Membrane electrode assembly wetting method and computer readable storage medium
By using water vapor to heat and condense the membrane electrode assembly, the problem of slow and high cost in the prior art PEMFC wetting process is solved, and a fast and economical wetting effect of membrane electrode assembly is achieved.
Patent Information
- Application Number
- CN202311605344.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-28
- Publication Date
- 2025-05-30
AI Technical Summary
In the prior art, the wetting process of membrane electrode assembly (MEA) in proton exchange membrane fuel cell (PEMFC) is slow and costly, making it difficult to quickly achieve optimal working performance.
The membrane electrode assembly is wetted by water vapor. The specific steps include heating the membrane electrode assembly to the water vapor temperature, guiding the water vapor through the gas diffusion layer to the catalyst coated film after heating, and condensing the water vapor into liquid water through a coolant.
The rapid wetting of membrane electrode assembly is achieved, shortening wetting time and reducing wetting costs without combining with the discharge process.
Smart Images
Figure CN120072976A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of proton exchange membrane fuel cells (PEMFCs), and more particularly to a method for wetting a membrane electrode assembly (MEA) in a PEMFC during an activation stage. Background Art
[0002] The membrane electrode assembly (MEA) is the core component of a proton exchange membrane fuel cell (PEMFC), and its performance largely determines the performance of the PEMFC. The performance of several main components of the MEA (gas diffusion layer, catalyst layer, and proton exchange membrane) and the manufacturing process of the MEA have a great impact on its performance. In addition, in order for the PEMFC to quickly reach its optimal operating performance after starting to work, before the prepared PEMFC is delivered to end users for use, it is usually necessary to perform an activation treatment on it. An important purpose of PEMFC activation is to wet the MEA to ensure good ionic conductivity, thereby improving the output performance of the fuel cell.
[0003] In the prior art, at least one of a pre-activation method and a discharge activation method is usually used to treat a PEMFC to increase the water content of the MEA. During the pre-activation process, the PEMFC is treated by boiling the MEA in boiling water, injecting water into the PEMFC, or soaking and wetting, etc., but the activation effect is generally average. During the discharge activation process, the water generated by the reaction of the anode gas (usually hydrogen) and the cathode gas (usually air) gradually wets the MEA. At the same time, the active sites of the catalyst are improved, and the overall resistance of the stack is reduced. However, the discharge activation process takes a long time and consumes a large amount of hydrogen, making its cost relatively high.
[0004] To solve one or more problems existing in the prior art, the present disclosure proposes a method for wetting an MEA. Summary of the Invention
[0005] The method for wetting an MEA proposed by the present disclosure can achieve rapid wetting of the MEA, especially its catalyst-coated membrane (CCM). In addition, this method can be used alone and does not need to be combined with a discharge process (i.e., current / voltage cycling) to achieve effective wetting of the CCM, thereby shortening the wetting time and saving the wetting cost.
[0006] Specifically, the present disclosure proposes a method for wetting a membrane electrode assembly, where the membrane electrode assembly includes: a catalyst coated membrane; and an anode gas diffusion layer and a cathode gas diffusion layer respectively located on both sides of the catalyst coated membrane. Among them, the method for wetting the membrane electrode assembly uses water vapor to wet the membrane electrode assembly, and includes: Step 102: Heating the membrane electrode assembly to a temperature greater than or equal to that of the water vapor; Step 104: Guiding the water vapor to both sides of the membrane electrode assembly so that the water vapor penetrates through the anode gas diffusion layer and the cathode gas diffusion layer to reach the catalyst coated membrane; and Step 106: Flowing a coolant through both sides of the membrane electrode assembly so that the water vapor reaching the catalyst coated membrane condenses into liquid water.
[0007] In one embodiment, during Step 106, the water vapor in Step 104 is continuously guided to both sides of the membrane electrode assembly.
[0008] In one embodiment, the water vapor used in the method for wetting the membrane electrode assembly is saturated water vapor.
