A high-conductivity and high-toughness carbon-coated current collector and a preparation method thereof

Abstract

The application discloses a kind of high-conductivity and high-toughness carbon-coated current collector and preparation method thereof, and relates to the technical field of current collector.The present application aims to solve the problem that the carbon-coated current collector is damaged in subsequent processing, such as slitting, rewinding and positive active material coating, due to mechanical stress on the whole current collector, making it difficult to produce battery packs, and causing a conflict between the requirements of low internal resistance and high conductivity for battery performance. Therefore, by providing PANI / P(BA-co-DVB) core-shell composite microspheres that can be used as a toughening agent in the raw material, they can be easily integrated into the existing carbon-coated slurry homogenization process. This material enables the final carbon-coated layer to achieve excellent toughness to resist processing stress while its intrinsic conductivity also improves the overall electrical performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of current collector technology, specifically a carbon-coated current collector with high conductivity and high toughness and its preparation method. Background Technology

[0002] To improve the rate performance of lithium batteries, a conductive carbon layer is often coated on the surface of the current collector. Traditional carbon coatings are mainly composed of brittle carbon materials. In subsequent high-tension manufacturing processes such as high-speed coating, rolling, slitting, and rewinding, microcracks are easily generated due to the mismatch between the modulus and the flexible aluminum foil substrate, leading to plastic deformation or even breakage of the aluminum foil, which seriously affects the production yield and the stability of the battery electrode structure.

[0003] In existing technologies, most solutions for improving the toughness of carbon-coated current collectors and functional current collectors employ physical blending of elastomers or stepwise coating processes, which have several drawbacks and shortcomings: First, carbon-coated current collectors typically use simple addition of nanofiber materials, which reduces the conductivity of the coating layer and affects the final battery's electrical performance; Second, carbon coating through two or more steps is complex, leading to weak interfacial adhesion and easy peeling of the functional layer; Third, conventional toughening solutions fail to achieve intrinsic integration of conductivity and interfacial activity, and cannot simultaneously meet the high requirements of subsequent processing for coating toughness and the high requirements of the battery for low internal resistance.

[0004] In summary, to solve the above problems, it is of great significance to provide a carbon-coated current collector with high conductivity and high toughness and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a high-conductivity and high-toughness carbon-coated current collector and its preparation method, wherein polyaniline / elastomer core-shell composite conductive microspheres are added as a toughening agent in the carbon coating slurry, and the carbon-coated current collector made from this slurry has high toughness and high conductivity to solve the problems mentioned in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a carbon-coated current collector with high conductivity and high toughness includes the following steps: S1: Mix the binder, conductive agent and toughening agent, stir evenly, then add the pH adjuster and wetting agent in sequence, stir until homogeneous, and obtain the coating slurry; S2: Apply the coating slurry to the surface of the current collector substrate and dry it to form a carbon coating layer; thus, a carbon-coated current collector is obtained. The toughening agent is PANI / P(BA-co-DVB) core-shell composite microspheres.

[0007] Among them, the PANI / P(BA-co-DVB) core-shell composite microspheres are composite microspheres with an intrinsically conductive polymer (PANI) as the shell and an elastomer (BA-co-DVB) as the core.

[0008] More preferably, the adhesive is an aqueous solution of polyacrylic acid; the solid content of the aqueous solution of polyacrylic acid is 15~25%, and the viscosity is 800~3000 mPa·s.

[0009] In a more optimized manner, the raw materials of the carbon coating layer, by weight percentage, contain: 37%~40% binder, 57%~60% conductive agent, 0.1%~2% toughening agent, and 1% pH adjuster.

[0010] In a more optimized manner, the conductive agent is composed of conductive agent 1 and conductive agent 2 in a mass ratio of (0.8~1.2):(0.8~1.2); the conductive agent 1 is carbon black and the conductive agent 2 is graphite.

[0011] The wetting agent includes one or more of polyether siloxane, modified polyether siloxane, and alcohol reagents, with isopropanol being preferred as the wetting agent. The main function of the wetting agent is to reduce the surface tension of the slurry and improve the quality of the coating film.

