Fuel cell

A fuel cell of the disclosure includes a cell stack including a plurality of unit cells stacked in a first direction, an end plate disposed on at least one of the two ends of the cell stack, a heating element disposed between the end plate and the cell stack, and a heater connector embedded in the end plate and electrically connected to the heating element. The end plate includes a core having a first rigidity and having a first recess defined therein to receive at least a portion of the heater connector, a reinforcement plate covering the first recess and having a second rigidity, and a clad having a third rigidity less than each of the first rigidity and the second rigidity and disposed so as to envelop the heater connector and to cover the core and the reinforcement plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2022-0073423, filed on Jun. 16, 2022, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Implementations relate to a fuel cell.

BACKGROUND

In general, in a fuel cell, each of a plurality of unit cells generates electricity using air supplied to one surface of a polymer electrolyte membrane and hydrogen supplied to the opposite surface of the polymer electrolyte membrane. An end plate may be disposed on each of both ends of a cell stack composed of a plurality of unit cells, and a heater wiring connector may be disposed on each end plate. The heater wiring connector may receive a drive signal (voltage or current) necessary to drive a heating element from the cell stack. In addition, the end plate may include a metal portion and a resin portion, and the heater wiring connector may be seated on the metal portion and may be attached thereto by the resin portion.

In this case, in the end plate that is in contact with a gasket, which is disposed between each of the first cell and the last cell of the cell stack and the end plate, a resin portion corresponding to the portion on which the heater wiring connector is disposed is not flat, which adversely affects seal reliability at the interface between the cell stack and the end plate, leading to degradation of the quality of the stack. Therefore, research with the goal of solving this problem is underway.

SUMMARY

Accordingly, implementations are directed to a fuel cell that substantially obviates one or more problems due to limitations and disadvantages of the related art.

Implementations provide a fuel cell having excellent seal reliability.

However, objects to be accomplished by the implementations are not limited to the above-mentioned objects, and other objects not mentioned herein will be clearly understood by those skilled in the art from the following description.

A fuel cell according to an implementation may include a cell stack including a plurality of unit cells stacked in a first direction, an end plate disposed on at least one of the two ends of the cell stack, a heating element disposed between the end plate and the cell stack, and a heater connector embedded in the end plate and electrically connected to the heating element. The end plate may include a core having a first rigidity and having a first recess defined therein to receive at least a portion of the heater connector, a reinforcement plate covering the first recess and having a second rigidity, and a clad having a third rigidity less than each of the first rigidity and the second rigidity and disposed so as to envelop the heater connector and to cover the core and the reinforcement plate.

In an example, the reinforcement plate and the core may be made of the same material.

In an example, the end plate may further include a second recess defined around the first recess to receive the reinforcement plate.

In an example, the reinforcement plate may be located between a distal end of the end plate and a reaction surface in a second direction intersecting the first direction.

In an example, the reinforcement plate may include a first surface facing the end plate and a second surface located opposite the first surface and facing the cell stack. The inner surface of the end plate that faces the cell stack and the second surface of the reinforcement plate may form the same horizontal surface.

In an example, the clad may include a first portion, which is embedded in the first recess and is disposed between the heater connector and the core and between the heater connector and the reinforcement plate, and a second portion, which covers the second surface of the reinforcement plate and at least a portion of the inner surface of the end plate.

In an example, the end plate may further include a first coupling portion defined in the second recess, and the reinforcement plate may include a second coupling portion coupled to the first coupling portion.

In an example, the fuel cell may further include a screw to couple the first coupling portion and the second coupling portion to each other in a screw-coupling manner.

In an example, the heater connector may include a first terminal connected to the heating element, an extension portion connected to a drive signal driving the heating element, and a connection portion interconnecting the first terminal and the extension portion and embedded in the second recess.

In an example, the connection portion of the heater connector may include a third surface facing the end plate in the first direction and a fourth surface located opposite the third surface and facing the cell stack in the first direction.

In an example, the connection portion may include a body in which a wire is embedded, the wire interconnecting the first terminal and the extension portion and a support leg protruding from the body toward the bottom surface of the first recess in the first direction.

In an example, the end plate may include a first end plate disposed on one of the two ends of the cell stack and a second end plate disposed on the other of the two ends of the cell stack. The first end plate may include an oxygen inlet receiving air introduced thereinto from the outside, a hydrogen inlet receiving hydrogen introduced thereinto from the outside, a hydrogen outlet discharging hydrogen therethrough from the cell stack to the outside, and an oxygen outlet discharging oxygen therethrough from the cell stack to the outside. The second end plate may include a coolant inlet receiving a cooling medium introduced thereinto from the outside and a coolant outlet discharging the cooling medium therethrough to the outside.

In an example, the heater connector may be disposed between the hydrogen inlet and the oxygen outlet in the first end plate or between the oxygen inlet and the hydrogen outlet in the first end plate.

In an example, the heater connector may be disposed at a periphery of the coolant inlet or the coolant outlet in the second end plate.

DETAILED DESCRIPTION

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

It will be understood that when an element is referred to as being “on” or “under” another element, it may be directly on/under the element, or one or more intervening elements may also be present.

