Electrolyte thin film and preparation method therefor

Abstract

An electrolyte thin film and a preparation method therefor. The electrolyte thin film comprises a sulfide solid-state electrolyte and a binder, the molecular weight of the binder being 0.50-7 million, and the porosity of the electrolyte thin film being less than or equal to 10%.

Description

An electrolyte thin film and its preparation method Technical Field

[0001] This invention relates to the field of solid electrolyte technology, and in particular to an electrolyte thin film and its preparation method. Background Technology

[0002] With the rapid development of electric vehicles and portable electronic products, lithium batteries with high energy density have become one of the research hotspots in the fields of power batteries and energy storage.

[0003] There are still some problems with the electrolyte film in existing lithium batteries. For example, the high porosity of the electrolyte film leads to a decrease in mechanical strength and affects the stability of the electrolyte film. Summary of the Invention

[0004] The purpose of this invention is to provide an electrolyte film and its preparation method, which reduces the porosity of the electrolyte film, increases its mechanical strength, and improves the stability of its ionic conductivity.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an electrolyte film comprising: a sulfide solid electrolyte and a binder, wherein the molecular weight of the binder is between 500,000 and 7,000,000.

[0006] The porosity of the electrolyte membrane is less than or equal to 10%.

[0007] The beneficial effects of the electrolyte film provided by the present invention are as follows: by using a binder with a molecular weight of 50-7 million to prepare the electrolyte film and making its porosity less than or equal to 10%, not only is the mechanical strength of the electrolyte film increased, but the stability of ionic conductivity is also improved.

[0008] In some embodiments, the tensile strength of the electrolyte film is between 0.3 and 1 MPa, and the bending radius of the electrolyte film is less than or equal to 5 mm.

[0009] In some embodiments, the elongation at break of the electrolyte film is between 0.5% and 1.5%.

[0010] In some embodiments, the sulfide solid electrolyte has a weight percentage of 94-96 wt% and the binder has a weight percentage of 4-6 wt%.

[0011] In some embodiments, the ionic conductivity of the electrolyte film is greater than or equal to 1.5 mS / cm, and the electronic conductivity of the electrolyte film is in the range of 2.4 × 10⁻⁶ mS / cm. -10 -6.1*10 -10 S / cm.

[0012] In some embodiments, the thickness of the electrolyte film is less than or equal to 65 μm.

[0013] In some embodiments, the adhesive comprises at least one of thermoplastic elastomer, styrene-butadiene rubber, polyvinylidene fluoride, thermoplastic styrene-butadiene rubber, synthetic rubber, hydrogenated nitrile rubber, polyethylene-vinyl acetate, polymethyl methacrylate, polyacrylic acid, polyisobutylene, cis-butadiene rubber, and nitrile rubber.

[0014] In a second aspect, embodiments of the present invention provide a method for preparing an electrolyte thin film, the method comprising:

[0015] The solution containing the binder is stirred and mixed with a sulfide solid electrolyte to obtain a slurry;

[0016] The slurry is coated onto a release film, and the release film is then heated to form an electrolyte film on the release film.

[0017] The electrolyte film is separated from the release film and then subjected to heating and pressurization treatment.

[0018] The beneficial effects of the method for preparing the electrolyte film provided by the present invention are as follows: after coating the slurry onto the release film, heat-treating it, and after separating the electrolyte film from the release film, heating and pressurizing the electrolyte film to make the porosity of the electrolyte film less than or equal to 10%, which not only increases the mechanical strength of the electrolyte film, but also improves the stability of the ionic conductivity.

[0019] In some embodiments, transferring the release film to a heating device for heat treatment includes:

[0020] The release film is transferred to a vacuum transition chamber at 50-100°C and heated for 2-12 hours;

[0021] The release film is transferred to a heating table at 50-100°C and heated for 2-12 hours.

[0022] In some embodiments, separating the electrolyte film from the release film includes:

[0023] Apply a pressure of 30-80 MPa to the electrolyte film until the electrolyte film separates from the release film.

[0024] In some embodiments, the heating and pressurizing treatment of the electrolyte membrane includes:

[0025] The electrolyte membrane is placed in an environment of 50-100°C and subjected to a pressure of 30-80 MPa for 2-12 hours.

