Solid-state electrolyte membrane, method for preparing the same, and use thereof

Abstract

The application relates to a solid-state electrolyte film and a preparation method and application thereof. The solid-state electrolyte film comprises a high-porosity support film and a heterogeneous electrolyte layer arranged on the surface of the high-porosity support film, wherein the heterogeneous electrolyte layer comprises polymer monomers, a lithium salt electrolyte and a nano-oxide electrolyte; and the nano-oxide electrolyte is gradiently distributed in the heterogeneous electrolyte layer. In the application, the nano-oxide electrolyte is gradiently distributed in the heterogeneous electrolyte layer, so that the oxide concentration in the lower layer of the heterogeneous electrolyte layer is low, the support film is fully infiltrated and filled, the oxide electrolyte concentration in the upper layer of the heterogeneous electrolyte layer is high, a high-mechanical-strength dense electronic insulation layer is formed, the phenomenon of large difference in ion conductivity between the polymer layer and the composite electrolyte layer in the same multilayer heterogeneous electrolyte structure is avoided, the lithium precipitation phenomenon is avoided, meanwhile, the abnormal phenomenon of delamination between the heterogeneous layers due to solidification effect and battery cycle is also avoided, and the cycle life of the battery is further improved.

Description

Technical Field

[0001] This invention relates to the field of ion battery technology, specifically to a solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Solid-state ion batteries reduce or eliminate the use of liquid electrolytes, thus significantly improving battery safety. Solid-state electrolytes can be divided into inorganic solid-state electrolytes and polymer solid-state electrolytes. Inorganic solid-state electrolytes generally have high ionic conductivity and mechanical strength, but their solid-solid contact with the electrode leads to a large interfacial resistance, hindering ion transport and easily causing short circuits. Organic polymer solid-state electrolytes have advantages such as light weight, good elasticity, and simple processing, but their ionic conductivity is relatively low. As important components of solid-state ion batteries, combining polymers and inorganic electrolytes is currently an effective strategy to facilitate the rapid application and promotion of solid-state electrolytes, for example, in the form of similar multilayer heterostructure electrolytes.

[0003] This type of multilayer heterostructure electrolyte is mostly prepared by coating polymer electrolytes and composite electrolytes layer by layer. The layer-by-layer coating method may cause separation due to different curing effects caused by different compositions of each layer. It may also cause interlayer separation during battery cycling. At the same time, due to the large differences in composition between each layer, the ionic conductivity also varies greatly, which may lead to lithium plating between layers during cycling, affecting the service life. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of short service life and poor cycle stability of electrolyte membranes in the prior art, thereby providing a solid electrolyte membrane, its preparation method and application to solve the above problems.

[0005] In a first aspect, the present invention provides a solid electrolyte membrane, comprising a high-porosity support membrane and a heterogeneous electrolyte layer disposed on the surface of the high-porosity support membrane, wherein the heterogeneous electrolyte layer comprises a polymer monomer, a lithium salt electrolyte and a nano-oxide electrolyte; the nano-oxide electrolyte is gradient-distributed in the heterogeneous electrolyte layer on the surface of the high-porosity support membrane.

[0006] In one optional embodiment, the polymer monomer includes acrylate crosslinking agent monomers; The lithium salt electrolyte is prepared by dissolving lithium salt in a carbonate organic solvent.

[0007] In one optional embodiment, the acrylate crosslinking agent monomer includes one or more of the following: polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, hexanediol di(meth)acrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate. The lithium salt includes one or more of LiPF6, LiTFSI, LiFSI, LiDFOB, and LiBOB; The carbonate organic solution includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and methyl propyl carbonate.

[0008] In one optional embodiment, the porosity of the high-porosity supported membrane is 80-90%. The high-porosity support membrane includes any one of polypropylene membrane, polyethylene membrane, PET membrane, polyimide membrane, polyacrylonitrile membrane, and CMC cellulose membrane.

