CN114950906A

CN114950906A - Preparation process of bipolar plate coating

Info

Publication number: CN114950906A
Application number: CN202210630234.9A
Authority: CN
Inventors: 王英; 刘冬安; 丁加乐; 关春红; 任致行
Original assignee: China Automotive Innovation Co Ltd
Current assignee: China Automotive Innovation Co Ltd
Priority date: 2022-06-06
Filing date: 2022-06-06
Publication date: 2022-08-30
Anticipated expiration: 2042-06-06
Also published as: CN114950906B

Abstract

The invention discloses a preparation process of a bipolar plate coating, and belongs to the technical field of fuel cells. The preparation process of the bipolar plate coating comprises the following steps: preparing a hydrophobic coating on the first surface and/or the second surface; assembling the modified tooling and the bipolar plate, and shielding the bottom wall and partial side wall of the first gas flow channel and/or the second gas flow channel by using the modified tooling; and bombarding the surfaces of the first surface and/or the second surface except the modified tool shielding surface by using plasma to enhance the hydrophilicity of the surfaces of the first surface and/or the second surface except the modified tool shielding surface. The bottom wall and partial side wall of the first gas flow channel and/or the second gas flow channel are shielded by the modified tooling, the hydrophilicity of the hydrophobic coating is enhanced through plasma bombardment, the original coating preparation process is not required to be changed, different regions of the first surface and/or the second surface have different hydrophilicity and hydrophobicity, the water management state of the electric pile is improved, and the process is simple.

Description

Preparation process of bipolar plate coating

Technical Field

The invention relates to the technical field of fuel cells, in particular to a bipolar plate coating preparation process.

Background

The cell stack is a core component of a fuel cell and mainly comprises a bipolar plate, a membrane electrode assembly, a bus plate and the like. The function of the bipolar plates is to provide a gas path, prevent the hydrogen and oxygen in the fuel cell from communicating, and establish a current path between the serially connected anode and cathode. The thickness of the bipolar plate should be as thin as possible while maintaining mechanical strength and gas barrier function to reduce the conductive resistance to current and heat.

At present, the common bipolar plates mainly include graphite bipolar plates, metal bipolar plates and composite bipolar plates. The metal bipolar plate is easy to process, can be manufactured in batches, and has low cost, thin thickness and high volume specific power and specific energy of the battery. However, the corrosion resistance of the metal bipolar plate is poor, and metal ions such as iron are easily precipitated, so that the membrane electrode fails. Therefore, metallic bipolar plates require coating preparation to ensure the integrity and corrosion resistance of the bipolar plates.

In the actual operation of the electric pile, the actual situation of hydrothermal operation inside the electric pile needs to be considered. If the water in the galvanic pile is too much and difficult to discharge, the uniformity of gas distribution can be affected, so that the local gas shortage of the membrane electrode is caused, an abnormal high potential is generated, and the catalyst and the coating are irreversibly affected.

Hydrothermal management needs to be considered from many aspects such as plate design, membrane electrode assembly, coatings, etc. The smaller the water contact angle of the coating of the polar plate is, the stronger the hydrophilicity is, and the stronger the hydrophobicity of the membrane electrode assembly is, so that the coating can absorb water in the membrane electrode assembly more easily, and the flooding probability of the membrane electrode is reduced. But for the water in the flow channels of the polar plates, the water is easier to discharge, so that the situations of water blockage and corrosion are reduced.

However, in the prior art, in order to meet the above requirements, a hydrophobic coating is usually disposed in the flow channel of the plate, and a hydrophilic coating is disposed on the top surface of the ridge, so that different regions of the plate have different hydrophilicity or hydrophobicity, and this method is complicated in process, inefficient, and unable to meet production requirements.

Disclosure of Invention

The invention aims to provide a bipolar plate coating preparation process which can effectively improve the water management state of a galvanic pile and has simple process and strong operability.