[0009] In one embodiment, in Step 102, the membrane electrode assembly is heated using saturated water vapor.
[0010] In one embodiment, the saturated water vapor used in Step 102 and the water vapor used in Step 104 come from the same water vapor source.
[0011] In one embodiment, the saturated water vapor used in Step 102 and the water vapor used in Step 104 have the same temperature.
[0012] In one embodiment, in Step 106, the coolant flows through both sides of the membrane electrode assembly at regular time intervals.
[0013] In one embodiment, the coolant flows through both sides of the membrane electrode assembly at regular time intervals.
[0014] In one embodiment, first and second electrode plates are respectively formed on both sides of the membrane electrode assembly. An anode gas channel for anode gas to flow into the membrane electrode assembly and a coolant channel are formed in the first electrode plate, and a cathode gas channel for cathode gas to flow into the membrane electrode assembly and a coolant channel are formed in the second electrode plate. Among them, in Step 102, the membrane electrode assembly is heated by introducing saturated water vapor into at least one of the anode gas channel and the coolant channel of the first electrode plate and the cathode gas channel and the coolant channel of the second electrode plate.
[0015] In one embodiment, in step 104, the water vapor is introduced into the anode gas channel of the first bipolar plate and the cathode gas channel of the second bipolar plate, so that the water vapor penetrates through the anode gas diffusion layer and the cathode gas diffusion layer to reach the catalyst coated membrane.
[0016] In one embodiment, in step 106, the coolant is made to flow through the coolant channels of the first bipolar plate and the second bipolar plate, so that the water vapor reaching the catalyst coated membrane condenses into liquid water.
[0017] In one embodiment, in step 102, the membrane electrode assembly is heated to 100 - 105 °C; in step 104, the water vapor is continuously introduced into the anode gas channel of the first bipolar plate and the cathode gas channel of the second bipolar plate for 10 minutes; and in step 106, the coolant at 80 °C is made to flow through the coolant channels of the first bipolar plate and the second bipolar plate for 30 seconds and then stopped for 30 seconds, and then the coolant is made to flow through the coolant channels again, and this cycle is repeated 15 times.
[0018] In one embodiment, the method for wetting the membrane electrode assembly further includes: applying a partial vacuum condition to the saturated water vapor to make its temperature lower than 100 °C.
[0019] In one embodiment, the coolant includes deionized water.
[0020] The present disclosure also provides a computer-readable storage medium, on which a program is stored, the program includes instructions, when the instructions are executed by a processor, the processor is made to execute the method for wetting the membrane electrode assembly according to any one of the above.
[0021] Generally speaking, the various embodiments of the present disclosure can be combined and coupled in any possible way within the scope of the present disclosure. These and other aspects, features and / or advantages of the present disclosure will be apparent and elucidated with reference to the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The embodiments of the present disclosure will be described by way of example with reference to the following drawings, in which:
[0023] Figure 1 A cross-sectional schematic diagram of a conventional proton exchange membrane fuel cell in the art is shown, in which the MEA wetting method according to the embodiments of the present disclosure can be implemented;
[0024] Figure 2 A flowchart of the MEA wetting method according to an embodiment of the present disclosure is shown; and
[0025] Figure 3A graph showing the relationship between the pressure and temperature of saturated water vapor is shown.
[0026] It should be understood that the drawings only show one way of implementing the present disclosure and should not be construed as limiting other possible embodiments falling within the scope of the appended claims. Detailed Description of the Invention
[0027] Figure 1 A cross-sectional schematic diagram of a conventional proton exchange membrane fuel cell in the art is shown, in which the MEA wetting method according to the embodiments of the present disclosure can be implemented. The following will refer to Figure 1 The structure of the proton exchange membrane fuel cell will be described in detail.
