Separator for fuel battery

Abstract

To provide a separator for a fuel battery, capable of improving performance of the fuel battery.SOLUTION: A first part 50 includes a first projection 51 and a first groove 52 that are extended to a first direction X. The first projection 51 and the first groove 52 are arranged so as to be alternately arranged to a second direction Y. A projection end of the first projection 51 is contacted to a power generation part of a fuel battery. A second part 60 includes a second projection 61 and a second groove 62 that are extended to the first direction X. The second projection 61 and the second groove 62 are arranged in an aspect that they are alternately arranged to a second direction Y. A top surface of the second projection 61 is not contacted to the power generation part. Each of parts 50 and 60 is integrally formed in a state where they are arranged to the first direction X. Each of the plurality of first projections 51 and each of the plurality of second projections 61 are coupled to form a plurality of projection parts 31. Each of the plurality of first grooves 52 and each of the plurality of second grooves 62 are coupled to form the plurality of groove parts 32. In a boundary part of each of the parts 50 and 60, a position of the first groove 52 and a position of the second groove 62 are deviated in the second Y direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a separator for a fuel cell. [Background technology]

[0002] Conventionally, a polymer electrolyte fuel cell includes a stack in which multiple unit cells are stacked, each unit cell including a power generation section having a membrane electrode assembly and a pair of plate-shaped separators sandwiching the power generation section (see, for example, Patent Document 1).

[0003] The separators described in Patent Document 1 have ridges and grooves that extend in parallel and alternately arranged. Between each separator constituting a single cell and the power generation section, a gas flow passage through which the reactant gas flows is formed, partitioned by the ridges and grooves. In this single cell, water generated during power generation in the power generation section flows into the gas flow passage. The water that has flowed into the gas flow passage is swept away by the flow pressure of the reactant gas flowing inside the gas flow passage and is discharged to the outside of the gas flow passage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-47442 A Summary of the Invention [Problem to be solved by the invention]

[0005] Usually, the water flows intermittently inside the gas flow path in the single cell. Therefore, the flow rate and flow speed of the water vary in each part of the gas flow path. This causes the gas flow to become unstable in each part of the gas flow path, such as making it difficult for the gas to flow in some parts of the gas flow path. Therefore, this may cause a partial decrease in the amount of power generation in the single cell, which may cause a decrease in the power generation performance of the fuel cell. [Means for solving the problem]

[0006] Various aspects of the device for solving the above problems will now be described. [Mode 1] A fuel cell separator arranged in a manner to abut against a power generation section of a fuel cell, the separator comprising a plurality of first portions and a plurality of second portions, the first portions having a plurality of first ridges and a plurality of first grooves extending in a first direction, the first ridges and the first grooves being arranged in a manner such that they alternate in a second direction intersecting the first direction, the ends of the first ridges being arranged in a manner such that they abut against the power generation section, the second portions having a plurality of second ridges and a plurality of second grooves extending in the first direction, the second ridges and the second grooves being arranged in a manner such that they alternate in the second direction, a separator for a fuel cell, wherein the first portion and the second portion are integrally formed in a line-up in the first direction such that each of the plurality of first ridges and each of the plurality of second ridges are connected to form a plurality of ridge portions and each of the plurality of first grooves and each of the plurality of second grooves are connected to form a plurality of groove portions, and at a boundary portion between the first portion and the second portion, a position of the first groove and a position of the second groove are shifted from each other in the second direction.

[0007] In the above configuration, adjacent grooves are connected to each other through a gap (hereinafter, a communication passage) between the tip of the second ridge and the power generation section. The communication passage allows the flow of the reaction gas between adjacent grooves. In addition, in the above configuration, the position of the first groove and the position of the second groove are shifted in the second direction at the boundary between the first and second parts of each groove, so that each groove and each ridge is extended in a step-like manner. Therefore, a part of the reaction gas flowing through the groove hits a step in the step-like shape and changes direction, and enters the communication passage. In this way, a flow of the reaction gas flowing through the communication passage is generated. Furthermore, in the above configuration, due to its structure, water generated during power generation in the power generation section appears and spreads on the rear surface of the first ridge, i.e., the inner surface of the communication passage.

