Gas diffusion layer with gradient inclined holes built inside and application of gas diffusion layer

Abstract

The invention discloses a gas diffusion layer with gradient inclined holes built inside. The gas diffusion layer comprises a porous gas diffusion layer (2), the gradient inclined holes (3), super-hydrophilic stripes (6) and super-hydrophobic stripes (7). A plurality of gradient inclined holes (3) are distributed in the porous gas diffusion layer (2), and each gradient inclined hole (3) comprises an outer opening (31) and an inner hole (32); and the super-hydrophilic stripes (6) and the super-hydrophobic stripes (7) cover the front surface of the porous gas diffusion layer (2). According to the gas diffusion layer, an ordered bubble overflow micro-flow field is self-built through internal gradient inclined holes, a super-hydrophilic / super-hydrophobic stripe induction solution is supplemented into the gas diffusion layer in an ordered and directional mode, an ordered channel that gas flows through a gas path and liquid flows through a liquid path is achieved, an efficient gas and ion transmission path is built, and gas export and mass transfer efficiency is remarkably improved. Meanwhile, the gas diffusion layer has the advantages of being simple in preparation method, low in cost and suitable for large-scale application, and has wide market application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by electrolysis of water, in particular to the field of gas diffusion layers, and specifically relates to a gas diffusion layer with gradient inclined holes constructed inside and application thereof. Background Art

[0002] As a clean and renewable energy source, hydrogen energy is gaining increasing attention worldwide. With the intensification of climate change and the pursuit of sustainable development goals, hydrogen energy is considered an important solution to achieve a low-carbon economy and energy transformation. According to a report by the International Energy Agency (IEA), the market size of hydrogen energy is expected to grow significantly in the next decade, especially in the fields of transportation, industry and energy storage. At the same time, governments around the world have launched hydrogen energy development strategies in an effort to take a leading position in this emerging field.

[0003] Hydrogen production by water electrolysis is widely regarded as an important way to obtain "green hydrogen". Hydrogen production by water electrolysis can not only effectively utilize renewable energy, but also provide a flexible energy storage solution for the power system to help balance supply and demand. The efficiency and economy of hydrogen production by water electrolysis depend to a large extent on the size of the current and the control of energy consumption. In recent years, high current and low energy consumption have been the development trend of hydrogen production by water electrolysis. By increasing the current density of the electrolyzer, the production rate of hydrogen can be significantly increased, thereby reducing the unit production cost of hydrogen.

[0004] However, the gas diffusion layer (GDL) plays a vital role in the process of hydrogen production by water electrolysis. The performance of the GDL directly affects the current distribution and energy efficiency. In the water electrolysis device, the gas diffusion layer is responsible for transporting electrons and fresh electrolyte to the catalyst surface, while exporting gas products (hydrogen or oxygen bubbles) from the catalyst surface, acting as a channel for electrons, ions and gases. GDL is usually composed of materials such as foam metal, metal fiber felt, carbon paper or carbon cloth, and its interior usually has a three-dimensional disordered pore structure with high porosity. Because this disordered structure lacks specially designed gas channels and ion channels, bubbles are easily accumulated in the internal solution, which affects the discharge of gas and the supply of ions. This problem is particularly obvious under high current conditions, and may even cause the gas to completely block the interior, hindering the increase in current density, and significantly increasing the reaction energy consumption.

[0005] In particular, the new generation of proton exchange membrane (PEM) and anion exchange membrane (AEM) technologies can produce hydrogen with a current density of up to 20,000A / m 2 , is the current density of traditional alkaline water electrolysis hydrogen production (ALK) (200A / m 2) by 5 to 10 times. This significant improvement places higher demands on the gas introduction and mass transfer capabilities of the gas diffusion layer. Therefore, there is an urgent need for a universal gas diffusion layer with low cost and carefully designed gas and droplet channels to improve gas conduction and mass transfer efficiency to meet the needs of high current and low energy consumption hydrogen production.

[0006] In order to solve the above problems, the present invention is proposed. Summary of the invention

[0007] In the field of hydrogen production by water electrolysis, the traditional gas diffusion layer is prone to bubble blockage due to its disordered internal structure. This blockage phenomenon not only hinders the rapid discharge of gas products, but also limits the effective introduction of reactive ions, resulting in a significant reduction in the mass transfer efficiency inside the gas diffusion layer. As a result, the energy consumption of water electrolysis hydrogen production equipment increases, affecting the overall energy efficiency and economy.

