Fuel cell stack

Abstract

A fuel cell stack formed by stacking elementary fuel cells each having a membrane electrode assembly (MEA) and a pair of separators arranged on opposite sides of the MEA, comprising: a first separator (200) and a second separator (300) held opposite each other between adjacent MEAs and each having a plurality of manifolds, a reaction region, and a guide region arranged between the plurality of manifolds and the reaction region; a first cooling medium guide channel (230) which guides a flow of a cooling medium between the plurality of distributors and the reaction region formed in the guide region of the first separator (200); a second cooling medium guide channel (330) which guides a flow of a cooling medium between the plurality of distributors and the reaction region formed in the guide region of the second separator (300); and wherein at least portions of the first cooling medium guide channel (230) and the second cooling medium guide channel (330) are overlapped to communicate with each other, wherein the first cooling medium guide channel (230) comprises a first edge-side guide channel (245) extending along the edge of the guide region, a plurality of first continuous channels (241) continued from the first edge-side guide channel (245), and a plurality of first discontinuous channels (242) discontinuous from the first edge-side guide channel (245).

Description

BACKGROUND(a) Technical field

[0001] The present invention relates to a fuel cell stack, and more particularly to a fuel cell stack in which a machining accuracy of a cooling medium guide channel in a guide portion of each separator is improved and a cooling medium is effectively distributed to significantly improve heat transfer efficiency. (b) Description of the prior art

[0002] A fuel cell includes a fuel cell stack that generates electrical energy, a fuel supply system that supplies a fuel (hydrogen) to the fuel cell stack, an air supply system including an air blower and a humidifier to supply oxygen in the air, an oxidizer required for an electrochemical reaction, to the fuel cell stack, and a heat and water management system that controls an operating temperature of the fuel cell stack.

[0003] As in Fig. 1 (PRIOR ART), the fuel cell stack is formed by stacking a plurality of unit fuel cells 40, and the unit fuel cells 40 each include a membrane electrode assembly (MEA) 10 and a pair of separators 20 and 30 tightly / fixedly attached to opposite surfaces of the MEA 10.

[0004] The MEA 10 comprises a solid polymer electrolyte membrane that allows a hydrogen proton to move, and catalyst layers, i.e., a cathode and an anode, that are applied to opposite surfaces of the electrolyte membrane so that hydrogen and oxygen can react with each other.

[0005] A gas diffusion layer (GDL) is arranged on outer surfaces of the MEA 10, that is, at portions where the cathode and the anode are arranged, and the pair of separators 20 and 30 are arranged on outer sides of the GDL.

[0006] The pair of separators 20 and 30 has reaction gas channels 23 which supply a reaction gas (fuel or air) or discharge water produced after a reaction.

[0007] The pair of separators 20 and 30 includes a cathode separator tightly / fixedly attached to the cathode of the MEA 10 and an anode separator tightly / fixedly attached to the anode of the MEA 10.

[0008] A cathode reaction surface is formed on one surface of the cathode separator 20, and a plurality of air channels 23 that supply air as an oxidant to the cathode of the MEA 10 are formed on the cathode reaction surface. A cathode cooling surface is formed on the other surface of the cathode separator 20, and a plurality of cooling channels 24 that distribute a cooling medium are formed on the cathode cooling surface.

[0009] An anode reaction surface is formed on one surface of the anode separator 30, and a plurality of fuel channels 33 that supply fuel to the anode of the MEA 10 are formed on the anode reaction surface. An anode cooling surface is formed on the other surface of the anode separator, and a plurality of cooling channels 34 that distribute a cooling medium are formed on the anode cooling surface.

[0010] In the fuel cell stack, since the majority of the unit fuel cells 40 are stacked in a vertical direction, the cathode separator 20 of one unit fuel cell 40 and the anode separator 30 of the other unit fuel cell 40 are bonded / held oppositely between adjacent MEAs 10, and in particular, the cooling channels 24 of the cathode separator 20 and the cooling channels 34 of the anode separator 30 are connected to form cooling channels / passages 24 and 34 for distributing a cooling medium, and accordingly, a pair of cooling channels 24 and 34 are symmetrically arranged on opposite sides of each of the MEAs 10.

[0011] Fig. 2 (PRIOR ART) shows a plan view illustrating a portion of a cooling surface of a conventional cathode separator.