When an element is referred to as being “on” or “under”, “under the element” as well as “on the element” may be included based on the element.

In addition, relational terms, such as “first”, “second”, “on/upper part/above” and “under/lower part/below”, are used only to distinguish between one subject or element and another subject or element, without necessarily requiring or involving any physical or logical relationship or sequence between the subjects or elements.

Hereinafter, a fuel cell100according to an implementation will be described with reference to the accompanying drawings. The fuel cell100will be described using the Cartesian coordinate system (x-axis, y-axis, z-axis) for convenience of description, but may also be described using other coordinate systems. In the Cartesian coordinate system, the x-axis, the y-axis, and the z-axis are perpendicular to each other, but the implementations are not limited thereto. That is, the x-axis, the y-axis, and the z-axis may intersect each other obliquely. Hereinafter, for convenience of description, the +x-axis direction or the −x-axis direction will be referred to as a “first direction”, the +y-axis direction or the −y-axis direction will be referred to as a “second direction”, and the +z-axis direction or the −z-axis direction will be referred to as a “third direction”.

FIG.1is a perspective view showing the external appearance of a fuel cell100according to an implementation, andFIG.2is a cross-sectional view for explaining a cell stack (or a power generation module)122included in the fuel cell100according to an implementation. Illustration of the enclosure280shown inFIG.1is omitted fromFIG.2.

The fuel cell100may be, for example, a polymer electrolyte membrane fuel cell (or a proton exchange membrane fuel cell) (PEMFC), which has been studied most extensively as a power source for driving vehicles. However, the implementations are not limited to any specific form of fuel cell.

The fuel cell100may include end plates (or pressing plates or compression plates)110A and110B, a cell stack122, an enclosure280, and first and second heater assemblies300A and300B.

The enclosure280shown inFIG.1may be coupled to the end plates110A and110B, and may be disposed so as to surround at least part of the side portions of the cell stack122disposed between the end plates110A and110B. The enclosure280may serve to clamp a plurality of unit cells together with the end plates110A and110B in the first direction. In other words, the clamping pressure of the cell stack122may be maintained by the end plates110A and110B, which have rigid body structures, and the enclosure280. However, the clamping pressure of the cell stack122may be maintained without using the enclosure280. The implementations are not limited to any specific configuration for maintaining the clamping pressure.

The end plates may be disposed on at least one of the two end portions of the cell stack122, and may support and fix a plurality of unit cells. That is, the first end plate110A may be disposed on one of the two end portions of the cell stack122, and the second end plate110B may be disposed on the other of the two end portions of the cell stack122.

The fuel cell100may include a plurality of manifolds M. The manifolds may include a first inflow communication portion (or a first inlet manifold) IN1, a second inflow communication portion (or a second inlet manifold) IN2, a third inflow communication portion (or a third inlet manifold) IN3, a first outflow communication portion (or a first outlet manifold) OUT1, a second outflow communication portion (or a second outlet manifold) OUT2, and a third outflow communication portion (or a third outlet manifold) OUT3.

One of the first and second inflow communication portions IN1and IN2may correspond to a hydrogen inlet through which hydrogen, which is a reactant gas, is introduced into the cell stack122from the outside, and the other of the first and second inflow communication portions IN1and IN2may correspond to an oxygen inlet through which oxygen, which is a reactant gas, is introduced into the cell stack122from the outside. In addition, one of the first and second outflow communication portions OUT1and OUT2may correspond to a hydrogen outlet through which hydrogen, which is a reactant gas, and condensed water are discharged out of the cell stack122, and the other of the first and second outflow communication portions OUT1and OUT2may correspond to an oxygen outlet through which oxygen, which is a reactant gas, and condensed water are discharged out of the cell stack122.

In an example, the first inflow communication portion IN1may correspond to a hydrogen inlet, the second inflow communication portion IN2may correspond to an oxygen inlet, the first outflow communication portion OUT1may correspond to a hydrogen outlet, and the second outflow communication portion OUT2may correspond to an oxygen outlet.

In addition, the third inflow communication portion IN3may correspond to a coolant inlet through which a cooling medium (e.g. coolant) is introduced from the outside, and the third outflow communication portion OUT3may correspond to a coolant outlet through which a cooling medium is discharged to the outside.

The first and second outflow communication portions OUT1and OUT2may be disposed below the first and second inflow communication portions IN1and IN2, the first inflow communication portion IN1and the first outflow communication portion OUT1may be disposed at positions separated from each other in an oblique direction, and the second inflow communication portion IN2and the second outflow communication portion OUT2may be disposed at positions separated from each other in an oblique direction. Due to this arrangement of the first and second inflow communication portions IN1and IN2and the first and second outflow communication portions OUT1and OUT2, condensed water may be discharged from the lower portions of the unit cells included in the cell stack122, or may remain in the lower portions of the unit cells due to gravity.

According to one implementation, the first and second inflow communication portions IN1and IN2and the first and second outflow communication portions OUT1and OUT2may be included in any one of the first and second end plates110A and110B (e.g. the first end plate110A, as shown inFIG.1), and the third inflow communication portion IN3and the third outflow communication portion OUT3may be included in the other of the first and second end plates110A and110B (e.g. the second end plate110B shown inFIG.1).

