Metal bipolar plate coating and preparation method thereof

Abstract

The invention provides a metal bipolar plate coating and a preparation method thereof, and relates to the field of proton exchange membrane batteries. Comprising a solvent and a solute, and the solute comprises the following raw materials in percentage by mass: 0.5-20% of ceramic particles, 35-80% of a conductive filler, 10-40% of a polymer resin matrix and 0.5-10% of a surfactant. Uniformly mixing the ceramic particles, the conductive filler, the surfactant and the solvent; adding a polymer resin matrix, continuously stirring, and uniformly mixing to obtain slurry; coating a metal bipolar plate with the slurry; and heating and curing to obtain the coating. The corrosion resistance of the metal bipolar plate in an acid environment can be obviously improved; good conductivity is maintained, and the working requirements of PEMFC or PEMWE are met; and the binding force between the coating and the metal substrate is strong, so that the mechanical strength and durability are improved. The coating is coated in a non-vacuum manner, so that the coating efficiency is greatly improved, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of proton exchange membrane batteries, and in particular to a metal bipolar plate coating and a preparation method thereof. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) or proton exchange membrane water electrolysis cell (PEMWE), as a clean energy conversion technology, one of its core components is the metal bipolar plate. Metal bipolar plates have been widely used in PEMFC or PEMWE due to their high strength, good formability, impact resistance and low gas permeability, especially in high-power fuel cells. In addition, metal bipolar plates have the dual functions of conducting electricity and separating gases in PEMFC or PEMWE. However, metal bipolar plates are susceptible to corrosion in acidic environments, which affects the performance and life of PEMFC or PEMWE.

[0003] Metal bipolar plate coating technology can improve the performance of PEMFC or PEMWE, and its coatings are mainly divided into metal coatings, non-metallic coatings and composite coatings. Metal coatings such as metal nitrides, carbides, oxides, etc. have good conductivity and chemical stability, but the cost may be high. Non-metallic coatings such as graphite-based coatings and conductive polymer coatings have the advantages of low cost, but may have problems with poor corrosion resistance and easy detachment. Composite coatings combine the advantages of metal and non-metallic coatings, and have good corrosion resistance and maintain conductivity. However, existing metal bipolar plates with composite coatings still have problems of high cost, poor corrosion resistance and erosion resistance. Summary of the invention

[0004] The object of the present invention is to provide a metal bipolar plate coating which has good corrosion resistance and erosion resistance and low cost.

[0005] Another object of the present invention is to provide a method for preparing a metal bipolar plate coating, wherein the coating slurry is directly coated on the surface of the metal bipolar plate, and the preparation method is simple.

[0006] The present invention solves the technical problem by adopting the following technical solutions.

[0007] In one aspect, an embodiment of the present invention provides a metal bipolar plate coating, comprising a solvent and a solute, wherein the solute comprises the following raw materials by mass percentage:

[0008] 0.5-20% ceramic particles, 35-80% conductive fillers, 10-40% polymer resin matrix and 0.5-10% surfactant. Adding ceramic particles can enhance the erosion resistance and thermal conductivity of the coating, and after high-temperature annealing, the coating is more dense. The resin matrix plays a role in solidifying and fixing the remaining components; the surfactant can improve the mutual solubility of the raw materials and reduce the viscosity of the slurry, so that the raw materials can be mixed evenly.

[0009] In some embodiments of the present invention, the ceramic particles are a mixture of one or more of aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, tantalum oxide, niobium oxide, and iridium oxide.

[0010] In some embodiments of the present invention, the conductive filler is a mixture of one or more of nano-carbon powder, graphite powder, graphene, carbon nanotubes, carbon fibers, nano-silver powder, nano-silver wires, nano-gold powder, nano-platinum black, and nano-iridium black.

[0011] In some embodiments of the present invention, the polymer resin matrix is ​​a mixture of one or more of epoxy resin, polyurethane resin, acrylic resin, fluororesin, and fluorosilicone resin.

[0012] In some embodiments of the present invention, the surfactant is polyethylene glycol sorbitan monooleate (Tween 80), sorbitan monooleate (Span 80), or a mixture of the two.

