Nanocarbon capacitor slurry, electrode and supercapacitor

Abstract

The application relates to the new energy technology field, in particular to a nano-carbon capacitor slurry, an electrode and a super capacitor, and according to weight parts, effective components of raw materials of the nano-carbon capacitor slurry include the following components: 18-22 parts of nano-carbon materials; 3-6 parts of a binder; wherein the nano-carbon materials are graphene-carbon nanotube double-carbon network / crystalline MOF composite materials. The nano-carbon capacitor slurry provided by the application takes the graphene-carbon nanotube double-carbon network / crystalline MOF composite material as a conductive agent, the conductive agent is synergized by graphene, carbon nanotubes and MOF structures, the dispersivity of graphene and carbon nanotubes is effectively improved while the conductive performance is ensured, and therefore the nano-carbon capacitor slurry is endowed with excellent stability and electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, and in particular to a nano-carbon capacitor paste, electrode, and supercapacitor. Background Technology

[0002] With the increasing demand for efficient energy storage solutions, supercapacitors, as a high-power-density, long-cycle-life energy storage device, have shown great application potential and are considered one of the most promising energy storage devices.

[0003] The structure of a supercapacitor mainly consists of porous electrode materials with high specific surface area (including current collectors), a porous battery separator, and an electrolyte. The electrode is one of the key components in the supercapacitor's structure; it is obtained by coating a conductive agent slurry onto the current collector, drying it, and ensuring active loading. Most existing slurries suffer from poor stability and low electrochemical performance, such as specific capacitance and cycle life, severely limiting their widespread adoption. Therefore, how to coat the current collector with a conductive agent while ensuring high conductivity, high specific capacitance, and long service life is a significant challenge.

[0004] Carbon nanotubes are one of the more mature nanomaterials in recent years. They have excellent electrical conductivity, chemical stability, thermal stability and electrochemical cycling stability. Due to their one-dimensional nanostructure, electrons can be conducted at a relatively fast axial speed. As a conductive material, they can effectively reduce the internal resistance of the system. This material has a wide range of applications as a highly efficient conductive agent in electrochemical energy storage devices.

[0005] However, although carbon nanotubes have many advantages over conventional conductive agents, their strong van der Waals forces make them difficult to disperse fully during slurry preparation. Insufficiently dispersed carbon nanotube aggregates cannot form an efficient and uniform three-dimensional conductive network, resulting in poor conductive chemical properties and limiting their application in supercapacitors. Summary of the Invention

[0006] To address the problem of insufficient dispersion of carbon nanotubes in existing technologies, this invention provides a nano-carbon capacitor paste. This paste forms a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material by applying MOF crystalline form to graphene and carbon nanotubes. The MOF structure serves as an excellent intercalating agent, effectively improving dispersibility and solving the problem of insufficient dispersion of carbon nanotubes in existing technologies.

[0007] The technical solution adopted by this invention to solve its technical problem is:

[0008] A nano-carbon capacitor paste, by weight, comprises the following active ingredients:

[0009] 18-22 parts of nano-carbon material;

[0010] 3-6 parts adhesive;

[0011] The nano-carbon material is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material.

[0012] Optionally, the nano-carbon material is prepared according to the following method:

[0013] S1: Carbon nanotubes are oxidized to obtain product I;

[0014] S2: Oxidize the graphene to obtain product II;

[0015] S3: Using product I, product II, metal salt, and organic ligand as raw materials, a solvothermal reaction is carried out to obtain nano-carbon materials.

[0016] Optionally, the metal salt is selected from at least one of copper salt, zinc salt, nickel salt, and cobalt salt.

[0017] Optionally, the organic ligand is selected from at least one of terephthalic acid, 1,3,5-benzenetricarboxylic acid, 2,5-dihydroxyterephthalic acid, pyromellitic acid, and citric acid.

[0018] Optionally, the molar ratio of the metal salt to the organic ligand is (2-4):1.

[0019] Optionally, the mass ratio of product I to product II is 1:(1-2).

[0020] Optionally, the ratio of the total mass of product I and product II to the total mass of the metal salt and the organic ligand is (0.2-0.5):1.

[0021] Optionally, the adhesive is a composite adhesive composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of (0.7-0.9):(0.1-0.3).

[0022] Another object of the present invention is to provide an electrode comprising the nano-carbon capacitor paste as described above.

[0023] Another object of the present invention is to provide a supercapacitor comprising the electrodes described above.

[0024] The beneficial effects of this invention are:

[0025] The nano-carbon capacitor paste provided by this invention uses a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material as a conductive agent. Through the synergistic effect of graphene, carbon nanotubes and MOF structure, the conductive agent effectively improves the dispersibility of graphene and carbon nanotubes while ensuring conductivity, thereby endowing the nano-carbon capacitor paste with excellent stability and electrochemical performance. Detailed Implementation

[0026] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] To address the problem of insufficient dispersion of carbon nanotubes in existing technologies, this invention provides a nano-carbon capacitor paste. The effective components of this nano-carbon capacitor paste raw material, by weight, include the following:

[0028] 18-22 parts of nano-carbon material;

[0029] 3-6 parts adhesive;

[0030] Among them, the nano-carbon material is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material.

