Separator for a fuel cell and elementary cell of a fuel cell

Abstract

Separator for a fuel cell, with: a separation plate (100) provided with a coupling projection (110) projecting at one edge thereof; and a porous body (200) provided with a coupling hole (210) into which the coupling projection (110) is firmly inserted, so that the porous body (200) is coupled to a plane of the separation plate (100), wherein the porous body (200) defines a path in which reactive gases flow, characterized in that: the coupling projections (110) are formed such that a diameter of one end thereof is larger than the length of the minor axis of the corresponding coupling hole (210).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a separator for a fuel cell and a unit cell of a fuel cell. BACKGROUND

[0002] A fuel cell is a type of generator that electrochemically converts the chemical energy of a fuel into electrical energy in a stack. Fuel cells can be used not only to provide motive power for industries, homes, and vehicles, but also to power manually operated electronic devices such as mobile devices. Recently, the application of fuel cells has gradually expanded, as they are recognized as a clean, highly efficient energy source.

[0003] Fig. 1 is an exploded view showing a conventional fuel cell stack.

[0004] As in Fig. 1, the conventional fuel cell stack includes a membrane electrode assembly (MEA) 4 having two electrolyte membranes and electrodes disposed on both surfaces thereof, a pair of gas diffusion layers (GDL) 6 attached to the electrodes of the membrane electrode assembly and which help diffuse reactant gases, a separator 8 in close contact with each gas diffusion layer to supply the reactant gases, and a gasket 8a which prevents the leakage of the reactant gases.

[0005] The separator 8, on the other hand, prevents hydrogen and oxygen, which are reaction gases, from mixing with each other and is electrically connected to the membrane electrode assembly 4 to support it, and therefore serves to maintain the shape of the fuel cell stack.

[0006] Therefore, the separator 8 should have a delicate structure to prevent the reaction gases from mixing with each other, and should have high strength and high conductivity to serve as a conductor and support member. Separator 8 made of a metallic material is mainly used.

[0007] Since a voltage generated by a unit cell 2 including the membrane electrode assembly 4, the gas diffusion layer 6, the gasket 8a, and the separator 8 is low, a plurality of unit cells are stacked and used depending on a required voltage.

[0008] However, in the case of stacking many unit cells 2 as such, the separator 8 maintains a uniform surface pressure, which therefore leads to local deformation or does not maintain the seal.

[0009] Further, spot welding or laser welding is used to fix the plurality of stacked separators 8. However, the corrosion resistance of a welded part is low, so the welded part may be corroded, and the welded part has lower strength than a peripheral part, so cracks or the like may be generated.

[0010] In particular, when the thickness of the separator is 0.1 mm or less, deformation may be generated by pressure during welding, and stackability deteriorates.

[0011] In order to improve the stackability of the conventional separator 8, a technology has been developed in which uneven parts for fitting are formed on both sides of the separator 8 to improve the stackability. However, the above-mentioned method is problematic because it is necessary to secure a height sufficient for the uneven part to form a shape for fitting, and the separator 8 with 0.1 mm or less may be deformed, or cracks may occur during a pressing operation for fitting the uneven part.

[0012] DE 699 05 177 T2 discloses a multi-cell assembly formed by alternately stacking two types of pre-assembled elements: a subassembly for holding a bipolar electrode and a subassembly for holding a membrane. The alternating stack of elements is stacked over a lower end element, and the stack is completed by placing an upper end electrode element over the last membrane-holding element.Each bipolar plate electrode support member and each ion exchange membrane separator support member includes a substantially similar rectangular frame piece made of an electrically non-conductive and chemically resistant material, typically molded plastics material, having grooves on its upper (assembly) surface for receiving O-rings - ring-like sealing means with an inner flange portion (19) recessed from a first planar surface and an electrically non-conductive support mating flange (4, 15), and with through-holes and recesses at coordinated locations arranged along two opposite sides of the rectangle and a frame which, upon completion of assembly, forms channels for the separate circulation of the negative electrolyte and the positive electrolyte through all the negative electrolyte flow chambers and all the positive electrolyte flow chambers in cascade, respectively.The bipolar reactor has no inlet and outlet manifolds for the two electrolytes; the electrolytes flow through the respective flow chambers in a zigzag path, essentially in a hydraulic series or cascade mode. Preferably, two orders of parallel flow channels are defined in felt electrodes. Each order defines a comb-shaped flow distribution channel system whose parallel fingers are interleaved with the finger channels of the other order. SUMMARY

[0013] The present disclosure relates to a separator for a fuel cell and a unit cell of a fuel cell. Embodiments relate to a separator for a fuel cell and a unit cell of a fuel cell that facilitate assembly of the separator for the fuel cell with a porous body using a coupling protrusion, and in which a coupling protrusion and a coupling recess are formed, respectively, on adjacent separators, thus improving stacking capability of unit cells of a fuel cell.

