JP5657429B2 - Fuel cell - Google Patents

Description

  In the present invention, an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is laminated between a pair of separators, and an electrode reaction surface is provided between the electrolyte / electrode structure and each separator. The present invention relates to a fuel cell in which a reaction gas channel for supplying a reaction gas is formed along a surface direction, and a reaction gas communication hole penetrating in the stacking direction and communicating with the reaction gas channel is formed.

  For example, a solid polymer fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. This fuel cell has an electrolyte membrane / electrode structure (MEA) in which an anode electrode and a cathode electrode each made of an electrode catalyst (electrode catalyst layer) and porous carbon (diffusion layer) are provided on both sides of a solid polymer electrolyte membrane, respectively. Is constituted by a separator (bipolar plate). Normally, in a fuel cell, a fuel cell stack in which a predetermined number of power generation cells are stacked is used as, for example, an in-vehicle fuel cell stack.

  In this type of fuel cell, a fuel gas (reactive gas), for example, a gas mainly containing hydrogen (hereinafter also referred to as hydrogen-containing gas) is supplied to the anode electrode, while an oxidant is supplied to the cathode electrode. A gas (reactive gas), for example, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas) is supplied. In the fuel gas supplied to the anode electrode, hydrogen is ionized on the electrode catalyst and moves to the cathode electrode side through the electrolyte membrane. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy.

  In the above fuel cell, an internal manifold is often configured to supply a fuel gas and an oxidant gas, which are reaction gases, to the anode electrode and the cathode electrode of each of the stacked power generation cells. The internal manifold includes a reaction gas inlet communication hole and a reaction gas outlet communication hole provided so as to penetrate in the stacking direction of the power generation cells, and a reaction gas flow path (oxidant gas) for supplying the reaction gas along the electrode surface. The reaction gas inlet communication hole and the reaction gas outlet communication hole communicate with the inlet and the outlet of the flow channel and the fuel gas flow channel, respectively.

  By the way, in the oxidant gas flow path through which the oxidant gas flows, reaction product water is generated during power generation, while in the fuel gas flow path through which the fuel gas flows, condensed water is generated due to reverse diffusion or condensation of the reaction product water. Easy to do. At this time, if the condensed water (product water) adheres to the oxidant gas flow path or the fuel gas flow path, the flow of the oxidant gas or the fuel gas is hindered, causing a decrease in power generation performance. For this reason, it is necessary to reliably discharge condensed water from the oxidant gas flow path and the fuel gas flow path to the oxidant gas outlet communication hole and the fuel gas outlet communication hole (reaction gas outlet communication hole), respectively.

  Thus, for example, a fuel cell system disclosed in Patent Document 1 is known. This patent document 1 discloses a polymer electrolyte fuel cell system that generates power by an electrochemical reaction between a fuel gas supplied to a fuel electrode and oxygen in the air supplied to an air electrode. A fuel electrode passage switching valve for switching between supply and air; and a communication valve for communicating the air electrode and the fuel electrode, and the fuel electrode so as to supply air to the fuel electrode passage according to operating conditions. The gist of the invention is to perform air purging for purging the fuel electrode with air by switching the passage switching valve and communicating the communication valve.

  As a result, it is possible to blow away water accumulated in the fuel electrode by air instead of fuel gas, so that the amount of fuel consumed without being used for power generation can be reduced and fuel consumption can be improved. It is said.

Japanese Patent No. 3664150

  In Patent Document 1 described above, water or the like accumulated in the fuel electrode is blown off by air when the fuel cell system is started and when power generation is completed. For this reason, the mixed gas in which hydrogen gas, nitrogen gas, and oxygen are mixed easily remains in the reaction gas communication hole. Further, since hydrogen easily permeates and diffuses through the membrane, a mixed gas in which hydrogen gas, nitrogen gas, and oxygen are mixed easily remains in the reaction gas communication hole. Moreover, nitrogen and oxygen are likely to be mixed from the outside during the stop. Accordingly, the mixed gas flows into the electrode reaction surface from the reaction gas inlet communication hole at the time of start-up, while the backflow of the mixed gas may occur from the reaction gas outlet communication hole to the electrode reaction surface at the time of stop.

