Preparation method of metal bipolar plate coating, metal bipolar plate and fuel cell

Abstract

The invention discloses a preparation method of a metal bipolar plate coating, a metal bipolar plate and a fuel cell. The preparation method of the metal bipolar plate coating comprises the following steps: S1, depositing a Ti layer on a metal bipolar plate base material by adopting direct current magnetron sputtering; s2, depositing a TiAlN ceramic layer on the Ti layer by adopting high-power pulse magnetron sputtering; and the process parameters of the high-power pulse magnetron sputtering are as follows: the sputtering temperature is 150-300 DEG C, the reaction gas comprises N2, the flow of the N2 is 5-20 sccm, the power is 3-6 kW, the bias voltage is 50-250 V, and the duty ratio is 30-80%. According to the metal bipolar plate coating provided by the invention, functional gradient design and stress self-adaptive matching are realized, so that the corrosion resistance of the metal bipolar plate is remarkably improved, and excellent high-potential corrosion resistance and high conductivity are considered.

Description

Technical Field

[0001] This invention relates to a method for preparing a coating for a metal bipolar plate, a metal bipolar plate, and a fuel cell. Background Technology

[0002] As a highly efficient and clean energy conversion device, fuel cells have attracted much attention for their commercial application. Metal bipolar plates are one of the core components of a fuel cell stack, and their performance directly affects the cell's efficiency and lifespan. However, under dynamic operating conditions such as fuel cell start-up, shutdown, and load variations, reverse polarity (insufficient hydrogen supply on the anode side) can easily occur, causing the bipolar plate potential to rise sharply to above 1.5 V. At this high potential, traditional carbon-based coatings will undergo severe oxidation and corrosion, and the metal substrate will also experience ion dissolution, resulting in permanent performance degradation of the fuel cell.

[0003] To improve the corrosion resistance of metal bipolar plates, current research has shifted from carbon-based coatings to metal-ceramic coatings with superior corrosion resistance, and various technical approaches have been explored, but all have certain limitations. The mainstream approach uses noble metal coatings such as gold and platinum, but these are costly and require a thickness exceeding 100 nanometers to form an effective continuous protective layer, resulting in high expenses. Another approach is to introduce catalytically active anti-reverse electrode materials. For example, patent CN111525151B proposes a discrete distribution structure: based on a corrosion-resistant layer (such as TiN / CrN), noble metal dots / layers (Au / Pt) and independent anti-reverse electrode material layers (such as IrO2 / RuO2) are set on the surface. The noble metal ensures conductivity, while IrO2 and other materials catalyze water splitting reactions to consume overpotential. However, this approach has a complex structure, typically requiring masking processes for patterning, increasing the difficulty and cost of fabrication. In addition, some studies have focused on optimizing coating processes and compositions. For example, CN117778971A uses high-power pulsed ion plating combined with porous targets to prepare metal-ceramic coatings, while CN120048930A develops MAX phase metal-ceramic coatings with self-healing capabilities. However, these methods either face problems such as complex preparation processes that are not conducive to large-scale production, or difficulty in balancing the coating's excellent corrosion resistance with the necessary conductivity.

[0004] Therefore, how to develop a metal bipolar plate coating that combines excellent conductivity and resistance to high-potential corrosion while effectively controlling costs, and how to make its preparation process meet the needs of large-scale industrial production, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the shortcomings of existing metal bipolar plates in achieving both excellent corrosion resistance and conductivity. This invention provides a method for preparing a metal bipolar plate coating, a metal bipolar plate, and a fuel cell. The metal bipolar plate coating provided by this invention achieves functional gradient design and stress adaptive matching, resulting in a significant improvement in the corrosion resistance of the metal bipolar plate while maintaining excellent resistance to high-potential corrosion and high conductivity.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] This invention provides a method for preparing a coating on a metal bipolar plate, comprising the following steps:

[0008] S1. A Ti layer is deposited on a metal bipolar substrate using direct current magnetron sputtering (DC);

[0009] S2. A TiAlN ceramic layer is deposited on the Ti layer using high-power pulsed magnetron sputtering (HiPIMS); the process parameters of the high-power pulsed magnetron sputtering are: sputtering temperature of 150-300℃, reaction gas including N2 with a flow rate of 5-20 sccm, power of 3-6kW, bias voltage of 50-250V, and air ratio of 30-80%.

