An ultra-thin flexible solid-state electrolyte film stabilized against lithium based on high dielectric oxide backbone

Abstract

The application discloses a lithium-stable ultra-thin flexible solid-state electrolyte film based on a high-dielectric oxide framework, and belongs to the technical field of solid-state electrolytes. The ultra-thin flexible solid-state electrolyte film comprises a framework composed of a high-dielectric oxide and a polymer electrolyte formed in situ and solidified, wherein the polymer electrolyte covers the surface of the framework and fills the pores of the framework. Thanks to the high-dielectric oxide framework, the ultra-thin flexible solid-state electrolyte film has high lithium stability, high ionic conductivity, high ionic transference number and long cycle life, and is very suitable for preparing solid-state batteries with high volume and / or high mass energy density.

Description

Technical Field

[0001] This application belongs to the field of solid electrolyte technology, specifically relating to an ultrathin flexible solid electrolyte film with lithium stabilization based on a high dielectric oxide framework, and also to the preparation method and application of the ultrathin flexible solid electrolyte film. Background Technology

[0002] Composite solid-state electrolytes (CSSEs) are considered one of the key materials for achieving high safety and high energy density solid-state lithium batteries because they combine the advantages of inorganic solid-state electrolytes and polymer electrolytes.

[0003] In existing technologies, the inorganic components of composite electrolytes commonly use conventional solid-state electrolytes (such as garnet-type, LISICON-type, NASICON-type, etc.) or inorganic nanofillers such as boron nitride and alumina. These traditional fillers face insurmountable challenges in dispersibility and interfacial compatibility, severely restricting the development of solid-state batteries. Specifically, due to the high surface energy of inorganic nanofillers (such as ceramic particles), they are prone to agglomeration in polymer matrices, leading to uneven filler dispersion and severely compromising the uniformity and mechanical stability of the electrolyte structure. This uneven structure directly results in the formation of high-resistivity solid-solid interfaces within the electrolyte and between the electrolyte and the electrode, resulting in poor interfacial compatibility and a sharp increase in impedance during battery cycling. Furthermore, these structural and interfacial defects obstruct lithium-ion transport paths, making it difficult to achieve the required ionic conductivity, especially the lithium-ion transference number, for practical applications, and hindering effective and long-term stable compatibility with lithium metal anodes.

[0004] More importantly, traditional filler systems struggle to address the complex interfacial issues in solid-state batteries. Interfacial side reactions, dendrite formation, and space charge layers (SCLs) severely hinder efficient ion transport, leading to direct battery failure or safety hazards. Strategies are urgently needed to regulate the composition and structure of the interfacial layers within solid-state batteries to improve ion conductivity and ion transport kinetics at the interfaces.

[0005] The emergence of functional high-dielectric materials exhibiting ferroelectric effects offers a novel approach to solving the aforementioned challenges. Ion transport is primarily influenced by the number of charge carriers, concentration gradient, and electric field distribution at the interface. These materials can actively adapt to and regulate the non-uniform transport of ions at multiphase interfaces, effectively modulating and promoting ion transport, suppressing the space charge layer at the positive and negative electrode multiphase interfaces, effectively controlling the distribution of electric field and cation flux at the interface, and suppressing non-uniform cation deposition at the negative electrode interface. Furthermore, high-dielectric materials can generate an internal electric field under the influence of an electric field, significantly promoting the dissociation efficiency of lithium salts, increasing the concentration of mobile lithium ions, and thus simultaneously improving the ionic conductivity and lithium-ion transference number of the electrolyte.

[0006] In the existing technology, some researchers have attempted to solve the problem of inorganic powder agglomeration by preparing ceramic material skeletons and obtaining composite electrolyte films based on the skeletons through in-situ curing. However, since the skeleton materials still use conventional solid electrolytes or traditional inert fillers such as boron nitride and alumina, their improvement effect on key electrolyte performance (such as lithium-ion conductivity, lithium-ion transference number, and lithium deposition and stripping stability) is not significant, and they have failed to fundamentally break through the performance limitations of traditional fillers.

[0007] Therefore, developing a composite solid electrolyte that leverages the advantages of high dielectric materials while also possessing excellent mechanical flexibility, high ionic conductivity, high lithium-ion transference number, and long-term stable compatibility with lithium metal anodes remains a pressing technical challenge in this field. Summary of the Invention

[0008] In view of this, the primary objective of this application is to provide an ultrathin flexible solid electrolyte film based on a high dielectric oxide framework. This ultrathin flexible solid electrolyte film has high lithium stability, high ionic conductivity, high ion transference number and long cycle life, which is of great significance for the preparation of solid-state batteries with high volumetric and / or high energy density.

