A fuel cell bipolar plate coating and its method of manufacture and use

Abstract

The application discloses a fuel cell bipolar plate coating and a preparation method and application thereof, and belongs to the technical field of metal material surface coating. The fuel cell bipolar plate coating comprises a base layer, an intermediate layer and an outer layer which are stacked in sequence, wherein the base layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nano composite phase structure of TiC and Ti3SiC2. The fuel cell bipolar plate coating has the synergistic effect of the specific nano composite phase of the outer layer, the intermediate layer and the base layer, effectively improves the hydrophobicity and corrosion resistance of the fuel cell bipolar plate, and reduces the contact resistance of the interface of the fuel cell bipolar plate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal material surface coating, more particularly to a fuel cell bipolar plate coating, a preparation method and application thereof. BACKGROUND

[0002] Proton exchange membrane fuel cell has the effect of converting chemical energy into electrical energy, with high conversion rate, green and pollution-free, environmentally friendly, and due to its high power density, low working temperature, fast start, and is expected to replace traditional internal combustion engine. The bipolar plate is one of the core components of the fuel cell, accounting for 40% of the cost of the entire fuel cell stack, and its main functions include electrical conductivity, thermal conductivity, uniform delivery of reaction gas, and timely discharge of excess water. The traditional graphite bipolar plate is difficult to commercialize due to its brittleness, poor processability, and high cost. The electrical conductivity of the composite bipolar plate needs to be improved, and the influencing factors are more, and the performance is not stable enough. The metal bipolar plate made of stainless steel and titanium alloy has good mechanical properties and electrical conductivity, and is easy to process and commercialize. However, the metal bipolar plate is prone to corrosion in acidic solution, and the corrosion of the metal bipolar plate in the environment of the proton exchange membrane fuel cell releases metal ions which are toxic to the proton exchange membrane, and the metal bipolar plate will be passivated when it encounters acid, which greatly reduces the electrical conductivity and the output power. How to ensure the electrical conductivity of the metal bipolar plate at a low cost and improve its corrosion resistance is a bottleneck restricting the bipolar plate.

[0003] The prior art discloses a double-layer coating of a fuel cell metal connector, the outer layer is Ti3SiC2, and the inner layer is a TiC layer, which can improve the corrosion resistance and electrical conductivity of the proton exchange membrane fuel cell bipolar plate, the corrosion current density is 12 μA / cm 2 , and the contact resistance is 6.5 mΩ·cm 2 . However, the corrosion current density is still large, the corrosion resistance is poor, and the fuel cell bipolar plate cannot meet the corrosion resistance requirements, and the problem of hydrophobicity of the coating has not been solved. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the defects and deficiencies of the poor hydrophobicity of the existing fuel cell bipolar plate coating, and to provide a fuel cell bipolar plate coating, which effectively improves the corrosion resistance and hydrophobicity of the fuel cell bipolar plate through the synergistic effect of the specific nano-composite phase of the outer layer, the intermediate layer and the primer layer, and also reduces the contact resistance of the fuel cell bipolar plate interface.

[0005] Another object of the present application is to provide a fuel cell bipolar plate coating for preparing a fuel cell bipolar plate.

[0006] Still another object of the present application is to provide a fuel cell bipolar plate.

[0007] The present application also provides a method for preparing the fuel cell bipolar plate.

[0008] The above object of the present application is achieved by the following technical solutions.

[0009] A fuel cell bipolar plate coating, comprising a primer layer, an intermediate layer and an outer layer stacked in sequence, wherein the primer layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nano-composite phase structure of TiC and Ti3SiC2.

[0010] It should be noted that:

[0011] In the fuel cell bipolar plate coating of the present application, the outer layer has two phase structures of TiC and Ti3SiC2, which exist in the form of nano-composite phase. Since the TiC phase has excellent corrosion resistance and hydrophobicity, and the Ti3SiC2 phase has excellent electrical conductivity, the nano-composite phase with the two phases not only has excellent electrical conductivity, but also has improved corrosion resistance and hydrophobicity. Therefore, the fuel cell bipolar plate coating of the present application can improve the hydrophobicity and corrosion resistance of the fuel cell bipolar plate, and reduce the contact resistance of the interface of the fuel cell bipolar plate.

[0012] Preferably, the intermediate layer is one or more of metal Ti, Zr, Cr, TiN, CrN or ZrN.

