A dispersing agent for conductive paste and a method for preparing the same

Abstract

The application belongs to the technical field of dispersants, and relates to a dispersant for conductive slurry and a preparation method thereof. The dispersant for conductive slurry is a copolymer prepared through step-by-step free radical polymerization. First, two functional monomers, naphthothiophene acrylic anhydride with a double bond and imidazole ethyl acrylate, are synthesized, then the two functional monomers are copolymerized, and finally, the copolymer is copolymerized with acrylic acid, methyl methacrylate and butyl acrylate to obtain a target product. The target product has both a naphthothiophene large pi conjugate plane and an imidazole nitrogen heterocyclic coordination group, can be synergistically anchored on the surface of conductive materials through strong pi-pi adsorption and coordination, and can significantly enhance the adsorption strength. Meanwhile, the alkyl acrylate segments in the polymer main chain are fully stretched in the solvent, providing excellent steric hindrance effect, preventing the agglomeration and sedimentation of conductive particles, and improving the dispersion stability and uniformity of the slurry. The preparation method is simple, and the prepared dispersant is suitable for carbon nanometer conductive slurry.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of dispersants, and particularly relates to a dispersant for conductive slurry and a preparation method thereof. BACKGROUND

[0002] At present, the conductive slurry for electrodes is mainly composed of conductive fillers, dispersion media and dispersants. The conductive fillers mainly include conductive carbon black, carbon nanotubes and graphene and other nanocarbon materials. These nanoscale conductive fillers with high specific surface area are prone to agglomeration, and need to rely on dispersion technology to build a stable and efficient conductive network.

[0003] The current dispersion methods mainly include physical and chemical methods: the physical method destroys the agglomerates through high-speed stirring, ultrasonic treatment, ball milling and other mechanical energy, which is simple to operate but has high energy consumption and is difficult to maintain long-term dispersion stability; the chemical method adds dispersants such as surfactants and amphoteric ion polymers, and realizes the stable dispersion of the conductive slurry by using electrostatic repulsion, steric hindrance or the amphoteric affinity effect of polar and nonpolar groups.

[0004] However, the existing dispersants still have significant defects: on the one hand, the traditional dispersant molecular structure has insufficient affinity with carbon nanomaterials, resulting in easy sedimentation or gelation of the dispersion system; on the other hand, excessive or improper dispersants may wrap the conductive particles, and the insulating groups thereof may block the electron transmission channel, thereby deteriorating the intrinsic conductivity of the slurry. Although polyvinylpyrrolidone, which is most commonly used in industry, can adsorb carbon materials through pyrrolidone rings, the carbon-oxygen five-membered ring in the molecule thereof will undergo ring-opening decomposition under high voltage and high temperature, resulting in the failure of the key “anchor point”, the rapid decrease of the binding force between PVP and active substances, and the significant deterioration of dispersion stability. Chinese Patent CN110436443A uses poly(ethylene glycol) phenyl ether acrylate and poly(ethylene glycol) methyl ether acrylate, which can play a dispersing role in water and organic solvents, but the single phenyl group has insufficient affinity with carbon nanomaterials, which is prone to cause desorption; Chinese Patent CN109867776A improves the adsorption capacity of the carbon nanotube high-efficiency dispersant on the surface of carbon nanotubes by introducing multiple aromatic rings and double polyether chains, but the insulating groups thereof may affect the conductivity of the conductive slurry. Therefore, it is an urgent need to develop a new type of dispersant with high carbon material affinity, conductivity compatibility and high-voltage stability to improve the performance of batteries. SUMMARY

[0005] The present application aims to provide a dispersant for conductive slurry and a preparation method thereof to solve the above technical problems.

[0006] To achieve the above technical purposes, the technical scheme of the present application is as follows:

[0007] The present application provides a preparation method of a dispersant for conductive slurry, which comprises the following steps:

[0008] S1, dissolve naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate in anhydrous toluene, add azobisisobutyronitrile as initiator, deoxygenate with nitrogen, heat to 60~70℃, slowly stir for 2h to obtain a reaction solution;

[0009] S2, add acrylic acid and acrylate to the reaction solution, add azobisisobutyronitrile as initiator, deoxygenate with nitrogen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add n-hexane solution, stir until precipitation occurs, suction filtration, collect the precipitate, wash with n-hexane, vacuum dry for 24h to obtain a dispersant for conductive paste.

[0010] As a further improvement, in step S1, the preparation method of the naphthothiophene-2-acrylic anhydride comprises the following steps: dissolve naphthothiophene-2-carboxylic acid in anhydrous tetrahydrofuran, add hydroquinone, stir to dissolve uniformly; add triethylamine, stir at room temperature for 5min, deoxygenate with nitrogen for 40min; slowly add acryloyl chloride at 0~5℃, continue to react for 1~2h after the addition is completed, filter, collect the filtrate, evaporate and concentrate, recrystallize with toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride.