[0009] To achieve the above objectives, this application adopts the following technical solution:

[0010] One aspect of this application discloses an ultrathin flexible solid electrolyte film based on a high-dielectric oxide framework, comprising:

[0011] The framework, the framework being composed of a relative permittivity Composed of high-dielectric oxides with r > 20;

[0012] And a polymer electrolyte formed by in-situ curing, wherein the polymer electrolyte covers the surface of the skeleton and fills the pores of the skeleton;

[0013] The high dielectric oxide is at least one of barium titanate, strontium titanate, potassium niobate, lead titanate, lead zirconate titanate, lithium niobate, and tantalum oxide.

[0014] In this application, the polarization effect of high-dielectric oxides is utilized to promote lithium salt dissociation and rapid lithium ion transport. Simultaneously, the space charge layer strength between the electrode and the polymer is weakened, reducing the interfacial transport barrier and facilitating the dissociation of Lithium ions. + It can spontaneously and uniformly migrate at the interface between two phases, promoting the cross-phase transport and deposition of lithium ions.

[0015] This application discloses, in another aspect, a method for preparing the ultrathin flexible solid electrolyte film described in this application, comprising the following steps:

[0016] A casting slurry is prepared, the casting slurry comprising a polymer binder, high dielectric oxide ceramic powder, and a solvent;

[0017] After the cast slurry is cast and dried to form a film, the polymer binder is removed by a first ultrafast high-temperature sintering in a non-reactive atmosphere, followed by a second ultrafast high-temperature sintering in an oxidizing atmosphere to obtain a high-dielectric oxide skeleton.

[0018] Prepare an in-situ curing liquid, wherein the in-situ curing liquid comprises a polymerizable monomer, a crosslinking agent, an electrolyte, and an initiator;

[0019] The high-dielectric oxide framework is placed in the in-situ curing liquid, fully immersed, and then cured in situ to obtain an ultrathin flexible solid electrolyte film.

[0020] In this application, a porous framework of high-dielectric oxide ceramic powder is prepared by slurry casting, drying, and ultrafast high-temperature sintering. This preparation process not only effectively avoids particle agglomeration and ensures unobstructed lithium-ion transport paths, but also significantly shortens the sintering time through ultrafast high-temperature sintering, and can control grain size and suppress element volatilization. The synergistic effect of these two factors further enhances the role of the high-dielectric oxide framework and improves the overall performance of solid-state batteries.

[0021] This application also discloses the application of ultrathin flexible solid electrolyte films as described in this application in the preparation of solid-state batteries.

[0022] Another aspect of this application discloses a solid-state battery containing the ultrathin flexible solid-state electrolyte film described in this application.

[0023] The beneficial effects of this application are:

[0024] This application uses a high-dielectric oxide as the inorganic component of a composite solid electrolyte. The high-dielectric-constant ceramic material can generate strong polarization under an external electric field, forming a local electric field, thereby effectively weakening the Li... + With anions (such as TFSI) - PF6 - The electrostatic interaction between lithium salts promotes lithium salt dissociation and increases the number of free Li.+ Concentration increases the electrolyte's ionic conductivity, promoting rapid lithium-ion transport and thus enhancing solid-state battery performance. Simultaneously, the polarization effect of high-dielectric-constant ceramic materials weakens the space charge layer strength between the electrode and the polymer, lowering the interfacial transport barrier and facilitating the dissociation of Li-ion ions. + It can spontaneously and uniformly migrate at the interface between two phases, promoting the cross-phase transport and deposition of lithium ions, thus enabling the obtained ultrathin flexible solid electrolyte film to be well applied in lithium metal solid batteries. Attached Figure Description

[0025] Figure 1 This is a photograph of the slurry coating process during the preparation of the high-dielectric oxide framework in a preferred embodiment of this application.

[0026] Figure 2 This is a photograph of the slurry coating and drying process during the preparation of the high-dielectric oxide framework in a preferred embodiment of this application.

[0027] Figure 3 The images show various stages of the skeleton disc fabrication process in a preferred embodiment of this application: before sintering (left image), after sintering in an inert atmosphere (middle image), and after sintering in air (right image).

[0028] Figure 4 The results of the ionic conductivity (30°C) test of EPTA-BTO and EPTA samples in a preferred embodiment of this application are shown.

[0029] Figure 5 The lithium-ion transference number test results are for an ETPTA-BTO sample in a preferred embodiment of this application.

