A kind of ethyl cellulose modified by a bissilane coupling agent, a composite binder and its preparation method and application

Abstract

The present invention discloses a preparation method and application of a disilane coupling agent modified composite binder, specifically a preparation method of disilane coupling agent modified ethyl cellulose, comprising: hydrolysis of the disilane coupling agent: mixing a methacryloxy-type silane coupling agent and an amino-type silane coupling agent, adding the mixture to a solvent, adjusting the pH to carry out a hydrolysis reaction, and obtaining a hydrolyzed silane solution; grafting modification reaction: slowly dripping the hydrolyzed silane solution into an ethyl cellulose solution, carrying out a grafting modification reaction, and obtaining a silane-modified ethyl cellulose solution; and performing rotary evaporation, washing, and drying. The present invention also discloses disilane coupling agent modified ethyl cellulose prepared by the above-mentioned preparation method, a disilane coupling modified composite binder, a preparation method thereof, and its application in wet film formation of sulfide electrolytes. The electrolyte membrane prepared by the present invention has controllable thickness, high ionic conductivity, and high film-forming properties and flexibility.

Description

Technical Field

[0001] The present invention relates to the technical field of all-solid-state batteries, and in particular to a double silane coupling agent modified composite binder and application thereof in wet film formation of sulfide electrolytes. Background Art

[0002] Sulfide solid electrolytes are considered to be ideal electrolyte materials for all-solid-state batteries due to their high ionic conductivity and good machinability. However, their film formation process still faces many challenges: during the wet film formation process, sulfides are extremely sensitive to polar solvents (such as NMP and water) and are prone to decomposition reactions (such as the generation of H2S), resulting in degradation of electrolyte performance. At the same time, traditional binders (such as PVDF) rely on high-boiling-point solvents (such as NMP), which are not only difficult to completely remove but also undergo side reactions with sulfides, increasing interfacial impedance. In addition, the electrolyte membranes formed by wet film formation often have structural defects (such as cracks), resulting in insufficient mechanical strength and poor interfacial contact, which seriously affect the cycle stability and rate performance of the entire battery.

[0003] Currently, the selection of solvents and binders is crucial for wet-film formation of sulfide electrolytes. While common organic solvents (such as toluene) can reduce sulfide decomposition, they have poor solubility in most binders, resulting in insufficient film uniformity. A single binder (such as PTFE or styrene-butadiene rubber) struggles to simultaneously meet the requirements for high bonding strength and ion conductivity. Furthermore, the formed electrolyte membrane is prone to shrinkage and cracking during drying, and the solid-solid interface impedance with the electrode material is high, limiting large-scale fabrication and industrial application. Therefore, developing a highly compatible solvent system and multifunctional composite binder to achieve high-quality wet-film formation of sulfide electrolytes has become a key technical challenge in promoting the development of all-solid-state batteries. Summary of the Invention

[0004] To address the above-mentioned technical problems, the present invention provides a bis-silane coupling agent-modified composite binder and a wet-process sulfide electrolyte membrane formation method based on the bis-silane coupling agent-modified composite binder. Ethyl cellulose is synergistically modified with two different silane coupling agents, KH-570 (methacryloyloxy) and KH-550 (amino), and then combined with styrene-butadiene rubber to construct a three-dimensional network structure bonding system. A toluene / dibromomethane mixed solvent is used to achieve uniform sulfide electrolyte membrane formation. The modified ethyl cellulose forms a chemical bond with the sulfide electrolyte through the silane coupling agent, reducing interfacial impedance. Combined with the elastic properties of styrene-butadiene rubber, the resulting sulfide electrolyte membrane exhibits both excellent membrane-forming and ion-conducting properties.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing ethyl cellulose modified with a disilane coupling agent, comprising the following steps:

[0007] S1, hydrolyzing the disilane coupling agent: mixing a methacryloxy silane coupling agent and an amino silane coupling agent, adding the mixture to a solvent, adjusting the pH to carry out a hydrolysis reaction, and obtaining a hydrolyzed silane solution;

[0008] S2, graft modification reaction: slowly adding the hydrolyzed silane solution prepared in step S1 dropwise to the ethyl cellulose solution to carry out a graft modification reaction to obtain a silane-modified ethyl cellulose solution;

[0009] S3. Rotary evaporation is performed on the silane-modified ethyl cellulose solution to remove unreacted silane coupling agent by washing, and vacuum drying is performed to obtain the product.

