Fuel cell separator plate

Abstract

In a pulse-type orifice flow channel structure in which the widthwise length of the channel is repeatedly increased or decreased along the flow direction of the reactive gas, a fuel cell separator plate is provided that can improve water discharge performance at the land, ensure voltage stability to the fuel cell, and enable stable voltage generation. [Solution] A base plate forms a flow path for the reaction gas, and a first channel section includes a first retraction region and a first expansion region that are repeatedly positioned along the flow path; and a second channel section is arranged in parallel with the first channel section at a distance equal to the width of the land section, and includes a second expansion region positioned facing the first retraction region along the flow path, and a second retraction region positioned facing the first expansion region; wherein the first expansion region is provided in the same shape as the second expansion region and is formed by deforming it to have a cross-sectional area corresponding to the cross-sectional area of ​​the general region that forms the flow path in the first channel section.

Description

Technical Field

[0001] The present invention relates to a separator for a fuel cell, and more particularly, in a structure of a pulse-type orifice flow channel in which the length in the width direction of a channel is repeatedly increased and shortened, the cross-sectional area of the channel in a section where the length in the width direction of the channel increases is reduced to prevent a decrease in the flow velocity of a reactive gas. The present invention relates to a separator for a fuel cell.

Background Art

[0002] Generally, a fuel cell is a device that directly converts chemical energy of 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 studied with interest as a power source for automobiles, a power source for laser electric appliances, and the like.

[0003] 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. Therefore, in order to separate electrons from the hydrogen and oxygen and promote ionization, a humidifying device for supplying moisture to the hydrogen and oxygen is respectively installed on the anode and cathode of the fuel cell.

[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] The electrochemical reaction in a fuel cell consists of two reactions: an oxidation reaction at the oxidizing electrode (anode) and a reduction reaction at the reducing electrode (cathode). The two electrodes form a catalyst layer using platinum or a mixture of platinum and ruthenium metal to promote oxidation and reduction. To reduce the amount of platinum catalyst used and increase its utilization rate, fine carbon particles are used as a catalyst support. The final byproducts of the reaction are electricity, heat, and water. The water produced at the reducing electrode exists in the form of water and water vapor, and 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). The membrane-electrode assembly is supported by a separation plate with a channel through which hydrogen (methanol in the case of a direct methanol fuel cell) and oxygen or air (a reducing gas) can be supplied, and water produced by the oxidation-reduction reaction can be discharged. A gasket is provided to prevent gas or liquid supplied or discharged through the channel of the separation plate from leaking out. 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 constructed by fixing end plates to both ends as a means of securing them.

[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 functions as a mechanical support for each stacked unit battery. It also ensures that the fuel gas (hydrogen, methanol) and reducing gas (oxygen, air) flow uniformly to the electrodes through the 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, the reducing electrode will have an excess of water, consisting of water produced by electrochemical reactions and water moved from the oxidizing electrode by electroosmosis. Some of this excess water evaporates into the reducing gas (oxygen or air) flowing through the separation plate channel, saturating the gas. The water that does not evaporate remains in a liquid state in the gas diffusion layer (GDL) and the separation plate channel.

[0009] Excess water present in the gas diffusion layer or separation plate channel, if not properly discharged by an appropriate engineering mechanism, 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 Patent No. 10-0766154 Specification [Overview of the project] [Problems that the invention aims to solve]

[0011] The object of the present invention is to provide a fuel cell separator plate that, in a pulse-type orifice flow channel structure in which the widthwise length of the channel is repeatedly increased or decreased along the flow direction of the reaction gas, maintains the same widthwise length of the land between adjacent channels, reduces the cross-sectional area by adjusting the height of the channel in the section where the widthwise length of the channel increases, and prevents a decrease in the flow velocity of the reaction gas, thereby improving water discharge performance at the land, ensuring voltage stability to the fuel cell, and enabling stable voltage generation. [Means for solving the problem]

[0012] The fuel cell separator plate according to the present invention includes a base plate that forms a flow path for a reaction gas, a first channel portion including a first shrinking region and a first expanding region that are repeatedly positioned along the flow path, and a second channel portion that is arranged in parallel with the first channel portion at a distance equal to the width of the land portion, and includes a second expanding region positioned facing the first shrinking region along the flow path, and a second shrinking region positioned facing the first expanding region, wherein the first expanding region is provided in the same shape as the second expanding region and is formed by deforming the first channel portion to have a cross-sectional area corresponding to the cross-sectional area of ​​the general region that forms the flow path.

