Separator for fuel cell

Abstract

The present invention relates to a separator plate for a fuel cell, comprising: a first channel comprising first narrowing regions and first widening regions repeatedly arranged within a first regular region, the first channel being configured to form a flow path of a reaction gas on a substrate; and a second channel disposed parallel to the first channel spaced apart by a widthwise length of a boss, the second channel comprising second narrowing regions and second widening regions repeatedly arranged along the flow path within a second regular region; wherein along the flow path, the second widening regions are arranged adjacent to the first narrowing regions, and the second narrowing regions are arranged adjacent to the first widening regions; wherein the first widening regions have the same shape as the second widening regions; wherein the first regular region has the same cross-sectional area as the second regular region; and wherein the first widening regions and the second widening regions each have a cross-sectional area corresponding to the cross-sectional area of the first regular region.

Description

Technical Field

[0001] This invention relates to a separator for fuel cells. Background Technology

[0002] Generally speaking, a fuel cell is a device that directly electrochemically converts the chemical energy of fuel into electrical energy within the fuel cell, rather than converting chemical energy into heat through combustion. It is also a pollution-free power generation device, and its application as a power source for vehicles, laser devices, etc., is attracting interest in research.

[0003] Hydrogen, as a fuel gas, is supplied to the anode of the fuel cell, and oxygen, as an oxidant, is supplied to the cathode. To separate electrons from the hydrogen and oxygen and promote ionization, a humidifier is installed at each of the anode and cathode of the fuel cell to supply moisture to the hydrogen and oxygen.

[0004] Depending on the operating temperature and the type of electrolyte, fuel cells are classified into solid oxide fuel cells, molten carbonate fuel cells, polymer electrolyte membrane fuel cells, and direct methanol fuel cells.

[0005] In a fuel cell, two electrochemical reactions occur: oxidation at the anode and reduction at the cathode. In each of the two electrodes, a catalyst layer using platinum or a combination of platinum and ruthenium is formed to facilitate oxidation or reduction. Fine carbon particles are used as the catalyst support to reduce the amount of platinum catalyst used and improve its utilization. The final byproducts of the reaction are electricity, heat, and water. The water generated at the cathode exists as water and water vapor and is typically removed by a vigorous flow of reducing gas (oxygen or air) to the cathode.

[0006] A basic cell in a fuel cell stack comprises two electrodes, an anode and a cathode, separated by a polymer electrolyte membrane. The polymer electrolyte membrane and the anode and cathode on its outer surface are hot-pressed to form a membrane electrode assembly (MEA). The MEA is supported by a separator with flow paths formed thereon to supply hydrogen as fuel (methanol in the case of a direct methanol fuel cell) and oxygen or air as a reducing gas, and to discharge water generated by the redox reaction. Gaskets are provided to prevent leakage of the gas or liquid supplied or discharged through the flow paths of the separator. These cell units, including the MEA, separator, and gaskets, are stacked in series to achieve the desired output. The fuel cell stack is formed by fixing end plates, as stationary units, to both ends of the cell units.

[0007] The separator serves to electrically connect the two electrodes while preventing the fuel (hydrogen or methanol) and reducing gas (oxygen or air) from mixing within the fuel cell. The separator also functions as mechanical support for the stacked cell units and allows the fuel (hydrogen or methanol) and reducing gas (oxygen or air) to flow uniformly to the electrodes through flow paths formed on the separator, thus preventing the membrane from drying out through proper humidity management. When operating a polymer electrolyte fuel cell, it is important to supply a sufficiently humidified supply of fuel and reducing gas (oxygen or air).

[0008] Under high-current operating conditions exceeding the critical current density, excess water is present at the cathode, generated by electrochemical reactions, and water migrates from the anode via electroosmosis. A portion of the excess water evaporates into reducing gas (oxygen or air) flowing through the partition channels, saturating the reducing gas. The non-evaporating water exists in a liquid state within the gas diffusion layer (GDL) or the partition channels.

[0009] Excessive water present in the gas diffusion layer or partition channels can lead to overflow if it is not discharged to the outside through appropriate engineering mechanisms, causing fatal problems in fuel cell performance or reliability.