[0010] As some specific embodiments of the present invention, step S1 includes at least one of the following technical features:

[0011] 1. The methacryloxy silane coupling agent includes silane coupling agent KH-570, i.e. 3-(methacryloyloxy)propyltrimethoxysilane; the amino silane coupling agent includes silane coupling agent KH-550, i.e. γ-aminopropyltriethoxysilane;

[0012] 2. The mass ratio of the methacryloxy silane coupling agent to the amino silane coupling agent is 1:1-1:3; in the hydrolyzed silane solution, the total mass fraction of the methacryloxy silane coupling agent and the amino silane coupling agent is 10-20%; specifically, the mass ratio of KH-570 to KH-550 is 1:1-1:3; in the hydrolyzed silane solution, the total mass fraction of the silane coupling agents KH-570 and KH550 is 10-20%;

[0013] 3. The solvent is a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 9:1-8:2;

[0014] 4. Adjust the pH to 4-5; perform the hydrolysis reaction at a temperature of 20-30°C, preferably room temperature, for 30-60 minutes.

[0015] As some specific embodiments of the present invention, in step S2, the ethyl cellulose solution is obtained by adding ethyl cellulose to anhydrous ethanol and stirring and dissolving it. The stirring and dissolving temperature is 50-70°C, the time is 5-10 h, and the stirring is performed by a magnetic stirrer at a stirring speed of 600-800 rpm to obtain a uniform ethyl cellulose solution. The mass fraction of the ethyl cellulose solution is 5-10%.

[0016] As some specific embodiments of the present invention, in step S2, the mass ratio of the hydrolyzed silane solution to the ethyl cellulose solution is 1:3-1:5.

[0017] As some specific embodiments of the present invention, in step S2, the temperature of the graft modification reaction is 60-70° C., and the reaction time is 5-8 h.

[0018] As some specific embodiments of the present invention, in step S3, the rotary evaporation (rotary evaporation concentration) temperature is 40-80°C, preferably 50°C, and the time is 1-3 h;

[0019] And / or, the detergent used for washing is anhydrous ethanol, and the number of washing times is 3-5 times;

[0020] And / or, the vacuum drying temperature is 40-80° C., the time is 10-15 h, and the vacuum degree is 0.03-0.08 MPa.

[0021] In a second aspect, the present invention provides an ethyl cellulose modified with a disilane coupling agent, which is prepared by any of the preparation methods described above.

[0022] In a third aspect, the present invention provides a method for preparing a composite adhesive modified with a bissilane coupling agent, comprising: adding the ethyl cellulose modified with the bissilane coupling agent and styrene-butadiene rubber to a mixed solvent of toluene and dibromomethane, and stirring until completely dissolved, preferably at room temperature.

[0023] As some specific embodiments of the present invention, the mass ratio of the ethyl cellulose modified by disilane coupling to the styrene-butadiene rubber is 1:5-1:10;

[0024] And / or, in the mixed solvent, the mass ratio of toluene to dibromomethane is 9:1-8:2.

[0025] In some specific embodiments of the present invention, the stirring temperature is 20-30° C., preferably 23-28° C., more preferably 25° C., the stirring time is 2-6 h, preferably 4 h, and the rotation speed is 300-700 rpm, preferably 500 rpm.

[0026] In a fourth aspect, the present invention provides a composite adhesive modified with a disilane coupling agent, which is prepared by any of the preparation methods described above.

[0027] As some specific embodiments of the present invention, the solid content of the bis-silane coupling agent modified composite adhesive is 4-6%.

[0028] In a fifth aspect, the present invention provides a use of the above-mentioned double silane coupling agent modified composite binder in wet film formation of sulfide electrolyte.

[0029] As some specific embodiments of the present invention, the sulfide electrolyte wet film formation includes the following steps:

[0030] A1. Preparing a sulfide electrolyte slurry: ball milling a sulfide solid electrolyte and a double silane coupling agent-modified composite binder to form a uniform sulfide electrolyte slurry;

[0031] A2. Sulfide electrolyte film formation: The sulfide electrolyte is formed into a film on the copper foil by wet coating, and then dried to obtain the sulfide electrolyte membrane.

