阅读说明：本技术 一种用于质子交换膜燃料电池的合金金属双极板及制备方法 (Alloy metal bipolar plate for proton exchange membrane fuel cell and preparation method thereof ) 是由 廖世军 文兆辉 于 2021-07-21 设计创作，主要内容包括：本发明公开了一种用于燃料电池的低成本合金金属双极板及制备方法,该金属双极板由导电性能良好的耐腐蚀合金材料经过成型、焊接及简单后处理而成,该合金极板无需专门制作导电耐腐蚀涂层,或者只需要简单的表面后处理,可大幅度降低金属极板的生产成本。该极板导电率高、耐腐蚀性能良好,可满足质子交换膜燃料电池对于金属极板的耐久性要求。(The invention discloses a low-cost alloy metal bipolar plate for a fuel cell and a preparation method thereof, the metal bipolar plate is formed by molding, welding and simple post-treatment of a corrosion-resistant alloy material with good conductivity, and the alloy bipolar plate does not need to be specially manufactured with a conductive corrosion-resistant coating or only needs simple surface post-treatment, so that the production cost of the metal bipolar plate can be greatly reduced. The polar plate has high conductivity and good corrosion resistance, and can meet the durability requirement of the proton exchange membrane fuel cell on the metal polar plate.)

1. An alloy metal bipolar plate for a proton exchange membrane fuel cell is characterized in that the metal bipolar plate is made of a corrosion-resistant alloy thin plate without specially manufacturing a conductive and corrosion-resistant coating and is manufactured through surface post-treatment, and the thickness of the alloy thin plate is 0.1-0.5 mm.

2. The alloy metal bipolar plate for a proton exchange membrane fuel cell as claimed in claim 1, wherein the alloy material is an alloy composed of a major component element and a minor component element; the main component element is more than one of titanium, tungsten and nickel; the secondary component elements comprise one or more of tungsten, molybdenum, zirconium, chromium, niobium, vanadium, iron, silicon and carbon.

3. The alloy metal bipolar plate for a proton exchange membrane fuel cell according to claim 2, wherein the mass content of the main component element is 60-95%, and the mass content of the sub-component element is 5-40%.

4. The alloy metal bipolar plate for a pem fuel cell of claim 1 wherein said post-treatment comprises one or more of cleaning, annealing, surface nitriding, and surface carburizing. And a conductive and corrosion-resistant coating is not required to be specially manufactured on the surface of the alloy polar plate.

5. The bipolar plate of claim 1, wherein the bipolar plate is formed by welding an anode side plate and a cathode side plate, wherein the anode side plate and the cathode side plate are both provided with flow field regions, the plate is provided with main fluid channels, and the anode plate and the cathode plate are combined to form a coolant flow field therebetween.

6. The method of making an alloy metal bipolar plate for a proton exchange membrane fuel cell as claimed in claim 1, comprising the steps of:

(1) cutting and punching a thin plate;

(2) punching and forming the flow field of the anode plate and the cathode plate;

(3) pre-cleaning;

(4) welding, namely after the anode plate and the cathode plate are combined and positioned, welding and combining the two pole plates by adopting technologies such as laser welding and the like, and automatically forming a cooling flow field between the two pole plates;

(5) the welding comprises the steps of carrying out spot welding on proper positions of the two polar plates, improving the binding force between the polar plates and keeping the shapes of the polar plates;

(6) post-processing the polar plate to obtain an alloy metal bipolar plate for the proton exchange membrane fuel cell; the post-processing comprises: sand blasting, grinding and polishing, chemical cleaning and surface treatment.

7. The method for preparing an alloy metal bipolar plate for a proton exchange membrane fuel cell according to claim 6, wherein in the step (1), the thin plate cutting method comprises laser cutting, wire cutting or punching; the punching refers to punching a gas channel hole and a fixing pin positioning hole of the pole plate by using a punching machine, and punching of the pole plate are synchronously completed.

In the step (2), the flow field punch forming technology means that the alloy sheet is placed in a die and is subjected to punch forming under the pressure of 2000-6000KN/cm 2.

8. The method for preparing the alloy metal bipolar plate for the proton exchange membrane fuel cell according to claim 6, wherein in the step (3), the pre-cleaning is to perform oil removal, scale removal and oxide removal treatment on the alloy sheet by using dilute sulfuric acid solution, acetone, ethanol and distilled water.

9. The method for preparing an alloy metal bipolar plate for a proton exchange membrane fuel cell according to claim 6, wherein in the step (4), the welding technology comprises laser welding or argon arc welding;

in the step (5), the spot welding technology refers to electrostatic spot welding technology.