According to another implementation, all of the first to third inflow communication portions IN1to IN3and the first to third outflow communication portions OUT1to OUT3may be included in any one of the first and second end plates110A and110B.

Referring toFIG.2, the cell stack122may include a plurality of unit cells122-1to122-N, which are stacked in the first direction. Here, “N” is a positive integer of 1 or greater, and may range from several tens to several hundreds. “N” may be determined depending on the intensity of the power to be supplied from the fuel cell100to a load. Here, “load” may refer to a part requiring power in a vehicle that uses the fuel cell.

The membrane electrode assembly210has a structure in which catalyst electrode layers, in which electrochemical reactions occur, are attached to both sides of an electrolyte membrane through which hydrogen ions move. Specifically, the membrane electrode assembly210may include a polymer electrolyte membrane (or a proton exchange membrane)212, a fuel electrode (a hydrogen electrode or an anode)214, and an air electrode (an oxygen electrode or a cathode)216. In addition, the membrane electrode assembly210may further include a sub-gasket238.

The polymer electrolyte membrane212is disposed between the fuel electrode214and the air electrode216.

Hydrogen, which is the fuel in the fuel cell100, may be supplied to the fuel electrode214through the first separator242, and air containing oxygen as an oxidizer may be supplied to the air electrode216through the second separator244.

The hydrogen supplied to the fuel electrode214is decomposed into hydrogen ions (protons) (H+) and electrons (e−) by the catalyst. The hydrogen ions alone may be selectively transferred to the air electrode216through the polymer electrolyte membrane212, and at the same time, the electrons may be transferred to the air electrode216through the gas diffusion layers222and224and the separators242and244, which are conductors. In order to realize the above operation, a catalyst layer may be applied to each of the fuel electrode214and the air electrode216. The movement of the electrons described above causes the electrons to flow through an external conductive wire, thus generating current. That is, the fuel cell100may generate electric power due to the electrochemical reaction between hydrogen, which is the fuel, and oxygen contained in the air.

In the air electrode216, the hydrogen ions supplied through the polymer electrolyte membrane212and the electrons transferred through the separators242and244meet oxygen in the air supplied to the air electrode216, thus causing a reaction that generates water (hereinafter referred to as “condensed water” or “product water”). The condensed water generated in the air electrode216may penetrate the polymer electrolyte membrane212and may be transferred to the fuel electrode214.

In some cases, the fuel electrode214may be referred to as an anode, and the air electrode216may be referred to as a cathode. Alternatively, the fuel electrode214may be referred to as a cathode, and the air electrode216may be referred to as an anode.

The gas diffusion layers222and224serve to uniformly distribute hydrogen and oxygen, which are reactant gases, and to transfer the generated electrical energy. To this end, the gas diffusion layers222and224may be disposed on respective sides of the membrane electrode assembly210. That is, the first gas diffusion layer222may be disposed on the left side of the fuel electrode214, and the second gas diffusion layer224may be disposed on the right side of the air electrode216.

The first gas diffusion layer222may serve to diffuse and uniformly distribute hydrogen supplied as a reactant gas through the first separator242, and may be electrically conductive.

The second gas diffusion layer224may serve to diffuse and uniformly distribute air supplied as a reactant gas through the second separator244, and may be electrically conductive.

Each of the first and second gas diffusion layers222and224may be a microporous layer in which fine carbon fibers are combined. However, the implementations are not limited to any specific forms of the first and second gas diffusion layers222and224.

The gaskets232,234, and236serve to maintain the airtightness and clamping pressure of the cell stack at an appropriate level with respect to the reactant gases and the coolant, to disperse the stress when the separators242and244are stacked, and to independently seal the flow paths.

The separators242and244may serve to move the reactant gases and the cooling medium and to separate each of the unit cells from the other unit cells. In addition, the separators242and244may serve to structurally support the membrane electrode assembly210and the gas diffusion layers222and224and to collect the generated current and transfer the collected current to a current collector340.

The separators242and244may be respectively disposed outside the gas diffusion layers222and224. That is, the first separator242may be disposed on the left side of the first gas diffusion layer222, and the second separator244may be disposed on the right side of the second gas diffusion layer224.

The first separator242serves to supply hydrogen as a reactant gas to the fuel electrode214through the first gas diffusion layer222. To this end, the first separator242may include an anode plate (AP), in which a channel (i.e. a passage or a flow path) is defined so that hydrogen is capable of flowing therethrough.

The second separator244serves to supply air as a reactant gas to the air electrode216through the second gas diffusion layer224. To this end, the second separator244may include a cathode plate (CP), in which a channel is defined so that air containing oxygen is capable of flowing therethrough. In addition, each of the first and second separators242and244may form a channel through which a cooling medium is capable of flowing.

Further, the separators242and244may be made of a graphite-based material, a composite graphite-based material, or a metal-based material. However, the implementations are not limited to any specific material of the separators242and244.

For example, each of the first and second separators242and244may include the first to third inflow communication portions IN1, IN2, and IN3and the first to third outflow communication portions OUT1, OUT2, and OUT3, or may include some of the communication portions.

