An isolated-ion conductor polymer, ternary composite binder solution, high solid content sulfide electrolyte slurry and its wet film forming method and application

Abstract

The application discloses a single-ion conductor polymer, a ternary composite binder solution, a high-solid-content sulfide electrolyte slurry and a wet film forming method and application thereof, and belongs to the technical field of full solid-state lithium batteries. The application solves the key technical problems in the wet film forming of the sulfide electrolyte through an innovative solvent-binder synergistic system, and specifically comprises the following steps: 1. through the synergistic effect of non-polar-weak polar solvents, high solid content slurry is coated with low viscosity while the chemical stability of the sulfide electrolyte is ensured; 2. a poly(styrene sulfonic acid lithium-butyl acrylate) ternary composite binder is designed, lithium ion transmission channels are provided through lithium sulfonate groups, the mechanical strength is enhanced through the benzene ring structure in the butadiene styrene rubber, the long-chain alkane in the polyisobutylene improves the interfacial adhesion, and the three are synergistically combined to balance the mechanical and electrochemical properties of the electrolyte membrane, so that the prepared electrolyte membrane has low porosity, high ionic conductivity and mechanical strength.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of all-solid-state lithium batteries, and relates to a single-ion conductor polymer, a ternary composite binder solution, a high-solid-content sulfide electrolyte slurry, and a wet film forming method and application thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles and energy storage industries, all-solid-state lithium batteries with high energy density and high safety have become a research hotspot. Sulfide solid electrolytes are considered as one of the most promising electrolyte systems due to their extremely high room-temperature ionic conductivity and good mechanical processing performance. However, there are the following key challenges in the process of preparing sulfide electrolyte films by wet method: (1) solvent selection dilemma: sulfide electrolytes are extremely sensitive to polar solvents, and traditional polar solvents (such as NMP, DMF) will react with electrolytes to produce active sulfur species (such as H2S), which seriously affects the stability of the electrolyte; and the dispersion ability of non-polar solvents is insufficient, and it is difficult to realize uniform and stable high solid content slurry; (2) defects in the binder system: in the existing technology, the solubility of a single binder (such as PVDF, PTFE) in non-polar / weakly polar solvents is limited, and it cannot meet the multiple requirements of electrolyte films: ionic conductivity: conventional binders lack lithium ion conduction groups, resulting in increased film body impedance; mechanical properties: a single polymer is difficult to balance flexibility (anti-cracking) and strength (anti-puncture); film forming property: the adhesion of the binder is insufficient at high solid content, resulting in peeling of the film and the electrode / current collector interface; (3) process-performance contradiction: the strong interaction between small particle size sulfide electrolyte particles (<5 μm) and solvents leads to a sharp increase in the viscosity of the slurry when the solid content exceeds 40%, and the following technical problems occur: coating process is limited: high viscosity slurry is difficult to uniformly coat, and after film forming, cracks, uneven thickness and other problems easily occur; film structure defects: low solid content (<40%) leads to large electrolyte particle spacing, high porosity of the film (>20%), and discontinuous ion transport path; performance degradation: high porosity makes the mechanical strength of the electrolyte film insufficient, and the interface contact impedance increases, which seriously affects the energy density and cycle life of the full battery.

[0003] In the prior art, attempts are made to reduce the viscosity of the slurry by adding plasticizers, but this introduces electrochemically unstable organic matter, which sacrifices electrochemical stability, and has always failed to break through the bottleneck of "high solid content-low viscosity-high stability" synergistic optimization. Therefore, developing a solvent-binder synergistic system that adapts to the characteristics of sulfide electrolytes to realize stable coating and dense film forming of high solid content (>60%) slurry has become a key technical breakthrough for promoting the industrialization of all-solid-state batteries. SUMMARY