  Therefore, the reaction occurs at the site where the mixed gas first contacts the electrode catalyst layer, and substances such as hydrogen peroxide and radicals are easily generated at the end of the electrode catalyst layer. Thereby, there is a problem that local deterioration of the solid polymer electrolyte membrane occurs.

  The present invention solves this type of problem, and provides a fuel cell that can satisfactorily oxidize and reduce a mixed gas and reliably prevent a deterioration promoting substance from being supplied to an electrode reaction surface. The purpose is to provide.

  In the present invention, an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is laminated between a pair of separators, and an electrode reaction surface is provided between the electrolyte / electrode structure and each separator. The present invention relates to a fuel cell in which a reaction gas channel for supplying a reaction gas is formed along a surface direction, and a reaction gas communication hole penetrating in the stacking direction and communicating with the reaction gas channel is formed.

In this fuel cell, at the end of the electrolyte / electrode structure between the reaction gas communication hole and the electrode reaction surface, a notch in which a gas diffusion layer is cut from the electrolyte is adjacent to the reaction gas communication hole. In the notch, an insulating member having a gas barrier property and an insulating property is provided on the electrolyte, and is electrically isolated from the electrode and the electrolyte, and is separated from the end surface of the gas diffusion layer on the insulating member. a position, the electrode redox catalyst layer formed separately is provided with, on an insulating member and a redox catalyst layer, an insulating mesh member is found provided that the reaction gas has permeated and insulation .

Also, the fuel in the cell, the redox catalyst layer, Ru provided at the end of the adjacent electrolyte electrode assembly to reactant gas passage.

Furthermore, in this fuel cell, redox catalyst layer is Ru are either electrolyte et electrically insulated by interposing the insulating member.

Furthermore, in this fuel cell, a redox catalyst layer formed separately from the electrode is disposed adjacent to the reaction gas communication hole in the separator between the reaction gas communication hole and the electrode reaction surface.

Further, in this fuel cell, redox catalyst layer, the member having a gas barrier property to promote deterioration material and the electrolyte does not directly contact, Ru KaiSosu between the electrolyte and the redox catalyst layer.

According to the present invention, a redox catalyst layer is disposed between the reaction gas communication hole and the electrode reaction surface, and the mixed gas flowing from the reaction gas communication hole to the electrode reaction surface side is It is reduced oxidation by a redox catalyst layer. Therefore, no deterioration promoting substance is supplied to the electrode reaction surface, and deterioration of the electrolyte, particularly the solid polymer electrolyte membrane, can be satisfactorily suppressed.

It is a principal part disassembled perspective view of the fuel cell which concerns on the 1st Embodiment of this invention. It is front explanatory drawing of the 2nd separator which comprises the said fuel cell. It is the III-III sectional view taken on the line of the said fuel cell in FIG. FIG. 4 is a sectional view of the electrolyte membrane / electrode structure constituting the fuel cell, taken along line IV-IV in FIG. 1. It is the VV sectional view taken on the line of FIG. 1 of the said electrolyte membrane electrode structure. It is explanatory drawing of the manufacturing method of the said electrolyte and electrode structure. It is a principal part disassembled perspective view of the fuel cell which concerns on the 2nd Embodiment of this invention. It is front explanatory drawing of the 2nd separator which comprises the said fuel cell. It is front explanatory drawing of the 2nd separator which comprises the fuel cell which concerns on the 3rd Embodiment of this invention. It is front explanatory drawing of the 2nd separator which comprises the fuel cell which concerns on the 4th Embodiment of this invention. It is a principal part disassembled perspective view of the fuel cell which concerns on the 5th Embodiment of this invention. It is the XII-XII sectional view taken on the line of the said fuel cell in FIG. It is front explanatory drawing of the 2nd separator which comprises the said fuel cell. It is the XIV-XIV sectional view taken on the line of the said fuel cell in FIG.

