Preparation method of composite conductive paste for high-energy density power battery
By constructing a composite conductive paste using carbon-coated nanoporous silica, single-walled CNTs, and graphene in lithium-ion batteries, the problem of electron and lithium-ion transport in thick electrodes was solved, improving the battery's electronic conductivity and lithium-ion migration ability, and extending the battery's cycle life and capacity.
Patent Information
- Application Number
- CN202511770746.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-02-13
AI Technical Summary
The thick electrodes of existing lithium-ion batteries suffer from electrochemical polarization problems in terms of electron and lithium-ion migration and transport, resulting in limited battery capacity and reduced cycle life. Traditional conductive agents cannot construct long-distance, high-speed electron transport channels, and the electrolyte penetration capacity is insufficient.
Carbon-coated nanoporous silica was used as a carrier to form a highly efficient three-dimensional electron transport network by combining single-walled CNTs and graphene, and carbon black with high specific surface area was added to construct a composite conductive paste to improve electronic conductivity and lithium-ion migration capability.
It improves the battery's electronic conductivity and lithium-ion transport efficiency, reduces electrochemical polarization resistance, extends battery cycle life, and increases battery capacity.
Smart Images
Figure CN121528641A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high energy density power battery technology, specifically relating to a method for preparing a composite conductive slurry for high energy density power batteries. Background Technology
[0002] With the rapid development of new energy electric vehicles and energy storage systems, the market demand for high-energy-density batteries is increasing, requiring battery systems to provide longer driving ranges and faster charging speeds to reach the level of internal combustion engine vehicles. On the one hand, traditional lithium-ion battery electrode fabrication methods mainly employ thin electrode designs, limiting the loading of active materials and thus restricting the battery's energy storage capacity. Thick electrode technology will become a new means to overcome these limitations. Increasing electrode thickness and improving the mass loading of active materials can reduce the proportion of inactive components such as separators and current collectors, significantly improving the overall energy density of the battery. This is crucial for achieving longer driving ranges in electric vehicles and enhancing the energy storage capacity of energy storage systems. On the other hand, novel battery technologies such as solid-state batteries, lithium-air batteries, and lithium-sulfur batteries are still in the research and development stage and are some distance from true industrialization. Summary of the Invention
[0003] To address the problems in the prior art, this invention provides a method for preparing a composite conductive slurry for high energy density power batteries, achieving the goal of improving battery capacity and cycle life by providing a conductive slurry with high electronic conductivity and high lithium-ion migration.
[0004] The technical problem solved by this invention is achieved by the following technical solution:
[0005] The present invention aims to provide a method for preparing a composite conductive slurry for high energy density power batteries, comprising the following steps:
[0006] (1) Modification of nano-porous silica: Organic polymers are added to deionized water and stirred to dissolve. Then nano-porous silica is added to form a solution. After grinding, drying and carbonization, carbon-coated silica material is obtained.
[0007] (2) Preparation of conductive paste: In NMP, a high molecular surfactant and a small molecular surfactant are added, and then carbon nanoparticle conductive powders such as graphene, single-walled CNT and carbon black are added respectively. After homogeneous dispersion, carbon nanoparticle conductive paste is obtained.
[0008] (3) Preparation of composite slurry: Add the carbon-coated silicon dioxide material obtained in (1) to the conductive slurry in (2), grind, disperse and mix evenly to obtain a high-energy-density power battery composite conductive slurry.
[0009] Currently, the most reliable solution to improve the high energy density of batteries is to increase the loading and proportion of active materials per unit area. However, such thick electrodes face many electrochemical challenges, such as longer migration and transport paths for electrons and lithium ions, increased electrochemical polarization resistance, which is not conducive to the battery's capacity utilization and causes rapid degradation of cycle life. The core reason is that traditional conductive agents cannot build long-distance high-speed electron transport channels and rapid electrolyte penetration in thick electrodes, thus causing uneven distribution of electron transport and ion diffusion coefficients inside the electrode.
[0010] Therefore, a conductive paste with high electronic conductivity and high lithium-ion migration is needed to solve the electrochemical polarization problem of thick electrodes, thereby improving battery capacity and cycle life.
