For example, in a direct methanol fuel cell (hereinafter referred to as DMFC) using an aqueous methanol solution as a liquid fuel, power is generated by a cell reaction represented by the following chemical formulas 1 to 3, and therefore carbon dioxide is generated on the fuel electrode side. To do.
(Chemical formula 1); Fuel electrode: CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻
(Chemical formula 2); Oxidant electrode: 6H ⁺ + 6e ⁻ + 3 / 2O ₂ → 3H ₂ O
(Chemical formula 3); Battery reaction: CH ₃ OH + 3 / 2O ₂ → CO ₂ + 2H ₂ O

The fuel in contact with the fuel electrode is decomposed by the action of catalyst particles fixed on the fuel electrode and separated into carbon dioxide, protons (H ⁺ ), and electrons (e ⁻ ), and the protons pass through the solid polymer electrolyte membrane. It reacts with oxygen in the air on the oxidizer electrode to produce water. At this time, electric power is taken out by the electrons moving from the fuel electrode to the oxidant electrode through the external load.

  In such a DMFC, since a liquid is used as the fuel, the energy density of the fuel can be increased and the volume of the fuel tank can be reduced as compared with those using a gas such as hydrogen. Moreover, since a reformer is not required, it is easy to reduce the size and weight, and it is expected as a power generator for small equipment. On the other hand, since the liquid fuel is in direct contact with the fuel electrode, a crossover occurs in which methanol and water pass through the solid polymer electrolyte membrane unreacted and reach the oxidizer electrode side. In some cases, the voltage drops and the fuel utilization efficiency decreases. In addition, carbon dioxide generated at the fuel electrode cannot be efficiently discharged, the pressure in the fuel container increases, and liquid fuel leaks, crossover increases, and cell performance decreases. In other words, it is desired to provide a technique capable of efficiently discharging carbon dioxide.

  In relation to the above, Patent Document 1 describes that fuel obtained by vaporizing liquid fuel through a gas-liquid separation membrane such as a PTFE porous body is supplied to the fuel electrode.

  Patent Document 2 discloses a fuel cell that selectively discharges carbon dioxide gas out of a fuel container through a separation membrane.

  In general, since a fuel cell has a low voltage obtained by a single cell, a necessary voltage is obtained as a fuel cell stack in which a plurality of cells are stacked and connected in series. As a method of stacking a plurality of fuel cells, a bipolar type in which unit cells of a fuel cell are stacked in the cell thickness direction and a planar stack type in which unit cells of a fuel cell are arranged in a plane are known. Since the planar stack type fuel cell can be made thinner than the bipolar type, the structure is suitable for a power generator for small equipment that is required to be small and thin.

  As such a planar stack type fuel cell, Patent Document 3 discloses that an oxygen electrode layer, a proton conductor layer, and a fuel electrode layer have a laminated structure, and the proton electrode is interposed between the oxygen electrode layer and the fuel electrode layer. A plurality of power generating elements in which the conductor layer is located are provided, and one adjacent power generating element layer and the other power generating element layer are arranged in series on a substantially same plane in a layer direction orthogonal to the stacking direction. In a planar array type electrochemical device unit that is connected and the proton conductor layer of the one power generation element and the proton conductor layer of the other power generation element are arranged on the same plane, the proton conductor layer On one side, the fuel electrode layer of the one power generating element and the oxygen electrode layer of the other power generating element on substantially the same plane are alternately arranged, and on the other side of the proton conductor layer, The oxygen electrode layer of the one power generating element on the same plane; Other power generating element of the fuel electrode layer and the planar array type electrochemical element unit, characterized in that are arranged alternately, it is described.

  In Patent Document 4, a plurality of fuel electrodes and air electrodes are alternately provided along a predetermined arrangement direction on each of the front and back surfaces of the proton conductor film, and the fuel electrode and the air electrode are disposed on the front and back surfaces of the proton conductor film. The fuel electrode and the air electrode are electrically connected to each other at a position adjacent to each other on the same plane with respect to the proton conductor film and in a predetermined direction with respect to the arrangement direction. A direct type fuel cell in which a pair of an electrode and an air electrode is formed is disclosed.

  Patent Document 5 supplies liquid fuel to the fuel electrode side of an electrode-membrane assembly in which a pair of air electrode and fuel electrode are joined via a proton conductive electrolyte membrane, and air is supplied to the air electrode side. In a direct liquid supply type fuel cell to be supplied, a plurality of electrode-membrane assemblies are formed on the same plane, and adjacent air electrodes and fuel electrodes of the plurality of electrode-membrane assemblies are connected in series or in parallel. In addition, fuel is supplied to the plurality of fuel electrodes configured on the same surface by the capillary body from the same fuel storage unit, and the air electrode chamber is formed to cover the plurality of air electrodes configured on the same plane. There is disclosed a direct liquid supply type fuel cell configured to supply air to the air electrode by a fan or a blower.

JP 2001-15130 A JP 2001-102070 A JP 2002-151134 A

  However, when the fuel is vaporized and supplied to the fuel electrode through the porous body, carbon dioxide generated at the fuel electrode may permeate the porous body and flow backward to the fuel supply side. Backflow sometimes hindered fuel vaporization.

  In addition, carbon dioxide may not smoothly escape from the porous body, and the fuel supply to the fuel electrode may become insufficient due to the carbon dioxide gas being filled between the fuel electrode and the porous body. As described above, when the fuel supply to the fuel electrode becomes insufficient, the power generation becomes unstable. In particular, since the generation of carbon dioxide increases as power is generated at a high current, it is desired to maintain stable power generation at a high output for a long time in a high current region.

  Further, when carbon dioxide is selectively discharged through the separation membrane, the carbon dioxide generated at the fuel electrode is likely to stagnate between the liquid fuel holding part and the fuel electrode, and as a result, the fuel supply to the fuel electrode is hindered. It is difficult to maintain stable power generation in a high current range for a long time.

  In a planar stack type polymer electrolyte fuel cell in which the fuel electrode and the oxidant electrode are alternately arranged on one surface of the electrolyte membrane, the fuel electrode and the oxidant electrode are on the same plane. It will be adjacent. At this time, in order to avoid mixing of the fuel supplied to the fuel electrode side and the oxidant gas supplied to the oxidant electrode, a member having a sealing property is disposed between the two to be blocked. Since the periphery of the fuel electrode is sealed with a sealing member, carbon dioxide generated at the fuel electrode may flow backward to the fuel flow path.

  That is, even in a planar stack type fuel cell in which the fuel electrode and the oxidant electrode are alternately arranged on one surface of the electrolyte membrane, carbon dioxide generated at the fuel electrode can be efficiently discharged. Offer is desired.

  Accordingly, an object of the present invention is to provide a technique for efficiently discharging carbon dioxide generated at a fuel electrode in a planar stack type fuel cell.

  Another object of the present invention is a solid polymer fuel in which carbon dioxide generated at the fuel electrode is efficiently discharged in a planar stack type fuel cell in which the fuel electrode and the oxidant electrode are alternately arranged. To provide a battery.

