PEM water electrolysis hydrogen production bipolar plate functional coating and preparation method thereof

Abstract

The invention relates to the technical field of hydrogen production, in particular to a PEM water electrolysis hydrogen production bipolar plate functional coating and a preparation method, and the PEM water electrolysis hydrogen production bipolar plate functional coating comprises at least one metal carbide doped metal layer. As the bipolar plate coating does not contain noble metal elements, the bipolar plate coating provided by the invention is low in cost, and the manufacturing cost of the PEM hydrogen production electrolytic cell can be reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of hydrogen production, in particular to a PEM water electrolysis hydrogen production bipolar plate functional coating and a preparation method. BACKGROUND

[0002] Proton exchange membrane (PEM) water electrolysis hydrogen production is an efficient and environmentally friendly hydrogen production technology, and is an important direction of water electrolysis hydrogen production. Among them, the bipolar plate is one of the key components of the PEM electrolysis tank, and the weight accounts for 60-80% of the electric pile, and the cost accounts for about 40%. At the same time, the bipolar plate has the important functions of current collection, conduction, connection of single modules and the like. Therefore, an ideal bipolar plate should have good heat conduction, electrical conductivity and mechanical properties and the like. The metal bipolar plate is widely studied because of the above-mentioned properties. However, the working environment of the PEM electrolysis tank is acidic (pH = 2-5), high temperature (60-80 o C) and high voltage (1.4-2.2 V vs SHE). In this environment, the metal bipolar plate is easily corroded, thereby shortening the service life of the electric pile. In addition, the oxide film formed on the metal surface has low conductivity, thereby increasing the interface contact resistance between the bipolar plate and the gas diffusion layer, and further increasing the ohmic loss. Therefore, it is very important to develop a low-resistance and high-corrosion-resistant coating on the surface of the bipolar plate.

[0003] At present, the coating materials used on the surface of the PEM electrolysis tank bipolar plate are mostly noble metals (Pt, Ru, Ir and the like), nitrides (TiN, CrN and the like), conductive oxides (Ti4O7, indium tin oxide and the like) and other corrosion-resistant coatings. The noble metal coating has good corrosion resistance and conductivity, and can significantly improve the comprehensive performance of the bipolar plate. However, the expensive price of the noble metal leads to a substantial increase in the preparation cost, thereby limiting its commercial application. The nitride coating can exhibit excellent conductivity, but the coating will be dissolved at high potential and lose the protection effect, so the nitride coating cannot be applied on a large scale. The conductive oxide coating has problems of complex preparation process, poor process stability, high cost and the like. The metal-based coating has good application value in the application of the bipolar plate due to the advantages in the material cost and the preparation process, but has the problem of rising contact resistance caused by corrosion and oxidation. SUMMARY

[0004] The purpose of the present application is to provide a PEM water electrolysis hydrogen production bipolar plate functional coating and a preparation method, which solves the technical problem of rising contact resistance caused by corrosion and oxidation of the metal-based coating in the prior art.

[0005] The application discloses a PEM water electrolysis hydrogen production bipolar plate functional coating, which comprises at least one metal carbide doped metal layer.

[0006] Further, the metal carbide is one or more of TiC, WC, NbC, ZrC, TaC and HfC.

[0007] Further, the metal element accounts for 65-98% and the C element accounts for 2-35% in the coating in terms of atomic percentage.

[0008] Further, the doping metal is one or more of Ti, Zr, Nb, Ta and Hf.

[0009] Further, the coating comprises a metal transition layer and a metal carbide-doped metal layer.

[0010] Further, the metal transition layer and the metal carbide-doped metal layer are alternately stacked, and the alternating period is ≤5.

[0011] Further, the metal transition layer is coated on the bipolar plate.

[0012] Further, the bipolar plate is a metal titanium bipolar plate.

[0013] A preparation method of a PEM electrolytic water hydrogen production bipolar plate functional coating, the preparation method is direct current magnetron sputtering.

[0014] Further, the direct current magnetron sputtering comprises the following steps: The coating is deposited on the surface of the etched and activated bipolar plate by co-sputtering a metal target and a metal carbide target, or by alternately sputtering a metal target and a metal carbide target.

[0015] Further, the metal target material is one or more of Ti, Zr, Nb, Ta and Hf, and the purity of the target material is higher than 99.9%.

