KR20240025968A - Endplate assembly for fuel cell stack - Google Patents

Abstract

The present invention relates to an end plate assembly for a fuel cell stack, which includes a current collector plate, an insulating plate, and an end plate, wherein the insulating plate is formed with a first receiving groove of a shape corresponding to the current collector plate, and a central portion that accommodates the current collector plate on one side. , and both ends protruding from the other surface where the end plate is located and forming a manifold through which the working fluid moves, and the end plate is formed with a second receiving groove having a shape corresponding to the manifold of the insulating plate to accommodate the manifold. The end plate assembly for a fuel cell stack according to the present invention has excellent corrosion resistance and improves fuel cell performance by uniformly distributing fastening pressure during fastening.

Description

End plate assembly for fuel cell stack {ENDPLATE ASSEMBLY FOR FUEL CELL STACK}

The present invention relates to an end plate assembly used to integrally fasten and secure a fuel cell stack. More specifically, it has excellent corrosion resistance against working fluid and improves fuel cell performance degradation by evenly distributing fastening pressure. It relates to an end plate assembly.

A fuel cell is a battery that converts chemical energy generated by the oxidation/reduction reaction of working fluid, that is, hydrogen and oxygen, into electrical energy. Generally, an anode and a cathode are arranged with an electrolyte in between, and a gas diffusion layer is placed on each of the anode and cathode. (GDL), separators are sequentially stacked to form a unit cell. At the cathode, hydrogen is ionized and separated into hydrogen ions and electrons, and the hydrogen ions move to the anode through the electrolyte. Electrons move to the anode through the circuit, and a reduction reaction occurs where hydrogen ion electrons and oxygen react to produce water at the anode.

Because the unit cells of fuel cells have low voltage and low compatibility, a fuel cell stack consisting of dozens to hundreds of unit cells is used, and the outermost area on both sides of the fuel cell stack is a housing for outputting current to the outside. An end plate that fastens and supports the front plate and fuel cell stack is disposed, respectively.

The end plate used synthetic resin in the past, but lightweight metal is used to increase rigidity, and an insulating plate is inserted between the current collector and the metal end plate for insulation. Meanwhile, the end plate serves (1) to support the fuel cell stack and (2) to serve as a flow path that brings in working fluid from the outside and delivers it to the power generation unit of the fuel cell stack. As the end plate uses metal, working fluids such as hydrogen, air, and coolant flow, causing corrosion during long-term operation, which reduces the performance of the fuel cell.

To solve this problem, Republic of Korea Patent Publication No. 10-2013-0104490 inserts a corrosion-prevention reinforcement material made of synthetic resin into the manifold position corresponding to the flow path of the end plate to block contact between the end plate and the working fluid and prevent corrosion. prevent.

Republic of Korea Patent Publication No. 10-2013-0104490 can sufficiently prevent corrosion of the end plate, but as accessories such as anti-corrosion reinforcement materials are inserted into both ends of the end plate, the shape of the end plate has no choice but to become longer in the longitudinal direction. In addition, the fuel cell is equipped with an SVM (Stack Voltage Monitor) as an accessory that measures the voltage of the unit cells that make up the fuel cell stack. SVM detects the voltage of a unit cell to identify problem unit cells with degraded performance and enable replacement. In order for the SVM to detect voltage and transmit the detected signal to the outside, the SVM is located at both longitudinal ends of the fuel cell stack, that is, at both longitudinal ends of the end plate. As the number of fuel cell accessories increases, the shape of the end plate tends to become longer in the longitudinal direction.

When the end plate is elongated in the longitudinal direction, the fastening pressure at each location is uneven when fastening the fuel cell stack and the end plate, which affects the power generation performance of the fuel cell. Figure 1 is a schematic diagram of a fuel cell stack and an end plate being fastened. The fastening members 3 are arranged at regular intervals along the edges of the two end plates 2 due to the fuel cell stack 1 located inside them. Therefore, when the fastening pressure from the fastening member 3 is applied to the fuel cell stack 1 through the end plate 2, the fastening pressure at the edge of the fuel cell stack 1 is higher than the center position and the resistance is relatively low. Therefore, the power generation performance is high. Conversely, the central location of the fuel cell stack has lower clamping pressure and higher resistance than the edges, resulting in lower power generation performance.