[0032] As some specific embodiments of the present invention, in step A1, the sulfide solid electrolyte includes at least one of Li3PS4 and an argyrodite-type electrolyte, and the argyrodite-type electrolyte includes at least one of Li6PS5Cl, Li6PS5Br, and Li6PS5I;

[0033] The mass ratio of the sulfide solid electrolyte to the double silane coupling agent modified composite binder is 9-99:1.

[0034] As some specific embodiments of the present invention, in step A1, the ball milling time is 1-2 h, the rotation speed is 200-300 rpm, and the ball milling is carried out in a sealed argon atmosphere;

[0035] The ball milling is wet ball milling, the solvent includes toluene, and the mass ratio of toluene to sulfide electrolyte is 0.5-1.5:1.

[0036] As some specific embodiments of the present invention, in step A1, the mass fraction of the composite binder modified by the disilane coupling agent in the prepared sulfide electrolyte slurry is 1-5%.

[0037] As some specific embodiments of the present invention, in step A2, the thickness of the sulfide electrolyte membrane is 30-80 μm.

[0038] As some specific embodiments of the present invention, in step A2, the drying is performed by vacuum drying, the vacuum drying temperature is 40-80° C., the time is 10-15 h, and the vacuum degree is 0.03-0.08 MPa.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) In the present invention, the acyl group of the silane coupling agent KH-570 condenses with the hydroxyl group of ethyl cellulose to form a cross-linked network, and the amino group of the silane coupling agent KH-550 coordinates with the lithium ions on the surface of the sulfide. The dual effects significantly enhance the interfacial bonding strength and reduce the interfacial impedance.

[0041] (2) At the same time, the viscosity of styrene-butadiene rubber and the rigidity of ethyl cellulose synergistically enable the electrolyte membrane to have both high film-forming properties and flexibility, and the mixed solvent system effectively avoids the decomposition of the sulfide electrolyte.

[0042] (3) The electrolyte membrane prepared by the present invention has controllable thickness and high ionic conductivity retention rate, which solves the key problems of many interfacial side reactions and poor structural integrity in traditional wet film formation and is suitable for large-scale production of high-performance sulfide all-solid-state batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0044] Figure 1 This is a schematic diagram of the process of preparing a composite binder modified with a bissilane coupling agent and using it for wet film formation of a sulfide electrolyte in Example 1;

[0045] Figure 2 This is a scanning electron microscope image (SEM image) of the sulfide electrolyte membrane prepared in Example 1. DETAILED DESCRIPTION

[0046] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0047] For ease of understanding, the abbreviations or nouns mentioned in the text are first explained:

[0048] Silane coupling agent KH-570: γ-methacryloxypropyltrimethoxysilane;

[0049] Silane coupling agent KH-560: γ-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0050] Silane coupling agent KH-550: γ-aminopropyltriethoxysilane.

[0051] Example 1

[0052] This embodiment provides a method for preparing a double silane coupling agent modified composite binder and using the same for wet film formation of sulfide electrolyte. The specific process is as follows: Figure 1 shown.

[0053] 1. Preparation of double silane coupling agent modified composite adhesive:

[0054] (1) Pretreatment of ethyl cellulose: Weigh 5 g of ethyl cellulose and add it to 95 g of anhydrous ethanol. Stir the mixture at a magnetic stirring speed of 700 rpm in a 60 °C water bath for 6 h to obtain a uniform ethyl cellulose solution with a mass fraction of 5%.

[0055] (2) Hydrolysis of silane coupling agent: 1.5 g of KH-570 silane coupling agent and 1.5 g of KH-550 silane coupling agent (mass ratio 1:1) were mixed and added to a mixed solvent consisting of 27 mL of anhydrous ethanol and 3 mL of deionized water (volume ratio 9:1). The pH was adjusted to 4.5 with dilute hydrochloric acid, and hydrolyzed at room temperature of 25 °C with magnetic stirring for 45 min to obtain a hydrolyzed silane solution.

[0056] (3) Graft modification reaction: The hydrolyzed silane solution (total mass 30 g) prepared in step (2) was slowly added dropwise to 100 g of ethyl cellulose solution prepared in step (1), with the addition rate controlled at 1 mL / min. The mixture was reacted in an oil bath at 65°C for 6 h to obtain a silane-modified ethyl cellulose solution.