[0004] To solve the above technical problems, the present application aims to provide a single-ion conductor polymer, a ternary composite binder solution, a high-solid-content sulfide electrolyte slurry, a wet film forming method thereof and application. The present application solves the problems of solvent sensitivity, high viscosity of the slurry and insufficient film performance in the wet film forming of the sulfide electrolyte by an innovative solvent-binder synergistic system. Specifically, (1) in the solvent system, p-xylene nonpolar solvent is used as the main solvent, and isoamyl isoamylate weak polar solvent is used as the diluent. Through the synergistic effect of nonpolar-weak polar solvents, the decomposition of the sulfide electrolyte is avoided, and the viscosity of the high-solid-content slurry is significantly reduced, so that it has good coating performance; (2) in the binder system, a ternary composite system of poly (lithium styrene sulfonate-butyl acrylate), butadiene rubber and polyisobutylene is designed. The poly (lithium styrene sulfonate-butyl acrylate) provides lithium ion transmission channels, the butadiene rubber enhances the mechanical strength, and the polyisobutylene improves the interfacial adhesion, so that the balance of the mechanical and electrochemical performance of the electrolyte film is achieved through the synergistic effect of the three. Through the synergistic optimization of the above-mentioned solvent and binder, the stable coating and film forming of the sulfide electrolyte slurry under high solid content are realized. The process of the present application is compatible with the existing production line, and the stability of the slurry is improved, which provides a reliable solution for the industrialization of the sulfide full solid-state battery.

[0005] The object of the present application can be achieved by the following scheme:

[0006] In a first aspect, the present application provides a preparation method of a single-ion conductor polymer poly (lithium styrene sulfonate-butyl acrylate), comprising the following steps:

[0007] Step 1: mixing 4-sodium styrene sulfonate and butyl acrylate, adding an initiator, and performing a free radical copolymerization reaction in a solvent to obtain a poly (sodium styrene sulfonate-butyl acrylate) precursor;

[0008] Step 2: dissolving the precursor and adding a LiOH solution for ion exchange treatment to obtain poly (lithium styrene sulfonate-butyl acrylate) (PSSLi-BA).

[0009] As an embodiment of the present application, in step 1, the molar ratio of 4-sodium styrene sulfonate to butyl acrylate is 5:5-7:3.

[0010] As an embodiment of the present application, in step 1, the initiator includes azobisisobutyronitrile; and the addition concentration of the initiator is 0.5-1.5 mol%. In some implementations, the solvent includes toluene.

[0011] In one embodiment of the present invention, in step 1, the temperature of the free radical copolymerization reaction is 50~70°C, and the time is 10~12 hours. In some embodiments, the free radical copolymerization reaction is carried out under an inert atmosphere; after the free radical copolymerization reaction, excess ethanol is added for precipitation, and after filtration and vacuum drying, the poly(sodium styrene sulfonate-butyl acrylate) precursor is obtained.

[0012] In one embodiment of the present invention, in step 2, the concentration of the LiOH solution is 1~2M. In some embodiments, the solvent used for dissolution includes methanol.

[0013] In one embodiment of the present invention, in step 2, the ion exchange treatment time is 6-8 hours. The ion exchange treatment realizes the lithiation process.

[0014] As one embodiment of the present invention, step 2 further includes: after ion exchange treatment, performing dialysis and rotary evaporation to remove residual LiOH and solvent.

[0015] Secondly, the present invention provides a single-ion conductor polymer, poly(lithium styrene sulfonate-butyl acrylate), obtained by the preparation method described above.

[0016] Thirdly, the present invention provides a method for preparing a ternary composite adhesive solution containing the aforementioned poly(lithium styrene sulfonate-butyl acrylate), comprising: mixing poly(lithium styrene sulfonate-butyl acrylate), styrene-butadiene rubber and polyisobutylene, stirring and dissolving to obtain the ternary composite adhesive solution.

