Dynamic self-adaptive lithium-conducting network binder for sulfide all-solid-state battery

Abstract

The invention relates to the technical field of sulfide all-solid-state batteries, in particular to a dynamic self-adaptive lithium-conducting network binder for a sulfide all-solid-state battery, which comprises a triblock copolymer and a dynamic cross-linking agent, the triblock copolymer comprises a polybutadiene chain segment, a poly (4-vinylpyridine) chain segment and a poly (itaconic acid-co-hydroxyethyl methylacrylate) chain segment, wherein the polybutadiene chain segment is prepared by polymerizing butadiene; the poly (4-vinylpyridine) chain segment is prepared by polymerizing 4-vinylpyridine; the dynamic cross-linking agent is one or two of 1, 4-benzene diboronic acid and p-benzene diboronic acid pinacol ester. In the preparation process, each functional chain segment of the binder respectively provides strong coordination bonds, ion conduction capability and thermoplasticity, and meanwhile, borate bonds provide a dynamic network, so that high binding power, strong ion conduction capability, interface reaction resistance, flexibility self-adaption and machinability are synergistically provided.

Description

Technical Field

[0001] This invention relates to the field of sulfide all-solid-state battery technology, specifically to a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries. Background Technology

[0002] Sulfide electrolytes possess extremely high ionic conductivity, but they also have several fatal weaknesses: extreme sensitivity to air / humidity (easily reacting with water to generate highly toxic hydrogen chloride gas, leading to structural failure); unstable interface with electrodes (especially high-voltage positive electrodes) (side reactions can occur, forming a high-resistivity interface layer); mechanically rigid yet brittle (volume changes in electrode materials during battery charge-discharge cycles can cause electrolyte breakage and contact failure); and poor processability (traditional PVDF / NMP slurry processes are unusable because polar solvents such as NMP can damage the sulfide electrolyte). Therefore, an ideal binder must not only have high adhesion but also be able to conduct ions, resist interfacial reactions, be flexible and adaptable, and be solvent resistant.

[0003] In the prior art, CN120158242A discloses a fluorinated binder for sulfide all-solid-state batteries, its preparation method, and its application. The binder is copolymerized from isoprene and lithium perfluorovinyl ether sulfonate. The isoprene enhances the solubility of the lithium perfluorovinyl ether sulfonate fragments in non-polar solvents, thereby enabling the overall polymer to dissolve in non-polar solvents. The lithium perfluorovinyl ether sulfonate has a large steric octane ratio of fluorocarbon groups, which can shield the hydrocarbon groups on the isoprene, thus improving the overall polymer stability. The above binder is used for wet coating to prepare the cathode, exhibiting certain compatibility, stability, and ion-conducting ability. However, it lacks a strong adhesive structure and cannot accommodate large volume expansion.

[0004] CN120041113A discloses a polymer binder for sulfide solid-state batteries, its preparation method, and its application. The binder is composed of vinyltriethoxysilane, It is copolymerized with styrene. By introducing silane groups, the interfacial adhesion with the sulfide electrolyte is enhanced through their coupling effect. At the same time, the water in the system is consumed through condensation reaction, reducing the water content of the electrolyte membrane. This binder provides dissociated lithium ions, improving the ionic conductivity of the binder and reducing its negative impact on the conductivity of the sulfide electrolyte. The styrene groups improve the binder's solubility in non-polar solvents. This binder is soluble in solvents such as toluene and xylene, and can be mixed with the sulfide electrolyte to form a film via a wet coating process. While this binder possesses certain adhesion and ionic conductivity, its flexibility is generally limited, which is detrimental to electrolyte membrane processing.

[0005] CN120025762A discloses a method for preparing a single-ion conductor composite binder and its application, particularly relating to a composite binder soluble in non-polar solvents for use in wet film formation of sulfide solid electrolytes and in sulfide all-solid-state batteries. This binder combines non-polar solvent compatibility, solubility, bonding performance, and ionic conductivity, and also effectively reduces interfacial impedance through its single-ion conductivity.

[0006] In the aforementioned patent, the binder can be used in the preparation of positive electrode or electrolyte membrane, but it cannot be used in silicon-carbon negative electrode with a very high full-charge expansion rate.

[0007] Based on this, the present invention provides a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries. Summary of the Invention

[0008] The purpose of this invention is to provide a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries. The binder prepared by this invention not only has excellent mechanical adaptability and self-healing properties, but also excellent interface stability and auxiliary ion conduction properties, effectively improving the long-cycle stability and rate performance of all-solid-state batteries.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries, comprising a triblock copolymer and a dynamic crosslinking agent;

[0010] The triblock copolymer includes polybutadiene segments obtained by butadiene polymerization, poly(4-vinylpyridine) segments obtained by 4-vinylpyridine polymerization, and poly(itaconic acid-co-hydroxyethyl methacrylate) segments;

[0011] The dynamic crosslinking agent is one or both of 1,4-phenylenediboronic acid and pinacol terephthalate.

