JP2020107397A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell having both electron conductivity and gas diffusivity. SOLUTION: At least one of a pair of separators has a plurality of non-channel portions that continuously project toward a gas diffusion layer between adjacent gas flow paths and come into contact with the gas diffusion layer. Is provided, and at least one non-flow path portion is adjacent to a throttle portion having a gas flow path having a first flow path cross-sectional area and a gas flow path having a second flow path cross-sectional area. The first flow path cross-sectional area includes an upstream portion arranged adjacent to the upstream of the drawing portion and a main portion arranged adjacent to the upstream of the upstream portion, and the first flow path cross-sectional area is the second flow path. Assuming that the distance between the main portion and the membrane electrode assembly is the first distance, which is smaller than the cross-sectional area, the distance between the throttle portion and the membrane electrode assembly is shorter than the first distance. It is formed so as to be a distance, and the distance between the upstream portion and the membrane electrode assembly is formed to be a third distance longer than the first distance. [Selection diagram] FIG. 4

Description

The present invention relates to a fuel cell unit.

A fuel cell is a system that obtains electric energy by supplying a fuel gas and an oxidant gas to an anode-side electrode and a cathode-side electrode to cause an electrochemical reaction.

Generally, a fuel cell has a stack structure in which a plurality of fuel cells are stacked. This fuel battery cell is composed of a membrane electrode assembly in which an anode side catalyst layer and a cathode side catalyst layer are provided on both sides of an electrolyte membrane, and a pair of separators sandwiching the membrane electrode assembly. In the above fuel cell, for the purpose of further improving gas diffusivity into the membrane electrode assembly, a gas diffusion layer that is a porous diffusion layer base material is arranged on both sides of the membrane electrode assembly to form a membrane electrode. In some cases, a gas diffusion layer assembly is formed and the membrane electrode gas diffusion layer assembly is sandwiched between a pair of separators. Here, in Patent Document 1, a gas flow path as a gas flow path forming body is formed on the side of the separator facing the membrane electrode gas diffusion layer assembly, and the gas flow direction in the gas flow path is increased. It is disclosed that by providing a plurality of protrusions extending in the orthogonal direction, the protrusions function as constrictions for the flow path and the reaction gas can be uniformly diffused in the gas diffusion layer.

JP, 2017-228482, A

Here, in order to further improve the gas diffusibility into the gas diffusion layer, it is necessary to facilitate the diffusion of the reaction gas staying upstream of the narrowed portion into the gas diffusion layer. Therefore, it is necessary to increase the porosity of the gas diffusion layer. However, when the porosity of the gas diffusion layer is large, the porous base material becomes sparse, and the electron conductivity decreases. Therefore, there has been a demand for a technique that achieves both electronic conductivity and gas diffusivity in the vicinity of the narrowed portion.

In order to achieve at least a part of the above-mentioned subject, the present invention can be implemented as the following modes.

According to one aspect of the present invention, a pair of gas diffusion layers that are porous diffusion layer base materials are disposed on both sides of the membrane electrode assembly and the membrane electrode assembly, and the pair of gas diffusion layers A pair of separators arranged on both sides, and a fuel cell comprising the pair of separators, a reaction gas supply manifold and a reaction gas discharge manifold penetrating in the thickness direction are arranged, At least one of the separators is provided with a plurality of gas flow passages that allow the reaction gas to flow from the reaction gas supply manifold toward the reaction gas discharge manifold, and the plurality of gas flow passages are adjacent to each other. A plurality of non-flow passage portions that are in contact with the gas diffusion layer are provided between the matching gas flow passages, and the non-flow passage portions are continuously provided along the plurality of gas flow passages. At least one non-flow passage portion of the plurality of non-flow passage portions has a second flow passage cross-sectional area and a throttle portion adjacent to the gas flow passage having the first flow passage cross-sectional area. An upstream part disposed adjacent to a gas flow path and adjacent to an upstream side of the throttle part; and a main part arranged adjacent to an upstream side of the upstream part, wherein the first flow path cross-sectional area is If the distance between the main portion and the membrane electrode assembly is smaller than the second flow path cross-sectional area and the distance between the main portion and the membrane electrode assembly is a first distance, the distance between the narrowed portion and the membrane electrode assembly is the first. The second distance is shorter than the distance, and the distance between the upstream portion and the membrane electrode assembly is a third distance longer than the first distance.

