A highly conductive, corrosion-resistant porous titanium diffusion layer, its preparation method and application

Abstract

This invention discloses a highly conductive and corrosion-resistant porous titanium diffusion layer, its preparation method, and its application, belonging to the field of reversible fuel cell technology. The preparation method of the highly conductive and corrosion-resistant porous titanium diffusion layer includes the following steps: S01: etching titanium fiber felt to obtain an etched porous titanium diffusion layer; S02: depositing noble metal particles to obtain a noble metal-deposited porous titanium diffusion layer; S03: performing in-situ oxide layer growth on the noble metal-deposited porous titanium diffusion layer to obtain an oxide-fixed noble metal particle porous titanium diffusion layer; S04: performing conductivity optimization treatment on the oxide-fixed noble metal porous titanium diffusion layer to obtain a highly conductive and corrosion-resistant porous titanium diffusion layer. The highly conductive and corrosion-resistant porous titanium diffusion layer prepared by this invention can reduce the contact resistance of the porous titanium diffusion layer, improve its conductivity by converting titanium oxide into a conductive material, and simultaneously increase the corrosion resistance of porous titanium. Its preparation process is simple.

Description

Technical Field

[0001] This invention belongs to the field of reversible fuel cell technology, and particularly relates to a highly conductive, corrosion-resistant porous titanium diffusion layer, its preparation method, and its application. Background Technology

[0002] In reversible fuel cells and water electrolysis, the diffusion layer typically functions as a mass transport and electron transport layer. The conductivity of the diffusion layer directly affects the performance of a single cell. In reversible fuel cells and water electrolysis, the anode diffusion layer is generally made of titanium felt, while the cathode is made of titanium felt or carbon felt. In the environment of reversible fuel cells and water electrolysis, pure titanium diffusion layers undergo corrosion and passivation, leading to a decrease in conductivity and a continuous increase in the cell's ohmic resistance. Surface modification of the titanium diffusion layer can improve the performance of the titanium felt.

[0003] Currently, most titanium felt coatings use micron-level precious metal coatings. Although precious metal coatings have excellent conductivity and stability, their large quantity leads to high costs. Non-precious metal coatings are cheaper but have shorter lifespans, poorer conductivity, and are prone to dissolving and peeling off in an electrolytic water environment. Summary of the Invention

[0004] This invention provides a highly conductive, corrosion-resistant porous titanium diffusion layer, its preparation method, and its application, aiming to solve the problems of cost and performance of titanium diffusion layer coatings. The porous titanium diffusion layer obtained by this invention can reduce the contact resistance of porous titanium diffusion layers, improve its conductivity by transforming titanium oxide into a conductive material, and increase the corrosion resistance of porous titanium; at the same time, it reduces the noble metal loading in the porous titanium coating, increases the coating adhesion through in-situ growth of the encapsulation structure, and the preparation process is simple.

[0005] The technical solution of this invention is implemented as follows:

[0006] A method for preparing a highly conductive and corrosion-resistant porous titanium diffusion layer includes the following steps:

[0007] S01: Etch the titanium fiber felt to obtain an etched porous titanium diffusion layer;

[0008] S02: Deposit noble metal particles into the etched porous titanium diffusion layer to obtain a porous titanium diffusion layer with noble metal deposition.

[0009] S03: In-situ oxide layer growth treatment is performed on the porous titanium diffusion layer deposited with noble metal to obtain a porous titanium diffusion layer with oxide fixed noble metal particles.

[0010] S04: Conductivity optimization treatment is performed on the porous titanium diffusion layer with oxide-fixed noble metal to obtain a highly conductive and corrosion-resistant porous titanium diffusion layer.

[0011] In step S01,

[0012] The etching includes at least one of acid etching, acid boiling, chemical polishing, or electrochemical polishing.

[0013] The acid etching method specifically involves using a mixed acid of 0.5%-1% HF and 4%-6% HNO3 by mass, with an etching time of 1-3 minutes.