[0008] The present invention discloses a design of an efficient mass transfer gas diffusion layer, which aims to improve the transmission efficiency of gas and ions by constructing gradient inclined holes and self-constructing micro-convection internally. The present invention discloses a gas diffusion layer with internally constructed gradient inclined holes, which comprises: a porous gas diffusion layer 2, gradient inclined holes 3, super-hydrophilic stripes 6 and super-hydrophobic stripes 7; a plurality of gradient inclined holes 3 are distributed on the porous gas diffusion layer 2, the outer opening 31 of the gradient inclined holes 3 is located on the front of the porous gas diffusion layer 2, and the inner hole 32 of the gradient inclined holes 3 is located inside the porous gas diffusion layer 2; the super-hydrophilic stripes 6 and the super-hydrophobic stripes 7 cover the front of the porous gas diffusion layer 2. The gas diffusion layer self-constructs an orderly bubble overflow microflow field through the internal gradient inclined holes, and induces the solution to replenish the gas diffusion layer in an orderly and directional manner through the super-hydrophilic / super-hydrophobic stripes, so as to realize an orderly channel in which gas goes through a gas path and liquid goes through a liquid path, and constructs an efficient transmission path for gas and ions, significantly improving the gas extraction and mass transfer efficiency. The results show that the size of the bubbles is reduced from 50μm in the conventional gas diffusion layer to 18μm by using the gradient oblique hole gas diffusion layer. At the same overpotential, the current density is increased to 2.1 times of the original, thereby greatly improving the reaction performance. At the same time, the gas diffusion layer has the advantages of simple preparation method, low cost and suitability for large-scale application, and has broad market application prospects.

[0009] The first aspect of the present invention provides a gas diffusion layer with gradient oblique holes constructed therein, comprising: a porous gas diffusion layer 2, gradient oblique holes 3, super hydrophilic stripes 6 and super hydrophobic stripes 7;

[0010] The porous gas diffusion layer 2 serves as the main body of the gas diffusion layer with gradient oblique holes constructed inside;

[0011] A plurality of the gradient inclined holes 3 are distributed on the porous gas diffusion layer 2, the outer openings 31 of the gradient inclined holes 3 are located on the front side of the porous gas diffusion layer 2, and the inner holes 32 of the gradient inclined holes 3 are located inside the porous gas diffusion layer 2;

[0012] The gradient inclined hole 3 is a through hole, and the diameter of the outer opening 31 is larger than the diameter of the inner hole 32, forming a gradient structure from inside to outside;

[0013] The gradient inclined holes 3 form a certain angle with the front surface of the porous gas diffusion layer 2;

[0014] The super-hydrophilic stripes 6 and the super-hydrophobic stripes 7 cover the front side of the porous gas diffusion layer 2 , wherein the super-hydrophilic stripes 6 cover between two adjacent columns of the gradient inclined holes 3 , and the super-hydrophobic stripes 7 cover above each column of the gradient inclined holes 3 .

[0015] Preferably, the angle between the gradient inclined holes 3 and the front surface of the porous gas diffusion layer 2 is 0° to 90°.

[0016] Preferably, the porous gas diffusion layer 2 can be made of various materials, including but not limited to: foam metal, metal fiber felt, carbon paper or carbon cloth and other materials with three-dimensional disordered pores inside. The thickness of the porous gas diffusion layer 2 is 50μm-1000μm, and the porosity of the porous gas diffusion layer 2 is 10% to 95%.

[0017] Preferably, the surface properties of the front side of the porous gas diffusion layer 2 can be various, including but not limited to the properties of the material itself, hydrophilic, hydrophobic, super hydrophilic, super hydrophobic and other surface properties, and the surface properties of the three-dimensional structure surface inside the porous gas diffusion layer 2 can be the properties of the material itself or hydrophilic or super hydrophilic properties. The microstructure of the porous gas diffusion layer 2 can be the microstructure of the material itself, or can be a structure such as an in-situ grown nanoarray.