[0016] Further, the metal carbide target material is one or more of TiC, WC, NbC, ZrC, TaC and HfC, and the purity of the target material is higher than 99.5%.

[0017] Further, the bipolar plate is etched by Ar plasma under vacuum conditions before sputtering the transition layer, and Ar is used as the working gas when sputtering the transition layer.

[0018] Further, the vacuum condition is that the base vacuum of the vacuum chamber is less than 5 × 10 -3 Pa, and the distance between the surface of the bipolar plate and the sputtering target material is 5-15 cm.

[0019] Further, when etching the bipolar plate by Ar plasma, an ion source assisted method is used, or a high negative bias voltage is applied to the bipolar plate, and the bias voltage is less than -450 V.

[0020] Further, the bipolar plate is cleaned before etching.

[0021] Further, the bipolar plate cleaning process uses organic solvents, alkaline cleaning solution or ultrasonic cleaning with water.

[0022] Further, when the coating is a double-layer or multi-layer structure, the metal transition layer is deposited by sputtering with a metal target, and the metal carbide doped metal layer is deposited by co-sputtering with a metal target and a metal carbide target.

[0023] Further, during the co-sputtering deposition of the metal carbide doped metal layer, the metal target uses high target current or high target power, and the metal carbide target uses low target current or low target power.

[0024] Compared with the prior art, the present application has the following beneficial effects: 1. Since it does not contain noble metal elements, the bipolar plate coating provided by the present application has low cost, which can reduce the manufacturing cost of PEM hydrogen production electrolysis cell; 2. By reasonably selecting metal and metal carbide target materials, the functional coating preparation method provided by the present application is suitable for establishing a continuous and stable production line through co-sputtering with multiple targets; 3. The proton exchange membrane water electrolysis hydrogen production bipolar plate surface coating provided by the present application can significantly improve the corrosion resistance of titanium bipolar plate under PEM hydrogen production working conditions, and the contact resistance of the corroded bipolar plate surface is significantly lower than that of the bipolar plate coated with metal Nb, thereby effectively improving the electrolysis efficiency and service life of PEM water electrolysis hydrogen production electrolysis cell. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. It should be understood that the following drawings only represent some embodiments of the present application, and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0026] Figure 1 The potentiodynamic polarization curve of the Ta-WC coating of the present application embodiment 1.

[0027] Figure 2 The potentiodynamic polarization curve of the Ta-WC coating of the present application embodiment 1. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all.

[0029] Example 1 The present embodiment discloses a PEM electrolytic water hydrogen production bipolar plate functional coating and a preparation method thereof, comprising the following steps: (1) Select a metal titanium bipolar plate with a runner, and clean the bipolar plate in ethanol and petroleum ether respectively by ultrasonic cleaning to remove surface oil stains and debris, wherein the thickness of the bipolar plate is about 2 mm.

[0030] (2) Fix the cleaned metal titanium bipolar plate on a sample holder, and transfer the sample holder to the working position of the sputtering coating chamber. When the surface of the bipolar plate is parallel to the surface of the target, the distance between them is 10 cm. After closing the coating chamber, vacuumize the chamber, and when the pressure in the chamber is less than 5.0 × 10 -3 Pa, introduce Ar into the chamber, and maintain the vacuum in the chamber at about 0.1 Pa. After the gas pressure is stable, apply a -600 V pulsed direct current bias to the surface of the substrate for plasma etching, and the etching time is 30 minutes.

[0031] (3) After the plasma etching is completed, turn on the target cathode power supply to start depositing the coating. The coating chamber is configured with 4 direct current magnetron cathodes, two Ta and two WC targets are installed respectively, and the target current control mode is adopted in the coating process. Among them, the transition layer is deposited by sputtering a metal target, the target current is 5.0 A, the metal carbide doped metal layer is deposited by co-sputtering a metal Ta and a WC target, the target currents are 5.0 A and 0.6 A respectively, the deposition pressure is about 0.1 Pa, the bipolar plate bias voltage is -200 V, and the coating deposition time is 240 minutes. In order to obtain a uniform WC doped metal Ta coating, the bipolar plate is rotated at a speed of 10 revolutions per minute on a three-axis hanger, and the two surfaces of the bipolar plate are plated. After the coating is completed, naturally cool to a vacuum chamber temperature below 80 ℃, then charge the vacuum chamber, open the chamber, and take out the sample.