[0014] The acid cooking process specifically involves using oxalic acid with a mass fraction of 0.1%-98% to cook at 75-85°C for 2-2.5 hours.

[0015] After the etching process in step S01, the surface roughness of the titanium fiber felt is improved and impurities on the surface of the titanium fiber are removed, resulting in an etched porous titanium diffusion layer.

[0016] In step S02,

[0017] The method of depositing the precious metal particles includes at least one of direct spraying, electrochemical deposition, or vapor deposition.

[0018] The specific method for direct spraying is as follows: noble metal powder with a particle size of 260-350 nm is dispersed and prepared into a slurry, which is then electrostatically sprayed onto the surface of acid-etched titanium fibers at a loading of 0.3-1.4 mg / cm³. 2 The content of precious metal powder in the slurry is 0.001%-10%; the solvent used in the slurry is an aqueous solvent or an oil-based solvent.

[0019] The precious metal powder is at least one of platinum black or iridium black.

[0020] In step S02, noble metal particles are deposited on the etched porous titanium diffusion layer, and the size of the noble metal particles is controlled to obtain a porous titanium diffusion layer with noble metal deposition.

[0021] In step S03,

[0022] The in-situ oxide layer growth process specifically involves a thermal oxidation temperature of 580-610℃, an oxygen partial pressure of 1-2 Pa, a time of 1-5 min, followed by natural cooling.

[0023] In step S03, the porous titanium diffusion layer deposited with noble metal is subjected to in-situ oxide layer growth treatment to fix the noble metal particles and obtain a porous titanium diffusion layer with oxide-fixed noble metal particles.

[0024] Furthermore, in step S03, the growth thickness of the film after coating can be further adjusted according to the loading.

[0025] In step S04,

[0026] The conductivity optimization treatment is preferably one of the following: titanium partial reduction treatment, magnesia reduction treatment, plasma injection treatment, microwave treatment, or vapor deposition reduction treatment.

[0027] The titanium partial reduction treatment specifically involves spraying titanium powder onto the surface of the porous diffusion layer deposited with noble metal, with a loading of 2.8-3.2 mg / cm³. 2 The vacuum is evacuated to 0.001-0.002 Pa, the temperature is 580-620℃, and the time is 1.5-2.5 min. Titanium oxide is partially reduced using titanium powder. Partial reduction is manifested in the fact that titanium powder can react with titanium dioxide under high vacuum to form conductive titanium oxide.

[0028] The magnesium thermal reduction treatment specifically involves placing a porous diffusion layer of noble metal deposition in magnesium powder, introducing nitrogen gas, maintaining high pressure, and treating at 680-720℃ for 1-2 hours; the high pressure range is 0.1MPa-0.2MPa.

[0029] In step S04, the porous titanium diffusion layer with oxide-fixed noble metal is subjected to conductivity optimization treatment, which transforms the titanium oxide into a conductive compound. While maintaining corrosion resistance, the conductivity of the diffusion layer is further improved, and finally a highly conductive and corrosion-resistant porous titanium diffusion layer is obtained.

[0030] The conductive compound includes at least one of conductive nitrides, conductive oxides, and conductive carbides.

[0031] A highly conductive and corrosion-resistant porous titanium diffusion layer is obtained by the above-described preparation method. Further, the highly conductive and passivation-resistant porous titanium diffusion layer comprises a titanium fiber felt, noble metal particles coated on the titanium fiber felt, a titanium oxide layer, and a titanium conductive compound mixture layer; the titanium conductive compound mixture layer coats the outer side of the titanium oxide layer.

[0032] The aforementioned highly conductive and corrosion-resistant porous titanium diffusion layer is used in reversible fuel cells.

[0033] The highly conductive and corrosion-resistant porous titanium diffusion layer obtained above can also be modified to be hydrophilic or hydrophobic to match different electrolyzers or reversible fuel cells.