[0010] In this invention, a plasma cleaning operation may be included before step S1.

[0011] During the plasma cleaning process, argon and hydrogen gases can be introduced. The preferred flow rate of the argon gas is 20-40 sccm. The preferred flow rate of the hydrogen gas is also 20-40 sccm.

[0012] During the plasma cleaning process, the chamber pressure can be maintained at 0.1-0.3 Pa.

[0013] In the plasma cleaning process, the parameters of the ion source in the anode layer can be 2-4kW power, 100-200V bias voltage, and 85-95% space ratio.

[0014] In this invention, in step S1, the metal bipolar plate substrate may be selected from stainless steel and / or titanium alloy.

[0015] In this invention, argon gas can be introduced in step S1. The preferred flow rate of the argon gas is 200-400 sccm.

[0016] In this invention, in step S1, the chamber pressure can be maintained at 0.2-0.4 Pa.

[0017] In this invention, in step S1, the DC magnetron sputtering can use a titanium planar sputtering target.

[0018] In this invention, in step S1, the process parameters of the DC magnetron sputtering can be: power of 6-9kW, sputtering current of 10-14A, bias voltage of 80-120V, and open area ratio of 85-95%.

[0019] In this invention, in step S1, the pure Ti layer serves as a buffer layer between the metal bipolar plate substrate and the TiAlN ceramic layer. It can enhance the interfacial bonding force through Ti-Fe / Ti-O chemical bonding, avoid a sudden drop in interfacial potential, and suppress galvanic corrosion.

[0020] In this invention, in step S2, the sputtering temperature can be 150°C, 200°C, 250°C, or 300°C.

[0021] In this invention, in step S2, the reaction gas may include N2, and the N2 gas flow rate is 5 sccm, 10 sccm, 15 sccm or 20 sccm.

[0022] In this invention, in step S2, the power can be 3kW, 4kW, 5kW or 6kW.

[0023] In this invention, in step S2, the bias voltage can be 50V, 100V, 150V, 200V or 250V.

[0024] In this invention, in step S2, the empty ratio can be 30%, 40%, 60% or 80%.

[0025] In this invention, in step S2, preferably, the process parameters of the high-power pulsed magnetron sputtering are: sputtering temperature of 150°C, reaction gas including N2 with an N2 gas flow rate of 5-10 sccm, power of 5-6 kW, bias voltage of 150-200 V, and air-to-ground ratio of 30-40%;

[0026] Alternatively, the sputtering temperature can be 200°C, the reactant gas can include N2 with a flow rate of 5-20 sccm, the power can be 4-6 kW, the bias voltage can be 50-150 V, and the air-to-ground ratio can be 30-80%; for example, the sputtering temperature can be 200°C, the reactant gas can include N2 with a flow rate of 5 sccm, the power can be 4 kW, the bias voltage can be 250 V, and the air-to-ground ratio can be 30%.

[0027] Alternatively, the sputtering temperature is 250-300℃, the reaction gas includes N2 with a flow rate of 5 sccm, the power is 3-4kW, the bias voltage is 50-150V, and the air ratio is 40-60%.

[0028] In this invention, in step S2, the frequency of the high-power pulsed magnetron sputtering can be 400-600Hz.

[0029] In this invention, in step S2, the pulse width of the high-power pulsed magnetron sputtering can be 70-90 μs.

[0030] In this invention, argon gas can also be introduced in step S2; the preferred flow rate of the argon gas is 380-400 sccm.

[0031] In this invention, in step S2, the high-power pulsed magnetron sputtering can use a Ti / Al alloy target. Preferably, the atomic ratio of Ti to Al in the Ti / Al alloy target is 4:1.

[0032] In this invention, in step S2, HiPIMS high-ionization plasma forms a dense nanocrystalline structure, and Al doping enhances the compactness of the film and the stability of the passivation film, blocking Cl... - / H + Diffusion path, taking into account surface conductivity.

[0033] In this invention, the preparation method further includes the step of depositing a noble metal layer on the TiAlN ceramic layer using radio frequency sputtering (RF).

[0034] Preferably, argon gas is introduced during the deposition of the noble metal layer. The preferred flow rate of the argon gas is 500-700 sccm.

[0035] Preferably, the chamber pressure is maintained at 0.4-0.6 Pa during the deposition of the noble metal layer.