[0011] As a further improvement, in step S1, the preparation method of the imidazole ethyl acrylate comprises the following steps: dissolve 1-(2-hydroxyethyl)imidazole in anhydrous tetrahydrofuran, add hydroquinone, stir to dissolve uniformly; add triethylamine, stir at room temperature for 5min, deoxygenate with nitrogen for 40min, slowly add acryloyl chloride at 0~5℃, continue to react for 1~2h after the addition is completed, filter, collect the filtrate, evaporate and concentrate, recrystallize with toluene and petroleum ether to obtain imidazole ethyl acrylate.

[0012] As a further improvement, in step S1, the mass ratio of naphthothiophene-2-acrylic anhydride to imidazole ethyl acrylate is 1:1~1.5, and the mass of azobisisobutyronitrile is 2% of the total mass of naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate.

[0013] As a further improvement, the molar ratio of naphthothiophene-2-carboxylic acid, acryloyl chloride and triethylamine is 1:1~1.2:1~1.3, and the mass of hydroquinone is 1% of the mass of naphthothiophene-2-carboxylic acid.

[0014] As a further improvement, the molar ratio of 1-(2-hydroxyethyl)imidazole, acryloyl chloride and triethylamine is 1:1~1.2:1~1.3, and the mass of hydroquinone is 1% of the mass of 1-(2-hydroxyethyl)imidazole.

[0015] As a further improvement, the acrylate is a mixture of methyl methacrylate and butyl acrylate; the mass ratio of the acrylate, the methyl methacrylate and the butyl acrylate is 1:3-5:6-8; the total mass ratio of the acrylate, the methyl methacrylate and the butyl acrylate to the naphthothiophene-2-acryloyl anhydride and the imidazole ethyl acrylate is 2:1; the mass of the azobisisobutyronitrile is 2% of the total mass of the acrylate, the methyl methacrylate and the butyl acrylate.

[0016] A dispersant for conductive slurry, the structural general formula of the dispersant is:

[0017] ;

[0018] Wherein, R1 is a long polymerization chain after the double bond polymerization reaction of acrylic acid, butyl acrylate and methyl methacrylate; m and n are the polymerization degree, m=1-15; n=1-20.

[0019] Due to the adoption of the above technical solution, the application has the following beneficial effects:

[0020] The dispersant for conductive slurry provided by the application uses naphthothiophene and imidazole groups as double-anchor point branches. Compared with a single benzene ring or a single naphthalene ring, naphthothiophene has a larger and more rigid planar conjugated structure, resulting in stronger and more matched pi-pi interactions; the anhydride bond and the ester bond provide flexibility, enabling the imidazole group and the naphthalene ring to undergo intramolecular pi-pi stacking to generate a compact and rigid composite aromatic nucleus, so that the dispersant can quickly and powerfully complete adsorption when contacting carbon nanomaterials, and is difficult to be desorbed or replaced, thereby providing excellent thermodynamic stability for the dispersion system. The sulfur atom introduced in the thiophene ring not only participates in conjugation, but also provides lone pair electrons as a weak electron donor, which produces additional interactions or weak coordination with defects or trace functional groups on the surface of the conductive material. Moreover, the electron cloud delocalization of the naphthothiophene unit is much better than that of a single naphthalene or thiophene, and its intramolecular charge transport capacity is stronger. The thiophene ring and the naphthalene ring cooperate to reduce the charge transport energy barrier of the contact interface with carbon nanomaterials, form a more efficient charge transport channel, greatly reduce the resistance, and exhibit higher electrical conductivity.

[0021] The methyl methacrylate and the butyl acrylate added in the dispersant for conductive slurry provided by the application provide rigid and flexible structures for the polymerization chain, the carboxyl group in the acrylate provides hydrophilicity for the polymerization chain, and the hydrocarbon group structure provides hydrophobicity for the polymerization chain, so that the dispersant can make the nanocarbon material well dispersed in the aqueous phase and the organic solvent phase, and inhibit the agglomeration of the conductive nanocarbon particles.

[0022] The dispersant uses naphthalene ring, thiophene and imidazole to form a strong adsorption to the conductive paste, and uses acrylic acid and acrylate to adjust the hydrophilic and hydrophobic properties, so that the conductive paste has the properties of higher thermal stability, lower resistance and higher voltage resistance. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 ATR-FTIR image of the dispersant for the conductive paste prepared in Example 1;

[0024] Figure 2 Actual picture of the carbon nanotube mixed solution containing the dispersant for the conductive paste of Example 1 and Comparative Example 1 after standing for 30 days;

[0025] Figure 3 Particle size distribution result graph of the carbon nanotube containing the dispersant for the conductive paste of Example 1;

[0026] Figure 4 Particle size distribution result graph of the carbon nanotube containing the dispersant for the conductive paste of Comparative Example 1. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described in detail below in conjunction with the specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application. The specific conditions are not specified in the examples, which are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, which are conventional products that can be purchased on the market.