[0008] According to the above configuration, water that is generated in the power generation section and appears on the inner surface of the communication passage can be swept away into the groove section (more specifically, into its bottom) by the flow of reactant gas flowing through the communication passage. This allows the water to be quickly moved to a portion away from the power generation section, i.e., a portion where it is unlikely to interfere with power generation by the power generation section. This makes it possible to suppress a partial decrease in the amount of power generated in the power generation section, thereby improving the power generation performance of the fuel cell.

[0009] In addition, the communication passages that connect the adjacent grooves are formed, and a flow of the reactant gas through the communication passages can be generated. Therefore, the reactant gas can be diffused over a wider area than in a fuel cell without a communication passage. This also improves the performance of the fuel cell.

[0010] [Aspect 2] The fuel cell separator according to [Aspect 1], wherein the first portions and the second portions are arranged alternately in the first direction. With the above configuration, the communication passages, which allow the reactant gas to flow between adjacent grooves and allow water generated in the power generation section to move quickly to the bottom of the grooves, can be arranged in a well-balanced manner over the entire surface of the fuel cell separator facing the power generation section, thereby making it possible to effectively prevent a partial decrease in the amount of power generated in the power generation section and to effectively diffuse the reactant gas over a wide area over the entire area between the power generation section of the fuel cell and the fuel cell separator. Effect of the Invention

[0011] The fuel cell separator of the present invention can improve the performance of the fuel cell. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of a fuel cell stack to which a fuel cell separator according to one embodiment is applied; [Diagram 2] FIG. 4 is a perspective view of a model showing the structure of a portion of a first separator on the power generation section side in the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view of the model taken along line 3-3 in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view of the model taken along line 4-4 in FIG. 2. [Diagram 5] 5A to 5C are diagrams illustrating the operation of the fuel cell separator according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, one embodiment of a fuel cell separator will be described. In the drawings, for the convenience of explanation, some components may be shown exaggerated or simplified, and the dimensional ratios of each component may differ from the actual ones.

[0014] 1, a fuel cell separator of this embodiment (hereinafter referred to as separator 20) is used in a polymer electrolyte fuel cell stack 100. Note that separator 20 is a general term for a first separator 30 and a second separator 40, which will be described later.

[0015] The stack 100 has a structure in which a plurality of unit cells 10 are stacked. The unit cell 10 includes a first separator 30 on the cathode side, a second separator 40 on the anode side, and a power generation section 11 sandwiched between the separators 30, 40.

[0016] <Power Generation Division> The power generation section 11 is composed of a membrane electrode assembly 12, and a cathode side gas diffusion layer 13 and an anode side gas diffusion layer 14 which sandwich the membrane electrode assembly 12. The cathode side gas diffusion layer 13 is provided between the membrane electrode assembly 12 and a first separator 30. The anode side gas diffusion layer 14 is provided between the membrane electrode assembly 12 and a second separator 40. Both the cathode side gas diffusion layer 13 and the anode side gas diffusion layer 14 are formed of carbon fiber.

[0017] The membrane electrode assembly 12 includes an electrolyte membrane 15 made of a solid polymer material that has good proton conductivity in a wet state, and a pair of electrode catalyst layers 16 that sandwich the electrolyte membrane 15. Each electrode catalyst layer 16 supports a catalyst such as platinum to promote the electrochemical reaction of the reactant gas in the fuel cell.