[0032] In the present embodiment, the coating deposited on the surface of the bipolar plate comprises a Ta transition layer and a Ta-WC metal carbide doped metal layer. The thickness of the Ta transition layer is 400 nm, and the thickness of the Ta-WC metal carbide doped metal layer is 2.8 μm. In the metal carbide doped metal layer, metal Ta is the main phase and WC is the doped phase. In terms of atomic percentage, the metal content of the metal carbide doped metal layer is 97.5 %, and the carbon content is 2.5 %. The initial contact resistance between the coating and the carbon paper is 17.8 mΩ·cm 2 Under the simulated PEM hydrogen production harsh conditions (0.5 M H2SO4+ 5 ppm HF, 80 o C), the corrosion current density of the potentiodynamic polarization test is 0.824 μA / cm 2 Figure 1 ​), the current density of the potentiostatic polarization test for 12 h was 0.45 μA / cm 2 ( Figure 2 , the contact resistance after the potentiostatic test was 265 mΩ·cm 2 .

[0033] Example 2 This example is a preferred embodiment of the present application, which discloses a PEM water electrolysis hydrogen generation bipolar plate functional coating and a preparation method thereof. The only change is the WC target sputtering current based on Example 1.

[0034] In this example, the metal Ta and WC target currents are 5.0 and 1.2 A, respectively, and the coating includes a Ta transition layer and a Ta-WC metal carbide doped metal layer. The thickness of the Ta transition layer is 400 nm, and the thickness of the Ta-WC metal carbide doped metal layer is 3.2 μm. In the metal carbide doped metal layer, metal Ta is the main phase, and WC is the doped phase. In terms of atomic percentage, the metal content of the metal carbide doped metal layer is 92.8 %, and the carbon content is 7.2 %. The initial contact resistance between the coating and the carbon paper is 15.2 mΩ·cm 2 Under the simulated harsh conditions of PEM hydrogen generation, the corrosion resistance of the coating was evaluated, and the potentiodynamic polarization test showed that the corrosion current density of the coating was 0.90 μA / cm 2 , the current density of the potentiostatic polarization test for 24 h was 0.87 μA / cm 2 , and the surface contact resistance after the test was 348 mΩ·cm 2 .

[0035] Example 3 This example is a preferred embodiment of the present application, which discloses a PEM water electrolysis hydrogen generation bipolar plate functional coating and a preparation method thereof. The only change is the WC target sputtering current based on Example 1.

[0036] In this example, the metal Ta and WC target currents are 5.0 and 1.8 A, respectively, and the deposited coating includes a Ta transition layer and a Ta-WC metal carbide doped metal layer. The thickness of the metal Ta transition layer is about 400 nm, and the thickness of the Ta-WC metal carbide doped metal layer is about 3.4 μm. In terms of atomic percentage, the metal content of the metal carbide doped metal layer is 87.2 %, and the carbon content is 12.8 %. The initial contact resistance between the coating and the carbon paper is 25 mΩ·cm 2 Under the simulated harsh conditions of PEM hydrogen generation, the corrosion resistance of the coating was evaluated, and the potentiodynamic polarization test showed that the corrosion current density of the coating was 1.05 μA / cm 2, the current density of the potentiostatic polarization test for 24 h was 0.93 μA / cm 2 , the surface contact resistance after the test was 575 mΩ·cm 2 .

[0037] Example 4 The present example discloses a PEM water electrolysis hydrogen generation bipolar plate functional coating and a preparation method thereof as a preferred embodiment of the present application. The only change on the basis of Example 1 is that the sputtering process uses metal Nb and TiC targets, and further includes a metal transition layer. The transition metal is Nb, and the metal carbide is TiC.

[0038] In the present example, the metal Nb and TiC target currents are 5.0 and 0.6 A respectively, and the deposited coating includes a Nb transition layer and a Nb-TiC metal carbide doped metal layer. Among them, the thickness of the metal Nb transition layer is about 400 nm, and the thickness of the Nb-TiC metal carbide doped metal layer is about 2.0 μm. In terms of atomic percentage, the metal content of the metal carbide doped metal layer is 95.9 %, and the carbon content is 4.1 %. The initial contact resistance between the coating and the carbon paper is 16 mΩ·cm 2 under the simulated harsh conditions of PEM hydrogen generation. The corrosion current density of the coating is 0.35 μA / cm 2 , the current density of the potentiostatic polarization test for 24 h is 0.22 μA / cm 2 , the surface contact resistance after the test is 522 mΩ·cm 2 .