As the end plate becomes longer in the longitudinal direction, the imbalance of fastening pressure between the center and edges of the fuel cell stack inevitably increases, ultimately impeding the lifespan of the fuel cell and uniform power generation performance. Therefore, there is an urgent need to develop a structure that can improve corrosion resistance and apply uniform fastening pressure to an end plate that is elongated in the longitudinal direction.

Republic of Korea Patent Publication No. 10-2013-0104490, end plate for fuel cell stack with excellent corrosion resistance

As a result of studying the structure of the clamping pressure of an end plate extending in the longitudinal direction through various simulations, the present inventors developed an end plate assembly that can minimize clamping pressure unevenness. It was found that the end plate assembly of the present invention can minimize unevenness of fastening pressure through a structure in which an insulating plate is integrated by accommodating a current collector on one side, and a manifold protruding from the other side of the insulating plate is inserted into the end plate.

Accordingly, the purpose of the present invention is to provide an end plate assembly that improves the power generation performance of a fuel cell by improving corrosion resistance and minimizing uneven clamping pressure.

In order to achieve the above object, a metal separator plate for a fuel cell according to an embodiment of the present invention includes a current collector plate, an insulating plate, and an end plate, and the insulating plate is formed with a first receiving groove having a shape corresponding to the current collector plate. It includes a central part that accommodates the current collector plate on one side and protruding from the other side where the end plate is located, but both ends are formed with a manifold through which the working fluid moves, and the end plate has a second receiving groove of a shape corresponding to the manifold of the insulating plate. is formed to receive the manifold.

The insulating plate has a third receiving groove formed to accommodate the SVM, and the third receiving groove may be formed in at least one of both ends of the insulating plate. The current collector plate may include an electrode tab that outputs the collected electricity to the outside, and the insulating plate may have an opening formed so that the electrode tab can protrude from the insulating plate while the current collector plate is accommodated in the first receiving groove of the insulating plate. there is.

The end of the current collector plate may have a protruding shape so as to be accommodated in the insulating plate and press at least a portion of the facing surface. Additionally, the manifold of the insulating plate may have a protruding shape so as to be accommodated in the end plate and press at least a portion of the facing surface.

The insulating plate has a rectangular shape with different horizontal and vertical lengths when viewed from above, and the ratio of the long horizontal length to the relatively short vertical length can be 2 to 3.5:1. .

The insulating plate and the end plate have fastening grooves formed at the same opposing positions so that the fastening member can penetrate, and the fastening grooves may be formed both in the center and both ends of the insulating plate. At least two may be formed at the corners of both ends of the insulating plate.

Since the end plate assembly according to the present invention has a structure in which the current collector plate, the insulating plate, and the end plate can be integrated into one piece, the fastening pressure can be evenly distributed when fastening the fuel cell stack. In addition, manifolds are provided at both ends of the insulating plate to prevent the metal end plate from coming into contact with the working fluid, thus improving corrosion resistance. The end plate assembly according to the present invention can be designed with sufficient space so that accessories such as SVMs and manifolds can be mounted on the fuel cell, and even if it has a shape that increases in length in one longitudinal direction, the fastening pressure is evenly distributed to fuel the fuel cell. Battery performance can be improved.

Figure 1 is a schematic diagram of a fuel cell stack and an end plate of the prior art being fastened.
Figure 2 is an exploded perspective view of an end plate assembly according to an embodiment of the present invention.
Figure 3 is an enlarged view of the insulating plate of Figure 2.
FIG. 4 is a diagram showing the combined state of the current collector plate, insulating plate, and end plate shown in FIG. 2.
FIG. 5 is a view showing the opposite side of the end plate assembly shown in FIG. 4.
FIG. 6 is an enlarged view of portion T of FIG. 2.
FIG. 7 is a cross-sectional view of the manifold shown in FIG. 3 taken along line A-A'.
FIG. 8 is an exploded perspective view of a fuel cell stack equipped with the end plate assembly shown in FIG. 2.
FIG. 9 is a diagram showing a state in which the fuel cell stack shown in FIG. 8 is fastened by a fastening member.
FIG. 10 is a diagram showing the fuel cell stack of FIG. 9 covered with a case.

Hereinafter, the features of the present invention will be specified through drawings and explained by examples. However, the illustrated embodiments, structures, and shapes can be implemented in other embodiments without departing from the spirit and scope of the present invention, and are therefore considered to cover the elements of the claims and equivalent scope. It must be taken in.