[0057] (4) Post-treatment purification: The ethyl cellulose solution was concentrated by rotary evaporation at 50°C, and then washed with anhydrous ethanol four times. The washed product was placed in a vacuum drying oven and dried at 60°C and 0.05 MPa for 12 h to obtain a solid sample of ethyl cellulose modified with a disilane coupling agent.

[0058] (5) Preparation of composite binder: 1.0 g of ethyl cellulose solid sample modified with a disilane coupling agent and 5.0 g of styrene-butadiene rubber (mass ratio 1:5) were added to a mixed solvent consisting of 90 g of toluene and 10 g of dibromomethane (mass ratio 9:1). The mixture was stirred magnetically at 500 rpm for 4 h at room temperature (25°C) to obtain a uniform modified composite binder solution with a solid content of 5.66%.

[0059] 2. Use of double silane coupling modified composite binder for wet film formation of sulfide electrolyte:

[0060] (1) Preparation of sulfide electrolyte slurry: In an argon-filled glove box, 10 g of sulfide electrolyte was added to a ball mill. 5.3 g of the composite binder solution and 6 g of toluene solvent were then added to uniformly disperse the electrolyte. After sealing, the mixture was ball milled at room temperature for 2 h at a speed of 300 rpm to obtain a uniform electrolyte slurry. The mass fraction of the composite binder in the sulfide electrolyte was 3%.

[0061] (2) Sulfide electrolyte wet film formation: The electrolyte slurry was coated on a copper foil substrate in an argon-filled glove box with a thickness of 60 μm. The film was then air-dried for 2 h. The film was then dried in a vacuum oven at 50°C and a vacuum degree of 0.05 MPa for 12 h.

[0062] like Figure 2 The figure shows a scanning electron microscope image of the sulfide electrolyte membrane prepared in Example 1. Figure 2 It can be seen that the surface of the sulfide electrolyte membrane is very smooth and uniform, without any unevenness or cracks. This is because the modified composite binder enhances the film-forming property of the sulfide electrolyte.

[0063] Example 2

[0064] 1. This embodiment provides a method for preparing a composite adhesive modified with a bissilane coupling agent, the steps of which are as follows:

[0065] (1) Pretreatment of ethyl cellulose: 8 g of ethyl cellulose was weighed and added to 92 g of anhydrous ethanol. The mixture was stirred at 750 rpm in a water bath at 65 °C for 8 h to obtain a uniform ethyl cellulose solution with a mass fraction of 8%.

[0066] (2) Hydrolysis of silane coupling agent: Mix 1.2 g of KH-570 silane coupling agent and 2.4 g of KH-550 silane coupling agent (mass ratio 1:2) and add them to a mixed solvent consisting of 24 mL of anhydrous ethanol and 6 mL of deionized water (volume ratio 8:2). Adjust the pH to 4.5 with dilute hydrochloric acid and hydrolyze with magnetic stirring at room temperature of 25°C for 50 min.

[0067] (3) Graft modification reaction: 30 g of the hydrolyzed silane solution prepared in step (2) was slowly added dropwise to 100 g of the ethyl cellulose solution prepared in step (1), with the addition rate controlled at 0.8 mL / min. The reaction was carried out in a 68 °C oil bath for 7 h to obtain a disilane coupling agent-modified ethyl cellulose solution.

[0068] (4) Post-treatment purification: The reaction solution was concentrated by rotary evaporation at 55 °C, and then washed with anhydrous ethanol five times. The washed product was placed in a vacuum drying oven and dried at 70 °C and 0.06 MPa for 14 h to obtain a solid sample of ethyl cellulose modified with a disilane coupling agent.

[0069] (5) Preparation of composite binder: 1.0 g of ethyl cellulose sample modified with a disilane coupling agent and 5.0 g of styrene-butadiene rubber (mass ratio 1:5) were added to a mixed solvent consisting of 90 g of toluene and 10 g of dibromomethane (mass ratio 9:1). The mixture was stirred magnetically at 500 rpm for 4 h at room temperature (25°C) to obtain a uniform composite binder solution with a solid content of 5.66%.