[0009] In one optional embodiment, the nano-oxide electrolyte includes one or more of LLZO, LLZTO, LATP, LAGP, LLTO, Al2O3, and SiO2.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned solid electrolyte membrane, comprising the following steps: S1: The polymer monomer and lithium salt electrolyte are mixed evenly to obtain the first solid electrolyte precursor; S2: The polymer monomer, lithium salt electrolyte and nano-oxide electrolyte are mixed evenly to obtain the second solid electrolyte precursor; S3: The first solid electrolyte precursor is coated on the surface of the positive or negative electrode to form a wetted electrolyte layer, and the wetted electrolyte layer is prepolymerized using a UV lamp. S4: Apply a high-porosity support membrane to the surface of the electrolyte layer; S5: The first solid electrolyte precursor and the second solid electrolyte precursor are simultaneously coated onto the surface of the high-porosity support membrane to form a heterogeneous electrolyte layer, with the first solid electrolyte precursor coating located below and between the second solid electrolyte precursor coating and the high-porosity support membrane. S6: Use a UV lamp to rapidly polymerize and solidify the heterogeneous electrolyte layer, then wind it up to obtain a solid electrolyte membrane.

[0011] In one optional embodiment, in step S1, when preparing the first solid electrolyte precursor or the second solid electrolyte precursor, a plasticizer and an initiator are also added. The plasticizer includes one or more of succinic acid, adiponitrile, and sebacate. The initiator includes one or more of benzophenone, methyl benzoylformate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2,4-diethylthioxanthrone, and α-hydroxyisobutyroylbenzene.

[0012] In one optional embodiment, the concentration of lithium salt relative to carbonate organic solvent in the lithium salt electrolyte is 1-2 mol / L; In the first solid electrolyte precursor, by mass, the acrylate crosslinking agent monomer accounts for 10-15 parts, the lithium salt electrolyte accounts for 70-90 parts, the plasticizer accounts for 10-40 parts, and the initiator accounts for 0.1-0.5 parts.

[0013] In one optional embodiment, in the second solid electrolyte precursor, by mass parts, the acrylate crosslinking agent monomer accounts for 10-15 parts, the lithium salt electrolyte accounts for 30-50 parts, the plasticizer accounts for 10-40 parts, the nano-oxide electrolyte accounts for 30-60 parts, and the initiator accounts for 0.1-0.5 parts.

[0014] Thirdly, the present invention provides an application of the solid electrolyte membrane described above or the solid electrolyte membrane prepared by the preparation method described above in an ion battery.

[0015] The technical solution of this invention has the following advantages: 1. The present invention provides a solid electrolyte membrane, comprising a high-porosity support membrane and a heterogeneous electrolyte layer disposed on the surface of the high-porosity support membrane, wherein the heterogeneous electrolyte layer comprises a polymer monomer, a lithium salt electrolyte and a nano-oxide electrolyte; the nano-oxide electrolyte is gradient distributed in the heterogeneous electrolyte layer.

[0016] This invention employs a multilayer heterogeneous coating process. First, a first solid electrolyte precursor is coated onto the surface of the positive or negative electrode to form a wetted electrolyte layer, effectively solving the electrode wetting problem. Furthermore, the nano-oxide electrolyte is gradient-distributed within the heterogeneous electrolyte layer. This results in a low oxide concentration in the lower layer, fully wetting and filling the high-porosity support membrane, while the upper layer has a high oxide electrolyte concentration, forming a dense, high-mechanical-strength electronic insulating layer. Due to diffusion, the oxide electrolyte in the second solid electrolyte precursor diffuses into the first solid electrolyte precursor, forming a three-dimensional gradient composite electrolyte layer. This three-dimensional gradient distribution provides an effective transition, allowing for microscopic control and optimization of the interlayer interface. This avoids the significant difference in ionic conductivity between the polymer layer and the composite electrolyte layer in similar multilayer heterogeneous electrolyte structures, which can lead to lithium plating. It also prevents abnormal delamination between heterogeneous layers due to curing effects and battery cycling, further improving the battery's cycle life.

