Dispersing agent for conductive slurry and preparation method thereof

Abstract

The invention belongs to the technical field of dispersing agents, and relates to a dispersing agent for conductive paste and a preparation method thereof, the dispersing agent for conductive paste is a copolymer formed by stepwise free radical polymerization; the preparation method comprises the following steps: synthesizing two functional monomers, namely naphthothiophene acrylic anhydride with double bonds and imidazole ethyl acrylate, copolymerizing the two functional monomers, and copolymerizing with acrylic acid, methyl methacrylate and butyl acrylate to obtain a target product. The target product has a naphthothiophene large pi conjugate plane and an imidazole azacyclo coordination group, and can be synergistically anchored on the surface of a conductive material through strong pi-pi adsorption and coordination effects, so that the adsorption strength is remarkably enhanced; meanwhile, an alkyl acrylate chain segment in a polymer main chain fully stretches in a solvent, an excellent steric hindrance effect is provided, agglomeration and sedimentation of conductive particles are prevented, and the dispersion stability and uniformity of the slurry are improved; the preparation method is simple, and the prepared dispersing agent is suitable for carbon nano conductive paste.

Description

Technical Field

[0001] This invention belongs to the field of dispersant technology, specifically relating to a dispersant for conductive pastes and its preparation method. Background Technology

[0002] Currently, conductive pastes for electrodes mainly consist of conductive fillers, dispersion media, and dispersants. Conductive fillers primarily include conductive carbon black, carbon nanotubes, and graphene, among other nanomaterials. These high specific surface area nanoscale conductive fillers are prone to aggregation, necessitating dispersion techniques to construct stable and efficient conductive networks.

[0003] Current dispersion methods mainly include two categories: physical methods and chemical methods. Physical methods use mechanical energy such as high-speed stirring, ultrasonic treatment, and ball milling to break down agglomerates. Although they are easy to operate, they are energy-intensive and difficult to maintain long-term dispersion stability. Chemical methods use dispersants such as surfactants and zwitterionic polymers to achieve stable dispersion of conductive slurries by utilizing electrostatic repulsion, steric hindrance, or the amphoteric affinity effect of polar and nonpolar groups.

[0004] However, existing dispersants still have significant drawbacks: on the one hand, the molecular structure of traditional dispersants has insufficient affinity with carbon nanomaterials, leading to easy sedimentation or gelation of the dispersion system; on the other hand, excessive or inappropriate dispersants may encapsulate conductive particles, and their insulating groups can block electron transport channels, degrading the intrinsic conductivity of the slurry. Although polyvinylpyrrolidone (PVP), the most commonly used industrial dispersant, can adsorb carbon materials through the pyrrolidone ring, the carbon-oxygen five-membered ring in its molecule undergoes ring-opening decomposition under high voltage and high temperature conditions, causing the key "anchor point" to fail, the binding force between PVP and active materials to decrease sharply, and the dispersion stability to deteriorate significantly. 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. However, the monophenyl group has insufficient affinity for carbon nanomaterials, which easily leads to desorption. Chinese patent CN109867776A improves the adsorption capacity of the high-efficiency carbon nanotube dispersant on the surface of carbon nanotubes by introducing multiple aromatic rings and diether chains, but its insulating groups may affect the conductivity of the conductive paste. Therefore, developing novel dispersants that combine high affinity for carbon materials, conductivity compatibility, and high-voltage stability has become an urgent need to improve battery performance. Summary of the Invention

[0005] The purpose of this invention is to provide a dispersant for conductive pastes and its preparation method to solve the above-mentioned technical problems.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows: This invention provides a method for preparing a dispersant for conductive pastes, comprising the following steps: S1. Dissolve naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate in anhydrous toluene, add azobisisobutyronitrile as an initiator, remove oxygen by nitrogen purging, heat to 60~70℃, stir slowly for 2h to obtain the reaction solution. S2. Add acrylic acid and acrylate to the reaction solution, add azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen, react at 70°C for 4 hours, cool to room temperature under nitrogen protection, add n-hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with n-hexane, and vacuum dry for 24 hours to obtain a dispersant for conductive paste.

