A binder precursor solution, a positive electrode slurry, a positive electrode sheet, a method for manufacturing the same, and a full solid-state battery

Abstract

The present application relates to the technical field of solid-state batteries, in particular to a binder precursor solution, a positive electrode slurry, a positive electrode sheet, a preparation method of the positive electrode sheet and a solid-state battery. The binder precursor solution comprises a binder matrix, a co-crosslinking agent, a thermal initiator and a solvent; wherein the binder matrix comprises styrene-butadiene rubber and polyisobutylene capped with an alkenyl group; and the co-crosslinking agent comprises a multi-sulfhydryl compound. The binder precursor solution is directly added to the positive electrode slurry system, and a click reaction is triggered synchronously during the drying and heating stage after coating, so that the SBR and the polyisobutylene capped with an alkenyl group form a three-dimensional interpenetrating crosslinking network through chemical bonding. The two phases of SBR and PIB form synergistic complementation and coupling enhancement in terms of adhesion, mechanical properties and chemical stability, and the comprehensive performance is significantly better than that of the two types of binders used alone or simply physically blended. Meanwhile, the solubility problem of the pre-modified binder is avoided, and the wet preparation process of the existing positive electrode sheet is adapted.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more specifically, to a binder precursor solution, a positive electrode slurry, a positive electrode sheet, a method for preparing the same, and an all-solid-state battery. Background Technology

[0002] Sulfide solid electrolytes (such as Li6PS5Cl and LPSCl) possess high room-temperature ionic conductivity and good mechanical deformability, making them a key material for next-generation high-energy-density, high-safety all-solid-state batteries (ASSBs), currently in the early stages of commercialization. However, in practical applications, the operating pressure of all-solid-state batteries is typically limited to below 5 MPa, far lower than the hundreds of megapascals pressures commonly used in laboratory research. Under low-pressure conditions, the volume changes in the positive electrode active material (such as high-nickel ternary materials NCM) during charge and discharge can lead to interfacial contact failure between the active material and the solid electrolyte, resulting in increased interfacial resistance and capacity decay.

[0003] Binders are crucial components for maintaining the structural integrity of composite cathodes. Currently, wet-process sulfide batteries commonly employ rubber-based binders that are soluble in non-polar solvents such as toluene and xylene. Styrene-butadiene rubber (SBR) and polyisobutylene (PIB) are two representative systems, but both have their own performance limitations, and a single system cannot meet the comprehensive requirements of industrial applications.

[0004] SBR exhibits good bonding and molding properties, but the presence of unsaturated butadiene double bonds in its molecular chain makes it susceptible to oxidative degradation on the high-voltage positive electrode side. Furthermore, prolonged contact with alkaline sulfide electrolytes poses a risk of side reactions, leading to a continuous increase in interfacial impedance. Simultaneously, SBR suffers from low elastic recovery and insufficient creep resistance, making it difficult to effectively buffer the volumetric deformation of high-nickel materials. Under long-term low-voltage operation, it is prone to particle slippage and interfacial delamination, resulting in rapid capacity decay. Some studies have modified SBR through crosslinking, but this only increases the modulus and fails to improve its chemical stability and long-term interfacial compatibility, resulting in limited performance improvements.

[0005] Poly(ethylene glycol) (PIB) possesses a fully saturated hydrocarbon backbone structure, exhibiting excellent chemical inertness and good compatibility with sulfide electrolytes, posing no risk of defluorination or oxidative decomposition. However, ordinary linear PIB lacks active reaction sites, making it difficult to construct a cross-linked network through mild processes. Cold creep is a significant issue, and the molecular chains are prone to slippage under long-term pressure, resulting in unsatisfactory electrode compaction density retention. Furthermore, PIB has a low surface energy, leading to weak adhesion to ternary active materials, conductive carbon, and aluminum foil current collectors, resulting in low electrode peel strength and a tendency for powder shedding and delamination during roll cutting. Using peroxide for high-temperature cross-linking of PIB typically requires temperatures above 160°C, which would cause thermal decomposition of the sulfide electrolyte and release of H2S, rendering the process impractical.

[0006] To balance the properties of both types of adhesives, existing technologies attempt to use physical blending of SBR and PIB as a composite adhesive. However, this is merely a simple mechanical mixing, lacking chemical bonds between molecules, resulting in limited compatibility and easy micro-phase separation. It fails to form a unified three-dimensional cross-linked network, and the cold creep problem of PIB has not been effectively solved, nor has the insufficient elasticity of SBR been fundamentally improved, resulting in limited overall performance improvement.

