A fully solid composite dry-process conductive agent and its preparation method

Abstract

The invention discloses an all-solid-state composite dry-process conductive agent and a preparation method thereof, belonging to the technical field of batteries. The all-solid-state composite dry-process conductive agent of the invention comprises the following steps: firstly, carbon nanotubes, highly dispersed carbon black and graphene are uniformly mixed to obtain a primary mixture; then, a composite dispersant and water are configured to form a uniformly dispersed glue solution; then, the primary mixture is added to the glue solution, mixed uniformly, and then sand-milled, homogenized, dried and pulverized to obtain the conductive agent; the highly dispersed carbon black is firstly oxidized to form active groups such as carboxyl and hydroxyl groups on the carbon black surface, and then acyl halogenated and reacted with lithium 2,5-diaminobenzenesulfonate to obtain the conductive agent; and the composite dispersant is obtained by grafting histidine ester onto carboxymethyl cellulose using propylene glycol diglycidyl ester as a crosslinking agent, then introducing propylene-1,3-sultone, and then copolymerizing with lithium 2-acrylamido-2-methylpropanesulfonate and fluorenylmethyloxycarbonyl-protected allyl 3-aminobenzoate, followed by deprotection.

Description

Technical Field

[0001] The invention relates to an all-solid composite dry-process conductive agent and a preparation method thereof. Background Art

[0002] With the rapid development of the global new energy sector, lithium-ion batteries, as high-efficiency energy storage devices, play a vital role in portable electronic devices, electric vehicles, and large-scale energy storage systems. All-solid-state lithium batteries, due to their enhanced safety and potential energy density advantages, are considered one of the ultimate forms of commercial lithium-ion battery development. Compared with traditional lithium-ion batteries, all-solid-state lithium batteries can effectively avoid risks such as thermal runaway and flammability, thereby significantly improving battery safety performance.

[0003] However, the conductive agents currently used in lithium-ion batteries face significant challenges in transitioning to all-solid-state lithium-ion batteries. The two main conductive agents currently in use are conductive carbon black and carbon nanotube conductive paste. Conductive carbon black, in powder form, is low-cost and easy to disperse, but its conductivity is poor. To ensure conductivity in both the positive and negative electrodes of lithium-ion batteries, a high proportion of conductive carbon black is typically required, which not only increases the overall weight of the battery but also reduces its energy density. Meanwhile, while carbon nanotube conductive paste offers good conductivity, its solids content generally does not exceed 10%, meaning that most of the ingredients are unused solvents. This not only complicates transportation and storage but also increases costs. Oil-based conductive pastes, in particular, use NMP (N-methylpyrrolidone) as the primary solvent. NMP is toxic, placing higher demands on the production environment. Furthermore, NMP's high water absorption makes it incompatible with the strict moisture control requirements of lithium-ion battery production processes.

[0004] Single-component carbon nanotube conductive pastes or conductive carbon black powders have limited potential for improving lithium-ion battery performance, making them difficult to meet the demands of high-performance all-solid-state lithium batteries. Furthermore, existing conductive agents contain hazardous solvents and are difficult to transport and store, further limiting their application and potential. Therefore, the development of an all-solid-state composite dry-process conductive agent and its preparation method is crucial. Summary of the Invention

[0005] The purpose of the present invention is to provide an all-solid-state composite dry-process conductive agent and a preparation method thereof, so as to solve the technical problems mentioned in the above background technology.

[0006] The technical solution for achieving the purpose of the present invention is:

[0007] In a first aspect, the present invention provides an all-solid-state composite dry-process conductive agent, wherein the raw material components mainly include, by weight: 20 to 80 parts by weight of carbon nanotubes, 5 to 20 parts by weight of highly dispersed carbon black, 1 to 20 parts by weight of graphene, 1 to 20 parts by weight of a composite dispersant, and 80 to 90 parts by weight of deionized water; the preferred raw material components mainly include: 50 to 80 parts by weight of carbon nanotubes, 10 to 20 parts by weight of highly dispersed carbon black, 1 to 10 parts by weight of graphene, 1 to 20 parts by weight of a composite dispersant, and 80 to 90 parts by weight of deionized water.

[0008] The present invention adopts a combination of one-dimensional carbon nanotubes, zero-dimensional carbon black and two-dimensional graphene. Among them, the carbon nanotubes provide long-range conductive paths to reduce interfacial resistance, the carbon black fills microscopic gaps to enhance point contact conductivity, and the graphene forms surface contact support to improve the overall structural stability, thereby constructing a multi-dimensional conductive network from points, lines to surfaces, effectively improving the conductive performance of the all-solid-state composite dry-process conductive agent.

[0009] Furthermore, the highly dispersed carbon black is obtained by first oxidizing the carbon black, then subjecting it to acyl halogenation, and finally reacting it with lithium 2,5-diaminobenzenesulfonate.

[0010] The highly dispersed carbon black of the present invention is obtained by first oxidizing carbon black to form active groups such as carboxyl and hydroxyl groups on the carbon black surface, and then reacting with lithium 2,5-diaminobenzenesulfonate after acyl halogenation. Hydrophilic lithium 2,5-diaminobenzenesulfonate is grafted on the carbon black surface. The lithium sulfonate is firmly anchored to the carbon black surface through chemical bonding. Its strong hydrophilic property effectively weakens the van der Waals force between carbon black particles, so that the conductive agent is uniformly dispersed in the rubber system, which can significantly reduce the contact resistance in the conductive network and enhance the conductive performance of the all-solid-state composite dry-process conductive agent.

[0011] Furthermore, the composite dispersant is obtained by copolymerizing functionalized carboxymethyl cellulose with lithium 2-acrylamido-2-methylpropanesulfonate and fluorenylmethoxycarbonyl-protected allyl 3-aminobenzoate and then deprotecting the copolymer.

[0012] The composite dispersant of the present invention is obtained by copolymerizing functionalized carboxymethyl cellulose with lithium 2-acrylamido-2-methylpropanesulfonate and fluorenylmethoxycarbonyl-protected 3-aminobenzoic acid allyl ester and then deprotecting the copolymer. The functionalized carboxymethyl cellulose is used as a reinforcing phase, and a copolymer of functionalized carboxymethyl cellulose, lithium 2-acrylamido-2-methylpropanesulfonate and allyl 3-aminobenzoate is prepared by carbon-carbon double bond polymerization. The lithium 2-acrylamido-2-methylpropanesulfonate monomer synthesized by reacting 2-acrylamido-2-methylpropanesulfonic acid with lithium hydroxide has fixed anionic groups and free lithium ions after polymerization. The fixed anionic structure brings stronger negative charge delocalization ability, makes lithium ions more likely to dissociate in the system, and further improves the conductivity of the composite dispersant.

[0013] Furthermore, the functionalized carboxymethyl cellulose is obtained by grafting histidine ester onto carboxymethyl cellulose using propylene glycol diglycidyl ester as a crosslinking agent and then introducing propenyl-1,3-sultone.