[0013] In some embodiments of the present invention, the solvent is a mixture of one or more of water, ethanol, n-propanol, isopropanol, ethylene glycol, glycerol, DMF (N,N-dimethylformamide), and DMSO (dimethyl sulfoxide).

[0014] On the other hand, an embodiment of the present invention provides a method for preparing a metal bipolar plate coating, comprising the following steps:

[0015] S1, mixing ceramic particles, conductive fillers, surfactants and solvents uniformly;

[0016] S2, adding the polymer resin matrix, continuing to stir, mixing evenly, to obtain a slurry with a certain viscosity and rheological properties; wherein the viscosity of the slurry can be adjusted by adjusting the amount of solvent added to the raw material according to the coating method.

[0017] S3, coating the slurry on the metal bipolar plate;

[0018] S4, after heating, curing and annealing, the coating is obtained.

[0019] In some embodiments of the present invention, the temperature of heating and curing is 80-100°C, and the annealing treatment is 120-220°C for 0.5-1 hour. By heating, the resin matrix is ​​cured, a coating is formed on the surface of the substrate, and raw materials such as ceramic particles and conductive fillers are fixed on the substrate, and then annealing is performed to provide the density of the coating, thereby improving the corrosion resistance and erosion resistance of the coating.

[0020] In some embodiments of the present invention, the coating is one of spraying, scraping, screen printing, and slit coating.

[0021] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0022] The metal bipolar plate coating provided by the present invention has ceramic particles added therein, which can significantly improve the corrosion resistance of the metal bipolar plate in an acidic environment; maintain good electrical conductivity to meet the working requirements of PEMFC or PEMWE; the coating has a strong bonding force with the metal substrate, which improves the mechanical strength and durability of the metal bipolar plate. The coating is applied in a non-vacuum manner, which greatly improves the coating efficiency and reduces the production cost.

[0023] The preparation method of the metal bipolar plate coating provided by the present invention comprises coating the slurry on the substrate, heating and curing it, and then performing an annealing treatment, which can effectively improve the tightness of the coating, and further improve the corrosion resistance, mechanical strength and durability of the coating. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0025] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0026] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0027] Example 1

[0028] The metal bipolar plate of this embodiment was prepared according to the following ratio and method.

[0029] S1. Take 5% alumina ceramic particles, 60% graphene conductive filler, 34.5% epoxy resin and 0.5% surfactant (Tween 80), and the total mixture is 120g.

[0030] S2. Under stirring conditions, add 1000 ml of ethanol and water, and mix the above materials evenly until a uniform slurry is formed.

[0031] S3. The slurry was ultrasonically sprayed on a 316L stainless steel bipolar plate, and then placed in an oven, cured at 80°C for 2 hours, and annealed at 120°C for 1 hour.

[0032] Example 2

[0033] The metal bipolar plate of this embodiment was prepared according to the following ratio and method.

[0034] S1. Take 2% titanium oxide ceramic particles, 60% graphene conductive filler, 10% nano silver powder, 27% fluorosilicone resin and 1.0% surfactant, and the total mixture is 100g.

[0035] S2. Under stirring conditions, add 1000 ml of n-propanol and water, and mix the above materials evenly until a uniform slurry is formed.

[0036] S3. The slurry was coated on a 316L stainless steel bipolar plate, and then placed in an oven, cured at 180°C for 1 hour, and annealed at 220°C for 0.5 hour.

[0037] Example 3

[0038] The metal bipolar plate of this embodiment was prepared according to the following ratio and method.

[0039] S1. Take 2% of tantalum oxide ceramic particles, 5% of nano-platinum black, 70% of nano-iridium black, 22% of fluorosilicone resin and 1.0% of surfactant, and the total mixture is 50g.

[0040] S2. Under stirring conditions, add 1000 ml of isopropanol, n-propanol and water, and mix the above materials evenly until a uniform slurry is formed.

[0041] S3. The slurry was coated on a 316L stainless steel bipolar plate, and then placed in an oven, cured at 180° C. for 1 hour, and annealed at 180° C. for 1 hour.

[0042] Example 4

[0043] The metal bipolar plate of this embodiment was prepared according to the following ratio and method.

[0044] S1. Take 20% alumina ceramic particles, 45% graphene conductive filler, 34.5% epoxy resin and 0.5% surfactant (Span 80), and the total mixture is 120g.