[0018] Preferably, the gradient inclined hole 3 can be diverse, and the shape of the outer opening 31 of the gradient inclined hole 3 can be circular, elliptical, rectangular, ordered polygonal and disordered polygonal, etc. The opening diameter of the outer opening 31 ranges from 10μm to 500μm; when the shape of the outer opening 31 is non-circular, the opening diameter here refers to the equivalent diameter.

[0019] The shape of the inner hole 32 of the gradient inclined hole 3 can be circular, elliptical, rectangular, ordered polygonal and disordered polygonal, etc., and the opening diameter of the inner hole 32 ranges from 0μm to 500μm; when the shape of the inner hole 32 is non-circular, the opening diameter here refers to the equivalent diameter.

[0020] The outer opening 31 of the gradient inclined hole 3 and the inner hole 32 of the gradient inclined hole 3 are interconnected, presenting a gradient aperture structure.

[0021] Preferably, the arrangement of the plurality of gradient inclined holes 3 includes an ordered or disordered arrangement method, which may be a horizontal, vertical, tic-tac-toe arrangement, or other staggered arrangement, etc.;

[0022] When the plurality of gradient inclined holes 3 are arranged in a horizontal and vertical well-shaped arrangement, the horizontal spacing is 1 μm to 5 mm, and the vertical spacing is 1 μm to 5 mm.

[0023] Preferably, the width of the super-hydrophilic stripes 6 is between 10 μm and 10 mm, and the super-hydrophilic stripes 6 can be arranged in uniform stripes or in non-uniform stripes; the super-hydrophilic stripes 6 can be in stripe shape or in other shapes, including but not limited to: dots, circles, ellipses, rectangles, ordered polygons or disordered polygons;

[0024] The surface wettability of the super hydrophobic stripes 7 is measured by the droplet contact angle, and the contact angle of the super hydrophilic stripes 6 is between 0° and 90°. The manufacturing method of the super hydrophilic stripes 6 includes but is not limited to: using ultrasonic spraying super hydrophilic coating or in-situ growth of super hydrophilic nano array structure.

[0025] Preferably, the width of the super-hydrophobic stripes 7 is between 10 μm and 10 mm, and the super-hydrophobic stripes 7 can be arranged in uniform stripes or in non-uniform stripes; the super-hydrophobic stripes 7 can be in stripe shape or in other shapes, including but not limited to: dots, circles, ellipses, rectangles, ordered polygons and / or disordered polygons;

[0026] The surface wettability of the super-hydrophobic stripes 7 is measured by the contact angle of the liquid drop, and the contact angle of the super-hydrophobic stripes 7 is between 90° and 180°. The manufacturing method of the super-hydrophobic stripes 7 includes but is not limited to: using ultrasonic spraying of super-hydrophobic coating or in-situ growth of super-hydrophilic nano-array structure.

[0027] The second aspect of the present invention provides an application of the gas diffusion layer with internally constructed gradient slanted holes as described in the first aspect of the present invention, wherein the gas diffusion layer with internally constructed gradient slanted holes is used in a water electrolysis device, including a traditional alkaline water electrolysis device, a proton exchange membrane water electrolysis device or an anion exchange membrane water electrolysis device.

[0028] In addition, the gas diffusion layer with gradient inclined holes constructed therein can also be used in any device requiring a gas production reaction.

[0029] Preferably, in the water electrolysis device, the inner hole 32 faces one side of the water electrolysis device diaphragm 1, and the outer opening 31 faces the outside of the water electrolysis device diaphragm 1, forming a gradient structure from inside to outside;

[0030] The gas diffusion layer with internally constructed gradient oblique holes is used in a water electrolysis device to reduce the average size of bubbles passing through the gas diffusion layer with internally constructed gradient oblique holes and to increase the current density at the same overpotential.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention constructs an efficient gas-conducting channel, thereby significantly reducing the overflow size of bubbles. The present invention arranges ordered inclined holes in the gas diffusion layer, so that bubbles can quickly overflow outward along the gradient inclined holes under the action of buoyancy. Since the diameter of the gradient inclined holes gradually decreases from the outer opening to the inner hole, the problem of siltation caused by bubbles merging and becoming larger during operation is effectively solved, and the phenomenon of bubbles being stuck in the gas diffusion layer is reduced. At the same time, as a large number of bubbles form an ordered bubble flow through the inclined holes, the surface flow velocity inside the gas diffusion layer is enhanced, further reducing the average size of the bubbles from 50μm to 18μm, preventing bubble blockage and improving overall energy consumption.