[0012] A more optimized method for preparing the PANI / P(BA-co-DVB) core-shell composite microspheres is as follows: Step 1: Disperse nano-silica and sodium dodecylbenzenesulfonate in water in sequence, add butyl acrylate and divinylbenzene dropwise in sequence under vigorous stirring, emulsify at high speed for 4-6 minutes, place in an ice water bath, then add aniline and stir for 2-3 hours to obtain an emulsion; Step 2: Add ammonium persulfate to the pre-cooled hydrochloric acid solution and stir until homogeneous to obtain the oxidant. Add the oxidant dropwise to the emulsion, set the temperature to 0~5℃, and continue the reaction for 12~24 hours to obtain a dark green product. Step 3: The dark green product was sequentially filtered, washed, dried, and ground to obtain PANI / P(BA-co-DVB) core-shell composite microspheres.

[0013] This preparation method abandons the complex stepwise coating process and adopts a one-step in-situ emulsion polymerization method to directly synthesize PANI / P(BA-co-DVB) core-shell composite microspheres. In the emulsion prepared in step 1, silica particles self-assemble at the oil / water interface to form a strong physical barrier to prevent droplet polymerization. Then, in an ice-water bath at a temperature of 0~5℃, it is conducive to the formation of polyaniline with high conductivity. Subsequently, aniline is added to the emulsion, and aniline will preferentially adsorb and dissolve in sodium dodecylbenzenesulfonate micelles on the surface and interface of the oil phase. The slow dropwise addition of ammonium persulfate solution causes aniline to be oxidized at the oil-water interface, initiating polymerization, and the reaction continues at 0~5℃. As the reaction proceeds, the color of the emulsion gradually changes from milky white to dark green, and finally to dark green, indicating the formation of conductive polyaniline. After the reaction is completed, the microspheres are ground and dried to obtain dark green PANI / P(BA-co-DVB) core-shell composite microspheres.

[0014] More preferably, the raw materials of the emulsion, by weight, are: 0.1-0.3 parts nano-silica, 0.4-0.6 parts sodium dodecylbenzenesulfonate, 8-12 parts butyl acrylate, 0.2-0.4 parts divinylbenzene, and 0.8-1.2 parts aniline; The raw materials for the oxidant, by weight, are: 2-3 parts ammonium persulfate and 15-25 parts hydrochloric acid solution.

[0015] Ideally, the amount of wetting agent added is 8-12% of the total mass of the coating slurry.

[0016] More preferably, the pH adjuster includes sodium hydroxide to adjust the pH to 6-8.

[0017] Ideally, the thickness of the carbon coating layer on one side is 1~3μm, and the coating width is 300~800mm.

[0018] A method for preparing a carbon-coated current collector with high conductivity and high toughness.

[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention aims to address the problem of current collectors being damaged by mechanical stress during subsequent processing, such as slitting, rewinding, and coating with positive electrode active materials. This damage hinders battery pack fabrication and creates a conflict between the battery's requirements for low internal resistance and high conductivity. Therefore, this invention provides a PANI / P (BA-co-DVB) core-shell composite microsphere that can be directly used as a toughening agent in the raw material and can be easily integrated into existing carbon coating slurry homogenization processes. This material enables the final carbon coating layer to achieve excellent toughness to resist processing stress, while its intrinsic conductivity synergistically improves the overall electrical performance of the battery.

[0020] 1. This invention uses PANI / P(BA-co-DVB) core-shell composite microspheres as a toughening agent in the carbon coating layer. On the one hand, the PANI / P(BA-co-DVB) core-shell composite microspheres, through their unique core-shell structure, construct a multi-level mechanical defense system in the carbon coating layer. Their elastic core acts as a highly efficient energy dissipation unit, absorbing stress through the reversible deformation of the molecular chains; while the polyaniline shell forms a flexible nanofiber network, which can uniformly transmit stress, buffer stress concentration at the interface, and "stitch" the two sides of the crack through fiber bridging mechanisms during microcrack propagation, preventing destructive propagation. This synergistic effect transforms the coating from a brittle failure mode to a ductile dissipation mode, enabling the current collector to actively dissipate energy through microscopic deformation during subsequent processing such as cutting, bending, and dynamic tension. This significantly suppresses plastic deformation and fracture risks, improving processing yield and reliability. On the other hand, PANI / P(BA-co-DVB) core-shell composite microspheres synergistically enhance conductivity and electrochemical performance by constructing a multidimensional conductive network. This material, as the intrinsic conductive phase, forms a spatially complementary three-dimensional conductive architecture with the conductive agent particles. Polyaniline fibers provide long-range continuous electronic pathways, and carbon black ensures tight point contact. This dual-network structure significantly reduces bulk resistance and contact resistance, and maintains network integrity under deformation due to fiber bridging. At the electrochemical level, this structure reduces the local current density of the electrode and promotes Li + Uniform deposition enhances the interfacial adhesion between the coating and the foil, suppressing contact failure caused by volume changes during cycling; the pseudocapacitive properties of the polyaniline skeleton contribute additional capacity. Ultimately, this results in low internal resistance, high rate performance, and long cycle life, providing a stable current-collecting foundation for high-energy-density battery systems.