[0014] Embodiments of the present invention have been provided in consideration of the above-mentioned problems encountered in the related art. For example, embodiments of the present invention provide a separator for a fuel cell and a unit cell of a fuel cell that facilitates coupling of a separator to a porous body, thus shortening assembly time and preventing a reduction in corrosion resistance from occurring.

[0015] Other embodiments of the present invention provide a separator for a fuel cell and a unit cell of a fuel cell that reduce a thickness of the separator, which accordingly reduces both the volume and the weight of the fuel cell.

[0016] Further embodiments provide a separator for a fuel cell and a unit cell of a fuel cell, which are suitable for improving stackability of the adjacent unit cells of the fuel cell.

[0017] The different embodiments can be used in combination with each other.

[0018] A separator according to the invention is defined by claim 1. The porous body defines a path or route in which reaction gases or reactive gases flow.

[0019] Subclaims relate to preferred embodiments. The separation plate and the porous body may have at least one pair of coupling projections and coupling holes on both sides of edges thereof, each facing each other.

[0020] Each of the coupling holes may be formed in a shape of a slot and may have a width such that a length of a shorter axis of the coupling hole corresponds to a diameter of the corresponding coupling projection.

[0021] The coupling holes, which are arranged opposite to each other, can be designed such that the major axes thereof are perpendicular to each other.

[0022] The coupling protrusion may be inserted into the coupling hole to be movable in a direction of the major axis of the coupling hole, thus absorbing deformation due to springback when the separation plate is coupled to the porous body, and thus ensuring flatness accordingly.

[0023] The separation plate may further comprise a seal fixed to the plane thereof, wherein the fixing projection is formed on or at the seal.

[0024] A unit cell for a fuel cell according to the invention is defined by patent claim 9. A fuel cell according to the invention is defined by patent claim 12. The fastening projection and the fastening recess allow adjacent unit cells of the fuel cell to be easily coupled to one another.

[0025] Subclaims relate to preferred embodiments. The fastening projection may include a plurality of fastening projections, and the fastening recess may include a plurality of fastening recesses, and each of the fastening recesses may be formed in a slot shape to allow the fastening projection to be movable while being disposed in the fastening recess.

[0026] The fastening recesses, which are arranged opposite to each other, can be shaped so that their main axes are perpendicular to each other.

[0027] The fastening projection may be formed such that a diameter thereof increases toward an end thereof, and the fastening recess may be formed such that a width thereof gradually increases in a direction in which the fastening projection is inserted to correspond to a portion of the fastening projection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other objects, features and other advantages of the present invention will become more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is an exploded view of a conventional fuel cell stack; Fig. Fig. 2 is a view showing a separator according to an embodiment of the present invention; Fig. 3 is a view showing the coupling of a coupling protrusion to a coupling hole according to an embodiment of the present invention; Fig. 4 is a view showing a separator according to another embodiment of the present invention; Fig. 5 is a view showing a unit cell of a fuel cell according to an embodiment of the present invention; FIG: 6 is a view showing a mounting recess according to an embodiment of the present invention; and Fig. 7 is a view showing the coupling of a fastening projection to a fastening recess according to an embodiment of the present invention. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0029] Hereinafter, reference will be made in detail to various embodiments of the present invention, examples of which are shown in the accompanying drawings and described below. While the invention will be described in connection with exemplary embodiments, it is to be understood that the present description is not intended to limit the invention to the exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may fall within the spirit and scope of the present invention as defined by the accompanying claims.

[0030] Fig. Fig. 2 is a view showing a separator according to an embodiment of the present invention, and Fig. 3 is a view showing the coupling of a coupling protrusion to a coupling hole according to an embodiment of the present invention.