[0033] 2. The present invention constructs an ordered microfluid inside the gas diffusion layer, which significantly enhances its mass transfer capacity. The movement of the ordered bubble flow through the gradient inclined holes drives the surrounding fluid, providing a stronger mass transfer effect inside the gas diffusion layer. At the same time, the surface coverage of superhydrophilic stripes and superhydrophobic stripes is coupled with the gradient inclined hole design, so that fresh electrolyte can effectively enter through the superhydrophilic stripes, while bubbles can smoothly overflow through the gradient stripe holes under the superhydrophobicity. This design realizes the construction of an ordered microflow field inside the gas diffusion layer, greatly improving the mass transfer efficiency. Under the same overpotential, the current density is increased to 2.1 times the original, significantly improving the overall performance of hydrogen production by water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The left figure is a schematic diagram of the structure of the ordered gradient oblique hole gas diffusion layer and a schematic diagram of the side section working principle. The right figure is a schematic diagram of the side section working principle of a part of the ordered gradient oblique hole gas diffusion layer.

[0035] Figure 2 Schematic diagram of the surface structure of super-hydrophilic / super-hydrophobic alternating stripes on the front side of the ordered gradient oblique hole gas diffusion layer;

[0036] Figure 3 Schematic diagram of the structure without surface stripes and the schematic diagram of the ordered fluid field brought about by the surface structure with super-hydrophilic / super-hydrophobic alternating stripes. The left figure is a schematic diagram of the flow field of the structure without surface stripes, and the right figure is a schematic diagram of the ordered fluid field brought about by the surface structure with super-hydrophilic / super-hydrophobic alternating stripes;

[0037] Figure 4It is the bubble statistics diagram on the surface and inside of different gas diffusion layers;

[0038] Figure 5 This is a comparison chart of hydrogen performance curves of different gas diffusion layers;

[0039] Figure 6 The left picture shows the bubbles in the conventional gas diffusion layer and the ordered gradient inclined hole gas diffusion layer. The right picture shows the bubbles in the ordered gradient inclined hole gas diffusion layer.

[0040] Figure 7 The left figure is the principle diagram of bubble overflow of conventional gas diffusion layer and ordered gradient inclined hole gas diffusion layer, and the right figure is the principle diagram of bubble overflow of ordered gradient inclined hole gas diffusion layer;

[0041] The names of the figure marks in the figure description: 1. Water electrolysis device diaphragm, 2. Porous gas diffusion layer, 3. Gradient inclined hole, 31. Gradient inclined hole outer opening, 32. Gradient inclined hole inner hole, 4. Bubble high-speed overflow path, 5. Bubble, 51. Tiny bubble, 52. Large bubble, 53. Super large bubble, 6. Super hydrophilic stripes, 7. Super hydrophobic stripes, 8. Electrolyte replenishes the running direction from the side of the gradient inclined hole, 9. Gradient inclined hole inclination angle, 10. Electrolyte replenishes the running direction from the front of the gradient inclined hole. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with embodiments.

[0043] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the art or the product specifications are used. If the manufacturer of the materials or equipment used is not specified, they are all conventional products that can be purchased.

[0044] Those skilled in the art will appreciate that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" to another element, it may be directly connected to the other element, or there may be intermediate elements. In addition, the "connection" used herein may include wireless connections.

[0045] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two. The terms "inside", "upper", "lower", etc., indicating positions or state relationships, are based on the positions or state relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operate in a specific position, and therefore cannot be understood as limiting the present invention.

[0046] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "provided with" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention will be understood according to specific circumstances.