In order to realize the purpose, the following technical scheme is provided:

a process for preparing a bipolar plate coating, the bipolar plate comprising a first surface and a second surface opposite to each other along a first direction, the first surface having a plurality of first ridges, a first gas flow channel being formed between any adjacent two of the first ridges, the second surface having a plurality of second ridges, a second gas flow channel being formed between any adjacent two of the second ridges, the process comprising the steps of:

preparing a hydrophobic coating on the first surface and/or the second surface;

assembling a modified tool with the bipolar plate, and shielding the bottom wall and partial side wall of the first gas flow channel and/or the second gas flow channel by using the modified tool;

and bombarding the surfaces of the first surface and/or the second surface except the modified tool shielding surface by using plasma to enhance the hydrophilicity of the surfaces of the first surface and/or the second surface except the modified tool shielding surface.

As an alternative of the preparation process of the bipolar plate coating, in the bombardment of the first surface and/or the second surface except the modified tooling shielding surface by using plasma, the method comprises the following steps:

putting the bipolar plate and the modified tooling assembled with the bipolar plate into a reaction cavity;

vacuumizing the reaction cavity;

introducing working gas into the reaction cavity;

and adjusting the radio frequency and the power thereof, and bombarding the surfaces of the first surface and/or the second surface except the surface shielded by the modification tool by using plasma gas.

As an alternative to the bipolar plate coating preparation process, in the step of bombarding the first surface and/or the second surface except for the modified tooling shielding surface by using plasma, the method further comprises the following steps:

and rotating the bipolar plate and the modified tool assembled with the bipolar plate.

As an alternative of the preparation process of the bipolar plate coating, in the bombardment of the first surface and/or the second surface except the modified tooling shielding surface by using plasma gas, the method further comprises the following steps:

and controlling the temperature of the reaction chamber to be maintained at a preset temperature.

As an alternative of the preparation process of the bipolar plate coating, introducing working gas into the reaction cavity, wherein the working gas is nitrogen or argon;

introducing working gas into the reaction cavity, wherein the flow of the introduced working gas is 1sccm-100 sccm;

in the adjusting radio frequency and the power thereof, the power of the radio frequency is 10W-1000W;

bombarding the first surface and/or the second surface except the surface shielded by the modification tool by using plasma gas for 1-120 min;

and controlling the temperature of the reaction cavity to be maintained at a preset temperature, wherein the preset temperature is 50-200 ℃.

As an alternative to the bipolar plate coating preparation process, after the bombardment of the first surface and/or the second surface other than the modified tooling shielding surface with plasma to enhance the hydrophilicity of the first surface and/or the second surface other than the modified tooling shielding surface,

and the water contact angle of the surface of the first surface and/or the second surface except the surface shielded by the modified tooling is 30-60 degrees.

As an alternative to the bipolar plate coating preparation process, in the bombardment of the first surface and/or the second surface with plasma, except for the modified tooling-masked surface, to enhance the hydrophilicity of the first surface and/or the second surface, except for the modified tooling-masked surface,

the surface of the first surface except the surface shielded by the modification tool is the surface of the first surface in contact with the corresponding membrane electrode assembly;

and the surface of the second surface except the surface shielded by the modification tool is the surface of the second surface in contact with the corresponding membrane electrode assembly.

As an alternative of the bipolar plate coating preparation process, in the process of assembling the modified tooling and the bipolar plate, all surfaces of the modified tooling are provided with anticorrosive coatings.

As an alternative of the preparation process of the bipolar plate coating, in the process of assembling the modified tooling and the bipolar plate, the modified tooling is utilized to shield the bottom wall and part of the side wall of the first gas flow channel and/or the second gas flow channel,

the modified tooling comprises shielding pieces which are arranged in one-to-one correspondence with the first gas flow channels and the second gas flow channels, the shielding pieces are placed in the corresponding first gas flow channels or the second gas flow channels, and two sides of each shielding piece are respectively abutted against two side walls of the corresponding first gas flow channels or the second gas flow channels so as to shield the bottom walls and partial side walls of the corresponding first gas flow channels or the second gas flow channels.

the modified tool comprises two tool split bodies, wherein the two tool split bodies are respectively assembled on the first surface and the second surface and fixedly connected through a connecting piece.