[0011] To improve the electronic conductivity and ion transport of existing conductive pastes in thick electrodes, this invention first selects carbon-coated nanoporous silica as a carrier for efficiently adsorbing battery electrolyte, providing excellent ion transport channels and wetting performance for thick electrodes, improving the ion diffusion coefficient, and reducing charge transfer and mass transfer impedance. It possesses chemical stability, high specific surface area, and a large mesoporous structure, and can react with HF generated in the electrolyte, thus avoiding the corrosion and damage of electrode materials by HF, further improving the stability of the electrode structure. Secondly, in terms of electronic transport, a highly efficient three-dimensional electronic transport network model is created. Single-walled CNTs and graphene advanced conductive materials are used as the central hub of the electronic transport network, running through the entire thickness direction of the electrode, providing strong support for electron transport between particles. Its special ultrathin flexible structure can form a more stable PEI film for the electrode and enhance the interaction force with the active material. Electrons can be uniformly distributed throughout the entire electrode, avoiding local polarization. Simultaneously, due to close contact with the electrode material, it can alleviate the stress and volume changes caused by charge-discharge expansion of the electrode, preventing the "island" effect of particles. Meanwhile, in order to further improve the reaction rate of electrons and ions on the surface of electrode particles, high specific surface area carbon black is added to this scheme as an electron transporter on the particle surface, so as to increase the contact area between the particles and the conductive carbon black, so as to achieve a relatively ideal state for electrons in both short and long ranges.
[0012] Furthermore, the mass ratio of organic polymer to nano-porous silica is 10%-20%: 80%-90%; the solid content of the solution is 5-10%, and the viscosity is <1000cp.
[0013] Furthermore, the particle size D50 of the nano-porous silica is 10-100 nm, and the specific surface area is 700-1200 m². 2 / g, with mesopore sizes of 10-50nm; the organic polymers used are phenolic resins or polyvinyl alcohols. These organic materials have good film-forming properties and can be uniformly adsorbed on the surface of porous silica to form a stable adsorption layer.
[0014] Further, in step (1), a nano-grinding mill is used for grinding. The size of the nano-grinding beads is 0.6-1mm, the rotation speed is 1000-3000rpm, and the grinding time is ≥2h. The ground slurry is granulated and dried using a spray granulation device. The inlet temperature is controlled at 190-210℃, and the outlet temperature is controlled at 90-100℃. The dried powder is carbonized at high temperature using a box furnace or tube furnace. The required gas environment is an inert atmosphere, such as nitrogen or argon. The high-temperature carbonization temperature is 600-700℃, and the carbonization time is ≥2h.
[0015] Furthermore, the mass ratio of polymeric surfactant: small molecule surfactant: graphene: single-walled CNT: carbon black is 15%-25%: 5%-10%: 15%-25%: 5%-10%: 35%-60%.
[0016] Furthermore, the high molecular surfactant is one or more of polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), and hydrogenated nitrile butadiene rubber (HNBR); the low molecular surfactant is ethanolamine or piperazine.
[0017] Furthermore, the graphene used is reduced-oxidation graphene with a specific surface area of 300-500 m². 2 / g, with a D50 of 10-30μm and a carbon content ≥98%; single-walled CNTs have a specific surface area ≥700m². 2 / g, tube diameter 1-3nm, length ≥5um, carbon content ≥98%, G / D ratio ≥60; specific surface area of carbon black ≥100m² 2 / g, oil absorption value ≥180mL / 100g, carbon content ≥99.9%.
[0018] Furthermore, in step (2), a high-pressure homogenizer is used for homogenization. The pressure of the high-pressure homogenizer is ≥800 bar, and the homogenization cycle is ≥5 times. The resulting carbon nanotube conductive slurry has a viscosity of <5000 cp, a particle size D50 of 2-5 μm, and a solid content of 3-8%.
[0019] Furthermore, in step (3) of the composite slurry preparation, the mass ratio of powder to carbon-coated silica in the conductive slurry is 80%-95%: 5%-20%.
[0020] Furthermore, in step (3), a nano-grinding mill is used for grinding. The size of the nano-grinding beads is 0.6-1mm, the rotation speed is 1000-3000rpm, and the grinding time is ≥2h.
[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:
[0022] 1. Adding nano-sized porous silica material, which has abundant mesoporous structure and high specific surface area, can efficiently adsorb electrolyte, providing a fast channel for lithium ion transport and migration inside the electrode, and solving the lithium ion mass transfer problem caused by electrode thickness.
[0023] 2. Carbon coating technology is used to modify nano-porous silica materials to improve their intrinsic non-conductivity, enhance their reaction kinetics inside the electrode, and reduce the internal resistance of the electrode.
