Fuel cell

Abstract

A fuel cell includes a cell stack having a plurality of unit cells stacked in a first direction, an end plate provided at an end of the cell stack, and a current collecting plate provided between the end plate and the end of the cell stack. The current collecting plate includes an electrically conductive region having an electrically conductive surface in electrically conductive surface contact with a reaction surface of the end of the cell stack and configured to collect electric power generated by the cell stack, and a gas-tight region having a gas-tight surface in gas-tight surface contact with a non-reaction surface of the end of the cell stack and enclosing the electrically conductive region. The electrically conductive surface protrudes toward the end of the cell stack to a different extent than the gas-tight surface.

Description

TECHNICAL FIELD

[0001] The present invention relates to a fuel cell, and more particularly, to a fuel cell having improved airtightness and electrical conductivity. BACKGROUND

[0002] Generally, a fuel cell includes a cell stack, an end plate, and a current collector plate. The electric power generated using hydrogen and oxygen in the cell stack can be transmitted to the outside through the current collector plate disposed between the cell stack and the end plate.

[0003] However, when the current collector plate does not make surface contact with a reaction surface of an end cell disposed at an end portion of the cell stack or does not make complete surface contact with the reaction surface of the end cell disposed at the end portion of the cell stack, the current collector plate can have difficulty in sufficiently providing an electrical path for transmitting the electric power generated in the cell stack to the outside. In addition, when the current collector plate does not make airtight contact with the end cell, then it can be impossible to uniformly distribute a surface pressure on the reaction surface of the cell stack. SUMMARY

[0004] Accordingly, the present invention relates to a fuel cell that substantially obviates one or more problems due to limitations and disadvantages of the prior art. According to one aspect, the present invention provides a fuel cell having improved airtightness and electrical conductivity.

[0005] A fuel cell according to an exemplary embodiment can include a cell stack having a plurality of unit cells stacked in a first direction, an end plate disposed at an end portion of the cell stack, and a current collector plate disposed between the end plate and the end portion of the cell stack. The current collector plate can include an electrically conductive region having an electrically conductive surface formed in surface contact with a reaction surface of an end portion of the cell stack facing the current collector plate in the first direction, wherein the electrically conductive region is configured to collect electric power generated by the cell stack, and an airtight region having an airtight surface formed in surface contact with a non-reaction surface of the end portion of the cell stack facing the current collector plate in the first direction, wherein the airtight region surrounds the electrically conductive region. The electrically conductive surface protrudes toward the end portion of the cell stack in the first direction to a different extent than the airtight surface protrudes toward the end portion of the cell stack in the first direction.

[0006] For example, each of the plurality of unit cells can include a membrane electrode assembly, a gas diffusion layer disposed on each of both sides of the membrane electrode assembly, a separator disposed outside the gas diffusion layer to separate each of the plurality of unit cells from another unit cell, and a cell frame connected to the membrane electrode assembly, the gas diffusion layer, and the separator. For example, the airtight surface can protrude further toward the end portion of the cell stack in the first direction than the electrically conductive surface.

[0007] Further, the current collecting plate includes a main body having an electrically conductive surface in contact with a surface of a separator at a first side thereof, the separator being an end portion of the battery stack, and a current collecting frame configured to fill a space between a second side of the main body and the separator in the gas-tight region. For example, the main body and the current collecting frame can be integrally formed with each other or separately disposed from each other.

[0008] The material of the battery frame and the material of the current collecting frame can be the same as or different from each other. For example, at least one of the battery frame and the current collecting frame has at least one of elasticity and electrical insulation. The electrically conductive surface can further protrude toward the end portion of the battery stack than the gas-tight surface in the first direction.

[0009] The current collecting plate can include a main body having a gas-tight surface in contact with a battery frame gas-tight surface corresponding to a non-reaction surface at a first side thereof, wherein the main body can have an electrically conductive surface at a second side thereof, the electrically conductive surface protruding toward a gas diffusion layer corresponding to a reaction surface, a separator, or a membrane electrode assembly to be in surface contact therewith. For example, the current collecting plate can include a current collecting portion corresponding to the electrically conductive region, the current collecting portion having electrical conductivity, and an insulating portion corresponding to the gas-tight region, the insulating portion surrounding the current collecting portion and having electrical insulation.

[0010] The insulating portion can include a plurality of manifolds through which a fluid can be introduced from or discharged to the outside. The current collecting plate can further include a current collecting terminal extending from the current collecting portion in a second direction crossing the first direction and configured to provide power to the outside. For example, the insulating portion can have elasticity. The current collecting plate can further include an adhesive bonding the current collecting portion and the insulating portion. For example, the current collecting portion can include at least one through-hole through which at least a portion of the insulating portion passes. BRIEF DESCRIPTION OF DRAWINGS

[0011] Arrangements and exemplary embodiments can be described in detail with reference to the following drawings, in which like reference numerals refer to like elements, in which:

[0012] Figure 1 is a perspective view showing an external appearance of a fuel cell according to an exemplary embodiment of the present application;

[0013] Figure 2 is a perspective view of a fuel cell according to an exemplary embodiment of the present application; Figure 1 is a cross-sectional view of a portion of the fuel cell shown;

[0014] Figure 3 is a front view of a current collecting plate according to an exemplary embodiment of the present application;

[0015] Figure 4 is a cross-sectional view of the current collecting plate taken along line I-I’ shown; Figure 3

[0016] ​Figure 5 is a cross-sectional view of the collector plate taken along line II-II' according to an exemplary embodiment of the present application. Figure 3 is a cross-sectional view of the collector plate taken along line II-II' according to an exemplary embodiment of the present application.