[0028] As Figure 1 shown, the proton exchange membrane fuel cell generally includes a proton exchange membrane 1 at the center, an anode catalyst layer 2 and a cathode catalyst layer 3 on both sides of the proton exchange membrane 1, an anode gas diffusion layer 4 and a cathode gas diffusion layer 5 outside the catalyst layer, and a first bipolar plate 6 and a second bipolar plate 7 outside the gas diffusion layer. Among them, the proton exchange membrane 1, the anode catalyst layer 2 and the cathode catalyst layer 3 together constitute the above-mentioned catalyst coated membrane CCM 8, and the CCM 8 and the anode gas diffusion layer 4 and the cathode gas diffusion layer 5 together constitute the above-mentioned membrane electrode assembly MEA 9.
[0029] Those skilled in the art will understand that additional MEAs (not shown in the figure) can be arranged on the upper side of the first bipolar plate 6 and the lower side of the second bipolar plate 7 to form a fuel cell stack including a plurality of fuel cell monomers. The MEA wetting method according to the present disclosure can be implemented in any one of the plurality of fuel cell monomers. Those skilled in the art will also understand that for the fuel cell monomer at the uppermost side of the fuel cell stack, the first bipolar plate 6 can be an end plate, and for the fuel cell monomer at the lowermost side of the fuel cell, the second bipolar plate 7 can be an end plate. The above bipolar plates 6, 7 and end plates can be collectively referred to as plates.
[0030] The first bipolar plate 6 and the second bipolar plate 7 may have the same structure and are generally formed by welding two thin plates 6a and 6b, 7a and 7b with a cross-section in a wavy shape or a city wall shape. Thus, a cathode gas channel 10 is formed on the upper side of the first thin plates 6a, 7a, an anode gas channel 11 is formed on the lower side of the second thin plates 6b, 7b, and a coolant channel 12 is formed between the first thin plates 6a, 7a and the second thin plates 6b, 7b. The cathode gas channel 10 is used to supply a cathode gas such as compressed air to the MEA 9, and the anode gas channel 11 is used to supply an anode gas such as hydrogen to the MEA 9, so that oxygen and hydrogen undergo an electrochemical reaction in the MEA 9 to generate electric energy. The coolant channel 12 is used for a coolant such as water to flow through to take away a large amount of heat generated by the above electrochemical reaction.
[0031] The above-mentioned proton exchange membrane 1 is generally composed of a perfluorosulfonic acid (PFSA) ionomer, which is essentially a copolymer of tetrafluoroethylene (TFE) and different perfluorosulfonic acid monomers. Well-known membrane materials include the Nafion membrane produced by DuPont, the Dow Chemical Gore membrane, the Dongyue membrane, etc. The water content of the polymer membrane is usually expressed as the number of grams of water contained in each gram of the dry polymer membrane, or as the number of water molecules present in each sulfonic acid group of the polymer. According to the Schroeder paradox, compared with the gaseous environment, Figure 1 the CCM 8 in [the relevant context] can absorb more water in a shorter water balance time in the liquid environment. One explanation for the difference in water absorption between the gaseous environment and the liquid environment is that the water absorption in the gaseous environment includes condensed water inside the polymer, mostly located on the strongly hydrophobic polymer backbone, resulting in less water absorption than directly absorbing water from the liquid environment. According to relevant articles, the water absorption of the membrane in liquid water for 48 hours is 1139% of the dry membrane, while the water absorption of the membrane in gaseous water for 20 days is only 41.4% of the dry membrane.
[0032] In addition, the anode gas diffusion layer 4 and the cathode gas diffusion layer 5 covering both sides of the CCM 8 as key functional components of the MEA 9 are generally hydrophobic, so they will prevent liquid water from penetrating through them to the inner CCM 8. Therefore, when pumping liquid water or a gas containing liquid water into the cathode gas channel 10 and the anode gas channel 11, the liquid water therein will be difficult to penetrate through the anode gas diffusion layer 4 and the cathode gas diffusion layer 5 to reach the CCM 8.
