Gas diffusion layer, method of making, electrode, and battery

Abstract

The application discloses a kind of gas diffusion layer and preparation method, electrode and battery, it is related to battery technical field, to solve the problem that existing microporous layer is easy to drop powder after high-temperature sintering.The gas diffusion layer includes support layer and microporous layer formed on the surface of the support layer, and the microporous layer contains at least hydroxyl-terminated polyester resin and curing agent.The preparation method is used to prepare the gas diffusion layer, and the electrode uses the gas diffusion layer, and the battery uses the gas diffusion layer.The gas diffusion layer and preparation method, electrode and battery provided by the application are used to improve the bonding strength of microporous layer and support layer, reduce the surface defects of microporous layer, and improve the water vapor heat transfer efficiency.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a gas diffusion layer and its preparation method, an electrode, and a battery. Background Technology

[0002] The gas diffusion layer (GDL) is an important component of the membrane electrode assembly (MEA) of a fuel cell. It is typically composed of support layers (SL) and a microporous layer (MPL). Its main functions are to collect current, transfer gas, and remove water produced by electrochemical reactions, providing a channel for water-gas-heat transfer for the electrode reaction.

[0003] Currently, conventional microporous layers are generally composed of carbon materials and polytetrafluoroethylene (PTFE). The microporous layer mainly relies on PTFE for bonding. However, the microporous layer is prone to powdering after high-temperature sintering. When it is assembled into membrane electrodes and batteries, the microporous layer is more likely to fall off under pressure, leading to failure of water vapor heat transfer. Summary of the Invention

[0004] The purpose of this invention is to provide a gas diffusion layer and its preparation method, an electrode and a battery, which improves the bonding strength between the microporous layer and the support layer, reduces surface defects in the microporous layer and improves the water vapor heat transfer efficiency.

[0005] In a first aspect, the present invention provides a gas diffusion layer comprising a support layer and a microporous layer formed on the surface of the support layer, the microporous layer containing at least a hydroxyl-terminated polyester resin and a curing agent.

[0006] Compared with the prior art, the gas diffusion layer provided by the present invention has the following advantages:

[0007] The gas diffusion layer provided in this invention includes a support layer and a microporous layer formed on the surface of the support layer. When the microporous layer contains at least a hydroxyl-terminated polyester resin and a curing agent, due to chemical action, the functional groups in the curing agent can react with the hydroxyl groups in the hydroxyl-terminated polyester resin and connect through chemical bonds to form a cross-linked network structure with a high cross-linking density. This improves the bonding strength between the hydroxyl-terminated polyester resin and the curing agent, reduces the possibility of powder shedding after high-temperature sintering of the microporous layer, improves the water vapor heat transfer efficiency, and gives the microporous layer good toughness, tensile strength, and flexural strength. Furthermore, when the gas diffusion layer provided by this invention is assembled into a membrane electrode and a battery, the microporous layer is less prone to powder shedding under pressure. Moreover, the microporous layer can be distributed within the fiber pores of the support layer, thereby improving the compatibility between the support layer and the microporous layer, making the distribution of the microporous layer on the support layer more uniform, and consequently, making the stress distribution of the gas diffusion layer more uniform and improving electrical performance.

[0008] As can be seen from the above, the gas diffusion layer provided in the embodiments of the present invention improves the bonding strength between the microporous layer and the support layer, reduces the surface defects of the microporous layer, and improves the water vapor heat transfer efficiency.

[0009] Secondly, the present invention also provides a method for preparing a gas diffusion layer, comprising:

[0010] A microporous layer is formed on the surface of a support layer using a microporous hybrid material to obtain a pre-diffusion layer, wherein the microporous hybrid material contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0011] The prefabricated diffusion layer is cured with infrared light to obtain a gas diffusion layer.

[0012] Compared with the prior art, the beneficial effects of the gas diffusion layer preparation method provided by the present invention are the same as those of the gas diffusion layer in the first aspect, and will not be repeated here.

[0013] Thirdly, the present invention also provides an electrode comprising the gas diffusion layer provided in the first aspect.

[0014] Compared with the prior art, the beneficial effects of the electrode provided by the present invention are the same as those of the gas diffusion layer in the first aspect, and will not be elaborated here.

[0015] Fourthly, the present invention also provides a battery comprising the gas diffusion layer provided in the first aspect.

