GDL hydrophobic modification treatment method and device for cathode open type air-cooled fuel cell

Abstract

The invention discloses a GDL hydrophobic modification treatment method and device for a cathode open type air-cooled fuel cell, relates to the technical field of cells, and aims to solve the problems that in the existing GDL preparation process, carbon paper and a base material layer need to be dried through a plurality of drying ovens, the production line is relatively long, the occupied area is relatively large, and the cost is relatively high in the traditional treatment process. The problems that in the prior art, the GDL is inconvenient to use in small factory workshops, the number of devices is large due to the fact that all the steps of the GDL are segmented in a segmented mode, and all the steps are inconvenient to move are solved. Comprising an immersion liquid layer, a first coating layer used for modifying the surface of a base material layer is arranged above the immersion liquid layer, a second coating layer used for modifying the other surface of the base material layer is arranged above the first coating layer, and drying layers are arranged at one end of the immersion liquid layer, one end of the first coating layer and one end of the second coating layer.

Description

Technical Field

[0001] The invention relates to the technical field of batteries, and in particular to a method and a device for hydrophobic modification of a GDL of an open cathode air-cooled fuel cell. Background Art

[0002] GDL, or gas diffusion layer, is an important component of air-cooled PEMFC membrane electrode. It is located between the bipolar plate and the catalyst layer, and is an effective conductor for transferring electrons generated in the catalyst layer, while ensuring that the reaction gas can effectively diffuse to the catalyst layer and the product is efficiently discharged. Therefore, GDL requires porous characteristics and high conductivity to improve electron transport, material distribution and prevent water flooding.

[0003] In the preparation process of existing GDL, the carbon paper and the substrate layer need to be dried in multiple ovens. Under the traditional processing technology, the production line is long and occupies a large area, which is not conducive to use in small factory workshops. If the GDL is processed in sections, the number of equipment is large and the movement between the steps is inconvenient. For this reason, we provide a GDL hydrophobic modification treatment method and device for cathode open air-cooled fuel cells. Summary of the invention

[0004] The object of the present invention is to provide a method and device for hydrophobic modification of the GDL of an open cathode air-cooled fuel cell, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a GDL hydrophobic modification treatment device for a cathode open air-cooled fuel cell, comprising an immersion layer, a first coating layer for modifying the surface of a substrate layer is arranged above the immersion layer, a second coating layer for modifying the other side of the substrate layer is arranged above the first coating layer, a drying layer is arranged at one end of the immersion layer, the first coating layer and the second coating layer, a roller coating back-moving assembly for driving carbon paper and the substrate layer to move into the drying layer is arranged above the immersion layer, the first coating layer and the second coating layer, the interior of the drying layer is divided into three drying sections of upper, middle and lower, and the three drying sections are respectively used to correspond to the immersion layer, the first coating layer and the second coating layer, a winding assembly for winding displacement is arranged at the outer bottom of one side of the drying layer, and the roller coating back-moving assembly is composed of a plurality of back-moving coating rollers arranged at intervals in the transverse direction.

[0006] Preferably, a rewinding roller is provided on the upper surface of one end of the immersion layer, an immersion tank is provided inside the immersion layer, displacement frames are provided on both sides above the immersion tank, a displacement block is provided above the displacement frame, a first downward pressure limiter is provided above the displacement block, the first downward pressure limiter includes a first pressure roller located at both ends of the immersion tank, a first lifting frame is provided at both ends of the first pressure roller, and a first driving member for driving the first pressure roller to move up and down is provided above the first lifting frame.

[0007] Preferably, moving components are provided on both sides of the upper surface of the first coating layer, and the moving components include a screw motor, a ball screw is provided at the output end of the screw motor, a screw slider is provided on the outer wall of the ball screw, and the first coating component is provided above the screw slider.

[0008] Preferably, the first coating assembly includes a scraper, a second lifting frame is arranged above the scraper, both ends of the second lifting frame are provided with second driving members for driving the lifting and moving thereof, a carbon ink storage tank is arranged on the side of the second lifting frame close to the drying layer, and a control valve port for controlling the discharge amount is arranged on the lower surface of the carbon ink storage tank.

