Preparation method and application of multifunctional self-repairing silicon-based material binder

Abstract

This invention relates to the field of lithium-ion battery technology, specifically to a method for preparing a multifunctional self-healing silicon-based material binder, comprising the following steps: 1. Synthesizing and preparing 1-allyl-1-methylpyrrolidone-onium bis(fluorosulfonamide)imine ionic liquid; 2. Crosslinking reaction to generate 1-allyl-1-methylpyrrolidone-onium bis(trifluoromethanesulfonyl)imine polyionic liquid; 3. Preparing (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid powder, dissolving the powder in N-methylpyrrolidone solvent to obtain a self-healing silicon-based material binder liquid composite. The binder prepared by this method can simultaneously and efficiently solve the problems of conductive network destruction, particle pulverization, repeated SEI film growth, and interface impedance rise faced by silicon-based anodes during cycling, effectively improving the energy density, cycle life, and rate performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to a multifunctional self-healing silicon-based material binder and a method for preparing battery electrodes using the binder. Background Technology

[0002] Silicon-based anodes have attracted significant attention in battery research due to their extremely high theoretical capacity and the ability of a single silicon atom to store 4.4 lithium atoms. However, during charge and discharge, the insertion / extraction of lithium ions causes silicon atoms to undergo volume changes of up to 300%, leading to instability at the solid electrolyte interface (SEI) and pulverization of silicon particles. Furthermore, the accumulation of non-conductive, non-uniform SEI components increases interfacial resistance, causing heterogeneous charge transfer during cycling. In addition, silicon is a semiconductor, and high-purity silicon exhibits very low conductivity at room temperature. These drawbacks result in rapid capacity decay of silicon anodes.

[0003] To address the issues of significant volume change and low conductivity in silicon-based anode materials during charge-discharge cycles, existing technologies typically employ binders as a solution. For example, the carboxyl groups (-COOH) in polyacrylic acid (PAA) are beneficial for lamination processes, making it particularly suitable for large-scale production. Polyvinylidene fluoride (PVDF) exhibits good thermal stability and adhesion between the current collector and active material, but its mechanical strength is insufficient to suppress the pulverization of the anode during the expansion of silicon nanoparticles. Chinese patent application CN110071289A discloses a composite binder of modified polyacrylic acid and polyionic liquid, utilizing the adhesive properties of polyacrylic acid and the ionic conductivity of the polyionic liquid. However, the polyacrylic acid prepared by this method is a pure insulator, providing only mechanical bonding and completely lacking electronic and ionic conductivity. Furthermore, since the bonding of polyacrylic acid mainly relies on hydrogen bonds and van der Waals forces, these forces are weakened in the electrolyte environment and become irreversible once broken. Additionally, the TFSI of the polyionic liquid... - Anions have a large volume and low mobility. Chinese patent application CN115101748A discloses a polyionic liquid as a surface modifier for silicon-based powder materials. By modifying the surface of the powder material, the polyionic liquid is coated on the surface of the silicon-based anode active material. Although this method can reduce the electrochemical impedance of the silicon-based anode active material and improve lithium-ion transport kinetics, it mainly improves the surface stability of individual silicon particles. However, it cannot construct a continuous and stable three-dimensional mechanical support framework and long-range electron transport pathway inside the electrode on a macroscopic scale. The overall structural integrity of the electrode still depends on another set of traditional binder and conductive agent systems. Moreover, the polyionic liquid mainly improves ionic conductivity and does not have intrinsic electronic conductivity. It belongs to a surface treatment process and still requires traditional electrode preparation processes, which increases the system complexity. Summary of the Invention

[0004] The present invention aims to provide a silicon-based material binder and its preparation method to solve the problems of poor long-cycle performance and low conductivity of current silicon-based anodes.

[0005] To achieve the above objectives, this invention provides a multifunctional polyhealing silicon-based adhesive, the structural formula of which is: .

[0006] This invention also provides a method for preparing the above-mentioned multifunctional polyhealing silicon-based material adhesive, comprising: Step 1: Synthesis and preparation of 1-allyl-1-methylpyrrolidone bis(fluorosulfonamide)imine ionic liquid: The first step is to synthesize the bromide salt intermediate, and the second step is to perform anion exchange; Step 2: Crosslinking reaction to generate 1-allyl-1-methylpyrrolidone bis(trifluoromethanesulfonyl)imide polyionic liquid: The ionic liquid is dissolved in tetrahydrofuran, and the initiator azobisisobutyronitrile is added. Heating induces free radical polymerization of the carbon-carbon double bonds. This includes the preparation of the polymerizable ionic liquid solution, initiator dispersion, static thermal polymerization, and subsequent purification.

[0007] Step 3: Preparation of (aniline-co-3-aminophenylboronic acid) / fluorinated polyionic liquid composite: The polyionic liquid obtained in Step 2, 3-aminophenylboronic acid, and aniline hydrochloride are dissolved in a polar aprotic solvent. In the presence of an oily initiator, the copolymerization reaction of aniline and 3-aminophenylboronic acid is initiated. After multiple washings and drying, the poly(aniline-co-3-aminophenylboronic acid) / polyionic liquid composite is obtained. Specifically, this includes the steps of preparing the composite reaction system, establishing a low-temperature reaction environment, adding and initiating the oxidant solution, polymerization reaction, precipitation separation, and purification.

[0008] Finally, the binder is diluted, and a silicon-based negative electrode sheet is obtained by wet homogenization: the binder prepared in step 3 is prepared to a certain concentration, and then the silicon-based material powder particles are uniformly dispersed in the binder solution. Finally, the silicon-based negative electrode sheet is obtained by slurry preparation, coating, and rolling.

[0009] Further specifying, the synthesis of the bromide intermediate in step 1 requires nitrogen protection. In a three-necked flask equipped with a magnetic stirrer, a condenser, and a nitrogen inlet tube, 1.0 equivalent of 1-methylpyrrolidine and anhydrous acetonitrile are added. The flask is then placed in an ice-water bath at 0°C, and 1.05–1.15 equivalents of anhydrous acetonitrile solution of allyl bromide is slowly added dropwise over 20–30 minutes using a constant-pressure dropping funnel. After the addition is complete, the ice bath is removed, and the reaction mixture is heated to 70–80°C under reflux at a stirring speed of 300–400 rpm for 24–26 hours. After the reaction is complete, the acetonitrile solvent is washed away by rotary evaporation to obtain a viscous liquid. The byproduct hydrogen bromide was then washed with a saturated sodium bicarbonate acetonitrile solution. The saturated sodium bicarbonate acetonitrile solution was pre-cooled to 0°C in a refrigerator. The crude product was dissolved and washed 3-4 times by vacuum filtration to obtain a white solid product—1-propenyl-1-methylpyrrolidine onium bromide. Finally, the white product was washed 3-4 times with pre-cooled pure acetonitrile and dried in a vacuum oven at a low temperature of 40-50°C.