[0012] Preferably, the dynamic adaptive lithium-conducting network binder is prepared by the following method:

[0013] Step 1: Using anhydrous dichloromethane as a solvent, trimethylchlorosilane and anhydrous triethylamine are added in an ice-water bath at 0°C under a nitrogen atmosphere. Hydroxyethyl methacrylate is then added dropwise at a uniform rate of 300–600 mg / L over 0.5 hours. The mixture was stirred at 100-200 rpm for 10-30 minutes. After the addition was complete, the ice-water bath was removed, and the stirring speed was maintained. The mixture was reacted at room temperature for 12-24 hours to obtain a reaction solution. The reaction solution was washed twice with sodium bicarbonate solution and then twice with water. After standing for 5-8 minutes, the upper aqueous phase was discharged through a separatory funnel, leaving the lower liquid as the organic phase. The organic phase and anhydrous magnesium sulfate were added to the stirred tank at a mass ratio of 1:0.038-0.075 and stirred at 100-200 rpm for 10-30 minutes. After stirring, the mixture was filtered through a Buchner funnel and a vacuum filtration flask to collect the liquid and obtain a dried product. The dried product was placed in a rotary evaporator and the temperature was set to 30-40℃ for 10-30 minutes to obtain poly(hydroxyethyl methacrylate)-trimethylsilane.

[0014] Step 2: Under a nitrogen atmosphere, anhydrous cyclohexane and sec-butyllithium are added to the reactor. Then, under nitrogen protection, the frozen butadiene ampoule is opened, and butadiene is drawn into the reactor using a dry syringe. The reaction is carried out at 50°C for 2–3 hours to form polybutadiene segments. After the reaction is completed, the temperature is lowered to 0°C, and 4-vinylpyridine is added. The reaction is carried out for 4–6 hours to form poly(4-vinylpyridine) segments. Subsequently, dimethyl itaconic acid and poly(hydroxyethyl methacrylate)-trimethylsilane are added using an acetone or dry ice bath at -70 to -80°C. The reaction is carried out for 5–7 hours to form the precursor. The chain segment was added to anhydrous methanol to obtain a first mixture. The first mixture was added to a glass jar containing a first methanol solution and stirred with a magnetic stirrer at 1000-1200 r / min for 5-10 min. After settling for 30-60 min, it was filtered with 100-200 mesh filter paper to obtain a solid product. The solid product was then dissolved by dissolving in tetrahydrofuran and added to a methanol solution. After settling and filtration, the process was repeated 2-4 times. The product was then placed in a vacuum drying oven and dried at 40℃ for 48-72 h to obtain the first block copolymer.

[0015] Step 3: Add tetrahydrofuran solvent to a three-necked flask. Under nitrogen protection, add the first block copolymer to the three-necked flask, stir to dissolve, and heat to 55-65℃ using an oil bath. Then add excess 9.5mol / L lithium hydroxide aqueous solution and stir the reaction with a magnetic stirrer at 100-120r / min for 48-72min to form poly(itaconic acid-co-hydroxyethyl methacrylate) segments. After the reaction is complete, transfer the reaction solution to a dialysis bag (molecular cutoff 3.5-5kDa) and dialyze in water for three days, changing the water three times a day. After dialysis, remove the solution from the dialysis bag and transfer it to a suitable lyophilization bottle. Place the lyophilization bottle in a low-temperature freezer to freeze it into a solid state, and then place it in a freeze dryer for freeze drying to obtain the triblock copolymer.

[0016] Step 4: Add the triblock copolymer and tetrahydrofuran solution to the reactor at a mass ratio of 1:5 to 10 and stir to dissolve. Under normal temperature conditions, add the dynamic crosslinking agent to the reactor and stir at 100 to 120 r / min for 10 to 20 h. After rotary evaporation, collect the solid to complete the preparation of the dynamic adaptive lithium-conducting network binder.

[0017] Preferably, in step one, the molar ratio of anhydrous dichloromethane, trimethylchlorosilane, anhydrous triethylamine, and hydroxyethyl methacrylate is 1.565:0.11:0.11:0.1.

[0018] Preferably, in step two, the molar ratio of butadiene, 4-vinylpyridine, dimethyl itaconic acid, poly(hydroxyethyl methacrylate)-trimethylsilane, anhydrous cyclohexane, and sec-butyllithium is 0.1–0.2:0.1–0.2:0.05–0.1:0.05–0.1:278:0.01. The methanol solution is prepared by mixing methanol and water at a ratio of 9:1. The mass ratio of methanol solution, anhydrous methanol, the first mixture, and the solid product is 411:1:279:1. The mass ratio of the solid product to the first tetrahydrofuran solution is 1:13.

[0019] Preferably, in step three, the mass ratio of the second tetrahydrofuran solvent to the first block copolymer is 13:1-3.

[0020] Preferably, in step four, the molar ratio of the dynamic crosslinking agent to the triblock copolymer is 0.05-0.1:0.3-0.4.