[0014] The functionalized carboxymethyl cellulose of the present invention is prepared by grafting histidine ester onto carboxymethyl cellulose using propylene glycol diglycidyl ester as a crosslinking agent, and then introducing propenyl-1,3-sultone to react with the tertiary amine on the imidazole ring of the histidine ester for ring-opening grafting to form an imidazolium ionic liquid containing propene and sulfonic acid groups, thereby effectively improving the conductivity of the carboxymethyl cellulose.

[0015] In a second aspect, the present invention provides a method for preparing the all-solid-state composite dry-process conductive agent as described in the first aspect, comprising the following preparation steps:

[0016] (1) Weigh and mix the raw materials;

[0017] (2) uniformly mixing the carbon nanotubes, highly dispersed carbon black, and graphene weighed in step (1) to obtain a primary mixture;

[0018] (3) mixing the composite dispersant weighed in step (1) with deionized water to obtain a rubber compound;

[0019] (4) adding the primary mixture obtained in step (2) to the rubber obtained in step (3), adding 3M hydrochloric acid solution to adjust the pH to 6-6.5, adding 2-30 parts by mass of 0.5 mol / L ammonium persulfate aqueous solution under stirring conditions, continuing stirring for 30 minutes, and then continuing stirring at -2-2°C for 5.5-6.5 hours to obtain a secondary mixture;

[0020] (5) The secondary mixture obtained in step (4) is placed in a sand mill for sand grinding to obtain a slurry; the parameters of the sand grinding step are: rotation speed 1000~3000rpm, feed pressure ≤0.5MPa, material temperature ≤60℃; sand grinding requirements: slurry viscosity: 1000~5000mPa.S, slurry particle size D10 ≤1μm, D50 ≤10μm, D90 ≤20μm;

[0021] (6) The slurry obtained in step (5) is homogenized, dried, and air-flow-pulverized to obtain a fully solid composite dry-process conductive agent; the parameters of the homogenization step are: homogenization pressure: 20~100MPa, homogenization times: 5~30 times, homogenization material temperature: ≤60°C, homogenization requirements: slurry viscosity: 1000~5000mPa.S, slurry particle size D10≤1μm, D50≤5μm, D90≤20μm; air-flow-pulverization parameters: classifying wheel 40±10Hz, air pressure 0.6±0.2MPa, pulverization requirements: powder particle size D10≤1μm, D50=3.5±1.5μm, D90≤20μm.

[0022] During the preparation of the all-solid-state composite dry-process conductive agent of the present invention, aniline in the composite dispersant and aniline on the surface of highly dispersed carbon black are oxidatively polymerized to form a polyaniline π-conjugated polymer network. The composite dispersant utilizes the π-π interaction between polyaniline and carbon nanotubes and graphene to uniformly disperse the carbon nanotubes and graphene in the rubber material. Lithium ions act as glue to firmly combine the polyaniline stacked together through the π-π interaction with relatively weak interaction strength with the carbon nanotubes and graphene, effectively preventing active substances from falling off the graphene and carbon nanotubes, further improving the conductivity of the all-solid-state composite dry-process conductive agent, and thus improving the cycle performance of the battery.

[0023] Furthermore, the preparation steps of the highly dispersed carbon black are as follows: 50 parts by mass of carbon black and 330-340 parts by mass of 30% hydrogen peroxide are stirred and reacted at 78-82° C. for 9.5-10.5 hours, after the reaction is completed, the mixture is cooled to room temperature and filtered, and 330-340 parts by mass of 30% hydrogen peroxide are continuously added and stirred and reacted at 78-82° C. for 9.5-10.5 hours, after the reaction is completed, the mixture is cooled to room temperature and filtered, and 330-340 parts by mass of 30% hydrogen peroxide are continuously added and stirred and reacted at 78-82° C. for 9.5-10.5 hours. h, after the reaction is completed, it should be cooled to room temperature and filtered, washed with deionized water until the filtrate is neutral, and the filter residue is dried at 74-76 ° C to obtain surface oxidized carbon black with a surface oxygen functional group of 1.85-1.86 mmol / g; 50 parts by mass of surface oxidized carbon black, 12-13 parts by mass of thionyl chloride, and 200 parts by mass of toluene are mixed and stirred for 10-20 minutes, and then 3.4-3.6 parts by mass of triethylamine are added as an acid binding agent, and the reaction is carried out in an ice bath for 25-35 minutes, and then heated to 115-125 ° C and the reaction is continued for 25-35 min, after the reaction is completed, filter, and remove unreacted thionyl chloride by rotary evaporation at 75-85° C. to obtain acyl chloride carbon black; under ice bath conditions, 50 parts by mass of acyl chloride carbon black and 200-300 parts by mass of toluene are mixed, stirred and dispersed for 25-35 minutes, then 3.4-3.6 parts by mass of triethylamine are added as an acid binding agent, followed by adding 17-18 parts by mass of lithium 2,5-diaminobenzenesulfonate, stirring and reacting overnight, filtering, washing with deionized water 2-4 times, and drying at 70-80° C. to obtain highly dispersed carbon black.

[0024] Furthermore, the preparation steps of the composite dispersant are as follows: adding 0.4 to 0.6 parts by mass of functionalized carboxymethyl cellulose, 2 to 3 parts by mass of lithium 2-acrylamido-2-methylpropanesulfonate, 7 to 8 parts by mass of fluorenylmethoxycarbonyl-protected 3-aminobenzoic acid allyl ester, and 0.045 to 0.046 parts by mass of ammonium persulfate to 30 to 40 parts by mass of deionized water, stirring and mixing for 25 to 35 minutes, and then adding 0.062 to 0.063 parts by mass of tetramethylethylenediamine, stirring and mixing evenly at 0 to 5° C., and then standing at room temperature for reaction for 23 to 25 hours, followed by adding 80 parts by mass of methanol and 5 to 6 parts by mass of piperidine, stirring at room temperature for 17 to 19 hours, and then soaking in deionized water for impurity removal for 2 to 4 days, and changing the water every 11 to 13 hours to obtain a composite dispersant.

[0025] Furthermore, the preparation steps of the functionalized carboxymethyl cellulose are as follows: 0.4 mol / L sodium hydroxide aqueous solution is mixed with carboxymethyl cellulose, stirred at 78-82°C until the carboxymethyl cellulose is dissolved, ultrasonically degassed and cooled to room temperature to obtain a 6.5-7.5 wt% carboxymethyl cellulose solution, then 15 wt% propylene glycol diglycidyl ester dimethyl sulfoxide solution and histidine ester are added to the carboxymethyl cellulose solution, stirred at room temperature for 55-65 minutes, then kept in a water bath at 38-42°C for 23-25 ​​hours, and then Then, allyl-1,3-sultone is added within 10 minutes, and the temperature is raised to 85-95°C and the reaction is continued for 11-13 hours. Then, concentrated sulfuric acid is added and the reaction is continued at 85-95°C for 9-11 hours. Then, the mixture is immersed in deionized water to remove impurities, and the water is changed every 11-13 hours until it becomes transparent to obtain functionalized carboxymethyl cellulose, wherein the molar ratio of deoxyglucose units in the carboxymethyl cellulose to propylene glycol diglycidate, allyl-1,3-sultone, and concentrated sulfuric acid is 8:8-10:10-12:10-12.