[0013] Such a first enlarged region is formed to have a relatively longer widthwise length compared to the general region, and a relatively shorter heightwise length compared to the general region.

[0014] Here, the first enlarged region is formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general region.

[0015] Furthermore, the first enlarged region is formed to have a relatively longer widthwise length compared to the general region, and to have a relatively smaller inclination angle of the side walls compared to the general region.

[0016] Here, the first enlarged region is formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general region.

[0017] Furthermore, the first enlarged region is formed to have a relatively longer widthwise length compared to the general region, and its side walls are formed with a step compared to the general region.

[0018] Here, the first enlarged region is formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general region.

[0019] On the other hand, the land portion is formed to have the same widthwise length along the flow path.

[0020] The separator plate for a fuel cell according to the present invention further includes an uppermost channel portion located at the uppermost end of the base plate, and the uppermost channel portion selectively includes a reduced region positioned to face the first reduced region and the first enlarged region along the flow path.

[0021] In addition, the separator plate for a fuel cell according to the present invention further includes a lowermost channel portion located at the lowermost end of the base plate, and the lowermost channel portion includes the general region forming the flow path and selectively includes an enlarged region positioned to face the second reduced region along the flow path.

Advantages of the Invention

[0022] In the pulse-type orifice flow path structure in which the length in the width direction of the channel repeatedly increases or decreases along the flow direction of the reaction gas, the length in the width direction of the land between adjacent channels is maintained the same, and in the section where the length in the width direction of the channel increases, the cross-sectional area is reduced through the adjustment of the channel height to prevent the decrease in the flow velocity of the reaction gas, thereby improving the water discharge performance on the land, ensuring the voltage stability for the fuel cell, and having the effect of stably generating the voltage.

[0023] And through various methods such as changing the inclination of the channel or changing the shape of the channel in the section where the length in the width direction increases, the cross-sectional area of the channel can be reduced at an optimal ratio compared to the general channel, so that the decrease in the flow velocity of the reaction gas in that section can be efficiently prevented.

Brief Description of the Drawings

[0024] [Figure 1] It is a diagram of a first embodiment for showing a first channel portion and a second channel portion of a separator plate for a fuel cell according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view taken along line A-A of FIG. 1 for showing a general region of a separator plate for a fuel cell according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view taken along line B-B of FIG. 1 for showing an enlarged region and a reduced region with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 4] It is a view of a second embodiment for showing a first channel portion and a second channel portion with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 5] It is a cross-sectional view taken along line C-C of FIG. 4 for showing an enlarged region and a reduced region with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 6] It is a view of a third embodiment for showing a first channel portion and a second channel portion with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 7] It is a cross-sectional view taken along line D-D of FIG. 6 for showing an enlarged region and a reduced region with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 8] It is a view for showing an uppermost channel portion and a lowermost channel portion with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 9] It is a view for showing an uppermost channel portion with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 10] It is a view for showing a lowermost channel portion with respect to a separator for a fuel cell according to an embodiment of the present invention. [Figure 11a] It is a view for showing an orifice flow path with respect to a conventional separator for a fuel cell. [Figure 11b] It is a view for showing an orifice flow path with respect to a conventional separator for a fuel cell. [Figure 11c] It is a view for showing an orifice flow path with respect to a conventional separator for a fuel cell. [Figure 12a] It is a view for showing a pulse-type orifice flow path with respect to a conventional separator for a fuel cell. [Figure 12b] It is a view for showing a pulse-type orifice flow path with respect to a conventional separator for a fuel cell. [Figure 12c] It is a view for showing a pulse-type orifice flow path with respect to a conventional separator for a fuel cell. [Modes for carrying out the invention]

[0025] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0026] The advantages, features, and methods for achieving the present invention will become clear with reference to the embodiments described in detail below, along with the accompanying drawings.

[0027] However, the present invention is not limited to the embodiments disclosed below, and can be embodied in a variety of different forms, provided that these embodiments are for the purpose of completing the disclosure of the present invention and fully informing those who are ordinary skill in the art to which the present invention pertains, and the present invention is defined only by the scope of the claims.

