Water-based composite conductive paste for silicon-based negative electrode of lithium battery and preparation method thereof

Abstract

The present application relates to the technical field of conductive agent, and specifically discloses a water-based composite conductive slurry for silicon-based negative electrode of lithium battery and a preparation method thereof.The water-based composite conductive slurry for silicon-based negative electrode of lithium battery comprises pre-lithiation mesoporous silicon-carbon composite material, single-walled carbon nanotube powder, graphene powder, conductive carbon black, polyacrylic acid, sodium alginate, water-based polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, sodium carboxymethyl cellulose, non-ionic surfactant, lithiated humic acid, pre-emulsified fluoroethylene carbonate, lithium ion conductor nanowire and deionized water.The conductive slurry provides efficient and redundant electron transmission paths, has excellent resistance to volume change of silicon, realizes molecular-level fusion of conductive and adhesive functions, and thus promotes formation of SEI film with high ionic conductance and high mechanical stability.

Description

Technical Field

[0001] This invention relates to the field of conductive agent technology, and more specifically, to a water-based composite conductive slurry for lithium battery silicon-based negative electrodes 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 water-based composite conductive slurry for lithium battery silicon-based anodes and its preparation method.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A water-based composite conductive slurry for lithium-ion battery silicon-based anodes, comprising the following components by weight: The composition includes 20-30 parts of pre-lithiated mesoporous silicon-carbon composite material, 2-4 parts of single-walled carbon nanotube powder, 1-3 parts of graphene powder, 0.5-1.5 parts of conductive carbon black, 1-3 parts of polyacrylic acid, 0.5-1.5 parts of sodium alginate, 0.5-1.5 parts of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.3-0.9 parts of sodium carboxymethyl cellulose, 0.1-0.3 parts of nonionic surfactant, 0.1-0.3 parts of lithiumized humic acid, 1-3 parts of fluoroethylene carbonate preemulsion, 1-2 parts of lithium-ion conductor nanowires, and 80-100 parts of deionized water.

[0005] Furthermore, the preparation method of the pre-lithiated mesoporous silicon-carbon composite material includes the following steps: In an argon-filled glove box, mesoporous silicon-carbon composite material with a pore size of 5-20 nm is mixed with stabilized lithium metal powder at a mass ratio of 4-5:1 for 60-120 min. The mixture is then placed in an atmosphere furnace and heat-treated at 100-200℃ for 4-12 h in an argon atmosphere. The temperature is then raised to 300-500℃ for 1-2 h, followed by annealing and sieving to obtain a pre-lithiated mesoporous silicon-carbon composite anode material.

[0006] Furthermore, the diameter of the single-walled carbon nanotube powder is 1~3nm and the length is 8~12μm.

[0007] Furthermore, the graphene powder has 3 to 8 layers.

[0008] Furthermore, the conductive carbon black has a particle size of 30~50nm.

[0009] Furthermore, the preparation method of the aqueous polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite includes the following steps: S1. Weigh the following raw materials by weight: 60-80 parts of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, 0.5-2.5 parts of aniline, 0.04-0.06 parts of ammonium persulfate, 0.01-0.03 parts of sodium dodecylbenzenesulfonate, 0.05-0.07 parts of polyvinylpyrrolidone, 0.02-0.04 parts of glutaraldehyde, and 20-30 parts of deionized water; S2. Add sodium dodecylbenzenesulfonate and polyvinylpyrrolidone to poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, stir at 500-1000 rpm for 30-60 min in a cold water bath at 0-5℃, and add hydrochloric acid dropwise to adjust the pH value to 1.5-2.5 to obtain an acidic dispersion. S3. Add aniline slowly to the acidic dispersion at a dropping rate of 1~2 mL / min, and continue stirring in a cold water bath at 0~5℃ for 2~4 h to obtain an acidic mixture. S4. Add ammonium persulfate to deionized water, stir to dissolve, and pre-cool to 0~5℃. Add the acidic mixture dropwise over 10~30 min at a speed of 800~1200 rpm. After the addition is complete, keep the temperature at 0~5℃ and continue the reaction for 12~24 h. Let it mature at room temperature for 2~6 h. Add glutaraldehyde and stir the reaction at room temperature for 4~8 h to obtain the reaction solution. S5. Transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 8000~14000 Da, dialyze with deionized water for 48~72 hours, changing the water every 6~8 hours. After dialysis, centrifuge the liquid in the dialysis bag at a speed of 8000~12000 rpm for 20~40 minutes and collect the supernatant. S6. Add deionized water to the supernatant to adjust the solid content to 1.5~3.5wt%, then add ammonia water to adjust the pH to 3.5~5.0, mix well, and you will get an aqueous polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite.

[0010] Furthermore, the nonionic surfactant includes at least one of octylphenol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and oleyl alcohol polyoxyethylene ether.

[0011] Furthermore, the lithium-ion conductor nanowire has a diameter of 20-50 nm and a length of 0.5-1.5 μm.