10. The method for preparing an alloy metal bipolar plate for a proton exchange membrane fuel cell according to claim 6, wherein in the step (6), the post-treatment method is as follows: firstly, sand blasting, grinding and polishing, then washing with distilled water, then respectively placing the polar plate in 90% ethanol and acetone solution, ultrasonically cleaning for 1 hour, and then drying the polar plate;

the surface treatment comprises the following steps: heat sealing treatment in an inert atmosphere, heat treatment in a nitrogen or ammonia atmosphere, vacuum plasma surface nitriding sealing treatment, and vacuum plasma surface carbonizing sealing treatment.

Technical Field

The invention relates to the technical field of fuel cells, in particular to an alloy metal bipolar plate for a proton exchange membrane fuel cell and a preparation method thereof.

Background

The proton exchange membrane fuel cell is a device capable of directly, efficiently and environmentally converting chemical energy of fuel into electric energy, and has very important application prospects in the fields of traffic (automobiles, ships and the like), communication, military and the like. The use of the high-performance metal bipolar plate can greatly improve the volume power density and the mass power density of the fuel cell stack, so that the fuel cell has higher application value and application economy. The metal bipolar plate technology is one of the next generation fuel cell technologies which compete with each other and develop in various countries around the world.

As a bipolar plate, it is essential to have good electrical and thermal conductivity, and more importantly: the fuel cell operating environment is characterized by high temperature, high humidity, high oxygen concentration (cathode), and the bipolar plate must also have good chemical and electrochemical corrosion resistance.

The metal bipolar plate has the important advantages of thin volume, high mechanical strength, low gas permeability, good processability and the like, and can overcome the defects of large volume, large mass, low mechanical strength and the like of the traditional graphite bipolar plate. Therefore, the development of metallic bipolar plates is considered to be the most important way to improve the performance of fuel cells. The materials currently used as metal bipolar plates are mainly stainless steel and titanium metal plates, and because of their poor chemical and electrochemical corrosion resistance, it is generally necessary to build a corrosion-resistant coating on the surface of these materials to improve their electrical conductivity and corrosion resistance.

Chinese patent application CN 111342073A discloses a metal bipolar plate based on a pure titanium sheet and a preparation method thereof, wherein a corrosion-resistant coating consisting of titanium nitride and titanium carbide is constructed on the surface of the pure titanium plate by adopting a plasma technology, the thickness of the coating is 0.5-5 microns, and the conductivity of the plate is greatly improved after the coating is constructed. However, this invention does not provide data for durability testing of the plates, carbides or even nitrides often do not provide good durability due to oxidation; in addition, the technical means used by the invention needs to use expensive equipment, which can cause the problem of overhigh cost of the product;

the invention of Chinese patent application CN112909281A discloses a metal bipolar plate based on stainless steel sheet and its preparation method, in order to solve the corrosion-resistant problem of the stainless steel polar plate, the invention adopts magnetron sputtering technology to coat a transition layer containing tungsten, molybdenum, etc. on the stainless steel substrate first, then adopt magnetron sputtering technology to construct a layer of mixed nitride or carbide (MAX layer) of two or more transition metals on the transition layer, according to the application document, the conductivity of the polar plate is greatly improved, the corrosion current is obviously reduced; however, the invention also needs expensive magnetron sputtering equipment, and the carbon-nitrogen compound coating is the current mainstream technology, and the binding force and the durability are not ideal.

The construction of a corrosion-resistant coating on a metal plate is a very difficult task, expensive special equipment and raw materials are often required, and the preparation cost is usually high, so that the cost of the metal bipolar plate is high. More importantly, the corrosion-resistant coating often has the problems of poor conductivity, weak binding force, poor durability and the like; so that the fuel cell stack assembled by the metal bipolar plate has the problem of insufficient durability. Therefore, the development of a novel bipolar plate which has good chemical corrosion resistance and electrochemical corrosion resistance and does not need to specially construct a corrosion-resistant coating is of great significance for improving the volume power density of the fuel cell, reducing the cost of the fuel cell and improving the durability of the fuel cell. The development and application of fuel cell technology can be effectively promoted.

Disclosure of Invention

The present invention is directed to solving the above-mentioned problems of the prior art and is directed to providing an alloy metal bipolar plate for a fuel cell. The metal bipolar plate has the characteristics of good electric and thermal conductivity, chemical corrosion resistance and electrochemical corrosion resistance, greatly simplified preparation process, greatly reduced manufacturing cost and the like without specially manufacturing a corrosion-resistant conductive coating or simply post-processing.