[0016] Compared with the prior art, the beneficial effects of the battery provided by the present invention are the same as those of the gas diffusion layer in the first aspect, and will not be elaborated here. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 This is a schematic diagram of the battery structure according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the gas diffusion layer according to an embodiment of the present invention;

[0020] Figure 3 This is a schematic flowchart of the gas diffusion layer preparation method according to an embodiment of the present invention;

[0021] Figure 4 This is a comparison chart of the current density and voltage density of Embodiment 1 and Comparative Examples 1 and 2 of the present invention.

[0022] Figure label:

[0023] 100 - Battery, 101 - Proton exchange membrane, 102a - First gas diffusion layer, 102b - Second gas diffusion layer, 103a - First catalyst layer, 103b - Second catalyst layer, 200 - Gas diffusion layer, 201 - Support layer, 202 - Microporous layer. Detailed Implementation

[0024] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0026] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0027] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this disclosure should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0028] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0029] A fuel cell is a device that directly converts chemical energy into electrical energy. By avoiding the heat-to-work conversion process of existing heat engines, it fundamentally overcomes the efficiency limitations of the Carnot cycle. Currently, it is the most widely developed type of fuel cell, possessing unique advantages such as no environmental pollution, high energy conversion efficiency and power density, low emissions and heat radiation, and low noise pollution, making its market prospects broad.

[0030] The gas diffusion layer is a key material in ion batteries, primarily functioning to collect current, transfer gas, and remove water produced by the electrochemical reaction, providing a channel for water-gas-heat transport in the electrode reactions. The gas diffusion layer consists of a support layer and a microporous layer, and its main functions are to collect current, transfer gas, and remove water produced by the electrochemical reaction, providing a channel for water-gas-heat transport in the electrode reactions.

[0031] Currently, conventional microporous layers are generally composed of carbon materials and polytetrafluoroethylene (PTFE). The microporous layer mainly relies on PTFE for bonding. However, the microporous layer is prone to powdering after high-temperature sintering. When it is assembled into membrane electrodes and batteries, the microporous layer is more likely to fall off under pressure, leading to failure of water vapor heat transfer.

[0032] To address the aforementioned problems, embodiments of the present invention provide a battery that may include electrodes. These electrodes may include a gas diffusion layer, as described in the embodiments of the present invention, to improve the bonding strength between the microporous layer and the support layer, reduce surface defects in the microporous layer, and improve water vapor heat transfer efficiency. It should be understood that the battery may include a gas diffusion layer, a catalyst layer, and a proton exchange membrane. Figure 1 A schematic diagram of the battery structure according to an embodiment of the present invention is shown, as follows: Figure 1 As shown, the battery 100 of this embodiment includes a proton exchange membrane 101, a first gas diffusion layer 102a, a second gas diffusion layer 102b, a first catalyst layer 103a, and a second catalyst layer 103b.

[0033] In practical applications, the battery in this embodiment of the invention can be a proton exchange membrane fuel cell, or other types of fuel cells, which will not be described in detail here. The gas diffusion layer in this embodiment of the invention includes a support layer and a microporous layer. It should be understood that the support layer can be a carbon paper layer.

[0034] An embodiment of the present invention provides a gas diffusion layer that is applied to the aforementioned battery. Figure 2 A schematic diagram of the gas diffusion layer according to an embodiment of the present invention is shown. Figure 2 As shown, the gas diffusion layer 200 of this embodiment includes a support layer 201 and a microporous layer 202 formed on the surface of the support layer. The microporous layer 202 contains a hydroxyl-terminated polyester resin and a curing agent.

[0035] The gas diffusion layer provided by this invention includes a support layer with two opposing surfaces and a microporous layer formed on one of the surfaces of the support layer. When the microporous layer includes at least a hydroxyl-terminated polyester resin and a curing agent, due to chemical action, the functional groups contained in the curing agent can react with the hydroxyl groups in the hydroxyl-terminated polyester resin and connect through chemical bonds to form a cross-linked network structure with a high cross-linking density. This improves the bonding strength between the hydroxyl-terminated polyester resin and the curing agent, reduces the possibility of powder shedding after high-temperature sintering of the microporous layer, improves the water vapor heat transfer efficiency, and gives the microporous layer good toughness, tensile strength, and flexural strength. Furthermore, when the gas diffusion layer provided by this invention is assembled into a membrane electrode and a battery, the microporous layer is less prone to powder shedding under pressure. Moreover, the microporous layer can be distributed within the fiber pores of the support layer, thereby improving the compatibility between the support layer and the microporous layer, making the distribution of the microporous layer on the support layer more uniform, and consequently, making the stress distribution of the gas diffusion layer more uniform and improving electrical performance.