In other words, the reactant gases required for the membrane electrode assembly210may be introduced into the cell through the first and second inflow communication portions IN1and IN2, and gas or liquid, in which the reactant gases humidified and supplied to the cell and the condensed water generated in the cell are combined, may be discharged to the outside of the fuel cell100through the first and second outflow communication portions OUT1and OUT2.

In addition, the fuel cell100may further include a heater assembly. The heater assembly serves to raise the temperature of the cell stack122when the cell stack122in a cooled state is started up. To this end, the heater assembly may include at least one of a first heater assembly300A or a second heater assembly300B. In an example, as shown inFIG.2, the heater assembly may include both the first heater assembly300A and the second heater assembly300B. Alternatively, the heater assembly may include only one of the first heater assembly300A and the second heater assembly300B. The first heater assembly300A may be disposed between the cell122-1, which is located on one of the two end portions of the cell stack122, and an inner surface110AI of the first end plate110A, and the second heater assembly300B may be disposed between the cell122-N, which is located on the other of the two end portions of the cell stack122, and an inner surface110BI of the second end plate110B.

According to one implementation, as shown inFIG.2, each of the first and second heater assemblies300A and300B may include a current collector340, a heating element (a heater or a planar heating element)330, and a pad (an insulation pad or a silicon pad)320. In addition, each of the first and second heater assemblies300A and300B may include a heater plate (or a bypass plate)310. For better understanding of the positions at which the current collector340, the heating element330, the pad320, and the heater plate310are disposed, the current collector340, the heating element330, the pad320, and the heater plate310are illustrated schematically inFIG.2, and the concrete configurations of these components310,320,330, and340will be described later.

According to another implementation, unlike what is shown inFIG.2, each of the first and second heater assemblies300A and300B may include the current collector340, the heating element330, the pad320, and the end plates110A and110B. That is, unlike the above implementation, according to this implementation, the first end plate110A serves as the first heater plate310of the first heater assembly300A, and the second end plate110B serves as the second heater plate310of the second heater assembly300B, so the heater plate310may be omitted from each of the first and second heater assemblies300A and300B. With this exception, since the first and second heater assemblies300A and300B according to this implementation are the same as the first and second heater assemblies300A and300B according to the above implementation, a duplicate description thereof will be omitted.

Hereinafter, the first and second heater assemblies300A and300B will be described with reference toFIG.2. The following description of the first and second heater assemblies300A and300B shown inFIG.2may also apply to the case described later in which each of the end plates110A and110B serves as the heater plate310.

The current collector340may be disposed between each of the first and second end plates110A and110B, which face the cell stack122, and the cell stack122.

That is, the current collector340included in the first heater assembly300A may be disposed between the heating element330and one (e.g.122-1) of the two end portions of the cell stack122. The current collector340included in the second heater assembly300B may be disposed between the heating element330and the other (e.g.122-N) of the two end portions of the cell stack122.

The current collector340serves to collect electrical energy generated by the flow of electrons in the cell stack122and to supply the same to the load of the vehicle in which the fuel cell100is used. In an example, the current collector340may be implemented as a metal plate, which is made of an electrically conductive material, and may be conductively connected to the cell stack122.

The heating element330may be disposed between at least one of the two end portions of the cell stack122and the end plates110A and110B. In an example, referring toFIG.2, the heating element330of the first heater assembly300A may be disposed between one (e.g.122-1) of the two end portions of the cell stack122and the first end plate110A, and the heating element330of the second heater assembly300B may be disposed between the other (e.g.122-N) of the two end portions of the cell stack122and the second end plate110B.

In an example, the heating element330may include a heating part, which is composed of a carbon paste and an electrode, and a protective film part, which is configured such that a polyethylene terephthalate (PET) layer disposed on both surfaces of the heating part, an aluminum layer disposed on both surfaces of the PET layer, and a PET layer disposed on both surfaces of the aluminum layer are sequentially stacked.

Further, in the heating element330, the pattern of the heating part, which is composed of the carbon paste and the electrode, may take any of various forms, and the heat density may be adjusted for each part by changing the pattern of the heating part. Furthermore, the heating element330may be implemented as a planar heating element, for example, a polymer positive temperature coefficient (PTC) heating element. If moisture permeates the carbon paste performing a PTC function for a long time, heat generation performance is eventually deteriorated. In order to prevent permeation of moisture, a PET film is attached to the carbon paste and the electrode, thereby improving resistance to moisture.

In particular, the heating element330may be further provided with an aluminum thin film and a PET film, which have high resistance to moisture. In this case, in order to prevent the withstand voltage performance from being deteriorated by the presence of aluminum, which is conductive, the aluminum thin film may be manufactured to have a smaller size than the PET film, thereby improving not only moisture resistance characteristics but also withstand voltage characteristics.

Further, in some implementations, thermal grease or a thermal pad may be interposed between the heating element330and the current collector340so as to ensure close contact therebetween. Due to the thermal pad or the thermal grease interposed between the heating element330and the current collector340in order to improve heat conductivity, the heat generated by the heating element330may be efficiently transferred to the unit cells122-nof the cell stack122via the current collector340.