[0007] Given the above problems, how to achieve chemical bonding and synergistic enhancement of SBR and PIB components at the molecular scale through a mild low-temperature crosslinking process while adapting to the existing wet process of sulfide solid-state batteries, and taking into account the chemical stability, elastic creep resistance and long-term structural integrity of the system under high areal loading thick electrode and low-voltage operating conditions, is a technical problem that urgently needs to be solved in this field.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] To address the shortcomings of the existing technologies, this invention provides a binder precursor solution, a positive electrode slurry, a positive electrode sheet, a preparation method thereof, and an all-solid-state battery. Based on the high selectivity, high yield, and mild reaction characteristics of the mercapto-alkene click chemistry reaction, it uses styrene-butadiene rubber (SBR) and alkenyl-terminated polyisobutylene (PIB) as binder matrices and a multi-thiol compound as a co-crosslinking agent. During the drying and curing process after the positive electrode slurry is coated onto the current collector, the mercapto groups simultaneously undergo covalent addition with the double bonds of the butadiene segments in the SBR molecular chain and the alkenyl double bonds at the ends of the PIB, connecting the SBR and PIB segments through covalent bonds to form a three-dimensional interpenetrating crosslinked network. This results in synergistic complementarity and enhanced coupling between the SBR and PIB phases in terms of adhesion, mechanical properties, and chemical stability, with significantly better overall performance than when the two binders are used alone or simply physically blended. Simultaneously, it avoids the solubility problem of pre-modified binders and is compatible with existing wet preparation processes for positive electrodes.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: An adhesive precursor solution includes an adhesive matrix, a co-crosslinking agent, a thermal initiator, and a solvent; wherein the adhesive matrix includes styrene-butadiene rubber and polyisobutylene with alkenyl groups at the end; and the co-crosslinking agent includes a polythiol compound.

[0011] Preferably, the polythiol compound includes at least one of 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane and mercaptopropylsilsesquioxane oligomers.

[0012] Preferably, the mass ratio of the styrene-butadiene rubber to the polyisobutylene with alkenyl groups at the end is 1:0.2 to 1:2.

[0013] Preferably, the mass ratio of the adhesive matrix to the co-crosslinking agent is 10:1 to 6:1.

[0014] Preferably, the thermal initiator comprises azobisisobutyronitrile.

[0015] Preferably, the amount of the thermal initiator added is 8wt% to 12wt% of the binder matrix.

[0016] Preferably, the number average molecular weight of the polyisobutylene with alkenyl groups at the end is 5,000 to 250,000.

[0017] Preferably, the alkenyl group is a vinyl group or a vinylsiloxane group.

[0018] Preferably, the solvent includes at least one of p-xylene, toluene, trimethylbenzene, and alkanes.

[0019] Preferably, the method for preparing the binder precursor solution includes the following steps: The adhesive matrix is ​​dissolved in the solvent, and then the thermal initiator and the co-crosslinking agent are added and mixed evenly to obtain the adhesive precursor solution.

[0020] A positive electrode slurry includes a positive electrode active material, a sulfide solid electrolyte, a conductive agent, and a binder precursor solution as described in any of the preceding embodiments.

[0021] A positive electrode sheet, the raw materials of which include the positive electrode slurry described in the foregoing embodiments.

[0022] A method for preparing a positive electrode sheet includes the following steps: The positive electrode slurry described in the foregoing embodiments is coated onto the current collector and dried to obtain the positive electrode sheet; the drying includes vacuum drying at 75~85℃ for 10~20h.

[0023] An all-solid-state battery includes a positive electrode, wherein the positive electrode is the positive electrode described in the foregoing embodiments, or a positive electrode prepared by the method described in the foregoing embodiments.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The binder precursor solution of the present invention uses SBR and PIB with alkenyl groups as composite binder matrix and multi-thiol compound as co-crosslinking agent. Under the action of thermal initiator, the thiol group in the co-crosslinking agent can undergo thiol-alkene click reaction with the double bond in SBR and PIB with alkenyl groups under mild conditions to construct a covalently bonded interpenetrating three-dimensional crosslinking network. This makes the SBR and PIB phases synergistically complementary and coupled to enhance their adhesion, mechanical properties and chemical stability. The overall performance is significantly better than that of the two types of binders used alone or in simple physical blending.