Compared with the prior art, the invention has the beneficial effects that:

the bipolar plate coating preparation process of the invention comprises the steps of firstly preparing a hydrophobic coating on the first surface and/or the second surface of a bipolar plate, then assembling a modified tool with the bipolar plate, shielding the bottom wall and part of the side wall of a first gas flow channel and/or a second gas flow channel by using the modified tool, so that the plasma can bombard the surfaces of the first surface and/or the second surface except the surface shielded by the modified tool to enhance the hydrophilicity of the surfaces of the first surface and/or the second surface except the surface shielded by the modified tool, enhancing the hydrophilicity of the hydrophobic coating by the plasma bombardment without changing the original coating preparation process, keeping the original hydrophobicity of the hydrophobic coating on the bottom wall and part of the side wall of the first gas flow channel and/or the second gas flow channel, and enabling the hydrophobic coating on the surfaces of the first surface and/or the second surface except the surface shielded by the modified tool to have hydrophilicity, in other words, different areas of the first surface and/or the second surface have different hydrophilicities and hydrophobicities, so that the water management state of the electric pile can be effectively improved, the process is simple, the operability is strong, and the preparation efficiency of the coating can be greatly improved.

Drawings

FIG. 1 is a schematic view of an assembly of a bipolar plate and a modified tooling in an embodiment of the present invention;

FIG. 2 is a first schematic diagram illustrating a relationship between a bipolar plate and a modified tooling in an embodiment of the present invention;

FIG. 3 is a second schematic diagram illustrating a relationship between a bipolar plate and a modified tooling in an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a tooling split in the embodiment of the invention;

FIG. 5 is an enlarged view of portion A of FIG. 4;

FIG. 6 is a first schematic view of a bipolar plate and a membrane electrode assembly according to an embodiment of the present invention;

FIG. 7 is a second schematic diagram of the relationship between the bipolar plate and the MEA according to the embodiment of the present invention.

Reference numerals:

100. a bipolar plate; 200. a membrane electrode assembly;

1. an anode plate; 11. a first surface; 111. a first ridge; 112. a first gas flow path; 12. an anode cooling surface;

2. a cathode plate; 21. a second surface; 211. a second ridge; 212. a second gas flow channel; 22. a cathode cooling surface;

3. modifying the tool; 31. the tool is split; 311. a shield.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that are conventionally placed when the products of the present invention are used, and are used only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements to be referred to must have specific orientations, be constructed in specific orientations, and operate, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; either mechanically or electrically. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As shown in fig. 1 to 3, the present embodiment provides a bipolar plate 100, the bipolar plate 100 includes a first surface 11 and a second surface 21 opposite to each other along a first direction, the first surface 11 is provided with a plurality of first ridges 111, a first gas flow channel 112 is formed between any two adjacent first ridges 111, the second surface 21 is provided with a plurality of second ridges 211, and a second gas flow channel 212 is formed between any two adjacent second ridges 211.

It will be appreciated that the bipolar plate 100 comprises a fixedly connected anode plate 1 and cathode plate 2, wherein the anode plate 1 has an anode gas surface provided with anode gas flow channels and an anode cooling surface 12 provided with anode cooling flow channels, and the cathode plate 2 has a cathode gas surface provided with cathode gas flow channels and a cathode cooling surface 22 provided with cathode cooling flow channels. In the present embodiment, the anode cooling surface 12 of the anode plate 1 and the cathode cooling surface 22 of the cathode plate 2 are welded and fixed, and illustratively, the first surface 11 is an anode gas surface, the first ridge 111 is an anode ridge, and the first gas flow channel 112 is an anode gas flow channel; the second surface 21 is a cathode gas surface, the second ridge 211 is a cathode ridge, and the second gas flow channel 212 is a cathode gas flow channel.

In the prior art, in order to improve the water management condition of the stack, make the water in the first gas flow channel 112 and the second gas flow channel 212 easier to discharge, and reduce the problems of water blocking and corrosion, a hydrophobic coating is usually disposed on the bottom wall of the first gas flow channel 112 and the second gas flow channel 212 and a part of the side wall connected with the bottom wall; in order to suck out water from the membrane electrode assembly 200, a hydrophilic coating is usually disposed on the surfaces of the first surface 11 and the second surface 21 except for the surface covered by the hydrophobic coating, in other words, the surfaces of the first surface 11 and the second surface 21 except for the surface covered by the hydrophobic coating, that is, the surfaces of the first surface 11 and the second surface 21 which are in contact with the corresponding membrane electrode assembly 200.