[0047] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0048] Example

[0049] Combination Figures 1 to 7 As shown, a design of an efficient mass transfer gas diffusion layer with self-built micro-convection with gradient inclined holes is provided, and the gas diffusion layer comprises: a porous gas diffusion layer 2, a gradient inclined hole 3, a super hydrophobic stripe 7 and a super hydrophilic stripe 6. The porous gas diffusion layer 2 is used as the main body of the gas diffusion layer, and a plurality of gradient inclined holes 3 are evenly distributed on its surface. The outer opening 31 of the gradient inclined hole is located on the front of the porous gas diffusion layer, and the inner hole 32 is located inside the porous gas diffusion layer. The gradient inclined hole is a through hole, and the outer opening diameter is larger than the inner hole diameter. In the water electrolysis device, the inner hole faces one side of the water electrolysis device diaphragm 1, and the outer opening faces the outside of the water electrolysis device diaphragm 1, forming a gradient structure from the inside to the outside. The gradient inclined hole is at a certain angle to the front of the porous gas diffusion layer, and the gradient inclined hole inclination angle 9 described in this embodiment is 60°. In addition, the surface of the porous gas diffusion layer is covered with super hydrophilic stripes and super hydrophobic stripes, wherein the super hydrophilic stripes cover between each column of gradient inclined holes, and the super hydrophobic stripes cover above each column of gradient inclined holes.

[0050] In the specific implementation process, firstly, a 1mm thick nickel foam is selected as the substrate of the gas diffusion layer, and the porosity of the porous gas diffusion layer 2 is 95%. A needle row is used, the front end of which is a sharp point, the diameter gradually increases, and the bottom end is a circle with a diameter of 500μm. The needle row is inserted into the nickel foam at an angle of 60°, and then taken out at the same angle, and this operation is repeated many times to form an ordered gradient inclined hole array. The outer opening 31 of the formed gradient inclined hole 3 is circular in shape, and the opening diameter of the outer opening 31 is 500μm, and the inner hole 32 is circular in shape, and the opening diameter of the inner hole 32 is 500μm.

[0051] Next, the nickel foam is internally modified by immersing it in a solution of nickel nitrate and ferric nitrate using a hydrothermal method, setting the reaction temperature to 120°C and the reaction time to 12 hours to obtain a super-hydrophilic nanoarray structure inside and on the surface of the nickel foam. Subsequently, a polyimide tape with stripe holes is used to cover the surface of the nickel foam, ensuring that the size and spacing of the stripe holes on the tape match the arrangement of the gradient oblique holes to ensure that there is a corresponding tape stripe hole above each inclined hole. Finally, a 1% concentration of polytetrafluoroethylene suspension is evenly sprayed on the polyimide tape using a spray gun. After removing the tape, the coating is dried at 360°C for 1 hour to finally obtain a gradient oblique hole nickel foam gas diffusion layer with super-hydrophilic / super-hydrophobic stripes, which is then assembled into a water electrolysis device for use. The super-hydrophilic stripe 6 is 500um wide, and the super-hydrophilic stripes 6 are arranged as uniform stripes. The super-hydrophobic stripes 7 are 500μm wide, and the super-hydrophobic stripes 7 are arranged as uniform stripes.

[0052] When the water electrolysis device is working, the working process and principle of the gas diffusion electrode are as follows. Bubbles will fill the gas diffusion layer. Traditional gas diffusion electrodes, such as Figure 6 As shown in the left figure, due to its disordered structure, the overflow of bubbles 5 inside the gas diffusion layer is hindered, causing the internal tiny bubbles 51 to merge continuously and become large bubbles 52 or even super large bubbles 53, thereby affecting the gas discharge and mass transfer efficiency, as shown in Figure 7 Left figure. In contrast, in the gas diffusion electrode of the present invention, Figure 6 As shown in the right figure, nickel foam with gradient inclined holes 3 is used as the gas diffusion layer. In this design, the buoyancy component of the bubble is consistent with the direction of the gradient inclined hole 3, and the tiny bubble 51 can be quickly discharged outward along the bubble high-speed overflow path 4 of the gradient inclined hole 3 under the action of buoyancy. Since the internal aperture of the gradient inclined hole is small and the external aperture gradually increases, a good gradient structure is formed, which effectively solves the problem of silting caused by the merging and enlargement of bubbles during operation, and reduces the phenomenon of bubbles being stuck in the gas diffusion layer, such as Figure 7As shown in the right figure. As a large number of bubbles pass through the gradient inclined holes 3 to form an ordered bubble flow, the surface velocity inside the gas diffusion layer is enhanced, further reducing the average size of the bubbles, so that desorption is achieved in the form of tiny bubbles 51 inside the gas diffusion layer, reducing it from 50μm in the traditional gas diffusion layer to 18μm, as shown in the figure on the right. Figure 4 The ordered bubble flow through the gradient inclined holes not only improves the discharge of bubbles, but also drives the movement of the surrounding fluid, enhancing the mass transfer effect inside the gas diffusion layer.