[0025] (2) The present invention adopts an in-situ crosslinking process design, in which the binder matrix participates in the slurry preparation in a soluble state, and crosslinking and curing are completed simultaneously during the coating and drying process. This not only ensures the uniformity of the slurry, but also avoids the process problem of the pre-crosslinked material being difficult to dissolve. It is compatible with the wet process of sulfide solid battery cathode sheet and has good compatibility with existing mainstream production lines.

[0026] (3) Based on the high selectivity, high yield and mild reaction characteristics of mercapto-olefin click chemistry, this invention constructs a co-crosslinking composite binder system of SBR and PIB with alkenyl groups at the end. This binder system has high modulus, high elastic recovery rate, high chemical stability and strong adhesion. It can significantly improve the cycle stability of all-solid-state batteries under low pressure of 5MPa and is suitable for the preparation of thick electrodes with high areal loading. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0028] A first aspect of the present invention provides an adhesive precursor solution comprising an adhesive matrix, a co-crosslinking agent, a thermal initiator, and a solvent; wherein the adhesive matrix comprises styrene-butadiene rubber and polyisobutylene with alkenyl groups at the end (i.e., the end groups of polyisobutylene contain alkenyl groups); the co-crosslinking agent comprises a polythiol compound, wherein in the present invention, a polythiol compound refers to a compound containing two or more thiol groups.

[0029] The binder precursor solution provided by this invention comprises SBR and PIB with alkenyl groups at the ends. The butadiene double bond in the SBR molecular chain and the alkenyl double bond at the end of the PIB molecular chain with alkenyl groups at the ends can both serve as active sites for thiol-alkene addition. Under the action of a thermal initiator, the multi-thiol compound can covalently add to both types of double bonds simultaneously under mild conditions, forming a chemically bonded three-dimensional interpenetrating crosslinked network between the SBR and PIB segments. This results in a synergistic complementarity and enhanced coupling between the SBR and PIB phases in terms of adhesion, mechanical properties, and chemical stability, with overall performance significantly better than that of using the two types of binders alone or in simple physical blending.

[0030] In some specific embodiments of the present invention, the polythiol compound includes at least one of 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane and mercaptopropylsilsesquioxane oligomers.

[0031] In some specific embodiments of the present invention, the mass ratio of styrene-butadiene rubber and polyisobutylene with alkenyl groups at the end is 1:0.2 to 1:2. For example, it can be any one value or a range of any two values ​​from 1:0.2, 1:0.3, 1:0.5, 1:1, 1:1.5, 1:2.

[0032] In some specific embodiments of the present invention, the mass ratio of the binder matrix to the co-crosslinking agent is 10:1 to 6:1. For example, it can be any one value or a range of any two values ​​among 10:1, 9:1, 8:1, 7:1, and 6:1.

[0033] In some specific embodiments of the present invention, the thermal initiator includes azobisisobutyronitrile (AIBN).

[0034] In some specific embodiments of the present invention, the amount of thermal initiator added is 8wt% to 12wt% of the binder matrix. For example, it can be any one value or a range of any two values ​​from 8wt%, 9wt%, 10wt%, 11wt%, to 12wt%.

[0035] In some specific embodiments of the present invention, the number average molecular weight of the polyisobutylene with alkenyl group end caps is 5,000 to 250,000. For example, it can be any one value or a range of any two values ​​among 5,000, 10,000, 50,000, 100,000, 150,000, 200,000, and 250,000.

[0036] In some specific embodiments of the present invention, the alkenyl groups in the polyisobutylene with alkenyl groups at the ends are vinyl groups or vinylsiloxane groups; the double bonds in the vinyl groups can undergo a mercapto-alkene click chemical reaction with the mercapto groups to achieve covalent bonding between the PIB segments and the SBR; when the alkenyl groups are vinylsiloxane groups, they can not only achieve co-crosslinking, but the terminal siloxane groups can also form chemical bonds with inorganic particles and current collector surfaces to achieve interfacial coupling enhancement; at the same time, they assume the dual functions of "crosslinking component" and "interfacial coupling agent", improving the mechanical properties of the system while simultaneously enhancing the interfacial bonding force, simplifying the formulation and process.

[0037] In some specific embodiments of the present invention, the solvent includes at least one of p-xylene, toluene, trimethylbenzene, and alkanes; used to completely dissolve the binder matrix and without chemically reacting with the sulfide solid electrolyte.