  Another object of the present invention is to provide a technique for efficiently discharging carbon dioxide generated at a fuel electrode in a planar stack type fuel cell.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the best mode for carrying out the invention. These numbers and symbols are added in parentheses in order to clarify the correspondence between the description of the claims and the best mode for carrying out the invention. However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

The polymer electrolyte fuel cell (15) according to the present invention includes a plurality of power generation elements (10), an electrical connection part (5), an insulating part (6), and a ventilation part (16). The plurality of power generation elements (10) have a common solid polymer electrolyte membrane (3). Each of the plurality of power generation elements (10) further includes a fuel electrode (1) and an oxidant electrode (2). In each power generating element (10), the fuel electrode (1) and the oxidant electrode (2) are arranged so as to sandwich the solid polymer electrolyte membrane (3). The plurality of power generation elements (10) are arranged so that the fuel electrode (1) and the oxidant electrode (2) are alternately arranged on the main surface of the solid polymer electrolyte membrane (3). On the main surface of the solid polymer electrolyte membrane (3), between the adjacent fuel electrode (1) and oxidant electrode (2), there is an electrical connection (5) or an insulating part (6).
Are provided alternately. On the back surface of the solid polymer electrolyte membrane (3), an oxidant electrode (2) is disposed at a position facing the fuel electrode (1) on the main surface, and the oxidant electrode (2) on the main surface. The fuel electrode (1) is disposed at a position opposite to the electrical connection portion (5), and the insulation portion (6) is disposed at a position opposed to the electrical connection portion (5) on the main surface. The electrical connection portion (5) is disposed at a position opposite to. The electrical connection (5) electrically connects between the adjacent fuel electrode (1) and the oxidant electrode (2). The insulating part (6) insulates between the adjacent fuel electrode (1) and the oxidant electrode (2). The plurality of power generation elements (10) are electrically connected in series. The oxidant electrode (2) is connected to the oxidant channel (2c) through which the oxidant gas flows. The ventilation part (16) discharges carbon dioxide generated in the fuel electrode (1) from the outer peripheral part on the planar direction side of the plurality of power generation elements (10) to the outside or to the adjacent oxidant electrode (2). It is provided to be discharged to the connected oxidant flow path (2c).

  According to the above-described configuration, the carbon dioxide generated at the fuel electrode (1) is efficiently discharged to the outside or the oxidant gas flow path via the ventilation portion (16).

  The fuel electrode (1) includes an anode catalyst layer (1b) in close contact with the solid polymer electrolyte membrane (3), and an anode gas diffusion electrode (1a) provided on the anode catalyst layer (1b). Have. The oxidant electrode (2) has a cathode catalyst layer (2b) in close contact with the solid polymer electrolyte membrane (3), and a cathode gas diffusion electrode (1a) provided on the cathode catalyst layer (2b). .

  The ventilation part (16) is a gap provided between the fuel electrode (1) and the oxidant electrode (2) insulated by the insulating part (6). The ventilation part (16) is connected to the anode gas diffusion electrode (1a). The ventilation portion (16) communicates with the outside at the outer peripheral portion in the planar direction of the plurality of power generation elements (10). The carbon dioxide generated at the fuel electrode (1) is discharged to the outside from the anode gas diffusion electrode (1a) through the vent (16).

  According to the above-described configuration, carbon dioxide generated at the fuel electrode (1) is discharged to the outside from the anode gas diffusion electrode (1a) through the ventilation portion (16). Since carbon dioxide does not flow back to the fuel flow path side, the supply of fuel is not hindered, and the pressure in the fuel flow path does not increase. Therefore, stable power generation can be maintained for a long time.

  In one embodiment of the present invention, the anode gas diffusion electrode (1a) covers the entire surface of the anode catalyst layer (1b). The anode gas diffusion electrode (1a) is wider in the planar direction than the anode catalyst layer (1b). The ventilation portion (16) includes a void formed under the portion where the anode gas diffusion electrode (1a) protrudes from the anode catalyst layer (1b). Carbon dioxide generated at the fuel electrode (1) is discharged to the outside from the lower part of the anode gas diffusion electrode (1a) protruding from the anode catalyst layer (1b) through the ventilation part (16).

  The polymer electrolyte fuel cell (15) according to the present invention further includes a porous body (14), a gas-liquid separation membrane (4), and a fuel channel (1c). The porous body (14) is provided on the electrical connecting portion (5) and the insulating portion (6). The gas-liquid separation membrane (4) is provided so as to cover the fuel electrode (1) through the gap (20) from above the two porous bodies (14). The fuel channel (1c) is provided so as to be connected to the surface of the gas-liquid separation membrane (4) opposite to the fuel electrode (1). The gap (20) formed between the gas-liquid separation membrane (4) and the fuel electrode (1) has an oxidant connected to the adjacent oxidant electrode (2) through the porous body (14). It communicates with the flow path (2c). The carbon dioxide generated in the fuel electrode (1) passes through the gap (20) formed between the gas-liquid separation membrane (4) and the porous body (14), and the oxidant channel (2c). Is discharged.

  Even with the above-described configuration, carbon dioxide generated in the fuel electrode (1) is discharged to the oxidant flow path (2c), and therefore does not flow back to the fuel flow path side. Therefore, stable power generation can be maintained for a long time.

  The electrical connection portion (5) is made of a non-porous conductive material through which gas cannot pass. The electrical connection (5) is preferably joined to both the anode gas diffusion electrode (1a) and the cathode gas diffusion electrode (1b).

  Moreover, an electrical connection part (5) is a gas seal part (7) which has gas-sealing property. The electrical connection part (5) and the anode gas diffusion electrode (1a) and the cathode gas diffusion electrode (2a) which are adjacent to each other through the electrical connection part (5) are formed from the gas diffusion electrode (17) which is a single member. Is formed.

  If the single gas diffusion electrode (17) is directly shared by the fuel electrode (1) and the oxidant electrode (2), it is not necessary to newly provide an electric connection part (5). It becomes easy. Moreover, since there is no contact resistance in the junction part of an electrical connection part (5) and a gas diffusion electrode (17), voltage loss can be suppressed. The gas seal portion (7) is formed in order to suppress mixing of fuel and oxidant through the gas diffusion electrode.

  The gas seal portion (7) is provided with a gas seal portion vent hole (18) for connecting between the adjacent anode gas diffusion electrode (1a) and the cathode gas diffusion electrode (1b). The insulating part (6) is provided with an insulating part vent hole (19) for connecting the anode gas diffusion electrode (1a) and the cathode gas diffusion electrode (1b) adjacent to each other through the insulating part (6). Yes. The carbon dioxide generated in the fuel electrode (1) passes from the anode gas diffusion electrode (1a) to the adjacent cathode gas diffusion electrode (2a) via the gas seal portion vent hole (18) or the insulating portion vent hole (19). Is discharged. The carbon dioxide discharged to the cathode gas diffusion electrode (2a) is discharged to the oxidant channel (2c).

  According to the present invention, there is provided a polymer electrolyte fuel cell in which carbon dioxide generated at the fuel electrode is efficiently discharged.

  Furthermore, according to the present invention, there is provided a polymer electrolyte fuel cell capable of efficiently discharging carbon dioxide generated at the fuel electrode in a planar stack type fuel cell.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a cross-sectional view of a polymer electrolyte fuel cell 1 in the present embodiment. FIG. 3 is a plan view of the polymer electrolyte fuel cell 15. As shown in FIG. 1A, the polymer electrolyte fuel cell 15 includes a plurality of power generation elements 10, an electrical connection unit 5, an insulating unit 6, a ventilation unit 16, an oxidant channel 2 c, a fuel channel 1 c, and a gas-liquid separation. The membrane 4, the flow path plate 12, and the spacer 11 are provided.

  As shown in FIG. 1A, one solid polymer electrolyte membrane 3 is commonly used in a plurality of power generating elements 10. Each power generation element 10 has a fuel electrode 1 and an oxidant electrode 2. In each power generation element 10, the fuel electrode 1 and the oxidant electrode 2 are disposed so as to sandwich the solid polymer electrolyte membrane 3. The plurality of power generation elements 10 arranged in this way may be described as MEA units below. Such a MEA unit is sandwiched between the flow path plates 12 to constitute the solid polymer fuel cell 15.