[0018] <First separator> The first separator 30 is formed by, for example, press-molding a composite material containing a carbon material such as graphite and a resin material such as polypropylene while heating it. The first separator 30 has a plurality of protrusions 31 and a plurality of grooves 32 extending in a first direction X. The plurality of protrusions 31 extend in parallel at intervals from one another. Each protrusion 31 basically has a cross section (cross section shown in FIG. 1) in a second direction Y perpendicular to the first direction X, which is tapered toward the tip. The tip portion of each protrusion 31 abuts against the cathode-side gas diffusion layer 13. The plurality of grooves 32 extend along the protrusions 31 between two adjacent protrusions 31. Each groove 32 has a passage cross section (cross section shown in FIG. 1) that is tapered toward the bottom. In the single cell 10, a reactant gas flows inside each groove 32 that is groove-shaped. Each of the protrusions 31 and each of the grooves 32 extend in a direction perpendicular to the plane of the paper in FIG.

[0019] <Second separator> The second separator 40 is formed by, for example, press-molding a composite material containing a carbon material such as graphite and a resin material such as polypropylene while heating it. The second separator 40 has a plurality of protrusions 41 and a plurality of grooves 42 extending in the first direction X. The plurality of protrusions 41 extend in parallel at intervals from one another. Each protrusion 41 basically has a cross section in the second direction Y (cross section shown in FIG. 1) that tapers toward the tip. The tip portion of each protrusion 41 abuts against the anode-side gas diffusion layer 14. The plurality of grooves 42 extend along the protrusions 41 between two adjacent protrusions 41. Each groove 42 has a passage cross section (cross section shown in FIG. 1) that tapers toward the bottom. In the single cell 10, the reactant gas flows inside the groove 42 that is in the form of a concave groove. The protrusions 41 and the grooves 42 extend in a direction perpendicular to the plane of the paper in FIG.

[0020] An oxidizing gas flow path through which an oxidizing gas as a reactant gas flows is formed in a portion defined by the grooves 32 of the first separator 30 and the cathode side gas diffusion layer 13. A fuel gas flow path through which a fuel gas as a reactant gas flows is formed in a portion defined by the grooves 42 of the second separator 40 and the anode side gas diffusion layer 14. In this embodiment, the oxidizing gas flowing through the oxidizing gas flow path is air, and the fuel gas flowing through the fuel gas flow path is hydrogen.

[0021] The back surface of the bottom of the groove 32 in the first separator 30 and the back surface of the bottom of the groove 42 in the second separator 40 adjacent to the first separator 30 are joined to each other. In the area partitioned by the back surface of the protrusion 31 in the first separator 30 and the back surface of the protrusion 41 in the second separator 40, a cooling water flow path through which cooling water flows is formed.

[0022] The specific structure of the separator 20 of this embodiment will be described in detail below with reference to FIGS. In this embodiment, the first separator 30 and the second separator 40 have the same structure. Therefore, hereinafter, the specific structure of the first separator 30 will be described, and a description of the specific structure of the second separator 40 will be omitted. In addition, hereinafter, the upstream side in the flow direction of the reaction gas flowing through the groove portion 32 will be simply referred to as the upstream side, and the downstream side in the same flow direction will be simply referred to as the downstream side.

[0023] 2 to 4 show a model having the structure of the portion of first separator 30 on the side of power generation section 11. In reality, grooves that form the cooling water flow paths are formed on the rear surface of protrusion 31 of first separator 30.

[0024] 2, the first separator 30 has a first portion 50 and a second portion 60. The first separator 30 has a structure in which the first portions 50 and the second portions 60 are integrally formed in a manner in which the first portions 50 and the second portions 60 are alternately arranged in the first direction X.

[0025] <Part 1> 2 and 3, the first portion 50 has a plurality of first ridges 51 and a plurality of first grooves 52 extending in a first direction X. The first ridges 51 constitute a part of the ridge portion 31. The cross section of the first ridges 51 in the second direction Y has a mountain shape tapering toward the tip. The first grooves 52 constitute a part of the groove portion 32. The passage cross section of the first grooves 52 has a mountain shape tapering toward the bottom of the first grooves 52.

[0026] In the first portion 50, the first ridges 51 and first grooves 52 are arranged alternately in the second direction Y. The first portion 50 has a band shape of the same width extending in the second direction Y. In this embodiment, the first separator 30 is arranged such that the tip of each first ridge 51 abuts against the power generation section 11 (see FIG. 1).