[0010] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this invention, and therefore may contain information that does not constitute prior art as defined by patent law. Summary of the Invention

[0011] Embodiments of the present invention relate to a separator for a fuel cell, wherein in a pulsed orifice flow path structure with a channel width length that repeatedly increases and decreases, the cross-sectional area of ​​the channel decreases in the sections where the channel width length increases. This structure can prevent a decrease in the flow rate of the reactant gas.

[0012] This invention describes a subject that can solve the aforementioned problems associated with the prior art. Embodiments of the invention provide a separator for a fuel cell, wherein, in a pulsed orifice flow path structure, the width-direction length of the channel repeatedly increases and decreases in the direction of reactant gas flow. The width-direction length of the bosses between adjacent channels remains constant, but in sections where the width-direction length of the channel increases, the cross-sectional area of ​​the channel decreases. This structure prevents a decrease in reactant gas flow velocity, thereby improving the emission performance of the bosses and ensuring the voltage stability of the fuel cell to stabilize the generated voltage.

[0013] In one aspect, the present invention provides a separator for a fuel cell, comprising: a first channel configured to form a flow path for a reactant gas on a substrate, and including a first narrowing region and a first enlarged region repeatedly arranged along the flow path; and a second channel configured to be spaced apart from the first channel in a width direction by a boss, and including a second enlarged region arranged along the flow path facing the first narrowing region and a second narrowing region arranged facing the first enlarged region. The first enlarged region is configured to have the same shape as the second enlarged region and is modified to have a cross-sectional area corresponding to the cross-sectional area of ​​the conventional region configured to form the flow path in the first channel.

[0014] In one embodiment, the first enlarged region may be formed to have a greater width length and a smaller height length than the conventional region.

[0015] In another embodiment, the ratio of the cross-sectional area of ​​the enlarged region to the cross-sectional area of ​​the conventional region is 1:1 to 1:1.3.

[0016] In yet another embodiment, the first enlarged region may be formed to have a greater width-direction length and a smaller sidewall inclination angle than the conventional region.

[0017] In another embodiment, the first enlarged region may be formed to have a greater width-direction length than the conventional region and to have stepped sidewalls compared to the conventional region.

[0018] In a further embodiment, the boss may be formed to have the same width-direction length along the flow path.

[0019] In a further embodiment, the partition may also include a topmost channel located at the topmost part of the substrate. The topmost channel may optionally include a shrinking region arranged along the flow path facing the first shrinking region and the first expanding region.

[0020] In a further embodiment, the partition may also include a lowermost channel located at the bottommost part of the substrate. The lowermost channel may include a conventional region configured to form a flow path, and optionally include an enlarged region along the flow path facing the second shrinkage region.

[0021] It should be understood that the embodiments can be combined with each other. Other aspects and embodiments of the invention are discussed below.

[0022] The above and other features of the invention are discussed below. Attached Figure Description

[0023] The above and other features of the invention will now be described in detail with reference to certain exemplary embodiments of the invention shown in the accompanying drawings, which are given hereinafter by way of illustration only and are not intended to limit the invention. In the drawings:

[0024] Figure 1 This is a view showing the first and second channels of a separator for a fuel cell according to a first embodiment of the present invention;

[0025] Figure 2 It is along Figure 1 The cross-sectional view taken by line AA shows the conventional area of ​​the separator for a fuel cell according to the first embodiment of the present invention;

[0026] Figure 3 It is along Figure 1 The cross-sectional view taken by the BB line shows the enlarged region and the reduced region of the separator for a fuel cell according to the first embodiment of the present invention;

[0027] Figure 4 This is a view showing the first and second channels of a separator for a fuel cell according to a second embodiment of the present invention;

[0028] Figure 5 It is along Figure 4 A cross-sectional view taken by the CC line shows the enlarged and reduced regions of the separator for a fuel cell according to the second embodiment of the present invention;

[0029] Figure 6 This is a view showing the first and second channels of a separator for a fuel cell according to a third embodiment of the present invention;

[0030] Figure 7 It is along Figure 6 A cross-sectional view taken by the DD line shows the enlarged and reduced regions of the separator for a fuel cell according to the third embodiment of the present invention;

[0031] Figure 8 This is a view showing the uppermost and lowermost channels of a separator for a fuel cell according to an embodiment of the present invention;

[0032] Figure 9 This is a view showing the uppermost channel of a separator for a fuel cell according to an embodiment of the present invention;

[0033] Figure 10 This is a view showing the lowermost channel of a separator for a fuel cell according to an embodiment of the present invention;

[0034] Figures 11A to 11C This is a view showing the orifice flow path of a conventional separator used in fuel cells; and

[0035] Figures 12A to 12C This is a view showing the pulsed orifice flow path of another conventional separator used in fuel cells.