[0009] Preferably, driven moving parts are provided on both sides of the upper surface of the second coating layer, and the driven moving parts include a driven slide rail, a driven slider is provided above the driven slide rail, and a second coating component is provided above the driven slider, and a connecting frame is provided on the outer wall of the second coating component, and the end of the connecting frame away from the second coating component is connected to the first coating component.

[0010] Preferably, both ends of the upper surfaces of the first coating layer and the second coating layer are provided with second downward pressure limiting members, the second downward pressure limiting member includes a second pressure roller, and both ends of the second pressure roller are provided with third driving members for driving the second pressure roller to move up and down.

[0011] Preferably, a first drying section is provided at the inner bottom of the drying layer, and the first drying section is used to dry the immersed carbon paper, a second drying section and a third drying section are respectively provided above the first drying section, and the second drying section and the third drying section correspond to the first coating layer and the second coating layer respectively, the first drying section, the second drying section and the third drying section are each composed of a plurality of heating rollers, a plurality of electric heaters are provided on the inner wall of the drying layer, a plurality of inlets and outlets are provided on the side wall of the drying layer, and a winding and discharging port is provided on the side wall on the other side of the drying layer.

[0012] Preferably, the winding assembly comprises a winding roller, and a winding motor is disposed at one end of the winding roller.

[0013] Preferably, the first driving member, the second driving member and the third driving member are driven by any one of hydraulic, pneumatic and electric means to realize lifting and displacement operations.

[0014] Preferably, a modification method of a GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell comprises the following steps:

[0015] Step 1: The carbon paper at the unwinding roller is pulled by the winding roller and moves forward to the immersion tank. The first driving member drives the first pressing roller to move downward, pressing the carbon paper into the immersion tank, so that the carbon paper is immersed in the PTFE slurry. After immersion, the carbon paper moves to the first drying section of the drying layer through the roller coating back movement assembly for drying.

[0016] Step 2: After the first drying, the substrate layer is moved onto the first coating layer, and the second downward limiter presses it down onto the table surface. The carbon ink storage tank discharges the carbon ink downward, so that the carbon ink falls onto the upper surface of the substrate layer. The second driving member adjusts the height of the scraper so that the scraper contacts the carbon ink, and the scraper is driven by the moving component to form an MPL layer on the side of the substrate layer coated with carbon ink. The MPL layer and the substrate layer form a GDL. After coating, the substrate layer is moved back through the roller coating return component there. During the return process, the surface of the substrate layer is evenly coated by the return coating roller. After moving back to the drying layer, the substrate layer is dried in the second drying section.

[0017] Step 3: After the secondary drying, the substrate layer is moved to the second coating layer with the uncoated surface facing upward, and the moving assembly drives the upper driven moving member to move through the connection of the connecting frame, and the second coating assembly coats the uncoated surface of the substrate layer during the movement. After coating, it is moved back to the third drying section in the drying layer for drying;

[0018] Step 4: After three dryings, the GDL moves out of the drying layer from the winding outlet, and the winding motor drives it to be pulled and wound onto the winding roller.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention modifies the GDL by means of immersion and coating, wherein the GDL is modified according to the process of immersion, drying, coating, drying, coating and drying by means of winding and moving. The overall equipment can be gradually displaced by means of upper and lower level segments, and the drying place is concentrated together with the immersion and coating place. The drying equipment is required to occupy a small area, and during coating, another coating part can be driven by connection to perform displacement coating operations, thereby reducing equipment costs and being conducive to use in small factory workshops. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the immersion layer of the present invention;

[0023] Figure 3 It is a schematic diagram of the structure of the first coating layer of the present invention;

[0024] Figure 4 is a schematic diagram of the structure of the second coating layer of the present invention;

[0025] Figure 5 It is a schematic diagram of the internal structure of the drying layer of the present invention;

[0026] Figure 6 It is a schematic diagram of the structure of the winding assembly of the present invention;