[0017] 2. The solid electrolyte membrane preparation method provided by the present invention uses a UV lamp to enable the heterogeneous electrolyte layer to be rapidly and completely solidified in a very short time, thereby completing the gradient distribution of nano-oxide electrolyte in the heterogeneous electrolyte layer.

[0018] 3. The plasticizer added in this invention has a strong ability to dissolve lithium salts and relatively good electrochemical stability. The plasticizer that dissolves lithium salts is a high-performance solid ionic conductor in the plastic crystal phase. It achieves high ionic conductivity through the dynamic disordered environment provided by its molecular rotation. As a plasticizer, it can significantly improve the performance of solid electrolytes, increase the room temperature ionic conductivity of solid electrolytes, and further improve the first efficiency and cycle stability of batteries. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a process flow diagram of the solid electrolyte membrane preparation method in Embodiment 1 of the present invention; Figure 2 This is an SEM image of the solid electrolyte membrane prepared in Example 1 of the present invention. Detailed Implementation

[0021] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0022] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0023] Example 1 This embodiment provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: according to... Figure 1 The process flow diagram shown illustrates the following steps performed under constant temperature conditions of 25℃ and dew point temperature of -60℃: S1: Ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 3:7. LiFSI and LiPF6 were added, and the mixture was stirred at 500 rpm for 5 min until homogeneous to prepare a lithium salt electrolyte. The concentration of LiFSI relative to the organic solvent was 1 mol / L, and the concentration of LiPF6 relative to the organic solvent was 0.5 mol / L. Pre-melted succinate liquid was added to the lithium salt electrolyte, and the mixture was stirred at 500 rpm for 5 min until homogeneous to obtain a lithium salt mixture. Butyl acrylate and ethoxylated trimethylolpropionate were added to the lithium salt mixture. The methyl propane triacrylate was stirred at 1000 r / min for 5 min to obtain a uniformly mixed slurry. Then, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide was added to the slurry and stirred at 1000 r / min for 10 min to obtain a uniformly mixed first solid electrolyte precursor. The precursor consisted of, by mass, 80 parts lithium salt electrolyte, 10 parts succinate, 1 part ethoxylated trimethylolpropane triacrylate, 10 parts butyl acrylate, and 0.1 parts 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. S2: Ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 3:7. LiFSI and LiPF6 were added, and the mixture was stirred at 500 rpm for 5 min to prepare a lithium salt electrolyte. The concentration of LiFSI relative to the organic solvent was 1 mol / L, and the concentration of LiPF6 relative to the organic solvent was 0.5 mol / L. Pre-melted succinate liquid was added to the lithium salt electrolyte, and the mixture was stirred at 500 rpm for 5 min to obtain a lithium salt mixture. Butyl acrylate and ethoxylated trimethylolpropane triacrylate were added to the lithium salt mixture, and the mixture was stirred at 1000 rpm for 5 min to obtain... To obtain a uniformly mixed slurry, add the nano-oxide electrolyte LATP to the slurry and stir at 3000 r / min for 120 min to obtain an oxide electrolyte dispersion slurry. Then add the initiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and stir at 1000 r / min for 10 min to obtain a uniformly mixed second solid electrolyte precursor. In this precursor, by mass, the lithium salt electrolyte accounts for 40 parts, succinate accounts for 10 parts, ethoxylated trimethylolpropane triacrylate accounts for 1 part, butyl acrylate accounts for 10 parts, LATP accounts for 40 parts, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide accounts for 0.2 parts. S3: The first solid electrolyte precursor obtained in step S1 is coated onto the surface of the negative electrode to form a wetted electrolyte layer with a coating thickness of 5 μm. Then, the wetted electrolyte layer is pre-polymerized using a UV lamp with an irradiation intensity of 1 mW / cm². 2 The irradiation time was 0.5 min; S4: A PET film is coated onto the surface of the electrolyte-wetting layer; the porosity of the PET film is 85%. S5: The first solid electrolyte precursor and the second solid electrolyte precursor are simultaneously coated onto the surface of the polypropylene film through a dual-cavity dual-component co-extrusion die to form a heterogeneous electrolyte layer. The coating of the first solid electrolyte precursor is on the bottom and the coating of the second solid electrolyte precursor is on the top. The coating is applied simultaneously and the coating thickness is 20μm. S6: The heteroelectrolyte layer is rapidly polymerized and cured using a UV lamp with an irradiation intensity of 100 mW / cm². 2 The irradiation time is 0.5 minutes, followed by winding.