[0012] Furthermore, the preparation method of the aqueous composite conductive slurry for the silicon-based negative electrode of the lithium battery includes the following steps: (1) Weigh each raw material component according to its weight percentage; The composition includes: 20-30 parts of pre-lithiated mesoporous silicon-carbon composite material, 2-4 parts of single-walled carbon nanotube powder, 1-3 parts of graphene powder, 0.5-1.5 parts of conductive carbon black, 1-3 parts of polyacrylic acid, 0.5-1.5 parts of sodium alginate, 0.5-1.5 parts of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.3-0.9 parts of sodium carboxymethyl cellulose, 0.1-0.3 parts of nonionic surfactant, 0.1-0.3 parts of lithium-based humic acid, 1-3 parts of fluoroethylene carbonate pre-emulsion, 1-2 parts of lithium-ion conductor nanowires, and 80-100 parts of deionized water. (2) Add single-walled carbon nanotube powder, graphene powder, and conductive carbon black to 1 / 2 of deionized water, and add sodium carboxymethyl cellulose, nonionic surfactant and lithium humic acid in sequence. Shear and disperse at a speed of 2000~5000 rpm for 15~45 min, and then continue to homogenize at a pressure of 800~1600 bar. Repeat the cycle 3~8 times to obtain a conductive agent dispersion. (3) Add polyacrylic acid, sodium alginate, and waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid complex to the remaining 1 / 2 of deionized water and stir at 400~800 rpm for 2~6 hours to dissolve and obtain adhesive solution. (4) Slowly add the binder solution to the conductive agent dispersion, stir and mix at a speed of 800~1500 rpm for 30~90 min, add ammonia water dropwise to adjust the pH value to 9~10, and obtain the mixture; (5) The pre-lithiated mesoporous silicon-carbon composite material, fluoroethylene carbonate pre-emulsion, and lithium-ion conductor nanowires are gradually added to the mixture in 3 to 5 batches. After each batch is added, the mixture is first stirred at 500 to 1000 rpm for 10 to 30 minutes for initial wetting, and then sheared and dispersed at 1500 to 2500 rpm for 15 to 30 minutes. After mixing evenly, the material is placed in a sand mill, and zirconium oxide balls are added at a ball-to-material ratio of 3 to 8:1. The mixture is then ground at 200 to 400 rpm for 2 to 6 hours to obtain a grinding slurry. (6) Place the grinding slurry in an ultrasonic reactor and ultrasonically treat it for 15 to 45 minutes at a power of 500 to 1500W and a frequency of 20 to 40kHz. Stir and degas at a speed of 50 to 150 rpm for 1 to 3 hours under a pressure of -0.1 to -0.08MPa to obtain a water-based composite conductive slurry for lithium battery silicon-based negative electrode.

[0013] In summary, this application includes at least the following beneficial effects: (1) This invention possesses a complete synergistic dispersion and stabilization system. Lithium-modified humic acid is adsorbed onto the surface of carbon nanotubes / graphene through π-π interactions, providing electrostatic repulsion; the long-chain hydrophilic blocks of nonionic surfactant PEO form a thick hydration layer and steric hindrance; the in-situ polymerized aqueous polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite has a hydrophilic shell and is itself an excellent aqueous dispersion. The synergistic effect of these three components effectively "encapsulates" and "isolates" the hydrophobic nano-conductive agent, achieving long-term kinetic stability.

[0014] (2) This invention constructs a highly efficient hybrid conductive network of "three-dimensional continuity + molecular-level bridging". Carbon nanotubes and graphene form a long-range framework that runs through the electrode. Conductive carbon black fills its large pores. Most importantly, the in-situ polymerized aqueous polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite acts as a conductive binder, forming a strong molecular-level conductive "bridge" and "coating" between the active particles and the carbon materials, as well as between the carbon materials themselves. The composite achieves efficient charge transport through π-π stacking, significantly reducing contact resistance.

[0015] (3) The conductive paste of the present invention exhibits excellent high-rate performance due to its "dual high-conductivity" network. The high-speed electron transport is achieved through an ultra-low sheet resistance three-dimensional electron network. High-speed ion transport is achieved through lithium-ion conductor nanowires acting as built-in fast-conducting channels embedded within the electrode, significantly enhancing the bulk diffusion rate of lithium ions in the electrode thick film. The synergy of these two features ensures that electrons and ions can reach the reaction interface synchronously and rapidly during high-rate (high-current) charging and discharging, avoiding polarization.

[0016] (4) This invention achieves a perfect synergy between structural stability and interface stability. The strong and elastic bonding network composed of polyacrylic acid-sodium alginate-composite conductive polymer intertwines with the flexible conductive network composed of carbon nanotubes-graphene, forming an integrated framework similar to "reinforced concrete," which can effectively bind silicon particles, adapt to their volume changes, and prevent electrode pulverization. Pre-lithiation compensates for the initial lithium consumption; fluoroethylene carbonate induces the formation of a dense and flexible SEI rich in LiF; lithium-ion conductors participate in the construction of a stable interface layer with high ionic conductivity. Together, these factors ensure the mechanical integrity and high ionic conductivity of the SEI during long-term cycling, greatly reducing the continuous consumption of active lithium and electrolyte. Detailed Implementation

[0017] It should be noted that, where there is no conflict, 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 embodiments.

[0018] 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.