  FIG. 3 is a top view of the polymer electrolyte fuel cell 15. Actually, it is covered with the flow path plate 12 and the inside is not visible. The positional relationship of the connecting portion 5 and the like is shown through. Each power generating element 10 has a rectangular shape. The plurality of power generation elements 10 are arranged in the short side direction with their long sides facing each other. Here, in the adjacent power generation elements 10, the fuel electrode 1 and the oxidant electrode 2 are arranged so as to be adjacent to each other. That is, on the main surface of the solid polymer electrolyte membrane 3, the fuel electrode 1 and the oxidant electrode 2 are arranged alternately. The plurality of power generation elements 10 arranged in this way are electrically connected so as to be in series in the arrangement direction.

  As shown in FIG. 1A, the positive electrode terminal 8 and the negative electrode terminal 9 are connected to the power generation elements 10 located at both ends of the plurality of power generation elements 10. The positive terminal 8 and the negative terminal 9 are connected to an external load (not shown). A current flows from the positive electrode terminal 8 to the negative electrode terminal 9, and electric power is taken out from the polymer electrolyte fuel cell 15.

  A gap corresponding to the thickness of the MEA unit is formed in the outer peripheral portion of the polymer electrolyte fuel cell 15, and this gap is filled with the insulating portion 6 and the spacer 11. This prevents fuel leakage to the outside.

  FIG. 1B is an enlarged cross-sectional view showing two adjacent power generation elements 10 among a plurality of power generation elements 10. The fuel electrode 1 has an anode gas diffusion electrode 1a and an anode catalyst layer 1b. On the solid polymer electrolyte membrane 3, the anode catalyst layer 1b and the anode gas diffusion electrode 1a are laminated in this order. The oxidant electrode 2 has a cathode gas diffusion electrode 2a and a cathode catalyst layer 2b. On the solid polymer electrolyte membrane 3, the cathode catalyst layer 2b and the cathode gas diffusion electrode 2a are laminated in this order.

  As shown in FIG. 1A and FIG. 3, an electrical connection portion 5 or an insulating portion 6 is provided between adjacent power generation elements 10. Here, the electrical connecting portions 5 and the insulating portions 6 are provided alternately on the main surface of the solid polymer electrolyte membrane 3. Further, the electrical connection portion 5 and the insulating portion 6 are provided on the main surface and the back surface so as to face each other with the solid polymer electrolyte membrane 3 interposed therebetween. The electrical connection unit 5 electrically connects the anode gas diffusion electrode 1a of one power generation element 10 and the cathode gas diffusion electrode 2a of the adjacent power generation element 10. On the other hand, the insulating part 6 insulates the fuel electrode 1a from the adjacent oxidant electrode 2a.

  Similarly, on the back side of the solid polymer electrolyte membrane 3, the electrical connection portion 5 or the insulating portion is provided between the adjacent power generation elements 10. However, an insulating portion 6 is provided at a position facing the electrical connection portion 5 on the main surface side, and an electrical insulating portion 5 is provided at a position facing the insulating portion 6 on the main surface side.

  In this way, the plurality of power generation elements 10 are connected in series in the short side direction.

  The insulating part 6 is provided to electrically isolate the adjacent fuel electrode 1 and the oxidant electrode 2, and a part or all of the space between the fuel electrode 1 and the oxidant electrode 2 has a corrosion resistance. It can be formed by partitioning with a material. The insulating portion 6 is thinner than the anode gas diffusion electrode 1a. The ratio of the thickness of the insulating portion 6 to the anode gas diffusion electrode 1a is not particularly limited, but it is sufficient that carbon dioxide is effectively removed, and a value of 0.2 to 0.5 is desirable. Further, as shown in FIG. 3, the insulating portion 6 may be provided also on the outer peripheral portion of the polymer electrolyte fuel cell 15. Thereby, the exterior and each electric power generation element 10 are insulated.

  The insulating portion 6 may be formed as an insulating portion 6 by simply providing a gap between the fuel electrode 1 and the oxidant electrode 2 instead of partitioning both electrodes with a resin.

  Refer to FIG. 1B. Between the anode gas diffusion electrode 1a and the cathode gas diffusion electrode 2a located on both sides of the insulation part 6 because the thickness of the insulation part 6 is thinner than the thickness of the anode gas diffusion electrode 1a or a gap, The ventilation part 16 which is a space | gap is formed. That is, the air gap 16 is a gap formed between the insulating portion 6 and the solid electrolyte membrane 3. Since the insulating portion 6 is thinner than the anode gas diffusion electrode 1 a, the anode gas diffusion electrode 1 a is connected to the ventilation portion 16. Thereby, as shown by the arrow in FIG. 1B, the carbon dioxide generated in the anode gas diffusion electrode 1 a is exhausted to the ventilation part 16.

  On the other hand, the electrical connection portion 5 has the same thickness as the anode gas diffusion electrode 1a and is provided at the same height. A space having the same thickness as the anode catalyst layer 1b is formed between the electrical connecting portion 5 and the solid polymer electrolyte membrane 3, but is not connected to the anode gas diffusion electrode 1a. Therefore, it does not particularly contribute to the emission of carbon dioxide. However, the thickness of the electrical connecting portion 5 may be made thinner than the anode gas diffusion electrode 1a in the same manner as the insulating portion 6, and the space may be connected to the anode gas diffusion electrode 1a. In this way, carbon dioxide can be discharged from both the insulating portion 6 side and the electrical connecting portion 5 side in one fuel electrode 1. Therefore, carbon dioxide is discharged more efficiently.

  In addition, when the insulating part 6 is not a partition using a material such as a resin but a gap, the insulating part 6 itself between the anode gas diffusion electrode 1 a and the cathode gas diffusion electrode 2 a becomes the ventilation part 16.

  The ventilation portion 16 extends on the long side of the power generation element 10 (in the direction perpendicular to the paper surface in FIG. 1B). The solid polymer type communicates with the outside at the outer periphery of the fuel cell 15. As described above, the outer peripheral portion of the polymer electrolyte fuel cell 15 is filled with the gap by the insulating portion 6 and the spacer 11, but openings are provided at portions located at both ends of the ventilation portion 16. . Through the opening, the ventilation portion 16 communicates with the outside at both ends in the long side direction, that is, at the outer peripheral portion of the polymer electrolyte fuel cell 15.

  As shown in FIG. 1B, the gas-liquid separation membrane 4 is provided on the anode gas diffusion electrode 1a (on the opposite side of the solid polymer electrolyte membrane 3). A fuel flow path 1 c is connected on the gas-liquid separation membrane 4. The fuel flow path 1c is a recess provided at a position corresponding to the fuel electrode 1 in the flow path plate 12, and allows fuel to flow. When a liquid fuel such as a methanol aqueous solution is allowed to flow through the fuel flow path 1 c, the fuel is vaporized via the gas-liquid separation film 4, and the vaporized fuel is supplied to the fuel electrode 1. As the gas-liquid separation membrane 4, a water-repellent porous membrane such as a PTFE porous membrane is preferably used.

  An oxidant flow path 2c is connected on the cathode gas diffusion electrode 2a. The oxidant flow path 2 c is a recess provided in a portion of the flow path plate 12 positioned on the oxidant electrode 2. An oxidant gas such as air is supplied from the oxidant flow path 2c to the cathode gas diffusion electrode 2a.

  The flow path plate 12 sandwiches the MEA unit in which the fuel electrodes 1 and the oxidant electrodes 2 are alternately arranged and a plurality of power generation elements 10 are connected in series in a planar shape as described above. Further, although not shown in the drawing, a seal member for preventing fuel leakage may be disposed between the MEA unit and the flow path plate 12. As the sealing member, those having sealing properties, insulating properties and elasticity are preferable, and usually rubber materials having a sealing function, for example, rubber materials such as silicon rubber, butyl rubber and fluororesin rubber are suitably used. By providing the seal member, it is possible to more effectively prevent the liquid fuel from leaking. As a method of sandwiching both sides of the MEA unit with the flow path plate 12, two flow path plates 12 are screwed with a plurality of screws so as to penetrate the peripheral edge of the flow path plate 12, or the flow path plate 12 and the MEA unit may be bonded with an adhesive or the like.

