High-conductivity composite conductive paste and preparation method thereof
By constructing a hierarchical conductive structure using carbon nanotubes, graphene, and vapor-grown carbon fibers, and combining purified conductive polymers and ionic liquids, the problems of easy agglomeration and difficult dispersion of conductive agents were solved, achieving efficient electron conduction and improved battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-03-27
AI Technical Summary
Existing conductive agents such as carbon black have low conductivity, and carbon nanotubes and graphene are prone to agglomeration and difficult to disperse. The conductive network of a single material has dimensional defects, making it difficult to meet the conductivity requirements of high-energy-density lithium-ion batteries.
A hierarchical conductive structure was constructed using carbon nanotubes, graphene, and vapor-grown carbon fibers. Combined with purified conductive polymers and ionic liquids, a composite conductive slurry was prepared using ultrasonic, shearing, and high-pressure homogenization techniques to form a stable three-dimensional conductive network.
This achieves an efficient electronic conduction path, reduces contact resistance, improves the conductivity, flexibility, and structural stability of the electrodes, and enhances the rate performance and cycle performance of the battery.
Smart Images
Figure CN121748031A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of conductive agent technology, and more specifically, to a highly conductive composite conductive paste and its preparation method. Background Technology
[0002] Currently, lithium-ion batteries are developing towards higher energy density and higher power density, which places higher demands on the conductivity of electrodes. Therefore, conductive agents in lithium-ion batteries need higher performance to match the high-performance lithium-ion batteries. Traditional conductive agents, such as carbon black, have low conductivity due to their point contact mode. Although one-dimensional and two-dimensional nanomaterials such as carbon nanotubes and graphene can construct more efficient conductive networks, they are prone to agglomeration and are difficult to disperse in slurries, and the conductive networks of single materials have dimensional defects. Single-walled carbon nanotubes are gradually becoming ideal materials for conductive agents due to their high graphitization, but they usually have a large specific surface area and high oil absorption value, making them difficult to disperse. Therefore, developing a composite conductive slurry that can fully utilize the synergistic effect of carbon materials of different dimensions and has both high conductivity and excellent dispersion stability is the key to improving battery performance. Summary of the Invention
[0003] To address the shortcomings of existing technologies, the present invention aims to provide a highly conductive composite conductive paste and its preparation method.
[0004] To achieve the above objectives, the present invention provides the following technical solution: A highly conductive composite conductive paste, comprising the following components by weight: 5-15 parts carbon nanotube powder, 10-20 parts graphene powder, 5-15 parts vapor-grown carbon fiber, 2-6 parts purified conductive polymer dispersion, 1-3 parts 1-butyl-3-methylimidazolium tetrafluoroborate, 0.5-1.5 parts hydrogenated nitrile butadiene rubber, 0.2-0.6 parts potassium perfluorooctyl sulfonate, 0.3-0.5 parts 3-aminopropyltriethoxysilane, 90-120 parts N-methylpyrrolidone, and 60-80 parts deionized water.
[0005] Furthermore, the carbon nanotube powder includes at least one of multi-walled carbon nanotube powder, oligo-walled carbon nanotube powder, and single-walled carbon nanotube powder.
[0006] Furthermore, the graphene powder has 5 to 15 layers.
[0007] Furthermore, the diameter of the vapor-grown carbon fiber is 60~100nm and the length is 5~15μm.
[0008] Furthermore, the method for preparing the purified conductive polymer dispersion includes the following steps: After thoroughly washing the strong acid cation exchange resin with deionized water, it was activated with hydrochloric acid, washed with deionized water until neutral, and then packed into a glass exchange column. Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate was mixed with deionized water and stirred evenly, and then slowly passed through the glass exchange column. The effluent was collected to obtain a purified conductive polymer dispersion.
[0009] Furthermore, the mass ratio of the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate to deionized water is 1:20~40.
[0010] Furthermore, the flow rate within the glass exchange column is 1~2 BV / h.