[0036] As can be seen from the above, the gas diffusion layer provided in the embodiments of the present invention improves the bonding strength between the microporous layer and the support layer, reduces the surface defects of the microporous layer, and improves the water vapor heat transfer efficiency.

[0037] In one feasible embodiment, the aforementioned hydroxyl-terminated polyester resin includes an aliphatic hydroxyl-terminated polyester resin or an aromatic hydroxyl-terminated polyester resin. When the hydroxyl-terminated polyester resin is aliphatic, it contains 2 to 20 carbon atoms; when it is aromatic, it contains 2 to 30 carbon atoms. For example, the hydroxyl-terminated polyester resin can be a hydroxyl-terminated saturated polyester resin or a hydroxyl-terminated hyperbranched polyester. When the hydroxyl-terminated polyester resin is a hydroxyl-terminated saturated polyester resin, it can be HK-7805 or RB-7805, or other hydroxyl-terminated saturated polyester resins, without limitation. When the hydroxyl-terminated polyester resin is a hydroxyl-terminated hyperbranched polyester, it can be HyPer H10, HyPer H20, HyPer H30, or HyPer H40. It should be understood that the hydroxyl-terminated polyester resin used in the embodiments of the present invention may be in powder form.

[0038] In one feasible embodiment, the microporous layer of the present invention further includes a hydrophobic agent, a pore-forming agent, and a conductive filler, which can cause the hydroxyl-terminated polyester resin, curing agent, hydrophobic agent, pore-forming agent, and conductive filler to undergo a chemical reaction and bond together, thereby enabling the microporous layer to form a cross-linked network structure with a high cross-linking density. This improves the bonding strength between the hydroxyl-terminated polyester resin and the curing agent, reduces the possibility of powder shedding after high-temperature sintering of the microporous layer, and improves the water vapor heat transfer efficiency.

[0039] Based on this, by mass percentage, the aforementioned hydroxyl-terminated polyester resin accounts for 8%~9% of the microporous layer, the curing agent accounts for 0.42%~0.53% of the microporous layer, the hydrophobic agent accounts for 15%~40% of the microporous layer, the pore-forming agent accounts for 3%~5% of the microporous layer, and the conductive filler accounts for 50%~70% of the microporous layer. In this embodiment of the invention, controlling the mass percentages of the aforementioned hydroxyl-terminated polyester resin, curing agent, hydrophobic agent, pore-forming agent, and conductive filler within the above-mentioned percentage range allows for a more complete and thorough bonding reaction, preventing the hydroxyl-terminated polyester resin from agglomerating.

[0040] The curing agent can include one or more of triglycidyl isocyanurate, β-hydroxyalkylamide, and glycidyl polybenzoate. When the curing agent is triglycidyl isocyanurate, the epoxy groups contained in triglycidyl isocyanurate can react with the hydroxyl groups in the polyester to form a cross-linked network structure, and its rigid triazine heterocyclic structure can provide high hardness to the coating. When the curing agent is β-hydroxyalkylamide, the hydroxyalkylamide groups contained in β-hydroxyalkylamide react with the hydroxyl groups of the polyester resin to form a cross-linked network structure. Therefore, the bonding strength between the hydroxyl-terminated polyester resin and the curing agent can be improved.

[0041] Hydrophobic agents can include one or more of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF). It should be understood that the hydrophobic agent can be in powder form.

[0042] The pore-forming agent may include one or more of decomposable salts and inorganic pore-forming agents. When the pore-forming agent is a decomposable salt, it may be at least one of ethyl cellulose, polyvinyl alcohol, polyethylene glycol, ammonium carbonate, and ammonium chloride.

[0043] For conductive fillers, they can be one or more of carbon-based conductive fillers. For example, conductive fillers can be one or more of acetylene black, carbon nanotubes, carbon black, carbon powder, graphene, and graphite.

[0044] In one alternative embodiment, the amount of microporous layer in this invention is 20g to 30g per square meter of one surface of the support layer. When the amount of microporous layer is within this range, it allows the microporous layer to be completely formed on the surface of the support layer, avoiding the problem of poor support layer density caused by gaps between the support layer and the microporous layer. Simultaneously, within this quantitative range, since the microporous layer can completely cover one surface of the support layer, the tensile strength and flexural strength of the support layer are improved, giving it suitable density and good flexibility. Furthermore, when the amount of microporous layer is within this range, the thickness of the microporous layer can be thinner, thereby enabling faster water vapor heat transfer.