[0033] Based on the above premises, the present disclosure proposes a novel MEA wetting method. The key point of this method lies in introducing gaseous water into the cathode gas channel 10 and the anode gas channel 11. After the gaseous water successfully penetrates the anode gas diffusion layer 4 and the cathode gas diffusion layer 5 to reach the CCM 8, the gaseous water is cooled to condense it. In this way, the obtained liquid water will be able to be absorbed more by the CCM 8 within a shorter water balance time, so that the CCM 8 reaches a good wetting state. The above method includes the phase change process of water from gaseous to liquid, which can avoid the hydrophobic defects of the gas diffusion layers 4 and 5 (in terms of wetting) through gaseous water, and can also enable the CCM 8 to reach a better wetting state in a liquid water environment.
[0034] Specifically, Figure 2 shows a flowchart of an MEA wetting method according to an embodiment of the present disclosure. As described above, the MEA forms part of a PEMFC. This method uses water vapor to wet the MEA, which reduces the cost compared to using nitrogen containing water vapor, etc. To improve the wetting effect, this method preferably uses saturated water vapor to wet the MEA. Referring to Figure 2 , the MEA wetting method according to the present disclosure includes steps 102-106.
[0035] In step 102, the MEA is heated to a temperature greater than or equal to the temperature of the above-mentioned saturated water vapor. In the case where the MEA forms part of a PEMFC, the PEMFC is heated to a temperature greater than or equal to the temperature of the above-mentioned saturated water vapor. The purpose of step 102 is to prevent the saturated water vapor subsequently introduced into the PEMFC from condensing before penetrating the gas diffusion layer, which will be further described in detail below.
[0036] Next, in step 104, the saturated water vapor is guided to both sides of the MEA 9, so that the saturated water vapor can pass through the anode gas diffusion layer 4 and the cathode gas diffusion layer 5 of the MEA 9 and reach the CCM 8. Specifically, guiding the saturated water vapor to both sides of the MEA 9 includes introducing the saturated water vapor into the gas channels 10 and 11 of the first bipolar plate 6 and the second bipolar plate 7, so that the saturated water vapor can penetrate the gas diffusion layers 4 and 5 from the gas channels 10 and 11 and reach the CCM 8.
[0037] Then, in step 106, the coolant is made to flow through both sides of the MEA 9, causing the saturated water vapor reaching the CCM 8 to condense into liquid water, so as to form a liquid water environment at the CCM. Thus, the CCM 8 can quickly absorb more water from the liquid water environment. The above-mentioned coolant can be deionized water or any other suitable type of coolant. In a preferred embodiment according to the present disclosure, during the flow of the coolant, the saturated water vapor in step 104 is continuously guided to both sides of the MEA 9, so that continuously saturated water vapor reaches the CCM 8 and is condensed into liquid water. In a further preferred embodiment, the coolant can flow through both sides of the MEA 9 at certain time intervals, and further the coolant can flow through both sides of the MEA 9 at regular time intervals. That is to say, the coolant is not continuously flowing through the MEA 9, but stops for a period of time after flowing for a certain time, and then flows through both sides of the MEA 9 again, repeating this cycle many times. Among them, during the above-mentioned flow of the coolant, not only the water vapor at the CCM 8 will condense into liquid water to be absorbed by the CCM 8, but also a part of the water vapor in the gas channel will condense into liquid water in the channel. This part of the liquid water gradually accumulates, posing a risk of blocking the gas channel. Therefore, during the above-mentioned period when the coolant flow stops, the water vapor continuously introduced into the gas channel can purge the liquid water therein, thus avoiding the blockage of the gas channel.
[0038] In step 102, the MEA 9 can be heated by any suitable method. In one embodiment, the PEMFC can be placed in a high-temperature chamber for a period of time to reach a higher temperature. In another embodiment, since the temperature of saturated water vapor reaches 100 °C under ambient pressure, saturated water vapor can also be used to heat the PEFMC. In this case, the PEMFC is brought to a higher temperature by continuously introducing high-temperature saturated water vapor into the gas channels and / or coolant channels in the first bipolar plate 6 and the second bipolar plate 7. Since the initial temperature of the PEMFC is relatively low, when the high-temperature saturated water vapor is introduced, a certain amount of condensed water will be generated in the PEMFC initially. However, it should be understood that since the water vapor is continuously introduced, the generated condensed water will be carried away by the subsequent introduced water vapor and will not block the gas channels and / or coolant channels.