[0024] 3. Construct a ternary composite conductive paste system to fully leverage the synergistic advantages of each component. Utilize the one-dimensional linear and two-dimensional sheet structures of single-walled CNTs and graphene to act as efficient network nodes, significantly inhibiting high electron conductivity transport and volume expansion; while the selected carbon black with high specific surface area and high structural integrity constructs diverse conductive network fulcrums on the particle surface, providing more active sites for rapid electron-ion reactions, reducing charge transfer resistance, and minimizing polarization.
[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. Furthermore, in order to make the above contents, objectives, features and advantages of the present invention more obvious and understandable, specific embodiments of the present invention are described below. Attached Figure Description
[0026] Figure 1 This is a physical image of the high-energy-density composite conductive slurry for power batteries according to the present invention. Detailed Implementation
[0027] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.
[0028] In addition, unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or prepared by existing methods.
[0029] Example 1
[0030] A method for preparing a composite conductive slurry for high-energy-density power batteries, comprising the following steps:
[0031] (1) Modification with nanoscale porous silica:
[0032] In a 2L stainless steel container, first add 1380g of deionized water, then add 18g of phenolic resin and dissolve it completely. Next, add 102g of nano-porous silica with a surface area of 910m². 2 The silica particles, with a particle size D50 of 30 nm and a mesopore size of 30 nm, were fully wetted and pre-dispersed in solution using a high-speed disperser. They were then ground for 3 hours using a nano-mill with 0.8 mm beads at 1800 rpm. The resulting slurry was granulated and dried using a spray granulator. The dried powder was then carbonized at 650°C for 3 hours in a tube furnace to obtain carbon-coated nanoporous silica material. The carbonization process was carried out under nitrogen protection.
[0033] (2) Preparation of conductive paste:
[0034] In a solvent of 1900g NMP, 10g of the small molecule surfactant ethanolamine and 20g of the high molecule surfactant hydrogenated nitrile butadiene rubber (HNBR) were first added and stirred until fully dissolved. Then, 20g of graphene, 10g of single-walled CNT powder, and 50g of high specific surface area carbon black were added. After thorough stirring and wetting, the mixture was uniformly dispersed using a high-pressure homogenizer at a pressure of 900 bar. The homogenization cycle was 7 times to obtain a conductive paste with a solid content of 5% and a carbon content of 4%. The specific surface area of the graphene powder was 380 μm. 2 / g, D50 particle size is 25um, carbon content is 98.5%; single-walled CNT powder has a specific surface area of 960m². 2 / g, tube diameter 2nm, length 7um, carbon content 99.1%, G / D ratio 95; carbon black specific surface area 130m² 2 / g, oil absorption value is 210mL / 100g, carbon content is 99.95%.
[0035] (3) Preparation of composite slurry:
[0036] Take 1000g of the conductive slurry from (2), add 10g of the coated nano-porous silica material prepared in (1), and then add 190g of NMP solvent. After stirring and pre-dispersing, grind the mixture using a nano-grinding mill for 4 hours to obtain a conductive slurry with a solid content of 5%. The grinding equipment used a ball size of 0.8mm and a rotation speed of 1800rpm.
[0037] Example 2
[0038] A method for preparing a composite conductive slurry for high-energy-density power batteries, comprising the following steps:
[0039] (1) Modification with nanoscale porous silica:
[0040] In a 2L stainless steel container, first add 1380g of deionized water, then add 12g of polyethylene glycol and dissolve it completely. Next, add 108g of nano-porous silica with a surface area of 700m². 2 The silica material has a particle size (D50) of 10 nm and a mesopore size of 10 nm. It is fully wetted and pre-dispersed in solution using a high-speed disperser; then ground for 2 hours using a nano-mill with 0.6 mm beads at 1000 rpm. The resulting slurry is granulated and dried using a spray granulator. The dried powder is then carbonized at 600°C for 2 hours in a tube furnace to obtain carbon-coated nanoporous silica material. The carbonization process is performed under argon protection.