[0026] Furthermore, the drying step is freeze drying; the freeze drying parameters are: cold trap temperature ≤-50°C, vacuum degree ≤5Pa, and freeze drying requirements: sample moisture ≤1%.

[0027] Furthermore, the drying step is to first perform filter pressing and then place the product in an oven for drying; the filter pressing parameters are: working pressure 0.4~1.2MPa, feed pump pressure: 0.2~0.8MPa, filter pressing requirements: material moisture ≤60%; the oven drying parameters are: oven temperature 80~100℃, drying requirements: material moisture ≤1%.

[0028] By adopting the above technical solution, the present invention has the following beneficial effects:

[0029] (1) The present invention adopts a combination of one-dimensional carbon nanotubes, zero-dimensional carbon black and two-dimensional graphene, wherein the carbon nanotubes provide long-range conductive paths to reduce interface resistance, the carbon black fills microscopic gaps to enhance point contact conductivity, and the graphene forms surface contact support to improve the overall structural stability, thereby constructing a multi-dimensional conductive network from point to line to surface, effectively improving the conductive performance of the all-solid-state composite dry-process conductive agent.

[0030] (2) The composite dispersant of the present invention is obtained by copolymerizing functionalized carboxymethyl cellulose with lithium 2-acrylamido-2-methylpropanesulfonate and 3-aminobenzoic acid allyl ester protected by fluorenylmethoxycarbonyl and then deprotecting the copolymer. The functionalized carboxymethyl cellulose is used as a reinforcing phase, and a copolymer of functionalized carboxymethyl cellulose, lithium 2-acrylamido-2-methylpropanesulfonate and 3-aminobenzoic acid allyl ester is prepared by carbon-carbon double bond polymerization. The lithium 2-acrylamido-2-methylpropanesulfonate monomer synthesized by reacting 2-acrylamido-2-methylpropanesulfonic acid with lithium hydroxide has fixed anionic groups and free lithium ions after polymerization. The fixed anionic structure brings stronger negative charge delocalization ability, making it easier for lithium ions to dissociate in the system, further improving the conductivity of the composite dispersant.

[0031] (3) The highly dispersed carbon black of the present invention is obtained by first oxidizing carbon black to form active groups such as carboxyl and hydroxyl groups on the carbon black surface, and then reacting with lithium 2,5-diaminobenzenesulfonate after acyl halogenation. Hydrophilic lithium 2,5-diaminobenzenesulfonate is grafted on the carbon black surface. The lithium sulfonate is firmly anchored on the carbon black surface through chemical bonding. Its strong hydrophilic property effectively weakens the van der Waals force between carbon black particles, allowing the conductive agent to be uniformly dispersed in the rubber system, which can significantly reduce the contact resistance in the conductive network and enhance the conductive performance of the all-solid-state composite dry-process conductive agent.

[0032] (4) The functionalized carboxymethyl cellulose of the present invention is prepared by grafting histidine ester onto carboxymethyl cellulose using propylene glycol diglycidyl ester as a crosslinking agent, and then introducing propenyl-1,3-sultone to react with the tertiary amine on the imidazole ring of the histidine ester for ring-opening grafting to form an imidazole ionic liquid containing propene and sulfonic acid groups, which effectively improves the conductivity of the carboxymethyl cellulose.

[0033] (5) During the preparation of the all-solid composite dry-process conductive agent of the present invention, the aniline in the composite dispersant and the aniline on the surface of the highly dispersed carbon black are oxidatively polymerized to form a polyaniline π-conjugated polymer network. The composite dispersant utilizes the π-π interaction between polyaniline and carbon nanotubes and graphene to uniformly disperse the carbon nanotubes and graphene in the rubber material, while the lithium ions can act as a glue to firmly combine the polyaniline stacked together by the π-π interaction with the carbon nanotubes and graphene with relatively weak interaction strength, which can effectively prevent the active material from falling off from the graphene and carbon nanotubes, further improving the conductivity of the all-solid composite dry-process conductive agent, thereby improving the cycle performance of the battery.

[0034] (6) The all-solid composite dry-process conductive agent of the present invention is in the form of a powder with an effective ingredient content greater than 80%, which is easier to store and transport than conductive paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein

[0036] Figure 1 The figure is a flow chart for preparing the all-solid composite dry-process conductive agent of the present invention. DETAILED DESCRIPTION

[0037] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods.

[0038] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0039] The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0040] Some of the raw materials of the present invention are as follows, and the remaining raw materials are commercially available:

[0041] Sodium carboxymethyl cellulose, purity 99.0%, produced by Sinopharm Chemical Reagent Co., Ltd.

[0042] The inner diameter of carbon nanotubes is 2nm~5nm; the outer diameter is 5nm~15nm; the length is 10μm~30μm; the specific surface area is 220m 2 / g~300m 2 / g.

[0043] The specific surface area of ​​graphene is 25m 2 / g~31m 2 / g; flake diameter is 3.0μm~9.0μm.

[0044] The carbon black is carbon black N330 produced by Shanxi Hengda Chemical Co., Ltd.

[0045] The histidine ester used was L-histidine benzyl ester.

[0046] (Example 1)

[0047] A method for preparing an all-solid-state composite dry-process conductive agent comprises the following steps:

[0048] (1) Weigh and mix the following raw material components: 50 parts by mass of carbon nanotubes, 20 parts by mass of highly dispersed carbon black, 10 parts by mass of graphene, 10 parts by mass of composite dispersant, and 80 parts by mass of deionized water;

[0049] (2) uniformly mixing the carbon nanotubes, highly dispersed carbon black, and graphene weighed in step (1) to obtain a primary mixture;

[0050] (3) mixing the composite dispersant weighed in step (1) with deionized water to obtain a rubber compound;

[0051] (4) adding the primary mixture obtained in step (2) to the rubber obtained in step (3), adding 3M hydrochloric acid solution to adjust the pH to 6, adding 15 parts by mass of 0.5 mol / L ammonium persulfate aqueous solution under stirring, continuing stirring for 30 minutes, and then continuing stirring at -2°C for 5.5 hours to obtain a secondary mixture;

[0052] (5) The secondary mixture obtained in step (4) is placed in a sand mill for sand grinding to obtain a slurry; the parameters of the sand grinding step are: rotation speed 1000 rpm, feed pressure ≤ 0.5 MPa, material temperature ≤ 60°C; sand grinding requirements: slurry viscosity: 1000~5000 mPa.S, slurry particle size D10 ≤ 1 μm, D50 ≤ 10 μm, D90 ≤ 20 μm.