[0070] 2. Use of double silane coupling modified composite binder for wet film formation of sulfide electrolyte:

[0071] (1) Preparation of sulfide electrolyte slurry: In an argon-filled glove box, 10 g of sulfide electrolyte was added to a ball mill. 5.3 g of the composite binder solution and 6 g of toluene solvent were then added to uniformly disperse the electrolyte. After sealing, the mixture was ball milled at room temperature for 2 h at a speed of 300 rpm to obtain a uniform electrolyte slurry. The mass fraction of the composite binder in the sulfide electrolyte was 3%.

[0072] (2) Sulfide electrolyte wet film formation: The electrolyte slurry was coated on a copper foil substrate in an argon-filled glove box with a thickness of 60 μm. The film was then air-dried for 2 h. The film was then dried in a vacuum oven at 50°C and a vacuum degree of 0.05 MPa for 12 h.

[0073] Comparative Example 1

[0074] The step of modifying ethyl cellulose with KH-570 and KH-550 silane coupling agents in Example 1 was omitted. Instead, a composite binder solution was prepared directly using unmodified ethyl cellulose and styrene-butadiene rubber in a toluene / dibromomethane mixed solvent. The resulting composite binder solution was then used for wet film formation of sulfide electrolytes.

[0075] That is, compared with Example 1, when preparing the composite adhesive, steps (1) to (4) are not performed. In step (5), 1.0 g of an ethyl cellulose solid sample that has not been modified with a disilane coupling agent and 5.0 g of styrene-butadiene rubber are taken to prepare the composite adhesive, and the subsequent steps are carried out according to Example 1.

[0076] Comparative Example 2

[0077] In Example 1, only KH-570 silane coupling agent was used to modify ethyl cellulose, which was then mixed with styrene-butadiene rubber in a toluene / dibromomethane mixed solvent to prepare a composite binder solution. The prepared composite binder solution was used for wet film formation of sulfide electrolytes.

[0078] That is, compared with Example 1, when preparing the composite adhesive, only 1.5 g of KH-570 silane coupling agent was used for hydrolysis in step (2), without using KH-550 silane coupling agent, and the remaining steps were carried out according to Example 1.

[0079] Comparative Example 3

[0080] In Example 1, only KH-550 silane coupling agent was used to modify ethyl cellulose, which was then mixed with styrene-butadiene rubber in a toluene / dibromomethane mixed solvent to prepare a composite binder solution. The prepared composite binder solution was used for wet film formation of sulfide electrolytes.

[0081] That is, compared with Example 1, when preparing the composite adhesive, only 1.5 g of KH-550 silane coupling agent was used for hydrolysis in step (2), and KH-570 silane coupling agent was not used, and the remaining steps were carried out according to Example 1.

[0082] Comparative Example 4

[0083] Only styrene-butadiene rubber is used as a single binder, and a binder solution is prepared in a mixed solvent of toluene / dibromomethane. The prepared binder solution is used for wet film formation of a sulfide electrolyte.

[0084] That is, compared with Example 1, when preparing the composite adhesive, steps (1) to (4) are eliminated, and in step (5), only 5.0 g of styrene-butadiene rubber is added to a mixed solvent consisting of 90 g of toluene and 10 g of dibromomethane to prepare the adhesive solution, and the remaining steps are carried out according to Example 1.

[0085] Comparative Example 5

[0086] After ethyl cellulose was modified with KH-570 and KH-550 silane coupling agents, it was directly used as a binder without adding styrene-butadiene rubber. The binder solution was prepared in a mixed solvent of toluene / dibromomethane, and a sulfide electrolyte wet film was formed.

[0087] That is, compared with Example 1, when preparing the composite adhesive, in step (5), only 1.0 g of the ethyl cellulose solid sample modified with a disilane coupling agent is taken and added to a mixed solvent consisting of 90 g of toluene and 10 g of dibromomethane to prepare the adhesive solution, without taking styrene-butadiene rubber, and the remaining steps are carried out according to Example 1.

[0088] Comparative Example 6

[0089] Ethyl cellulose was modified with KH-570 and KH-550 silane coupling agents and then compounded with styrene-butadiene rubber in a single solvent, toluene, to prepare a binder solution. Sulfide electrolyte wet film formation was then performed.