[0013] Further preferably, the intermediate layer is one or more of TiN, CrN or ZrN.

[0014] More preferably, the intermediate layer is TiN.

[0015] Preferably, the primer layer is one or more of metal Ti, Cr, Zr.

[0016] Further preferably, the primer layer is Cr or Ti.

[0017] Preferably, the thickness of the outer layer is 0.1-3.0 μm.

[0018] Preferably, the thickness of the intermediate layer is 50-500 nm.

[0019] Further preferably, the thickness of the intermediate layer is 80-450 nm.

[0020] Preferably, the thickness of the primer layer is 50-500 nm.

[0021] Further preferably, the thickness of the primer layer is 100-250 nm.

[0022] Preferably, a transition layer is further included between the primer layer and the intermediate layer, and the transition layer has a nano-composite phase structure of TiC and Ti3SiC2.

[0023] Preferably, the thickness of the transition layer is 350-1600 nm.

[0024] The application also protects the use of the fuel cell bipolar plate coating in the preparation of stainless steel or titanium alloy bipolar plates for fuel cells.

[0025] The fuel cell bipolar plate coating of the application has high hydrophobicity, high electrical conductivity and high corrosion resistance, and can meet the needs of fuel cell bipolar plates, and thus can be used in the preparation of fuel cell bipolar plates.

[0026] The application also protects a fuel cell bipolar plate comprising the fuel cell bipolar plate coating described above.

[0027] The application also protects a method for preparing a fuel cell bipolar plate, comprising the following steps:

[0028] S1. Pretreatment: cleaning the fuel cell bipolar plate substrate and glow etching;

[0029] S2. Depositing a primer layer: depositing a primer layer on the surface of the fuel cell bipolar plate substrate after S1 treatment under an argon atmosphere using an arc metal target as a sputtering source;

[0030] S3. Depositing an intermediate layer: depositing an intermediate layer on the surface of the primer layer under an argon or nitrogen atmosphere using an arc metal target as a sputtering source;

[0031] S4. Depositing an outer layer: depositing an outer layer on the surface of the intermediate layer under an argon atmosphere using a composite target as a sputtering source;

[0032] In S2 and S3, the arc metal target is one or more of Ti, Cr or Zr;

[0033] In S4, the composite target is Ti3SiC2, and the deposition temperature is 600-930℃.

[0034] The application uses a magnetron sputtering and arc evaporation composite deposition process to deposit a coating on a metal bipolar plate, and the preparation method is simple, the preparation cost is low, and it is easy to implement.

[0035] Moreover, the alternation of magnetron sputtering and arc evaporation is conducive to improving the deposition rate and reducing the pinhole defects existing in the growth of thin films by a single deposition technology.

[0036] Preferably, in S4, the current is 2-6 A.

[0037] The current has an influence on the deposition rate and compactness of the outer layer. If the current is too small, the growth rate of the outer layer will be slow. If the current is too large, the microstructure of the outer layer will be coarse and loose.

[0038] Preferably, in S4, the deposition time is 20-60 min.

[0039] The deposition time has an influence on the corrosion resistance and residual stress of the outer layer. If the deposition time is too small, the thickness of the outer layer will be small and the corrosion resistance will be insufficient. If the deposition time is too large, the thickness of the outer layer will be large, the cumulative residual stress will be large, the coating will be easy to peel off, and the substrate surface will be easy to stress concentrate and cause pitting.

[0040] The fuel cell bipolar plate substrate is any one of stainless steel or titanium alloy.

[0041] In practical applications, in S1, the cleaning can be ultrasonic cleaning with deionized water and anhydrous ethanol.

[0042] The glow etching can be as follows: the pretreated bipolar plate is loaded into the workpiece turret of a magnetic filtered ion sputtering coating machine, the chamber door is closed, vacuum is pumped and heated, argon gas is introduced, and the fuel cell bipolar plate substrate is glow etched at a bias voltage of -1000 to -600 V.

[0043] The S2 deposition of the primer layer can be as follows: the bias voltage is set to -200 to -50 V, the gas pressure is adjusted to 0.8 to 1.5 Pa, the arc metal target is used as the sputtering source, the target current is set to 60-100 A, and the deposition time is 3-10 min to deposit the primer layer.