[0030] Figure 6 The lithium-ion transference number test results of the ETPTA sample in a preferred embodiment of this application are shown.

[0031] Figure 7 In a preferred embodiment of this application, the Li||Li symmetric cell assembled with ETPTA-BTO operates at 0.2 mA·cm⁻¹. -2 Current density, 0.1 mAh·cm -2 Cyclic performance at capacity density. Detailed Implementation

[0032] The embodiments of this application will be clearly and completely described below. The technical solutions in the embodiments described below are exemplary and only possible technical implementations of this application, not all possible implementations. Those skilled in the art can combine the embodiments of this application to obtain other embodiments without creative effort, and these embodiments are also within the protection scope of this application.

[0033] The first aspect of this application discloses an ultrathin flexible solid electrolyte film based on a high-dielectric oxide framework. This ultrathin flexible solid electrolyte film includes a framework composed of high-dielectric oxides, on which a polymer electrolyte is in-situ cured to form a polymer electrolyte. The polymer electrolyte covers the surface of the framework and fills the pores within the framework. This overcomes the problem that inorganic nanofillers (such as ceramic particles) have high surface energy and are prone to agglomeration in a polymer matrix, leading to uneven filler dispersion, thus obtaining a uniform ultrathin flexible solid electrolyte film.

[0034] More importantly, the outstanding contribution of this application is that the framework is composed of high dielectric oxide, which promotes the dissociation of lithium salt, improves ionic conductivity and transference number, alleviates the space charge layer, promotes the transport of lithium ions at the interface, facilitates lithium ion deposition and stripping, and achieves long-term stability of lithium metal.

[0035] In this application, the "skeleton" is a porous ceramic skeleton formed by ultrafast high-temperature sintering of high-dielectric oxide ceramic powder, which has interconnected channels.

[0036] In this application, "high dielectric oxide" refers to a oxide with a relative permittivity. Oxygen-containing compounds with r > 20. Among them, the relative permittivity ( r) is the absolute permittivity ( ) and free space permittivity ( Compared to 0), such materials can generate stronger polarization under the action of an electric field, which helps to promote the dissociation of lithium salts and improve ionic conductivity and transference number.

[0037] In some specific examples, the high dielectric oxide includes at least one of barium titanate (BaTiO3), strontium titanate (SrTiO3), potassium niobate (KNbO3), lead titanate (PbTiO3), lead zirconate titanate (PZT), lithium niobate (LiNbO3), and tantalum oxide (Ta2O5), but is not limited thereto.

[0038] Furthermore, in the framework, the particle size of the high-dielectric oxide is 20~500nm, for example, it can be any particle size or a range between any two particle sizes selected from 20nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, and 500nm; more preferably, the particle size of the high-dielectric oxide is 100~300nm, for example, it can be any particle size or a range between any two particle sizes selected from 100nm, 120nm, 140nm, 160nm, 180nm, 200nm, 220nm, 240nm, 260nm, 280nm, and 300nm. If the particle size is too large (e.g., greater than 500nm), on the one hand, it is easy to settle in the casting slurry, resulting in uneven film thickness; on the other hand, the sintering activity is reduced, making it difficult to obtain a uniform microstructure, and the mechanical strength and dielectric enhancement effect of the framework will decrease. If the particle size is too small (e.g., less than 20 nm), the high surface energy of the nanoparticles will lead to severe agglomeration, which is difficult to completely avoid even with the addition of dispersants. After sintering, defects are easily formed, reducing the reliability and electrochemical performance of the framework. Therefore, the appropriate particle size of the high-dielectric oxide powder is very important for forming a high-quality framework. The appropriate particle size range can be determined experimentally by those skilled in the art.

[0039] Furthermore, the specific thickness of the skeleton can be adjusted by those skilled in the art based on experimental purposes and research needs through controllable fabrication processes. In some specific examples of this application, the skeleton thickness is preferably 10-50 μm, for example, it can be any thickness or a range between any two thicknesses selected from 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, and 50 μm. More preferably, the skeleton thickness is 10-20 μm, for example, it can be any thickness or a range between any two thicknesses selected from 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, and 20 μm.

[0040] In this application, the polymer electrolyte can be obtained by in-situ curing of polymerizable monomers well known in the art, including but not limited to ethoxylated trimethylolpropane triacrylate (ETPTA), polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), diethoxyethyl acrylate (DEGA), tripropylene glycol diacrylate (TPGDA), polyethylene glycol methyl ether methacrylate (PEGMEMA), methyl methacrylate (MMA), pentaerythritol tetraacrylate (PETEA), 1,3-dioxane (DOL), hydroxyethyl methacrylate (HEMA), trimethylolpropane triacrylate (TMPTA), dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA), 1,4 - At least one of butanediol diacrylate (BDDA), triethylene glycol divinyl ether (TEGDVE), diethylene glycol divinyl ether (DEGDVE), and ethylene glycol divinyl ether (EGDVE), and those skilled in the art can select the appropriate type based on experimental purposes and product needs.

