Gas diffusion layer and method for producing the same, and unitized reversible fuel cell

Abstract

The application discloses a kind of gas diffusion layer and its preparation method, integrated reversible fuel cell, gas diffusion layer includes at least one layer of first functional layer and at least one layer of second functional layer;First functional layer includes first titanium-based porous material, first transition layer and first composite layer in turn;Second functional layer includes second titanium-based porous material, second transition layer, second composite layer in turn;At least one of first composite layer and second composite layer contains platinum group element and oxygen element, second composite layer also includes hydrophobic substance, the contact angle of first composite layer is 0~60°, the contact angle of the second composite layer is 90~180°.Gas diffusion layer of the application can solve the problem that gas diffusion layer is not compatible, can also reduce ohmic resistance, improve the output characteristics of electric pile.

Description

Technical Field

[0001] This invention belongs to the field of energy and energy storage technology, specifically relating to a gas diffusion layer and its preparation method, and an integrated reversible fuel cell. Background Technology

[0002] An integrated regenerative fuel cell (URFC) is an energy conversion and storage device that integrates the dual functions of fuel cell (FC) power generation and water electrolysis (WE) hydrogen production within a single unit. In fuel cell mode, the URFC generates water from hydrogen and oxygen through an electrochemical reaction and releases electrical energy; in water electrolysis mode, the URFC electrolyzes water into hydrogen and oxygen with the help of external electrical energy, thereby achieving energy storage.

[0003] An integrated reversible fuel cell (URFC) mainly consists of a proton exchange membrane, a catalyst layer, a gas diffusion layer, and bipolar plates. The gas diffusion layer, located outside the catalyst layer, is responsible for gas / water transport and current conduction. In the dual-mode operation of the URFC, the water management function of the gas diffusion layer is particularly critical: in fuel cell mode, the gas diffusion layer needs to be hydrophobic to effectively drain product water and prevent flooding; in water electrolysis mode, it needs to be hydrophilic to ensure a sufficient water supply to the catalyst layer. Traditional fuel cell gas diffusion layers cannot simultaneously meet these requirements.

[0004] Therefore, there is an urgent need to develop a dual-functional integrated gas diffusion layer that can simultaneously meet the requirements of both fuel cell mode and water electrolysis mode, in order to solve the problem of incompatibility of traditional gas diffusion layer materials. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, the main objective of this invention is to provide a gas diffusion layer and its preparation method, as well as an integrated reversible fuel cell. The gas diffusion layer of this invention is a dual-function integrated gas diffusion layer that can simultaneously meet the requirements of both fuel cell mode and water electrolysis mode, solving the problem of gas diffusion layer incompatibility, while reducing ohmic internal resistance and improving the output characteristics of the battery.

[0006] In a first aspect, embodiments of this application provide a gas diffusion layer. The gas diffusion layer includes at least one first functional layer and at least one second functional layer; The first functional layer comprises, in sequence, a first titanium-based porous material, a first transition layer, and a first composite layer; The second functional layer comprises, in sequence, a second titanium-based porous material, a second transition layer, and a second composite layer; At least one of the first transition layer and the second transition layer comprises a Ta-M alloy, wherein M comprises at least one of Ti and Nb; At least one of the first composite layer and the second composite layer includes a porous layer comprising an oxide of a platinum group element, wherein carbon is distributed on the surface and in the pores of the porous layer, and the platinum group element includes at least one of Pt, Ir, and Ru; or At least one of the first composite layer and the second composite layer comprises oxides of platinum group elements and tantalum oxide, wherein the platinum group elements include at least one of Pt, Ir and Ru; The second composite layer further includes a hydrophobic material, which is polytetrafluoroethylene. The contact angle of the first composite layer is 0~60°, and the contact angle of the second composite layer is 90°~180°.

[0007] Secondly, embodiments of this application provide a method for preparing the gas diffusion layer described in the first aspect, comprising the following steps: Provide titanium-based porous materials; Forming a transition layer on the surface of the titanium-based porous material, the step of forming the transition layer includes: Under vacuum conditions and in an argon atmosphere, Ta and M metal targets are used to deposit on the surface of the titanium-based porous material, the deposition including magnetron sputtering; A composite layer is formed on the surface of the transition layer to obtain an intermediate part, wherein the contact angle of the composite layer is 0~60°; The steps for forming the composite layer include: depositing platinum group metal targets and graphite targets on the surface of the transition layer under vacuum conditions in a mixed gas atmosphere of argon, acetylene, and oxygen; or The steps for forming the composite layer include: coating the surface of the transition layer with an oxyacid solution containing platinum group elements and a salt solution containing tantalum, performing a first heat treatment, repeating the coating and first heat treatment steps 10 to 20 times, and then performing a second heat treatment. Two intermediate components are provided. The surface of the composite layer of one of the intermediate components is hydrophobically treated with a fluorine-containing substance to obtain a second functional layer. The contact angle of the composite layer after hydrophobic treatment is 90°~180°. The other intermediate component serves as the first functional layer. A gas diffusion layer is obtained by stacking at least one first functional layer and at least one second functional layer.

[0008] Thirdly, embodiments of this application provide an integrated reversible fuel cell, the integrated reversible fuel cell comprising: The first and second bipolar plates are set relative to each other; A proton exchange membrane located between the first bipolar plate and the second bipolar plate; A first gas diffusion layer located between the first bipolar plate and the proton exchange membrane; and a second gas diffusion layer located between the second bipolar plate and the proton exchange membrane, wherein at least one of the first gas diffusion layer and the second gas diffusion layer comprises a gas diffusion layer prepared by the method described in the first aspect or the method described in the second aspect.

[0009] Compared with the prior art, the present invention has at least the following technical effects: The first functional layer of this application includes a first titanium-based porous material, a first transition layer, and a first composite layer. The first composite layer contains platinum group elements and oxygen. The contact angle of the first composite layer is 0-60°, giving it hydrophilic properties and fulfilling the hydrophilic requirement of the gas diffusion layer. The second functional layer of this application includes a second titanium-based porous material, a second transition layer, and a second composite layer. The second composite layer contains a hydrophobic material. The contact angle of the second composite layer is 90°-180°, giving it hydrophobic properties and fulfilling the hydrophobic requirement of the gas diffusion layer. Thus, the gas diffusion layer can be used in integrated reversible fuel cells without replacing or reprocessing it; the same gas diffusion layer can adapt to both operating modes. Moreover, this application solves the incompatibility problem of the gas diffusion layer through the synergistic effects of the titanium-based porous material, the first transition layer, and the first composite layer, and the synergistic effects of the titanium-based porous material, the first transition layer, and the second composite layer, while also reducing ohmic internal resistance and improving the output characteristics of the battery.