[0017] Figure 6 is a front view of a collector portion according to an exemplary embodiment of the present application.

[0018] Figure 7 is an exemplary cross-sectional view of an end portion of a battery stack according to an exemplary embodiment of the present application.

[0019] Figure 8 is a cross-sectional view showing a combined structure of a battery stack and a collector plate according to an exemplary embodiment of the present application.

[0020] Figure 9 is a cross-sectional view showing a combined structure of a battery stack and a collector plate according to an exemplary embodiment of the present application.

[0021] Figure 10 is a cross-sectional view showing a combined structure of a battery stack and a collector plate according to an exemplary embodiment of the present application.

[0022] Figure 11 is a cross-sectional view showing a combined structure of a collector plate and a battery stack having an exemplary end portion shape according to a comparative example; and

[0023] Figure 12 is a cross-sectional view showing a combined structure of a collector plate and a battery stack having another exemplary end portion shape according to a comparative example. DETAILED DESCRIPTION

[0024] It can be appreciated that the term "vehicle" or "vehicular" or other similar term used herein, includes a general motor vehicle, such as a passenger car, a truck, a bus, a passenger vehicle, a cargo vehicle, various commercial vehicles, a watercraft including various boats and ships, an aircraft, and the like, and includes a hybrid vehicle, an electric vehicle, an internal combustion vehicle, a plug-in hybrid electric vehicle, a hydrogen vehicle, and other alternative fuel vehicles (e.g., fueled by resources other than petroleum).

[0025] While the exemplary embodiments are described as using a plurality of units to perform exemplary processes, it is understood that the exemplary processes can be performed by one or more modules. In addition, it is understood that the term controller / control unit refers to a hardware device that includes a memory and a processor. The memory is configured to store modules, and the processor is specifically configured to execute the modules to perform one or more processes as further explained below.

[0026] Further, the control logic of the present application can be embodied as a non-transitory computer readable medium on a computer readable medium containing executable program instructions executed by a processor, controller / control unit, or the like. Examples of computer readable mediums include, but are not limited to, ROM, RAM, compact discs (CD)-ROM, tape, floppy disks, flash memories, smart cards, and optical data storage devices. The computer readable medium can also be distributed over network coupled computer systems so that the computer readable medium is stored in a distributed fashion throughout the system, for example, over a

[0027] Unless specifically stated or otherwise understood from the context, the word "about" as used herein is understood to be within the normal tolerances of the art, for example within 2 standard deviations of the mean. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise explicitly stated from the context, all numerical values provided herein are modified by the word "about".

[0028] The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which various exemplary embodiments are shown. The examples may, however, be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0029] It will be understood that when an element is referred to as being "on" or "under" another element, it can be directly on / under the element or one or more intervening elements can also be present. In the description of embodiments, when a part is referred to as being "on" or "under" another part, it can be included in the "under" part as well as the "on" part based on the part. In addition, relative terms such as "first", "second", "upper / upper portion / upper side", and "lower / lower portion / lower side" are used only to distinguish one object or element from another object or element, and do not necessarily require or imply any physical or logical relationship or order between the objects or elements.

[0030] Hereinafter, a fuel cell 100 according to an exemplary embodiment will be described with reference to the accompanying drawings. For ease of description, the fuel cell 100 will be described using a Cartesian coordinate system (x-axis, y-axis, z-axis). However, other different coordinate systems can be used. In the drawings, the x-axis, y-axis, and z-axis of the Cartesian coordinate system are perpendicular to each other. However, embodiments are not limited thereto. In other words, the x-axis, y-axis, and z-axis can intersect each other. Hereinafter, the x-axis direction can be referred to as a "first direction", the z-axis direction can be referred to as a "second direction", and the y-axis direction can be referred to as a "third direction".

[0031] Figure 1 is a perspective view illustrating an outer appearance of a fuel cell 100 according to an exemplary embodiment. The fuel cell 100 can be, for example, a polymer electrolyte membrane fuel cell (or a proton exchange membrane fuel cell) (PEMFC), which has been widely studied as a power source to drive a vehicle. However, the exemplary embodiments are not limited to any particular form of the fuel cell 100.

[0032] The fuel cell 100 can include first and second end plates (e.g., press plates or compression plates) 110A and 110B, first and second current collector plates 112A and 112B, and a cell stack 122. The cell stack 122 can include a plurality of unit cells stacked with each other in a first direction. Each of the first end plate 110A and the second end plate 110B can be disposed at both ends of the cell stack 122 and can support and fix the unit cells. In other words, the first end plate 110A can be disposed at a first end of the cell stack 122, and the second end plate 110B can be disposed at a second end (e.g., opposite to the first end) of the cell stack 122.

[0033] In addition, the fuel cell 100 can further include a clamping member (not shown). The clamping member can clamp the unit cells together with the first and second end plates 110A and 110B in the first direction. For example, the clamping member can have a rod shape, a long bolt shape, a belt shape, or a rigid rope shape to clamp the unit cells. Alternatively, the clamping member can have a housing shape to clamp the unit cells. However, the fuel cell according to an embodiment is not limited to any particular shape of the clamping member.

