Fuel cell separator plate

Abstract

The present invention provides a fuel cell separation plate that increases the land area of ​​unreacted channels that encroach upon the reaction region, thereby preventing the generation of water in the unreacted channel. [Solution] A fuel cell separation plate comprising a first separation plate containing a straight channel flow path and a second separation plate 20 containing a corrugated channel flow path, which are repeatedly stacked, wherein the reaction region B formed in the first separation plate and the second separation plate respectively includes a land expansion portion 100 formed in the folded region C of the land portion 2a adjacent to the unreacted flow path 2 located at the uppermost end of the second separation plate.

Description

Technical Field

[0001] The present invention relates to a separator for a fuel cell, and more particularly to a separator for a fuel cell that can increase the land of an unreacted flow path that invades a reaction region and prevent the generation of generated water in an unreacted channel flow path.

Background Art

[0002] Generally, a fuel cell is a device that directly converts the chemical energy of a fuel into electrical energy electrochemically in a battery without converting it into heat by combustion, and is a pollution-free power generation device that has been attracting attention and studied as a power source for automobiles, a power source for laser electrical appliances, etc.

[0003] When hydrogen, which is a fuel gas, is supplied to the anode of such a fuel cell and oxygen, which is an oxidant, is supplied to the cathode, a humidifying device for supplying moisture to hydrogen and oxygen is attached to the anode and cathode of the fuel cell, respectively, in order to separate electrons from this hydrogen and oxygen and promote ionization.

[0004] Fuel cells are classified into solid oxide fuel cells (SOFCs), molten carbonate fuel cells (MCFCs), polymer electrolyte membrane fuel cells (PEMFCs), and direct methanol fuel cells (DMFCs) according to the operating temperature and the type of electrolyte.

[0005] In a fuel cell, the electrochemical reaction consists of two reactions: an oxidation reaction at the oxidizing electrode (anode) and a reduction reaction at the reducing electrode (cathode). Both electrodes form a catalyst layer using platinum or platinum and ruthenium metal to promote oxidation and reduction. Fine carbon particles are used as a catalyst support to reduce the amount of platinum catalyst used while increasing its utilization rate. The final byproducts of the reaction are electricity, heat, and water. The water produced at the reducing electrode is in the form of water and water vapor, but is generally removed by strongly flowing a reducing gas (oxygen or air) towards the reducing electrode.

[0006] The basic unit cell of a stack consists of two electrodes, an oxidizing electrode and a reducing electrode, separated by a polymer electrolyte membrane. The oxidizing and reducing electrodes on the outer surface of this polymer electrolyte membrane are hot-pressed to form a membrane-electrode assembly (MEA). This membrane-electrode assembly is supported by a separation plate with a channel through which hydrogen (or methanol in the case of a direct methanol fuel cell) and oxygen or air (a reducing gas) are supplied, and water produced by the oxidation-reduction reaction is discharged. A gasket is provided to prevent leakage of gas or liquid supplied or discharged through the channel of the separation plate. Unit cells composed of such membrane-electrode assemblies, separation plates, and gaskets are stacked in series to obtain the required output, and the stack is formed by fixing them at both ends with end plates.

[0007] The separation plate prevents the fuel (hydrogen, methanol) and reducing gas (oxygen, air) from mixing within the battery, electrically connects the two electrodes, and also functions as a mechanical support for the stacked unit battery. It ensures that the fuel gas (hydrogen, methanol) and reducing gas (oxygen, air) flow uniformly to the electrodes through channels formed on its surface, and prevents the membrane from drying out through proper moisture management. When operating a polymer electrolyte fuel cell, it is important to supply sufficiently humidified fuel and reducing gas (oxygen, air).

[0008] Under high-current operating conditions that exceed the critical current density, an excess amount of water is present at the reducing electrode, including water generated by electrochemical reactions and water moved from the oxidizing electrode by electroosmosis. Some of this excess water evaporates as reducing gas (oxygen or air) flowing through the separation plate channel, saturating the reducing gas, while the unevaporated water remains in liquid form in the gas diffusion layer (GDL) or the separation plate channel.

