Sandwich structured ceramic-polymer composite electrolyte, method for preparing the same, and use thereof

Abstract

The application provides a sandwich structure ceramic-polymer composite electrolyte, a preparation method and application thereof, and the sandwich structure ceramic-polymer composite electrolyte provides a flexible matrix and a further bonding basis for a composite structure through 1,3-dioxolane ring-opening prepolymerization products; the thermal stability can be obviously improved, and the problems of traditional electrolytes, such as high-temperature flammability and failure, can be solved due to the synergistic modification of outer layers MXene and SiO2 and the supporting effect of the intermediate layer LLZO; in addition, the sandwich structure can effectively improve the strength and toughness, effectively inhibit the growth of lithium dendrites, the composite electrolyte can effectively improve the electrical conductivity, electrochemical stability and cycle performance, and is applied to solid-state batteries, and the application prospect is remarkable.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, specifically to a sandwich-structured ceramic-polymer composite electrolyte, its preparation method, and its application. Background Technology

[0002] In the field of new energy, solid-state lithium batteries have become the core development direction of next-generation energy storage technology due to their advantages of high safety and high energy density. The electrolyte, as a key component, directly determines the upper limit of battery performance. Traditional electrolytes are mainly divided into two categories: liquid electrolytes and solid electrolytes. Liquid electrolytes, with their high ionic conductivity (typically 1×10⁻⁶ at room temperature), are... -2 With a density of S / cm or higher and good interfacial compatibility, solid electrolytes are widely used in commercial lithium batteries, and the technology is mature and the cost is controllable. Solid electrolytes (such as ceramic-based and polymer-based electrolytes) can fundamentally solve the safety hazards of liquid electrolytes such as leakage and flammability. They are compatible with high-capacity lithium metal anodes and are the core materials for realizing the industrialization of solid-state lithium batteries. Currently, their application exploration in the fields of power batteries and consumer electronics is continuing to advance, and the market prospects are broad.

[0003] Traditional liquid electrolytes face significant safety and performance bottlenecks: their solvents (such as carbonates) are flammable and volatile, easily triggering thermal runaway under high battery temperatures or overcharge conditions. Furthermore, their reaction with the lithium metal anode generates an unstable SEI film, leading to dendrite growth and short-circuit risks. While solid-state electrolytes offer improved safety, both mainstream systems have limitations: ceramic-based electrolytes (such as LLZO) are mechanically brittle and prone to cracking, and have high interfacial impedance with the electrode; pure polymer electrolytes (such as PEO) have low ionic conductivity (often below 1×10⁻⁶ at room temperature). -5 Solid-state lithium batteries have poor thermal stability (typically starting to lose thermal weight below 200℃), and it is difficult to balance mechanical strength and toughness. They cannot meet the requirements of battery cycle stability and puncture resistance, which restricts the practical application of solid-state lithium batteries. Summary of the Invention

[0004] This invention proposes a sandwich-structured ceramic-polymer composite electrolyte, its preparation method, and its application, aiming to address the shortcomings of existing electrolytes for lithium-ion batteries, such as poor thermal stability, low strength, and poor toughness.

[0005] The technical solution of this invention is implemented as follows: The first aspect of the present invention is to provide a sandwich-structured ceramic-polymer composite electrolyte, which is polymerized from an intermediate layer and an outer layer precursor coated on both sides thereof, wherein the intermediate layer is obtained by prepolymerization of an intermediate layer precursor composed of LLZO, LiTFSI, a first dioxapentane prepolymer and a first initiator; and the outer layer precursor includes SiO2, MXene, LiTFSI, a second dioxapentane prepolymer and a second initiator.

[0006] Furthermore, the thickness of the intermediate layer is 25~40μm; and / or, the thickness of the outer precursor after polymerization is 15~30μm.

[0007] Furthermore, the number-average molecular weight Mn of the first dioxapentane prepolymer and / or the second dioxapentane prepolymer is 60,000 to 70,000 g / mol.

[0008] Furthermore, in the intermediate layer precursor, the mass ratio of LLZO, LiTFSI and dioxane first prepolymer is (20~40):(10~20):(80~100). And / or, in the outer precursor, the mass ratio of SiO2, MXene, LiTFSI to dioxane second prepolymer is (1~3):(0.5~2):(10~20):(80~100).

[0009] Furthermore, the LLZO is a cubic phase with a particle size of 200~500 nm; And / or, the MXene is titanium carbide nanosheets with a thickness of 1~5 nm and a sheet diameter of 1~3 μm.

[0010] Furthermore, the first initiator and / or the second initiator are each independently selected from one or more of Al(OTf)3, Sc(OTf)3, Sn(OTf)2, and LiPF6.

[0011] A second aspect of the present invention is to provide a method for preparing the composite electrolyte described in the first aspect above, comprising the steps of: S1. After dispersing the intermediate layer precursor, coating it onto the substrate and evaporating some of the solvent, prepolymerize to obtain the intermediate layer; S2. After coating the upper surface of the intermediate layer with a dispersion containing the outer layer precursor, the temperature is raised to carry out deep polymerization, and the substrate is peeled off to obtain an intermediate layer with an outer layer coated on one side; S3. After coating the other side of the intermediate layer obtained in S2 with a dispersion containing the outer layer precursor, the mixture is deeply polymerized again to obtain a sandwich-structured ceramic-polymer composite electrolyte.

[0012] Further, in step S1, the prepolymerization conditions are a vacuum of -0.095 to -0.10 MPa and prepolymerization at 60 to 70°C for 40 to 50 minutes. And / or, in step S2, the deep polymerization conditions are: vacuum degree -0.095~-0.10MPa, polymerization at 70~80℃ for 90~100 min; And / or, in step S3, the deep polymerization conditions are: vacuum degree -0.095~-0.10MPa, polymerization at 70~80℃ for 90~100 min.

[0013] A third aspect of the present invention is to provide the application of the ceramic-polymer composite electrolyte described in the first aspect, or the ceramic-polymer composite electrolyte prepared by the preparation method described in the second aspect, in solid-state batteries.