[0021] 2. Traditional solutions often sacrifice conductivity to improve coating toughness, or neglect mechanical reliability in pursuit of high conductivity. This invention achieves a synergistic improvement in two major properties through the intrinsic integrated design of the material: First, the elastic polymer core in the PANI / P (BA-co-DVB) core-shell composite microspheres can efficiently absorb and dissipate energy, while the polyaniline shell can bridge and passivate microcracks. This enables the carbon coating layer to exhibit excellent crack resistance and peel resistance during subsequent high-stress processing such as rewinding and cathode coating, significantly reducing production breakage rate and improving manufacturing yield and efficiency. Second, the highly conductive polyaniline shell on the microsphere surface and traditional conductive agents such as carbon black construct a stable dual-network conductive pathway, which not only ensures excellent initial conductivity of the coating but also maintains the integrity of the conductive network during deformation. This results in lower internal resistance, higher rate performance, and more stable cycle life in the battery.

[0022] 3. The material of this invention has a high degree of functional integration and a synergistic performance enhancement mechanism; a single microsphere simultaneously carries the triple functions of conductivity, toughening and interface strengthening, and the core-shell structure with chemical bonding ensures the synergistic effect of each functional layer, avoiding the interface defects and performance imbalance problems common in physical blending.

[0023] 4. The process of this invention is simple, highly compatible, and easy to promote; the PANI / P(BA-co-DVB) core-shell composite microspheres can be directly used as functional raw materials or additives, and can be dispersed together with conductive carbon materials, binders, etc. in the existing carbon coating slurry homogenization process without modifying existing production lines or introducing complex processes, which greatly reduces the technology introduction threshold and production costs. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the following embodiments, the parts are by weight. It should be noted that there are no special restrictions on the purchasers of any of the raw materials involved in this invention. Exemplary examples include: butyl acrylate (CAS: 141-32-2), 1,4-divinylbenzene (CAS: 105-06-6), aniline (CAS: 65-53-3), ammonium persulfate (CAS: 7727-54-0), hydrochloric acid (CAS: 7647-01-0), sodium dodecylbenzenesulfonate (CAS: 25155-30-0), nano silica (particle size of 500nm), polyacrylic acid (weight average molecular weight of 2000), carbon black (model SHYT-150P, provided by Cabot Chemical Co., Ltd.), graphite (model CP (Shanghai Test), provided by Sinopharm Chemical Reagent Co., Ltd.), isopropanol (CAS: 67-63-0), and sodium hydroxide (CAS: 1310-73-2).

[0026] Pre-preparation: Preparation of PANI / P(BA-co-DVB) core-shell composite microspheres: Step 1: Disperse 0.2 parts of nano silica in 50 parts of water and sonicate at 2500 Hz for 30 minutes. Then add 0.5 parts of sodium dodecylbenzenesulfonate and stir continuously to dissolve. Under vigorous stirring at 1000 rpm, add 10 parts of butyl acrylate and 0.3 parts of divinylbenzene dropwise. Use a homogenizer to emulsify at 15000 rpm for 5 minutes. Then place in an ice-water bath and keep the temperature at 4°C. Then add 1 part of aniline and stir at 200 rpm for 2.5 hours to obtain an emulsion. Step 2: Add 2.4 parts of ammonium persulfate to 20 parts of 1M hydrochloric acid solution pre-cooled to 0℃, stir well to obtain oxidant, add the oxidant dropwise to the emulsion, set the temperature to 4℃, and continue the reaction for 18 hours to obtain dark green product; Step 3: Filter the dark green product and wash it repeatedly with 0.1M hydrochloric acid solution and deionized water until the filtrate is colorless. Dry it at 60℃ for 24 hours and grind it to obtain PANI / P(BA-co-DVB) core-shell composite microspheres.