[0024] The SEM image of the solid electrolyte membrane prepared in this embodiment is shown below. Figure 2 As shown.

[0025] Example 2 This embodiment provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: performing the following steps under constant temperature of 25°C and dew point temperature of -60°C: S1: Propylene carbonate and dimethyl carbonate are mixed at a volume ratio of 3:7. LiTFSI and LiDFOB are added, and the mixture is stirred at 500 rpm for 5 min to prepare a lithium salt electrolyte. The concentration of LiTFSI relative to the organic solvent is 1 mol / L, and the concentration of LiDFOB relative to the organic solvent is 0.5 mol / L. Pre-melted adiponitrile liquid is added to the lithium salt electrolyte, and the mixture is stirred at 500 rpm for 5 min to obtain a lithium salt mixture. Butyl acrylate and polyethylene glycol diacrylate were added to the lithium salt mixture and stirred at 1000 r / min for 5 min to obtain a uniformly mixed slurry. The initiator benzophenone was then added to the slurry and stirred at 1000 r / min for 10 min to obtain a uniformly mixed first solid electrolyte precursor. The precursor consisted of 70 parts by mass of lithium salt electrolyte, 20 parts by adiponitrile, 2 parts by polyethylene glycol diacrylate, 13 parts by butyl acrylate, and 0.5 parts by benzophenone. S2: Propylene carbonate and dimethyl carbonate are mixed at a volume ratio of 3:7. LiTFSI and LiDFOB are added, and the mixture is stirred at 500 rpm for 5 minutes to prepare a lithium salt electrolyte. The concentration of LiTFSI relative to the organic solvent is 1 mol / L, and the concentration of LiDFOB relative to the organic solvent is 0.5 mol / L. Pre-melted adiponitrile liquid is added to the lithium salt electrolyte, and the mixture is stirred at 500 rpm for 5 minutes to obtain a lithium salt mixture. Butyl acrylate and polyethylene glycol diacrylate are added to the lithium salt mixture at a volume ratio of 10... Stir at 00 r / min for 5 min to obtain a uniformly mixed slurry. Add nano-oxide electrolyte LLZO to the slurry and stir at 3000 r / min for 120 min to obtain an oxide electrolyte dispersion slurry. Then add initiator benzophenone and stir at 1000 r / min for 10 min to obtain a uniformly mixed second solid electrolyte precursor. The precursor contains, by mass, 50 parts lithium salt electrolyte, 20 parts adiponitrile, 2 parts polyethylene glycol diacrylate, 13 parts butyl acrylate, 30 parts LLZO, and 0.5 parts benzophenone. S3: The first solid electrolyte precursor obtained in step S1 is coated onto the surface of the positive electrode to form a wetted electrolyte layer with a coating thickness of 5 μm. Then, the wetted electrolyte layer is pre-polymerized using a UV lamp with an irradiation intensity of 1 mW / cm². 2 The irradiation time was 0.5 min; S4: A polyethylene film is applied to the surface of the electrolyte-wetting layer; the porosity of the polyethylene film is 80%. S5: The first solid electrolyte precursor and the second solid electrolyte precursor are simultaneously coated onto the surface of the polyethylene film through a dual-cavity dual-component co-extrusion die to form a heterogeneous electrolyte layer. The coating of the first solid electrolyte precursor is on the bottom and the coating of the second solid electrolyte precursor is on the top. The coating is applied simultaneously and the coating thickness is 20μm. S6: The heteroelectrolyte layer is rapidly polymerized and cured using a UV lamp with an irradiation intensity of 100 mW / cm². 2 The irradiation time is 0.5 minutes, followed by winding.