[0036] Preferably, when depositing the noble metal layer, the radio frequency sputtering uses an Au planar sputtering target and / or a Pt planar sputtering target.

[0037] Preferably, when depositing the noble metal layer, the process parameters of the radio frequency sputtering are: power of 1-2kW.

[0038] In this invention, the noble metal layer can further enhance surface conductivity, and at the same time, as a sacrificial layer for high-potential corrosion, it can further improve the anti-reverse polarity characteristics.

[0039] This invention provides a metal bipolar plate coating, which is prepared by the metal bipolar plate coating preparation method described above.

[0040] In this invention, preferably, the metal bipolar plate coating comprises a Ti layer and a TiAlN ceramic layer, wherein the thickness of the Ti layer is 200-400 nm and the thickness of the TiAlN ceramic layer is 300-500 nm. When the metal bipolar plate coating includes a noble metal layer, the thickness of the noble metal layer is 5-15 nm.

[0041] The present invention provides a metal bipolar plate, comprising a metal bipolar plate substrate and a metal bipolar plate coating; the metal bipolar plate coating is prepared by the metal bipolar plate coating preparation method described above.

[0042] In this invention, the metal bipolar plate substrate may be selected from stainless steel and / or titanium alloy.

[0043] In this invention, preferably, the metal bipolar plate coating comprises a Ti layer and a TiAlN ceramic layer, wherein the thickness of the Ti layer is 200-400 nm and the thickness of the TiAlN ceramic layer is 300-500 nm; when the metal bipolar plate coating comprises a noble metal layer, the thickness of the noble metal layer is 5-15 nm.

[0044] The present invention provides a fuel cell comprising a metal bipolar plate coating as described above, or a metal bipolar plate as described above.

[0045] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0046] The reagents and raw materials used in this invention are all commercially available.

[0047] The positive and progressive effects of this invention are as follows:

[0048] In the metal bipolar plate provided by this invention, the coating adopts a composite structure. The Ti layer increases the bonding force between the coating and the substrate and achieves stress matching; the TiAlN ceramic layer provides a strong role in resisting reverse polarity. This structure realizes functional gradient design and stress adaptive matching, which significantly improves the corrosion resistance of the metal bipolar plate, while taking into account excellent resistance to high potential corrosion (it can withstand continuous corrosion for more than 10 hours at a high potential of 1.6V) and high conductivity.

[0049] Furthermore, with a thin surface noble metal layer (≤10nm) and continuous nanoscale coverage (coverage >95%), surface conductivity is enhanced (contact resistance <2mΩ·cm). 2 This ensures anti-reverse polarity (1.6V vs SHE 10H). The design of the surface noble metal layer can also effectively balance the manufacturing cost, reducing the amount of noble metal used by 90% compared to conventional pure Pt coatings.

[0050] In terms of fabrication process, this invention achieves high-performance metal bipolar plates by optimizing the process parameters of high-power pulsed magnetron sputtering. Furthermore, the magnetron sputtering technologies employed in this invention are mainstream technologies, highly compatible with existing fuel cell bipolar plate production line equipment, facilitating large-scale production and engineering applications. Moreover, the use of conventional metal or alloy targets effectively controls raw material costs, resulting in good economic efficiency.

[0051] This invention simultaneously overcomes the challenges of durability, conductivity, and economy of metal bipolar plates, providing key component technology support for the commercialization of fuel cells. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the structure of the metal bipolar plate prepared in Example 1B.

[0053] Figure 2 This is a SEM image of the metal bipolar plate prepared in Example 1B in its initial state.

[0054] Figure 3 The image shows the SEM image of the metal bipolar plate prepared in Example 1B after corrosion testing.

[0055] Figure 4 The potentiodynamic corrosion current test curve of the metal bipolar plate prepared in Example 1B is shown.

