Preparation method of metal-based carbon nanotube-doped composite conductive paste

Abstract

The invention discloses a preparation method of composite conductive paste of a metal-based doped carbon nano tube, and belongs to the field of conductive material preparation.Silver-coated metal powder is synthesized in an over-chemical plating mode, generation of free silver is effectively reduced by precisely regulating and controlling the proportion of a silver-ammonia solution to a complex, and then waste of silver is reduced; and compared with a physical deposition mode, the time is saved, and the cost is reduced while the performance is ensured by reducing the consumption of silver. Besides, the dispersing agent is added into the carbon nano tube in an ultrasonic and ball-milling physical mode, the carbon paste is formed through dispersion treatment, then the carbon paste and the conductive agent formed by silver-coated copper are subjected to ultrasonic and ball-milling mixing, a liquid-phase carbon network is formed, and the highly-dispersed and highly-mixed composite paste is constructed. Compared with the existing method for forming the carbon paste by modifying the carbon nanotubes, the method disclosed by the invention has the advantages that the problem of dispersity caused by agglomeration of the carbon nanotubes is solved, steps are greatly reduced, and the carbon tube modification cost is saved.

Description

Technical Field

[0001] The present invention relates to the field of conductive material preparation, and in particular to a method for preparing a metal-based doped carbon nanotube composite conductive slurry. Background Art

[0002] Traditional conductive pastes made from pure copper and pure silver, while having good electrical conductivity, exhibit insufficient mechanical strength, are susceptible to oxidation, and are prohibitively expensive in certain applications, resulting in reduced conductivity and other limitations. However, these limitations in pure conductor performance have prompted researchers to seek improvements. For example, prior art patent application number CN02824162.2 discloses a copper alloy powder for conductive paste, characterized by comprising 80-99.9% by mass of Cu and 0.1-20% by mass of one or two elements selected from Ta and W, and having an average particle size of 0.1-1 μm. This copper alloy powder has a higher sintering starting temperature than copper powder, improving its oxidation resistance and heat resistance. Another example is patent application number CN201710283245.3, which discloses a copper conductive paste comprising the following raw material components and percentages by mass: 65-90% by mass of micronized copper powder coated with a nano-copper powder layer; 0.1-5% by mass of a dispersant; and 9-34% by mass of a solvent. This invention uses micron copper powder as the main conductive filler, which is cheap, has a high bulk density, and high electron conduction efficiency; the surface of the micron copper powder is coated with a layer of nano-copper, which is evenly dispersed and easy to sinter; it is directly photo-sintered after screen printing, which is a simple process and suitable for large-scale production; the circuit resistance after sintering is low and the bending resistance is high; by adding a stabilizer to the system, copper oxide is reduced during the sintering process, thereby reducing the copper oxide content in the copper wire and obtaining a conductive circuit with a low copper oxide content.

[0003] Prior art also involves coating copper or nickel powder with silver. This coating not only improves the electrical properties of the conductor itself but also enhances its oxidation resistance. Furthermore, the introduction of carbon nanotubes further enhances its electrical properties and stability. However, during the preparation of conductive pastes containing silver-coated copper or nickel powder doped with carbon nanotubes, silver often precipitates in a free state, resulting in uneven silver coating. Carbon nanotubes can also agglomerate during dispersion, leading to uneven dispersion of the silver-coated copper or nickel powder and the carbon nanotubes, compromising conductivity and paste uniformity. Summary of the Invention

[0004] Based on this, in order to solve one of the above problems, the present invention provides a method for preparing a metal-based doped carbon nanotube composite conductive paste, the specific technical solution is as follows:

[0005] A method for preparing a metal-based composite conductive paste doped with carbon nanotubes, the method comprising the following steps:

[0006] Step 1. Pre-treating the metal powder: The metal powder is dispersed in polyvinyl pyrrolidone, and then subjected to surface modification with sodium hydroxide solution and dilute sulfuric acid in sequence, followed by washing and drying to obtain pre-treated metal powder;

[0007] Step 2. The pretreated metal powder, complexing agent, and dispersant A are thoroughly mixed, and then the pre-prepared silver ammonia solution is added. The pH is adjusted with an ammonia solution, and ultrasonic stirring is performed to mix the mixture evenly. A reducing agent is then added, and the mixture is washed and dried to obtain a conductive agent.