[0014] A fourth aspect of the present invention is to provide a solid-state battery comprising the ceramic-polymer composite electrolyte described in the first aspect, or the ceramic-polymer composite electrolyte prepared by the preparation method described in the second aspect.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The sandwich-structured ceramic-polymer composite electrolyte of this invention provides a flexible matrix and a basis for further bonding through the prepolymerization of 1,3-dioxane ring-opening product. The synergistic modification of the outer MXene and SiO2 layers and the supporting effect of the middle LLZO layer significantly improve thermal stability, mitigating the problems of high-temperature flammability and easy failure of traditional electrolytes. Furthermore, the sandwich structure effectively enhances strength and toughness, effectively suppresses lithium dendrite growth, and the composite electrolyte effectively improves conductivity, electrochemical stability, and cycle performance, showing significant promise for application in solid-state batteries.

[0016] The sandwich-structured ceramic-polymer composite electrolyte of this invention achieves uniform dispersion of components without significant agglomeration by precisely controlling the PDOL polymerization process and combining it with layered coating in a controllable polymerization process. The sandwich structure has clear layers and strong repeatability, solving the problems of uneven structure and large batch differences in traditional electrolytes, making it suitable for industrial production. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a sandwich-structured ceramic-polymer composite electrolyte provided by the present invention.

[0019] Figure 2 This is a scanning electron microscope image of the sandwich-structured ceramic-polymer composite electrolyte prepared in Example 1.

[0020] Figure 3The image shows the XRD pattern of the sandwich-structured ceramic-polymer composite electrolyte prepared in Example 1.

[0021] Figure 4 The image shows the thermal stability test results of the sandwich-structured ceramic-polymer composite electrolyte prepared in Example 1.

[0022] Figure 5 The stress-strain diagram is shown for the sandwich-structured ceramic-polymer composite electrolyte prepared in Example 1.

[0023] Figure 6 This is a battery cycle test diagram of the sandwich-structured ceramic-polymer composite electrolyte prepared in Example 1. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention proposes a sandwich-structured ceramic-polymer composite electrolyte, which is polymerized from an intermediate layer and an outer layer precursor coated on both sides. The intermediate layer is obtained by prepolymerization of an intermediate layer precursor composed of LLZO, LiTFSI, a first dioxapentane prepolymer, and a first initiator. The outer layer precursor includes SiO2, MXene, LiTFSI, a second dioxapentane prepolymer, and a second initiator. A schematic diagram of the sandwich-structured ceramic-polymer composite electrolyte is shown below. Figure 1 As shown.

[0026] The sandwich-structured ceramic-polymer composite electrolyte of this invention uses 1,3-dioxane ring-opening prepolymer products to provide a flexible matrix and a basis for further bonding of the composite structure; it designs an “outer layer (PDOL / SiO2 / MXene)-middle layer (PDOL / LLZO)-outer layer (PDOL / SiO2 / MXene)” structure, in which the middle layer is constructed with LLZO nanoparticles to build a ceramic framework, improving mechanical strength and lithium-ion transport efficiency; the outer layer enhances interfacial bonding with SiO2 and improves thermal conductivity and puncture resistance with MXene, synergistically modifying the structure, while introducing LiTFSI to provide a lithium-ion source, ultimately achieving a balance between thermal stability, mechanical properties and electrochemical performance.

[0027] Specifically, it exhibits the following superior performance: 1. Significantly improved thermal stability Traditional liquid electrolytes typically have a 5% thermal weight loss temperature (T5%) of 120-150℃, while pure PDOL polymer electrolytes have a T5% of only 220℃, and are prone to chain segment degradation at high temperatures. This invention provides a composite electrolyte whose T5% is increased to 270℃ due to the synergistic modification of the outer MXene and SiO2 layers and the supporting effect of the middle LLZO layer, with a thermal weight loss rate of <7% at 150℃. Simultaneously, the glass transition temperature (Tg) is -42℃, significantly enhancing the high-temperature stability of the chain segments and significantly improving the problems of high-temperature flammability and easy failure of traditional electrolytes.

[0028] 2. Synergistic optimization of mechanical properties: strength and toughness

[0029] Traditional ceramic-polymer composite electrolytes often suffer from the defect of being "strong but brittle," with a fracture strength of approximately 8 MPa, an elongation at break of approximately 20%, and a toughness of less than 1 MJ / m. 3 Pure polymer electrolytes have low mechanical strength and cannot withstand lithium dendrite penetration. The sandwich-structured composite electrolyte provided by this invention has a fracture strength of 16 MPa, an elongation at break of 55%, and a calculated toughness of 4.4 MJ / m. 3 It has more than 5 times the energy of pure PDOL electrolyte; and the energy storage modulus retention rate is 75% at 60℃ and more than 70% at room temperature. Its high-temperature mechanical stability far exceeds that of traditional systems, and it can effectively suppress lithium dendrite growth.

[0030] 3. Excellent electrochemical performance

[0031] Traditional polymer electrolytes typically have room-temperature ionic conductivity below 1×10⁻⁶. -5 The Li / electrolyte / Li symmetric battery exhibits poor interfacial stability with the lithium metal anode, and voltage fluctuations easily exceed 100mV after 500 hours of cycling, resulting in a short cycle life. The composite electrolyte provided by this invention achieves a room-temperature ionic conductivity of 2.5 × 10⁻⁶ S / cm. -3 S / cm; Li / / Electrolyte / / Li symmetric cell showed no short circuit after 1000h cycling at 0.1mA / cm², with voltage fluctuation <50mV; LFP / / Li cell achieved 92% capacity retention after 100 cycles at 0.5C, with electrochemical stability and cycle performance far exceeding traditional electrolytes.

[0032] 4. Higher structural and performance stability

[0033] Traditional composite electrolytes often employ simple blending methods, leading to the tendency for ceramic fillers to agglomerate and polymer molecular weight dispersion often exceeding 2.0. This results in poor electrolyte performance repeatability with an error exceeding 15%, failing to meet industrialization requirements. This invention, through precise control of the PDOL polymerization process, combined with layered coating and controlled polymerization, achieves uniform dispersion of LLZO / SiO2 / MXene in the matrix. SEM / EDS analysis shows no significant agglomeration, a clear sandwich structure, and a performance repeatability error of <10%, solving the problems of uneven structure and large batch-to-batch variations in traditional electrolytes.

[0034] In a preferred embodiment, the thickness of the intermediate layer is 25-40 μm; and / or, the thickness of the outer layer formed after the outer layer precursor is polymerized is 15-30 μm.