[0034] According to an exemplary embodiment, as Figure 1 illustrated, the first end plate 110A can include first to third inlet communication portions (or inlet manifolds) MI1, MI2, and MI3 and first to third outlet communication portions (or outlet manifolds) MO1, MO2, and MO3. According to another exemplary embodiment, unlike as illustrated in Figure 1 , a portion of the first to third inlet communication portions MI1, MI2, and MI3 and a portion of the first to third outlet communication portions MO1, MO2, and MO3 can be disposed on the second end plate 110B, instead of being disposed on the first end plate 110A. However, the exemplary embodiments are not limited to any particular position of the first to third inlet communication portions MI1, MI2, and MI3 and the first to third outlet communication portions MO1, MO2, and MO3. The first to third inlet communication portions MI1, MI2, and MI3 and the first to third outlet communication portions MO1, MO2, and MO3 will be described in more detail later.

[0035] Figure 2 is Figure 1Cross-sectional views of the first and second end plates 110A and 110B, the first and second current collecting plates 112A and 112B, and the cell stack 122 in the fuel cell 100 shown. For ease of description, Figure 1 the current collecting terminals 316 of each of the first and second current collecting plates 112A and 112B shown in FIG. 1 are not shown in Figure 2 , and will be described later in detail with reference to Figure 3 , Figure 5 and Figure 6 .

[0036] Figure 2 The first and second end plates 110A and 110B, the first and second current collecting plates 112A and 112B, and the cell stack 122 shown in Figure 1 correspond to the first and second end plates 110A and 110B, the first and second current collecting plates 112A and 112B, and the cell stack 122 shown in FIG. 1, respectively, and thus the same reference numerals are used to denote the same components.

[0037] Referring to Figure 2 , the cell stack 122 can include a plurality of unit cells 122-1 to 122-N stacked in a first direction. In particular, “N” is a positive integer of 1 or more, and can be in the range of several tens to several hundreds. “N” can be determined according to the strength of the electric power provided from the fuel cell 100 to a load. In addition, the “load” can refer to a part of a vehicle that requires power. Each unit cell 122-n can include a membrane electrode assembly (MEA) 210, first and second gas diffusion layers (GDLs) 222 and 224, a plurality of gaskets 232, 234, and 236, and first and second separators (or bipolar plates) 242 and 244. Here, 1 ≤ n ≤ N.

[0038] The membrane electrode assembly 210 has a structure in which a catalyst electrode layer in which an electrochemical reaction occurs can be attached to both sides of an electrolyte membrane in which hydrogen ions move through. Specifically, the membrane electrode assembly 210 can include a polymer electrolyte membrane (or a proton exchange membrane) 212, a fuel electrode (hydrogen electrode or anode) 214, and an air electrode (oxygen electrode or cathode) 216. In addition, the membrane electrode assembly 210 can further include a sub-gasket 238.

[0039] The polymer electrolyte membrane 212 can be disposed between the fuel electrode 214 and the air electrode 216. Hydrogen gas, which is a fuel in the fuel cell 100, can be supplied to the fuel electrode 214 through the first separator 242, and air containing oxygen, which is an oxidizing agent, can be supplied to the air electrode 216 through the second separator 244.

[0040] The hydrogen gas supplied to the fuel electrode 214 is decomposed into hydrogen ions (protons) (H+) and electrons (e-) by the catalyst. Only the hydrogen ions can be selectively transported to the air electrode 216 through the polymer electrolyte membrane 212, while the electrons can be transported to the air electrode 216 through the first and second gas diffusion layers 222 and 224 and the first and second separators 242 and 244, which are conductors.

[0041] To achieve the above operation, a catalyst layer can be applied to each of the fuel electrode 214 and the air electrode 216. The movement of the above-described electrons causes the electrons to flow through an external lead, thereby generating an electric current. In other words, the fuel cell 100 can be configured to generate electric power through an electrochemical reaction between hydrogen gas as a fuel and oxygen gas contained in air.

[0042] In the air electrode 216, the hydrogen ions supplied through the polymer electrolyte membrane 212 and the electrons transported through the first and second separators 242 and 244 meet oxygen gas supplied to the air electrode 216, thereby causing a reaction to generate water ("condensed water" or "product water"). The condensed water generated in the air electrode 216 can pass through the polymer electrolyte membrane 212 and can be transported to the fuel electrode 214. In some cases, the fuel electrode 214 can be referred to as a negative electrode, and the air electrode 216 can be referred to as a positive electrode. Alternatively, the fuel electrode 214 can be referred to as an anode, and the air electrode 216 can be referred to as a cathode.

[0043] The first and second gas diffusion layers 222 and 224 uniformly distribute the hydrogen gas and the oxygen gas, which are reaction gases, and transport generated electric power. Accordingly, the first and second gas diffusion layers 222 and 224 can be disposed on both sides of the membrane electrode assembly 210. In other words, the first gas diffusion layer 222 can be disposed on the left side of the fuel electrode 214, and the second gas diffusion layer 224 can be disposed on the right side of the air electrode 216.