[0027] In the figure: 1, immersion layer; 101, displacement frame; 102, displacement block; 103, first downward pressure limiter; 104, first driving member; 105, first lifting frame; 106, first pressure roller; 107, unwinding roller; 108, immersion tank; 2, first coating layer; 201, moving assembly; 202, screw motor; 203, ball screw; 204, screw slider; 205, first coating assembly; 206, second driving member; 207, second lifting frame; 208, scraper; 209, carbon ink storage tank; 3, second coating layer; 301, driven displacement Moving part; 302, driven slide rail; 303, driven slider; 304, second coating assembly; 305, connecting frame; 4, drying layer; 401, entrance; 402, first drying section; 403, heating roller; 404, exit; 405, second drying section; 406, third drying section; 407, electric heater; 408, winding outlet; 5, winding assembly; 501, winding motor; 502, winding roller; 6, roller coating back movement assembly; 601, back movement of coating roller; 7, second downward pressure limiter; 701, second pressure roller; 702, third driving part. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] See also Figure 2An embodiment of the present invention is as follows: a GDL hydrophobic modification treatment device for a cathode open air-cooled fuel cell, wherein a reel 107 is provided on the upper surface of one end of an immersion layer 1, an immersion tank 108 is provided inside the immersion layer 1, displacement racks 101 are provided on both sides above the immersion tank 108, a displacement block 102 is provided above the displacement rack 101, a first downward pressure limiter 103 is provided above the displacement block 102, the first downward pressure limiter 103 comprises a first pressing roller 106 located at both ends of the immersion tank 108, a first lifting rack 105 is provided at both ends of the first pressing roller 106, a first driving member 104 for driving the first pressing roller 106 to move up and down is provided above the first lifting rack 105; the height of the first lifting rack 105 is adjusted by the first downward pressure limiter 103, so that the first pressing roller 106 can press the carbon paper into the immersion tank 108 to perform the immersion operation on the carbon paper.

[0030] See also Figure 1 , Figure 3 , Figure 4A first coating layer 2 for modifying the surface of the substrate layer is arranged above the immersion layer 1, and moving components 201 are arranged on both sides of the upper surface of the first coating layer 2. The moving component 201 includes a screw motor 202, and a ball screw 203 is arranged at the output end of the screw motor 202. A screw slider 204 is arranged on the outer wall of the ball screw 203, and a first coating component 205 is arranged above the screw slider 204. The first coating component 205 includes a scraper 208, and a second lifting frame 207 is arranged above the scraper 208. Both ends of the second lifting frame 207 are provided with a second driving member 206 for driving the lifting and moving thereof. A carbon ink storage tank 209 is arranged on the side of the second lifting frame 207 close to the drying layer 4, and a control valve port for controlling the discharge amount is arranged on the lower surface of the carbon ink storage tank 209. A second coating layer 3 for modifying the other side of the substrate layer is arranged above the first coating layer 2, and driven moving members are arranged on both sides of the upper surface of the second coating layer 3. 301, the driven moving member 301 includes a driven rail 302, a driven slider 303 is arranged above the driven rail 302, a second coating component 304 is arranged above the driven slider 303, a connecting frame 305 is arranged on the outer wall of the second coating component 304, and the end of the connecting frame 305 away from the second coating component 304 is connected to the first coating component 205; the screw motor 202 and the ball screw 203 drive the screw slider 204 to move, so that the scraper 208 can scrape the carbon ink on the surface of the substrate layer in a moving manner, and the second driving member 206 drives the scraper 208 to move up and down, so as to adjust the height of the scraper 208. Through the connection of the connecting frame 305, when the first coating component 205 moves, the second coating component 304 above is driven to move, so that the coating operation can be performed on the two surfaces of the substrate layer, and the carbon ink with different PTFE loading amounts is adjusted to obtain GDL with different PTFE loading amounts;

[0031] Typically, a thin hydrophobic MPL mainly formed by Vulcan XC-72R carbon black and PTFE is coated on the surface of the GDL substrate layer to form a double-layer GDL. The addition of MPL can minimize the contact resistance between the catalyst layer and the GDL; provide support for the catalyst layer to limit the catalyst loss caused by the entry of some small particle catalysts into the GDL; reduce the possibility of flooding the catalyst layer and the GDL, thereby reducing the oxygen mass transfer resistance. PTFE is the most commonly used binder and hydrophobic agent in MPL. According to the cell design and operating conditions, there is an optimal PTFE loading in MPL to maximize the performance of PEMFC.

