Core-shell structure binder, preparation method and application of core-shell structure binder in silicon-based negative electrode solid-state battery

Abstract

The invention provides a core-shell structure binder, a preparation method and application of the core-shell structure binder in a silicon-based negative electrode solid-state battery. The binder comprises an inner core layer and a shell layer which is arranged on the outer surface of the inner core layer and at least partially covers the inner core layer, comonomers of the inner core layer comprise acrylic acid and divinyl benzene; the material of the shell layer is a polyethylene oxide-beta-cyclodextrin material grafted with thioglycidyl ether; the binder has a structure of'hard inside, soft outside, sparse inside and hydrophilic outside ', so that the binder simultaneously has structural rigidity and surface activity, has adhesion and flexibility, is provided with a stress buffer layer, and can disperse a stress transfer path in pole piece preparation or cyclic stress, thereby improving the fatigue resistance, the bonding life, the initial bonding strength and the cyclic stability of the pole piece.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary batteries, in particular to a core-shell structure binder, a preparation method and application thereof in silicon-based negative electrode solid-state batteries. BACKGROUND

[0002] With the rapid development of new energy vehicles and energy storage devices, the demand for energy density of lithium ion batteries is increasing. Silicon-based negative electrodes are considered to be the most potential next-generation high-energy negative electrode materials due to their theoretical specific capacity of up to 4200 mAh / g. However, the volume expansion rate of silicon during lithium intercalation / deintercalation is more than 300%, which is much higher than that of traditional graphite negative electrodes (<10%). Such a dramatic volume change will cause stress concentration in the electrode structure, leading to particle pulverization, destruction of the conductive network and shedding of active materials, and the overall shedding rate of the electrode can exceed 40%, which further causes the failure of the electrode / electrolyte interface and rapid capacity decay.

[0003] To alleviate this problem, existing technologies mostly use elastic binders such as CMC / SBR, PVDF, PAA, or composite polymer systems to absorb strain. However, the Young's modulus of traditional binders is generally low (<0.5 GPa), which is difficult to provide sufficient mechanical support, and at the same time lacks ion conductivity and chemical stability. Especially under high load (>5 mg / cm²) and long cycle conditions of silicon-based negative electrodes, its adhesion performance decreases significantly, and the interfacial failure easily occurs.

[0004] On the other hand, as a key material to replace liquid electrolyte, solid-state electrolyte has high safety and high electrochemical stability, but its Young's modulus is usually as high as 5-20 GPa, and the interface rigidity is much greater than that of the silicon negative electrode. The rigid interface formed between silicon and solid-state electrolyte during the volume change of charge and discharge will cause serious stress concentration and micro-crack propagation, leading to interface peeling, ion transport blockage and internal resistance increase. This interface mechanics mismatch becomes a key problem restricting the cycle life and fast charging performance of silicon-based solid-state batteries.

[0005] To solve the above problems, researchers have proposed various improvement schemes, such as constructing porous silicon structure, designing elastic gel electrolyte, or forming an artificial interface layer by surface coating, but these methods usually have problems such as complex preparation, high cost or poor compatibility, which are difficult to balance the mechanical support, ion conduction and interface stability in actual batteries. Therefore, it is urgent to develop an interface bonding material that can adapt to stress changes and simultaneously realize chemical coupling and continuous ion conduction. SUMMARY

[0006] Inventive purpose: The purpose of the present application is to provide a core-shell structure binder, a preparation method and its application in silicon-based negative solid-state battery, so as to effectively alleviate the stress concentration caused by the volume expansion of silicon negative electrode, significantly improve the interface stability and cycle performance of solid-state battery, and be suitable for high-strain silicon-carbon negative electrode system in electric vehicle fast charging scene.

[0007] Technical scheme of the present application: In the first aspect, the present application provides a core-shell structure binder, which comprises an inner core layer and an outer shell layer arranged on the outer surface of the inner core layer and at least partially covering the inner core layer. The comonomer of the inner core layer comprises acrylic acid and divinylbenzene. The material of the outer shell layer is polyethylene oxide-beta-cyclodextrin material grafted with thio glycidyl ether.

[0008] In some embodiments, the monomer molar ratio of acrylic acid and divinylbenzene is 3-4:1.

[0009] In some embodiments, the diameter of the inner core layer is 80-120 nm.