[0026] In some embodiments, the sulfide solid electrolyte is in the form of a powder, and the D50 of the sulfide solid electrolyte is 3-15 μm. Attached Figure Description

[0027] Figure 1 is a flowchart of the preparation method of the electrolyte film according to an embodiment of the present invention. Embodiments of the present invention

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Unless otherwise specified, the term "connection" as used herein can refer to a direct connection or an indirect connection, i.e., a connection through an intermediate object.

[0029] Furthermore, it should be understood that the orientations or positional relationships indicated by terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" in this document are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "first" and "second" in this document are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0030] To address the problems existing in the prior art, embodiments of the present invention provide an electrolyte film, a sulfide solid electrolyte, and a binder, wherein the molecular weight of the binder is between 500,000 and 7 million, and the porosity of the electrolyte film is less than or equal to 10%.

[0031] In this embodiment, the electrolyte film prepared by using a binder with a molecular weight of 50-7 million and by heating and pressurizing has a porosity of less than or equal to 10%, which not only increases the mechanical strength of the electrolyte film, but also improves the stability of the ionic conductivity.

[0032] In some specific embodiments, the molecular weight of the binder can be 500,000, 1,000,000, 1,500,000, 1,800,000, 2,000,000, 2,300,000, 2,500,000, 2,800,000, 3,000,000, 4,000,000, 5,000,000, 6,000,000, or 7,000,000. The porosity of the electrolyte film can be 1%, 3%, 4%, 5%, 9%, or 10%, etc. The binder includes at least one of thermoplastic elastomers, styrene-butadiene rubber, polyvinylidene fluoride, thermoplastic styrene-butadiene rubber, synthetic rubber, hydrogenated nitrile rubber, polyethylene-vinyl acetate, polymethyl methacrylate, polyacrylic acid, polyisobutylene, cis-butadiene rubber, and nitrile rubber. More preferably, the binder is polyisobutylene, whose mechanism of action is based on physical adsorption theory. Since the interaction between polyisobutylene and the sulfide electrolyte is physical adsorption without reaction, when the binder is polyisobutylene, the membrane has higher ionic conductivity and faster lithium-ion transport.

[0033] It is understandable that improving the mechanical strength of the electrolyte membrane also facilitates the continuous coating of the electrolyte film, accelerates the large-scale production process of the electrolyte film, and improves the energy density and safety of the battery.

[0034] In some embodiments, the tensile strength of the electrolyte film is between 0.3 and 1 MPa, and the bending radius of the electrolyte film is less than or equal to 5 mm.

[0035] In some specific embodiments, the tensile strength of the electrolyte film is 0.3 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, or 1 MPa, etc. The bending radius of the electrolyte film is 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, etc.

[0036] In some embodiments, the sulfide solid electrolyte has a weight percentage of 94-96 wt% and the binder has a weight percentage of 4-6 wt%.

[0037] In some specific embodiments, when the weight percentage of the sulfide solid electrolyte is 94 wt%, the weight percentage of the binder is 6 wt%. When the weight percentage of the sulfide solid electrolyte is 95 wt%, the weight percentage of the binder is 5 wt%. When the weight percentage of the sulfide solid electrolyte is 96 wt%, the weight percentage of the binder is 4 wt%.

[0038] In some embodiments, the ionic conductivity of the electrolyte film is greater than or equal to 1.5 mS / cm, and the electronic conductivity of the electrolyte film is 2.4*10-10-6.1*10-10 S / cm.

[0039] In some embodiments, the thickness of the electrolyte film is less than or equal to 65 μm.

[0040] In another embodiment of the present invention, a method for preparing an electrolyte thin film is provided, for preparing the electrolyte thin film of the above embodiment, the method comprising:

[0041] S101: The solution containing the binder is stirred and mixed with the sulfide solid electrolyte to obtain a slurry.

[0042] Prior to this step, a solution containing the binder is prepared. Specifically, the binder is mixed with an ester or benzene solvent and heated at 80-90°C for 24 hours to ensure that the binder and the solvent are fully dissolved. Finally, the solution is allowed to stand to defoam and obtain the solution containing the binder.