The pad320blocks the heat generated by the heating element330from traveling in the direction in which the cell stack122faces the end plates110A and110B, and causes a larger amount of heat to travel to the cell stack122. In this way, the pad320may exhibit a thermal insulation function of preventing heat loss. In addition, the pad320may also serve to buffer the clamping pressure of the cell stack122. To this end, the pad320may be disposed between the end plates110A and110B and the heating element330. For example, the pad320may be implemented as a foamed silicon sheet, and may prevent damage to the film-type heating element330when assembled with the heater plate310and the heating element330so as to be stacked in close contact therewith. However, the implementations are not limited to any specific material of the pad320. Alternatively, the pad320may be omitted from the fuel cell100according to the implementation.

In addition, as shown inFIG.3to be described later, the pad320may have a through-hole TH defined therein to allow a first terminal T1of a heater connector (or a heater wiring connector) and a second terminal T2of the heating element330to be in contact with and connected to each other, which will be described later.

The heater plate310is conceptually a dummy cell, which is a unit cell disposed at the outermost position in the direction in which the unit cells122-nare stacked in the cell stack122. The heater plate310may be formed in the shape of a plate corresponding to the external shape of the unit cells122-n.

In addition, the heater plate310may have communication portions penetrating both side surfaces thereof in the first direction, for example, the first and second inflow communication portions IN1and IN2and the first and second outflow communication portions OUT1and OUT2.

In addition, the heater plate310may be implemented as a single plate, as shown in the drawings.

Alternatively, unlike what is shown in the drawings, the heater plate310may be configured such that a plurality of unit heater plates, e.g. three unit heater plates, is stacked in the first direction. Similar to the membrane electrode assembly210in which the fuel electrode214, the polymer electrolyte membrane212, and the air electrode216are assembled into an integral form, the three unit heater plates constituting the heater plate310may be stacked in the first direction.

The heater plate310may be disposed on at least one of the two end portions122-1and122-N of the cell stack122. For example, as shown inFIG.2, the first heater plate310of the first heater assembly300A may be disposed between the first end plate110A and one (e.g.122-1) of the two end portions of the cell stack122, and the second heater plate310of the second heater assembly300B may be disposed between the second end plate110B and the other (e.g.122-N) of the two end portions of the cell stack122.

In addition, the heater plate310may be configured such that a metallic pipe is integrally formed with a plastic body through insert injection molding, and the pipe may form flow channels (e.g. a hydrogen channel and an oxygen channel). However, the implementations are not limited to any specific material of the heater plate310.

Hereinafter, the heater connector and the end plates according to the implementation will be described in more detail with reference to the accompanying drawings. Since the end plates110A and110B respectively serve as the heater plates310A and310B of the first and second heater assemblies300A and300B, the following description will be made on the assumption that the heater plates310A and310B are omitted. Therefore, the heater connector may be disposed on at least one of the first end plate110A or the second end plate110B, in place of the heater plates310A and310B.

Hereinafter, the fuel cell according to the implementation will be described as including both the heater connector disposed on the first end plate110A and the heater connector disposed on the second end plate110B. However, the following description may also apply to the case in which the heater connector is disposed on only one of the first and second end plates110A and110B.

FIG.3is an exploded perspective view of the first heater assembly300A according to an implementation,FIG.4Aillustrates the configurations of the first end plate110A and the heater connector400A according to an implementation, andFIG.4Billustrates the configuration of the heating element330according to an implementation. Illustration of the current collector340is omitted fromFIG.3. For better understanding, portions that are disposed inside and are invisible from the outside are denoted by dotted lines inFIG.4A.

FIG.5is a front view of the second end plate110B and the heater connector400B according to an implementation,FIG.6Ais an assembled cross-sectional view taken along line I-I′ shown inFIG.5, andFIG.6Bis an exploded cross-sectional view taken along line I-I′ shown inFIG.5. For better understanding, the portion of the heater connector400B that is disposed inside and is invisible from the outside is denoted by dotted lines inFIG.5. In addition, illustration of the screws430and the first and second coupling portions CP1and CP2shown inFIG.6Bis omitted fromFIG.6A.

Each of the first and second end plates110A and110B may include a core (or a metal insert) and a clad (or a resin material). In an example, as shown inFIG.6A, the second end plate110B may include a core114B and clads116B1and116B2. In some implementations, the first end plate110A may also include a core and clads, like the configuration shown inFIG.6A. In addition, the first end plate110A may further include a reinforcement plate410A, and the second end plate110B may further include a reinforcement plate410B.

In this case, according to the implementation, the core may be enveloped by the clads.

The core114B may have a first rigidity, each of the reinforcement plates410A and410B may have a second rigidity, and each of the clads116B1and116B2may have a third rigidity. Here, the third rigidity may be less than each of the first rigidity and the second rigidity. In an example, the first rigidity and the second rigidity may be equal to each other. That is, the material of the reinforcement plates410A and410B and the material of the core114B may be the same as each other.

For example, the material of each of the core114B and the reinforcement plates410A and410B may be a metal material, such as aluminum or SUS, and the material of the clads116B1and116B2may be an insulative resin material. Here, the resin material may be a synthetic resin rubber-based material or plastic, but the implementations are not limited to any specific material of the resin material. The core114B of each of the first and second end plates110A and110B may be characterized by high rigidity in order to withstand the internal surface pressure, and may be embodied by machining a metal material.