[0009] Excess water present in the gas diffusion layer or separation plate channel, if not discharged to the outside by appropriate engineering equipment, can induce flooding, leading to critical problems in terms of fuel cell performance and reliability. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Korean Registered Patent Publication No. 10-0766154 [Overview of the project] [Problems that the invention aims to solve]

[0011] The object of the present invention is to provide a fuel cell separation plate in which linear channels and corrugated channels are repeatedly stacked, and by increasing the land area of ​​the unreacted flow path of the corrugated channel that encroaches on a set reaction region, thereby preventing the generation of generated water in the unreacted flow path, water discharge performance can be improved in the low temperature / low current section where water discharge performance is weakened, and the performance of the stack can be effectively improved. [Means for solving the problem]

[0012] The fuel cell separator according to the present invention is a fuel cell separator comprising a first separator containing a straight channel flow path and a second separator containing a corrugated channel flow path, which are repeatedly stacked, and is characterized in that, in the reaction regions formed in the first separator and the second separator, respectively, a land expansion portion is formed in the folded region of the land portion adjacent to the unreacted flow path located at the uppermost end of the second separator.

[0013] Such land extensions are formed so that the folded region is extended toward the uppermost end of the second separation plate and coincides with the boundary position for forming the reaction region.

[0014] Here, the land extension portion is formed in the bending region along the flow direction of the reactive gas, extended such that the length on one side is the same as the length on the other side, and extended such that the length on the central side is longer than both sides.

[0015] Furthermore, the land extension portion is formed such that the folded region extends in a direction toward the uppermost end of the second separation plate and exceeds the boundary position for forming the reaction region.

[0016] Furthermore, the land extension portion is extended so as to face the land portion of the unreacted channel located at the uppermost end of the first separation plate.

[0017] Furthermore, the land extension portion is formed in the bending region along the flow direction of the reactive gas, extended so that the length on one side is the same as the length on the other side, and extended so that the length on the central side is longer than both sides.

[0018] Furthermore, the land expansion portion is formed to be connected to the reverse forming portion, which is formed by folding in the opposite direction to the gas diffusion layer in the folding region.

[0019] Such land extensions are formed on one side and the other side of the bending region and are connected to the inverse forming portion, respectively.

[0020] Here, the land extension portion forms a circulation flow path for the reaction gas in the unreacted flow path by being connected to the reverse forming portion.

[0021] On the other hand, the first separation plate is formed such that oxygen flows along the linear channel flow path, the second separation plate is laminated to face the first separation plate so that the reaction regions coincide with each other, and is formed such that hydrogen flows along the corrugated channel flow path.

Advantages of the Invention

[0022] In the separation plate structure in which the linear channel and the corrugated channel are repeatedly laminated, the present invention increases the land of the unreacted flow path of the corrugated channel that invades the set reaction region, and prevents the generation of generated water in the unreacted flow path, thereby improving the water discharge property in the low temperature / low current section where the water discharge property is weakened, and having the effect of improving the performance of the stack.

[0023] Thereby, the present invention can prevent deterioration due to the stagnation of generated water in the unreacted flow path, and thus has the effect of improving the durability of the stack.

[0024] And the present invention has the effect of improving the durability deterioration of the stack due to the freezing of the generated water accumulated in the unreacted flow path under sub-zero conditions.

Brief Description of the Drawings

[0025] [Figure 1A] It is a diagram showing a conventional separator for a fuel cell. [Figure 1B] It is a diagram showing a conventional separator for a fuel cell. [Figure 1C] It is a diagram showing a conventional separator for a fuel cell. [Figure 2] It is a diagram showing a first embodiment of the land extension portion of the separator for a fuel cell according to an embodiment of the present invention. [Figure 3]Figure 2, section AA shows a first embodiment of the land expansion portion of a fuel cell separation plate according to an embodiment of the present invention. [Figure 4] This figure shows a second embodiment of the land expansion portion of a fuel cell separation plate according to an embodiment of the present invention. [Figure 5] Figure 4, part AA, is a cross-sectional view showing a second embodiment of the land expansion portion of a fuel cell separation plate according to an embodiment of the present invention. [Figure 6] This figure shows a third embodiment of the land expansion portion of a fuel cell separation plate according to an embodiment of the present invention. [Modes for carrying out the invention]

[0026] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0027] The advantages and features of the present invention, as well as methods for achieving them, will become clear with reference to the embodiments described in detail below, along with the accompanying drawings.