[0010] In the second aspect, the present application also provides a preparation method of the core-shell structure binder, which specifically comprises the following steps: S1: adding acrylic acid, divinylbenzene, RAFT reagent and initiator into a reactor, mixing uniformly; then adding a solvent and stirring uniformly; performing reaction under heating and stirring, cooling, centrifuging, and washing after the reaction is completed to obtain crosslinked core particles; S2: dissolving beta-CD in a solvent and stirring until clear; slowly adding polyethylene oxide and stirring at room temperature to obtain a complex solution; freeze-drying to obtain a complex powder for standby use; S3: dispersing the obtained crosslinked core particles in a solvent, adding a crosslinking agent, slowly adding the complex powder solution under heating, and ultrasonically stirring to form a core-shell product; S4: dispersing the core-shell product in a solution, adding carbodiimide under nitrogen protection, stirring at room temperature to activate; adding thio glycidyl ether, and performing reaction under heating and stirring; cooling, centrifuging to remove by-products, and washing and vacuum drying to obtain a dry powder state core-shell structure binder.

[0011] In some embodiments, the RAFT reagent is selected from one of dithiobenzoic acid esters, trithiocarbonate or xanthate, for example, one of trithiocarbonate or dithiobenzoic acid 4-cyanopentanoic acid; and the initiator is AIBN.

[0012] In some embodiments, the reaction temperature of the reaction under heating and stirring in S1 is 50-70℃, and the reaction time is 6-8 h.

[0013] In some embodiments, the molar ratio of the addition of acrylic acid, divinylbenzene, RAFT agent and initiator in S1 is 3-4:1:0.1:0.02-0.05.

[0014] In some embodiments, the Mw of the polyethylene oxide is 6k-12k; the mass ratio of the addition of the beta-CD and the polyethylene oxide is 1:1-2.

[0015] In some embodiments, the crosslinking agent in S3 is selected from one of divinylthiopropane, glutaraldehyde, diisocyanate; the mass ratio of the addition of the crosslinked core particle, the crosslinking agent, the composite powder is 1:0.01-0.02:0.2-0.3.

[0016] In some embodiments, the solid content of the core-shell product in S4 in the solvent is 5-10 wt%, the mass ratio of the addition of the core-shell product and the thio glycidyl ether is 1:0.4-1.

[0017] In a third aspect, the present application also provides the use of the core-shell structure binder on the negative electrode material of the solid-state battery.

[0018] Advantages: The core-shell structure binder provided by the present application has the configuration of "hard inside and soft outside, and hydrophobic outside", so that the binder has structural rigidity and surface activity at the same time, and has adhesion and flexibility. The binder has a stress buffer layer, which can disperse the stress transmission path in the preparation of the pole piece or the cyclic stress, thereby improving the fatigue resistance and bonding life of the pole piece.

[0019] DVB forms a three-dimensional crosslinked structure in the core layer, and contains a benzene ring structure, which significantly improves the overall Tg and thermal decomposition temperature of the binder, can meet the electrode drying and subsequent hot pressing process, makes the core layer not easy to flow or deform, and can significantly improve the structure retention and anti-dust performance of the pole piece. The pi-pi interaction of the benzene ring helps to improve the interfacial action between the binder and the conductive agent.

[0020] The core layer polymerization is controlled by RAFT reaction, and the thio carbonyl or carboxylic acid end group is reserved, which can be further reacted or coupled with the surface of the active particle, realizes chemical combination / in-situ grafting, greatly enhances the interfacial stability, and the shell layer is rich in polar groups, which significantly improves the initial bonding strength and cycle stability, and provides an interfacial platform for multifunctionalization. DETAILED DESCRIPTION

[0021] The present application will be described below in conjunction with specific embodiments. It should be noted that the following examples are examples of the present application, and are only used to illustrate the present application, and are not used to limit the present application. Other combinations and various modifications within the concept of the present application can be made without departing from the spirit or scope of the present application.

[0022] The chemical reagents used in the present application are all commercially available analytical grade unless otherwise specified. The polyethylene oxide is purchased from Shanghai Macklin Biochemical Technology Co., Ltd. with the item number P697836; the β-CD is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with the CAS number: 7585-39-9.