[0032] With the increase of PTFE content, the hydrophobicity of the substrate layer is further enhanced, which weakens the diffusion and transmission of water from the catalyst layer to the flow channel. More water is retained inside the membrane electrode, so that the proton exchange membrane can maintain a good degree of hydration, and the ionic ohmic impedance is reduced. The reduction in ionic ohmic impedance is greater than the increase in volume resistance and contact resistance caused by the increase in PTFE content, so it is ultimately reflected in the reduction of ohmic impedance. In general, at low current density, a substrate layer with a high PTFE loading (40wt.%) is conducive to water retention inside the membrane electrode and can achieve the best performance output. At high current density, a substrate layer PTFE loading of 10wt.% can allow the battery to maintain a suitable oxygen mass transfer capacity and water content of the proton exchange membrane, and the performance of air-cooled PEMFC is the best.

[0033] The optimal PTFE loading of the substrate layer of GDL and MPL is 10wt.% and 40wt.%, respectively. The performance of air-cooled PEMFC is best at high current density. Adding an appropriate amount of PTFE to the substrate layer can enhance the hydrophobicity of the substrate layer, increase the water content in the proton exchange membrane and the catalyst layer ionomer, avoid the accumulation of generated water in the substrate layer, and is beneficial to enhance the oxygen mass transfer capacity of air-cooled PEMFC. However, excessive PTFE in the substrate layer will also lead to a decrease in porosity and increase the mass transfer impedance. At the same time, adding an appropriate amount of PTFE to MPL increases the water content of the catalyst layer, reduces the charge transfer resistance, and is beneficial to the improvement of the performance of air-cooled PEMFC.

[0034] Furthermore, second downward pressure limit members 7 are provided at both ends of the upper surfaces of the first coating layer 2 and the second coating layer 3, and the second downward pressure limit member 7 includes a second pressing roller 701, and both ends of the second pressing roller 701 are provided with third driving members 702 for driving the second pressing roller 701 to move up and down. Through the setting of the second downward pressure limit member 7, the substrate layer can be restricted so that it is attached to the table surface, which is more convenient for coating operations. The height of the second pressing roller 701 is adjusted by the third driving member 702, thereby changing the downward pressure height.

[0035] See also Figure 5 , Figure 6The interior of the drying layer 4 is divided into three drying sections, namely, upper, middle and lower drying sections, and the three drying sections are respectively used to correspond to the immersion layer 1, the first coating layer 2 and the second coating layer 3. Specifically, a first drying section 402 is provided at the inner bottom of the drying layer 4, and the first drying section 402 is used to dry the immersed carbon paper. A second drying section 405 and a third drying section 406 are respectively provided above the first drying section 402, and the second drying section 405 and the third drying section 406 correspond to the first coating layer 2 and the second coating layer 3 respectively. The first drying section 402, the second drying section 405 and the third drying section 406 are all composed of a plurality of heating rollers 403. A plurality of electric heaters 407 are provided on the inner wall of the drying layer 4. A plurality of inlets 401 and outlets 404 are provided on the side wall of the drying layer 4. A winding outlet 408 is provided on the side wall on the other side of the drying layer 4. A winding component for winding displacement is provided on the outer bottom on one side of the drying layer 4. 5. The winding assembly 5 includes a winding roller 502, one end of which is provided with a winding motor 501, and one end of the immersion layer 1, the first coating layer 2, and the second coating layer 3 are all provided with a drying layer 4. The immersion layer 1, the first coating layer 2, and the second coating layer 3 are all provided with a roller coating return assembly 6 for driving the carbon paper and the substrate layer to move to the drying layer 4. The roller coating return assembly 6 is composed of a plurality of laterally spaced return coating rollers 601. After immersion and coating, a drying device is required to dry and solidify the GDL. The return coating roller 601 can be used to return the GDL after immersion and coating to the drying layer 4, and it is dried by the heating rollers 403 and the electric heater 407 at different drying sections, so that the drying device can meet the drying processing requirements required for immersion and coating, and occupies a smaller area. The GDL can realize immersion, coating and drying operations by winding and moving, which is convenient for users to use.

[0036] Furthermore, the first drive member 104, the second drive member 206, and the third drive member 702 use any one of hydraulic, pneumatic, and electric methods to achieve lifting and displacement operations, including the use of hydraulic cylinders, air cylinders, and electric cylinders through piston transmission, and also include the use of components such as electric push rods and lead screw linear modules to achieve lifting and movement.