[0010] Compared to traditional catalytic layers and gas diffusion layers, this application uses a first composite layer and a second composite layer containing platinum group elements as gas diffusion layers, and a porous titanium-based material as the substrate layer. This achieves the integration of catalytic and gas transport functions. Platinum group elements can be used for catalytic oxygen reduction in fuel cell mode and catalytic hydrogen evolution in electrolysis mode, effectively simplifying the structure of the integrated reversible fuel cell URFC, reducing thickness and interfacial resistance, and improving electron conduction efficiency. This solves the problem that traditional carbon-based gas diffusion layers (GDL) cannot be used in electrolyzers, while titanium-based porous diffusion layers (PTL) cannot be used in fuel cells. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a gas diffusion layer provided in an embodiment of this application; Figure 2 This is a schematic diagram of another structure of the gas diffusion layer provided in the embodiments of this application; Figure 3 This is a schematic diagram of another structure of the gas diffusion layer provided in the embodiments of this application; Figure 4 This is a schematic diagram of an integrated reversible fuel cell provided in an embodiment of this application; Figure 5 This is an electron microscope schematic diagram of the Ir-CO composite layer prepared in Example 1; Figure 6 This is a schematic diagram comparing the polarization curves of the gas diffusion layer in Example 1 and Comparative Example 1 under electrolytic cell mode. Figure 7 This is a schematic diagram comparing the polarization curves of the gas diffusion layer in Example 1 and Comparative Example 1 under fuel cell mode.

[0012] In the attached image: 1000 - Integrated reversible fuel cell; 100 - First bipolar plate; 200 - Second bipolar plate; 300-proton exchange membrane; 400 - First gas diffusion layer; 500 - Second gas diffusion layer; 10-Gas diffusion layer; 1-First functional layer; 11-First titanium-based porous material; 12-First transition layer; 13-First composite layer; 2-Second functional layer; 21-Second titanium-based porous material; 22-Second transition layer; 23-Second composite layer. Detailed Implementation

[0013] To more fully understand and demonstrate the technical solutions, objectives, and advantages of the present invention, the technical effects produced by the present invention will be described in further detail and completely below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be noted that other embodiments obtained by those skilled in the art without departing from the concept of the present invention are all within the protection scope of the present invention.

[0014] In related technologies, traditional fuel cell gas diffusion layers typically consist of two layers: a substrate layer and a microporous layer. The substrate layer, mainly made of carbon paper or carbon cloth, provides mechanical support, electronic conduction, and gas diffusion channels for the electrodes. The microporous layer, usually composed of carbon powder and a hydrophobic agent, is coated on the side of the substrate layer closest to the catalyst layer. However, on the anode side (oxygen evolution side) of the electrolyzer, carbon materials are unsuitable due to the extreme corrosive environment of high potential, strong acidity, and oxygen abundance. Therefore, titanium-based materials have become the preferred choice for porous transport layers. However, under anodic oxidation conditions, titanium-based porous diffusion layers spontaneously form a titanium dioxide passivation layer on their surface, leading to a significant increase in interfacial contact resistance. Furthermore, traditional fuel cell gas diffusion requires hydrophobic treatment, while the porous diffusion layer of the electrolyzer requires hydrophilic treatment. This makes it impossible for traditional single-design gas diffusion layers to simultaneously meet the requirements of URFC dual-mode operation.

[0015] In view of this, this application provides a gas diffusion layer and its preparation method, and an integrated reversible fuel cell. The gas diffusion layer of the present invention is a dual-function integrated gas diffusion layer that can simultaneously meet the requirements of fuel cell mode and water electrolysis mode, solves the incompatibility problem of traditional materials, reduces ohmic internal resistance, and improves the output characteristics of the battery.

[0016] This application provides a gas diffusion layer. Figure 1 A schematic diagram of a gas diffusion layer structure is shown, such as... Figure 1 As shown, the gas diffusion layer 10 includes at least one first functional layer 1 and at least one second functional layer 2; The first functional layer 1 includes, in sequence, a first titanium-based porous material 11, a first transition layer 12, and a first composite layer 13; The second functional layer 2 includes, in sequence, a second titanium-based porous material 21, a second transition layer 22, and a second composite layer 23; At least one of the first composite layer 13 and the second composite layer 23 contains platinum group elements and oxygen elements. The second composite layer 23 also includes a hydrophobic material. The contact angle of the first composite layer 13 is 0~60° and the contact angle of the second composite layer 23 is 90°~180°.

[0017] In the above technical solution, the first functional layer 1 of this application includes a first titanium-based porous material 11, a first transition layer 12, and a first composite layer 13. The first composite layer 13 contains platinum group elements and oxygen elements. The contact angle of the first composite layer 13 is 0~60°, giving the first functional layer 1 a hydrophilic function, thus meeting the hydrophilic requirement of the gas diffusion layer 10 in the water electrolysis mode. The second functional layer 2 of this application includes a second titanium-based porous material 21, a second transition layer 22, and a second composite layer 23. The second composite layer 23 contains a hydrophobic material. The contact angle of the second composite layer 23 is 90°~180°, giving the second functional layer 2 a hydrophobic function, thus meeting the hydrophobic requirement of the gas diffusion layer 10 in the fuel cell mode. Therefore, the gas diffusion layer 10 can be applied to an integrated reversible fuel cell without replacing or reprocessing the gas diffusion layer 10; the same gas diffusion layer 10 can be used to adapt to both operating modes. Moreover, this application solves the incompatibility problem of the gas diffusion layer 10 through the synergistic effect of the first titanium-based porous material 11, the first transition layer 12 and the first composite layer 13, and the synergistic effect of the second titanium-based porous material 21, the first transition layer 12 and the second composite layer 23, while reducing the ohmic internal resistance and improving the output characteristics of the battery.

[0018] The first functional layer 1 of this application is hydrophilic, and the second functional layer 2 is hydrophobic. In fuel cell mode, water droplets generated during the reaction are "absorbed" into the gas diffusion layer 10 upon encountering the first functional layer 1, and then "pushed" towards the bipolar plate flow channel upon encountering the second functional layer 2, forming a continuous drainage channel. In water electrolysis mode, water in the flow channel is "absorbed" upon encountering the first functional layer 1, and the generated oxygen bubbles are "expelled" upon encountering the second functional layer 2, forming a highly efficient water intake-exhaust system.