In an example, each of the first and second end plates110A and110B may be defined by coupling a plurality of plates to each other. However, the implementations are not limited to any specific number of plates constituting each of the first and second end plates110A and110B.

Hereinafter, for convenience of description, the heater connector400A disposed on the first end plate110A will be referred to as a “first heater connector”, the heater connector400B disposed on the second end plate110B will be referred to as a “second heater connector”, and the first or second heater connector400A or400B will be referred to as a “heater connector”.

As shown inFIG.4A, in the first end plate110A, the first heater connector400A may be disposed between the oxygen inlet IN2and the hydrogen outlet OUT1. Alternatively, unlike what is shown inFIG.4A, the first heater connector400A may be disposed between the hydrogen inlet IN1and the oxygen outlet OUT2. As shown inFIG.5, in the second end plate110B, the second heater connector400B may be disposed near the coolant inlet IN3. Alternatively, unlike what is shown inFIG.5, the second heater connector400B may be disposed near the coolant outlet OUT3.

FIG.7is a perspective view showing an implementation of the second heater connector400B.

Each of the first and second heater connectors400A and400B may include a first terminal, an extension portion, and a connection portion. In an example, as shown inFIG.4A, the first heater connector400A may include a first terminal T1, extension portions OT1and OT2, and a connection portion Y, and as shown inFIG.7, the second heater connector400B may include a first terminal402, an extension portion404, and a connection portion406.

As shown inFIG.4A, the connection portion Y of the first heater connector400A is disposed between the oxygen inlet IN2and the hydrogen outlet OUT1, and thus has a straight shape, rather than being curved. On the other hand, the connection portion406of the second heater connector400B is disposed near the coolant inlet IN3, and thus has a curved shape that bypasses the coolant inlet IN3.

Except for the difference in position and shape between the first heater connector400A and the second heater connector400B, the first heater connector400A is the same as the second heater connector400B, and the first end plate110A is the same as the second end plate110B. Therefore, with regard to any aspect of any one of the first and second end plates110A and110B that is not described in detail, reference may be made to the description of the other of the first and second end plates110A and110B, and with regard to any aspect of any one of the first and second heater connectors400A and400B that is not described in detail, reference may be made to the description of the other of the first and second heater connectors400A and400B.

Referring toFIGS.6A and6B, the core114B of the second end plate110B may have a first recess H1defined therein. The first recess H1serves to receive at least part of the second heater connector400B, i.e. the connection portion406. In addition, at least a portion of the first terminal402of the second heater connector400B may be received in the first recess H1.

The reinforcement plate410B may be disposed so as to cover the first recess H1.

In addition, as shown inFIGS.4A and4B, the reinforcement plate410A may be disposed in a first region AR1between a distal end110AOE of the first end plate110A and a reaction surface112A thereof in the second direction. As shown inFIG.5, the reinforcement plate410B may be disposed in a second region AR2between a distal end110BOE of the second end plate110B and a reaction surface112B thereof in the second direction. That is, the length ly of the reinforcement plate410B in the second direction may correspond to the spacing distance between the distal end110BOE of the second end plate110B and the reaction surface112B thereof in the second direction.

The regions AR1and AR2in which the reinforcement plates410A and410B are disposed are regions in which gaskets are disposed. These regions have more influence on the flatness of the fuel cell than other portions.

In addition, each of the reinforcement plates410A and410B may have a length in the third direction so as to completely encompass an airtight line. For example, the length lz of the reinforcement plate410B in the third direction may be a length encompassing not only the airtight line but also a space in which the second coupling portion CP2to be described later is defined.

In addition, the reinforcement plate410B may include a first surface S1, which faces the second end plate110B in the first direction, and a second surface S2, which is located opposite the first surface S1and faces the cell stack122in the first direction.

According to the implementation, the second surface S2of the reinforcement plate410B and the inner surface110BI of the second end plate110B, which face the cell stack122in the first direction, may form the same horizontal surface HS. As such, in the case in which the inner surface110BI and the second surface S2form the same horizontal surface HS, the flatness of the surface adjacent to the cell stack122is ensured, whereby surface pressure may be uniformly distributed on the reaction surfaces112A and112B of the cell stack122.

The clad may include a first portion116B1and a second portion116B2.

The first portion116B1may be disposed so as to be received in the first recess H1and to envelop the second heater connector400B. That is, referring toFIG.6A, the first portion116B1may be disposed between the second heater connector400B and the core114B and between the second heater connector400B and the reinforcement plate410B. Since the first portion116B1is disposed so as to envelop the connection portion406of the heater connector400B, which is disposed in the first recess H1, the connection portion406and the core114B may be electrically isolated from each other, and the connection portion406and the reinforcement plate410B may be electrically isolated from each other.

The second portion116B2may be disposed so as to cover the second surface S2of the reinforcement plate410B and at least a portion of the inner surface110BI of the second end plate110B (i.e. the upper surface of the core114B). Illustration of the second portion116B2is omitted fromFIG.6B.

In addition, the second end plate110B may further have therein a second recess H2defined around the first recess H1. The second recess H2serves to receive the reinforcement plate410B.