[0023] Example 1 S1: 3 mol of acrylic acid, 1 mol of divinylbenzene, 0.1 mol of trithiocarbonate and 0.05 mol of AIBN were added into 250 mL, and mixed uniformly; 150 mL of an ethanol / deionized water mixed solvent (volume ratio 1:1) was further added, and stirred uniformly; the reaction was carried out at 70°C for 8 h under the condition of 400 rpm stirring, and after the reaction was completed, the product was cooled, centrifuged and washed to obtain crosslinked core particles; S2: 10 g of β-CD was dissolved in 200 mL of deionized water, and stirred until clear; 15 g of polyethylene oxide was slowly added, and the reaction was carried out at 25°C for 12 h under the condition of stirring at room temperature to obtain a complex solution; the complex powder was obtained by freeze-drying, and was used as needed; S3: 5 g of the obtained crosslinked core particles were dispersed in deionized water (solid content 5 wt%), 0.1 g of diisocyanate was added, and 1 g of the complex powder was slowly added into the deionized water solution (solid content 5 wt%) under the condition of heating at 50°C, and ultrasonic stirring was carried out to form a core-shell product; S4: 5 g of the core-shell product prepared above was dispersed in DMF to form a solution with a solid content of 5 wt%, and was placed in a nitrogen atmosphere, 1 g of carbodiimide was added, and stirring was carried out at room temperature for 30 min to activate; 2 g of thio glycidyl ether was added, and the reaction was carried out at 60°C for 6 h under the condition of stirring; after the reaction was completed, the product was cooled, centrifuged to remove by-products, and washed, and then vacuum dried at 40°C to obtain a dry powder of the core-shell structure adhesive.

[0024] The FTIR data of the obtained adhesive are as follows: ~1735 cm -1 : strong peak-C=O, carbonyl vibration of carboxylic acid / ester / carboxylate; ~2870 cm -1 : C-H stretching, saturated alkyl; ~1450 cm -1 : C-H bending / CH2 bending.

[0025] ~1600 cm -1 : aromatic ring C=C skeleton vibration; ~900 cm -1 : out-of-plane C-H swing of aromatic ring.

[0026] ~1150 cm -1 : C-O-C stretching, representing ether bond, PEO and cyclodextrin both have this peak, the peak shape is strong and sharp; ~2930 cm -1: CH2stretch, PEO segment; ~3300 cm -1 (Broad): O-H stretch, hydroxyl of β-CD.

[0027] ~2550 cm -1 : S-H weak absorption.

[0028] Overall determination: C-O-C peak appears in the shell layer, and the C=O peak shape has a slight shift / broadening. This indicates that the product is successfully prepared.

[0029] Example 2 The preparation steps are basically the same as in Example 1, except that the addition of acrylic acid and divinylbenzene in S1 is 4 mol and 1 mol, respectively.

[0030] Example 3 The preparation steps are basically the same as in Example 1, except that the addition of β-CD and polyethylene oxide in S2 is 10 g and 20 g, respectively.

[0031] Comparative Example 1 S1: In 250 mL, add 3 mol of acrylic acid, 1 mol of divinylbenzene, 0.1 mol of thiocarbonate, and 0.05 mol of AIBN, mix well; then add 150 mL of ethanol / deionized water mixed solvent (volume ratio 1:1), stir well; 70°C, 400 rpm stirring for 8 h, after reaction, cool, centrifuge, wash, get crosslinked core particles; S2: In 200 mL of deionized water, slowly add 15 g of polyethylene oxide, stir at room temperature for 12 h to get a composite solution; freeze-dried to get a composite powder for use; S3: Disperse the obtained 5 g of crosslinked core particles in deionized water (solid content 5 wt%), add 0.1 g of diisocyanate, slowly add 1 g of composite powder containing deionized water solution (solid content 5 wt%) at 50°C, ultrasonic stirring, form core-shell product; S4: Disperse the 5 g of core-shell product prepared above in DMF to form a solution with a solid content of 5 wt%, place in nitrogen protection, add 1 g of carbodiimide, stir at room temperature for 30 min to activate; add 2 g of thio glycidyl ether, heat to 60°C and stir for 6 h, cool after reaction, centrifuge to remove byproducts, wash, vacuum dry at 40°C to get dry powder state of core-shell structure adhesive.