[0037] A modification method for a GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell comprises the following steps:

[0038] Step 1: The carbon paper at the unwinding roller 107 is pulled by the winding and moves forward to the immersion tank 108, and the first driving member 104 drives the first pressing roller 106 to move downward, pressing the carbon paper down into the immersion tank 108, so that the carbon paper is immersed in the PTFE slurry. After the immersion, the carbon paper moves to the first drying section 402 of the drying layer 4 through the roller coating back movement assembly 6 for drying.

[0039] Step 2: After the first drying, the substrate layer moves onto the first coating layer 2, the second downward limiter 7 presses it down onto the table, the carbon ink storage tank 209 discharges the carbon ink downward, and the carbon ink falls onto the upper surface of the substrate layer, the second driving member 206 adjusts the height of the scraper 208, so that the scraper 208 contacts the carbon ink, and the scraper 208 is driven by the moving component 201 to form an MPL layer on the side of the substrate layer coated with carbon ink, and the MPL layer and the substrate layer form a GDL, and after coating, the substrate layer is moved back through the roller coating back moving component 6 there, and the surface of the substrate layer is evenly coated by the back moving coating roller 601 during the back moving process, and after moving back to the drying layer 4, the substrate layer is dried at the second drying section 405;

[0040] Step 3: After the secondary drying, the substrate layer is moved to the second coating layer 3 with the uncoated surface facing upward, and the moving component 201 drives the upper driven moving component 301 to move through the connection of the connecting frame 305, and the second coating component 304 coats the uncoated surface of the substrate layer during the movement. After coating, it is moved back to the third drying section 406 in the drying layer 4 for drying;

[0041] Step 4: After three dryings, the GDL moves out of the drying layer 4 from the winding outlet 408 , and the winding motor 501 drives it to be pulled and wound onto the winding roller 502 .

[0042] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A GDL hydrophobic modification treatment device for an open cathode air-cooled fuel cell, comprising a liquid immersion layer (1), characterized in that: A first coating layer (2) for modifying the surface of the substrate layer is arranged above the immersion layer (1); a second coating layer (3) for modifying the other side of the substrate layer is arranged above the first coating layer (2); a drying layer (4) is arranged at one end of the immersion layer (1), the first coating layer (2) and the second coating layer (3); a roller coating return assembly (6) for driving the carbon paper and the substrate layer to move into the drying layer (4) is arranged above the immersion layer (1), the first coating layer (2) and the second coating layer (3); the interior of the drying layer (4) is divided into three drying sections, namely, upper, middle and lower sections, and the three drying sections are respectively used to correspond to the immersion layer (1), the first coating layer (2) and the second coating layer (3); a winding assembly (5) for winding displacement is arranged at the outer bottom of one side of the drying layer (4); the roller coating return assembly (6) is composed of a plurality of return coating rollers (601) arranged at intervals in the transverse direction.

2. The GDL hydrophobic modification treatment device for a cathode open air-cooled fuel cell according to claim 1, characterized in that: A reeling roller (107) is arranged on the upper surface of one end of the immersion layer (1), an immersion tank (108) is provided inside the immersion layer (1), displacement frames (101) are arranged on both sides above the immersion tank (108), a displacement block (102) is arranged above the displacement frame (101), a first downward pressure limiter (103) is arranged above the displacement block (102), the first downward pressure limiter (103) comprises a first pressing roller (106) located at both ends of the immersion tank (108), first lifting frames (105) are arranged at both ends of the first pressing roller (106), and a first driving member (104) for driving the first pressing roller (106) to move up and down is arranged above the first lifting frame (105).

3. The GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell according to claim 2, characterized in that: A moving component (201) is arranged on both sides of the upper surface of the first coating layer (2), and the moving component (201) includes a screw motor (202), a ball screw (203) is arranged at the output end of the screw motor (202), a screw slider (204) is arranged on the outer wall of the ball screw (203), and a first coating component (205) is arranged above the screw slider (204).