[0039] In a preferred embodiment, the saturated water vapor used in step 102 and the saturated water vapor used in step 104 may come from the same water vapor source. Further, the temperatures of the saturated water vapor used in step 102 and the saturated water vapor used in step 104 may be equal. In this case, the PEMFC can be heated to a temperature greater than or equal to the temperature of the saturated water vapor used in step 104, which can not only prevent the water vapor introduced in step 104 from condensing, but also reduce the number of devices required to implement the MEA wetting method according to the present disclosure, thereby reducing the implementation cost.
[0040] In a specific embodiment according to the present disclosure, in step 102, saturated water vapor is introduced into at least one of the gas channels and the coolant channels of the PEMFC to heat the PEMFC to 100 - 105 °C. Then, in step 104, saturated water vapor is continuously introduced into the gas channel for a certain period of time, such as 10 minutes, so that the saturated water vapor penetrates through the gas diffusion layer to reach the CCM 8. Next, in step 106, deionized water at about 80 °C is made to flow through the coolant channels 12 of the first bipolar plate 6 and the second bipolar plate 7 of the PEMFC for 30 seconds and then stopped for 30 seconds, and then the deionized water is made to flow through the coolant channels 12 again. This cycle is repeated 15 times to bring the PEMFC to a good wetting state. Those skilled in the art will understand that the heating temperature of the PEMFC, the temperature of the saturated water vapor, and the temperature of the coolant can be adjusted, and the flow duration and cycle of the water vapor and the coolant can also be adjusted to achieve the desired wetting effect.
[0041] Figure 3 A graph showing the relationship between the pressure and temperature of saturated water vapor is presented, and its general trend is that the higher the pressure of saturated water vapor, the higher the temperature. As Figure 3 shown, at an atmospheric pressure of 100 KPa, the temperature of saturated water vapor is 100 °C. In an embodiment according to the present disclosure, a partial vacuum condition can be applied to the saturated water vapor so that its temperature is lower than 100 °C. Thus, saturated water vapor below 100 °C can be used to wet the MEA, which helps to reduce the energy consumption for implementing the MEA wetting method according to the present disclosure.
[0042] The MEA wetting method of any of the above-described embodiments can effectively wet the MEA alone without the need to be combined with the commonly used discharge activation in the art subsequently, thereby shortening the wetting time and saving the wetting cost.
[0043] According to another embodiment of the present disclosure, a computer-readable storage medium is also proposed. A program is stored on this computer-readable storage medium. The program includes instructions, and when the instructions are executed by a processor, the processor is made to execute the membrane electrode assembly wetting method described in any of the above embodiments.
[0044] Although the present disclosure has been described in connection with the above specific embodiments, it should not be construed as being limited in any way to the presented examples. The scope of the present disclosure is defined by the appended claims. In the context of the claims, the term "comprising" or "including" does not exclude other possible elements or steps. Additionally, references such as "a" or "an" should not be construed as excluding a plurality. The use of reference signs of elements shown in the drawings in the claims should also not be construed as limiting the scope of the present disclosure. Furthermore, the various features mentioned in different claims may be advantageously combined, and the mention of these features in different claims does not exclude the combination of these features from being possible and advantageous. Moreover, the "first", "second", "third", etc. used in the present disclosure are merely used to distinguish the relevant components from each other and are not intended to confer any priority-related attributes on them.