[0019] Compared to traditional catalytic layers and gas diffusion layers, this application uses a first composite layer 13 and a second composite layer 23 as the gas diffusion layer 10, and a porous titanium-based material as the substrate layer, thus integrating catalytic and gas transport functions. Platinum group elements can be used for catalytic oxygen reduction in fuel cell mode and catalytic hydrogen evolution in electrolysis mode, effectively simplifying the structure of the integrated reversible fuel cell URFC, reducing thickness and interfacial resistance, and improving electron conduction efficiency. This solves the problem that traditional carbon-based gas diffusion layers (GDL) cannot be used in electrolyzers, while titanium-based porous diffusion layers (PTL) cannot be used in fuel cells.

[0020] In some embodiments, the contact angle of the first composite layer 13 is 0° to 60°, specifically 0°, 10°, 20°, 30°, 40°, 50°, 60°, etc., and is not limited here. Preferably, the contact angle of the first composite layer 13 is 20° to 60°.

[0021] In this application, the contact angle was measured according to the national standard GB / T 30447-2013. Specifically, the testing equipment was a contact angle meter with a testing range of 0°~180°, a resolution of 0.1°, a measurement accuracy of ±1°, and a syringe needle of 0.9mm. The testing procedure was as follows: when a water droplet with a volume of 4μL (a flow rate of approximately 0.5μL / s) could contact the surface of the sample and detach from the needle, forming a seated droplet on the sample surface, the formation and spread of the seated droplet were photographed using the contact angle meter at a speed of not less than 2 frames / s. The spread time of the seated droplet was 180s, but results with a spread time of 55s~65s could be selected.

[0022] In some embodiments, the contact angle of the second composite layer 23 is 90° to 180°, specifically 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, 180°, etc., and is not limited thereto. Preferably, the contact angle of the first composite layer 13 is 100° to 150°.

[0023] This application does not limit the number of the first functional layer 1 and the second functional layer 2. The first functional layer 1 can be, for example, 1, 3, 5, 8, 10, 15, 20, 25, 30, etc., and the second functional layer 2 can be, for example, 1, 3, 5, 8, 10, 15, 20, 25, 30, etc. Figure 1 A schematic diagram of a first functional layer 1 and a second functional gas diffusion layer 10 is shown. Figure 2 and Figure 3 A schematic diagram of a structure consisting of two or more first functional layers 1 and two or more second functional gas diffusion layers 10 is shown.

[0024] In some implementations, the platinum group elements include at least one of Pt, Ir, and Ru.

[0025] In some embodiments, the platinum group elements exist in at least one of the following forms: elemental platinum group elements and oxides of platinum group elements. In some embodiments, the platinum group elements exist in elemental platinum group elements. In some embodiments, the platinum group elements exist in the form of oxides of platinum group elements. In some embodiments, the platinum group elements exist in both elemental platinum group elements and oxides of platinum group elements. Optionally, the first composite layer 13 and the second composite layer 23 contain at least oxides of platinum group elements. Elemental platinum group elements include Pt, Ir, and Ru, etc. When the platinum group element includes Pt, the oxide of the platinum group element is PtO2. When the platinum group element includes Ir, the oxide of the platinum group element is IrO2. When the platinum group element includes Ru, the oxide of the platinum group element is RuO2.

[0026] In some embodiments, the total loading of at least one of the platinum group elements and platinum group element oxides in the first composite layer 13 is less than or equal to 2 g / m². 2 Specifically, it could be 0.1 g / m 2 0.3 g / m 2 0.5 g / m 2 0.7 g / m 2 1g / m 2 1.3 g / m 2 1.5 g / m 2 1.8 g / m 2 2 g / m 2 etc. are not specified here.

[0027] In some embodiments, the total loading of at least one of the platinum group elements and platinum group element oxides in the second composite layer 23 is less than or equal to 2 g / m². 2 Specifically, it could be 0.1 g / m 2 0.3 g / m 2 0.5 g / m 2 0.7 g / m 2 1g / m 2 1.3 g / m 2 1.5 g / m 2 1.8 g / m 2 2 g / m 2 etc. are not specified here.

[0028] In some embodiments, the hydrophobic material is connected to the second composite layer 23 via adsorption and / or chemical bonds. The hydrophobic material contains fluorine and may be, for example, polytetrafluoroethylene (PTFE). PTFE is distributed in the form of a thin film on the surface of the second composite layer 23, imparting hydrophobicity to the second composite layer 23. Alternatively, the hydrophobic material may be a fluorinated modified layer formed by the second composite material and fluorine element connected by adsorption and covalent bonds, creating a functional surface that combines hydrophobicity and stability.

[0029] In some implementations, the thickness of the first functional layer 1 is 150nm~250nm, specifically 150 nm, 170nm, 200 nm, 220 nm, 240 nm, 250 nm, etc., which are not limited here.

[0030] In some embodiments, the thickness of the second functional layer 2 is 150nm~250nm, specifically 150 nm, 170nm, 200 nm, 220 nm, 240 nm, 250 nm, etc., which are not limited here.

[0031] In some embodiments, the first titanium-based porous material 11 includes, but is not limited to, porous materials such as titanium felt and titanium foam. The second titanium-based porous material 21 includes, but is not limited to, porous materials such as titanium felt and titanium foam.

[0032] In some embodiments, at least one of the first composite layer 13 and the second composite layer 23 includes a porous layer comprising an oxide of a platinum group element, specifically, the platinum group element oxides of this application constitute the porous layer, with carbon elements distributed on the surface and within the pores of the porous layer. The porous layer configuration of this application facilitates an increase in the specific surface area of ​​the first composite layer 13 and the second composite layer 23, exposing more active sites and enhancing catalytic activity; it also catalyzes gas-liquid two-phase transport. Carbon elements provide electron transport channels, reducing contact resistance. Carbon elements can also form composite structures with the platinum group element oxides, enhancing structural stability. Furthermore, the presence of carbon elements can suppress excessive lattice expansion of the platinum group element oxides during the oxygen evolution reaction, reducing coating peeling from the first composite layer 13 and the second composite layer 23.

[0033] Optionally, carbon materials include amorphous carbon.

[0034] Optionally, when the platinum group elements include iridium (Ir), the porous layer is an iridium oxide (IrO2) porous layer, and carbon is distributed on the surface and inside the iridium oxide porous layer.