[0053] (6) The slurry obtained in step (5) is homogenized, freeze-dried, and air-flow-pulverized to obtain a fully solid composite dry-process conductive agent; the parameters of the homogenization step are: homogenization pressure: 20 MPa, number of homogenizations: 10 times, homogenization material temperature: ≤60°C, homogenization requirements: slurry viscosity: 1000~5000mPa.S, slurry particle size D10≤1μm, D50≤5μm, D90≤20μm; the freeze-drying parameters are: cold trap temperature ≤-50°C, vacuum degree ≤5Pa, freeze-drying requirements: sample moisture ≤1%; air-flow-pulverization parameters are: classifying wheel 40±10Hz, air pressure 0.6±0.2MPa, pulverization requirements: powder particle size D10≤1μm, D50=3.5±1.5μm, D90≤20μm.

[0054] The preparation steps of the highly dispersed carbon black are as follows: 50 parts by mass of carbon black and 330 parts by mass of 30% hydrogen peroxide are stirred and reacted at 78° C. for 9.5 hours, cooled to room temperature after the reaction is completed, filtered, and further added with 330 parts by mass of 30% hydrogen peroxide, stirred and reacted at 78° C. for 9.5 hours, cooled to room temperature after the reaction is completed, filtered, and further added with 330 parts by mass of 30% hydrogen peroxide, stirred and reacted at 78° C. for 9.5 hours, cooled to room temperature after the reaction is completed, filtered, washed with deionized water until the filtrate is neutral, and dried the filter residue at 74° C. to obtain surface oxidized carbon black with a surface oxygen-containing functional group of 1.85 mmol / g; 50 parts by mass of surface oxidized carbon black, 12 parts by mass of dichlorothionyl, and 200 parts by mass of toluene are mixed and stirred for 10 minutes, then 3.4 parts by mass of triethylamine is added as an acid binding agent, reacted in an ice bath for 25 minutes, and then heated to 115° C. and continued to react for 25 minutes. min, after the reaction is completed, the reaction is filtered and the unreacted thionyl chloride is removed by rotary evaporation at 75°C to obtain acyl chloride carbon black; under ice bath conditions, 50 parts by mass of acyl chloride carbon black and 200 parts by mass of toluene are mixed, stirred and dispersed for 25 minutes, followed by the addition of 3.4 parts by mass of triethylamine as an acid binding agent, followed by the addition of 17 parts by mass of lithium 2,5-diaminobenzenesulfonate, the reaction is stirred overnight, filtered, washed twice with deionized water, and dried at 70°C to obtain highly dispersed carbon black.

[0055] The preparation steps of the composite dispersant are as follows: adding 0.4 parts by mass of functionalized carboxymethyl cellulose, 2 parts by mass of lithium 2-acrylamido-2-methylpropanesulfonate, 7 parts by mass of fluorenylmethyloxycarbonyl-protected 3-aminobenzoic acid allyl ester, and 0.045 parts by mass of ammonium persulfate to 30 parts by mass of deionized water, stirring and mixing for 25 minutes, then adding 0.062 parts by mass of tetramethylethylenediamine, stirring and mixing at 0°C until uniform, and then standing at room temperature for reaction for 23 hours, then adding 80 parts by mass of methanol and 5 parts by mass of piperidine, stirring at room temperature for 17 hours, and then soaking in deionized water for 2 days to remove impurities, and changing the water every 11 hours to obtain a composite dispersant.

[0056] The functionalized carboxymethyl cellulose is prepared as follows: 0.4 mol / L sodium hydroxide aqueous solution is mixed with carboxymethyl cellulose, stirred at 78° C. until the carboxymethyl cellulose is dissolved, ultrasonically degassed and cooled to room temperature to obtain a 6.5 wt% carboxymethyl cellulose solution, then a 15 wt% dimethyl sulfoxide solution of propylene glycol diglycidyl ester and histidine ester are added to the carboxymethyl cellulose solution, stirred at room temperature for 55 minutes, then kept in a 38° C. water bath for 23 hours, then allyl-1,3-sultone is added within 10 minutes, then the temperature is raised to 85° C. and the reaction is continued for 11 hours, then concentrated sulfuric acid is added and the reaction is continued at 85° C. for 9 hours, then the functionalized carboxymethyl cellulose is immersed in deionized water for impurity removal, and the water is changed every 11 hours until it becomes transparent to obtain the functionalized carboxymethyl cellulose, wherein the molar ratio of deoxyglucose units in the carboxymethyl cellulose to propylene glycol diglycidyl ester, allyl-1,3-sultone and concentrated sulfuric acid is 8:8:10:10.

[0057] (Example 2)

[0058] A method for preparing an all-solid-state composite dry-process conductive agent comprises the following steps:

[0059] (1) Weigh and mix the following raw material components: 65 parts by mass of carbon nanotubes, 15 parts by mass of highly dispersed carbon black, 6 parts by mass of graphene, 15 parts by mass of composite dispersant, and 85 parts by mass of deionized water;

[0060] (2) uniformly mixing the carbon nanotubes, highly dispersed carbon black, and graphene weighed in step (1) to obtain a primary mixture;

[0061] (3) mixing the composite dispersant weighed in step (1) with deionized water to obtain a rubber compound;

[0062] (4) adding the primary mixture obtained in step (2) to the rubber obtained in step (3), adding 3M hydrochloric acid solution to adjust the pH to 6, adding 18 parts by mass of 0.5 mol / L ammonium persulfate aqueous solution under stirring, continuing stirring for 30 minutes, and then continuing stirring at 0°C for 6 hours to obtain a secondary mixture;

[0063] (5) The secondary mixture obtained in step (4) is placed in a sand mill for sand grinding to obtain a slurry; the parameters of the sand grinding step are: rotation speed 2000 rpm, feed pressure ≤ 0.5 MPa, material temperature ≤ 60°C; sand grinding requirements: slurry viscosity: 1000~5000 mPa.S, slurry particle size D10 ≤ 1 μm, D50 ≤ 10 μm, D90 ≤ 20 μm.

[0064] (6) The slurry obtained in step (5) is homogenized, freeze-dried, and air-flow-pulverized to obtain a fully solid composite dry-process conductive agent; the parameters of the homogenization step are: homogenization pressure: 60 MPa, number of homogenizations: 20 times, homogenization material temperature: ≤60°C, homogenization requirements: slurry viscosity: 1000~5000mPa.S, slurry particle size D10≤1μm, D50≤5μm, D90≤20μm; the freeze-drying parameters are: cold trap temperature ≤-50°C, vacuum degree ≤5Pa, freeze-drying requirements: sample moisture ≤1%; air-flow-pulverization parameters are: classifying wheel 40±10Hz, air pressure 0.6±0.2MPa, pulverization requirements: powder particle size D10≤1μm, D50=3.5±1.5μm, D90≤20μm.