[0044] After the S2 deposition of the primer layer, a transition layer can also be deposited, which can be as follows: the arc target power is turned off, the bias voltage is adjusted to -300 to -50 V, the gas pressure is 0.3 to 0.8 Pa, the power of the composite target is turned on, the current is set to 2 to 6 A, and the deposition time is 20 to 60 min to deposit the transition layer on the surface of the primer layer.

[0045] The function of the transition layer is to inhibit the contact of the corrosion solution with the substrate, reduce the defects in the coating, improve the contact with the primer layer and the intermediate layer, and thus improve the overall conductivity of the coating.

[0046] The S3 deposition of the intermediate layer can be as follows: the magnetron target power is turned off, the gas pressure is adjusted to 0.8 to 1.5 Pa, the bias voltage is set to -200 to -50 V, the arc metal target is turned on, the current is set to 60 to 100 A, and the deposition time is 3 to 15 min to deposit the intermediate layer on the surface of the transition layer.

[0047] In the S3 deposition of the intermediate layer, the gas can be argon or nitrogen.

[0048] The argon gas flow rate can be 100 to 300 sccm.

[0049] The nitrogen gas flow rate can be 100–400 sccm.

[0050] The S4 deposition of the outer layer can be performed as follows: turn off the power supply of the arc target, adjust the bias voltage to -300 to -50V, the gas pressure to 0.3 to 0.8Pa, turn on the power supply of the composite target, set the current to 2 to 6A, and the deposition time to 20 to 60 minutes, and deposit the outer layer on the surface of the intermediate layer.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] This invention discloses a bipolar plate coating for fuel cells. Through the synergistic effect of the outer layer, middle layer and bottom layer of a specific nanocomposite phase, the corrosion resistance and hydrophobicity of the bipolar plate coating for fuel cells are effectively improved, and the contact resistance of the interface is reduced.

[0053] The corrosion current of the fuel cell bipolar plate of the present invention is 0.05–1.1 μA·cm. -2 The contact resistance is 3.85–19.87 mΩ·cm. 2 It has a water contact angle of 91.5–104.6° and exhibits excellent corrosion resistance, electrical conductivity, and hydrophobicity. It meets the requirements of high electrical conductivity, corrosion resistance, and high hydrophobicity for fuel cells. Attached Figure Description

[0054] Figure 1 This is the XRD pattern of the magnetron sputtering target sample of the present invention.

[0055] Figure 2 This is a SEM image of the cross-section of the bipolar plate of the fuel cell in Embodiment 1 of the present invention.

[0056] Figure 3 This is a SEM image of the cross-section of the bipolar plate of the fuel cell in Embodiment 2 of the present invention.

[0057] Figure 4 This is a SEM image of the cross-section of the bipolar plate of the fuel cell in Embodiment 3 of the present invention.

[0058] Figure 5 This is a SEM image of the cross-section of the bipolar plate of the fuel cell in Embodiment 4 of the present invention.

[0059] Figure 6 This refers to the water contact angle of the fuel cell bipolar plate in Embodiment 1 of the present invention. Detailed Implementation

[0060] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0061] Example 1

[0062] As shown in Figure 2 A fuel cell bipolar plate comprising a fuel cell bipolar plate coating, the fuel cell bipolar plate coating comprising a base layer, an intermediate layer and an outer layer stacked in sequence, wherein the base layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nanocomposite phase structure of TiC and Ti3SiC2. The thickness of the outer layer is 600 nm. The intermediate layer is Cr, and the thickness is 256 nm. The base layer is Cr, and the thickness is 169 nm. A transition layer is further included between the base layer and the intermediate layer, the transition layer having a nanocomposite phase structure of TiC and Ti3SiC2, and the thickness of the transition layer is 435 nm.

[0063] The preparation method of the fuel cell bipolar plate is specifically as follows:

[0064] S1. Pretreatment: cleaning the fuel cell bipolar plate substrate and glow etching;

[0065] S2. Preparing the base layer: using an arc metal target as a sputtering source to deposit the base layer on the surface of the fuel cell bipolar plate substrate after S1 treatment in an argon atmosphere;

[0066] S3. Preparing the intermediate layer: using an arc metal target as a sputtering source to deposit the intermediate layer on the surface of the base layer in an argon atmosphere;

[0067] S4. Preparing the outer layer: using a composite target as a sputtering source to deposit the outer layer on the surface of the intermediate layer in an argon atmosphere;

[0068] In S2 and S3, the arc metal target is a Cr target;

[0069] In S4, the composite target is Ti3SiC2, and the deposition temperature is 800℃.