[0045] This invention also provides a method for preparing a gas diffusion layer, which can be used to prepare the gas diffusion layer of this invention. Figure 3 A schematic flowchart illustrating the method for preparing a gas diffusion layer according to an embodiment of the present invention is shown. Figure 3 As shown, the method for preparing the gas diffusion layer in this embodiment of the invention includes:

[0046] Step 301: A microporous layer is formed on the surface of the support layer using a microporous hybrid material to obtain a pre-fabricated diffusion layer. The microporous hybrid material contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0047] For example: First, a hydroxyl-terminated polyester resin, curing agent, hydrophobic agent, pore-forming agent, and conductive filler are mixed and dispersed to form a uniformly mixed powder. Then, the powder is sprayed / scraped / screen-printed onto one surface of the support layer until the powder loading is 25 g / m². 2 A support layer containing powder, i.e., a pre-fabricated diffusion layer, is obtained. In this embodiment of the invention, all added components are powders. Compared with wet mixing, this avoids polar effects and agglomeration, resulting in more uniform powder dispersion and mixing, and reducing surface defects in the microporous layer. Simultaneously, by introducing pore-forming agents and hydrophobic agents, this embodiment of the invention enables the formed microporous layer to possess better hydrophobicity and pore structure, effectively improving electrical performance.

[0048] Step 302: The pre-fabricated diffusion layer is cured with infrared light to obtain a gas diffusion layer. It should be understood that infrared curing can be performed in a gas-fired catalytic infrared heating device.

[0049] For example, a support layer containing powder is transferred to an infrared curing tunnel for fuel catalytic curing to obtain a gas diffusion layer. This embodiment of the invention utilizes an infrared curing process, which allows the hydroxyl-terminated polyester resin, curing agent, hydrophobic agent, pore-forming agent, and conductive filler to chemically react and bond together. This results in a highly cross-linked network structure in the microporous layer, improving the bonding strength between the microporous layer and the support layer and reducing the possibility of powder shedding after high-temperature sintering. Furthermore, compared to high-temperature baking, the infrared curing process consumes less energy, is simpler to operate, has a shorter curing time, produces higher coating quality, and has a higher safety factor.

[0050] In one feasible embodiment, the infrared curing conditions of this invention include: an infrared curing temperature of 240℃~320℃, an infrared curing wavelength of 3µm~7µm, and an infrared curing time of 2min~8min. The infrared curing temperature of this invention is much lower than the high-temperature baking temperature, reducing the possibility of powder loss after high-temperature sintering of the microporous layer.

[0051] In one alternative embodiment, this invention utilizes a microporous hybrid material to form a microporous layer on the surface of the support layer. Before obtaining the prefabricated diffusion layer, the method for preparing the gas diffusion layer further includes: performing a hydrophobic treatment on the surface of the support layer. This hydrophobic treatment prevents the gas diffusion layer from being "flooded," allowing water to be drained from the gas diffusion layer before flooding occurs, thus ensuring the normal output of the fuel cell.

[0052] In the gas diffusion layer provided in this embodiment of the invention, through chemical action, the functional groups contained in the curing agent can react with the hydroxyl groups in the hydroxyl-terminated polyester resin and connect through chemical bonds to form a cross-linked network structure with a high cross-linking density. This improves the bonding strength between the hydroxyl-terminated polyester resin and the curing agent, reduces the possibility of powder shedding after high-temperature sintering of the microporous layer, and improves the water vapor heat transfer efficiency.

[0053] To verify the effectiveness of the gas diffusion layer provided in the embodiments of the present invention, the embodiments of the present invention are demonstrated by comparing the embodiments with comparative examples.

[0054] Example 1

[0055] This invention provides a gas diffusion layer, including a support layer and a microporous layer formed on the surface of the support layer, wherein the microporous layer contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0056] The method for preparing the gas diffusion layer provided in this embodiment of the invention includes the following steps:

[0057] The first step involves mixing and dispersing 8g of RB-7805 hydroxyl-terminated saturated polyester resin, 0.46g of β-hydroxyalkylamide, 18g of polytetrafluoroethylene powder, 3g of vinyl cellulose, and 6.5g of acetylene black to form a uniformly mixed powder.