[0041] (2) Preparation of conductive paste:
[0042] In a solvent of 1900g NMP, 5g of the small molecule surfactant piperazine and 15g of the high molecule surfactant polyvinylpyrrolidone (PVP) were first added and stirred until fully dissolved. Then, 15g of graphene, 5g of single-walled CNT powder, and 60g of high specific surface area carbon black were added. After thorough stirring and wetting, the mixture was uniformly dispersed using a high-pressure homogenizer at a pressure of 800 bar. The homogenization cycle was 5 times to obtain a conductive slurry with a solid content of 3% and a carbon content of 3%. The specific surface area of the graphene powder was 300 μm. 2 / g, D50 particle size is 10um, carbon content is 98%; single-walled CNT powder has a specific surface area of 700m². 2 / g, tube diameter 1nm, length 5um, carbon content 98%, G / D ratio 60; carbon black specific surface area 100m² 2 / g, oil absorption value is 180mL / 100g, carbon content is 99.9%.
[0043] (3) Preparation of composite slurry:
[0044] Take 1000g of the conductive slurry from (2), add 20g of the coated nano-porous silica material prepared in (1), and then add 190g of NMP solvent. After stirring and pre-dispersing, grind the mixture using a nano-grinding mill for 2 hours to obtain a conductive slurry with a solid content of 4%. The grinding equipment used a ball size of 0.6mm and a rotation speed of 1000rpm.
[0045] Example 3
[0046] A method for preparing a composite conductive slurry for high-energy-density power batteries, comprising the following steps:
[0047] (1) Modification with nanoscale porous silica:
[0048] In a 2L stainless steel container, first add 1380g of deionized water, then add 20g of phenolic resin and dissolve it completely. Finally, add 100g of nano-porous silica with a surface area of 1200m². 2 The silica particles, with a particle size D50 of 100 nm and a mesopore size of 50 nm, were thoroughly wetted and pre-dispersed in solution using a high-speed disperser. They were then milled for 5 hours using a nano-mill with 1 mm beads at 3000 rpm. The resulting slurry was granulated and dried using a spray granulator. The dried powder was then carbonized at 700°C for 5 hours in a tube furnace to obtain carbon-coated nanoporous silica material under nitrogen protection.
[0049] (2) Preparation of conductive paste:
[0050] In a solvent of 1900g NMP, 10g of the small molecule surfactant ethanolamine and 20g of the high molecule surfactant polyvinylidene fluoride (PVDF) were first added and stirred until fully dissolved. Then, 25g of graphene, 10g of single-walled CNT powder, and 35g of high specific surface area carbon black were added. After thorough stirring and wetting, the mixture was uniformly dispersed using a high-pressure homogenizer at a pressure of 1000 bar. The homogenization cycle was 9 times to obtain a conductive slurry with a solid content of 7% and a carbon content of 6%. The specific surface area of the graphene powder was 500 μm. 2 / g, D50 particle size is 30um, carbon content is 99.5%; single-walled CNT powder has a specific surface area of 1000m². 2 / g, tube diameter 3nm, length 8um, carbon content 99.3%, G / D ratio 96; carbon black specific surface area 150m² 2 / g, oil absorption value is 240mL / 100g, carbon content is 99.96%.
[0051] (3) Preparation of composite slurry:
[0052] Take 1000g of the conductive slurry from (2), add 5g of the coated nano-porous silica material prepared in (1), and then add 95g of NMP solvent. After stirring and pre-dispersing, grind the mixture using a nano-grinding mill for 4 hours to obtain a conductive slurry with a solid content of 5%. The grinding equipment uses 1mm ball beads and a rotation speed of 3000rpm.
[0053] Comparative Example 1
[0054] The difference between this comparative example and Example 1 is that no polymeric organic matter is added in step (1) to modify the nano-porous silica with carbon coating, and nano-porous silica is directly added in step (3). The rest are the same as in Example 1.
[0055] Comparative Example 2
[0056] The difference between this comparative example and Example 1 is that, in step (2) of this comparative example, instead of adding single-walled CNTs, ordinary multi-walled CNTs with a specific surface area of 250 m² are added. 2 / g, tube diameter 5-15nm, G / D ratio 0.9-1.0, carbon content 99.3%.
[0057] Comparative Example 3
[0058] The difference between this comparative example and Example 1 is that, in step (2) of this comparative example, no graphene is added; instead, ordinary multi-walled CNTs with a specific surface area of 250 m² are added. 2 / g, tube diameter 5-15nm, G / D ratio 0.9-1.0, carbon content 99.3%.
[0059] Comparative Example 4
[0060] The difference between this comparative example and Example 1 is that, in step (2) of this comparative example, instead of adding carbon black, ordinary multi-walled CNTs with a specific surface area of 250 m² are added. 2 / g, tube diameter 5-15nm, G / D ratio 0.9-1.0, carbon content 99.3%.