[0017] In one embodiment of the present invention, the mass ratio of poly(lithium styrene sulfonate-butyl acrylate), styrene-butadiene rubber, and polyisobutylene is 3~5:2~4:2~4; the solvent used for dissolution includes p-xylene, and the stirring time is 18~24 hours. In some embodiments, the stirring is magnetic stirring at room temperature.

[0018] As one embodiment of the present invention, the mass concentration of the ternary composite adhesive solution is 3~6 wt.%.

[0019] Fourthly, the present invention provides a ternary composite adhesive solution obtained by the preparation method described above.

[0020] Fifthly, the present invention provides a method for wet film formation of high solids content sulfide electrolyte slurry, comprising the following steps:

[0021] S1. Under a sealed inert atmosphere, the sulfide solid electrolyte is mixed with the ternary composite binder solution, a non-polar solvent and a diluent are added, and the mixture is ball-milled to obtain a high solid content sulfide electrolyte slurry.

[0022] S2. Using a wet coating method, the sulfide electrolyte slurry is coated onto the substrate, and after vacuum drying, a high solids content sulfide electrolyte membrane is obtained.

[0023] As one embodiment of the present invention, in step S1, the sulfide solid electrolyte includes Li6PS5Cl (D50=7μm).

[0024] In one embodiment of the present invention, in step S1, the mass ratio of the sulfide solid electrolyte to the ternary composite binder solution is 2-4:1; the mass ratio of the diluent to the non-polar solvent is 1:1-5, the diluent includes isoamyl isovalerate, and the non-polar solvent includes p-xylene; the solid content of the sulfide electrolyte slurry is 60-70%.

[0025] In one embodiment of the present invention, in step S1, the ball mill rotates at a speed of 200-400 rpm for 1-3 hours. In some embodiments, the inert atmosphere includes argon.

[0026] In one embodiment of the present invention, in step S2, the substrate includes copper foil; the vacuum drying is performed at a vacuum degree of 0.03-0.08 MPa, a temperature of 40-80℃, and a time of 10-15 h.

[0027] In one embodiment of the present invention, in step S2, the thickness of the high solid content sulfide electrolyte membrane is 30~100μm.

[0028] In a sixth aspect, the present invention provides a high solids content sulfide electrolyte membrane obtained by the preparation method described above.

[0029] In a seventh aspect, the present invention also provides an application of the high solid content sulfide electrolyte membrane in a sulfide all-solid-state battery, wherein the positive electrode of the sulfide all-solid-state battery is an NCM ternary active material, the negative electrode is micron-sized silicon, and the electrolyte layer is the high solid content sulfide electrolyte membrane.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. In terms of solvent system innovation: This invention utilizes the synergistic effect of non-polar solvent (paraxylene) and weakly polar solvent (isoamyl isovalerate) to successfully achieve low-viscosity stable coating of slurry with a high solid content of 60-70% while ensuring the chemical stability of the sulfide electrolyte, thus solving the technical contradiction of difficulty in balancing high solid content and low viscosity in traditional processes.

[0032] 2. Breakthrough in Adhesive System: This invention first prepares a novel polymer, poly(lithium styrene sulfonate-butyl acrylate), and then blends it with styrene-butadiene rubber and polyisobutylene to obtain a ternary composite adhesive. This invention achieves synergistic optimization of multiple properties through the ternary composite adhesive (poly(lithium styrene sulfonate-butyl acrylate) / styrene-butadiene rubber / polyisobutylene). Specifically, the lithium styrene sulfonate groups in poly(lithium styrene sulfonate-butyl acrylate) provide efficient lithium-ion transport channels, improving the ionic conductivity of the electrolyte membrane (4.83 mS / cm); the benzene ring groups in styrene-butadiene rubber impart excellent mechanical properties, improving the tensile strength of the membrane (0.6 MPa); and the long-chain alkanes in polyisobutylene significantly improve interfacial adhesion (peel strength > 2.2 N / cm). These three components synergistically achieve a balance between the mechanical and electrochemical properties of the electrolyte membrane. Traditional lithium salts are inorganic substances that can only conduct lithium but cannot act as binders, and their addition will lead to a deterioration in film-forming performance. However, the poly(lithium styrene sulfonate-butyl acrylate) in this invention is a high-molecular-weight organic polymer that can not only conduct lithium but also act as a binder. It forms a ternary composite binder with styrene-butadiene rubber and polyisobutylene, enabling the electrolyte membrane to have both high ionic conductivity and excellent film-forming performance.