[0012] As in Fig. 2, a plurality of manifolds / collecting lines 7, 8 and 9 are provided in at least one end of each separator 20 and 30, and the plurality of manifolds 7, 8 and 9 may be an air manifold 7, a cooling medium manifold 8 and a fuel manifold 9.

[0013] A cooling surface (or reaction surface) of each of the separators 20 and 30 includes a guide region 4 adjacent to the plurality of manifolds 7, 8, and 9, and a reaction region 2 in which an electrochemical reaction takes place. The reaction region 2 may need to ensure a predetermined contact pressure to move the electric current generated according to the electrochemical reaction, and the guide region 4, in which no electrochemical reaction takes place, is configured to simply guide a flow of a fluid (air, fuel, or cooling medium) between the manifolds and the reaction region 2.

[0014] In order to distribute a reaction gas uniformly, the plurality of reaction gas channels 23 and 33 are formed to extend from the guide region 4 to the reaction region 2 on the reaction surfaces of the separators 20 and 30, whereby the reaction gas channels in the guide region 4 and the reaction gas channels in the reaction region 2 are matched respectively (ie, one to one).

[0015] Since the plurality of distributors 7, 8, and 9 are formed in the ends of the separators 20 and 30, the guide region 4 has an area 4 that is narrower than that of the reaction region 2. Thus, since the plurality of reaction gas channels are provided to be continuously formed from the guide region 4 to the reaction region 2 at / on the reaction surfaces of the separators 20 and 30, the plurality of cooling channels 24 and 34 are necessarily formed to extend from the guide region 4 to the reaction region 2 at / on the cooling surfaces opposite the reaction surfaces. However, as shown in Fig. 2, the distances between the cooling channels 24 and 34 are so narrow that the cooling channels 24 and 34 are difficult to form.

[0016] Particularly, in a case where the cooling channels 24 and 34 of the separators 20 and 30 are formed by punching using a thin plate material with low elongation, if the distances between the cooling channels are 1.5 or less, it is very difficult to process the cooling channels, and cracks are likely to occur in the cooling channels.

[0017] Thus, in the prior art separators 20 and 30, the formability of the cooling channels 24 and 34 in the narrow guide region 4 is reduced, resulting in a reduction in the number of cooling channels 24 and 34. However, this can impair the effective distribution of a cooling medium or the heat transfer performance, resulting in a deterioration of the overall efficiency of a fuel cell. For further prior art, reference is made to US 2015 / 0 380 745 A1 and JP 2007-226 991 A. SUMMARY

[0018] The invention is defined by independent claim 1. Advantageous embodiments are subject to the dependent claims. One embodiment of the present invention provides a fuel cell stack in which the machining accuracy of a cooling medium guide channel in a guide region of each separator is significantly improved and a cooling medium is effectively distributed to significantly improve heat transfer efficiency.

[0019] According to one embodiment of the present invention, a fuel cell stack is provided formed by stacking elementary fuel cells, each having a membrane electrode assembly (MEA) and a pair of separators disposed on opposite sides of the MEA, comprising: a first separator and a second separator, which are held opposite each other between adjacent MEAs and each have a plurality of manifolds, a reaction region, and a guide region disposed between the plurality of manifolds and the reaction region; a first cooling medium guide channel that guides a flow of a cooling medium between the plurality of manifolds and the reaction region formed in the guide region of the first separator;a second cooling medium guide channel that guides a flow of a cooling medium between the plurality of manifolds and the reaction region formed in the guide region of the second separator; and wherein at least portions of the first cooling medium guide channel and the second cooling medium guide channel overlap to communicate with each other, the first cooling medium guide channel including a first peripheral guide channel extending along the edge of the guide region, a plurality of first continuous channels continued from the first peripheral guide channel, and a plurality of first discontinuous channels discontinued from the first peripheral guide channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, features and advantages of the present invention will become more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings. Fig. 1 (PRIOR ART) shows a sectional view illustrating part of reaction surfaces of a conventional fuel cell stack. Fig. 2 (PRIOR ART) is a view showing a guide portion of a cooling surface of a separator of a conventional fuel cell stack. Fig. 3 is a view illustrating a reaction surface of a first separator of a fuel cell stack according to an embodiment of the present invention. Fig. 4 is a view illustrating a cooling surface of the first separator of a fuel cell stack according to an embodiment of the present invention. Fig. 5 is a view illustrating a reaction surface of a second separator of a fuel cell stack according to an embodiment of the present invention. Fig. 6 is a view illustrating a cooling surface of the second separator of a fuel cell stack according to an embodiment of the present invention. Fig. 7 is a view showing a state in which the first separator and the second separator of the fuel cell stack according to an embodiment of the present invention are held opposite to each other. Fig. 8 shows an enlarged view of a region indicated by the arrow of Fig. 7 specified section 'A'. Fig. Figure 9 shows a sectional view along the line CC of Fig. 8. Fig. 10 shows a sectional view along the line DD of Fig. 8. Fig. 11 shows an enlarged view of a region indicated by the arrow of Fig. 7 specified section 'B'. Fig. 12 shows a sectional view along the line EE of Fig. 7. Fig. 13 shows a view showing an alternative arrangement / configuration of Fig. 11 represents. DETAILED DESCRIPTION