[0041] The second aspect of this application discloses a method for preparing an ultrathin flexible solid electrolyte film as described in this application. The preparation of the ultrathin solid electrolyte film in this application employs a casting method combined with ultrafast high-temperature sintering (UHS) for framework preparation, thereby obtaining a large-size, ultrathin solid electrolyte film with excellent performance. The specific method mainly includes the following steps:

[0042] <Preparation of Casting Slurry>

[0043] In this application, the "cast slurry" refers to a suspension in which the components used to form the skeleton are uniformly dispersed and mixed in a solvent to form a stable, uniform suspension with a certain fluidity and viscosity, which is the basis of the casting film process.

[0044] In this application, the casting paste includes a polymer binder, high dielectric oxide ceramic powder, and a solvent. In addition, functional additives such as plasticizers, dispersants, and defoamers can be selected as needed to add to it to obtain a suitable casting paste.

[0045] The types of high-dielectric oxide ceramic powders used in the casting slurry are as described above and will not be elaborated further here.

[0046] The polymer binder may be any known or independently developed polymer binder in the art, without particular limitation. Specific examples include at least one of polyvinyl butyral (PVB), polyvinyl alcohol (PVA), and ethyl cellulose, but are not limited thereto.

[0047] Furthermore, the solvent should be an organic solvent capable of dissolving the polymer binder without chemically reacting with the high-dielectric oxide ceramic powder. Specifically, it can be adapted according to the polymer binder and the high-dielectric oxide ceramic powder. As a specific example, the solvent may be at least one of ethanol, isopropanol, n-butanol, methanol, toluene, xylene, methyl ethyl ketone, acetone, and cyclohexanone, but is not limited to these.

[0048] It should be understood that the content of each component can be adjusted or selected according to the specific experimental purpose and product performance requirements when preparing the casting slurry. As a specific example, the proportion of polymer binder in the casting slurry is 5-15 wt%, which can be any value or a range between any two values ​​from 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt%, to 15 wt%. The proportion of high-dielectric oxide ceramic powder is 40-60 wt%, for example, it can be any value or a range between any two values ​​from 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, to 60 wt%; the proportion of solvent is 30-50 wt%. It is understood that the sum of the contents of all components should satisfy 100%.

[0049] <Preparation of High-Dielectric Oxide Frameworks>

[0050] After the cast slurry described above is cast and dried to form a film using methods commonly used in the art, the polymer binder is removed by a first ultrafast high-temperature sintering in a non-reactive atmosphere, followed by a second ultrafast high-temperature sintering in an oxidizing atmosphere to obtain a high-dielectric oxide skeleton.

[0051] In this application, "ultrafast high-temperature sintering (UHS)" refers to the use of heating (such as a carbon heater or graphite felt) to generate instantaneous ultra-high temperatures and ultra-high heating rates, thereby achieving densification sintering of powder materials in an extremely short time (typically 10 seconds to several minutes). In this application, its application to the preparation of high-dielectric oxide frameworks not only shortens sintering time, achieving high efficiency and low energy consumption, but more importantly, it enables precise control of grain size and suppression of volatile elements, thus ensuring that the framework possesses optimal dielectric properties and mechanical strength.

[0052] In this application, two ultrafast high-temperature sintering processes were performed. The first ultrafast high-temperature sintering was carried out in a non-reactive atmosphere to rapidly carbonize the polymer, remove the binder, and initially establish neck connections between ceramic particles, forming a porous framework with a certain strength. The "non-reactive atmosphere" refers to at least one of nitrogen and rare gases (such as helium, argon, etc.). The specific temperature can be adjusted and selected according to the type of polymer binder, etc. As a specific example, the temperature of the first ultrafast high-temperature sintering was 800~1400℃.

[0053] Furthermore, a second ultrafast high-temperature sintering is carried out in an oxidizing atmosphere. The purpose is to oxidize and remove the carbon remaining after the first sintering, and to re-oxidize the reduced framework components as much as possible, thereby improving the purity and insulation of the framework to obtain a high-dielectric oxide framework with excellent performance. As a specific example, the temperature of the second ultrafast high-temperature sintering is 800~1200℃.