[0010] Further specifying that the anion exchange process in step 1 is carried out in a fume hood, and the lithium salt used is lithium bis(fluorosulfonyl)imide, i.e., LiFSI. First, the bromide intermediate and lithium salt solution are prepared: 1 equivalent of white 1-propenyl-1-methylpyrrolidine onium bromide solid is dissolved in 100 mL of deionized water, and in another beaker, 1.05~1.2 equivalents of LiFSI is dissolved in 50 mL of deionized water. Anion exchange reaction was then carried out: at room temperature (25-30°C), the LiFSI solution was slowly poured into the aqueous solution of the bromide intermediate. The solution immediately became turbid. A magnetic stir bar was added, and the stirring speed was 600-800 rpm. The reaction time was 3-4 hours. The mixed solution was then transferred to a separatory funnel, and the reaction product was extracted with dichloromethane in three separate extractions. After extraction, the organic phases were combined and washed with deionized water. Anhydrous magnesium sulfate was then added to the organic phase and dried overnight (approximately 12-14 hours). The magnesium sulfate was then removed by filtration, and the organic phase was purified by passing it through a neutral alumina column. The crude product was dried under vacuum after removing dichloromethane by rotary evaporation at 80-85°C for approximately 24 hours to obtain a pale yellow transparent liquid 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imide ionic liquid monomer.

[0011] Further specifying, the process of preparing the cross-linked polyionic liquid network in step 2 includes two parts: a pre-processing material handling process and a reaction process. The pre-processing material handling is completed in a fume hood, the reaction process is completed in a glove box, and the final product handling is completed by removing the product from the glove box and transferring it to a fume hood. Pre-processing material handling: First, the 1-allyl-1-methylpyrrolidone bis(fluorosulfonyl)imide ionic liquid monomer is dissolved in a tetrahydrofuran solution and magnetically stirred to ensure thorough mixing at 400-500 rpm for 30-40 minutes, resulting in a solution concentration of 15-20 wt%. Then, azobisisobutyronitrile is added to the solution as an initiator, with an initiator concentration relative to the monomer concentration of 1-2 wt%. The homogenized mixture is then placed in a mixer and vacuum-degassed at a vacuum degree of -0.05-0.1 MPa for approximately 5-10 minutes to remove trace amounts of oxygen from the solution. The operation is completed under air conditions. The degassed solution was then transferred to a temperature-controlled heating plate / table inside a glove box to complete the free radical polymerization reaction, forming a cross-linked polyionic network structure. The reaction was carried out under an argon protective atmosphere inside the glove box. The temperature control of the heating plate was as follows: heating rate 1~2℃ / min, reaction temperature 70~80℃, and isothermal duration 24~26 hours. In the subsequent processing stage, the polymer was removed from the glove box and processed in a fume hood. The polymer fragments were placed in a stoppered conical flask and soaked in tetrahydrofuran for 24~25 hours to remove unreacted monomers. The volume of tetrahydrofuran was approximately 20~30 times the volume of the polymer. The conical flask was placed in a constant-temperature shaker and shaken at room temperature at a speed of 150~200 rpm. The washed polymer was then dried in a vacuum oven for 48~50 hours at a temperature of 80~85℃ and a vacuum degree ≤1.0 Pa to ensure complete drying of the tetrahydrofuran. Finally, the hard and brittle polymer is fed into a ball mill. The ball milling process requires argon protection to prevent moisture absorption and oxidation. The rotation speed is 300-350 rpm, and the milling time is 2-3 hours. Every 30 minutes of milling, the process is paused and cooled for 10 minutes to prevent overheating and polymer degradation. Standard molecular sieves are used for sieving, and the fraction with a particle size ≤20 μm is collected as the final polyionic liquid product.

[0012] Further specifying, the preparation of the aniline-3-aminophenylboronic acid copolymer in step 3 must be completed entirely within a fume hood. The copolymerization process includes: preparing the composite reaction system, polymerization reaction, and purification and drying processes. First, the composite reaction system is prepared: white polyionic liquid powder, aniline hydrochloride, and 3-aminophenylboronic acid are dissolved together in N-methylpyrrolidone, with the mass ratio of the three controlled at 5:3:2. The solid content of the mixed solution is 5-10 wt%. A lidded conical flask is used. The system is then sonicated until it presents a homogeneous suspension for 30-40 minutes. The polymerization reaction then proceeds: the sonicated suspension is poured into a three-necked round-bottom flask, which is placed in an ice-water environment at 0–5°C. Ammonium persulfate is dissolved in pre-cooled N-methylpyrrolidone to a concentration of approximately 0.5–0.8 g / mL. The oxidant solution is slowly added dropwise to the reaction system at a rate of 1.0–1.5 mL / min using a constant-pressure dropping funnel. The mass ratio of ammonium persulfate to reactants (aniline and 3-aminophenylboronic acid) is 1–1.1:1. After the addition is complete, the reaction is carried out in an ice bath for 12–14 hours. Subsequently, to ensure that the reaction does not run away from control due to violent exothermic reactions, and to obtain a high-quality polymer with more uniform composition, more ideal sequence distribution, and fewer conjugated skeleton defects, the reaction system is transferred to a refrigerator and allowed to stand for 12–14 hours at a temperature controlled at -25 to -20°C. The entire polymerization reaction lasts for approximately 24–28 hours. After the reaction is completed, the reaction system gradually changes from colorless to dark green. The product purification process was then carried out: the polymerization product was slowly poured into anhydrous diethyl ether, the volume of which was 10 to 12 times that of the polymer. The stirring speed was 300 to 500 rpm and the stirring time was 30 to 40 minutes. It was observed that the dark green fibers gradually precipitated completely. The precipitate was then filtered and washed three times with anhydrous diethyl ether-deionized water-anhydrous diethyl ether. The washed dark green product was then placed in a vacuum oven at a temperature of 55 to 65°C and a vacuum degree of ≤1.0 kPa for 24 to 26 hours to obtain a dark green (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder.

[0013] This invention also provides a method for preparing silicon-based negative electrode sheets using the aforementioned multifunctional polyhealing silicon-based material binder. Specifically, a wet slurry method is used. The (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder is dissolved in N-methylpyrrolidone solvent, with a binder concentration of 3 wt%. Silicon-based material powder (Si, active material) and conductive agent Super P are weighed at a mass ratio of 8:1:1 (Si:Super P: binder). The binder solution and conductive agent Super P are initially mixed in a planetary mixer. Then, nano-silicon powder is added, and the mixture is stirred at 2000 rpm for 2 hours, stopping for 5 minutes every half hour to check the slurry state, equipment heat dissipation, and replenish the N-methylpyrrolidone lost during high-speed rotation, until a uniform slurry with suitable viscosity is formed. An automatic coating machine is used to coat the slurry onto a copper foil current collector, with a wet film thickness of 150 μm. The coated electrodes were transferred to an 80°C forced-air oven for initial drying for 2 hours, followed by vacuum drying at 120°C for 12 hours to completely remove the solvent. Finally, the dried electrodes were rolled using a roller press to control the compaction density at 0.8-1.0 g / cm³. 3 The silicon-based negative electrode is punched into a circular piece with a diameter of 12 mm to obtain the required silicon-based negative electrode. The negative electrode is then assembled with a lithium sheet to form a half-cell and tested.