[0056] Figure 5 The corrosion current test curve of the metal bipolar plate prepared in Example 1B at a constant potential of 1.6V is shown. Detailed Implementation

[0057] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0058] Example 1

[0059] The ultrasonically cleaned fuel cell metal bipolar plates (made of 316L stainless steel) were fixed to the workpiece gantry and then placed into the vacuum chamber of a vacuum coating equipment (purchased from Chengdu Jinshi Dongfang, model GSV10L4). Subsequently, the chamber was heated to 200°C and evacuated to a background vacuum of 2×10⁻⁶. -3 Pa, prepare the metal bipolar plate coating according to the following steps:

[0060] (1) Plasma cleaning:

[0061] Introduce 30 sccm of argon and 30 sccm of hydrogen into the anode ion source, maintaining a chamber pressure of 0.2 Pa. Turn on the anode layer ion source and set the parameters as follows: power 3 kW, bias voltage 150 V, and space ratio 90%. The argon and hydrogen are ionized within the anode layer ion source, and the resulting ions bombard the surface of the metal bipolar plate substrate for cleaning. The cleaning time is approximately 1800 s.

[0062] (2) Deposition of pure metal substrate by DC magnetron sputtering:

[0063] Evacuate the chamber to 5×10⁻⁶. -3After Pa, 300 sccm of argon gas was introduced into the chamber, and the pressure was maintained at 0.3 Pa until it stabilized. A titanium planar sputtering target was used, and the following parameters were set: power of 8 kW, sputtering current of 12 A, bias voltage of 100 V, and air ratio of 90%.

[0064] (3) High-power pulsed magnetron sputtering (HiPIMS) deposition of TiAlN ceramic layers:

[0065] Evacuate the chamber to 5×10⁻⁶. -3 After Pa, 395 sccm of argon and 5 sccm of nitrogen were introduced into the chamber, maintaining a pressure of 0.4 Pa until stable. A Ti / Al alloy target (Ti to Al atomic ratio of 4:1) was used, with the following parameters set: power of 4 kW, frequency of 500 Hz, pulse width of 80 μs, bias voltage of 250 V, and empty ratio of 30%.

[0066] Through the above steps, a coated metal bipolar plate is obtained. The coating structure is as follows: the bottom layer is made of pure titanium (Ti) with a thickness of 300 nm, and the ceramic layer is made of TiAlN with a thickness of 400 nm.

[0067] Examples 2-17 and Comparative Examples 1-2

[0068] Based on Example 1, Examples 2-17 and Comparative Examples 1-2 adjusted the sputtering temperature, N2 gas flow rate, power, bias voltage and air ratio in step (3), as shown in Table 1 below.

[0069] Table 1

[0070]

[0071] Examples 1B, 3B, 9B and 14B

[0072] Examples 1B, 3B, 9B, and 14B, based on Examples 1, 3, 9, and 14 respectively, further include step (4): radio frequency (RF) sputtering of a noble metal surface layer.

[0073] Evacuate the chamber to 5×10⁻⁶. -3 After Pa, 600 sccm of argon gas was introduced into the chamber, and the pressure was maintained at 0.5 Pa until it stabilized. Au planar sputtering target was used, and RF sputtering power supply was used with the following parameters: power of 1.5 kW, bias voltage of 100 V, and air-to-ground ratio of 30%.

[0074] Through the above steps, a coated metal bipolar plate is obtained. Figure 1 The diagram shows the structure. The coating structure is as follows: the bottom layer is made of pure titanium (Ti) with a thickness of 300 nm, the ceramic layer is made of TiAlN with a thickness of 400 nm, and the noble metal layer is made of Au with a thickness of 10 nm.

[0075] Example 1: Morphological Diagram

[0076] The SEM images of the metal bipolar plate prepared in Example 1B in its initial state and after etching are shown below. Figure 2 and Figure 3 As shown.

[0077] The corrosion test conditions were as follows: test voltage 1.6V (vs. SHE), test time 10h; water bath temperature 80℃, pH=3 H2SO4+0.1ppm HF, and oxygen was introduced into the electrolyte solution at a flow rate of 20mL / min.

[0078] As can be seen from the comparison of the figures, at a high potential of 1.6V, only a portion of the Au particles dissolve, and they can withstand corrosion for up to 10 hours, indicating that this structure can effectively improve the resistance to high potential corrosion.

[0079] Example 2: Corrosion Resistance

[0080] The metal bipolar plates prepared in the above embodiments and comparative examples were subjected to corrosion resistance tests, including potentiodynamic tests, constant potential tests, and contact resistance tests.