[0032] Comparative Example 2 S1: 4 mol of acrylic acid, 0.1 mol of thio-trithiocarbonate and 0.05 mol of AIBN were added into 250 mL, mixed uniformly; 150 mL of ethanol / deionized water mixed solvent (volume ratio 1:1) was further added, stirred uniformly; 70°C was raised, 400 rpm was stirred for 8 h, after the reaction was completed, it was cooled, centrifuged, washed, and crosslinked core particles were obtained; S2: 10 g of β-CD was dissolved in 200 mL of deionized water, stirred until clear; 15 g of polyethylene oxide was slowly added, stirred at 25°C for 12 h to obtain a complex solution; freeze-dried to obtain a complex powder for standby; S3: 5 g of the obtained crosslinked core particles were dispersed in deionized water (solid content 5 wt%), 0.1 g of diisocyanate was added, and a deionized water solution containing 1 g of complex powder (solid content 5 wt%) was slowly added under heating at 50°C, ultrasonic stirring was performed, and a core-shell product was formed; S4: 5 g of the core-shell product prepared above was dispersed in DMF to form a solution with a solid content of 5 wt%, and was placed in a nitrogen atmosphere, 1 g of carbodiimide was added, and stirring was performed at room temperature for 30 min to activate; 2 g of thio-glycidyl ether was added, and stirring was performed at 60°C for 6 h, after the reaction was completed, it was cooled, centrifuged to remove by-products, washed, and vacuum dried at 40°C to obtain a dry powder state of the core-shell structure adhesive.

[0033] Comparative Example 3 S1: 10 g of β-CD was dissolved in 200 mL of deionized water, stirred until clear; 15 g of polyethylene oxide was slowly added, stirred at 25°C for 12 h to obtain a complex solution; freeze-dried to obtain a complex powder for standby; S3: S1: 3 mol of acrylic acid, 1 mol of divinylbenzene, 0.1 mol of thio-trithiocarbonate and 0.05 mol of AIBN were added into 250 mL, mixed uniformly; 150 mL of ethanol / deionized water mixed solvent (volume ratio 1:1) was further added, stirred uniformly; 1 g of complex powder was added to deionized water solution (solid content 5 wt%), 70°C was raised, 400 rpm was stirred for 8 h, after the reaction was completed, it was cooled, centrifuged, washed, and a product was obtained; S4: 5 g of the product prepared above was dispersed in DMF to form a solution with a solid content of 5 wt%, and was placed in a nitrogen atmosphere, 1 g of carbodiimide was added, and stirring was performed at room temperature for 30 min to activate; 2 g of thio-glycidyl ether was added, and stirring was performed at 60°C for 6 h, after the reaction was completed, it was cooled, centrifuged to remove by-products, washed, and vacuum dried at 40°C to obtain a dry powder state of the adhesive.

[0034] Comparative Example 4 S1 : 3 mol of acrylic acid, 1 mol of divinylbenzene, 0.1 mol of tri- thiocarbonate and 0.05 mol of AIBN were added into 250 mL, mixed uniformly; 150 mL of ethanol / deionized water mixed solvent (volume ratio 1:1) was further added, stirred uniformly; 70°C was raised, 400 rpm was stirred for 8 h, after the reaction was completed, it was cooled, centrifuged, washed, and crosslinked core particles were obtained; S2: 10 g of β-CD was dissolved in 200 mL of deionized water, stirred until clear; 15 g of polyethylene oxide was slowly added, stirred at 25°C for 12 h to obtain a complex solution; freeze-dried to obtain a complex powder for standby; S3: 5 g of the obtained crosslinked core particles were dispersed in deionized water (solid content 5 wt%), 0.1 g of diisocyanate was added, and 1 g of the complex powder was slowly added into the deionized water solution (solid content 5 wt%) under the condition of 50°C heating, ultrasonic stirring, reaction was completed, cooled, centrifuged to remove by-products, washed, vacuum dried at 40°C to obtain a dry powder state of the core-shell structure binder.

[0035] Comparative Example 5 S1 : 10 g of β-CD was dissolved in 200 mL of deionized water, stirred until clear; 15 g of PVDF was slowly added, stirred at 25°C for 12 h to obtain a complex solution; freeze-dried to obtain a complex powder for standby; S2: 3 mol of acrylic acid, 1 mol of divinylbenzene, 0.1 mol of tri- thiocarbonate and 0.05 mol of AIBN were added into 250 mL, mixed uniformly; 150 mL of ethanol / deionized water mixed solvent (volume ratio 1:1) was further added, stirred uniformly; 1 g of the complex powder was added into the deionized water solution (solid content 5 wt%), 70°C was raised, 400 rpm was stirred for 8 h, after the reaction was completed, it was cooled, centrifuged, washed, and vacuum dried at 40°C to obtain a dry powder state of the binder.