  As shown in FIG. 1A, the spacer 11 is provided for the purpose of absorbing gaps, thickness variations, etc. generated in the polymer electrolyte fuel cell 15. As the material, the same material as the above-described seal member can be used. The spacer 11 is provided, for example, in a gap between the power generation element located at both ends and the outside.

  Then, the raw material of the above-mentioned structural member is demonstrated.

  As the solid polymer electrolyte membrane 3, a polymer membrane having corrosion resistance to fuel, high hydrogen ion (proton) conductivity, and no electronic conductivity is preferably used. The constituent material of the solid polymer electrolyte membrane 11 is preferably an ion exchange resin having a polar group such as a strong acid group such as a sulfone group, a phosphoric acid group, a phosphone group or a phosphine group, or a weak acid group such as a carboxyl group. Examples include perfluorosulfonic acid resins, sulfonated polyether sulfonic acid resins, sulfonated polyimide resins, and the like. More specifically, for example, sulfonated poly (4-phenoxybenzoyl-1,4-phenylene), sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polyimide, alkylsulfonated polybenzo Examples thereof include a solid polymer electrolyte membrane made of an aromatic polymer such as imidazole. The film thickness of the solid polymer electrolyte membrane can be appropriately selected within a range of about 10 to 300 μm depending on the material, the use of the fuel cell, and the like.

  The oxidant electrode 2 is an electrode that reduces oxygen to water, and includes, for example, particles (including powder) in which a catalyst is supported on a carrier such as carbon or a catalyst alone having no carrier, a proton conductor, The catalyst layer (cathode catalyst layer (2b)) that is a mixture of the above is formed on a gas diffusion electrode (cathode gas diffusion electrode 2a) such as carbon paper by coating or the like. Examples of the catalyst include platinum, rhodium, palladium, iridium, osmium, ruthenium, rhenium, gold, silver, nickel, cobalt, molybdenum, lanthanum, strontium, yttrium, and the like. The catalyst may be used alone or in combination of two or more. Examples of the particles supporting the catalyst include carbon-based materials such as acetylene black, ketjen black, carbon nanotubes, and carbon nanohorns. For example, when the carbonaceous material is a granular material, the size of the particles is appropriately selected within a range of about 0.01 to 0.1 μm, preferably within a range of about 0.02 to 0.06 μm. In order to support the catalyst on the particles, for example, a colloidal method can be applied.

The fuel electrode 1 is an electrode that generates hydrogen ions, carbon dioxide, and electrons from methanol and water, and similarly to the oxidant electrode 2 described above, a catalyst layer (anode catalyst layer 1b) and a gas diffusion electrode (anode gas diffusion electrode). 1a). The catalyst amount per unit area of the anode and the cathode, depending on the catalyst type and size, ^etc., and can be appropriately selected within 1mg / cm ² ~20mg / cm 2 in the range of about.

  As the gas diffusion electrodes 1a and 2a, a conductive porous material such as carbon paper, a carbon molded body, a carbon sintered body, a sintered metal, and a foam metal can be used, and the thickness is 100 μm to 300 μm. Those having a porosity of 40% to 90% are preferably used.

  The electrical connection portion 5 is made of a material having high conductivity, corrosion resistance, and gas sealability. For example, stainless steel or noble metal is preferably used.

  As the insulating part 6 and the flow path plate 12, an insulating material having corrosion resistance is used. Examples thereof include polyolefins such as polypropylene and polyethylene, resins such as polycarbonate, polyvinyl chloride, polyether ether ketone, polysulfone, and silicone, or ceramics such as silica and alumina.

  As the liquid fuel supplied from the fuel flow path 1c, a mixed aqueous solution of methanol and water is generally used. Air is generally used as the oxidant supplied from the oxidant flow path 2c. The liquid fuel and the oxidant can be supplied using an auxiliary machine such as a pump or a blower. The fuel flow path 1c and the oxidant flow path 2c may be formed so that a plurality of power generation elements 10 are connected in series, or formed in parallel so as to branch into a plurality of flow paths and flow to each power generation element. May be. Further, air may be introduced by opening the oxidant flow path 2c entirely or partially to the atmosphere without using an auxiliary machine. In addition, a methanol aqueous solution can be supplied to the fuel electrode 1 by a capillary phenomenon using a fuel holding material called a wicking material in the fuel channel 1c. As the fuel holding material, for example, a hydrophilic foam material such as a hydrophilic urethane foam material or hydrophilic glass fiber, or a porous material is preferably used.

  The electrical connection portion 5 can be formed by joining the gas diffusion electrodes of the fuel electrode 1 and the oxidant electrode 2 with a metal material having corrosion resistance. In this manner, the fuel electrode 1 and the oxidant electrode 2 can be electrically connected while having gas sealing properties.

  On the other hand, the insulating portion 6 is an insulating plate or seal made of a resin or ceramic having a thickness smaller than that of the gas diffusion electrode around the gap between the gas diffusion electrodes of the fuel electrode 1 and the oxidant electrode 2 adjacent after the MEA unit is manufactured. It can be formed by adhering or thermally bonding members. Alternatively, the same structure including the ventilation portion 16 can be obtained by previously joining the above-described insulating plate or seal member to the flow path plate 12 together with the gas-liquid separation film 4 and sandwiching the MEA unit between the flow path plates 12. It is possible to form.

  Next, a carbon dioxide discharge path in the polymer electrolyte fuel cell 15 according to the present embodiment will be described.

  The arrows in FIG. 1B indicate the flow of carbon dioxide generated at the fuel electrode 1. As described above, the fuel electrode 1 generates carbon dioxide during power generation. The generated carbon dioxide is discharged from the side portion of the anode gas diffusion electrode 1a to the ventilation portion 16. The carbon dioxide led to the ventilation part 16 is discharged to the outside at both ends in the long side direction as indicated by arrows in FIG.

  In the fuel cell stack structure of the type in which fuel electrodes and oxidant electrodes are alternately arranged on the same plane as in the present invention and connected in series, for example, when a fuel such as hydrogen gas is used as the gaseous fuel, the fuel gas In order to prevent leakage, high sealing performance is required between the adjacent fuel electrode and oxidant electrode. Also, when liquid fuel is supplied directly to the fuel electrode, it is desired that the liquid fuel be completely sealed in order to prevent fuel leakage.

  On the other hand, in this invention, in order to discharge | release the carbon dioxide which is a reaction product to the exterior, it is made the structure which dared to remove the seal partially. Although the vaporized fuel leaks, the amount thereof is small, and it is possible to improve the cell performance of the fuel cell stack by providing a means for discharging carbon dioxide.

  As described above, according to the present embodiment, in the planar stack type fuel cell that vaporizes and supplies the methanol aqueous solution, the ventilation portion 16 is provided between the gas-liquid separation membrane and the solid polymer electrolyte membrane. Thus, carbon dioxide generated at the fuel electrode is efficiently discharged, and the liquid fuel is smoothly vaporized and supplied through the gas-liquid separation membrane, so that stable high-output power generation can be maintained for a long time. .

  Moreover, since the flow path structure is not externally attached to the MEA unit in order to discharge carbon dioxide, a new volume is not taken. Therefore, it is advantageous also for the demand for miniaturization of the fuel cell.

(Second Embodiment)
FIG. 2A is a cross-sectional view of a polymer electrolyte fuel cell according to a second embodiment. FIG. 2B is an enlarged cross-sectional view of two adjacent power generation elements in FIG. 2A. In the present embodiment, the sizes of the anode gas diffusion electrode 1a and the cathode gas diffusion electrode 2a are devised compared to the first embodiment. In the detailed description of the configuration, the description of the same configuration as in the first embodiment is omitted.