[0054] <Preparation of In-situ Curing Solution>

[0055] In this application, the "in-situ curing solution" refers to a precursor solution containing polymerizable monomers, initiators, and liquid electrolytes. Under specific conditions (such as heating or light exposure), the monomers can undergo a polymerization reaction to form a solid or gel-like polymer electrolyte.

[0056] In some specific examples of this application, the in-situ curing liquid includes polymerizable monomers, crosslinking agents, electrolytes, and initiators.

[0057] Polymerizable monomers typically refer to monomers containing unsaturated bonds such as double bonds that can undergo free radical polymerization or cationic polymerization. Specific examples include at least one of the following: ethoxylated trimethylolpropane triacrylate (ETPTA), polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), diethoxyethyl acrylate (DEGA), tripropylene glycol diacrylate (TPGDA), polyethylene glycol methyl ether methacrylate (PEGMEMA), methyl methacrylate (MMA), pentaerythritol tetraacrylate (PETEA), 1,3-dioxane (DOL), hydroxyethyl methacrylate (HEMA), trimethylolpropane triacrylate (TMPTA), dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA), 1,4-butanediol diacrylate (BDDA), triethylene glycol divinyl ether (TEGDVE), diethylene glycol divinyl ether (DEGDVE), and ethylene glycol divinyl ether (EGDVE), but are not limited to these.

[0058] Specific examples of the crosslinking agent include at least one of ethoxylated trimethylolpropane triacrylate (ETPTA), polyethylene glycol dimethacrylate (PEGDMA), and trimethylolpropane triacrylate (TMPTA), or other crosslinking monomers containing two or more functional groups, but are not limited thereto.

[0059] The electrolyte can be any known or independently developed liquid electrolyte for lithium-ion batteries in the art. For example, it can be a carbonate (EC, DEC, DMC, EMC) or ether (DOL, DME) solvent system containing dissolved lithium salts (such as LiPF6, LiTFSI, LiFSI, etc.), and various film-forming additives (such as FEC, VC, etc.) can be selectively added. In some specific examples, the added electrolyte composition is: a mixture of EC and DEC solvents, dissolving 1 mol / L LiPF6, and adding 10 vol% FEC.

[0060] In this application, a suitable initiator is selected according to the type of polymerizable monomer and the polymerization initiation method, such as a photoinitiator or a thermal initiator. For example, 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP) is an exemplary photoinitiator; for thermal initiators, azobisisobutyronitrile (AIBN) is an exemplary initiator, but it is not limited to the above examples.

[0061] It is understood that the controllable preparation of polymeric electrolytes can be achieved by adjusting the concentration of polymerizable monomers in the in-situ curing solution. A suitable ratio of the in-situ curing solution can improve the performance of ultrathin flexible solid electrolyte films, and those skilled in the art possess the capability to perform such optimization. For example, in some specific examples, the polymerizable monomer content in the in-situ curing solution is 10-75 vol%, such as any percentage or a range between any two of the following: 10 vol%, 15 vol%, 20 vol%, 25 vol%, 30 vol%, 35 vol%, 40 vol%, 45 vol%, 50 vol%, 55 vol%, 60 vol%, 65 vol%, 70 vol%, 75 vol%. The crosslinking agent content is 1-15 vol%, such as any percentage or a range between any two of the following: 1 vol%, 2 vol%, 3 vol%, 4 vol%, 5 vol%, 6 vol%, 7 vol%, 8 vol%, 9 vol%, 10 vol%, 11 vol%, 12 vol%, 13 vol%, 14 vol%, 15 vol%. The electrolyte concentration is 25-85 vol%, for example, any concentration within the range of 25 vol%, 30 vol%, 35 vol%, 40 vol%, 45 vol%, 50 vol%, 55 vol%, 60 vol%, 65 vol%, 70 vol%, 75 vol%, 80 vol%, or 85 vol%, or any two of these concentrations. The initiator concentration is 0.1-3 wt% (based on the total mass of polymerizable monomers and crosslinking agents).

[0062] <Preparation of Ultrathin Flexible Solid Electrolyte Films>

[0063] In this step, the skeleton described above is placed in an in-situ curing solution and fully immersed. The specific immersion time can be adjusted as needed. It is then removed and cured in situ under photo-initiated or thermal-initiated conditions to obtain an ultrathin flexible solid electrolyte film. This allows the polymer electrolyte to cover the surface of the skeleton and fill the pores within it.

[0064] The ultrathin flexible solid electrolyte film described in this application has a thickness of no more than 50 μm. As a preferred example, its thickness is 10-20 μm, for example, it can be any thickness among 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, and 20 μm or any range between two thicknesses.