[0033] 3. Improved film-forming performance: The electrolyte membrane prepared by this invention has ultra-low porosity and high density, increases the number of electrolyte particles per unit volume, significantly reduces the interfacial impedance of the membrane, and controls the thickness uniformity deviation within ±3μm.

[0034] 4. Process compatibility: The method of this invention is fully compatible with existing coating equipment production lines, and the slurry stability reaches more than 36 hours, meeting the requirements of industrial production. This invention achieves a comprehensive improvement in the performance of sulfide electrolyte membranes through a combination of material system innovation and process optimization, providing a reliable solution for the industrialization of sulfide all-solid-state batteries. It has significant industrial application value for the energy density and long-cycle stability of sulfide all-solid-state batteries. Attached Figure Description

[0035] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0036] Figure 1 A flowchart of wet film formation of high solids content sulfide electrolyte slurry provided in an embodiment of the present invention;

[0037] Figure 2 This is a SEM image of the electrolyte membrane prepared in Example 2 of the present invention;

[0038] Figure 3 This is a SEM image of the electrolyte membrane prepared in Comparative Example 5 of the present invention;

[0039] Figure 4NMR of poly(lithium styrene sulfonate-butyl acrylate) prepared in Example 1 of this invention 1 H spectrum;

[0040] Figure 5 NMR of poly(lithium styrene sulfonate-butyl acrylate) prepared in Example 1 of this invention 13 C-spectrum. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, providing detailed implementation methods and specific operating procedures, which will help those skilled in the art to further understand the present invention. It should be noted that the scope of protection of the present invention is not limited to the following embodiments; any adjustments and improvements made under the concept of the present invention are all within the scope of protection of the present invention.

[0042] The preparation process of the high solids content sulfide electrolyte slurry and its wet film formation according to the present invention is as follows: Figure 1 .

[0043] The sodium 4-styrene sulfonate used in the examples and comparative examples is sodium p-styrene sulfonate, CAS: 27457-28-9.

[0044] Example 1

[0045] This embodiment provides a method for preparing a single-ion conductor polymer, poly(lithium styrene sulfonate-butyl acrylate), the steps of which are as follows:

[0046] (1) Free radical copolymerization: Under nitrogen protection, sodium 4-styrene sulfonate (14.0 g, 0.07 mol) and butyl acrylate (5.7 g, 0.03 mol) were added to a three-necked flask containing toluene (200 mL) at a molar ratio of 7:3. Azobisisobutyronitrile (0.16 g, 1 mol% of total monomer) was added as an initiator. The reaction system was heated to 70 °C and reacted for 12 hours with stirring. After the reaction was completed, the mixture was poured into excess ethanol to precipitate, and the white solid product was collected by filtration and vacuum dried for 24 hours to obtain the poly(sodium styrene sulfonate-butyl acrylate) precursor;

[0047] (2) Lithification treatment: The above copolymer precursor (15.0 g) was dissolved in methanol (300 mL), and 1 M LiOH methanol solution (200 mL) was added. The mixture was stirred and refluxed at 60 °C for 6 hours to carry out the ion exchange reaction. After the reaction was completed, the solution was cooled to room temperature;

[0048] (3) Purification: The reaction solution was placed in a dialysis bag (molecular weight cutoff 3500 Da) and dialyzed in deionized water for 48 hours, with the water changed every 8 hours to completely remove residual LiOH. After dialysis, the solution was concentrated by rotary evaporation to remove methanol, finally yielding the product poly(lithium styrene sulfonate-butyl acrylate). The NMR of this poly(lithium styrene sulfonate-butyl acrylate) was... 1 H-spectrum and NMR 13 The C-spectrums are as follows: Figure 4 and Figure 5 As shown.