[0058] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 25 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0059] The third step is to prepare the gas diffusion layer: the support layer with powder is transferred to the infrared drying tunnel for fuel catalytic curing and cured at a temperature of 278℃, a wavelength of 3~7µm, and a curing time of 3min to obtain the gas diffusion layer.

[0060] Example 2

[0061] This invention provides a gas diffusion layer, including a support layer and a microporous layer formed on the surface of the support layer, wherein the microporous layer contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0062] The method for preparing the gas diffusion layer provided in this embodiment of the invention includes the following steps:

[0063] The first step involves mixing and dispersing 10 g of HK-7805 hydroxyl-terminated saturated polyester resin, 0.56 g of triglycidyl isocyanurate, 18 g of polytetrafluoroethylene powder, 3 g of vinyl cellulose, and 5.6 g of graphene to form a uniformly mixed powder.

[0064] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 25 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0065] The third step is to prepare the gas diffusion layer: the support layer with powder is transferred to the infrared drying tunnel for fuel catalytic curing and cured at a temperature of 278℃, a wavelength of 3~7µm, and a curing time of 3min to obtain the gas diffusion layer.

[0066] Example 3

[0067] This invention provides a gas diffusion layer, including a support layer and a microporous layer formed on the surface of the support layer, wherein the microporous layer contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0068] The method for preparing the gas diffusion layer provided in this embodiment of the invention includes the following steps:

[0069] The first step involves mixing and dispersing 8g of HyPer H40 hydroxyl-terminated hyperbranched polyester, 0.80g of glycidyl benzoate, 19g of polytetrafluoroethylene powder, 4g of vinyl cellulose, and 5g of carbon black to form a uniformly mixed powder.

[0070] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 25 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0071] The third step is to prepare the gas diffusion layer: the support layer with powder is transferred to the infrared drying tunnel for fuel catalytic curing and cured at a temperature of 278℃, a wavelength of 3~7µm, and a curing time of 3min to obtain the gas diffusion layer.

[0072] Example 4

[0073] This invention provides a gas diffusion layer, including a support layer and a microporous layer formed on the surface of the support layer, wherein the microporous layer contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0074] The method for preparing the gas diffusion layer provided in this embodiment of the invention includes the following steps:

[0075] The first step involves mixing and dispersing 9.2g of HyPer H10 hydroxyl-terminated hyperbranched polyester, 0.62g of β-hydroxyalkylamide, 20g of polyvinylidene fluoride powder, 2.8g of ammonium carbonate, and 7.2g of carbon nanotubes to form a uniformly mixed powder.

[0076] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 25 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0077] The third step is to prepare the gas diffusion layer: the support layer with powder is transferred to the infrared drying tunnel for fuel catalytic curing and cured at a temperature of 278℃, a wavelength of 3~7µm, and a curing time of 3min to obtain the gas diffusion layer.

[0078] Example 5

[0079] This invention provides a gas diffusion layer, including a support layer and a microporous layer formed on the surface of the support layer, wherein the microporous layer contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0080] The method for preparing the gas diffusion layer provided in this embodiment of the invention includes the following steps:

[0081] The first step involves mixing and dispersing 9.5g of HyPer H20 hydroxyl-terminated hyperbranched polyester, 0.63g of β-hydroxyalkylamide, 22g of polytetrafluoroethylene powder, 3.4g of polyethylene glycol, and 7.5g of acetylene black to form a uniformly mixed powder.

[0082] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 25 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0083] The third step is to prepare the gas diffusion layer: the support layer with powder is transferred to the infrared drying tunnel for fuel catalytic curing and cured at a temperature of 278℃, a wavelength of 3~7µm, and a curing time of 3min to obtain the gas diffusion layer.

[0084] Example 6

[0085] This invention provides a gas diffusion layer, including a support layer and a microporous layer formed on the surface of the support layer, wherein the microporous layer contains at least a hydroxyl-terminated polyester resin and a curing agent.

[0086] The method for preparing the gas diffusion layer provided in this embodiment of the invention includes the following steps:

[0087] The first step involves mixing and dispersing 8.9g of HyPer H30 hydroxyl-terminated hyperbranched polyester, 0.55g of β-hydroxyalkylamide, 16g of polyvinylidene fluoride powder, 3.3g of polyvinyl alcohol, and 5.8g of acetylene black to form a uniformly mixed powder.