[0007] As a further improvement, in step S1, the preparation method of the naphthothiophene-2-acrylic anhydride includes the following steps: dissolving naphthothiophene-2-carboxylic acid in anhydrous tetrahydrofuran, adding hydroquinone, and stirring to make it uniformly dissolved; adding triethylamine, stirring at room temperature for 5 min, and purging with nitrogen to remove oxygen for 40 min; slowly adding acryloyl chloride at 0~5℃, and after the addition is completed, continuing the reaction for 1~2 h, filtering, collecting the filtrate, evaporating and concentrating, and recrystallizing with toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride.

[0008] As a further improvement, in step S1, the preparation method of the imidazole ethyl acrylate includes the following steps: dissolving 1-(2-hydroxyethyl)imidazolium in anhydrous tetrahydrofuran, adding hydroquinone, and stirring to make it uniformly dissolved; adding triethylamine, stirring at room temperature for 5 min, purging with nitrogen to remove oxygen for 40 min, slowly adding acryloyl chloride at 0~5℃, continuing the reaction for 1~2 h after the addition is completed, filtering, collecting the filtrate, evaporating and concentrating, and recrystallizing with toluene and petroleum ether to obtain imidazole ethyl acrylate.

[0009] As a further improvement, in step S1, the mass ratio of the naphthothiophene-2-acrylic anhydride to imidazole ethyl acrylate is 1:1 to 1.5, and the mass of azobisisobutyronitrile is 2% of the total mass of the naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate.

[0010] 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.

[0011] As a further improvement, the molar ratio of 1-(2-hydroxyethyl)imidazole, acryloyl chloride and triethylamine is 1:1 to 1.2:1 to 1.3, and the mass of hydroquinone is 1% of the mass of 1-(2-hydroxyethyl)imidazole.

[0012] As a further improvement, the acrylate is a mixture of methyl methacrylate and butyl acrylate; the mass ratio of acrylic acid, methyl methacrylate and butyl acrylate is 1:3~5:6~8; the total mass ratio of acrylic acid, methyl methacrylate and butyl acrylate to the total mass ratio of naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate is 2:1; the mass of the azobisisobutyronitrile is 2% of the total mass of acrylic acid, methyl methacrylate and butyl acrylate.

[0013] A dispersant for conductive pastes, wherein the general structural formula of the dispersant for conductive pastes is: ; Wherein, R1 is the long polymer chain resulting from the double bond polymerization reaction of acrylic acid, butyl acrylate, and methyl methacrylate; m and n are the degrees of polymerization, m=1~15; n=1~20.

[0014] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: This invention provides a dispersant for conductive pastes, using naphthothiophene and imidazole groups as dual-anchored branches. Compared to single benzene or naphthalene rings, naphthothiophene possesses a larger and more rigid planar conjugated structure, generating stronger and more matched π-π interactions. The anhydride and ester bonds provide flexibility, allowing the imidazole group and naphthalene ring to undergo intramolecular π-π stacking, forming a compact and rigid composite aromatic core. This enables the dispersant to rapidly and forcefully adsorb upon contact with carbon nanomaterials, making it difficult to desorb or be replaced, thus providing excellent thermodynamic stability for the dispersion system. Furthermore, the sulfur atom introduced into the thiophene ring not only participates in conjugation but also provides lone pair electrons that act as weak electron donors, generating additional interactions or weak coordination with defects or trace functional groups on the conductive material surface. Moreover, the electron cloud delocalization of the naphthothiophene unit is far superior to that of single naphthalene or thiophene, resulting in stronger intramolecular charge transport capabilities. The synergistic effect of the thiophene ring and the naphthalene ring can lower the charge transport barrier at the interface with carbon nanomaterials, forming a more efficient charge transport channel, which greatly reduces the resistance and exhibits higher conductivity.

[0015] The methyl methacrylate and butyl acrylate added to the dispersant for the conductive paste provided by this invention provide a rigid and flexible structure for the polymer chain. The carboxyl group in acrylic acid provides hydrophilicity to the polymer chain, and the hydrocarbon group provides hydrophobicity to the polymer chain. This allows the dispersant to effectively disperse the nano-carbon material in both the aqueous phase and the organic solvent phase, and inhibits the agglomeration of conductive nano-carbon particles.

