KR102895452B1 - Cell of fuel cell, fuel cell stack and manufacturing method of the same - Google Patents

Abstract

A fuel cell stack according to the present invention comprises: a plurality of fuel cell cells that receive gas and air to generate power and are stacked; and an adhesive applied between adjacent fuel cell cells among the plurality of fuel cell cells to combine the adjacent fuel cell cells and to disappear under a predetermined condition; wherein the fuel cell cells include: a power generation unit that receives the gas and the air to produce power; and a separator plate that is coupled to both sides of the power generation unit and has an outer groove that is concavely formed on a surface that does not contact the power generation unit so that a cooling water can flow therethrough; and wherein the adhesive is applied to the outer grooves of the adjacent fuel cell cells to combine the adjacent separator plates with each other.

Description

Fuel cell cell, fuel cell stack and manufacturing method thereof {CELL OF FUEL CELL, FUEL CELL STACK AND MANUFACTURING METHOD OF THE SAME}

The present invention relates to a fuel cell cell, a fuel cell stack, and a method for manufacturing the same.

A fuel cell stack is a type of power generation device that produces electricity, the main energy source for fuel cell vehicles. It has a structure in which a fuel electrode to which hydrogen is supplied and an air electrode to which air is supplied are stacked with an electrode membrane assembly in between, and it refers to a device that generates electrical energy through a chemical reaction between oxygen in the air and hydrogen supplied from the outside.

Typically, a fuel cell stack is composed of tens to hundreds of fuel cell cells stacked one on top of the other. Each cell of the fuel cell stack consists of a membrane-electrode assembly (MEA), which is composed of a polymer electrolyte membrane that can move hydrogen ions, a cathode, which is a catalyst layer applied to both sides of the electrolyte membrane so that hydrogen and oxygen can react, and an anode, which is a fuel electrode, and a gas diffusion layer is stacked on the outer parts of the cathode and the anode, and a separator with a flow field formed on the outer side of the gas diffusion layer is placed to supply fuel and discharge water generated by the reaction.

Hydrogen is supplied to the fuel electrode, air (oxygen) is supplied to the air electrode, and coolant for cooling is also supplied to the coolant passage of the separator through the inlet passage of the open end plate.

Accordingly, an oxidation reaction of hydrogen occurs at the fuel electrode, generating hydrogen ions (protons) and electrons. The hydrogen ions and electrons generated at this time move to the air electrode through the electrolyte membrane and the separator, respectively. Through an electrochemical reaction involving the hydrogen ions and electrons moved from the fuel electrode and oxygen in the air, water is generated, and electrical energy is generated from the flow of electrons.

When stacking fuel cell cells to form a fuel cell stack, if an abnormality occurs during a test run, the part with weak or no bond can be separated and the defective part can be replaced.

The present invention has been devised to solve such problems, and provides a reversibly bondable fuel cell, a fuel cell stack, and a method for manufacturing the same.

A fuel cell stack according to an embodiment of the present invention comprises: a plurality of fuel cell cells that receive gas and air to generate power and are stacked; and an adhesive that is applied between adjacent fuel cell cells among the plurality of fuel cell cells to combine the adjacent fuel cell cells and is designed to disappear under a predetermined condition, wherein the fuel cell cells include: a power generation unit that receives the gas and the air to produce power; and a separator plate that is coupled to both sides of the power generation unit and has an outer groove that is concavely formed on a surface that does not come into contact with the power generation unit so that a cooling water can flow therethrough, wherein the adhesive is applied to the outer grooves of the adjacent fuel cell cells to combine the adjacent separator plates with each other.

According to one embodiment of the present invention, a fuel cell cell is a fuel cell in which a plurality of cells are laminated and combined to form a fuel cell stack, the fuel cell cell comprising: a power generation unit that receives gas and air to generate power; and a separator plate that is coupled to both sides of the power generation unit and has an outer groove formed inwardly on an outer surface to define a coolant flow path through which coolant can flow, wherein the separator plate is coupled to another adjacent separator plate by an adhesive that is applied to an inner surface of the outer groove and is designed to disappear under a predetermined condition.

