Solid-state electrolyte film and preparation method thereof, electrode assembly and preparation method thereof, solid-state battery and electric device

Abstract

The invention discloses a solid electrolyte film and a preparation method thereof, an electrode assembly and a preparation method thereof, a solid-state battery and an electric device. The method for preparing the solid electrolyte film comprises the following steps: (1) preparing a mixed material: the mixed material comprises an inorganic material, a thermoplastic elastomer and a lithium salt, the inorganic material comprises an inorganic ceramic material and / or an inorganic solid electrolyte, and the mixed material is obtained by dry mixing; (2) carrying out hot pressing on the mixed material to obtain a solid electrolyte film; wherein a release layer is arranged on the contact surface of the hot-pressing equipment for hot-pressing the mixed material and the mixed material. By adopting the method, the strippable flexible solid electrolyte film with good flexibility, good ductility, high ionic conductivity, uniform thickness, smooth and pore-free surface can be prepared, the method does not use an organic solvent, is low in cost and environment-friendly, meanwhile, batch production of the solid electrolyte film can be realized by one-step hot press molding, and the method has remarkable economic benefits.

Description

Technical Field

[0001] The present invention belongs to the field of batteries, and particularly relates to a solid electrolyte film, a preparation method thereof, an electrode assembly, a preparation method thereof, a solid battery, and an electrical device. Background Art

[0002] Improving the energy density and safety of lithium-ion batteries is a key direction in the research and development of commercial batteries at present. Due to the use of liquid electrolytes and separators, traditional lithium-ion batteries seriously affect the high-temperature performance and safety of the batteries, and the use of separators inevitably affects the energy density of the batteries. To improve the energy density and safety of lithium-ion batteries, a solid electrolyte membrane can be used to replace the separator and liquid electrolyte.

[0003] Solid electrolytes can be divided into inorganic solid electrolytes, polymer solid electrolytes, and composite solid electrolytes. While improving the ionic conductivity of solid electrolytes, how to solve the processability of solid electrolytes is currently a problem restricting the mass production of solid batteries. Preparing a solid electrolyte film can improve the processability of solid electrolytes and solve the use problem in solid batteries, but the production of solid electrolyte films is limited by the preparation method and cannot achieve mass production. Currently, the commonly used methods for preparing solid electrolyte membranes include dry methods and wet methods. The traditional wet method for preparing solid electrolyte membranes has a high cost due to the use of specific solvents. At the same time, the volatilization of toxic organic solvents during the wet preparation process will also cause environmental pollution, and pores and other defects are likely to occur during the drying process. Moreover, in the preparation process, process steps such as drying and rolling will result in uneven thickness of the solid electrolyte membrane, which is not conducive to obtaining a solid electrolyte membrane with uniform thickness. The dry preparation process can avoid the use of organic solvents and does not require energy-consuming steps such as drying, which can effectively reduce production costs and improve production efficiency. However, in the existing dry preparation process, the active components of the solid electrolyte membrane are not easily dispersed during the mixing stage, increasing the film-making difficulty. Moreover, during the preparation of the solid electrolyte membrane, there are process problems such as difficult peeling, strong adhesion, poor tensile strength of the obtained solid electrolyte membrane, and difficult control of the thickness of the solid electrolyte membrane. In addition, the use of binders seriously affects the ionic conductivity of the solid electrolyte film. On the other hand, the solid electrolyte membrane obtained by dry film-making is relatively thick and needs to be solved by processes such as rolling. However, during the subsequent process of controlling the thickness by rolling, problems such as wrinkles and stress damage caused by adhesion to the substrate will occur, seriously affecting the interface contact between the solid electrolyte membrane and the electrode active material and resulting in an increase in interface impedance.

[0004] Therefore, there is an urgent need to develop a new process method to solve the problems of the existing dry process for preparing solid electrolyte films and prepare solid electrolyte films that are easy to peel and have excellent performance. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an object of the present invention is to provide a solid electrolyte film, a method for preparing the same, an electrode assembly, a method for preparing the same, a solid-state battery, and an electrical device. By synergistically combining materials, processes, and release layers, the present invention can prepare a flexible solid electrolyte film with good flexibility, excellent ductility, high ionic conductivity, uniform thickness, a flat surface without pores, and peelability. Moreover, this method does not use organic solvents, has low costs, is environmentally friendly, and can achieve batch production of solid electrolyte films through one-step hot pressing, thus having significant economic benefits.

[0006] In one aspect of the present invention, a method for preparing a solid electrolyte film is provided. According to an embodiment of the present invention, the method includes:

[0007] (1) Preparing a mixed material: The mixed material includes an inorganic material, a thermoplastic elastomer, and a lithium salt. The inorganic material includes an inorganic ceramic material and / or an inorganic solid electrolyte, and the mixed material is obtained by dry mixing.

[0008] (2) Hot pressing the mixed material to obtain a solid electrolyte film; a release layer is provided on the contact surface between the hot pressing device for hot pressing the mixed material and the mixed material.

[0009] According to the method for preparing a solid electrolyte film of the above embodiment of the present invention, first, an inorganic ceramic material and / or an inorganic solid electrolyte, a thermoplastic elastomer, and a lithium salt are mixed to obtain a mixed material. Among them, the thermoplastic elastomer has good flexibility at both high and low temperatures, can increase the contact area between the solid electrolyte and the electrode sheet, reduce the contact gap, effectively improve the ionic conductivity and ion transport efficiency of the solid electrolyte film, and further improve the cycle stability of the battery. The inorganic ceramic material not only has good insulation and high-temperature resistance, can improve the safety performance of the solid electrolyte film, but also the introduction of the inorganic ceramic material can increase the proportion of amorphous regions in the solid electrolyte, increase the specific surface area in the composite solid electrolyte system, and construct more lithium ion channels at the interface, thereby improving the ionic conductivity and ion transport efficiency of the solid electrolyte film. A single thermoplastic elastomer or inorganic material cannot be hot pressed into a film. In the present invention, the inorganic material and lithium salt can regulate the hardness of the elastomer, making the mixed material have better ductility and facilitating hot pressing into a film at low temperature. Therefore, the inorganic material, thermoplastic elastomer, and lithium salt cooperate with each other, and none of the three raw materials can be missing, so that the raw materials meet the hot pressing conditions, the mixed material has viscoelasticity and ductility, is conducive to cooperating with the subsequent hot pressing process, forms a uniform, dense, pore-free, and self-supporting solid electrolyte film during hot pressing, softens the contact interface between the solid electrolyte film and the electrode sheet, and improves the flexibility and ionic conductivity of the solid electrolyte film.