[0036] It should be understood that the accompanying drawings are not necessarily drawn to scale, but rather present a simplified representation of various preferred features illustrating the basic principles of the invention. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific intended application and usage environment.

[0037] In the figures, reference numerals refer to the same or equivalent portions of the invention that run through several figures. Detailed Implementation

[0038] In the following, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0039] The advantages and features of the invention, as well as the methods for carrying out the invention, will become apparent from the following description of embodiments with reference to the accompanying drawings.

[0040] However, the present invention is not limited to the embodiments disclosed herein, but can be implemented in various different forms, and these embodiments are provided to provide a thorough description of the invention and to fully convey its scope to those skilled in the art. Note that the scope of the invention is defined only by the claims.

[0041] Furthermore, in the following description of the invention, detailed descriptions of known functions and configurations incorporated herein will be omitted if it may obscure the subject matter of the invention.

[0042] The purpose of a traditional fuel cell separator is to evenly distribute the reactant gases, such as hydrogen or air, supply the reactant gases to the gas diffusion layer G, and smoothly discharge the water generated by the reaction to the outside.

[0043] Therefore, traditional fuel cell separators employ a multi-orifice structure along the flow path of the reactant gas, i.e., as shown in the figure. Figure 11A and Figure 11B As shown. The partition adopts the following structure, wherein the width and height lengths of one of the adjacent channels 2 and 3 are reduced (see reference). Figure 11C The 2' channel has a narrower cross-sectional area than the other channel 3. Therefore, as the reactant gas moves from the channel 2' with the smaller cross-sectional area to the adjacent channel 3, the water on the platform 4 is removed by the flow disturbance between channels 2' and 3.

[0044] However, in the structure of a conventional fuel cell separator, the flow rate of the reactant gas is reduced, and water may accumulate on the protrusions 4 that contact the gas diffusion layer G. This is likely because the porosity of the gas diffusion layer G decreases due to the contraction and expansion characteristics of the fuel cell as operating time increases.

[0045] Furthermore, as mentioned above, as the width of channel 2' decreases, the length of boss 4 increases relatively, so a larger amount of water may accumulate on boss 4.

[0046] like Figure 12A As shown, a structure with increased width length can be applied to the position facing orifice structure 1. That is, pulse-type orifice structure 1' in which orifice structure 1 and structure with increased width length are alternately arranged in channels 2 and 3, thereby ensuring that the width length of boss 4 remains constant along the flow path of the reactant gas.

[0047] In other words, such as Figure 12B and Figure 12C As shown, in the case of adjacent channels 2 and 3, if the width and height lengths of one channel 2 decrease, the width length of the other channel 3 increases, thereby ensuring that the length of the boss 4 set between the deformable channels 2' and 3' remains constant.

[0048] However, in the aforementioned pulsed orifice structure 1' of the separator used in the fuel cell, although water accumulated on the boss 4 can be effectively removed, the flow rate of the reactant gas may decrease due to the increased width-direction length of the channel 3'. Therefore, the fuel cell may not stably generate voltage, and the stability of the fuel cell may decrease.

[0049] Therefore, according to an embodiment of the present invention, the separator for a fuel cell incorporates a conventional pulsed orifice structure 1' (see... Figures 12A to 12C The solution is applied to the first channel 100 and the second channel 200, and includes enlarged regions 120 and 210 with deformable shapes, thereby effectively removing water accumulated on the boss 300 and allowing the fuel cell to generate voltage stably.

[0050] For example, Figure 1 A view is provided illustrating a first channel and a second channel of a separator for a fuel cell according to a first embodiment of the present invention. Figure 2 It is along Figure 1 The cross-sectional view taken by line AA shows the conventional area of ​​the separator for a fuel cell according to the first embodiment of the present invention. Figure 3 It is along Figure 1 The cross-sectional view taken by the BB line shows the enlarged and reduced regions of the separator for a fuel cell according to the first embodiment of the present invention.