In addition, the second end plate110B may include a first coupling portion CP1in the second recess H2, and the reinforcement plate410B may include a second coupling portion CP2coupled to the first coupling portion CP1.

According to one implementation, the first coupling portion CP1and the second coupling portion CP2may be coupled to each other in a force-fitting manner. For example, one of the first coupling portion CP1and the second coupling portion CP2may be formed in the shape of a coupling protrusion, and the other of the first coupling portion CP1and the second coupling portion CP2may be formed in the shape of a coupling recess into which the coupling protrusion is inserted.

According to another implementation, the first coupling portion CP1and the second coupling portion CP2may be screwed to each other. To this end, referring toFIG.6B, the fuel cell may further include a screw430, the first coupling portion CP1may be formed to have the cross-sectional shape of a blind hole in which the screw430is received and secured, and the second coupling portion CP2may be formed to have the cross-sectional shape of a through-hole through which the screw430passes.

However, the implementations are not limited to any specific manner of coupling between the first coupling portion CP1and the second coupling portion CP2or to any specific shape thereof.

The first heater connector400A may be embedded in the first end plate110A so as to be electrically connected to the heating element330, and the second heater connector400B may be embedded in the second end plate110B so as to be electrically connected to the heating element330. That is, the first and second heater connectors400A and400B may receive a drive signal (voltage or current) necessary to drive the heating element330from outside the first and second end plates110A and110B (e.g. the cell stack122), and may transfer the received drive signal to the heating element330. To this end, as shown inFIG.4A, the first terminal T1of the first heater connector400A may be connected to the heating element330. In some implementations, the first terminal402of the second heater connector400B may also be connected to the heating element330in the same manner as shown inFIGS.4A and4B. In addition, each of the extension portions OT1and OT2of the first heater connector400A and the extension portion404of the second heater connector400B may be connected to a drive signal. The connection portion Y of the first heater connector400A may electrically connect the first terminal T1and the extension portions OT1and OT2to each other, and the connection portion406of the second heater connector400B may electrically connect the first terminal402and the extension portion404to each other.

According to the implementation, the first terminals T1and402and the extension portions OT1and OT2may be electrically connected to each other via wires. In an example, referring toFIG.4A, the connection portion Y of the first heater connector400A may include two wires HW1and HW2for electrically connecting the first terminals T1(T11and T12) to the extension portions OT1and OT2.

The first wire HW1may serve to connect the first terminal T1(T11) to the extension portion OT1, and the second wire HW2may serve to connect the first terminal T1(T12) to the extension portion OT2. That is, one of the two ends of the first wire HW1may be connected to the first terminal T11, and the other of the two ends of the first wire HW1may be connected to the extension portion OT1. One of the two ends of the second wire HW2may be connected to the first terminal T12, and the other of the two ends of the second wire HW2may be connected to the extension portion OT2.

In an example, the first terminal T1may include a pair of male heater terminals T11and T12, and the second terminal T2may include a pair of female heater terminals T21and T22. In another example, the first terminal T1may include a pair of female heater terminals T11and T12, and the second terminal T2may include a pair of male heater terminals T21and T22. The first terminals T11and T12and the second terminals T21and T22may be electrically connected to each other in a female-male coupling manner. However, the implementations are not limited to any specific manner of coupling between the first terminal T1and the second terminal T2.

The connection portions406of the second heater connector400B may include a third surface S3and a fourth surface S4. In an example, as shown inFIG.6B, the third surface S3is a surface that faces the second end plate110B in the first direction, and the fourth surface S4is a surface that is located opposite the third surface S3and faces the cell stack122in the first direction.

The connection portion406may include a body BO and a support leg L. The body BO is a portion in which the wires HW1and HW2connecting the first terminal402to the extension portion404are embedded, and the support leg L is a portion that protrudes from the body BO toward the bottom surface HBS of the first recess H1in the first direction. Although the case in which four support legs L are provided is illustrated inFIG.7, the implementations are not limited to any specific number of support legs L.

By virtue of the support leg L, the third surface S3of the connection portion406and the bottom surface HBS of the first recess H1may be spaced apart from each other, with the first portion116B1interposed therebetween. This will be described later in detail when a manufacturing method is described.

Hereinafter, a method of manufacturing the fuel cell according to the implementation, in which the heater connector is assembled to the end plate, will be described with reference to the accompanying drawings.

FIGS.8A to8Dare perspective views for explaining processes of a method of manufacturing the fuel cell according to the implementation.

The core114B of the second end plate110B, which has the configuration shown inFIG.8A, is prepared.

Thereafter, as shown inFIG.8B, the connection portion406of the second heater connector400B is seated in the first recess H1in the core114B.

Thereafter, as shown inFIG.8C, the reinforcement plate410B is disposed in the second recess H2, and is then coupled to the core114B using the screw430.