[0049] Example 2

[0050] This embodiment provides a high solids content sulfide electrolyte slurry and its wet film formation preparation method, the steps of which are as follows:

[0051] (1) Preparation of ternary composite adhesive solution: 4.0g of poly(lithium styrene sulfonate-butyl acrylate), 3.0g of styrene-butadiene rubber, and 3.0g of polyisobutylene in a mass ratio of 4:3:3 were added to 190g of p-xylene solvent. After each component was added, the mixture was stirred at 500rpm for 30 minutes. After all the materials were added, the stirring speed was increased to 1000rpm and stirred continuously for 20 hours at room temperature to obtain a uniform and transparent ternary composite adhesive solution with a mass fraction of 5%.

[0052] (2) Preparation of high solids content electrolyte slurry: In an argon glove box (H2O<0.1ppm, O2<0.1ppm), Li6PS5Cl powder (60g) and ternary composite binder solution (20g) were added to a 500mL zirconia ball mill jar, followed by p-xylene (15g) and isoamyl isovalerate (5g). Zirconia grinding balls (ball-to-material ratio 10:1) were then loaded, sealed, and transferred to a planetary ball mill. The slurry was ball-milled at 250rpm for 1.5 hours to obtain a uniform electrolyte slurry with a solids content of 61%.

[0053] (3) Wet coating and drying: The operation was carried out in a glove box filled with argon gas. The electrolyte slurry was coated on the copper foil substrate using a doctor blade coater with a thickness of about 100 μm. Then it was directly air-dried for 2 h. After that, it was dried in a vacuum oven at a temperature of 50℃ and a vacuum degree of 0.05 MPa for 12 h. Finally, a dense electrolyte membrane with a thickness of 80±2 μm was obtained.

[0054] Example 3

[0055] This embodiment provides a high solids content sulfide electrolyte slurry and its wet film formation preparation method, the steps of which are as follows:

[0056] (1) Preparation of ternary composite adhesive solution: 3.5g of poly(lithium styrene sulfonate-butyl acrylate), 3.0g of styrene-butadiene rubber, and 2.5g of polyisobutylene in a mass ratio of 3.5:3:2.5 were added to 210g of p-xylene solvent. After each component was added, the mixture was stirred at 500rpm for 30 minutes. After all the materials were added, the stirring speed was increased to 1000rpm and stirred continuously for 20 hours at room temperature to obtain a uniform and transparent ternary composite adhesive solution with a mass fraction of 4.1%.

[0057] (2) Preparation of high solids electrolyte slurry: In an argon glove box (H2O<0.1ppm, O2<0.1ppm), Li6PS5Cl powder (70g) and ternary composite binder solution (20g) were added to a 500mL zirconia ball mill jar, followed by p-xylene (12g) and isoamyl isovalerate (3g). Zirconia grinding balls (ball-to-material ratio 10:1) were then loaded, sealed, and transferred to a planetary ball mill. The slurry was ball-milled at 300rpm for 2 hours to obtain a uniform electrolyte slurry with a solids content of 67.4%.

[0058] (3) Wet coating and drying: The operation was carried out in a glove box filled with argon gas. The electrolyte slurry was coated on the copper foil substrate using a doctor blade coater with a thickness of about 100 μm. Then it was directly air-dried for 2 h. After that, it was dried in a vacuum oven at a temperature of 55℃ and a vacuum degree of 0.06 MPa for 14 h. Finally, a dense electrolyte membrane with a thickness of 82±2 μm was obtained.