[0031] In addition, the raw materials of the nano-carbon capacitor paste also include water, preferably deionized water. The amount of deionized water added depends on the amount of nano-carbon material and binder. Specifically, in the present invention, the total amount of nano-carbon material, binder and deionized water in the raw materials of the nano-carbon capacitor paste is 100 parts by weight.

[0032] Currently used nanomaterials include graphene with a two-dimensional structure, carbon nanotubes with a one-dimensional structure, and carbon dots or quantum dots with a zero-dimensional structure. However, all of these materials are prone to agglomeration and unstable slurries, resulting in poor electrochemical performance such as short cycle life and low specific capacitance in the long-term use of nanomaterial capacitor slurries in existing technologies. MOFs, as a unique type of crystalline material, are composed of various metal nodes and organic ligands, possessing a large number of potential active sites, large specific surface area, and structural flexibility. However, they have poor conductivity. Therefore, the use of MOF materials currently involves calcination and carbonization to form nanostructure phases. Although this can solve the problem of poor conductivity to some extent, it also generates huge energy consumption. Considering the above, this invention applies crystalline MOFs to graphene and carbon nanotubes to form a novel graphene-carbon nanotube dual-carbon network / crystalline MOF composite material, involving 0D, 1D, and 2D spatial network structures. The aim is to utilize the graphene / carbon nanotube dual-carbon network to improve conductivity and reduce internal resistance. Simultaneously, the porous structure of MOFs enhances the accessibility of charge carriers and charge storage capacity in the electrode material, ultimately improving electrochemical performance such as cycle life and specific capacitance. Furthermore, the MOF structure, as an excellent intercalating agent, can effectively improve the dispersibility of graphene and carbon nanotubes.

[0033] The nano-carbon capacitor paste provided by this invention uses a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material as a conductive agent. Through the synergistic effect of graphene, carbon nanotubes and MOF structure, the conductive agent effectively improves the dispersibility of graphene and carbon nanotubes while ensuring conductivity, thereby endowing the nano-carbon capacitor paste with excellent stability and electrochemical performance.

[0034] The preferred nano-carbon material of this invention is prepared according to the following method:

[0035] S1: Carbon nanotubes are oxidized to obtain product I;

[0036] The carbon nanotubes preferred in this invention are multi-walled carbon nanotubes; and preferably, after oxidation treatment, the carboxyl content in product I is 2.5-3.0 wt%.

[0037] Specifically, this step is preferably performed according to the following method:

[0038] Carbon nanotubes were placed in an oxy-containing strong acid and magnetically stirred. The temperature was raised to 60-90℃, and the reaction endpoint was set when the carboxyl content reached 2.5-3.0 wt%. After the reaction was completed, the mixture was centrifuged at 10000 r / min for 5 min and dried at room temperature for 6 h to obtain product I, which was then set aside for use. Preferably, the ratio of carbon nanotubes to oxy-containing strong acid in this step was 1 g: 20 mL. Preferably, the carbon nanotubes were multi-walled carbon nanotubes, and more preferably, the diameter of the carbon nanotubes was 80-100 nm and the length was 3-4 μm.

[0039] In this invention, the oxy-containing strong acid in this step is preferably nitric acid or sulfuric acid, preferably added in the form of a solution, and more preferably the concentration of the oxy-containing strong acid in the solution is 7.0-10.0 mol / L;

[0040] S2: Oxidize the graphene to obtain product II;

[0041] Preferably, after oxidation treatment, the carboxyl content in product II is 5.0-5.5 wt%;

[0042] Specifically, this step is preferably performed according to the following method:

[0043] Graphene and sodium nitrate were added to concentrated sulfuric acid (98% by mass). The mixture was stirred at room temperature for 1-2 hours, then potassium permanganate was added, and the temperature was raised to 30-40°C. The mixture was stirred until the carboxyl content was 5.0-5.5 wt%. Deionized water was then slowly added, and the mixture was stirred at 95-100°C for 0.5 hours. 30% hydrogen peroxide was then added dropwise to remove excess potassium permanganate (potassium permanganate is purple and will fade upon the addition of hydrogen peroxide; the addition of hydrogen peroxide was stopped when the color of the reaction solution remained unchanged), resulting in a yellow dispersion. The dispersion was centrifuged at 10000 r / min for 5 minutes and washed with deionized water until neutral. The solution was dried at room temperature for 6 hours to obtain product II, which was then ready for use.

[0044] The preferred graphene thickness is 0.5-5 nm, and the sheet area is 0.01-50 μm. 2 In this invention, the preferred ratio of graphene, sodium nitrate, concentrated sulfuric acid, potassium permanganate, and deionized water in this step is 1g:(0.3-0.8)g:(20-30)mL:(3-8)g:(50-80)mL, and more preferably, the preferred ratio is 1g:0.5g:25mL:5.0g:60mL.