[0035] In some embodiments, at least one of the first composite layer 13 and the second composite layer 23 includes a platinum group element, an oxygen element, and tantalum oxide. The mass percentage of tantalum oxide in the first composite layer is greater than or equal to 30 wt%, specifically 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, etc., and is not limited herein. The mass percentage of tantalum oxide in the second composite layer is greater than or equal to 30 wt%, specifically 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, etc., and is not limited herein.

[0036] Optionally, platinum group elements and oxygen form oxides of platinum group elements. These oxides (e.g., iridium oxide) readily undergo irreversible dissolution in the high-potential oxygen evolution reaction, as shown in the following reaction equation: IrO2 + 2H + Ir 4+ +H₂O + 1 / 2O₂

[0037] Optionally, tantalum oxide and oxides of platinum group elements form a solid solution structure. Tantalum oxide has good stability, and its solid solution structure with oxides of platinum group elements can inhibit the dissolution of platinum group element oxides, thereby improving the catalytic activity and long-term stability of the first composite layer 13 and the second composite layer 23. Moreover, tantalum oxide itself is an insulator, and its solid solution structure with oxides of platinum group elements can effectively compensate for the conductivity of the first composite layer 13 and the second composite layer 23.

[0038] In some embodiments, at least one of the first composite layer 13 and the second composite layer 23 comprises an oxide of a platinum group element and tantalum oxide, which together form a solid solution.

[0039] In some embodiments, at least one of the first transition layer 12 and the second transition layer 22 comprises a Ta-M alloy, where M comprises at least one of Ti and Nb. The first transition layer 12 can be metallurgically bonded to the first titanium-based porous material 11, thereby enhancing the bonding force between the first titanium-based porous material 11 and the first composite layer 13. Moreover, the Ta-M alloy exhibits excellent corrosion resistance, remaining stable in extreme corrosive environments characterized by high potential, strong acidity, and oxygen abundance. The Ta-M alloy can cover the surface of the first titanium-based porous material 11, inhibiting its oxidation and effectively improving its corrosion resistance. Optionally, at least one of the first transition layer 12 and the second transition layer 22 comprises a Ta-Ti alloy or a Ta-Nb alloy.

[0040] In some embodiments, the atomic content of Ta in the Ta-M alloy is 30 at% to 65 at%, and the specific atomic content of Ta can be 30 at%, 35 at%, 40 at%, 45 at%, 50 at%, 55 at%, 60 at%, 65 at%, etc., without limitation.

[0041] In some embodiments, the atomic content of Ta in the first transition layer 12 decreases along the direction from the first titanium-based porous material 11 to the first composite layer 13. The decreasing Ta content in the first transition layer 12 of this application helps eliminate interfacial stress concentration in the gas diffusion layer 10 and simultaneously improves the bonding force between the first transition layer 12 and the first titanium-based porous material 11, as well as the bonding force between the first transition layer 12 and the first composite layer 13. Optionally, the decrease in the atomic content of Ta in the first transition layer 12 along the direction from the first titanium-based porous material 11 to the first composite layer 13 can be uniform, gradient, or non-uniform.

[0042] In some embodiments, the atomic content of Ta in the second transition layer 22 decreases along the direction from the second titanium-based porous material 21 to the second composite layer 23. The decreasing Ta content in the second transition layer 22 in this application helps eliminate interfacial stress concentration in the gas diffusion layer 10 and simultaneously improves the bonding force between the second transition layer 22 and the second titanium-based porous material 21, as well as the bonding force between the second transition layer 22 and the second composite layer 23. Optionally, the magnitude of the decrease in the atomic content of Ta mentioned above can be a uniform decrease, a gradient decrease, or a non-uniform decrease.

[0043] In some embodiments, the thickness of the first transition layer 12 is 100nm~200nm, specifically it can be 100 nm, 110nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200nm, etc., and is not limited here.

[0044] In some embodiments, the thickness of the second transition layer 22 is 100nm~200nm, specifically it can be 100 nm, 110nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200nm, etc., and is not limited here.

[0045] In some implementations, the first functional layer 1 and the second functional layer 2 are alternately arranged. Figure 2 (As shown).

[0046] In some implementations, the number of first functional layers 1 is greater than or equal to the number of second functional layers 2. When the number of first functional layers 1 is greater than the number of second functional layers 2, the first functional layers 1 and the second functional layers 2 can be partially alternated. Figure 3 As shown in the figure, multiple first functional layers 1 can be stacked, and multiple second functional layers 2 can be stacked, and then superimposed. Of course, other stacking methods can also be used, and this application does not limit them.

[0047] Optionally, the proportion of the second functional layer 2 in the sum of the first functional layer 1 and the second functional layer 2 is 40% to 45%, specifically 40%, 41%, 42%, 43%, 44%, 45%, etc., which is not limited here. Controlling the proportion of the second functional layer 2 in the sum of the first functional layer 1 and the second functional layer 2 within the above range is beneficial to achieving a performance balance between the fuel cell mode and the electrolyzer mode of the integrated reversible fuel cell, so that the performance of both modes reaches the optimal level.

[0048] This application also provides a method for preparing the above-mentioned gas diffusion layer, including the following steps: S100 provides titanium-based porous materials; S200, a transition layer is formed on the surface of the titanium-based porous material; S300, A composite layer is formed on the surface of the transition layer to obtain an intermediate part; the composite layer contains platinum group elements and oxygen elements, and the contact angle of the composite layer is 0°~60°; S400. Two middlewares are provided. The surface of the composite layer of one of the middlewares is hydrophobically treated to obtain a second functional layer. The contact angle of the hydrophobically treated composite layer is 90°~180°. The other middleware is used as the first functional layer. S500, At least one first functional layer and at least one second functional layer are stacked to obtain a gas diffusion layer.

[0049] In some embodiments, in S200, forming a transition layer on the surface of the titanium-based porous material includes the following steps: Under vacuum conditions and in an argon atmosphere, deposition is performed on the surface of a titanium-based porous material using a Ta target and an M metal target, the deposition including magnetron sputtering, and M including at least one of Ti and Nb.

[0050] In some implementations, the deposition current of the Ta target is 1A to 4A, specifically 1A, 1.5A, 2A, 2.5A, 3A, 3.5A, 4A, etc., which are not limited here.

[0051] In some implementations, the deposition current of the M metal target is 5A to 8A, specifically 5A, 5.5A, 6A, 6.5A, 7A, 7.5A, 8A, etc., which are not limited here.

[0052] In some embodiments, the deposition temperature is 200°C to 400°C, specifically 200°C, 250°C, 300°C, 350°C, 400°C, etc., which are not limited here.