[0043] In this step, specifically, the sulfide solid electrolyte and the solution containing the binder are mixed in a degassing machine in a certain proportion, then filtered and defoamed to finally obtain the slurry.

[0044] The degassing machine operates at a speed of 1200-3200 rpm, and the stirring time is 10-60 min. The sulfide solid electrolyte is in powder form, and its D50 is 3-15 μm.

[0045] S102: The slurry is coated onto a release film, and the release film is heated to form an electrolyte film on the release film.

[0046] In this step, a transfer coater or a flatbed coater is used to uniformly coat the release film with the slurry. The release film is then transferred to a vacuum transition chamber or a heating table for heating and drying. The heating temperature of the vacuum transition chamber or the heating table is controlled at 50-100°C, and the heating time is 2-12 hours.

[0047] S103: Separate the electrolyte film from the release film and subject the electrolyte film to heating and pressurization treatment.

[0048] In this step, a roller press is used to apply a pressure of 30-80 MPa to the electrolyte film until the electrolyte film separates from the release film. Then, the electrolyte film is placed on a hot press, which provides the electrolyte film with a temperature environment of 50-100°C and applies a pressure of 30-80 MPa for 2-12 hours to finally obtain the electrolyte film.

[0049] The binder used in the following examples and comparative examples is polyisobutylene.

[0050] Example 1

[0051] This invention provides a method for preparing an electrolyte thin film, the method specifically comprising the following steps:

[0052] (1) A solution containing the binder is prepared by mixing 6 wt% of the binder with an ester or benzene solvent at 80°C and maintaining the mixture for 24 h. The molecular weight of the binder is 2 million.

[0053] (2) A solution of sulfide solid electrolyte and binder with a weight percentage of 94wt% was placed into a degassing machine. The speed of the degassing machine was controlled at 1200rpm and the stirring time was 60min to obtain a slurry.

[0054] (3) Use a transfer coating machine to evenly coat the slurry onto the release film.

[0055] (4) Transfer the release film coated with slurry to the heating table, control the temperature of the heating table at 50°C, and heat for 12 hours to form an electrolyte film on the release film.

[0056] (5) Use a roller press to press the electrolyte film at a pressure of 30 MPa so that the electrolyte film is separated from the release film.

[0057] (6) Place the electrolyte film on a hot press, heat the electrolyte film to 50°C, and apply a pressure of 80 MPa to the electrolyte film for 2 hours to obtain the electrolyte film.

[0058] Example 2

[0059] This invention provides a method for preparing an electrolyte thin film, the method specifically comprising the following steps:

[0060] (1) A solution containing the binder is prepared by mixing 5 wt% of the binder with an ester or benzene solvent at 85°C and maintaining the mixture for 24 h. The molecular weight of the binder is 3 million.

[0061] (2) A solution of 95 wt% sulfide solid electrolyte and binder was placed in a degassing machine. The speed of the degassing machine was controlled at 2000 rpm and the stirring time was 30 min to obtain a slurry.

[0062] (3) Use a transfer coating machine to evenly coat the slurry onto the release film.

[0063] (4) Transfer the release film coated with slurry to the heating table, control the temperature of the heating table at 75°C, and heat for 7 hours to form an electrolyte film on the release film.

[0064] (5) Use a roller press to press the electrolyte film at a pressure of 55 MPa so that the electrolyte film is separated from the release film.

[0065] (6) Place the electrolyte film on a hot press, heat the electrolyte film to 75°C, and apply a pressure of 55 MPa to the electrolyte film for 7 hours to obtain the electrolyte film.

[0066] Example 3

[0067] This invention provides a method for preparing an electrolyte thin film, the method specifically comprising the following steps:

[0068] (1) A solution containing the binder is prepared by mixing 4 wt% of the binder with an ester or benzene solvent at 90°C and maintaining the mixture for 24 h. The molecular weight of the binder is 4 million.

[0069] (2) A solution of 96 wt% sulfide solid electrolyte and binder was placed in a degassing machine. The speed of the degassing machine was controlled at 3200 rpm and the stirring time was 10 min to obtain a slurry.