[0021] It is understood that the term "vehicle" or "vehicle-" or other synonymous terms as used herein include motor vehicles in general, such as passenger cars including sports utility vehicles (SUVs), buses, trucks, various utility vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuel derived from sources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more power sources, such as both gasoline-powered and electric-powered vehicles.

[0022] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is further understood that the terms "comprise" and / or "comprising," when used in this specification, describe the presence of the specified features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed elements.Throughout the description, unless expressly stated otherwise, the word "comprise" and variations such as "comprises" or "comprising" are understood to imply the inclusion of the recited elements but not the exclusion of any other elements. Furthermore, the terms "...unit," "...er," "...or," and "...module" described in the description refer to units for processing at least one function and operation, and may be realized / implemented by hardware components or software components and combinations thereof.

[0023] Furthermore, the control logic of the present invention may be embodied as non-transitory computer-readable media on a computer-readable medium comprising executable program instructions executed by a processor, controller, or the like. Examples of computer-readable storage media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable recording medium may also be decentralized in network-coupled computer systems such that the computer-readable medium is stored and executed in a distributed manner, e.g., by a telematics server or a controller area network (CAN).

[0024] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. For reference, dimensions of elements or thicknesses of lines shown in the drawings referred to to describe the present disclosure may be exaggerated for clarity. Also, the terms used from now on have been defined in consideration of the functions of the present disclosure and may be changed according to the intention of a user or operator or conventional practice. Accordingly, the terms should be defined based on the entire contents of this specification.

[0025] A fuel cell stack according to an embodiment of the present invention is formed by stacking a plurality of elemental fuel cells (not shown), each comprising a membrane electrode assembly (MEA) (not shown) and a pair of separators 200 and 300 arranged on opposite sides of the MEA, such that in order to form a reaction gas passage / reaction gas channel and a cooling passage / cooling channel between MEAs of adjacent elemental fuel cells, the first separator 200 and the second separator 300 are arranged to face each other (see, for example, Fig. 1, which represents the general configuration / arrangement of a conventional fuel cell).

[0026] As in Fig. 3 and Fig. As shown in Figure 4, according to the present invention, a plurality of manifolds 110, 120, and 130 are formed in at least one end portion of the first separator 200. The plurality of manifolds 110, 120, and 130 may be a first reaction gas manifold 110 that supplies or discharges a first reaction gas, a cooling medium manifold 120 that supplies or discharges a cooling medium, and a second reaction gas manifold 130 that supplies or discharges a second reaction gas, respectively. A plurality of communication ports 111 communicating with the first reaction gas manifold 110 are formed so as to be adjacent to the first reaction gas manifold 110.

[0027] As in Fig. 3 and Fig. 4, a first reaction surface 210 is formed on a surface of the first separator 200 (see Fig. 3), and a first cooling surface 220 is formed on the other surface of the first separator 200 (see Fig. 4). Each of the first reaction surface 210 and the first cooling surface 220 of the first separator 200 includes a reaction region 150 in which an electrochemical reaction takes place, and a guide region 140 disposed between the plurality of manifolds 110, 120, and 130 and the reaction region 150. The reaction region 150 may require a predetermined contact pressure to move the electric current generated according to the electrochemical reaction, and the guide region 140, in which an electrochemical reaction does not take place, is configured to guide a flow of a first reaction gas (fuel or air) and a cooling medium between the manifolds 110, 120, and 130 and the reaction region 150.