[0027] Example 1: A method for preparing a carbon-coated current collector with high conductivity and high toughness, comprising the following steps: Step 1: (1) Add 40wt% polyacrylic acid to deionized water, place it in a double-star stirred tank, and stir and disperse at 1100 rpm for 30 minutes to obtain the binder (polyacrylic acid aqueous solution). Then add 28.5wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), stir and disperse at 1650 rpm for 30 minutes, then add the remaining 28.5wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), stir and disperse at 2300 rpm for 30 minutes, and add... Add an appropriate amount of deionized water, continue stirring and dispersing for 30 minutes, then add 2wt% PANI / P(BA-co-DVB) core-shell composite microspheres, stir and disperse at 2300 rpm for 30 minutes to obtain a mixed slurry; (2) add 1wt% pH adjuster (1M sodium hydroxide solution) to adjust the pH to 6.5, add wetting agent (isopropanol), stir and disperse at 12 rpm for 37 minutes; (3) place in a homogenizer and homogenize twice at 600 bar pressure to obtain a coating slurry; Step 2: Apply the coating slurry evenly to the surface of the substrate, with a single-sided coating thickness of 1μm and a coating width of 300mm. Dry the coating to form a carbon coating layer, thus obtaining the carbon-coated current collector.

[0028] The binder (polyacrylic acid aqueous solution) has a solid content of 19% and a viscosity of 1000 mPa·s; the wetting agent is added at 10% of the total mass of the coating slurry.

[0029] Example 2: A method for preparing a carbon-coated current collector with high conductivity and high toughness, comprising the following steps: Step 1: (1) Add 40wt% polyacrylic acid to deionized water, place it in a double-star stirred tank, and stir and disperse at 1100 rpm for 30 minutes to obtain the binder (polyacrylic acid aqueous solution). Then add 29wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), and stir and disperse at 1650 rpm for 30 minutes. Then add the remaining 29wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), and stir and disperse at 2300 rpm for 30 minutes. Add an appropriate amount of deionized water, continue stirring and dispersing for 30 minutes, then add 1wt% PANI / P(BA-co-DVB) core-shell composite microspheres, stir and disperse at 2300 rpm for 30 minutes to obtain a mixed slurry; (2) add 1wt% pH adjuster (1M sodium hydroxide solution) to adjust the pH to 6.5, add wetting agent (isopropanol), stir and disperse at 12 rpm for 37 minutes; (3) place in a homogenizer and homogenize twice at 600 bar pressure to obtain a coating slurry; Step 2: Apply the coating slurry evenly to the surface of the substrate, with a single-sided coating thickness of 1μm and a coating width of 300mm. Dry the coating to form a carbon coating layer, thus obtaining the carbon-coated current collector.

[0030] The binder has a solid content of 19% and a viscosity of 1000 mPa·s; the wetting agent is added at 10% of the total mass of the coating slurry.

[0031] Example 3: A method for preparing a carbon-coated current collector with high conductivity and high toughness, comprising the following steps: Step 1: (1) Add 40wt% polyacrylic acid to deionized water, place it in a double-star stirred tank, and stir and disperse at 1100 rpm for 30 minutes to obtain the binder (polyacrylic acid aqueous solution). Then add 29.2wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), stir and disperse at 1650 rpm for 30 minutes, then add the remaining 29.2wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), stir and disperse at 2300 rpm for 30 minutes, and add... Add an appropriate amount of deionized water, continue stirring and dispersing for 30 minutes, then add 0.6wt% PANI / P(BA-co-DVB) core-shell composite microspheres, stir and disperse at 2300rpm for 30 minutes to obtain a mixed slurry; (2) add 1wt% pH adjuster (1M sodium hydroxide solution) to adjust the pH to 6.5, add wetting agent (isopropanol), stir and disperse at 12rpm for 37 minutes; (3) place in a homogenizer and homogenize twice at 600bar pressure to obtain a coating slurry; Step 2: Apply the coating slurry evenly to the surface of the substrate, with a single-sided coating thickness of 1μm and a coating width of 300mm. Dry the coating to form a carbon coating layer, thus obtaining the carbon-coated current collector.

[0032] The binder has a solid content of 19% and a viscosity of 1000 mPa·s; the wetting agent is added at 10% of the total mass of the coating slurry.