[0034] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0035] 1. The highly conductive and corrosion-resistant porous titanium diffusion layer prepared by this invention can reduce the contact resistance of the porous titanium diffusion layer, improve its conductivity by transforming titanium oxide into a conductive material, and at the same time increase the corrosion resistance of porous titanium.

[0036] 2. The highly conductive and corrosion-resistant porous titanium diffusion layer prepared by this invention reduces the noble metal loading in the porous titanium coating and increases the coating adhesion through in-situ growth of the encapsulation structure.

[0037] 3. The preparation process of the highly conductive and corrosion-resistant porous titanium diffusion layer obtained by the present invention is simple.

[0038] 4. The highly conductive and corrosion-resistant porous titanium diffusion layer prepared by this invention has good conductivity, corrosion resistance and passivation resistance, which can improve the electrolysis performance of the electrolyzer and the overall performance of the reversible fuel cell. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the diffusion layer after noble metal deposition in Example 1; where 1 is titanium fiber felt and 2 is noble metal particles;

[0040] Figure 2 This is a schematic diagram of the diffusion layer after in-situ growth of titanium oxide in Example 1; where 1 is titanium fiber felt, 2 is noble metal particles, and 3 is titanium oxide layer;

[0041] Figure 3 This is a schematic diagram of the porous titanium diffusion layer with improved conductivity in Example 1; wherein, 1 is titanium fiber felt, 2 is noble metal particles, 4 is unreacted titanium oxide layer, and 5 is a conductive compound mixture layer of titanium. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0044] Currently, titanium diffusion layers in reversible fuel cells suffer from the following drawbacks: most use micron-sized noble metal coatings as titanium felt coatings. While noble metal coatings offer excellent conductivity and stability, their large quantity leads to high costs. Non-noble metal coatings, on the other hand, are inexpensive but have shorter lifespans, poorer conductivity, and are prone to dissolution and detachment in water electrolysis environments. To address these technical problems, this invention proposes a method for preparing a highly conductive, corrosion-resistant porous titanium diffusion layer.

[0045] Example 1

[0046] like Figures 1 to 3 As shown, a method for preparing a highly conductive and corrosion-resistant porous titanium diffusion layer includes the following steps:

[0047] S01: Acid etching treatment is performed on titanium fiber felt, wherein the acid etching concentration is 0.5% HF + 5% HNO3, and the acid etching time is 2 min; an acid-etched porous titanium diffusion layer is obtained.

[0048] S02: The acid-etched porous titanium diffusion layer from step S01 is subjected to noble metal particle deposition. A slurry is prepared by dispersing platinum black with a particle size of 300 nm, and then electrostatically sprayed onto the surface of the acid-etched porous titanium diffusion layer at a loading of 0.3 mg / cm³. 2 A porous titanium diffusion layer coated with noble metal was obtained;

[0049] S03: The porous titanium diffusion layer coated and deposited in step S02 is subjected to in-situ oxide layer growth treatment. The thermal oxidation temperature is 610℃, the time is 1min, the oxygen partial pressure is 1Pa, and it is naturally cooled to obtain a porous titanium diffusion layer with oxide fixed noble metal particles.

[0050] S04: The porous titanium diffusion layer with oxide-fixed noble metal particles from step S03 is subjected to conductivity optimization treatment to partially reduce titanium, achieving a conductive compound transformation. Titanium powder is then sprayed onto the surface of the porous titanium diffusion layer at a loading of 3 mg / cm³. 2 Titanium oxide was partially reduced using titanium powder, and the vacuum was drawn to 0.001 Pa. The temperature was 600℃ and the time was 2 min. After the process was completed, a highly conductive and corrosion-resistant porous titanium diffusion layer was obtained.

[0051] Furthermore, in step S01, the corrosion time and concentration can be determined based on the corrosion rate of the titanium material. Preferably, it is 0.5% HF + 5% HNO3, with an acid etching time of 2 minutes.

[0052] Furthermore, in step S02, the spraying method with the best dispersibility can be selected for spraying, preferably electrostatic spraying.