[0028] Example 1 A preparation method of a dispersant for a conductive paste, specifically comprising the following steps:

[0029] S1, 20 g of naphthothiophene-2-carboxylic acid is dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone is added, and it is stirred to dissolve uniformly; 8.78 g of triethylamine is added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 7.86 g of acryloyl chloride is slowly added dropwise at 0℃, after the addition is completed, continue to stir, react for 1 h, filter, collect the filtrate, concentrate on a rotary evaporator, recrystallize with toluene and petroleum ether, and obtain naphthothiophene-2-acrylate; the specific reaction equation is as follows:

[0030] ;

[0031] S2, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was stirred to be uniformly dissolved; 18.04 g of triethylamine was added, and it was stirred at room temperature for 5 min, and deoxygenated for 40 min, and 16.14 g of acryloyl chloride was slowly added dropwise at 0°C, and after the addition was completed, it was continuously stirred, and reacted for 1 h, and the product was filtered, and the filtrate was concentrated on a rotary evaporator, and recrystallized using toluene and petroleum ether, and imidazole ethyl acrylate was obtained; the specific reaction equation is as follows:

[0032] ;

[0033] S3, 5 g of naphthothiophene-2-propylene anhydride and 5 g of imidazole ethyl acrylate were dissolved in 50 mL of anhydrous toluene, 0.2 g of azobisisobutyronitrile was added as an initiator, and deoxygenated for 40 min, and the temperature was increased to 60°C, and slowly stirred for 2 h to obtain a reaction liquid; the specific reaction equation is as follows:

[0034] ;

[0035] wherein m and n are the polymerization degree, m = 1 ~ 15; n = 1 ~ 20;

[0036] S4, 2 g of acrylic acid, 6 g of methyl methacrylate, and 12 g of butyl acrylate were added to the reaction liquid, 0.4 g of azobisisobutyronitrile was added as an initiator, and deoxygenated for 40 min, and reacted at 70°C for 4 h, and cooled to room temperature under nitrogen protection, and the reaction liquid was added to a n-hexane solution, and stirred until precipitation occurred, and suction filtered, and the precipitate was collected, and washed using n-hexane, and placed in a vacuum drying box, and dried for 24 h to obtain a dispersant for conductive paste; the specific reaction equation is as follows:

[0037] ;

[0038] wherein R1 is a polymerization chain formed after the double bond polymerization reaction of acrylic acid, butyl acrylate, and methyl methacrylate; m = 1 ~ 15; n = 1 ~ 20;

[0039] The ATR-FTIR graph of the dispersant for conductive paste prepared in this example is shown in FIG. 1. Figure 1

[0040] Example 2 A method for preparing a dispersant for conductive paste, specifically comprising the following steps:

[0041] ​S1, 20 g of naphthothiophene-2-carboxylic acid was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 11.42 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 9.43 g of acryloyl chloride was slowly added dropwise at 3°C, after the addition was completed, the reaction was continued for 2 h, filtration was performed, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and naphthothiophene-2-acrylic anhydride was obtained;

[0042] S2, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 23.46 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min, 19.37 g of acryloyl chloride was slowly added dropwise at 3°C, after the addition was completed, the reaction was continued for 2 h, the product was filtered, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and imidazole ethyl acrylate was obtained;

[0043] S3, 4 g of naphthothiophene-2-acrylic anhydride and 6 g of imidazole ethyl acrylate were dissolved in 50 mL of anhydrous toluene, 0.2 g of azobisisobutyronitrile was added as an initiator, deoxygenated by nitrogen for 30 min, and the temperature was raised to 70°C. Slowly stir for 2 h to obtain a reaction solution;

[0044] S4, 1.42 g of acrylic acid, 7.15 g of methyl methacrylate, and 11.43 g of butyl acrylate were added to the reaction solution, 0.4 g of azobisisobutyronitrile was added as an initiator, deoxygenated by nitrogen for 30 min, and reacted at 70°C for 4 h. Cool to room temperature under nitrogen protection, add the reaction solution to a n-hexane solution, stir until precipitate appears, suction filter, collect the precipitate, wash with n-hexane, and place in a vacuum drying box for 24 h to obtain a dispersant for conductive paste.