[0053] In some embodiments, the bias voltage for deposition includes a first bias voltage, a second bias voltage, and a third bias voltage set sequentially. The first bias voltage is 1000V~1300V, the second bias voltage is 400V~600V, and the third bias voltage is 100V~300V. The deposition time under the first bias voltage is 20min~40min, the deposition time under the second bias voltage is 20min~40min, and the deposition time under the third bias voltage is 20min~40min.

[0054] In some embodiments, in S300, forming a composite layer on the surface of the transition layer includes the following two methods: The first method involves forming a composite layer by depositing platinum group metal targets and graphite targets on the surface of the transition layer under vacuum conditions in a mixed gas atmosphere of argon, acetylene and oxygen, wherein the deposition includes magnetron sputtering.

[0055] In the above steps, during the deposition process, the mixed gas and graphite target are doped and distributed in the formed layer structure. Under certain temperature and vacuum conditions, the graphite target undergoes gasification and decomposition, and together with the mixed gas, forms pores in the layer structure.

[0056] In some embodiments, the volume ratio of argon, acetylene, and oxygen is (6~16):(1~6):(0.5~2), specifically 6:3:1, 7:2:1, 8:1:1, 9:5:2, 10:1:0.5, 11:6:1, 12:1:1, 13:3:0.5, 14:2:2, 15:4:1, 16:1:0.5, etc., and no limitation is made here.

[0057] In some implementations, the deposition current of the platinum group metal target is 1A to 3A, specifically 1A, 1.5A, 2A, 2.5A, 3A, etc., which are not limited here.

[0058] In some embodiments, the deposition current of the graphite target is 5A to 15A, specifically 5A, 8A, 10A, 12A, 15A, etc., which are not limited here.

[0059] In some embodiments, the deposition temperature is 300℃~800℃, specifically 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, etc., which are not limited here.

[0060] In some implementations, the bias voltage for deposition is 400V~600V, specifically 400V, 430V, 450V, 480V, 500V, 520V, 550V, 580V, 600V, etc., which are not limited here.

[0061] In some implementations, the deposition time is 60 min to 120 min, specifically 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, etc., and is not limited here.

[0062] This application controls the deposition current, deposition temperature, deposition bias, and deposition time of platinum group metal targets and graphite targets to form a loose and porous platinum group metal oxide layer, with the graphite target deposited on the surface and / or in the pores of the platinum group metal oxide layer.

[0063] The second method involves forming a composite layer by coating a solution of oxyacid salt containing platinum group elements and a solution of salt containing tantalum on the surface of the transition layer, performing a heat treatment at 70°C to 90°C, repeating the coating and heat treatment process 10 to 20 times, and then performing a second heat treatment at 100°C to 150°C. This forms a solid solution structure of platinum group elements, tantalum, and oxygen, which not only inhibits the dissolution of platinum group elements and maintains their catalytic activity, but also improves the conductivity of the composite layer and reduces contact resistance. Furthermore, the multiple coatings and heat treatments enhance the bonding between the composite layer and the transition layer.

[0064] In the above steps, during the heat treatment process, the solvent in the oxyacid solution containing platinum group elements and the salt solution containing tantalum evaporates to form gas, and the gas overflows from the composite layer to form a porous structure.

[0065] In some embodiments, in S400, the hydrophobic treatment includes modifying the surface of the composite layer of one of the intermediates with a fluorine-containing substance. The modification treatment includes, but is not limited to, at least one of impregnation, spraying and vacuum filling methods, so that fluorine enters the composite layer and exhibits hydrophobicity.

[0066] This application also provides an integrated reversible fuel cell. Figure 4 A schematic diagram of an integrated reversible fuel cell structure is shown, such as... Figure 4 As shown, the integrated reversible fuel cell 1000 includes: The first bipolar plate 100 and the second bipolar plate 200 are set relative to each other; A proton exchange membrane 300 is located between the first bipolar plate 100 and the second bipolar plate 200; A first gas diffusion layer 400 located between a first bipolar plate 100 and a proton exchange membrane 300; and a second gas diffusion layer 500 located between a second bipolar plate 200 and a proton exchange membrane 300, wherein at least one of the first gas diffusion layer 400 and the second gas diffusion layer 500 includes the aforementioned gas diffusion layer.

[0067] The integrated reversible fuel cell 1000 of this application achieves seamless switching between fuel cell power generation mode and water electrolysis hydrogen production mode using a single gas diffusion layer, completely resolving the contradiction between "flooding" and "gas blockage" caused by incompatibility of gas diffusion layers in existing technologies. Through the synergistic design of the first transition layer, second transition layer, first functional layer, and second functional layer in the gas diffusion layer, this application significantly improves the oxidation resistance under high-potential environments, while reducing contact resistance by 60%, increasing the power density of the fuel cell mode by 25%, and reducing energy consumption in the electrolyzer mode by 12%.

[0068] The following are specific embodiments illustrating this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0069] Example 1 (1) Select titanium fiber felt with uniform thickness and ultrasonically clean it in ethanol and water to remove surface grease and surface debris.

[0070] (2) Fix the titanium fiber felt electrode plate to the hanger, move it to the closed reaction chamber and evacuate the inside. When the vacuum reaches 5×10 -3 At Pa, the heater is turned on to heat to 300℃ and held at that temperature. Then, Ar gas is introduced into the cavity through the gas path and gas hole. Magnetron sputtering deposition is performed using Ti and Ta targets. The vacuum degree of the process is controlled to be 0.1 Pa by the gas extraction system. At the deposition temperature of 300℃, the deposition current of Ti target is controlled to be 6A and the deposition current of Ta target is controlled to be 2A. The deposition bias voltage is stacked in three layers of 1200V / 500V / 200V, and the deposition time of each layer is 30min to form a Ta-Ti alloy transition layer with a thickness of 150nm.

[0071] (3) After shielding the side of the sample obtained in (2) where the Ta-Ti alloy transition layer has not formed, fix it to the hanger, move it to the closed reaction chamber and evacuate the inside. When the vacuum reaches 5×10 -3 At a pressure of Pa, the heater is turned on to heat to 500℃ and held at that temperature. Then, Ar, C2H2, and O2 are introduced into the cavity through the gas path and vents, with a flow rate ratio of 7:2:1. Magnetron sputtering deposition is performed using Ir and graphite targets, and the vacuum level is controlled at 0.2 Pa using a vacuum system. At a deposition temperature of 500℃, the deposition current for the Ir target is controlled at 2 A, and the deposition current for the graphite target is controlled at 10 A. The deposition bias voltage is 500 V, and the deposition time is 90 min, forming an Ir-CO composite layer consisting of iridium oxide and amorphous carbon. The thickness of the Ir-CO composite layer is 200 nm, and the contact angle is 30°.