[0044] The first gas diffusion layer 222 can be configured to diffuse and uniformly distribute the hydrogen gas, which is a reaction gas, supplied through the first separator 242, and can be electrically conductive. The second gas diffusion layer 224 can be configured to diffuse and uniformly distribute the air, which is a reaction gas, supplied through the second separator 244, and can be electrically conductive. Each of the first and second gas diffusion layers 222 and 224 can be a microporous layer in which fine carbon fibers are incorporated. However, the present application is not limited to any particular configuration of the first and second gas diffusion layers 222 and 224.

[0045] The gaskets 232, 234, and 236 can be configured to maintain the gas tightness and clamping pressure of the cell stack at an appropriate level with respect to the reaction gas and coolant to distribute stress when the first and second separators 242 and 244 are stacked and independently seal the flow paths. Thus, since the gas tightness and water tightness can be maintained by the gaskets 232, 234, and 236, the flatness of the surface adjacent to the cell stack 122 that generates electricity can be ensured, and thus a uniform surface pressure distribution can be achieved on the reaction surface of the cell stack 122. However, the present application is not limited to Figure 2 any particular number or position of the gaskets shown.

[0046] The first separator 242 and the second separator 244 can be configured to move the reaction gas and the cooling medium and separate each unit cell from other unit cells. In addition, the first separator 242 and the second separator 244 can be configured to structurally support the membrane electrode assembly 210 and the first and second gas diffusion layers 222 and 224 and collect and transmit the generated electric current to the first and second current collectors 112A and 112B.

[0047] The first separator 242 and the second separator 244 can be disposed outside the first and second gas diffusion layers 222 and 224, respectively. In other words, the first separator 242 can be disposed at the left side of the first gas diffusion layer 222, and the second separator 244 can be disposed at the right side of the second gas diffusion layer 224.

[0048] The first separator 242 can be configured to supply hydrogen gas, which is a reaction gas, to the fuel electrode 214 through the first gas diffusion layer 222. Thus, the first separator 242 can include an anode plate (AP) in which a channel (i.e., a passage or flow path) is formed to allow the hydrogen gas to flow therethrough. The second separator 244 can be configured to supply air, which is a reaction gas, to the air electrode 216 through the second gas diffusion layer 224. Thus, the second separator 244 can include a cathode plate (CP) in which a channel is formed to allow air containing oxygen to flow therethrough.

[0049] In addition, each of the first and second separators 242 and 244 can form a channel through which a cooling medium (e.g., coolant) can flow. Furthermore, the first and second separators 242 and 244 can be formed of a graphite-based material, a composite graphite-based material, or a metal-based material. However, the present application is not limited to any particular material of the first and second separators 242 and 244. In addition, each of the first and second separators 242 and 244 can include first to third inlet communication portions MI1, MI2, and MI3 and first to third outlet communication portions MO1, MO2, and MO3.

[0050] The first inlet communication portion MI1 and the first outlet communication portion MO1 can be configured to communicate with each other, and hydrogen (or oxygen) as a reaction gas can be introduced from the outside through the first inlet communication portion MI1 and can be discharged through the first outlet communication portion MO1. The second inlet communication portion MI2 and the second outlet communication portion MO2 can be configured to communicate with each other, and oxygen (or hydrogen) as a reaction gas can be introduced from the outside through the second inlet communication portion MI2 and can be discharged through the second outlet communication portion MO2. The third inlet communication portion MI3 and the third outlet communication portion MO3 can be configured to communicate with each other, and a cooling medium can be introduced from the outside through the third inlet communication portion MI3 and can be discharged to the outside through the third outlet communication portion MO3.

[0051] As shown in FIG. 1, Figure 1 When the first outlet communication portion MO1 and the second outlet communication portion MO2 are arranged at positions lower than the first inlet communication portion MI1 and the second inlet communication portion MI2, condensed water can be discharged toward the lower side of the unit cells 122-1 to 122-N or remain at the lower side thereof due to gravity. Each of the first end plate 110A and the second end plate 110B can be configured such that the metal insert is surrounded by a plastic injection-molded product. The metal insert of each of the first end plate 110A and the second end plate 110B can have high rigidity to withstand internal surface pressure and can be formed by machining a metal material. For example, the first end plate 110A and the second end plate 110B can be formed by combining a plurality of plates. However, the present application is not limited to any particular configuration of the first end plate 110A and the second end plate 110B.

[0052] The first current collector plate 112A and the second current collector plate 112B can be disposed between the first end plate 110A and the second end plate 110B at both ends of the cell stack 122 and the inner surfaces 110AI and 110BI of the first end plate 110A and the second end plate 110B facing the cell stack 122 in the first direction. The first current collector plate 112A and the second current collector plate 112B are configured to collect electric energy generated by the flow of electrons in the cell stack 122 and to supply the electric energy to a load of a vehicle using the fuel cell 100.

[0053] Hereinafter, the configuration and operation of an exemplary embodiment 300 of a current collector plate 112A and 112B included in the fuel cell 100 will be described with reference to the accompanying drawings. The first current collector plate 112A and the second current collector plate 112B can have the same configuration and perform the same operation as each other. Accordingly, the current collector plate 300 according to the exemplary embodiment can correspond to each of the first current collector plate 112A and the second current collector plate 112B.