[0028] Fig. 3 shows a view illustrating the first reaction surface 210 of the first separator 200. As in Fig. 3, a plurality of first reaction gas guide channels 230 are formed in the guide region 140 of the first reaction surface 210 and accordingly, a flow of a first reaction gas between the reaction region 150 and the first reaction gas distributor 110 can be guided through the plurality of first reaction gas guide channels 230 (see the line indicated by the arrow “a” of Fig. 3 indicated direction).

[0029] As in Fig. 3, the plurality of first reaction gas guide channels 230 are formed to extend from the guide region 140 to the reaction region 150. Thus, the first reaction gas can be moved from the first reaction gas distributor 110 to the first reaction gas guide channel 230 of the guide region 140 through the connecting openings 111, as indicated by the arrow “a” of Fig. 3 is specified.

[0030] Fig. 4 shows a view illustrating a first cooling surface 220 opposite the first reaction surface 210 of the first separator 200. As in Fig. 4, a first cooling medium guide channel 240 is formed in the guide region 140 of the first cooling surface 220 and accordingly, a flow of a cooling medium between the reaction region 150 and the cooling medium distributor 120 can be guided through the first cooling medium guide channel 240 (see the line indicated by the arrow “b” of Fig. 4 indicated direction).

[0031] As in Fig. 4, the first cooling medium guide channel 240 has a first edge-side guide channel 245 extending along the edge of the guide region 140, a plurality of first continuous channels 241 which are continued from the first edge-side guide channel 245, and a plurality of first interrupted (non-continuous) channels 242 which are not continued from the first edge-side guide channel 245.

[0032] The first edge-side guide channel 245 extends along the edge of the guide region 140 and one side thereof is connected to the cooling medium distributor 120.

[0033] The plurality of first through-channels 241 are formed to extend from the first peripheral side guide channel 245, and accordingly, a cooling medium that has passed through the first peripheral side guide channel 245 from the cooling medium distributor 120 can be transferred to the plurality of first through-channels 241 as indicated by the arrow “b” of Fig. 4 is specified.

[0034] Some of the plurality of first through-channels 241 may be connected to communicate with each other through a first communication space 244, and accordingly, the cooling medium transmitted from the cooling medium distributor 120 may be evenly distributed to the plurality of first through-channels 241 through the first communication space 244.

[0035] The plurality of first discontinuous channels 242 are not continued from the first edge-side guide channel 245 and thus the plurality of first discontinuous channels 242 are not connected to the first edge-side guide channel 245.

[0036] As in Fig. 5 and Fig. 6, a plurality of manifolds 110, 120, and 130, each corresponding to the manifolds 110, 120, and 130 of the first separator 200, may also be formed in at least one end portion of the second separator 300. A plurality of connecting holes 131 communicating with the second reaction gas manifold 130 are formed adjacent to the second reaction gas manifold 130.

[0037] As in Fig. 5 and Fig. 6, the second reaction surface 310 is formed on / at a surface of the second separator 300 (see Fig. 5) and the second cooling surface 320 is formed on the other surface of the second separator 300 (see Fig. 6). Each of the second reaction surface 310 and the second cooling surface 320 of the second separator 300 includes a reaction region 150 in which an electrochemical reaction takes place, and a guide region 140 disposed between the plurality of manifolds 110, 120, and 130 and the reaction region 150. The reaction region 150 may require a predetermined contact pressure to move the electric current generated according to the electrochemical reaction, and the guide region 140, in which an electrochemical reaction does not take place, is configured to guide a flow of a second reaction gas (fuel or air) and a cooling medium between the manifolds 110, 120, and 130 and the reaction region 150.

[0038] Fig. 5 shows a view illustrating the second reaction surface 310 of the second separator 300. As in Fig. 5, a plurality of second reaction gas guide channels 330 are formed in the guide region 140 of the second reaction surface 310, and accordingly, a flow of a second reaction gas between the reaction region 150 and the second reaction gas distributor 110 can be guided through the plurality of second reaction gas guide channels 330 (see a view indicated by the arrow “H” of Fig. 5 indicated direction).

[0039] As in Fig. 5, the plurality of second reaction gas guide channels 330 are formed to extend from the guide region 140 to the reaction region 150. Thus, the second reaction gas can be moved from the second reaction gas distributor 130 to the second reaction gas guide channel 330 of the guide region 140 through the connecting openings 131, as indicated by the arrow “H” of Fig. 5 is specified.