[0070] (3) Use a transfer coating machine to evenly coat the slurry onto the release film.

[0071] (4) Transfer the release film coated with slurry to the heating table, control the temperature of the heating table at 100°C, and heat for 12 hours to form an electrolyte film on the release film.

[0072] (5) Use a roller press to press the electrolyte film at a pressure of 80 MPa so that the electrolyte film is separated from the release film.

[0073] (6) Place the electrolyte film on a hot press, heat the electrolyte film to 100°C and apply a pressure of 30 MPa to the electrolyte film for 12 hours to obtain the electrolyte film.

[0074] Example 4

[0075] This invention provides a method for preparing an electrolyte thin film, the method specifically comprising the following steps:

[0076] (1) A solution containing the binder is prepared by mixing 6 wt% of the binder with an ester or benzene solvent at 80°C and maintaining the mixture for 24 h. The molecular weight of the binder is 1 million.

[0077] (2) A solution of sulfide solid electrolyte and binder with a weight percentage of 94wt% was placed into a degassing machine. The speed of the degassing machine was controlled at 1200rpm and the stirring time was 60min to obtain a slurry.

[0078] (3) Use a transfer coating machine to evenly coat the slurry onto the release film.

[0079] (4) Transfer the release film coated with slurry to the heating table, control the temperature of the heating table at 50°C, and heat for 12 hours to form an electrolyte film on the release film.

[0080] (5) Use a roller press to press the electrolyte film at a pressure of 30 MPa so that the electrolyte film is separated from the release film.

[0081] (6) Place the electrolyte film on a hot press, heat the electrolyte film to 50°C, and apply a pressure of 80 MPa to the electrolyte film for 2 hours to obtain the electrolyte film.

[0082] Example 5

[0083] This invention provides a method for preparing an electrolyte thin film, the method specifically comprising the following steps:

[0084] (1) A solution containing the binder is prepared by mixing 6 wt% of the binder with an ester or benzene solvent at 80°C and maintaining the mixture for 24 h. The molecular weight of the binder is 6.5 million.

[0085] (2) A solution of sulfide solid electrolyte and binder with a weight percentage of 94wt% was placed into a degassing machine. The speed of the degassing machine was controlled at 1200rpm and the stirring time was 60min to obtain a slurry.

[0086] (3) Use a transfer coating machine to evenly coat the slurry onto the release film.

[0087] (4) Transfer the release film coated with slurry to the heating table, control the temperature of the heating table at 50°C, and heat for 12 hours to form an electrolyte film on the release film.

[0088] (5) Use a roller press to press the electrolyte film at a pressure of 30 MPa so that the electrolyte film is separated from the release film.

[0089] (6) Place the electrolyte film on a hot press, heat the electrolyte film to 50°C, and apply a pressure of 80 MPa to the electrolyte film for 2 hours to obtain the electrolyte film.

[0090] Comparative Example 1

[0091] S1: Add 93 wt% solid electrolyte and 7 wt% binder to...

[0092] In the dispersion, a uniformly dispersed electrolyte slurry is obtained by thorough mixing; wherein the molecular weight of the binder is 300,000.

[0093] S2: Coat the electrolyte slurry onto the skeleton, heat to 50℃ for 12 hours, and then pressurize to 30MPa.

[0094] An electrolyte film was obtained.

[0095] Comparative Example 2

[0096] S1: Add 97 wt% solid electrolyte and 3 wt% binder to...

[0097] In the dispersion, a uniformly dispersed electrolyte slurry is obtained by thorough mixing; wherein the molecular weight of the binder is 8 million.

[0098] S2: Coat the electrolyte slurry onto the skeleton, heat to 50℃ for 12 hours, and then pressurize to 30MPa.

[0099] An electrolyte film was obtained.

[0100] Comparative Example 3

[0101] S1: Add 94 wt% solid electrolyte and 6 wt% binder to...

[0102] In the dispersion, a uniformly dispersed electrolyte slurry is obtained by thorough mixing; wherein the molecular weight of the binder is 2 million.

[0103] S2: Coat the electrolyte slurry onto the skeleton, heat to 50℃ for 12 hours, and then pressurize to 30MPa.