[0028] 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.

[0029] Figure 1 is a diagram of a first embodiment showing the first channel portion and the second channel portion of a fuel cell separation plate according to an embodiment of the present invention; Figure 2 is a cross-sectional view along line AA of Figure 1 showing the general region of the fuel cell separation plate according to an embodiment of the present invention; and Figure 3 is a cross-sectional view along line BB of Figure 1 showing the enlarged region and the reduced region of the fuel cell separation plate according to an embodiment of the present invention.

[0030] Figure 4 is a diagram of a second embodiment showing the first and second channel portions of a fuel cell separation plate according to an embodiment of the present invention, and Figure 5 is a cross-sectional view of Figure 4 along the CC line, showing the enlarged and reduced regions of the fuel cell separation plate according to an embodiment of the present invention.

[0031] Furthermore, Figure 6 is a diagram of a third embodiment showing the first and second channel portions of a fuel cell separation plate according to an embodiment of the present invention, and Figure 7 is a cross-sectional view of Figure 6 along the DD line showing the enlarged and reduced regions of the fuel cell separation plate according to an embodiment of the present invention.

[0032] Furthermore, Figure 8 is a diagram showing the uppermost channel portion and the lowermost channel portion of a fuel cell separation plate according to an embodiment of the present invention, Figure 9 is a diagram showing the uppermost channel portion of a fuel cell separation plate according to an embodiment of the present invention, and Figure 10 is a diagram showing the lowermost channel portion of a fuel cell separation plate according to an embodiment of the present invention.

[0033] Conventional fuel cell separators aim to supply a reaction gas such as hydrogen or air to the gas diffusion layer G while uniformly distributing it, and at the same time, to smoothly discharge the water generated by the reaction to the outside.

[0034] To address this, conventional fuel cell separators apply multiple orifice structures 1 along the flow path of the reaction gas. In other words, as shown in Figures 11a and 11b, they apply a structure to one of the adjacent channels 2 and 3 that reduces its length in the width and height directions (see 2' in Figure 11c), thereby narrowing its cross-sectional area compared to the other channels 3. This allows the reaction gas to move from the narrower channel 2' to the adjacent channel 3, thereby removing water from the land 4 through flow disturbance between channels 2' and 3.

[0035] However, in such conventional fuel cell separation plate structures, as the operating time increases, the porosity of the gas diffusion layer G decreases due to the contraction / expansion characteristics of the fuel cell, which reduces the flow of the reaction gas. As a result, water may accumulate in the land 4 that is in contact with the gas diffusion layer G.

[0036] Furthermore, as described above, the reduction in the widthwise length of channel 2' relatively extends the length of land 4, allowing a larger amount of water to accumulate in land 4.

[0037] Therefore, as shown in Figure 12a, a structure with an increased length in the width direction was applied to a position opposite the orifice structure 1. In other words, by applying a pulse-type orifice structure 1' to channels 2 and 3, which alternately positions the orifice structure 1 and the structure with an iteratively increasing length in the width direction along the flow path of the reaction gas, the length of the land 4 was kept constant along the flow path of the reaction gas.

[0038] In other words, as shown in Figures 12b and 12c, when the width and height lengths of either channel 2 or 3 adjacent to each other were reduced, the width length of the other channel 3 was increased, and the length of the land 4 positioned between the deformed channels 2' and 3' was kept constant.

[0039] However, in the pulsed orifice structure 1' of the fuel cell separator plate described above, while it can effectively remove water accumulated in the land 4, the increased width of the channel 3' can lead to a decrease in the flow velocity of the reaction gas. This prevents the fuel cell cell from stably generating voltage, ultimately reducing the stability of the fuel cell.

[0040] To this end, the fuel cell separation plate according to this embodiment applies a conventional pulse-type orifice structure 1' including a first channel portion 100 and a second channel portion 200 (see Figures 12a to 12c), deforms the shape of the enlarged regions 120 and 210, and effectively removes water accumulated in the land portion 300 while enabling the fuel cell cell to generate voltage stably.

[0041] Here, as shown in Figure 1, the first channel section 100 forms a flow path for the reaction gas with the base plate 100a and includes a first shrinking region 110 and a first expanding region 120 that are repeatedly positioned along the flow path.