[0019] This invention provides a method for preparing an aqueous composite conductive slurry for a silicon-based negative electrode in lithium-ion batteries, comprising the following steps: (1) In a glove box filled with argon, the mesoporous silicon-carbon composite material with a pore size of 5~20nm is mixed with stabilized lithium metal powder at a mass ratio of 4~5:1 for 60~120min. The mixture is placed in an atmosphere furnace and heat-treated at a temperature of 100~200℃ for 4~12h under an argon atmosphere. Then the temperature is raised to 300~500℃ for 1~2h, annealed, and sieved to obtain the pre-lithiated mesoporous silicon-carbon composite anode material. (2) Weigh the following raw materials by weight: 60-80 parts of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, 0.5-2.5 parts of aniline, 0.04-0.06 parts of ammonium persulfate, 0.01-0.03 parts of sodium dodecylbenzenesulfonate, 0.05-0.07 parts of polyvinylpyrrolidone, 0.02-0.04 parts of glutaraldehyde, and 20-30 parts of deionized water; (3) Add sodium dodecylbenzenesulfonate and polyvinylpyrrolidone to poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, stir at 500-1000 rpm for 30-60 min in a cold water bath at 0-5℃, and add hydrochloric acid dropwise to adjust the pH value to 1.5-2.5 to obtain an acidic dispersion. (4) Add aniline slowly to the acidic dispersion at a dropping rate of 1~2 mL / min, and continue stirring in a cold water bath at 0~5℃ for 2~4 h to obtain an acidic mixture; (5) Add ammonium persulfate to deionized water, stir to dissolve, and pre-cool to 0~5℃. Add acidic mixture dropwise over 10~30 min at a speed of 800~1200 rpm. After the addition is complete, keep the temperature at 0~5℃ and continue the reaction for 12~24 h. Let it mature at room temperature for 2~6 h. Add glutaraldehyde and stir the reaction at room temperature for 4~8 h to obtain the reaction solution. (6) Transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 8000~14000 Da, dialyze with deionized water for 48~72h, change the water every 6~8h, after dialysis, centrifuge the liquid in the dialysis bag at a speed of 8000~12000rpm for 20~40min, and collect the supernatant. (7) Add deionized water to the supernatant to adjust the solid content to 1.5~3.5wt%, then add ammonia water to adjust the pH value to 3.5~5.0, mix well, and obtain water-based polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite. (8) Weigh the following raw material components by weight: 20-30 parts of pre-lithiated mesoporous silicon-carbon composite material, 2-4 parts of single-walled carbon nanotube powder with a diameter of 1-3 nm and a length of 8-12 μm, 1-3 parts of graphene powder with 3-8 layers, 0.5-1.5 parts of conductive carbon black with a particle size of 30-50 nm, 1-3 parts of polyacrylic acid, 0.5-1.5 parts of sodium alginate, 0.5-1.5 parts of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.3-0.9 parts of sodium carboxymethyl cellulose, 0.1-0.3 parts of nonionic surfactant, 0.1-0.3 parts of lithiumized humic acid, 1-3 parts of fluoroethylene carbonate pre-emulsion, 1-2 parts of lithium-ion conductor nanowires with a diameter of 20-50 nm and a length of 0.5-1.5 μm, and 80-100 parts of deionized water; (9) Add single-walled carbon nanotube powder, graphene powder, and conductive carbon black to 1 / 2 of deionized water, and add sodium carboxymethyl cellulose, nonionic surfactant and lithium humic acid in sequence. Shear and disperse at a speed of 2000~5000 rpm for 15~45 min, and then continue to homogenize at a pressure of 800~1600 bar. Repeat the cycle 3~8 times to obtain a conductive agent dispersion. (10) Add polyacrylic acid, sodium alginate, and waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid complex to the remaining 1 / 2 of deionized water and stir at 400~800 rpm for 2~6 hours to dissolve and obtain adhesive solution. (11) Slowly add the binder solution to the conductive agent dispersion, stir and mix at a speed of 800~1500 rpm for 30~90 min, add ammonia water dropwise to adjust the pH value to 9~10, and obtain the mixture; (12) The pre-lithiated mesoporous silicon-carbon composite material, fluoroethylene carbonate pre-emulsion, and lithium-ion conductor nanowires are gradually added to the mixture in 3 to 5 batches. After each batch is added, the mixture is first stirred at 500 to 1000 rpm for 10 to 30 minutes for initial wetting, and then sheared and dispersed at 1500 to 2500 rpm for 15 to 30 minutes. After mixing evenly, the material is placed in a sand mill, and zirconium oxide balls are added at a ball-to-material ratio of 3 to 8:1. The mixture is then ground at 200 to 400 rpm for 2 to 6 hours to obtain a grinding slurry. (13) Place the grinding slurry in an ultrasonic reactor and ultrasonically treat it for 15 to 45 minutes under the conditions of power 500~1500W and frequency 20~40kHz. Stir and degas at a speed of 50~150rpm for 1~3 hours under a pressure of -0.1~-0.08MPa to obtain a water-based composite conductive slurry for lithium battery silicon-based negative electrode.

[0020] The nonionic surfactant includes at least one of octylphenol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and oleyl alcohol polyoxyethylene ether.

[0021] 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.