A method for manufacturing a fuel cell stack according to one embodiment of the present invention comprises the steps of: forming a plurality of fuel cell cells by contacting two separators on opposite sides of a power generation unit, respectively; applying an adhesive, which is designed to disappear under a predetermined condition, to an outer groove formed by digging inward on an outer surface of a separator arranged at the outermost side of the fuel cell cells; stacking the plurality of fuel cell cells by contacting the outer surfaces of the separators arranged at the outermost side of each of the plurality of fuel cell cells so that two of the outermost separators are in contact with each other; and forming a fuel cell stack by contacting two supports on opposite sides of the plurality of stacked fuel cell cells and applying pressure inward.

Accordingly, a reversibly bondable fuel cell cell and a fuel cell stack composed of such fuel cell cells can be obtained.

FIG. 1 is a conceptual diagram of a fuel cell stack according to one embodiment of the present invention.
Figure 2 is a conceptual diagram showing a separator assembly according to one embodiment of the present invention.
FIG. 3 is a conceptual diagram showing an enlarged portion of a separator assembly according to one embodiment of the present invention.
FIG. 4 is a cross-sectional view of a fuel cell stack according to one embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. When designating components in each drawing, it should be noted that, where possible, identical components will be given the same reference numerals, even if they appear in different drawings. Furthermore, when describing embodiments of the present invention, detailed descriptions of related known structures or functions will be omitted if they are deemed to hinder understanding of the embodiments of the present invention.

Additionally, terms such as first, second, A, B, (a), (b), etc. may be used to describe components of embodiments of the present invention. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not limited by the terms. When it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

Figure 1 is a conceptual diagram of a fuel cell stack (100) according to one embodiment of the present invention.

A fuel cell stack (100) according to one embodiment of the present invention includes a plurality of fuel cell cells (1). The plurality of fuel cell cells (1) may be stacked in one direction, i.e., a stacking direction (D1), to form a fuel cell stack (100), and supports may be arranged at both ends of the plurality of stacked fuel cell cells (1) to pressurize and fix the plurality of fuel cell cells (1) inward.

A fuel cell cell (1) includes a power generation unit (G) and separators (31, 32). The power generation unit (G) and separators (31, 32) can be stacked to form a fuel cell cell (1). Two separators (31, 32) can be arranged on each side of the power generation unit (G) to form a fuel cell cell (1).

Power generation unit (G)

The power generation unit (G) is a unit that generates power by receiving gas and air, and may include an electrode membrane assembly (10) and a gas diffusion layer (20).

A gas diffusion layer (20) can be arranged on both sides of the electrode membrane assembly (10) centered on the electrode membrane assembly (10) in which a reaction for generating electricity by receiving gas and air occurs. Accordingly, gas and air can be transmitted from the outside of the power generation unit (G) to the electrode membrane assembly (10) on the inside through the gas diffusion layer (20), and the electrode membrane assembly (10) can generate electricity by reacting the received gas and air.

Separator (31, 32)

Fig. 2 is a conceptual diagram illustrating a separator assembly according to one embodiment of the present invention. Fig. 3 is a conceptual diagram illustrating an enlarged portion of a separator assembly according to one embodiment of the present invention.

Referring further to FIGS. 2 and 3, the separator plates (31, 32) will be described. The separator plates (31, 32) can be coupled to both sides of a power generation unit (G) to form a fuel cell cell (1). The separator plates (31, 32) can include a first separator plate (31) coupled to one side of the power generation unit (G) to transfer air to the power generation unit (G), and a second separator plate (32) coupled to the other side of the power generation unit (G) to transfer gas to the power generation unit (G). The first separator plate (31) and the second separator plate (32a) of an adjacent fuel cell can come into contact with each other to form a separator assembly as shown in FIG. 2.

The separator (31, 32) may have an inner side and an outer side. Here, the inner side and the outer side refer to the inner side and the outer side based on the stacking direction (D1) of the entire fuel cell cell (1), and do not refer to the inner side and the outer side of the separator (31, 32) alone.

The outer surface of the separator (31, 32) may not contact the power generation unit (G), but may contact another adjacent separator (31, 32). The outer surface of the first separator (31) may contact the outer surface of the second separator (32), and the outer surface of the second separator (32) may contact the first separator (31). Conversely, the inner surface of the separator (31, 32) may contact the gas diffusion layer (20) of the power generation unit (G).