[0026] Example 3 This embodiment provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: performing the following steps under constant temperature of 25°C and dew point temperature of -60°C: S1: Diethyl carbonate and methyl propyl carbonate were mixed at a volume ratio of 3:7. LiPF6 and LiBOB were added, and the mixture was stirred at 500 rpm for 5 min until homogeneous to prepare a lithium salt electrolyte. The concentration of LiPF6 relative to the organic solvent was 1 mol / L, and the concentration of LiBOB relative to the organic solvent was 0.5 mol / L. Pre-melted sebacate was added to the lithium salt electrolyte, and the mixture was stirred at 500 rpm for 5 min until homogeneous to obtain a lithium salt mixture. Butyl acrylate and ethylene glycol diacrylate were added to the mixture, and stirred at 1000 r / min for 5 min to obtain a uniformly mixed slurry. Methyl benzoylformate, the initiator, was then added to the slurry, and stirred at 1000 r / min for 10 min to obtain a uniformly mixed first solid electrolyte precursor. The precursor consisted of 90 parts by mass of lithium salt electrolyte, 10 parts of sebacate, 1 part of ethylene glycol diacrylate, 10 parts of butyl acrylate, and 0.1 parts of methyl benzoylformate. S2: Diethyl carbonate and methyl propyl carbonate are mixed at a volume ratio of 3:7. LiPF6 and LiBOB are added, and the mixture is stirred at 500 rpm for 5 min to prepare a lithium salt electrolyte. The concentration of LiPF6 relative to the organic solvent is 1 mol / L, and the concentration of LiBOB relative to the organic solvent is 0.5 mol / L. Pre-melted sebacate is added to the lithium salt electrolyte, and the mixture is stirred at 500 rpm for 5 min to obtain a lithium salt mixture. Butyl acrylate and ethylene glycol diacrylate are added to the lithium salt mixture, and the mixture is stirred at 1000 rpm. Stirring at a speed of n for 5 min yields a uniformly mixed slurry. Add nano-oxide electrolyte LLZTO to the slurry and stir at 3000 r / min for 120 min to obtain an oxide electrolyte dispersion slurry. Then add initiator methyl benzoylformate and stir at 1000 r / min for 10 min to obtain a uniformly mixed second solid electrolyte precursor. The precursor comprises, by mass, 30 parts lithium salt electrolyte, 40 parts sebacate, 1 part ethylene glycol diacrylate, 10 parts butyl acrylate, 60 parts LLZTO, and 0.2 parts methyl benzoylformate. S3: The first solid electrolyte precursor obtained in step S1 is coated onto the surface of the negative electrode to form a wetted electrolyte layer with a coating thickness of 5 μm. Then, the wetted electrolyte layer is pre-polymerized using a UV lamp with an irradiation intensity of 1 mW / cm². 2 The irradiation time was 0.5 min; S4: A polyethylene film is applied to the surface of the electrolyte-wetting layer; the porosity of the polyethylene film is 80%. S5: The first solid electrolyte precursor and the second solid electrolyte precursor are simultaneously coated onto the surface of the polyethylene film through a dual-cavity dual-component co-extrusion die to form a heterogeneous electrolyte layer. The coating of the first solid electrolyte precursor is on the bottom and the coating of the second solid electrolyte precursor is on the top. The coating is applied simultaneously and the coating thickness is 20μm. S6: The heteroelectrolyte layer is rapidly polymerized and cured using a UV lamp with an irradiation intensity of 100 mW / cm². 2 The irradiation time is 0.5 minutes, followed by winding.