[0022] Example 1 The method for preparing the aqueous composite conductive paste for the silicon-based negative electrode of the lithium battery in this embodiment includes the following steps: (1) In a glove box filled with argon, the mesoporous silicon-carbon composite material with a pore size of 5 nm was mixed with stabilized lithium metal powder at a mass ratio of 4:1 for 60 min. The mixture was placed in an atmosphere furnace and heat-treated at 100 °C for 4 h in an argon atmosphere. Then the temperature was raised to 300 °C for 1 h, annealed, and sieved to obtain the pre-lithiated mesoporous silicon-carbon composite anode material. (2) Weigh the following raw materials by weight: 60 parts of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, 0.5 parts of aniline, 0.04 parts of ammonium persulfate, 0.01 parts of sodium dodecylbenzenesulfonate, 0.05 parts of polyvinylpyrrolidone, 0.02 parts of glutaraldehyde, and 20 parts of deionized water; (3) Sodium dodecylbenzenesulfonate and polyvinylpyrrolidone were added to poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, stirred at 500 rpm for 30 min in a 0℃ cold water bath, and hydrochloric acid was added dropwise to adjust the pH value to 1.5 to obtain an acidic dispersion. (4) Add aniline slowly to the acidic dispersion at a dropping rate of 1 mL / min, and continue stirring for 2 h in a cold water bath at 0 °C to obtain an acidic mixture; (5) Add ammonium persulfate to deionized water, stir to dissolve, pre-cool to 0°C, add acidic mixture dropwise over 10 minutes at 800 rpm, and continue to react at 0°C for 12 hours. Let it mature at room temperature for 2 hours, add glutaraldehyde, and stir to react for 4 hours at room temperature to obtain the reaction solution. (6) Transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 8000 Da, dialyze with deionized water for 48 hours, change the water every 6 hours, and after dialysis, centrifuge the liquid in the dialysis bag at 8000 rpm for 20 minutes and collect the supernatant. (7) Add deionized water to the supernatant to adjust the solid content to 1.5 wt%, then add ammonia water to adjust the pH value to 3.5, mix well, and obtain water-based polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite. (8) Weigh the following raw material components by weight: 20 parts of pre-lithiated mesoporous silicon-carbon composite material, 2 parts of single-walled carbon nanotube powder with a diameter of 1 nm and a length of 8 μm, 1 part of graphene powder with 3 layers, 0.5 parts of conductive carbon black with a particle size of 30 nm, 1 part of polyacrylic acid, 0.5 parts of sodium alginate, 0.5 parts of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.3 parts of sodium carboxymethyl cellulose, 0.1 parts of octylphenol polyoxyethylene ether, 0.1 parts of lithiumized humic acid, 1 part of fluoroethylene carbonate pre-emulsion, 1 part of lithium-ion conductor nanowire with a diameter of 20 nm and a length of 0.5 μm, and 80 parts of deionized water; (9) Add single-walled carbon nanotube powder, graphene powder, and conductive carbon black to 1 / 2 of deionized water, and add sodium carboxymethyl cellulose, nonionic surfactant and lithium humic acid in sequence. Shear and disperse at 2000 rpm for 15 min, and then continue homogenization treatment at 800 bar. Repeat the cycle 3 times to obtain conductive agent dispersion. (10) Add polyacrylic acid, sodium alginate, and waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid complex to the remaining 1 / 2 of deionized water and stir at 400 rpm for 2 hours to dissolve and obtain adhesive solution. (11) Slowly add the binder solution to the conductive agent dispersion, stir and mix at 800 rpm for 30 min, add ammonia water dropwise to adjust the pH value to 9, and obtain the mixture; (12) The pre-lithiated mesoporous silicon-carbon composite material, fluoroethylene carbonate pre-emulsion, and lithium-ion conductor nanowires were gradually added to the mixture in three batches. After each batch was added, the mixture was first stirred at 500 rpm for 10 min for initial wetting, and then sheared and dispersed at 1500 rpm for 15 min. After mixing evenly, the material was placed in a sand mill, and zirconia balls were added at a ball-to-material ratio of 3:1. The mixture was then ground at 200 rpm for 2 h to obtain a grinding slurry. (13) The grinding slurry was placed in an ultrasonic reactor and ultrasonically treated for 15 minutes at a power of 500W and a frequency of 20kHz. It was then stirred and vacuum degassed for 1 hour at a speed of 50rpm under a pressure of -0.1MPa to obtain a water-based composite conductive slurry for lithium battery silicon-based negative electrode.

[0023] Example 2 The method for preparing the aqueous composite conductive paste for the silicon-based negative electrode of the lithium battery in this embodiment includes the following steps: (1) In a glove box filled with argon, the mesoporous silicon-carbon composite material with a pore size of 10 nm was mixed with stabilized lithium metal powder at a mass ratio of 4.5:1 for 90 min. The mixture was placed in an atmosphere furnace and heat-treated at 150 °C for 8 h in an argon atmosphere. Then the temperature was raised to 400 °C for 1.5 h, annealed, and sieved to obtain the pre-lithiated mesoporous silicon-carbon composite anode material. (2) Weigh the following raw materials by weight: 70 parts of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, 1.5 parts of aniline, 0.05 parts of ammonium persulfate, 0.02 parts of sodium dodecylbenzenesulfonate, 0.06 parts of polyvinylpyrrolidone, 0.03 parts of glutaraldehyde, and 25 parts of deionized water; (3) Sodium dodecylbenzenesulfonate and polyvinylpyrrolidone were added to poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, stirred at 750 rpm for 45 min in a 3℃ cold water bath, and hydrochloric acid was added dropwise to adjust the pH value to 2 to obtain an acidic dispersion. (4) Add aniline slowly to the acidic dispersion at a dropping rate of 1.5 mL / min, and continue stirring for 3 h in a cold water bath at 3 °C to obtain an acidic mixture; (5) Add ammonium persulfate to deionized water, stir to dissolve, pre-cool to 3°C, add acidic mixture dropwise over 20 minutes at 1000 rpm, and continue to react at 3°C ​​for 18 hours after the addition is complete. Let it mature at room temperature for 4 hours, add glutaraldehyde, and stir to react at room temperature for 6 hours to obtain the reaction solution. (6) Transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 11000 Da, dialyze with deionized water for 60 h, change the water every 7 h, and after dialysis, centrifuge the liquid in the dialysis bag at 10000 rpm for 30 min and collect the supernatant. (7) Add deionized water to the supernatant to adjust the solid content to 2.5 wt%, then add ammonia to adjust the pH to 4, mix well, and obtain water-based polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite. (8) Weigh the following raw material components by weight: 25 parts of pre-lithiated mesoporous silicon carbon composite material, 3 parts of single-walled carbon nanotube powder with a diameter of 2 nm and a length of 10 μm, 2 parts of graphene powder with 5 layers, 1 part of conductive carbon black with a particle size of 40 nm, 2 parts of polyacrylic acid, 1 part of sodium alginate, 1 part of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.6 parts of sodium carboxymethyl cellulose, 0.2 parts of lauryl alcohol polyoxyethylene ether, 0.2 parts of lithiumized humic acid, 2 parts of fluoroethylene carbonate pre-emulsion, 1.5 parts of lithium-ion conductor nanowire with a diameter of 35 nm and a length of 1 μm, and 90 parts of deionized water; (9) Add single-walled carbon nanotube powder, graphene powder, and conductive carbon black to 1 / 2 of deionized water, and add sodium carboxymethyl cellulose, nonionic surfactant and lithium humic acid in sequence. Shear and disperse at 3500 rpm for 30 min, and then continue homogenization treatment at 1200 bar. Repeat 5 times to obtain conductive agent dispersion. (10) Add polyacrylic acid, sodium alginate, and waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid complex to the remaining 1 / 2 of deionized water and stir at 600 rpm for 4 hours to dissolve and obtain adhesive solution. (11) Slowly add the binder solution to the conductive agent dispersion, stir and mix at 1200 rpm for 60 min, and add ammonia water dropwise to adjust the pH value to 9.5 to obtain the mixture; (12) The pre-lithiated mesoporous silicon-carbon composite material, fluoroethylene carbonate pre-emulsion, and lithium-ion conductor nanowires were gradually added to the mixture in 4 batches. After each batch was added, the mixture was first stirred at 750 rpm for 20 min for initial wetting, and then sheared and dispersed at 2000 rpm for 20 min. After mixing evenly, the material was placed in a sand mill, and zirconia balls were added at a ball-to-material ratio of 5:1. The mixture was ground at 300 rpm for 4 h to obtain the grinding slurry. (13) The grinding slurry was placed in an ultrasonic reactor and ultrasonically treated for 30 min at a power of 1000 W and a frequency of 30 kHz. It was then stirred and vacuum degassed for 2 h at a speed of 100 rpm under a pressure of -0.09 MPa to obtain a water-based composite conductive slurry for lithium battery silicon-based negative electrode.

