Fuel cell, fuel cell stack, and fuel cell system
By introducing a nitrogen separation layer into the fuel cell unit, the problem of reduced oxygen concentration on the cathode side is solved, the reaction rate and performance are improved, and nitrogen permeation is reduced, resulting in cost-effective improvements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-04-03
AI Technical Summary
In existing proton exchange membrane fuel cells, a decrease in oxygen concentration on the cathode side leads to a slowdown in the reaction rate, and nitrogen diffuses into the cathode catalyst layer, affecting performance.
A nitrogen separation layer is introduced into the fuel cell unit. Nitrogen separation bars block nitrogen diffusion in the cathode gas channel, allowing oxygen to pass through to the cathode catalyst layer. This reduces the nitrogen concentration, increases the oxygen concentration, and improves the reaction rate.
Increasing the oxygen concentration at the cathode catalyst layer improves fuel cell performance while reducing nitrogen permeation to the anode side, saving materials and reducing production costs.
Smart Images
Figure CN224082435U_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fuel cell technology, and in particular to a fuel cell cell. It also relates to a corresponding fuel cell stack and a corresponding fuel cell system. Background Technology
[0002] In recent years, with the development of society and technology, people have paid increasing attention to issues such as air pollution and energy loss. A fuel cell is a highly efficient power generation device that directly converts the chemical energy in the anode and cathode gases into electrical energy through an electrochemical reaction without a combustion process. The reaction products are mainly water and virtually no harmful gases are emitted. Therefore, fuel cells have significant advantages in high energy conversion efficiency and clean environmental protection.
[0003] In a proton exchange membrane (PEM) fuel cell, hydrogen as the anode gas and air as the cathode gas are supplied to the anode and cathode sides of the fuel cell, respectively. Approximately 21% of the oxygen in the air acts as an oxidant, reacting with hydrogen to produce water, while approximately 78% of the nitrogen in the air does not participate in the electrochemical reaction. As the fuel cell operates, the oxygen on the cathode side is gradually consumed, resulting in a decrease in oxygen concentration at the cathode catalyst layer and a gradual increase in nitrogen concentration. This phenomenon becomes more pronounced closer to the downstream end of the fuel cell; for example, the oxygen molar fraction is approximately 21% near the cathode inlet manifold, while it drops to approximately 5% near the cathode exhaust manifold. This slows down the reaction rate and negatively impacts fuel cell performance. Utility Model Content
[0004] Therefore, the purpose of this invention is to provide an improved fuel cell unit that can prevent nitrogen from diffusing into the cathode catalyst layer in a cost-effective and material-saving manner, thereby significantly increasing the oxygen concentration at the cathode catalyst layer and effectively improving the reaction rate and performance of the fuel cell. The purpose of this invention also is to provide a corresponding fuel cell stack and a corresponding fuel cell system.
[0005] According to a first aspect of the present invention, a fuel cell unit is provided, wherein the fuel cell unit comprises at least:
[0006] - A membrane electrode assembly, the membrane electrode assembly having an anode gas diffusion layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer and a cathode gas diffusion layer stacked sequentially;
[0007] - An anode septum disposed on the anode side of the membrane electrode assembly, the anode septum forming a plurality of anode gas channels spaced apart from each other in the transverse direction;
[0008] - A cathode septum disposed on the cathode side of the membrane electrode assembly, the cathode septum forming a plurality of cathode gas channels spaced apart from each other along the lateral direction; and
[0009] - A nitrogen separation layer is disposed on the cathode gas diffusion layer between the cathode separator and the membrane electrode assembly, wherein the nitrogen separation layer has a plurality of nitrogen separation strips spaced apart from each other along the transverse direction, and the nitrogen separation strips are disposed only in the cathode gas channel.
[0010] Compared to existing technologies, in the fuel cell unit according to this invention, a nitrogen separation layer is arranged on the cathode gas diffusion layer between the cathode separator and the membrane electrode assembly. This nitrogen separation layer at least partially separates oxygen and nitrogen from the air in the cathode gas channel. Oxygen is allowed to flow freely through the nitrogen separation layer to the cathode gas diffusion layer and the cathode catalyst layer, while nitrogen is blocked by the nitrogen separation layer and thus at least partially retained in the cathode gas channel, exiting the fuel cell unit under the influence of airflow. This makes the diffusion of nitrogen from the air to the cathode catalyst layer more difficult and reduces the nitrogen concentration at the cathode catalyst layer, thereby correspondingly increasing the oxygen concentration at the cathode catalyst layer and effectively improving the reaction rate and performance of the fuel cell. Furthermore, by reducing the nitrogen concentration at the cathode catalyst layer, the amount of nitrogen permeating to the anode side via the proton exchange membrane is also effectively reduced, which helps to increase the hydrogen concentration at the anode catalyst layer and further improve the performance of the fuel cell. Here, the nitrogen separation layer has multiple nitrogen separation strips spaced apart from each other in the lateral direction. These nitrogen separation strips are arranged only in the cathode gas channel. This can significantly save the amount of material used in the nitrogen separation layer and reduce production costs while ensuring the nitrogen separation effect.