[0016] This dispersant uses the synergistic effect of naphthalene ring, thiophene and imidazole to form a strong adsorption to conductive paste. It uses acrylic acid and acrylate to adjust the hydrophilicity and hydrophobicity, so that the conductive paste has higher thermal stability, lower resistance and higher withstand voltage. Attached Figure Description

[0017] Figure 1 ATR-FTIR image of the dispersant for the conductive paste prepared in Example 1; Figure 2 A photograph of a carbon nanotube mixture containing the dispersant for conductive pastes of Example 1 and Comparative Example 1, after standing for 30 days. Figure 3 The particle size distribution of carbon nanotubes containing the dispersant for the conductive paste of Example 1 is shown in the figure. Figure 4 The figure shows the particle size distribution of carbon nanotubes containing the dispersant of the conductive paste in Comparative Example 1. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0019] Example 1: A method for preparing a dispersant for conductive paste, specifically including the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until uniformly dissolved; add 8.78g of triethylamine, stir at room temperature for 5min, and purge with nitrogen for 40min to remove oxygen; slowly add 7.86g of acryloyl chloride dropwise at 0℃, and continue stirring after the addition is complete, react for 1h, filter, collect the filtrate, concentrate on a rotary evaporator, and recrystallize using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; the specific reaction equation is as follows: ; S2. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until uniformly dissolved; add 18.04g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 16.14g of acryloyl chloride dropwise at 0℃. After the addition is complete, continue stirring and react for 1h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate ethyl ester; the specific reaction equation is as follows: ; S3. Dissolve 5g of naphthothiophene-2-acrylic anhydride and 5g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 40min, raise the temperature to 60℃, and stir slowly for 2h to obtain the reaction solution; the specific reaction equation is as follows: ; Where m and n are the degree of polymerization, m = 1~15; n = 1~20; S4. Add 2g acrylic acid, 6g methyl methacrylate, and 12g butyl acrylate to the reaction solution, add 0.4g azobisisobutyronitrile as an initiator, and perform nitrogen purging for 40 minutes to remove oxygen. React at 70°C for 4 hours. Under nitrogen protection, cool to room temperature, add the reaction solution to a hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with hexane, and place in a vacuum drying oven to dry for 24 hours to obtain a dispersant for conductive paste. The specific reaction equation is as follows: ; Wherein, R1 is the polymer chain formed by the double bond polymerization reaction of acrylic acid, butyl acrylate, and methyl methacrylate; m=1~15; n=1~20; The ATR-FTIR spectrum of the dispersant used in the conductive paste prepared in this embodiment is as follows: Figure 1 As shown.

[0020] Example 2: A method for preparing a dispersant for conductive paste, specifically including the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 11.42g of triethylamine, stir at room temperature for 5min, and purge with nitrogen for 40min to remove oxygen; slowly add 9.43g of acryloyl chloride at 3℃, and after the addition is complete, continue the reaction for 2h, filter, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; S2. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 23.46g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 19.37g of acryloyl chloride at 3℃. After the addition is complete, continue the reaction for 2h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S3. Dissolve 4g of naphthothiophene-2-acrylic anhydride and 6g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 30min, heat to 70℃, stir slowly for 2h to obtain the reaction solution. S4. Add 1.42g acrylic acid, 7.15g methyl methacrylate and 11.43g butyl acrylate to the reaction solution, add 0.4g azobisisobutyronitrile as an initiator, purge with nitrogen for 30min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain a dispersant for conductive paste.

[0021] Example 3: A method for preparing a dispersant for conductive paste, specifically including the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 9.66g of triethylamine, stir at room temperature for 5min, and purge with nitrogen for 40min to remove oxygen; slowly add 8.64g of acryloyl chloride at 0℃, and after the addition is complete, continue the reaction for 1h, filter, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; S2. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 19.85g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 17.75g of acryloyl chloride at 0℃. After the addition is complete, continue the reaction for 1h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S3. Dissolve 5g of naphthothiophene-2-acrylic anhydride and 6.5g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.23g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 30min, raise the temperature to 65℃, stir slowly for 2h to obtain the reaction solution. S4. Add 1.91g acrylic acid, 7.67g methyl methacrylate and 13.42g butyl acrylate to the reaction solution, add 0.46g azobisisobutyronitrile as an initiator, purge with nitrogen for 30min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain a dispersant for conductive paste.