[0008] Step 3. The carbon nanotubes, dispersant B and solvent are mixed, and subjected to ultrasonication and ball milling to prepare a carbon precursor;

[0009] Step 4. The conductive agent obtained in step 2 is fully mixed with the carbon precursor, dispersant C and coupling agent in step 3 to obtain a conductive agent precursor for preparing a conductive paste;

[0010] Step 5. Fully mix the conductive agent precursor and the binder into a slurry state to obtain a composite conductive slurry.

[0011] Furthermore, in step 1, the metal powder is copper powder, and the copper powder is flaky copper powder with a size of 1-5 μm.

[0012] Furthermore, in step 1, the weight ratio of metal powder, polyvinyl pyrrolidone, sodium hydroxide and dilute sulfuric acid is (3-7): (2-7): (45-55): (5-10).

[0013] Furthermore, in step 2, the complexing agent accounts for 2%-15% of the mass of the conductive agent, the dispersant A accounts for 2.5%-5% of the mass of the conductive agent, and the reducing agent accounts for 0.5%-2.5% of the mass of the conductive agent.

[0014] Furthermore, in step 3, by mass percentage, the carbon nanotubes are 5%-20%, the dispersant B is 2.5%-5%, and the solvent is 60%-85%.

[0015] Furthermore, in step 3, the carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, or a mixture thereof.

[0016] Furthermore, in step 3, the dispersant B is at least one of polypropylene, polyether ester polymer and polymethylbutylene.

[0017] Furthermore, in step 4, the dispersant C is PVP with a molecular weight between 10,000 and 40,000, and the coupling agent is silane coupling agent KH550.

[0018] Furthermore, in step 4, by mass proportion: conductive agent 80%-92%, carbon precursor 1%-5%, dispersant C 2.5%-5%, coupling agent 2%-5%.

[0019] Furthermore, in step 5, the binder is at least one of polypropylene glycol, phenolic ester resin, o-phenylsilane resin, and phenolic resin.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention synthesizes silver-coated metal powder by chemical plating. By precisely controlling the ratio of silver ammonia solution to the complex, the generation of free silver is minimized, thereby minimizing silver waste. Compared with the existing physical deposition method, the present invention not only saves time but also reduces the amount of silver used, thereby ensuring performance while reducing costs.

[0022] 2. This invention utilizes a physical method involving ultrasound and ball milling to disperse carbon nanotubes into a carbon slurry. This is then mixed with a conductive agent consisting of silver-coated copper by ultrasound and ball milling to form a liquid carbon network, creating a highly dispersed and mixed composite slurry. Compared to existing methods of forming carbon slurries by modifying carbon nanotubes, this method not only solves the dispersibility issues caused by carbon nanotube agglomeration, but also significantly reduces the number of steps and the cost of carbon nanotube modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of resistivity results of thin films formed from composite conductive pastes of metal-based doped carbon nanotubes prepared in Examples 1 to 4. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] In one embodiment of the present invention, a method for preparing a metal-based composite conductive paste doped with carbon nanotubes comprises the following steps:

[0027] Step 1. Pre-treating the metal powder: The metal powder is dispersed in polyvinyl pyrrolidone, and then subjected to surface modification with sodium hydroxide solution and dilute sulfuric acid in sequence, followed by washing and drying to obtain pre-treated metal powder;

[0028] Step 2. The pretreated metal powder, complexing agent, and dispersant A are thoroughly mixed, and then the pre-prepared silver ammonia solution is added. The pH is adjusted with an ammonia solution, and ultrasonic stirring is performed to mix the mixture evenly. A reducing agent is then added, and the mixture is washed and dried to obtain a conductive agent.

[0029] Step 3. The carbon nanotubes, dispersant B and solvent are mixed, and subjected to ultrasonication and ball milling to prepare a carbon precursor;

[0030] Step 4. The conductive agent obtained in step 2 is fully mixed with the carbon precursor, dispersant C and coupling agent in step 3 to obtain a conductive agent precursor for preparing a conductive paste;

[0031] Step 5. Fully mix the conductive agent precursor and the binder into a slurry state to obtain a composite conductive slurry.