[0027] <Second part> As shown in Figs. 2 and 4, the second portion 60 has a plurality of second ridges 61 and a plurality of second grooves 62 extending in the first direction X. The second ridges 61 constitute a part of the ridge portion 31. The cross-sectional shape of the second ridges 61 in the second direction Y is such that the side of the mountain shape that abuts against the power generation section 11 (the upper side in Fig. 4) is cut away. The top surface of the second ridges 61 is flat and extends in the first direction X and the second direction Y. In this embodiment, the first separator 30 is disposed such that the top surfaces, which are the tips of the second ridges 61, do not abut against the power generation section 11. The second grooves 62 constitute a part of the groove portion 32. The passage cross-section of the second grooves 62 is in the shape of a mountain tapering toward the bottom of the second grooves 62.

[0028] In the second portion 60, the second protrusions 61 and the second grooves 62 are arranged alternately in the second direction Y. The second portion 60 has a band shape that has the same width and extends in the second direction Y. In this embodiment, the width of the second portion 60 and the width of the first portion 50 are the same.

[0029] As shown in FIGS. 2 to 4, in the first separator 30, the first portion 50 and the second portion 60 are integrally formed in a manner alternately arranged in the first direction X. In the first separator 30, the first ridges 51 and the second ridges 61 are connected to each other to form a plurality of ridge portions 31. More specifically, each ridge portion 31 forms a single ridge in which the first ridges 51 and the second ridges 61 are connected to each other in a manner alternately arranged in the first direction X. In the first separator 30, the first grooves 52 and the second grooves 62 are connected to each other to form a plurality of groove portions 32. More specifically, each groove portion 32 forms a single groove in which the first grooves 52 and the second grooves 62 are connected to each other in a manner alternately arranged in the first direction X.

[0030] In the first separator 30, the positions of the first grooves 52 and the second grooves 62 are shifted from each other in the second direction Y at the boundary between the first portion 50 and the second portion 60. Specifically, the positions of two adjacent first grooves 52 in the first direction X are shifted in the second direction Y by an amount equivalent to approximately "1 / 4" of the interval K between adjacent protrusions 31 in the second direction Y. In addition, the positions of two adjacent second grooves 62 in the first direction X are shifted in the second direction Y by an amount equivalent to approximately "1 / 4" of the interval K. In addition, in the boundary between the first portion 50 located on the upstream side and the second portion 60 located on the downstream side, the positions of the first grooves 52 and the second grooves 62 are shifted in the second direction Y by an amount equivalent to "1 / 5" of the interval K.

[0031] In this embodiment, a portion of the downstream end face of the first ridges 51, a portion of the upstream end face of the first ridges 51, and a portion of the upstream end face of the second ridges 61 are exposed. The exposed portions of these end faces all have a planar shape extending in the second direction Y and the third direction Z. The third direction Z is perpendicular to both the first direction X and the second direction Y.

[0032] <Communication path> Of the ridges 51, 61 constituting the ridge portion 31, the first ridges 51 abut against the power generation section 11, while the second ridges 61 do not abut against the power generation section 11. Therefore, a gap (hereinafter, a communication passage 33) is formed between the power generation section 11 and the tip of the second ridge 61. More specifically, the communication passage 33 is defined by the outer surface of the power generation section 11, the downstream end face of the first ridge 51, the upstream end face of the first ridge 51, and the top face of the second ridge 61. In this embodiment, adjacent grooves 32 in the second direction Y are communicated with each other via the communication passage 33. Therefore, the communication passage 33 allows the flow of reactant gas between adjacent grooves 32.

[0033] <effect> The function of the separator 20 of this embodiment will be described below. 1, in the unit cell 10 of this embodiment, water W (not shown) is generated during power generation in the power generation section 11. This water W accumulates inside the cathode side gas diffusion layer 13. A part of the generated water W passes through the cathode side gas diffusion layer 13 and seeps out onto the surface of the cathode side gas diffusion layer 13. This water W is then swept downstream by the flow of the reactant gas in the groove portion 32.