[0081] (1) Potential dynamics test

[0082] Potentiodynamic testing was performed on Example 1B using an electrochemical workstation. The testing conditions were as follows: voltage range -0.6V to 1.2V, water bath temperature 80℃, electrolyte pH=3 H₂SO₄ solution (containing 0.1ppm HF), and oxygen was introduced into the electrolyte solution at a flow rate of 20mL / min. The corrosion current density of the sample was determined by fitting a curve using the Tafel extrapolation method and finding the intersection of the two Tafel lines.

[0083] Test results are as follows Figure 4 As shown, the corrosion current density in Example 1B is 1.8E-7 A·cm. -2 .

[0084] (2) Constant potential test and contact resistance test

[0085] Electrochemical workstations were used to perform constant potential tests on Examples 1-17, Examples 1B, 3B, 9B and 14B and Comparative Examples 1-2, and their corresponding contact resistances were measured.

[0086] A. Constant Potential Test

[0087] The test voltage was 1.6V (vs. SHE), the water bath temperature was 80℃, the electrolyte was a pH=3 H2SO4 solution (containing 0.1ppmHF), and oxygen was introduced into the electrolyte solution at a flow rate of 20mL / min. The test time for Examples 1-17 and Comparative Examples 1-2 was 1 h, and the test time for Examples 1B, 3B, 9B, and 14B was 10 h.

[0088] Taking Example 1B as an example, the corrosion current curve after the constant potential test is as follows: Figure 5 As shown.

[0089] B. Contact resistance test

[0090] Contact resistance was tested using a low-resistance meter with gold-plated copper electrodes. The steps are as follows:

[0091] S1. The resistance value was measured using a low-resistance meter with gold-plated copper electrodes. During measurement, one layer of carbon paper and one sample were placed sequentially between the two copper electrodes (coated side facing the carbon paper). The resistance value under a pressure of 1.5 MPa was recorded as R1.

[0092] S2. Place a layer of brand-new carbon paper between the two copper electrodes and test again. Record the resistance value under a pressure of 1.5 MPa as R2.

[0093] S3. Calculate the contact resistance: R = (R1 - R2) × S, where S is the geometric area of ​​the part of the sample that is in direct contact with the carbon paper.

[0094] The contact resistance test results of Examples 1-17 and Comparative Examples 1-2 are shown in Table 2, and the contact resistance test results of Examples 1B, 3B, 9B and 14B are shown in Table 3.

[0095] Table 2

[0096]

[0097] Table 3

[0098]

[0099] As shown in the table above, the metal bipolar plate prepared by the optimized high-power pulsed magnetron sputtering process parameters of this invention has excellent corrosion resistance and conductivity.

[0100] Regarding corrosion resistance, potentiodynamic testing showed a corrosion current density as low as 1.8 × 10⁻⁶. -7 A·cm -2This indicates that it possesses excellent basic corrosion resistance; under harsh conditions (1.6V vs. SHE, 80℃, acidic oxygen-bearing environment), the structure can effectively resist high-potential corrosion and withstand continuous testing for up to 10 hours.

[0101] Regarding conductivity and durability, the metal bipolar plate provided by this invention balances low initial contact resistance and excellent retention rate after corrosion. Compared with Comparative Examples 1 and 2, the metal bipolar plate fabricated by the optimized high-power pulsed magnetron sputtering process parameters of this invention exhibits a significantly reduced difference in resistance before and after corrosion, resulting in significantly improved durability. In some preferred embodiments, the initial contact resistance can be as low as 2 mΩ·cm. 2 In Example 1B, the contact resistance decreased only from 1.36 mΩ·cm after 10 hours of corrosion. 2 Slightly increased to 1.44 mΩ·cm 2 Its durability is outstanding.

[0102] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method of preparing a coating for a metal bipolar plate, characterized by, It comprises the following steps: S1. Depositing a Ti layer on a metal bipolar plate substrate by direct current magnetron sputtering; S2. Depositing a TiAlN ceramic layer on the Ti layer by high-power pulsed magnetron sputtering; the process parameters of the high-power pulsed magnetron sputtering are: a sputtering temperature of 150-300℃, a reaction gas comprising N2 and a N2 gas flow of 5-20sccm, a power of 3-6kW, a bias voltage of 50-250V, and an empty ratio of 30-80%.

