A method for preparing anode titanium-based porous transmission layer

Abstract

The present invention relates to a method for preparing an anode titanium-based porous transport layer, and belongs to the field of electrochemical technology. The method comprises the following steps: S1, laying titanium fiber felt by dry method; S2, pre-treating metal precursor powder by polyethylene glycol, cationic surfactant, coupling agent, polyvinyl alcohol, and polyaniline; S3, depositing the metal composite material onto the titanium fiber felt by chemical vapor deposition technology to obtain a titanium-based porous transport layer. The titanium-based conductive porous transport layer prepared by the present invention has the characteristics of more uniform surface, lower roughness, smaller interface contact resistance, better corrosion resistance, and longer service life. The technical solution of the present invention has simple steps and strong operability.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemistry and relates to a method for preparing an anode titanium-based porous transmission layer. Background Art

[0002] A proton exchange membrane (PEM) electrolyzer primarily consists of end plates, bipolar plates, a diffusion layer, a catalyst layer, a proton exchange membrane, and a gasket. The titanium-based porous transport layer at the anode plays a role in water transport, exhaust, heat conduction, and electrical conductivity during the oxygen evolution reaction at the anode, integrating the four-phase fluid fields of gas, liquid, electricity, and heat. When an electrolysis reaction occurs within a PEM electrolyzer, the anode is acidic, and the electrolysis voltage is typically higher than 1.6V. Therefore, in practical applications, titanium materials with good stability are typically selected: porous sintered titanium plates and titanium fiber felt. However, untreated titanium materials will gradually form a thin titanium dioxide film on their surface in an oxidizing environment, significantly reducing the electrode's electrical conductivity.

[0003] To solve the oxidation problem of titanium materials, electroplating, vapor deposition, magnetron sputtering and other methods are usually used to add oxidation-resistant precious metal coatings on the surface of titanium materials, such as ruthenium oxide, iridium oxide, etc. These precious metal oxides have high corrosion resistance and can protect titanium fiber felt from corrosion in acidic environments, thereby increasing its service life. At the same time, they have low electrical resistivity and high catalytic activity, which improves the efficiency of the catalyst in the catalytic layer, effectively reduces the load of the catalyst layer, and improves battery efficiency. Patent CN109518168A discloses a method for preparing an active titanium-based electrode plate with a high-stable coating. With titanium as the substrate, a multi-metal catalyst layer is formed by thermal decomposition, and a dense oxide titanium-based protective layer is formed by combining sol-gel method and electrochemical deposition method. Patent CN114990604A discloses a diffusion layer for PEM water electrolysis cell catalyst loading and its preparation method. A double-layer coating is prepared on the diffusion layer, including a metal diffusion layer substrate, a corrosion-resistant intermediate layer and a catalytic active layer. Patent CN115125558A discloses a method for preparing a metal-based conductive porous transport layer and its application in a water electrolysis cell. The metal-based conductive material powder is scraped onto the surface of a titanium felt to obtain a metal-based conductive porous transport layer.

[0004] However, the traditional pyrolysis method of forming a coating has weak bonding between the coating and the substrate, and acid corrosion and other treatments are performed before plating, which makes the process cumbersome. The electrochemical deposition method of plating the metal layer results in uneven coating and large roughness. The magnetron sputtering coating is on the surface of the substrate, while the precious metal oxide film deposited by chemical vapor deposition (CVD) technology can not only cover the surface of the substrate, but also be deposited in the pores of the substrate.

[0005] Therefore, it is necessary to develop a new method for preparing an anode titanium-based porous transport layer with simpler process, better corrosion resistance and stronger conductivity. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing an anode titanium-based porous transport layer. The prepared titanium-based porous transport layer has the characteristics of higher corrosion resistance, lower resistance, stronger conductivity, more uniform thickness, and longer service life of the titanium fiber felt.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A method for preparing an anode titanium-based porous transport layer, characterized in that the specific preparation steps of the anode titanium-based porous transport layer are as follows:

[0009] S1. Titanium fiber felt is prepared by dry laying. The specific steps of forming titanium fiber felt are as follows:

[0010] First, the fiber bundle is combed into a single fluffy fiber through air combing, and then the fiber bundle is laid into a net in a web laying machine. After being rolled by a roller press, it is placed in a vacuum sintering furnace for sintering at a temperature of 900-1500℃ and a vacuum degree of ≤3×10 -2 Pa; then perform multi-pass roller pressing and leveling for 2 to 3 times to obtain titanium fiber felt;