[0054] Figure 3 is a front view of the current collector plate 300 according to the exemplary embodiment, Figure 4 is a sectional view taken along Figure 3a plan view taken along a line I-I' of the current collector 300 shown, and Figure 5 is a right side view taken along a line II-II' of the current collector 300 shown. Referring to Figure 3 , the current collector 300 can include a current collecting portion 310 and an insulating portion 320. Figure 3 to Figure 5

[0055] The current collecting portion 310 can be electrically conductive, and can include an electrically conductive region (or "battery reaction region"), and the insulating portion 320 can surround the current collecting portion 310, which can be electrically non-conductive, and can include a gas-tight region. The electrically conductive region and the gas-tight region will be described in detail later. The insulating portion 320 can include a plurality of manifolds, e.g., first to third inlet communication portions MI1, MI2, and MI3 and first to third outlet communication portions MO1, MO2, and MO3, through which a fluid is introduced from or discharged to the outside.

[0056] In addition, the current collecting portion 310 can be formed of a metal such as aluminum, and the insulating portion 320 can be formed of a material having elasticity and insulating properties, e.g., rubber or plastic. For example, when the material of the current collecting portion 310 is metal and the material of the insulating portion 320 is rubber, the current collector 300 can be manufactured by injecting an elastic rubber material into a metal insert formed by extrusion.

[0057] Figure 6 is a front view of the current collecting portion 310 according to an exemplary embodiment. Figure 6 The current collecting portion 310 shown in FIG. 1A can include a center portion 310I, an outer portion 310O, and a current collecting terminal 316. The center portion 310I can be exposed without being surrounded by the insulating portion 320, and can correspond to an electrically conductive region of the current collector 300.

[0058] The outer portion 310O can be exposed without being surrounded by the insulating portion 320, and can provide a gas-tight region. However, the present application is not limited thereto. For example, in the current collector 300, a region other than the center portion 310I and the current collecting terminal 316, which is an electrically conductive region, can correspond to a gas-tight region of the current collector 300.

[0059] The current collecting terminal 316 can extend from the outer portion 310O in a second direction crossing the first direction, and be configured to provide power to the outside. For example, the current collecting terminal 316 can be in contact with at least one of a terminal block (not shown) and a busbar (not shown), and can transmit power to the outside.

[0060] In addition, the current collector 300 can further include an adhesive 330. For example, as Figure 5 ​As illustrated, the adhesive 330 can bind the current collecting part 310 and the insulating part 320 together. Thus, the binding force of the interface formed between the metal current collecting part 310 and the rubber insulating part 320 can be increased by the adhesive 330.

[0061] In addition, the current collecting part 310 can include at least one through-hole TH (e.g., a hole). For example, as illustrated in FIG. 2A, the current collecting part 310 can include a plurality of through-holes TH. Figure 5 As illustrated, at least a portion of the insulating part 320 can be disposed in the through-hole TH while passing through the through-hole TH. When the insulating part 320, which is, for example, a rubber injection molded product, is disposed in the through-hole TH, the current collecting part 310 can be prevented from being separated when the current collecting plate 300 is manufactured by injecting an elastic rubber material into a metal insert formed by extrusion. In other words, the through-hole TH can function as a locking part for preventing the current collecting part 310 from being separated.

[0062] Hereinafter, various exemplary embodiments 300A, 300B, and 300C of the current collecting plate 300 contacting the end portion of the battery stack 122 while maintaining airtightness and electrical conductivity will be described with reference to the accompanying drawings. Figure 7 is an exemplary cross-sectional view of an end portion of the battery stack 122. Before explaining the contact between the current collecting plate 300 (300A, 300B, or 300C) according to an exemplary embodiment and the end portion of the battery stack 122, an example of the end portion of the battery stack 122 will be described with reference to Figure 7 Figure 7 Figure 2 Components identical to those in

[0063] Referring to Figure 7 , the space between the first separator 242 and the first gas diffusion layer 222 corresponds to a flow path LP1 through which hydrogen gas (or oxygen gas) as a reaction gas moves, the space between the second separator 244 and the second gas diffusion layer 224 corresponds to a flow path LP2 through which oxygen gas (or hydrogen gas) as a reaction gas moves, and the space between the first separator 242 and the second separator 244 corresponds to a flow path LP3 through which a cooling medium moves.

[0064] In addition, each unit cell in the battery stack 122 can further include a battery frame 250. The battery frame 250 can be bound to the membrane-electrode assembly 210, the first and second gas diffusion layers 222 and 224, and the first and second separators 242 and 244 using a method such as bonding or welding.

[0065] Figure 8 to Figure 10 is a cross-sectional view illustrating various binding structures of the battery stack 122 and the current collecting plate 300 (300A, 300B, and 300C) according to an exemplary embodiment. The current collecting plate 300A, 300B, or 300C can include an electrically conductive region and an airtight region. ​​

[0066] The conductive region can be defined as a region having a surface (hereinafter referred to as a "conductive surface") in conductive surface contact with a reaction surface of the end portion of the battery stack 122 facing the current collecting plate 300A, 300B, or 300C in the first direction. The conductive region can collect the electric power generated by the battery stack 122. As described above, the conductive region can correspond to the central region 310I of the current collecting portion 310.

[0067] The airtight region can be defined as a region having a surface (hereinafter referred to as an "airtight surface") in airtight surface contact with a non-reaction surface of the end portion of the battery stack 122 facing the current collecting plate 300A, 300B, or 300C in the first direction. As Figure 3 illustrated, the airtight region can have a shape surrounding the conductive region. In other words, with reference to Figure 3 , the airtight region can correspond to the peripheral portion 310O and the insulating portion 320 of the current collecting portion 310.