[0011] According to an exemplary embodiment of the present invention, when viewed in the transverse direction, the width of the nitrogen separation strip is equal to the width of the cathode gas channel.
[0012] According to an exemplary embodiment of the present invention, the nitrogen separation layer is adhered to the cathode gas diffusion layer by an adhesive.
[0013] According to an exemplary embodiment of the present invention, the nitrogen separation strips of the nitrogen separation layer are arranged independently on the cathode gas diffusion layer; or, the nitrogen separation layer includes connecting strips that connect adjacent nitrogen separation strips, so that the nitrogen separation layer is arranged integrally on the cathode gas diffusion layer.
[0014] According to an exemplary embodiment of the present invention, the nitrogen separation bar is arranged at least in the downstream region of the cathode gas channel when viewed along the flow direction of the cathode gas in the cathode gas channel.
[0015] According to an exemplary embodiment of the present invention, the nitrogen separation layer is made of a polymer material; and / or, a conductive additive is doped into the nitrogen separation layer.
[0016] According to an exemplary embodiment of the present invention, the cathode separator and the anode separator are respectively constructed as part of a corresponding bipolar plate; and / or, the anode catalyst layer, the proton exchange membrane and the cathode catalyst layer are constructed together in the form of a catalyst coating membrane.
[0017] According to a second aspect of the present invention, a fuel cell stack is provided, the fuel cell stack having a plurality of fuel cell cells according to the present invention stacked on top of each other.
[0018] According to a third aspect of the present invention, a fuel cell system is provided, wherein the fuel cell system comprises at least:
[0019] - The fuel cell stack according to this utility model;
[0020] - An anode circuit, configured to supply hydrogen to the anode side of each individual fuel cell cell in the fuel cell stack; and
[0021] - A cathode circuit, which is configured to supply air to the cathode side of each fuel cell cell in the fuel cell stack.
[0022] According to an exemplary embodiment of the present invention, the fuel cell system is configured such that the cathode gas pressure on the cathode side is greater than the anode gas pressure on the anode side.
[0023] According to an exemplary embodiment of the present invention, a gas separation device is provided upstream of the fuel cell stack in the cathode circuit, the gas separation device being configured to at least partially separate nitrogen and oxygen in the supplied air. Attached Figure Description
[0024] The present invention will now be described in more detail with reference to the accompanying drawings, which will provide a better understanding of its principles, features, and advantages. The drawings include:
[0025] Figure 1 A schematic cross-sectional view of a fuel cell cell according to an exemplary embodiment of the present invention is shown;
[0026] Figure 2A schematic view of the main extension plane of a fuel cell cell according to an exemplary embodiment of the present invention is shown;
[0027] Figure 3 A schematic connection block diagram of a fuel cell system according to an exemplary embodiment of the present invention is shown. Detailed Implementation
[0028] To make the technical problems to be solved, the technical solutions and the beneficial technical effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and several exemplary embodiments.
[0029] In this specification, unless otherwise expressly specified and limited, the terms "arrangement," "connection," and "linkage" should be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection via an intermediate component, or a connection within two components. Those skilled in the art will understand the meaning of these terms in this disclosure as appropriate.
[0030] Figure 1 A schematic cross-sectional view of a fuel cell cell 100 according to an exemplary embodiment of the present invention is shown, the cross-sectional view being perpendicular to the main extension plane of the fuel cell cell 100, the main extension plane being defined by the mutually perpendicular longitudinal direction L and transverse direction Q of the fuel cell cell 100.