[0045] S3: Using product I, product II, metal salt, and organic ligand as raw materials, a solvothermal reaction is carried out to obtain nano-carbon materials;

[0046] Preferably, this step is performed as follows:

[0047] Metal salts and organic ligands were added to N,N-dimethylformamide and magnetically stirred for 0.5 h. Then, product I and product II were added, ultrasonically dispersed for 0.5 h, and magnetically stirred at 300 r / min for 3 h to obtain a mixture. The mixture was then added to a sealed reactor, slowly heated to 120-150 °C, and kept at that temperature for 8-24 h. After cooling, the mixture was centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0048] The method for preparing nano-carbon materials provided by this invention first involves oxidizing carbon nanotubes and graphene respectively. Then, the oxidized carbon nanotubes and graphene are used as part of the ligands and reacted together with organic ligands to generate MOF structures. In other words, the in-situ growth reaction of MOFs is carried out on the surface of carbon nanotubes and between graphene layers, so that the generated MOF structure acts as an excellent intercalating agent, effectively improving the dispersibility of carbon nanotubes and graphene.

[0049] Specifically, the nano-carbon material prepared by this invention is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material. First, the MOF structure is a porous structure with a high specific surface area, which can significantly improve the accessibility of charge carriers and charge storage capacity in the electrode material, ultimately achieving synergistic optimization of high power density and high energy density. Second, the high aspect ratio of carbon nanotubes provides excellent mechanical properties, which can suppress microcracks in the cyclic lattice. Graphene sheets form interlayer coverage on the MOF crystal faces, preventing the dissolution of MOF in the electrolyte, thereby synergistically extending cycle life. Third, the graphene sheets and the axial carbon nanotubes exhibit high electron migration efficiency and form a point-line-surface continuous network structure with the MOF, resulting in low interfacial impedance. Fourth, the MOF structure is deposited and intercalated between graphene layers and on the surface of carbon nanotubes, effectively improving the dispersibility of the nanomaterial, thus enabling the nano-carbon material to exhibit excellent electrochemical properties.

[0050] The metal salt of the present invention is preferably selected from at least one of copper salt, zinc salt, nickel salt, and cobalt salt. More preferably, the anion in the metal salt is selected from at least one of nitrate, sulfate, chloride, and acetate.

[0051] The organic ligand of the present invention is preferably a polycarboxylic acid structure, and more preferably selected from at least one of terephthalic acid, 1,3,5-benzenetricarboxylic acid, 2,5-dihydroxyterephthalic acid, pyromellitic acid, and citric acid.

[0052] Furthermore, the present invention preferably has a molar ratio of metal salt to organic ligand of (2-4):1, and a mass ratio of product I to product II of 1:(1-2); and preferably the ratio of the total mass of product I and product II to the total mass of metal salt and organic ligand is (0.2-0.5):1, that is, the total mass of product I and product II is denoted as the first total mass, and the total mass of metal salt and organic ligand is denoted as the second total mass, and the ratio of the first total mass to the second total mass is (0.2-0.5):1.

[0053] The present invention preferably uses a composite adhesive as the adhesive, and more preferably uses a composite adhesive composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of (0.7-0.9):(0.1-0.3); and preferably the degree of sulfonation in the sulfonated polyaniline is 0.35-0.45 mol%, and the weight average molecular weight is 50,000-80,000.

[0054] The composite binder used in this invention uses sulfonated polyaniline, which has a conductive polymer structure. The sulfonic acid groups can form hydrogen bonds with oxygen-containing functional groups in graphene or carbon nanotubes, and can also form coordination bonds with active metal sites in MOF materials, forming a highly efficient conductive pathway while also having advantages such as anti-settling. The carboxyl groups in carboxymethyl cellulose also have anti-settling and thickening effects. Furthermore, this composite binder has a water-soluble structure and is safe, environmentally friendly, and low-carbon.

[0055] The nano-carbon capacitor paste of this invention can be prepared according to the following method:

[0056] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are then slowly added and sheared to obtain the nano-carbon capacitor slurry.

[0057] This invention addresses the problems of poor electrochemical performance in existing nano-carbon capacitor pastes, such as short cycle life and low specific capacitance, during long-term use. It provides a nano-carbon capacitor paste by first preparing MOF material on the surface of graphene / carbon nanotubes as the nano-carbon material through a solvothermal reaction, and then formulating the paste accordingly. This product exhibits excellent electrochemical performance.

[0058] Another object of the present invention is to provide an electrode comprising the nano-carbon capacitor paste as described above.

[0059] Specifically, the electrode includes a current collector. The electrode sheet, i.e., the electrode, is obtained by coating the current collector with the nano-carbon capacitor paste as described above, drying it under vacuum, and then rolling it.

[0060] The electrode provided by this invention uses a nano-carbon capacitor paste with a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material as a conductive agent. Through the synergistic effect of graphene, carbon nanotubes and MOF structure, the conductive agent effectively improves the dispersibility of graphene and carbon nanotubes while ensuring conductivity, thereby endowing the nano-carbon capacitor paste with excellent stability and electrochemical performance, and thus endowing the electrode with excellent electrochemical performance.

[0061] Another object of the present invention is to provide a supercapacitor comprising the electrodes described above.