[0022] Example 4: A method for preparing a dispersant for conductive paste, specifically including the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 10.54g of triethylamine, stir at room temperature for 5min, and purge with nitrogen for 40min to remove oxygen; slowly add 9.43g of acryloyl chloride at 3℃, and after the addition is complete, continue the reaction for 2h, filter, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; S2. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 21.65g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 19.37g of acryloyl chloride at 3℃. After the addition is complete, continue the reaction for 2h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S3. Dissolve 5g of naphthothiophene-2-acrylic anhydride and 5g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 40min, heat to 70℃, stir slowly for 2h to obtain the reaction solution. S4. Add 1.42g acrylic acid, 7.15g methyl methacrylate and 11.43g butyl acrylate to the reaction solution, add 0.4g azobisisobutyronitrile as an initiator, purge with nitrogen for 40min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain a dispersant for conductive paste.

[0023] Example 5: A method for preparing a dispersant for conductive paste, specifically including the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 8.78g of triethylamine, stir at room temperature for 5min, and purge with nitrogen to remove oxygen for 40min; slowly add 7.86g of acryloyl chloride at 5℃, and after the addition is complete, continue the reaction for 1h, filter, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; S2. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 18.04g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 16.14g of acryloyl chloride at 5℃. After the addition is complete, continue the reaction for 1h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S3. Dissolve 5g of naphthothiophene-2-acrylic anhydride and 6.5g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.23g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 30min, heat to 60℃, stir slowly for 2h to obtain the reaction solution. S4. Add 2.3g acrylic acid, 6.9g methyl methacrylate and 13.8g butyl acrylate to the reaction solution, add 0.46g azobisisobutyronitrile as an initiator, purge with nitrogen for 30min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain a dispersant for conductive paste.

[0024] Comparative Example 1: A method for preparing a dispersant for conductive paste, which differs from Example 1 in that the dispersant is polyvinylpyrrolidone (PVP), a commonly used industrial dispersant.

[0025] Comparative Example 2: A method for preparing a dispersant for conductive paste, differing from Example 1 in that the reaction process does not include naphthothiophene-2-acrylic anhydride, and specifically includes the following steps: S1. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 18.04g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 16.14g of acryloyl chloride at 0℃. After the addition is complete, continue the reaction for 1h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S2. Dissolve 10g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 40min, heat to 60℃, stir slowly for 2h to obtain the reaction solution. S3. Add 2g of acrylic acid, 6g of methyl methacrylate and 12g of butyl acrylate to the reaction solution, add 0.4g of azobisisobutyronitrile as an initiator, purge with nitrogen for 40min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain a dispersant for conductive paste.

[0026] Comparative Example 3: A method for preparing a dispersant for conductive paste, differing from Example 1 in that the reaction process does not include imidazole ethyl acrylate, and specifically includes the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 8.78g of triethylamine, stir at room temperature for 5min, and purge with nitrogen for 40min to remove oxygen; slowly add 7.86g of acryloyl chloride at 0℃, and after the addition is complete, continue the reaction for 1h, filter, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; S2. Dissolve 10g of naphthothiophene-2-acrylic anhydride in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, remove oxygen by purging with nitrogen, heat to 60℃, and stir slowly for 2h to obtain the reaction solution. S3. Add 2g acrylic acid, 6g methyl methacrylate and 12g butyl acrylate to the reaction solution, add 0.4g azobisisobutyronitrile as an initiator, purge with nitrogen for 40min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter to collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain a dispersant for conductive paste.

[0027] Comparative Example 4: A method for preparing a dispersant for conductive paste, differing from Example 1 in that the reaction process does not include acrylic acid and methyl methacrylate, and specifically includes the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 8.78g of triethylamine, stir at room temperature for 5min, and purge with nitrogen for 40min to remove oxygen; slowly add 7.86g of acryloyl chloride at 0℃, and after the addition is complete, continue the reaction for 1h, filter, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; S2. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 18.04g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 16.14g of acryloyl chloride at 0℃. After the addition is complete, continue the reaction for 1h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S3. Dissolve 5g of naphthothiophene-2-acrylic anhydride and 5g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 40min, heat to 60℃, stir slowly for 2h to obtain the reaction solution. S4. Add 20g of butyl acrylate to the reaction solution, add 0.4g of azobisisobutyronitrile as an initiator, and perform nitrogen purging for 40min to remove oxygen. React at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter to collect the precipitate, wash with n-hexane, place in a vacuum drying oven, and dry for 24h to obtain a dispersant for conductive paste.