[0011] Furthermore, the preparation method of the highly conductive composite conductive paste includes the following steps: (1) Weigh each raw material component according to its weight percentage; (2) Add carbon nanotubes, vapor-grown carbon fibers and graphene to 1 / 3 of N-methylpyrrolidone, and sonicate in a probe-type ultrasonic cell disruptor with a power of 500~1000W for 30~90min to obtain a primary dispersion. (3) Mix the purified conductive polymer dispersion, 1 / 3 of N-methylpyrrolidone and deionized water and stir until homogeneous. Add 1-butyl-3-methylimidazolium tetrafluoroborate and stir at 200-400 rpm for 1-3 hours at 25-40°C to obtain a solution. (4) Add hydrogenated nitrile rubber to the remaining 1 / 3 of N-methylpyrrolidone, and stir at 300-500 rpm for 4-12 hours at 50-70°C to obtain a homogeneous and viscous mixture. (5) Slowly add the primary dispersion to the solution, place it under a high-speed shear emulsifier, slowly add the mixture at a rate of 0.5~1.5mL / min, and shear disperse at a speed of 8000~15000rpm for 90~120min, control the system temperature at 30~40℃, and obtain the composite slurry. (6) Add potassium perfluorooctyl sulfonate and 3-aminopropyltriethoxysilane to the composite slurry, place it in a high-pressure homogenizer, and homogenize it for 5 to 15 times under a pressure of 80 to 150 MPa to obtain a highly conductive composite conductive slurry.
[0012] In summary, this application includes at least the following beneficial effects: (1) This scheme uses carbon nanotubes, graphene powder, and vapor-grown carbon fibers as raw materials to construct a hierarchical conductive structure for a conductive slurry system. With its large specific surface area, few-layer graphene forms a flexible, continuous two-dimensional conductive substrate in the slurry, providing a path for rapid in-plane charge transport. Graphene sheets effectively isolate carbon nanotubes and vapor-grown carbon fibers, preventing their direct aggregation and providing them with a plane for attachment. Carbon nanotubes are interspersed between and on the graphene sheets. They can connect points separated by graphene at relatively long distances, forming a longitudinal conductive pathway that runs through the entire electrode thickness, and their high elasticity and toughness endow the network with a certain degree of resistance to deformation. The rigid structure of vapor-grown carbon fibers can effectively expand the graphene sheets, preventing irreversible stacking during drying and compaction, and maintaining the porous structure. Simultaneously, the length and diameter of the vapor-grown carbon fibers allow them to span multiple aggregates of carbon nanotubes and graphene, establishing a long-range conductive backbone network. Carbon nanotubes and vapor-grown carbon fibers form a complementary "linear" system. Carbon nanotubes solve the connection of nanoscale gaps, while vapor-grown carbon fibers solve the connection of micrometer-scale regions. Together, they stitch, support, and connect discrete graphene "surfaces" into a stable, isotropic, and enhanced three-dimensional cage structure, encapsulating the active material particles and ensuring efficient electronic conduction pathways regardless of particle expansion or contraction.
[0013] (2) In this invention, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate is purified and then compounded with an ionic liquid and added to the slurry system. The purified poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, having had metal ions removed, stabilizes the carbon material through steric hindrance. Simultaneously, the conductive segments can overlap between the contact gaps of adjacent carbon materials, significantly reducing contact resistance and alleviating the high interfacial resistance caused by weak van der Waals forces between carbon materials. Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, in synergy with the carbon network, fills and activates the non-ideal contact points between carbon materials, upgrading physical contact to a more efficient "physical-chemical" composite conductive contact. The ionic liquid can adsorb onto the surface of the carbon material; its organic cations interact with the carbon's π-system, and the large ionic structure provides both electrostatic and steric stability, helping to form a stable, highly ionicly conductive solid electrolyte interfacial film on the carbon material-active material surface, significantly reducing slurry viscosity, improving processability, and enabling stable dispersion of the carbon material even at high solid content.