[0032] In one embodiment, in step 1, the metal powder is copper powder, and the copper powder is flaky copper powder with a size of 1-5 μm.

[0033] In one embodiment, in step 1, the metal powder is nickel powder.

[0034] In one embodiment, the conductive agent is silver-coated copper powder or silver-coated nickel powder. Larger copper or nickel powders are easier to coat, but excessively large particle sizes can lead to uneven silver coating. Therefore, 1-5 μm flake copper powder is selected. During pickling, the acid concentration should be carefully considered; excessive acid concentrations can lead to copper loss and alter the copper powder particle size.

[0035] In one embodiment, in step 1, the weight ratio of metal powder, polyvinyl pyrrolidone, sodium hydroxide and dilute sulfuric acid is (3-7): (2-7): (45-55): (5-10).

[0036] In one embodiment, in step 2, the complexing agent accounts for 2%-15% of the mass of the conductive agent, the dispersant B accounts for 2.5%-5% of the mass of the conductive agent, and the reducing agent accounts for 0.5%-2.5% of the mass of the conductive agent.

[0037] In one embodiment, the complexing agent is disodium edetate.

[0038] In one embodiment, the dispersant A is polyvinyl pyrrolidone.

[0039] In one embodiment, the reducing agent is glucose.

[0040] In one embodiment, the concentration of sodium hydroxide is 0.1-0.5M.

[0041] In one embodiment, the concentration of the dilute sulfuric acid is 2%-5%.

[0042] In one embodiment, the concentration of the ammonia solution is 5%-20%.

[0043] In one embodiment, the conductive agent is silver-coated copper powder, and by mass percentage, the silver content in the silver-coated copper powder is 3%-8%, the disodium ethylenediaminetetraacetic acid content is 2%-15%, the polyvinylpyrrolidone content is 2.5%-5%, the ammonia concentration is 5%-20%, and the glucose content is 0.5%-2.5%.

[0044] In one embodiment, in step 3, by mass percentage, the carbon nanotubes are 5%-20%, the dispersant is 2.5%-5%, and the solvent is 60%-85%.

[0045] In one embodiment, in step 3, the carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, or a mixture thereof.

[0046] In one embodiment, in step 3, the dispersant B is at least one of polypropylene, polyether ester polymer and polymethylbutylene.

[0047] In one embodiment, in step 3, the solvent is cyclohexanone.

[0048] In one embodiment, in step 3, the ultrasonic treatment time is 0.5 h, and the ball milling treatment time is 2 h to 8 h.

[0049] In one embodiment, in step 4, the dispersant C is PVP with a molecular weight between 10,000 and 40,000, and the coupling agent is silane coupling agent KH550.

[0050] In one embodiment, in step 4, by mass proportion: conductive agent 80%-92%, carbon precursor 1%-5%, dispersant B 2.5%-5%, coupling agent 2%-5%.

[0051] In one embodiment, in step 4, the mixing method is ultrasonication followed by ball milling, and the ball milling speed is 250-800 r / min and the time is 2h to 8h.

[0052] In one embodiment, in step 5, the binder is at least one of polypropylene glycol, phenolic ester resin, o-phenylsilane resin, and phenolic resin.

[0053] In one embodiment, the metal-based doped carbon nanotube composite conductive paste includes the following components by mass percentage: 75%-95% metal powder, 1%-5% silver, 1%-5% carbon nanotubes, 0.5%-5% binder, and 0.5%-5% coupling agent.

[0054] The metal-based doped carbon nanotube composite conductive paste prepared in the above scheme is highly dispersed and highly mixed, can effectively solve the dispersion problem caused by carbon nanotube agglomeration, and has excellent conductive properties.

[0055] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0056] Example 1:

[0057] A silver-coated copper-doped carbon nanotube conductive paste comprises the following steps:

[0058] Step 1. Pretreatment of copper powder: 5 parts of copper powder were added to 0.25 parts of polyvinyl pyrrolidone (PVP) for dispersion treatment, and then surface modified by adding 50 parts of sodium hydroxide solution and 50 parts of dilute sulfuric acid solution, respectively, and then washed and dried to obtain pretreated copper powder;