The inner surface of the separator (31, 32), which is the surface facing the power generation unit (G), may be dug outward to have an inner groove (312, 322). The inner groove (312, 322) may be formed to extend along the flow direction (D2), which is a direction perpendicular to the stacking direction (D1). The inner groove (312, 322) may have a rectangular shape in a cross-section cut along a plane perpendicular to the flow direction (D2), but various shapes may be adopted.

The inner grooves (312, 322) may be formed in multiple numbers and arranged spaced apart from each other in a direction perpendicular to the stacking direction (D1) and the flow direction (D2). In the drawing, five inner grooves (312, 322) are formed, but the number is not limited thereto.

Gas or air can flow through the inner grooves (312, 322). Gas or air can be delivered to the inner grooves (312, 322) of each fuel cell cell (1) through a manifold (M) that the fuel cell stack (100) can include. As the gas or air flows along the inner grooves (312, 322), the gas or air can diffuse into the gas diffusion layer (20) of the power generation unit (G) facing the inner grooves (312, 322) and reach the electrode membrane assembly (10).

A gas path (42, 43) through which gas or air can flow can be defined by the inner grooves (312, 322) and the outer surface of the adjacent power generation unit (G). Air can flow through the gas path (43) defined by the inner groove (312) of the first separator (31), and gas can flow through the gas path (42) defined by the inner groove (322) of the second separator (32). In this way, the fluids flowing through the gas paths (42, 43) formed in the two separator plates (31, 32) included in one fuel cell cell (1) can be different from each other.

The outer surface of the separator (31, 32) may be concavely dug inward to have an outer groove (311, 321). The outer groove (311, 321) may be formed to extend along a flow direction (D2), which is a direction perpendicular to the stacking direction (D1). The outer groove (311, 321) may have a rectangular shape in a cross-section cut along a plane perpendicular to the flow direction (D2), but various shapes may be adopted.

The outer grooves (311, 321) may be configured in multiple numbers and arranged spaced apart from each other in a direction perpendicular to the stacking direction (D1) and the flow direction (D2). In the drawing, five outer grooves (311, 321) are formed on each separator plate (31, 32), but the number is not limited thereto.

Coolant can flow through the outer grooves (311, 321). Coolant can be delivered to the outer grooves (311, 321) of each fuel cell cell (1) through some of the plurality of manifolds (M in FIG. 4) that the fuel cell stack (100) can include, and as the coolant flows along the outer grooves (311, 321), cooling of the separator plates (31, 32) can be achieved, and heat generated from the power generation unit (G) can be cooled via the separator plates (31, 32).

The outer grooves (311, 321) can define a coolant passage (41) through which coolant can flow. The coolant passage (41) can be defined by the inner surface of the outer groove (311, 321) formed in a separator (31, 32) and the outer surface of an adjacent separator (31a, 32a). The outer grooves (311, 321) of the separator plates (31, 32) can be arranged to face each other and the outer grooves (311a, 321a) included in the separator plates (31a, 32a) of other adjacent fuel cell cells. That is, the outer grooves (311 and 321a or 321 and 311a) of adjacent separators (31 and 32a or 32 and 31a) meet with their open surfaces facing each other to form a coolant passage (41) defined by the inner surfaces of the outer grooves (311 and 321a or 321 and 311a). Coolant flows along the coolant passage (41) and exchanges heat with the separators (31, 32) to cool the fuel cell (1).

Adhesive (B)

An adhesive (B) may be applied to the outer grooves (311, 311a, 321, 321a) forming the coolant passage (41). The adhesive (B) may be applied between adjacent fuel cell cells (1) to bond adjacent separators (31 and 32a or 32 and 31a). At this time, the adhesive is placed in a non-contact area (V) rather than a contact area (T) where adjacent separators (31 and 32a or 32 and 31a) are in contact, so that reversible bonding of the outer surfaces of the respective fuel cell cells spaced apart from each other can be achieved.

An adhesive (B) may be placed so as to fill the coolant passage (41). In Fig. 3, the adhesive (B) is shown to be placed only in the coolant passage (41) located at the center of the drawing, but this is for convenience of explanation, and the adhesive (B) may be placed in other coolant passages (41), and an adhesive (B) having a volume smaller than or equal to the volume of the coolant passage (41) may be placed so as to fill the coolant passage (41).