[0065] The preparation steps of the highly dispersed carbon black are as follows: 50 parts by mass of carbon black and 335 parts by mass of 30% hydrogen peroxide are stirred and reacted at 80° C. for 10 hours, cooled to room temperature after the reaction is completed, filtered, 335 parts by mass of 30% hydrogen peroxide are continuously added, stirred and reacted at 80° C. for 10 hours, cooled to room temperature after the reaction is completed, filtered, 335 parts by mass of 30% hydrogen peroxide are continuously added, stirred and reacted at 80° C. for 10 hours, cooled to room temperature after the reaction is completed, filtered, washed with deionized water until the filtrate is neutral, and dried the filter residue at 75° C. to obtain surface oxidized carbon black with a surface oxygen-containing functional group of 1.856 mmol / g; 50 parts by mass of surface oxidized carbon black, 12.5 parts by mass of dichlorothionyl, and 200 parts by mass of toluene are mixed and stirred for 15 minutes, then 3.5 parts by mass of triethylamine are added as an acid binding agent, reacted in an ice bath for 30 minutes, and then heated to 120° C. and continued to react for 30 minutes. min, after the reaction is completed, the reaction is filtered, and the unreacted dichloride is removed by rotary evaporation at 80°C to obtain acyl chloride carbon black; under ice bath conditions, 50 parts by mass of acyl chloride carbon black and 250 parts by mass of toluene are mixed, stirred and dispersed for 30 minutes, and then 3.5 parts by mass of triethylamine are added as an acid binding agent, followed by adding 17.5 parts by mass of lithium 2,5-diaminobenzenesulfonate, stirring and reacting overnight, filtering, washing with deionized water 3 times, and drying at 75°C to obtain highly dispersed carbon black.

[0066] The preparation steps of the composite dispersant are as follows: adding 0.5 parts by mass of functionalized carboxymethyl cellulose, 2.5 parts by mass of lithium 2-acrylamido-2-methylpropanesulfonate, 7.5 parts by mass of fluorenylmethyloxycarbonyl-protected 3-aminobenzoic acid allyl ester, and 0.045 parts by mass of ammonium persulfate to 35 parts by mass of deionized water, stirring and mixing for 30 minutes, then adding 0.062 parts by mass of tetramethylethylenediamine, stirring and mixing evenly at 0°C, and then standing at room temperature for reaction for 24 hours, then adding 80 parts by mass of methanol and 5.5 parts by mass of piperidine, stirring at room temperature for 18 hours, and then soaking in deionized water for 3 days to remove impurities, and changing the water every 12 hours to obtain a composite dispersant.

[0067] The functionalized carboxymethyl cellulose is prepared as follows: 0.4 mol / L sodium hydroxide aqueous solution is mixed with carboxymethyl cellulose, stirred at 80° C. until the carboxymethyl cellulose is dissolved, ultrasonically degassed and cooled to room temperature to obtain a 7 wt% carboxymethyl cellulose solution, then a 15 wt% propylene glycol diglycidyl ester dimethyl sulfoxide solution and histidine ester are added to the carboxymethyl cellulose solution, stirred at room temperature for 60 minutes, then kept in a 40° C. water bath for 24 hours, then allyl-1,3-sultone is added within 10 minutes, then the temperature is raised to 90° C. and the reaction is continued for 12 hours, then concentrated sulfuric acid is added and the reaction is continued at 90° C. for 10 hours, then the functionalized carboxymethyl cellulose is immersed in deionized water to remove impurities, and the water is changed every 12 hours until it is transparent to obtain the functionalized carboxymethyl cellulose, wherein the molar ratio of deoxyglucose units in the carboxymethyl cellulose to propylene glycol diglycidyl ester, allyl-1,3-sultone and concentrated sulfuric acid is 8:9:11:11.

[0068] (Example 3)

[0069] A method for preparing an all-solid-state composite dry-process conductive agent comprises the following steps:

[0070] (1) Weigh and mix the following raw material components: 80 parts by mass of carbon nanotubes, 10 parts by mass of highly dispersed carbon black, 2 parts by mass of graphene, 20 parts by mass of composite dispersant, and 90 parts by mass of deionized water;

[0071] (2) uniformly mixing the carbon nanotubes, highly dispersed carbon black, and graphene weighed in step (1) to obtain a primary mixture;

[0072] (3) mixing the composite dispersant weighed in step (1) with deionized water to obtain a rubber compound;

[0073] (4) adding the primary mixture obtained in step (2) to the rubber obtained in step (3), adding 3M hydrochloric acid solution to adjust the pH to 6.5, adding 30 parts by mass of 0.5 mol / L ammonium persulfate aqueous solution under stirring, continuing stirring for 30 minutes, and then continuing stirring at 2°C for 6.5 hours to obtain a secondary mixture;

[0074] (5) The secondary mixture obtained in step (4) is placed in a sand mill for sand grinding to obtain a slurry; the parameters of the sand grinding step are: rotation speed 3000 rpm, feed pressure ≤ 0.5 MPa, material temperature ≤ 60°C; sand grinding requirements: slurry viscosity: 1000~5000 mPa.S, slurry particle size D10 ≤ 1 μm, D50 ≤ 10 μm, D90 ≤ 20 μm.

[0075] (6) The slurry obtained in step (5) is homogenized, freeze-dried, and air-flow crushed to obtain a fully solid composite dry-process conductive agent; the parameters of the homogenization step are: homogenization pressure: 100 MPa, number of homogenizations: 30 times, homogenization material temperature: ≤60°C, homogenization requirements: slurry viscosity: 1000~5000 mPa.S, slurry particle size D10≤1μm, D50≤5μm, D90≤20μm; the freeze-drying parameters are: cold trap temperature ≤-50°C, vacuum degree ≤5Pa, freeze-drying requirements: sample moisture ≤1%; air-flow crushing parameters are: classifying wheel 40±10Hz, air pressure 0.6±0.2MPa, crushing requirements: powder particle size D10≤1μm, D50=3.5±1.5μm, D90≤20μm.

[0076] The preparation steps of the highly dispersed carbon black are as follows: 50 parts by mass of carbon black and 340 parts by mass of 30% hydrogen peroxide are stirred and reacted at 82° C. for 10.5 hours, cooled to room temperature after the reaction is completed, filtered, 340 parts by mass of 30% hydrogen peroxide are continuously added, stirred and reacted at 82° C. for 10.5 hours, cooled to room temperature after the reaction is completed, filtered, 340 parts by mass of 30% hydrogen peroxide are continuously added, stirred and reacted at 82° C. for 10.5 hours, cooled to room temperature after the reaction is completed, filtered, washed with deionized water until the filtrate is neutral, and dried the filter residue at 76° C. to obtain surface oxidized carbon black with a surface oxygen-containing functional group of 1.86 mmol / g; 50 parts by mass of surface oxidized carbon black, 13 parts by mass of dichlorothionyl, and 200 parts by mass of toluene are mixed and stirred for 20 minutes, then 3.6 parts by mass of triethylamine are added as an acid binding agent, reacted in an ice bath for 35 minutes, and then heated to 125° C. and continued to react for 35 minutes. min, after the reaction is completed, the reaction is filtered and unreacted thionyl chloride is removed by rotary evaporation at 85°C to obtain acyl chloride carbon black; under ice bath conditions, 50 parts by mass of acyl chloride carbon black and 300 parts by mass of toluene are mixed, stirred and dispersed for 35 minutes, followed by the addition of 3.6 parts by mass of triethylamine as an acid binding agent, followed by the addition of 18 parts by mass of lithium 2,5-diaminobenzenesulfonate, the reaction is stirred overnight, filtered, washed four times with deionized water, and dried at 80°C to obtain highly dispersed carbon black.