[0014] The technical solution of the present invention has the following characteristics: 1. This invention abandons the traditional physical mixing system of insulating binder (PAA) + conductive agent (carbon black) used in silicon-based anodes, overcoming the problems of functional separation of components, high interfacial resistance, and inability to synergistically adapt to volume expansion. The binder in this application, through molecular design, integrates the polyaniline backbone, phenylboronic acid groups, and FSI... - Polyionic liquids can be prepared into single, homogeneous, multifunctional materials through copolymerization or hydrogen bonding, achieving the integration and synergy of functions such as electron transport, ion transport, mechanical bonding, and interface stabilization, thus solving the problems of high interfacial impedance and poor synergy between functional phases.

[0015] 2. This invention possesses the advantage of intrinsic electronic and ionic dual-channel continuous conductivity. The polyaniline chains in the copolymer provide intrinsic electronic conductivity in the doped state, constructing a continuous electron transport network inside the electrode, which can significantly reduce or even replace inactive carbon black conductive agents; the embedded FSI - The polyionic liquid network provides a highly efficient lithium-ion transport channel. Among them, FSI... - Compared to common TFSI, anions - With a smaller molar volume and higher conformational flexibility, it possesses higher ionic conductivity. Therefore, a dual continuous transport network of electrons and ions is simultaneously constructed within the binder, greatly reducing the charge transfer impedance within the electrode.

[0016] 3. This invention possesses the advantages of covalent bonding and self-healing. The 3-aminophenylboronic acid unit in the copolymer, with its borate group (-B(OH)2), can undergo dehydration condensation with the silanol groups (-Si-OH) on the surface of silicon particles under coating and drying conditions, forming a strong BO-Si covalent bond. The strength of this chemical bond is far higher than that of traditional hydrogen bonds or van der Waals forces, which can strongly "anchor" the silicon particles in the binder network. Furthermore, hydrogen bonding also exists between the polyionic liquid cation and the silanol groups (-Si-OH) on the surface of the silicon particles. Simultaneously, the phenylboronic acid ester bond exhibits a certain degree of reversibility under specific conditions (such as stress, the presence of water, or alcohols). When the silicon particles undergo volume expansion / contraction, this dynamic bond can undergo reversible breakage and recombination, effectively buffering and dissipating mechanical stress and preventing the binder network from permanently breaking due to fatigue. Therefore, this binder combines the initial adhesion of strong covalent bonds with the long-term adaptability of dynamic bonds, achieving tolerance to huge volume changes (>300%) in the silicon anode.

[0017] ④ The conductive polyaniline chain and polyionic liquid of this invention possess a structural advantage that combines rigidity and flexibility. The selected 1-allyl-1-methylpyrrolidine onium polyionic liquid has a more flexible saturated pyrrolidine ring structure compared to imidazole rings, enabling the formation of a polymer matrix with a lower glass transition temperature and stronger chain segment mobility. This flexible matrix complements the rigid conductive polyaniline chain, together forming a rigid-flexible interpenetrating or cross-linked network. The flexible portion absorbs strain, while the rigid portion provides support and conductivity, giving the material as a whole good toughness, film-forming properties, and adhesion to electrode sheets. Therefore, the binder of this application can simultaneously and efficiently solve the problems faced by silicon-based anodes during cycling, such as conductive network destruction, particle pulverization, repeated SEI film growth, and increased interfacial impedance, thereby improving the energy density, cycle life, and rate performance of the battery.

[0018] The reaction process and the structural formula of the chemical substances used in this application are as follows: Attached Figure Description

[0019] Figure 1 Example 1C charge-discharge cycle performance diagram.

[0020] Figure 2 Charge-discharge cycle performance diagrams of Example 1 and Comparative Example 1.

[0021] Figure 3 Charge-discharge cycle performance diagrams of Example 2 and Comparative Example 2.

[0022] Figure 4 Charge-discharge cycle performance diagrams of Example 3 and Comparative Example 3.

[0023] Figure 5Rate performance diagrams of Examples 1 and 2 and Comparative Examples 1 and 2.

[0024] Figure 6 Impedance diagrams of Example 3 and Comparative Example 3.

[0025] Figure 7 Cross-sectional SEM images of Examples 1-3 and Comparative Examples 1-3 before and after 100 cycles.

[0026] Figure 8 Cross-sectional SEM images of Examples 1(a), (c) and Comparative Examples 1(b), (d) before and after 100 cycles.

[0027] Figure 9 Schematic diagram of current testing of adhesive after cutting and self-healing.

[0028] Figure 10 The NMR spectrum of the polymer compound prepared in Example 1. Detailed Implementation

[0029] The following detailed description, in conjunction with the accompanying drawings, provides further explanation of the specific implementation methods. Example 1:

[0030] A silicon (nanoscale) negative electrode sheet prepared using a multifunctional poly(aniline-copolymer-aminophenylboronic acid) / fluorinated polyionic liquid self-healing silicon-based material binder includes the following steps: Step 1: Synthesis and preparation of 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonamide)imine ionic liquid: The first step involves the synthesis of the bromide intermediate. Nitrogen protection is required during this process. In a three-necked flask equipped with a magnetic stirrer, a condenser, and a nitrogen inlet tube, 1.0 equivalent of 1-methylpyrrolidine and anhydrous acetonitrile are added. The flask is then placed in an ice-water bath at 0°C. Using a constant-pressure dropping funnel, 1.05 equivalents of anhydrous acetonitrile solution of allyl bromide is slowly added dropwise over 20–30 minutes. After the addition is complete, the ice bath is removed, and the reaction mixture is heated to 70°C and refluxed at a stirring speed of 300–400 rpm for 24 hours. After the reaction is complete, the acetonitrile solvent is removed by rotary evaporation, yielding a viscous liquid. The byproduct hydrogen bromide was then washed with a saturated sodium bicarbonate acetonitrile solution. The saturated sodium bicarbonate acetonitrile solution was pre-cooled to 0°C in a refrigerator. The crude product was dissolved and washed 3-4 times by vacuum filtration to obtain a white solid product—1-propenyl-1-methylpyrrolidine onium bromide. Finally, the white product was washed 3-4 times with pre-cooled pure acetonitrile and dried in a vacuum oven at a low temperature of 40-50°C.