[0031] like Figure 1As shown, the fuel cell unit 100 includes a membrane electrode assembly 10, which is the core component of the fuel cell unit 100. The membrane electrode assembly consists of a proton exchange membrane 11 located in the middle, an anode catalyst layer 12 and a cathode catalyst layer 13 respectively arranged on both sides of the proton exchange membrane 11, and an anode gas diffusion layer 14 and a cathode gas diffusion layer 15. These layers are stacked on top of each other along the thickness direction H. During normal operation of the fuel cell, hydrogen gas is supplied as the anode gas to the anode of the membrane electrode assembly 10. It passes through the anode gas diffusion layer 14 to reach the anode catalyst layer 12 and decomposes into hydrogen ions under the catalysis of the anode catalyst, such as platinum, releasing two electrons. The hydrogen ions then pass through the proton exchange membrane 11 to reach the cathode. Air is supplied as the cathode gas to the cathode of the membrane electrode assembly 10. Oxygen in the air passes through the cathode gas diffusion layer 15 to reach the cathode catalyst layer 13. The hydrogen ions react with oxygen under the catalysis of the cathode catalyst, such as platinum, to generate water, and the released electrons form an electric current in the external circuit. In particular, the anode catalyst layer 12, the proton exchange membrane 11, and the cathode catalyst layer 13 are constructed together in the form of a catalyst coated membrane (CCM) to reduce the thickness of the membrane electrode assembly 10 and improve catalytic efficiency. Here, the anode gas diffusion layer 14 and the cathode gas diffusion layer 15 can be applied to the anode side and the cathode side of the membrane electrode assembly 10, respectively, by hot pressing or bonding processes, with the anode side and the cathode side facing away from each other.
[0032] like Figure 1 As shown, the fuel cell unit 100 includes an anode partition 20 arranged on the anode side of the membrane electrode assembly 10. The anode partition forms a plurality of anode gas channels 21 spaced apart from each other in the lateral direction Q. The anode gas channels lead to the anode gas diffusion layer 14 to achieve uniform distribution of hydrogen on the anode catalyst layer 12.
[0033] like Figure 1 As shown, the fuel cell unit 100 includes a cathode separator 30 arranged on the cathode side of the membrane electrode assembly 10. The cathode separator forms a plurality of cathode gas channels 31 spaced apart from each other in the lateral direction Q. The cathode gas channels lead to the cathode gas diffusion layer 15 to achieve uniform distribution of oxygen on the cathode catalyst layer 13.
[0034] For example, such as Figure 1 As shown, the cathode separator 30 and the anode separator 20 are respectively constructed as part of the corresponding bipolar plate 40, so that two adjacent fuel cell cells 100 can share the same bipolar plate 40. The bipolar plate can be constructed by welding the anode separator 20 and the cathode separator 30 to form an anode gas channel 21, a cathode gas channel 31 and a cooling water channel 41.
[0035] like Figure 1 As shown, the fuel cell unit 100 also includes a nitrogen separation layer 50, which is arranged on the cathode gas diffusion layer 15 between the cathode separator 30 and the membrane electrode assembly 10. Here, due to the gas selectivity of the nitrogen separation layer 50, oxygen in the air can more easily permeate through the nitrogen separation layer 50, while at least most of the nitrogen in the air is blocked by the nitrogen separation layer 50, thereby achieving at least partial separation of oxygen and nitrogen. This reliably prevents nitrogen in the cathode gas channel 31 from permeating through the nitrogen separation layer 50 to the cathode gas diffusion layer 15, thereby correspondingly increasing the oxygen concentration at the cathode catalyst layer 13 and also reducing to some extent the nitrogen permeating to the anode side via the proton exchange membrane 11, thus effectively improving the reaction rate and performance of the fuel cell unit 100. Here, the nitrogen separation layer 50 has a plurality of nitrogen separation strips 51 spaced apart from each other in the lateral direction Q, which are arranged only in the cathode gas channel 31. In this configuration, the nitrogen separation strip 51 is only arranged in the area through which air flows, and not in the contact area between the cathode separator 30 and the cathode gas diffusion layer 15, where no air exists. This significantly reduces the material usage of the nitrogen separation layer 50 while ensuring effective nitrogen separation, thereby lowering production costs. Furthermore, compared to applying the nitrogen separation membrane comprehensively to the cathode gas diffusion layer 15, the arrangement of the nitrogen separation strip 51 only in the cathode gas channel 31 can also reduce the overall thickness of the fuel cell unit 100 to some extent.
[0036] For example, such as Figure 1 As shown, viewed along the transverse direction Q, the width of the nitrogen separation strip 51 is equal to the width of the cathode gas channel 31, ensuring that the communication area between the cathode gas channel 31 and the cathode gas diffusion layer 15 is completely covered by the nitrogen separation strip 51 in the transverse direction Q. This effectively prevents nitrogen leakage into the cathode gas diffusion layer 15. Here, the cathode gas channels 31 are spaced apart from each other by the partition walls 32 of the cathode partition 30, forming cooling water channels 41. The distance between adjacent nitrogen separation strips 51 is substantially equivalent to the width of the cooling water channels 41.