[0024] Example 3 The method for preparing the aqueous composite conductive paste for the silicon-based negative electrode of the lithium battery in this embodiment includes the following steps: (1) In a glove box filled with argon, the mesoporous silicon-carbon composite material with a pore size of 20 nm was mixed with stabilized lithium metal powder at a mass ratio of 5:1 for 120 min. The mixture was placed in an atmosphere furnace and heat-treated at 200 °C for 12 h in an argon atmosphere. Then the temperature was raised to 500 °C for 2 h, annealed, and sieved to obtain the pre-lithiated mesoporous silicon-carbon composite anode material. (2) Weigh the following raw materials by weight: 80 parts of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, 2.5 parts of aniline, 0.06 parts of ammonium persulfate, 0.03 parts of sodium dodecylbenzenesulfonate, 0.07 parts of polyvinylpyrrolidone, 0.04 parts of glutaraldehyde, and 30 parts of deionized water; (3) Sodium dodecylbenzenesulfonate and polyvinylpyrrolidone were added to poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, stirred at 1000 rpm for 60 min in a 5℃ cold water bath, and hydrochloric acid was added dropwise to adjust the pH value to 2.5 to obtain an acidic dispersion. (4) Add aniline slowly to the acidic dispersion at a dropping rate of 2 mL / min, and continue stirring in a 5°C cold water bath for 4 h to obtain an acidic mixture; (5) Add ammonium persulfate to deionized water, stir to dissolve, pre-cool to 5°C, add acidic mixture dropwise over 30 minutes at 1200 rpm, and continue to react at 5°C for 24 hours after the addition is complete. Let it mature at room temperature for 6 hours, add glutaraldehyde, and stir to react at room temperature for 8 hours to obtain the reaction solution. (6) Transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 14000 Da, dialyze with deionized water for 72 h, change the water every 8 h, and after dialysis, centrifuge the liquid in the dialysis bag at 12000 rpm for 40 min and collect the supernatant. (7) Add deionized water to the supernatant to adjust the solid content to 3.5 wt%, then add ammonia water to adjust the pH value to 5, mix well, and obtain water-based polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite. (8) Weigh the following raw material components by weight: 30 parts of pre-lithiated mesoporous silicon-carbon composite material, 4 parts of single-walled carbon nanotube powder with a diameter of 3 nm and a length of 12 μm, 3 parts of graphene powder with 8 layers, 1.5 parts of conductive carbon black with a particle size of 50 nm, 3 parts of polyacrylic acid, 1.5 parts of sodium alginate, 1.5 parts of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.9 parts of sodium carboxymethyl cellulose, 0.3 parts of oleyl alcohol polyoxyethylene ether, 0.3 parts of lithiumized humic acid, 3 parts of fluoroethylene carbonate pre-emulsion, 2 parts of lithium-ion conductor nanowires with a diameter of 50 nm and a length of 1.5 μm, and 100 parts of deionized water; (9) Add single-walled carbon nanotube powder, graphene powder, and conductive carbon black to 1 / 2 of deionized water, and add sodium carboxymethyl cellulose, nonionic surfactant and lithium humic acid in sequence. Shear and disperse at 5000 rpm for 45 min, and then continue homogenization treatment at 1600 bar. Repeat the cycle 8 times to obtain conductive agent dispersion. (10) Add polyacrylic acid, sodium alginate, and waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid complex to the remaining 1 / 2 of deionized water and stir at 800 rpm for 6 hours to dissolve and obtain adhesive solution. (11) Slowly add the binder solution to the conductive agent dispersion, stir and mix at 1500 rpm for 90 min, add ammonia water dropwise to adjust the pH value to 10, and obtain the mixture; (12) The pre-lithiated mesoporous silicon-carbon composite material, fluoroethylene carbonate pre-emulsion, and lithium-ion conductor nanowires were gradually added to the mixture in 5 batches. After each batch was added, the mixture was first stirred at 1000 rpm for 30 min for initial wetting, and then sheared and dispersed at 2500 rpm for 30 min. After mixing evenly, the material was placed in a sand mill, and zirconia balls were added at a ball-to-material ratio of 8:1. The mixture was ground at 400 rpm for 6 h to obtain the grinding slurry. (13) The grinding slurry was placed in an ultrasonic reactor and ultrasonically treated for 45 minutes at a power of 1500W and a frequency of 40kHz. It was then stirred and vacuum degassed at a speed of 150rpm under a pressure of -0.08MPa for 3 hours to obtain a water-based composite conductive slurry for lithium battery silicon-based negative electrode.