[0038] In some specific embodiments of the present invention, the total amount of solid matter in the binder precursor solution accounts for 1wt%-8wt% of the binder precursor solution. For example, it can be any value or a range of any two values ​​from 1wt%, 3wt%, 5wt%, to 8wt%; preferably, it is 1wt%-5wt%. When the total concentration of solid matter in the binder precursor solution is high (e.g., greater than 5wt%), additional solvent can be added as needed when preparing the slurry later.

[0039] In some specific embodiments of the present invention, the method for preparing the binder precursor solution includes the following steps: Add the binder matrix to the solvent and stir until completely dissolved; then add the thermal initiator and co-crosslinking agent and stir evenly to obtain the binder precursor solution.

[0040] A second aspect of the present invention provides a positive electrode slurry, comprising a positive electrode active material, a sulfide solid electrolyte, a conductive agent, and a binder precursor solution provided in the first aspect of the present invention. In some embodiments, if the binder precursor solution concentration is high, an appropriate amount of solvent can be added during slurry preparation according to the required slurry concentration.

[0041] As an example, the positive electrode active material used can be LiNi. 0.9 Co 0.05 Mn 0.05 O2 (NCM9); the sulfide solid electrolyte used can be Li6PS5Cl; the conductive agent used can be SuperC65.

[0042] In some specific embodiments of the present invention, the solid composition of the positive electrode slurry includes: 80wt%~85wt% positive electrode active material, 10wt%~20wt% sulfide solid electrolyte, 0.5~1.5wt% conductive agent, and 1wt%~2wt% binder precursor; wherein, the binder precursor refers to all solid substances in the binder precursor solution, including binder matrix, co-crosslinking agent and initiator.

[0043] A third aspect of the present invention provides a positive electrode sheet whose raw materials include the positive electrode slurry provided in the second aspect of the present invention.

[0044] A fourth aspect of the present invention provides a method for preparing a positive electrode sheet, comprising the following steps: The positive electrode slurry provided in the second aspect of the present invention is coated onto a current collector and dried to obtain a positive electrode sheet; wherein, the drying includes vacuum drying at 75~85°C (for example, any one value or a range of any two values ​​among 75°C, 78°C, 80°C, 82°C, and 85°C) for 10~20h (for example, any one value or a range of any two values ​​among 10h, 12h, 15h, 18h, and 20h); since the coating is prone to peeling or damage during the transfer process, it is preferable to dry the coated sheet at room temperature until it is set before transferring it to a drying oven for heat drying. During the heating and drying process at 75~85℃, the double bonds in the binder matrix react in situ with the thiol groups in the co-crosslinking agent to form a three-dimensional interpenetrating network. This invention adopts an in-situ crosslinking process design, in which the binder matrix participates in the slurry preparation in a soluble state and completes crosslinking and curing simultaneously during the coating and drying process. This ensures the uniformity of the slurry and avoids the solubility problem of pre-crosslinked materials. It is suitable for wet process of sulfide solid-state batteries and has good compatibility with existing mainstream production lines.

[0045] The fifth aspect of this method provides an all-solid-state battery, including a positive electrode, wherein the positive electrode is the positive electrode provided in the third aspect of this invention, or a positive electrode prepared by the method for preparing the positive electrode provided in the fourth aspect of this invention.

[0046] In some specific embodiments of the present invention, the all-solid-state battery further includes a sulfide solid electrolyte layer and a negative electrode; as an example, the negative electrode is one of Li-In alloy, lithium metal or silicon-based negative electrode.

[0047] The all-solid-state battery provided by this invention can operate stably at a low voltage of 5MPa.

[0048] The following detailed description of some embodiments of the present invention is provided in conjunction with specific examples. Unless otherwise specified, all raw materials used in the embodiments can be obtained commercially available.

[0049] The experimental materials used in the examples and comparative examples are as follows: SBR (ZEON); α,ω-bis(ethylene)polyisobutylene (BASF, number average molecular weight 5000), 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane (Yingyicheng (Shanghai), CAS: 18001-52-0); AIBN (99%, Daejung Chemicals & Metals); trimethylbenzene (anhydrous, 99%, Sigma-Aldrich); PIB (BASF, model OPPANOL® B 10 SFN); Li6PS5Cl (TOB new energy); Super C65 (Imerys Graphite & Carbon); carbon-coated aluminum foil was used as the current collector; Li-In alloy anode (Li and In were mixed at a mass ratio of 1:1).