[0068] In addition, as Figure 8 to Figure 10 illustrated, the current collecting plate 300A, 300B, or 300C can include first to third regions A1, A2, and A3. According to an exemplary embodiment, as Figure 9 illustrated, the entire first region A1 can be included in the airtight region SA, and the entire second region A2 can be included in the conductive region CA.

[0069] According to another exemplary embodiment, as Figure 8 and Figure 10 illustrated, the entire first region A1 can be included in the airtight region, a portion of the second region A2 can be included in the conductive region CA, and the remaining portion of the second region A2 can be included in the airtight region SA. In addition, the third region A3 can be included in at least one of the airtight region SA or the conductive region CA. For example, as Figure 8 illustrated, the third region A3 can be included in the airtight region SA. As Figure 9 illustrated, a portion of the third region A3 can be included in the airtight region SA, and the remaining portion thereof can be included in the conductive region CA. As Figure 10 illustrated, the entire third region A3 can be included in the airtight region SA.

[0070] In the current collecting plate 300A, 300B, or 300C according to an exemplary embodiment, the degree (e.g., length) to which the conductive surface protrudes toward the end portion of the battery stack 122 in the first direction and the degree to which the airtight surface protrudes toward the end portion of the battery stack 122 in the first direction can be different from each other. The degrees to which the conductive surface and the airtight surface protrude can vary based on the shape of the end portion of the battery stack 122. The degrees to which the conductive surface and the airtight surface protrude can be determined to secure airtightness and conductivity with the end portion of the battery stack 122.

[0071] According to an example embodiment, the gas-tight surface can further protrude in the first direction than the conductive surface toward the end of the cell stack 122. For example, as shown in FIG. 3A, the gas-tight surface SS1 of the current collecting plate 300A can further protrude in the first direction than the conductive surface CS1 toward the end of the cell stack 122. Figure 8 Figure 8 The current collecting plate 300A shown in FIG. 3A can include a main body 312A and a current collecting frame 314. The main body 312A can include the conductive surface CS1 on a first side thereof, which is in surface contact with the separator 244 that is the end of the cell stack 122. The current collecting frame 314 can be disposed to fill a space between a second side (e.g., an opposite side) of the main body 312A and the separator 244 in the gas-tight region (e.g., SA in A1, A3, and A2).

[0072] The main body 312A and the current collecting frame 314 can be integrally formed with each other. For example, the main body 312A and the current collecting frame 314 can be integrally formed by bonding and / or injection molding. However, according to another example embodiment, the main body 312A and the current collecting frame 314 can be separately disposed. The material of the battery frame 250 and the material of the current collecting frame 314 can be the same as or different from each other.

[0073] At least one of the battery frame 250 and the current collecting frame 314 can exhibit at least one of elasticity and electrical insulation (e.g., insulating properties). For example, Figure 8 Each of the cell frame 250 and the current collecting frame 314 shown in FIG. 3B can exhibit elasticity and electrical insulation. In addition, the material of at least one of the battery frame 250 and the current collecting frame 314 can be the same as that of the gasket shown in FIG. 3B. For example, the material of at least one of the battery frame 250 and the current collecting frame 314 can be ethylene propylene diene monomer rubber (EPDM) or silicon. However, the present application is not limited to any particular material of these components 250 and 314. Figure 2 According to another example embodiment, the conductive surface can further protrude in the first direction than the gas-tight surface toward the end of the cell stack 122. For example, as shown in FIG. 3B, the conductive surface CS2 of the current collecting plate 300B can further protrude in the first direction than the gas-tight surface SS2 toward the end of the cell stack 122.

[0074] Figure 9 In addition, as shown in FIG. 3C, the conductive surface CS3 of the current collecting plate 300C can further protrude in the first direction than the gas-tight surface SS2 toward the end of the cell stack 122. Figure 10

[0075] Figure 9 or Figure 10 ​​​The illustrated current collector 300B or 300C can include only the main body 312B or 312C. The main body 312B or 312C can include a gas-tight surface SS2 formed on a first side thereof, which is in gas-tight surface contact with the battery frame 250 corresponding to the non-reaction surface. As one example, as illustrated, Figure 9 As illustrated, the battery frame 250 and the first gas diffusion layer 222 can be exposed to the end of the cell stack 122, and the first separator 242 and the second separator 244 disposed on the left side of the first gas diffusion layer 222 and indicated by a dashed line can be omitted.

[0076] In particular, the main body 312B can include a conductive surface CS2 formed on a second side thereof, which protrudes in the first direction toward the first gas diffusion layer 222 corresponding to the reaction surface, and is in surface contact with the first gas diffusion layer 222. Since the first separator 242 and the second separator 244 indicated by a dashed line are omitted, the conductive surface CS2 can protrude further in the first direction than Figure 8 The illustrated conductive surface CS1 further protrudes in the first direction toward the first gas diffusion layer 222, which is the end of the cell stack 122.