[0040] Fig. 6 shows a view illustrating a second cooling surface 330 opposite the second reaction surface 310 of the second separator 300. As in Fig. 6, a second cooling medium guide channel 340 is formed on the second cooling surface 320 and accordingly, a flow of a cooling medium between the reaction region 150 and the cooling medium distributor 120 can be guided through the second cooling medium guide channel 340 (see the line indicated by the arrow “G” of Fig. 6 indicated direction).

[0041] As in Fig. 6, the second cooling medium guide channel 340 has a second edge-side guide channel 345 extending along the edge of the guide region 140, a plurality of second continuous channels 341 which are continued from the second edge-side guide channel 345, and a plurality of second interrupted (non-continuous) channels 342 which are not continued from the second edge-side guide channel 345.

[0042] The plurality of second through-channels 341 are formed to extend from the second peripheral side guide channel 345, and accordingly, a cooling medium that has passed through the second peripheral side guide channel 345 from the cooling medium distributor 120 can be transferred to the plurality of second through-channels 341 as indicated by the arrow “G” of Fig. 6 is given.

[0043] Some of the plurality of second through-channels 341 may be connected to communicate with each other through a second communication space 344, and accordingly, the cooling medium transmitted from the cooling medium distributor 120 may be evenly distributed to the plurality of second through-channels 341 through the second communication space 344.

[0044] The plurality of second discontinuous channels 342 are not continued from the second edge-side guide channel 345 and thus the plurality of second discontinuous channels 342 are not connected to the second edge-side guide channel 345.

[0045] The first separator 200 may be selectively applied as any one of a cathode-side separator and an anode-side separator, and thus the second separator 300 may correspond to the opposite pole of the first separator 200.

[0046] For example, if the first separator 200 is a cathode-side separator that is closely attached to a cathode of the MEA 100 and supplies a gas including oxygen, that is, gas, to the cathode of the MEA 100, the second separator 300 is an anode-side separator that supplies fuel to an anode of the MEA 100.

[0047] Conversely, if the first separator 200 is an anode-side separator that is closely attached to the anode of the MEA 100 and supplies fuel to the anode of the MEA 100, the second separator 300 is a cathode-side separator that supplies gas including oxygen, that is, air, to the cathode of the MEA 100.

[0048] Since a plurality of elementary fuel cells 400 are stacked, the first cooling surface 220 of the first separator 200 and the second cooling surface 320 of the second separator 300 are held to oppose between the mutually adjacent MEAs, as shown in Fig. 7 and Fig. 12 shown.

[0049] In particular, at least portions of the first cooling medium guide channel 240 of the first cooling surface 220 and the second cooling medium guide channel 340 of the second cooling surface overlap each other in an overlapping manner.

[0050] The first edge-side guide channel 245 of the first cooling medium guide channel 240 and the second edge-side guide channel 345 of the second cooling medium guide channel 340 may have the same size and arrangement structure, and accordingly, when the first cooling surface 210 of the first separator 200 and the second cooling surface 320 of the second separator 300 are mounted to correspond to each other, the first edge-side guide channel 245 and the second edge-side guide channel 345 may be maintained with the corresponding structure / arrangement.

[0051] As in Fig. 7 to 10, the first cooling medium guide channel 240 and the second cooling medium guide channel 340 overlap in at least one section to form overlap sections 510 and 520.

[0052] As in Fig. 8 to 10, the first continuous channel 241 of the first cooling medium guide channel 240 may intersect / overlap with the second continuous channel or the second discontinuous channel 342 of the second cooling medium guide channel 340 in a partial section at a predetermined angle in an overlapping manner to form a first overlapping section 510.

[0053] According to an alternative embodiment, the first discontinuous channel 242 of the first cooling medium guide channel 240 may intersect / overlap with the second continuous channel 341 or the second discontinuous channel 342 of the second cooling medium guide channel 340 in a partial section at a predetermined angle in an overlapping manner to form a first overlapping section 510.

[0054] Since the first cooling medium guide channel 240 and the second cooling medium guide channel 340 can communicate with each other through the first overlap portion 510, a cooling medium can flow smoothly between the first cooling medium guide channel 240 and the second cooling medium guide channel 340.

[0055] As in Fig. 11 to 13, one or more second discontinuous channels 342 may partially overlap a first continuous channel 241 or a first discontinuous channel 242 to form one or more second overlap portions 520.