Specifically, the hydrophobic coating is prepared by using a hydrophobic material, and the hydrophilic coating is prepared by using a hydrophilic material. The preparation method of the coating has complex process and low efficiency and can not meet the production requirement.

In order to solve the above problems, the present embodiment provides a process for preparing a bipolar plate coating, comprising the following steps:

s1, preparing hydrophobic coating on the first surface 11 and the second surface 21.

Only continuous hydrophobic coatings need to be prepared on the first surface 11 and the second surface 21, and compared with the prior art that alternate hydrophobic coatings and alternate hydrophilic coatings are prepared by respectively utilizing hydrophobic materials and hydrophilic materials, the method is simple in process and strong in operability.

And S2, assembling the modified tooling 3 and the bipolar plate 100, and shielding the bottom wall and part of the side wall of the first gas flow channel 112 and the second gas flow channel 212 by using the modified tooling 3.

Optionally, all surfaces of the modified tooling 3 are provided with anticorrosive coatings, so that the corrosion problem of the modified tooling 3 can be avoided, and further, corrosive impurities are prevented from being adhered to the bipolar plate 100 to influence the performance of the galvanic pile. In addition, the modified tooling 3 also needs to have higher flatness and smoothness, so that the modified tooling 3 is prevented from damaging the integrity of the hydrophobic coating.

Optionally, as shown in fig. 4 and 5 in combination with fig. 1, the modification tool 3 includes two tool components 31, the two tool components 31 are respectively assembled on the first surface 11 and the second surface 21, and the two tool components 31 are fixedly connected by a connecting member such as a bolt, which is beneficial to improving the assembly precision, and further accurately controlling the area of the hydrophobic coating modification region.

Optionally, the modified tool 3 includes shielding members 311 disposed in one-to-one correspondence with the first gas flow channels 112 and the second gas flow channels 212, the shielding members 311 are disposed in the corresponding first gas flow channels 112 or the second gas flow channels 212, and two sides of the shielding members 311 are respectively abutted against two side walls of the corresponding first gas flow channels 112 or the second gas flow channels 212, so as to shield a bottom wall and a part of side walls of the corresponding first gas flow channels 112 or the second gas flow channels 212. The shielding tightness of the bottom walls and part of the side walls of the first gas flow passages 112 and the second gas flow passages 212 can be ensured by using the plurality of shielding members 311 to shield the plurality of first gas flow passages 112 and the plurality of second gas flow passages 212 one by one. The plurality of shutters 311 also need to have a high degree of precision and consistency to ensure consistency in the modified areas of the different ridges.

And S3, bombarding the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modification tool 3 by using plasma to enhance the hydrophilicity of the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modification tool 3.

Note that the surface of the first surface 11 other than the surface shielded by the modification tool 3 is a surface of the first surface 11 that contacts the corresponding membrane electrode assembly 200. The surface of the second surface 21 other than the surface shielded by the modification tool 3 is a surface of the second surface 21 which is in contact with the corresponding membrane electrode assembly 200.

In other words, the first surface 11 and the second surface 21 are both prepared with continuous hydrophobic coatings, and the part of the hydrophobic coatings which do not need to be modified is shielded by the modification tool 3, so that the part of the hydrophobic coatings keeps hydrophobic, and the corrosion of water to the coatings is reduced; the part of the hydrophobic coating which needs to be modified is exposed, so that the hydrophilicity of the part of the coating is enhanced, and the membrane electrode assembly 200 is prevented from being flooded by water.

Specific definitions of the partially hydrophobic coating that does not require modification and the partially hydrophobic coating that requires modification are detailed below.

As shown in fig. 2 and 3, the first gas flow channel 112 has a bottom wall and two opposite side walls at the first surface 11, one end of each side wall is connected with the bottom wall, and the other end is connected with the top surface of the corresponding first ridge 111. In order to ensure that the water in the first gas flow channel 112 is easier to be discharged, it is necessary to ensure that the hydrophobic coatings of the bottom wall of the first gas flow channel 112 and the part of the side wall connected to both sides of the bottom wall keep hydrophobic, so that modification treatment is not required, and the hydrophobic coatings of the bottom wall of the first gas flow channel 112 and the part of the side wall connected to the bottom wall are the part of the hydrophobic coatings which do not need to be modified.