[0050] Example 1 (1) Preparation of binder precursor solution: Dissolve 0.18g SBR and 0.12g α,ω-bisethylene polyisobutylene in 13.4g tricresyl and stir until completely dissolved; add 0.03g AIBN and 0.03g 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane and continue stirring for 30 minutes to obtain the binder precursor solution.

[0051] (2) Preparation of positive electrode slurry: 16.4g NCM9, 3g LPSCl and 0.3g Super C65 were added to the precursor solution prepared in this embodiment and stirred at high speed for 2 hours to obtain a uniform positive electrode slurry.

[0052] (3) Preparation of the positive electrode: The positive electrode slurry prepared in this embodiment was coated onto a carbon-coated aluminum foil and dried at room temperature for 1 hour, followed by vacuum drying at 80°C for 12 hours to obtain a positive electrode sheet with a coating thickness of approximately 50 μm and an electrode surface loading of 10 mg / cm³. 2 .

[0053] (4) Battery assembly: In an argon glove box, 150 mg of LPSCl powder was pressed into an electrolyte sheet with a diameter of 13 mm (370 MPa). A Li-In alloy negative electrode and a positive electrode sheet prepared in this embodiment were placed on both sides of the electrolyte sheet to assemble a CR2032 coin cell and a constant pressure of 5 MPa was applied.

[0054] Example 2 (1) Preparation of binder precursor solution: Similar to Example 1, the only difference is that the amount of SBR used is 0.15g and the amount of α,ω-bis(ethylene)polyisobutylene used is 0.15g; all other conditions are the same as in Example 1.

[0055] (2) Preparation of positive electrode slurry: Similar to Example 1, the only difference is that the binder precursor solution prepared in this example is used; all other conditions are the same as in Example 1.

[0056] (3) Preparation of the positive electrode: Similar to Example 1, the only difference is that the positive electrode slurry prepared in this example is used; all other conditions are the same as in Example 1.

[0057] (4) Battery assembly: Similar to Example 1, the only difference is that the positive electrode sheet prepared in this example is used; all other conditions are the same as in Example 1.

[0058] Example 3 (1) Preparation of binder precursor solution: Similar to Example 1, the only difference is that the amount of 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane used is 0.05 g; all other conditions are the same as in Example 1.

[0059] (2) Preparation of positive electrode slurry: Similar to Example 1, the only difference is that the binder precursor solution prepared in this example is used; all other conditions are the same as in Example 1.

[0060] (3) Preparation of the positive electrode: Similar to Example 1, the only difference is that the positive electrode slurry prepared in this example is used; all other conditions are the same as in Example 1.

[0061] (4) Battery assembly: Similar to Example 1, the only difference is that the positive electrode sheet prepared in this example is used; all other conditions are the same as in Example 1.

[0062] Comparative Example 1 (1) Preparation of binder precursor solution: 0.3g SBR was directly dissolved in 13.4g tricresyl to obtain a binder precursor solution; that is, without adding α,ω-bisethylene polyisobutylene, 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane and AIBN.

[0063] (2) Preparation of positive electrode slurry: Similar to Example 1, the only difference is that the binder precursor solution prepared in this comparative example was used; all other conditions were the same as in Example 1.

[0064] (3) Preparation of the positive electrode: Similar to Example 1, the only difference is that the positive electrode slurry prepared in this comparative example is used; all other conditions are the same as in Example 1.

[0065] (4) Battery assembly: Similar to Example 1, the only difference is that the positive electrode sheet prepared in this comparative example is used; all other conditions are the same as in Example 1.

[0066] Comparative Example 2 (1) Preparation of binder precursor solution: Similar to Example 1, the only difference is that α,ω-bisethylene polyisobutylene is not added, the amount of SBR is 0.3g, and the amount of 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane is 0.03g; all other conditions are the same as in Example 1.

[0067] (2) Preparation of positive electrode slurry: Similar to Example 1, the only difference is that the binder precursor solution prepared in this comparative example was used; all other conditions were the same as in Example 1.

[0068] (3) Preparation of the positive electrode: Similar to Example 1, the only difference is that the positive electrode slurry prepared in this comparative example is used; all other conditions are the same as in Example 1.

[0069] (4) Battery assembly: Similar to Example 1, the only difference is that the positive electrode sheet prepared in this comparative example is used; all other conditions are the same as in Example 1.