[0021] An application of a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries includes the following steps: In an anhydrous environment, the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder are heated to 100–250°C and stirred at 200–300 r / min for 5–10 min using a magnetic stirrer to obtain a coating. This coating is then applied to the negative electrode foil using a coating machine, and the mixture is cooled to room temperature to obtain the negative electrode sheet, thus completing the application of the dynamic adaptive lithium-conducting network binder.

[0022] Preferably, the negative electrode active material is any one or a combination of at least two of the composite materials of nano-silicon, silicon suboxide, silicon carbide, or graphite, and the graphite material is any one or a combination of at least two of the materials of artificial graphite, hard carbon, and mesophase carbon microspheres.

[0023] Preferably, the conductive agent is at least one of conductive carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, and graphene, and the sulfide solid electrolyte is a lithium phosphorus sulfur chloride electrolyte.

[0024] Preferably, the mass ratio of the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder is 55:5-8:30-35:10-15.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. In the preparation process of this invention, the pyridine nitrogen atoms of poly(4-vinylpyridine) can form strong coordination bonds with lithium atoms on the surface of sulfide, achieving strong adhesion and providing support for the overall structure. At the same time, the weak basicity of the pyridine group can preferentially capture acidic substances or trace amounts of water vapor released from the positive electrode, slightly sacrificing the protection of the sulfide electrolyte and delaying its decomposition.

[0027] 2. In this invention, in the lithium itaconic acid-co-hydroxyethyl methacrylate segment, the lithium itaconic acid unit provides a large number of lithium carboxylic acid functional groups. These functional groups are themselves lithium ion migration sites, which can form continuous, low-barrier lithium ion transport paths, assist lithium ion conduction, reduce interfacial impedance, and the hydroxyl groups of hydroxyethyl methacrylate provide dynamic crosslinking network sites.

[0028] 3. In this invention, the flexible polybutadiene segments provide elasticity, and the dynamic borate bond network endows the material with rheological properties under pressure and stress, which can effectively buffer stress and restore the network structure after cycling, greatly improving the cycle life of the all-solid-state battery.

[0029] 4. The polymer is designed to be thermoplastic, and the electrode powder, electrolyte powder and binder powder can be pressed into shape under heating using a hot pressing process. Heating softens and flows the polymer, fully encapsulating the particles. After cooling, a strong and elastic composite electrode is formed, avoiding the damage of the sulfide electrolyte by the solvent. This is the key to realizing the mass production of sulfide all-solid-state batteries. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0032] Example 1: A dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries, comprising a triblock copolymer and a dynamic crosslinking agent;

[0033] Triblock copolymers include polybutadiene segments obtained by butadiene polymerization, poly(4-vinylpyridine) segments obtained by 4-vinylpyridine polymerization, and poly(itaconic acid-co-hydroxyethyl methacrylate) segments;

[0034] The dynamic crosslinking agent is pinacol terephthalate.

[0035] The dynamic adaptive lithium-conducting network binder is prepared by the following method:

[0036] Step 1: Using anhydrous dichloromethane as solvent, trimethylchlorosilane and anhydrous triethylamine were added in an ice-water bath at 0℃ under a nitrogen atmosphere. Hydroxyethyl methacrylate was added dropwise at a uniform rate over 0.5 h, with stirring at 300 r / min during the addition process. After the addition was completed, the ice-water bath was removed, and the stirring speed was maintained. The reaction was carried out at room temperature for 12 h to obtain a reaction solution. The reaction solution was washed twice with sodium bicarbonate solution and then twice with water. After standing for 5 min, the upper aqueous phase was discharged through a separatory funnel, leaving the lower liquid as the organic phase. At the same time, the organic phase and anhydrous magnesium sulfate were added to a stirred tank at a mass ratio of 1:0.038 and stirred at 100 r / min for 10 min. After stirring, the mixture was filtered through a Buchner funnel and a vacuum filtration flask to collect the liquid and obtain a dried product. The dried product was placed in a rotary evaporator and the temperature was set at 30℃ for 10 min to obtain poly(hydroxyethyl methacrylate)-trimethylsilane.

[0037] Step 2: Under a nitrogen atmosphere, anhydrous cyclohexane and sec-butyllithium were added to the reactor. Then, under nitrogen protection, a frozen butadiene ampoule was opened, and butadiene was drawn into the reactor using a dry syringe. The reaction was carried out at 50°C for 2 hours to form polybutadiene segments. After the reaction was completed, the temperature was lowered to 0°C, and 4-vinylpyridine was added. The reaction was carried out for 4 hours to form poly(4-vinylpyridine) segments. Subsequently, dimethyl itaconic acid and poly(hydroxyethyl methacrylate)-trimethylsilane were added in a -70°C dry ice bath and reacted for 5 hours to form poly(4-vinylpyridine) segments. The precursor segment was formed, and anhydrous methanol was added to obtain the first mixture. The first mixture was added to a glass jar containing the first methanol solution, and stirred at 1000 r / min for 5 min with a magnetic stirrer. After settling for 30 min, it was filtered with 100 mesh filter paper to obtain a solid product. The solid product was then dissolved by dissolving in tetrahydrofuran, added to the methanol solution, and filtered after settling. This process was repeated twice. The product was then placed in a vacuum drying oven and dried at 40℃ for 48 h to obtain the first block copolymer.