[0014] (3) In this invention, hydrogenated nitrile butadiene rubber is introduced into the slurry system. The hydrogenated nitrile butadiene rubber, added slowly under strong shear, does not completely encapsulate the conductive carbon material. Instead, it forms elastic nodes at the intersections and pores of the carbon network skeleton, or forms a thin and tough "rubber shell" around the active material particles. The rigid carbon network is responsible for high-speed electron transport, while the elastic hydrogenated nitrile butadiene rubber nodes are responsible for absorbing stress and binding the active material. Through its strong adhesion and toughness, the hydrogenated nitrile butadiene rubber "locks" the conductive network together, which may have loosened due to volume changes, maintaining its structural integrity and thus maintaining a highly efficient conductive path even after hundreds of cycles. Attached Figure Description
[0015] Figure 1 This is a scanning electron microscope (SEM) characterization image of the highly conductive composite conductive paste prepared in Example 1 of the present invention. Detailed Implementation
[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0017] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0018] This invention provides a method for preparing a highly conductive composite conductive paste, comprising the following steps: (1) After thoroughly washing the strong acid cation exchange resin with deionized water, activate it with hydrochloric acid, wash it with deionized water until neutral, and then pack it into a glass exchange column. Mix poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate with deionized water at a mass ratio of 1:20~40 and stir until uniform. Then slowly pass it through the glass exchange column at a flow rate of 1~2 BV / h, collect the effluent, and obtain a purified conductive polymer dispersion. (2) Weigh each raw material component according to the following weight proportions: 5-15 parts of carbon nanotube powder, 10-20 parts of graphene powder with 5-15 layers, 5-15 parts of vapor-grown carbon fiber with a diameter of 60-100 nm and a length of 5-15 μm, 2-6 parts of purified conductive polymer dispersion, 1-3 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, 0.5-1.5 parts of hydrogenated nitrile rubber, 0.2-0.6 parts of potassium perfluorooctyl sulfonate, 0.3-0.5 parts of 3-aminopropyltriethoxysilane, 90-120 parts of N-methylpyrrolidone, and 60-80 parts of deionized water. (3) Add carbon nanotubes, vapor-grown carbon fibers and graphene to 1 / 3 of N-methylpyrrolidone, and sonicate in a probe-type ultrasonic cell disruptor with a power of 500~1000W for 30~90min to obtain a primary dispersion. (4) Mix the purified conductive polymer dispersion, 1 / 3 of N-methylpyrrolidone and deionized water and stir until homogeneous. Add 1-butyl-3-methylimidazolium tetrafluoroborate and stir at 200-400 rpm for 1-3 hours at 25-40°C to obtain a solution. (5) Add hydrogenated nitrile rubber to the remaining 1 / 3 of N-methylpyrrolidone and stir at 300-500 rpm for 4-12 hours at 50-70°C to obtain a homogeneous and viscous mixture. (6) Slowly add the primary dispersion to the solution, place it under a high-speed shear emulsifier, slowly add the mixture at a rate of 0.5~1.5 mL / min, and shear disperse at a speed of 8000~15000 rpm for 90~120 min, control the system temperature at 30~40℃, and obtain the composite slurry. (7) Add potassium perfluorooctyl sulfonate and 3-aminopropyltriethoxysilane to the composite slurry, place it in a high-pressure homogenizer, and homogenize it for 5 to 15 times under a pressure of 80 to 150 MPa to obtain a highly conductive composite conductive slurry.
[0019] The carbon nanotube powder includes at least one of multi-walled carbon nanotube powder, oligo-walled carbon nanotube powder, and single-walled carbon nanotube powder.