The adhesive (B) may be designed to disappear under certain conditions. Accordingly, in the step of forming a fuel cell stack (100) by stacking fuel cell cells (1), the adhesive (B) is used to help each fuel cell cell (1) to be evenly aligned, but later, when the fuel cell stack (100) is activated or power is generated using the fuel cell stack (100), the adhesive (B) may disappear. Even if the adhesive (B) disappears, the fuel cell stack (100) can pressurize the stacked fuel cell cells (1) toward each other at high pressure and fix them with a support plate or the like, so that the alignment of each fuel cell cell (1) may not be disturbed.

The adhesive (B) may be composed of a water-soluble material. Therefore, when the coolant flows along the coolant passage (41), the adhesive (B) can be removed.

The melting point of the adhesive (B), which is the temperature at which it dissolves, may be below a predetermined temperature. Specifically, this predetermined temperature may be 70°C. Furthermore, the vitrification temperature of the adhesive (B) may be below a predetermined temperature. Due to this characteristic, the adhesive (B) can be removed when the fuel cell (1) operates and generates heat.

The adhesive (B) may include at least one of a starch adhesive, a glue adhesive, and a thermoplastic hot melt adhesive comprising starch.

The amount of adhesive (B) applied to the outlet of the coolant channel (41) may be greater than the amount of adhesive (B) applied to the inlet of the coolant channel (41). Based on the flow direction (D2), the upstream side of the coolant channel (41) may be the inlet, and the downstream side may be the outlet. Since the temperature of the coolant rises as it passes through the reaction surface, the outlet of the coolant channel (41) generally has a higher temperature than the inlet of the coolant channel (41). Therefore, by applying a greater amount of adhesive (B) to the area adjacent to the outlet of the coolant channel (41) than the amount of adhesive (B) applied to the area adjacent to the inlet of the coolant channel (41), the fixing force may be maintained at a predetermined level or higher, while allowing complete removal of the adhesive (B) when the fuel cell stack (100) is activated.

FIG. 4 is a drawing showing a cross-section of a fuel cell stack (100) according to one embodiment of the present invention.

The adhesive can be applied by forming multiple points at the inlet and outlet of the cooling water passage (41). A tapered diffusion portion (50) for diffusion or convergence of the cooling water can be formed adjacent to the inlet and outlet of the cooling water passage (41) connected to the manifold (M), and the adhesive can be applied in a viscosity manner to this diffusion portion (50).

Based on the above-described contents, a method for forming a fuel cell stack (100) is described. A power generation unit (G) can be prepared. The power generation unit (G) can be formed by bonding an electrode membrane assembly (10) and a gas diffusion layer (20). A fuel cell cell (1) can be formed by contacting two separators (31, 32) on each side of the power generation unit (G), and a plurality of such fuel cell cells (1) can be formed.

An adhesive (B) that is designed to disappear under a predetermined condition can be applied to the outer grooves (311, 321) formed by digging inward on the outer surface of the separator plates (31, 32) arranged at the outermost side of the fuel cell cell (1). A plurality of fuel cell cells (1) can be laminated and bonded by having the outer surfaces of the separator plates (31 and 32a or 32 and 31a) contact each other. A fuel cell stack (100) can be formed by bringing two supports into contact with each other on both sides of the stacked plurality of fuel cell cells (1) and pressurizing them inward using a fastening bar or the like connecting the supports. A fuel cell can be formed by putting this fuel cell stack (100) into a housing.

In this way, the fuel cell stack (100) can be formed and the adhesive (B) can be removed by going through an activation step or operating it. Even after the adhesive (B) is removed, the fuel cell cells (1) can remain in contact and bonded to each other.

If it is determined that there is a problem with the operation of the fuel cell stack (100), the configuration between the gas diffusion layers (20) arranged at the outermost side of Fig. 1 may be considered as a repair unit (U0), in which the gas diffusion layer (20) where the reaction occurs and the electrode membrane assembly (10) are separated and replaced. In this case, in order to replace the problematic part, the entire repair unit (U0) including the problematic part is replaced.

In addition, in such a case, the separators (31 and 32a or 32 and 31a) can be strongly and irreversibly bonded to each other by a method such as spot welding to form a separator assembly, and there is no such strong bond between the gas diffusion layer (20) and the electrode film assembly (10), so that the reaction surfaces, which are the facing surfaces of the gas diffusion layer (20) and the electrode film assembly (10), can become the boundary of one repair unit (U0). When the repair unit (U0) is replaced, the reaction surface is exposed, which may cause additional defects in other adjacent repair units.