  As shown in FIG. 1, the fuel cell 10 according to the first embodiment of the present invention includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 12, a first separator 14, and a second separator 16, which are arrows. They are stacked in the A direction (for example, the horizontal direction). By stacking the plurality of fuel cells 10 in the direction of arrow A, for example, an in-vehicle fuel cell stack is configured. The first separator 14 and the second separator 16 are metal separators or carbon separators.

  The fuel cell 10 has a horizontally long shape, and one end edge in the direction of arrow B communicates with each other in the direction of arrow A, which is the stacking direction, to supply an oxidant gas, for example, an oxygen-containing gas. A gas inlet communication hole (reaction gas communication hole) 18a and a fuel gas outlet communication hole (reaction gas communication hole) 20b for discharging a fuel gas, for example, a hydrogen-containing gas, are arranged in an arrow C direction (vertical direction). Provided.

  The other end edge of the fuel cell 10 in the direction of arrow B communicates with each other in the direction of arrow A, and discharges a fuel gas inlet communication hole (reactive gas communication hole) 20a for supplying fuel gas and oxidant gas. For this purpose, oxidant gas outlet communication holes (reactive gas communication holes) 18b are arranged in the direction of arrow C.

  A cooling medium inlet communication hole 22a for supplying a cooling medium is provided at one end edge (upper edge) in the arrow C direction of the fuel cell 10, and the other end edge of the fuel cell 10 in the arrow C direction. A cooling medium outlet communication hole 22b for discharging the cooling medium is provided at the (lower edge).

  An oxidant gas flow path (reaction gas flow path) 24 is provided on the surface 14 a of the first separator 14 facing the electrolyte membrane / electrode structure 12. The oxidant gas flow path 24 has a plurality of oxidant gas flow path grooves 24a, and the oxidant gas flow path grooves 24a extend in the direction of arrow B. An inlet buffer portion 24b is provided on the inlet side of the oxidant gas flow channel groove 24a, while an outlet buffer portion 24c is provided on the outlet side of the oxidant gas flow channel groove 24a. An inlet connection channel (bridge part) 26a is formed between the oxidant gas inlet communication hole 18a and the inlet buffer part 24b, and an outlet connection between the oxidant gas outlet communication hole 18b and the outlet buffer part 24c. A flow path (bridge portion) 26b is formed.

  As shown in FIG. 2, a fuel gas channel (reactive gas channel) 28 is provided on the surface 16 a of the second separator 16 facing the electrolyte membrane / electrode structure 12. Similar to the oxidant gas flow path 24, the fuel gas flow path 28 has a plurality of fuel gas flow path grooves 28 a extending in the direction of arrow B. An inlet buffer portion 28b is provided on the inlet side of the fuel gas passage groove 28a, while an outlet buffer portion 28c is provided on the outlet side of the fuel gas passage groove 28a. An inlet connection channel (bridge portion) 30a is formed between the fuel gas inlet communication hole 20a and the inlet buffer portion 28b, and an outlet connection channel between the fuel gas outlet communication hole 20b and the outlet buffer portion 28c. (Bridge part) 30b is formed.

  The first separator 14 and the second separator 16 integrally form a cooling medium flow path 32 on the surfaces 14b, 16b facing each other (see FIG. 1).

  On the surfaces 14a and 14b of the first separator 14, a first seal member 34 is integrally provided around the outer peripheral edge of the first separator 14 by injection molding or the like. A second seal member 36 is integrally provided on the surfaces 16a and 16b of the second separator 16 by injection molding or the like around the outer peripheral edge of the second separator 16. The first seal member 34 and the second seal member 36 are, for example, EPDM, NBR, fluororubber, silicon rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, or acrylic rubber, or a cushioning material. Or use packing material.

  The electrolyte membrane / electrode structure 12 has a horizontally long shape, and has an oxidant gas inlet communication hole 18a and a fuel gas inlet communication hole from the oxidant gas flow path 24 and the fuel gas flow path 28 above and below both ends in the direction of arrow B. Protrusions 12a, 12b, 12c and 12d projecting toward 20a, the oxidant gas outlet communication hole 18b and the fuel gas outlet communication hole 20b are provided. The protrusions 12a, 12b, 12c, and 12d are arranged to cover the inlet connection channel 26a, the inlet connection channel 30a, the outlet connection channel 26b, and the outlet connection channel 30b.