[0051] Here, the first channel 100 forms a flow path for the reactive gas on the substrate 100a, and includes a first shrinkage region 110 and a first expansion region 120 repeatedly arranged along the flow path.

[0052] Furthermore, the second channel 200 is arranged parallel to the first channel 100 and spaced apart from the boss 300 in the width direction. These channels include a second enlarged region 210 arranged along the flow path facing the first reduced region 110, and a second reduced region 220 arranged facing the first enlarged region 120.

[0053] In other words, such as Figure 2 As shown, the regular regions 130 and 230 of the first channel 100 and the second channel 200 have the same shape. However, as Figure 3 As shown, the first reduced region 110 and the second enlarged region 210 are formed with different shapes. Similarly, the first enlarged region 120 and the second reduced region 220 are formed with different shapes.

[0054] In particular, such as Figure 2 and Figure 3 As shown, the boss 300 is formed to have the same width direction length along the flow path. To achieve this, a first reduced region 110 is formed by reducing the width direction length of the regular region 130, and a second enlarged region 210 is formed by increasing the width direction length of the regular region 230. Furthermore, the second enlarged region 210 is formed to have a relatively small height direction length.

[0055] More specifically, such as Figure 3 As shown, the second enlarged region 210 can be formed to have a cross-sectional area corresponding to the cross-sectional area of ​​the conventional region 230 that forms the flow path. For example, compared to the conventional region 230, the boss 300 can be formed to have a relatively larger width direction length so as to have the same width direction length along the flow path, and compared to the conventional region 230, the second enlarged region 210 can be formed to have a relatively smaller height direction length.

[0056] Here, the first enlarged region 120 and the second enlarged region 210 can be formed with a cross-sectional area ratio of 1:1 to 1:1.3 relative to the conventional regions 130 and 230.

[0057] Therefore, compared to the conventional pulse-type orifice structure 1', the first enlarged region 120 and the second enlarged region 210 are deformed to have relatively small lengths in the height direction. More specifically, regions 120 and 210 are deformed into shorter trapezoidal shapes (see...). Figures 12A to 12CIt has a cross-sectional area corresponding to that of conventional regions 130 and 230. This feature allows the reactant gas to flow at a higher velocity than that of the conventional pulsed orifice structure 1'.

[0058] In the conventional pulse-type orifice structure 1', drainage from the boss 4 is facilitated. However, due to the increased width length of channels 2 and 3, the width length of the boss 4 is kept constant, thus reducing the flow rate of the reactant gas in channels 2 and 3. To improve this problem, the first enlarged region 120 and the second enlarged region 210 are modified to have a relatively small height length, i.e., a reduced cross-sectional area. This prevents the reduction in the flow rate of the reactant gas in the first enlarged region 120 and the second enlarged region 210 compared to the conventional pulse-type orifice structure 1'.

[0059] Therefore, preventing a decrease in the flow rate of the reactant gas in the first channel 100 and the second channel 200 by reducing the height length of the first enlarged region 120 and the second enlarged region 210 corresponds to only one embodiment, and the same effect can be achieved by applying other embodiments.

[0060] For example, Figure 4 This is a view showing the first and second channels of a separator for a fuel cell according to a second embodiment of the present invention. Figure 5 It is along Figure 4 The cross-sectional view taken by the CC line shows the enlarged and reduced regions of the separator for a fuel cell according to the second embodiment of the present invention.

[0061] like Figure 4 and Figure 5 As shown, the first enlarged region 120 and the second enlarged region 210 can be formed to have a relatively large width-direction length compared to the conventional regions 130 and 230, but can be formed to have a relatively small sidewall inclination angle θ compared to the conventional regions 130 and 230 (see...). Figure 5 ).

[0062] Here, the first enlarged region 120 and the second enlarged region 210 can be formed in the same manner as in the previous embodiment, with a cross-sectional area ratio of 1:1 to 1:1.3 relative to the conventional regions 130 and 230.