<End plate assembly for fuel cell stack>

Figure 2 is an exploded perspective view of an end plate assembly according to an embodiment of the present invention. Referring to Figure 2, the end plate assembly 100 of the present invention includes a current collector plate 110, an insulating plate 120, and an end plate 130.

Two end plate assemblies 100 are disposed at the top and bottom with the fuel cell stack including the power generation unit in between, and have an integrated structure by pressing the fuel cell stack with a fastening member. A fuel cell stack generally consists of a separator, a membrane electrode assembly (MEA), a gas diffusion layer (GDL), and a gasket, but is not limited to this and includes a combination of commercially available fuel cell unit cells.

The current collector 110 outputs electricity collected from the fuel cell stack to the outside. The material of the current collector 110 can be any metal or alloy with excellent electrical conductivity. For example, the current collector plate may be made of copper, aluminum, silver, gold, and an alloy of two or more thereof, and preferably a copper-aluminum alloy can be used to obtain a high current collection effect. Additionally, the current collector plate may be gold plated to improve electrical conductivity. For example, the base material of the current collector is a copper-aluminum alloy, and the alloy surface can be gold-plated. The current collector 110 may include an electrode tab 111 to output the collected electricity to the outside. The electrode tab 111 may be made of the same material as the current collector plate 110 and may have a structure that protrudes from the current collector plate 110 . The electrode tab 111 may be formed with a connection portion 112 so that it can be electrically connected to an external terminal. The external terminal (not shown) may be screwed to the connection portion 112 to secure the electrical connection and position.

The insulating plate 120 is disposed between the current collector plate 110 and the end plate 130 to insulate it. The end plate 130 of the present invention uses a metal with excellent rigidity, and an insulating plate 120 is used to insulate the current collector plate 110 and the metal end plate. Specifically, FIG. 3 is an enlarged view of the insulating plate of FIG. 2. Referring to FIGS. 2 and 3 , the insulating plate 120 includes a center 121, both ends 122, and a manifold 123. The material of the insulating plate 120 can be an insulating synthetic resin, preferably polyether-ether-ketone (PEEK), which not only has an insulating effect but also allows the fastening pressure to be distributed more evenly during fastening. In particular, the center 121 and both ends 122 of the insulating plate 120 are integrally connected to distribute the fastening pressure more evenly.

The center 121 has a first receiving groove 124 formed on one side to accommodate the current collector plate 110. The first receiving groove 124 may have a shape corresponding to the shape of the current collecting plate so that the current collecting plate 110 can be accommodated. For example, FIG. 4 is a view showing a combined state of the current collector plate, insulating plate, and end plate shown in FIG. 2, and FIG. 5 is a view showing the opposite side of the end plate assembly shown in FIG. 4.

The current collector plate 110 may be inserted into the insulating plate 120 to fix its position and be integrated with each other. As an example in which the current collector plate 110 is inserted into the insulating plate 120, FIG. 6 is an enlarged view of portion T of FIG. 2. The end of the current collector plate 110 may be accommodated in the first receiving groove 124 of the insulating plate 120 and may have a protruding shape so as to press at least a portion of the surfaces facing each other. For example, the current collector 110 has an upper surface 110B and a lower surface 110A of the same length, and may include an extension portion 110C extending from the upper surface such that the upper surface 110B is longer than the lower surface 110A. . As another example, the extension may be formed so that the lower surface (110A) is longer than the upper surface (110B). As illustrated, when the current collector plate 110 is inserted into and integrated with the insulating plate 120, the performance of the fuel cell can be improved by uniformly distributing the fastening pressure when fastening the fuel cell stack.

When the electrode tab 111 is formed on the current collector plate 110, the insulating plate 120 can accommodate at least a portion of the electrode tab 111 of the current collector plate 110. For example, referring to FIGS. 2 and 3, an opening H that can accommodate a portion of the electrode tab 111 may be formed in the center of the insulating plate 120. The electrode tab 111 may protrude out of the insulating plate 120 through the opening H, and the insulating plate 120 may prevent the electrode tab 111 from being deformed, such as being bent due to an external impact. Additionally, the previously described method of fitting the current collector plate 110 and the insulating plate 120 can be applied to the electrode tab 111 and the opening H of the insulating plate in the same manner.