[0077] As another example, as illustrated, Figure 10 As illustrated, the battery frame 250 and the second separator 244 can be exposed to the end of the cell stack 122, and the first separator 242 and the second separator 244, the first gas diffusion layer 222 and the second gas diffusion layer 224, and the membrane electrode assembly 210 disposed on the left side of the second separator 244 and indicated by a dashed line can be omitted. In particular, the main body 312C can include a conductive surface CS3 formed on a second side thereof, which protrudes toward the second separator 244 corresponding to the reaction surface, and is in surface contact with the second separator 244. Since the membrane electrode assembly 210, the first separator 242 and the second separator 244, and the first gas diffusion layer 222 and the second gas diffusion layer 224 are omitted, the conductive surface CS3 can protrude further in the first direction than Figure 8 The illustrated conductive surface CS1 or Figure 9 The illustrated conductive surface CS2 further protrudes in the first direction toward the second separator 244, which is the end of the cell stack 122.

[0078] As yet another example, although not illustrated, when the battery frame 250 and the membrane electrode assembly 210 are exposed to the end of the cell stack 122, and when the first separator 242 and the second separator 244 and the first gas diffusion layer 222 disposed on the left side of the membrane electrode assembly 210 are omitted, the main body 312C can include a conductive surface formed on a second side (e.g., an opposite side) thereof, which protrudes toward the membrane electrode assembly 210 corresponding to the reaction surface, and is in surface contact with the membrane electrode assembly 210.

[0079] Hereinafter, a current collecting plate according to a comparative example and current collecting plates according to exemplary embodiments will be compared and described. Figure 11 and Figure 12 are cross-sectional views showing a combination structure of a current collecting plate 30 according to a comparative example and a battery stack 122 having various end shapes.

[0080] Figure 11 and Figure 12 the same components in the battery stack 122 shown in Figure 7 the same components in the battery stack 122 shown in

[0081] When the end of the battery stack 122 has the same shape as that shown in Figure 11 in the comparative example, the conductive surface S1 facing the end of the battery stack 122 is in surface contact with the separator 244 that is a reaction surface of the battery stack 122, so that the electrical conductivity can be ensured, while the gas-tight surface S2 is spaced apart from the end of the battery stack 122, so that the gas-tightness cannot be ensured.

[0082] or, when the end of the battery stack 122 has the same shape as that shown in Figure 12 in the comparative example, the gas-tight surface S2 can be in surface contact with the cell frame 250 of the battery stack 122, so that the gas-tightness can be ensured, while the conductive surface S1 facing the end of the battery stack 122 can be spaced apart from the first gas diffusion layer 222 that is a reaction surface of the battery stack 122 and not in surface contact with the first gas diffusion layer 222, so that the electrical conductivity can not be ensured. Thus, the current collecting plate 30 according to the comparative example can not transfer the power generated by the battery stack 122 to the outside.

[0083] On the other hand, in the case of the current collecting plates 300A, 300B, and 300C according to exemplary embodiments, as shown in Figure 8 to Figure 10 depending on the shape of the end of the battery stack 122, the extent to which the conductive surface protrudes in the first direction toward the end of the battery stack 122 and the extent to which the gas-tight surface protrudes in the first direction toward the end of the battery stack 122 can be set to be different from each other, so that the gas-tightness and the electrical conductivity can be ensured.

[0084] In addition, when the current collecting plate 30 according to the comparative example is formed entirely of metal, the manufacturing cost and weight thereof can increase. In particular, the inside of the manifold can be corroded by the reaction gas and the cooling medium. To address these problems, when the inside of the manifold is sealed using a grommet, the manufacturing cost and weight can further increase.

[0085] On the other hand, in the case of the current collecting plate 300 (300A, 300B, or 300C) according to the exemplary embodiment, since the conductive region can be made of metal and the insulating portion 320 occupying most of the airtight region can be made of an insulating material, the manufacturing cost and weight thereof can be less than those of the current collecting plate 30 according to the comparative example. In addition, in the case of the current collecting plate 300 (300A, 300B, or 300C) according to the exemplary embodiment, since the first to third inlet communication portions MI1, MI2, and MI3 and the first to third outlet communication portions MO1, MO2, and MO3 as the manifold can be located in the insulating portion 320, even without sealing the inside of the manifold using the grommet used in the comparative example, it is possible to prevent the manifold from being corroded, thereby securing the electrical insulation and corrosion resistance. In addition, since a separate member such as the grommet is not required compared to the comparative example, it is possible to simplify the manufacturing process, further reduce the manufacturing cost, and further reduce the weight.

[0086] When the current collecting plate 30 according to the comparative example is formed entirely of metal, heat can be dissipated in the first direction to the third direction due to the high thermal conductivity of the metal. On the other hand, in the case of the current collecting plate of the fuel cell according to the exemplary embodiment, the current collecting portion 310 can be made of metal and the insulating portion 320 can be made of an insulating material such as rubber, which has a lower heat transfer coefficient than metal.

[0087] Therefore, compared to the comparative example, the heat capacity of the current collecting plate 300 is minimized, and the heat dissipated therefrom to the outside is minimized. Thus, it is possible to form a heat transfer path through which heat is more effectively transferred in the first direction. Since the heat transfer path is formed, heat is transferred from the heating element to the end cell along the heat transfer path without loss, and thus it is possible to rapidly increase the temperature of the fuel cell. In addition, in the case of the current collecting plate 300A shown, when external clamping pressure is applied to the fuel cell, the current collecting frame 314 having elasticity can perform a shock absorbing function with respect to the end portion of the cell stack 122 (e.g., the end cell provided at the end portion of the cell stack 122). Figure 8

[0088] ​In addition, in the current collector plate according to the comparative example, the current collecting terminal can be provided to pass through the end plate. On the other hand, the current collecting terminal 316 of the current collector plate 300 according to the exemplary embodiment protrudes in a second direction crossing the first direction. Therefore, compared to the comparative example, the length of the fuel cell according to the exemplary embodiment in the first direction can be reduced, and the power extraction path can be simplified. In other words, the fuel cell according to the exemplary embodiment can be made compact.