4. The GDL hydrophobic modification treatment device for an open cathode air-cooled fuel cell according to claim 3, characterized in that: The first coating component (205) comprises a scraper (208), a second lifting frame (207) is arranged above the scraper (208), both ends of the second lifting frame (207) are provided with second driving members (206) for driving the lifting and moving thereof, a carbon ink storage tank (209) is arranged on the side of the second lifting frame (207) close to the drying layer (4), and a control valve port for controlling the discharge amount is arranged on the lower surface of the carbon ink storage tank (209).

5. The GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell according to claim 4, characterized in that: A driven moving part (301) is arranged on both sides of the upper surface of the second coating layer (3), and the driven moving part (301) includes a driven slide rail (302), a driven slider (303) is arranged above the driven slide rail (302), and a second coating component (304) is arranged above the driven slider (303), and a connecting frame (305) is arranged on the outer wall of the second coating component (304), and the end of the connecting frame (305) away from the second coating component (304) is connected to the first coating component (205).

6. The GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell according to claim 5, characterized in that: Both ends of the upper surface of the first coating layer (2) and the second coating layer (3) are provided with second downward pressure limiting members (7), the second downward pressure limiting member (7) comprises a second pressing roller (701), and both ends of the second pressing roller (701) are provided with third driving members (702) for driving the second pressing roller (701) to move upward and downward.

7. The GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell according to claim 6, characterized in that: A first drying section (402) is arranged at the inner bottom of the drying layer (4), and the first drying section (402) is used to dry the carbon paper immersed in liquid. A second drying section (405) and a third drying section (406) are arranged above the first drying section (402), and the second drying section (405) and the third drying section (406) correspond to the first coating layer (2) and the second coating layer (3), respectively. The first drying section (402), the second drying section (405) and the third drying section (406) are all composed of a plurality of heating rollers (403). A plurality of electric heaters (407) are arranged on the inner wall of the drying layer (4). A plurality of inlets (401) and outlets (404) are provided on the side wall of the drying layer (4), and a winding and discharging port (408) is provided on the side wall on the other side of the drying layer (4).

8. The GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell according to claim 7, characterized in that: The winding assembly (5) comprises a winding roller (502), and a winding motor (501) is provided at one end of the winding roller (502).

9. The GDL hydrophobic modification treatment device of a cathode open air-cooled fuel cell according to claim 8, characterized in that: The first driving member (104), the second driving member (206) and the third driving member (702) are driven by any one of hydraulic, pneumatic and electric methods to achieve lifting and displacement operations.

10. A modification method of a GDL hydrophobic modification treatment device for a cathode open air-cooled fuel cell, based on the GDL hydrophobic modification treatment device for a cathode open air-cooled fuel cell according to claim 9, characterized in that: The following steps are involved: Step 1: The carbon paper at the unwinding roller (107) is pulled by the winding roller and moved forward to the immersion tank (108), and the first driving member (104) drives the first pressing roller (106) to move downward, pressing the carbon paper down into the immersion tank (108) so that the carbon paper is immersed in the PTFE slurry. After the immersion, the carbon paper is moved to the first drying section (402) of the drying layer (4) through the roller coating return assembly (6) for drying. Step 2: After the first drying, the substrate layer is moved onto the first coating layer (2), the second downward limit member (7) presses it down onto the table, the carbon ink storage tank (209) discharges the carbon ink downward, and the carbon ink falls onto the upper surface of the substrate layer, the second driving member (206) adjusts the height of the scraper (208) so that the scraper (208) contacts the carbon ink, and the scraper (208) is driven by the moving component (201) to form an MPL layer on the side of the substrate layer coated with carbon ink, and the MPL layer and the substrate layer form a GDL. After coating, the substrate layer is moved back through the roller coating return component (6) there, and the surface of the substrate layer is evenly coated by the return coating roller (601) during the return process. After moving back to the drying layer (4), the substrate layer is dried in the second drying section (405); Step 3: After the secondary drying, the substrate layer is moved to the second coating layer (3) with the uncoated surface facing upwards, and the moving component (201) drives the upper driven moving component (301) to move through the connection of the connecting frame (305), and the second coating component (304) is used to coat the uncoated surface of the substrate layer during the movement. After coating, it is moved back to the third drying section (406) in the drying layer (4) for drying; Step 4: After three dryings, the GDL is moved out of the drying layer (4) from the winding outlet (408), and the winding motor (501) drives it to be pulled and wound onto the winding roller (502).

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