[0070] Between S2 and S3, a transition layer is further deposited on the surface of the base layer using a Ti3SiC2 composite target as a sputtering source in an argon atmosphere.

[0071] In the preparation method, the fuel cell bipolar plate substrate is 316L stainless steel.

[0072] The cleaning in S1 pretreatment is specifically: ultrasonic cleaning the fuel cell bipolar plate substrate in deionized water and anhydrous ethanol for 30 min respectively, and then blowing dry.

[0073] The S1 pre-treatment glow discharge etching is specifically as follows: the cleaned fuel cell bipolar plate substrate is loaded on a workpiece turntable of a magnetic filter ion sputtering film coating machine, the chamber door is closed, vacuumizing and heating are started, when the vacuum degree reaches 6*10-3 Pa and the temperature reaches 300 DEG C, argon gas with a flow rate of 300 sccm is introduced, the gas pressure is adjusted to 1.5 Pa, the workpiece turntable rotates at a speed of 50 r / min, and the substrate is subjected to glow discharge for 20 min under a bias voltage of-1000 V, then the gas pressure is adjusted to 0.8 Pa, the bias voltage is set to-600 V, the ion source is started, the ion source current is 4 A, the voltage is 500 V, and the ion source etching is performed for 10 min.

[0074] In S2, an arc Cr target is used as a sputtering source, the target current is set to 80 A, the bias voltage is set to-200 V, the gas pressure is adjusted to 1.0 Pa, and the deposition time is 5 min to obtain the primer layer.

[0075] The arc target power is turned off, the bias voltage is adjusted to-100 V, the gas pressure is 0.5 Pa, the power of the Ti3SiC2 composite target is turned on, the current is set to 2 A, and the deposition time is 30 min to obtain the transition layer.

[0076] In S3, the magnetron target power is turned off, the gas pressure is adjusted to 1.0 Pa, the bias voltage is-200 V, the arc Cr target is turned on, the current is set to 80 A, and the deposition time is 8 min to obtain the intermediate layer.

[0077] In S4, the arc target power is turned off, the bias voltage is adjusted to-100 V, the gas pressure is 0.5 Pa, the power of the composite target is turned on, the current is set to 2 A, and the deposition time is 30 min to obtain the metal bipolar plate.

[0078] Example 2

[0079] As shown in Figure 3 a fuel cell bipolar plate includes a fuel cell bipolar plate coating, the fuel cell bipolar plate coating includes a primer layer, an intermediate layer and an outer layer which are stacked in sequence, wherein the primer layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nano-composite phase structure of TiC and Ti3SiC2. The thickness of the outer layer is 602 nm. The intermediate layer is Zr, and the thickness is 191 nm. The primer layer is Zr, and the thickness is 157 nm. The primer layer and the intermediate layer further include a transition layer, the transition layer has a nano-composite phase structure of TiC and Ti3SiC2, and the thickness of the transition layer is 520 nm.

[0080] In the preparation method of the fuel cell bipolar plate, S1 is the same as in Example 1, and S2-S3 are different from those in Example 1.

[0081] In S2, an arc Zr target is used as a sputtering source, the target current is set to 80 A, the bias voltage is set to-200 V, the gas pressure is adjusted to 1.0 Pa, and the deposition time is 5 min to obtain the primer layer.

[0082] Turn off the power supply to the arc target, adjust the bias voltage to -100V and the gas pressure to 0.5Pa, turn on the power supply to the composite target, set the current to 2A, and the deposition time to 30min to obtain the transition layer.

[0083] In S3, turn off the magnetron target power supply, adjust the gas pressure to 1.0 Pa and the bias voltage to -200 V, turn on the arc Zr target, set the current to 80 A, and deposit for 8 min to obtain the intermediate layer.

[0084] Example 3

[0085] like Figure 4 As shown, a fuel cell bipolar plate includes a fuel cell bipolar plate coating. The fuel cell bipolar plate coating comprises a base layer, an intermediate layer, and an outer layer stacked sequentially. The base layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nanocomposite phase structure of TiC and Ti3SiC2. The outer layer has a thickness of 1489 nm. The intermediate layer is Ti with a thickness of 85 nm. The base layer is Ti with a thickness of 128 nm. A transition layer is also included between the base layer and the intermediate layer. The transition layer has a nanocomposite phase structure of TiC and Ti3SiC2 and a thickness of 1574 nm.