[0010] Secondly, due to the viscoelasticity of the composite solid electrolyte mixture of inorganic materials, thermoplastic elastomers and lithium salts, it is not easy to peel off, and it is impossible to prepare an independently supported film. Moreover, defects such as breakage, wrinkles, and pores are likely to occur during the peeling process, which will affect the density, mechanical properties, and electrochemical properties of the solid electrolyte film. Therefore, in the present invention, the above-mentioned mixed material is placed between the release layers and hot-pressed, so that the release layers play a role in the synthesis process of the solid electrolyte film. Through the synergistic cooperation among the material, the hot-pressing process, and the release layers, on the one hand, it helps the peeling of the solid electrolyte film, prevents the generation of defects during the peeling process, eliminates the pores on the surface of the solid electrolyte film, increases the interfacial contact area between the solid electrolyte film and the electrode, reduces the interfacial impedance, and improves the electrochemical properties and tensile strength of the solid electrolyte film. On the other hand, the cooperation of the material, the hot-pressing process, and the release layers can also reduce the extension resistance of the mixed material during the hot-pressing process, improve the density of the obtained solid electrolyte film and reduce the thickness, eliminating the preparation step of rolling. This not only reduces energy consumption and saves costs, but also overcomes the problem of uneven thickness of the solid electrolyte film caused by rolling, further avoiding the generation of defects, and realizing the preparation of a solid electrolyte film to replace the separator to complete the all-solid-state battery. In addition, when preparing the solid electrolyte film by the dry method, no organic solvent is used throughout the process, which not only reduces costs, but also avoids the generation of pores on the surface of the solid electrolyte film caused by the volatilization of organic solvents, increases the interfacial contact area between the solid electrolyte and the electrode, and reduces the interfacial impedance. It is precisely because of the use of thermoplastic elastomers and the combined use of release layer plates that a one-step hot-pressing forming process is realized, and an independently supported solid electrolyte film with excellent interfacial flexibility, small stress damage, uniform thickness, and no pores is prepared. Thus, a flexible solid electrolyte film with good flexibility, excellent ductility, high ionic conductivity, uniform thickness, flat surface, no pores, and peelable can be prepared by this method. Moreover, this method does not use organic solvents, has low costs, is environmentally friendly, and at the same time, the one-step hot-pressing forming can realize the batch production of solid electrolyte films, with significant economic benefits.

[0011] In addition, the method for preparing a solid electrolyte film according to the above embodiments of the present invention may further have the following additional technical features:

[0012] In some embodiments of the present invention, the weight-average molecular weight of the thermoplastic elastomer is 20,000 to 150,000, and further preferably 80,000 to 120,000. Thereby, the flexibility of the solid electrolyte film can be improved, the interfacial impedance can be reduced, and the ionic conductivity can be increased.

[0013] In some embodiments of the present invention, the hardness of the thermoplastic elastomer is 0A to 80A, preferably 0A to 65A, and further preferably 40 to 60A. Thereby, the flexibility of the solid electrolyte film can be improved, the interfacial impedance can be reduced, and the ionic conductivity can be increased.

[0014] In some embodiments of the present invention, the thermoplastic elastomer includes at least one of polyimide (PI), thermoplastic polyurethane (TPU), thermoplastic polyamide elastomer (TPAE), polyetherimide (PEI), polyetheretherketone (PEEK), thermoplastic vulcanizate (TPV), thermoplastic polyvinyl chloride elastomer (TPVC), polyolefin elastomer (TPV), vinyl chloride thermoplastic elastomer (TPE), and thermoplastic polyester elastomer (TPEE). Thereby, the flexibility of the solid electrolyte film can be improved, the interfacial impedance can be reduced, and the ionic conductivity can be increased.

[0015] In some embodiments of the present invention, the inorganic ceramic material includes at least one of metal oxides, nitrides, carbides, borides, and non-metal oxides. Thereby, the safety and ionic conductivity of the solid electrolyte film can be improved.

[0016] In some embodiments of the present invention, the inorganic solid electrolyte includes at least one of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, nitride solid electrolytes, and borate solid electrolytes.

[0017] In some embodiments of the present invention, the particle sizes of the inorganic ceramic material and the inorganic solid electrolyte are independently 300 nm to 3 μm respectively. Thereby, the safety and ionic conductivity of the solid electrolyte film can be improved.

[0018] In some embodiments of the present invention, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, and lithium difluorooxalate borate.

[0019] In some embodiments of the present invention, the hot pressing device includes a first heating plate and a second heating plate. The mixed material is placed between the first heating plate and the second heating plate for hot pressing, and release layers are respectively provided on the opposite surfaces of the first heating plate and the second heating plate.

[0020] In some embodiments of the present invention, the metal oxide includes at least one of aluminum oxide (Al2O3), titanium dioxide (TiO2), zirconium dioxide (ZrO2), and magnesium oxide (MgO).

[0021] In some embodiments of the present invention, the nitride includes at least one of silicon nitride (Si3N4), titanium nitride (TiN), aluminum nitride (AlN), boron nitride (BN), magnesium nitride (Mg3N2), and zirconium nitride (ZrN or Zr3N4).

[0022] In some embodiments of the present invention, the carbide includes at least one of silicon carbide (SiC) and boron carbide (B4C).

[0023] In some embodiments of the present invention, the non-metal oxide includes at least one of silicon dioxide (SiO2) and boron oxide (B2O3).

[0024] In some embodiments of the present invention, the boride includes at least one of silicon boride, vanadium boride, magnesium boride, and titanium boride.

[0025] In some embodiments of the present invention, in step (1), the mass ratio of the inorganic material to the thermoplastic elastomer is (90 - 70):(10 - 30). Thereby, the tensile strength and ionic conductivity of the solid electrolyte film can be improved.

[0026] In some embodiments of the present invention, in step (1), the mass ratio of the thermoplastic elastomer to the lithium salt is (5 - 1):1. Thereby, the flexibility of the solid electrolyte film can be improved, the interfacial impedance can be reduced, and the ionic conductivity can be increased.

[0027] In some embodiments of the present invention, the dry mixing method is grinding, specifically dry grinding; the grinding includes ball milling, the vacuum degree of the ball milling is not greater than 0.1 MPa, the rotation speed of the ball milling is 200 r / min - 600 r / min, and the time of the ball milling is 20 min - 180 min. Thereby, agglomeration can be avoided and the ionic conductivity of the solid electrolyte film can be improved.

[0028] In some embodiments of the present invention, the mixed material does not contain a binder. Thereby, the ionic conductivity of the solid electrolyte film can be improved.

[0029] In some embodiments of the present invention, in step (2), the hot pressing temperature is 40°C - 160°C, the hot pressing time is 20 min - 90 min, and the hot pressing pressure is 2 MPa - 40 MPa. Thereby, the ionic conductivity of the solid electrolyte film can be improved.

[0030] In some embodiments of the present invention, the release layer board includes coated release paper, glassine release paper, CCK release paper, single-sided silicone release paper, double-sided silicone release paper, silicone oil paper, release film, fluorine release film, anti-static paper, PET film, sulfur-free paper, kraft paper, aluminum-plastic film, rust-proof paper, or stainless steel plate. Preferably, it includes single-sided silicone release paper, double-sided silicone release paper, silicone oil paper, release film, PET film, or sulfur-free paper. More preferably, it includes single-sided silicone release paper, double-sided silicone release paper, silicone oil paper, silicone-containing release film, or sulfur-free paper.

[0031] In some embodiments of the present invention, the mixed material is hot-pressed and cooled by the hot-pressing device and then cold-pressed. Thereby, the denseness of the solid electrolyte film can be improved.

[0032] In some embodiments of the present invention, the pressure of the cold pressing is 10 MPa to 50 MPa, and the time of the cold pressing is 10 min to 60 min. Thereby, the denseness of the surface of the solid electrolyte film can be improved.

[0033] In some embodiments of the present invention, the thickness of the solid electrolyte film is 20 μm to 80 μm. Thereby, the electrical performance of the solid-state battery can be improved.

[0034] In the second aspect of the present invention, the present invention provides a solid electrolyte film. According to the embodiments of the present invention, the solid electrolyte film is obtained by the above method for preparing a solid electrolyte film. Thus, the solid electrolyte film has excellent flexibility, high ionic conductivity, uniform thickness, and a flat surface without pores.