[0059] Comparative Example 1

[0060] In step 1 of Example 2, the addition of poly(lithium styrene sulfonate-butyl acrylate) was omitted, and only styrene-butadiene rubber and polyisobutylene were used in a 1:1 mass ratio to prepare a 5% binary composite adhesive solution, with other parameters remaining unchanged. The impedance of the final electrolyte membrane was 6.28Ω, which was significantly higher than the impedance of 2.46Ω of the electrolyte membrane in Example 2. This is because the lack of lithium sulfonate groups in the adhesive, which can conduct lithium ions, led to a decrease in its ionic conductivity and a weakening of its ion conduction ability.

[0061] Comparative Example 2

[0062] In step 1 of Example 2, the addition of styrene-butadiene rubber was omitted, and only poly(lithium styrene sulfonate-butyl acrylate) and polyisobutylene were used in a mass ratio of 4:3 to prepare a binary composite adhesive solution with a mass fraction of 5%, while the other parameters remained unchanged. The tensile strength of the final electrolyte membrane was 0.1 MPa, which was significantly lower than the 0.5 MPa of the electrolyte membrane in Example 2. This is because the adhesive lacks the rigid structure of the benzene ring in styrene-butadiene rubber to provide high mechanical properties.

[0063] Comparative Example 3

[0064] In step 1 of Example 2, the addition of polyisobutylene was omitted, and only poly(lithium styrene sulfonate-butyl acrylate) and styrene-butadiene rubber were used in a mass ratio of 4:3 to prepare a binary composite adhesive solution with a mass fraction of 5%, while the other parameters remained unchanged. The peel strength of the final electrolyte membrane was 1.5 MPa, which was significantly lower than the 2.1 MPa of the electrolyte membrane in Example 2. This was because the adhesive lacked polyisobutylene, which has better adhesion properties, making it easier for the electrolyte membrane to detach from the copper foil.

[0065] Comparative Example 4

[0066] In step 2 of Example 2, the addition of isoamyl isovalerate was removed, and only p-xylene was added to prepare an electrolyte slurry with a solid content of 61%, while the other parameters remained unchanged. Since isoamyl isovalerate was not added, the electrolyte slurry was too viscous and lacked fluidity at the high solid content of 61%, making it impossible to coat and form a film.

[0067] Comparative Example 5

[0068] In step 2 of Example 2, the addition of isoamyl isovalerate was omitted, and only p-xylene was added to prepare an electrolyte slurry with a solid content of 41%, while other parameters remained unchanged. Because isoamyl isovalerate was not added, the electrolyte slurry at 41% solid content was better than that at 61% solid content; the slurry could flow and be coated normally, but the surface of the film formed was observed to be relatively rough and uneven. Figure 3 As shown, this is due to the electrolyte particles not being completely wetted and coated by the solvent; the electrolyte membrane in this comparative example has a porosity of 17% and a compaction density of 1.7 g / cm³. 3 The electrolyte membrane in Example 2 had a porosity of 10% and a compaction density of 2.7 g / cm³. 3 Furthermore, the surface smoothness of the electrolyte membrane prepared in Example 2 is significantly higher than that in Comparative Example 5, such as... Figure 2 As shown, the porosity of the electrolyte membrane in this comparative example is significantly higher, and the compaction density is very low. This is because the lower the solid content of the electrolyte, the fewer electrolyte particles per unit volume, which leads to increased porosity and decreased compaction density.

[0069] Comparative Example 6

[0070] In step 2 of Example 2, the addition of isoamyl isovalerate was omitted, and only p-xylene was added to prepare an electrolyte slurry with a solid content of 40%, while other parameters remained unchanged. At this solid content, the electrolyte slurry had moderate viscosity and better film-forming properties than at a solid content of 41%. The film surface was relatively smooth, without any uneven dispersion or particle feel. This indicates that without using isoamyl isovalerate as a diluent, the maximum solid content of the electrolyte slurry can only reach 40%. The porosity of the electrolyte membrane in this comparative example was 18%, and the compaction density was 1.8 g / cm³. 3 The tensile strength was 0.1 MPa, the porosity of the electrolyte membrane in Example 2 was 10%, and the compaction density was 2.7 g / cm³. 3 The tensile strength is 0.5 MPa. The porosity of the electrolyte membrane in this comparison is significantly larger, and the compaction density and tensile strength are also very low. This is because the lower the solid content of the electrolyte, the fewer electrolyte particles per unit volume, and the larger the porosity, which is not conducive to ion transport.