[0053] The platinum black content in the slurry in step S02 is 1%; the solvent used in the slurry is an aqueous solvent.

[0054] like Figure 1 As shown, the porous titanium diffusion layer of noble metal deposition obtained in step S02 of Example 1 includes titanium fiber felt 1 and noble metal particles 2 covering the titanium fiber felt 1.

[0055] like Figure 2 As shown, the porous titanium diffusion layer with oxide-fixed noble metal particles prepared in step S03 of Example 1 includes titanium fiber felt 1, noble metal particles 2 and titanium oxide layer 3 covering the titanium fiber felt 1, wherein the titanium oxide layer 3 covers the noble metal particles 2.

[0056] like Figure 3 As shown, the highly conductive and passivation-resistant porous titanium diffusion layer prepared in Example 1 includes a titanium fiber felt 1, noble metal particles 2 and a titanium oxide layer 4 coated on the titanium fiber felt 1, and a titanium conductive compound mixture layer 5; the titanium conductive compound mixture layer 5 covers the outside of the titanium oxide layer 4.

[0057] The resistivity of the highly conductive, corrosion-resistant porous titanium diffusion layer prepared in Example 1 is <150 mΩ·cm 2 Corrosion current density < 2 μA·cm -2 The cross-cut adhesion test shows a bonding strength rating of 5B, indicating excellent electrical conductivity, corrosion resistance, and coating adhesion. It can be used in reversible fuel cells.

[0058] Example 2

[0059] A method for preparing a highly conductive and corrosion-resistant porous titanium diffusion layer includes the following steps:

[0060] S01: Titanium fiber felt is acid-boiled at 80°C for 2 hours with 50% oxalic acid by mass to remove impurities and passivation film from the surface of titanium fiber felt, and an etched porous titanium diffusion layer is obtained.

[0061] S02: Deposit noble metal particles into the etched porous titanium diffusion layer from step S01 using 300nm iridium black coating at a loading of 1.4mg / cm³. 2 A porous titanium diffusion layer of noble metal deposition was obtained;

[0062] S03: The porous titanium diffusion layer with noble metal deposition obtained in step S02 is subjected to in-situ oxide layer growth treatment. The thermal oxidation conditions are 580℃ heat treatment for 1 min under an oxygen partial pressure of 1 Pa to obtain a porous titanium diffusion layer with oxide fixed noble metal particles.

[0063] S04: The porous titanium diffusion layer with oxide-fixed noble metal particles obtained in step S03 is subjected to conductivity optimization treatment so that the surface titanium oxide is converted into a titanium compound with good conductivity. The conductive titanium compound is prepared by magnesothermic reduction method. The porous titanium diffusion layer with oxide-fixed noble metal particles obtained in step S03 is placed in magnesium powder, nitrogen gas is introduced, and the pressure is maintained at 0.2 MPa. It is treated at 700℃ for 1 h to obtain a highly conductive and corrosion-resistant porous titanium diffusion layer.

[0064] The resistivity of the highly conductive and corrosion-resistant porous titanium diffusion layer prepared in Example 2 is <200 mΩ·cm. 2 Corrosion current density < 5 μA·cm -2 The cross-cut adhesion test shows a bonding strength rating of 5B, indicating excellent electrical conductivity, corrosion resistance, and coating adhesion. It can be used in reversible fuel cells.

[0065] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0066] 1. The highly conductive and corrosion-resistant porous titanium diffusion layer prepared by this invention can reduce the contact resistance of the porous titanium diffusion layer, improve its conductivity by transforming titanium oxide into a conductive material, and at the same time increase the corrosion resistance of porous titanium.

[0067] 2. The highly conductive and corrosion-resistant porous titanium diffusion layer prepared by this invention reduces the noble metal loading in the porous titanium coating and increases the coating adhesion through in-situ growth of the encapsulation structure.

[0068] 3. The preparation process of the highly conductive and corrosion-resistant porous titanium diffusion layer obtained by the present invention is simple.