[0070] Comparative Example 3 (1) Preparation of binder precursor solution: Similar to Example 1, the only difference is that α,ω-bisethylene polyisobutylene is replaced with ordinary linear PIB, and 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane and AIBN are not added. The SBR is 0.18 g and the ordinary PIB is 0.12 g. All other conditions are the same as in Example 1.

[0071] (2) Preparation of positive electrode slurry: Similar to Example 1, the only difference is that the binder precursor solution prepared in this comparative example was used; all other conditions were the same as in Example 1.

[0072] (3) Preparation of the positive electrode: Similar to Example 1, the only difference is that the positive electrode slurry prepared in this comparative example is used; all other conditions are the same as in Example 1.

[0073] (4) Battery assembly: Similar to Example 1, the only difference is that the positive electrode sheet prepared in this comparative example is used; all other conditions are the same as in Example 1.

[0074] Test case 1. The electrochemical performance of the sulfide solid-state batteries in each example and comparative example was tested. The test pressure was 5 MPa, the charge / discharge current was 0.2 C, and the voltage range was 3.0-4.4 V. The test results are shown in Table 1.

[0075] Table 1

[0076] 2. The mechanical properties of the positive electrode sheets in each embodiment and comparative example were tested respectively. The Young's modulus was tested according to GB / T 1040; the elastic recovery rate was tested according to GB / T 47029-2026; and the interfacial adhesion was tested according to ASTM D903-2010. The test results are shown in Table 2.

[0077] Table 2

[0078] As shown in Tables 1 and 2, the mechanical properties of the positive electrode and the electrochemical performance of the solid-state battery in the embodiments of the present invention are significantly better than those in the comparative example. The co-crosslinking binder system of SBR and α,ω-bisethylene polyisobutylene constructed in the present invention has high modulus, high elastic recovery rate, high chemical stability and strong adhesion, which can significantly improve the cycle stability of all-solid-state batteries under low pressure of 5MPa and is suitable for the preparation of thick electrode sheets with high areal loading. Traditional SBR binders, crosslinked modified SBR binders and SBR and PIB blend binders cannot achieve this effect.

[0079] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A binder precursor solution, characterized in that, It includes an adhesive matrix, a co-crosslinking agent, a thermal initiator, and a solvent; wherein the adhesive matrix includes styrene-butadiene rubber and polyisobutylene with alkenyl groups at the end; and the co-crosslinking agent includes a polythiol compound.

2. The binder precursor solution according to claim 1, characterized in that, The polythiol compound includes at least one of 1,3-bis(3-mercaptopropyl)-1,1,3,3-tetramethyldisiloxane and mercaptopropylsilsesquioxane oligomers.

3. The binder precursor solution according to claim 1, characterized in that, The mass ratio of the styrene-butadiene rubber to the polyisobutylene with alkenyl groups at the end is 1:0.2 to 1:

2.

4. The binder precursor solution according to claim 1, characterized in that, The mass ratio of the binder matrix to the co-crosslinking agent is 10:1 to 6:

1.

5. The binder precursor solution according to claim 1, characterized in that, It meets at least one of the following characteristics: (1) The thermal initiator includes azobisisobutyronitrile; (2) The amount of the thermal initiator added is 8wt%~12wt% of the binder matrix; (3) The number average molecular weight of the polyisobutylene with alkenyl group end caps is 5,000 to 250,000; (4) The alkenyl group is a vinyl group or a vinylsiloxane group; (5) The solvent includes at least one of p-xylene, toluene, trimethylbenzene, and alkanes.

6. The binder precursor solution according to any one of claims 1 to 5, characterized in that, The preparation method of the binder precursor solution includes the following steps: The adhesive matrix is ​​dissolved in the solvent, and then the thermal initiator and the co-crosslinking agent are added and mixed evenly to obtain the adhesive precursor solution.

7. A positive electrode slurry, characterized in that, It includes a positive electrode active material, a sulfide solid electrolyte, a conductive agent, and a binder precursor solution as described in any one of claims 1 to 6.

8. A positive electrode plate, characterized in that, The raw materials for the positive electrode include the positive electrode slurry as described in claim 7.

9. A method for preparing a positive electrode sheet, characterized in that, Includes the following steps: The positive electrode slurry of claim 7 is coated onto the current collector and dried to obtain the positive electrode sheet; the drying includes vacuum drying at 75~85℃ for 10~20h.

10. An all-solid-state battery, characterized in that, Includes a positive electrode sheet, wherein the positive electrode sheet is the positive electrode sheet according to claim 8, or the positive electrode sheet prepared by the preparation method according to claim 9.

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