[0086] In the method for preparing the bipolar plate of the fuel cell, step S1 is the same as in Example 1, but steps S2 to S3 differ from those in Example 1:

[0087] In S2, an arc Ti target was used as the sputtering source, the target current was set to 80A, the bias voltage was set to -200V, the gas pressure was adjusted to 1.0Pa, and the deposition time was 3min to obtain the bottom layer.

[0088] Turn off the power supply to the arc target, adjust the bias voltage to -100V and the gas pressure to 0.5Pa, turn on the power supply to the composite target, set the current to 2A, and the deposition time to 30min to obtain the transition layer.

[0089] In S3, turn off the magnetron target power supply, adjust the gas pressure to 1.0 Pa and the bias voltage to -200 V, turn on the arc Ti target, set the current to 80 A, and deposit for 8 min to obtain the intermediate layer.

[0090] Example 4

[0091] like Figure 5As shown, a fuel cell bipolar plate includes a fuel cell bipolar plate coating, the fuel cell bipolar plate coating includes a base layer, an intermediate layer and an outer layer which are sequentially stacked, wherein the base layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nanocomposite phase structure of TiC and Ti3SiC2. The thickness of the outer layer is 424 nm. The intermediate layer is ZrN, and the thickness is 424 nm. The base layer is Zr, and the thickness is 211 nm. A transition layer is further included between the base layer and the intermediate layer, the transition layer has a nanocomposite phase structure of TiC and Ti3SiC2, and the thickness of the transition layer is 393 nm.

[0092] In the preparation method of the fuel cell bipolar plate, S1 is the same as that in Example 1, and S2-S4 are different from those in Example 1:

[0093] In S2, an arc Zr target is used as a sputtering source, the target current is set to 80 A, the bias voltage is set to -00 V, the gas pressure is adjusted to 1.0 Pa, and the deposition time is 3 min to obtain the base layer.

[0094] The arc target power is turned off, the bias voltage is adjusted to -100 V, the gas pressure is 0.5 Pa, the power of the composite target is turned on, the current is set to 2 A, and the deposition time is 30 min to obtain the transition layer.

[0095] In S3, the magnetron target power is turned off, the argon gas is turned off, the nitrogen gas is turned on at 400 sccm, the gas pressure is adjusted to 1.0 Pa, the bias voltage is -200 V, the arc Zr target is turned on, the current is set to 80 A, and the deposition time is 8 min to obtain the secondary outer layer.

[0096] In S4, the arc target power is turned off, the nitrogen gas is turned off, the argon gas is turned on at 300 sccm, the bias voltage is adjusted to -100 V, the gas pressure is 0.5 Pa, the power of the composite target is turned on, the current is set to 2 A, and the deposition time is 30 min.

[0097] Example 5

[0098] A fuel cell bipolar plate includes a fuel cell bipolar plate coating, the fuel cell bipolar plate coating includes a base layer, an intermediate layer and an outer layer which are sequentially stacked, wherein the base layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nanocomposite phase structure of TiC and Ti3SiC2. The thickness of the outer layer is 933 nm. The intermediate layer is TiN, and the thickness is 80 nm. The base layer is Ti, and the thickness is 200 nm. A transition layer is further included between the base layer and the intermediate layer, the transition layer has a nanocomposite phase structure of TiC and Ti3SiC2, and the thickness of the transition layer is 921 nm.

[0099] In the preparation method of the fuel cell bipolar plate, S1 is the same as that in Example 1, and S2-S4 are different from those in Example 1:

[0100] In S2, the arc Ti target is used as a sputtering source, the target current is set to 80 A, the bias voltage is set to -200 V, the gas pressure is adjusted to 1.0 Pa, and the deposition time is 3 min to obtain the base layer.

[0101] The arc target power is turned off, the bias voltage is adjusted to -100 V, the gas pressure is 0.5 Pa, the power of the composite target is turned on, the current is set to 2 A, and the deposition time is 30 min to obtain the transition layer.

[0102] In S3, the magnetron target power is turned off, the argon gas is turned off, the nitrogen gas is turned on at 400 sccm, the gas pressure is adjusted to 1.0 Pa, the bias voltage is -200 V, the arc Ti target is turned on, the current is set to 80 A, and the deposition time is 3 min to obtain the intermediate layer.