[0053] Figure 2 The design shown further optimizes the mass transfer efficiency by using surface coverage of superhydrophilic stripes 6 and superhydrophobic stripes 7, coupled with the design of gradient inclined holes 3, so that fresh electrolyte can effectively enter through the superhydrophilic stripes 6, while bubbles can smoothly overflow through the gradient inclined holes 3 located under the superhydrophobic stripes 7. Figure 3 This fluid motion pattern is demonstrated: Figure 3 In the left figure, in the case of a solution without a surface stripe structure, the entire surface of the gas diffusion layer replenishes the solution inside the diffusion layer. After the electrolyte replenishes from the front of the gradient inclined hole in the direction of 10, the overall solution cannot be brought deep into the gas diffusion layer. After the electrolyte is replenished, it is quickly discharged along the gradient inclined hole 3. However Figure 3 In the right figure, in the gas diffusion layer with a superhydrophilic / superhydrophobic alternating stripe surface structure, the superhydrophobic part cannot enter the solution, and the fresh electrolyte is replenished along the electrolyte from the side of the gradient inclined hole in the running direction 8, and enters the gas diffusion layer through the superhydrophilic stripes, while the bubbles can be discharged smoothly along the gradient inclined holes. In this way, an orderly microflow field is formed inside the gas diffusion layer, and the electrolyte can be replenished deeply into the gas diffusion layer, significantly increasing the flow rate of the electrolyte and bubbles, and enhancing the mass transfer effect in the inclined holes. Ultimately, the performance of hydrogen production by electrolysis of water has been significantly improved. Through the optimized gas diffusion electrode design, the current density is increased to 2.1 times the original under the same overpotential, such as Figure 5 As shown, the efficiency and performance of hydrogen production by water electrolysis are greatly improved.

[0054] In summary, the present invention can spontaneously construct a microflow field in the gas diffusion layer by designing a gas diffusion electrode with gradient inclined holes and combining the surface structure of superhydrophilic / superhydrophobic stripes, thereby achieving effective discharge of bubbles and efficient transmission of gas ions. It not only improves the working state of the gas diffusion layer and reduces the size of the bubbles, but also greatly improves the performance and energy efficiency of hydrogen production by electrolysis of water, and is particularly suitable for working under high current.

Claims

1. A gas diffusion layer with gradient oblique holes constructed inside, characterized in that It comprises: a porous gas diffusion layer (2), gradient oblique holes (3), super-hydrophilic stripes (6) and super-hydrophobic stripes (7); The porous gas diffusion layer (2) serves as the main body of the gas diffusion layer with gradient oblique holes constructed therein; A plurality of the gradient inclined holes (3) are distributed on the porous gas diffusion layer (2), the outer openings (31) of the gradient inclined holes (3) are located on the front side of the porous gas diffusion layer (2), and the inner holes (32) of the gradient inclined holes (3) are located inside the porous gas diffusion layer (2); The gradient inclined hole (3) is a through hole, and the diameter of the outer opening (31) is larger than the diameter of the inner hole (32), forming a gradient structure from inside to outside; The gradient inclined holes (3) form a certain angle with the front surface of the porous gas diffusion layer (2); The super-hydrophilic stripes (6) and the super-hydrophobic stripes (7) are covered on the front side of the porous gas diffusion layer (2), wherein the super-hydrophilic stripes (6) are covered between two adjacent columns of the gradient inclined holes (3), and the super-hydrophobic stripes (7) are covered above each column of the gradient inclined holes (3).

2. The gas diffusion layer with gradient oblique holes constructed inside according to claim 1, characterized in that: The angle between the gradient inclined holes (3) and the front surface of the porous gas diffusion layer (2) is 0° to 90°.