  The anode gas diffusion electrode 1a is formed wider than the anode catalyst layer 1b. Similarly, the cathode gas diffusion electrode 2a is also formed wider than the cathode catalyst layer 2b. In this way, the anode gas diffusion electrode 1a slightly protrudes from the anode catalyst layer 1b. Similarly, the cathode gas diffusion electrode 2a slightly protrudes from the cathode catalyst layer 2b.

  The thickness of the insulating portion 6 is the same as the thickness of the anode gas diffusion electrode 1a, and is provided at the same height as the anode gas diffusion electrode 1a. The insulating part 6 is formed of a material such as resin.

  With the configuration as described above, a gap having the same thickness as the anode catalyst layer 1 b is formed as the ventilation portion 16 between the insulating portion 6 and the solid polymer electrolyte membrane 3. Similarly, a gap is generated between the electrical connection portion 5 and the solid polymer electrolyte membrane 3 to form a ventilation portion 16. The ventilation part 16 is connected to the anode gas diffusion electrode 1a at the lower part (solid polymer electrolyte membrane 3 side) where the anode gas diffusion electrode 1a protrudes from the anode catalyst layer 1b. In addition, the ventilation | gas_flowing part 16 is connected with the exterior in the long side direction both ends of the electric power generation element 10 similarly to 1st Embodiment.

  Next, the carbon dioxide emission route in the present embodiment will be described. In FIG. 2B, arrows indicate the direction of carbon dioxide flow. Carbon dioxide generated at the fuel electrode 1 is discharged from the lower part of the protruding portion (on the side of the solid polymer electrolyte membrane 3) to the ventilation part 16 in the anode gas diffusion electrode 1a. The carbon dioxide exhausted to the ventilation portion 16 is exhausted to the outside from both end portions in the long side direction (the outer peripheral portion of the polymer electrolyte fuel cell 15), as in the first embodiment.

  According to the present embodiment, similarly to the first embodiment, carbon dioxide generated at the fuel electrode can be smoothly discharged outside the fuel cell without returning to the fuel flow path side. The area ratio of the anode catalyst layer 1b to the anode gas diffusion electrode 1a is preferably 80% to 95%. By setting it as such a range, carbon dioxide can be discharged | emitted more smoothly outside.

(Third embodiment)
4A, B, and 5 show the configuration of the polymer electrolyte fuel cell 15 according to the third embodiment. FIG. 5 is a diagram for explaining the arrangement of the components on the main surface of the solid polymer electrolyte membrane 3. 4A is a cross-sectional view taken along the line AA ′ of FIG. 4B is an enlarged view of two adjacent power generation elements 10 in FIG. 4A. In the present embodiment, compared to the first embodiment, (1) the anode gas diffusion electrode 1a and the cathode gas diffusion electrode 2a share a single member (gas diffusion electrode 17). 2) The inventor 6 and the electrical connection part 5 (gas seal part 7) have been devised in that vent holes are provided. Details of these configurations will be described below. Note that description of the same configuration as in the first embodiment may be omitted.

  As shown in FIG. 4A, the anode gas diffusion electrode 1a of one power generation element 10 is formed by a gas diffusion electrode 17 that is the same member as the cathode gas diffusion electrode 2a of another adjacent power generation element 10. Yes. That is, one gas diffusion electrode 17 is used in common by the two power generation elements 10.

  A gas seal portion 7 is provided at the center of the gas diffusion electrode 17. Here, the gas seal portion 7 is provided at a position corresponding to the electrical connection portion 5 in the first embodiment. The gas diffusion electrode 17 is divided into an anode gas diffusion electrode 1 a and a cathode gas diffusion electrode 2 a by the gas seal portion 7. That is, in this embodiment, the gas seal portion 7 is the electrical connection portion 5. The gas seal portion 7 has gas seal properties and suppresses mixing of fuel and oxidant. The gas seal portion 7 has a gas seal property but does not have an insulating property, and the anode gas diffusion electrode 1a and the cathode gas diffusion electrode 2a are electrically connected.

  The gas seal portion 7 can be formed by applying a thermosetting sealant to the gas diffusion electrode 17. As the sealant, for example, a silicone-based or olefin-based one can be suitably used. Or you may form by apply | coating the conductive paste which consists of metal particulates which have corrosion resistance like gold | metal | money, platinum, etc. to a gas diffusion electrode, and sintering it.

  Incidentally, as shown in FIG. 5, the gas seal portion 7 is formed so as to fill substantially the entire long side direction between the adjacent power generation elements 10, but in part, the gas seal portion 7 is provided. Not. A portion where the gas seal portion 7 is not provided serves as a gas seal portion vent hole 18 connecting the anode gas diffusion electrode 1a and the adjacent cathode gas diffusion electrode 2a.

  In addition, the spacer 11 and the insulating part 6 are arrange | positioned at the outer peripheral part of the polymer electrolyte fuel cell 15, and the inside is sealed.

  As shown in FIGS. 4A and 4B, the insulating portion 6 is provided between the adjacent gas diffusion electrodes 17. Similar to the gas seal portion 7, the insulating portion 6 is provided over substantially the entire long-side direction of the power generation element 10. However, in some cases, the insulating portion 6 is not provided and is a gap. This gap portion is the insulating portion vent hole 19. The insulating part vent hole 19 allows ventilation between one fuel electrode 1 and the adjacent oxidant electrode 2.

  The insulating portion 6 provided with the insulating portion vent hole 19 is provided with an insulating plate or a seal member made of resin or ceramic partially cut out with the same thickness as the fuel electrode 1 and the oxidizer electrode 2 of the MEA unit, and an adjacent fuel. It can be formed by inserting between the electrode 1 and the oxidant electrode 2. Alternatively, a thermosetting sealant may be applied between the fuel electrode 1 and the oxidant electrode 2 by partially applying a gap and thermosetting.

  When the insulating portion 6 is a gap, the entire insulating portion 6 acts as the insulating portion vent hole 19 and allows ventilation between one fuel cell 1 and the adjacent oxidant electrode 2.

  Next, the carbon dioxide emission route in the present embodiment will be described. In the present embodiment, the insulating portion vent hole 19, the gas seal portion vent hole 18, and the cathode gas diffusion electrode 2 a function as the vent portion 16.

  The arrows in FIG. 5 indicate the flow of carbon dioxide generated at the fuel electrode 1. According to the present embodiment, at least one or more insulating portion vent holes 19 are provided in the insulating portion 6, and at least one or more gas seal portion vent holes 18 are provided in the gas seal portion 7. The carbon dioxide generated at the pole 1 is discharged to the adjacent cathode gas diffusion electrode 2a through these vent holes 18 and 19.

  Similarly, in FIG. 4B, the flow of carbon dioxide is indicated by arrows. However, since FIG. 4B is a cross section passing through the gas seal portion 7 and the insulating portion 6, carbon dioxide does not actually move in this cross section. The carbon dioxide moving through the gas seal portion vent hole 18 and the insulating portion vent hole 19 is conceptually seen through. As shown in FIG. 4B, the carbon dioxide discharged to the cathode gas diffusion electrode 2a is discharged to the oxidant channel 2c. In this way, carbon dioxide generated at the fuel electrode is discharged to the oxidant channel 2c.

  That is, in this embodiment, the gas seal portion vent hole 18, the insulating portion vent hole 19, and the cathode gas diffusion electrode 2 a function as the vent portion 16.

  According to the present embodiment, as in the first and second embodiments, in the planar stack type fuel cell in which the fuel electrode and the oxidant electrode are alternately arranged on the same plane, carbon dioxide is used. It can be discharged efficiently.

  Furthermore, according to the present embodiment, since the ventilation portion 16 does not communicate with the outside air, the outside air is prevented from entering the inside of the fuel cell during storage of the fuel cell, and the electrode is deteriorated or dried up during storage. Deterioration of battery performance can be suppressed.