[0061] Comparative Example 5
[0062] The difference between this comparative example and Example 1 is that in step (3), carbon-coated modified nanoporous silica material is not added to this comparative example.
[0063] Test case
[0064] The conductive slurries obtained in Examples 1-3 and Comparative Examples 1-5 were mixed with lithium-ion battery polycrystalline nickel-cobalt-manganese (NCM523) cathode material and PVDF at a mass ratio of 1.5:97:1.5 in NMP solvent to prepare a slurry, where the mass of NMP was 0.6-0.7 times the mass of the solids. The slurry was coated onto a 16µm thick aluminum foil and a 60µm thick PET film using a 400µm doctor blade, and then dried, rolled, and punched into 12mm diameter button discs. The resistivity of the PEI film discs was measured using a four-probe resistivity meter. A lithium foil was used as the counter electrode, and the above-prepared aluminum foil button discs were assembled into a 2032 button cell. The main components of the battery electrolyte were: lithium hexafluorophosphate (1.0mol / L) as the lithium salt; and ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate (MEC) as the solvent, in a mass ratio of 1:1:1. The separator was a 20µm thick polyethylene microporous membrane. The battery's initial charge / discharge capacity was tested at a 0.1C rate, and its initial charge / discharge efficiency was calculated. Cycle performance was tested at a 1C rate for 100 cycles (Note: the specific capacity of the nickel-cobalt-manganese (NCM523) cathode material was calculated based on 155 mAh / g). The battery's charge / discharge cutoff voltage was 2.75–4.2V. The test results are shown in the table below:
[0065] Table 1. Film resistivity of Examples 1-3 and Comparative Examples 1-5 in Nickel-Cobalt-Manganese (NCM523) cathode material
[0066]
[0067] As can be seen from the resistivity test data in Table 1, the composite conductive paste of this invention exhibits excellent electronic conductivity in nickel-cobalt-manganese (NCM523) cathode materials. This is mainly due to the combined use of single-walled and graphene conductive materials. Their unique one-dimensional linear and two-dimensional layered structures allow them to penetrate the entire thickness of the electrode, resulting in a highly efficient electron transport network between electrode particles. Furthermore, the single-walled and graphene materials possess extremely high specific surface areas and strong interactions with the electrode particles, maintaining a stable conductive network. While multi-walled CNTs have good electronic conductivity, their numerous defects and phonon scattering interference between the wall layers significantly reduce electron transport distance and efficiency compared to single-walled and graphene materials. Simultaneously, nanoscale porous silica materials, without carbon coating modification, also exhibit high resistivity, significantly hindering electron transport.
[0068] Table 2. Results of the first discharge and cycle tests for Examples 1-3 and Comparative Examples 1-5
[0069]
[0070] As shown in Table 2 above, the composite conductive paste of this invention exhibits higher initial charge-discharge efficiency in thick electrodes of nickel-cobalt-manganese (NCM523) cathode materials, approximately 2% higher than the comparative group. This is because a more perfect electron and ion network is constructed in the electrode, reducing internal polarization resistance and improving electrode reaction kinetics. Simultaneously, the capacity does not show significant decay after 100 cycles at 1C, while the batteries in Comparative Examples 1-5 experienced more severe decay due to electrode thickness issues. The good cycle stability is also attributed to the physical encapsulation and strong interaction between the single-walled structure and graphene on the electrode active material. Furthermore, the added carbon-coated modified carbon nanofiber silica material can react with HF generated in the electrolyte, preventing HF from corroding the electrode material surface and damaging the PEI film layer of the cathode, thus avoiding increased electrode resistance, increased difficulty in lithium-ion diffusion, and consequently, rapid cycle life decay.
[0071] In terms of electrode ion transport, carbon-coated nanoscale porous silica serves as a carrier for highly efficient adsorption of battery electrolytes, providing excellent ion transport channels and wetting properties for thick electrodes, improving the ion diffusion coefficient, and reducing charge transfer and mass transfer impedance. It possesses chemical stability, high specific surface area, and a large mesoporous structure, and can react with HF generated in the electrolyte, thus preventing HF from corroding and damaging the electrode material, further improving the stability of the electrode structure. Regarding electrode electron transport, both graphene and single-walled CNTs exhibit excellent electronic conductivity, good electrochemical and thermal stability, and low charge transfer impedance. The two-dimensional sheets of graphene and the one-dimensional linear structure of single-walled CNTs together create a long-range ordered conductive network, while their strong interaction with the electrode active material provides robust mechanical support for buffering the expansion stress of the electrode material and battery cycling.