[0011] S2. Preparation of metal composite materials:

[0012] Fully dissolve the polyethylene glycol solid in anhydrous ethanol, add the coupling agent, and stir thoroughly in a stirrer for 0.5 to 1 hour. After stirring evenly, add the metal precursor powder and stir at a low speed of 100 to 150 r / min for 15 to 20 minutes; then stir at a high speed of 800 to 1200 r / min for 2 to 3 hours to obtain a metal slurry;

[0013] Polyvinyl alcohol, a cationic surfactant, and polyaniline are added to a metal slurry, and the mixture is fully stirred and then ultrasonically treated for 0.5 h, wherein the mass ratio of polyethylene glycol to anhydrous ethanol, metal precursor, cationic surfactant, coupling agent, polyvinyl alcohol, and polyaniline is 2:15-20:20-25:1-2:0.5-1:0.5-1:0.5-1, and the mixture is reacted by microwave method for 5-10 min. After filtering, the solid is dried in an oven at 100° C. for 2-4 h to obtain the metal composite material;

[0014] S3. Preparation of titanium-based anode gas transport layer:

[0015] The titanium fiber felt is rinsed with anhydrous ethanol and deionized water, dried in an oven and placed in a chemical vapor deposition furnace. Carrier hydrogen is introduced for preheating at a temperature of 200-500°C and kept warm for 10-50 minutes. The prepared metal composite material is then vaporized and introduced into a deposition box. Carrier carbon dioxide and hydrogen are introduced at the same time to form an oxide metal coating on the surface of the titanium fiber felt substrate. The coating thickness is 1-30 μm. After cooling, a titanium-based anode gas transport layer is obtained.

[0016] As a preferred technical solution of the present invention, in step S1, the titanium fiber has a diameter of 10 to 30 μm and a length of 30 to 80 mm.

[0017] As a preferred technical solution of the present invention, in step S1, the titanium fiber felt has a thickness of 0.1 to 1.0 mm and a porosity of 50 to 90%, wherein the single-layer felt has a gram weight of 50 to 600 g / m 2 ,During the rolling process, single layer or multi-layer felt is selected for rolling forming.

[0018] As a preferred technical solution of the present invention, in step S2, the cationic surfactant is one of guar gum, dodecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and a cationic antistatic agent.

[0019] As a preferred technical solution of the present invention, in step S2, the average molecular weight of the polyethylene glycol is 800-1200.

[0020] As a preferred technical solution of the present invention, in step S2, the coupling agent is one of a silane coupling agent, a phthalate coupling agent, a borate coupling agent, and an aluminate coupling agent.

[0021] As a preferred technical solution of the present invention, in step S2, the metal precursor is one or more halides or metal organic compounds of iridium, ruthenium, platinum, palladium, osmium, and rhodium; the chemical vapor deposition coating can be plated multiple times with different metal precursors.

[0022] As a preferred technical solution of the present invention, in step S3, the flow rate of the hydrogen used for preheating is 300-700 mL / min.

[0023] As a preferred technical solution of the present invention, in step S3, the flow rates of the hydrogen and carbon dioxide introduced simultaneously are 300-700 mL / min and 100-400 mL / min, respectively; the pressure of chemical vapor deposition is 800-1200 Pa, and the temperature is 300-800°C.

[0024] Beneficial effects of the present invention:

[0025] (1) By adding conductive polyaniline to the metal precursor to increase the conductivity of the titanium-based porous transport layer, an effective charge conduction channel is created between the titanium fiber felt and the metal oxide coating, while suppressing titanium passivation caused by the unfavorable charge conduction between the titanium fiber felt and the traditional metal oxide layer due to the lack of conductive substances; at the same time, the addition of cationic surfactants allows the metal organic ions to be better dispersed in the organic solvent and increases the number of charges therein, further increasing the charge transfer between the titanium fiber felt and the surface coating. The addition of a coupling agent allows the components to exist stably, while improving the adhesion between the coating and the titanium fiber felt.