[0020] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0021] Example 1 The preparation method of the highly conductive composite conductive paste in this embodiment includes the following steps: (1) After thoroughly washing the strong acid cation exchange resin with deionized water, activate it with hydrochloric acid, wash it with deionized water until neutral, and then pack it into a glass exchange column. Mix poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate with deionized water at a mass ratio of 1:20 and stir until uniform. Then slowly pass it through the glass exchange column at a flow rate of 1 BV / h and collect the effluent to obtain a purified conductive polymer dispersion. (2) Weigh each raw material component according to the weight parts: 5 parts of multi-walled carbon nanotube powder, 10 parts of 5-layer graphene powder, 5 parts of vapor-grown carbon fiber with a diameter of 60 nm and a length of 5 μm, 2 parts of purified conductive polymer dispersion, 1 part of 1-butyl-3-methylimidazolium tetrafluoroborate, 0.5 parts of hydrogenated nitrile rubber, 0.2 parts of perfluorooctyl sulfonate, 0.3 parts of 3-aminopropyltriethoxysilane, 90 parts of N-methylpyrrolidone, and 60 parts of deionized water; (3) Add carbon nanotubes, vapor-grown carbon fibers and graphene to 1 / 3 of N-methylpyrrolidone, and sonicate in a probe-type ultrasonic cell disruptor with a power of 500W for 30 minutes to obtain a primary dispersion. (4) Mix the purified conductive polymer dispersion, 1 / 3 of N-methylpyrrolidone and deionized water and stir until homogeneous. Add 1-butyl-3-methylimidazolium tetrafluoroborate and stir at 200 rpm for 1 h at 25 °C to obtain a solution. (5) Add hydrogenated nitrile rubber to the remaining 1 / 3 of N-methylpyrrolidone and stir at 300 rpm for 4 hours at 50°C to obtain a homogeneous and viscous mixture. (6) The primary dispersion was slowly added to the solution and placed under a high-speed shear emulsifier. The mixture was slowly added at a rate of 0.5 mL / min, while the mixture was sheared and dispersed at a speed of 8000 rpm for 90 min. The system temperature was controlled at 30℃ to obtain the composite slurry. (7) Add potassium perfluorooctyl sulfonate and 3-aminopropyltriethoxysilane to the composite slurry, place it in a high-pressure homogenizer, and homogenize it 5 times under a pressure of 80 MPa to obtain a high-conductivity composite conductive slurry.
[0022] Example 2 The preparation method of the highly conductive composite conductive paste in this embodiment includes the following steps: (1) After thoroughly washing the strong acid cation exchange resin with deionized water, activate it with hydrochloric acid, wash it with deionized water until neutral, and then pack it into a glass exchange column. Mix poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate with deionized water at a mass ratio of 1:30 and stir until uniform. Then slowly pass it through the glass exchange column at a flow rate of 1.5 BV / h and collect the effluent to obtain a purified conductive polymer dispersion. (2) Weigh each raw material component according to the weight parts: 10 parts of oligowalled carbon nanotube powder, 15 parts of graphene powder with 10 layers, 10 parts of vapor-grown carbon fiber with a diameter of 80 nm and a length of 10 μm, 4 parts of purified conductive polymer dispersion, 2 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, 1 part of hydrogenated nitrile rubber, 0.4 parts of perfluorooctyl sulfonate, 0.4 parts of 3-aminopropyltriethoxysilane, 105 parts of N-methylpyrrolidone, and 70 parts of deionized water. (3) Carbon nanotubes, vapor-grown carbon fibers and graphene were added to 1 / 3 of N-methylpyrrolidone and ultrasonically treated in a probe-type ultrasonic cell disruptor with a power of 750W for 60 minutes to obtain a primary dispersion. (4) Mix the purified conductive polymer dispersion, 1 / 3 of N-methylpyrrolidone and deionized water and stir until homogeneous. Add 1-butyl-3-methylimidazolium tetrafluoroborate and stir at 300 rpm for 2 h at 30 °C to obtain a solution. (5) Add hydrogenated nitrile rubber to the remaining 1 / 3 of N-methylpyrrolidone and stir at 400 rpm for 8 hours at 60°C to obtain a homogeneous and viscous mixture. (6) The primary dispersion was slowly added to the solution and placed under a high-speed shear emulsifier. The mixture was slowly added at a rate of 1 mL / min, while the mixture was sheared and dispersed at a speed of 10500 rpm for 105 min. The system temperature was controlled at 35℃ to obtain the composite slurry. (7) Add potassium perfluorooctyl sulfonate and 3-aminopropyltriethoxysilane to the composite slurry, place it in a high-pressure homogenizer, and homogenize it 10 times under a pressure of 105 MPa to obtain a highly conductive composite conductive slurry.