[0063] Figure 6 and Figure 7 Another example is provided below. Figure 6 This is a view showing the first and second channels of a separator for a fuel cell according to a third embodiment of the present invention. Figure 7 It is along Figure 6 The cross-sectional view taken by the DD line shows the enlarged and reduced regions of the separator for a fuel cell according to the third embodiment of the present invention.

[0064] like Figure 6 and Figure 7 As shown, the first enlarged region 120 and the second enlarged region 210 can be formed to have a relatively larger width-direction length compared to the conventional regions 130 and 230, but compared to the conventional regions 130 and 230, they can be formed to have stepped sidewalls, that is, to have a stepped structure (see...). Figure 7 ).

[0065] Here, the first enlarged region 120 and the second enlarged region 210 can be formed in the same manner as in the previous embodiment, with a cross-sectional area ratio of 1:1 to 1:1.3 relative to the conventional regions 130 and 230.

[0066] Figure 8 This is a view showing the uppermost and lowermost channels of a separator for a fuel cell according to an embodiment of the present invention. Figure 8 As shown, the partition according to one embodiment of the present invention may further include an uppermost channel 400 and a lowermost channel 500.

[0067] like Figure 9 As shown, the uppermost channel 400 is located at the uppermost part of the substrate 100a, and may selectively include a reduced region 400a arranged along the flow path facing the first channel 100, the first reduced region 110 and the first expanded region 120.

[0068] Since no reaction occurs in the flow path of the uppermost channel 400, the reactant gas does not need to flow through the corresponding flow path. Therefore, by selectively arranging the narrowing region 400a, the flow path is repeatedly reduced, thereby generating resistance. As a result, less reducing gas is supplied to the flow path of the uppermost channel 400.

[0069] In addition, such as Figure 10 As shown, the lowermost channel 500 is located at the lowermost part of the substrate 100a and may include a conventional region 500a forming a flow path, and optionally include an enlarged region 500b arranged along the flow path facing the second channel 200, which is a second reduced region 220.

[0070] Since the lowest channel 500 corresponds to the passageway through which water moves due to gravity, the lowest channel 500 can form a flow path that includes only the regular area 500a and the enlarged area 500b, rather than a structure with a reduced cross-sectional area to obstruct the flow of water to be discharged, thereby ensuring an effective water removal flow path.

[0071] In this invention, the width of the channel in a pulsed orifice flow path structure is repeatedly increased or decreased along the flow direction of the reactant gas. This ensures that the width of the bosses between adjacent channels remains the same, but the cross-sectional area of ​​the channel is reduced in sections where the width of the channel increases to prevent a decrease in the flow velocity of the reactant gas. This configuration improves the drainage performance of the bosses and ensures the voltage stability of the fuel cell to maintain a stable generated voltage.

[0072] Furthermore, embodiments of the present invention can reduce the cross-sectional area of ​​the channel in an optimal ratio to the conventional area of ​​the channel by various methods, such as changing the slope or shape of the channel in the section where the width direction length increases, thereby effectively preventing the flow rate of the reactant gas in the corresponding section from decreasing.

[0073] As can be easily understood from the above description, in the pulsed orifice flow path structure in which the width length of the channel repeatedly increases or decreases in the flow direction of the reactant gas, the width length of the bosses between adjacent channels remains the same, but the cross-sectional area of ​​the channel is reduced in the section where the width length of the channel increases, so as to prevent the flow velocity of the reactant gas from decreasing, thereby improving the drainage performance of the bosses and ensuring the voltage stability of the fuel cell to stabilize the generated voltage.

[0074] Furthermore, the present invention can reduce the cross-sectional area of ​​the channel by various methods to achieve an optimal ratio with the conventional area of ​​the channel, such as by changing the slope or shape of the channel in the section where the width direction length increases, thereby effectively preventing the flow rate of the reactant gas in the corresponding section from decreasing.