[0072] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.
[0073] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.
Claims
1. A method for preparing a composite conductive slurry for high-energy-density power batteries, characterized in that, Includes the following steps: (1) Modification of nano-porous silica: Organic polymers are added to deionized water and stirred to dissolve. Then nano-porous silica is added to form a solution. After grinding, drying and carbonization, carbon-coated silica material is obtained. (2) Preparation of conductive paste: In NMP, a high molecular surfactant and a small molecular surfactant are added, and then carbon nanoparticle conductive powders such as graphene, single-walled CNT and carbon black are added respectively. After homogeneous dispersion, carbon nanoparticle conductive paste is obtained. (3) Preparation of composite slurry: Add the carbon-coated silicon dioxide material obtained in (1) to the conductive slurry in (2), grind, disperse and mix evenly to obtain a high-energy-density power battery composite conductive slurry.
2. The method for preparing a composite conductive slurry for high-energy-density power batteries as described in claim 1, characterized in that: The mass ratio of organic polymer to nano-porous silica is 10%-20%: 80%-90%; the solid content of the solution is 5-10%, and the viscosity is <1000cp.
3. The method for preparing a composite conductive slurry for high-energy-density power batteries as described in claim 2, characterized in that: Nanoscale porous silica has a particle size D50 of 10-100 nm and a specific surface area of 700-1200 m². 2 / g, with mesopore size of 10-50nm; organic polymers are phenolic resins or polyvinyl alcohols.
4. The method for preparing a composite conductive slurry for high-energy-density power batteries as described in claim 3, characterized in that: In step (1), a nano-grinding mill is used for grinding. The size of the nano-grinding beads is 0.6-1mm, the rotation speed is 1000-3000rpm, and the grinding time is ≥2h. The ground slurry is granulated and dried using a spray granulation device. The inlet temperature is controlled at 190-210℃ and the outlet temperature is controlled at 90-100℃. The dried powder is carbonized at high temperature using a box furnace or tube furnace. The required gas environment is an inert atmosphere. The high-temperature carbonization temperature is 600-700℃, and the carbonization time is ≥2h.
5. The method for preparing a composite conductive slurry for high-energy-density power batteries as described in claim 1, characterized in that: The mass ratio of polymeric surfactant: small molecule surfactant: graphene: single-walled CNT: carbon black is 15%-25%: 5%-10%: 15%-25%: 5%-10%: 35%-60%.
6. The method for preparing a high-energy-density power battery composite conductive slurry as described in claim 1, characterized in that: The high molecular surfactant is one or more of polyvinylpyrrolidone, polyvinylidene fluoride and hydrogenated nitrile rubber; the low molecular surfactant is ethanolamine or piperazine.
7. The method for preparing a composite conductive slurry for high-energy-density power batteries as described in claim 1, characterized in that: The graphene used is reduced graphene oxide, with a specific surface area of 300-500 m². 2 / g, with a D50 of 10-30μm and a carbon content ≥98%; single-walled CNTs have a specific surface area ≥700m². 2 / g, tube diameter 1-3nm, length ≥5um, carbon content ≥98%, G / D ratio ≥60; specific surface area of carbon black ≥100m² 2 / g, oil absorption value ≥180mL / 100g, carbon content ≥99.9%.
8. The method for preparing a composite conductive slurry for high-energy-density power batteries as described in claim 1, characterized in that: In step (2), a high-pressure homogenizer is used for homogenization. The pressure of the high-pressure homogenizer is ≥800 bar, and the homogenization cycle is ≥5 times. The resulting carbon nanotube conductive slurry has a viscosity of <5000cp, a particle size D50 of 2-5um, and a solid content of 3-8%.
9. The method for preparing a composite conductive slurry for high-energy-density power batteries as described in claim 1, characterized in that: In step (3) of the composite slurry preparation, the mass ratio of powder to carbon-coated silica in the conductive slurry is 80%-95%: 5%-20%.
10. The method for preparing a high-energy-density power battery composite conductive slurry as described in claim 9, characterized in that: In step (3), a nano-grinding mill is used for grinding. The size of the nano-grinding beads is 0.6-1mm, the rotation speed is 1000-3000rpm, and the grinding time is ≥2h.