[0027] Example 4 This embodiment provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: preparing the solid electrolyte membrane under constant temperature of 25°C and dew point temperature of -60°C, which differs from Embodiment 1. In steps S1 and S2, the crosslinking agent monomer is selected as 1,6-hexanediol diacrylate; In step S2, the nano-oxide electrolyte is LAGP; The remaining steps are the same as in Example 1.

[0028] Example 5 This embodiment provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: preparing the solid electrolyte membrane under constant temperature of 25°C and dew point temperature of -60°C, which differs from Embodiment 1. In steps S1 and S2, the crosslinking agent monomer is selected from hexanediol di(meth)acrylate; In step S2, the nano-oxide electrolyte is LLTO; The remaining steps are the same as in Example 1.

[0029] Example 6 This embodiment provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: preparing the solid electrolyte membrane under constant temperature of 25°C and dew point temperature of -60°C, which differs from Embodiment 1. In steps S1 and S2, the crosslinking agent monomer is pentaerythritol triacrylate; In step S2, Al2O3 is selected as the nano-oxide electrolyte; The remaining steps are the same as in Example 1.

[0030] Example 7 This embodiment provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: preparing the solid electrolyte membrane under constant temperature of 25°C and dew point temperature of -60°C, which differs from Embodiment 1. In steps S1 and S2, the crosslinking agent monomer is pentaerythritol tetraacrylate; In step S2, the nano-oxide electrolyte is SiO2; The remaining steps are the same as in Example 1.

[0031] Comparative Example 1 This comparative example provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: preparing the solid electrolyte membrane under constant temperature of 25°C and dew point temperature of -60°C. The difference from Example 1 is that... In step S5, only the second solid electrolyte precursor is coated onto the surface of the polyethylene film, and the coating thickness is 10 μm. The remaining steps are the same as in Example 1.

[0032] Comparative Example 2 This comparative example provides a solid electrolyte membrane and a method for preparing the solid electrolyte membrane, including: preparing the solid electrolyte membrane under constant temperature of 25°C and dew point temperature of -60°C. The difference from Example 1 is that... In step S5, only the first solid electrolyte precursor is coated onto the surface of the polyethylene film, and the coating thickness is 10 μm. The remaining steps are the same as in Example 1.

[0033] Test Example 1 The solid electrolyte membranes prepared in Examples 1-7 and Comparative Examples 1-2 of this invention were subjected to battery cycle performance tests. The test methods and results are as follows: 1. Lithium battery assembly: Graphite anode is selected, and the solid electrolyte membrane prepared in each embodiment and comparative example is directly coated on the surface of graphite anode. It is then die-cut, stacked, and welded with 811NCM cathode to form a soft pack battery.

[0034] 2. Battery cycle performance test: Perform a 0.5C rate charge-discharge cycle test and measure the number of cycles when the capacity decays to 80%.

[0035] Testing equipment: Xinwei test cabinet, 5V 300A, accuracy ±0.2%FS Cyclic steps: Charge at a constant current of 0.5C to 4.2V, charge at a constant voltage of 4.2V to the current cutoff point of 0.05C, let stand for 15 minutes, and discharge at a constant current of 0.5C to the cutoff point of 2.75V.

[0036]

[0037] A comparison of the data from Example 1 and Comparative Examples 1-2 revealed that the solid electrolyte membrane prepared in Example 1 exhibited significantly higher initial cycle capacity and cycle counts when capacity decayed to 80% compared to the solid electrolyte membranes prepared in Comparative Examples 1 and 2. This is because the gradient distribution of oxides within the electrolyte layer allows for more microscopic control and optimization of the interlayer interface, preventing the significant difference in ionic conductivity between the polymer layer and the composite electrolyte layer in similar multilayer heterogeneous electrolyte structures, which could lead to lithium plating. Furthermore, it avoids the abnormal phenomenon of delamination between heterogeneous layers due to curing effects and battery cycling, further improving the battery's cycle life.