[0090] That is, compared with Example 1, when preparing the composite adhesive, the mixed solvent consisting of 90 g of toluene and 10 g of dibromomethane in step (5) is replaced with 100 g of toluene solvent, and the remaining steps are carried out according to Example 1.

[0091] Comparative Example 7

[0092] Ethyl cellulose was modified with KH-570 and KH-550 silane coupling agents and then compounded with styrene-butadiene rubber in a single solvent, dibromomethane, to prepare a binder solution. Sulfide electrolyte wet film formation was then performed.

[0093] That is, compared with Example 1, when preparing the composite adhesive, the mixed solvent consisting of 90 g of toluene and 10 g of dibromomethane in step (5) is replaced with 100 g of dibromomethane solvent, and the remaining steps are carried out according to Example 1.

[0094] Comparative Example 8

[0095] Ethyl cellulose was modified with the epoxy silane coupling agent KH-560 (γ-(2,3-epoxypropoxy)propyltrimethoxysilane). The resulting composite binder solution was prepared with styrene-butadiene rubber in a toluene / dibromomethane mixture. This composite binder solution was then used for wet-process film formation of sulfide electrolytes.

[0096] That is, compared with Example 1, when preparing the composite adhesive, only 1.5 g of KH-560 epoxy silane coupling agent was used for hydrolysis in step (2), and the remaining steps were carried out according to Example 1.

[0097] Comparative Example 9

[0098] Ethyl cellulose was modified with KH-550 and KH-560 silane coupling agents and then mixed with styrene-butadiene rubber in a toluene / dibromomethane mixed solvent to prepare a composite binder solution. The prepared composite binder solution was then used for wet film formation of sulfide electrolytes.

[0099] That is, compared with Example 1, when preparing the composite adhesive, 1.5 g of KH-550 and 1.5 g of KH-560 silane coupling agents were hydrolyzed in step (2), and the remaining steps were carried out according to Example 1.

[0100] Comparative Example 10

[0101] Ethyl cellulose was modified with KH-560 and KH-570 silane coupling agents and then mixed with styrene-butadiene rubber in a toluene / dibromomethane mixed solvent to prepare a composite binder solution. The prepared composite binder solution was then used for wet film formation of sulfide electrolytes.

[0102] That is, compared with Example 1, when preparing the composite adhesive, 1.5 g of KH-560 and 1.5 g of KH-570 silane coupling agents were hydrolyzed in step (2), and the remaining steps were carried out according to Example 1.

[0103] Effect embodiment

[0104] The performance tests of the embodiments and comparative examples are carried out as follows:

[0105] The electrolyte membranes prepared in each embodiment and comparative example were cut into small discs, loaded into a pressure battery mold, and punched under a pressure of 1 ton for 1 min. An AC impedance test was performed at room temperature using an electrochemical workstation with specification model CHI660E. The test results are shown in Table 1.

[0106] Table 1 Electrochemical performance data of sulfide electrolyte membrane

[0107]

[0108] As can be seen from Table 1, the sulfide electrolyte membranes of the examples exhibit lower impedance than the comparative examples, higher ionic conductivity, and superior film-forming properties and surface uniformity and smoothness compared to the comparative examples. This is primarily due to the modification of ethyl cellulose with the silane coupling agents KH-570 and KH-550. The acyloxy groups of the silane coupling agent KH-570 condense with the hydroxyl groups of the ethyl cellulose to form a cross-linked network, while the amino groups of the silane coupling agent KH-550 coordinate with the lithium ions on the sulfide surface. These dual effects significantly enhance interfacial bonding and reduce interfacial impedance. Furthermore, the elasticity of styrene-butadiene rubber and the rigidity of ethyl cellulose synergistically impart high film-forming properties and flexibility to the electrolyte membrane. Furthermore, the mixed solvent system effectively prevents decomposition of the sulfide electrolyte, significantly improving the ionic conductivity of the electrolyte membrane.