[0031] The second step is anion exchange: The anion exchange process is carried out in a fume hood. The lithium salt used is lithium bis(fluorosulfonyl)imide (LiFSI). First, the bromide intermediate and lithium salt solution are prepared: 1 equivalent of white 1-propenyl-1-methylpyrrolidine onium bromide solid is dissolved in 100 mL of deionized water. In another beaker, 1.05 equivalent of LiFSI is dissolved in 50 mL of deionized water. Anion exchange reaction was then carried out: at room temperature (25°C), the LiFSI solution was slowly poured into the aqueous solution of the bromide intermediate. The solution immediately became turbid. A magnetic stir bar was added, and the stirring speed was 600 rpm for 3 hours. The mixed solution was then transferred to a separatory funnel, and the reaction product was extracted with dichloromethane in three extractions. After extraction, the organic phases were combined and washed with deionized water. Anhydrous magnesium sulfate was then added to the organic phase and dried overnight (approximately 12-14 hours). The magnesium sulfate was then removed by filtration, and the organic phase was purified by passing it through a neutral alumina column. The crude product was dried under vacuum after removing dichloromethane by rotary evaporation at 80-85°C for approximately 24 hours to obtain a pale yellow, transparent liquid 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imine ionic liquid monomer. Proton nuclear magnetic resonance (NMR) was used to analyze the reaction. 1 H NMR), fluorine nuclear magnetic resonance (NMR) 19 The molecular structure and composition of DFIL were verified by 300 MHz F NMR spectroscopy (Bruker AvanceIII HD) and gas chromatography-high resolution time-of-flight mass spectrometry (JEOLJMS-T2000GC).

[0032] Step 2: Crosslinking reaction generates 1-allyl-1-methylpyrrolidineonium bis(trifluoromethanesulfonyl)imine polyionic liquid: The first step is the pre-processing of materials: First, the 1-allyl-1-methylpyrrolidone bis(fluorosulfonyl)imide ionic liquid monomer is dissolved in a tetrahydrofuran solution and magnetically stirred at 400 rpm for 30 minutes to ensure thorough mixing, resulting in a solution concentration of 15 wt%. Then, azobisisobutyronitrile is added to the solution as an initiator at a concentration of 1 wt% relative to the monomer concentration. The homogenized mixture is then placed in a mixer (or vacuum oven) and vacuumed to remove bubbles at a vacuum level of -0.05 to 0.1 MPa for approximately 5 to 10 minutes to remove trace amounts of oxygen from the solution. The process is completed under air conditions.

[0033] The second step is the reaction process: the degassed solution is transferred to a heated platform / hot plate with programmable temperature control inside a glove box to complete the free radical polymerization reaction, forming a cross-linked polyionic network structure. The reaction is carried out under an argon protective atmosphere inside the glove box. The temperature control of the heating plate is: heating rate 1℃ / min, reaction temperature 70℃, and constant temperature time 24 hours. In the subsequent processing stage, the polymer needs to be removed from the glove box and processed in a fume hood. The polymer fragments are placed in a stoppered conical flask and soaked in tetrahydrofuran for 24-25 hours to remove unreacted monomers. The volume of tetrahydrofuran is approximately 20-30 times the volume of the polymer. The conical flask is placed in a constant-temperature shaker and shaken at room temperature at a speed of 150-200 rpm. The washed polymer is then dried in a vacuum oven for 48-50 hours at a temperature of 80-85℃ and a vacuum degree ≤1.0 Pa to ensure complete drying of the tetrahydrofuran. Finally, the hard and brittle polymer was fed into a ball mill. The ball milling process required argon protection to prevent moisture absorption and oxidation. The rotation speed was 300-350 rpm, and the milling time was 2 hours. Every 30 minutes of milling, the process was paused and allowed to cool for 10 minutes to prevent overheating and polymer degradation. Standard molecular sieves were used for sieving, and particles with a diameter ≤20 μm were collected as the final polyionic liquid product.

[0034] Step 3: Preparation of (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite: Preparation of the composite reaction system: White polyionic liquid powder, aniline hydrochloride, and 3-aminophenylboronic acid were dissolved together in N-methylpyrrolidone at a mass ratio of 5:3:2, and the solid content of the mixed solution was 5 wt%. A lidded conical flask was used. The system was then sonicated until a homogeneous suspension was achieved, for 30-40 minutes. Polymerization reaction was then carried out: The sonicated suspension was poured into a three-necked round-bottom flask, which was placed in an ice-water environment at 0-5°C. Ammonium persulfate (APS) was dissolved in pre-cooled N-methylpyrrolidone to a concentration of approximately 0.5 g / mL. The oxidant solution was slowly added dropwise to the reaction system at a rate of 1.0 mL / min using a constant-pressure dropping funnel. The mass ratio of ammonium persulfate to reactants (aniline and 3-aminophenylboronic acid) was 1:1.

[0035] Polymerization reaction: After the addition was completed, the reaction was carried out in an ice bath for 12 hours. Then, to ensure that the reaction would not get out of control due to violent exothermic reaction, and to obtain a high-quality polymer with more uniform composition, more ideal sequence distribution and fewer conjugated skeleton defects, the reaction system was transferred to a refrigerator and left to stand for 12 hours. The refrigerator temperature was controlled at -25~-20℃. The entire polymerization reaction lasted for about 24 hours. After the reaction was completed, the reaction system gradually changed from colorless to dark green.

[0036] Purification and drying process: The polymerization product is slowly poured into anhydrous diethyl ether, the volume of which is 10 to 12 times that of the polymer. The stirring speed is 300 to 500 rpm and the stirring time is 30 to 40 minutes. The dark green fibers are observed to gradually precipitate completely. The precipitate is then filtered and washed three times with anhydrous diethyl ether-deionized water-anhydrous diethyl ether. The washed dark green product is then placed in a vacuum oven at a temperature of 55 to 65°C and a vacuum degree of ≤1.0 kPa for 24 to 26 hours to obtain a dark green (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder.