[0035] In a preferred embodiment, the number-average molecular weight (Mn) of the first and / or second dioxapentane prepolymer is 60,000–70,000 g / mol, and the dispersion is 1.3–1.6. The prepolymer with these parameters is preferably prepared by the following method: DOL monomer and Al(OTf)3 are added at a molar ratio of (1000–1100):(1–2), and an organic solvent is added and stirred until completely dissolved. Polymerization is carried out in an oil bath at 50–60 °C for 6–12 h, under nitrogen protection, at a flow rate of 50–60 mL / min. An organic amine of equal molar amount to Al(OTf)3 is added to terminate the reaction, and the mixture is stirred for 15–20 min. The reaction solution is poured into an excess of organic solvent to precipitate PDOL, and after standing, it is filtered to collect the white solid. The solid is washed with an organic solvent and vacuum dried to obtain the pure PDOL prepolymer with the target number-average molecular weight.

[0036] In a preferred embodiment, the mass ratio of LLZO, LiTFSI and dioxapentane first prepolymer in the intermediate layer precursor is (20~40):(10~20):(80~100); and the mass ratio of SiO2, MXene, LiTFSI and dioxapentane second prepolymer in the outer layer precursor is (1~3):(0.5~2):(10~20):(80~100).

[0037] In a preferred embodiment, the LLZO is a cubic phase with a particle size of 200-500 nm; and / or, the MXene is titanium carbide (Ti3C2T). x Nanosheets with a thickness of 1~5 nm and a diameter of 1~3 μm.

[0038] In a preferred embodiment, the first initiator and / or the second initiator are each independently selected from one or more of Al(OTf)3, Sc(OTf)3, Sn(OTf)2, and LiPF6.

[0039] This invention also proposes a method for preparing a sandwich-structured ceramic-polymer composite electrolyte, comprising the following steps: 1) Preparation of dioxapentane prepolymer Add DOL monomer and Al(OTf)3 at a molar ratio of (1000~1100):(1~2), and add organic solvent while stirring until completely dissolved. Polymerize in an oil bath at 50-60℃ for 6~12 h under nitrogen protection at a flow rate of 50~60 mL / min. Add an organic amine of equal molar amount to Al(OTf)3 to terminate the reaction, and stir for 15~20 min. Pour the reaction solution into excess organic solvent to precipitate PDOL, allow it to stand, filter, and collect the white solid. Wash with organic solvent and vacuum dry to obtain pure PDOL prepolymer with the target number average molecular weight.

[0040] 2) Preparation of intermediate layer precursor (PDOL / LLZO composite system): Weigh the raw materials according to the mass ratio of PDOL:LLZO:LiTFSI = (80~100):(20~40):(10~20), and disperse them after adding an organic solvent. Add an initiator with a concentration of 0.4~0.6mM and stir to obtain a homogeneous intermediate layer precursor.

[0041] 3) Preparation of outer layer precursor (PDOL / SiO2 / MXene composite system)

[0042] Weigh the raw materials according to the mass ratio of PDOL:SiO2:MXene:LiTFSI = (80~100):(1~3):(0.5~2):(10~20), add an organic solvent to disperse, use an ice-water bath to prevent MXene oxidation, and stir to ensure complete exfoliation of MXene sheets without agglomeration. Add an initiator with a concentration of 0.4~0.6mM and stir to obtain the outer layer precursor.

[0043] 4) Intermediate layer coating and prepolymerization

[0044] The intermediate layer precursor is uniformly coated onto a PET substrate using a blade coating method with a blade height of 115-120 μm. The substrate is allowed to stand at room temperature for 15-20 minutes to allow some solvent to evaporate. It is then transferred to a vacuum drying oven and pre-polymerized at 60-70°C for 40-50 minutes (vacuum degree -0.095 to -0.10 MPa) to form a semi-cured intermediate layer with a thickness of approximately 25-40 μm, ensuring shape stability.

[0045] (5) Outer coating and overall polymerization

[0046] First, the outer precursor is coated onto the exposed outer surface of the intermediate layer using a blade coating method with a blade height of 80-85 μm, and allowed to stand at room temperature for 10-20 min. The entire assembly is then transferred to a vacuum drying oven and polymerized at 70-80℃ for 90-100 min under a vacuum of -0.095 to -0.10 MPa to complete PDOL polymerization. Then, the base layer is peeled off, and the above process is repeated to coat the other side with the outer precursor and perform complete polymerization, forming a "outer layer-intermediate layer-outer layer" sandwich structure ceramic-polymer composite electrolyte that combines thermal stability and mechanical compatibility.

[0047] In the above preparation method, the combination of layered coating and controlled polymerization process achieves uniform dispersion of LLZO / SiO2 / MXene in the matrix. SEM / EDS shows no obvious agglomeration, and the sandwich structure is clearly layered with an outer layer thickness of 15-25 μm and an intermediate layer thickness of 25-40 μm.

[0048] In a preferred embodiment, in step (1), the organic solvent is one or more of anhydrous DME, anhydrous diethyl ether, and anhydrous ethanol; and the organic amine is one or more of triethylamine, tri-n-propylamine, and pyridine.

[0049] In a preferred embodiment, in steps (2) and (3), the organic solvent is independently selected from one or more of anhydrous acetonitrile, anhydrous DME, anhydrous THF, and anhydrous MTBE.

[0050] In a preferred embodiment, in steps (2) and (3), the initiator is independently selected from one or more of Al(OTf)3, Sc(OTf)3, Sn(OTf)2, and LiPF6.

[0051] Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0052] In the following examples, the LLZO used was a cubic phase with a particle size of 200~500 nm, purchased from Xi'an Qiyue Biotechnology (catalog number XL216248); MXene was titanium carbide (Ti3C2T). x Nanosheets with a thickness of 1~5 nm and a diameter of 1~3 μm were purchased from Nanjing Xianfeng Nano (item number XF186).

[0053] Example 1

[0054] A ceramic-polymer sandwich structured composite electrolyte is provided, and its preparation method is as follows: (1) Preparation of PDOL: The DOL monomer was purified by passing it through a neutral Al2O3 chromatography column to remove the polymerization inhibitor. The Al2O3 chromatography column was a neutral Al2O3 70 mesh, grade II, 150m column. 2 / g, with 3wt% water content, was added to a glass column with an inner diameter of 1.5cm and a length of 20cm, G3 sintered glass core, and then dried for 48h with 4Å molecular sieve (mass ratio 1:10). The raw material was weighed according to DOL:Al(OTf)3 = 1000:1mol, and anhydrous DME was added. The mixture was magnetically stirred for 30min at 500rpm until completely dissolved. The solution was transferred to a Schlenk flask and polymerized in a 50℃ oil bath for 6h under nitrogen protection at a flow rate of 50mL / min. Triethylamine was added in an equimolar amount to Al(OTf)3 to terminate the reaction, and the mixture was stirred for 15min. The reaction solution was poured into excess anhydrous diethyl ether (volume ratio 1:5) to precipitate PDOL. After standing for 2h, the mixture was filtered, and the white solid was collected. The solid was washed three times with anhydrous diethyl ether (100mL each time) and dried under vacuum at 60℃ for 24h to obtain pure PDOL with a number average molecular weight of approximately 60,000 and a dispersion of 1.3.