[0045] Example 3 A method for preparing a dispersant for conductive paste, specifically comprising the following steps:

[0046] S1, 20 g of naphthothiophene-2-carboxylic acid was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 9.66 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 8.64 g of acryloyl chloride was slowly added dropwise at 0°C, after the addition was completed, the reaction was continued for 1 h, filtration was performed, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and naphthothiophene-2-acrylic anhydride was obtained;

[0047] S2, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 19.85 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 17.75 g of acryloyl chloride was slowly added dropwise at 0°C, and after the addition was completed, the reaction was continued for 1 h; the product was filtered, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and imidazole ethyl acrylate was obtained;

[0048] S3, 5 g of naphthothiophene-2-acrylic anhydride and 6.5 g of imidazole ethyl acrylate were dissolved in 50 mL of anhydrous toluene, 0.23 g of azobisisobutyronitrile was added as an initiator, deoxygenated by nitrogen for 30 min, warmed to 65°C, and slowly stirred for 2 h to obtain a reaction solution;

[0049] S4, 1.91 g of acrylic acid, 7.67 g of methyl methacrylate, and 13.42 g of butyl acrylate were added to the reaction solution, 0.46 g of azobisisobutyronitrile was added as an initiator, deoxygenated by nitrogen for 30 min, and reacted at 70°C for 4 h; cooled to room temperature under nitrogen protection, the reaction solution was added to a n-hexane solution, stirred until precipitation occurred, suction filtered, the precipitate was collected, washed with n-hexane, and placed in a vacuum drying box for drying for 24 h to obtain a dispersant for conductive paste.

[0050] Example 4 A method for preparing a dispersant for conductive paste, specifically comprising the following steps:

[0051] S1, 20 g of naphthothiophene-2-carboxylic acid was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 10.54 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 9.43 g of acryloyl chloride was slowly added dropwise at 3°C, and after the addition was completed, the reaction was continued for 2 h; filtered, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and naphthothiophene-2-acrylic anhydride was obtained;

[0052] S2, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 21.65 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 19.37 g of acryloyl chloride was slowly added dropwise at 3°C, and after the addition was completed, the reaction was continued for 2 h; the product was filtered, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and imidazole ethyl acrylate was obtained;

[0053] S3, 5 g of naphthothiophene-2-acrylic anhydride and 5 g of imidazole ethyl acrylate were dissolved in 50 mL of anhydrous toluene, 0.2 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 40 min, the temperature was raised to 70°C, and the reaction was slowly stirred for 2 h to obtain a reaction solution;

[0054] S4, 1.42 g of acrylic acid, 7.15 g of methyl methacrylate and 11.43 g of butyl acrylate were added to the reaction solution, 0.4 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 40 min, and the reaction was carried out at 70°C for 4 h. The reaction solution was cooled to room temperature under nitrogen protection, added to a n-hexane solution, stirred until precipitation occurred, suction filtered, the precipitate was collected, washed with n-hexane, and placed in a vacuum drying box for drying for 24 h to obtain a dispersant for conductive paste.

[0055] Example 5 A preparation method of a dispersant for conductive paste, specifically comprising the following steps:

[0056] S1, 20 g of naphthothiophene-2-carboxylic acid was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added and stirred to dissolve uniformly; 8.78 g of triethylamine was added, stirred at room temperature for 5 min, and nitrogen was blown for 40 min; 7.86 g of acryloyl chloride was slowly added at 5°C, and after the addition was completed, the reaction was continued for 1 h, filtered, the filtrate was concentrated on a rotary evaporator, and recrystallized with toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride;

[0057] S2, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added and stirred to dissolve uniformly; 18.04 g of triethylamine was added, stirred at room temperature for 5 min, and nitrogen was blown for 40 min; 16.14 g of acryloyl chloride was slowly added at 5°C, and after the addition was completed, the reaction was continued for 1 h, the product was filtered, the filtrate was concentrated on a rotary evaporator, and recrystallized with toluene and petroleum ether to obtain imidazole ethyl acrylate;

[0058] S3, 5 g of naphthothiophene-2-acrylic anhydride and 6.5 g of imidazole ethyl acrylate were dissolved in 50 mL of anhydrous toluene, 0.23 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 30 min, the temperature was raised to 60°C, and the reaction was slowly stirred for 2 h to obtain a reaction solution;

[0059] S4, 2.3 g of acrylic acid, 6.9 g of methyl methacrylate and 13.8 g of butyl acrylate were added to the reaction solution, 0.46 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 30 min to remove oxygen, and the reaction was carried out at 70°C for 4 h. The reaction solution was cooled to room temperature under nitrogen protection, added to a n-hexane solution, stirred until precipitation occurred, suction filtered, the precipitate was collected, washed with n-hexane, placed in a vacuum drying oven, and dried for 24 h to obtain a dispersant for conductive paste.

[0060] Comparative Example 1: A method for preparing a dispersant for conductive paste, which is different from Example 1 in that the dispersant is a commonly used industrial dispersant polyvinylpyrrolidone (PVP).