[0035] In the third aspect of the present invention, the present invention provides an electrode assembly. According to the embodiments of the present invention, the electrode assembly includes the above solid electrolyte film. Thus, the electrode assembly has a high ionic conductivity.

[0036] In the fourth aspect of the present invention, the present invention provides a method for preparing the above electrode assembly. According to the embodiments of the present invention, the above solid electrolyte film is hot-pressed on the surface of the electrode sheet, and a release layer is provided on the contact surface of the hot-pressing device for hot-pressing the solid electrolyte film, so as to obtain the electrode assembly. Thus, an electrode assembly with high ionic conductivity can be prepared by using this method.

[0037] In the fifth aspect of the present invention, the present invention provides a solid-state battery. According to the embodiments of the present invention, the solid-state battery includes the above solid electrolyte film or the above electrode assembly. Thus, the solid-state battery has high safety and energy density.

[0038] In the sixth aspect of the present invention, the present invention provides an electrical device. According to the embodiments of the present invention, the electrical device includes the above solid-state battery. Thus, the electrical device has excellent cycle stability and safety.

[0039] The additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0041] Figure 1 It is the SEM image of the solid electrolyte film prepared in Example 1 of the present invention;

[0042] Figure 2 It is the physical image of the solid electrolyte film prepared in Example 1 of the present invention. Detailed implementation manners

[0043] The embodiments of the present invention will be described in detail below, aiming to explain the present invention and should not be construed as a limitation to the present invention.

[0044] In one aspect of the present invention, the present invention provides a method for preparing a solid electrolyte film, especially an independently supported solid electrolyte film. According to an embodiment of the present invention, the method includes:

[0045] S100: Prepare a mixed material

[0046] In this step, an inorganic material, a thermoplastic elastomer, and a lithium salt are mixed and ground. The inorganic material includes an inorganic ceramic material and / or an inorganic solid electrolyte, and a dry mixing method is used to obtain the mixed material. Among them, the thermoplastic elastomer has good flexibility at both high and low temperatures, which can increase the contact area between the solid electrolyte and the electrode sheet and reduce the contact gap, thereby effectively improving the ionic conductivity and ionic transport efficiency of the solid electrolyte film, and further enhancing the cycle stability of the battery. The inorganic ceramic material not only has good insulation and high-temperature resistance properties, which can improve the safety performance of the solid electrolyte film, but also the introduction of the inorganic ceramic material can increase the proportion of amorphous regions in the solid electrolyte, increase the specific surface area in the composite solid electrolyte system, and construct more lithium-ion channels at the interface, thereby improving the ionic conductivity and ionic transport efficiency of the solid electrolyte film. A single thermoplastic elastomer or inorganic material cannot be hot-pressed into a film. The inorganic material and lithium salt in the present invention can regulate the hardness of the elastomer, making the mixed material have better ductility and facilitating low-temperature hot-pressing into a film. Therefore, the inorganic material, thermoplastic elastomer, and lithium salt cooperate with each other, and none of the three raw materials can be missing, so that the raw materials meet the hot-pressing conditions. The mixed material has viscoelasticity and ductility, which is conducive to cooperating with the subsequent hot-pressing process to form a uniform, dense, pore-free, and independently supported solid electrolyte film during the hot-pressing process, softening the contact interface between the solid electrolyte film and the electrode sheet, and enhancing the flexibility and ionic conductivity of the solid electrolyte film.

[0047] It should be noted that the lithium salt is a conventional material in the art, and those skilled in the art can select it according to the actual situation. For example, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, and lithium difluorooxalate borate.

[0048] According to an embodiment of the present invention, the inorganic ceramic material includes at least one of metal oxides, nitrides, carbides, borides, and non-metal oxides. The inorganic solid electrolyte includes at least one of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, nitride solid electrolytes, and borate solid electrolytes.

[0049] According to an embodiment of the present invention, the particle sizes of the inorganic ceramic material and the inorganic solid electrolyte are independently 300 nm to 3 μm respectively. For example, the particle sizes are 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc. The inventors have found that when the particle size of the inorganic ceramic material is in the range of 300 nm to 3 μm, particle agglomeration can be avoided, which is beneficial to the dispersion of the inorganic ceramic material and the inorganic solid electrolyte, thereby improving the uniformity and ionic conductivity of the solid electrolyte thin film.

[0050] As an example, the oxide solid electrolyte includes, but is not limited to, one or a combination of lithium lanthanum zirconium oxide (LLZO), niobium-doped lithium lanthanum zirconium oxide (LLZNO), tantalum-doped lithium lanthanum zirconium oxide (LLZTO), niobium and tantalum co-doped lithium lanthanum zirconium oxide (LLZNTO), lithium lanthanum titanium oxide (LLTO), lithium aluminum titanium phosphate (LATP), yttrium titanium phosphate (LYTP), lithium germanium aluminum phosphate (LAGP), lithium aluminum oxide (LiAlO2); the sulfide solid electrolyte includes, but is not limited to, one or a combination of lithium germanium phosphorus sulfide (LGPS), lithium phosphorus sulfur chloride (LPSCl), lithium thiophosphate (LPS), vitreous sulfide (Li2S-P2S5, Li2S-SiS2, Li2S-B2S3); the halide solid electrolyte includes, but is not limited to, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1), Li2XCl4 (X includes Cd and / or Mg), Li2X′I4 (X′ includes Cd and / or Zn), LiMCl5X″ (M includes one or more of La, Ta, Nb; X″ includes any one of O, Cl, F, OH), Li 3-x Zr x M′ 1-x Cl6 (M′ includes one or more of Y, Er, Yb, Ho, Lu, 0 ≤ x ≤ 1) in one or a combination; the nitride solid electrolyte includes, but is not limited to, one or a combination of LiPON, Li3N, Li7PN4, LiSi2N3; the borate solid electrolyte includes, but is not limited to, Li2B4O7, Li2O-B2O3-P2O5, Li 6+2x [B 10 S 18 S xone or more combinations thereof; the hydride solid electrolyte includes, but is not limited to, one or more combinations of Li3AlH6, LiBH4, LiNH2, Li2NH, LiBH4-LiNH2, LiBHI, LiBH4-LiX (X = Cl, Br, I).

[0051] As an example, the metal oxide includes, but is not limited to, at least one of alumina, titanium dioxide, zirconium dioxide, and magnesium oxide. The nitride includes, but is not limited to, at least one of silicon nitride, titanium nitride, aluminum nitride, boron nitride, magnesium nitride, and zirconium nitride. The carbide includes at least one of silicon carbide and boron carbide. The boride includes, but is not limited to, at least one of silicon boride, vanadium boride, magnesium boride, and titanium boride. The non-metal oxide includes, but is not limited to, at least one of silicon dioxide and boron oxide.

[0052] According to an embodiment of the present invention, the weight-average molecular weight of the thermoplastic elastomer is 20,000 to 150,000, more preferably 80,000 to 120,000. For example, the weight-average molecular weight is 20,000, 40,000, 60,000, 80,000, 100,000, 130,000, 150,000, etc. The inventors found that when the weight-average molecular weight of the thermoplastic elastomer is between 20,000 and 150,000, it is beneficial to the peeling of the solid electrolyte film and easier to form a film, thereby improving the tensile strength and ionic conductivity of the solid electrolyte film.