[0037] Exemplarily, the nitrogen separation layer 50 can be made of a polymer material, such as selected from the group consisting of polysulfone (PSf), polyamide (PA), polyurethane (PU), polydimethylsiloxane, polyimide (PI), and polyaniline (PANi). Other polymer materials that may be considered meaningful by those skilled in the art are also acceptable. Here, the nitrogen separation layer 50 is constructed in the form of a flat sheet membrane, for example, by processes such as solution casting or phase inversion.
[0038] For example, a conductive additive, such as carbon nanotubes, is doped into the nitrogen separation layer 50. This conductive additive advantageously enhances the conductivity of the nitrogen separation layer 50 and improves the performance of the fuel cell unit 100.
[0039] Figure 2 A schematic view of the main extension plane of a fuel cell cell 100 according to an exemplary embodiment of the present invention is shown.
[0040] For example, such as Figure 2 As shown, the nitrogen separation layer 50 includes connecting strips 52 that connect adjacent nitrogen separation strips 51, allowing the nitrogen separation layer 50 to be integrally arranged on the cathode gas diffusion layer 15. This simplifies the assembly process of the nitrogen separation layer 50. Here, the connecting strips 52 are located particularly outside the cathode separator 30 of the fuel cell unit 100 to avoid affecting the installation of the cathode separator 30. However, it is also possible that the individual nitrogen separation strips 51 of the nitrogen separation layer 50 are arranged independently on the cathode gas diffusion layer 15. In this case, the spacing between adjacent nitrogen separation strips 51 needs to be specifically set. Here, the individual nitrogen separation strips 51 of the nitrogen separation layer 50 are adhered to the cathode gas diffusion layer 15, particularly by means of adhesive.
[0041] For example, such as Figure 2 As shown, looking along the flow direction F of the cathode gas in the cathode gas channel 31, the nitrogen separation strip 51 is arranged at least in the downstream region of the cathode gas channel 31, particularly in the middle and downstream regions of the cathode gas channel 31, but not in the upstream region of the cathode gas channel 31. Here, the flow direction F is at least substantially parallel to the longitudinal direction L of the fuel cell unit 100. Within the framework of this invention, "upstream region" should be understood as the first third of the region of the cathode gas channel 31 along the flow direction F, "middle region" should be understood as the first third to two-thirds of the region of the cathode gas channel 31 along the flow direction F, and "downstream region" should be understood as the last third of the region of the cathode gas channel 31 along the flow direction F. In the upstream region of the cathode gas channel 31, nitrogen in the air does not accumulate excessively and permeate into the cathode catalyst layer 13. Therefore, the arrangement of the nitrogen separation strip 51 in this upstream region can be eliminated without significantly reducing the oxygen concentration at the cathode catalyst layer 13. This can minimize the material consumption of the nitrogen separation layer 50 while ensuring the reaction rate of the fuel cell unit 100.
[0042] Figure 3 A schematic connection block diagram of a fuel cell system 1000 according to an exemplary embodiment of the present invention is shown.
[0043] like Figure 3As shown, the fuel cell system 1000 includes a fuel cell stack 1 according to the present invention, the fuel cell stack having a plurality of stacked fuel cell cells 100 according to the present invention, the fuel cell cells being clamped by end plates and sealed by seals. Here, the fuel cell stack 1 is the core of the entire fuel cell system 1000.
[0044] like Figure 3 As shown, the fuel cell system 1000 includes an anode circuit 2, which is configured to supply hydrogen, which serves as the anode gas, to the anode side of each fuel cell cell 100 in the fuel cell stack 1. The anode circuit 2 includes, for example, a high-pressure hydrogen storage tank 201 and a hydrogen circulation pump 202. The hydrogen circulation pump can guide the anode exhaust gas discharged from the fuel cell stack 1 back to the fuel cell stack 1 to improve the hydrogen utilization rate.
[0045] like Figure 3 As shown, the fuel cell system 1000 includes a cathode circuit 3, which is configured to supply air, for example, via an air compressor 301, to the cathode side of each fuel cell cell 100 in the fuel cell stack 1. Specifically, a gas separator 302 is provided upstream of the fuel cell stack 1 in the cathode circuit 3. This gas separator is capable of separating nitrogen and oxygen in the supplied air, thereby reducing the nitrogen content in the cathode gas beforehand and thus lowering the pressure of the nitrogen separation layer 50. Here, the gas separator 302 is, for example, provided with a hollow fiber membrane or a carbon molecular sieve.