[0034] In this embodiment, adjacent grooves 32 are communicated with each other via communication passages 33. Through these communication passages 33, reaction gas is permitted to flow between adjacent grooves 32. In this embodiment, as shown in Figs. 2 to 4, the position of the first groove 52 and the position of the second groove 62 are shifted in the second direction Y at the boundary between the first portion 50 and the second portion 60 in each groove 32. As a result, each groove 32 and each protrusion 31 is extended in a stepped manner. Therefore, a part of the reactant gas flowing in the groove 32 in the first direction X hits a step portion in the stepped manner and changes direction, thereby entering the communication passage 33. In this manner, in this embodiment, a flow of the reactant gas flowing in the communication passage 33 is generated.

[0035] As shown in FIG. 5, in the separator 20 of this embodiment, due to its structure, water W generated during power generation in the power generation section 11 appears and spreads on the downstream end face of the first protrusion 51, i.e., on the inner surface of the communication passage 33. According to this embodiment, a flow of reactant gas (indicated by an outlined arrow in the figure) flows in the second direction Y in the communication passage 33. Therefore, the water W generated in the power generation section 11 (see FIG. 1) and appears on the inner surface of the communication passage 33 can be swept away into the groove portion 32 (more specifically, its bottom) by the flow of reactant gas flowing through the communication passage 33. Therefore, the water W can be quickly moved to a portion away from the power generation section 11, i.e., a portion that is unlikely to interfere with power generation by the power generation section 11. This can suppress a partial decrease in the amount of power generation in the power generation section 11, thereby improving the power generation performance of the fuel cell.

[0036] Moreover, the communication passages 33 are formed to connect the adjacent grooves 32, and a flow of the reactant gas is generated through the communication passages 33. Therefore, the reactant gas can be diffused over a wider area than in a fuel cell that does not have the communication passages 33. This also improves the performance of the fuel cell.

[0037] <Effects> According to this embodiment, the following effects can be obtained. (1) It is possible to improve the power generation performance of the fuel cell by suppressing a partial decrease in the amount of power generated in the power generation section 11. Moreover, it is possible to diffuse the reactant gas over a wider range than in a fuel cell that does not have the communication passages 33. This also improves the performance of the fuel cell.

[0038] (2) The first portions 50 and the second portions 60 are arranged in an alternating manner in the first direction X. Therefore, the communication passages 33, which are portions for circulating the reaction gas between adjacent grooves 32 and for quickly moving water W generated in the power generation section 11 to the bottom of the grooves 32, can be arranged in a well-balanced manner over the entire surface of the separator 20 facing the power generation section 11. This makes it possible to suitably prevent a partial decrease in the amount of power generated in the power generation section 11 and to suitably diffuse the reaction gas over a wide area over the entire area between the power generation section 11 and the separator 20.

[0039] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0040] The amount of deviation in the second direction Y between the positions of the first grooves 52 and the second grooves 62 at the boundary between the first portion 50 and the second portion 60 can be changed arbitrarily. For example, the amount of deviation can be set to a value equivalent to "1 / 4" of the interval K between the adjacent protrusions 31 in the second direction Y, or to a value equivalent to "1 / 6" of the interval K. In addition, the amount of deviation in the second direction Y between two first grooves 52 adjacent to each other in the first direction X and the amount of deviation in the second direction Y between two second grooves 62 adjacent to each other in the first direction X can be changed arbitrarily. For example, the amount of deviation can be set to a value equivalent to "1 / 3" of the interval K, or to a value equivalent to "1 / 5" of the interval K.

[0041] The top surface of the second ridges 61 may be formed into a shape other than a flat shape. For example, the top surface of the second ridges 61 may be formed into a curved surface shape that is convex in the protruding direction. The downstream end face of the first ridges 51 and the upstream end face of the first ridges 51 may be formed into a shape other than a flat shape. For example, the downstream end face of the first ridges 51 may be formed into a curved surface shape that is convex toward the downstream side, or the upstream end face of the first ridges 51 may be formed into a curved surface shape that is convex toward the upstream side.