[0053] According to an embodiment of the present invention, the hardness of the thermoplastic elastomer is 0A to 80A, preferably 0A to 65A, and more preferably 40 to 60A. For example, the hardness is 0A, 10A, 20A, 30A, 40A, 50A, 60A, 70A, 80A, etc. The inventors found that when the hardness of the thermoplastic elastomer is controlled within the above range, it can effectively form a uniformly dispersed mixture with inorganic materials and lithium salts during the ball milling stage and is beneficial to film formation during the hot pressing stage. If the hardness is too large, the solid electrolyte film cannot be prepared, and the thickness of the film cannot be controlled by hot pressing.

[0054] According to an embodiment of the present invention, the thermoplastic elastomer includes at least one of polyimide, thermoplastic polyurethane, polyamide thermoplastic elastomer, polyetherimide, polyetheretherketone, thermoplastic vulcanizate, polyvinyl chloride thermoplastic elastomer, polyolefin elastomer, vinyl chloride thermoplastic elastomer, and thermoplastic polyester elastomer. The above thermoplastic elastomers all have good flexibility at high and low temperatures, can reduce the interfacial impedance of the solid electrolyte film, and improve the ionic conductivity.

[0055] According to an embodiment of the present invention, the mass ratio of the inorganic material to the thermoplastic elastomer is (90 to 70):(10 to 30). For example, the mass ratio is 90:10, 70:10, 80:10, 90:15, 70:15, 80:15, 90:20, 70:20, 80:20, etc. The inventors have found that when the mass ratio of the inorganic material to the thermoplastic elastomer is controlled within the range of (90 to 70):(10 to 30), the mechanical strength of the solid electrolyte membrane can be adjusted, the proportion of the thermoplastic elastomer can be minimized, the specific surface area in the composite solid electrolyte system can be increased, more lithium ion channels can be constructed at the interface, the ionic conductivity of the solid electrolyte membrane can be improved, the ductility of the solid electrolyte mixture can be improved within this range, which is beneficial to obtaining a uniform and dense solid electrolyte thin film under the conditions of the hot pressing process. If the proportion of the thermoplastic elastomer is too high, it will lead to too large interface resistance, reduce the ionic conductivity, and affect the cycle stability of the solid electrolyte thin film.

[0056] According to an embodiment of the present invention, the mass ratio of the thermoplastic elastomer to the lithium salt is (5 to 1):1. For example, the mass ratio is 5:1, 4:1, 3:1, 2:1, etc. The inventors have found that controlling the mass ratio of the thermoplastic elastomer to the lithium salt to be (5 to 1):1 can effectively improve the ionic conductivity of the solid electrolyte membrane, and controlling the proportion of the mixture components is beneficial to the use of the release layer for peeling during the hot pressing process to obtain a uniform and dense solid electrolyte thin film.

[0057] According to an embodiment of the present invention, the dry mixing method is grinding, specifically dry grinding; the grinding includes ball milling, the vacuum degree of the ball milling is not greater than 0.1 MPa, the rotation speed of the ball milling is 200 r / min to 600 r / min, and the time of the ball milling is 20 min to 180 min. For example, the vacuum degrees are 0.08 MPa, 0.07 MPa, 0.06 MPa, 0.05 MPa, 0.04 MPa, 0.03 MPa, 0.02 MPa, etc.; the rotation speeds are 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, etc.; the times are 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, etc. The inventor found that controlling the vacuum degree of the ball milling not greater than 0.1 MPa is beneficial to the formation of a dense solid electrolyte film, avoiding the formation of pores and the oxidation failure of the solid electrolyte film in the air. At the same time, controlling the rotation speed of the ball milling within 200 r / min to 600 r / min and the time of the ball milling within 20 min to 180 min is beneficial to improving the dispersibility of the thermoplastic elastomer in the solid electrolyte, avoiding material agglomeration at the same time, and improving the electrical properties of the solid electrolyte film. Further, the ball milling beads of the ball milling include zirconia ball milling beads, the diameter of the zirconia ball milling beads is 2 mm to 10 mm, and the mass ratio of the zirconia ball milling beads with a diameter of 2 mm to the zirconia ball milling beads with a diameter of 10 mm is 3:1.

[0058] According to an embodiment of the present invention, the mixed material does not contain a binder. After the mixed material is ball milled, it has self-adhesiveness. Combining with the release layer can realize the preparation and peeling of the independent support film, ensure the flatness of the solid electrolyte film, and avoid defects such as breakage, wrinkles, and pores in the solid electrolyte film. The mixed material does not contain a binder, which can improve the ionic conductivity of the solid electrolyte film.

[0059] According to an embodiment of the present invention, an inorganic material, a thermoplastic elastomer, a lithium salt, and a binder are mixed and ground. Based on the total mass of the solid electrolyte, the addition amount of the binder is not greater than 5 wt%. For example, the addition amounts of the binder are 4 wt%, 3.5 wt%, 3 wt%, 2.5 wt%, 2 wt%, 1.5 wt%, 1 wt%, etc. By controlling the addition amount of the binder not greater than 5 wt%, the influence of the binder on the ionic conductivity of the solid electrolyte film is reduced, and good ionic conductivity of the solid electrolyte film is ensured.

[0060] It should be noted that the binder is a conventional material in the art, and those skilled in the art can make selections according to the actual situation. For example, the binder includes but is not limited to at least one of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, lithium polyacrylate, perfluorosulfonic acid resin, and lithium perfluorosulfonic acid resin.

[0061] S200: Hot press the mixed materials

[0062] In this step, hot press the mixed materials. A release layer is provided on the contact surface between the hot press equipment and the mixed materials, thereby obtaining a solid electrolyte film. The composite solid electrolyte mixture of inorganic materials, thermoplastic elastomers, and lithium salts has viscoelasticity, is not easy to peel off, cannot prepare an independently supported film, and is prone to defects such as breakage, wrinkles, and pores during the peeling process, which will affect the density, mechanical properties, and electrochemical properties of the solid electrolyte film. Therefore, in the present invention, the above-mentioned mixed materials are placed between the release layers for hot pressing, so that the release layer plays a role in the synthesis process of the solid electrolyte film. Through the synergistic cooperation among the material, the hot press process, and the release layer, on the one hand, it helps the peeling of the solid electrolyte film, prevents the generation of defects during the peeling process, eliminates the pores on the surface of the solid electrolyte film, increases the interfacial contact area between the solid electrolyte film and the electrode sheet, reduces the interfacial impedance, and improves the electrochemical properties and tensile strength of the solid electrolyte film. On the other hand, the cooperation of the material, the hot press process, and the release layer can also reduce the extension resistance of the mixed materials during the hot press process, improve the density of the obtained solid electrolyte film and reduce the thickness, eliminating the preparation step of rolling. This not only reduces energy consumption and saves costs, but also overcomes the problem of uneven thickness of the solid electrolyte film caused by rolling, further avoiding the generation of defects, and realizing the preparation of a full solid-state battery by replacing the separator with a solid electrolyte film. In addition, when preparing the solid electrolyte film by the dry method, no organic solvent is used throughout the process, which not only reduces costs, but also avoids the generation of pores on the surface of the solid electrolyte film caused by the volatilization of organic solvents, increases the interfacial contact area between the solid electrolyte film and the electrode sheet, and reduces the interfacial impedance. It is precisely because of the use of thermoplastic elastomers and the combined use of the release layer plate that a one-step hot press forming process is realized, and a solid electrolyte film that can be independently supported with excellent interfacial flexibility, small stress damage, uniform thickness, and no pores is prepared.