[0065] This application further discloses a solid-state battery comprising the ultrathin flexible solid-state electrolyte film described in this application. It is understood that the solid-state battery also includes a positive electrode and a negative electrode, and there are no particular limitations on the positive and negative electrodes. However, the preferred negative electrode is lithium metal or a lithium alloy (such as lithium-indium alloy, lithium-tin alloy, etc.), which, thanks to the excellent lithium stability of the ultrathin flexible solid-state electrolyte film, can be better matched with lithium metal solid-state batteries.

[0066] The present application will be further illustrated below with reference to specific embodiments. It should be noted that the specific embodiments below are for illustrative purposes only and do not limit the scope of the present application in any way.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0068] In addition, unless otherwise specified, methods without detailed conditions or steps are conventional methods, and the reagents and materials used are commercially available.

[0069] Example 1: Ultrathin Flexible Solid Electrolyte Film Based on BaTiO3 High Dielectric Oxide Framework

[0070] 1.1 Preparation of high-dielectric oxide framework

[0071] According to the mass ratio, take 3 parts BaTiO3 powder, 0.076 parts dispersant triethanolamine, and 2.44 parts solvent anhydrous ethanol, mix and stir evenly, then add 0.342 parts binder PVB and 0.357 parts plasticizer dibutyl phthalate, and stir and mix evenly to obtain a slurry; coat the slurry onto a polyethylene terephthalate (PET) substrate with a coating thickness of 80 μm. Figure 1 The film after natural drying (peeled from the PET substrate) Figure 2 ), and cut into circles with a diameter of 14cm ( Figure 3 The circular piece in the middle left image is then sintered in an inert atmosphere using ultrafast high temperature (1200℃, 3s) to form a dark blue skeleton circular piece. Figure 3 The disc in the middle of the image), the resulting disc was then sintered in air at an ultrafast high temperature (1000℃, 3s) to form a white high-dielectric BaTiO3 framework ( Figure 3 (The circle in the middle right image).

[0072] 1.2 Preparation of in-situ curing solution

[0073] According to volume proportions, take 120 parts ETPTA, 740 parts electrolyte (solvent is EC and DEC in a volume ratio of 1:1, dissolve 1 mol / L LiPF6, and add 10 vol% FEC) and 15 parts HMPP, mix them, and stir evenly to obtain the in-situ curing solution.

[0074] 1.3 Preparation of ultrathin flexible solid electrolyte films

[0075] The BaTiO3 skeleton discs prepared in section 1.1 were immersed in the in-situ curing solution prepared in section 1.2. After immersion for half an hour, they were removed and cured with a UV lamp (UV light intensity of 100 μW / cm²). 2 The in-situ curing solution was cured by irradiation with ultraviolet light (at a wavelength of 320 nm) for 3 minutes to obtain an ultrathin flexible solid electrolyte film, denoted as ETPTA-BTO. Meanwhile, the in-situ curing solution from step 1.2 was directly cured with ultraviolet light to obtain a pure ETPTA electrolyte film as a comparison.

[0076] Example 2: Ultrathin Flexible Solid Electrolyte Film Based on SrTiO3 High Dielectric Oxide Framework

[0077] 2.1 Preparation of high-dielectric oxide framework

[0078] According to the mass ratio, take 3 parts of SrTiO3 powder, 0.076 parts of dispersant triethanolamine and 2.44 parts of solvent anhydrous ethanol, mix and stir evenly, then add 0.342 parts of binder PVB and 0.357 parts of plasticizer dibutyl phthalate, and stir and mix evenly to obtain a slurry; coat the slurry with a coating thickness of 100 μm on a polyethylene terephthalate (PET) substrate, and cut the film (peeled from the PET substrate) after natural drying into a disc with a diameter of 14 cm, and then sinter it into a skeleton disc in an inert atmosphere using ultrafast high temperature (1200℃, 3s). Subsequently, sinter the obtained disc in air at ultrafast high temperature (1000℃, 3s) to form a high dielectric SrTiO3 skeleton.

[0079] 2.2 Preparation of in-situ curing solution

[0080] According to volume proportions, take 750 parts DEGA, 250 parts electrolyte (solvent is FEC, dissolve 1mol / L LiPF6) and 15 parts HMPP, mix them, stir evenly, and obtain in-situ curing solution.