Manifolds 123 are formed at both ends 122 of the insulating plate 120. The manifold 123 can be made of the same material as the insulating plate 120 described above, and hydrogen, oxygen, and water flow through the manifold. The diameter of each hole in the manifold 123 through which each fluid can flow can be designed in various ways to control hydraulic pressure, and the position of each hole can also be changed to be arranged downward or upward when looking at the manifold from the top. For example, as shown in FIG. 3, the degree of water discharge can be adjusted by implementing the manifold 123 in a gently curved shape rather than a straight line and arranging the hole in the middle upward or downward differently from the positions of the remaining two holes. The manifold 123 improves corrosion resistance by blocking the end plate 130 made of metal from contacting the working fluid. The manifold 123 may protrude in a direction perpendicular to the longitudinal direction of the insulating plate 120, and protrude on the other side opposite to one side of the insulating plate on which the first receiving groove 124 is formed.

When fastening a fuel cell stack, in order to uniformly distribute the fastening pressure, the manifold 123 must be inserted into the end plate 130 and its position must be fixed. A second receiving groove 131 having a shape corresponding to the outer surface of the manifold 123 of the insulating plate may be formed in the end plate 130. As an example in which the manifold 123 is inserted into the second receiving groove 131 of the end plate and its position is fixed, FIG. 7 is a cross-sectional view of the manifold shown in FIG. 3 taken along line A-A'. Referring to FIGS. 5 and 7 , the protruding thickness of the manifold 123 may have a thickness (W) thicker at the bottom than at the top. In this case, the manifold 123 of the insulating plate is accommodated in the end plate 130 and is coupled and fixed in position while pressing the surfaces facing each other. Meanwhile, in order to reinforce the combination of the manifold 123 and the end plate 130, sub-fixing holes (X) are formed in the insulating plate 120 and the end plate 130, respectively, as shown in FIG. It can be combined and fixed using bolts, etc. The sub-fixing hole

The insulating plate 120 may include a third receiving groove 125 that accommodates the SVM 140. SVM (Stack Voltage Monitor) refers to a device that is electrically connected to the unit cells that make up the fuel cell stack and measures the voltage of the unit cells. It identifies and replaces problem unit cells with deteriorated performance. The third receiving groove 125 formed in the insulating plate 120 is a groove formed so that the length of the insulating plate 120 and the end plate 130 is not as long as possible even if the SVM is mounted, and the SVM does not protrude to the outside, thereby preventing the external It protects against impact and minimizes uneven tightening pressure during tightening. The third receiving groove 125 may be formed at both ends of the insulating plate due to the internal structure of the fuel cell stack, and when the electrode tab is formed on the current collector plate, the external protrusion direction of the electrode tab and the formation position of the third receiving groove are arranged perpendicularly. It is desirable.

Except for the thickness, the overall size and shape of the insulating plate 120 and the end plate 130 are preferably the same as shown in FIGS. 4 and 5, which improves the corrosion resistance of the end plate 130 and improves corrosion resistance. This is because the fastening pressure applied to the end plate 130 can be evenly distributed throughout the fuel cell stack through the insulating plate 120. When looking at the top from the top of FIG. 4, the insulating plate 120 and the end plate 130 may have a rectangular shape with different horizontal and vertical lengths, and in this case, the length is relative to the long horizontal length. It is desirable to have a short length ratio of 2 to 3.5:1. If the width:length ratio exceeds 3.5:1, uneven fastening pressure may occur when fastening the fuel cell stack, despite the structural characteristics of the end plate assembly of the present invention. On the other hand, if the width:length ratio is less than 2:1, it becomes difficult to allocate space to mount accessories such as a manifold or SVM on the insulating plate.

A fastening groove L may be formed in the insulating plate 120 and the end plate 130 at the same position facing each other so that the fastening member can penetrate when fastening the fuel cell stack. The fastening grooves L are formed at both the center and both ends of the insulating plate 120, and are preferably formed at regular intervals to evenly distribute the fastening pressure. In addition, it is preferable that at least two fastening grooves (L) are formed at the corners of both ends of the insulating plate and the end plate.

Additionally, an alignment groove (Y) may be formed in the insulating plate and the end plate at the same location to enable precise alignment in the stacked state (see Figure 3).

Hereinafter, the form in which the fuel cell stack is fastened using the end plate assembly of the present invention described above will be described by way of example.

FIG. 8 is an exploded perspective view of a fuel cell stack equipped with the end plate assembly shown in FIG. 2, FIG. 9 is a view showing the fuel cell stack shown in FIG. 8 fastened by a fastening member, and FIG. 10 is a view showing the fuel cell stack shown in FIG. This is a drawing showing the case covered with the fuel cell stack in Figure 9.