[0088] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 25 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0089] The third step is to prepare the gas diffusion layer: the support layer with powder is transferred to the infrared drying tunnel for fuel catalytic curing and cured at a temperature of 278℃, a wavelength of 3~7µm, and a curing time of 3min to obtain the gas diffusion layer.

[0090] Comparative Example 1

[0091] The present invention provides a gas diffusion layer in a comparative example, with the same formulation and coating method as in Example 1, but the drying method is changed to high-temperature curing.

[0092] The method for preparing the gas diffusion layer provided in the comparative example of this invention includes the following steps:

[0093] The first step involves mixing and dispersing 8g of RB-7805 hydroxyl-terminated saturated polyester resin, 0.46g of β-hydroxyalkylamide, 18g of polytetrafluoroethylene powder, 3g of vinyl cellulose, and 6.5g of acetylene black to form a uniformly mixed powder.

[0094] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 25 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0095] The third step is to prepare the gas diffusion layer: place the sample in a drying oven and dry it at 200°C for 10 minutes, and then sinter it in a muffle furnace at 275°C to obtain the gas diffusion layer.

[0096] Comparative Example 2

[0097] The present invention provides a gas diffusion layer in a comparative example, with the same coating and drying methods as the examples, except that the ingredients are changed from a dry method to a wet method.

[0098] The method for preparing the gas diffusion layer provided in the comparative example of this invention includes the following steps:

[0099] The first step involves mixing 8g of RB-7805 hydroxyl-terminated saturated polyester resin, 0.46g of β-hydroxyalkylamide, 30g of polytetrafluoroethylene emulsion (the solid content of the polytetrafluoroethylene emulsion is 60%), 3g of vinyl cellulose, 6.5g of acetylene black, and 59g of water / alcohol solution (water:isopropanol = 1:5), and then shearing and dispersing the mixture to form a uniformly mixed powder.

[0100] The second step is to prepare the pre-fabricated diffusion layer: spray / coat / screen print the above-mentioned powder onto one side of the hydrophobically treated support layer until the powder loading is 38 g / m³. 2 This yields a support layer containing powder, namely a prefabricated diffusion layer.

[0101] The third step is to prepare the gas diffusion layer: the support layer with powder is transferred to the infrared drying tunnel for fuel catalytic curing and cured at a temperature of 278℃, a wavelength of 3~7µm, and a curing time of 3min to obtain the gas diffusion layer.

[0102] Comparative Example 3

[0103] Comparative Example 3 of the present invention provides a gas diffusion layer that does not contain the polyester resin with terminal hydroxyl groups of the embodiments of the present invention, and the other conditions are the same as those in Example 1.

[0104] The present invention tested relevant data of the gas diffusion layers prepared in Example 1 and the comparative example, and the results are shown in the table below:

[0105]

[0106] As can be seen from the table above, the gas diffusion layers prepared in Example 1 and Comparative Examples 1 and 2 of this invention all used microporous layers containing hydroxyl-terminated polyester resin and a curing agent. Their surface resistivity was lower than that of Comparative Example 3, and their contact angles were higher. This indicates that the surface roughness of the microporous layer containing hydroxyl-terminated polyester resin and a curing agent of this invention is lower than that of the microporous layer without hydroxyl-terminated polyester resin, and the dispersion uniformity of the microporous layer coating is better than that of Comparative Example 3. Compared with Comparative Examples 1 and 2, Example 1 has a higher surface resistivity, a lower pressure difference, and a higher contact angle. It is evident that compared to Example 1, the surface resistivity of Comparative Examples 1 and 2 increases sequentially, indicating that the surface roughness of the microporous layer in Example 1 is lower than that of Comparative Examples 1 and 2, the dispersion uniformity of the microporous layer coating is better than that of the comparative examples, and the contact angles decrease sequentially. In other words, when the microporous layer contains hydroxyl-terminated polyester resin and a curing agent, and the infrared curing process of this application is used, a gas diffusion layer with high water vapor heat transfer efficiency can be obtained.

[0107] Meanwhile, Comparative Example 3 does not contain the polyester resin with terminal hydroxyl groups of the present invention. As can be seen from the table above, the surface resistivity of the gas diffusion layer prepared by it is greater than that of Example 1 and Comparative Examples 1 to 2, and the contact angle is smaller than that of Example 1 and Comparative Examples 1 to 2. This indicates that the surface roughness of the microporous layer of Comparative Example 3 is greater than that of Example 1 and Comparative Examples 1 to 2, and the dispersion uniformity of the microporous layer coating of Comparative Example 3 is not as good as that of Example 1 and Comparative Examples 1 to 2.