[0037] The binder was diluted, and a silicon-based negative electrode sheet was obtained using a wet homogenization method. The selected active material is nano-silicon powder (D 50 <100nm). The (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder was dissolved in N-methylpyrrolidone solvent with a binder concentration of 3wt%. Nano-silicon powder (Si, active material) and conductive agent Super P were weighed at a mass ratio of 8:1:1 (Si:Super P: binder). The binder solution and conductive agent Super P were initially mixed in a planetary mixer, then the nano-silicon powder was added. The mixture was stirred at 2000 rpm for 2 hours, stopping for 5 minutes every half hour to check the slurry state, equipment heat dissipation, and replenish any N-methylpyrrolidone lost during high-speed stirring, until a uniform slurry with suitable viscosity was formed. The slurry was coated onto a copper foil current collector using an automatic coating machine, with a wet film thickness of 150μm. The coated electrode was transferred to an 80°C forced-air oven for initial drying for 2 hours, followed by vacuum drying at 120°C for 12 hours to completely remove the solvent. Finally, the dried electrode sheets are rolled using a roller press, with the compaction density controlled at 0.8-1.0 g / cm³. 3 The silicon-based negative electrode is obtained by punching out a circular sheet with a diameter of 12 mm. The negative electrode is then assembled with a lithium sheet to form a half-cell and tested. Example 2:

[0038] A silicon (micron-scale) negative electrode sheet prepared using a multifunctional poly(aniline-copolymer-aminophenylboronic acid) / fluorinated polyionic liquid self-healing silicon-based material binder includes the following steps: Step 1: Synthesis and preparation of 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonamide)imine ionic liquid: The first step involves the synthesis of the bromide intermediate. Nitrogen protection is required during this process. In a three-necked flask equipped with a magnetic stirrer, a condenser, and a nitrogen inlet tube, 1.0 equivalent of 1-methylpyrrolidine and anhydrous acetonitrile are added. The flask is then placed in an ice-water bath at 0°C. Using a constant-pressure dropping funnel, 1.15 equivalents of anhydrous acetonitrile solution of allyl bromide is slowly added dropwise over 20–30 minutes. After the addition is complete, the ice bath is removed, and the reaction mixture is heated to 80°C and refluxed at a stirring speed of 300–400 rpm for 26 hours. After the reaction is complete, the acetonitrile solvent is removed by rotary evaporation, yielding a viscous liquid. The byproduct hydrogen bromide was then washed with a saturated sodium bicarbonate acetonitrile solution. The saturated sodium bicarbonate acetonitrile solution was pre-cooled to 0°C in a refrigerator. The crude product was dissolved and washed 3-4 times by vacuum filtration to obtain a white solid product—1-propenyl-1-methylpyrrolidine onium bromide. Finally, the white product was washed 3-4 times with pre-cooled pure acetonitrile and dried in a vacuum oven at a low temperature of 40-50°C.

[0039] The second step is anion exchange: The anion exchange process is carried out in a fume hood. The lithium salt used is lithium bis(fluorosulfonyl)imide (LiFSI). First, the bromide intermediate and lithium salt solution are prepared: 1 equivalent of white 1-propenyl-1-methylpyrrolidine onium bromide solid is dissolved in 100 mL of deionized water. In another beaker, 1.2 equivalents of LiFSI is dissolved in 50 mL of deionized water. Anion exchange reaction was then carried out: at room temperature (25°C), the LiFSI solution was slowly poured into the aqueous solution of the bromide intermediate, and the solution immediately became turbid. A magnetic stir bar was added, and the stirring speed was 600 rpm. The reaction time was 4 hours. The mixed solution was then transferred to a separatory funnel, and the reaction product was extracted with dichloromethane in three extractions. After extraction, the organic phases were combined and washed with deionized water. Anhydrous magnesium sulfate was then added to the organic phase and dried overnight, about 12-14 hours. The magnesium sulfate was then removed by filtration, and the organic phase was purified by passing it through a neutral alumina column. The crude product was dried under vacuum after removing dichloromethane by rotary evaporation at 80-85°C for about 24 hours to obtain a pale yellow transparent liquid 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imide ionic liquid monomer.

[0040] Step 2: Crosslinking reaction generates 1-allyl-1-methylpyrrolidineonium bis(trifluoromethanesulfonyl)imine polyionic liquid: The first step is the pre-processing of materials: First, the 1-allyl-1-methylpyrrolidone bis(fluorosulfonyl)imide ionic liquid monomer is dissolved in a tetrahydrofuran solution and magnetically stirred at 400 rpm for 30 minutes to ensure thorough mixing, resulting in a solution concentration of 20 wt%. Then, azobisisobutyronitrile is added to the solution as an initiator at a concentration of 2 wt% relative to the monomer concentration. The homogenized mixture is then placed in a mixer (or vacuum oven) and vacuumed to remove bubbles at a vacuum level of -0.05 to 0.1 MPa for approximately 5 to 10 minutes to remove trace amounts of oxygen from the solution. The process is completed under air conditions.

[0041] The second step is the reaction process: the degassed solution is transferred to a heated platform / hot plate with programmable temperature control inside a glove box to complete the free radical polymerization reaction, forming a cross-linked polyionic network structure. The reaction is carried out under an argon protective atmosphere inside the glove box. The temperature control of the heating plate is: heating rate 2℃ / min, reaction temperature 80℃, and constant temperature time 26 hours. In the subsequent processing stage, the polymer needs to be removed from the glove box and processed in a fume hood. The polymer fragments are placed in a stoppered conical flask and soaked in tetrahydrofuran for 24-25 hours to remove unreacted monomers. The volume of tetrahydrofuran is approximately 20-30 times the volume of the polymer. The conical flask is placed in a constant-temperature shaker and shaken at room temperature at a speed of 150-200 rpm. The washed polymer is then dried in a vacuum oven for 48-50 hours at a temperature of 80-85℃ and a vacuum degree ≤1.0 Pa to ensure complete drying of the tetrahydrofuran. Finally, the hard and brittle polymer was fed into a ball mill. The ball milling process required argon protection to prevent moisture absorption and oxidation. The rotation speed was 300-350 rpm, and the milling time was 3 hours. Every 30 minutes of milling, the process was paused and allowed to cool for 10 minutes to prevent overheating and polymer degradation. Standard molecular sieves were used for sieving, and particles with a diameter ≤20 μm were collected as the final polyionic liquid product.

[0042] Step 3: Preparation of (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite: Preparation of the composite reaction system: White polyionic liquid powder, aniline hydrochloride, and 3-aminophenylboronic acid were dissolved together in N-methylpyrrolidone at a mass ratio of 5:3:2, and the solid content of the mixed solution was 10 wt%. A lidded conical flask was used. The system was then sonicated until a homogeneous suspension was achieved, for 30-40 minutes. Polymerization reaction was then carried out: The sonicated suspension was poured into a three-necked round-bottom flask, which was placed in an ice-water environment at 0-5°C. Persulfate (APS) was dissolved in pre-cooled N-methylpyrrolidone to a concentration of approximately 0.8 g / mL. The oxidant solution was slowly added dropwise to the reaction system at a rate of 1.0 mL / min using a constant-pressure dropping funnel. The mass ratio of ammonium persulfate to reactants (aniline and 3-aminophenylboronic acid) was 1.1:1.

[0043] Polymerization reaction: After the addition was completed, the reaction was carried out in an ice bath for 14 hours. Then, to ensure that the reaction would not get out of control due to violent exothermic reaction, and to obtain a high-quality polymer with more uniform composition, more ideal sequence distribution and fewer conjugated skeleton defects, the reaction system was transferred to a refrigerator and left to stand for 14 hours. The refrigerator temperature was controlled at -25~-20℃. The entire polymerization reaction lasted for about 28 hours. After the reaction was completed, the reaction system gradually changed from colorless to dark green.