[0104] An electrolyte film was obtained.

[0105] Examples 1 to 5 and prior art were prepared using the method for preparing electrolyte films provided by the present invention.

[0106] The results of comparative examples 1 to 3 prepared by the method for preparing electrolyte films are shown in Table 1 below:

[0107] Adhesive molecular weight, adhesive (wt%), temperature, sulfide, solid electrolyte (wt%), degassing machine speed and stirring time, heating platform temperature and heating time, pressure, temperature, pressure, and duration of electrolyte film heating. Example 1: 2 million, 6wt%, 80℃, 94wt%, 1200rpm, 60min, 50℃, 12h, 30MPa, 50℃, 80MPa, 2h. Example 2: 3 million, 5wt%, 85℃, 95wt%, 2000rpm, 30min, 75℃, 7h, 55MPa, 75℃, 55MPa, 7h. Example 3: 4 million, 4wt%, 90... Example 4: 1,000,000 units; 96wt%; 3200rpm; 10min; 100℃; 12h; 80MPa; 100℃; 30MPa; 12h; Example 5: 6,500,000 units; 6wt%; 80℃; 94wt%; 1200rpm; 60min; 50℃; 12h; 30MPa; 50℃; 80MPa; 2h; Comparative Example 1: 1,300,000 units; 7wt%; 80℃; 93wt%; 1200rpm; 60min; 50℃; 12h; 30MPa Comparative Example 28 million, 3wt% at 80℃, 97wt% at 1200rpm, 60min at 50℃, 12h at 30MPa; Comparative Example 32 million, 6wt% at 80℃, 94wt% at 1200rpm, 60min at 50℃, 12h at 30MPa

[0108] Table 1

[0109] Porosity was calculated using mercury intrusion porosimetry (by measuring the pressure change of mercury in the pores of the material), AC impedance spectroscopy (using a Gamry Reference 620 electrochemical workstation), DC polarization method (using a Gamry Reference 620 electrochemical workstation, calculated using the Hebb-Wagner DC polarization method), universal mechanical testing machine (manufactured by Shanghai Xiangjie Instrument Technology Co., Ltd.), bending tester (using a QTY-32 paint film cylindrical bending tester), and optical microscope (manufactured by Yuescope). The results obtained after testing the porosity, ionic conductivity, electronic conductivity, tensile strength, and thickness of the electrolyte films in Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 2 below.

[0110] Porosity, Ionic Conductivity, Electronic Conductivity, Tensile Strength, Bending Radius, Elongation at Break, Electrolyte Film Thickness Example 1: 9% 1.6 mS / cm 2.7 × 10⁻¹⁰ S / cm 0.45 MPa 3 mm 0.55% 50 μm Example 2: 8.5% 1.8 mS / cm 3.2 × 10⁻¹⁰ S / cm 0.37 MPa 2 mm 0.51% 50 μm Example 3: 7% 2.0 mS / cm 5.9 × 10⁻¹⁰ S / cm 0.84 MPa 2 mm 1.48% 50 μm Example 4: 7.1% 1.8 mS / cm 2.6 × 10⁻¹⁰ S / cm 0.32 MPa 4 mm 0.6% 50 μm Example 5 6.7% 1.7 mS / cm 3.1 × 10⁻¹⁰ S / cm 0.86 MPa 2 mm 1.31% 50 μm Comparative Example 1 15% 1.2 mS / cm 2.3 × 10⁻¹⁰ S / cm 0.28 MPa 7 mm 0.45% 50 μm Comparative Example 2 10.5% 1.4 mS / cm 2.2 × 10⁻¹⁰ S / cm 0.71 MPa 6 mm 1.1% 50 μm Comparative Example 3 12% 1.2 mS / cm 2.1 × 10⁻¹⁰ 0.24 MPa 7 mm 0.3% 50 μm

