Bipolar plate composite coating and electrolytic bath

Abstract

The invention provides a bipolar plate composite coating and an electrolytic bath, and relates to the technical field of coating materials, the bipolar plate composite coating provided by the invention comprises Ti element, Ta element and Si element, and the composite coating has better corrosion resistance and smaller interface contact resistance. Moreover, the composite coating provided by the invention does not use noble metal, so that the cost is relatively low. In conclusion, the bipolar plate composite coating provided by the invention has relatively good conductivity, relatively good corrosion resistance and relatively low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of coating materials, and in particular to a bipolar plate composite coating and an electrolytic cell. Background Art

[0002] At present, in the technical system of water electrolysis, hydrogen preparation technologies mainly include: alkaline water electrolysis hydrogen production technology, proton exchange membrane (PEM) water electrolysis hydrogen production technology and solid oxide electrolysis cell (SOEC) water electrolysis hydrogen production technology; among them, PEM hydrogen production technology uses pure water as raw material, has the advantages of fast response speed and high hydrogen production efficiency, and is one of the current hot spots in the research of water electrolysis hydrogen production technology.

[0003] The bipolar plate is the core component of the PEM water electrolysis hydrogen production equipment. Its main functions are to support the diffusion layer, conduct gas and cooling water, transmit electrolysis current and conduct heat generated by the stack, etc. Due to the harsh operating environment of the bipolar plate, corrosion resistance and conductivity have become the core indicators of metal bipolar plates. Commonly used metal materials cannot meet the requirements of bipolar plates, and coating the surface of metal bipolar plates has become a necessary means. At present, the more mature bipolar plate surface coatings are mainly precious metal coatings such as platinum and gold, but the cost is too high and is not suitable for the commercialization needs of bipolar plates. Therefore, how to obtain a bipolar plate coating with better conductivity, better corrosion resistance and lower cost has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] The problem solved by the present invention is: how to obtain a bipolar plate coating with better conductivity, better corrosion resistance and lower cost.

[0005] In order to solve the above problems, the present invention provides a bipolar plate composite coating, the components of which include Ti element, Ta element and Si element.

[0006] Optionally, the mass fraction of the Ti element is 30-50%, the mass fraction of the Ta element is 40-60%, and the mass fraction of the Si element is 10-20%.

[0007] Optionally, its thickness is 500-2000 nm.

[0008] Optionally, it includes a base layer, an intermediate layer and a surface layer deposited in sequence on the surface of the bipolar plate; the composition of the base layer includes Ti element, the composition of the intermediate layer includes Ti element, Ta element and Si element; the composition of the surface layer includes Ta element and Si element.

[0009] Optionally, the thickness of the primer layer is 25-100 nm.

[0010] Optionally, the thickness of the intermediate layer is 200-400 nm.

[0011] Optionally, the thickness of the surface layer is 100-300 nm.

[0012] Optionally, the mass ratio of the Ti element, the Ta element and the Si element in the intermediate layer is (3-5):(4-6):1.

[0013] Optionally, the mass ratio of Ta element to Si element in the surface layer is (8-9):(1-2).

[0014] The present invention also provides an electrolytic cell, comprising a bipolar plate, on which the bipolar plate composite coating as described above is provided.

[0015] Compared with the prior art, the components of the bipolar plate composite coating provided by the present invention include Ti, Ta and Si elements, and the composite coating has better corrosion resistance and lower interface contact resistance. Moreover, the composite coating provided by the present invention does not use precious metals, and the cost is lower. In summary, the bipolar plate composite coating provided by the present invention has better conductivity, better corrosion resistance and lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a bipolar plate having a bipolar plate composite coating formed on the surface in an embodiment of the present invention;

[0017] Figure 2 It is a comparison chart of the potentiodynamic polarization test of the bipolar plates with composite coatings formed in Example 1 and Comparative Examples 1-3.

[0018] Description of reference numerals:

[0019] 1. Bipolar plate; 2. Base layer; 3. Middle layer; 4. Surface layer. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application;

[0022] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" is "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, the meaning of "multiple" is two or more.

[0023] An embodiment of the present invention provides a bipolar plate composite coating, the components of which include Ti element, Ta element and Si element.

[0024] The components of the bipolar plate composite coating provided by the embodiment of the present invention include Ti, Ta and Si elements, and the composite coating has better corrosion resistance and lower interface contact resistance. Moreover, no precious metal is used in the composite coating, and the cost is lower. In summary, the bipolar plate composite coating provided by the embodiment of the present invention has better conductivity, better corrosion resistance and lower cost.

[0025] In some embodiments of the present invention, in the bipolar plate composite coating, the mass fraction of the Ti element is 30-50%, the mass fraction of the Ta element is 40-60%, and the mass fraction of the Si element is 10-20%.