[0045] S2. Under stirring conditions, add 1000 ml of ethanol and water, and mix the above materials evenly until a uniform slurry is formed.

[0046] S3. The slurry was coated on the titanium bipolar plate, and then placed in an oven, cured at 80°C for 2 hours, and annealed at 130°C for 1 hour.

[0047] Example 5

[0048] The metal bipolar plate of this embodiment was prepared according to the following ratio and method.

[0049] S1. Take 10% alumina ceramic particles, 55% graphene conductive filler, 34.5% epoxy resin and 0.5% surfactant (Span 80), and the total mixture is 120g.

[0050] S2. Under stirring conditions, add 1000 ml of ethanol and water, and mix the above materials evenly until a uniform slurry is formed.

[0051] S3. The slurry was coated on the titanium bipolar plate, and then placed in an oven, cured at 80°C for 2 hours, and annealed at 135°C for 1 hour.

[0052] Comparative Example 1

[0053] The difference from Example 1 is that in this comparative example, ceramic particles are not added, and graphene conductive fillers are used instead of ceramic particles. The remaining raw material ratios and preparation methods are the same as those of Example 1.

[0054] Experimental example

[0055] The metal bipolar plates of Examples 1-3 and Comparative Example 1 were used as the objects, and an electrochemical workstation, a peeling force tester, and a thermal conductivity measuring instrument were used to test the corrosion resistance of the coating, the bonding strength between the coating and the metal substrate, the thermal conductivity of the coating, etc. The results are shown in Table 1.

[0056] Table 1 Properties of each coating

[0057]

[0058] It can be concluded from Table 1 above that the coating provided by the embodiment of the present invention has good corrosion resistance, and the peel strength of the coating is greater than 30N / cm, which is significantly higher than 4N / cm of Comparative Example 1. This is because in Examples 1-5, ceramic particles are added, and after thermal curing and annealing treatment, the coating has good density and is firmly connected to the substrate.

[0059] In summary, the metal bipolar plate coating provided by the present invention, which adds ceramic particles, can significantly improve the corrosion resistance of the metal bipolar plate in an acidic environment; maintain good electrical conductivity and thermal conductivity, and meet the working requirements of PEMFC or PEMWE; the coating has a strong bonding force with the metal substrate, and improves the mechanical strength and durability. The coating is coated in a non-vacuum manner, which greatly improves the coating efficiency and reduces the production cost.

[0060] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A metal bipolar plate coating, characterized in that: The method comprises a solvent and a solute, wherein the solute comprises the following raw materials by mass percentage: 0.5-20% ceramic particles, 35-80% conductive filler, 10-40% polymer resin matrix, and 0.5-10% surfactant.

2. The metal bipolar plate coating according to claim 1, characterized in that: The ceramic particles are a mixture of one or more of aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, tantalum oxide, niobium oxide, and iridium oxide.

3. The metal bipolar plate coating according to claim 1, characterized in that: The conductive filler is a mixture of one or more of nano carbon powder, graphite powder, graphene, carbon nanotube, carbon fiber, nano silver powder, nano silver wire, nano gold powder, nano platinum black, and nano iridium black.

4. The metal bipolar plate coating according to claim 1, characterized in that: The polymer resin matrix is ​​a mixture of one or more of epoxy resin, polyurethane resin, acrylic resin, fluororesin and fluorosilicone resin.

5. The metal bipolar plate coating according to claim 1, characterized in that: The surfactant is polyethylene glycol sorbitan monooleate, sorbitan monooleate or a mixture of the two.

6. The metal bipolar plate coating according to claim 1, characterized in that: The solvent is a mixture of one or more of water, ethanol, n-propanol, isopropanol, ethylene glycol, glycerol, DMF, and DMSO.

7. A method for preparing a metal bipolar plate coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, mixing ceramic particles, conductive fillers, surfactants and solvents uniformly; S2, adding the polymer resin matrix, continuing to stir, mixing evenly, to obtain a slurry; S3, coating the slurry on the metal bipolar plate; S4, after heating, curing and annealing, the coating is obtained.

8. The method for preparing a metal bipolar plate coating according to claim 7, characterized in that: The coating includes one of spraying, scraping, screen printing and slit coating.

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