  The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane 38 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode electrode 40 and an anode electrode 42 sandwiching the solid polymer electrolyte membrane 38. Prepare.

  As shown in FIG. 3, the cathode electrode 40 and the anode electrode 42 include gas diffusion layers 40a and 42a made of carbon paper or the like, and porous carbon particles having a platinum alloy supported on the surface, the gas diffusion layers 40a and 42a. And electrode catalyst layers 40b and 42b formed by uniformly applying to the surface. The end portions of the gas diffusion layers 40a and 42a protrude outward from the end portions of the electrode catalyst layers 40b and 42b, and an electrode reaction surface is formed by the electrode catalyst layers 40b and 42b.

  As shown in FIG. 4, in the protruding portion 12b of the electrolyte membrane / electrode structure 12 (the same applies to the protruding portion 12d), the tip of the gas diffusion layer 42a on the anode electrode 42 side is cut away, so that the cathode electrode 40 side It is formed shorter than the gas diffusion layer 40a. A protective film 44 having a gas barrier property is disposed between the end face 42ae and the solid polymer electrolyte membrane 38 in contact with the cut end face 42ae of the gas diffusion layer 42a and the end polymer 42ae. The protective film 44 is made of, for example, an insulating material such as polyimide, polytetrafluoroethylene, polyethylene naphthalate, and the like, and the protective film 44 is an insulating mesh member 48 through which the redox catalyst layer 46 and the reaction gas permeate. Are stacked.

Progress redox catalyst layer 46, since rapidly it is necessary to water to capture the gas mixture _(O 2, _{N 2} and _{H 2,} etc.), oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) there is a need to be. For this reason, a catalyst with a large catalyst surface area and high oxidation-reduction reaction activity is preferable. The redox catalyst layer 46 is configured separately from the anode electrode 42, and, as shown in FIG. 2, the protrusion 12b is located between the fuel gas inlet communication hole 20a and the inlet buffer portion 28b, that is, at the inlet. It arrange | positions corresponding to the connection flow path 30a. The oxidation-reduction catalyst layer 46 is disposed in the protruding portion 12d between the fuel gas outlet communication hole 20b and the outlet buffer portion 28c, that is, corresponding to the outlet connection flow path 30b.

For example, a catalyst such as platinum, platinum-supported carbon, platinum-cobalt-supported carbon, or platinum-nickel-supported carbon is used for the oxidation-reduction catalyst layer 46, and is composed of the catalyst and an electrolyte or an adhesive. The oxygen reduction _{^{reaction, (ORR) 1 / 2O 2}} + 2H + + 2e - a → _{H 2} O, the hydrogen oxidation _{reaction, (HOR) H 2 → 2H} + + 2e - a.

  The insulating mesh member 48 has a heat resistant temperature of 70 ° C. or higher, and has oxidation resistance and insulating properties. The insulating mesh member 48 is made of, for example, PTFE (polytetrafluoroethylene), FEP (fluororesin in which tetrafluoroethylene and hexafluoropropylene are combined), PEN (polyethylene naphthalate), polyimide, or the like.

  The oxidation-reduction catalyst layer 46 is disposed between the protective film 44, which is an insulating member, and the insulating mesh member 48, and is separated from the cut end surface 42ae of the gas diffusion layer 42a by a distance S. The redox catalyst layer 46 is electrically insulated from the solid polymer electrolyte membrane 38 and the electrode catalyst layer 42 b of the anode electrode 42.

  As shown in FIG. 5, in the protrusion 12a of the electrolyte membrane / electrode structure 12 (the same applies to the protrusion 12c), the tip of the gas diffusion layer 40a on the cathode electrode 40 side is cut away, so that the anode electrode 42 side It is shorter than the gas diffusion layer 42a. A protective film 44 is disposed in contact with the cut end surface 40ae of the gas diffusion layer 40a and the solid polymer electrolyte membrane 38.