[0033] Example 4: A method for preparing a carbon-coated current collector with high conductivity and high toughness, comprising the following steps: Step 1: (1) Add 40wt% polyacrylic acid to deionized water, place it in a double-star stirred tank, and stir and disperse at 1100 rpm for 30 minutes. Then add 29.4wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), and stir and disperse at 1650 rpm for 30 minutes. Then add the remaining 29.4wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), and stir and disperse at 2300 rpm for 30 minutes. Add an appropriate amount of deionized water. Continue stirring and dispersing for 30 minutes, then add 0.2wt% PANI / P(BA-co-DVB) core-shell composite microspheres, and stir and disperse at 2300 rpm for 30 minutes to obtain a mixed slurry; (2) add 1wt% pH adjuster (1M sodium hydroxide solution) to adjust the pH to 6.5, add wetting agent (isopropanol), and stir and disperse at 12 rpm for 37 minutes; (3) place in a homogenizer and homogenize twice at 600 bar pressure to obtain a coating slurry; Step 2: Apply the coating slurry evenly to the surface of the substrate, with a single-sided coating thickness of 1μm and a coating width of 300mm. Dry the coating to form a carbon coating layer, thus obtaining the carbon-coated current collector.

[0034] The binder has a solid content of 19% and a viscosity of 1000 mPa·s; the wetting agent is added at 10% of the total mass of the coating slurry.

[0035] Example 5: A method for preparing a carbon-coated current collector with high conductivity and high toughness, comprising the following steps: Step 1: (1) Add 40wt% polyacrylic acid to deionized water, place it in a double-star stirred tank, and stir and disperse at 1100 rpm for 30 minutes to obtain the binder (polyacrylic acid aqueous solution). Then add 28.5wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), stir and disperse at 1650 rpm for 30 minutes, then add the remaining 28.5wt% conductive agent (composed of carbon black and graphite in a mass ratio of 1:1), stir and disperse at 2300 rpm for 30 minutes, and add... Add an appropriate amount of deionized water, continue stirring and dispersing for 30 minutes, then add 2wt% PANI / P(BA-co-DVB) core-shell composite microspheres, stir and disperse at 2300 rpm for 30 minutes to obtain a mixed slurry; (2) add 1wt% pH adjuster (1M sodium hydroxide solution) to adjust the pH to 6.5, add wetting agent (isopropanol), stir and disperse at 12 rpm for 37 minutes; (3) place in a homogenizer and homogenize twice at 600 bar pressure to obtain a coating slurry; Step 2: Apply the coating slurry evenly to the surface of the substrate, with a single-sided coating thickness of 1μm and a coating width of 300mm. Dry the coating to form a carbon coating layer, thus obtaining the carbon-coated current collector.

[0036] The binder has a solid content of 19% and a viscosity of 1000 mPa·s; the wetting agent is added at 10% of the total mass of the coating slurry.

[0037] Comparative Example 1: Based on Example 1, without adding polyaniline / elastomer composite conductive microspheres, the amount of binder added is 40%, the amount of conductive agent added is 60%, and the rest is the same as in Example 1.

[0038] Comparative Example 2: Based on Example 1, the composition of the conductive agent was adjusted, wherein the mass ratio of carbon black to graphite was adjusted to 3:1, and the rest remained the same as in Example 1.

[0039] Comparative Example 3: Based on Example 1, the amount of adhesive added was adjusted to 60%, the amount of conductive agent added was 30%, and the amount of PANI / P(BA-co-DVB) core-shell composite microspheres added was 10%, while the rest remained the same as in Example 1.

[0040] Performance testing: The carbon-coated current collectors prepared in the examples and comparative examples were subjected to the following performance tests to characterize their conductivity and toughness.

[0041] (1) Penetration resistance test: The penetration resistance of the carbon coating layer of the carbon current collector is tested using a Four-Point Probe. (2) Elongation test and tensile strength test: The carbon-coated current collector was tested for elongation and tensile strength using a Tesmite universal testing machine.

[0042]

[0043] Conclusion: Example 1 exhibits the best overall performance, likely due to the high conductivity provided by the polyaniline shell, the flexibility imparted by the elastomer core layer, and the complementary conductive pathway formed with the carbon black / graphite (1:1). The 40% polyacrylic acid binder swells sufficiently at pH 6.5, ensuring both adhesion strength to the substrate and preventing excessive encapsulation of conductive particles. Adjusting the pH to 6.5 allows the binder molecular chains to expand, promoting uniform dispersion of the conductive agent. In contrast, Examples 2-4, while showing improved elongation due to decreased microsphere content and increased conductive agent, suffer from decreased conductive network continuity, leading to a significant increase in resistance. Example 5, without pH adjustment, exhibits poor binder dispersion and agglomeration, causing a surge in resistance, demonstrating that pH can improve the overall stability of the slurry system.