[0038] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A solid electrolyte membrane, characterized in that, It includes a high-porosity support membrane and a heterogeneous electrolyte layer disposed on the surface of the high-porosity support membrane. The heterogeneous electrolyte layer includes a polymer monomer, a lithium salt electrolyte, and a nano-oxide electrolyte. The nano-oxide electrolyte is distributed in a gradient within the heterogeneous electrolyte layer.

2. The solid electrolyte membrane according to claim 1, characterized in that, The polymer monomers include acrylate crosslinking agent monomers; The lithium salt electrolyte is prepared by dissolving lithium salt in a carbonate organic solvent.

3. The solid electrolyte membrane according to claim 2, characterized in that, The acrylate crosslinking agent monomer includes: One or more of the following: polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, hexanediol di(meth)acrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate. The lithium salt includes one or more of LiPF6, LiTFSI, LiFSI, LiDFOB, and LiBOB; The carbonate organic solution includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and methyl propyl carbonate.

4. The solid electrolyte membrane according to claim 1, characterized in that, The porosity of the high-porosity supported membrane is 80-90%; The high-porosity support membrane includes any one of polypropylene membrane, polyethylene membrane, PET membrane, polyimide membrane, polyacrylonitrile membrane, and CMC cellulose membrane.

5. The solid electrolyte membrane according to claim 1, characterized in that, The nano-oxide electrolyte includes one or more of LLZO, LLZTO, LATP, LAGP, LLTO, Al2O3, and SiO2.

6. A method for preparing a solid electrolyte membrane, characterized in that, Includes the following steps: S1: The polymer monomer and lithium salt electrolyte are mixed evenly to obtain the first solid electrolyte precursor; S2: The polymer monomer, lithium salt electrolyte and nano-oxide electrolyte are mixed evenly to obtain the second solid electrolyte precursor; S3: The first solid electrolyte precursor is coated on the surface of the positive or negative electrode to form a wetted electrolyte layer, and the wetted electrolyte layer is prepolymerized using a UV lamp. S4: Apply a high-porosity support membrane to the surface of the electrolyte layer; S5: The first solid electrolyte precursor and the second solid electrolyte precursor are simultaneously coated onto the surface of the high-porosity support membrane to form a heterogeneous electrolyte layer, with the coating of the first solid electrolyte precursor located between the coating of the second solid electrolyte precursor and the high-porosity support membrane. S6: Use a UV lamp to rapidly polymerize and solidify the heterogeneous electrolyte layer, then wind it up to obtain a solid electrolyte membrane.

7. The preparation method according to claim 6, characterized in that, In step S1, when preparing the first solid electrolyte precursor or the second solid electrolyte precursor, a plasticizer and an initiator are also added. The plasticizer includes one or more of succinic acid, adiponitrile, and sebacate. The initiator includes one or more of benzophenone, methyl benzoylformate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2,4-diethylthioxanthrone, and α-hydroxyisobutyroylbenzene.

8. The preparation method according to claim 6, characterized in that, In the lithium salt electrolyte, the concentration of lithium salt relative to the carbonate organic solvent is 1-2 mol / L; and / or, In the first solid electrolyte precursor, by mass, the acrylate crosslinking agent monomer accounts for 10-15 parts, the lithium salt electrolyte accounts for 70-90 parts, the plasticizer accounts for 10-40 parts, and the initiator accounts for 0.1-0.5 parts.

9. The preparation method according to claim 6, characterized in that, In the second solid electrolyte precursor, by mass, the acrylate crosslinking agent monomer accounts for 10-15 parts, the lithium salt electrolyte accounts for 30-50 parts, the plasticizer accounts for 10-40 parts, the nano-oxide electrolyte accounts for 30-60 parts, and the initiator accounts for 0.1-0.5 parts.

10. The application of the solid electrolyte membrane according to any one of claims 1-5 or the solid electrolyte membrane prepared by the preparation method of claims 6-9 in an ion battery.

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