[0025] Comparative Example 1 The preparation method of the aqueous composite conductive slurry for the silicon-based negative electrode of the lithium battery in this comparative example is basically the same as that in Example 1. The difference is that the silicon-based active material added in this comparative example is a mesoporous silicon-carbon composite material with the same structure as in Example 1 but without pre-lithiation.

[0026] Comparative Example 2 The preparation method of the aqueous composite conductive slurry for the silicon-based negative electrode of the lithium battery in this comparative example is basically the same as that in Example 1. The difference is that the fluoroethylene carbonate pre-emulsion and lithium-ion conductor nanowires were not added in this comparative example.

[0027] Comparative Example 3 The preparation method of the aqueous composite conductive slurry for the silicon-based negative electrode of lithium battery in this comparative example is basically the same as that in Example 1. The difference is that in this comparative example, physically mixed polyaniline powder and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion are used instead of the in-situ polymerized aqueous polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite. The mixing ratio is the same as the feeding ratio in the in-situ polymerization.

[0028] Experimental Example The slurry products from Examples 1-3 and Comparative Examples 1-3 were selected for various performance tests, including the following: Slurry properties: The slurry was left to stand for 7 days, the settling volume ratio was tested, and the 7-day settling rate was calculated.

[0029] Electrode performance: Electrode electronic surface resistance (Ω / sq) was measured using a four-probe ohmmeter.

[0030] Electrochemical performance (CR2032 coin cell, counter electrode is lithium metal): Cycling performance: First, activate at 0.1C for 2 cycles, then cycle at 1C for 500 cycles, and record the capacity retention rate.

[0031] Rate performance: The discharge capacity was calculated by cycling 5 times each at 0.2C, 0.5C, 1C, 2C, and 5C. The specific results are shown in Table 1.

[0032] Table 1: Performance Statistics of Conductive Pastes in Examples and Comparative Examples

[0033] As shown in Table 1, Example 1 benefits from a complete synergistic dispersion stabilization system. Lithium-modified humic acid (Li-HA) adsorbs onto the surface of carbon nanotubes (CNTs) / graphene through π-π interactions, providing electrostatic repulsion; the long-chain hydrophilic blocks of nonionic surfactant PEO form a thick hydration layer and steric hindrance; and the in-situ polymerized PANI-PEDOT:PSS has a hydrophilic PSS shell and is itself an excellent aqueous dispersion. The synergistic effect of these three components effectively "encapsulates" and "isolates" the hydrophobic conductive nanoparticles, achieving long-term kinetic stability. Comparative Example 1 is similar to Example 1 because pre-lithiation mainly alters the bulk phase and surface chemistry of the material (introducing lithium species), having minimal impact on its surface wettability in water and its interaction with the dispersant. Therefore, the physical dispersion stability of the slurry mainly depends on the same dispersant system, resulting in comparable sedimentation rates. Comparative Example 2 is similar to Example 1. The main functions of the FEC preemulsion and LATP nanowires are electrochemical interface modification rather than physical dispersion. The LATP nanowires have a charged surface, which has a slight impact on stability. The sharp increase in sedimentation rate in Comparative Example 3 indicates that physical mixing disrupted the colloidal stability of the system. Commercial PANI powder is highly hydrophobic and prone to aggregation; its introduction is akin to adding a "foreign object" to a stable PEDOT:PSS colloid. During stirring, PANI aggregates are not only difficult to disperse but may also act as "coagulation nuclei," adsorbing and bridging multiple PEDOT:PSS micelles through hydrophobic interactions, leading to colloid instability, flocculation, and rapid sedimentation. This demonstrates the irreplaceable role of in-situ polymerization in achieving molecular-level composites and maintaining the colloidal stability of the system.

[0034] Example 1 constructed a highly efficient hybrid conductive network with "three-dimensional continuity + molecular-level bridging". SWCNT and FLG form a long-range framework that runs through the electrode. Conductive carbon black fills its large pores. Most importantly, in-situ polymerized PANI-PEDOT:PSS acts as a conductive binder, forming a strong molecular-level conductive "bridge" and "coating" between the active particles and carbon materials, as well as between the carbon materials themselves. PANI and PEDOT achieve efficient charge transport through π-π stacking, significantly reducing contact resistance. Comparative Example 1 is very similar to Example 1. This confirms that the pre-lithiation treatment is a chemical pre-doping process that compensates for lithium loss, but does not significantly change the electronic conductivity of the active material itself (mainly dependent on the carbon coating layer) and the construction method of the macroscopic conductive network of the electrode. Therefore, the electronic surface resistance of the electrode is basically the same. Comparative Example 2 is slightly higher than Example 1. LATP nanowires are lithium-ion conductors with extremely low electronic conductivity. Their introduction does not contribute to the electronic pathway and may even slightly block point contacts between carbon materials. Before drying, FEC exists in emulsion form; after drying, it forms an organic interface layer, which may slightly increase the resistance to interfacial electron transport. The combined effect of these two factors leads to a slight increase in sheet resistance. The comparative example shows a doubling of sheet resistance, profoundly revealing the degradation of the network structure. Physically mixed PANI, as discontinuous, highly aggregated insulating / semiconductor particles, is unevenly dispersed. It cannot form effective intermolecular charge transport with PEDOT:PSS, instead disrupting the originally continuous PEDOT:PSS conductive pathway. This introduces an additional high-resistance interface between the active material and the current collector.