[0031] As in Fig. 2 and Fig. 3, a separator 10 for a fuel cell according to an embodiment of the present invention includes a separation plate 100 having coupling projections 110 at one edge thereof, and a porous body 200 having coupling holes 210 into which the coupling projections 110 are firmly inserted and coupled to a plane of the separation plate 100.

[0032] The separation plate 100 is formed from a metallic material in the shape of a flat plate. The porous body 200 is formed from a conductive material with a microporous structure, such as a metal foam, carbon foam, or wire mesh, and is coupled to the plane of the separation plate, thus defining a path through which reactive gases flow.

[0033] The porous body 200 according to the embodiment of the present invention can be manufactured by forming a porous structure such as microholes and a channel on a metallic thin plate using a pressing method, thereby forming a three-dimensional microporous structure.

[0034] The porous body 200 manufactured in this way is integrally secured to the plane of the separation plate 100 via the coupling protrusions 110 and the coupling holes 210 and compresses a gas diffusion layer (GDL) 6 uniformly to disperse surface pressure, thus minimizing electrical resistance and maximizing the performance of the fuel cell.

[0035] Further, when the separator is fixed using a conventional welding method, it is possible to prevent the corrosion resistance of a welded part from being reduced, to prevent the airtightness from being reduced due to microcracks of the welded part, and to eliminate the need to replace and manage the welded part at certain time intervals, thus realizing a reduction in management costs and minimizing the deformation of the separator 10.

[0036] In particular, even if the thickness of the separation plate 100 is made 0.1 mm or smaller, a separate welding process for fixing the porous body 200 is not required, thus minimizing a reduction in stackability due to damage such as deformation.

[0037] Preferably, the separation plate 100 and the porous body 200 according to the embodiment of the present invention are characterized in that at least a pair of coupling protrusions 110 and coupling holes 210 are positioned to face each other. This is because when the separation plate 100 and the porous body 200 are coupled to each other via a single coupling protrusion 110 and coupling hole 210, unwanted rotation may occur around a coupling portion. Therefore, it is preferable to form at least a pair of coupling portions so as to fix a coupled position.

[0038] The coupling hole 210 according to the embodiment of the present invention is formed to have a slot shape extending in one direction. Preferably, the coupling hole 210 is shaped such that the length of a minor axis B thereof corresponds to a diameter of the coupling protrusion 210.

[0039] In the case of fixing both ends using spot welding or the like when the separation plate 100 is coupled to the porous body 200, the separation plate 100 and the porous body 200 having relatively large widths may conventionally be separated from each other at a central portion due to a difference in width between the separation plate 100 and the porous body 200 when the separation plate 100 is coupled to the porous body 200.

[0040] Such a separation phenomenon makes it difficult to ensure the flatness of the separation plate 100 and the porous body 200, thus leading to a reduction in performance and durability due to non-uniformity of surface pressure, thus making it difficult to assemble the fuel cell stack, thus leading to a reduction in performance.

[0041] Here, the coupling hole 210 of the porous body 200 according to the embodiment of the present invention is formed in the shape of a slit, and the coupling protrusion 110 is inserted into the coupling hole 210. In this state, the coupling protrusion is movable along the length of a major axis A in the direction of the major axis A of the coupling hole 210. Such a structure can absorb deformation due to springback when the separation plate 100 is coupled to the porous body 200, thus preventing the occurrence of the separation phenomenon and ensuring the flatness of the separation plate 100 and the porous body 200. Accordingly, it is possible to improve the assemblability and performance of the fuel cell stack.

[0042] Preferably, the coupling holes 210 are arranged at both ends of the porous body 200 to be opposite to each other and are formed so that their main axes A are perpendicular to each other. This is because the porous body 200 and the separation plate 100 each have the shape of a rectangular flat plate and should not be deformed in perpendicular directions, that is, in both the width direction and the length direction.

[0043] Preferably, the coupling protrusion 110 according to the embodiment of the present invention is shaped such that a diameter C of a protruding end thereof is larger than the length of the minor axis B of the coupling hole 210. The reason for this is that it is possible to prevent the coupling protrusion 110 inserted into the coupling hole 210 from being removed from the coupling hole 210.

[0044] Fig. 4 is a view showing a separator according to another embodiment of the present invention.