[0056] In a case where two or more second overlap portions 520 are formed, the two or more second overlap portions 520 may be formed so that overlap areas thereof are different in order to distribute a cooling medium flow rate more balanced.

[0057] Fig. Fig. 11 illustrates a structure / arrangement in which two second overlapping portions 520 (521 and 522) are provided, and here, the two second overlapping portions 520 (521 and 522) may be formed to have different overlapping areas. Among the two overlapping portions 520 (521 and 522), the second overlapping portion 522, which is farther away from a flow direction of the cooling medium than the second overlapping portion 521 closer to the flow direction (see U-direction indicated by the arrow of Fig. 11) have a smaller overlap area. In particular, since a larger flow rate / flow volume tends to be directed toward the farther side due to flow inertia of the cooling medium, when the overlap areas of the second overlap portions 520 (521 and 522) are the same, flow rates may be unbalanced. Thus, when the second overlap portion 522 on the farther side has a smaller overlap area than the second overlap portion 521 on the nearer side, the flow rates of the cooling medium can be distributed evenly.

[0058] Fig. 13 illustrates a structure in which three overlapping portions 520 (521, 522, and 523) are formed. The three overlapping portions 520 (521, 522, and 523) may be formed to have different overlapping areas. Among the three overlapping portions 520 (521, 522, and 523), the middle second overlapping portion 521 preferably has the largest overlapping area, and among the two overlapping portions 522 and 523 arranged from both sides of the middle second overlapping portion 521, the second overlapping portion 523, which is farther away from the flow direction of the cooling medium than the second overlapping portion 522 closer to the flow direction (see U-direction indicated by the arrow of Fig. 13) has a smaller overlap area.

[0059] In this way, since one or more second discontinuous channels 342 overlap the first continuous channel 241 or the first discontinuous channel 242 to form one or more second overlapping portions 520, the cooling medium can be branched or connected between the first discontinuous channel 242 and the second discontinuous channel 342, whereby the cooling medium can flow smoothly between the first cooling medium guide channel 240 of the first separator 200 and the second cooling medium guide channel 340 of the second separator 300, thereby ensuring a smooth flow of the cooling medium.

[0060] According to an alternative embodiment, since one or more discontinuous channels 242 partially overlap a second continuous channel 341 or a second discontinuous channel 342, one or more second overlapping sections 520 may be formed.

[0061] In the present invention described above, since the cooling medium flows smoothly to be properly distributed or connected between the first cooling medium guide channel 240 and the second cooling medium guide channel 340 through the first overlap portion 510 and the second overlap portion 520, the flow of the cooling medium can be uniform with respect to the reaction surface 210 of the first separator 200 and the reaction surface 310 of the second separator 300. Furthermore, since the distances between the cooling medium guide channels 240 and 340 in the guide region are significantly reduced compared to the prior art, even a thin plate with an elongation of 60% or less can have significantly improved formability.

[0062] Meanwhile, as in Fig.7, the first and second separators 200 and 300 have a central reaction section K1 in which the highest temperatures are distributed after a chemical reaction of the reaction surface, and outer reaction sections K2 and K3 arranged on both the left and right sides of the central reaction section K1.

[0063] In the central reaction section K1, a second overlap section 520 is formed to be more than the two or more second overlap sections 520, and thus a flow rate of the cooling medium in the central reaction section K1 can be increased.

[0064] In the outer reaction sections K2 and K3, two or more overlapping sections 520 are formed to be more than the one second overlapping section 520, and thus a flow of the cooling medium in the outer reaction sections K2 and K3 can be reduced.

[0065] As a result, a proportion of the two or more second overlapping portions 520 in the outer reaction portions K2 and K3 is larger than in the central reaction portion K1, whereby the heat transfer efficiency can be maximized by varying a cooling flow according to a temperature distribution in the reaction region.

[0066] As described above, according to the present invention, the heat transfer efficiency can be remarkably improved by increasing a machining accuracy of the cooling channel in the guide portion of each separator and effectively distributing a cooling medium.

[0067] In particular, since the distances of the cooling medium guide channel in the guide region are greatly increased compared to the prior art, even with a material having an elongation of 60% or less, the formability of a cooling channel in the guide region of the separator can be significantly improved.