[0059] Step 2. According to the mass percentage, the silver content of the silver-coated copper powder is 5%, the disodium ethylenediaminetetraacetic acid content is 2.5%, the polyvinylpyrrolidone content is 2.5%, the ammonia concentration is 8%, and the glucose content is 2.5%. The ingredients are prepared; 2.5% disodium ethylenediaminetetraacetic acid (EDTA-2Na) is added to the pretreated copper powder as a complex and 2.5% polyvinylpyrrolidone (PVP) is added as a dispersant, and the mixture is thoroughly mixed. The prepared 5% silver ammonia solution is added, and the pH is adjusted to 10 with the ammonia solution, and the mixture is uniformly mixed by ultrasonic stirring; then 75 mL of 0.1 M glucose solution is added as a reducing agent until silver ions on the surface of the copper powder are reduced to nanosilver. The resulting powder is washed with ethanol and water and dried to obtain silver-coated copper powder;

[0060] Step 3. 17.5% carbon nanotubes, 2.5% polypropylene, and 80% cyclohexanone were mixed uniformly by mass, ultrasonicated for 0.5 h, and ball-milled for 5 h to obtain a carbon precursor;

[0061] Step 4. Mix 90% of the silver-coated copper powder obtained in Step 2 with 4% of the carbon precursor obtained in Step 3, 3% polyvinyl pyrrolidone, and 3% silane coupling agent KH550, by mass percentage, and then perform ultrasonic treatment and ball milling at a speed of 500 rpm for 5 hours to obtain a conductive agent precursor for preparing a conductive paste.

[0062] Step 5. According to the mass percentage, 98% of the conductive agent precursor and 2% of polypropylene glycol are ultrasonically mixed for 4 hours to a slurry state to obtain a composite conductive slurry of metal-based doped carbon nanotubes.

[0063] The metal-based doped carbon nanotube composite conductive paste prepared in Example 1 was prepared into a 50 μm film by a coating machine. After curing, the resistivity was measured to be 2.5×10 -5 Ω·m, showing excellent electrical conductivity.

[0064] Example 2:

[0065] A silver-coated copper-doped carbon nanotube conductive paste comprises the following steps:

[0066] Step 1. Pretreatment of copper powder: 5 parts of copper powder were added to 0.25 parts of polyvinyl pyrrolidone (PVP) for dispersion treatment, and then surface modified by adding 50 parts of sodium hydroxide solution and 50 parts of dilute sulfuric acid solution, respectively, and then washed and dried to obtain pretreated copper powder;

[0067] Step 2. According to the mass percentage, the proportion of silver in the silver-coated copper powder is 3%, the proportion of disodium ethylenediaminetetraacetic acid is 2.5%, the proportion of polyvinylpyrrolidone is 2.5%, the concentration of ammonia water is 8%, and the proportion of glucose is 2.5%. The ingredients are prepared; 2.5% disodium ethylenediaminetetraacetic acid (EDTA-2Na) as a complex and 2.5% polyvinylpyrrolidone (PVP) as a dispersant are added to the pretreated copper powder, and the mixture is thoroughly mixed. The prepared 3% silver ammonia solution is added, and the pH is adjusted to 10 with an ammonia solution, and ultrasonic stirring is performed to mix evenly; then 75 mL of 0.1 M glucose solution is added as a reducing agent until silver ions on the surface of the copper powder are reduced to nanosilver. The obtained powder is washed with ethanol and water and dried to obtain silver-coated copper powder;

[0068] Step 3. 17.5% carbon nanotubes were added to 2.5% polypropylene by mass, and 80% cyclohexanone was added and mixed evenly. The mixture was ultrasonicated for 0.5 h and ball milled for 5 h to obtain a carbon precursor.

[0069] Step 4. 91% of the silver-coated copper powder obtained in Step 2 was mixed as a conductive agent with 3% of the carbon precursor obtained in Step 3, 3% polyvinyl pyrrolidone, and 3% of a silane coupling agent, KH550, by mass percentage. After ultrasonication, the mixture was ball-milled at a speed of 500 rpm for 5 hours to obtain a conductive agent precursor for preparing a conductive paste.

[0070] Step 5. According to the mass percentage, 98% of the conductive agent precursor and 2% of polypropylene glycol are ultrasonically mixed for 4 hours to a slurry state to obtain a composite conductive slurry of metal-based doped carbon nanotubes.