Thereafter, as shown inFIG.8D, the first portion116B1of the clad is embedded in the first recess H1through an injection molding process, and the second portion116B2is applied to the reinforcement plate410B and the core114B. In this case, if the connection portion406is not provided with the support leg L, the third surface S3of the connection portion406may come into contact with the bottom surface HBS of the first recess H1, and thus the first portion116B1may not be formed between the third surface S3and the bottom surface HBS. However, according to the implementation, since the connection portion406includes the support leg L, when the connection portion406is seated in the first recess H1and subsequently the first portion116B1is embedded in the first recess H1, a resin material is charged into the first recess H1in the state in which the third surface S3of the connection portion406is spaced apart from the bottom surface HBS of the first recess H1by the support leg L. Accordingly, the first portion116B1may be disposed between the third surface S3of the connection portion406and the bottom surface HBS of the first recess H1. As a result, it is possible to ensure electrical isolation of the connection portion406from the core114B due to the support leg L.

Hereinafter, a fuel cell according to a comparative example and the fuel cell according to the implementation will be described with reference to the accompanying drawings.

FIG.9is a cross-sectional view of a fuel cell according to a comparative example.

The fuel cell according to the comparative example shown inFIG.9includes a core14B, a heater connector40, and a clad16B. The core14B, the heater connector40, and the clad16B respectively perform the same functions as the core114B, the second heater connector400B, and the clad shown inFIGS.6A and6B, and thus duplicate descriptions thereof will be omitted. That is, unlike the fuel cell according to the implementation, the fuel cell according to the comparative example does not include the reinforcement plate410B. Further, unlike the implementation, the clad16B according to the comparative example is not divided into the first and second portions116B1and116B2, and is embedded in a third recess H3while enveloping the heater connector40.

In the case of the fuel cell according to the comparative example, a portion of the clad16B that is disposed on the inner surface110BI of the core14B of the second end plate110B has a first thickness t1, and a portion of the clad16B that is embedded in the third recess H3while enveloping the heater connector40disposed in the third recess H3has a second thickness t2. For example, the second thickness t2may be at least four times greater than the first thickness t1. Since the second thickness t2is greater than the first thickness t1, as shown inFIG.9, the portion of the clad16B that has the second thickness t2and overlaps the third recess H3in the first direction may contract, and thus the upper part thereof may have a shape that is concavely depressed in the first direction. This phenomenon is more prominent when the second thickness t2is greater. Furthermore, this phenomenon is more prominent in the clad16B covering the second heater connector40located between the cell stack122and the second end plate110B than in the clad covering the first heater connector located between the cell stack122and the first end plate110A. In the case in which the clad16B is concavely depressed as shown inFIG.9, the surface pressure of the fuel cell may be less uniform than in the case in which the clad16B is flat (refer to reference numeral502).

In contrast, according to the implementation, by virtue of the reinforcement plate410B disposed between the second portion116B2and the first portion116B1of the clad, the clad maintains a constant thickness without being concavely depressed, unlike what is shown inFIG.9. Accordingly, the flatness of the clad116B2may be improved, and thus the flatness of the surface adjacent to the cell stack122may also be improved, thereby ensuring uniform distribution of surface pressure.

As described above, airtightness/watertightness may be maintained by the gaskets232,234, and236shown inFIG.2, and thus the flatness of the surface adjacent to the cell stack122that generates electric power may be ensured, whereby surface pressure may be uniformly distributed on the reaction surfaces112A and112B of the cell stack122. Considering this, in the fuel cell according to the implementation, the reinforcement plates410A and410B are disposed in the regions AR1and AR2in which the gaskets are disposed. Accordingly, the flatness of the surface adjacent to the cell stack122may be improved, and thus uniform distribution of surface pressure may be achieved.

Considering that the depression phenomenon shown inFIG.9is more prominent in the clad16B covering the second heater connector40located between the cell stack122and the second end plate110B than in the clad covering the first heater connector located between the cell stack122and the first end plate110A, in the fuel cell according to the implementation, the second end plate110B, in which the second heater connector400B is embedded, includes the reinforcement plate410B, as shown inFIGS.6A and6B, whereas the first end plate110A, in which the first heater connector400B is embedded, may include the reinforcement plate410A, or may not include the reinforcement plate410A.

The fuel cell according to the implementation has been described above as including only one cell stack. However, according to another implementation, the fuel cell may also be applied to the case in which a plurality of cell stacks configured as described above is stacked in the third direction.

As is apparent from the above description, the fuel cell according to the implementation is provided with a reinforcement plate, which enables a clad to maintain a constant thickness without being concavely depressed. Accordingly, the flatness of the clad may be improved, and thus uniform distribution of surface pressure may be achieved.

However, the effects achievable through the disclosure are not limited to the above-mentioned effects, and other effects not mentioned herein will be clearly understood by those skilled in the art from the above description.

The above-described various implementations may be combined with each other without departing from the scope of the present disclosure unless they are incompatible with each other.

In addition, for any element or process that is not described in detail in any of the various implementations, reference may be made to the description of an element or a process having the same reference numeral in another implementation, unless otherwise specified.

While the present disclosure has been particularly shown and described with reference to exemplary implementations thereof, these implementations are only proposed for illustrative purposes, and do not restrict the present disclosure, and it will be apparent to those skilled in the art that various changes in form and detail may be made without departing from the essential characteristics of the implementations set forth herein. For example, respective configurations set forth in the implementations may be modified and applied. Further, differences in such modifications and applications should be construed as falling within the scope of the present disclosure as defined by the appended claims.