  In addition, the discharged carbon dioxide is mixed in the oxidant gas. However, by sufficiently increasing the flow rate of the oxidant gas compared to the generated carbon dioxide, the deterioration of the battery performance due to the mixed carbon dioxide is prevented. Can be suppressed. The number and size of the gas seal portion vent holes 18 and the insulating portion vent holes 19 are not particularly limited as long as at least the number and size of carbon dioxide are effectively discharged. When the length of the portion where the gas seal portion vent hole 18 and the insulating portion vent hole 19 are provided is in the range of 10% to 50% with respect to the length of the power generation element 10 in the long side direction, carbon dioxide is More effectively discharged.

  Furthermore, since fuel leakage due to an increase in the internal pressure of the fuel container can be prevented, a decrease in performance and life of the fuel cell stack can be suppressed, and a highly reliable fuel cell can be provided.

  Further, since the adjacent fuel electrode 1 and the oxidant electrode 2 communicate with each other through the vent hole, water vapor generated at the oxidant electrode 2 is supplied to the fuel electrode 1 side. Since the fuel electrode 1 is humidified, more stable power generation is possible.

  Furthermore, since the anode gas diffusion electrode 1a and the cathode gas diffusion electrode 2a share the gas diffusion electrode 17 that is one member, a process for adding a new electrical connection is not required. Therefore, the manufacturing process can be simplified. Moreover, since there is no contact resistance in the junction part of the electrical connection part 5 and a gas diffusion electrode, a voltage loss can be suppressed.

(Fourth embodiment)
FIG. 6A is a cross-sectional view of the polymer electrolyte fuel cell 15 in the fourth embodiment. In the present embodiment, in contrast to the third embodiment, the insulating portion 6 and the gas seal portion 7 are continuous without a vent hole, and the porous body 14 is provided between the fuel electrode 1 and the gas-liquid separation membrane 4. It is different in that it is inserted. Other configurations are the same as those of the third embodiment, and a description thereof will be omitted.

  6B is an enlarged cross-sectional view of a portion related to the two power generation elements 10 in FIG. 6A. A porous body 14 is disposed on the gas seal portion 7. The porous body 14 provided on the gas seal portion 7 is connected to the oxidant flow path 2c at one end. On the other hand, the porous body 14 is also disposed on the insulating portion 6 (on the opposite side of the solid polymer electrolyte membrane 3). The gas-liquid separation membrane 4 is provided on the porous body 14 provided on the gas seal portion 7 and the porous body 14 provided on the insulating portion 6. A gap 20 about the thickness of the porous body 14 is formed between the gas-liquid separation membrane 4 and the anode gas diffusion electrode 1a. A fuel flow path 1 c is provided on the gas-liquid separation membrane 4. That is, the porous body 14 is connected to the gap 20 on the opposite side of the oxidant flow path 2c.

  In FIG. 6B, the arrows indicate the flow of carbon dioxide generated at the fuel electrode 1. Carbon dioxide generated on the fuel electrode 1 side (anode gas diffusion electrode 1a) of the gas diffusion electrode 17 is discharged into the gap 20 from the upper side (gas-liquid separation membrane 4 side). The carbon dioxide discharged to the gap 20 is discharged from the side portion through the porous body 14 to the oxidant flow path 2c. That is, in the present embodiment, the gap 20 and the porous body 14 act as the ventilation part 16.

  The porous body 14 is inserted between the gas-liquid separation membrane 4 and the insulating portion 6 and between the gas-liquid separation membrane 4 and the gas seal portion 7 so as to surround the outer peripheral portion in the planar direction of the anode gas diffusion electrode 1a of each power generation element 10. can do.

  The porous body 14 is preferably water-repellent and has a pore diameter of 1 to 10 μm and a porosity of 40% to 80%. The thickness of the porous body 14 varies depending on the pore diameter, but may be a thickness that allows carbon dioxide to permeate smoothly, and is preferably in the range of 0.1 to 1 mm from the viewpoint of practicality.

  The porous body 14 may be provided only on the gas seal portion 7. In this case, outside air can be prevented from entering the inside of the fuel cell during storage of the fuel cell, and deterioration of the battery performance due to electrode deterioration and dry-up during storage can be suppressed.

  According to the present embodiment, the carbon dioxide generated at the fuel electrode 1 can be efficiently discharged as in the third embodiment. Further, since the fuel electrode 1 and the oxidant electrode 2 communicate with each other through the porous body 14, water vapor generated at the oxidant electrode 2 by the power generation reaction is diffused and supplied to the fuel electrode 1 side through the porous body 14. Therefore, the fuel electrode 1 is always humidified during power generation, and more stable power generation is possible.

  In addition, since carbon dioxide generated in the fuel electrode 1 escapes to the oxidant channel 1c, there is no need to provide a vent hole in the gas seal portion 7 or the insulating portion 6. Therefore, the insulating part 6 is formed by inserting a continuous resin plate or seal member between the adjacent fuel electrode 1 and oxidant electrode 2 with the same thickness as the fuel electrode 1 and oxidant electrode 2 of the MEA unit. can do. Alternatively, it can be formed by filling a thermosetting sealant between the fuel electrode 1 and the oxidant electrode 2 and thermosetting it. Since it is not necessary to provide a vent hole in the gas seal portion 7 or the insulating portion 6, the manufacturing process is simplified and the same carbon dioxide emission effect as that in the third embodiment can be obtained.

  In addition, the device made | formed in the 1st-4th embodiment does not need to be an independent thing, respectively, The same effect can be show | played by combining and using a some form as needed.

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

(Example)
The structure of the fuel cell stack used in the examples will be described below. The structure of the fuel cell stack is the same as that shown in FIG. As the gas diffusion electrode, carbon paper (manufactured by Toray Industries, Inc.) having a thickness of about 0.3 mm is used, and two types of a length of 90 mm, a width of 15 mm (electrode A), and a length of 90 mm and a width of 32 mm (electrode B) are used. A rectangular shape was prepared. In addition, a gas seal portion is obtained by filling the inside of the gas diffusion electrode with a thermosetting olefin-based sealant in the center of the short side of the electrode B and having a length of 90 mm and a width of 2 mm in parallel with the long side of the electrode. 7 was formed.

  An anode catalyst layer and a cathode catalyst layer were formed on the two electrodes A, respectively. For the electrode B, a total of four electrodes were prepared in which the anode catalyst layer was formed on one surface partitioned by the gas seal portion and the cathode catalyst layer was formed on the other surface. The cathode catalyst layer and the anode catalyst layer were produced as follows. The catalyst used for the cathode catalyst layer may be the same as the catalyst used for the anode catalyst layer.

Catalyst-supported carbon fine particles prepared by supporting 50% by weight of platinum fine particles having a particle diameter in the range of 3 to 5 nm on carbon particles (Ketjen Black EC600JD manufactured by Lion Corporation) were prepared. A 5 wt% Nafion solution manufactured by DuPont (trade name; DE521, “Nafion” is a registered trademark of DuPont) is added and stirred to obtain a catalyst paste for cathode formation. On the other hand, except for using platinum (Pt) -ruthenium (Ru) alloy fine particles (Ru ratio is 50 at%) having a particle diameter in the range of 3 to 5 nm instead of platinum fine particles, A catalyst paste for anode formation is obtained under the same conditions. A cathode forming catalyst paste was applied onto the gas diffusion electrode at a coating amount of ¹ to 8 mg / cm ² and dried to form a cathode catalyst layer. The anode catalyst layer was formed in the same manner using a catalyst paste for anode formation.