[0035] Example 1 demonstrates excellent high-rate performance due to its "dual high-conductivity" network. The network consists of an ultra-low sheet resistance three-dimensional electron network for high-speed electron transport. High-speed ion transport is achieved through LATP nanowires acting as built-in fast lithium-ion channels embedded within the electrode, significantly enhancing the bulk diffusion rate of lithium ions in the thick electrode film. This synergy ensures that electrons and ions reach the reaction interface synchronously and rapidly during high-rate (high-current) charge and discharge, avoiding polarization. Comparative Example 1, while showing a seemingly high retention rate, is deceptive due to its small full-cycle reversible capacity base. At 5C high rates, its true lithium-ion diffusion kinetics are severely limited. Due to the lack of a favorable initial interface formed by pre-lithiation, its SEI is thicker and has greater impedance, resulting in slower lithium-ion diffusion across the SEI and in the bulk phase of the active material, leading to a very low actual usable capacity at high rates. The calculated high retention rate is an illusion due to the low base. Comparative Example 2 is significantly lower than Example 1, directly demonstrating the decisive contribution of LATP nanowires to rate performance. Lacking this fast ion-conducting channel, lithium-ion transport in the electrode relies entirely on the tortuous pores wetted by the electrolyte. At high rates, concentration polarization increases dramatically, leading to a rapid capacity decrease. Comparative Example 3's poor rate performance is caused by a combination of electron transport bottlenecks and potential structural inhomogeneities. On one hand, its high sheet resistance indicates slow electron transport; on the other hand, uneven distribution of binder / conductive agent due to physical mixing may cause localized obstruction of ion transport paths. Any bottleneck in electron or ion transport will be amplified at high rates, leading to performance degradation.

[0036] Example 1 achieves a perfect synergy between structural and interfacial stability. A robust, elastic bonding network composed of PAA / SA / composite conductive polymers intertwines with a flexible conductive network composed of SWCNT / FLG, forming an integrated framework similar to reinforced concrete. This effectively confines silicon particles, adapts to their volume changes, and prevents electrode pulverization. Pre-lithiation compensates for initial lithium consumption; FEC induces the formation of a dense, flexible SEI rich in LiF; and LATP participates in constructing a stable interface layer with high ionic conductivity. Together, these factors ensure the mechanical integrity and high ionic conductivity of the SEI during long-term cycling, significantly reducing the continuous consumption of active lithium and electrolyte. Comparative Example 1 exhibits the worst cycling performance, primarily due to the continuous depletion of its "lithium inventory." The unpre-lithiated material has a low initial efficiency, having already lost a significant amount of lithium. During cycling, the unstable SEI (due to the lack of FEC / LATP optimization) repeatedly breaks down and regenerates under silicon expansion, irreversibly consuming lithium and electrolyte from the positive electrode with each cycle. This cumulative lithium consumption is the dominant factor in capacity decay. Comparative Example 2 was superior to Comparative Example 1 but far inferior to Example 1, indicating that even with pre-lithiation to compensate for the "initial lithium debt," interface degradation during cycling remains a bottleneck. The lack of interface protection from FEC and LATP resulted in a SEI with poor mechanical strength and low ionic conductivity, which continuously thickened and fractured during cycling, leading to a sustained increase in impedance and slow lithium consumption, resulting in a steady decline in capacity. In Comparative Example 3, the capacity degradation was primarily due to mechanical failure. The physically mixed conductive / bonding network was uneven and fragile. Under the enormous shear forces generated by the repeated expansion and contraction of silicon particles, the active material easily detached from the conductive network, becoming "dead lithium." The conductive network itself fractured, losing its electron pathways. The electrode peeled off from the current collector. This "structural collapse" caused rapid and irreversible capacity degradation.

[0037] 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 water-based composite conductive paste for a silicon-based negative electrode in lithium batteries, characterized in that, The raw materials, by weight, include the following components: The composition includes: 20-30 parts of pre-lithiated mesoporous silicon-carbon composite material, 2-4 parts of single-walled carbon nanotube powder, 1-3 parts of graphene powder, 0.5-1.5 parts of conductive carbon black, 1-3 parts of polyacrylic acid, 0.5-1.5 parts of sodium alginate, 0.5-1.5 parts of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.3-0.9 parts of sodium carboxymethyl cellulose, 0.1-0.3 parts of nonionic surfactant, 0.1-0.3 parts of lithiumized humic acid, 1-3 parts of fluoroethylene carbonate preemulsion, 1-2 parts of lithium-ion conductor nanowires, and 80-100 parts of deionized water. The preparation method of the aqueous polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite includes the following steps: S1. Weigh the following raw materials by weight: 60-80 parts of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, 0.5-2.5 parts of aniline, 0.04-0.06 parts of ammonium persulfate, 0.01-0.03 parts of sodium dodecylbenzenesulfonate, 0.05-0.07 parts of polyvinylpyrrolidone, 0.02-0.04 parts of glutaraldehyde, and 20-30 parts of deionized water; S2. Add sodium dodecylbenzenesulfonate and polyvinylpyrrolidone to poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid dispersion, stir at 500-1000 rpm for 30-60 min in a cold water bath at 0-5℃, and add hydrochloric acid dropwise to adjust the pH value to 1.5-2.5 to obtain an acidic dispersion. S3. Add aniline slowly to the acidic dispersion at a dropping rate of 1~2 mL / min, and continue stirring in a cold water bath at 0~5℃ for 2~4 h to obtain an acidic mixture. S4. Add ammonium persulfate to deionized water, stir to dissolve, and pre-cool to 0~5℃. Add the acidic mixture dropwise over 10~30 min at a speed of 800~1200 rpm. After the addition is complete, keep the temperature at 0~5℃ and continue the reaction for 12~24 h. Let it mature at room temperature for 2~6 h. Add glutaraldehyde and stir the reaction at room temperature for 4~8 h to obtain the reaction solution. S5. Transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 8000~14000 Da, dialyze with deionized water for 48~72 hours, changing the water every 6~8 hours. After dialysis, centrifuge the liquid in the dialysis bag at a speed of 8000~12000 rpm for 20~40 minutes and collect the supernatant. S6. Add deionized water to the supernatant to adjust the solid content to 1.5~3.5wt%, then add ammonia water to adjust the pH to 3.5~5.0, mix well, and you will get an aqueous polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite.