[0044] Purification and drying process: The polymerization product is slowly poured into anhydrous diethyl ether, the volume of which is 10 to 12 times that of the polymer. The stirring speed is 300 to 500 rpm and the stirring time is 30 to 40 minutes. The dark green fibers are observed to gradually precipitate completely. The precipitate is then filtered and washed three times with anhydrous diethyl ether-deionized water-anhydrous diethyl ether. The washed dark green product is then placed in a vacuum oven at a temperature of 55 to 65°C and a vacuum degree of ≤1.0 kPa for 24 to 26 hours to obtain a dark green (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder.

[0045] The binder was diluted, and a silicon-based negative electrode sheet was obtained using a wet homogenization method. The selected active material is micron-sized silicon powder (D 50=1µm). The (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder was dissolved in N-methylpyrrolidone solvent with a binder concentration of 3wt%. Nano-silicon powder (Si, active material) and conductive agent Super P were weighed at a mass ratio of 8:1:1 (Si:Super P: binder). The binder solution and conductive agent Super P were initially mixed in a planetary mixer, then the nano-silicon powder was added. The mixture was stirred at 2000 rpm for 2 hours, stopping for 5 minutes every half hour to check the slurry state, equipment heat dissipation, and replenish any N-methylpyrrolidone lost during high-speed stirring, until a uniform slurry with suitable viscosity was formed. The slurry was coated onto a copper foil current collector using an automatic coating machine, with a wet film thickness of 150 μm. The coated electrode was transferred to an 80°C forced-air oven for initial drying for 2 hours, followed by vacuum drying at 120°C for 12 hours to completely remove the solvent. Finally, the dried electrode sheets are rolled using a roller press, with the compaction density controlled at 0.8-1.0 g / cm³. 3 The silicon-based negative electrode is obtained by punching out a circular sheet with a diameter of 12 mm. The negative electrode is then assembled with a lithium sheet to form a half-cell and tested. Example 3:

[0046] A silicon suboxide (micron-scale) negative electrode sheet prepared using a multifunctional poly(aniline-copolymer-aminophenylboronic acid) / fluorinated polyionic liquid self-healing silicon-based material binder includes the following steps: Step 1: Synthesis and preparation of 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonamide)imine ionic liquid: The first step involves the synthesis of the bromide intermediate. Nitrogen protection is required during this process. In a three-necked flask equipped with a magnetic stirrer, a condenser, and a nitrogen inlet tube, 1.0 equivalent of 1-methylpyrrolidine and anhydrous acetonitrile are added. The flask is then placed in an ice-water bath at 0°C. Using a constant-pressure dropping funnel, 1.1 equivalents of anhydrous acetonitrile solution of allyl bromide is slowly added dropwise over 20–30 minutes. After the addition is complete, the ice bath is removed, and the reaction mixture is heated to 75°C and refluxed at a stirring speed of 300–400 rpm for 25 hours. After the reaction is complete, the acetonitrile solvent is removed by rotary evaporation, yielding a viscous liquid. The byproduct hydrogen bromide was then washed with a saturated sodium bicarbonate acetonitrile solution. The saturated sodium bicarbonate acetonitrile solution was pre-cooled to 0°C in a refrigerator. The crude product was dissolved and washed 3-4 times by vacuum filtration to obtain a white solid product—1-propenyl-1-methylpyrrolidine onium bromide. Finally, the white product was washed 3-4 times with pre-cooled pure acetonitrile and dried in a vacuum oven at a low temperature of 40-50°C.

[0047] The second step is anion exchange: The anion exchange process is carried out in a fume hood. The lithium salt used is lithium bis(fluorosulfonyl)imide (LiFSI). First, the bromide intermediate and lithium salt solution are prepared: 1 equivalent of white 1-propenyl-1-methylpyrrolidine onium bromide solid is dissolved in 100 mL of deionized water. In another beaker, 1.1 equivalent of LiFSI is dissolved in 50 mL of deionized water. Anion exchange reaction was then carried out: at room temperature (25°C), the LiFSI solution was slowly poured into the aqueous solution of the bromide intermediate, and the solution immediately became turbid. A magnetic stir bar was added, and the magnetic stirring speed was 600 rpm for 3.5 hours. The mixed solution was then transferred to a separatory funnel, and the reaction product was extracted with dichloromethane in three extractions. After extraction, the organic phases were combined and washed with deionized water. Anhydrous magnesium sulfate was then added to the organic phase and dried overnight, about 12-14 hours. The magnesium sulfate was then removed by filtration, and the organic phase was purified by passing it through a neutral alumina column. The crude product was dried under vacuum after removing dichloromethane by rotary evaporation at 80-85°C for about 24 hours to obtain a pale yellow transparent liquid 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imide ionic liquid monomer.

[0048] Step 2: Crosslinking reaction generates 1-allyl-1-methylpyrrolidineonium bis(trifluoromethanesulfonyl)imine polyionic liquid: The first step is the pre-processing of materials: First, the 1-allyl-1-methylpyrrolidone bis(fluorosulfonyl)imide ionic liquid monomer is dissolved in a tetrahydrofuran solution and magnetically stirred at 400 rpm for 30 minutes to ensure thorough mixing, resulting in a solution concentration of 18 wt%. Then, azobisisobutyronitrile is added to the solution as an initiator at a concentration of 1.5 wt% relative to the monomer concentration. The homogenized mixture is then placed in a mixer (or vacuum oven) and vacuumed to remove bubbles at a vacuum level of -0.05 to 0.1 MPa for approximately 5 to 10 minutes to remove trace amounts of oxygen from the solution. The process is completed under air conditions.

[0049] The second step is the reaction process: the degassed solution is transferred to a heated platform / hot plate with programmable temperature control inside a glove box to complete the free radical polymerization reaction, forming a cross-linked polyionic network structure. The reaction is carried out under an argon protective atmosphere inside the glove box. The temperature control of the heating plate is: heating rate 1.5℃ / min, reaction temperature 75℃, and constant temperature time 25 hours. In the subsequent processing stage, the polymer needs to be removed from the glove box and processed in a fume hood. The polymer fragments are placed in a stoppered conical flask and soaked in tetrahydrofuran for 24-25 hours to remove unreacted monomers. The volume of tetrahydrofuran is approximately 20-30 times the volume of the polymer. The conical flask is placed in a constant-temperature shaker and shaken at room temperature at a speed of 150-200 rpm. The washed polymer is then dried in a vacuum oven for 48-50 hours at a temperature of 80-85℃ and a vacuum degree ≤1.0 Pa to ensure complete drying of the tetrahydrofuran. Finally, the hard and brittle polymer was fed into a ball mill. The ball milling process required argon protection to prevent moisture absorption and oxidation. The rotation speed was 300-350 rpm, and the milling time was 2.5 hours. Every 30 minutes of milling, the process was paused and allowed to cool for 10 minutes to prevent overheating and polymer degradation. Standard molecular sieves were used for sieving, and particles with a diameter ≤20 μm were collected as the final polyionic liquid product.