[0039] Example 5 The present example discloses a PEM water electrolysis hydrogen generation bipolar plate functional coating and a preparation method thereof as a preferred embodiment of the present application. The only change on the basis of Example 1 is that the sputtering process uses metal Nb and NbC targets, and further includes a metal transition layer. The transition metal is Nb, and the metal carbide is NbC.

[0040] In the present example, the metal Nb and NbC target currents are 5.0 and 0.8 A respectively, and the deposited coating includes a Nb transition layer and a Nb-C metal carbide doped metal layer. Among them, the thickness of the metal Nb transition layer is about 400 nm, and the thickness of the Nb-C metal carbide doped metal layer is about 2.1 μm. In terms of atomic percentage, the metal content of the metal carbide doped metal layer is 94.3 %, and the carbon content is 5.7 %. The initial contact resistance between the coating and the carbon paper is 11 mΩ·cm 2 under the simulated harsh conditions of PEM hydrogen generation. The corrosion current density of the coating is 0.63 μA / cm2 , the current density of the potentiostatic polarization test for 24 h was 0.1 μA / cm 2 , the surface contact resistance after the test was 155 mΩ·cm 2 .

[0041] Example 6 This example serves as a preferred embodiment of the present application, which discloses a PEM water electrolysis hydrogen production bipolar plate functional coating and a preparation method thereof. The only change from Example 1 is that the sputtering process uses metal Nb and ZrC targets, and further includes a metal transition layer, the transition layer metal is Nb, and the metal carbide is ZrC.

[0042] In this example, the metal Nb and ZrC target currents are 5.0 and 0.6 A respectively, and the deposited coating includes a Nb transition layer and a Nb-ZrC metal carbide doped metal layer. Among them, the thickness of the metal Nb transition layer is about 400 nm, and the thickness of the Nb-ZrC metal carbide doped metal layer is about 2.2 μm. In terms of atomic percentage, the metal content of the metal carbide doped metal layer is 96.2 %, and the carbon content is 3.8 %. The initial contact resistance between the coating and the carbon paper is 16 mΩ·cm 2 under simulated PEM hydrogen production harsh conditions, the corrosion current density of the coating is 0.28 μA / cm 2 , the current density of the potentiostatic polarization test for 24 h was 0.41 μA / cm 2 , the surface contact resistance after the test was 182 mΩ·cm 2 .

[0043] Comparative Example 1 This example serves as a preferred embodiment of the present application, which discloses a PEM water electrolysis hydrogen production bipolar plate functional coating and a preparation method thereof. The only change from Example 1 is that the sputtering WC target current is changed, and in terms of atomic percentage, the metal content of the metal carbide doped metal layer is 64.8 %, and the carbon content is 35.2 %.

[0044] In this example, the metal Ta and WC target currents are 5.0 and 2.5 A respectively, and the coating includes a Ta transition layer and a Ta-WC metal carbide doped metal layer. Among them, the thickness of the Ta transition layer is 400 nm, and the thickness of the Ta-WC metal carbide doped metal layer is 3.8 μm. In the metal carbide doped metal layer, Ta is the main phase and WC is the doped phase. The initial contact resistance between the coating and the carbon paper is 46 mΩ·cm 2 under simulated PEM hydrogen production harsh conditions, the corrosion current density of the coating is 2.3 μA / cm 2, the current density of the potentiostatic polarization test for 24 h was 6.4 μA / cm 2 , the surface contact resistance after the test was greater than 4000 mΩ·cm 2 .

[0045] Comparative Example 2 This example serves as a pair of comparative examples of the present application, and discloses a PEM water electrolysis hydrogen production bipolar plate functional coating and a preparation method thereof. The only change from Example 1 is that the sputtering WC target current is changed, and the metal carbide doped metal layer has a metal content of 99.2% and a carbon content of 0.8% in terms of atomic percentage.