[0026] (2) The porous titanium felt is prepared by the titanium fiber airflow felt forming technology, and then a layer of precious metal film is deposited on the surface of the titanium fiber by chemical vapor deposition technology to improve the corrosion resistance and oxidation resistance of the titanium fiber felt. At the same time, a mixture of carbon dioxide and hydrogen is introduced to prevent the titanium fiber felt from being oxidized, reduce the risk of the oxidized metal coating falling off, and ensure that the titanium fiber felt has high conductivity and a high number of active sites, thereby improving the catalytic efficiency. In addition, the dry method used to lay the titanium fiber felt saves water resources and reduces the acid pretreatment process in the traditional preparation of the titanium-based diffusion layer, simplifies the process steps, and reduces environmental pollution. Moreover, the precious metal oxide film prepared by chemical vapor deposition technology has the properties of high dispersion, high coverage, high purity, low resistance, and uniform particle size and strong bonding with the substrate. It improves the unevenness of the platinum coating of the anode titanium-based diffusion layer in the traditional PEM electrolytic cell, expands the active sites, and the catalytic coating can catalyze the electrode reaction, reducing the amount of catalyst in the catalytic layer. The dense precious metal oxide films such as iridium oxide or ruthenium oxide formed by chemical vapor deposition are more corrosion-resistant and can enhance the life of titanium fiber felt. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0028] Figure 1 Polarization curves of the electrolytic cells assembled with the anode gas transport layers prepared in Examples and Comparative Examples. DETAILED DESCRIPTION

[0029] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0030] Example 1

[0031] Titanium fiber felt is prepared by dry laying. The specific steps of forming titanium fiber felt are as follows:

[0032] Titanium fibers with a diameter of 15 μm and a length of 50 mm were used. After being air-combed, they were formed in a web laying machine, pressed and reinforced by a roller press, and then sintered in a vacuum sintering furnace at a temperature of 1200 ° C and a vacuum degree of 2 × 10 -2 Pa; then the titanium fiber felt was rolled and leveled to obtain a thickness of 0.23 mm and a porosity of 85%;

[0033] Preparation of metal composite materials:

[0034] Dissolve 2g of polyethylene glycol solid in 20g of anhydrous ethanol, add 1g of coupling agent, stir thoroughly in a stirrer for 0.5-1h, stir evenly, add 20g of metal organic precursor iridium hexafluoride (IrF6) powder, stir at low speed for 20min, the speed is 150r / min; then stir at high speed for 3h, the speed is 1200r / min, to obtain metal slurry;

[0035] 1 g of polyvinyl alcohol, 1 g of cationic surfactant, and 1 g of polyaniline were added to the metal slurry, and the mixture was thoroughly stirred and then ultrasonically treated for 0.5 h. The mixture was reacted by microwave method for 10 min, filtered, and dried in an oven at 100° C. for 3 h to obtain the treated IrF6 precursor.

[0036] Preparation of titanium-based anode gas transport layer:

[0037] The titanium fiber felt was rinsed with anhydrous ethanol and deionized water, dried and placed in a chemical vapor deposition furnace, and preheated with carrier gas H2 at a hydrogen flow rate of 400 mL / min. The mixture was kept at 400°C for 30 minutes. The treated IrF6 was then vaporized and introduced into a deposition box. At the same time, carrier gases carbon dioxide and hydrogen were introduced. The hydrogen flow rate was 400 mL / min, the carbon dioxide flow rate was 300 mL / min, the deposition box pressure was 700 Pa, and the temperature was 700°C. A metal oxide coating was formed on the surface of the titanium fiber felt substrate with a coating thickness of 20 μm, obtaining a titanium-based anode gas transport layer IrO2@titanium fiber felt. The final IrO2@titanium fiber felt was 0.25 mm.

[0038] Example 2

[0039] Titanium fiber felt is prepared by dry laying. The specific steps of forming titanium fiber felt are as follows:

[0040] Titanium fibers with a diameter of 20 μm and a length of 50 mm were used. After being air-combed, they were formed in a web laying machine, pressed and reinforced by a roller press, and then sintered in a vacuum sintering furnace at a temperature of 1300 ° C and a vacuum degree of 2×10 -2 Pa; then the titanium fiber felt was rolled and leveled to obtain a thickness of 0.23 mm and a porosity of 85%;

[0041] Preparation of metal composite materials:

[0042] Dissolve 2g of polyethylene glycol solid in 20g of anhydrous ethanol, add 1g of coupling agent, stir thoroughly in a stirrer for 0.5-1h, stir evenly, add 20g of metal organic precursor ruthenium hexafluoride (RuF6) powder, stir at low speed for 20min, the speed is 150r / min; then stir at high speed for 3h, the speed is 1200r / min, to obtain metal slurry;

[0043] 1 g of polyvinyl alcohol, 1 g of cationic surfactant, and 1 g of polyaniline were added to the metal slurry, and the mixture was thoroughly stirred and then ultrasonically treated for 0.5 h. The mixture was reacted by microwave method for 10 min, filtered, and dried in an oven at 100° C. for 3 h to obtain the treated RuF6 precursor.