[0061] Comparative Example 2: A method for preparing a dispersant for conductive paste, which is different from Example 1 in that the reaction process does not include naphthothiophene-2-acryloyl anhydride, and specifically includes the following steps:

[0062] S1, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added and stirred to dissolve uniformly; 18.04 g of triethylamine was added, stirred at room temperature for 5 min, and nitrogen was blown for 40 min to remove oxygen. At 0°C, 16.14 g of acryloyl chloride was slowly added dropwise, and after the addition was completed, the reaction was continued for 1 h. The product was filtered, the filtrate was concentrated on a rotary evaporator, and recrystallized with toluene and petroleum ether to obtain imidazole ethyl acrylate;

[0063] S2, 10 g of imidazole ethyl acrylate was dissolved in 50 mL of anhydrous toluene, 0.2 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 40 min to remove oxygen, and the temperature was raised to 60°C. Slowly stirred for 2 h to obtain a reaction solution;

[0064] S3, 2 g of acrylic acid, 6 g of methyl methacrylate and 12 g of butyl acrylate were added to the reaction solution, 0.4 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 40 min to remove oxygen, and the reaction was carried out at 70°C for 4 h. The reaction solution was cooled to room temperature under nitrogen protection, added to a n-hexane solution, stirred until precipitation occurred, suction filtered, the precipitate was collected, washed with n-hexane, placed in a vacuum drying oven, and dried for 24 h to obtain a dispersant for conductive paste.

[0065] Comparative Example 3: A method for preparing a dispersant for conductive paste, which is different from Example 1 in that the reaction process does not include imidazole ethyl acrylate, and specifically includes the following steps:

[0066] S1, 20 g of naphthothiophene-2-carboxylic acid was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 8.78 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 7.86 g of acryloyl chloride was slowly added dropwise at 0°C, after the addition was completed, the reaction was continued for 1 h, filtration was performed, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and naphthothiophene-2-acrylic anhydride was obtained;

[0067] S2, 10 g of naphthothiophene-2-acrylic anhydride was dissolved in 50 mL of anhydrous toluene, 0.2 g of azobisisobutyronitrile was added as an initiator, deoxygenated by nitrogen, and heated to 60°C; slowly stirred for 2 h to obtain a reaction solution;

[0068] S3, 2 g of acrylic acid, 6 g of methyl methacrylate and 12 g of butyl acrylate were added to the reaction solution, 0.4 g of azobisisobutyronitrile was added as an initiator, deoxygenated by nitrogen for 40 min, and reacted at 70°C for 4 h; cooled to room temperature under nitrogen protection, the reaction solution was added to a n-hexane solution, stirred until precipitation occurred, the precipitate was collected by suction filtration, washed with n-hexane, and placed in a vacuum drying box for drying for 24 h to obtain a dispersant for conductive paste.

[0069] Comparative Example 4: A method for preparing a dispersant for conductive paste, which is different from Example 1 in that the reaction process does not include acrylic acid and methyl methacrylate, and specifically includes the following steps:

[0070] S1, 20 g of naphthothiophene-2-carboxylic acid was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 8.78 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 7.86 g of acryloyl chloride was slowly added dropwise at 0°C, after the addition was completed, the reaction was continued for 1 h, filtration was performed, the filtrate was collected, concentrated on a rotary evaporator, recrystallized with toluene and petroleum ether, and naphthothiophene-2-acrylic anhydride was obtained;

[0071] S2, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added, and it was uniformly dissolved by stirring; 18.04 g of triethylamine was added, stirred at room temperature for 5 min, and deoxygenated by nitrogen for 40 min; 16.14 g of acryloyl chloride was slowly added dropwise at 0°C, after the addition was completed, the reaction was continued for 1 h, the product was filtered, the filtrate was collected, concentrated on a rotary evaporator, and recrystallized with toluene and petroleum ether to obtain imidazole ethyl acrylate;

[0072] S3, 5 g naphthothiophene-2-propenoic anhydride and 5 g imidazole ethyl acrylate were dissolved in 50 mL anhydrous toluene, 0.2 g azobisisobutyronitrile was added as an initiator, deoxygenated for 40 min, heated to 60 °C, slowly stirred for 2 h, and a reaction solution was obtained;

[0073] S4, 20 g butyl acrylate was added to the reaction solution, 0.4 g azobisisobutyronitrile was added as an initiator, deoxygenated for 40 min, reacted at 70 °C for 4 h, cooled to room temperature under nitrogen protection, the reaction solution was added to a n-hexane solution, stirred until precipitation appeared, the precipitate was collected by suction filtration, washed with n-hexane, and placed in a vacuum drying box for drying for 24 h, and a dispersant for conductive paste was obtained.