[0038] Step 3: Add tetrahydrofuran solvent to a three-necked flask. Under nitrogen protection, add the first block copolymer to the three-necked flask, stir to dissolve, and heat to 55°C using an oil bath. Then add excess 9.5 mol / L lithium hydroxide aqueous solution and stir the reaction at 100 r / min for 48 min using a magnetic stirrer to form poly(itaconic acid-co-hydroxyethyl methacrylate) segments. After the reaction is complete, transfer the reaction solution to a dialysis bag (molecular cutoff 3.5 kDa) and dialyze in water for three days, changing the water three times a day. After dialysis, remove the solution from the dialysis bag and transfer it to a suitable lyophilization bottle. Place the lyophilization bottle in a low-temperature freezer to freeze it into a solid state, and then place it in a freeze dryer for freeze drying to obtain the triblock copolymer.

[0039] Step 4: Add the triblock copolymer and tetrahydrofuran solution to the reactor at a mass ratio of 1:5 and stir to dissolve. Then, add the dynamic crosslinking agent to the reactor at room temperature and stir at 100 r / min for 10 h. After rotary evaporation, collect the solid to complete the preparation of the dynamic adaptive lithium-conducting network binder.

[0040] In step one, the molar ratio of anhydrous dichloromethane, trimethylchlorosilane, anhydrous triethylamine, and hydroxyethyl methacrylate is 1.565:0.11:0.11:0.1.

[0041] In step two, the molar ratio of butadiene, 4-vinylpyridine, dimethyl itaconic acid, poly(hydroxyethyl methacrylate)-trimethylsilane, anhydrous cyclohexane, and sec-butyllithium is 0.1:0.1:0.05:0.05:278:0.01. The methanol solution is prepared by mixing methanol and water at a ratio of 9:1. The mass ratio of methanol solution, anhydrous methanol, the first mixture, and the solid product is 411:1:279:1. The mass ratio of the solid product to the first tetrahydrofuran solution is 1:13.

[0042] In step three, the mass ratio of the second tetrahydrofuran solvent to the first block copolymer is 13:1.

[0043] In step four, the molar ratio of the dynamic crosslinking agent to the triblock copolymer is 0.05:0.3.

[0044] An application of a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries includes the following steps: in an anhydrous environment, the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder are heated to 100°C, stirred at 200 r / min for 5 min using a magnetic stirrer to obtain a coating, and then coated onto the negative electrode foil using a coating machine. After cooling to room temperature, the resulting negative electrode sheet completes the application of the dynamic adaptive lithium-conducting network binder.

[0045] The negative electrode active material is nano-silicon, the conductive agent is conductive carbon black, and the sulfide solid electrolyte is lithium phosphorus sulfur chloride electrolyte.

[0046] The mass ratio of negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder is 55:5:30:10.

[0047] Example 2: A dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries, comprising a triblock copolymer and a dynamic crosslinking agent;

[0048] Triblock copolymers include polybutadiene segments obtained by butadiene polymerization, poly(4-vinylpyridine) segments obtained by 4-vinylpyridine polymerization, and poly(itaconic acid-co-hydroxyethyl methacrylate) segments;

[0049] The dynamic crosslinking agent is 1,4-phenylenediboric acid.

[0050] The dynamic adaptive lithium-conducting network binder is prepared by the following method:

[0051] Step 1: Using anhydrous dichloromethane as solvent, trimethylchlorosilane and anhydrous triethylamine were added in an ice-water bath at 0℃ under a nitrogen atmosphere. Hydroxyethyl methacrylate was added dropwise over 0.5 h at a uniform rate, with stirring at 450 r / min during the addition process. After the addition was completed, the ice-water bath was removed, and the stirring speed was maintained. The reaction was carried out at room temperature for 18 h to obtain a reaction solution. The reaction solution was washed twice with sodium bicarbonate solution and then twice with water. After standing for 6 min, the upper aqueous phase was discharged through a separatory funnel, leaving the lower liquid as the organic phase. At the same time, the organic phase and anhydrous magnesium sulfate were added to a stirred tank at a mass ratio of 1:0.06 and stirred at 150 r / min for 20 min. After stirring, the mixture was filtered through a Buchner funnel and a vacuum filtration flask to collect the liquid and obtain a dried product. The dried product was placed in a rotary evaporator and the temperature was set at 35℃ for 20 min to obtain poly(hydroxyethyl methacrylate)-trimethylsilane.