[0103] In S4, the arc target power is turned off, the nitrogen gas is turned off, the argon gas is turned on at 300 sccm, the bias voltage is adjusted to -100 V, the gas pressure is 0.5 Pa, the power of the composite target is turned on, the current is set to 2 A, and the deposition time is 30 min.

[0104] Example 6

[0105] A fuel cell bipolar plate includes a fuel cell bipolar plate coating, the fuel cell bipolar plate coating includes a base layer, an intermediate layer and an outer layer which are stacked in sequence, wherein the base layer is a metal, the intermediate layer is a metal and / or a metal nitride, and the outer layer has a nano-composite phase structure of TiC and Ti3SiC2. The thickness of the outer layer is 964 nm. The intermediate layer is TiN with a thickness of 153 nm. The base layer is Ti with a thickness of 200 nm. The base layer and the intermediate layer further include a transition layer, the transition layer has a nano-composite phase structure of TiC and Ti3SiC2, and the thickness of the transition layer is 915 nm.

[0106] In the preparation method of the fuel cell bipolar plate, S1 is the same as in Example 1, and S2-S4 are different from Example 1.

[0107] In S2, the arc Ti target is used as a sputtering source, the target current is set to 80 A, the bias voltage is set to -200 V, the gas pressure is adjusted to 1.0 Pa, and the deposition time is 3 min to obtain the base layer.

[0108] The arc target power is turned off, the bias voltage is adjusted to -100 V, the gas pressure is 0.5 Pa, the power of the composite target is turned on, the current is set to 2 A, and the deposition time is 30 min to obtain the transition layer.

[0109] In S3, the magnetron target power is turned off, the argon gas is turned off, the nitrogen gas is turned on at 400 sccm, the gas pressure is adjusted to 1.0 Pa, the bias voltage is -200 V, the arc Ti target is turned on, the current is set to 80 A, and the deposition time is 5 min to obtain the intermediate layer.

[0110] In S4, turn off the power supply to the arc target, turn off the nitrogen gas, introduce argon gas at 300 sccm, adjust the bias voltage to -100V and the gas pressure to 0.5Pa, turn on the power supply to the composite target, set the current to 2A and the deposition time to 30min.

[0111] Example 7

[0112] A fuel cell bipolar plate includes a fuel cell bipolar plate coating. The coating comprises a base layer, an intermediate layer, and an outer layer stacked sequentially. The base layer is metal, the intermediate layer is metal and / or metal nitride, and the outer layer has a nanocomposite phase structure of TiC and Ti3SiC2. The outer layer has a thickness of 961 nm. The intermediate layer is TiN with a thickness of 240 nm. The base layer is Ti with a thickness of 195 nm. A transition layer with a TiC and Ti3SiC2 nanocomposite phase structure and a thickness of 973 nm is also included between the base layer and the intermediate layer.

[0113] In the method for preparing the bipolar plate of the fuel cell, step S1 is the same as in Example 1, but steps S2 to S4 differ from those in Example 1:

[0114] In S2, an arc Ti target was used as the sputtering source, the target current was set to 80A, the bias voltage was set to -200V, the gas pressure was adjusted to 1.0Pa, and the deposition time was 3min to obtain the bottom layer.

[0115] Turn off the power supply to the arc target, adjust the bias voltage to -100V and the gas pressure to 0.5Pa, turn on the power supply to the composite target, set the current to 2A, and the deposition time to 30min to obtain the transition layer.

[0116] In S3, turn off the magnetron target power supply and argon gas, introduce nitrogen gas at 400 sccm, adjust the gas pressure to 1.0 Pa, the bias voltage to -200 V, turn on the arc Ti target, set the current to 80 A, and deposit for 8 min to obtain the intermediate layer.

[0117] In S4, turn off the power supply to the arc target, turn off the nitrogen gas, introduce argon gas at 300 sccm, adjust the bias voltage to -100V and the gas pressure to 0.5Pa, turn on the power supply to the composite target, set the current to 2A and the deposition time to 30min.

[0118] Example 8

[0119] A fuel cell bipolar plate, the preparation method of which differs from that in Example 1 is S4:

[0120] S4. The current is 6A.

[0121] Example 9

[0122] A fuel cell bipolar plate, the preparation method of which differs from that in Example 1 is S4:

[0123] S4. The current was 1 A.