[0046] In this example, the metal Ta and WC target currents are 5.0 and 0.2 A, respectively, and the coating includes a Ta transition layer and a Ta-WC metal carbide doped metal layer. The Ta transition layer has a thickness of 400 nm, and the Ta-WC metal carbide doped metal layer has a thickness of 2.8 μm. In the metal carbide doped metal layer, Ta is the main phase and WC is the doped phase. The initial contact resistance between the coating and the carbon paper is measured to be 11 mΩ·cm 2 under a pressure of 1.2 MPa. The corrosion resistance of the coating is evaluated under simulated harsh conditions of PEM hydrogen production, and the potentiodynamic polarization measurement shows that the corrosion current density of the coating is 0.55 μA / cm 2 . The current density of the potentiostatic polarization test for 24 h is 0.86 μA / cm 2 . The surface contact resistance after the test is greater than 1000 mΩ·cm 2 .

[0047] Comparative Example 3 This example serves as a pair of comparative examples of the present application, and discloses a PEM water electrolysis hydrogen production bipolar plate functional coating and a preparation method thereof. The only change from Example 1 is that the sputtering process uses metal Nb and TiC targets, and also includes a metal transition layer. The transition layer metal is Nb, and the metal carbide is TiC. The coating has a Nb content of 62.8% and a carbon content of 37.2% in terms of atomic percentage.

[0048] In this example, the metal Nb and TiC target currents are 5.0 and 3.0 A, respectively, and the deposited coating includes a Nb transition layer and a Nb-TiC metal carbide doped metal layer. The metal Nb transition layer has a thickness of about 400 nm, and the Nb-TiC metal carbide doped metal layer has a thickness of about 2.3 μm. The initial contact resistance between the coating and the carbon paper is measured to be 36 mΩ·cm 2 under a pressure of 1.2 MPa. The corrosion resistance of the coating is evaluated under simulated harsh conditions of PEM hydrogen production, and the potentiodynamic polarization measurement shows that the corrosion current density of the coating is 2.1 μA / cm 2, the current density of the potentiostatic polarization test for 24 h is 6.35 μA / cm 2 , the surface contact resistance after the test is 3165 mΩ·cm 2 .

[0049] The above are the embodiments enumerated by the present embodiment, but the present embodiment is not limited to the above optional embodiments, and those skilled in the art can obtain other various embodiments by arbitrarily combining the above modes with each other. The above specific embodiments should not be understood as limiting the protection scope of the present embodiment, and the protection scope of the present embodiment should be defined by the claims, and the specification can be used to explain the claims.

Claims

1. A PEM electrolysis water-splitting hydrogen generation bipolar plate functional coating, characterized by: The coating comprises at least one metal carbide doped metal layer.

2. The PEM water electrolysis hydrogen generation bipolar plate functional coating according to claim 1, characterized in that: The metal carbide is one or more of TiC, WC, NbC, ZrC, TaC and HfC.

3. The PEM water electrolysis hydrogen generation bipolar plate functional coating according to claim 1, characterized in that: In the metal carbide, the metal element accounts for 65-98% and the C element accounts for 2-35% in terms of atomic percentage.

4. The PEM water electrolysis hydrogen generation bipolar plate functional coating of claim 1, wherein: The doped metal is one or more of Ti, Zr, Nb, Ta and Hf.

5. The PEM water electrolysis hydrogen generation bipolar plate functional coating according to claim 1, characterized in that: The coating comprises a metal transition layer and a metal carbide doped metal layer.

6. The PEM water electrolysis hydrogen generation bipolar plate functional coating according to claim 5, characterized in that: The metal transition layer and the metal carbide doped metal layer are alternately stacked, and the alternating period is ≤5.

7. A method of producing a PEM water electrolysis hydrogen generation bipolar plate functional coating according to any one of claims 1 to 6, characterized in that: The preparation method is direct current magnetron sputtering.

8. The method according to claim 7, wherein the method is characterized by: The direct current magnetron sputtering comprises the following steps: The coating is deposited on the surface of the etched and activated bipolar plate by co-sputtering a metal target and a metal carbide target or alternately sputtering a metal target and a metal carbide target.

9. The method of claim 8, wherein the method further comprises: depositing a layer of platinum on the surface of the bipolar plate; and depositing a layer of iridium on the layer of platinum. When the coating is a double-layer or multi-layer structure, the metal transition layer is deposited by sputtering a metal target, and the metal carbide doped metal layer is deposited by co-sputtering a metal target and a metal carbide target.

10. The method of claim 8, wherein the method further comprises: In the co-sputtering deposition process of the metal carbide doped metal layer, the metal target uses high target current or high target power, and the metal carbide target uses low target current or low target power.

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