[0046] For example, the fuel cell system 1000 is configured such that the cathode gas pressure supplied to the cathode side through the cathode circuit 3 is greater than the anode gas pressure supplied to the anode side through the anode circuit 2, so as to promote the nitrogen separation process based on the nitrogen separation layer 50.
[0047] The foregoing description of the embodiments is limited to the framework of the examples described herein. Of course, the various features of the embodiments can be freely combined with each other without departing from the framework of this invention, as long as it is technically meaningful.
[0048] Other advantages and alternative embodiments of this invention will be apparent to those skilled in the art. Therefore, this invention is not, in its broader sense, limited to the specific details, representative structures, and exemplary embodiments shown and described. Rather, those skilled in the art can make various modifications and substitutions without departing from the basic spirit and scope of this invention.
Claims
1. A fuel cell unit (100) characterized by, The fuel cell element (100) comprises at least: - a membrane electrode assembly (10) having, in succession, an anode gas diffusion layer (14), an anode catalyst layer (12), a proton exchange membrane (11), a cathode catalyst layer (13), and a cathode gas diffusion layer (15); - an anode separator plate (20) arranged on the anode side of the membrane electrode assembly (10), the anode separator plate (20) forming a plurality of anode gas channels (21) spaced apart from one another along a transverse direction (Q); - a cathode separator plate (30) arranged on the cathode side of the membrane electrode assembly (10), the cathode separator plate (30) forming a plurality of cathode gas channels (31) spaced apart from one another along the transverse direction (Q); and - a nitrogen separation layer (50) arranged on the cathode gas diffusion layer (15) between the cathode separator plate (30) and the membrane electrode assembly (10), wherein the nitrogen separation layer (50) has a plurality of nitrogen separation strips (51) spaced apart from one another along the transverse direction (Q), the nitrogen separation strips (51) being arranged only in the cathode gas channels (31).
2. The fuel cell element (100) according to claim 1, characterized in that the width of the nitrogen separation strips (51) is equal to the width of the cathode gas channels (31) as seen along the transverse direction (Q).
3. The fuel cell element (100) according to claim 1 or 2, characterized in that the nitrogen separation layer (50) is adhered to the cathode gas diffusion layer (15) by means of an adhesive.
4. The fuel cell element (100) according to claim 1 or 2, characterized in that the individual nitrogen separation strips (51) of the nitrogen separation layer (50) are arranged on the cathode gas diffusion layer (15) in a mutually independent manner; or the nitrogen separation layer (50) comprises connecting strips (52) connecting adjacent nitrogen separation strips (51) such that the nitrogen separation layer (50) is arranged on the cathode gas diffusion layer (15) in one piece.
5. The fuel cell element (100) according to claim 1 or 2, characterized in that the nitrogen separation strips (51) are arranged at least in a downstream region of the cathode gas channels (31) as seen along the flow direction (F) of the cathode gas in the cathode gas channels (31).
6. The fuel cell element (100) according to claim 1 or 2, characterized in that the nitrogen separation layer (50) is made of a polymeric material; and / or an electrically conductive auxiliary agent is doped in the nitrogen separation layer (50); and / or the cathode separator plate (30) and the anode separator plate (20) are respectively configured as part of a respective bipolar plate (40); and / or the anode catalyst layer (12), the proton exchange membrane (11), and the cathode catalyst layer (13) are collectively configured in the form of a catalyst-coated membrane.
7. A fuel cell stack (1) having a plurality of fuel cell units (100) according to any one of claims 1 to 6 stacked on top of each other.
8. A fuel cell system (1000) characterized by comprising: The fuel cell system (1000) comprises at least: - a fuel cell stack (1) according to claim 7; - an anode circuit (2) configured and adapted to supply hydrogen gas to the anode side of each fuel cell unit (100) of the fuel cell stack (1); and - a cathode circuit (3) configured and adapted to supply air to the cathode side of each fuel cell unit (100) of the fuel cell stack (1).
9. The fuel cell system (1000) according to claim 8, characterized in that the fuel cell system (1000) is configured such that the cathode gas pressure at the cathode side is greater than the anode gas pressure at the anode side.
10. The fuel cell system (1000) according to claim 8 or 9, characterized in that a gas separation device (302) is provided in the cathode circuit (3) upstream of the fuel cell stack (1), the gas separation device (302) being configured and adapted to at least partially separate nitrogen from oxygen in the supplied air.