[0044] Comparing Example 1 with Comparative Examples 1-3, it can be seen that in Comparative Example 1, after completely removing the PANI / P (BA-co-DVB) core-shell composite microspheres, the system relies on carbon black / graphite to construct a conductive network. However, the contact resistance between rigid conductive particles increases, leading to an increase in resistance. At the same time, the lack of buffering effect of the elastomer core layer results in a high elongation but a decrease in tensile strength to 220 MPa. In Comparative Example 2, the carbon black / graphite ratio was adjusted to 3:1. Excessive carbon black caused severe agglomeration due to its high specific surface area and strong van der Waals forces. Uneven dispersion increased the resistance, and the increased proportion of rigid carbon black led to a decrease in elongation. In Comparative Example 3, excessive binder (60%) formed a thick coating layer, which blocked electron tunneling between conductive particles, resulting in a significant increase in resistance. Meanwhile, reducing the microsphere content to 10% was insufficient to construct an effective toughening network, and the excessive binder reduced the coating cohesion and tensile strength. In summary, when PANI / P(BA-co-DVB) core-shell composite microspheres, conductive agents, and binders are in specific proportions and under optimized pH conditions, the optimal balance between conductivity and mechanical properties is achieved.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a carbon-coated current collector with high conductivity and high toughness, characterized in that: Includes the following steps: S1: Mix the binder, conductive agent, and toughening agent, stir evenly, then add the pH adjuster and wetting agent in sequence, stir until homogeneous, and obtain the coating slurry; S2: Apply the coating slurry to the surface of the current collector substrate and dry it to form a carbon coating layer; thus, a carbon-coated current collector is obtained. The toughening agent is PANI / P(BA-co-DVB) core-shell composite microspheres.

2. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 1, characterized in that: The adhesive is an aqueous solution of polyacrylic acid; the solid content of the aqueous solution of polyacrylic acid is 15-25%, and the viscosity is 800-3000 mPa·s.

3. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 1, characterized in that: The raw materials of the carbon coating layer, by weight percentage, are: 37%~40% binder, 57%~60% conductive agent, 0.1%~2% toughening agent, and 1% pH adjuster.

4. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 1, characterized in that: The conductive agent is composed of conductive agent 1 and conductive agent 2 in a mass ratio of (0.8~1.2):(0.8~1.2); the conductive agent 1 is carbon black and the conductive agent 2 is graphite.

5. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 1, characterized in that: The preparation method of the PANI / P(BA-co-DVB) core-shell composite microspheres is as follows: Step 1: Disperse nano-silica and sodium dodecylbenzenesulfonate in water in sequence, add butyl acrylate and divinylbenzene dropwise in sequence under vigorous stirring, emulsify at high speed for 4-6 minutes, place in an ice water bath, then add aniline and stir for 2-3 hours to obtain an emulsion; Step 2: Add ammonium persulfate to the pre-cooled hydrochloric acid solution and stir until homogeneous to obtain the oxidant. Add the oxidant dropwise to the emulsion, set the temperature to 0~5℃, and continue the reaction for 12~24 hours to obtain a dark green product. Step 3: The dark green product was sequentially filtered, washed, dried and ground to obtain PANI / P(BA-co-DVB) core-shell composite microspheres.

6. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 5, characterized in that: The raw materials of the emulsion, by weight, are: 0.1-0.3 parts nano silica, 0.4-0.6 parts sodium dodecylbenzenesulfonate, 8-12 parts butyl acrylate, 0.2-0.4 parts divinylbenzene, and 0.8-1.2 parts aniline; The raw materials for the oxidant, by weight, are: 2-3 parts ammonium persulfate and 15-25 parts hydrochloric acid solution.

7. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 1, characterized in that: The amount of wetting agent added is 8-12% of the total mass of the coating slurry.

8. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 1, characterized in that: The pH adjuster includes sodium hydroxide, which adjusts the pH to 6-8.

9. The method for preparing a highly conductive and highly tough carbon-coated current collector according to claim 1, characterized in that: The thickness of the carbon coating layer on one side is 1~3μm, and the coating width is 300~800mm.

10. The carbon-coated current collector prepared by the method for preparing a high-conductivity and high-toughness carbon-coated current collector according to any one of claims 1 to 9.

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