[0042] The second channel section 200 is arranged in parallel with the first channel section 100, separated by the width of the land section 300, and includes a second expansion section 210 positioned facing the first contraction section 110 along the flow path, and a second contraction section 220 positioned facing the first expansion section 120.

[0043] In other words, as shown in Figure 2, the general regions 130 and 230 of the first channel portion 100 and the second channel portion 200 have the same shape, but as shown in Figure 3, the first reduced region 110 and the second increased region 210 and the first increased region 120 and the second reduced region 220 are formed to have different shapes from each other.

[0044] Preferably, the land portion 300 is formed to have the same widthwise length along the flow path. As shown in Figures 2 and 3, the widthwise length of the general region 130 is reduced, and the first reduced region 110 is formed. This relatively increases the widthwise length of the general region 230, and the second increased region 210 is formed. At this time, the second increased region 210 is formed to have a relatively shorter length along the height direction.

[0045] More preferably, as shown in Figure 3, the second enlarged region 210 can be deformed to have a cross-sectional area corresponding to the cross-sectional area of ​​the general region 230 that forms the flow path in the second channel portion 200. For example, the land portion 300 may be formed with a relatively longer widthwise length compared to the general region 230 so as to have the same widthwise length along the flow path, and the second enlarged region 210 may be formed with a relatively shorter heightwise length compared to the general region 230.

[0046] Here, the first augmented region 120 and the second augmented region 210 can be formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general regions 130 and 230.

[0047] Therefore, by deforming the height of the first augmentation region 120 and the second augmentation region 210 to be relatively shorter than that of the conventional pulse-type orifice structure 1', and more specifically by deforming them into a trapezoidal shape with a shorter length (see Figures 12a to 12c), they have a cross-sectional area equivalent to that of the general regions 130 and 230, and as a result, the reaction gas can be flowed at a relatively faster velocity compared to the conventional pulse-type orifice structure 1'.

[0048] In addition, in the case of the conventional pulse-type orifice structure 1', water discharge in the land portion 300 can be facilitated, but increasing the widthwise length so that the length of the land portion 300 is set to a constant level causes a decrease in the flow velocity of the reaction gas in the channel. To improve this, the heightwise length of the first augmentation region 120 and the second augmentation region 210 is deformed to be relatively shorter, that is, the cross-sectional area is reduced, thereby preventing a decrease in the flow velocity of the reaction gas in the first augmentation region 120 and the second augmentation region 210 compared to the conventional structure.

[0049] Thus, preventing a decrease in the flow velocity of the reaction gas in the first channel section 100 and the second channel section 200 by reducing the height of the first augmentation region 120 and the second augmentation region 210 corresponds to only one of the embodiments and is not predetermined; therefore, the same effect can be achieved by applying other embodiments as well.

[0050] For example, as shown in Figures 4 and 5, the first augmented region 120 and the second augmented region 210 may be formed to have a relatively longer widthwise length compared to the general regions 130 and 230, and the inclination angle θ of the side walls may be relatively smaller compared to the general regions 130 and 230 (see Figure 5).

[0051] In this case, the first enlarged region 120 and the second enlarged region 210 can be formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general regions 130 and 230, in the same manner as in the embodiment described above.

[0052] As another example, as shown in Figures 6 and 7, the first augmented region 120 and the second augmented region 210 may be formed to have a relatively longer widthwise length compared to the general regions 130 and 230, and the side walls may be formed to have steps while forming a staircase structure compared to the general region (see Figure 7).

[0053] Similar to the embodiments described above, the first enlarged region 120 and the second enlarged region 210 in this case can be formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general regions 130 and 230, just as in the embodiments described above.

[0054] On the other hand, as shown in Figure 8, the fuel cell separation plate according to this embodiment may further include an uppermost channel portion 400 and a lowermost channel portion 500.

[0055] As shown in Figure 9, the uppermost channel portion 400 is located at the uppermost end of the base plate 100a and can selectively include a reduced region 400a that is positioned along the flow path and opposite the first reduced region 110 and the first increased region 120 of the first channel portion 100.