According to this aspect, since the plurality of non-flow passage portions provided in the separator have three types of heights different from the first distance, the second distance, and the third distance, the gas diffusion contacting the separator is increased. The contact pressure acting on the layers is different. Therefore, the thicknesses of the gas diffusion layers in contact with the plurality of non-flow passage portions adjacent to the main portion, the throttle portion, and the upstream portion are different. The gas diffusion layer is a porous diffusion layer base material. The higher the contact surface pressure at which the gas diffusion layer works, the smaller the thickness of the gas diffusion layer, so the conductive porous base material becomes denser. While the electron conductivity is improved, the porosity of the gas diffusion layer is decreased and the gas diffusivity is decreased. The second distance is higher than the first distance and the third distance, and the thickness of the gas diffusion layer is thin. Therefore, the contact surface pressure acting on the gas diffusion layer in the throttle portion adjacent to the upstream portion is high and the thickness of the gas diffusion layer is thin, so that the porosity of the gas diffusion layer is small and the electron conductivity is good. On the other hand, the contact surface pressure in the upstream portion is lower than that in the throttle portion and the main portion, and the thickness of the gas diffusion layer is large. For this reason, in the upstream portion where the reaction gas flowing through the gas flow passage tends to stay in the throttle portion, the reaction gas is more likely to diffuse into the gas diffusion layer than in the throttle portion and the main portion. Since the high contact pressure portion and the low contact surface pressure portion are provided close to each other, the reaction gas diffused in the reaction gas diffused in the part of the gas diffusion layer that is in contact with the upstream portion where the reaction gas easily diffuses It can diffuse to a part of the gas diffusion layer that is in contact with the difficult throttle. On the other hand, since the diaphragm having high electron conductivity is arranged adjacent to the upstream portion having low electron conductivity, the electron conductivity is also uniform in the vicinity of the diaphragm. Therefore, it is possible to achieve both electron conductivity and gas diffusivity in the vicinity of the narrowed portion.

In the fuel cell separator of the above aspect, at least one non-flow passage part of the plurality of non-flow passage parts has the second distance and the third distance in the throttle part and the upstream part. It may have a surface parallel to the membrane electrode assembly and a surface which is not perpendicular to the membrane electrode assembly in which the height continuously changes up to the second distance or the third distance.

According to this mode, since the height changes continuously, it is possible to suppress the occurrence of a gap between the gas diffusion layer and the separator. Therefore, the electronic conductivity can be further improved.

In the fuel cell separator of the above aspect, at least one non-flow passage portion of the plurality of non-flow passage portions is perpendicular to the membrane electrode assembly of the non-flow passage portion and with respect to the gas flow direction. A cross section in a parallel plane may have an arc shape at the narrowed portion and the upstream portion.

According to this mode, since the throttle portion and the upstream portion have an arc shape, it is possible to suppress the generation of a gap between the gas diffusion layer and the separator. Therefore, the electronic conductivity can be further improved.

It is a section explanatory view of a fuel cell concerning this embodiment. It is a top view showing a schematic structure of a separator concerning this embodiment. It is a cross-sectional view of the fuel cell according to the present embodiment, which is a view for explaining the flow of gas. FIG. 4 is an enlarged plan view of a region C shown in FIG. 2 and a sectional view taken along the line AA of FIG. FIG. 9 is an enlarged plan view of a region C shown in FIG. 2 in a modified example and a cross-sectional view taken along the line BB of FIG. It is a top view which shows schematic structure of the separator concerning a modification.