[0074] Comparative Example 5: A preparation method of a dispersant for conductive paste, which is different from Example 1 in that the polymerization reaction process does not include naphthothiophene-2-propenoic anhydride, i.e., the obtained copolymer product does not contain naphthothiophene-2-propenoic anhydride component, but the naphthothiophene-2-propenoic anhydride is mixed with the copolymer product to prepare a conductive paste dispersant, which specifically includes the following steps:

[0075] S1, 20 g naphthothiophene-2-carboxylic acid was dissolved in 100 mL anhydrous tetrahydrofuran, 0.2 g hydroquinone was added and stirred to uniformly dissolve; 8.78 g triethylamine was added, stirred at room temperature for 5 min, deoxygenated for 40 min; 7.86 g acryloyl chloride was slowly added at 0 °C, after the addition was completed, the reaction was continued for 1 h, filtration was performed, the filtrate was concentrated on a rotary evaporator, and recrystallization was performed using toluene and petroleum ether to obtain naphthothiophene-2-propenoic anhydride;

[0076] S2, 20 g 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL anhydrous tetrahydrofuran, 0.2 g hydroquinone was added and stirred to uniformly dissolve; 18.04 g triethylamine was added, stirred at room temperature for 5 min, deoxygenated for 40 min, 16.14 g acryloyl chloride was slowly added at 0 °C, after the addition was completed, the reaction was continued for 1 h, the product was filtered, the filtrate was concentrated on a rotary evaporator, and recrystallization was performed using toluene and petroleum ether to obtain imidazole ethyl acrylate;

[0077] S3, 10 g imidazole ethyl acrylate was dissolved in 50 mL anhydrous toluene, 0.2 g azobisisobutyronitrile was added as an initiator, deoxygenated for 40 min, heated to 60 °C, slowly stirred for 2 h, and a reaction solution was obtained;

[0078] S4, 2 g of acrylic acid, 6 g of methyl methacrylate and 12 g of butyl acrylate were added to the reaction solution, 0.4 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 40 min to remove oxygen, and the reaction was carried out at 70°C for 4 h. The reaction solution was cooled to room temperature under nitrogen protection, added to a n-hexane solution, stirred until precipitation occurred, the precipitate was collected by suction filtration, washed with n-hexane, placed in a vacuum drying oven, and dried for 24 h to obtain a copolymer product;

[0079] S5, 6 g of the copolymer product was mixed with 1 g of naphthothiophene-2-acrylic anhydride to obtain a dispersant for conductive paste.

[0080] Comparative Example 6: A method for preparing a dispersant for conductive paste, which is different from Example 1 in that naphthothiophene-2-acrylic anhydride is replaced by 1-allylnaphthalene, and specifically comprising the following steps:

[0081] S1, 20 g of 1-(2-hydroxyethyl)imidazole was dissolved in 100 mL of anhydrous tetrahydrofuran, 0.2 g of hydroquinone was added and stirred until it was uniformly dissolved; 18.04 g of triethylamine was added, stirred at room temperature for 5 min, and nitrogen was blown for 40 min to remove oxygen. At 0°C, 16.14 g of acryloyl chloride was slowly added dropwise, and after the addition was completed, the reaction was continued for 1 h. The product was filtered, the filtrate was concentrated on a rotary evaporator, and recrystallized with toluene and petroleum ether to obtain imidazole ethyl acrylate;

[0082] S2, 5 g of imidazole ethyl acrylate and 5 g of 1-allylnaphthalene were dissolved in 50 mL of anhydrous toluene, 0.2 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 40 min to remove oxygen, and the temperature was raised to 60°C. Slowly stir for 2 h to obtain a reaction solution;

[0083] S3, 2 g of acrylic acid, 6 g of methyl methacrylate and 12 g of butyl acrylate were added to the reaction solution, 0.4 g of azobisisobutyronitrile was added as an initiator, nitrogen was blown for 40 min to remove oxygen, and the reaction was carried out at 70°C for 4 h. The reaction solution was cooled to room temperature under nitrogen protection, added to a n-hexane solution, stirred until precipitation occurred, the precipitate was collected by suction filtration, washed with n-hexane, placed in a vacuum drying oven, and dried for 24 h to obtain a dispersant for conductive paste.

[0084] Performance test:

[0085] The dispersants for conductive paste prepared in Examples 1-5 and Comparative Examples 1-6 were mixed with carbon nanotubes, N-methyl pyrrolidone in a mass ratio of 1:5:94, stirred uniformly, and then ultrasonic treated for 30 min to obtain a conductive paste containing a dispersant. The prepared conductive paste containing a dispersant was used for testing.

[0086] (1) Dispersion effect test:

[0087] The viscosity of the conductive paste containing the dispersant was tested using a viscometer at a temperature of 25°C and a rotation speed of 30 rpm. The smaller the viscosity of the conductive paste, the better the dispersing performance. The test results are shown in Table 1.

[0088] The prepared conductive paste containing the dispersant was placed in a glass bottle and placed in a 50°C oven for constant temperature standing. The time for stratification to occur was observed. The longer the time, the better the dispersing performance of the dispersant on the conductive paste. The test results are shown in Table 1. The actual pictures of the conductive paste prepared by the dispersants of Example 1 and Comparative Example 1 after 30 days of standing are shown in FIG. 1, where FIG. (a) is the conductive paste prepared by Example 1, and FIG. (b) is the conductive paste prepared by Comparative Example 1. Figure 2

[0089] Table 1. Test results of dispersing effect of conductive paste

[0090] ;

[0091] As can be seen from Table 1, the time for stratification to occur of the conductive paste prepared by the dispersants of Examples 1-5 is significantly later than that of the conductive paste prepared by the dispersants of the comparative examples, indicating that the dispersants prepared by the preparation method of the present application can maintain the dispersing performance of carbon nanotubes for a longer time and have good dispersing properties.