[0075] The present invention has been described in detail above with reference to embodiments thereof. However, those skilled in the art will understand that changes can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A separator for a fuel cell, comprising: A first channel includes a first reduced region and a first expanded region repeatedly arranged within a first conventional region, the first channel being configured to form a flow path for the reactive gas on the substrate; as well as The second channel is configured to be parallel to the first channel and spaced apart from the width of the boss by a length, and the second channel includes a second narrowing region and a second expanding region that are repeatedly arranged along the flow path within the second conventional region; Along the flow path, the second expanding region is arranged adjacent to the first shrinking region, and the second shrinking region is arranged adjacent to the first expanding region. The first enlarged region has the same shape as the second enlarged region; Wherein, the first conventional region has the same cross-sectional area as the second conventional region; and The first enlarged region and the second enlarged region each have a cross-sectional area corresponding to the cross-sectional area of ​​the first conventional region.

2. The partition according to claim 1, wherein, The first enlarged region has a greater width length than the first regular region and a smaller height length than the first regular region.

3. The partition according to claim 1, wherein, The first enlarged region has a greater width length than the first conventional region and a smaller sidewall inclination angle than the first conventional region.

4. The partition according to claim 1, wherein, The first enlarged region has a greater width length than the first regular region and has stepped sidewalls compared to the first regular region.

5. The partition according to claim 1, wherein, Each of the protrusions has a constant length in the width direction along the flow path.

6. The partition according to claim 1, further comprising an uppermost channel located at the uppermost part of the substrate, wherein, The uppermost channel includes a narrowing region arranged adjacent to the first narrowing region and the first expanding region along the flow path.

7. The partition according to claim 1, further comprising a lowermost channel located at the lowermost part of the substrate, wherein, The lowermost channel includes a lowermost regular region configured to form a flow path, and includes an enlarged region arranged adjacent to the second reduced region along the flow path.

8. A separator for a fuel cell, comprising: Multiple first channels, each first channel including a flow path for the reactant gas on the substrate, each flow path including a conventional region in which a shrinkage region and an expansion region are formed; as well as A plurality of second channels, each second channel being parallel to an adjacent first channel and spaced apart from the adjacent first channel by a boss, each second channel including a flow path having a conventional region in which a narrowing region and an enlarging region are formed, wherein, along the flow path, the enlarging region of each second channel is arranged adjacent to the narrowing region of the adjacent first channel, and the narrowing region of each second channel is arranged adjacent to the enlarging region of the adjacent first channel. Each of the first and second channels has a first cross-sectional area in its regular region; Each of the reduced regions of the first and second channels has a second cross-sectional area; Wherein, the enlarged region of each first channel and second channel has a third cross-sectional area larger than the second cross-sectional area; and The ratio of the third cross-sectional area to the first cross-sectional area is 1:1 to 1:1.

3.

9. The partition according to claim 8, wherein, For each first channel and second channel, the enlarged region has a greater width length and a smaller height length than the regular region.

10. The partition according to claim 8, wherein, For each first channel and second channel, the enlarged region has a greater width-direction length than the conventional region, and a smaller sidewall inclination angle than the conventional region.

11. The partition according to claim 8, wherein, For each first channel and second channel, the enlarged region has a greater width-direction length than the conventional region and has stepped sidewalls compared to the conventional region.

12. The partition according to claim 8, wherein, For each second channel and adjacent first channel, the boss has a constant width length along the flow path.

13. The partition according to claim 8, further comprising an uppermost channel located at the uppermost part of the substrate, wherein, The uppermost channel includes a narrowed region arranged adjacent to the narrowed and expanded regions of the adjacent channels along the flow path.

14. The partition according to claim 8, further comprising a lowermost channel located at the lowermost part of the substrate, wherein, The lowermost channel includes a lowermost regular region configured to form a flow path, and includes an enlarged region arranged adjacent to the reduced region of the adjacent channel along the flow path.

15. A separator for a fuel cell, comprising: Multiple first channels, each first channel including a flow path for the reactant gas on the substrate, each flow path including a conventional region in which a shrinkage region and an expansion region are formed; A plurality of second channels, each parallel to an adjacent first channel, each second channel including a flow path having a conventional region in which a narrowing region and an expanding region are formed, wherein, along the flow path, the expanding region of each second channel is arranged adjacent to the narrowing region of the adjacent first channel, and the narrowing region of each second channel is arranged adjacent to the expanding region of the adjacent first channel; and Multiple bosses, each boss being arranged in one of the second channels between the adjacent first channels, wherein each boss has a constant width-direction length along the flow path.

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