Hereinafter, the fuel cell separator of the present invention will be described in detail with reference to the drawings. The following embodiments are merely suitable application examples, and the scope of application of the present invention is not limited thereto.

FIG. 1 is a cross-sectional view showing the structure of a fuel battery cell 100 as one embodiment of the present invention. The fuel cell unit 100 includes a membrane electrode assembly 10, two gas diffusion layers 20, and a pair of separators, that is, an anode side separator 30 and a cathode side separator 40. In the membrane electrode assembly 10, an anode side catalyst layer 11 and a cathode side catalyst layer 12 are arranged on both sides of an electrolyte membrane 13, respectively. The electrolyte membrane 13 is a solid polymer membrane that exhibits good proton conductivity in a wet state. In the present embodiment, the electrolyte membrane 13 is composed of a fluorine resin ion exchange membrane. The anode side catalyst layer 11 and the cathode side catalyst layer 12 are made of a catalyst that promotes a chemical reaction between the fuel gas and the oxidant gas.

Gas diffusion layers 20 are laminated on both sides of the membrane electrode assembly 10. The membrane electrode assembly 10 and the two gas diffusion layers 20 form a membrane electrode gas diffusion layer assembly (hereinafter referred to as “MEGA”) 21. The gas diffusion layer 20 is a layer that diffuses the reaction gas used for the electrode reaction along the surface direction of the electrolyte membrane 13, and is made of a porous diffusion layer base material. As the diffusion layer base material, a porous base material having conductivity and gas diffusivity such as a carbon fiber base material or a graphite fiber base material is used. The gas diffusion layer 20 is subjected to water repellent treatment on the membrane electrode assembly 10 side.

An uneven surface is formed on the two separators 30 and 40, and the gas flow paths 32 and 42 are formed by bringing the upper surfaces 36 and 46 of the convex portions of the uneven surface into contact with the gas diffusion layer 20. The reaction gas flows into the concave portions of the uneven surface, and almost no reaction gas flows into the upper surfaces 36 and 46 of the convex portions that are in contact with the gas diffusion layer 20, and is therefore referred to as “non-flow passage portion”. The gas flow paths 32 and 42 allow the reaction gas to flow from the reaction gas supply manifolds 470 and 480 described below toward the reaction gas discharge manifolds 472 and 482 described below. In the anode-side separator 30, the anode-side gas flow channel 32 is formed on the anode-side surface of the MEGA 21 between the plurality of anode-side non-flow channel portions 36, and on the opposite side thereof, a plurality of streaky cooling medium flow channels 34 are provided. Are formed. The cathode-side separator 40 has a cathode-side gas passage 42 formed between a plurality of cathode-side non-passage portions 46 on the cathode-side surface of the MEGA 21, and the cathode-side non-passage portion 46 and the gas diffusion layer 20 are Are in contact. The separators 30 and 40 are formed by press-molding a metal plate made of stainless steel, titanium, or an alloy thereof, for example.