  The oxidation-reduction catalyst layer 46 is disposed between the protective film 44, which is an insulating member, and the insulating mesh member 48, and is separated by a distance S from the cut end surface 40ae of the gas diffusion layer 40a. The redox catalyst layer 46 is configured separately from the cathode electrode 40, and, as shown in FIG. 1, in the protrusion 12a, between the oxidizing gas inlet communication hole 18a and the inlet buffer 24b, that is, It arrange | positions corresponding to the inlet connection flow path 26a. The oxidation-reduction catalyst layer 46 is disposed in the protruding portion 12c between the oxidant gas outlet communication hole 18b and the outlet buffer portion 24c, that is, corresponding to the outlet connection channel 26b.

  A method of manufacturing the electrolyte membrane / electrode structure 12 in the fuel cell 10 configured as described above will be described below.

  First, as shown in FIG. 6A, a solid polymer electrolyte membrane 38 having notches at both ends in the longitudinal direction is prepared. 6 (b), electrode catalyst layers 42b and 40b are provided on both sides of the solid polymer electrolyte membrane 38, and protrusions that are the four corners of the solid polymer electrolyte membrane 38 are provided. In each of the portions 12a to 12d, a redox catalyst layer 46 is formed with a protective film 44 interposed on a predetermined surface side.

  Specifically, the electrode catalyst layers 42b and 40b are formed by forming catalyst particles in which platinum particles are supported on carbon black and using a solution containing a polymer electrolyte as an ion conductive binder. And a catalyst paste prepared by uniformly mixing the catalyst particles. This catalyst paste is printed, applied, or transferred onto both surfaces of the solid polymer electrolyte membrane 38 through a mask sheet with the electrode portions cut out, thereby forming the catalyst coating membrane 50. As the polymer electrolyte, a fluorine-based ion exchange membrane, for example, Nafion (trade name) manufactured by DuPont is used.

  Next, as shown in FIG. 6C, the catalyst coating film 50 has a gas applied to the catalyst coating film 50 in a state where the insulating mesh members 48 are installed in the oxidation-reduction catalyst layers 46 at the four corners. The diffusion layers 42a and 40a are integrated by hot pressing. Here, the gas diffusion layer 42a has bulging portions at diagonal positions corresponding to the protrusions 12a and 12c, while the gas diffusion layer 40a bulges at diagonal positions corresponding to the protrusions 12b and 12d. Part. Thereby, the electrolyte membrane / electrode structure 12 is manufactured.

  Further, the first separator 14 and the second separator 16 are disposed on both sides of the electrolyte membrane / electrode structure 12, and the fuel cell 10 is assembled by applying a tightening load (see FIGS. 1 and 2).

  The operation of the fuel cell 10 configured as described above will be described below.

  As shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 18a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 20a. Further, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet communication hole 22a.

  The oxidant gas is introduced into the oxidant gas flow path 24 of the first separator 14 from the oxidant gas inlet communication hole 18a. In the oxidant gas flow path 24, the oxidant gas is introduced into the inlet buffer part 24b from the inlet connection flow path 26a and then dispersed in the plurality of oxidant gas flow path grooves 24a. Therefore, the oxidant gas moves along the cathode electrode 40 of the electrolyte membrane / electrode structure 12 through each oxidant gas flow channel 24a.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 28 of the second separator 16 from the fuel gas inlet communication hole 20a. In the fuel gas channel 28, as shown in FIG. 2, after the fuel gas is introduced from the inlet connection channel 30a to the inlet buffer portion 28b, it is dispersed into the plurality of fuel gas channel grooves 28a. Further, the fuel gas moves along the anode electrode 42 of the electrolyte membrane / electrode structure 12 through each fuel gas channel groove 28a.

  Therefore, in the electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode electrode 40 and the fuel gas supplied to the anode electrode 42 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is called.