[0092] As can be seen from Table 1, the dispersing stability of the dispersants of Comparative Examples 2 and 3 is lower than that of Example 1. Because Comparative Example 2 does not add a naphthothiophene group, and Comparative Example 3 does not add an imidazole group, the naphthalene group and the imidazole group cannot perform intramolecular π-π stacking, thereby failing to form a strong adsorption on the carbon nanotubes, affecting the dispersing stability of the carbon nanotubes, indicating that the two groups can synergistically achieve the best dispersing effect. The dispersing stability of Comparative Example 5 is also significantly lower than that of Example 1, which may be because the naphthalene group and the imidazole group are not connected to the same molecular structure, resulting in the naphthalene group and the imidazole group failing to smoothly perform intramolecular π-π stacking, thereby failing to strongly adsorb on the carbon nanotubes, resulting in poor dispersing stability. The dispersing stability of the dispersant of Comparative Example 6 is also significantly lower than that of Example 1, because Comparative Example 6 does not add a thiophene group structure, which cannot synergize with the naphthalene group to form a strong adsorption layer through chemical adsorption and physical adsorption, and cannot exhibit good dispersing performance, indicating that the naphthalene group and the thiophene group linked to the same molecule can exhibit good dispersing stability. The dispersing stability of the dispersant of Comparative Example 4 is lower than that of Example 1, because the copolymerization of acrylic acid, methyl methacrylate, and butyl acrylate is used as a long-chain structure to regulate the spatial conformation and steric effect of the dispersant molecules, to obtain the optimal spatial stability effect, while the use of butyl acrylate alone does not have this ability, and cannot have the best dispersing effect.

[0093] ​(2) DLS particle size distribution test:

[0094] The conductive paste containing the dispersant of Example 1 and Comparative Example 1 was detected using a nanoparticle size analyzer under the temperature condition of 25°C, and the test results are shown in Figure 3 and Figure 4 . Figure 3 The particle size distribution graph of the conductive paste containing the dispersant of Example 1 is Figure 4 , and the particle size distribution graph of the conductive paste containing the dispersant of Comparative Example 1 is Figure 3 and Figure 4 . As can be seen from and

[0095] , the particle size of the conductive paste containing the dispersant of Example 1 is smaller than that of the conductive paste containing the dispersant of Comparative Example 1, and there is no large particle, and the distribution width is also significantly smaller than that of Comparative Example 1, indicating that the dispersing performance of the dispersant for the conductive paste prepared by the preparation method of the present application is better than that of the commonly used dispersant PVP.

[0096] Preparation of a blank control: carbon nanotubes and N-methyl pyrrolidone were mixed uniformly according to a mass ratio of 1:19, and ultrasonic treatment was performed for 30 min to obtain carbon nanometer conductive paste without dispersant.

[0097] The prepared carbon nanometer conductive paste containing dispersant and the carbon nanometer conductive paste without dispersant were respectively coated on a glass substrate, and cured at 120°C for 30 min. A four-probe resistance tester was used to measure the resistance change. Taking the resistance of the carbon nanometer conductive paste without dispersant as the benchmark, the resistance change percentage of the conductive paste containing dispersant was calculated. If the resistance change amplitude is less than 10%, it indicates that the dispersant does not affect the performance of the conductive paste. The test results are shown in Table 2.

[0098] Table 2 Test results of resistance change of conductive paste

[0099] ;

[0100] As can be seen from Table 2, the resistance change of Example 1 is less than that of the comparative examples, indicating that the dispersant prepared by the preparation method of the present application basically does not affect the conductive performance of the conductive paste. The dispersant of Comparative Example 1 has a large effect on the resistance of the conductive paste due to the insulating property of its molecular structure; from the results of Comparative Examples 2, 3 and 6, it can be concluded that the naphthothiophene structure can enhance the conductive performance of the dispersant, because the naphthothiophene structure has a highly delocalized π conjugated system, and electrons can move relatively freely therein, so it can not affect the resistance of the conductive paste.

[0101] (4) Voltage resistance and cycle performance test:

[0102] The prepared carbon nanometer conductive paste containing dispersant was mixed with the tackifier PVDF according to the mass ratio of 89:11 to obtain a coating paste. The coating paste was coated on a current collector (12 μm thick aluminum foil), and vacuum dried at 110°C to obtain an electrode sheet. The obtained electrode sheet was rolled and sliced, and then assembled into a battery with a lithium sheet in a glove box. The maximum voltage of the battery was tested, and the maximum voltage of the redox peak was recorded. The test results are shown in Table 3.