2. The method of making a metal bipolar plate coating of claim 1, wherein, In step S2, the sputtering temperature is 150℃, 200℃, 250℃ or 300℃; And / or, in step S2, the reaction gas comprises N2, and the N2 gas flow is 5sccm, 10sccm, 15sccm or 20sccm; And / or, in step S2, the power is 3kW, 4kW, 5kW or 6kW; And / or, in step S2, the bias voltage is 50V, 100V, 150V, 200V or 250V; And / or, in step S2, the empty ratio is 30%, 40%, 60% or 80%.

3. The method of claim 2, wherein the metal bipolar plate coating is prepared by a process comprising: The process parameters of the high-power pulsed magnetron sputtering are: a sputtering temperature of 150℃, a reaction gas comprising N2 and a N2 gas flow of 5-10sccm, a power of 5-6kW, a bias voltage of 150-200V, and an empty ratio of 30-40%; Or, a sputtering temperature of 200℃, a reaction gas comprising N2 and a N2 gas flow of 5-20sccm, a power of 4-6kW, a bias voltage of 50-150V, and an empty ratio of 30-80%; for example, a sputtering temperature of 200℃, a reaction gas comprising N2 and a N2 gas flow of 5sccm, a power of 4kW, a bias voltage of 250V, and an empty ratio of 30%; Or, a sputtering temperature of 250-300℃, a reaction gas comprising N2 and a N2 gas flow of 5sccm, a power of 3-4kW, a bias voltage of 50-150V, and an empty ratio of 40-60%.

4. The method of making a metal bipolar plate coating of claim 1, wherein, In step S2, the frequency of the high-power pulsed magnetron sputtering is 400-600Hz; And / or, in step S2, the pulse width of the high-power pulsed magnetron sputtering is 70-90μs; And / or, in step S2, argon gas is also introduced; the argon gas flow is preferably 380-400sccm; And / or, in step S2, the high-power pulsed magnetron sputtering uses a Ti / Al alloy target; preferably, the atomic ratio of Ti to Al in the Ti / Al alloy target is 4:

1.

5. The method of making a metal bipolar plate coating of claim 1, wherein, Before step S1, a plasma cleaning operation is further included; And / or, in step S1, argon gas is introduced; the argon gas flow is preferably 200-400sccm; And / or, in step S1, the chamber pressure is kept at 0.2-0.4Pa; And / or, in step S1, the direct current magnetron sputtering uses a titanium plane sputtering target; And / or, in step S1, the process parameters of the direct current magnetron sputtering are: a power of 6-9kW, a sputtering current of 10-14A, a bias voltage of 80-120V, and an empty ratio of 85-95%.

6. The method of making a metal bipolar plate coating of claim 5, wherein, The argon gas flow is preferably 20-40 sccm; the hydrogen gas flow is preferably 20-40 sccm; And / or, the chamber pressure during the plasma cleaning is kept at 0.1-0.3 Pa; And / or, the anode layer ion source parameters during the plasma cleaning are: power 2-4 kW, bias 100-200 V, and empty ratio 85-95%.

7. The method of making a metal bipolar plate coating according to any one of claims 1-6, wherein, The preparation method further comprises a step of depositing a noble metal layer on the TiAlN ceramic layer by radio frequency sputtering; Preferably, argon gas is introduced during the deposition of the noble metal layer; the argon gas flow is preferably 500-700 sccm; Preferably, the chamber pressure during the deposition of the noble metal layer is kept at 0.4-0.6 Pa; Preferably, the radio frequency sputtering during the deposition of the noble metal layer uses an Au planar sputtering target and / or a Pt planar sputtering target; Preferably, the radio frequency sputtering during the deposition of the noble metal layer has a power of 1-2 kW.

8. A metal bipolar plate characterized by It comprises a metal bipolar plate substrate and a metal bipolar plate coating; the metal bipolar plate coating is prepared by the preparation method of the metal bipolar plate coating according to any one of claims 1-7.

9. The metal bipolar plate of claim 8, wherein The metal bipolar plate substrate is selected from stainless steel and / or titanium alloy; And / or, the metal bipolar plate coating comprises a Ti layer and a TiAlN ceramic layer; the thickness of the Ti layer is 200-400 nm, and the thickness of the TiAlN ceramic layer is 300-500 nm; when the metal bipolar plate coating comprises a noble metal layer, the thickness of the noble metal layer is 5-15 nm.

10. A fuel cell characterized by comprising: It comprises the metal bipolar plate according to claim 8 or 9.

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