[0055] (2) Preparation of intermediate layer precursor (PDOL / LLZO composite system): Weigh the raw materials according to the mass ratio of PDOL:LLZO:LiTFSI = 80:20:10, and add anhydrous acetonitrile (solid-liquid ratio 1:6 g / mL). Disperse ultrasonically for 40 min at 300 W and 25 °C. Add Al(OTf)3 at a concentration of 0.4 mM, and stir magnetically for 20 min at 600 rpm to obtain a homogeneous intermediate layer precursor.

[0056] (3) Preparation of the outer precursor (PDOL / SiO2 / MXene composite system): Weigh the raw materials according to the mass ratio of PDOL:SiO2:MXene:LiTFSI = 80:1:0.5:10, and add anhydrous acetonitrile (solid-liquid ratio 1:6 g / mL). First, ultrasonically disperse the mixture for 50 min at 300 W. For the first 20 min, place it in an ice-water bath to prevent MXene oxidation, then magnetically stir for 30 min at 600 rpm to ensure complete exfoliation of the MXene sheets without agglomeration. Add Al(OTf)3 at a concentration of 0.4 mM and stir for 30 min to obtain the outer layer precursor.

[0057] (4) Intermediate layer coating and prepolymerization

[0058] The intermediate layer precursor was uniformly coated onto a PET substrate using a blade coating method with a blade height of 120 μm. The substrate was allowed to stand at room temperature for 15 minutes to allow some solvent to evaporate. It was then transferred to a vacuum drying oven and pre-polymerized at 60°C for 40 minutes (vacuum degree -0.095 MPa) to form a semi-cured intermediate layer with a thickness of approximately 25 μm, ensuring shape stability.

[0059] (5) Outer coating and overall polymerization

[0060] The outer precursor was symmetrically coated on both sides of the intermediate layer using a blade coating method with a blade height of 80 μm, and allowed to stand at room temperature for 10 min. The entire assembly was then transferred to a vacuum drying oven and polymerized at 80℃ for 90 min under a vacuum of -0.095 MPa to complete the polymerization of PDOL. The outer precursor on the exposed side of the intermediate layer was first coated and polymerized using a blade coating method. After cooling to room temperature, the PET substrate was peeled off, and the outer precursor on the other side was then coated and polymerized using a blade coating method to obtain a ceramic-polymer sandwich structure composite electrolyte.

[0061] Example 2

[0062] A ceramic-polymer sandwich structured composite electrolyte is provided, and its preparation method is as follows: (1) Preparation of PDOL: The DOL monomer was purified by passing it through a neutral Al2O3 chromatography column to remove the polymerization inhibitor. The Al2O3 chromatography column was a neutral Al2O3 70 mesh, grade II, 150m column. 2 / g, with 3wt% water content, was added to a glass column with an inner diameter of 1.5cm and a length of 20cm, G3 sintered glass core, and then dried for 54h with 4Å molecular sieve (mass ratio 1:8). The raw material was weighed according to a DOL:Al(OTf)3 ratio of 1000:1.5mol, and anhydrous DME was added. The mixture was magnetically stirred for 30min at 500rpm until completely dissolved. The solution was transferred to a Schlenk flask and polymerized in a 50℃ oil bath for 9h under nitrogen protection at a flow rate of 50mL / min. Triethylamine, in an equimolar amount with Al(OTf)3, was added to terminate the reaction, and the mixture was stirred for 15min. The reaction solution was poured into excess anhydrous diethyl ether (volume ratio 1:5) to precipitate PDOL. After standing for 2h, the mixture was filtered, and the white solid was collected. The solid was washed three times with anhydrous diethyl ether (100mL each time) and dried under vacuum at 60℃ for 24h to obtain pure PDOL with a number average molecular weight of approximately 65000 and a dispersion of 1.4.

[0063] (2) Preparation of intermediate layer precursor (PDOL / LLZO composite system): Weigh the raw materials according to the mass ratio of PDOL:LLZO:LiTFSI = 100:30:15, and add anhydrous acetonitrile (solid-liquid ratio 1:6 g / mL). Disperse ultrasonically for 40 min at 300 W and 25 °C. Add Al(OTf)3 at a concentration of 0.4 mM, and stir magnetically for 20 min at 600 rpm to obtain a homogeneous intermediate layer precursor.

[0064] (3) Preparation of the outer precursor (PDOL / SiO2 / MXene composite system): Weigh the raw materials according to the mass ratio of PDOL:SiO2:MXene:LiTFSI = 100:1.5:1:15, and add anhydrous acetonitrile (solid-liquid ratio 1:6 g / mL). First, ultrasonically disperse the mixture for 50 min at 300 W. For the first 20 min, place it in an ice-water bath to prevent MXene oxidation, then magnetically stir for 30 min at 600 rpm to ensure complete exfoliation of the MXene sheets without agglomeration. Add Al(OTf)3 at a concentration of 0.4 mM and stir for 30 min to obtain the outer layer precursor.

[0065] (4) Intermediate layer coating and prepolymerization

[0066] The intermediate layer precursor was uniformly coated onto a PET substrate using a blade coating method with a blade height of 145 μm. The substrate was allowed to stand at room temperature for 15 minutes to allow some solvent to evaporate. It was then transferred to a vacuum drying oven and pre-polymerized at 60°C for 40 minutes (vacuum degree -0.095 MPa) to form a semi-cured intermediate layer with a thickness of approximately 30 μm, ensuring shape stability.

[0067] (5) Outer coating and overall polymerization

[0068] The outer precursor was symmetrically coated on both sides of the intermediate layer using a blade coating method with a blade height of 100 μm, and allowed to stand at room temperature for 10 min. The entire assembly was then transferred to a vacuum drying oven and polymerized at 80 °C for 90 min under a vacuum of -0.095 MPa to complete the polymerization of PDOL. First, the outer precursor on the exposed side of the intermediate layer was coated and polymerized using a blade coating method. After cooling to room temperature, the PET substrate was peeled off, and then the outer precursor on the other side was coated and polymerized using a blade coating method to obtain a ceramic-polymer sandwich structure composite electrolyte.