[0103] The prepared battery was subjected to a cycle performance test, and a 0.5C charge / 0.5C discharge 100 cycle capacity test was performed to calculate the cycle capacity retention rate. The test results are shown in Table 3.

[0104] Table 3: Conductive paste voltage resistance and cycle performance test results

[0105] ;

[0106] As can be seen from Table 3, the redox peak voltage of Examples 1-5 is higher than that of Comparative Examples 1-6, indicating that the dispersant used in the conductive paste prepared by the method of the application can withstand higher voltage and is suitable for high-voltage system batteries. The use of naphthothiophene and imidazole in the application improves the antioxidant decomposition ability of the dispersant molecules themselves, thereby maintaining stability in a high-voltage positive electrode environment and protecting the electrode interface.

[0107] The specific embodiments of the application described above do not constitute a limitation on the scope of protection of the application. Any various other corresponding changes and modifications made in accordance with the technical concept of the application shall be included within the scope of protection of the claims of the application.

Claims

1. A method for producing a dispersant for conductive paste, characterized by, The preparation method comprises the following steps: S1, naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate are dissolved in anhydrous toluene, azobisisobutyronitrile is added as an initiator, nitrogen is blown to remove oxygen, the temperature is raised to 60-70℃, and slow stirring is carried out for 2h to obtain a reaction solution; S2, acrylic acid and acrylate are added to the reaction solution, azobisisobutyronitrile is added as an initiator, nitrogen is blown to remove oxygen, and reaction is carried out at 70℃ for 4h, and then the solution is cooled to room temperature under nitrogen protection, added into n-hexane solution, stirred until precipitation occurs, filtered, collected the precipitate, washed with n-hexane, and vacuum dried for 24h to obtain a dispersant for conductive slurry.

2. The method for producing a dispersant for conductive paste according to claim 1, characterized by, In step S1, the preparation method of the naphthothiophene-2-acrylic anhydride comprises the following steps: naphthothiophene-2-carboxylic acid is dissolved in anhydrous tetrahydrofuran, hydroquinone is added, and stirring is carried out until it is uniformly dissolved; triethylamine is added, stirring is carried out at room temperature for 5min, nitrogen is blown to remove oxygen for 40min; acryloyl chloride is slowly added at 0-5℃, after the addition is completed, reaction is continued for 1-2h, filtration is carried out, the filtrate is collected, concentrated by evaporation, recrystallized with toluene and petroleum ether, and naphthothiophene-2-acrylic anhydride is obtained.

3. The method for preparing the dispersant for conductive paste according to claim 1, characterized in that, In step S1, the preparation method of the imidazole ethyl acrylate comprises the following steps: 1-(2-hydroxyethyl)imidazole is dissolved in anhydrous tetrahydrofuran, hydroquinone is added, and stirring is carried out until it is uniformly dissolved; triethylamine is added, stirring is carried out at room temperature for 5min, nitrogen is blown to remove oxygen for 40min, acryloyl chloride is slowly added at 0-5℃, after the addition is completed, reaction is continued for 1-2h, filtration is carried out, the filtrate is collected, concentrated by evaporation, and recrystallized with toluene and petroleum ether to obtain imidazole ethyl acrylate.

4. The method for preparing the dispersant for conductive paste according to claim 1, characterized in that, In step S1, the mass ratio of the naphthothiophene-2-acrylic anhydride to the imidazole ethyl acrylate is 1:1-1.5, and the mass of the azobisisobutyronitrile is 2% of the total mass of the naphthothiophene-2-acrylic anhydride and the imidazole ethyl acrylate.

5. The method for preparing the dispersant for conductive paste according to claim 2, characterized in that, The molar ratio of the naphthothiophene-2-carboxylic acid, the acryloyl chloride and the triethylamine is 1:1-1.2:1-1.3, and the mass of the hydroquinone is 1% of the mass of the naphthothiophene-2-carboxylic acid.

6. The method for preparing the dispersant for conductive paste according to claim 3, characterized in that, The molar ratio of the 1-(2-hydroxyethyl)imidazole, the acryloyl chloride and the triethylamine is 1:1-1.2:1-1.3, and the mass of the hydroquinone is 1% of the mass of the 1-(2-hydroxyethyl)imidazole.

7. The method for preparing the dispersant for conductive paste according to claim 1, characterized in that, The acrylate is a mixture of methyl methacrylate and butyl acrylate; the mass ratio of the acrylic acid, the methyl methacrylate and the butyl acrylate is 1:3-5:6-8; the total mass of the acrylic acid, the methyl methacrylate and the butyl acrylate to the total mass of the naphthothiophene-2-acrylic anhydride and the imidazole ethyl acrylate is 2:1; and the mass of the azobisisobutyronitrile is 2% of the total mass of the acrylic acid, the methyl methacrylate and the butyl acrylate.

8. The dispersant for conductive slurry prepared by the preparation method according to any one of claims 1-7.

Images