[0062] The supercapacitor provided by this invention uses a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material as a conductive agent in its electrode nano-carbon capacitor paste. Through the synergistic effect of graphene, carbon nanotubes and MOF structure, this conductive agent effectively improves the dispersibility of graphene and carbon nanotubes while ensuring conductivity, thereby endowing the nano-carbon capacitor paste with excellent stability and electrochemical performance, and thus endowing the supercapacitor with excellent electrochemical performance.

[0063] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0064] Unless otherwise specified, the multi-walled carbon nanotubes in all embodiments and comparative examples of this invention have a diameter of 90 nm and a length of 3.5 μm; the graphene thickness is 1.5 nm and the sheet area is 1.0 μm. 2 The metal salt anions are all chloride ions; the organic ligands are all mixtures of 1,3,5-benzenetricarboxylic acid and 2,5-dihydroxyterephthalic acid in a molar ratio of 3:1; the concentrated sulfuric acid is 98% sulfuric acid by mass.

[0065] Example 1

[0066] This embodiment provides a nano-carbon capacitor paste, which, by weight, comprises the following components:

[0067] 20.5 parts of nano-carbon material;

[0068] 4.5 parts adhesive;

[0069] 75 parts deionized water;

[0070] Among them, the nano-carbon material is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material, and the preparation steps of this graphene-carbon nanotube dual-carbon network / crystalline MOF composite material are as follows:

[0071] S1: Place 1g of multi-walled carbon nanotubes in 20mL of 9.0mol / L nitric acid, stir magnetically, heat to 80℃, stir until the carboxyl content reaches 2.8wt%, which is the reaction endpoint. After the reaction is completed, centrifuge at 10000r / min for 5min, and dry at room temperature for 6h to obtain product I, which is ready for use.

[0072] S2: 1g of graphene and 0.5g of sodium nitrate were added to 25mL of concentrated sulfuric acid and stirred at room temperature for 1.5h. Then, 5.0g of potassium permanganate was added, and the temperature was raised to 35℃. The reaction was continued until the carboxyl content was 5.2wt%. Then, 60mL of deionized water was slowly added, and the temperature was maintained at 98℃. After stirring for 0.5h, 30% hydrogen peroxide was added to remove excess potassium permanganate, resulting in a yellow dispersion. The dispersion was centrifuged at 10000r / min for 5min, washed with deionized water until neutral, and dried at room temperature for 6h to obtain product II, which was then set aside for use.

[0073] S3: 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.1 g of product I and 0.15 g of product II were added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor and slowly heated to 140 °C. After holding at this temperature for 14 h, the mixture was cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0074] The binder is a composite binder composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of 0.8:0.2; the degree of sulfonation in the sulfonated polyaniline is 0.40 mol%, and the weight average molecular weight is 70,000.

[0075] The nano-carbon capacitor paste in this embodiment was prepared according to the following method:

[0076] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are slowly added, and the mixture is sheared to adjust the viscosity to 5600 mPa·s. Vacuum is then applied to obtain the nano-carbon capacitor slurry.

[0077] Example 2

[0078] This embodiment provides a nano-carbon capacitor paste, which, by weight, comprises the following components:

[0079] 18 parts of nano-carbon materials;

[0080] 3 parts adhesive;

[0081] 79 parts of deionized water;

[0082] Among them, the nano-carbon material is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material, and the preparation steps of this graphene-carbon nanotube dual-carbon network / crystalline MOF composite material are as follows:

[0083] S1: Place 1g of multi-walled carbon nanotubes in 20mL of sulfuric acid (concentration of 10.0mol / L), stir magnetically, heat to 60℃, stir until the carboxyl content reaches 3.0wt%, which is the reaction endpoint. After the reaction is completed, centrifuge at 10000r / min for 5min, and dry at room temperature for 6h to obtain product I, which is ready for use.

[0084] S2: Add 1g of graphene and 0.5g of sodium nitrate to 25mL of concentrated sulfuric acid and stir at room temperature for 1h; then add 5.0g of potassium permanganate, heat to 40℃, and react until the carboxyl content is 5.5wt%; then slowly add 60mL of deionized water, keep stirring at 100℃ for 0.5h, then add 30% hydrogen peroxide to remove excess potassium permanganate, and obtain a yellow dispersion; centrifuge the dispersion at 10000r / min for 5min, wash with deionized water until neutral; dry at room temperature for 6h to obtain product II, which is ready for use.

[0085] S3: 0.54 g (4 mmol) of metal salt (a mixture of copper and cobalt salts in a ratio of 0.38 g (2.8 mmol): 0.16 g (1.2 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.12 g of product I and 0.18 g of product II were added to the above solution and ultrasonically dispersed for 0.5 h. After magnetic stirring for 3 h at a stirring rate of 300 r / min, the mixture was added to a sealed reactor and slowly heated to 150 °C. The temperature was then maintained for 8 h, cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0086] The binder is a composite binder composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of 0.7:0.3; the degree of sulfonation in the sulfonated polyaniline is 0.35 mol%, and the weight average molecular weight is 50,000.

[0087] The nano-carbon capacitor paste in this embodiment was prepared according to the following method:

[0088] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are slowly added, sheared, and the viscosity is adjusted to 5000 mPa·s. Vacuum is then applied to obtain the nano-carbon capacitor slurry.