FIG. 2 is a plan view showing a schematic configuration of the cathode side separator 30 in the present embodiment. The x direction in FIG. 2 corresponds to the “gas flow direction”, and the z direction corresponds to the “stacking direction”. FIG. 3 is a cross-sectional view of the fuel cell according to the present embodiment and is a diagram for explaining the gas flow. As shown in FIG. 2, the cathode-side separator 30 is, for example, a substantially rectangular plate-shaped member, has a power generation region 50 facing the MEGA 21 in the central portion, a plurality of openings 470, 472, 480, 482 in the outer edge portion. 490 and 492 are provided. These openings 470, 472, 480, 482, 490, 492 are manifolds for the reaction gas and the cooling medium, and are through holes penetrating in the thickness direction of the separator. Each of the manifolds is arranged such that the flow direction of the fuel gas and the flow direction of the oxidant gas in the power generation region 50 face each other across the electrolyte membrane 13 and intersect each other. Specifically, the fuel gas supply manifold 470, the oxidant gas supply manifold 480, and the cooling medium supply manifold 490 are arranged on the same side with respect to the power generation region 50, that is, on the right side of the drawing, and the fuel gas discharge manifold 472 is provided. The oxidant gas discharge manifold 482 and the cooling medium discharge manifold 492 are arranged on the opposite side, that is, on the left side of the drawing. The reaction gas, that is, the fuel gas and the oxidant gas, respectively flow from the fuel gas supply manifold 470 or the oxidant gas supply manifold 480 toward the fuel gas exhaust manifold 472 or the oxidant gas exhaust manifold 482. Here, in this specification, the fuel gas supply manifold 470 side of the anode side separator 30 or the oxidant gas supply manifold 480 side of the cathode side separator 40 is referred to as “upstream”. Further, the fuel gas exhaust manifold 472 side of the anode side separator 30 or the oxidant gas exhaust manifold 482 side of the cathode side separator 40 is referred to as “downstream”.

Here, the fuel gas supply manifold 470 and the fuel gas discharge manifold 472 are formed at positions diagonal to each other across the power generation region 50. The same applies to the oxidizing gas supply manifold 480, the oxidizing gas discharge manifold 482, the cooling medium supply manifold 490, and the cooling medium discharge manifold 492. It should be noted that the arrangement of the manifolds 470, 472, 480, 482, 490, 492 for the reaction gas and the cooling medium may have other configurations.

In addition, the cathode-side separator 40 is formed with cathode-side gas flow paths 42 that extend linearly in parallel with each other along the gas flow direction (the x direction in FIG. 2), and between the cathode-side gas flow paths 42. A plurality of cathode-side non-flow passage portions 46 are formed in the direction of projecting to the surface side in contact with the gas diffusion layer 20, that is, in the stacking direction (z direction in FIG. 2). The height of the cathode-side non-flow passage portion 46 in the stacking direction is constant in the direction orthogonal to the gas flow direction (the y direction in FIG. 2 ). Each cathode-side gas flow passage 42 has a constant width and a constant flow passage cross-sectional area except for the throttle portion 43 described later. By making the cathode-side gas flow path 42 linear, the efficiency of discharging the liquid water generated by the electrochemical reaction in the MEGA 21 can be increased. The cathode-side gas flow channel 42 is preferably formed so as to extend straight from the oxidant gas supply manifold 480 to the oxidant gas discharge manifold 482 between both ends of the power generation region 50. With such a configuration, liquid water can be discharged more easily.

As shown in FIG. 2, the cathode-side gas flow passage 42 has a portion where the flow passage cross-sectional area is reduced by providing a protrusion in a direction (y direction in FIG. 2) orthogonal to the gas flow direction, The cathode-side non-flow passage portion 46 adjacent to this portion is used as the throttle portion 43. Here, the flow passage cross-sectional area means the cross-sectional area of one gas flow passage of the plurality of cathode side gas flow passages 42 provided in the cathode side separator 40. In the cathode-side non-flow passage portion 46, the portion arranged adjacent to the upstream side of the throttle portion 43 is the upstream portion 44. In the present embodiment, the cathode side non-flow passage portion 46 excluding the throttle portion 43 and the upstream portion 44 is the main portion 45. By providing the portion for reducing the flow passage cross-sectional area in the cathode gas flow passage 42, pressure loss occurs in the oxidant gas flowing through the cathode gas flow passage 42, and the flow velocity of the oxidant gas becomes slow. Therefore, it stays in the upstream portion 44 arranged adjacent to the upstream side of the throttle portion 43. In this way, by causing the oxidant gas to stay in the cathode-side gas flow channel 42, the oxidant gas can be made to further penetrate into the gas diffusion layer 20, as shown in FIG. Therefore, the oxidant gas is easily diffused in the gas diffusion layer 20, and the concentration of the oxidant gas in the cathode side catalyst layer 12 in which the oxidant gas is diffused from the gas diffusion layer 20 can be improved.