[0124] Example 10

[0125] A fuel cell bipolar plate, the method of manufacture differing from Example 1 by S4:

[0126] S4. The deposition time was 20 min.

[0127] Example 11

[0128] A fuel cell bipolar plate, the method of manufacture differing from Example 1 by S4:

[0129] S4. The deposition time was 60 min.

[0130] Example 12

[0131] A fuel cell bipolar plate, the method of manufacture differing from Example 1 by S4:

[0132] S4. The bias was -50 V.

[0133] Example 13

[0134] A fuel cell bipolar plate, the method of manufacture differing from Example 1 by S4:

[0135] S4. The bias was -300 V.

[0136] Example 14

[0137] A fuel cell bipolar plate, the method of manufacture differing from Example 1 by S4:

[0138] S4. The gas pressure was 0.8 Pa.

[0139] Example 15

[0140] A fuel cell bipolar plate, the method of manufacture differing from Example 1 by S4:

[0141] S4. The gas pressure was 0.3 Pa.

[0142] Comparative Example 1

[0143] A fuel cell bipolar plate, differing from Example 1 by:

[0144] No coating was deposited on the surface.

[0145] Comparative Example 2

[0146] A fuel cell bipolar plate, differing from Example 1 by:

[0147] No intermediate layer was included.

[0148] The rest is the same as example 1, which will not be repeated here.

[0149] Comparative example 3

[0150] A fuel cell bipolar plate, which is different from example 1:

[0151] Not including the outer layer.

[0152] The rest is the same as example 1, which will not be repeated here.

[0153] Result detection

[0154] The fuel cell bipolar plates of the above examples and comparative examples are tested by the following performance test method:

[0155] Corrosion resistance of fuel cell bipolar plate: three-electrode system is used to test the potentiodynamic polarization curve, and Tafel linear extrapolation method is used to determine the corrosion current density. The corrosion current represents the corrosion resistance of the material, and the smaller the corrosion current density, the better the corrosion resistance.

[0156] Conductivity of fuel cell bipolar plate: the contact resistance of the bipolar plate is tested according to the voltammetry method, and the contact resistance between the bipolar plate and Toray carbon paper is measured under 1.4Mpa, so as to determine the contact resistance of the fuel cell bipolar plate. The smaller the contact resistance, the better the conductivity.

[0157] Hydrophobicity of fuel cell bipolar plate: JGW-360G type dynamic contact angle tester is used to measure the water contact angle of the fuel cell bipolar plate, and the larger the water contact angle, the better the hydrophobicity.

[0158] The specific test results are shown in Table 1 below:

[0159] Table 1

[0160] corrosion current (pA-cm -2 )]]> Contact resistance (mΩ-cm 2 )]]> Water contact angle (°) Example 1 0.75 3.85 104.6 Example 2 0.85 4.12 94.5 Example 3 0.71 8.81 91.5 Example 4 0.14 6.14 98.2 Example 5 1.1 7.86 94.7 Example 6 0.05 9.42 93.5 Example 7 0.88 19.87 94.1 Example 8 0.73 4.32 93.6 Example 9 0.86 5.62 94.1 Example 10 0.77 5.73 92.3 Example 11 0.73 6.29 93.1 Example 12 0.83 8.97 91.5 Example 13 0.77 6.19 93.7 Example 14 0.93 7.79 93.2 Example 15 0.91 5.16 92.3 Comparative Example 1 170 766 84.3 Comparative Example 2 8.0 7.96 92.5 Comparative Example 3 7.5 20.63 87.6

[0161] From the above data, the corrosion current is 0.05-1.1 μA·cm -2 , the contact resistance is 3.85-19.87 mΩ·cm 2 , the water contact angle is 91.5-104.6°, which has excellent corrosion resistance, conductivity and hydrophobicity. It can meet the requirements of high conductivity, corrosion resistance and high hydrophobicity of fuel cell.

[0162] In the fuel cell bipolar plate coating of example 1 of the present application, a composite target shown in Figure 1 is used to prepare a nanocomposite phase structure with TiC phase and Ti3SiC2 phase in the outer layer.

[0163] From Figure 2 , Figure 3 , Figure 4 andFigure 5 It can be seen that the fuel cell bipolar plate coating of the present application has a laminated structure of a primer layer, an intermediate layer and an outer layer, a compact structure, an obvious columnar structure in the outer layer, and a continuous, compact and defect-free interface.