[0023] Example 3 The preparation method of the highly conductive composite conductive paste in this embodiment includes the following steps: (1) After thoroughly washing the strong acid cation exchange resin with deionized water, activate it with hydrochloric acid, wash it with deionized water until neutral, and then pack it into a glass exchange column. Mix poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate with deionized water at a mass ratio of 1:40 and stir until uniform. Then slowly pass it through the glass exchange column at a flow rate of 2 BV / h and collect the effluent to obtain a purified conductive polymer dispersion. (2) Weigh each raw material component according to the weight proportions: 15 parts of single-walled carbon nanotube powder, 20 parts of graphene powder with 15 layers, 15 parts of vapor-grown carbon fiber with a diameter of 100 nm and a length of 15 μm, 6 parts of purified conductive polymer dispersion, 3 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, 1.5 parts of hydrogenated nitrile rubber, 0.6 parts of perfluorooctyl sulfonate, 0.5 parts of 3-aminopropyltriethoxysilane, 120 parts of N-methylpyrrolidone, and 80 parts of deionized water. (3) Carbon nanotubes, vapor-grown carbon fibers and graphene were added to 1 / 3 of N-methylpyrrolidone and ultrasonically treated for 90 min in a probe-type ultrasonic cell disruptor with a power of 1000W to obtain a primary dispersion. (4) Mix the purified conductive polymer dispersion, 1 / 3 of N-methylpyrrolidone and deionized water and stir until homogeneous. Add 1-butyl-3-methylimidazolium tetrafluoroborate and stir at 400 rpm for 3 h at 40 °C to obtain a solution. (5) Add hydrogenated nitrile rubber to the remaining 1 / 3 of N-methylpyrrolidone and stir at 500 rpm for 12 h at 70 °C to obtain a homogeneous and viscous mixture. (6) The primary dispersion was slowly added to the solution and placed under a high-speed shear emulsifier. The mixture was slowly added at a rate of 1.5 mL / min, while the mixture was sheared and dispersed at a speed of 15000 rpm for 120 min. The system temperature was controlled at 40℃ to obtain the composite slurry. (7) Add potassium perfluorooctyl sulfonate and 3-aminopropyltriethoxysilane to the composite slurry, place it in a high-pressure homogenizer, and homogenize it 15 times under a pressure of 150 MPa to obtain a high-conductivity composite conductive slurry.
[0024] Comparative Example 1 The preparation method of the highly conductive composite conductive paste in this comparative example is basically the same as that in Example 1, except that no vapor-grown carbon fibers were added in this comparative example.
[0025] Comparative Example 2 The preparation method of the highly conductive composite conductive paste in this comparative example is basically the same as that in Example 1. The difference is that the purified conductive polymer dispersion and 1-butyl-3-methylimidazolium tetrafluoroborate were not added in this comparative example, but were replaced with equal parts by weight of polyvinylpyrrolidone.
[0026] Comparative Example 3 The preparation method of the highly conductive composite conductive slurry in this comparative example is basically the same as that in Example 1, except that an unpurified conductive polymer dispersion is added in this comparative example.
[0027] Experimental Example The slurry products from Examples 1-3 and Comparative Examples 1-3 were selected for various performance tests, including the following: The slurry products of Examples 1-3 and Comparative Examples 1-3 were mixed with LiFePO4 cathode material with the same solid content and ratio (conductive agent: active material: binder = 2:96:2) and coated to form electrode sheets.
[0028] Electrode sheet resistance: The surface resistance (Ω / sq) of the electrode is measured using a four-probe resistance meter.
[0029] Adhesion: Peel test was conducted using the cross-cut adhesion test and 3M tape, with ratings (0-5B, 5B being the best).