  Next, the oxidant gas supplied to and consumed by the cathode electrode 40 is discharged from the outlet buffer portion 24c to the oxidant gas outlet communication hole 18b through the outlet connection channel 26b. Similarly, the fuel gas consumed by being supplied to the anode electrode 42 is discharged from the outlet buffer portion 28c to the fuel gas outlet communication hole 20b through the outlet connection passage 30b (see FIG. 2).

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 22a is introduced into the cooling medium flow path 32 formed between the first and second separators 14 and 16 (see FIG. 1). In the cooling medium flow path 32, the cooling medium moves in the direction of gravity (arrow C direction). Therefore, the cooling medium is cooled over the entire power generation surface of the electrolyte membrane / electrode structure 12 and then discharged to the cooling medium outlet communication hole 22b.

  In the fuel cell 10, scavenging with air (oxidant gas) is performed on the oxidant gas passage 24 and the fuel gas passage 28 at the end of power generation. In some cases, the fuel gas is supplied to the fuel gas passage 28 and the oxidant gas passage 24 when the fuel cell 10 is started.

Therefore, in addition to the fuel gas inlet communication hole 20a and the fuel gas outlet communication hole 20b, the oxidant gas inlet communication hole 18a and the oxidant gas outlet communication hole 18b contain a mixture containing O ₂ , N _2, H _{2 and the} like. Gas is likely to be present.

  Therefore, in the first embodiment, as shown in FIGS. 2 and 4, in the protruding portion 12 b constituting the electrolyte membrane / electrode structure 12, between the fuel gas inlet communication hole 20 a and the inlet buffer portion 28 b, that is, A redox catalyst layer 46 is disposed corresponding to the inlet connection flow path 30a. For this reason, the mixed gas flowing into the fuel gas flow path 28 (electrode reaction surface side) from the fuel gas inlet communication hole 20a is reduced by oxygen by the oxidation-reduction catalyst layer 46, and the mixed gas disappears due to oxidation of hydrogen. .

  Moreover, the oxidation-reduction catalyst layer 46 is disposed corresponding to the inlet connection flow path 30a closest to the fuel gas inlet communication hole 20a. Therefore, the mixed gas flowing in from the fuel gas inlet communication hole 20a can be reliably captured in a narrow region before being diffused by the inlet buffer portion 28b. In addition, the redox catalyst layer 46 can secure a relatively long distance from the electrode catalyst layer 42b, and can suppress the influence of ion conduction.

  Thereby, it becomes possible to prevent the deterioration promoting substance such as hydrogen peroxide from being supplied to the fuel gas passage 28 as much as possible. For this reason, the effect that the deterioration of the electrode catalyst layer 42b and the solid polymer electrolyte membrane 38 constituting the anode electrode 42 can be satisfactorily suppressed can be obtained.

  Furthermore, as shown in FIG. 4, the oxidation-reduction catalyst layer 46 is disposed between the protective film 44, which is an insulating member, and the insulating mesh member 48, and is at a distance from the cut end surface 42ae of the gas diffusion layer 42a. They are separated by S. Therefore, the redox catalyst layer 46 has an advantage that it is electrically and reliably insulated to such an extent that substantially no current flows from the solid polymer electrolyte membrane 38 and the electrode catalyst layer 42b of the anode electrode 42.

  Similarly, the oxidation-reduction catalyst layer 46 is also provided between the fuel gas outlet communication hole 20b and the outlet buffer portion 28c, that is, in the outlet connection channel 30b, in the protruding portion 12d constituting the electrolyte membrane / electrode structure 12. Correspondingly arranged. As a result, the mixed gas flowing backward from the fuel gas outlet communication hole 20b to the fuel gas flow path 28 is reliably captured by the oxidation-reduction catalyst layer 46 and subjected to oxidation-reduction treatment. For this reason, the deterioration promoting substance such as hydrogen peroxide is not supplied to the fuel gas passage 28, and the deterioration of the electrode catalyst layer 42b and the solid polymer electrolyte membrane 38 can be satisfactorily suppressed. can get.