[0028] However, the present invention is not limited to the embodiments disclosed below and may be embodied in various other forms, and these embodiments are provided merely to complete the disclosure of the present invention and to fully inform a person ordinary skill in the art to which the present invention belongs of the scope of the invention, and the present invention should be defined by the scope of the claims.

[0029] Furthermore, when describing the present invention, if it is determined that related prior art or other information may obscure the gist of the invention, a detailed explanation thereof will be omitted.

[0030] Figure 2 shows a first embodiment of the land expansion portion of a fuel cell separation plate according to an embodiment of the present invention, and Figure 3 is a cross-sectional view AA of Figure 2 showing the first embodiment of the land expansion portion of a fuel cell separation plate according to an embodiment of the present invention.

[0031] Furthermore, Figure 4 shows a second embodiment of the land expansion portion of the fuel cell separation plate according to an embodiment of the present invention, Figure 5 is a cross-sectional view AA of Figure 4 showing the second embodiment of the land expansion portion of the fuel cell separation plate according to an embodiment of the present invention, and Figure 6 shows a third embodiment of the land expansion portion of the fuel cell separation plate according to an embodiment of the present invention.

[0032] Generally, fuel cell separators consist of multiple unit cells stacked in a repeating manner, with each unit cell comprising a membrane-electrode assembly (MEA), a gas diffusion layer (GDL), and a separator. The separator may be provided with a structure that includes various types of flow channels.

[0033] Of these, as shown in Figure 1A, a channel formed by connecting an inlet and outlet through which the reaction gas flows in and out, and extending it in a linear shape so that the reaction gas flows, is called a parallel channel. As shown in Figure 1B, a channel formed by connecting an inlet and outlet through which the reaction gas flows in and out, and extending it in a wave-like shape with a changing phase difference so that the reaction gas flows, is called a wavy channel.

[0034] Then, a channel that flows within a reaction region B having a predetermined area and assists in the reaction with the reacting gas can be defined as reaction channel 1, and a channel that is located outside of reaction region B and flows along the outer edge without participating in the reaction can be defined as unreacted channel 2 (see Figures 1A and 1B).

[0035] In the case of the straight channel shown in Figure 1B, the flow path is in a straight shape, so the unreacted flow path 2 at the uppermost end does not encroach on the reaction region B. However, in the case of the corrugated channel shown in Figure 1A, due to the characteristic of changing phase difference, the reactant gas may encroach on the reaction region B as it flows along the bent portion of the unreacted flow path 2 at the uppermost end, i.e., the valley portion formed by the wave shape (see Figure 1C).

[0036] As a result, the unreacted reaction gas in channel 2, i.e., hydrogen, which has encroached on the valley portion of the waveform channel, reacts with the reaction gas in channel 1, i.e., oxygen, which is contained within the reaction region B of the straight channel, generating water, which then accumulates in the land portion 2a (see Figure 1A).

[0037] At this time, a small amount of reaction gas flows along the unreacted channel 2, and depending on the flow rate of such reaction gas, it may not be possible to discharge the accumulated generated water. This accumulated generated water causes flooding in the land section 2a, which ultimately affects the durability of the membrane electrode assembly (MEA) and degrades the durability and performance of the fuel cell stack.

[0038] Therefore, the fuel cell separation plate according to this embodiment can solve the above-mentioned problems by extending the land extension portion 100 to a predetermined length in the land portion 2a adjacent to the unreacted flow path 2 that encroaches on the valley portion of the waveform channel, as shown in Figure 2.