[0081] 2.3 Preparation of ultrathin flexible solid electrolyte films

[0082] The SrTiO3 skeleton discs prepared in section 2.1 were immersed in the in-situ curing solution prepared in section 2.2. After immersion for half an hour, they were removed and cured with a UV lamp (UV light intensity of 100 μW / cm²). 2The in-situ curing solution was cured by irradiation with ultraviolet light (at a wavelength of 320 nm) for 3 minutes to obtain an ultrathin flexible solid electrolyte film, denoted as PDEGA-STO. Meanwhile, the in-situ curing solution from section 2.2 was directly cured with ultraviolet light to obtain a pure PDEGA electrolyte film as a comparison.

[0083] Example 3: Ultrathin Flexible Solid Electrolyte Film Based on PbTiO3 High Dielectric Oxide Framework

[0084] 3.1 Preparation of high-dielectric oxide framework

[0085] According to the mass ratio, take 3 parts of PbTiO3 powder, 0.076 parts of dispersant triethanolamine and 2.44 parts of solvent anhydrous ethanol, mix and stir evenly, then add 0.342 parts of binder PVB and 0.357 parts of plasticizer dibutyl phthalate, and stir and mix evenly to obtain a slurry; coat the slurry with a coating thickness of 100 μm on a polyethylene terephthalate (PET) substrate, and cut the film (peeled from the PET substrate) after natural drying into a disc with a diameter of 14 cm, denoted as PTO-PF, and then sinter it in an inert atmosphere at ultrafast high temperature (1000℃, 3s) to form a dark blue skeleton disc. Subsequently, sinter the obtained disc in air at ultrafast high temperature (900℃, 3s) to form a high dielectric PbTiO3 skeleton.

[0086] 3.2 Preparation of in-situ curing solution

[0087] According to volume proportions, take 120 parts ETPTA, 740 parts electrolyte (solvent is EC and DEC in a volume ratio of 1:1, dissolve 1 mol / L LiTFSI and add 10 vol% FEC) and 15 parts HMPP, mix them, stir evenly, and obtain the in-situ curing solution.

[0088] 3.3 Preparation of ultrathin flexible solid electrolyte films

[0089] The PbTiO3 framework discs prepared in section 3.1 were immersed in the in-situ curing solution prepared in section 3.2. After immersion for half an hour, they were removed and cured with a UV lamp (UV light intensity of 100 μW / cm²). 2 The in-situ curing solution was cured by irradiation with ultraviolet light (at a wavelength of 320 nm) for 3 minutes to obtain an ultra-thin flexible solid electrolyte film, denoted as ETPTA-PTO-UHS.

[0090] Meanwhile, the PTO-PF prepared in section 3.1 was sintered in a muffle furnace (parameters: heating rate 5℃ / min, annealing temperature 1000℃, holding time 1h) to obtain the PTO-FS framework. Subsequent steps were the same as in sections 3.2 and 3.3 to obtain a solid electrolyte film, denoted as ETPTA-PTO-FS.

[0091] In addition, the three PbTiO3 powders in section 3.1 were replaced with alumina powder, and a solid electrolyte film was prepared using the same steps as EPTA-PTO-UHS, denoted as EPTA-Al2O3-UHS; a composite solid electrolyte film was prepared using the same steps as EPTA-PTO-FS, denoted as EPTA-Al2O3-FS.

[0092] Performance testing

[0093] 1. The ultrathin solid electrolyte disc from the embodiment is placed between two steel pads to form an SS||SS symmetric battery.

[0094] The impedance of the SS||SS symmetrical cell was measured using DHElecCHem, and the lithium-ion conductivity of the ETPTA-BTO ultrathin solid electrolyte was measured at 30℃ to be 4.12 mS·cm. -1 Compared to the ionic conductivity (2.85 mS·cm) of solid electrolyte cured with pure in-situ curing solution, -1 Nearly twice as high ( Figure 4 PDEGA-STO also has twice the ionic conductivity of the control sample PDEGA; the ultrafast high-temperature sintering sample has a higher sintering efficiency of only tens of seconds, while the furnace-fired sample requires 7.5 hours and has worse performance (Table 1); at the same time, the composite electrolyte obtained by preparing the framework using alumina powder with a relative permittivity of 9 has a significantly lower ionic conductivity than the composite electrolyte prepared by the high permittivity oxide framework.

[0095] 2. The ultrathin solid electrolyte membrane from the embodiment is placed between two lithium sheets to form a Li||Li symmetric battery.