In order to achieve the purpose, the invention adopts the technical scheme that:

the metal bipolar plate is made of an alloy thin plate, wherein the alloy thin plate is made of an alloy of titanium, tungsten, nickel and molybdenum, and the thickness of the alloy thin plate is 0.01-0.3 mm. In the case of simple post-treatment, the surface layer of the plate does not contain a corrosion-resistant coating, or contains a thin layer of nitride or carbide, which is left by the extremely thin (10-100 nm) post-treatment and is different from the specially constructed corrosion-resistant coating.

Further, the alloy material is an alloy composed of a main component element and a sub-component element; the main component element is more than one of titanium, tungsten and nickel; the secondary component elements comprise one or more of tungsten, molybdenum, zirconium, chromium, niobium, vanadium, iron, silicon and carbon, and other trace impurities.

Further, the mass content of the main component elements is 60-95%, and the mass content of the secondary component elements is 5-40%.

Further, the post-treatment comprises one or more of cleaning, annealing, surface nitriding and surface carburizing. And a conductive and corrosion-resistant coating is not required to be specially manufactured on the surface of the alloy polar plate.

Furthermore, the alloy metal bipolar plate is formed by welding an anode side plate and a cathode side plate, the anode side plate and the cathode side plate are both provided with flow field regions, the polar plates are provided with main fluid channels, and a cooling liquid flow field is formed in the middle after the anode polar plates and the cathode polar plates are combined.

The invention also provides a preparation method of the conductive corrosion-resistant titanium metal bipolar plate for the fuel cell, which comprises the following steps:

(1) cutting and punching a thin plate;

(2) punching and forming the anode plate and the cathode plate;

(3) pre-cleaning;

(4) welding, namely after the anode plate and the cathode plate are combined and positioned, welding and combining the two pole plates by adopting technologies such as laser welding and the like, and automatically forming a cooling flow field between the two pole plates;

(5) the welding comprises the steps of carrying out spot welding on proper positions of the two polar plates, improving the binding force between the polar plates and keeping the shapes of the polar plates;

(6) post-treatment of the plate, comprising: sand blasting, grinding and polishing, chemical cleaning, surface treatment and the like.

In the method, in the step (1), the sheet cutting method comprises laser cutting, wire cutting or punching; the punching refers to punching a gas channel hole and a fixing pin positioning hole of the pole plate by using a punching machine, and punching of the pole plate are synchronously completed.

In the step (2), the flow field punch forming technology means that the alloy sheet is placed in a die and is subjected to punch forming under the pressure of 2000-6000KN/cm 2.

In the above method, in the step (3), the pre-cleaning means performing oil removal, scale removal and oxide removal treatment on the alloy sheet by using a dilute sulfuric acid solution, acetone, ethanol and distilled water.

In the above method, in the step (4), the welding technique includes laser welding or argon arc welding.

In the above method, in the step (5), the spot welding technique is an electrostatic spot welding technique.

In the above method, in the step (6), the post-processing method is: firstly, sand blasting, grinding and polishing, then washing with distilled water, then respectively placing the polar plate in 90% ethanol and acetone solution, ultrasonically cleaning for 1 hour, and then drying the polar plate; the surface treatment mainly refers to the thermal (nitriding) treatment of the metal bipolar plate under nitrogen atmosphere (pure nitrogen or mixed gas of nitrogen and argon) or ammonia atmosphere (pure ammonia or mixed gas of ammonia and inert gas) at the temperature of 400-600 ℃, so that a compact nitride film is formed on the surface of the metal polar plate or no nitride film is generated.

Further, in the step (6), the surface treatment also comprises forming a thin layer of titanium carbide on the surface of the plate by using a chemical CVD method and a plasma carburizing method.

Compared with the prior art, the invention has the advantages that:

(1) the high-performance and high-durability fuel cell bipolar plate can be prepared by selecting high-conductivity and high-corrosion-resistance alloy materials and matching with a simple post-treatment technology, and a conductive corrosion-resistance coating does not need to be specially prepared on the surface of the bipolar plate. The preparation of the corrosion-resistant coating usually needs expensive special equipment and raw materials, so the invention can greatly reduce the equipment investment, simplify the preparation process and greatly reduce the cost of the metal bipolar plate.

(2) The existing bipolar plate containing the corrosion-resistant coating often has the problems of poor conductivity, weak bonding force with a substrate, poor durability and the like of the corrosion-resistant coating; so that the fuel cell stack assembled by the metal bipolar plate generally has the problem of insufficient durability. The metal bipolar plate manufactured by the invention does not have a specially manufactured corrosion-resistant coating, has good oxidation resistance and corrosion resistance, and perfectly solves the problems of the existing metal bipolar plate.