Referring to FIGS. 8 to 10, a fuel cell stack including a power generation unit is disposed between the end plate assemblies 100 and 200 of the present invention. That is, the fuel cell stack is disposed between the current collector plates 110 and 210. The end plate assemblies 100 and 200 may be used by arranging the same shape at the top and bottom, or may be changed differently by a person skilled in the art depending on the needs of structural design. For example, as shown in FIG. 8, the lower end plate assembly 200, unlike the upper end plate assembly 100, may be used without a manifold at both ends of the insulating plate 220. In this case, the working fluid flowing into one manifold of the upper end plate assembly 100 passes through the flow path of the fuel cell stack and flows out to the other manifold of the end plate assembly 100.

A fastening groove (L) is formed in the insulating plates 120, 220 and the end plates 130, 230 of the upper end plate assembly 100 and the lower end plate assembly 200, respectively, so that the fastening member 500 can penetrate. You can. Here, the fastening member 500 includes bolts, nuts, screw couplings, etc.

Additionally, as shown in FIGS. 9 and 10, case 400 may be used to protect the fuel cell stack. Case 400 may be coupled to both ends of the end plate assembly through screw coupling or the like. When the end plate assembly of the present invention has an electrode tab protruding from the current collector, at least one through hole B may be formed to protrude through the case 400. Additionally, when the SVM is mounted on the end plate assembly of the present invention, an opening may be formed in the case 400 so that the SVM can be viewed from the outside.

As such, the end plate assembly according to the present invention has a structure in which the current collector plate, the insulating plate, and the end plate can be integrated into one body, and the fastening pressure can be evenly distributed when fastening the fuel cell stack. In addition, manifolds are provided at both ends of the insulating plate to prevent the metal end plate from coming into contact with the working fluid, thus improving corrosion resistance. The end plate assembly according to the present invention can be designed with sufficient space so that accessories such as SVMs and manifolds can be mounted on the fuel cell, and even if it has a shape that increases in length in one longitudinal direction, the fastening pressure is evenly distributed to fuel the fuel cell. Battery performance can be improved.

100: End plate assembly for fuel cell stack
110: current collector 110A: bottom
110B: Top 110C: Extension
111: electrode tab 112: connection part
120: insulation plate
121: Center 122: Both ends
123: Manifold 124: First receiving groove
125: Third receiving groove
130: End plate
131: Second receiving groove
400: case
500: fastening member

Claims (8)

An end plate assembly for a fuel cell stack including a current collector plate, an insulating plate, and an end plate,
The insulating plate includes a central portion in which a first receiving groove having a shape corresponding to that of the current collecting plate is formed to accommodate the current collecting plate on one surface; and both ends protruding from the other surface where the end plate is located and formed with a manifold through which the working fluid moves,
The end plate assembly for a fuel cell stack is formed with a second receiving groove having a shape corresponding to the manifold of the insulating plate to accommodate the manifold. According to paragraph 1,
The insulating plate is formed with a third receiving groove to accommodate the SVM,
An end plate assembly for a fuel cell stack, wherein the third receiving groove is formed on at least one of both ends of the insulating plate. According to paragraph 1,
The current collector plate includes an electrode tab that outputs the collected electricity to the outside,
An end plate assembly for a fuel cell stack, wherein the insulating plate has an opening formed so that the electrode tab can protrude from the insulating plate while the current collector plate is accommodated in the first receiving groove of the insulating plate. According to paragraph 1,
An end plate assembly for a fuel cell stack, characterized in that the end of the current collector is accommodated in the insulating plate and has a protruding shape so as to press at least a portion of the facing surface. According to paragraph 1,
An end plate assembly for a fuel cell stack, wherein the manifold of the insulating plate is accommodated in the end plate and has a protruding shape to press at least a portion of the facing surface. According to paragraph 1,
The insulating plate has a rectangular shape with different horizontal and vertical lengths when viewed from above, and has a ratio of the long horizontal length to the relatively short vertical length of 2 to 3.5:1. Features an end plate assembly for a fuel cell stack. According to clause 6,
An end plate assembly for a fuel cell stack, wherein the insulating plate and the end plate have fastening grooves formed at the same opposing positions so that the fastening member can penetrate, and the fastening grooves are formed at both the center and both ends of the insulating plate. In clause 7,
An end plate assembly for a fuel cell stack, characterized in that at least two fastening grooves are formed at corners of both ends of the insulating plate.

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