According to one embodiment of the present invention, the repair unit (U1) extends from the first separator (31) to the second separator (32), thereby reducing its range. Accordingly, the number of components, such as the separator (31, 32), gas diffusion layer (20), and electrode membrane assembly (10) included in the repair unit (U1) to be replaced is reduced, thereby enabling cost reduction in the production process of the fuel cell stack (100).

In addition, according to one embodiment of the present invention, when replacing the repair unit (U1), the cooling surface, which is the outer surface of the separator (31, 32) where the cooling water passage (41) is formed, rather than the reaction surface, is exposed, thereby reducing the occurrence of additional defects.

Although all components constituting the embodiments of the present invention have been described above as being combined or operating in combination, the present invention is not necessarily limited to these embodiments. That is, within the scope of the purpose of the present invention, all components may be selectively combined and operated one or more times. In addition, terms such as "include," "comprise," or "have" described above, unless specifically stated to the contrary, mean that the corresponding component may be inherent, and therefore should be interpreted as including other components rather than excluding other components. All terms, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the art to which the present invention pertains, unless otherwise defined. Commonly used terms, such as terms defined in a dictionary, should be interpreted as being consistent with the contextual meaning of the related technology, and shall not be interpreted in an ideal or overly formal sense, unless explicitly defined in the present invention.

The above description is merely an illustrative illustration of the technical idea of the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the technical idea of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

1: Fuel cell cell
10: Electrode membrane assembly
20: Gas diffusion layer
31, 31a: First separator plate
32, 32a: Second separator
41: Coolant flow path
42, 43: Gas Euro
50: Diffusion section
100: Fuel cell stack
311, 311a, 321, 321a: Outer groove
312, 322: Inner groove
B: Adhesive
D1: Stacking direction
D2: Flow direction
G: Power generation unit
M: Manifold
T: Contact area
U0, U1: Repair units
V: Non-contact area

Claims (11)

A plurality of fuel cell cells that are stacked to generate electricity by receiving gas and air; and
An adhesive is applied between adjacent fuel cell cells among the plurality of fuel cell cells to combine the adjacent fuel cell cells, and is provided so as to disappear under a predetermined condition.
The above fuel cell cell:
A power generation unit that generates electricity by receiving the above gas and the above air;
A separator plate is coupled to both sides of the power generation unit, and has an outer groove concavely formed on a surface that does not come into contact with the power generation unit so that cooling water can flow.
The adhesive is applied to the outer grooves of the adjacent fuel cell cells to bond the adjacent separators to each other,
A fuel cell stack, wherein the outer groove of the separator is arranged to face the outer groove of the separator in an adjacent fuel cell. In the first paragraph,
The above adhesive is water-soluble, fuel cell stack. In the first paragraph,
A fuel cell stack having a melting point, which is the temperature at which the adhesive dissolves, of 70°C or less. In the first paragraph,
A fuel cell stack, wherein the adhesive comprises at least one of a starch adhesive, a glue adhesive, and a thermoplastic hot melt adhesive. delete In the first paragraph,
The above outer groove is a fuel cell stack having a rectangular cross-section. In the first paragraph,
A fuel cell stack, wherein the inner surface of the separator facing the power generation unit has an inner groove extending outward, thereby defining a gas path through which the gas or air can flow together with the outer surface of the power generation unit. In the first paragraph,
A fuel cell stack, wherein the amount of the adhesive applied to an area adjacent to the outlet of the coolant channel is greater than the amount of the adhesive applied to an area adjacent to the inlet of the coolant channel. In the first paragraph,
A fuel cell stack, wherein the adhesive is applied to form a plurality of points in a diffusion portion adjacent to the inlet and outlet of the coolant passage. In a fuel cell cell in which a plurality of cells are stacked and combined to form a fuel cell stack,
A power generation unit that generates electricity by receiving gas and air; and
A separator plate is formed on both sides of the power generation unit and has an outer groove formed inwardly on the outer surface to define a cooling water path through which cooling water can flow.
The above separator is in contact with another adjacent separator and is joined to the other adjacent separator by an adhesive applied to the inner surface of the outer groove and designed to disappear under a predetermined condition.
A fuel cell cell, wherein the outer groove of the separator is arranged to face the outer groove of the separator in another adjacent fuel cell. delete