FIG. 4 is an enlarged plan view of the region C shown in FIG. 2 and a sectional view taken along the line AA of FIG. FIG. 4A is an enlarged plan view of the area C shown in FIG. Note that, in FIG. 4A, arrows showing the flow of the oxidant gas in the cathode side separator 40 are shown. As shown in FIG. 4A, the cathode-side non-flow passage portion 46 is provided with a throttle portion 46 adjacent to the portion of the cathode-side gas flow passage 42 where the flow passage cross-sectional area is reduced. As described above, the provision of such a narrowed portion 43 facilitates diffusion into the gas diffusion layer 20, so that the concentration of the oxidant gas in the gas diffusion layer 20 changes from upstream to downstream in the gas flow direction. It becomes uniform at each stage. Therefore, it is possible to avoid deterioration of the power generation characteristics of the fuel cell unit 100. It is effective to provide such a narrowed portion 43 on the downstream side of the cathode side gas flow channel 42 where the oxidant gas concentration decreases.

4B is a cross-sectional view of the cathode-side non-flow passage portion 46 provided in the cathode-side separator 40 taken along the line AA of FIG. FIG. 4C is a diagram in which the cathode-side separator 43, the gas diffusion layer 20, and the membrane electrode assembly 10 are superposed. Here, the distance between the main portion 45 of the cathode-side non-flow passage portion 46 and the membrane electrode assembly 10 is a first distance L1, and the cathode-side non-flow passage adjacent to the throttle portion 43 of the cathode-side non-flow passage portion 46. The distance between the portion 46 and the membrane electrode assembly 10 is the second distance L2, and the distance between the cathode side non-flow passage portion 46 adjacent to the upstream portion 44 of the cathode side non-flow passage portion 46 and the membrane electrode assembly 10 is the second distance L2. The distance L3 is 3. In the cathode-side non-flow passage portion 46 formed in the cathode-side separator 40 in the present embodiment, the second distance L2 is larger than the first distance L1 as shown in FIGS. 4(b) and 4(c). It is short and the third distance L3 is formed to be longer than the first distance L1. That is, the cathode-side non-flow passage portion 46 adjacent to the narrowed portion 43 projects the highest in the stacking direction with respect to the gas diffusion layer 20. On the other hand, the cathode-side non-flow passage portion 46 adjacent to the upstream portion 44 is the least protruding.

In the power generation region 50, the cathode-side non-flow passage portion 46 provided in the cathode-side separator 43 is different from the membrane electrode assembly 10 in the first distance L1, the second distance L2, and the third distance L3. By having three types of distances, the magnitude of the contact surface pressure acting on the gas diffusion layer 20 in contact with the cathode side separator 40 is different. Therefore, as shown in FIG. 4C, the thickness of the gas diffusion layer 20 in contact with the cathode-side non-flow passage portion 46 varies depending on the location. Since the gas diffusion layer 20 is made of a porous diffusion layer base material, the thickness of the gas diffusion layer 20 decreases as the contact surface pressure acting on the gas diffusion layer 20 increases. When the thickness of the gas diffusion layer 20 is reduced, the conductive porous base material becomes denser, so that the electron conductivity is improved, while the porosity of the gas diffusion layer 20 is reduced, so that the gas diffusion property is reduced. .. Therefore, the distance between the main portion 45 and the membrane electrode assembly 10 is set to the first distance L1 which is the distance between the membrane electrode assembly 10 in which both electron conductivity and gas diffusivity are compatible. In the present embodiment, the distance between the main part 45 and the membrane electrode assembly 10 is constant at the first distance L1.