[0071] The metal-based doped carbon nanotube composite conductive paste prepared in Example 2 was prepared into a 50 μm film by a coating machine. After curing, the resistivity was measured to be 5×10 -5 Ω·m, showing excellent electrical conductivity.

[0072] Example 3:

[0073] A silver-coated copper-doped carbon nanotube conductive paste comprises the following steps:

[0074] Step 1. Pretreatment of copper powder: 5 parts of copper powder were added to 0.25 parts of polyvinyl pyrrolidone (PVP) for dispersion treatment, and then surface modified by adding 50 parts of sodium hydroxide solution and 50 parts of dilute sulfuric acid solution, respectively, and then washed and dried to obtain pretreated copper powder;

[0075] Step 2. According to the mass percentage, the proportion of silver in the silver-coated copper powder is 8%, the proportion of disodium ethylenediaminetetraacetic acid is 2.5%, the proportion of polyvinylpyrrolidone is 2.5%, the concentration of ammonia water is 8%, and the proportion of glucose is 2.5%. The ingredients are prepared; 2.5% disodium ethylenediaminetetraacetic acid (EDTA-2Na) as a complex and 2.5% polyvinylpyrrolidone (PVP) as a dispersant are added to the pretreated copper powder, and the mixture is thoroughly mixed. The prepared 8% silver ammonia solution is added, and the pH is adjusted to 10 with an ammonia solution, and ultrasonic stirring is performed to mix evenly; then 75 mL of 0.1 M glucose solution is added as a reducing agent until silver ions on the surface of the copper powder are reduced to nanosilver. The obtained powder is washed with ethanol and water and dried to obtain silver-coated copper powder;

[0076] Step 3. According to the mass percentage, 2.5% polypropylene and 80% cyclohexanone were added to 17.5% carbon nanotubes, mixed evenly, ultrasonicated for 0.5 h, and ball milled for 5 h to obtain a carbon precursor;

[0077] Step 4. 92% of the silver-coated copper powder obtained in Step 2 was mixed as a conductive agent with 2% of the carbon precursor obtained in Step 3, 3% polyvinyl pyrrolidone, and 3% silane coupling agent KH550, by mass percentage. After ultrasonication, the mixture was ball-milled at a speed of 500 rpm for 5 hours to obtain a conductive agent precursor for preparing a conductive paste.

[0078] Step 5. According to the mass percentage, 98% of the conductive agent precursor and 2% of polypropylene glycol are ultrasonically mixed for 4 hours to a slurry state to obtain a composite conductive slurry of metal-based doped carbon nanotubes.

[0079] The metal-based doped carbon nanotube composite conductive paste prepared in Example 3 was prepared into a 50 μm thin film by a coating machine. After curing, the resistivity was measured to be 5×10 -6 Ω·m, showing excellent electrical conductivity.

[0080] Example 4:

[0081] A method for preparing a silver-coated nickel-doped carbon nanotube conductive paste comprises the following steps:

[0082] Step 1. Pretreatment of nickel powder: 5 parts of copper powder were added to 0.25 parts of polyvinyl pyrrolidone (PVP) for dispersion treatment, and then surface modified by adding 50 parts of sodium hydroxide solution and 50 parts of dilute sulfuric acid solution, respectively, and then washed and dried to obtain pretreated nickel powder;

[0083] Step 2. According to the mass percentage, the silver content of the silver-coated nickel powder is 6%, the disodium ethylenediaminetetraacetic acid content is 2.5%, the polyvinylpyrrolidone content is 2.5%, the ammonia concentration is 8%, and the glucose content is 2.5%. The ingredients are prepared; 2.5% disodium ethylenediaminetetraacetic acid (EDTA-2Na) as a complex and 2.5% polyvinylpyrrolidone (PVP) as a dispersant are added to the pretreated nickel powder, and the mixture is thoroughly mixed. The prepared 6% silver ammonia solution is added, and the pH is adjusted to 11 with the ammonia solution, and the mixture is uniformly mixed by ultrasonic stirring; then 75 mL of 0.1 M glucose solution is added as a reducing agent until silver ions on the surface of the nickel powder are reduced to nanosilver. The resulting powder is washed with ethanol and water and dried to obtain silver-coated nickel powder;

[0084] Step 3. 17.5% carbon nanotubes were added to 2.5% polypropylene by mass, and 80% cyclohexanone was added and mixed evenly. The mixture was ultrasonicated for 0.5 h and ball milled for 5 h to obtain a carbon precursor.

