A metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material and its preparation method and application

Abstract

The invention belongs to the technical field of lithium battery new energy storage materials, and specifically relates to a metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material and a preparation method and application thereof. The invention comprises the following steps: dissolving cyclic metal oxygen clusters and vinyl ether in a solvent to cause a replacement reaction, adding a precipitant to separate the reaction product after the replacement, adding the solvent, a polyethylene glycol derivative and an initiator to the reaction product, causing a free radical polymerization reaction to form a polymer with a cross-linked structure, and obtaining a precursor polymer solution; and adding a lithium salt to the polymer solution to obtain a metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material. The cross-linked three-dimensional network polymer layer prepared by the invention can be used as a positive electrode interface protection layer and a negative electrode interface protection layer at the same time. The polymer protection layer contains abundant functional groups for conducting lithium ions, and can improve the conduction rate of lithium ions in the polymer.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy storage materials for lithium batteries, and specifically relates to a metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material, a preparation method and an application thereof. Background Art

[0002] With the rapid development of portable electronic products, smart grid storage and new energy vehicles, the demand for high energy density rechargeable batteries is increasing. However, the dominant plasma batteries (LIBs) in the market currently use graphite as the negative electrode and lithium with layered oxides or phosphates as the positive electrode (such as LiCoO 2 、LiFePO 4 ), whose energy density is rapidly reaching a theoretical limit. In contrast, lithium (Li) metal has a high theoretical specific capacity (3860 mAh g -1 ), the lowest potential (-3.04 V vs standard hydrogen electrode) and the lowest density (0.534 g cm -3 )'s advantages, coupled with the high-nickel ternary positive electrode, are considered to be the best choice for future high-energy density batteries.

[0003] However, the short cycle life and safety issues caused by uncontrollable lithium dendrite growth and serious side reactions between lithium metal and electrolyte seriously hinder the practical application of lithium metal batteries (LMBs). In addition, the electrolyte solid interface film (SEI film) formed at the interface between lithium metal and electrolyte generally has the disadvantages of uneven thickness and fragility, which is easily broken by lithium dendrites, causing the freshly exposed lithium to continuously react with the electrolyte, resulting in a serious decline in battery performance. At the same time, the positive electrode surface under high voltage is also attacked by the electrolyte, and there are problems such as easy cracking, fragile positive electrode electrolyte interface film (CEI film), and transition metal dissolution. Here, a stable artificial polymer electrolyte interface protective layer SEI or CEI can well protect the positive and negative electrodes from corrosion by the electrolyte, and its excellent mechanical properties can effectively alleviate the electrode volume change during the cycle. However, conventional polymers such as polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, etc. have high crystallinity, which limits the ability of polymer segments to conduct lithium ions. The interface protective layer cannot effectively conduct lithium ions, thereby affecting the conductivity of the battery and reducing the battery's rate performance. In addition, conventional polymer protective films have poor mechanical strength and cannot inhibit the growth of lithium dendrites. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material and its preparation method and application. The present invention aims to solve the problems of electrolyte corrosion and solid electrolyte interface film instability in existing high-voltage lithium metal batteries, and aims to provide a design principle and preparation method of an artificial polymer interface protection layer for high-voltage lithium metal batteries. The cross-linked three-dimensional network polymer layer prepared by the present invention can be used as both a positive electrode interface protection layer and a negative electrode interface protection layer.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material comprises the following steps:

[0007] The cyclic metal oxide cluster and vinyl ether are dissolved in a solvent to undergo a replacement reaction. The unstable sites of the sixteen monodentate-connected ethylene glycol on the cyclic metal oxide cluster are easily replaced by the vinyl ether in the solution, so that the sixteen metal atoms on the ring can be modified by different active functional groups, such as glycidol, olefin, hydroxyl, amino and carboxyl groups. These groups can further react with polyethylene glycol derivative monomers to form a cross-linked or hyperbranched polymer with the metal oxide cluster as the core, thereby improving its thermal stability, mechanical properties and flame retardancy. A precipitant is then added to separate the reaction product after the replacement and then dissolved in a solvent to obtain a solution A, and impurities replaced by the reaction and excess vinyl ether are removed;

[0008] Adding polyethylene glycol derivatives and initiators to the solution A, the polyethylene glycol derivatives will react with the active functional groups on the metal oxygen clusters to form a polymer with a cross-linked structure, and stirring to obtain a precursor polymer solution;

[0009] Lithium salt is added to the precursor polymer solution to improve the ionic conductivity of the polymer film, and the solution is heated and stirred to obtain a metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material.

[0010] In a preferred embodiment of the present invention, the cyclic metal oxide cluster is one of cyclic titanium oxide cluster, cyclic tin oxide cluster, cyclic aluminum oxide cluster and cyclic magnesium oxide cluster, wherein when the replacement reaction occurs, the mass fraction of the cyclic metal oxide cluster in the solvent is 1-20%.

[0011] In a preferred embodiment of the present invention, the vinyl ether is one of 4-hydroxybutyl vinyl ether, triethylene glycol divinyl ether, tert-butyl n-propyl vinyl ether, 3-chloroethyl vinyl ether, and isobutyl vinyl ether, wherein the mass ratio of the vinyl ether to the cyclic metal oxide cluster is 5 to 50:1.

[0012] In a preferred embodiment of the present invention, the polyethylene glycol derivative is one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, diamino polyethylene glycol, dicarboxyl polyethylene glycol, dimercapto polyethylene glycol, and polyethylene glycol diglycidyl ether, wherein the mass ratio of the polyethylene glycol derivative to the cyclic metal oxide cluster is 10 to 100:1.