[0069] Example 3

[0070] A ceramic-polymer sandwich structured composite electrolyte is provided, and its preparation method is as follows: (1) Preparation of PDOL After removing the polymerization inhibitor and drying, DOL monomer was added at a ratio of DOL:Al(OTf)3 = 1050:1.5 mol, dissolved in anhydrous DME, and polymerized in an oil bath at 55℃ for 10 h under nitrogen protection at a flow rate of 55 mL / min. The polymerization was terminated by adding an equimolar amount of triethylamine of Al(OTf)3, precipitated in diethyl ether, and dried under vacuum at 60℃ to obtain pure PDOL with a number average molecular weight of 68000 g / mol and a dispersion of 1.5.

[0071] (2) Preparation of intermediate layer precursor

[0072] Weigh the raw materials according to the mass ratio of PDOL:LLZO:LiTFSI=90:35:18, disperse them in anhydrous acetonitrile (solid-liquid ratio 1:6 g / mL), sonicate for 45 min, add 0.5 mM Al(OTf)3 and stir to obtain a homogeneous precursor.

[0073] (3) Preparation of outer layer precursor

[0074] Weigh the raw materials according to the mass ratio of PDOL:SiO2:MXene:LiTFSI=90:2:1.5:18, disperse them in anhydrous acetonitrile, sonicate in an ice-water bath for 50 min, and add 0.5 mM Al(OTf)3 and stir to obtain the precursor.

[0075] (4) Intermediate layer coating and prepolymerization

[0076] A 35μm thick semi-cured intermediate layer was obtained by scraping a PET substrate (scraper height 130μm), allowing it to stand at room temperature for 18 min, and then prepolymerizing it at 65℃ and -0.098MPa for 45 min.

[0077] (5) Outer coating and overall polymerization

[0078] The outer precursor was sequentially coated on both sides (scraper height 90μm), allowed to stand at room temperature for 15min, and then polymerized at 75℃ and -0.098MPa for 95min to obtain the sandwich structured composite electrolyte.

[0079] Comparative Example 1

[0080] This comparative example uses pure PDOL electrolyte, without sandwich structure, and without LLZO, SiO2, or MXene fillers. The preparation method is as follows: (1) The preparation of PDOL is the same as in Example 1; (2) Preparation of precursor PDOL Weigh the raw materials according to a mass ratio of PDOL:LiTFSI = 100:20, and add anhydrous acetonitrile (solid-liquid ratio 1:6 g / mL). Disperse ultrasonically for 40 min at 300 W and 25 °C. Add Al(OTf)3 at a concentration of 0.4 mM, and stir magnetically for 20 min at 600 rpm to obtain a homogeneous precursor.

[0081] (3) Precursor PDOL coating and polymerization

[0082] The precursor PDOL was uniformly coated onto a PET substrate using a blade coating method with a blade height of 100 μm. The mixture was allowed to stand at room temperature for 15 min to allow some solvent to evaporate. It was then transferred to a vacuum drying oven and vacuum-polymerized at 90°C for 90 min (vacuum degree -0.095 MPa) to form a semi-cured intermediate layer approximately 25 μm thick, ensuring shape stability. After cooling to room temperature, the PET substrate was peeled off to obtain pure PDOL electrolyte.

[0083] Comparative Example 2

[0084] This comparative example uses a single-layer PDOL / LLZO composite electrolyte, without a sandwich structure and without SiO2 or MXene fillers. The difference between this preparation method and Comparative Example 1 is that 30%wt LLZO is added in step (1), while steps (2) and (3) are the same.

[0085] Comparative Example 3

[0086] This comparative example uses a sandwich structure of PDOL / LLZO / PDOL, without SiO2-MXene. The preparation method differs from Example 1 in that SiO2 and MXene are not added to the outer precursor (PDOL / SiO2 / MXene composite system), while the other materials and preparation steps are the same.

[0087] Characterization of sandwich-structured composite electrolytes

[0088] 1) The composite electrolyte obtained in Example 1 was observed using SEM to assess the integrity of the sandwich structure, the uniformity of the outer layer thickness, and the tightness of the interface between the middle and outer layers. Figure 2 As shown, the results indicate that a well-structured sandwich composite electrolyte was successfully prepared. The interface between the middle and outer layers is tightly bonded with no obvious voids, and the sandwich composite structure is intact. The thickness of the outer layer is in the range of 15-25 μm, and the thickness of the middle layer is in the range of 25-40 μm.

[0089] 2) Crystal structure analysis: The XRD pattern of the composite electrolyte obtained in Example 1 is shown below. Figure 3 As shown: characteristic diffraction peaks of cubic LLZO appear at 2θ = 29.3°, 33.9°, and 48.8°, corresponding to the cubic phase Li7La3Zr2O in the PDF standard card. 12 The characteristic peak positions, sharp peak shapes, and lack of shift indicate that LLZO nanoparticles (200-500 nm) maintain a cubic phase structure within the PDOL matrix and exhibit MXene (Ti3C2T) at 2θ≈7.5°-8.5°. xThe characteristic peaks of the 002 plane of MXene are symmetrical and without significant broadening, indicating that the MXene sheets did not undergo severe stacking in the PDOL / SiO2 matrix. Due to the use of surface-hydroxylated SiO2 nanoparticles, the XRD characteristic peaks of 50-100 nm are broadened peaks at 2θ≈21.0°, which are characteristic of amorphous SiO2. The peak intensity is weak but identifiable, indicating that SiO2 is uniformly dispersed in an amorphous state in the outer layer. The appearance of PDOL crystallization diffraction peaks at 2θ≈19° with moderate peak intensity proves that the PDOL polymer was successfully synthesized.

[0090] Performance testing

[0091] Thermal stability test: A thermogravimetric analyzer (nitrogen atmosphere, temperature range 25-600℃, heating rate 10℃ / min) was used to record the temperature at which the sample mass loss was 5% (T5%) and the mass loss rate during the isothermal stage at 150℃.

[0092] Mechanical property testing: A universal testing machine (tensile rate 1 mm / min, sample size 10 mm × 5 mm × 0.1 mm) was used to record the stress (fracture strength) and strain (fracture elongation) at fracture. Toughness was calculated according to "toughness = fracture strength × fracture elongation / 2". Peel strength testing: A universal testing machine (peel rate 5 mm / min, sample size 20 mm × 50 mm) was used to test the interfacial peel force between the outer layer and the intermediate layer, which was then converted into peel strength.