[0026] In some embodiments of the present invention, the thickness of the bipolar plate composite coating is 500-2000 nm.

[0027] In some embodiments of the present invention, Figure 1 As shown, the bipolar plate composite coating includes a base layer 2, an intermediate layer 3 and a surface layer 4 which are sequentially deposited on the surface of the bipolar plate 1; the base layer 2 is composed of Ti elements, the intermediate layer is composed of Ti elements, Ta elements and Si elements; the surface layer 4 is composed of Ta elements and Si elements.

[0028] In some embodiments of the present invention, preferably, the bipolar plate composite coating includes a base layer 2, an intermediate layer 3 and a surface layer 4 sequentially deposited on the surface of the bipolar plate 1; the base layer 2 is made of Ti, the intermediate layer is composed of Ti, Ta and Si elements; and the surface layer 4 is composed of Ta and Si elements.

[0029] The bipolar plate composite coating provided in this embodiment is composed of a base layer 2, an intermediate layer 3 and a surface layer 4 deposited on the surface of the bipolar plate 1 in sequence, wherein the base layer 2 is made of Ti, which can form a good adhesion with the bipolar plate, and helps to prevent the composite coating from falling off or cracking during use; the intermediate layer 3 is composed of Ti, Ta and Si, Ti and Ta have high corrosion resistance, Si has good oxidation stability, so that the intermediate layer 3 has better corrosion resistance; the surface layer 4 is composed of Ta and Si, Ta itself has high corrosion resistance, and the doping of Si element can promote the formation of a film structure of (β+α)Ta, which is conducive to reducing defect corrosion; the base layer 2, the intermediate layer 3 and the surface layer 4 in the embodiment of the present invention work together to make the composite coating have better corrosion resistance. In addition, the interface contact resistance of the composite coating provided in this embodiment is small, and it has better conductivity.

[0030] In some embodiments of the present invention, preferably, the thickness of the base layer 2 is 25-100 nm; the thickness of the intermediate layer 3 is 200-400 nm, and the thickness of the surface layer 4 is 100-300 nm.

[0031] In some embodiments of the present invention, the mass ratio of Ti element, Ta element and Si element in the intermediate layer 3 is (3-5):(4-6):1.

[0032] In some embodiments of the present invention, the mass ratio of Ta element to Si element in the surface layer 4 is (8-9): (1-2).

[0033] The present invention also provides an electrolytic cell, comprising a bipolar plate, wherein the bipolar plate is provided with the bipolar plate composite coating as described above.

[0034] The embodiment of the present invention further provides a method for preparing a bipolar plate composite coating, which is used to prepare the bipolar plate composite coating as described above, comprising:

[0035] Step S1, depositing Ti on the surface of the bipolar plate 1 to obtain a base layer 2;

[0036] Step S2, using a co-sputtering deposition method to simultaneously deposit Ti, Ta and Si on the surface of the base layer 2 to obtain an intermediate layer 3;

[0037] Step S3, using a co-sputtering deposition method to simultaneously deposit Ta and Si on the surface of the intermediate layer 3 to obtain a surface layer 4.

[0038] In some embodiments of the present invention, in step S2, during the deposition process, the substrate bias is 100-200 V, the current of the Ti target is 10-15 A, the current of the Ta target is 10-15 A, the current of the Si target is 2-5 A, and the deposition time is 20-30 min.

[0039] In some embodiments of the present invention, in step S3, during the deposition process, the substrate bias voltage is 100-200 V, the current of the Ta target is 10-15 A, the current of the Si target is 2-5 A, and the deposition time is 20-30 min.

[0040] In some embodiments of the present invention, exemplarily, the material of the bipolar plate is Ti.

[0041] The present invention is further described below in conjunction with specific embodiments.

[0042] Example 1

[0043] A1. Place the bipolar plate in an ultrasonic cleaning device for ultrasonic cleaning to remove dust, impurities and oil stains on its surface, then install the cleaned bipolar plate on the sample stage of a magnetron sputtering device, turn on the Ti target, and deposit Ti on the surface of the bipolar plate to obtain a base layer; wherein the thickness of the base layer is 50 nm, the material of the bipolar plate is Ti, and during the deposition process, the working gas pressure is 0.3 Pa, the substrate bias is 150 V, and the current of the Ti target is 15 A.

[0044] A2. Keep the Ti target in an on state, turn on the Ta target and the Si target, and deposit Ti, Ta and Si on the surface of the base layer at the same time to obtain an intermediate layer; wherein the thickness of the intermediate layer is 250nm, and the mass ratio of the Ti element, the Ta element and the Si element in the intermediate layer is 4:5:1. During the deposition process, the working gas pressure is 0.3Pa, the substrate bias is 150V, the current of the Ti target is 15A, the current of the Ta target is 15A, and the current of the Si target is 3A.