In the cathode side separator 40 in the present embodiment, as shown in FIG. 4C, the second distance L2 in the narrowed portion 43 is shorter than the first distance L1 and the third distance L3, The gas diffusion layer 20 has the smallest thickness. The second distance L2 is preferably 0.6 times or more and 0.9 times or less, and more preferably 0.7 times or more and 0.8 times or less of the first distance L1. Therefore, the contact surface pressure acting on the gas diffusion layer 20 in the narrowed portion 43 becomes high, so that the porosity of the gas diffusion layer 20 becomes small and the electron conductivity becomes good. However, in the narrowed portion 43, since the porosity of the gas diffusion layer 20 is small, the oxidant gas is difficult to diffuse into the gas diffusion layer 20. Further, the cathode-side gas flow passage 42 adjacent to the throttle portion 43 has a reduced flow passage cross-sectional area, and the pressure loss generated when the oxidant gas flows through the cathode-side gas flow passage 42 is large. .. As a result, the oxidant gas is more likely to stay in the upstream portion 44 adjacent to the upstream of the throttle portion 43.

Here, the third distance L3 in the upstream portion 44 is longer than the first distance L1 and the second distance L2, and the thickness of the gas diffusion layer 20 is the largest. The third distance L3 is preferably 1.1 times or more and 1.3 times or less, and more preferably 1.1 times or more and 1.2 times or less than the first distance L1. Therefore, since the contact surface pressure acting on the gas diffusion layer 20 is low, the gas diffusion layer 20 has a high porosity. Therefore, the oxidant gas is likely to diffuse into the gas diffusion layer 20 in the upstream portion 44 where the oxidant gas is likely to stay.

As described above, the cathode-side separator 40 in the present embodiment increases the pressure loss generated in the cathode-side gas flow path 42 at the throttle portion 43, while diffusing the oxidant gas into the gas diffusion layer 20 at the upstream portion 44. The ease is also increased. As a result, the oxidizing gas diffused in the gas diffusion layer 20 in the upstream portion 44 diffuses in the portion of the gas diffusion layer 20 facing the narrowed portion 43. As a result, the concentration of the oxidant gas diffused in the gas diffusion layer 20 adjacent to the throttle portion 43 and the upstream portion 44 becomes uniform, and stable gas diffusibility can be obtained in the vicinity of the throttle portion 43. On the other hand, in the narrowed portion 43, the contact surface pressure acting on the gas diffusion layer 20 is high, and the gas diffusion layer 20 is thin, so that the electron conductivity is high. The narrowed portion 43 having high electron conductivity is located in the vicinity of the upstream portion 44 having a low contact surface pressure acting on the gas diffusion layer 20 and a low electron conductivity. As a result, stable electron conductivity can be obtained near the narrowed portion 43. As described above, in the cathode-side separator 40, both electron conductivity and gas diffusivity can be achieved in the vicinity of the narrowed portion 43.

In the above-described embodiment, the first distance of the cathode side non-flow passage portion 46 adjacent to the throttle portion 43 is formed so as not to change, and the same applies to the second distance and the third distance. The present disclosure is not limited to this. FIG. 5 is an enlarged plan view of a region C shown in FIG. 2 in a modified example and a cross-sectional view taken along the line BB of FIG. FIG. 5A is an enlarged plan view of the region C shown in FIG. 2 similarly to FIG. 5B and 5C are cross-sectional views taken along the line BB of FIG. 5A in the modified example. As shown in FIG. 5B, the cathode-side non-flow passage portion 46 has a plane parallel to the MEGA 21 having the second distance and the third distance, and the first distance to the third distance or the second distance. May have a surface that is not perpendicular to the MEGA 21 whose height continuously changes from the first to the third distance. In FIG. 5B, the cross section in a plane perpendicular to the MEGA 21 is formed to be linear, but the present invention is not limited to this, and a plane in which the height continuously changes has a cross section taken along line BB. It may be an upwardly convex or downwardly convex arc shape. Further, as shown in FIG. 5C, the cross section of the cathode non-flow passage portion 46 adjacent to the throttle portion 43 and the upstream portion 44 in a plane perpendicular to the MEGA 21 may have an arc shape. In the case of such a configuration, it is possible to suppress the formation of a gap between the gas diffusion layer 20 and the gas diffusion layer 20. Therefore, the electronic conductivity can be further improved.