[0042] The longitudinal directions of the band-shaped first portion 50 and second portion 60 are not limited to being set in the second direction Y perpendicular to the first direction X, but may be set in a fourth direction obliquely intersecting the first direction X.

[0043] The relationship between the width of the first portion 50 and the width of the second portion 60 can be changed arbitrarily in addition to making these widths the same. Here, when the width of the first portion 50 (i.e., the length of the first ridges 51) is made larger relative to the width of the second portion 60, the contact area between the separator 20 (more specifically, the first ridges 51) and the power generation section 11 increases, thereby increasing the strength required to support the separator 20. On the other hand, when the width of the second portion 60 (i.e., the length of the second ridges 61) is made larger relative to the width of the first portion 50, the contact area between the separator 20 and the power generation section 11 decreases, thereby decreasing the strength required to support the separator 20, but increasing the amount of reactant gas supplied to the power generation section 11.

[0044] In short, the relationship between the width of the first portion 50 and the width of the second portion 60 should be determined in a manner that provides sufficient strength for supporting the separator 20 and ensures a sufficient supply of reactive gas to the power generation section 11.

[0045] The order of arrangement of the first portion 50 and the second portion 60 in the first direction X is not limited to the order in which the first portion 50 and the second portion 60 are alternately arranged, and can be changed as desired. For example, the separator 20 may be structured such that the first portion 50, the first portion 50, and the second portion 60 are integrally arranged in the first direction X in this order. Alternatively, the separator 20 may be structured such that the first portion 50, the second portion 60, and the second portion 60 are integrally arranged in the first direction X in this order.

[0046] The configuration in which the first portion 50 and the second portion 60 are integrally formed in a state aligned in the first direction X is not limited to being applied to both the first separator 30 and the second separator 40, but may be applied to only one of the first separator 30 and the second separator 40.

[0047] The configuration having the first portion 50 and the second portion 60 does not necessarily have to be provided on both the first separator 30 and the second separator 40, but may be provided on only one of the first separator 30 and the second separator 40.

[0048] The first separator 30 and the second separator 40 may be made of a metal material such as stainless steel. [Explanation of symbols]

[0049] 100…Stack 10...Single cell 11…Power generation section 12...Membrane electrode assembly 13...Cathode side gas diffusion layer 14...Anode side gas diffusion layer 15...Electrolyte membrane 16...electrode catalyst layer 20…Separator 30…First separator 31...Protrusion part 32…Groove 33…Communication path 40…Second separator 41...Protrusion part 42…Groove 50…Part 1 51…First protrusion 52…1st groove 60…Second part 61...Second ridge 62…Second groove

Claims

1. A separator for a fuel cell that is provided in contact with a power generation section of the fuel cell, A plurality of first portions and a plurality of second portions; the first portion has a plurality of first protrusions and a plurality of first grooves extending in a first direction, the first protrusions and the first grooves being arranged alternately in a second direction intersecting the first direction, and protrusions of the first protrusions are arranged in a manner such that protrusions contact the power generation unit, the second portion has a plurality of second ridges and a plurality of second grooves extending in the first direction, the second ridges and the second grooves being arranged alternately in the second direction, and tips of the second ridges are arranged so as not to come into contact with the power generation unit, the first portion and the second portion are integrally formed in a state of being aligned in the first direction such that each of the plurality of first ridges and each of the plurality of second ridges are connected to form a plurality of ridge portions, and each of the plurality of first grooves and each of the plurality of second grooves are connected to form a plurality of groove portions, A fuel cell separator, wherein at a boundary portion between the first portion and the second portion, a position of the first groove and a position of the second groove are shifted from each other in the second direction.

2. The first and second portions are arranged in an alternating manner in the first direction. The fuel cell separator according to claim 1 .

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