[0045] A3. Keep the Ta target and the Si target in the open state, close the Ti target, and deposit Ta and Si on the surface of the intermediate layer at the same time to obtain a surface layer, and finally obtain a bipolar plate with a composite coating; wherein the mass ratio of the Ta element and the Si element in the surface layer is 8:2, and the thickness of the surface layer is 200nm. During the deposition process, the working gas pressure is 0.3Pa, the substrate bias is 150V, the current of the Ti target is 15A, and the current of the Si target is 3A.

[0046] Example 2

[0047] The difference from Example 1 is that in step A2, the mass ratio of Ti element, Ta element and Si element in the intermediate layer is 3:6:1.

[0048] Example 3

[0049] The difference from Example 1 is that in step A3, the mass ratio of Ta element to Si element in the surface layer is 9:1.

[0050] Comparative Example 1

[0051] The difference from Example 1 is that the surface layer in Example 1 is replaced by a Ta—N surface layer, wherein the mass ratio of Ta element to N element in the Ta—N surface layer is 8:2.

[0052] Comparative Example 2

[0053] The difference from Example 1 is that the intermediate layer in Example 1 is replaced by a Ti—Ta intermediate layer, wherein the mass ratio of the Ti element to the Ta element in the Ti—Ta intermediate layer is 1:1.

[0054] Experimental example

[0055] The interface resistance test was performed on the bipolar plates with composite coatings prepared in Examples 1-3 and Comparative Examples 1-2, and the results are shown in Table 1. It can be seen from Table 1 that compared with Comparative Examples 1-2, the composite coatings in Examples 1-3 have smaller interface contact resistance, indicating that the composite coatings in Examples 1-3 have better conductive properties.

[0056] Table 1

[0057]

[0058] The bipolar plates with composite coatings prepared in Example 1 and Comparative Examples 1-2 were subjected to potentiodynamic polarization tests. Figure 2 ,from Figure 2 It can be seen that under the constant potential polarization 2V test potential, the corrosion current in Example 1 is 0.37μA / cm 2 , the corrosion current in Comparative Example 1 is 5.4 μA / cm 2 , the corrosion current in Comparative Example 2 is 0.83 μA / cm 2 , indicating that the composite coating prepared in Example 1 has better corrosion resistance.

[0059] The test method involved in the present invention is as follows

[0060] (1) The interface contact resistance test is carried out in accordance with the national standards GB / T20042.6 and GB / T20042.7. The test pressure range is 0.2-3.0MPa and the test pressure interval is 0.2MPa.

[0061] (2) The reference electrode for the potentiodynamic test was a R0305 silver-silver chloride electrode. The potential scanning range was from 0.5 V below the open circuit potential to 1.4 V (vs. Ag / AgCl). The test temperature was 80 °C and the test area was 1 cm 2 The test solution is a sulfuric acid solution with a pH of 3 and containing 2 ppm hydrofluoric acid.

[0062] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A bipolar plate composite coating, characterized in that: Its components include Ti, Ta and Si elements.

2. The bipolar plate composite coating according to claim 1, characterized in that: The mass fraction of the Ti element is 30-50%, the mass fraction of the Ta element is 40-60%, and the mass fraction of the Si element is 10-20%.

3. The bipolar plate composite coating according to claim 1, characterized in that: Its thickness is 500-2000nm.

4. The bipolar plate composite coating according to claim 1, characterized in that: The invention comprises a base layer (2), an intermediate layer (3) and a surface layer (4) which are sequentially deposited on the surface of a bipolar plate (1); the base layer (2) comprises Ti element, the intermediate layer comprises Ti element, Ta element and Si element; the surface layer (4) comprises Ta element and Si element.

5. The bipolar plate composite coating according to claim 4, characterized in that: The thickness of the primer layer (2) is 25-100 nm.

6. The bipolar plate composite coating according to claim 4, characterized in that: The thickness of the intermediate layer (3) is 200-400 nm.

7. The bipolar plate composite coating according to claim 4, characterized in that: The thickness of the surface layer (4) is 100-300 nm.

8. The bipolar plate composite coating according to claim 4, characterized in that: The mass ratio of Ti element, Ta element and Si element in the intermediate layer (3) is (3-5):(4-6):

1.

9. The bipolar plate composite coating according to claim 4, characterized in that: The mass ratio of Ta element to Si element in the surface layer (4) is (8-9):(1-2).

10. An electrolytic cell, characterized in that: It comprises a bipolar plate, on which is provided a bipolar plate composite coating as claimed in any one of claims 1 to 9.

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