[0063] According to embodiments of the present invention, the release layer board includes, but is not limited to, coated release paper, glassine release paper, CCK release paper, single-sided silicon release paper, double-sided silicon release paper, silicone oil paper, release film, fluorine-based release film, anti-static paper, PET film, sulfur-free paper, kraft paper, aluminum-plastic film, rust-proof paper or stainless steel plate. Preferably, it includes single-sided silicon release paper, double-sided silicon release paper, silicone oil paper, release film, PET film or sulfur-free paper. More preferably, it includes single-sided silicon release paper, double-sided silicon release paper, silicone oil paper, silicon-containing release film or sulfur-free paper. The composite solid electrolyte mixture of inorganic materials, thermoplastic elastomers and lithium salts has viscoelasticity, is not easy to peel off, cannot be used to prepare an independently supported film, and is prone to defects such as breakage, wrinkles and pores during the peeling process, which will affect the density, mechanical properties and electrochemical properties of the solid electrolyte film. Therefore, a release layer must be selected. The release layer not only helps with peeling and prevents the generation of defects, but also can reduce the extension resistance during the hot pressing process, improve the density of the obtained solid electrolyte thin film and reduce the thickness. In particular, the release layer with a silicon-containing coating and the composite solid electrolyte mixture can produce a synergistic effect. Selecting a release layer with a silicon-containing coating can cause the surface of the solid electrolyte film to couple with the silicon-containing release layer during the film-forming process of heating and pressing in the hot pressing process, improve the dispersibility of the solid electrolyte, prevent agglomeration during the dry film-forming process, and some functional groups can fully release the stress during the film-forming process when contacting the surface of the silicon-containing release layer, improving the density of the solid electrolyte thin film, so as to be applicable to all-solid-state batteries.

[0064] According to embodiments of the present invention, the hot pressing temperature is 40°C to 160°C, the hot pressing time is 20 min to 90 min, and the hot pressing pressure is 2 MPa to 40 MPa. For example, the hot pressing temperature is 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, etc.; the hot pressing time is 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, etc.; the hot pressing pressure is 2 MPa, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, etc. The inventors found that controlling the hot pressing temperature within the range of 40°C to 160°C and the hot pressing time within the range of 20 min to 90 min is beneficial to the formation of a dense solid electrolyte thin film, while ensuring a high ionic conductivity of the solid electrolyte thin film; the hot pressing pressure within the range of 2 MPa to 40 MPa not only forms a film with a suitable thickness, but also avoids breakage of the film, ensuring excellent physical properties of the solid electrolyte thin film.

[0065] According to an embodiment of the present invention, a hot pressing device includes a first heating plate and a second heating plate. The mixed material is placed between the first heating plate and the second heating plate for hot pressing, and release layers are respectively provided on the opposite surfaces of the first heating plate and the second heating plate. The mixed material is placed between the first heating plate and the second heating plate, and then heating and pressing are started to prepare a solid electrolyte film. Alternatively, the first heating plate, the release layer plate, the second heating plate, and the release layer plate are first heated to a suitable hot pressing temperature, the temperature is kept constant, and then the mixed material is placed between the first heating plate and the second heating plate for pressing to prepare a solid electrolyte film. Further, when heating, the heating rate can be controlled to be 4°C / min to 6°C / min.

[0066] According to an embodiment of the present invention, cold pressing is performed after hot pressing and cooling using the hot pressing device. The denseness of the solid electrolyte film can be improved through cold pressing. Further, the pressure of cold pressing is 10 MPa to 50 MPa, and the time of cold pressing is 10 min to 60 min. By controlling the pressure and time of cold pressing within the above ranges, the thickness uniformity of the solid electrolyte film can be improved.

[0067] According to an embodiment of the present invention, the thickness of the solid electrolyte film is 20 μm to 80 μm. For example, the thickness is 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, etc. Controlling the thickness of the solid electrolyte film within 20 μm to 80 μm can avoid battery short - circuit, reduce the interface resistance at the same time, and improve the battery electrical performance.

[0068] Thus, by using this method, a flexible solid electrolyte film with good flexibility, excellent ductility, high ionic conductivity, uniform thickness, flat surface without pores and peelable can be prepared. Moreover, this method does not use organic solvents, has low cost, is environmentally friendly, and one - step hot pressing forming can realize the batch production of solid electrolyte films, with significant economic benefits.

[0069] In the second aspect of the present invention, the present invention proposes a solid electrolyte film. According to an embodiment of the present invention, this solid electrolyte film is obtained by using the above - mentioned method for preparing a solid electrolyte film. Thus, this solid electrolyte film has excellent flexibility, high ionic conductivity, uniform thickness, and a flat surface without pores.

[0070] In the third aspect of the present invention, the present invention proposes an electrode assembly. According to an embodiment of the present invention, this electrode assembly includes the above - mentioned solid electrolyte film. Thus, this electrode assembly has a high ionic conductivity. It should be noted that the features and advantages described above for the solid electrolyte film also apply to this electrode assembly, and will not be elaborated here.

[0071] In a fourth aspect of the present invention, there is provided a method for preparing the above-mentioned electrode assembly. According to an embodiment of the present invention, the above-mentioned solid electrolyte film is hot-pressed on the surface of the electrode sheet. A release layer is provided on the contact surface of the hot-pressing device for hot-pressing the solid electrolyte film to obtain the electrode assembly. Thus, an electrode assembly with high ionic conductivity can be prepared by this method. It should be noted that the features and advantages described above for the electrode assembly also apply to this method and will not be elaborated here.

[0072] In a fifth aspect of the present invention, there is provided a solid-state battery. According to an embodiment of the present invention, the solid-state battery includes the above-mentioned solid electrolyte film or electrode assembly. Thus, the solid-state battery has high safety and energy density. It should be noted that the features and advantages described above for the solid electrolyte film and the electrode assembly also apply to this solid-state battery and will not be elaborated here.

[0073] According to an embodiment of the present invention, the solid-state battery includes a positive electrode sheet, a solid electrolyte film, and a negative electrode sheet. The positive electrode sheet, the solid electrolyte film, and the negative electrode sheet are laminated and hot-pressed in sequence to prepare an integrated solid-state battery. Further, the hot-pressing temperature is 50°C to 100°C, and the hot-pressing pressure is 2 MPa to 10 MPa. It should be noted that the positive electrode sheet and the negative electrode sheet are conventional components in the art, and those skilled in the art can select them according to actual situations. As an example, the main materials of the positive electrode sheet include, but are not limited to, one or more combinations of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium cobaltate, lithium manganate, and lithium vanadium phosphate; the main materials of the negative electrode sheet include, but are not limited to, one or more combinations of graphite, graphene, carbon nanotubes, silicon-based alloys, silicon oxide anodes, silicon-carbon anodes, lithium metal, lithium alloy anodes, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

[0074] In a sixth aspect of the present invention, there is provided an electrical device. According to an embodiment of the present invention, the electrical device includes the above-mentioned solid-state battery. Thus, the electrical device has excellent cycle stability and safety. It should be noted that the features and advantages described above for the solid-state battery also apply to this electrical device and will not be elaborated here.