[0089] Example 3

[0090] This embodiment provides a nano-carbon capacitor paste, which, by weight, comprises the following components:

[0091] 22 parts of nano-carbon materials;

[0092] 6 parts adhesive;

[0093] 72 parts of deionized water;

[0094] Among them, the nano-carbon material is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material, and the preparation steps of this graphene-carbon nanotube dual-carbon network / crystalline MOF composite material are as follows:

[0095] S1: Place 1g of multi-walled carbon nanotubes in 20mL of nitric acid (7.0mol / L concentration), stir magnetically, heat to 90℃ and stir until the carboxyl content reaches 2.5wt% as the reaction endpoint. After the reaction is complete, centrifuge at 10000r / min for 5min and dry at room temperature for 6h to obtain product I, which is ready for use.

[0096] S2: Add 1g graphene and 0.5g sodium nitrate to 25mL concentrated sulfuric acid and stir at room temperature for 2h; then add 5.0g potassium permanganate and heat to 30℃ until the carboxyl content is 5.0wt%; then slowly add 60mL deionized water and stir at 95℃ for 0.5h; add 30% hydrogen peroxide to remove excess potassium permanganate, and obtain a yellow dispersion; centrifuge the dispersion at 10000r / min for 5min, wash with deionized water until neutral; dry at room temperature for 6h to obtain product II, which is ready for use.

[0097] S3: 0.27 g (2 mmol) of metal salt (a mixture of copper and zinc salts in a ratio of 0.19 g (1.4 mmol): 0.08 g (0.6 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.08 g of product I and 0.12 g of product II were added to the above solution and ultrasonically dispersed for 0.5 h. After magnetic stirring for 3 h at a stirring rate of 300 r / min, the mixture was added to a sealed reactor and slowly heated to 120 °C. The temperature was then maintained for 24 h, cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0098] The binder is a composite binder composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of 0.9:0.1; the degree of sulfonation of the sulfonated polyaniline is 0.45 mol%, and the weight average molecular weight is 80,000.

[0099] The nano-carbon capacitor paste in this embodiment was prepared according to the following method:

[0100] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are slowly added, and the mixture is sheared to adjust the viscosity to 6000 mPa·s. Vacuum is then applied to obtain the nano-carbon capacitor slurry.

[0101] Example 4

[0102] The difference between this embodiment and Example 1 is that, in the preparation process of the graphene-carbon nanotube dual carbon network / crystalline MOF composite material, step S3 is as follows:

[0103] S3: Add 0.40 g (3 mmol) of copper metal salt and 0.21 g (1 mmol) of organic ligand to 100 mL of N,N dimethylformamide. After magnetic stirring for 0.5 h, add 0.1 g of product I and 0.15 g of product II to the above solution. After ultrasonic dispersion for 0.5 h, magnetic stirring is carried out for 3 h at a stirring rate of 300 r / min. The above mixture is added to a sealed reaction vessel, and the temperature is slowly raised to 140 °C. Then, it is kept at this temperature for 14 h, cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0104] Example 5

[0105] The difference between this embodiment and Example 1 is that, in the preparation process of the graphene-carbon nanotube dual carbon network / crystalline MOF composite material, step S3 is as follows:

[0106] S3: 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.05 g of product I and 0.07 g of product II were added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor and slowly heated to 140 °C. After holding at this temperature for 14 h, the mixture was cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0107] Example 6

[0108] The difference between this embodiment and Example 1 is that, in the preparation process of the graphene-carbon nanotube dual carbon network / crystalline MOF composite material, step S3 is as follows:

[0109] S3: 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.12 g of product I and 0.18 g of product II were added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor and slowly heated to 140 °C. After holding at this temperature for 14 h, the mixture was cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0110] Example 7

[0111] The difference between this embodiment and Example 1 is that, in the preparation process of the graphene-carbon nanotube dual carbon network / crystalline MOF composite material, step S3 is as follows:

[0112] S3: 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.12 g of product I and 0.12 g of product II were added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor and slowly heated to 140 °C. After holding at this temperature for 14 h, the mixture was cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0113] Example 8

[0114] The difference between this embodiment and Example 1 is that, in the preparation process of the graphene-carbon nanotube dual carbon network / crystalline MOF composite material, step S3 is as follows:

[0115] S3: 0.40 g (3 mmol) of metal salt (a mixture of copper salt and nickel salt in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.08 g of product I and 0.16 g of product II were added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor and slowly heated to 140 °C. After holding at this temperature for 14 h, the mixture was cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0116] The following comparative examples are all compared with Example 1.

[0117] Comparative Example 1

[0118] This comparative example provides a nano-carbon capacitor paste, which, by weight, comprises the following components:

[0119] 20.5 parts of nano-carbon material;

[0120] 4.5 parts adhesive;

[0121] 75 parts deionized water;

[0122] The preparation steps for nano-carbon materials are as follows:

[0123] S1: Place 1g of multi-walled carbon nanotubes in 20mL of 9.0mol / L nitric acid, stir magnetically, heat to 80℃, stir until the carboxyl content reaches 2.8wt%, which is the reaction endpoint. After the reaction is completed, centrifuge at 10000r / min for 5min, and dry at room temperature for 6h to obtain product I, which is ready for use.