[0071] Comparative Example 7

[0072] In step 2 of Example 2, the addition of p-xylene was omitted, and only isoamyl isovalerate was added to prepare an electrolyte slurry with a solid content of 61%, while the other parameters remained unchanged. The electrolyte slurry was in a normal state and could be coated to form a film. The ionic conductivity of the electrolyte membrane in this comparative example was 1.10 mS / cm, which was significantly lower than the ionic conductivity of 3.88 mS / cm of the membrane in Example 2. This is because isoamyl isovalerate is a weakly polar solvent, and its polarity is stronger than that of p-xylene. Excessive use of isoamyl isovalerate will affect the electrolyte and, to some extent, damage the electrolyte structure, leading to a decrease in ionic conductivity.

[0073] Comparative Example 8

[0074] In step 1 of Example 2, poly(lithium styrene sulfonate-butyl acrylate) was replaced with lithium trifluoromethanesulfonate to prepare a 5% (w / w) binary composite adhesive solution, with other parameters remaining unchanged. In this comparative example, due to the addition of lithium salt, the inorganic particles reduced the viscosity of the slurry and resulted in poor film formation. The final tested ionic conductivity was 1.19 mS / cm, peel strength was 1.2 N / cm, and tensile strength was 0.2 MPa, all of which were significantly lower than the corresponding parameters in Example 2. This is because the addition of lithium trifluoromethanesulfonate disrupts the viscosity and continuity of the film, leading to a decrease in its ionic conductivity and mechanical properties.

[0075] Performance testing

[0076] The slurry state and coating film state of the examples and comparative examples were compared, and the results are shown in Table 1.

[0077] Table 1

[0078]

[0079] The examples and comparative examples were tested using the following methods:

[0080] The ionic conductivity of the electrolyte membrane was tested: The prepared electrolyte membrane was cut into small discs and then loaded into a pressure battery mold. It was pressed under a pressure of 1 ton and held for 1 minute. The AC impedance was tested using an electrochemical workstation of model CHI660E at room temperature and in a normal atmospheric atmosphere. The ionic conductivity was calculated and the results are shown in Table 2.

[0081] Table 2

[0082]

[0083] Porosity testing of the electrolyte membrane: A high-performance fully automated mercury porosimeter, model MicromeriticsAutoPore V 9620, was used. Pressures ranging from approximately 0.6 to 50 PSI were applied in the low-pressure station (LP) and from 20 to 60,000 PSI in the high-pressure station (HP). A glass cone probe was used as the sample container to apply pressure to the sample, which was 1 cm x 1 cm in size. The porosity of the electrolyte membrane was calculated based on the volume of mercury entering the pores.

[0084] Mechanical property testing of electrolyte membranes:

[0085] (1) 180° Peel Test: A universal tensile testing machine was used. The sample size was 1cm*10cm. A flat, thin steel plate was taken. A strip of double-sided tape was first applied to the center of the steel plate and smoothed out to ensure that the double-sided tape was tightly adhered to the center of the steel plate. The double-sided tape was peeled off, and the electrode was attached to the tape. It was necessary to ensure that the electrode and the tape were properly matched and adhered. The steel plate with the attached electrode was inserted into the lower clamp of the tensile testing machine and fixed vertically. The electrode without tape was inserted into the upper clamp and fixed so that the electrode attached to the tape was at a 180° angle to the electrode fixed in the upper clamp. After the test sample was fixed, the peel speed was 0.2mm / s, and the test began.