[0052] Step 2: Under a nitrogen atmosphere, anhydrous cyclohexane and sec-butyllithium were added to the reactor. Then, under nitrogen protection, a frozen butadiene ampoule was opened, and butadiene was drawn into the reactor using a dry syringe. The reaction was carried out at 50°C for 2.5 hours to form polybutadiene segments. After the reaction was completed, the temperature was lowered to 0°C, and 4-vinylpyridine was added. The reaction was carried out for 5 hours to form poly(4-vinylpyridine) segments. Subsequently, dimethyl itaconic acid and poly(hydroxyethyl methacrylate)-trimethylsilane were added in a -75°C dry ice bath and the reaction was carried out for 6 hours. A precursor segment was formed, and anhydrous methanol was added to obtain a first mixture. The first mixture was added to a glass jar containing a first methanol solution, and stirred at 1100 r / min for 7 min with a magnetic stirrer. After settling for 45 min, the mixture was filtered through 150 mesh filter paper to obtain a solid product. The solid product was then dissolved by dissolving in tetrahydrofuran, added to a methanol solution, and filtered after settling. This process was repeated 3 times. The product was then placed in a vacuum drying oven and dried under vacuum at 40°C for 60 h to obtain the first block copolymer.

[0053] Step 3: Add tetrahydrofuran solvent to a three-necked flask. Under nitrogen protection, add the first block copolymer to the three-necked flask, stir to dissolve, and heat to 60°C using an oil bath. Then add excess 9.5 mol / L lithium hydroxide aqueous solution and stir the reaction at 110 r / min for 60 min using a magnetic stirrer to form poly(itaconic acid-co-hydroxyethyl methacrylate) segments. After the reaction is complete, transfer the reaction solution to a dialysis bag (molecular cutoff 4.2 kDa) and dialyze in water for three days, changing the water three times a day. After dialysis, remove the solution from the dialysis bag and transfer it to a suitable lyophilization bottle. Place the lyophilization bottle in a low-temperature freezer to freeze it into a solid state, and then place it in a freeze dryer for freeze drying to obtain the triblock copolymer.

[0054] Step 4: Add the triblock copolymer and tetrahydrofuran solution to the reactor at a mass ratio of 1:7 and stir to dissolve. Then, add the dynamic crosslinking agent to the reactor at room temperature and stir at 110 r / min for 15 h. After rotary evaporation, collect the solid to complete the preparation of the dynamic adaptive lithium-conducting network binder.

[0055] In step one, the molar ratio of anhydrous dichloromethane, trimethylchlorosilane, anhydrous triethylamine, and hydroxyethyl methacrylate is 1.565:0.11:0.11:0.1.

[0056] In step two, the molar ratio of butadiene, 4-vinylpyridine, dimethyl itaconic acid, poly(hydroxyethyl methacrylate)-trimethylsilane, anhydrous cyclohexane, and sec-butyllithium is 0.15:0.1:0.05:0.05:278:0.01. The methanol solution is prepared by mixing methanol and water at a ratio of 9:1. The mass ratio of methanol solution, anhydrous methanol, the first mixture, and the solid product is 411:1:279:1. The mass ratio of the solid product to the first tetrahydrofuran solution is 1:13.

[0057] In step three, the mass ratio of the second tetrahydrofuran solvent to the first block copolymer is 13:1.

[0058] In step four, the molar ratio of the dynamic crosslinking agent to the triblock copolymer is 0.05:0.3.

[0059] In step four, the molar ratio of the dynamic crosslinking agent to the triblock copolymer is 0.05 to 0.5.

[0060] An application of a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries includes the following steps: in an anhydrous environment, the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder are heated to 180°C and stirred at 250 r / min for 7 min using a magnetic stirrer to obtain a coating. The coating is then applied to the negative electrode foil using a coating machine and cooled to room temperature to obtain the negative electrode sheet, thus completing the application of the dynamic adaptive lithium-conducting network binder.

[0061] The negative electrode active material is silicon suboxide, the conductive agent is acetylene black, and the sulfide solid electrolyte is lithium phosphorus sulfur chloride electrolyte;

[0062] The mass ratio of the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder is 55:6:32:12.

[0063] Example 3: A dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries, comprising a triblock copolymer and a dynamic crosslinking agent;

[0064] Triblock copolymers include polybutadiene segments obtained by butadiene polymerization, poly(4-vinylpyridine) segments obtained by 4-vinylpyridine polymerization, and poly(itaconic acid-co-hydroxyethyl methacrylate) segments;

[0065] The dynamic crosslinking agent is 1,4-phenylenediboric acid.