[0108] For example, the gas diffusion layer microporous layer, gas diffusion layer carbon paper support layer, and membrane electrode prepared in Example 1 and Comparative Examples 1 and 2 are assembled into a single cell. [CCM (cathode Pt loading 0.4 mg / cm²)] 2 Anode Pt loading: 0.07 mg / cm³ 2 The frame and seals are assembled into a single battery (effective area 7cm²). The test conditions were as follows: battery temperature 65℃, open cathode, hydrogen pressure 150kPa, hydrogen flow rate 2.5 slpm, ambient humidity 100%. Current density and voltage density were tested. Figure 4 A comparison graph of current density and voltage density of Embodiment 1 and Comparative Examples 1 and 2 of the present invention is shown.

[0109] like Figure 4 As shown, compared with the examples, the voltages of Comparative Examples 1 and 2 are lower as the current density increases, especially when the current density exceeds 1.5 A / cm². 2 At that time, the voltage of Comparative Example 1 and Comparative Example 2 was lower than 0.6V, indicating that the internal resistance of the microporous layer and its gas diffusion layer carbon paper support layer prepared in the comparative examples was high, and the water vapor heat transfer performance was not as good as that of Example 1.

[0110] The above description is merely a specific embodiment of the present invention. Obviously, various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, this specification and accompanying drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the present invention. Clearly, those skilled in the art can make various alterations and modifications to the present invention without departing from its spirit and scope. Thus, if these modifications and variations of the present invention fall within the scope of the claims and their equivalents, the intent of the present invention includes these modifications and variations. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a gas diffusion layer, characterized in that, include: A microporous layer is formed on the surface of a support layer using a microporous mixed material to obtain a pre-diffusion layer. The microporous mixed material contains at least a hydroxyl-terminated polyester resin and a curing agent. The hydroxyl-terminated polyester resin includes aliphatic or aromatic hydroxyl-terminated polyester resins, and the curing agent includes one or more of triglycidyl isocyanurate, β-hydroxyalkylamide, and glycidyl polybenzoate. The pre-fabricated diffusion layer is infrared-cured to obtain a gas diffusion layer. The infrared curing conditions include: an infrared curing temperature of 240℃~320℃, an infrared curing wavelength of 3µm~7µm, and an infrared curing time of 2min~8min.

2. The method for preparing the gas diffusion layer according to claim 1, characterized in that, The microporous hybrid material further includes a hydrophobic agent, a pore-forming agent, and a conductive filler. Before forming a microporous layer on the surface of the support layer using the microporous hybrid material to obtain the pre-fabricated diffusion layer, the method further includes: The surface of the support layer is treated with a hydrophobic coating.

3. A gas diffusion layer, characterized in that, The gas diffusion layer is prepared according to the method of any one of claims 1 or 2, and includes a support layer and a microporous layer formed on the surface of the support layer.

4. The gas diffusion layer according to claim 3, characterized in that, The microporous layer further includes a hydrophobic agent, a pore-forming agent, and a conductive filler. By mass percentage, the hydroxyl-terminated polyester resin accounts for 8% to 9% of the mass percentage of the microporous layer, the curing agent accounts for 0.42% to 0.53% of the mass percentage of the microporous layer, the hydrophobic agent accounts for 15% to 40% of the mass percentage of the microporous layer, the pore-forming agent accounts for 3% to 5% of the mass percentage of the microporous layer, and the conductive filler accounts for 50% to 70% of the mass percentage of the microporous layer.

5. The gas diffusion layer according to claim 4, characterized in that, The hydrophobic agent includes one or more of polytetrafluoroethylene and polyvinylidene fluoride; The pore-forming agent includes one or more of decomposable salts and inorganic pore-forming agents; The conductive filler includes one or more of the carbon-based conductive fillers.

6. The gas diffusion layer according to any one of claims 3 to 5, characterized in that, The mass of the microporous layer on one surface of the support layer per square meter is 20g to 30g.

7. An electrode, characterized in that, The electrode includes the gas diffusion layer as described in any one of claims 3 to 6.

8. A battery, characterized in that, The battery includes the gas diffusion layer as described in any one of claims 3 to 6.

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