[0039] In other words, in a fuel cell separation plate structure in which a first separation plate 10 containing a straight channel flow path and a second separation plate 20 containing a corrugated channel flow path are arranged facing each other with a reaction region B formed at the same position, the land extension portion 100 is extended and formed in the bent region C of the land portion 2a for connecting the unreacted flow path 2 located at the uppermost end of the second separation plate 20 and the reaction flow path 1 included in the reaction region B.

[0040] In other words, as shown in Figure 3, the land extension portion 100 is formed to extend a predetermined length along the direction in which the folded region C of the land portion 2a is filled, relative to the second separation plate 20 which contains a corrugated channel flow path facing the first separation plate 10, but the length is formed to extend beyond the boundary position of the reaction region B.

[0041] More specifically, as mentioned above (see Figures 1A to 1C), due to the characteristics of the second separation plate 20 where the phase difference of the waveform channel flow path changes, the reaction gas flowing along the unreacted channel 2 at the uppermost end may encroach on the reaction region B in the bent region C. Therefore, the land extension portion 100, which is extended in the bent region C of the land portion 2a adjacent to the unreacted channel 2, blocks the encroachment of the unreacted channel 2 on the boundary position of the reaction region B, thereby structurally preventing the hydrogen in the unreacted channel 2 from reacting with the oxygen in the first separation plate 10.

[0042] This fundamentally prevents the unreacted channel 2 from encroaching on the reaction region B, and minimizes the generation of water that accumulates in the bent region C of the unreacted channel 2. As a result, it is possible to improve water discharge performance in the low temperature / low current density region where it is difficult to discharge water generated from the fuel cell stack.

[0043] More preferably, in a fuel cell separation plate structure in which a first separation plate 10 and a second separation plate 20 are stacked such that their reaction regions B coincide (see Figure 3), the land extension portion 100 may be extended so as to coincide with the boundary position for forming the reaction region B when the bent region C is extended toward the uppermost end of the second separation plate 20.

[0044] Furthermore, the land extension portion 100 is formed in a manner that fills the bent region C of the unreacted flow path 2, and is formed along the flow direction of the reaction gas. It may be extended so that the length of one side is the same as the length of the other side, and the length of the central side is longer than that of the one side and the other side.

[0045] Thus, the structure in which the land extension portion 100 is extended to coincide with the boundary position for forming the reaction region B is merely one embodiment and is not limited thereto.

[0046] In other words, as shown in Figure 4, the land extension portion 100 may be extended to a predetermined length so that the folded region C is extended toward the uppermost end of the second separation plate 20 and exceeds the boundary position for forming the reaction region B.

[0047] More preferably, the land extension portion 100 may be extended to face the outermost land portion 10a connecting the unreacted flow path 2 in the first separation plate 10, as shown in Figure 5 (see Figure 1B). This ensures that the land portion 2a of the second separation plate 20 is extended to include the land extension portion 100 and positioned to face the land portion 10a, thereby providing further rigidity for supporting the first separation plate 10.

[0048] Here, as in the embodiment described above, the land extension portion 100 is formed in a manner that fills the bent region C of the unreacted flow path 2, thereby being formed along the flow direction of the reaction gas, and can be extended so that the length of one side is the same as the length of the other side, and the length of the central side is longer than that of the one side and the other side.

[0049] On the other hand, the land extension portion 100 may be formed to connect with the inverse forming 30 which is formed by folding in the direction of the opposite surface facing the gas diffusion layer in the folding region C.

[0050] As shown in Figure 6, such land extensions 100 may be formed on one and the other side of the folded region C and connected to the reverse forming 30. By connecting to the reverse forming 30 in this way, a circulation channel 100a for the reaction gas can be formed in the direction from the unreacted channel 2 toward the gasket 3.

[0051] In other words, the land extension 100 is configured such that the inflow of reaction gas into the reaction region B is blocked at the source by connecting one side and the other side of the folded region C of the land portion 2a adjacent to the unreacted flow path 2 located at the uppermost end of the second separation plate 20 where the reaction gas can intrude into the reaction region B, to the reverse forming 30. This creates a predetermined circulation flow path 100a between the land extension 100 and the reverse forming 30, allowing the reaction gas to flow towards the gasket 3 through the circulation flow path 100a.