[0077] The preparation steps of the composite dispersant are as follows: adding 0.6 parts by mass of functionalized carboxymethyl cellulose, 3 parts by mass of lithium 2-acrylamido-2-methylpropanesulfonate, 8 parts by mass of fluorenylmethyloxycarbonyl-protected 3-aminobenzoic acid allyl ester, and 0.046 parts by mass of ammonium persulfate to 40 parts by mass of deionized water, stirring and mixing for 35 minutes, then adding 0.063 parts by mass of tetramethylethylenediamine, stirring and mixing at 5°C until uniform, and then standing at room temperature for reaction for 25 hours, then adding 80 parts by mass of methanol and 6 parts by mass of piperidine, stirring at room temperature for 19 hours, and then soaking in deionized water for 4 days to remove impurities, and changing the water every 13 hours to obtain a composite dispersant.

[0078] The functionalized carboxymethyl cellulose is prepared as follows: 0.4 mol / L sodium hydroxide aqueous solution is mixed with carboxymethyl cellulose, stirred at 82° C. until the carboxymethyl cellulose is dissolved, ultrasonically degassed and cooled to room temperature to obtain a 7.5 wt% carboxymethyl cellulose solution, then a 15 wt% propylene glycol diglycidyl ester dimethyl sulfoxide solution and histidine ester are added to the carboxymethyl cellulose solution, stirred at room temperature for 65 minutes, then kept in a 42° C. water bath for 25 hours, then allyl-1,3-sultone is added within 10 minutes, then the temperature is raised to 95° C. and the reaction is continued for 13 hours, then concentrated sulfuric acid is added and the reaction is continued at 95° C. for 11 hours, then the functionalized carboxymethyl cellulose is immersed in deionized water to remove impurities, and the water is changed every 13 hours until it becomes transparent to obtain the functionalized carboxymethyl cellulose, wherein the molar ratio of deoxyglucose units in the carboxymethyl cellulose to propylene glycol diglycidyl ester, allyl-1,3-sultone and concentrated sulfuric acid is 8:10:12:12.

[0079] (Example 4)

[0080] The difference between Example 4 and Example 2 lies in step (6), which is as follows: the slurry obtained in step (5) is homogenized, filtered, oven-dried, and airflow-pulverized to obtain a fully solid composite dry-process conductive agent; the parameters of the homogenization step are: homogenization pressure: 60 MPa, homogenization times: 20 times, homogenization material temperature: ≤60°C, homogenization requirements: slurry viscosity: 1000~5000mPa.S, slurry particle size D10≤1μm, D50≤5μm, D90≤20μm; airflow-pulverization parameters: classifying wheel 40±10Hz, air pressure 0.6±0. 2MPa, crushing requirements: powder particle size D10≤1μm, D50=3.5±1.5μm, D90≤20μm; crushing requirements: powder particle size D10≤1μm, D50=3.5±1.5μm, D90≤20μm; the filter press parameters: working pressure 0.4~1.2MPa, feed pump pressure: 0.2~0.8MPa, filter press requirements: material moisture ≤60%; the oven drying parameters: oven temperature 80~100℃, drying requirements: material moisture ≤1%, and the remaining steps and components are the same as those in Example 2.

[0081] (Comparative Example 1)

[0082] The difference between Comparative Example 1 and Example 2 is that the raw material components of the all-solid-state composite dry-process conductive agent include: 65 parts by mass of carbon nanotubes, 15 parts by mass of carbon black, 6 parts by mass of graphene, 15 parts by mass of composite dispersant, and 85 parts by mass of deionized water. The remaining steps and components are the same as those in Example 2.

[0083] (Comparative Example 2)

[0084] The difference between Comparative Example 2 and Example 2 is that the composite dispersant is obtained by free radical polymerization of carboxymethyl cellulose, lithium 2-acrylamido-2-methylpropanesulfonate, and fluorenylmethyloxycarbonyl-protected 3-aminobenzoic acid allyl ester followed by deprotection. The remaining steps and components are the same as those in Example 2.

[0085] (Comparative Example 3)

[0086] The difference between Comparative Example 3 and Example 2 is that the composite dispersant is obtained by compounding functionalized carboxymethyl cellulose and lithium 2-acrylamido-2-methylpropanesulfonate, and the remaining steps and components are the same as those in Example 2.

[0087] (Comparative Example 4)

[0088] The difference between Comparative Example 4 and Example 2 is that the raw material components of the all-solid-state composite dry-process conductive agent include: 65 parts by mass of carbon nanotubes, 15 parts by mass of highly dispersed carbon black, 6 parts by mass of graphene, 15 parts by mass of functionalized carboxymethyl cellulose, and 85 parts by mass of deionized water. The remaining steps and components are the same as those in Example 2.

[0089] (Comparative Example 5)

[0090] The difference between Comparative Example 5 and Example 2 lies in step (4). Step (4) specifically comprises: adding the primary mixture obtained in step (2) to the rubber material obtained in step (3), and mixing them uniformly to obtain a secondary mixture; the remaining steps and components are the same as those in Example 2.

[0091] (Effect example)

[0092] Electrode conductivity: Lithium iron phosphate: polyvinylidene fluoride: the all-solid-state composite dry-process conductive agent prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were formulated into a positive electrode material in a mass ratio of 8:1:1. N-methylpyrrolidone was then added for slurrying, with a slurry viscosity of 10,000 mPa·s. The slurry was then coated with 150 μm on the PET surface to avoid the influence of the current collector conductivity on the experimental results. The material was dried in a vacuum drying oven and five points were randomly tested using a four-probe resistivity tester, and the average value was taken.