[0036] Battery preparation: Negative electrode preparation: In the glove box, SiOx / C 720 mg, Li3PS 490 mg, and 90 mg of the core-shell binder prepared above were weighed. The above materials were placed in a polyethylene mortar, and a low-speed planetary ball mill was used at 200 rpm for 20 min. After the ball milling was completed, the 14 mm round pieces were directly pressed, vacuum dried, and cut into negative electrode pieces.

[0037] Positive electrode preparation: In a glove box, weigh: NMC622 700 mg, Li3PS4 250 mg, the core-shell binder prepared above 40 mg, conductive carbon 10 mg. Put the above materials in a polyethylene mortar, use a low-speed planetary ball mill at 100 rpm for 10 min, after ball milling, directly press the tablet, cut the 14 mm round tablet as the negative electrode after vacuum drying.

[0038] Dense Li3PS4 electrolyte tablet preparation: In a glove box, weigh 200 mg of Li3PS4 powder for making a 14 mm diameter tablet. Fill the powder into a hard mold and use a unidirectional cold press machine to press: initial pressure 50 MPa for 1 min, then increase to 300 MPa for 10 min, to obtain a dense Li3PS4 electrolyte tablet.

[0039] Assembly: Take out the cut positive electrode tablet, Li3PS4 electrolyte tablet, negative electrode tablet and current collector in the glove box.

[0040] Place the positive electrode tablet flat, stack the Li3PS4 electrolyte tablet on top, and finally place the negative electrode tablet and Cu current collector. After alignment, place it in the tablet press mold. Lightly press at 30 MPa for 2 min, gradually increase the pressure to 300 MPa, and hold for 10 min, then slowly release the pressure, take out the stack, fix and seal according to the corresponding procedures, to obtain a solid-state battery.

[0041] The solid-state battery prepared from the above binder was tested as follows.

[0042] 1. Peeling strength test: A KT-PSA-1056 peeling force tester was used to test the peeling strength of the prepared and dried negative electrode tablet.

[0043] 2. Cycle retention rate: At room temperature, charge to the charge cut-off voltage 4.2V at a current of 0.5C, then constant voltage charge to the cut-off current 0.05C, stand for 0.5h, then discharge to the cut-off voltage 3.0V at a current of 0.5C, stand for 0.5h, enter the next charge-discharge cycle, and so on, a total of 500 charge-discharge cycles. Calculate the cycle retention rate.

[0044] 3. First discharge capacity test At room temperature, discharge the prepared battery at a constant current of 0.1C to the cut-off voltage 3.0V. Get the first discharge capacity.

[0045] 4. Battery expansion amount test Test the thickness of the prepared battery as d1, the thickness of the battery after 500 cycles as d2, and the battery expansion rate = (d2-d1 / d1)100%.

[0046] The test results are shown in Table 1.

[0047] Table 1 Test results The binder of the present application adopts a core-shell double-layer structure, wherein the inner core is composed of cross-linked acrylic acid / divinylbenzene, which is a high modulus structure, providing sufficient structural rigidity to maintain the integrity of the entire electrode frame, effectively preventing the displacement between silicon particles and the pulverization of the electrode. The shell layer is a low modulus polyethylene oxide-β-cyclodextrin inclusion complex, which has flexibility and high strain tolerance, enabling it to absorb and disperse local stress when the silicon particles expand, forming a gradient modulus transition zone, avoiding stress concentration between the rigid electrolyte and the negative active layer. This gradient modulus structure realizes a continuous transition from "soft-hard-soft", effectively reducing the risk of interface peeling and crack propagation, so that the electrode can still maintain stable structural integrity after multiple charge and discharge cycles.

[0048] Secondly, in terms of ion conduction and interface reconstruction, the β-cyclodextrin in the shell layer fixes the polyethylene oxide (PEO) segment through intramolecular inclusion. Due to local stress and electric field induction during charge and discharge cycles, the β-cyclodextrin inclusion bond reversibly dissociates, gradually releasing PEO segments. These segments can penetrate into the microcracks between silicon particles and solid-state electrolyte in situ, forming a flexible ion conduction layer. This layer not only realizes the self-healing of the interface, but also constructs a continuous Li + transport channel on a nanoscale, making the Li + diffusion coefficient increase by about 3 times. Compared with traditional inert binders such as PVDF, the binder of the present application can "dynamically reconstruct the interface" during the cycle process, realizing the adaptive repair and electrochemical activation of the ion channel, thereby significantly improving the capacity retention rate (>90%) and the adaptability of high-load electrodes.