[0044] Preparation of titanium-based anode gas transport layer:

[0045] The titanium fiber felt was rinsed with anhydrous ethanol and deionized water, dried and placed in a chemical vapor deposition furnace, and preheated with hydrogen carrier gas at a hydrogen flow rate of 400 mL / min. The temperature was kept at 400°C for 30 minutes. The treated RuF6 was then vaporized and introduced into a deposition box. At the same time, carrier gas carbon dioxide and hydrogen were introduced. The hydrogen flow rate was 400 mL / min, the carbon dioxide flow rate was 300 mL / min, the deposition box pressure was 700 Pa, and the temperature was 750°C. A metal oxide coating was formed on the surface of the titanium fiber felt substrate with a coating thickness of 20 μm, obtaining a titanium-based anode gas transport layer RuO2@titanium fiber felt. The final RuO2@titanium fiber felt was 0.25 mm.

[0046] Example 3

[0047] Titanium fiber felt is prepared by dry laying. The specific steps of forming titanium fiber felt are as follows:

[0048] Titanium fibers with a diameter of 20 μm and a length of 50 mm were used. After being air-combed, they were formed in a web laying machine, pressed and reinforced by a roller press, and then sintered in a vacuum sintering furnace at a temperature of 1200 ° C and a vacuum degree of 2 × 10 -2 Pa; then the titanium fiber felt is rolled and leveled to obtain a thickness of 0.37 mm and a porosity of 80%;

[0049] Preparation of metal composite materials:

[0050] Dissolve 2g of polyethylene glycol solid in 20g of anhydrous ethanol, add 1g of coupling agent, stir thoroughly in a stirrer for 0.5-1h, stir evenly, add 20g of metal organic precursor iridium hexafluoride (IrF6) powder, stir at low speed for 20min, the speed is 150r / min; then stir at high speed for 3h, the speed is 1200r / min, to obtain metal slurry;

[0051] 1 g of polyvinyl alcohol, 1 g of cationic surfactant, and 1 g of polyaniline were added to the metal slurry, and the mixture was thoroughly stirred and then ultrasonically treated for 0.5 h. The mixture was reacted by microwave method for 10 min, filtered, and dried in an oven at 100° C. for 3 h to obtain the treated IrF6 precursor.

[0052] Preparation of titanium-based anode gas transport layer:

[0053] The titanium fiber felt was rinsed with anhydrous ethanol and deionized water, dried and placed in a chemical vapor deposition furnace, and preheated with carrier gas H2 at a flow rate of 400 mL / min and a temperature of 200-500°C for 10-50 minutes. The treated IrF6 was then vaporized and introduced into a deposition box, and carrier gases carbon dioxide and hydrogen were introduced at the same time. The hydrogen flow rate was 400 mL / min, the carbon dioxide flow rate was 300 mL / min, the deposition box pressure was 700 Pa, and the temperature was 600°C. An iridium oxide coating was formed on the surface of the titanium fiber felt substrate with a coating thickness of 30 μm, obtaining a titanium-based anode gas transport layer IrO2@titanium fiber felt. The final IrO2@titanium fiber felt was 0.40 mm.

[0054] Comparative Example 1

[0055] Titanium fibers with a diameter of 20 μm and a length of 50 mm are used. After being air-combed, they are formed in a web laying machine, pressed and reinforced by a roller press, and then sintered in a vacuum sintering furnace at a sintering temperature of 1200 ° C and a vacuum degree of 2×10 -2 Pa; then roller pressing and leveling were performed to make the titanium fiber felt 0.37 mm thick and 80% porosity;

[0056] The titanium fiber felt was first cleaned with a methanol solution, then immersed in a 15% oxalic acid solution for 20 minutes, and then repeatedly rinsed with deionized water until the surface of the titanium fiber felt was neutral, and finally dried to obtain a titanium fiber felt matrix to be deposited;

[0057] Prepare conductive metal slurry: dissolve 2g of phenolic resin and 1g of dispersant in 30g of isopropyl alcohol, add 35g of iridium powder, stir and disperse evenly to obtain conductive metal slurry containing iridium powder;

[0058] The iridium powder-containing slurry was scraped onto the pretreated titanium fiber felt, and then dried in an oven at a temperature of 120° C. for 1 hour to obtain an iridium-coated titanium fiber felt.