[0045] As in Fig. 4, the separator 10 according to another embodiment of the present invention further includes a gasket 120 attached to an edge of a plane thereof. Here, the coupling protrusion 110 extends in the direction 120 and then protrudes upward. Therefore, the coupling protrusion 110 formed on the gasket 120 attached to the planar separation plate 100 is firmly inserted into the coupling hole 210 of the porous body 200, so that the separation plate 100 can be integrally coupled to the porous body 200.

[0046] Fig. 5 is a view showing a unit cell of a fuel cell according to an embodiment of the present invention, Fig. 6 is a view showing a fastening groove according to an embodiment of the present invention, and Fig. 7 is a view showing the coupling of a fastening projection with a fastening groove according to an embodiment of the present invention.

[0047] As in Fig. As shown in Figures 5 to 7, according to one embodiment of the present invention, a plurality of unit cells 1 are stacked to form a fuel cell. The unit cell includes a membrane electrode assembly (MEA) 4, a pair of gas diffusion layers (GDL) 6, and a pair of separators 10 attached to both sides of the membrane electrode assembly 4.

[0048] In order to improve the stackability of adjacent separators 10, similar to the above-described coupling structure of the separation plate 100 with the porous body 200, a fixing projection 11 protrudes on one separator 10 formed of the pair of separators 10, while a fixing groove 12 is formed in the remaining separator 10 to allow the fixing projection 11 to be firmly inserted therein.

[0049] Such a structure can improve the stackability of adjacent separators 10, which therefore makes it easier to assemble the fuel cell stack and therefore shortens a manufacturing time and improves productivity, and which can also minimize the deformation of the unit cell 1 of the fuel cell, which therefore increases the performance and maintenance life of the fuel cell.

[0050] Similar to the coupling protrusion 110 and the coupling hole 210, a plurality of fastening protrusions 11 and fastening recesses 12 are provided according to an embodiment of the present invention. Each fastening groove 12 is formed in the shape of a slot, thus allowing the fastening protrusion 11 inserted into the fastening groove 12 to be movable within a certain range.

[0051] Furthermore, the fastening grooves 12 arranged opposite to each other are shaped such that their main axes are perpendicular to each other, which therefore prevents the unit cell 1 of the fuel cell from being deformed and thereby improves the stackability of the unit cells 1 of the fuel cell.

[0052] Preferably, the fastening protrusion 11 according to the embodiment of the present invention may be shaped so that its diameter increases toward one end in a protruding direction thereof. Further, the fastening groove 12 may be formed to have a shape corresponding to a portion of the fastening protrusion 11 and its width gradually increasing in a direction in which the fastening protrusion 11 is inserted.

[0053] Therefore, such a structure prevents the fixing protrusion 11 from being removed from the fixing groove 12 when adjacent unit cells 1 of the fuel cell are coupled to each other, thus improving stackability and a coupling force between the unit cells 1 of the fuel cell.

[0054] The present invention simplifies the alignment of a porous body with a separator when assembling unit cells of a fuel cell, thus improving assemblability, and can eliminate the need to perform a separate welding process for the purpose of fastening, thus preventing a reduction in corrosion resistance and shortening an assembly time, thus leading to an increase in productivity.

[0055] Furthermore, even if the thickness of the separator is reduced, it is possible to minimize deformation and damage in the process of assembling the unit cells of the fuel cell, and it is possible to reduce the volume and weight of the fuel cell, which therefore improves the performance of a vehicle.