[0093] Cyclic performance test:

[0094] B1 in a dry state, 3 parts by mass of lithium iron phosphate as an active material and 0.3 parts by mass of an LPS-type electrolyte as a solid electrolyte are mixed;

[0095] B2 in 0.015 parts by mass of dry state Examples 1 to 4 and Comparative Examples 1 to 5 prepared all-solid composite dry conductive agent and the material B1 were mixed;

[0096] B3 in a dry state 0.7 parts by mass of an LPS-type electrolyte as a solid electrolyte is mixed with the material B2;

[0097] B4 in a wet state 0.025 parts by mass of styrene-butadiene rubber as a binder is mixed with the material of B3;

[0098] B5 in a wet state 0.035 parts by mass of a fully solid composite dry conductive agent and styrene-butadiene rubber pre-dispersed solution containing 0.01 parts by mass of styrene-butadiene rubber are mixed with the material B4;

[0099] B6. Mix 0.015 parts by mass of styrene-butadiene rubber as a binder with the material of B5 in a wet state; then coat 150 μm on the surface of the current collector aluminum foil, dry and roll-press to form a positive electrode sheet, use a metal lithium sheet as a reference electrode, and under vacuum, disperse the solid electrolyte LPS-type electrolyte into a tetrahydrofuran solution of 5 wt% polypropylene carbonate to prepare a solid electrolyte slurry, apply the solid electrolyte slurry to the positive electrode sheet, and dry to obtain a 300 μm thick solid electrolyte layer; under vacuum conditions, superimpose the negative electrode sheet on the solid electrolyte layer, and pressurize and heat the superimposed positive electrode sheet, solid electrolyte layer and negative electrode sheet, wherein the pressure is 3 MPa, the heating temperature is 190 ° C, and the time is 5 h to obtain an all-solid-state battery; assemble the all-solid-state battery cells obtained above into button batteries, and heat them at a constant temperature of 25 ℃ Using a Xinwei battery test system (CT-4008T-5V10mA-164), with the voltage window set to 2.5-4.2V, the battery's initial discharge capacity (C0) at a 1C charge / discharge rate and its discharge capacity (C1) after 1000 cycles were tested. Cycle performance (%) = C1 / C0 × 100%. A higher cycle performance indicates better cycle performance. The maximum discharge capacity was tested.

[0100] Table 1 below shows the performance test results of the all-solid-state composite dry-process conductive agents prepared in the examples and comparative examples of the present invention:

[0101] Table 1

[0102] Conductivity (mS / mm) Maximum discharge capacity (mAh / g) Cycle performance (%) Example 1 148.93 152.26 93.2 Example 2 152.36 159.67 95.6 Example 3 151.68 154.35 94.3 Example 4 152.27 159.38 95.2 Comparative Example 1 142.74 146.28 90.2 Comparative Example 2 144.68 153.72 94.7 Comparative Example 3 151.73 158.89 91.3 Comparative Example 4 141.57 149.46 89.3 Comparative Example 5 139.46 148.47 87.5

[0103] It can be seen from Table 1 above that the electrode sheets made from the all-solid-state composite dry-process conductive agents prepared in Examples 1 to 4 and Comparative Examples 1 to 5 have good conductivity, and the all-solid-state batteries made from the electrode sheets made from the all-solid-state composite dry-process conductive agents prepared in Examples 1 to 4 and Comparative Examples 1 to 5 have high cycle stability.

[0104] The difference between Comparative Example 1 and Example 2 is that the carbon black used in the all-solid-state composite dry-process conductive agent is not modified, the conductivity of the electrode sheet made with the prepared all-solid-state composite dry-process conductive agent is weak, and the cycle stability of the prepared all-solid-state battery is weak.

[0105] The difference between Comparative Example 2 and Example 2 is that the carboxymethyl cellulose is not functionally modified, and the conductivity of the electrode sheet made from the prepared all-solid composite dry-process conductive agent is relatively weak.

[0106] The difference between Comparative Example 3 and Example 2 is that the composite dispersant is obtained by compounding functionalized carboxymethyl cellulose and 2-acrylamido-2-methylpropanesulfonic acid lithium. The conductivity of the electrode sheet made from the prepared all-solid-state composite dry-process conductive agent is weak, and the cycle stability of the prepared all-solid-state battery is weak.

[0107] The all-solid-state composite dry-process conductive agent of Comparative Example 4 and Example 2 directly uses functionalized carboxymethyl cellulose instead of a composite dispersant. The conductivity of the electrode sheet made with the obtained all-solid-state composite dry-process conductive agent is weak, and the cycle stability of the obtained all-solid-state battery is weak.

[0108] The difference between Comparative Example 5 and Example 2 is that in step (4), the rubber obtained in step (3) is directly physically mixed with the primary mixture obtained in step (2), and the conductivity of the electrode sheet made from the obtained all-solid-state composite dry-process conductive agent is weak, and the cycle stability of the obtained all-solid-state battery is weak.

[0109] Comparison of the cycle performance data of Comparative Examples 1 to 4 shows that the cycle stability of Comparative Example 3 is better than that of Comparative Example 1, the cycle stability of Comparative Example 3 is better than that of Comparative Example 4, and the cycle stability of Comparative Example 4 is better than that of Comparative Example 5. This is because the polyaniline polymer network in the all-solid composite dry-process conductive agent can form π-π interactions with graphene and carbon nanotubes, but the π-π interaction is not sufficient to prevent the active material from being stripped from the carbon surface, which easily affects the cycle performance. The present invention adopts the method of first oxidizing carbon black to form carboxyl and hydroxyl groups on the carbon black surface. The highly dispersed carbon black obtained by reacting the active groups such as acyl group with lithium 2,5-diaminobenzenesulfonate after acyl halogenation is then grafted into carboxymethyl cellulose with propylene glycol diglycidyl ester as a crosslinker, and then allyl-1,3-sultone is introduced. The composite dispersant obtained by copolymerization with lithium 2-acrylamido-2-methylpropanesulfonate and fluorenylmethyloxycarbonyl-protected 3-aminobenzoic acid allyl ester after deprotection is prepared to prepare an all-solid-state composite dry-process conductive agent. The synergistic effect occurs, which effectively improves the cycle stability of the all-solid-state battery prepared with the all-solid-state composite dry-process conductive agent.