[0059] according to Figure 1 It can be concluded that the polarization curve of Example 1 has the flattest trend and the lowest slope, and the higher the maximum current density, the better the power performance of this battery. The polarization curve of Comparative Example 1 has the highest slope, indicating that the porous transport layer prepared by the present invention has good performance when used in a proton exchange membrane fuel cell.

[0060] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing an anode titanium-based porous transport layer, characterized by: The specific preparation steps of the anode titanium-based porous transport layer are as follows: S1. Titanium fiber felt is prepared by dry laying. The specific steps of forming titanium fiber felt are as follows: First, the fiber bundle is combed into a single fluffy fiber through air combing, and then the fiber bundle is laid into a net in a web laying machine. After being rolled by a roller press, it is placed in a vacuum sintering furnace for sintering at a temperature of 900-1500℃ and a vacuum degree of ≤3×10 -2 Pa; then perform multi-pass roller pressing and leveling for 2 to 3 times to obtain titanium fiber felt; S2. Preparation of metal composite materials: Fully dissolve the polyethylene glycol solid in anhydrous ethanol, add the coupling agent, and stir thoroughly in a stirrer for 0.5 to 1 hour. After stirring evenly, add the metal precursor powder and stir at a low speed of 100 to 150 r / min for 15 to 20 minutes; then stir at a high speed of 800 to 1200 r / min for 2 to 3 hours to obtain a metal slurry; Polyvinyl alcohol, a cationic surfactant, and polyaniline are added to a metal slurry, and the mixture is fully stirred and then ultrasonically treated for 0.5 h, wherein the mass ratio of polyethylene glycol to anhydrous ethanol, metal precursor, cationic surfactant, coupling agent, polyvinyl alcohol, and polyaniline is 2:15-20:20-25:1-2:0.5-1:0.5-1:0.5-1, and the mixture is reacted by microwave method for 5-10 min. After filtering, the solid is dried in an oven at 100° C. for 2-4 h to obtain the metal composite material; S3. Preparation of titanium-based anode gas transport layer: The titanium fiber felt is rinsed with anhydrous ethanol and deionized water, dried in an oven and placed in a chemical vapor deposition furnace. Carrier hydrogen is introduced for preheating at a temperature of 200-500°C and kept warm for 10-50 minutes. The prepared metal composite material is then vaporized and introduced into a deposition box. Carrier carbon dioxide and hydrogen are introduced at the same time to form an oxide metal coating on the surface of the titanium fiber felt substrate. The coating thickness is 1-30 μm. After cooling, a titanium-based anode gas transport layer is obtained.

2. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S1, the titanium fiber has a diameter of 10 to 30 μm and a length of 30 to 80 mm.

3. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S1, the titanium fiber felt has a thickness of 0.1-1.0 mm and a porosity of 50-90%, wherein a single layer of felt has a gram weight of 50-600 g / m2, and a single layer or multiple layers of felt are selected for rolling forming during the rolling process.

4. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S2, the cationic surfactant is one of guar gum, dodecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and a cationic antistatic agent.

5. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S2, the average molecular weight of the polyethylene glycol is 800-1200.

6. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S2, the coupling agent is one of a silane coupling agent, a phthalate coupling agent, a borate coupling agent, and an aluminate coupling agent.

7. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S2, the metal precursor is one or more halides or metal organic compounds of iridium, ruthenium, platinum, palladium, osmium, and rhodium; in step S3, when different metal precursors are used, the chemical vapor deposition coating undergoes one or more plating processes.

8. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S3, the flow rate of the carrier gas hydrogen is 300-700 mL / min.

9. The method for preparing an anode titanium-based porous transport layer according to claim 1, characterized in that: In step S3, the flow rates of the hydrogen and carbon dioxide introduced simultaneously are 300-700 mL / min and 100-400 mL / min, respectively; the pressure of the chemical vapor deposition is 800-1200 Pa, and the temperature is 300-800° C.

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