[0066] The dynamic adaptive lithium-conducting network binder is prepared by the following method:

[0067] Step 1: Using anhydrous dichloromethane as solvent, trimethylchlorosilane and anhydrous triethylamine were added in an ice-water bath at 0℃ under a nitrogen atmosphere. Hydroxyethyl methacrylate was added dropwise at a uniform rate over 0.5 h, with stirring at 600 r / min during the addition process. After the addition was completed, the ice-water bath was removed, and the stirring speed was maintained. The reaction was carried out at room temperature for 24 h to obtain a reaction solution. The reaction solution was washed twice with sodium bicarbonate solution and then twice with water. After standing for 8 min, the upper aqueous phase was discharged through a separatory funnel, leaving the lower liquid as the organic phase. At the same time, the organic phase and anhydrous magnesium sulfate were added to a stirred tank at a mass ratio of 1:0.075 and stirred at 200 r / min for 30 min. After stirring, the mixture was filtered through a Buchner funnel and a vacuum filtration flask to collect the liquid and obtain a dried product. The dried product was placed in a rotary evaporator and the temperature was set at 40℃ for 30 min to obtain poly(hydroxyethyl methacrylate)-trimethylsilane.

[0068] Step 2: Under a nitrogen atmosphere, anhydrous cyclohexane and sec-butyllithium were added to the reactor. Then, under nitrogen protection, a frozen butadiene ampoule was opened, and butadiene was drawn into the reactor using a dry syringe. The reaction was carried out at 50°C for 3 hours to form polybutadiene segments. After the reaction was completed, the temperature was lowered to 0°C, and 4-vinylpyridine was added. The reaction was carried out for 6 hours to form poly(4-vinylpyridine) segments. Subsequently, dimethyl itaconic acid and poly(hydroxyethyl methacrylate)-trimethylsilane were added in an acetone bath at -80°C and the reaction was carried out for 7 hours to form poly(4-vinylpyridine) segments. The precursor segment was formed, and anhydrous methanol was added to obtain the first mixture. The first mixture was added to a glass jar containing the first methanol solution, and stirred at 1200 r / min for 10 min with a magnetic stirrer. After settling for 60 min, it was filtered with 200 mesh filter paper to obtain a solid product. The solid product was then dissolved by dissolving in tetrahydrofuran, added to the methanol solution, and filtered after settling. This process was repeated 4 times. The product was then placed in a vacuum drying oven and dried under vacuum at 40°C for 72 h to obtain the first block copolymer.

[0069] Step 3: Add tetrahydrofuran solvent to a three-necked flask. Under nitrogen protection, add the first block copolymer to the three-necked flask, stir to dissolve, and heat to 65°C using an oil bath. Then add excess 9.5 mol / L lithium hydroxide aqueous solution and stir the reaction at 120 r / min for 48-72 min using a magnetic stirrer to form poly(itaconic acid-co-hydroxyethyl methacrylate) segments. After the reaction is complete, transfer the reaction solution to a dialysis bag (molecular cutoff 5 kDa) and dialyze in water for three days, changing the water three times a day. After dialysis, remove the solution from the dialysis bag and transfer it to a suitable lyophilization bottle. Place the lyophilization bottle in a low-temperature freezer to freeze it into a solid state, and then place it in a freeze dryer for freeze drying to obtain the triblock copolymer.

[0070] Step 4: Add the triblock copolymer and tetrahydrofuran solution to the reactor at a mass ratio of 1:10 and stir to dissolve. Then, add the dynamic crosslinking agent to the reactor at room temperature and stir at 120 r / min for 20 h. After rotary evaporation, collect the solid to complete the preparation of the dynamic adaptive lithium-conducting network binder.

[0071] In step one, the molar ratio of anhydrous dichloromethane, trimethylchlorosilane, anhydrous triethylamine, and hydroxyethyl methacrylate is 1.565:0.11:0.11:0.1.

[0072] In step two, the molar ratio of butadiene, 4-vinylpyridine, dimethyl itaconic acid, poly(hydroxyethyl methacrylate)-trimethylsilane, anhydrous cyclohexane, and sec-butyllithium is 0.1:0.15:0.05:0.05:278:0.01. The methanol solution is prepared by mixing methanol and water at a ratio of 9:1. The mass ratio of methanol solution, anhydrous methanol, the first mixture, and the solid product is 411:1:279:1. The mass ratio of the solid product to the first tetrahydrofuran solution is 1:13.

[0073] In step three, the mass ratio of the second tetrahydrofuran solvent to the first block copolymer is 13:1.

[0074] In step four, the molar ratio of the dynamic crosslinking agent to the triblock copolymer is 0.05:0.3.

[0075] An application of a dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries includes the following steps: in an anhydrous environment, the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder are heated to 250°C and stirred at 300 r / min for 10 min using a magnetic stirrer to obtain a coating. The coating is then applied to the negative electrode foil using a coating machine and cooled to room temperature to obtain the negative electrode sheet, thus completing the application of the dynamic adaptive lithium-conducting network binder.

[0076] The negative electrode active material is silicon carbide, the conductive agent is carbon nanotubes, and the sulfide solid electrolyte is lithium phosphorus sulfur chloride electrolyte.

[0077] The mass ratio of the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder is 55:8:35:15.