[0124] S2: 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.25 g of product I was added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor, slowly heated to 140 °C, and kept at that temperature for 14 h. After cooling, the mixture was centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, i.e., nano-carbon material.

[0125] The binder is a composite binder composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of 0.8:0.2; the degree of sulfonation in the sulfonated polyaniline is 0.40 mol%, and the weight average molecular weight is 70,000.

[0126] The nano-carbon capacitor paste of this comparative example was prepared according to the following method:

[0127] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are slowly added, and the mixture is sheared to adjust the viscosity to 5600 mPa·s. Vacuum is then applied to obtain the nano-carbon capacitor slurry.

[0128] Comparative Example 2

[0129] The difference between this comparative example and Example 1 is that step S2 is as follows:

[0130] S2: Add 1g of graphene and 0.5g of sodium nitrate to 25mL of concentrated sulfuric acid and stir at room temperature for 1.5h; then add 5.0g of potassium permanganate, heat to 35℃, and react until the carboxyl content is 4.5wt%; then slowly add 60mL of deionized water, maintain at 98℃, stir for 0.5h, then add 30% hydrogen peroxide to remove excess potassium permanganate, and obtain a yellow dispersion; centrifuge the dispersion at 10000r / min for 5min, wash with deionized water until neutral, and dry at room temperature for 6h to obtain product II, which is ready for use.

[0131] Comparative Example 3

[0132] The difference between this comparative example and Example 1 is that step S2 is as follows:

[0133] S2: Add 1g of graphene and 0.5g of sodium nitrate to 25mL of concentrated sulfuric acid and stir at room temperature for 1.5h; then add 5.0g of potassium permanganate, heat to 35℃, and react until the carboxyl content is 6.0wt%; then slowly add 60mL of deionized water, maintain at 98℃, stir for 0.5h, and then add 30% hydrogen peroxide to remove excess potassium permanganate, obtaining a yellow dispersion; centrifuge the dispersion at 10000r / min for 5min, wash with deionized water until neutral, and dry at room temperature for 6h to obtain product II, which is ready for use.

[0134] Comparative Example 4

[0135] This comparative example provides a nano-carbon capacitor paste, which, by weight, comprises the following components:

[0136] 20.5 parts of nano-carbon material;

[0137] 4.5 parts adhesive;

[0138] 75 parts deionized water;

[0139] The preparation steps for nano-carbon materials are as follows:

[0140] S1: 1g graphene and 0.5g sodium nitrate were added to 25mL concentrated sulfuric acid and stirred at room temperature for 1.5h; then 5.0g potassium permanganate was added, and the temperature was raised to 35℃, reacting until the carboxyl content was 5.2wt%; then 60mL deionized water was slowly added, and the temperature was maintained at 98℃. After stirring for 0.5h, 30% hydrogen peroxide was added to remove excess potassium permanganate, resulting in a yellow dispersion; the dispersion was centrifuged at 10000r / min for 5min, washed with deionized water until neutral, and dried at room temperature for 6h to obtain product II, which was then set aside for use.

[0141] S2: 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.25 g of product II was added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor and slowly heated to 140 °C. After holding at this temperature for 14 h, the mixture was cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely, nano-carbon material.

[0142] The binder is a composite binder composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of 0.8:0.2; the degree of sulfonation in the sulfonated polyaniline is 0.40 mol%, and the weight average molecular weight is 70,000.

[0143] The nano-carbon capacitor paste of this comparative example was prepared according to the following method:

[0144] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are slowly added, and the mixture is sheared to adjust the viscosity to 5600 mPa·s. Vacuum is then applied to obtain the nano-carbon capacitor slurry.

[0145] Comparative Example 5

[0146] The difference between this comparative example and Example 1 is that step S1 is as follows:

[0147] S1: Place 1g of multi-walled carbon nanotubes in 20mL of 9.0mol / L nitric acid, stir magnetically, heat to 80℃, stir until the carboxyl content reaches 2.0wt%, which is the reaction endpoint. After the reaction is completed, centrifuge at 10000r / min for 5min, and dry at room temperature for 6h to obtain product I, which is ready for use.

[0148] Comparative Example 6

[0149] The difference between this comparative example and Example 1 is that step S1 is as follows:

[0150] S1: Place 1g of multi-walled carbon nanotubes in 20mL of 9.0mol / L nitric acid, stir magnetically, heat to 80℃, stir until the carboxyl content reaches 3.5wt%, which is the reaction endpoint. After the reaction is completed, centrifuge at 10000r / min for 5min, and dry at room temperature for 6h to obtain product I, which is ready for use.

[0151] Comparative Example 7

[0152] This comparative example provides a nano-carbon capacitor paste, which, by weight, comprises the following components:

[0153] 20.5 parts of nano-carbon material;

[0154] 4.5 parts adhesive;

[0155] 75 parts deionized water;

[0156] The preparation steps for nano-carbon materials are as follows:

[0157] S1: Place 1g of multi-walled carbon nanotubes in 20mL of 9.0mol / L nitric acid, stir magnetically, heat to 80℃, stir until the carboxyl content reaches 2.8wt%, which is the reaction endpoint. After the reaction is completed, centrifuge at 10000r / min for 5min, and dry at room temperature for 6h to obtain product I, which is ready for use.