It is understood that, as shown in fig. 6 and 7, the top surfaces of the first ridges 111 are in contact with the membrane electrode assembly 200, and in order to suck water out of the membrane electrode assembly 200, the hydrophobic coating on the top surfaces of the first ridges 111 needs to be modified to enhance the hydrophilicity thereof; in addition, since the stack of the fuel cell is formed by stacking the bipolar plate 100, the membrane electrode assembly 200, and the bipolar plate 100 in sequence, and a certain pressure is applied during the assembly process, the membrane electrode assembly 200 is not flatly disposed on the bipolar plate 100, but the carbon paper of the membrane electrode assembly 200 may intrude into the first gas flow channel 112, specifically, the membrane electrode assembly 200 may contact with not only the top surface of the first ridge 111 but also a part of the side wall of the first gas flow channel 112 (the part of the side wall connected to the top surface of the first ridge 111), and therefore the hydrophobic coating of the part of the side wall may also need to be modified to enhance the hydrophilicity, and the hydrophobic coating of the top surface of the first ridge 111 and the side wall of the part of the first gas flow channel 112 connected to both sides of the top surface of the first ridge 111 are the hydrophobic coating that needs to be modified.

Similarly, on the second surface 21, the second gas channel 212 has a bottom wall and two opposite side walls, one end of each side wall is connected to the bottom wall, and the other end is connected to the top surface of the corresponding second ridge 211. In order to ensure that the water in the second gas flow channel 212 is easier to be discharged, it is necessary to ensure that the hydrophobic coatings of the bottom wall of the second gas flow channel 212 and the part of the side wall connected to both sides of the bottom wall maintain hydrophobicity, so that modification treatment is not required, and the hydrophobic coatings of the bottom wall of the second gas flow channel 212 and the part of the side wall connected to the bottom wall are the part of the hydrophobic coatings which do not need modification.

It is understood that the top surfaces of the second ridges 211 are in contact with the mea 200, and in order to suck out water in the mea 200, the hydrophobic coating on the top surfaces of the second ridges 211 needs to be modified to enhance its hydrophilicity; in addition, since the stack of the fuel cell is formed by stacking the bipolar plate 100, the membrane electrode assembly 200, and the bipolar plate 100 in sequence, a certain pressure is applied during the assembly process, so that the membrane electrode assembly 200 is not flatly placed on the bipolar plate 100, but the carbon paper of the membrane electrode assembly 200 may intrude into the second gas flow channel 212, specifically, the membrane electrode assembly 200 may contact with not only the top surface of the second ridge 211 but also a part of the side wall of the second gas flow channel 212 (a part of the side wall connected to the top surface of the second ridge 211), so that the hydrophobic coating of the part of the side wall may be modified to enhance the hydrophilicity, and the hydrophobic coatings of the top surface of the second ridge 211 and the side wall of the part of the second gas flow channel 212 connected to both sides of the top surface of the second ridge 211 are the hydrophobic coatings to be modified.

In the embodiment, after the plasma is used for bombarding the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modification tool 3, the water contact angles of the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modification tool 3 are 30-60 degrees; for example, the water contact angles of the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modification tool 3 may be any one of values of 30 °, 35 °, 40 °, 45 °, 50 °, 55 °, and 60 °; hydrophilicity is enhanced and the probability of flooding of the membrane electrode assembly 200 is reduced.

In this embodiment, the bipolar plate 100 is subjected to plasma modification treatment by using a plating apparatus.

In step S3, the method specifically includes the following steps:

s31, placing the bipolar plate 100 and the modified tooling 3 assembled with the bipolar plate into a reaction cavity;

it should be noted that the volume of the modified tooling 3 cannot be too large, so as to ensure that the modified tooling 3 can be placed into a reaction chamber of a coating device after being assembled with the bipolar plate 100.