[0050] Step 3: Preparation of (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite: Preparation of the composite reaction system: White polyionic liquid powder, aniline hydrochloride, and 3-aminophenylboronic acid were dissolved together in N-methylpyrrolidone at a mass ratio of 5:3:2, and the solid content of the mixed solution was 8 wt%. A lidded conical flask was used. The system was then sonicated until a homogeneous suspension was achieved, for 30-40 minutes. Polymerization reaction was then carried out: The sonicated suspension was poured into a three-necked round-bottom flask, which was placed in an ice-water environment at 0-5°C. Ammonium persulfate (APS) was dissolved in pre-cooled N-methylpyrrolidone to a concentration of approximately 0.6 g / mL. The oxidant solution was slowly added dropwise to the reaction system at a rate of 1.0 mL / min using a constant-pressure dropping funnel. The mass ratio of ammonium persulfate to reactants (aniline and 3-aminophenylboronic acid) was 1.05:1.

[0051] Polymerization reaction: After the addition was completed, the reaction was carried out in an ice bath for 13 hours. Then, to ensure that the reaction would not get out of control due to violent exothermic reaction, and to obtain a high-quality polymer with more uniform composition, more ideal sequence distribution and fewer conjugated skeleton defects, the reaction system was transferred to a refrigerator and left to stand for 13 hours. The refrigerator temperature was controlled at -25~-20℃. The entire polymerization reaction lasted for about 26 hours. After the reaction was completed, the reaction system gradually changed from colorless to dark green.

[0052] Purification and drying process: The polymerization product is slowly poured into anhydrous diethyl ether, the volume of which is 10 to 12 times that of the polymer. The stirring speed is 300 to 500 rpm and the stirring time is 30 to 40 minutes. The dark green fibers are observed to gradually precipitate completely. The precipitate is then filtered and washed three times with anhydrous diethyl ether-deionized water-anhydrous diethyl ether. The washed dark green product is then placed in a vacuum oven at a temperature of 55 to 65°C and a vacuum degree of ≤1.0 kPa for 24 to 26 hours to obtain a dark green (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder.

[0053] The binder was diluted, and a silicon-based negative electrode sheet was obtained using a wet homogenization method. The selected active material is micron-sized silica fume (D). 50 =5um). The (aniline-copoly-3-aminophenylboronic acid) / fluorinated polyionic liquid composite powder was dissolved in N-methylpyrrolidone solvent with a binder concentration of 3wt%. Nano-silicon powder (Si, active material) and conductive agent Super P were weighed at a mass ratio of 8:1:1 (Si:Super P: binder). The binder solution and conductive agent Super P were initially mixed in a planetary mixer, then the nano-silicon powder was added. The mixture was stirred at 2000 rpm for 2 hours, stopping for 5 minutes every half hour to check the slurry state, equipment heat dissipation, and replenish any N-methylpyrrolidone lost during high-speed stirring, until a uniform slurry with suitable viscosity was formed. The slurry was coated onto a copper foil current collector using an automatic coating machine, with a wet film thickness of 150 μm. The coated electrode was transferred to an 80°C forced-air oven for initial drying for 2 hours, followed by vacuum drying at 120°C for 12 hours to completely remove the solvent. Finally, the dried electrode sheets are rolled using a roller press, with the compaction density controlled at 0.8-1.0 g / cm³. 3 The silicon-based negative electrode is obtained by punching out a circular sheet with a diameter of 12 mm. The negative electrode is then assembled with a lithium sheet to form a half-cell and tested.

[0054] Comparative Example 1: The difference from Example 1 is that polyionic liquid was not used, that is, steps 1 and 2 were missing. Also, polyionic liquid powder was not added when preparing the composite reaction system in step 3. The rest of the preparation methods and parameters are the same as those in Example 1.

[0055] Comparative Example 2: The difference from Example 2 is that aniline-copolymerized 2-aminophenylboronic acid was not used, i.e. step 3 was missing. In step 4, the binder used was a polyionic liquid and PAA=1:1 binder (when using pure polyionic liquid, it was observed that the material was severely powdered during coating, making it impossible to carry out subsequent battery preparation work. Therefore, a conventional binder was used to mix with polyionic liquid to improve adhesion). The rest of the preparation methods and parameters are the same as in Example 2.

[0056] Comparative Example 3: The difference from Example 1 is that the most conventional adhesive is used in step 4, namely CMC and SBR, with silicon suboxide:SP:CMM+SBR=8:1:1.

[0057] Impedance and half-cell tests were performed on the silicon suboxide button cells obtained in Examples 1-3 and Comparative Examples 1-3. The specific test methods are as follows: (1) Cyclic performance test method: The half-cell was charged and discharged at 0.1C for the first 3 weeks, and then charged and discharged at 1C rate after the 4th week. The voltage range was 0.001~1.5V, and the cycle was 100 times to test its capacity and its retention rate.

[0058] (2) Rate performance test method: The half-cell was charged and discharged at 0.1C for the first 3 weeks. After the 4th week, it was charged and discharged at 0.5C, 1C, 2C, 4C, 5C and 1C. The voltage range was 0.001~1.5V. Each cycle was 5 rounds. The capacity and retention rate at 1C were tested.

[0059] The electrical performance test results of the batteries prepared from the materials of Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0060] Table 1 Battery performance test data Other test results such as Figure 1-10 As shown in the above examples and comparative examples, the experimental and testing results demonstrate that, compared to lithium batteries prepared using a single aniline-copolymer 3-aminophenylboronic acid copolymer, fluorinated polyionic liquid (which cannot be bonded and requires the addition of PAA binder), or traditional CMC+SBR binders, lithium batteries prepared using the composite binder made from aniline-copolymer 3-aminophenylboronic acid / fluorinated polyionic liquid exhibit significantly improved cycle performance, capacity retention, and electrode expansion, regardless of whether the half-cell is made of pure silicon or silicon suboxide. The composite binder prepared in this invention, as a binder for silicon-based anode materials in lithium-ion batteries, can effectively improve the cycle stability of the battery and effectively reduce the internal resistance of lithium-ion transport, showing promising application prospects.