[0089] As is apparent from the foregoing description, the exemplary embodiment provides a fuel cell that ensures airtightness and electrical conductivity between the current collector plate and the cell stack, ensures electrical insulation and corrosion resistance, reduces manufacturing costs and weight, simplifies the manufacturing process, has a high temperature rise speed, and has a compact structure.

[0090] As long as the above-described various embodiments can be combined with each other without departing from the object of the present application, as long as they do not contradict each other, the above-described various embodiments can be combined with each other. In addition, for any element not described in detail for any one of the various exemplary embodiments, a description thereof can be referred to for the element having the same reference numeral in another exemplary embodiment.

[0091] Although the present application has been particularly shown and described with reference to exemplary embodiments thereof, these exemplary embodiments are presented by way of illustration only, and are not intended to limit the present application, and it will be apparent to those skilled in the art that various changes in form and details can be made therein without departing from the essential characteristics of the exemplary embodiments set forth herein. For example, various configurations set forth in the exemplary embodiments can be modified and applied. Furthermore, differences in such modifications and applications should be interpreted as falling within the scope of the present application defined by the appended claims.

Claims

1. A fuel cell comprising: a cell stack having a plurality of unit cells stacked along a first direction; an end plate provided at an end of the cell stack; and a current collecting plate provided between the end plate and the end of the cell stack; wherein the current collecting plate includes: a conductive region having a conductive surface formed in surface contact with a reaction surface of the end of the cell stack facing the current collecting plate in the first direction, wherein the conductive region is used to collect electric power generated by the cell stack; and a gas-tight region having a gas-tight surface formed in surface contact with a non-reaction surface of the end of the cell stack facing the current collecting plate in the first direction, wherein the gas-tight region surrounds the conductive region, wherein the extent to which the conductive surface protrudes toward the end of the cell stack in the first direction differs from the extent to which the gas-tight surface protrudes toward the end of the cell stack in the first direction, and wherein the entire gas-tight surface is in surface contact with the non-reaction surface. each of the plurality of unit cells includes:

2. The fuel cell of claim 1, wherein, a membrane electrode assembly; a gas diffusion layer provided on each of both sides of the membrane electrode assembly; a separator provided outside the gas diffusion layer to separate each of the plurality of unit cells from other unit cells; and a cell frame connected to the membrane electrode assembly, the gas diffusion layer, and the separator. the gas-tight surface protrudes further toward the end of the cell stack in the first direction than the conductive surface.

3. The fuel cell of claim 2, wherein, the current collecting plate includes:

4. The fuel cell of claim 3, wherein, a main body having a conductive surface on a first side thereof in surface contact with the separator, the separator being the end of the cell stack; and a current collecting frame for filling a space between a second side of the main body and the separator in the gas-tight region. the main body and the current collecting frame are integrally formed with each other.

5. The fuel cell of claim 4, wherein, the main body and the current collecting frame are separate from each other.

6. The fuel cell of claim 4, wherein, the material of the cell frame and the material of the current collecting frame are the same as each other.

7. The fuel cell of claim 4, wherein, the material of the cell frame and the material of the current collecting frame are different from each other.

8. The fuel cell of claim 4, wherein, at least one of the cell frame and the current collecting frame has at least one of elasticity and electrical insulation.

9. The fuel cell of claim 4, wherein, the conductive surface protrudes further toward the end of the cell stack in the first direction than the gas-tight surface.

10. The fuel cell of claim 2, wherein, the current collecting plate includes:

11. The fuel cell of claim 10, wherein, a main body having a gas-tight surface on a first side thereof in surface contact with a cell frame corresponding to the non-reaction surface; wherein the main body has a conductive surface on a second side thereof protruding toward the gas diffusion layer corresponding to the reaction surface, the separator, or the membrane electrode assembly to be in surface contact therewith. the current collecting plate includes:

12. The fuel cell of claim 1, wherein, a current collecting portion corresponding to the conductive region, the current collecting portion having electrical conductivity; and an insulating portion corresponding to the gas-tight region, the insulating portion surrounding the current collecting portion and having electrical insulation. the insulating portion includes a plurality of manifolds through which a fluid is introduced from or discharged to the outside.

13. The fuel cell of claim 12, wherein, ​ 14. The fuel cell of claim 12, wherein, The current collecting plate further includes a current collecting terminal extending from the current collecting portion in a second direction crossing the first direction, wherein the current collecting terminal is used to provide electric power to the outside.

15. The fuel cell of claim 12, wherein, The insulating portion has elasticity.

16. The fuel cell of claim 12, wherein, The current collecting plate further includes an adhesive for bonding the current collecting portion and the insulating portion.

17. The fuel cell of claim 12, wherein, The current collecting portion includes at least one through hole through which at least a portion of the insulating portion passes.

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