[0096] (1) The Li||Li symmetric cell was placed in an oven, and the battery impedance was measured first at 30°C. Then, the DC polarization test was performed on the battery, followed by another impedance test. The lithium-ion transference number of the electrolyte was calculated. The lithium-ion transference number of ETPTA-BTO was as high as 0.61 ( Figure 5 ), far higher than ETPTA's 0.05 ( Figure 6 Meanwhile, the lithium-ion transference number of PDEGA-STO is as high as 0.4, which is much higher than that of PDEGA (0.06) (Table 1); and the lithium-ion transference number of the composite electrolyte prepared by using alumina powder with a relative dielectric constant of 9 is significantly lower than that of the composite electrolyte prepared by oxide framework with high dielectric constant.

[0097] (2) The Li||Li battery assembled with the ETPTA-BTO sample was tested at 30℃ with an energy of 0.2 mA·cm⁻¹. -2 Current density, 0.1 mAh·cm -2 The capacity density of the battery was tested in a cycle test, with a cycle time exceeding 1400 hours. Figure 7As shown, this indicates that it can stably deposit and strip lithium.

[0098] Table 1 Performance of the composite electrolyte in the examples

[0099]

[0100] The above results demonstrate that the continuous high-dielectric oxide framework in this application not only provides physical support but also significantly promotes the lithium-ion conduction process, facilitates lithium salt dissociation, and substantially increases the lithium-ion transference number. Furthermore, it exhibits excellent ability to suppress lithium dendrite formation and long-term cycling stability.

[0101] As can be seen from the examples, the ultrathin solid electrolyte film in this application has high ionic conductivity, high ion transport number, long lithium symmetric cycle life, and high sample preparation efficiency, indicating that the preparation method and the ultrathin solid electrolyte film obtained in this application can be applied to solid-state batteries and have industrial application prospects.

[0102] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An ultrathin flexible solid electrolyte film based on a high-dielectric oxide framework, characterized in that, include: A continuous high-dielectric oxide framework, the framework being composed of a relative permittivity Composed of high-dielectric oxides with r > 20; And a polymer electrolyte formed by in-situ curing, wherein the polymer electrolyte covers the surface of the skeleton and fills the pores of the skeleton; The high dielectric oxide is at least one of barium titanate, strontium titanate, potassium niobate, lead titanate, lead zirconate titanate, lithium niobate, and tantalum oxide.

2. The ultrathin flexible solid electrolyte film as described in claim 1, characterized in that, The high-dielectric oxide has a particle size of 20~500nm.

3. The ultrathin flexible solid electrolyte film as described in claim 1, characterized in that, The thickness of the skeleton is 10~50μm.

4. The ultrathin flexible solid electrolyte film as described in claim 1, characterized in that, The polymer electrolyte is formed by in-situ curing of at least one polymerizable monomer selected from ethoxylated trimethylolpropane triacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, diethoxyethyl acrylate, tripropylene glycol diacrylate, polyethylene glycol methyl ether methacrylate, methyl methacrylate, pentaerythritol tetraacrylate, 1,3-dioxane, hydroxyethyl methacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, triethylene glycol divinyl ether, diethylene glycol divinyl ether, and ethylene glycol divinyl ether.

5. A method for preparing an ultrathin flexible solid electrolyte film as described in any one of claims 1-4, characterized in that, Includes the following steps: A casting slurry is prepared, the casting slurry comprising a polymer binder, high dielectric oxide ceramic powder, and a solvent; After the cast slurry is cast and dried to form a film, the polymer binder is removed by a first ultrafast high-temperature sintering in a non-reactive atmosphere, followed by a second ultrafast high-temperature sintering in an oxidizing atmosphere to obtain a high-dielectric oxide skeleton. Prepare an in-situ curing liquid, wherein the in-situ curing liquid comprises a polymerizable monomer, a crosslinking agent, an electrolyte, and an initiator; The high-dielectric oxide framework is placed in the in-situ curing liquid, fully immersed, and then cured in situ to obtain an ultrathin flexible solid electrolyte film.

6. The method as described in claim 5, characterized in that, In the casting slurry, the polymer binder accounts for 5-15 wt%; the high dielectric oxide ceramic powder accounts for 40-60 wt%; and the solvent accounts for 30-50 wt%.

7. The method as described in claim 5, characterized in that, The first ultrafast high-temperature sintering temperature is 800~1400℃, which carbonizes the polymer, removes the binder, and initially forms the skeleton.

8. The method as described in claim 5, characterized in that, The second ultra-fast high-temperature sintering temperature is 800~1200℃, which removes residual carbon and oxidizes the reduced skeletal components at the same time.

9. A solid-state battery, characterized in that, It contains the ultrathin flexible solid electrolyte film according to any one of claims 1-4.

10. The solid-state battery as described in claim 9, characterized in that, Includes a negative electrode, which is lithium metal or a lithium alloy.

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