S32, vacuumizing the reaction cavity;

illustratively, the reaction chamber is evacuated by a vacuum pump so that the vacuum degree of the reaction chamber meets the requirement.

S33, introducing working gas into the reaction cavity;

the working gas is, for example, nitrogen or argon, but the working gas may be other gases capable of generating plasma, and is not limited herein. The flow rate of the introduced working gas is 1sccm-100 sccm. For example, the flow rate of the working gas can be any one of 1sccm, 5sccm, 10sccm, 20sccm, 30sccm, 40sccm, 50sccm, 60sccm, 70sccm, 80sccm, 90sccm, and 100 sccm.

And S34, adjusting the radio frequency and the power thereof, and bombarding the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modification tool 3 by using plasma gas.

The radio frequency power is too low, the bombardment time is longer, and the modification effect cannot be achieved; while too high a power of the radio frequency may destroy other properties of the hydrophobic coating. Illustratively, the power of the radio frequency is 10W-1000W; for example, the power of the radio frequency may be any one of 10W, 50W, 100W, 200W, 300W, 400W, 500W, 600W, 700W, 800W, 900W, and 1000W; the bombardment time is 1-120 min; for example, the bombardment time may be any one of 1min, 5min, 10min, 20min, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, and 120 min.

Further, it is necessary to control the temperature of the reaction chamber to be maintained at a predetermined temperature to avoid the problem of the bipolar plate 100 being warped due to too high temperature. Illustratively, the preset temperature is 50 ℃ to 200 ℃; for example, the predetermined temperature may be any one of 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃ and 200 ℃.

In order to ensure the hydrophilic consistency of the modified regions, optionally, when the plasma gas is used to bombard the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modifying tool 3, the bipolar plate 100 and the modifying tool 3 assembled with the bipolar plate can be rotated, so that the surfaces of the first surface 11 and the second surface 21 except the surface shielded by the modifying tool 3 can be uniformly bombarded by the plasma.

Specifically, after the hydrophobic coating is prepared, and before the bipolar plate 100 sealing process, the hydrophobic coating of the surface of the bipolar plate 100 contacting the membrane electrode assembly 200 is modified using the bipolar plate coating preparation process provided in this embodiment. It should be noted that, the modified tooling 3 is mainly arranged to shield the region of the bipolar plate 100 that does not need to be modified, and besides the bottom wall and part of the side wall of the first gas flow channel 112 and the second gas flow channel 212, the frame of the bipolar plate 100 also does not need to be modified, so that the modified tooling 3 can be used to shield the region of the bipolar plate 100.

It should be noted that in this embodiment, the hydrophobic coating modification treatment is performed on the first surface 11 and the second surface 21 simultaneously by plasma bombardment, in other embodiments, the modification tool 3 may also be used to shield only the bottom walls and partial side walls of the plurality of first gas flow channels 112 of the first surface 11, and further, the surfaces of the first surface 11 except the surface shielded by the modification tool 3 may be bombarded separately, so as to enhance the hydrophilicity of the surfaces of the first surface 11 except the surface shielded by the modification tool 3; the modification tool 3 may also be used to shield only the bottom walls and partial side walls of the plurality of second gas flow channels 212 of the second surface 21, and further, the surfaces of the second surface 21 except the surface shielded by the modification tool 3 may be bombarded separately, so as to enhance the hydrophilicity of the surfaces of the second surface 21 except the surface shielded by the modification tool 3.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements and substitutions will now be apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A bipolar plate coating preparation process, a bipolar plate (100) comprising a first surface (11) and a second surface (21) opposite to each other along a first direction, the first surface (11) being provided with a plurality of first ridges (111), a first gas flow channel (112) being formed between any adjacent two of the first ridges (111), the second surface (21) being provided with a plurality of second ridges (211), a second gas flow channel (212) being formed between any adjacent two of the second ridges (211), the process comprising the steps of:

-preparing a hydrophobic coating on said first surface (11) and/or said second surface (21);

assembling a modified tooling (3) with the bipolar plate (100), and shielding the bottom wall and partial side wall of the first gas flow channel (112) and/or the second gas flow channel (212) by using the modified tooling (3);

and bombarding the first surface (11) and/or the second surface (21) except the surface shielded by the modified tool (3) by using plasma to enhance the hydrophilicity of the first surface (11) and/or the second surface (21) except the surface shielded by the modified tool (3).