[0028] Comparative Example 5: A method for preparing a dispersant for conductive paste, differing from Example 1 in that the polymerization reaction process does not include naphthothiophene-2-acrylic anhydride, i.e., the resulting copolymer product does not contain naphthothiophene-2-acrylic anhydride. However, the conductive paste dispersant is prepared by mixing naphthothiophene-2-acrylic anhydride with the copolymer product, specifically including the following steps: S1. Dissolve 20g of naphthothiophene-2-carboxylic acid in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 8.78g of triethylamine, stir at room temperature for 5min, and purge with nitrogen for 40min to remove oxygen; slowly add 7.86g of acryloyl chloride at 0℃, and after the addition is complete, continue the reaction for 1h, filter, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride; S2. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 18.04g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 16.14g of acryloyl chloride at 0℃. After the addition is complete, continue the reaction for 1h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S3. Dissolve 10g of imidazole ethyl acrylate in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 40min, heat to 60℃, stir slowly for 2h to obtain the reaction solution. S4. Add 2g acrylic acid, 6g methyl methacrylate and 12g butyl acrylate to the reaction solution, add 0.4g azobisisobutyronitrile as an initiator, purge with nitrogen for 40min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter to collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain the copolymer product; S5. Mix 6g of copolymer product with 1g of naphthothiophene-2-acrylic anhydride to obtain a dispersant for conductive paste.

[0029] Comparative Example 6: A method for preparing a dispersant for conductive paste, differing from Example 1 in that naphthothiophene-2-acrylic anhydride is replaced with 1-allylnaphthalene, specifically including the following steps: S1. Dissolve 20g of 1-(2-hydroxyethyl)imidazol in 100mL of anhydrous tetrahydrofuran, add 0.2g of hydroquinone, and stir until it is evenly dissolved; add 18.04g of triethylamine, stir at room temperature for 5min, purge with nitrogen for 40min to remove oxygen, and slowly add 16.14g of acryloyl chloride at 0℃. After the addition is complete, continue the reaction for 1h. Filter the product, collect the filtrate, concentrate it on a rotary evaporator, and recrystallize it using toluene and petroleum ether to obtain imidazolium acrylate. S2. Dissolve 5g of imidazole ethyl acrylate and 5g of 1-allylnaphthalene in 50mL of anhydrous toluene, add 0.2g of azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen for 40min, heat to 60℃, stir slowly for 2h to obtain the reaction solution. S3. Add 2g acrylic acid, 6g methyl methacrylate and 12g butyl acrylate to the reaction solution, add 0.4g azobisisobutyronitrile as an initiator, purge with nitrogen for 40min to remove oxygen, react at 70℃ for 4h, cool to room temperature under nitrogen protection, add the reaction solution to n-hexane solution, stir until a precipitate appears, filter to collect the precipitate, wash with n-hexane, place in a vacuum drying oven and dry for 24h to obtain a dispersant for conductive paste.

[0030] Performance testing: The conductive pastes prepared in Examples 1-5 and Comparative Examples 1-6 were mixed with a dispersant, carbon nanotubes, and N-methylpyrrolidone at a mass ratio of 1:5:94. After stirring until homogeneous, the mixture was sonicated for 30 minutes to obtain a conductive paste containing the dispersant. The prepared conductive paste containing the dispersant was then used for testing.

[0031] (1) Dispersion effect test: The viscosity of the conductive paste containing the dispersant was tested using a viscometer at 25°C and 30 rpm. Lower viscosity indicates better dispersion performance. The test results are shown in Table 1.

[0032] The prepared conductive slurry containing the dispersant was placed in a glass bottle and kept in a 50°C oven for static temperature control. The time it took for stratification to occur was observed; the longer the time, the better the dispersant's dispersion performance on the conductive slurry. The test results are shown in Table 1. Actual images of the conductive slurries prepared with the dispersants of Example 1 and Comparative Example 1 after 30 days of storage are shown below. Figure 2 As shown, Figure (a) shows the conductive paste prepared in Example 1, and Figure (b) shows the conductive paste prepared in Comparative Example 1.