[0158] S2: 1g of graphene and 0.5g of sodium nitrate were added to 25mL of concentrated sulfuric acid and stirred at room temperature for 1.5h. Then, 5.0g of potassium permanganate was added, and the temperature was raised to 35℃. The reaction was continued until the carboxyl content was 5.2wt%. Then, 60mL of deionized water was slowly added, and the temperature was maintained at 98℃. After stirring for 0.5h, 30% hydrogen peroxide was added to remove excess potassium permanganate, resulting in a yellow dispersion. The dispersion was centrifuged at 10000r / min for 5min, washed with deionized water until neutral, and dried at room temperature for 6h to obtain product II, which was then set aside for use.

[0159] S3: Add 0.1g of product I and 0.15g of product II to 100mL of N,N-dimethylformamide, stir magnetically for 0.5h, then add the mixture to a sealed reactor, slowly heat to 140℃, keep warm for 14h, cool, centrifuge at 5000r / min for 3min, wash with anhydrous ethanol, and dry at 80℃ for 4h to obtain the target product, i.e., nano-carbon material.

[0160] The binder is a composite binder composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of 0.8:0.2; the degree of sulfonation in the sulfonated polyaniline is 0.40 mol%, and the weight average molecular weight is 70,000.

[0161] The nano-carbon capacitor paste in this embodiment was prepared according to the following method:

[0162] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are slowly added, and the mixture is sheared to adjust the viscosity to 5600 mPa·s. Vacuum is then applied to obtain the nano-carbon capacitor slurry.

[0163] Comparative Example 8

[0164] This comparative example provides a nano-carbon capacitor paste, which, by weight, comprises the following components:

[0165] 20.5 parts of nano-carbon material;

[0166] 4.5 parts adhesive;

[0167] 75 parts deionized water;

[0168] The preparation steps for nano-carbon materials are as follows:

[0169] 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N dimethylformamide. After magnetic stirring for 0.5 h, the mixture was added to a sealed reactor, and the temperature was slowly raised to 140 °C and kept at that temperature for 14 h. After cooling, the mixture was centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely, nano-carbon material.

[0170] The binder is a composite binder composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of 0.8:0.2; the degree of sulfonation in the sulfonated polyaniline is 0.40 mol%, and the weight average molecular weight is 70,000.

[0171] The nano-carbon capacitor paste in this embodiment was prepared according to the following method:

[0172] According to the formula, the nano-carbon material is added to some deionized water for grinding and ultrasonic dispersion. The composite binder and the remaining deionized water are slowly added, and the mixture is sheared to adjust the viscosity to 5600 mPa·s. Vacuum is then applied to obtain the nano-carbon capacitor slurry.

[0173] Comparative Example 9

[0174] The difference between this comparative example and Example 1 is that step S3 is as follows:

[0175] S3: 0.40 g (3 mmol) of metal salt (a mixture of copper and nickel salts in a ratio of 0.28 g (2.1 mmol): 0.12 g (0.9 mmol)) and 0.21 g (1 mmol) of organic ligand were added to 100 mL of N,N-dimethylformamide. After magnetic stirring for 0.5 h, 0.15 g of product I and 0.22 g of product II were added to the above solution. After ultrasonic dispersion for 0.5 h, the mixture was magnetically stirred for 3 h at a stirring rate of 300 r / min. The mixture was then added to a sealed reactor and slowly heated to 140 °C. After holding at this temperature for 14 h, the mixture was cooled, centrifuged at 5000 r / min for 3 min, washed with anhydrous ethanol, and dried at 80 °C for 4 h to obtain the target product, namely the graphene-carbon nanotube dual carbon network / crystalline MOF composite material.

[0176] Comparative Example 10

[0177] The difference between this comparative example and Example 1 is that the binder is sulfonated polyaniline.

[0178] Comparative Example 11

[0179] The difference between this comparative example and Example 1 is that the degree of sulfonation in the sulfonated polyaniline is 0.30 mol%, and the weight-average molecular weight is 40,000.

[0180] Comparative Example 12

[0181] The difference between this comparative example and Example 1 is that the degree of sulfonation in the sulfonated polyaniline is 0.50 mol%, and the weight-average molecular weight is 90,000.

[0182] Comparative Example 13

[0183] The difference between this comparative example and Example 1 is that the binder is carboxymethyl cellulose.

[0184] The capacitor paste from each of the above embodiments and comparative examples was uniformly coated onto the surface of a pretreated nickel foam current collector (1cm × 1cm), and then dried in a vacuum oven at 110℃, ensuring that the mass loading of the active material was controlled between 1.2-2.0 mg·cm³. -2 Between these layers, a double-sided supercapacitor electrode is obtained by rolling. During electrode assembly, two active electrode sheets with matching mass are selected to construct a symmetrical supercapacitor. The electrolyte used is 3 mol·L⁻¹. -1 KOH solution, with physical isolation between electrodes using a glass fiber diaphragm.