2. The process for preparing a coating for a bipolar plate according to claim 1, wherein said bombardment with plasma of said first surface (11) and/or said second surface (21) with the exception of the surface masked by said modifying tool (3) comprises the following steps:

putting the bipolar plate (100) and the modified tooling (3) assembled with the bipolar plate into a reaction cavity;

vacuumizing the reaction cavity;

introducing working gas into the reaction cavity;

adjusting the radio frequency and the power thereof, and bombarding the surfaces of the first surface (11) and/or the second surface (21) except the surface shielded by the modification tool (3) by using plasma gas.

3. The process for preparing a coating for a bipolar plate according to claim 2, wherein said bombardment of said first surface (11) and/or said second surface (21) with plasma, with the exception of the masking surface of said modified tooling (3), further comprises the steps of:

and rotating the bipolar plate (100) and the modified tooling (3) assembled with the bipolar plate.

4. The process for preparing a coating for a bipolar plate according to claim 2, wherein during said bombardment of the first surface (11) and/or of the second surface (21) with plasma gas, except for the surface masked by the modifying tool (3), the following steps are further included:

5. The process for preparing a bipolar plate coating according to claim 4, wherein a working gas is introduced into the reaction chamber, wherein the working gas is nitrogen or argon;

bombarding the first surface (11) and/or the second surface (21) except the surface shielded by the modification tool (3) by using plasma gas for 1-120 min;

6. The bipolar plate coating production process according to claim 1, wherein after said bombardment of the surfaces of the first surface (11) and/or the second surface (21) other than the modified tooling (3) shielding surface with plasma to enhance the hydrophilicity of the surfaces of the first surface (11) and/or the second surface (21) other than the modified tooling (3) shielding surface,

the water contact angle of the first surface (11) and/or the second surface (21) except the surface shielded by the modification tool (3) is 30-60 degrees.

7. The process for preparing a bipolar plate coating according to claim 1, wherein, in the bombardment of the first surface (11) and/or the second surface (21) with plasma, except for the surface shielded by the modified tooling (3), to enhance the hydrophilicity of the first surface (11) and/or the second surface (21), except for the surface shielded by the modified tooling (3),

the surface of the first surface (11) except the shielding surface of the modification tool (3) is the surface of the first surface (11) which is in contact with the corresponding membrane electrode assembly (200);

the surface of the second surface (21) except the shielding surface of the modification tool (3) is the surface of the second surface (21) which is in contact with the corresponding membrane electrode assembly (200).

8. The bipolar plate coating preparation process of claim 1, wherein in the assembling of the modified tooling (3) and the bipolar plate (100), all surfaces of the modified tooling (3) are provided with an anticorrosive coating.

9. The bipolar plate coating production process according to claim 1, wherein in the assembly of the modified tooling (3) with the bipolar plate (100), the modified tooling (3) is used to shield the bottom wall and part of the side wall of the first gas flow channel (112) and/or the second gas flow channel (212),

the modified tooling (3) comprises shielding pieces (311) which are arranged in one-to-one correspondence with the plurality of first gas flow channels (112) and the plurality of second gas flow channels (212), wherein the shielding pieces (311) are placed in the corresponding first gas flow channels (112) or the second gas flow channels (212), and two sides of each shielding piece (311) are respectively abutted against two side walls of the corresponding first gas flow channels (112) or the corresponding second gas flow channels (212) so as to shield the bottom walls and partial side walls of the corresponding first gas flow channels (112) or the corresponding second gas flow channels (212).

10. The bipolar plate coating production process according to claim 1, wherein in the assembly of the modified tooling (3) with the bipolar plate (100), the modified tooling (3) is used to shield the bottom wall and part of the side wall of the first gas flow channel (112) and/or the second gas flow channel (212),

the modified tooling (3) comprises two tooling split bodies (31), the two tooling split bodies (31) are respectively assembled on the first surface (11) and the second surface (21), and the two tooling split bodies (31) are fixedly connected through a connecting piece.