In the above embodiment, the cathode-side gas flow channel 42 is a straight flow channel that extends linearly from the oxidant gas supply manifold 480 to the oxidant gas discharge manifold 482, but the present disclosure is not limited to this. For example, the cathode-side gas passage 42 may be a serpentine passage in which the gas flow direction is reversed a plurality of times. Further, the cathode-side gas flow channel 42 may meander to the extent that the throttle portion 43 is provided.

In the above-described embodiment, the throttle portion 43 provided in the cathode-side gas flow passage 42 has a direction in which the cathode-side non-flow passage portions 46 adjacent to the cathode-side gas flow passage 42 are orthogonal to the gas flow direction. Although the width of the cathode-side gas flow passage 42 is reduced and the flow passage cross-sectional area is reduced by providing the protrusion protruding in the y direction in FIG. 2, the present disclosure is not limited to this. For example, only one of the cathode-side non-flow passage portions 46 adjacent to the cathode-side gas flow passage 42 is provided with a protrusion that protrudes in a direction orthogonal to the gas flow direction. The road cross-sectional area may be reduced. Further, the cathode-side non-flow passage portion 46 adjacent to the cathode-side gas flow passage 42 is not provided with a protrusion protruding in the direction orthogonal to the gas flow direction (the y direction in FIG. 2), and the cathode-side gas flow The flow passage cross-sectional area may be reduced by changing the height of the bottom of the passage 42. Further, these may be appropriately combined to reduce the flow passage cross-sectional area of the cathode-side gas flow passage 42.

In the above embodiment, the throttle portions 43 are provided at a plurality of locations in each of the plurality of cathode side gas flow paths 42, but only one throttle portion 43 may be provided in each of the plurality of cathode side gas flow paths 42. However, one may be provided only in one cathode-side gas flow channel 42. The throttle portion 43 is preferably provided at a position other than the outlet of the cathode gas flow channel 42. As a result, it is possible to prevent the phenomenon in which the outlet of the cathode side gas flow channel 42 is blocked by the liquid water and the oxidant gas is less likely to flow into the cathode side gas flow channel 42.

In the above embodiment, the diaphragm portions 43 are provided symmetrically, but the present disclosure is not limited to this. As shown in FIG. 6, more throttle portions 43 may be provided downstream of the cathode-side gas flow passage 42 than upstream. Since the oxidant gas flowing through the cathode side gas flow channel 42 diffuses into the gas diffusion layer 20, the gas concentration decreases as it goes downstream. According to this mode, the throttle portion 43 is provided on the downstream side where the gas concentration of the oxidant gas is lowered, and the contact surface pressure of the cathode side non-flow passage portion 46 is changed so as to correspond to the throttle portion 43. The height has been changed. Therefore, it is possible to efficiently diffuse the oxidant gas into the gas diffusion layer 20 with a small number of the narrowed portions 43.

In the above-described embodiment, the portion of the cathode-side non-flow passage portion 46 excluding the throttle portion 43 and the upstream portion 44 is the main portion 45, but the present disclosure is not limited to this. The main portion 45 is arranged adjacent to the upstream side of the upstream portion 44 of the cathode-side non-flow passage portion 46, and the distance between the main portion 45 and the membrane electrode assembly 10 is the second distance L2 and the third distance. It may be a distance from the distance L3.