[0185] The physical properties of the nano-carbon capacitor paste in each embodiment and comparative example of the present invention were measured respectively, and the test methods are as follows:

[0186] (1) Slurry properties:

[0187] (1.1) Settling rate: After the slurry is left to stand for 24 hours, the percentage of settling mass is calculated.

[0188] (1.2) Slurry state: visual flowability; the flowability is represented by ☆, ○, ◇, × respectively from best to worst.

[0189] (2) Electrochemical performance: Cyclic voltammetry (CV) tests were performed using a CHI660E electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.) within a voltage window of 0-0.6V (scan rate 5-100mV·s). -1 ) and constant current charge-discharge (GCD) test (current density 1-10 A·g) -1 The system evaluates key electrochemical parameters of materials, such as specific capacitance, rate performance, and cycle stability.

[0190] The results are shown in Table 1.

[0191] Table 1

[0192]

[0193] First, as can be seen from Examples 1-8 in Table 1, the nano-carbon capacitor slurry of the present invention has excellent stability (sedimentation rate <0.5%, good fluidity) and electrochemical performance (high specific capacitance, cycle life, high rate performance and low ESR).

[0194] Secondly, as observed in Examples 1 and Comparative Examples 1-3, the graphene structure in the carbon nanomaterials of the present invention's nano-carbon capacitor paste has a positive effect on improving specific capacitance, rate performance, and reducing ESR, and its carboxyl content is highly efficient within a reasonable range. As observed in Examples 1 and Comparative Examples 4-6, the carbon nanotube structure in the present invention's nano-carbon capacitor paste also improves electrochemical performance. As observed in Examples 1 and Comparative Example 7, the MOF material not only improves electrochemical performance but also promotes the dispersion of graphene and carbon nanotubes, enhancing paste stability. As observed in Examples 1 and Comparative Examples 8-9, graphene / carbon nanotubes improve electrochemical performance, with even better performance within a suitable range. As can be observed from Examples and Comparative Examples 1-9, the nano-carbon capacitor paste of the present invention exhibits excellent stability and electrochemical performance. This is because: the nano-carbon material is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite structure, in which the graphene sheets, carbon nanotube axes, and MOF form a continuous three-dimensional spatial network structure of points-lines-surfaces, exhibiting high electron mobility efficiency and low interfacial impedance; the MOF structure has high charge storage capacity; the graphene sheets provide protection, and the carbon nanotubes absorb lattice stress, etc. The graphene / carbon nanotube / MOF structure synergistically enhances the electrochemical performance, and the MOF structure is completely dispersed between the graphene layers and on the surface of the nanotubes, effectively inhibiting their aggregation and improving stability.

[0195] As can be observed from Examples 1 and Comparative Examples 10-13, the composite binder in the nano-carbon capacitor slurry of the present invention has anti-settling, conductive, and thickening effects, which positively contribute to improving the stability and electrical properties of the slurry. This is because sulfonated polyaniline has a conductive polymer structure and is conductive; the sulfonic acid groups in sulfonated polyaniline and the carboxyl groups in carboxymethyl cellulose can form hydrogen bonds with the oxygen-containing functional groups in carbon nanomaterials or coordinate bonds with active metal sites, thus exhibiting anti-settling and thickening effects.

[0196] In summary, the nano-carbon capacitor paste provided by this invention effectively solves the problems of poor electrochemical performance such as short cycle life and low specific capacitance during long-term use of nano-carbon capacitor paste, and has great application potential.

[0197] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A nano-carbon capacitor paste, characterized in that, Based on 100 parts by weight, it comprises the following components: 18-22 parts of nano-carbon material; 3-6 parts adhesive; Deionized water balance; The nano-carbon material is a graphene-carbon nanotube dual-carbon network / crystalline MOF composite material. The nano-carbon material is prepared according to the following method: S1: Carbon nanotubes are oxidized to obtain product I; The carboxyl content in product I is 2.5-3.0 wt%; S2: Oxidize the graphene to obtain product II; The carboxyl content in product II is 5.0-5.5 wt%; S3: Using product I, product II, metal salt, and organic ligand as raw materials, a solvothermal reaction is carried out to obtain nano-carbon materials; The molar ratio of the metal salt to the organic ligand is (2-4):1; The mass ratio of product I to product II is 1:(1-2). The ratio of the total mass of product I and product II to the total mass of the metal salt and the organic ligand is (0.2-0.5):1; as well as The adhesive is a composite adhesive composed of sulfonated polyaniline and carboxymethyl cellulose in a mass ratio of (0.7-0.9):(0.1-0.3).

2. The nano-carbon capacitor paste as described in claim 1, characterized in that, The metal salt is selected from at least one of copper salt, zinc salt, nickel salt, and cobalt salt.

3. The nano-carbon capacitor paste as described in claim 1, characterized in that, The organic ligand is selected from at least one of terephthalic acid, 1,3,5-benzenetricarboxylic acid, 2,5-dihydroxyterephthalic acid, pyromellitic acid, and citric acid.

4. An electrode, characterized in that, Includes the nano-carbon capacitor paste as described in any one of claims 1-3.

5. A supercapacitor, characterized in that, Includes the electrode as described in claim 4.

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