[0110] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an all-solid composite dry-process conductive agent, characterized in that: The method comprises the following preparation steps: (1) Weighing and mixing the raw material components, wherein the raw material components mainly include: 20-80 parts by mass of carbon nanotubes, 5-20 parts by mass of highly dispersed carbon black, 1-20 parts by mass of graphene, 1-20 parts by mass of composite dispersant, and 80-90 parts by mass of deionized water; (2) uniformly mixing the carbon nanotubes, highly dispersed carbon black, and graphene weighed in step (1) to obtain a primary mixture; (3) mixing the composite dispersant weighed in step (1) with deionized water to obtain a rubber compound; (4) adding the primary mixture obtained in step (2) to the rubber obtained in step (3), adding 3M hydrochloric acid solution to adjust the pH to 6-6.5, adding 2-30 parts by mass of 0.5 mol / L ammonium persulfate aqueous solution under stirring conditions, continuing stirring for 30 minutes, and then continuing stirring at -2-2°C for 5.5-6.5 hours to obtain a secondary mixture; (5) The secondary mixture obtained in step (4) is placed in a sand mill for sand grinding to obtain a slurry; the parameters of the sand grinding step are: rotation speed 1000~3000rpm, feed pressure ≤0.5MPa, material temperature ≤60℃; sand grinding requirements: slurry viscosity: 1000~5000mPa.S, slurry particle size D10 ≤1μm, D50 ≤10μm, D90 ≤20μm; (6) The slurry obtained in step (5) is homogenized, dried, and air-flow-pulverized to obtain a fully solid composite dry-process conductive agent; the parameters of the homogenization step are: homogenization pressure: 20~100MPa, homogenization times: 5~30 times, homogenization material temperature: ≤60°C, homogenization requirements: slurry viscosity: 1000~5000mPa.S, slurry particle size D10≤1μm, D50≤5μm, D90≤20μm; air-flow-pulverization parameters: classifying wheel 40±10Hz, air pressure 0.6±0.2MPa, pulverization requirements: powder particle size D10≤1μm, D50=3.5±1.5μm, D90≤20μm; The highly dispersed carbon black is obtained by first oxidizing carbon black, then subjecting it to acyl halogenation, and finally reacting it with lithium 2,5-diaminobenzenesulfonate; the composite dispersant is obtained by copolymerizing functionalized carboxymethyl cellulose with lithium 2-acrylamido-2-methylpropanesulfonate and fluorenylmethoxycarbonyl-protected allyl 3-aminobenzoate, followed by deprotection; and the functionalized carboxymethyl cellulose is obtained by grafting histidine ester onto carboxymethyl cellulose using propylene glycol diglycidyl as a crosslinker, and then introducing propenyl-1,3-sultone.

2. The method for preparing the all-solid composite dry-process conductive agent according to claim 1, characterized in that: The preparation steps of the highly dispersed carbon black are as follows: 50 parts by mass of carbon black and 330-340 parts by mass of 30% hydrogen peroxide are stirred and reacted at 78-82° C. for 9.5-10.5 hours, after the reaction is completed, the mixture is cooled to room temperature and filtered, 330-340 parts by mass of 30% hydrogen peroxide are continuously added and stirred and reacted at 78-82° C. for 9.5-10.5 hours, after the reaction is completed, the mixture is cooled to room temperature and filtered, 330-340 parts by mass of 30% hydrogen peroxide are continuously added and stirred and reacted at 78-82° C. for 9.5-10.5 hours, after the reaction is completed, the mixture is cooled to room temperature and filtered, and 330-340 parts by mass of 30% hydrogen peroxide are continuously added and stirred and reacted at 78-82° C. The reaction was carried out for 9.5 to 10.5 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered. The mixture was washed with deionized water until the filtrate was neutral. The filter residue was dried at 74 to 76 ° C to obtain surface oxidized carbon black with a surface oxygen functional group of 1.85 to 1.86 mmol / g. 50 parts by mass of surface oxidized carbon black, 12 to 13 parts by mass of thionyl chloride, and 200 parts by mass of toluene were mixed and stirred for 10 to 20 minutes, and then 3.4 to 3.6 parts by mass of triethylamine was added as an acid binding agent. The mixture was reacted in an ice bath for 25 to 35 minutes. min, then heated to 115-125°C and continued to react for 25-35 min. After the reaction, filtered, and rotary evaporated at 75-85°C to remove unreacted dichloride to obtain acyl chloride carbon black; under ice bath conditions, 50 parts by mass of acyl chloride carbon black and 200-300 parts by mass of toluene were mixed, stirred and dispersed for 25-35 min, and then 3.4-3.6 parts by mass of triethylamine were added as an acid binding agent, followed by adding 17-18 parts by mass of lithium 2,5-diaminobenzenesulfonate, stirred and reacted overnight, filtered, washed with deionized water 2-4 times, and dried at 70-80°C to obtain highly dispersed carbon black.

3. The method for preparing the all-solid composite dry-process conductive agent according to claim 1, characterized in that: The preparation steps of the composite dispersant are as follows: adding 0.4-0.6 parts by mass of functionalized carboxymethyl cellulose, 2-3 parts by mass of lithium 2-acrylamido-2-methylpropanesulfonate, 7-8 parts by mass of fluorenylmethyloxycarbonyl-protected 3-aminobenzoic acid allyl ester, and 0.045-0.046 parts by mass of ammonium persulfate to 30-40 parts by mass of deionized water, stirring and mixing for 25-35 minutes, then adding 0.062-0.063 parts by mass of tetramethylethylenediamine, stirring and mixing at 0-5°C until uniform, and then standing at room temperature for reaction for 23-25 ​​hours, then adding 80 parts by mass of methanol and 5-6 parts by mass of piperidine, stirring at room temperature for 17-19 hours, and then soaking in deionized water for 2-4 days to remove impurities, and changing the water every 11-13 hours to obtain the composite dispersant.

4. The method for preparing the all-solid composite dry-process conductive agent according to claim 1, characterized in that: The functionalized carboxymethyl cellulose is prepared as follows: 0.4 mol / L sodium hydroxide aqueous solution is mixed with carboxymethyl cellulose, stirred at 78-82° C. until the carboxymethyl cellulose is dissolved, subjected to ultrasonic degassing and cooled to room temperature to obtain a 6.5-7.5 wt% carboxymethyl cellulose solution, and then a 15 wt% dimethyl sulfoxide solution of propylene glycol diglycidyl ester and histidine ester are added to the carboxymethyl cellulose solution, stirred at room temperature for 55-65 minutes, then kept in a water bath at 38-42° C. for 23-25 ​​hours, and then added Propylene-1,3-sultone is added within 10 minutes, and then the temperature is raised to 85-95°C and the reaction is continued for 11-13 hours. Then concentrated sulfuric acid is added and the reaction is continued at 85-95°C for 9-11 hours. Then, it is immersed in deionized water to remove impurities, and the water is changed every 11-13 hours until it becomes transparent to obtain functionalized carboxymethyl cellulose, wherein the molar ratio of deoxyglucose units in the carboxymethyl cellulose to propylene glycol diglycidate, propenyl-1,3-sultone, and concentrated sulfuric acid is 8:8-10:10-12:10-12.

5. The method for preparing the all-solid composite dry-process conductive agent according to claim 1, characterized in that: The drying step is freeze drying; the freeze drying parameters are: cold trap temperature ≤-50°C, vacuum degree ≤5Pa, and freeze drying requirements: sample moisture ≤1%.

6. The method for preparing the all-solid composite dry-process conductive agent according to claim 1, characterized in that: The drying step is to first perform filter pressing and then place the material in an oven for drying; the filter pressing parameters are: working pressure 0.4~1.2MPa, feed pump pressure: 0.2~0.8MPa, filter pressing requirement: material moisture ≤60%; the oven drying parameters are: oven temperature 80~100℃, drying requirement: material moisture ≤1%.

7. An all-solid composite dry-process conductive agent, characterized in that: The all-solid-state composite dry-process conductive agent is prepared according to the preparation method of the all-solid-state composite dry-process conductive agent according to any one of claims 1 to 6.

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