[0111] Table 2

[0112] As shown in Table 2, the porosity of the electrolyte films in Examples 1 to 5 is all below 10%, while the porosity of the electrolyte films in Comparative Examples 1, 2, and 3 is all above 10%. The ionic conductivity of the electrolyte films in Examples 1 to 5 is all greater than or equal to 1.5 mS / cm, while the ionic conductivity of the electrolyte films in Comparative Examples 1, 2, and 3 is all less than 1.5 mS / cm. The electronic conductivity of the electrolyte films in Examples 1 to 5 is all above 2.4 × 10⁻⁶. -10 -6.1*10 -10 Within the S / cm range, the electronic conductivity of the electrolyte films in Comparative Examples 1, 2, and 3 is all less than 2.4 × 10⁻⁶. -10 S / cm. The tensile strength of the electrolyte films in Examples 1 to 5 is in the range of 0.3-1 MPa, the tensile strength of Comparative Examples 1 and 2 is in the range of 0.3-1 MPa, and the tensile strength of the electrolyte film in Comparative Example 3 is less than 0.3 MPa. The bending radius of the electrolyte films in Examples 1 to 5 is less than 5 mm, and the bending radii of the electrolyte films in Comparative Examples 1, 2, and 3 are 7 mm, 6 mm, and 7 mm, respectively. The thickness of the electrolyte films in Examples 1 to 5 and Comparative Examples 1, 2, and 3 is 50 μm. As shown in Table 2, the electrolyte films provided in this application have higher mechanical strength and higher stability of ionic conductivity compared to existing commercially available electrolyte films.

[0113] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. An electrolyte thin film, characterized in that, include: A sulfide solid electrolyte and a binder, wherein the molecular weight of the binder is between 500,000 and 7 million; The porosity of the electrolyte membrane is less than or equal to 10%.

2. The electrolyte film according to claim 1, characterized in that, The electrolyte film has a tensile strength of 0.3-1 MPa and a bending radius of 5 mm or less.

3. The electrolyte film according to claim 1, characterized in that, The elongation at break of the electrolyte film is between 0.5% and 1.5%.

4. The electrolyte film according to claim 1, characterized in that, The sulfide solid electrolyte has a weight percentage of 94-96 wt%, and the binder has a weight percentage of 4-6 wt%.

5. The electrolyte film according to claim 1, characterized in that, The electrolyte film has an ionic conductivity greater than or equal to 1.5 mS / cm and an electronic conductivity of 2.4 × 10⁻⁶ mS / cm. -10 -6.1*10 -10 S / cm.

6. The electrolyte film according to claim 1, characterized in that, The thickness of the electrolyte film is less than or equal to 65 μm.

7. The electrolyte film according to claim 1, characterized in that, The adhesive includes at least one of thermoplastic elastomer, styrene-butadiene rubber, polyvinylidene fluoride, thermoplastic styrene-butadiene rubber, synthetic rubber, hydrogenated nitrile rubber, polyethylene-vinyl acetate, polymethyl methacrylate, polyacrylic acid, polyisobutylene, cis-butadiene rubber, and nitrile rubber.

8. A method for preparing an electrolyte thin film, characterized in that, The method for preparing the electrolyte thin film according to any one of claims 1 to 6 comprises: The solution containing the binder is stirred and mixed with a sulfide solid electrolyte to obtain a slurry; The slurry is coated onto a release film, and the release film is then heated to form an electrolyte film on the release film. The electrolyte film is separated from the release film and then subjected to heating and pressurization treatment.

9. The preparation method according to claim 8, characterized in that, The step of transferring the release film to a heating device for heating treatment includes: The release film is transferred to a vacuum transition chamber at 50-100°C and heated for 2-12 hours; The release film is transferred to a heating table at 50-100°C and heated for 2-12 hours.

10. The preparation method according to claim 8, characterized in that, The step of separating the electrolyte film from the release film includes: Apply a pressure of 30-80 MPa to the electrolyte film until the electrolyte film separates from the release film.

11. The preparation method according to claim 8, characterized in that, The process of heating and pressurizing the electrolyte film includes: The electrolyte membrane is placed in an environment of 50-100°C and subjected to a pressure of 30-80 MPa for 2-12 hours.

12. The preparation method according to claim 8, characterized in that, The sulfide solid electrolyte is in the form of powder, and the D50 of the sulfide solid electrolyte is 3-15 μm.

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