[0061] Other reagents with similar properties and the selection of similar reaction parameters can be determined by those skilled in the art based on common knowledge. The above descriptions are merely embodiments of the present invention, and the specific structures, properties, and reactant ratios known in the schemes are not described in detail here. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, such as simply adjusting the selection of parameters within or near a specified parameter range. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a multifunctional self-healing silicon-based material adhesive, characterized in that, include: Step 1: Synthesize 1-propenyl-1-methylpyrrolidineonium bromide and perform anion exchange to prepare 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonamide)imine ionic liquid; Step 2: Dissolve the ionic liquid obtained in Step 1 in tetrahydrofuran, add an initiator, and heat to induce free radical polymerization of carbon-carbon double bonds to prepare 1-allyl-1-methylpyrrolidone-onium bis(fluorosulfonamide)imine polyionic liquid; Step 3: Dissolve the polyionic liquid, 3-aminophenylboronic acid and aniline hydrochloride obtained in Step 2 in a polar aprotic solvent. Initiate the copolymerization reaction of aniline and 3-aminophenylboronic acid in the presence of an oily initiator. After washing, drying and pulverizing, obtain (aniline-copolymer-3-aminophenylboronic acid) / fluorinated polyionic liquid powder. Dissolve the powder in N-methylpyrrolidone solvent to obtain a dark green self-healing silicon-based material binder.

2. The preparation method of the multifunctional self-healing silicon-based material adhesive according to claim 1, characterized in that: In step 1, the synthesis of the bromide intermediate is carried out under nitrogen protection. At 0-5°C, 1.0 equivalent of 1-methylpyrrolidone and 1.05-1.15 equivalents of allyl bromide solution are added to the reaction vessel in anhydrous acetonitrile.

3. The preparation method of a multifunctional self-healing silicon-based material adhesive according to claim 2, characterized in that: In step 1, during the synthesis of the bromide intermediate, the reactants are added dropwise over 20-30 minutes. After the addition is complete, the reaction mixture is heated to reflux at 70-80°C while being stirred at 300-400 rpm for 24-26 hours. After the reaction is complete, the solvent and byproducts are removed by rotary evaporation. The crude product is washed with a saturated sodium bicarbonate acetonitrile solution and then vacuum filtered to obtain 1-propenyl-1-methylpyrrolidineonium bromide.

4. The preparation method of a multifunctional self-healing silicon-based material adhesive according to claim 1, characterized in that: The lithium salt selected for the anion exchange process in step 1 is lithium bis(fluorosulfonyl)imide (LiFSI). First, a bromide intermediate and a lithium salt solution are prepared. One equivalent of 1-propenyl-1-methylpyrrolidine onium bromide is dissolved in deionized water to obtain an aqueous solution of the bromide intermediate. Then, 1.05 to 1.2 equivalents of LiFSI is dissolved in deionized water to obtain a LiFSI solution. Subsequently, anion exchange reaction was carried out by slowly pouring the LiFSI solution into the aqueous solution of the bromide intermediate. The reaction temperature was 25-30℃, the stirring speed was 600-800 rpm, and the reaction time was 3-4 hours. After that, the product was extracted with dichloromethane in fractions. The combined organic phases were washed with deionized water, and then a drying agent was added to the organic phase for drying. After filtration, the product was filtered and purified by passing it through a neutral alumina column. The crude product was dried under vacuum after removing dichloromethane by rotary evaporation at a temperature of 80-85℃ to obtain the ionic liquid monomer of 1-allyl-1-methylpyrrolidineonium bis(fluorosulfonyl)imine.

5. The method for preparing a multifunctional self-healing silicon-based material adhesive according to claim 1, characterized in that: In step 2, the 1-allyl-1-methylpyrrolidone bis(fluorosulfonyl)imide ionic liquid monomer is dissolved in a tetrahydrofuran solution and magnetically stirred at 400-500 rpm for 30-40 minutes, with a solution concentration of 15-20 wt%. Then, the initiator azobisisobutyronitrile is added to the solution at a concentration of 1-2 wt% relative to the monomer. The mixture is stirred evenly at room temperature, and the homogeneous mixture is subjected to a vacuum of -0.05 to -0.1 MPa to remove air bubbles. The degassed solution is then heated under an argon atmosphere to complete the free radical polymerization reaction to form a cross-linked polyionic liquid.

6. The method for preparing a multifunctional self-healing silicon-based material adhesive according to claim 5, characterized in that: The degassed solution was heated under an argon atmosphere at a heating rate of 1-2 °C / min, with a reaction temperature of 70-80 °C and a holding time of 24-26 hours. The resulting cross-linked polyionic liquid had an average molecular weight between cross-linking points of 500-2000 g / mol, a glass transition temperature of -20 to 20 °C, and an ionic conductivity of 10. -5 ~10 -3 S / cm, elongation at break is 10~50%.

7. The preparation method of a multifunctional self-healing silicon-based material adhesive according to claim 5, characterized in that: In step 2, after preparing the cross-linked polyionic liquid, purification and mechanical pulverization are also performed. First, the cross-linked polyionic liquid fragments are soaked in tetrahydrofuran to remove unreacted monomers. Then, they are washed and dried to remove tetrahydrofuran. Finally, the polymer is ball-milled and sieved under argon protection to collect polyionic liquid powder with a particle size ≤20um.

8. The method for preparing a multifunctional self-healing silicon-based material adhesive according to claim 1, characterized in that: In step 3, a composite reaction system is first prepared. The polyionic liquid powder obtained in step 2 is dissolved together with aniline hydrochloride and 3-aminophenylboronic acid in N-methylpyrrolidone. The mass ratio of the three is controlled at 5:3:

2. The mixture is mixed until a homogeneous suspension is formed and pre-cooled. Then, ammonium persulfate is dissolved in the pre-cooled N-methylpyrrolidone. The mass ratio of ammonium persulfate to aniline and 3-aminophenylboronic acid is 1~1.1:

1. The polymerization reaction is then carried out under ice bath conditions for 12~14 hours. The reaction system is then allowed to stand at -20~-25℃ for 12~14 hours. After that, the product is separated and vacuum dried to obtain (aniline-copoly-3-aminophenylboronic acid) / polyionic liquid composite powder.

9. A method for preparing silicon-based negative electrode sheets using the multifunctional self-healing silicon-based material binder as described in claim 1, characterized in that, The steps include the following: Configure the adhesive to the designed concentration; Silicon-based material powder and conductive agent are uniformly dispersed in a binder solution; Silicon-based negative electrode sheets are obtained through pulping, coating, and rolling.

10. The method for preparing a silicon-based negative electrode sheet according to claim 9, characterized in that: In step 1, nano-silicon powder, conductive agent Super P, and binder are weighed at a mass ratio of 8:1:1, with the binder solution concentration being 3 wt%. In step 2, the binder solution and conductive agent Super P are initially mixed, and then nano-silicon powder is added and stirred to form a uniform slurry. In step 3, an automatic coating machine is used to coat the slurry onto the copper foil current collector, setting the wet film thickness to 150 μm. The coated electrode is then vacuum-dried to completely remove the solvent. Finally, a roller press is used to roll the dried electrode, controlling the compaction density to 0.8-1.0 g / cm³. 3 The silicon-based negative electrode sheet is obtained by cutting.

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