[0078] Comparative Example 1: The difference between this comparative example and Example 1 is that in step two of this comparative example, the molar ratio of butadiene, 4-vinylpyridine, dimethyl itaconic acid, poly(hydroxyethyl methacrylate)-trimethylsilane, anhydrous cyclohexane, and sec-butyllithium is 0.1:0.15:0.08:0.05:278:0.01.

[0079] Comparative Example 2 differs from Example 1 in that: in step two of this comparative example, the molar ratio of butadiene, 4-vinylpyridine, dimethyl itaconic acid, poly(hydroxyethyl methacrylate)-trimethylsilane, anhydrous cyclohexane, and sec-butyllithium is 0.1:0.15:0.08:0.05:278:0.01; and in step four, the molar ratio of dynamic crosslinking agent to triblock copolymer is 0.33:0.08.

[0080] Comparative Example 3 differs from Example 1 in that a conventional PVDF binder is used when preparing the negative electrode sheet.

[0081] Performance Testing: The negative electrode sheets obtained after processing Examples 1-3 and Comparative Examples 1-4 were assembled into pouch cells with commercial sulfide solid electrolyte positive electrode sheets and sulfide solid electrolyte membranes. Constant current charge-discharge cycle experiments were conducted using a charge-discharge current of 0.1C. The test data are recorded in Table 1.

[0082] Table 1:

[0083] project First discharge capacity FDC / Ah First charge / discharge efficiency ICE / % Capacity retention rate after 20 cycles / % Capacity retention rate after 100 cycles / % Example 1 1.71 78% 95 89 Example 2 1.74 78% 95 89 Example 3 1.68 76% 96 90 Comparative Example 1 1.79 79% 95 89 Comparative Example 2 1.67 75% 97 91 Comparative Example 3 1.70 79% 95 90

[0084] The negative electrode sheets prepared after treatment in Examples 1-3 and Comparative Examples 1-4 were tested for adhesion, cohesion, and flexibility. The test data are recorded in Table 2.

[0085] Table 2:

[0086] project Adhesion strength (N / cm) Elastic recovery rate % Flexibility test (minimum bending radius, mm) Example 1 12.8 92 2.5 Example 2 12.5 95 2.0 Example 3 13.5 88 3.1 Comparative Example 1 12.9 90 2.8 Comparative Example 2 12.6 98 1.5 Comparative Example 3 6.5 55 Greater than 10 Test Standards ASTM D3330 (Tape Peeling Method) Indentation recovery method IPC TM-650 2.4.3 (Bending Test)

[0087] As shown in Tables 1 and 2, it can be seen that, compared with Example 1, increasing the butadiene monomer content from 33% to 43% had no significant impact on performance in Example 2. This indicates that 33% butadiene already provides sufficient elasticity to absorb the stress and strain of the electrode during cycling, preventing electrolyte particle breakage and contact failure. In Example 3, compared with Example 1, the vinylpyridine monomer content was increased from 33% to 43%. Because the vinylpyridine monomer provides overall structural support and adhesion, and the weak basicity of the pyridine group captures trace amounts of water vapor, it slightly sacrifices the protection of the sulfide electrolyte, delaying its decomposition. Therefore, Example 3 has a higher cycle capacity retention rate. However, its pyridine ring may have a certain degree of reduction side reaction, resulting in a slightly lower initial efficiency. After the SEI film is formed, contact with highly reducing substances can be avoided. Compared to Example 1, Comparative Example 1 showed that the final proportion of lithium itaconic acid units increased from 17% to 24%. Lithium itaconic acid effectively reduced interfacial impedance, which is beneficial to capacity utilization. Compared to Example 11, Comparative Example 2 showed that the final proportion of hydroxyethyl methacrylate units increased from 17% to 24%. The increased dynamic cross-linked carbonate bonds allowed the material to more effectively buffer stress and restore the network structure after cycling, improving the cycle life of the all-solid-state battery. However, the hydroxyl groups may consume more lithium, leading to a decrease in first-efficiency and FDC. Compared to Comparative Example 3, Examples 1, 2, and 3, Comparative Example 1 and Comparative Example 2 all showed better performance and significantly longer cycle life than Comparative Example 3. This indicates that the dynamic adaptive lithium-conducting network binder has better interfacial stability, assists in ion conduction to reduce impedance, has unique mechanical adaptability and self-healing ability, and good processability to avoid side reactions caused by solvents. Therefore, it significantly improves the electrochemical performance of sulfide all-solid-state batteries and extends cycle life.

[0088] By comparing and analyzing the relevant data in the table, it can be seen that the binder prepared in this invention not only possesses excellent mechanical self-adaptability and self-healing properties, but also excellent interfacial stability and auxiliary ion conduction performance, effectively improving the long-cycle stability and rate performance of all-solid-state batteries. This indicates that the dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries provided by this invention has a broader market prospect and is more suitable for widespread application.