[0068] In the above, although the present disclosure has been described with reference to embodiments and the accompanying drawings, the present disclosure is not limited thereto, but can be variously modified and changed by one of ordinary skill in the art relating to the present invention without departing from the spirit and scope of the present disclosure as claimed in the following claims. REFERENCE NUMBERS OF EACH OF THE ELEMENTS IN THE FIGURES 200 first separator 210 first reaction surface 230 first reaction gas guide channel 220 first cooling surface 240 first cooling medium guide channel 241 first continuous canal 242 first non-through channel 245 first edge side guide channel 300 second separator 310 second reaction surface 320 second cooling surface 330 second reaction gas guide channel 340 second cooling medium guide channel 345 second edge side guide channel 341 second continuous canal 342 second non-through channel 510 first overlap section 520 Overlap section

Claims

[1] A fuel cell stack formed by stacking elementary fuel cells each having a membrane electrode assembly (MEA) and a pair of separators arranged on opposite sides of the MEA, comprising: a first separator (200) and a second separator (300) held opposite each other between adjacent MEAs and each having a plurality of manifolds, a reaction region, and a guide region arranged between the plurality of manifolds and the reaction region; a first cooling medium guide channel (230) which guides a flow of a cooling medium between the plurality of distributors and the reaction region formed in the guide region of the first separator (200); a second cooling medium guide channel (330) which guides a flow of a cooling medium between the plurality of distributors and the reaction region formed in the guide region of the second separator (300); and wherein at least portions of the first cooling medium guide channel (230) and the second cooling medium guide channel (330) are overlapped to communicate with each other, wherein the first cooling medium guide channel (230) comprises a first edge-side guide channel (245) extending along the edge of the guide region, a plurality of first continuous channels (241) continued from the first edge-side guide channel (245), and a plurality of first discontinuous channels (242) discontinuous from the first edge-side guide channel (245). [2] The fuel cell stack according to claim 1, wherein some of the plurality of first through channels (241) are connected to each other to communicate with each other through a first communication space. [3] The fuel cell stack according to claim 1, wherein the second cooling medium guide channel (330) comprises a second edge-side guide channel (345) extending along the edge of the guide portion, a plurality of second continuous channels (341) continued from the second edge-side guide channel (345), and a plurality of second discontinuous channels (342) discontinuous from the second edge-side guide channel (345). [4] The fuel cell stack according to claim 3, wherein some of the plurality of second through channels (341) are connected to each other to communicate with each other through a second communication space. [5] The fuel cell stack according to claim 3, wherein the first cooling medium guide channel (230) and the second cooling medium guide channel (330) overlap each other in at least one portion at a predetermined angle in an overlapping manner to form one or more overlapping portions (510, 520). [6] The fuel cell stack according to claim 5, wherein the plurality of first continuous channels (241) intersect with the plurality of second continuous channels (341) or the plurality of second discontinuous channels (342) in partial sections at a predetermined angle in the overlapping manner to form first overlapping sections (510). [7] The fuel cell stack according to claim 6, wherein the plurality of first discontinuous channels (242) intersect with the plurality of second continuous channels (341) or the plurality of second discontinuous channels (342) in partial sections at a predetermined angle in the overlapping manner to form first overlapping sections (520). [8] The fuel cell stack of claim 5, wherein one or more second discontinuous channels partially overlap a first continuous channel to form one or more second overlap portions (520). [9] The fuel cell stack of claim 5, wherein one or more second discontinuous channels partially overlap a first discontinuous channel to form one or more second overlap portions (520). [10] The fuel cell stack of claim 5, wherein one or more first discontinuous channels partially overlap a second continuous channel to form one or more overlap portions (510, 520). [11] The fuel cell stack of claim 5, wherein one or more first discontinuous channels partially overlap a second discontinuous channel to form one or more overlap portions (510, 520). [12] The fuel cell stack according to claim 8, wherein, when two or more second overlap portions (520) are formed, the two or more second overlap portions (520) are formed to have different overlap areas. [13] The fuel cell stack according to claim 12, wherein, among the two or more second overlapping portions, a second overlapping portion (520) which is further away from a flow direction of the cooling medium than a second overlapping portion (520) closer to the flow direction has a smaller overlapping area. [14] The fuel cell stack according to claim 13, wherein the first and second separators (200, 300) each have a central reaction section in which the highest temperatures are distributed according to a chemical reaction of a reaction surface (210, 310), and outer reaction sections arranged on both the left and right sides of the central reaction section, and a proportion of the two or more overlap sections (510, 520) in the outer reaction sections is larger than in the central reaction section.

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