  Next, a 10 cm × 10 cm × 180 μm-thick membrane made of Nafion 117 (number average molecular weight 250,000) manufactured by DuPont was used as the solid polymer electrolyte membrane 3, and an anode (cathode) catalyst was formed on one surface of this membrane. The electrode A is arranged at the right end (left end) of the one electrode A and the two electrodes B in which the layers are formed, and the electrodes are alternately arranged with the fuel electrode and the oxidant electrode at intervals of 2 mm with the long sides parallel. Arranged. On the other surface, the electrodes A1 and B2 on which the cathode (anode) catalyst layer was formed were arranged such that the above arrangement was rotated 180 degrees parallel to the film surface. Thus, the electrode A is positioned at both ends of the MEA unit so as to face the membrane, and the fuel electrodes and the oxidant electrodes of the electrodes A and B are alternately arranged, and five power generating elements are connected in series. it can. The fuel electrode 1 and the oxidizer electrode 2 are joined to the solid polymer electrolyte membrane 3 by hot pressing from the outside of the electrode in the above arrangement with the surface of the catalyst layer formed on the electrode facing the solid polymer electrolyte membrane. Thus, an MEA (electrode-electrolyte membrane assembly) unit was obtained.

  Silicon rubber having a thickness of 0.3 mm, a width of 2 mm, and a length of 90 mm was inserted into the gap between the electrodes A and B of the MEA unit to constitute the insulating portion 6. In addition, a gas-liquid separation membrane 4 (thickness 30 μm, 80% porosity and 1 μm pore diameter) were adhered. Next, a porous film (thickness 0.15 mm, pore diameter 5 μm, porosity 50%) made of an acrylic copolymer having a water repellent treatment with a length of 90 mm and a width of 2 mm is formed on both surfaces of the MEA unit. The silicon sealer is disposed on the periphery of the MEA unit as a spacer, and the flow path plate 12 is disposed on both sides of the MEA unit so that the gas-liquid separation membrane 4 and the fuel electrode 1 are in contact with each other. And a desired fuel cell stack was obtained by screwing the peripheral edge of the flow path plate.

(Comparative example)
A fuel cell stack of Comparative Example 1 was configured in the same manner as Example 1 except that the porous membrane 4 for removing carbon dioxide was not provided.

FIG. 7 shows changes with time in voltage when the fuel cell stacks of Example 1 and Comparative Example 1 are generated at 125 mA / cm ² . The liquid fuel was supplied with 100 mL of a 10 vol% aqueous methanol solution at a flow rate of 30 mL / min using a pump, and the oxidant was supplied with air at a flow rate of about 600 mL / min using a blower. At this time, the fuel channel 1c and the oxidant channel 2c were connected in series.

  In the example, no voltage drop is observed even in an elapsed time of about 60 minutes, whereas in the comparative example, power generation is stopped within a few minutes. In the example, no inflow of carbon dioxide was observed on the fuel flow path side, but in the comparative example, inflow of carbon dioxide into the fuel flow path was confirmed. This result shows that carbon dioxide generated by power generation is released to the oxidant flow path side by inserting a porous body as a gas permeable layer between the fuel electrode and the gas-liquid separation membrane. Therefore, the fuel supply to the fuel electrode is not hindered, and it seems that high power generation can be maintained for a long time for a long time.

  On the other hand, in the comparative example, a rapid voltage drop occurred in a power generation time of about 5 minutes, and power generation became impossible. This is probably because the carbon dioxide gas generated at the fuel electrode hinders the fuel supply to the fuel electrode.

  In addition, in Example 1, although it illustrated about the effect of this invention in the fuel cell stack structure represented by FIG. 6, it was confirmed that the structure represented by FIGS. 1-5 also shows the same characteristic.

It is a figure which shows the cross-sectional structure of the polymer electrolyte fuel cell which concerns on 1st Embodiment. It is the figure which expanded the two electric power generation element parts in FIG. 1A. It is a figure which shows the cross-sectional structure of the polymer electrolyte fuel cell which concerns on 2nd Embodiment. It is the figure which expanded the two electric power generation element parts in FIG. 2A. In 1st Embodiment, it is a figure which shows the positional relationship on the main surface of a polymer electrolyte fuel cell. It is a figure which shows the cross-sectional structure of the polymer electrolyte fuel cell which concerns on 3rd Embodiment. It is the figure which expanded the two electric power generation element parts in FIG. 4A. In 3rd Embodiment, it is a figure which shows the positional relationship on the main surface of a polymer electrolyte fuel cell. It is a figure which shows the cross-sectional structure of the polymer electrolyte fuel cell which concerns on 4th Embodiment. It is the figure which expanded the two electric power generation element parts in FIG. 6A. It is the characteristic of the fuel cell used by the Example and the comparative example.

Explanation of symbols

1 Fuel electrode (anode)
1a Anode gas diffusion electrode 1b Anode catalyst layer 1c Fuel flow path 2 Oxidant electrode (cathode)
2a Cathode gas diffusion electrode 2b Cathode catalyst layer 2c Oxidant channel 3 Solid polymer electrolyte membrane 4 Gas-liquid separation membrane 5 Electrical connection unit 6 Insulation unit 7 Gas seal unit 8 Positive electrode terminal 9 Negative electrode terminal 10 Power generation element 11 Spacer 12 Channel Plate 14 Porous body 15 Polymer electrolyte fuel cell 16 Ventilation portion 17 Gas diffusion electrode 18 Gas seal portion ventilation hole 19 Insulation portion ventilation hole 20 Gap

Claims (10)