[0086] (2) Tensile strength test: A universal tensile testing machine was used. The sample size was 1cm*10cm. The sample was fixed in the upper and lower clamps of the tensile testing machine. The sample was stretched at a uniform speed of 0.2mm / s. The maximum tensile force value when the sample broke was recorded.

[0087] The test results of the porosity, peel strength, tensile strength and compaction density of the electrolyte membrane are shown in Table 3.

[0088] Table 3

[0089]

[0090] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a ternary composite adhesive solution comprising poly(lithium styrene sulfonate-butyl acrylate), characterized in that, The preparation method includes: mixing poly(lithium styrene sulfonate-butyl acrylate), styrene-butadiene rubber and polyisobutylene, stirring and dissolving to obtain a ternary composite adhesive solution; The preparation method of the poly(lithium styrene sulfonate-butyl acrylate) includes the following steps: Step 1: Sodium 4-styrene sulfonate and butyl acrylate are mixed, an initiator is added, and a free radical copolymerization reaction is carried out in a solvent to obtain a poly(sodium styrene sulfonate-butyl acrylate) precursor; Step 2: Dissolve the precursor and add LiOH solution for ion exchange treatment to obtain poly(lithium styrene sulfonate-butyl acrylate).

2. The preparation method according to claim 1, characterized in that, It also includes at least one of the following technical features: The mass ratio of poly(lithium styrene sulfonate-butyl acrylate), styrene-butadiene rubber, and polyisobutylene is 3~5:2~4:2~4; the solvent used for dissolution includes p-xylene, and the stirring time is 18~24 hours; The mass concentration of the ternary composite adhesive solution is 3~6 wt.%; The molar ratio of sodium 4-styrenesulfonate to butyl acrylate is 5:5 to 7:3; The initiator comprises azobisisobutyronitrile; the concentration of the initiator added is 0.5-1.5 mol%. The free radical copolymerization reaction is carried out at a temperature of 50~70℃ for 10~12 hours. The concentration of the LiOH solution is 1~2M; The ion exchange treatment takes 6 to 8 hours.

3. A ternary composite adhesive solution obtained by the preparation method as described in claim 1 or 2.

4. A method for wet film formation of high solids content sulfide electrolyte slurry, characterized in that, Includes the following steps: S1. Under a sealed inert atmosphere, the sulfide solid electrolyte is mixed with the ternary composite binder solution described in claim 3, a non-polar solvent and a diluent are added, and the mixture is ball-milled to obtain a high solid content sulfide electrolyte slurry. S2. Using a wet coating method, the sulfide electrolyte slurry is coated onto the substrate, and after vacuum drying, a high solids content sulfide electrolyte membrane is obtained.

5. The method according to claim 4, characterized in that, It also includes at least one of the following technical features: In step S1, The sulfide solid electrolyte includes Li6PS5Cl; The mass ratio of the sulfide solid electrolyte to the ternary composite binder solution is 2-4:1; the mass ratio of the diluent to the non-polar solvent is 1:1-5, wherein the diluent includes isoamyl isovalerate and the non-polar solvent includes p-xylene; and the solid content of the sulfide electrolyte slurry is 60-70%. The ball mill operates at a speed of 200-400 rpm for 1-3 hours. In step S2, The substrate includes copper foil; the vacuum drying process is performed at a vacuum level of 0.03-0.08 MPa, a temperature of 40-80℃, and a time of 10-15 h. The thickness of the high solids content sulfide electrolyte membrane is 30~100μm.

6. A high solids content sulfide electrolyte membrane prepared by the method described in claim 4 or 5.

7. The application of the high solids content sulfide electrolyte membrane as described in claim 6 in a sulfide all-solid-state battery, characterized in that, The positive electrode of the sulfide all-solid-state battery is an NCM ternary active material, the negative electrode is micron-sized silicon, and the electrolyte layer is the high-solid-content sulfide electrolyte membrane.

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