  On the other hand, in the protruding portion 12a, as shown in FIGS. 1 and 5, the redox catalyst layer 46 is formed between the oxidant gas inlet communication hole 18a and the inlet buffer portion 24b, that is, corresponding to the inlet connecting flow path 26a. In addition, the oxidation-reduction catalyst layer 46 is disposed in the protrusion 12c between the oxidant gas outlet communication hole 18b and the outlet buffer 24c, that is, corresponding to the outlet connection channel 26b. Therefore, in the oxidant gas flow path 24, the same effect as that of the fuel gas flow path 28 can be obtained.

  As shown in FIG. 7, the fuel cell 60 according to the second embodiment of the present invention includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 62 between the first separator 14 and the second separator 16. Hold it.

  The electrolyte membrane / electrode structure 62 has a horizontally long shape, and vertically extends at both ends in the direction of arrow B toward the inlet connection channel 26a, the inlet connection channel 30a, the outlet connection channel 26b, and the outlet connection channel 30b. Protruding protrusions 62a, 62b, 62c and 62d are provided. The protrusions 62a, 62b, 62c and 62d are arranged so as to cover a part of the inlet buffer part 24b, the inlet buffer part 28b, the outlet buffer part 24c and the outlet buffer part 28c.

  Similar to the first embodiment, the oxidation-reduction catalyst layer 46 is disposed on the protrusions 62a, 62b, 62c, and 62d. As shown in FIGS. 7 and 8, the oxidation-reduction catalyst layer 46 covers the inlet buffer portion 24b, the inlet buffer portion 28b, the outlet buffer portion 24c, and a part of the outlet buffer portion 28c. It arrange | positions in the position adjacent to the flow path 30a, the exit connection flow path 26b, and the exit connection flow path 30b.

  The oxidation-reduction catalyst layer 46 is set in a buffer region that is substantially the same as the connection channel width (see FIG. 8).

  The second embodiment configured as described above has an advantage that the same effect as that of the first embodiment can be obtained and the reaction area can be effectively secured.

  As shown in FIG. 9, in the fuel cell according to the third embodiment of the present invention, the oxidation-reduction catalyst layer 46 is provided in the entire buffer region, and as shown in FIG. 10, the fourth embodiment of the present invention. In the fuel cell according to the embodiment, the redox catalyst layer 46 is provided over the entire buffer region and the entire connection flow path. Therefore, in the third and fourth embodiments, the same effect as in the first and second embodiments can be obtained.

  As shown in FIG. 11, a fuel cell 70 according to a fifth embodiment of the present invention includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 72, a first separator 74, and a second separator 76. They are stacked in the A direction (for example, the horizontal direction).

The first separator 74 is provided with a redox catalyst layer 78 so as to cover the inlet connection channel 26a and the outlet connection channel 26b (see FIGS. 11 and 12). The oxidation-reduction catalyst layer 78 is formed on the surface of the first separator 74 by, for example, depositing platinum. In addition to vapor deposition, a coating method such as plating or ink jet can be employed. Between the first separator 74 and the oxidation-reduction catalyst layer 78, an insulating layer may be provided (not shown).

As shown in FIG. 13, the second separator 76 covers the inlet connection channel 30a and the outlet connection channel 30b and is provided with a redox catalyst layer 78. The oxidation-reduction catalyst layer 78 is formed by evaporating platinum, for example, on the surface of the second separator 76 (see FIG. 14). Between the second separator 76 and the oxidation-reduction catalyst layer 78, an insulating layer may be provided (not shown).

  The electrolyte membrane / electrode structure 72 has a horizontally long shape, and has an oxidant gas inlet communication hole 18a, a fuel gas inlet communication hole 20a, an oxidant gas outlet communication hole 18b, and a fuel gas outlet above and below both ends in the direction of arrow B. Protrusions 72a, 72b, 72c, and 72d that project toward the communication hole 20b are provided. The protrusions 72a, 72b, 72c and 72d are not provided with an oxygen reduction catalyst layer or the like.

  In the fifth embodiment configured as described above, the redox catalyst layer 78 is provided on the first separator 74 and the second separator 76, and oxygen reduction treatment of the mixed gas is performed by the redox catalyst layer 78. ing. Thereby, the fifth embodiment can obtain the same effects as those of the first embodiment.