[0075] Next, the present invention will be described with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0076] Example 1

[0077] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyimide (PI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to a mass ratio of 75:15:10. The ball mill beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball mill beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight-average molecular weight of polyimide is 100,000, the hardness of polyimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0078] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0079] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa. After maintaining for 20 min, obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with a lithium iron phosphate positive electrode sheet and a lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0080] As Figure 1 and Figure 2 shown, the surface structure of the solid electrolyte membrane prepared in Example 1 is dense and pore-free, with a uniform thickness. The surface of the solid electrolyte membrane is flat, without obvious agglomeration phenomena and defects.

[0081] Example 2

[0082] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), thermoplastic polyurethane (TPU), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to a mass ratio of 75:15:10. The ball mill beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball mill beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight-average molecular weight of thermoplastic polyurethane is 100,000, the hardness of thermoplastic polyurethane is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0083] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0084] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate positive electrode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0085] Example 3

[0086] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyamide thermoplastic elastomer (TPAE), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to the mass ratio of 75:15:10. The ball milling beads are made of zirconia, the diameter of the zirconia ball milling beads is 2 mm to 10 mm, the mass ratio of the zirconia ball milling beads with a diameter of 2 mm to the zirconia ball milling beads with a diameter of 10 mm is 3:1, the vacuum degree of ball milling is 0.06 MPa, set the rotation speed to 300 r / min, and ball mill for 30 min to prepare a mixture. The weight-average molecular weight of the polyamide thermoplastic elastomer is 100,000, the hardness of the polyamide thermoplastic elastomer is 60A, and the particle size of the tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0087] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0088] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate positive electrode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0089] Example 4

[0090] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetherimide (PEI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to a mass ratio of 75:15:10. The ball mill beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball mill beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight-average molecular weight of polyetherimide is 100,000, the hardness of polyetherimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0091] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0092] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with a lithium iron phosphate positive electrode sheet and a lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0093] Example 5

[0094] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), thermoplastic vulcanizate (TPV), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to a mass ratio of 75:15:10. The ball mill beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball mill beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight-average molecular weight of thermoplastic vulcanizate is 100,000, the hardness of thermoplastic vulcanizate is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0095] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0096] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa. After maintaining for 20 min, an ultra-thin solid electrolyte membrane with a thickness of 25 μm is obtained. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate cathode sheet and lithium metal, hot pressing is carried out at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0097] Example 6

[0098] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), thermoplastic polyvinyl chloride elastomer (TPVC), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to the mass ratio of 75:15:10. The ball milling beads are made of zirconia. The diameter of the zirconia ball milling beads is 2 mm to 10 mm. The mass ratio of the zirconia ball milling beads with a diameter of 2 mm to the zirconia ball milling beads with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa. Set the rotation speed at 300 r / min and ball mill for 30 min to prepare a mixture. The weight average molecular weight of the thermoplastic polyvinyl chloride elastomer is 100,000, the hardness of the thermoplastic polyvinyl chloride elastomer is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm.

[0099] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate at 5 °C / min and heat up to 65 °C and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 65 °C and 30 MPa for 30 min.

[0100] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa. After maintaining for 20 min, an ultra-thin solid electrolyte membrane with a thickness of 25 μm is obtained. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate cathode sheet and lithium metal, hot pressing is carried out at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0101] Example 7

[0102] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyolefin elastomer (TPV), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to the mass ratio of 75:15:10. The ball milling beads are made of zirconia. The diameter of the zirconia ball milling beads is 2 mm to 10 mm. The mass ratio of the zirconia ball milling beads with a diameter of 2 mm to the zirconia ball milling beads with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa. Set the rotation speed at 300 r / min and ball mill for 30 min to prepare a mixture. The weight average molecular weight of the polyolefin elastomer is 100,000, the hardness of the polyolefin elastomer is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm.

[0103] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min, heat up to 65 °C, and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0104] (3) Stop heating. After naturally cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate positive electrode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0105] Example 8

[0106] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), vinyl chloride-based thermoplastic elastomer (TPE), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to a mass ratio of 75:15:10. The ball milling beads are made of zirconia, the diameter of the zirconia ball milling beads is 2 mm to 10 mm, the mass ratio of the zirconia ball milling beads with a diameter of 2 mm to the zirconia ball milling beads with a diameter of 10 mm is 3:1, the vacuum degree of ball milling is 0.06 MPa, set the rotation speed to 300 r / min, and ball mill for 30 min to prepare a mixture. The weight-average molecular weight of the vinyl chloride-based thermoplastic elastomer is 100,000, the hardness of the vinyl chloride-based thermoplastic elastomer is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0107] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min, heat up to 65 °C, and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0108] (3) Stop heating. After naturally cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate positive electrode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0109] Example 9

[0110] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), thermoplastic polyester elastomer (TPEE), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank at a mass ratio of 75:15:10. The ball milling beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball milling beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight average molecular weight of the thermoplastic polyester elastomer is 100,000, the hardness of the thermoplastic polyester elastomer is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0111] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0112] (3) Stop heating. After naturally cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa, and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with a lithium iron phosphate positive electrode sheet and a lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0113] Example 10

[0114] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetheretherketone (PEEK), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank at a mass ratio of 75:15:10. The ball milling beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball milling beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight average molecular weight of the polyetheretherketone is 100,000, the hardness of the polyetheretherketone is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0115] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0116] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa, and maintain it for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 30 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate cathode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0117] Example 11

[0118] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetherimide (PEI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball milling jar according to a mass ratio of 75:15:10. The ball milling beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball milling beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight average molecular weight of polyetherimide is 100,000, the hardness of polyetherimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0119] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min, heat up to 45 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 45 °C and a pressure of 3 MPa for 20 min;

[0120] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 5 MPa, and maintain it for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate cathode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0121] Example 12

[0122] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetherimide (PEI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball milling jar according to a mass ratio of 75:15:10. The ball milling beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball milling beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 300 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight average molecular weight of polyetherimide is 100,000, the hardness of polyetherimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0123] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 150 °C, and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 150 °C and a pressure of 40 MPa for 90 min;

[0124] (3) Stop heating. After naturally cooling to room temperature, increase the pressure of the hot pressing plate to 45 MPa, and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 25 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate positive electrode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0125] Example 13

[0126] 1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetherimide (PEI), polyvinylidene fluoride (PVDF), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill according to a mass ratio of 75:10:5:10. The ball milling beads are made of zirconia, the diameter of the zirconia ball milling beads is 2 mm to 10 mm, the mass ratio of the zirconia ball milling beads with a diameter of 2 mm to the zirconia ball milling beads with a diameter of 10 mm is 3:1, the vacuum degree of ball milling is 0.06 MPa, set the rotation speed to 300 r / min, and ball mill for 30 min to prepare a mixture. The weight average molecular weight of polyetherimide is 100,000, the hardness of polyetherimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0127] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 50 °C. Place the mixture in (1) between the heating plates, and then maintain at 50 °C and a pressure of 30 MPa for 30 min;

[0128] (3) Stop heating. After naturally cooling to room temperature, increase the pressure of the hot pressing plate to 32 MPa, and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 30 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate positive electrode sheet and lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0129] Example 14

[0130] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetherimide (PEI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to a mass ratio of 75:15:10. The ball milling beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball milling beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 200 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight-average molecular weight of polyetherimide is 100,000, the hardness of polyetherimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0131] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 35 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 35 °C and a pressure of 30 MPa for 30 min;

[0132] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa, and maintain for 20 min to obtain an ultra-thin solid electrolyte membrane with a thickness of 30 μm. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with a lithium iron phosphate positive electrode sheet and a lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0133] Example 15

[0134] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetherimide (PEI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill tank according to a mass ratio of 75:15:10. The ball milling beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball milling beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 200 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight-average molecular weight of polyetherimide is 100,000, the hardness of polyetherimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0135] (2) Fix the ultrasonically cleaned single-silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixed material in (1) between the heating plates, and then maintain at 65 °C and a pressure of 1 MPa for 30 min;

[0136] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa. After maintaining for 20 min, an ultra-thin solid electrolyte membrane with a thickness of 25 μm is obtained. This solid electrolyte membrane can be easily peeled off from the release paper. After laminating with the lithium iron phosphate positive electrode sheet and lithium metal, hot pressing is carried out at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0137] Example 16

[0138] The difference between Example 16 and Example 1 is that the mass ratio of tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyimide (PI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in Example 16 is 92:4:4.