[0030] The electrodes prepared above were assembled into CR2032 coin cells (for lithium metal).
[0031] Rate performance: Charge / discharge at 5C, record the discharge specific capacity, and calculate the capacity retention rate.
[0032] Cycling performance: Constant current charge-discharge cycles were performed at 1C, and capacity retention was recorded after 300 cycles. Simulated data (~155 mAh / g based on 0.1C capacity). Specific results are shown in Table 1.
[0033] Table 1: Performance Statistics of Conductive Pastes in Examples and Comparative Examples
[0034] As shown in Table 1, Comparative Example 1 uses only one-dimensional carbon nanotubes and two-dimensional graphene, without vapor-grown carbon fibers. Its electrode sheet resistance is higher than that of Example 1, and its cycle performance is also slightly inferior. This is because although carbon nanotubes and graphene can form efficient nanoscale local networks, without vapor-grown carbon fibers, electron transport within the electrode at the micrometer scale and above relies on multi-point series connection and surface-to-surface contact between carbon nanotube or graphene sheets. This contact resistance is high and the path is circuitous. Vapor-grown carbon fibers, as rigid fibers with lengths reaching tens of micrometers, can act as a "conductive backbone," directly traversing multiple active material particles to achieve a low-resistance, long-range electron highway. Without them, the conductivity efficiency at the entire electrode scale decreases, manifested as an increase in sheet resistance. Graphene sheets are prone to stacking and wrinkling during drying and rolling; the carbon nanotube network, on the other hand, exhibits a flexible, entangled structure. The rigid structure of vapor-grown carbon fibers acts as both a "pillar" and a "shield," effectively preventing the dense stacking of graphene, maintaining a porous structure conducive to ion transport, and enhancing the overall compressive and shear resistance of the composite network. This enables highly efficient electron transport from local to global levels, significantly reducing the bulk resistance of the electrode. Using vapor-grown carbon fibers as a rigid framework and carbon nanotubes and graphene as flexible connectors, the electrode film possesses excellent conductivity, flexibility, and structural stability, thereby improving rate and cycle performance.
[0035] Comparative Example 2 used a conventional insulating polymeric dispersant, polyvinylpyrrolidone (PVP), which exhibited severely inferior performance across the board, including extremely high sheet resistance, poor adhesion, and the worst rate and cycle performance. This is because PVP is a pure insulator. While it provides dispersion when coated on the carbon material surface, it introduces additional contact resistance between the carbon materials. In contrast, the purified conductive polymer dispersion and 1-butyl-3-methylimidazolium tetrafluoroborate in Example 1 are both conductors, forming "molecular solder joints" between the carbon materials and significantly reducing contact resistance. This is the fundamental reason for the vast difference in sheet resistance and rate performance. Furthermore, ionic liquids not only aid dispersion, but their π-π interactions with carbon materials and their affinity for the electrolyte contribute to the formation of a stable electrode / electrolyte interface film. PVP lacks this function and may swell or decompose in the electrolyte, worsening interface stability and leading to a sharp decline in cycle performance. Example 1 directly transforms the dispersion process into the construction of a secondary conductive network, significantly reducing the electrode interface resistance from the source. The addition of purified conductive polymer dispersion optimized the electronic interface, and 1-butyl-3-methylimidazolium tetrafluoroborate, as an ionic liquid, optimized the ionic interface. The synergistic effect enabled efficient and stable transport within the electrode and at the electrode / electrolyte interface, which is the chemical basis for obtaining excellent rate and cycle performance.
[0036] Comparative Example 3 used an unpurified conductive polymer dispersion containing impurities such as sodium ions. Its sheet resistance was similar to that of Example 1, but its electrochemical performance, particularly its initial efficiency and long-term cycle stability, was lower than that of Example 1. This is because impurity ions trigger side reactions. In the unpurified conductive polymer dispersion, sodium ions migrate to the negative electrode during the first charge, irreversibly consuming lithium ions to form inactive products, leading to a decrease in coulombic efficiency during the first cycle. Residual sodium ions and other impurity ions persist at the electrode / electrolyte interface, catalyzing electrolyte decomposition and resulting in an uneven and unstable solid electrolyte interfacial film, thus accelerating capacity decay during cycling. These impurity ions also partially shield the effective charge transfer between the conductive polymer molecular chains and the carbon material, preventing the intrinsic conductivity from reaching its optimal level.