[0164] As can be seen from Example 1 and Comparative Example 1, the surface of the bipolar plate is not coated, the corrosion current density is 1.7 x 10 -4 A·cm -2 , the contact resistance is 766 mΩ·cm 2 , and the water contact angle is 84.3°. The corrosion current density of Example 1 is 7.5 x 10 -7 A·cm -2 , the contact resistance is 3.85 mΩ·cm 2 , and the water contact angle is 104.6°. Compared with the surface of the bipolar plate not being coated, the corrosion current density and the contact resistance of Example 1 are reduced by about two orders of magnitude, which not only improves the corrosion resistance and the interface conductivity, but also improves the hydrophobicity.

[0165] As can be seen from Example 1 and Comparative Example 2, the corrosion current density of the coating without the intermediate layer is 8.0 x 10 - 6 A·cm -2 , the contact resistance is 7.96 mΩ·cm 2 , and the water contact angle is 92.5°. The corrosion current density of Example 1 is reduced by one order of magnitude compared with Comparative Example 2, which improves the corrosion resistance and maintains the original interface conductivity and hydrophobicity.

[0166] As can be seen from Example 1 and Comparative Example 3, the corrosion current density of the coating without the outer layer is 7.5 x 10 - 6 A·cm -2 , the contact resistance is 20.63 mΩ·cm 2 , and the water contact angle is 87.6°. The corrosion current density and the contact resistance of Example 1 are reduced by one order of magnitude, which improves the corrosion resistance and the interface conductivity, and also improves the hydrophobicity.

[0167] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. It is not necessary or possible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method of making a fuel cell bipolar plate, characterized by, The method comprises the following steps: S1. Pretreatment: cleaning the fuel cell bipolar plate substrate and glow discharge etching; S2. Depositing a primer layer: under an argon atmosphere, setting a bias voltage of -200 to -50 V, adjusting the gas pressure to 0.8 to 1.5 Pa, using an arc metal target as a sputtering source, setting a target current of 60 to 100 A, and depositing a primer layer on the surface of the fuel cell bipolar plate substrate treated in S1 for 3 to 10 min; turning off the arc target power supply, adjusting the bias voltage to -300 to -50 V, and adjusting the gas pressure to 0.3 to 0.8 Pa; turning on a Ti3SiC2 composite target as a sputtering source, setting the current to 2 to 6 A, and depositing a transition layer on the surface of the primer layer under an argon atmosphere for 20 to 60 min; S3. Depositing an intermediate layer: turning off the magnetron target power supply, adjusting the gas pressure to 0.8 to 1.5 Pa, and adjusting the bias voltage to -200 to -50 V; using an arc metal target as a sputtering source, setting the current to 60 to 100 A, and depositing an intermediate layer on the surface of the primer layer under an argon or nitrogen atmosphere for 3 to 15 min; S4. Depositing an outer layer: turning off the arc target power supply, adjusting the bias voltage to -300 to -50 V, and adjusting the gas pressure to 0.3 to 0.8 Pa; using a composite target as a sputtering source, setting the current to 2 to 6 A, and depositing an outer layer on the surface of the intermediate layer under an argon atmosphere for 20 to 60 min; In S2 and S3, the arc metal target is one or more of Cr or Zr; In S4, the composite target is Ti3SiC2, and the deposition temperature is 600 to 930°C; The primer layer is one or more of Cr or Zr, the transition layer has a nanocomposite phase structure of TiC and Ti3SiC2, the intermediate layer is one or more of Zr, Cr, CrN, or ZrN, and the outer layer has a nanocomposite phase structure of TiC and Ti3SiC2.

2. The method of making a fuel cell bipolar plate according to claim 1, wherein, The thickness of the outer layer is 0.1 to 3.0 µm.

3. The method for manufacturing a fuel cell bipolar plate according to claim 1, wherein The thickness of the intermediate layer is 50 to 500 nm.

4. The method for producing a fuel cell bipolar plate according to claim 3, wherein The thickness of the intermediate layer is 80 to 450 nm.

5. The method of making a fuel cell bipolar plate according to claim 1, wherein The thickness of the primer layer is 50 to 500 nm.

6. The method for producing a fuel cell bipolar plate according to claim 5, wherein The thickness of the primer layer is 100 to 250 nm.

7. The method of making a fuel cell bipolar plate according to claim 1, wherein The thickness of the transition layer is 350 to 1600 nm.

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