  In the fifth embodiment, the oxidation-reduction catalyst layer 78 is disposed so as to cover the inlet connection channel 26a, the inlet connection channel 30a, the outlet connection channel 26b, and the outlet connection channel 30b. However, the present invention is not limited to this. Is not to be done. For example, as in the second embodiment, the oxidation-reduction catalyst layer 78 may be disposed so as to cover a part of the inlet buffer portion 24b, the inlet buffer portion 28b, the outlet buffer portion 24c, and the outlet buffer portion 28c.

Further, in the membrane electrode assembly 72, the protruding portions 72a, 72b, to 72c and 72d, for example, in order to favorably suppress the deterioration of the conductive electrode catalyst layer 40b, 42b and the solid polymer electrolyte membrane 38, the redox catalyst An insulating member (not shown) for electrically insulating the layer 78 is disposed between the oxidation-reduction catalyst layer 78 and the gas diffusion layers 40a and 42a, and a member (not shown) having gas barrier properties is provided. the solid polymer electrolyte membrane 38 and the electrode catalyst layer 40b, may be placed between 42b.

DESCRIPTION OF SYMBOLS 10, 60, 70 ... Fuel cell 12, 62, 72 ... Electrolyte membrane electrode assembly 12a, 12b, 12c, 12d, 62a, 62b, 62c, 62d, 72a, 72b, 72c, 72d ... Protrusion part 14, 16, 74, 76 ... Separator 18a ... Oxidant gas inlet communication hole 18b ... Oxidant gas outlet communication hole 20a ... Fuel gas inlet communication hole 20b ... Fuel gas outlet communication hole 22a ... Cooling medium inlet communication hole 22b ... Cooling medium outlet communication hole 24b 28b: Inlet buffer portion 24c, 28c ... Outlet buffer portion 26a, 30a ... Inlet connection flow channel 26b, 30b ... Outlet connection flow channel 28 ... Fuel gas flow channel 32 ... Cooling medium flow channel 38 ... Solid polymer electrolyte membrane 40 ... Cathode electrode 42 ... Asode electrodes 40a, 42a ... Gas diffusion layer 40b, 42b ... Electrode catalyst layer 44 ... Protective film 46, 78 ... Oxidation Based catalyst layer 48 ... insulating mesh member

Claims (2)

An electrolyte / electrode structure in which a pair of electrodes is provided on both sides of the electrolyte is laminated between a pair of separators, and the electrolyte / electrode structure and each separator are respectively along the surface direction of the electrode reaction surface. A reaction gas flow path for supplying a reaction gas, and a reaction gas communication hole penetrating in the stacking direction and communicating with the reaction gas flow path,
At the end portion of the electrolyte / electrode structure between the reaction gas communication hole and the electrode reaction surface, a notch in which a gas diffusion layer is cut out from the electrolyte is adjacent to the reaction gas communication hole. Formed,
In the notch, an insulating member having a gas barrier property and an insulating property is provided on the electrolyte, and on the insulating member and on the gas diffusion layer so as to be electrically insulated from the electrode and the electrolyte. An oxidation-reduction catalyst layer configured separately from the electrode is provided at a position separated from the end surface, and the insulating mesh is formed on the insulating member and the oxidation-reduction catalyst layer. fuel cell, characterized in that the member is provided. An electrolyte / electrode structure in which a pair of electrodes is provided on both sides of the electrolyte is laminated between a pair of separators, and the electrolyte / electrode structure and each separator are respectively along the surface direction of the electrode reaction surface. A reaction gas flow path for supplying a reaction gas, and a reaction gas communication hole penetrating in the stacking direction and communicating with the reaction gas flow path,
A redox catalyst layer configured separately from the electrode is disposed adjacent to the reaction gas communication hole at a portion of the separator between the reaction gas communication hole and the electrode reaction surface. ,
Between the redox catalyst layer and the separator is a fuel cell characterized by Rukoto insulating layer is provided.

Images