In the above embodiment, the height of the cathode-side non-flow passage portion 46 in the stacking direction was constant in the direction orthogonal to the gas flow direction, but the present disclosure is not limited to this. The height of the cathode-side non-flow passage portion 46 in the stacking direction may be substantially constant in the direction orthogonal to the gas flow direction. The height in the stacking direction being substantially constant in the direction perpendicular to the gas flow direction means that the stacking is within a predetermined range (-5% to +5%) over the direction perpendicular to the gas flow direction. It means the height in the direction, and the height in the stacking direction may be constant in the direction orthogonal to the gas flow direction, or may be slightly changed.

In the above-described embodiment, the throttle portion 43 is provided in the cathode gas flow passage 42 formed in the cathode separator 40, and the height of the cathode non-passage portion 46 is changed corresponding to the provided throttle portion 43. The present disclosure is not limited to this. You may apply to the anode side gas flow path 32 formed in the anode side separator 30.

It should be noted that the present disclosure is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each mode described in the section of the summary of the invention are provided in order to solve some or all of the above-mentioned problems, or one of the effects described above. Substitutions and combinations may be made as appropriate to achieve part or all. If the technical features are not described as essential in this specification, they can be deleted as appropriate.

100... Fuel cell 10... Membrane electrode assembly 11... Anode side catalyst layer 12... Cathode side catalyst layer 13... Electrolyte membrane 20... Gas diffusion layer 21... Membrane electrode gas diffusion layer assembly 30... Anode side separator 32... Anode side Gas channel 34... Cooling medium channel 36... Anode-side non-channel section 40... Cathode-side separator 42... Cathode-side gas channel 43... Restriction section 44... Upstream section 45... Main section 46... Cathode-side non-channel section 470 Fuel gas supply manifold 472 Fuel gas discharge manifold 480 Oxidant gas supply manifold 482 Oxidant gas discharge manifold 490 Cooling medium supply manifold 492 Cooling medium discharge manifold 50 Power generation area

Claims (3)

A pair of gas diffusion layers that are porous diffusion layer base materials are arranged on both sides of the membrane electrode assembly and the membrane electrode assembly, and a pair of separators arranged on both sides of the pair of gas diffusion layers. And a fuel cell unit comprising:
The pair of separators, a reaction gas supply manifold and a reaction gas discharge manifold penetrating in the thickness direction are arranged,
At least one separator of the pair of separators, a plurality of gas flow passages for allowing a reaction gas to flow from the reaction gas supply manifold toward the reaction gas discharge manifold are arranged,
In the plurality of gas flow paths, between adjacent gas flow paths, a plurality of non-flow path portions that contact the gas diffusion layer are provided,
The non-flow path portion is continuously provided along the plurality of gas flow paths,
At least one non-flow passage portion of the plurality of non-flow passage portions is a throttle portion adjacent to a gas flow passage having a first flow passage cross-sectional area, and a gas flow passage having a second flow passage cross-sectional area. Adjacent to each other, an upstream portion disposed adjacent to the upstream portion of the narrowed portion, and a main portion disposed adjacent to the upstream portion of the upstream portion,
The first channel cross-sectional area is smaller than the second channel cross-sectional area,
When the distance between the main part and the membrane electrode assembly is a first distance,
It is formed such that the distance between the narrowed portion and the membrane electrode assembly is a second distance shorter than the first distance,
The fuel cell unit, which is formed such that a distance between the upstream portion and the membrane electrode assembly is a third distance longer than the first distance. At least one non-flow passage portion of the plurality of non-flow passage portions has a surface parallel to the membrane electrode assembly having the second distance and the third distance in the throttle portion and the upstream portion. 2. The fuel cell according to claim 1, further comprising: a surface that is not perpendicular to the membrane electrode assembly, the height of which continuously changes up to the second distance or the third distance. .. At least one non-flow passage portion of the plurality of non-flow passage portions has a cross-section in a plane perpendicular to the membrane electrode assembly of the non-flow passage portion and parallel to the gas flow direction. The fuel cell according to claim 1, wherein the portion and the upstream portion have an arc shape.

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