2. The aqueous composite conductive slurry for a silicon-based negative electrode of a lithium battery according to claim 1, characterized in that, The preparation method of the pre-lithiated mesoporous silicon-carbon composite material includes the following steps: In an argon-filled glove box, mesoporous silicon-carbon composite material with a pore size of 5-20 nm is mixed with stabilized lithium metal powder at a mass ratio of 4-5:1 for 60-120 min. The mixture is then placed in an atmosphere furnace and heat-treated at 100-200℃ for 4-12 h in an argon atmosphere. The temperature is then raised to 300-500℃ for 1-2 h, followed by annealing and sieving to obtain a pre-lithiated mesoporous silicon-carbon composite anode material.

3. The aqueous composite conductive slurry for a silicon-based negative electrode of a lithium battery according to claim 1, characterized in that, The single-walled carbon nanotube powder has a diameter of 1~3nm and a length of 8~12μm.

4. The aqueous composite conductive slurry for a silicon-based negative electrode of a lithium battery according to claim 1, characterized in that, The graphene powder has 3 to 8 layers.

5. The aqueous composite conductive slurry for a silicon-based negative electrode of a lithium battery according to claim 1, characterized in that, The conductive carbon black has a particle size of 30~50nm.

6. The aqueous composite conductive slurry for a silicon-based negative electrode of a lithium battery according to claim 1, characterized in that, The nonionic surfactant includes at least one of octylphenol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and oleyl alcohol polyoxyethylene ether.

7. The aqueous composite conductive slurry for a silicon-based negative electrode of a lithium battery according to claim 1, characterized in that, The lithium-ion conductor nanowires have a diameter of 20-50 nm and a length of 0.5-1.5 μm.

8. A method for preparing an aqueous composite conductive paste for a silicon-based lithium battery anode 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; The composition includes: 20-30 parts of pre-lithiated mesoporous silicon-carbon composite material, 2-4 parts of single-walled carbon nanotube powder, 1-3 parts of graphene powder, 0.5-1.5 parts of conductive carbon black, 1-3 parts of polyacrylic acid, 0.5-1.5 parts of sodium alginate, 0.5-1.5 parts of waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid composite, 0.3-0.9 parts of sodium carboxymethyl cellulose, 0.1-0.3 parts of nonionic surfactant, 0.1-0.3 parts of lithiumized humic acid, 1-3 parts of fluoroethylene carbonate preemulsion, 1-2 parts of lithium-ion conductor nanowires, and 80-100 parts of deionized water. (2) Add single-walled carbon nanotube powder, graphene powder, and conductive carbon black to 1 / 2 of deionized water, and add sodium carboxymethyl cellulose, nonionic surfactant and lithium humic acid in sequence. Shear and disperse at a speed of 2000~5000 rpm for 15~45 min, and then continue to homogenize at a pressure of 800~1600 bar. Repeat the cycle 3~8 times to obtain a conductive agent dispersion. (3) Add polyacrylic acid, sodium alginate, and waterborne polyaniline-poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid complex to the remaining 1 / 2 of deionized water and stir at 400~800 rpm for 2~6 hours to dissolve and obtain adhesive solution. (4) Slowly add the binder solution to the conductive agent dispersion, stir and mix at a speed of 800~1500 rpm for 30~90 min, add ammonia water dropwise to adjust the pH value to 9~10, and obtain the mixture; (5) The pre-lithiated mesoporous silicon-carbon composite material, fluoroethylene carbonate pre-emulsion, and lithium-ion conductor nanowires are gradually added to the mixture in 3 to 5 batches. After each batch is added, the mixture is first stirred at 500 to 1000 rpm for 10 to 30 minutes for initial wetting, and then sheared and dispersed at 1500 to 2500 rpm for 15 to 30 minutes. After mixing evenly, the material is placed in a sand mill, and zirconium oxide balls are added at a ball-to-material ratio of 3 to 8:

1. The mixture is then ground at 200 to 400 rpm for 2 to 6 hours to obtain a grinding slurry. (6) Place the grinding slurry in an ultrasonic reactor and ultrasonically treat it for 15 to 45 minutes at a power of 500 to 1500W and a frequency of 20 to 40kHz. Stir and degas at a speed of 50 to 150 rpm for 1 to 3 hours under a pressure of -0.1 to -0.08MPa to obtain a water-based composite conductive slurry for lithium battery silicon-based negative electrode.

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