[0072] (4) Prepare two samples obtained in (3). After fixing one sample, move it to a closed reaction chamber. When the vacuum is evacuated to 5×10 -3At Pa, the heater is turned on to heat to 500℃ and held for a period of time. Then, Ar gas and CF4 are introduced into the cavity through the gas path and gas hole to perform surface hydrophobic treatment. The vacuum degree of the process is controlled at 0.1 Pa. At the deposition temperature of 500℃, a bias voltage of 800V is applied and the processing time is 60 min. The contact angle of the obtained sample is 120°.

[0073] (5) Take 10 samples obtained in (3) and 10 samples obtained in (4) and stack them alternately to obtain a gas diffusion layer.

[0074] Figure 5 This is an electron microscope schematic diagram of the Ir-CO composite layer prepared in Example 1, as shown. Figure 5 As shown, the Ir-CO composite layer has a porous structure.

[0075] Example 2 Unlike Example 1, in (5), 12 samples obtained in (3) and 8 samples obtained in (4) are stacked alternately to obtain a gas diffusion layer.

[0076] Example 3 Unlike Example 1, in (2): the titanium fiber felt electrode plate is fixed to the hanger, moved to the closed reaction chamber and its interior is evacuated. When the vacuum reaches 5×10 -3 At Pa, the heater is turned on to heat to 300℃ and held at that temperature. Then, Ar gas is introduced into the cavity through the gas path and gas hole. Magnetron sputtering deposition is performed using Nb and Ta targets. The vacuum degree of the process is controlled to be 0.1 Pa by the gas extraction system. At the deposition temperature of 300℃, the deposition current of Nb target is controlled to be 6A and the deposition current of Ta target is controlled to be 2A. The deposition bias voltage is stacked in three layers of 1200V / 500V / 200V, and the deposition time of each layer is 30min to form a Ta-Nb alloy transition layer with a thickness of 150nm.

[0077] Example 4 Unlike Example 1, in (3), the side of the sample obtained in (2) without the formation of the Ta-Ti alloy transition layer was shielded and fixed to the hanger. It was then moved to a closed reaction chamber and its interior was evacuated. When the vacuum reached 5×10 -3At a pressure of Pa, the heater is turned on to heat to 500℃ and held at that temperature. Then, Ar, C2H2, and O2 are introduced into the cavity through the gas path and vent. Magnetron sputtering deposition is performed using Pt and graphite targets, with the vacuum level controlled at 0.2 Pa via the evacuation system. At the deposition temperature of 500℃, the deposition current for the Pt target is controlled at 2 A, and the deposition current for the graphite target is controlled at 10 A. The deposition bias voltage is 500 V, and the deposition time is 90 min, forming a Pt-CO composite layer. The Pt-CO composite layer consists of platinum oxide and amorphous carbon. The thickness of the Pt-CO composite layer is 200 nm, and the contact angle is 40°.

[0078] Example 5 Unlike Example 1, in (3), the side of the sample obtained in (2) without the formation of the Ta-Ti alloy transition layer was shielded and fixed to the hanger. It was then moved to a closed reaction chamber and its interior was evacuated. When the vacuum reached 5×10 -3 At Pa, the heater is turned on to heat to 500℃ and held at that temperature. Then, Ar, C2H2, and O2 are introduced into the cavity through the gas path and vent. Magnetron sputtering deposition is performed using Ru and graphite targets, and the vacuum level of the process is controlled at 0.2 Pa by the gas extraction system. At the deposition temperature of 500℃, the deposition current of the Ru target is controlled at 2A, the deposition current of the graphite target is controlled at 10A, the deposition bias voltage is 500V, and the deposition time is 90min, forming a Ru-CO composite layer. The Ru-CO composite layer includes ruthenium oxide and amorphous carbon. The thickness of the Ru-CO composite layer is 200nm, and the contact angle of the Ru-CO composite layer is 50°.

[0079] Example 6 Unlike Example 1, in (3), the side of the sample obtained in (2) without the formation of the Ta-Ti alloy transition layer was shielded and fixed on a hanger. It was then moved to an acidic solution of iridium chloride (H2IrCl3) and tantalum pentachloride (TaCl5) with a metal mass ratio of Ir:Ta = 7:3. The prepared coating solution was evenly brushed onto the surface of the titanium substrate, dried at 80°C to remove the organic solvent, and the above steps were repeated 15 times. Finally, it was dried at 120°C for 3 hours to obtain an Ir-Ta-O composite layer, which includes iridium oxide and tantalum oxide. The contact angle of the Ir-Ta-O composite layer is 30°.

[0080] Example 7 Unlike Example 1, in (4), the sample obtained in (3) was moved into an acidic solution of hydrofluoric acid and polytetrafluoroethylene, and the prepared coating solution was evenly brushed onto the surface of the Ir-CO composite layer for hydrophobic treatment. It was dried at 80°C to remove the organic solvent. The above steps were repeated 5 times, and finally dried at 200°C for 3 hours under a nitrogen atmosphere. The contact angle of the sample obtained in (4) was 150°.

[0081] Example 8 Unlike Example 1, in step (3), the flow ratio of Ar gas, C2H2 and O2 is 6:2:2, and the contact angle of the Ir-CO composite layer is 10°.

[0082] Example 9 Unlike Example 1, in step (3), the flow ratio of Ar gas, C2H2 and O2 is 15:4:1, and the contact angle of the Ir-CO composite layer is 50°.

[0083] Example 10 Unlike Example 1, the processing time in step (4) is 90 min and the contact angle of the Ir-CO composite layer is 150°.

[0084] Example 11 Unlike Example 1, the processing time in step (4) is 45 min, and the contact angle of the Ir-CO composite layer becomes 100°.

[0085] Comparative Example 1 (1) Select titanium fiber felt with uniform thickness and ultrasonically clean it in ethanol and water to remove surface grease and surface debris.

[0086] Comparative Example 2 (1) Select titanium fiber felt with uniform thickness and ultrasonically clean it in ethanol and water to remove surface grease and surface debris.