[0049] In addition, the surface-grafted thio-glycidyl ether can form -S-S- covalent bridges with sulfide electrolytes (such as Li3PS4) in the solid-state interface, further enhancing the interfacial bonding force between the electrode and the electrolyte, making the peeling strength increase from <15 N / m in the traditional PVDF system to >35 N / m. This chemical coupling effect and the gradient modulus buffer together realize the mechanical and chemical dual-dimensional stabilization, effectively inhibiting the interface delamination and resistance increase problems of the silicon negative electrode system under fast charging and high load conditions.

[0050] In summary, through the gradient modulus design of the core-shell structure binder and the introduction of the reconfigurable ion network, the present application realizes the "stress absorption-interface self-healing-ion conduction" synergistic mechanism of the silicon negative electrode-solid-state electrolyte interface, significantly improving the cycle stability and interface reliability of the solid-state silicon-carbon negative electrode, representing the technical progress of the solid-state battery binder in the aspects of mechanical adaptation and interface functionalization.

[0051] The present application can also be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A core-shell structure binder, characterized by, The binder comprises an inner core layer and an outer shell layer arranged on the outer surface of the inner core layer and at least partially covering the inner core layer; The comonomer of the inner core layer comprises acrylic acid and divinyl benzene; The material of the outer shell layer is a polyethylene oxide-beta-cyclodextrin material grafted with thio glycidyl ether.

2. The core-shell structure binder of claim 1, wherein, The monomer molar ratio of the acrylic acid and divinyl benzene is 3-4:

1.

3. The method for preparing the core-shell structure binder according to any one of claims 1-2, characterized in that, The method comprises the following steps: S1: adding acrylic acid, divinyl benzene, a RAFT agent and an initiator into a reactor, mixing uniformly, then adding a solvent and stirring uniformly, and then performing a reaction under temperature rising and stirring, and then cooling, centrifuging, and washing after the reaction to obtain crosslinked core particles; S2: dissolving beta-CD in a solvent and stirring until clear, slowly adding polyethylene oxide, and then stirring at room temperature to obtain a complex solution, and then freeze-drying to obtain a complex powder for standby use; S3: dispersing the obtained crosslinked core particles in a solvent, adding a crosslinking agent, slowly adding the complex powder solution under heating, and then ultrasonically stirring to form a core-shell product; S4: dispersing the core-shell product in a solution, adding a carbodiimide under nitrogen protection, stirring at room temperature to activate, adding thio glycidyl ether, and then stirring and reacting under temperature rising, and then cooling, centrifuging to remove by-products, and then washing and vacuum drying to obtain a dry powder state core-shell structure binder.

4. The preparation method according to claim 3, characterized in that, The RAFT agent is selected from one of trithiocarbonates or dithiobenzoic acid 4-cyanopentanoic acid; and the initiator is AIBN.

5. The preparation method according to claim 3, characterized in that, The reaction temperature under temperature rising and stirring in S1 is 50-70°C, and the reaction time is 6-8 h.

6. The preparation method according to claim 3, characterized in that, The addition molar ratio of the acrylic acid, divinyl benzene, the RAFT agent and the initiator in S1 is 3-4:1:0.1:0.02-0.

05.

7. The preparation method according to claim 3, characterized in that, The Mw of the polyethylene oxide is 6k-12k; and the addition mass ratio of the beta-CD to the polyethylene oxide is 1:1-2.

8. The preparation method according to claim 3, characterized in that, The crosslinking agent in S3 is selected from one of divinylthiopropane, glutaraldehyde and diisocyanate; and the addition mass ratio of the crosslinked core particles, the crosslinking agent and the complex powder is 1:0.01-0.02:0.2-0.

3.

9. The preparation method according to claim 3, characterized in that, The solid content of the core-shell product in the solvent in S4 is 5-10wt%, and the addition mass ratio of the core-shell product to the thio glycidyl ether is 1:0.4-1.

10. Application of the core-shell structure binder prepared according to any one of claims 1-2 or prepared by the method of any one of claims 3-9 to a solid-state battery negative electrode material.

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