[0089] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries, characterized in that: Including triblock copolymers and dynamic crosslinking agents; The triblock copolymer includes polybutadiene segments obtained by butadiene polymerization, poly(4-vinylpyridine) segments obtained by 4-vinylpyridine polymerization, and poly(itaconic acid-co-hydroxyethyl methacrylate) segments; The dynamic crosslinking agent is one or both of 1,4-phenylenediboronic acid and pinacol terephthalate.

2. The dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 1, characterized in that, The dynamic adaptive lithium-conducting network binder is prepared by the following method: Step 1: Using anhydrous dichloromethane as a solvent, trimethylchlorosilane and anhydrous triethylamine were added at 0°C under a nitrogen atmosphere. The mixture was stirred and hydroxyethyl methacrylate was added dropwise at a uniform rate. After the addition was completed, the mixture was stirred and reacted at room temperature to obtain a reaction solution. The reaction solution was washed with sodium bicarbonate solution and water to obtain an organic phase. The organic phase and anhydrous magnesium sulfate were stirred at a mass ratio of 1:0.038 to 0.

075. The mixture was then filtered to obtain a dry product. The dry product was evaporated to obtain poly(hydroxyethyl methacrylate)-trimethylsilane. Step 2: Under a nitrogen atmosphere, butadiene is added to anhydrous cyclohexane and sec-butyllithium to react and form polybutadiene segments. Then, 4-vinylpyridine is added to react and form poly(4-vinylpyridine) segments. Subsequently, dimethyl itaconic acid and poly(hydroxyethyl methacrylate-trimethylsilane) are added in an acetone or dry ice bath at -70 to -80°C to form precursor segments. Anhydrous methanol is added to obtain the first mixture. The first mixture is added to a methanol solution, and after stirring, sedimentation and filtration, a solid product is obtained. The solid product is then dissolved in tetrahydrofuran, added to a methanol solution, and subjected to sedimentation and filtration. This process is repeated 2-4 times, and then dried to obtain the first block copolymer. Step 3: Add the first block copolymer to the second tetrahydrofuran solvent and dissolve it. Add excess 9.5 mol / L lithium hydroxide aqueous solution and stir to form poly(itaconic acid-co-hydroxyethyl methacrylate) segments. After the reaction is complete, dialyze the reaction solution. After dialyzing, freeze-dry the dialyzed solution to obtain the triblock copolymer. Step 4: Dissolve the triblock copolymer and tetrahydrofuran solution in a mass ratio of 1:5 to 10 by stirring. Add a dynamic crosslinking agent and stir to react at room temperature. Then, collect the solid by rotary evaporation to obtain the dynamic adaptive lithium-conducting network binder.

3. The dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 2, characterized in that, In step one, the molar ratio of anhydrous dichloromethane, trimethylchlorosilane, anhydrous triethylamine, and hydroxyethyl methacrylate is 1.565:0.11:0.11:0.

1.

4. The dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 2, characterized in that, In step two, the molar ratio of butadiene, 4-vinylpyridine, dimethyl itaconic acid, poly(hydroxyethyl methacrylate)-trimethylsilane, anhydrous cyclohexane, and sec-butyllithium is 0.1–0.2:0.1–0.2:0.05–0.1:0.05–0.1:278:0.

01. The methanol solution is prepared by mixing methanol and water at a ratio of 9:

1. The mass ratio of methanol solution, anhydrous methanol, the first mixture, and the solid product is 411:1:279:1, and the mass ratio of the solid product to the first tetrahydrofuran solution is 1:

13.

5. The dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 2, characterized in that, In step three, the mass ratio of the second tetrahydrofuran solvent to the first block copolymer is 13:1-3.

6. The dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 2, characterized in that, In step four, the molar ratio of the dynamic crosslinking agent to the triblock copolymer is 0.05-0.1:0.3-0.

4.

7. The application of the dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to any one of claims 1 to 6, characterized in that, The process includes the following steps: in an anhydrous environment, the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder are heated to 100-250°C and stirred at 200-300 r / min for 5-10 min using a magnetic stirrer to obtain a coating. The coating is then applied to the negative electrode foil using a coating machine and cooled to room temperature to obtain the negative electrode sheet, thus completing the application of the dynamic adaptive lithium-conducting network binder.

8. The application of the dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 7, characterized in that, The negative electrode active material is any one or a combination of at least two of the following: nano-silicon, silicon suboxide, silicon carbide, or graphite composite materials.

9. The application of the dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 7, characterized in that, The graphite material is any one or a combination of at least two of artificial graphite, hard carbon, and mesophase carbon microspheres; the conductive agent is at least one of conductive carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, and graphene; and the sulfide solid electrolyte is a lithium phosphorus sulfur chloride electrolyte.

10. The application of the dynamic adaptive lithium-conducting network binder for sulfide all-solid-state batteries according to claim 7, characterized in that, The mass ratio of the negative electrode active material, conductive agent, sulfide solid electrolyte, and dynamic adaptive lithium-conducting network binder is 55:5-8:30-35:10-15.