Drawings

FIG. 1 is a schematic structural diagram of an alloy metal bipolar plate for a proton exchange membrane fuel cell prepared by an example;

fig. 2 is a partially enlarged view of fig. 1.

The various components in the figure are as follows: the device comprises a surface sealing layer 1, a cathode side plate 2, an anode side plate 3, a welding seam 4, a fluid channel 5 and a flow field area 6.

Detailed Description

The following describes embodiments of the present invention in further detail through a description of examples. It is to be understood that the described embodiments are merely exemplary of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1, an alloy metal bipolar plate for a proton exchange membrane fuel cell does not need to be specially made with a special corrosion-resistant coating, and only needs to be subjected to simple surface treatment to obtain a bipolar plate without a special surface layer or with a self-generated thin nitride layer and a carbide layer. The bipolar plate substrate is made of a thin plate made of an alloy material with good corrosion resistance (chemical corrosion and electrochemical corrosion) and oxidation resistance, and the thickness of the thin plate is 0.1-0.33 mm. The surface treatment typically forms a surface layer having a thickness of 10 to 50 nm.

The preparation method comprises the following steps:

(1) a Ti-Mo alloy plate (containing Mo 32%) with the thickness of 0.1mm is punched into a size, a shape, an opening and the like by adopting a punching die, and then a required flow field is punched by adopting a flow field die; obtaining an anode sheet and a cathode sheet of the bipolar plate; the anode side plate and the cathode side plate are both provided with flow field regions, the polar plates are provided with main fluid channels, and a cooling liquid flow field is formed in the middle after the anode side plate and the cathode side plate are combined;

(2) after ultrasonic cleaning and drying, welding the anode sheet and the cathode sheet along the edge of the polar plate and the edge of the main channel by adopting a laser welding machine;

(3) adopting an electrostatic welder to complete the line welding of the drainage hidden channel and the reinforcing point welding of the main flow field area; the anode plate and the cathode side plate are firmly combined, and a uniformly distributed cooling liquid flow field is formed;

(4) pressurizing and carrying out heat treatment on the welded polar plate to finish the flattening and shape fixing work of the polar plate;

(5) the processed polar plate is firstly polished by a sand blasting machine, then polished, ultrasonically cleaned and dried, and then heated to 500 ℃ under a high-purity nitrogen atmosphere, and the temperature is kept for 30 minutes;

the obtained plate had a contact resistivity of 3.65 m.OMEGA.²(140N/cm²) The corrosion current density is 8.0 x 10^-4mA/cm²。

Example 2

The operation was the same as in example 1 except for the following changes.

(1) The Ti-Mo alloy plate of example 1 was replaced with a Ti-Pd alloy plate (containing Pd in an amount of 0.2 wt%) having a thickness of 0.2 mm;

(2) post-treating the electrode plate in ammonia-containing nitrogen atmosphere; the processing temperature was changed to 300 degrees celsius.

The contact resistivity of the prepared plate is 3.25m omega cm²(140N/cm²) The corrosion current density is 4.2 x 10^-4mA/cm²。

Example 3

The operation was the same as in example 1 except that a Ti-Nb (Nb content: 12 wt%) alloy sheet having a thickness of 0.1mm was used in place of the Ti-Mo alloy sheet of example 1.

The contact resistivity of the prepared polar plate is 3.65m omega cm²(140N/cm²) The corrosion current density is 6.6 x 10^-4mA/cm²。

Example 4

The operation was the same as in example 1 except that the Ti-Mo alloy sheet of example 1 was replaced with a W-Mo alloy sheet having a thickness of 0.1 mm.

The contact resistivity of the prepared plate is 3.47m omega cm²(140N/cm²) The corrosion current density is 9.6 x 10^-4mA/cm²。

Example 5

The operation was the same as in example 1 except that the Ti-Mo alloy sheet of example 1 was replaced with a Ni-Mo alloy sheet of 0.3mm thickness (Mo content 28 wt%, the sum of other impurity contents being less than 1 wt%).

The contact resistivity of the prepared plate is 5.21m omega cm²(140N/cm²) The corrosion current density is 6.77 x 10^-4mA/cm²。

Finally, it should be noted that the above preferred embodiments are only intended to illustrate the technical solution of the present invention and not to limit it, and it should be understood that various changes in form and details can be made by those skilled in the art without inventive efforts. In general, various changes in form and detail may be made by those skilled in the art without departing from the scope of the invention as defined by the appended claims.