[0093] Electrochemical performance testing: Assembled SS (stainless steel) / / electrolyte / / SS symmetric cells using an electrochemical workstation (frequency range 10). 6 -10 -2 AC impedance (EIS) testing was performed at Hz (amplitude 5mV). Conductivity was calculated using the formula "σ=L / (R×S)" (σ is conductivity, L is electrolyte thickness, R is impedance value, and S is electrode area). Interface stability testing: A Li / / electrolyte / / Li symmetric battery was assembled and cycled for 1000 hours at a current density of 0.1mA / cm² using a battery testing system. The voltage curve fluctuation amplitude was recorded. Battery cycle performance testing: An LFP (lithium iron phosphate) / / electrolyte / / Li full battery was assembled and charged and discharged at a rate of 0.5C (1C=170mAh / g) (voltage range 2.5-4.2V). The capacity retention rate after 100 cycles was recorded.

[0094] The thermal stability test graph of the ceramic-polymer sandwich structure composite electrolyte obtained in Example 1 is shown below. Figure 4 As shown, the stress-strain test results are as follows: Figure 5 As shown, the battery cycle performance test results are as follows: Figure 6 As shown.

[0095] The test results are shown in Table 1:

[0096] It is easy to see from the results in Table 1: 1) Ceramic fillers (LLZO / SiO2 / MXene) are key to improving the thermal stability of electrolytes. Example 1: The T5% (270℃) of the electrolyte is 50℃ higher than that of pure PDOL electrolyte (220℃), and the thermal weight loss rate at 150℃ (<7%) is much lower than that of pure PDOL (>20%), proving that the addition of LLZO, SiO2, and MXene can significantly enhance the heat resistance. Compared with the single-layer PDOL / LLZO (T5%=235℃) and the sandwich without SiO2-MXene (T5%=240℃), the target electrolyte has further optimized thermal stability due to the synergistic effect of the outer layer SiO2 (enhancing the heat resistance of the matrix) and MXene (accelerating heat conduction and inhibiting local overheating), thus improving the defect of "easy degradation at high temperature" of pure polymer electrolyte.

[0097] 2) Breakthrough in mechanical properties achieved through sandwich structure and multi-component synergistic modification

[0098] Example 1: The fracture strength (16 MPa) is 3.2 times that of pure PDOL (<5 MPa) and twice that of monolayer PDOL / LLZO (8 MPa), and the toughness (4.4 MJ / m) is... 3 The strength of the target electrolyte is 2.9-4.4 times that of the other three, which proves that the "ceramic skeleton" effect of the middle layer LLZO and the "two-dimensional reinforcement" effect of the outer layer MXene can effectively improve mechanical strength and puncture resistance. The peel strength of the target electrolyte outer layer (≥3N / m) is 3 times higher than that of the sandwich without SiO2-MXene (<1N / m), indicating that SiO2 can enhance the interfacial bonding force between the outer layer and the middle layer and avoid delamination. Pure PDOL and single-layer structures cannot meet the interfacial stability requirements under complex working conditions due to the lack of outer layer design.

[0099] 3) Layered functional design significantly improves electrochemical performance

[0100] The target electrolyte's room temperature ionic conductivity (2.5 × 10⁻⁶) -3 S / cm) is pure PDOL (<1×10) -4 25 times that of S / cm, and a single layer of PDOL / LLZO (5×10) -4 The efficiency of lithium-ion transport channels is 5 times that of lithium-ion transport channels (S / cm) because the intermediate LLZO layer constructs efficient lithium-ion transport channels and the outer layer modification does not block the channels. The voltage fluctuation of the target electrolyte Li / / Li after 1000h cycling (<50mV) was much lower than that of the comparative example (>80mV), and the capacity retention of the LFP / / Li battery (92%) was higher than that of the comparative example (<80%). This proves that the outer SiO2 / MXene can optimize the interfacial compatibility between the electrolyte and the lithium anode, suppress lithium dendrite growth, and improve the cycle stability of the battery.

[0101] 4) Single component or structural optimization cannot achieve synergistic effects on multiple performance aspects.

[0102] While pure PDOL electrolyte (without ceramic filler) possesses a certain degree of toughness, its thermal stability, mechanical strength, and electrochemical performance are the worst, proving that a single polymer matrix cannot meet the requirements of solid-state lithium batteries. Although single-layer PDOL / LLZO (with only the middle layer modified) and sandwich without SiO2-MXene (lacking outer layer synergy) have improved performance compared to pure PDOL, their thermal stability, interfacial bonding, and electrochemical performance still have shortcomings. Only a sandwich structure of "outer layer (MXene-SiO2) - middle layer (LLZO)" + multi-component synergy can achieve a balance between thermal stability, mechanical properties, and electrochemical performance.

[0103] Lithium metal battery application testing

[0104] The ceramic-polymer sandwich structure composite electrolyte, which combines thermal stability and mechanical compatibility, prepared in Example 1, was assembled into a lithium metal battery for battery performance testing, as detailed below: Battery assembly: Composite electrolyte: After preparation according to Example 1, it is cut into discs with a diameter of 16 mm and vacuum dried at 60°C for 24 h in a glove box to remove residual acetonitrile. Lithium metal electrode: Lithium sheets with a purity ≥99.9% are selected, cut into discs with a diameter of 15 mm and a thickness of 500 μm, wiped with anhydrous ethanol to remove the surface oxide layer, and then vacuum dried for 1 h. Positive electrode (LFP): Lithium iron phosphate (LFP) active material, acetylene black, and PVDF are mixed at a mass ratio of 8:1:1, and a slurry is prepared using N-methylpyrrolidone (NMP) as a solvent. The slurry is coated onto aluminum foil, vacuum dried at 80°C for 12 h, and then cut into discs with a diameter of 16 mm. Battery casing: A CR2032 button battery casing is selected, ultrasonically cleaned with anhydrous ethanol before assembly, and dried at 120°C. Assemble a Li / / electrolyte / / Li symmetrical battery by following the order: lower shell → lithium plate (15mm) → composite electrolyte (16mm) → lithium plate (15mm) → spring plate → gasket → upper shell; or assemble an LFP / / electrolyte / / Li full battery by following the order: lower shell → LFP positive electrode (16mm, aluminum foil facing down) → composite electrolyte (16mm) → lithium plate (15mm) → spring plate → gasket → upper shell. Test specifications: 1. Li / / electrolyte / / Li symmetric cell: CR2032 button cell, 16mm in diameter, 80μm in thickness, lithium sheet: 15mm in diameter, 500μm in thickness, argon glove box (H2O / O2 < 0.1 ppm).