Claims
1. A method for wetting a membrane electrode assembly, the membrane electrode assembly comprising: a catalyst coated membrane (8); and an anode gas diffusion layer (4) and a cathode gas diffusion layer (5) respectively located on both sides of the catalyst coated membrane (8), characterized in that the method for wetting the membrane electrode assembly uses water vapor to wet the membrane electrode assembly, and comprises: Step 102: Heating the membrane electrode assembly to a temperature greater than or equal to that of the water vapor; Step 104: Guiding the water vapor to both sides of the membrane electrode assembly so that the water vapor penetrates through the anode gas diffusion layer (4) and the cathode gas diffusion layer (5) to reach the catalyst coated membrane (8); and Step 106: Flowing a coolant through both sides of the membrane electrode assembly so that the water vapor reaching the catalyst coated membrane (8) condenses into liquid water.
2. The method for wetting a membrane electrode assembly according to claim 1, characterized in that during Step 106, the water vapor in Step 104 is continuously guided to both sides of the membrane electrode assembly.
3. The method for wetting a membrane electrode assembly according to claim 1, characterized in that the water vapor used in the method for wetting the membrane electrode assembly is saturated water vapor.
4. The method for wetting a membrane electrode assembly according to any one of claims 1-3, characterized in that in Step 102, the membrane electrode assembly is heated using saturated water vapor.
5. The method for wetting a membrane electrode assembly according to claim 4, characterized in that the saturated water vapor used in Step 102 and the water vapor used in Step 104 are from the same water vapor source.
6. The method for wetting a membrane electrode assembly according to claim 5, characterized in that the saturated water vapor used in Step 102 and the water vapor used in Step 104 have the same temperature.
7. The method for wetting a membrane electrode assembly according to any one of claims 1-3, characterized in that in Step 106, the coolant flows through both sides of the membrane electrode assembly at regular time intervals.
8. The method for wetting a membrane electrode assembly according to claim 7, characterized in that the coolant flows through both sides of the membrane electrode assembly at regular time intervals.
9. The method for wetting a membrane electrode assembly according to any one of claims 1-3, characterized in that first electrode plates (6) and second electrode plates (7) are respectively formed on both sides of the membrane electrode assembly. An anode gas channel for anode gas to flow into the membrane electrode assembly and a coolant channel are formed in the first electrode plate (6), and a cathode gas channel for cathode gas to flow into the membrane electrode assembly and a coolant channel are formed in the second electrode plate (7). Wherein, in Step 102, the membrane electrode assembly is heated by introducing saturated water vapor into at least one of the anode gas channel and the coolant channel of the first electrode plate (6) and the cathode gas channel and the coolant channel of the second electrode plate (7).
10. The method for wetting a membrane electrode assembly according to claim 9, characterized in that In step 104, the water vapor is introduced into the anode gas channel of the first plate (6) and the cathode gas channel of the second plate (7) so that the water vapor penetrates through the anode gas diffusion layer (4) and the cathode gas diffusion layer (5) to reach the catalyst coated membrane (8).
11. The method for wetting a membrane electrode assembly according to claim 10, wherein, in step 106, the coolant is made to flow through the coolant channels of the first plate (6) and the second plate (7) so that the water vapor reaching the catalyst coated membrane (8) condenses into liquid water.
12. The method for wetting a membrane electrode assembly according to claim 11, wherein, in step 102, the membrane electrode assembly is heated to 100 - 105 °C; in step 104, the water vapor is continuously introduced into the anode gas channel of the first plate (6) and the cathode gas channel of the second plate (7) for 10 minutes; and in step 106, the coolant at 80 °C is made to flow through the coolant channels of the first plate (6) and the second plate (7) for 30 seconds and then stopped for 30 seconds, and then the coolant is made to flow through the coolant channels again, and this cycle is repeated 15 times.
13. The method for wetting a membrane electrode assembly according to any one of claims 1 - 3, wherein, the method for wetting the membrane electrode assembly further includes: applying a partial vacuum condition to the saturated water vapor to make its temperature lower than 100 °C.
14. The method for wetting a membrane electrode assembly according to any one of claims 1 - 3, wherein, the coolant includes deionized water.
15. A computer - readable storage medium having a program stored thereon, the program including instructions which, when executed by a processor, cause the processor to execute the method for wetting a membrane electrode assembly according to any one of claims 1 - 14.