[0087] (2) Fix the titanium fiber felt electrode plate to the hanger, move it to the closed reaction chamber and evacuate the inside. When the vacuum reaches 5×10 -3 At Pa, the heater is turned on to heat to 300℃ and held at that temperature. Then, Ar gas is introduced into the cavity through the gas path and gas hole. Magnetron sputtering deposition is performed using Ti and Ta targets. The vacuum degree of the process is controlled to be 0.1 Pa by the gas extraction system. At the deposition temperature of 300℃, the deposition current of Ti target is controlled to be 6A and the deposition current of Ta target is controlled to be 2A. The deposition bias voltage is stacked in three layers of 1200V / 500V / 200V, and the deposition time of each layer is 30min to form a Ta-Ti alloy transition layer with a thickness of 150nm.

[0088] (3) After shielding the side of the sample obtained in (2) where the Ta-Ti alloy transition layer has not formed, fix it to the hanger, move it to the closed reaction chamber and evacuate the inside. When the vacuum reaches 5×10 -3At Pa, the heater is turned on to heat to 500℃ and held at that temperature. Then, Ar, C2H2, and O2 are introduced into the cavity through the gas path and gas holes. The flow ratio of Ar, C2H2, and O2 is 7:2:1. Magnetron sputtering deposition is performed using Ir and graphite targets. The vacuum degree of the process is controlled to be 0.2 Pa by the gas extraction system. At the deposition temperature of 500℃, the deposition current of the Ir target is controlled to be 2A, the deposition current of the graphite target is controlled to be 10A, the deposition bias voltage is 500V, and the deposition time is 90min, forming an Ir-CO composite layer with a thickness of 200nm and a contact angle of 30°.

[0089] Comparative Example 3 (1) Select titanium fiber felt with uniform thickness and ultrasonically clean it in ethanol and water to remove surface grease and surface debris.

[0090] (2) Fix the titanium fiber felt electrode plate to the hanger, move it to the closed reaction chamber and evacuate the inside. When the vacuum reaches 5×10 -3 At Pa, the heater is turned on to heat to 300℃ and held at that temperature. Then, Ar gas is introduced into the cavity through the gas path and gas hole. Magnetron sputtering deposition is performed using Ti and Ta targets. The vacuum degree of the process is controlled to be 0.1 Pa by the gas extraction system. At the deposition temperature of 300℃, the deposition current of Ti target is controlled to be 6A and the deposition current of Ta target is controlled to be 2A. The deposition bias voltage is stacked in three layers of 1200V / 500V / 200V, and the deposition time of each layer is 30min to form a Ta-Ti alloy transition layer with a thickness of 150nm.

[0091] (3) After shielding the side of the sample obtained in (2) where the Ta-Ti alloy transition layer has not formed, fix it to the hanger, move it to the closed reaction chamber and evacuate the inside. When the vacuum reaches 5×10 -3 At Pa, the heater is turned on to heat to 500℃ and held at that temperature. Then, Ar, C2H2 and O2 are introduced into the cavity through the gas path and gas holes. The flow ratio of Ar, C2H2 and O2 is 7:2:1. Magnetron sputtering deposition is performed using Ir and graphite targets. The vacuum degree of the process is controlled to be 0.2 Pa by the gas extraction system. At the deposition temperature of 500℃, the deposition current of Ir target is controlled to be 2A and the deposition current of graphite target is controlled to be 10A. The deposition bias voltage is 500V and the deposition time is 90min to form an Ir-CO composite layer.

[0092] (4) After fixing the sample obtained in (3), move it to the closed reaction chamber, and when the vacuum is evacuated to 5×10 -3At Pa, the heater is turned on to heat to 500℃ and held for a period of time. Then, Ar gas and CF4 are introduced into the cavity through the gas path and gas hole to perform surface hydrophobic treatment. The vacuum degree of the process is controlled at 0.1 Pa. At the deposition temperature of 500℃, a bias voltage of 800V is applied and the treatment time is 60 min, so that the contact angle of the Ir-CO composite layer is 120°.

[0093] Performance testing: 1. Contact resistivity test: 5cm × 5cm carbon paper was placed on both sides of the gas diffusion layer sample as supports. During the test, a resistance value was recorded for every 0.1 MPa increase in pressure. The test continued until the rate of change of the current resistance value relative to the previous resistance value was ≤5%, at which point the minimum resistance value was considered reached, and the test was stopped. In this application, the resistance value at a final pressure of 1.4 MPa is recorded as the contact resistance M (mΩ), and the contact resistivity A = M × 5 × 5, where A is in mΩ·cm. 2 .

[0094] 2. Corrosion resistance test: The gas diffusion layer sample was used as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet or platinum mesh as the auxiliary electrode. The electrodes were placed at 80°C and F. - The test was conducted in an H2SO4 electrolyte solution with a concentration of 0.1 mg / L and a pH of 3. First, an open-circuit potential test was performed. The test was considered stable if the potential changed by no more than 5 mV within 2 minutes and the test lasted for at least 30 minutes. Then, a corrosion current density test was started by applying 1.6 V. The test time was 24 hours, and the corrosion current density was recorded.

[0095] 3. Catalytic activity test: Assemble the gas diffusion layer, proton exchange membrane, and electrodes (e.g.) Figure 4 The image shown is of an integrated reversible fuel cell. Catalytic activity was tested in fuel cell mode: hydrogen was introduced at the anode and air at the cathode. Under different external loads, the voltage output by the battery was recorded in increments of 1 A / cm². 2 The stable output voltage of the integrated reversible fuel cell under certain conditions is used as an indicator of catalytic activity. Catalytic activity testing was conducted in electrolyzer mode: with water flowing through the anode and an external voltage applied, the applied voltage at different current densities was recorded. The stable output voltage of the integrated reversible fuel cell at 1 A / cm² was used as an indicator of catalytic activity.

[0096] The gas diffusion layers prepared in each embodiment and comparative example were subjected to the above-described performance tests, and the test results are shown in Table 1.

[0097] Table 1. Performance test results of the examples and comparative examples

[0098] Figure 6 The polarization curves of the gas diffusion layer in Example 1 and Comparative Example 1 under electrolytic cell mode are shown below. Figure 6 As shown, compared to Comparative Example 1, Example 1 has a lower voltage in the electrolysis cell mode, indicating that the gas diffusion layer of Example 1 has lower energy consumption, higher current efficiency, and better long-term stability, making it fully suitable for integrated reversible fuel cells.

[0099] Figure 7 The polarization curves of the gas diffusion layer in Example 1 and Comparative Example 1 under fuel cell mode are shown below. Figure 7 As shown, compared to Comparative Example 1, Example 1 has a higher voltage in fuel cell mode, indicating that the gas diffusion layer of Example 1 has a lower operating voltage, smoother mass transfer, and more stable operation, making it fully applicable to integrated reversible fuel cells.