[0109] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. Application of a double silane coupling agent modified composite binder in sulfide electrolyte wet film formation, characterized in that: The sulfide electrolyte wet film formation comprises the following steps: A1. Preparing a sulfide electrolyte slurry: ball milling a sulfide solid electrolyte and a double silane coupling agent-modified composite binder to form a uniform sulfide electrolyte slurry; A2. Sulfide electrolyte film formation: The sulfide electrolyte is formed on the copper foil by wet coating and then dried to obtain the sulfide electrolyte membrane; In step A1, (1) The sulfide solid electrolyte includes at least one of Li3PS4 and argyrodite-type electrolyte; the mass ratio of the sulfide solid electrolyte to the double silane coupling agent modified composite binder is 9-99:1; (2) The ball milling time is 1-2 h, the rotation speed is 200-300 rpm, and the ball milling is carried out in a sealed argon atmosphere; the ball milling is wet ball milling, the solvent includes toluene, and the mass ratio of toluene to sulfide solid electrolyte is 0.5-1.5:1; (3) In the sulfide electrolyte slurry, the mass fraction of the composite binder modified by the disilane coupling agent is 1-5%; The bissilane coupling agent modified composite adhesive is prepared by a preparation method comprising the following steps: adding ethyl cellulose modified with a bissilane coupling agent and styrene-butadiene rubber into a mixed solvent of toluene and dibromomethane, and stirring until completely dissolved; The ethyl cellulose modified with a disilane coupling agent is prepared by a preparation method comprising the following steps: S1, hydrolyzing the disilane coupling agent: mixing a methacryloxy silane coupling agent and an amino silane coupling agent, adding the mixture to a solvent, adjusting the pH to carry out a hydrolysis reaction, and obtaining a hydrolyzed silane solution; S2, graft modification reaction: slowly adding the hydrolyzed silane solution prepared in step S1 dropwise to the ethyl cellulose solution to carry out a graft modification reaction to obtain a silane-modified ethyl cellulose solution; S3. Rotary evaporation is performed on the silane-modified ethyl cellulose solution to remove unreacted silane coupling agent by washing, and vacuum drying is performed to obtain the product.

2. The use according to claim 1, characterized in that Step S1 includes at least one of the following technical features:

1. The methacryloxy silane coupling agent includes silane coupling agent KH-570; the amino silane coupling agent includes silane coupling agent KH-550; 2. The mass ratio of the methacryloxy silane coupling agent to the amino silane coupling agent is 1:1-1:3; the total mass fraction of the methacryloxy silane coupling agent and the amino silane coupling agent in the hydrolyzed silane solution is 10-20%; 3. The solvent is a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 9:1-8:2; 4. Adjust the pH to 4-5, and conduct the hydrolysis reaction at a temperature of 20-30°C for 30-60 minutes.

3. The use according to claim 1, characterized in that Step S2 includes at least one of the following technical features:

1. The ethyl cellulose solution is obtained by adding ethyl cellulose to anhydrous ethanol and stirring and dissolving it. The stirring and dissolving temperature is 50-70°C, the time is 5-10 hours, and the rotation speed is 600-800 rpm. The mass fraction of the ethyl cellulose solution is 5-10%; 2. The mass ratio of the hydrolyzed silane solution to the ethyl cellulose solution is 1:3-1:5; 3. The temperature of the graft modification reaction is 60-70°C, and the reaction time is 5-8 hours.

4. The use according to claim 1, characterized in that In step S3, the rotary evaporation temperature is 40-80°C and the time is 1-3 hours; And / or, the detergent used for washing is anhydrous ethanol, and the number of washing times is 3-5 times; And / or, the vacuum drying temperature is 40-80° C., the time is 10-15 h, and the vacuum degree is 0.03-0.08 MPa.

5. The use according to claim 1, characterized in that When preparing the double silane coupling agent modified composite adhesive, The mass ratio of the ethyl cellulose modified with the bissilane coupling agent to the styrene-butadiene rubber is 1:5-1:10; And / or, in the mixed solvent, the mass ratio of toluene to dibromomethane is 9:1-8:2; And / or, the stirring temperature is 20-30° C., the stirring time is 2-6 h, and the stirring speed is 300-700 rpm.

6. The use according to claim 1, characterized in that The solid content of the bissilane coupling agent modified composite adhesive is 4-6%.

7. The use according to claim 1, characterized in that In step A2, the thickness of the sulfide electrolyte membrane is 30-80 μm; The drying is performed by vacuum drying at a temperature of 40-80° C., for 10-15 h, and at a vacuum degree of 0.03-0.08 MPa.

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