[0139] Example 17

[0140] The difference between Example 17 and Example 1 is that the mass ratio of tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyimide (PI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is 60:20:20.

[0141] Example 18

[0142] The difference between Example 18 and Example 2 is that the release paper is replaced with a stainless steel plate, and microporous defects appear in the solid electrolyte film.

[0143] Example 19

[0144] The difference between Example 19 and Example 2 is that the molecular weight of the thermoplastic elastomer is 60,000 and the hardness is 30A.

[0145] Example 20

[0146] The difference between Example 20 and Example 2 is that the molecular weight of the thermoplastic elastomer is 50,000 and the hardness is 40A.

[0147] Comparative Example 1

[0148] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), poly(vinylidene fluoride - hexafluoropropylene) (PVDF-HFP), and LiTFSI evenly in a ball mill according to the mass ratio of 40:40:20. The ball milling beads are made of zirconia, the diameter of the zirconia ball milling beads is 2 mm to 10 mm, the mass ratio of the zirconia ball milling beads with a diameter of 2 mm to the zirconia ball milling beads with a diameter of 10 mm is 3:1, the vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 200 r / min, and ball milling is carried out for 30 min to prepare a mixed material. The particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0149] (2) Fix the ultrasonically cleaned single silicon release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0150] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa, and maintain for 20 min to obtain a solid electrolyte membrane with a thickness of 100 μm. This solid electrolyte membrane is difficult to peel into a solid electrolyte membrane. After laminating with a lithium iron phosphate positive electrode sheet and a lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery. Conventional polymer materials cannot prepare a composite solid film because of poor mechanical properties. The obtained composite solid electrolyte does not have viscoelasticity and ductility. Using the dry hot pressing and release layer method, only a 100-μm thick film can be prepared, and the breaking tensile strength is poor and it cannot be peeled off, increasing the interfacial impedance and affecting the electrochemical performance of the solid-state battery.

[0151] Comparative Example 2

[0152] (1) Mix lithium phosphorus sulfur chloride LiPSCl, polyethylene oxide (PEO), and LiTFSI evenly in a ball mill tank according to a mass ratio of 60:23:15. The ball mill beads are made of zirconia, the diameter of the zirconia ball mill beads is 2 mm to 10 mm, the mass ratio of the zirconia ball mill beads with a diameter of 2 mm to the zirconia ball mill beads with a diameter of 10 mm is 3:1, the vacuum degree of the ball mill is 0.06 MPa, set the rotation speed to 200 r / min, and ball mill for 30 min to prepare a mixture. The particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0153] (2) Fix the ultrasonically cleaned release paper on the upper and lower heating plates respectively. Set the heating rate to 5 °C / min and heat up to 65 °C, and maintain for 10 min. Place the mixture in (1) between the heating plates, and then maintain at 65 °C and a pressure of 30 MPa for 30 min;

[0154] (3) Stop heating. After natural cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa, and maintain for 20 min to obtain a solid electrolyte membrane with a thickness of 100 μm. After laminating with a lithium iron phosphate positive electrode sheet and a lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery. Conventional polymer materials cannot prepare a composite solid film because of poor mechanical properties. The obtained composite solid electrolyte does not have viscoelasticity and ductility. Using the dry hot pressing and release layer method, only a 100-μm thick film can be prepared, and the breaking tensile strength is poor and it cannot be peeled off, increasing the interfacial impedance and affecting the electrochemical performance of the solid-state battery.

[0155] Comparative Example 3

[0156] (1) Mix tantalum-doped lithium lanthanum zirconium oxide (LLZTO), polyetherimide (PEI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) evenly in a ball mill jar according to a mass ratio of 40:40:20. The ball milling beads are made of zirconia, with a diameter of 2 mm to 10 mm. The mass ratio of zirconia ball milling beads with a diameter of 2 mm to those with a diameter of 10 mm is 3:1. The vacuum degree of ball milling is 0.06 MPa, the set rotation speed is 200 r / min, and ball mill for 30 min to prepare a mixed material. Among them, the weight average molecular weight of polyetherimide is 100,000, the hardness of polyetherimide is 60A, and the particle size of tantalum-doped lithium lanthanum zirconium oxide is 500 nm;

[0157] (2) Heat the upper and lower heating plates that have been ultrasonically cleaned, set the heating rate to 5 °C / min, heat up to 65 °C, and keep it for 10 min. Place the mixed material in (1) between the heating plates, and then maintain it at 65 °C and a pressure of 30 MPa for 30 min;

[0158] (3) Stop heating. After naturally cooling to room temperature, increase the pressure of the hot pressing plate to 35 MPa, maintain it for 20 min to obtain a solid electrolyte membrane with a thickness of 100 μm. After laminating it with a lithium iron phosphate positive electrode sheet and a lithium metal, hot press at 5 MPa and 60 °C for 30 min to obtain an integrated solid-state battery.

[0159] Measure the ionic conductivity of the solid electrolyte films and the capacity retention rate of the solid-state batteries prepared in Examples 1-20 and Comparative Examples 1-3. The specific method is as follows:

[0160] Test method for ionic conductivity of solid electrolyte films: At room temperature of 25 °C and a dew point environment of -50 °C for air humidity, assemble a symmetrical battery with a steel sheet and a solid electrolyte membrane in a button cell, and set the frequency range from 0.1 Hz to 10 6 Hz and an amplitude of 10 mV on an electrochemical workstation. After testing the electrochemical impedance spectrum, obtain the ionic conductivity.

[0161] Test method for the breaking tensile strength of solid electrolyte membranes: Refer to GB / T1040 2018, use a universal mechanical property testing machine to test the breaking tensile strength of solid electrolyte membranes. After fixing the solid electrolyte membranes with a test mold, set the testing machine to stretch at a speed of 10 mm / min until the maximum force at failure for calculation.

[0162] Test method for the capacity retention rate of solid-state batteries: Charge at a rate of 0.3C and discharge at a rate of 0.3C at room temperature of 25 °C. Perform 300 cycles on the solid-state batteries of each example, record the capacity of the solid-state batteries before and after cycling, and calculate the capacity retention rate.

[0163] The performance test results of the solid electrolyte films and solid-state batteries prepared in Examples 1-20 and Comparative Examples 1-3 are shown in Table 1.