[0033] Table 1 Test results of conductive paste dispersion effect ; As can be seen from Table 1, the conductive slurries prepared with the dispersants in Examples 1-5 show stratification at a significantly later time than the conductive slurries prepared with the dispersants in the comparative examples. This indicates that the dispersant prepared using the preparation method of the present invention can maintain the dispersion performance of carbon nanotubes for a longer period of time and has good dispersibility.

[0034] As shown in Table 1, the dispersion stability of the dispersants in Comparative Examples 2 and 3 is lower than that in Example 1. This is because Comparative Example 2 did not add a naphthiophene group, and Comparative Example 3 did not add an imidazole group. The naphthiophene group and the imidazole group cannot undergo intramolecular π-π stacking, thus failing to form a strong adsorption bond with the carbon nanotubes, affecting the dispersion stability of the carbon nanotubes. This indicates that the synergy of the two groups can achieve the best dispersion effect. The dispersion stability of Comparative Example 5 is also significantly lower than that of Example 1, possibly because the naphthiophene group and the imidazole group are not connected to the same molecular structure, resulting in the inability of the naphthiophene group and the imidazole group to successfully undergo intramolecular π-π stacking, and thus failing to strongly adsorb onto the carbon nanotubes, leading to poor dispersion stability. The dispersion stability of the dispersant in Comparative Example 6 is also significantly lower than that of Example 1, because Comparative Example 6 does not add a thiophene group structure, and cannot synergistically form a strong adsorption layer with the naphthiophene group through chemical adsorption and physical adsorption, thus failing to achieve good dispersion performance. This indicates that the naphthiophene group and the thiophene group linked to the same molecule can achieve better dispersion stability. The dispersion stability of the dispersant in Comparative Example 4 was lower than that in Example 1 because the use of a copolymer of acrylic acid, methyl methacrylate and butyl acrylate as a long-chain structure can regulate the spatial conformation and steric hindrance effect of the dispersant molecules, thereby obtaining the best spatial stability effect. However, using only butyl acrylate does not have this ability and cannot achieve the best dispersion effect.

[0035] (2) DLS particle size distribution test: The conductive slurries containing the dispersants of Example 1 and Comparative Example 1 were analyzed using a nanoparticle size analyzer at a temperature of 25°C. The test results are as follows: Figure 3 and Figure 4 As shown. Figure 3 This is a particle size distribution diagram of the conductive slurry containing the dispersant of Example 1. Figure 4 This is a particle size distribution diagram of the conductive slurry containing the dispersant of Comparative Example 1. From... Figure 3 and Figure 4 As can be seen, the particle size of the conductive slurry containing the dispersant of Example 1 is smaller than that of the conductive slurry containing the dispersant of Comparative Example 1, and no large particles appear. The distribution width is also significantly smaller than that of Comparative Example 1. This indicates that the dispersant for conductive slurry prepared by the preparation method of the present invention has better dispersion performance than the commonly used dispersant PVP.

[0036] (3) Test on the effect of conductivity: Preparation of blank control example: Carbon nanotubes and N-methylpyrrolidone were mixed evenly at a mass ratio of 1:19 and ultrasonically treated for 30 min to obtain carbon nanotube conductive paste without dispersant.

[0037] The prepared carbon nanotube conductive paste containing dispersant and the carbon nanotube conductive paste without dispersant were coated onto glass substrates respectively and cured at 120℃ for 30 min. The resistance change was measured using a four-probe resistance meter. Using the resistance of the carbon nanotube conductive paste without dispersant as a benchmark, the percentage change in resistance of the conductive paste containing dispersant was calculated. If the resistance change was less than 10%, it indicated that the dispersant did not affect the performance of the conductive paste. The test results are shown in Table 2.

[0038] Table 2 Test results of resistance variation of conductive paste ; As can be seen from Table 2, the resistance change in Example 1 is smaller than that in the comparative example, indicating that the dispersant prepared by the method of the present invention has virtually no impact on the conductivity of the conductive slurry. The dispersant in Comparative Example 1 has a greater impact on the resistance of the conductive slurry due to the insulating nature 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 conductivity of the dispersant because it possesses a highly delocalized π-conjugated system in which electrons can move relatively freely, thus not affecting the resistance of the conductive slurry.