[0052] This connects the land portion 2a of the unreacted flow path 2 and the reverse forming 30 via the land expansion portions 100 on one side and the other side, preventing the reaction gas flowing along the unreacted flow path 2 from flowing into the reaction region B between the land expansion portions 100 in the second separation plate 20, and effectively preventing the generation of water in the unreacted flow path.

[0053] In a separation plate structure in which linear channels and corrugated channels are repeatedly stacked, the present invention increases the land area of ​​the unreacted flow path of the corrugated channel that encroaches on a set reaction region, thereby preventing the generation of generated water in the unreacted flow path. This improves water discharge performance in the low temperature / low current range where water discharge performance is weakened, and has the effect of improving the performance of the stack.

[0054] As a result, the present invention has the effect of improving the durability of the stack by preventing deterioration due to the stagnation of generated water in the unreacted flow path.

[0055] Furthermore, the present invention has the effect of improving the durability degradation of the stack due to the freezing of the generated water accumulated in the unreacted channel under sub-zero conditions.

[0056] Although the present invention has been described above with reference to the embodiments shown in the drawings, these are merely illustrative examples, and any person with ordinary skill in the art will understand that various modifications are possible, and that all or part of the embodiments described above may be selectively combined to form the present invention. Therefore, the true scope of technical protection of the present invention should be determined by the technical idea of ​​the appended claims. [Explanation of symbols]

[0057] 1: Reaction channel 2: Unreacted channel 2a: Land area 3: Gasket 10: 1st separation plate 20: 2nd separation plate 30: Reverse forming 100: Land extension 100a: Circulation channel B: Reaction region C: Folding area

Claims

1. A fuel cell separation plate comprising a first separation plate containing a linear channel flow path and a second separation plate containing a corrugated channel flow path, which are repeatedly stacked, A fuel cell separation plate, characterized in that, in the reaction regions formed in the first separation plate and the second separation plate, the second separation plate includes a land expansion portion formed in the folded region of the land portion adjacent to the unreacted flow path located at the uppermost end of the second separation plate.

2. The aforementioned land extension portion is The fuel cell separation plate according to claim 1, characterized in that the bending region is extended in a direction toward the uppermost end of the second separation plate and is formed to coincide with the boundary position for forming the reaction region.

3. The aforementioned land extension portion is The fuel cell separation plate according to claim 2, characterized in that it is formed in the bending region along the flow direction of the reaction gas, is extended such that the length of one side is the same as the length of the other side, and is extended such that the length of the central side is longer than the length of the one side and the other side.

4. The aforementioned land extension portion is The fuel cell separation plate according to claim 1, characterized in that the bending region is extended in a direction toward the uppermost end of the second separation plate and is formed to exceed the boundary position for forming the reaction region.

5. The aforementioned land extension portion is The fuel cell separation plate according to claim 4, characterized in that it extends so as to face the land portion of the unreacted flow path located at the uppermost end of the first separation plate.

6. The aforementioned land extension portion is The fuel cell separation plate according to claim 4, characterized in that it is formed in the bending region along the flow direction of the reaction gas, is extended such that the length of one side is the same as the length of the other side, and is extended such that the length of the central side is longer than the length of the one side and the other side.

7. The aforementioned land extension portion is The fuel cell separation plate according to claim 1, characterized in that it is formed so as to be connected to an inverse forming portion that is formed by folding in the direction opposite to the gas diffusion layer in the aforementioned folding region.

8. The aforementioned land extension portion is The fuel cell separation plate according to claim 7, characterized in that it is formed on one side and the other side of the bending region and is connected to the reverse forming portion, respectively.

9. The aforementioned land extension portion is The fuel cell separation plate according to claim 7, characterized in that it forms a circulation channel for the reaction gas in the unreacted channel by being connected to the inverse forming section.

10. The first separator plate is, The linear channel is formed so that oxygen flows along it. The fuel cell separator according to claim 1, characterized in that the second separator is stacked facing the first separator such that the reaction regions coincide with each other, and is formed so that hydrogen flows along the corrugated channel flow path.

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