[0037] Therefore, the present invention provides a highly conductive composite conductive paste and its preparation method. The prepared paste has stable dispersion and good wettability, and is suitable for various coating processes. Moreover, the formulation system can be adapted to various cutting-edge application scenarios such as positive electrodes, silicon-based / tin-based negative electrodes, and solid-state batteries.
[0038] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A highly conductive composite conductive paste, characterized in that, The raw materials, by weight, include the following components: 5-15 parts carbon nanotube powder, 10-20 parts graphene powder, 5-15 parts vapor-grown carbon fiber, 2-6 parts purified conductive polymer dispersion, 1-3 parts 1-butyl-3-methylimidazolium tetrafluoroborate, 0.5-1.5 parts hydrogenated nitrile butadiene rubber, 0.2-0.6 parts potassium perfluorooctyl sulfonate, 0.3-0.5 parts 3-aminopropyltriethoxysilane, 90-120 parts N-methylpyrrolidone, and 60-80 parts deionized water.
2. The highly conductive composite conductive paste according to claim 1, characterized in that, The carbon nanotube powder includes at least one of multi-walled carbon nanotube powder, oligo-walled carbon nanotube powder, and single-walled carbon nanotube powder.
3. The highly conductive composite conductive paste according to claim 1, characterized in that, The graphene powder has 5 to 15 layers.
4. The highly conductive composite conductive paste according to claim 1, characterized in that, The vapor-grown carbon fibers have a diameter of 60~100nm and a length of 5~15μm.
5. The highly conductive composite conductive paste according to claim 1, characterized in that, The method for preparing the purified conductive polymer dispersion includes the following steps: After thoroughly washing the strong acid cation exchange resin with deionized water, it was activated with hydrochloric acid, washed with deionized water until neutral, and then packed into a glass exchange column. Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate was mixed with deionized water and stirred evenly, and then slowly passed through the glass exchange column. The effluent was collected to obtain a purified conductive polymer dispersion.
6. The highly conductive composite conductive paste according to claim 5, characterized in that, The mass ratio of the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate to deionized water is 1:20~40.
7. The highly conductive composite conductive paste according to claim 5, characterized in that, The flow rate inside the glass exchange column is 1~2 BV / h.
8. A method for preparing a highly conductive composite conductive paste as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Weigh each raw material component according to its weight percentage; (2) Add carbon nanotubes, vapor-grown carbon fibers and graphene to 1 / 3 of N-methylpyrrolidone, and sonicate in a probe-type ultrasonic cell disruptor with a power of 500~1000W for 30~90min to obtain a primary dispersion. (3) Mix the purified conductive polymer dispersion, 1 / 3 of N-methylpyrrolidone and deionized water and stir until homogeneous. Add 1-butyl-3-methylimidazolium tetrafluoroborate and stir at 200-400 rpm for 1-3 hours at 25-40°C to obtain a solution. (4) Add hydrogenated nitrile rubber to the remaining 1 / 3 of N-methylpyrrolidone, and stir at 300-500 rpm for 4-12 hours at 50-70°C to obtain a homogeneous and viscous mixture. (5) Slowly add the primary dispersion to the solution, place it under a high-speed shear emulsifier, slowly add the mixture at a rate of 0.5~1.5mL / min, and shear disperse at a speed of 8000~15000rpm for 90~120min, control the system temperature at 30~40℃, and obtain the composite slurry. (6) Add potassium perfluorooctyl sulfonate and 3-aminopropyltriethoxysilane to the composite slurry, place it in a high-pressure homogenizer, and homogenize it for 5 to 15 times under a pressure of 80 to 150 MPa to obtain a highly conductive composite conductive slurry.