[0069] 4. The highly conductive and corrosion-resistant porous titanium diffusion layer prepared by this invention has good conductivity, corrosion resistance and passivation resistance, which can improve the electrolysis performance of the electrolyzer and the overall performance of the reversible fuel cell.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a highly conductive, corrosion-resistant porous titanium diffusion layer, characterized in that: Includes the following steps: S01: Etch the titanium fiber felt to obtain an etched porous titanium diffusion layer; S02: Deposit noble metal particles into the etched porous titanium diffusion layer to obtain a porous titanium diffusion layer with noble metal deposition. S03: In-situ oxide layer growth treatment is performed on the porous titanium diffusion layer deposited with noble metal to obtain a porous titanium diffusion layer with oxide fixed noble metal particles. S04: The conductivity of the porous titanium diffusion layer with oxide-fixed noble metal particles is optimized to obtain a highly conductive and corrosion-resistant porous titanium diffusion layer. In step S04, the conductivity optimization treatment is one of titanium partial reduction treatment or magnesium thermal reduction treatment; The titanium partial reduction treatment specifically involves: spraying titanium powder onto the surface of a porous titanium diffusion layer with oxide-fixed noble metal particles, with a loading of 2.8-3.2 mg / cm2, evacuating to 0.001-0.002 Pa, maintaining a temperature of 580-620℃, and a time of 1.5-2.5 min, thereby partially reducing titanium oxide using the titanium powder. The magnesium thermal reduction treatment specifically involves placing a porous titanium diffusion layer with oxide-fixed noble metal particles in magnesium powder, introducing nitrogen gas, maintaining high pressure, and treating at 680-720℃ for 1-2 hours, wherein the high pressure ranges from 0.1MPa to 0.2MPa. In step S02, the noble metal particles are deposited by direct spraying with a loading of 0.3-1.4 mg / cm2.

2. The method for preparing a highly conductive, corrosion-resistant porous titanium diffusion layer according to claim 1, characterized in that: In step S01, the etching includes at least one of acid etching, acid boiling, chemical polishing, or electrochemical polishing.

3. The method for preparing a highly conductive, corrosion-resistant porous titanium diffusion layer according to claim 2, characterized in that: The acid etching method is as follows: a mixed acid of 0.5%-1% HF and 4%-6% HNO3 by mass fraction is used, and the acid etching time is 1-3 minutes. The acid cooking process specifically involves using oxalic acid with a mass fraction of 0.1%-98% to cook at 75-85℃ for 2-2.5 hours.

4. The method for preparing a highly conductive, corrosion-resistant porous titanium diffusion layer according to claim 2, characterized in that: The specific method of direct spraying is as follows: a slurry is prepared by dispersing noble metal powder with a particle size of 260-350nm, and then coated onto the surface of acid-etched titanium fiber felt using electrostatic spraying; the content of noble metal powder in the slurry is 0.001%-10%; the solvent used in the slurry is an aqueous solvent or an oil-based solvent; and the noble metal powder is at least one of platinum black or iridium black.

5. The method for preparing a highly conductive, corrosion-resistant porous titanium diffusion layer according to claim 1, characterized in that: In step S03, the in-situ oxide layer growth treatment specifically involves a thermal oxidation temperature of 580-610℃, an oxygen partial pressure of 1-2 Pa, a time of 1-5 min, followed by natural cooling.

6. A highly conductive, corrosion-resistant porous titanium diffusion layer is obtained by the preparation method described in any one of claims 1-5.

7. The highly conductive, corrosion-resistant porous titanium diffusion layer according to claim 6, characterized in that: It includes titanium fiber felt, and noble metal particles, titanium oxide layer, and titanium conductive compound mixture layer coated on the titanium fiber felt; the titanium conductive compound mixture layer covers the outside of the titanium oxide layer.

8. The highly conductive, corrosion-resistant porous titanium diffusion layer of claim 6 or 7 is used in a reversible fuel cell.

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