[0105] 2. LFP / / Electrolyte / / Li Full Cell: CR2032 coin cell, 16mm diameter, 80μm thickness; LFP cathode: 16mm diameter, areal density 1.5mg / cm³ 2 Lithium foil: 15mm in diameter, 500μm in thickness, single cell capacity ≈1.0 mAh, argon glove box (H2O / O2 < 0.1 ppm).

[0106] 3. Electrochemical performance testing: Electrochemical workstation (frequency 10) -1 -10 6 Hz, amplitude 10 mV); battery testing system (voltage 0-5 V, current accuracy ±0.1%).

[0107] 4. Safety performance tests: Thermogravimetric analyzer (TGA, 10℃ / min); Needle penetration tester (needle diameter 1mm); Extrusion tester (maximum pressure 50MPa).

[0108] Test method: 1) Interface stability test. Lithium metal interface stability test: The assembled symmetrical battery was left to stand for 12 hours to ensure full wetting of the interface. A constant current cycle was performed at a current density of 0.1 mA / cm² using a battery testing system for 1000 hours. Voltage data was recorded every 10 hours, and a voltage-time curve was plotted to calculate the voltage fluctuation amplitude. Ionic conductivity test: An SS (stainless steel) / electrolyte / SS battery was assembled, with an SS sheet diameter of 16 mm, simulating the electrode interface. EIS was tested using an electrochemical workstation at room temperature (25℃) and 60℃, with a frequency range of 10. -1 -10 6 Hz, amplitude 10mV. Full battery cycle and rate performance testing: The full battery was left to stand for 24 hours (25℃) to ensure sufficient lithium-ion diffusion. Charge / discharge regime: Constant current charging to 4.2V, 0.5C rate, 1C=170 mA / g; constant voltage charging to current ≤0.05C; constant current discharging to 2.5V, 0.5C rate, completing one cycle. Cycle test: 100 cycles at 0.5C, recording the capacity of each charge / discharge cycle and calculating the capacity retention rate. Rate test: 5 cycles each at 0.2C, 0.5C, 1C, and 2C rates, recording the discharge capacity at each rate.

[0109] 2) Safety Performance Testing. Thermal Abuse Test: A full battery that has undergone ten cycles is placed on the thermogravimetric analyzer sample stage and heated from 25°C to 200°C at a rate of 10°C / min. The battery's appearance, including whether it smokes or bulges, and the temperature-mass change curve are recorded in real time. Needle Penetration Test: A 1mm diameter stainless steel needle with a tip sharpness Ra≤0.1μm is mounted on a needle penetration testing machine. At 25°C, the needle is perpendicularly pierced to the center of the battery at a speed of 5mm / s. The voltage is continuously monitored for 1 hour after penetration, and any short circuit is recorded. Compression Test: The full battery is placed between two plates of a compression testing machine, and a pressure of 10 MPa is applied and maintained for 5 minutes. Voltage changes are monitored in real time during compression. After compression, the battery is disassembled to observe whether the electrolyte has ruptured.

[0110] Test conditions: 1) Electrochemical performance testing. Ambient temperature: 25℃±2℃ (room temperature); 60℃±1℃ (high temperature). Humidity: <1%RH, atmosphere: argon (assembly); air (testing, moisture-free).

[0111] Resting time: 12h for symmetrical cells, 24h for full cells. 2. Safety performance test. Ambient temperature: 25℃±2℃. Humidity: <1% RH, Atmosphere: Air. Needle penetration speed: 5mm / s; Extrusion pressure: 10MPa.

[0112] The test results are shown in Table 2.

[0113]

[0114] Solid-state battery application testing

[0115] The ceramic-polymer sandwich structure composite electrolyte prepared in Example 1 was assembled into a solid-state battery for battery performance testing, as detailed below: Battery assembly: Composite electrolyte: Prepared according to the experimental protocol, peeled off the PET substrate to a thickness of 25 μm, cut into 16 mm diameter discs, and vacuum dried at 60 °C for 24 h in a glove box to remove residual anhydrous acetonitrile. Lithium metal anode: Select lithium sheets with a purity ≥99.9%, cut into 15 mm diameter discs and 500 μm thick discs, wipe the surface oxide layer with anhydrous ethanol (purity ≥99.9%), and vacuum dried at 120 °C for 1 h (to avoid the oxide layer affecting the interface contact). LFP cathode: LFP active material, acetylene black, and PVDF are mixed in a mass ratio of 8:1:1, slurry is prepared using N-methylpyrrolidone (NMP) as solvent, coated on aluminum foil, vacuum dried at 80 °C for 12 h, and cut into 16 mm diameter discs. Battery casing and auxiliary materials: CR2032 button battery casing is selected. Before assembly, it is ultrasonically cleaned with anhydrous ethanol for 15 minutes and dried at 120℃. The spring sheet thickness of 0.5mm and the gasket thickness of 1mm are cleaned and dried under the same conditions. Assemble a Li / / electrolyte / / Li symmetrical battery by following the order: lower casing → lithium sheet (15mm) → composite electrolyte (16mm) → lithium sheet (15mm) → spring sheet → gasket → upper casing; assemble a Li / / electrolyte / / LFP full battery by following the order: lower casing → LFP positive electrode (16mm, aluminum foil facing down) → composite electrolyte (16mm) → lithium sheet (15mm) → spring sheet → gasket → upper casing.

[0116] Test specifications: 1. Li / / electrolyte / / Li symmetric cell: CR2032 button solid-state cell, diameter 16mm, thickness 60-100μm, LLZO filling amount 20 wt%, lithium sheet: diameter 15mm, thickness 500μm, purity ≥99.9%, 0-1 V, constant current cycling.

[0117] 2. Li / / electrolyte / / LFP full cell: CR2032 button solid-state battery, 16mm in diameter, 60-100μm in thickness, LLZO filling amount 20 wt%, LFP cathode: 16mm in diameter, areal density 1.5mg / cm²; lithium sheet: 15mm in diameter, 500μm in thickness, approximately 1.0mAh, 2.5-4.2 V.

[0118] 3. Electrochemical performance testing: Electrochemical workstation (frequency 10) -1 -10 6 (Hz, amplitude 10mV); battery testing system, voltage 0-5V, current accuracy ±0.1%.