[0164] Table 1

[0165]

[0166]

[0167] From the data in Table 1, it can be seen that the fracture tensile strength and ionic conductivity of the solid electrolyte films in Examples 1-20, as well as the capacity retention rate of the solid-state batteries, are significantly higher than those in Comparative Examples 1-3. In Comparative Example 1 and Comparative Example 2, other polymer materials are used, and their solid electrolyte performance and solid-state battery performance are significantly lower than those in Examples 1-20. This shows that the solid electrolyte film of the present application has excellent electrical properties.

[0168] Furthermore, through the comparison between Example 4, Examples 11-12, and Examples 14-15, it can be seen that in the present invention, using a hot pressing temperature of 40°C to 160°C and a hot pressing pressure of 2 MPa to 40 MPa can better cooperate with the materials and processes to exert a synergistic effect. These hot pressing parameters are suitable for preparing the peelable solid electrolyte film in the present invention and can replace roll pressing. Under the synergistic effect of these process conditions and material ratios, a dense, defect-free, and ultra-thin solid electrolyte film with a thickness of ~30 μm can be prepared in one step. Therefore, the tensile strength, ionic conductivity, and capacity retention of the solid-state battery in Example 4 and Examples 11-12 are better.

[0169] Through the comparison between Example 4 and Example 13, it can be seen that adding an additional binder in the present invention will reduce the mechanical strength of the solid electrolyte film, significantly decrease the ionic conductivity, and affect the electrochemical performance of the solid-state battery.

[0170] Through the comparison between Example 4 and Examples 16-17, it can be seen that in the present invention, using a specific ratio of inorganic materials, thermoplastic elastomers, and lithium salts in combination can effectively enhance the mechanical properties and ionic conductivity of the solid electrolyte film and improve the cycle stability of the solid-state battery.

[0171] Through the comparison between Example 4 and Example 18, it can be seen that in the present invention, using a specific silicon-containing coating release paper, compared with Example 18, the release paper and the composite solid electrolyte mixture in Example 4 can produce a synergistic effect. Selecting a silicon-containing coating release layer can cause the surface of the solid electrolyte film to couple with the silicon-containing release layer during the film-forming process of heating and pressurizing in the hot pressing process, improve the dispersibility of the solid electrolyte, prevent agglomeration during the dry film-forming process, and some functional groups can contact the surface of the silicon-containing release layer to fully release the stress during the film-forming process, improving the density of the solid electrolyte film, so that it is suitable for all-solid-state batteries.

[0172] From the comparison between Example 4 and Examples 19 - 20, it can be seen that in the present invention, the thermoplastic elastomer with a molecular weight of 80,000 - 120,000 and a hardness of 40 - 60A is more suitable for preparing a peelable and independently supported solid electrolyte membrane. In this molecular weight range, it can ensure that the solid electrolyte mixture has good viscoelasticity, improve the ionic conductivity of the solid electrolyte thin film, and ensure that a thin solid electrolyte film with good mechanical strength can be obtained by a one-step forming method during the process.

[0173] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0174] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a solid electrolyte film, characterized in that, Comprising: (1) Prepare a mixed material: The mixed material includes an inorganic material, a thermoplastic elastomer, and a lithium salt. The inorganic material includes an inorganic ceramic material and / or an inorganic solid electrolyte, and the mixed material is obtained by dry mixing. (2) Hot press the mixed material to obtain a solid electrolyte film; a release layer is provided on the contact surface of the hot press equipment for hot pressing the mixed material with the mixed material.

2. The method according to claim 1, wherein The weight-average molecular weight of the thermoplastic elastomer is 20,000 to 150,000, and more preferably 80,000 to 120,000. Optionally, the hardness of the thermoplastic elastomer is 0A to 80A, preferably 0A to 65A, and more preferably 40 to 60A. Optionally, the thermoplastic elastomer includes at least one of polyimide, thermoplastic polyurethane, polyamide thermoplastic elastomer, polyetherimide, polyetheretherketone, thermoplastic vulcanizate, polyvinyl chloride thermoplastic elastomer, polyolefin elastomer, vinyl chloride thermoplastic elastomer, and thermoplastic polyester elastomer. Optionally, the inorganic ceramic material includes at least one of metal oxides, nitrides, carbides, borides, and non-metal oxides. Optionally, the inorganic solid electrolyte includes at least one of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, nitride solid electrolytes, and borate solid electrolytes. Optionally, the particle sizes of the inorganic ceramic material and the inorganic solid electrolyte are independently 300 nm to 3 μm. Optionally, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, and lithium difluorooxalate borate. Optionally, the hot press equipment includes a first heating plate and a second heating plate. The mixed material is placed between the first heating plate and the second heating plate for hot pressing, and release layers are respectively provided on the opposite surfaces of the first heating plate and the second heating plate.

3. The method according to claim 2, wherein The metal oxide includes at least one of aluminum oxide, titanium dioxide, zirconium dioxide, and magnesium oxide. Optionally, the nitride includes at least one of silicon nitride, titanium nitride, aluminum nitride, boron nitride, magnesium nitride, and zirconium nitride. Optionally, the carbide includes at least one of silicon carbide and boron carbide. Optionally, the non-metal oxide includes at least one of silicon dioxide and boron oxide. Optionally, the boride includes at least one of silicon boride, vanadium boride, magnesium boride, and titanium boride.

4. The method according to claim 1 or 2, characterized in that, In step (1), the mass ratio of the inorganic material to the thermoplastic elastomer is (90 - 70):(10 - 30). Optionally, the mass ratio of the thermoplastic elastomer to the lithium salt is (5 - 1):

1. Optionally, the dry mixing method is grinding. Optionally, the grinding includes ball milling. The vacuum degree of the ball milling is not greater than 0.1 MPa, the rotation speed of the ball milling is 200 r / min to 600 r / min, and the ball milling time is 20 min to 180 min. Optionally, the mixed material does not contain a binder.

5. The method according to claim 1 or 2, characterized in that, In step (2), the temperature of the hot pressing is 40°C to 160°C, the time of the hot pressing is 20 min to 90 min, and the pressure of the hot pressing is 2 MPa to 40 MPa; Optionally, the release layer includes a coated release paper, a glassine release paper, a CCK release paper, a single-silicon release paper, a double-silicon release paper, a silicone oil paper, a release film, a fluorine-based release film, an anti-static paper, a PET film, a sulfur-free paper, a kraft paper, an aluminum-plastic film, a rust-proof paper, or a stainless steel plate, preferably includes a single-silicon release paper, a double-silicon release paper, a silicone oil paper, a silicon-containing release film, or a sulfur-free paper; Optionally, after hot pressing and cooling the mixed material by using the hot pressing equipment, cold pressing is carried out; Optionally, the pressure of the cold pressing is 10 MPa to 50 MPa, and the time of the cold pressing is 10 min to 60 min; Optionally, the thickness of the solid electrolyte film is 20 μm to 80 μm.

6. A solid electrolyte film, characterized in that, It is obtained by using the method for preparing a solid electrolyte film according to any one of claims 1-5.

7. An electrode assembly, characterized in that, It includes a pole piece and the solid electrolyte film according to claim 6.

8. A method for preparing an electrode assembly, characterized in that, The solid electrolyte film according to claim 6 is hot pressed on the surface of the pole piece, and a release layer is provided on the contact surface of the hot pressing equipment for hot pressing the solid electrolyte film, so as to obtain an electrode assembly.

9. A solid-state battery, characterized in that, It includes the solid electrolyte film according to claim 6, or the electrode assembly according to claim 7, or the electrode assembly prepared by using the method according to claim 8.

10. An electrical device, characterized in that, It includes the solid-state battery according to claim 9.

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