[0039] (4) Withstand voltage and cycle performance test: The prepared carbon nanotube conductive slurry containing dispersant was mixed with PVDF binder at a mass ratio of 89:11 to obtain a coating slurry. This coating slurry was then coated onto a current collector (12 μm thick aluminum foil) and vacuum dried at 110 °C to obtain an electrode sheet. The obtained electrode sheet was then rolled and sliced, and assembled into a battery with a lithium foil in a glove box. The battery was used for a maximum voltage test, and the maximum voltage at which the redox peak appeared was recorded. The test results are shown in Table 3.

[0040] The prepared batteries were subjected to cycle performance testing, including 100 cycles of 0.5C charge / 0.5C discharge, and the cycle capacity retention rate was calculated. The test results are shown in Table 3.

[0041] Table 3. Test results of withstand voltage and cycle performance of conductive paste ; As shown in Table 3, the oxygen reduction peak voltages in Examples 1-5 are higher than those in Comparative Examples 1-6, indicating that the dispersant for the conductive slurry prepared using the method of this invention can withstand higher voltages and is suitable for high-voltage battery systems. This invention uses naphthothiophene and imidazole synergistically to improve the antioxidant decomposition ability of the dispersant molecules themselves, thereby maintaining stability under high-voltage cathode conditions and protecting the electrode interface.

[0042] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a dispersant for conductive paste, characterized in that, Includes the following steps: S1. Dissolve naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate in anhydrous toluene, add azobisisobutyronitrile as an initiator, remove oxygen by nitrogen purging, heat to 60~70℃, stir slowly for 2h to obtain the reaction solution. S2. Add acrylic acid and acrylate to the reaction solution, add azobisisobutyronitrile as an initiator, purge with nitrogen to remove oxygen, react at 70°C for 4 hours, cool to room temperature under nitrogen protection, add n-hexane solution, stir until a precipitate appears, filter, collect the precipitate, wash with n-hexane, and vacuum dry for 24 hours to obtain a dispersant for conductive paste.

2. The method for preparing the dispersant for conductive paste according to claim 1, characterized in that, In step S1, the preparation method of the naphthothiophene-2-acrylic anhydride includes the following steps: dissolving naphthothiophene-2-carboxylic acid in anhydrous tetrahydrofuran, adding hydroquinone, and stirring to make it uniformly dissolved; adding triethylamine, stirring at room temperature for 5 min, and purging with nitrogen for 40 min to remove oxygen; slowly adding acryloyl chloride at 0~5℃, and continuing the reaction for 1~2 h after the addition is completed, filtering, collecting the filtrate, evaporating and concentrating, and recrystallizing with toluene and petroleum ether to obtain naphthothiophene-2-acrylic anhydride.

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 includes the following steps: dissolving 1-(2-hydroxyethyl)imidazolium in anhydrous tetrahydrofuran, adding hydroquinone, and stirring to make it uniformly dissolved; adding triethylamine, stirring at room temperature for 5 min, purging with nitrogen to remove oxygen for 40 min, slowly adding acryloyl chloride at 0~5℃, continuing the reaction for 1~2 h after the addition is completed, filtering, collecting the filtrate, evaporating and concentrating, and recrystallizing 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 imidazole ethyl acrylate is 1:1 to 1.5, and the mass of azobisisobutyronitrile is 2% of the total mass of the naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate.

5. The method for preparing the dispersant for conductive paste according to claim 2, characterized in that, 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.

6. The method for preparing the dispersant for conductive paste according to claim 3, characterized in that, 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.

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 acrylic acid, methyl methacrylate and butyl acrylate is 1:3~5:6~8; the total mass ratio of acrylic acid, methyl methacrylate and butyl acrylate to the total mass ratio of naphthothiophene-2-acrylic anhydride and imidazole ethyl acrylate is 2:1; the mass of the azobisisobutyronitrile is 2% of the total mass of acrylic acid, methyl methacrylate and butyl acrylate.

8. The dispersant for conductive paste prepared by the method according to claims 1-7.

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