3. The gas diffusion layer with gradient oblique holes constructed inside according to claim 1, characterized in that: The porous gas diffusion layer (2) is made of foam metal, metal fiber felt, carbon paper or carbon cloth with three-dimensional disordered pores inside. The porous gas diffusion layer (2) has a thickness of 50 μm-1000 μm and a porosity of 10% to 95%.

4. The gas diffusion layer with gradient oblique holes constructed therein according to claim 1, characterized in that: The surface properties of the front side of the porous gas diffusion layer (2) include the properties of the material itself, hydrophilic, hydrophobic, super hydrophilic, and super hydrophobic surface properties; the surface properties of the three-dimensional structural surface inside the porous gas diffusion layer (2) are the properties of the material itself or hydrophilic or super hydrophilic properties; the microstructure of the porous gas diffusion layer (2) is the microstructure of the material itself or an in-situ grown nanoarray structure.

5. The gas diffusion layer with gradient oblique holes constructed inside according to claim 1, characterized in that: The shape of the outer opening (31) of the gradient inclined hole (3) is circular, elliptical, rectangular, ordered polygonal and disordered polygonal, and the opening diameter of the outer opening (31) ranges from 10 μm to 500 μm; The shape of the inner hole (32) of the gradient inclined hole (3) is circular, elliptical, rectangular, ordered polygonal and disordered polygonal, and the opening diameter of the inner hole (32) ranges from 0 μm to 500 μm; The outer opening (31) of the gradient inclined hole (3) and the inner hole (32) of the gradient inclined hole (3) are interconnected, presenting a gradient aperture structure.

6. The gas diffusion layer with gradient oblique holes constructed therein according to claim 1, characterized in that: The arrangement of the plurality of gradient inclined holes (3) includes an ordered or disordered arrangement method, such as a horizontal, vertical, tic-tac-toe arrangement or other staggered arrangement; When the plurality of gradient inclined holes (3) are arranged in a horizontal and vertical well-shaped arrangement, the horizontal spacing is 1 μm to 5 mm, and the vertical spacing is 1 μm to 5 mm.

7. The gas diffusion layer with gradient oblique holes constructed therein according to claim 1, characterized in that: The width of the super-hydrophilic stripes (6) is between 10 μm and 10 mm, and the super-hydrophilic stripes (6) are arranged as uniform stripes or uneven stripes; the super-hydrophilic stripes (6) are configured in stripe shapes or other shapes, and other shapes include dots, circles, ellipses, rectangles, ordered polygons or disordered polygons; The surface wettability of the super hydrophobic stripes (7) is measured by a droplet contact angle, and the contact angle of the super hydrophilic stripes (6) is between 0° and 90°. The super hydrophilic stripes (6) are prepared by ultrasonically spraying a super hydrophilic coating or in-situ growing a super hydrophilic nano array structure.

8. The gas diffusion layer with gradient oblique holes constructed therein according to claim 1, characterized in that: The width of the super hydrophobic stripes (7) is between 10 μm and 10 mm, and the super hydrophobic stripes (7) are arranged as uniform stripes or non-uniform stripes; the super hydrophobic stripes (7) are configured in stripe shape or other shapes, and other shapes include dots, circles, ellipses, rectangles, ordered polygons and disordered polygons; The surface wettability of the super-hydrophobic stripes (7) is measured by a droplet contact angle, and the contact angle of the super-hydrophobic stripes (7) is between 90° and 180°. The super-hydrophobic stripes (7) are prepared by ultrasonically spraying a super-hydrophobic coating or in-situ growing a super-hydrophilic nano-array structure.

9. An application of a gas diffusion layer with gradient oblique holes constructed inside as claimed in any one of claims 1 to 8, characterized in that: The gas diffusion layer with gradient oblique holes constructed inside is used in water electrolysis devices, including traditional alkaline water electrolysis devices, proton exchange membrane water electrolysis devices or anion exchange membrane water electrolysis devices.

10. The use according to claim 9, characterized in that: In the water electrolysis device, the inner hole (32) faces one side of the water electrolysis device diaphragm (1), and the outer opening (31) faces the water electrolysis device diaphragm (1), forming a gradient structure from inside to outside; The gas diffusion layer with internally constructed gradient oblique holes is used in a water electrolysis device to reduce the average size of bubbles passing through the gas diffusion layer with internally constructed gradient oblique holes and to increase the current density at the same overpotential.

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