[0119] 4. Safety performance testing: The thermogravimetric analyzer adopts TGA, 10℃ / min, 25-600℃; the needle penetration tester has a needle diameter of 1mm and a speed of 0-10mm / s; the extrusion tester has a maximum pressure of 50MPa.

[0120] Test method: 1. Electrochemical performance testing. Ionic conductivity testing: Assembled SS (stainless steel) / / electrolyte / / SS symmetric cells; tested EIS frequency range 10 at room temperature (25℃) and 60℃ using an electrochemical workstation. - ¹-10 6 Hz, amplitude 10mV. Lithium metal interface stability test: Symmetrical batteries were placed in a glove box for 12 hours (25℃) to ensure full interface wetting; constant current cycling was performed for 1000 hours at a current density of 0.1 mA / cm² using a battery testing system; voltage data was recorded every 10 hours, a voltage-time curve was plotted, and the voltage fluctuation amplitude was calculated. Full battery cycle and rate performance test: Full batteries were placed in a glove box for 24 hours (25℃) to ensure full lithium ion diffusion; charge and discharge regime: constant current charging to 4.2V (0.5 C rate), constant voltage charging to current ≤0.05 C; constant current discharging to 2.5V (0.5 C rate), completing one cycle; cycle test: 100 cycles at 0.5 C, recording the capacity of each charge and discharge, and calculating the capacity retention rate; rate test: cycles were performed 5 times each at 0.2C, 0.5C, 1C, and 2C rates, and the discharge capacity at different rates was recorded.

[0121] 2. Safety Performance Testing. Thermal Abuse Test: A full cell after 10 cycles was placed on a TGA sample stage under a nitrogen atmosphere at a flow rate of 50 mL / min. The temperature was increased from 25°C to 200°C at a rate of 10°C / min. The battery appearance, smoke, bulging, and temperature-voltage curves were recorded in real time. Needle Penetration Test: A 1 mm diameter stainless steel needle with a tip sharpness Ra ≤ 0.1 μm was mounted on a needle penetration tester. At 25°C, the needle was perpendicularly pierced to the center of the battery at a speed of 5 mm / s. The voltage was continuously monitored for 1 hour after piercing. Compression Test: The full cell was placed between two plates of a compression tester, and a pressure of 10 MPa was applied and maintained for 5 minutes. The voltage change was monitored in real time during compression. After compression, the battery was disassembled, and the electrolyte was observed using FESEM to check for cracking and delamination.

[0122] Test conditions: 1. Electrochemical performance testing. Ambient temperature: room temperature group, 25℃±2℃; high temperature group, 60℃±1℃. Humidity <1%RH; atmosphere: argon (assembly); dry air (testing). Standing time: 12h for symmetric cells, 24h for full cells; charge / discharge cutoff conditions: 4.2 V / 2.5 V.

[0123] 2. Safety performance test. Ambient temperature: 25℃±2℃, <1% RH; Atmosphere: Thermal abuse: nitrogen; Needle penetration / compression: air. Needle penetration speed: 5mm / s; Compression pressure: 10MPa, holding pressure for 5min.

[0124] The test results are shown in Table 3.

[0125] Table 3:

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sandwich-structured ceramic-polymer composite electrolyte, characterized in that, It is formed by polymerization of an intermediate layer and an outer layer precursor coated on both sides thereon. The intermediate layer is obtained by prepolymerization of an intermediate layer precursor composed of LLZO, LiTFSI, a first dioxapentane prepolymer and a first initiator. The outer layer precursor includes SiO2, MXene, LiTFSI, a second dioxapentane prepolymer and a second initiator.

2. The composite electrolyte according to claim 1, characterized in that, The thickness of the intermediate layer is 25~40μm; and / or the thickness of the outer precursor after polymerization is 15~30μm.

3. The composite electrolyte according to claim 1, characterized in that, The number-average molecular weight (Mn) of the first dioxane prepolymer and / or the second dioxane prepolymer is 60,000 to 70,000 g / mol.

4. The composite electrolyte according to claim 1, characterized in that, In the intermediate layer precursor, the mass ratio of LLZO, LiTFSI and dioxane first prepolymer is (20~40):(10~20):(80~100). And / or, in the outer precursor, the mass ratio of SiO2, MXene, LiTFSI to dioxane second prepolymer is (1~3):(0.5~2):(10~20):(80~100).

5. The composite electrolyte according to claim 1, characterized in that, The LLZO is a cubic phase with a particle size of 200~500 nm; And / or, the MXene is titanium carbide nanosheets with a thickness of 1~5 nm and a sheet diameter of 1~3 μm.

6. The composite electrolyte according to claim 1, characterized in that, The first initiator and / or the second initiator are each independently selected from one or more of Al(OTf)3, Sc(OTf)3, Sn(OTf)2, and LiPF6.

7. The method for preparing the composite electrolyte according to any one of claims 1 to 6, characterized in that, step include: S1. After dispersing the intermediate layer precursor, coating it onto the substrate and evaporating some of the solvent, prepolymerize to obtain the intermediate layer; S2. After coating the upper surface of the intermediate layer with a dispersion containing the outer layer precursor, the temperature is raised to carry out deep polymerization, and the substrate is peeled off to obtain an intermediate layer with an outer layer coated on one side; S3. After coating the other side of the intermediate layer obtained in S2 with a dispersion containing the outer layer precursor, the mixture is deeply polymerized again to obtain a sandwich-structured ceramic-polymer composite electrolyte.

8. The preparation method according to claim 7, characterized in that, In step S1, the prepolymerization conditions are a vacuum of -0.095 to -0.10 MPa and a prepolymerization temperature of 60 to 70°C for 40 to 50 minutes. And / or, in step S2, the deep polymerization conditions are: vacuum degree -0.095~-0.10MPa, polymerization at 70~80℃ for 90~100min; And / or, in step S3, the deep polymerization conditions are: vacuum degree -0.095~-0.10MPa, polymerization at 70~80℃ for 90~100min.

9. The application of the ceramic-polymer composite electrolyte according to any one of claims 1 to 6, or the ceramic-polymer composite electrolyte prepared by the preparation method according to any one of claims 7 to 8, in solid-state batteries.

10. A solid-state battery, characterized in that, The solid-state battery includes the ceramic-polymer composite electrolyte according to any one of claims 1 to 6, or the ceramic-polymer composite electrolyte prepared by the preparation method according to any one of claims 7 to 8.

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