A plurality of power generation elements;
An electrical connection;
An insulating part;
A vent,
Comprising
The plurality of power generation elements have a common solid polymer electrolyte membrane,
Each of the plurality of power generation elements further includes a fuel electrode and an oxidant electrode,
In each of the power generating elements, the fuel electrode and the oxidant electrode are arranged so as to sandwich the solid polymer electrolyte membrane,
The plurality of power generation elements are arranged such that fuel electrodes and oxidant electrodes are alternately arranged on the main surface of the solid polymer electrolyte membrane,
On the main surface of the solid polymer electrolyte membrane, between the adjacent fuel electrode and oxidant electrode, the electrical connection portion or the insulating portion is provided alternately,
On the back surface of the solid polymer electrolyte membrane, an oxidant electrode is disposed at a position facing the fuel electrode on the main surface, and a fuel electrode is disposed at a position facing the oxidant electrode on the main surface. ,
An insulating part is disposed at a position facing the electrical connection part on the main surface, and an electrical connection part is disposed at a position facing the insulating part on the main surface,
The electrical connection portion electrically connects between an adjacent fuel electrode and an oxidant electrode,
The insulating part insulates between an adjacent fuel electrode and an oxidant electrode,
The plurality of power generation elements are electrically connected in series,
The oxidant electrode is connected to an oxidant flow path through which an oxidant gas flows,
The vent portion discharges carbon dioxide generated in the fuel electrode from the outer peripheral portion in the plane direction of the plurality of power generation elements to the outside, or enters the oxidant flow path connected to the adjacent oxidant electrode. It is provided to discharge,
The fuel electrode has an anode catalyst layer in close contact with the solid polymer electrolyte membrane, and an anode gas diffusion electrode provided on the anode catalyst layer,
The oxidant electrode has a cathode catalyst layer in close contact with the solid polymer electrolyte membrane, and a cathode gas diffusion electrode provided on the cathode catalyst layer,
The ventilation portion is a gap formed by the fuel electrode and the oxidant electrode ,
The vent is connected to the anode gas diffusion electrode;
The ventilation portion communicates with the outside at a planar outer peripheral portion of the plurality of power generation elements,
The carbon dioxide generated in the fuel electrode is discharged from the anode gas diffusion electrode to the outside through the ventilation part. The polymer electrolyte fuel cell according to claim 1,
The anode gas diffusion electrode covers the entire surface of the anode catalyst layer,
The anode gas diffusion electrode is wider in the plane direction than the anode catalyst layer,
The vent includes a void formed under a portion where the anode gas diffusion electrode protrudes from the anode catalyst layer,
The carbon dioxide generated in the fuel electrode is discharged from the lower part of the anode gas diffusion electrode that protrudes from the anode catalyst layer to the outside through the vent. A polymer electrolyte fuel cell according to claim 1 or 2,
Furthermore,
A porous body;
A gas-liquid separation membrane;
A fuel flow path;
Comprising
The porous body is provided on the electrical connecting portion and the insulating portion,
The gas-liquid separation membrane is provided from above the two porous bodies so as to cover the fuel electrode via a gap,
The fuel flow path is provided to be connected to a surface of the gas-liquid separation membrane opposite to the fuel electrode,
A void formed between the gas-liquid separation membrane and the fuel electrode communicates with the oxidant flow path connected to the adjacent oxidant electrode via the porous body,
Carbon dioxide generated in the fuel electrode is discharged to the oxidant flow path through a void formed between the gas-liquid separation membrane and the porous body. A polymer electrolyte fuel cell according to claim 1 or 2,
The electrical connection part is composed of a non-porous conductive material through which gas cannot pass,
The electrical connection portion is a polymer electrolyte fuel cell in which both the anode gas diffusion electrode and the cathode gas diffusion electrode are joined. A polymer electrolyte fuel cell according to claim 1 or 2,
The electrical connection part is a gas seal part having gas sealing properties,
The solid polymer fuel cell, wherein the electrical connection part, the anode gas diffusion electrode and the cathode gas diffusion electrode adjacent to each other through the electrical connection part are formed from a gas diffusion electrode which is a single member. The polymer electrolyte fuel cell according to claim 5,
The gas seal portion is provided with a gas seal portion vent hole for connecting between the anode gas diffusion electrode and the cathode gas diffusion electrode adjacent to each other,
The insulating portion is provided with an insulating portion vent hole that connects between the anode gas diffusion electrode and the cathode gas diffusion electrode adjacent to each other via the insulating portion,
Carbon dioxide generated at the fuel electrode is discharged from the anode gas diffusion electrode to the adjacent cathode gas diffusion electrode through the gas seal portion ventilation hole or the insulating portion ventilation hole.
The solid polymer fuel cell in which carbon dioxide discharged to the cathode gas diffusion electrode is discharged to the oxidant channel. A plurality of power generation elements;
An electrical connection;
An insulating part;
A vent,
Comprising
The plurality of power generation elements have a common solid polymer electrolyte membrane,
Each of the plurality of power generation elements further includes a fuel electrode and an oxidant electrode,
In each of the power generating elements, the fuel electrode and the oxidant electrode are arranged so as to sandwich the solid polymer electrolyte membrane,
The plurality of power generation elements are arranged such that fuel electrodes and oxidant electrodes are alternately arranged on the main surface of the solid polymer electrolyte membrane,
On the main surface of the solid polymer electrolyte membrane, between the adjacent fuel electrode and oxidant electrode, the electrical connection portion or the insulating portion is provided alternately,
On the back surface of the solid polymer electrolyte membrane, an oxidant electrode is disposed at a position facing the fuel electrode on the main surface, and a fuel electrode is disposed at a position facing the oxidant electrode on the main surface. ,
An insulating part is disposed at a position facing the electrical connection part on the main surface, and an electrical connection part is disposed at a position facing the insulating part on the main surface,
The electrical connection portion electrically connects between an adjacent fuel electrode and an oxidant electrode,
The insulating part insulates between an adjacent fuel electrode and an oxidant electrode,
The plurality of power generation elements are electrically connected in series,
The oxidant electrode is connected to an oxidant flow path through which an oxidant gas flows,
The vent, the carbon dioxide generated at the fuel electrode, provided so as to discharge the oxidant flow path connected to the adjacent contact the oxidant electrode,
Furthermore,
A porous body;
A gas-liquid separation membrane;
A fuel flow path;
Comprising
The porous body is provided on the electrical connecting portion and the insulating portion,
The gas-liquid separation membrane is provided from above the two porous bodies so as to cover the fuel electrode via a gap,
The fuel flow path is provided to be connected to a surface of the gas-liquid separation membrane opposite to the fuel electrode,
A void formed between the gas-liquid separation membrane and the fuel electrode communicates with the oxidant flow path connected to the adjacent oxidant electrode via the porous body,
Carbon dioxide generated in the fuel electrode is discharged to the oxidant flow path through a void formed between the gas-liquid separation membrane and the porous body. The polymer electrolyte fuel cell according to claim 7,
The fuel electrode has an anode catalyst layer in close contact with the solid polymer electrolyte membrane, and an anode gas diffusion electrode provided on the anode catalyst layer,
The oxidant electrode includes a cathode catalyst layer in close contact with the solid polymer electrolyte membrane, and a cathode gas diffusion electrode provided on the cathode catalyst layer. A plurality of power generation elements;
An electrical connection;
An insulating part;
A vent,
Comprising
The plurality of power generation elements have a common solid polymer electrolyte membrane,
Each of the plurality of power generation elements further includes a fuel electrode and an oxidant electrode,
In each of the power generating elements, the fuel electrode and the oxidant electrode are arranged so as to sandwich the solid polymer electrolyte membrane,
The plurality of power generation elements are arranged such that fuel electrodes and oxidant electrodes are alternately arranged on the main surface of the solid polymer electrolyte membrane,
On the main surface of the solid polymer electrolyte membrane, between the adjacent fuel electrode and oxidant electrode, the electrical connection portion or the insulating portion is provided alternately,
On the back surface of the solid polymer electrolyte membrane, an oxidant electrode is disposed at a position facing the fuel electrode on the main surface, and a fuel electrode is disposed at a position facing the oxidant electrode on the main surface. ,
An insulating part is disposed at a position facing the electrical connection part on the main surface, and an electrical connection part is disposed at a position facing the insulating part on the main surface,
The electrical connection portion electrically connects between an adjacent fuel electrode and an oxidant electrode,
The insulating part insulates between an adjacent fuel electrode and an oxidant electrode,
The plurality of power generation elements are electrically connected in series,
The oxidant electrode is connected to an oxidant flow path through which an oxidant gas flows,
The vent, the carbon dioxide generated at the fuel electrode, provided so as to discharge the oxidant flow path connected to the adjacent contact the oxidant electrode,
The fuel electrode has an anode catalyst layer in close contact with the solid polymer electrolyte membrane, and an anode gas diffusion electrode provided on the anode catalyst layer,
The oxidant electrode has a cathode catalyst layer in close contact with the solid polymer electrolyte membrane, and a cathode gas diffusion electrode provided on the cathode catalyst layer,
The electrical connection part is a gas seal part having gas sealing properties,
The electrical connection part, the anode gas diffusion electrode and the cathode gas diffusion electrode adjacent to each other through the electrical connection part are formed from a gas diffusion electrode that is a single member,
The gas seal portion is provided with a gas seal portion vent hole for connecting between the anode gas diffusion electrode and the cathode gas diffusion electrode adjacent to each other,
The insulating portion is provided with an insulating portion vent hole that connects between the anode gas diffusion electrode and the cathode gas diffusion electrode adjacent to each other via the insulating portion,
Carbon dioxide generated at the fuel electrode is discharged from the anode gas diffusion electrode to the adjacent cathode gas diffusion electrode through the gas seal portion ventilation hole or the insulating portion ventilation hole.
The solid polymer fuel cell in which carbon dioxide discharged to the cathode gas diffusion electrode is discharged to the oxidant channel. The polymer electrolyte fuel cell according to claim 8 or 9,
The anode gas diffusion electrode covers the entire surface of the anode catalyst layer,
The anode gas diffusion electrode is wider in the plane direction than the anode catalyst layer,
The vent includes a void formed under a portion where the anode gas diffusion electrode protrudes from the anode catalyst layer,
The carbon dioxide generated in the fuel electrode is discharged from the lower part of the anode gas diffusion electrode that protrudes from the anode catalyst layer to the outside through the vent.

Images