Claims

[1] Separator for a fuel cell, comprising: a separation plate (100) provided with a coupling projection (110) projecting at one edge thereof; and a porous body (200) provided with a coupling hole (210) into which the coupling projection (110) is firmly inserted, so that the porous body (200) is coupled to a plane of the separation plate (100), wherein the porous body (200) defines a path in which reactive gases flow, characterized by , that: the coupling projections (110) are formed such that a diameter of one end thereof is larger than the length of the minor axis of the corresponding coupling hole (210). [2] The separator according to claim 1, wherein the separation plate (100) has a first coupling portion protruding at a first edge and a second coupling projection protruding at a second edge; wherein the porous body (200) has a first coupling hole adjacent to a first edge and a second coupling hole adjacent to a second edge; and wherein the first coupling projection faces the first coupling hole and the second coupling projection faces the second coupling hole. [3] The separator according to claim 2, wherein each of the coupling holes (210) is formed in a shape of a slit and has a width such that a length of a minor axis of the coupling hole (210) corresponds to a diameter of the corresponding coupling projection (110). [4] A separator according to claim 2 or 3, wherein the first edge is opposite to the second edge. [5] Separator according to claim 3 or 4, wherein a main axis of the first coupling hole (210) is perpendicular to a main axis of the second coupling hole (210). [6] The separator according to claim 1, wherein the coupling projection (110) is inserted into the coupling hole (210) to be movable in a direction of a main axis of the coupling hole (210). [7] A separator according to any one of the preceding claims, wherein the separator (10) is adapted to absorb deformation due to springback when the separation plate (100) is coupled to the porous body (200), thus ensuring flatness. [8] A separator according to any preceding claim, wherein the separation plate further comprises a gasket (120) fixed to the plane thereof, the fixing projection (11) being formed on the gasket (120). [9] Unit cell for a fuel cell formed by stacking a plurality of unit cells (1), the unit cell (1) comprising: first and second separators (10) arranged on opposite sides of the unit cell (1); wherein a fastening projection (11) is provided on the first separator (10) and a fastening recess (12) is formed in the second separator (10) to allow the fastening projection (11) to be firmly inserted into the fastening recess (12); wherein the unit cell (1) is suitable for being stacked with other unit cells (1) to form a fuel cell; and wherein the fastening projection (11) and the fastening recess (12) are suitable for being coupled to portions of adjacent unit cells (1), characterized by , that: a diameter of the fastening recess (12) increases toward an end of the fastening recess (12), and a width of the fastening recess (12) in a direction in which the fastening projection (11) is inserted gradually increases to correspond to a portion of the fastening projection (11). [10] The unit cell according to claim 9, wherein the fixing projection (11) is one of a plurality of fixing projections and the fixing recess (12) is one of a plurality of fixing recesses, and wherein each of the fixing recesses is formed in a shape of a slit to allow the fixing projection to be movable while being arranged in the fixing recess. [11] Unit cell according to claim 9 or 10, wherein the fastening recesses (12) arranged opposite one another are shaped such that the main axes thereof are perpendicular to one another. [12] Fuel cell, with: a stack of unit cells (1); where each unit cell (1) has: a membrane electrode assembly (4); a first gas diffusion layer (6) adjacent to a first major surface of the membrane electrode assembly (4); a second gas diffusion layer (6) adjacent to a second major surface of the membrane electrode assembly (4), the second major surface being opposite to the first major surface; a first separator (10) having a first surface adjacent to the first gas diffusion layer (6), the first surface of the first separator (10) facing the membrane electrode assembly (4) and being separated therefrom by the first gas diffusion layer (6); and a second separator (10) having a first surface adjacent to the second gas diffusion layer (6), the first surface of the second separator (10) facing the membrane electrode assembly (4) and being separated therefrom by the second gas diffusion layer (6); wherein a fixing projection (11) is provided on a second surface of the first separator (10) of each unit cell (1), the second surface of the first separator (10) being opposite to the first surface of the first separator (10); wherein a fixing recess (12) is formed in a second surface of the second separator (10) of each unit cell (1), the second surface of the second separator (10) being opposite to the first surface of the second separator (10); and wherein the unit cells (1) are stacked together, wherein the fastening projection (11) of each unit cell (1) is firmly inserted into the fastening recess (12) of an adjacent unit cell (1), wherein a diameter of the fastening recess (12) increases toward an end of the fastening recess (12), and a width of the fastening recess (12) gradually increases in a direction in which the fastening projection (11) is inserted to correspond to a portion of the fastening projection (11). [13] A fuel cell according to claim 12, wherein each first separator (10) has a plurality of fixing projections (11) and each second separator (10) has a plurality of fixing recesses (12). [14] A fuel cell according to claim 12 or 13, wherein each fixing recess (12) is formed in a shape of a slit. [15] A fuel cell according to any one of claims 12 to 14, wherein each fixing recess (12) is formed in a shape of a slit to allow the fixing projection (11) to be movable while being disposed in the fixing recess (12). [16] A fuel cell according to any one of claims 12 to 15, wherein each second separator (10) has a first fixing recess (12) and a second fixing recess (12), wherein a main axis of the first fixing recess (12) is perpendicular to a main axis of the second fixing recess (12).

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