[0085] Step 4. According to the mass percentage, 90% of the silver-coated nickel powder obtained in step 2 is mixed as a conductive agent with 4% of the carbon precursor in step 3, 3% polyvinyl pyrrolidone, and 3% silane coupling agent KH550. After ultrasonic treatment, the mixture is ball-milled at a speed of 500 r / min and a time of 5 h to obtain a conductive agent precursor for the final preparation of a conductive paste.

[0086] Step 5. According to the mass percentage, 98% of the conductive agent precursor and 2% of the phenolic ester resin are ultrasonically mixed for 4 hours to a slurry state to obtain a composite conductive slurry of metal-based doped carbon nanotubes.

[0087] The metal-based doped carbon nanotube composite conductive paste prepared in Example 4 was prepared into a 50 μm film using a coating machine. After curing, the resistivity was measured to be 7.5×10 -6 Ω·m, showing excellent electrical conductivity.

[0088] Figure 1 Schematic diagram of the resistivity results of the films formed from the composite conductive pastes of metal-based doped carbon nanotubes prepared in Examples 1 to 4. Figure 1 It can be seen from the figure that the metal-based doped carbon nanotube composite conductive paste prepared by the present invention has excellent conductive properties.

[0089] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a metal-based composite conductive paste doped with carbon nanotubes, characterized in that: The preparation method comprises the following steps: Step 1. Pre-treating the metal powder: The metal powder is dispersed in polyvinyl pyrrolidone, and then subjected to surface modification with sodium hydroxide solution and dilute sulfuric acid in sequence, followed by washing and drying to obtain pre-treated metal powder; Step 2. The pretreated metal powder, complexing agent, and dispersant A are thoroughly mixed, and then the pre-prepared silver ammonia solution is added. The pH is adjusted with an ammonia solution, and ultrasonic stirring is performed to mix the mixture evenly. A reducing agent is then added, and the mixture is washed and dried to obtain a conductive agent. Step 3. The carbon nanotubes, dispersant B and solvent are mixed, and subjected to ultrasonication and ball milling to prepare a carbon precursor; Step 4. The conductive agent obtained in step 2 is fully mixed with the carbon precursor, dispersant C and coupling agent in step 3 to obtain a conductive agent precursor for preparing a conductive paste; Step 5. Fully mix the conductive agent precursor and the binder into a slurry state to obtain a composite conductive slurry.

2. The preparation method according to claim 1, characterized in that In step 1, the metal powder is copper powder, and the copper powder is flaky copper powder with a size of 1-5 μm.

3. The preparation method according to claim 1, characterized in that In step 1, the weight ratio of metal powder, polyvinyl pyrrolidone, sodium hydroxide and dilute sulfuric acid is (3-7): (2-7): (45-55): (5-10).

4. The preparation method according to claim 1, characterized in that In step 2, the complexing agent accounts for 2%-15% of the mass of the conductive agent, the dispersant A accounts for 2.5%-5% of the mass of the conductive agent, and the reducing agent accounts for 0.5%-2.5% of the mass of the conductive agent.

5. The preparation method according to claim 1, characterized in that In step 3, by mass percentage, the carbon nanotubes are 5%-20%, the dispersant B is 2.5%-5%, and the solvent is 60%-85%.

6. The preparation method according to claim 1, characterized in that In step 3, the carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, or a mixture thereof.

7. The preparation method according to claim 1, characterized in that In step 3, the dispersant A is at least one of polypropylene, polyether ester polymer and polymethylbutylene.

8. The preparation method according to claim 1, characterized in that In step 4, the dispersant C is PVP with a molecular weight between 10,000 and 40,000, and the coupling agent is silane coupling agent KH550.

9. The preparation method according to claim 8, characterized in that In step 4, by mass proportion: conductive agent 80%-92%, carbon precursor 1%-5%, dispersant C 2.5%-5%, coupling agent 2%-5%.

10. The preparation method according to claim 1, characterized in that In step 5, the binder is at least one of polypropylene glycol, phenolic ester resin, o-phenylsilane resin, and phenolic resin.

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