[0100] Compared to Examples 1 to 11, the voltage of Comparative Example 2 in fuel cell mode is significantly lower than that of Examples 1 to 11, indicating that Comparative Example 2 has a larger polarization loss and poorer mass transfer performance.

[0101] Compared to Examples 1 to 11, the voltage of Comparative Example 3 in the electrolysis cell mode is significantly higher than that of Examples 1 to 11, indicating that Comparative Example 3 requires a higher voltage to drive the electrolysis reaction and its water electrolysis efficiency is lower.

[0102] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gas diffusion layer, characterized in that, The gas diffusion layer includes at least one first functional layer and at least one second functional layer; The first functional layer comprises, in sequence, a first titanium-based porous material, a first transition layer, and a first composite layer; The second functional layer comprises, in sequence, a second titanium-based porous material, a second transition layer, and a second composite layer; At least one of the first transition layer and the second transition layer comprises a Ta-M alloy, wherein M comprises at least one of Ti and Nb; At least one of the first composite layer and the second composite layer includes a porous layer comprising an oxide of a platinum group element, wherein carbon is distributed on the surface and in the pores of the porous layer, and the platinum group element includes at least one of Pt, Ir, and Ru; or At least one of the first composite layer and the second composite layer comprises oxides of platinum group elements and tantalum oxide, wherein the platinum group elements include at least one of Pt, Ir and Ru; The second composite layer further includes a hydrophobic material, which is polytetrafluoroethylene. The contact angle of the first composite layer is 0~60°, and the contact angle of the second composite layer is 90°~180°.

2. The gas diffusion layer according to claim 1, characterized in that, The gas diffusion layer includes at least one of the following features: (1) The loading of the platinum group element oxides in the first composite layer is less than or equal to 2 g / m 2 The loading of the platinum group element oxides in the second composite layer is less than or equal to 2 g / m². 2 ; (2) The hydrophobic material is connected to the second composite layer by adsorption and / or chemical bonds; (3) The thickness of the first functional layer is 150nm~250nm; (4) The thickness of the second functional layer is 150nm~250nm.

3. The gas diffusion layer according to claim 1, characterized in that, The tantalum oxide accounts for more than or equal to 30 wt% of the mass of the first composite layer, and the tantalum oxide accounts for more than or equal to 30 wt% of the mass of the second composite layer.

4. The gas diffusion layer according to claim 1, characterized in that, The gas diffusion layer includes at least one of the following features: (1) The atomic content of Ta in the Ta-M alloy is 30 at%~65 at%; (2) Along the direction from the first titanium-based porous material to the first composite layer, the atomic content of Ta in the first transition layer decreases; (3) Along the direction of the second titanium-based porous material toward the second composite layer, the atomic content of Ta element in the second transition layer decreases; (4) The thickness of the first transition layer is 100nm~200nm; (5) The thickness of the second transition layer is 100nm~200nm.

5. The gas diffusion layer according to claim 1, characterized in that, The gas diffusion layer includes at least one of the following features: (1) The first functional layer and the second functional layer are alternately set; (2) The number of the first functional layers is greater than or equal to the number of the second functional layers.

6. A method for preparing a gas diffusion layer, characterized in that, Includes the following steps: Provide titanium-based porous materials; Forming a transition layer on the surface of the titanium-based porous material, the step of forming the transition layer includes: Under vacuum conditions and in an argon atmosphere, Ta and M metal targets are used to deposit on the surface of the titanium-based porous material, the deposition including magnetron sputtering; A composite layer is formed on the surface of the transition layer to obtain an intermediate part, wherein the contact angle of the composite layer is 0~60°; The steps for forming the composite layer include: depositing platinum group metal targets and graphite targets on the surface of the transition layer under vacuum conditions in a mixed gas atmosphere of argon, acetylene, and oxygen; or The steps for forming the composite layer include: coating the surface of the transition layer with an oxyacid solution containing platinum group elements and a salt solution containing tantalum, performing a first heat treatment, repeating the coating and first heat treatment steps 10 to 20 times, and then performing a second heat treatment. Two intermediate components are provided. The surface of the composite layer of one of the intermediate components is hydrophobically treated with a fluorine-containing substance to obtain a second functional layer. The contact angle of the composite layer after hydrophobic treatment is 90°~180°. The other intermediate component serves as the first functional layer. A gas diffusion layer is obtained by stacking at least one first functional layer and at least one second functional layer.

7. The method for preparing the gas diffusion layer according to claim 6, characterized in that, In the step of forming the transition layer, the deposition current of the Ta target is 1A~4A, the M includes at least one of Ti and Nb, the deposition current of the M metal target is 5A~8A, the deposition temperature is 200℃~400℃, and the deposition bias voltage includes a first bias voltage, a second bias voltage and a third bias voltage set sequentially. The first bias voltage is 1000V~1300V, the second bias voltage is 400V~600V, and the third bias voltage is 100V~300V. The deposition time under the first bias voltage is 20min~40min, the deposition time under the second bias voltage is 20min~40min, and the deposition time under the third bias voltage is 20min~40min.

8. The method for preparing the gas diffusion layer according to claim 6, characterized in that, In the step of forming the composite layer, the volume ratio of argon, acetylene and oxygen is (6~16):(1~6):(0.5~2), the deposition includes magnetron sputtering, the deposition current of the platinum group metal target is 1A~3A, the deposition current of the graphite target is 5A~15A, the deposition temperature is 300℃~800℃, the deposition bias voltage is 400V~600V, and the deposition time is 60min~120min.

9. The method for preparing the gas diffusion layer according to claim 6, characterized in that, The temperature of the first heat treatment is 70℃~90℃, and the temperature of the second heat treatment is 100℃~150℃.

10. An integrated reversible fuel cell, characterized in that, The integrated reversible fuel cell includes: The first and second bipolar plates are set relative to each other; A proton exchange membrane located between the first bipolar plate and the second bipolar plate; A first gas diffusion layer located between the first bipolar plate and the proton exchange membrane; and a second gas diffusion layer located between the second bipolar plate and the proton exchange membrane, wherein at least one of the first gas diffusion layer and the second gas diffusion layer comprises a gas diffusion layer prepared by the method of preparing the gas diffusion layer according to any one of claims 1 to 5 or the gas diffusion layer according to any one of claims 6 to 9.

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