[0056] This is because no reaction occurs in the flow path of the uppermost channel section 400, and therefore there is no need for the reaction gas to flow through that flow path. By selectively arranging the reduced region 400a, the flow path is repeatedly reduced, inducing resistance and thus reducing the supply of reaction gas to the flow path of the uppermost channel section 400.

[0057] Furthermore, as shown in Figure 10, the lowest channel portion 500 is located at the lowest end of the base plate 100a and includes a general region 500a that forms a flow path, and can selectively include an enlarged region 500b that is positioned along the flow path and opposite the second reduced region 220 of the second channel portion 200.

[0058] In the case of the lowest channel section 500, this corresponds to a passage through which water generated by gravity moves, so the cross-sectional area is reduced, and instead of being a structure that obstructs the flow of discharged water, a flow path is formed that includes only the general region 500a and the increased region 500b, thereby effectively securing a flow path for water removal.

[0059] The present invention relates to a pulse-type orifice flow channel structure in which the widthwise length of the channel is repeatedly increased or decreased along the flow direction of the reaction gas. In this structure, the widthwise length of the land between adjacent channels is kept the same, and the cross-sectional area is reduced by adjusting the height of the channel in the section where the widthwise length of the channel increases, thereby preventing a decrease in the flow velocity of the reaction gas. This improves the water discharge performance at the land, ensures voltage stability for the fuel cell cell, and enables stable voltage generation.

[0060] Furthermore, by changing the channel's inclination in sections where its width increases, or by changing the channel's shape, the channel's cross-sectional area can be reduced at an optimal ratio compared to a general channel. This has the effect of efficiently preventing a decrease in the flow velocity of the reactive gas in those sections.

[0061] Although the present invention has been described above with reference to the embodiments shown in the drawings, these are merely illustrative, and a person with ordinary skill in the art will understand that a variety of modifications are possible, and that all or part of the embodiments described above can 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]

[0062] 100 Channel 1 100a base plate 110, 220, 400a reduction area 120, 210, 500b augmentation regions 130, 230, 500a general area 200 Second Channel Section 300 Land Division 400 Topmost channel section 500 Bottommost channel section

Claims

1. A base plate forms a flow path for the reaction gas, and a first channel portion includes a first shrinking region and a first expanding region that are repeatedly positioned along the flow path; and A second channel portion includes a second expanding region positioned parallel to the first channel portion at a distance equal to the width of the land portion, and located along the flow path facing the first shrinking region, and a second shrinking region located facing the first expanding region; The first augmented region is, A fuel cell separation plate is provided in the same shape as the second enlarged region and is formed by deforming it to have a cross-sectional area corresponding to the cross-sectional area of ​​the general region that forms the flow path in the first channel portion.

2. The first augmented region is, The fuel cell separation plate according to claim 1, characterized in that it is formed to have a relatively longer widthwise length compared to the general area, and a relatively shorter heightwise length compared to the general area.

3. The first augmented region is, The fuel cell separation plate according to claim 2, characterized in that it is formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general area.

4. The first augmented region is, The fuel cell separation plate according to claim 1, characterized in that it is formed to have a relatively longer widthwise length compared to the general area, and the angle of inclination of the side wall is relatively smaller compared to the general area.

5. The first augmented region is, The fuel cell separation plate according to claim 4, characterized in that it is formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general region.

6. The first augmented region is, The fuel cell separation plate according to claim 1, characterized in that it is formed to have a relatively longer widthwise length compared to the general area, and the side walls are formed to have a step compared to the general area.

7. The first augmented region is, The fuel cell separation plate according to claim 6, characterized in that it is formed with a cross-sectional area ratio of 1:1 to 1.3 with respect to the general area.

8. The aforementioned land portion is The fuel cell separation plate according to claim 1, characterized in that it is formed to have the same widthwise length along the flow path.

9. The above base plate further includes an uppermost channel portion located at the uppermost end of the base plate, The uppermost channel portion is, The fuel cell separation plate according to claim 1, characterized in that it selectively includes a reduction region located along the flow path so as to face the first reduction region and the first increase region.

10. The base plate further includes a lowest end channel portion located at the lowest end of the base plate, The lowermost channel section is, The fuel cell separator plate according to claim 1, characterized in that it includes the general region that forms the flow path, and selectively includes an enlarged region positioned along the flow path opposite the second reduced region.

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