[0013] In a preferred embodiment of the present invention, the lithium salt is one or a mixed salt of lithium perchlorate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonylimide), lithium bis(fluorosulfonylimide), and lithium nitrate, wherein the amount of the lithium salt accounts for 5wt% to 30wt% of the total mass of the precursor polymer solution.

[0014] In a preferred embodiment of the present invention, the solvent in which the replacement reaction occurs and the solvent added to the reactants are of the same type, the solvent is one of dimethyl carbonate, dichloropropane, dimethyl sulfoxide, N,N-dimethylacetamide, dichloromethane, and chloroform, the precipitant is one of N-methylpyrrolidone, acetone, and tetrahydrofuran, and the volume ratio of the solvent used in the replacement reaction to the precipitant is 1:5 to 20.

[0015] In a preferred embodiment of the present invention, the initiator is one or more of azobisisobutyronitrile, azobisisoheptylnitrile, diisotoluene peroxide, and benzoyl peroxide, wherein the mass of the initiator is 0.2wt% to 2wt% of the mass of the polyethylene glycol derivative, and the heating temperature is 40 to 100°C.

[0016] Another object of the present invention is to provide a metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material prepared by any of the preparation methods described above.

[0017] The third object of the present invention is to provide an application of the above-mentioned metal oxygen cluster in situ cross-linked polymer solid electrolyte interface protection layer material in a high voltage lithium metal battery, and the application method is: coating the metal oxygen cluster in situ cross-linked polymer solid electrolyte interface protection layer material on the surface of the ternary positive electrode and the surface of the negative electrode, and heating and drying.

[0018] In a preferred embodiment of the present invention, the ternary positive electrode is a high-nickel ternary positive electrode, the negative electrode is a lithium metal negative electrode, the heating and drying temperature is 40 to 100° C., and the heating and drying time is 2 to 24 hours.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The cross-linked three-dimensional network polymer layer prepared by the present invention can be used as both the positive electrode interface protection layer (artificial CEI film) and the negative electrode interface protection layer (artificial SEI film). The polymer protection layer contains abundant functional groups that conduct lithium ions, which can improve the conduction rate of lithium ions in the polymer. The three-dimensional network structure formed with metal oxygen clusters as the core has good mechanical properties. On the positive electrode side, it can alleviate the oxidative decomposition of the electrolyte in the high voltage area, inhibit the volume change of the high-nickel ternary electrode material, and prevent the formation of cracks; on the negative electrode side, the prepared cross-linked polymer coating can effectively inhibit the growth of lithium dendrites and prevent further reaction between metal lithium and electrolyte, thereby inhibiting the pulverization of lithium metal, thereby improving the cycle life and safety performance of the battery.

[0021] 2. The metal oxide clusters used in the present invention have multi-functional group sites. The unstable sites of the sixteen monodentate coordinated ethylene glycol on the ring can be easily exchanged by the functionalized functional groups in the solution, producing a cross-linked structure with multiple surface functions, increasing the mechanical strength of the polymer protective layer, and can effectively inhibit the stress deformation of the positive electrode and the lithium dendrites of the negative electrode.

[0022] 3. The polyethylene glycol derivatives and vinyl ethers selected in the present invention have abundant ether oxygen, epoxy and carbonyl oxygen functional groups in their molecular structures, which can serve as binding sites for lithium ions and effectively promote the transmission of lithium ions.

[0023] 4. The polyethylene glycol derivative selected in the present invention is a flexible polymer chain segment, which can serve as the supporting skeleton of the positive electrode material protective layer and the negative electrode material protective layer at the same time, and can effectively alleviate the volume change of the positive electrode and the negative electrode during the charge and discharge process, release stress and maintain the stability of the electrode structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 These are pictures of polymer film formation obtained in Example 1 of the present invention and Comparative Example 1.

[0025] Figure 2 Surface scanning electron micrographs of the polymer protective layers containing a cross-linked structure prepared in Example 1 and Comparative Example 1 of the present invention, A: Example 1; B: Comparative Example 1.

[0026] Figure 3 These are cross-sectional scanning electron microscope images of the lithium metal negative electrodes modified with the artificial polymer protective layers of Example 1 and Comparative Example 1 of the present invention.

[0027] Figure 4 It is a bar graph of the mechanical strength of Examples 1-5 of the present invention and Comparative Example 1.

[0028] Figure 5The cycle performance diagram of the button-type lithium metal battery with the polymer protective layer prepared in Example 1 of the present invention and Comparative Example 1 and the high-nickel ternary NCM811 positive electrode, where the cycle rate is 1C and the positive electrode loading is 12 mg cm -2 , (a) Example 1; (b) Comparative Example 1.

[0029] Figure 6 The rate performance diagram of the button-type lithium metal battery with the polymer protective layer prepared in Example 1 and Comparative Example 1 and the high-nickel ternary NCM811 positive electrode, wherein the cycle rates are 0.2C, 0.5C, 1C, 2C, 3C, 4C and then decrease, and the positive electrode loading is 12 mg cm -2 ; (a) Example 1; (b) Comparative Example 1. DETAILED DESCRIPTION

[0030] The following is a detailed description of the technical solutions in the embodiments of the present invention in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0032] Example 1

[0033] A method for preparing a metal oxide cluster polymer protective layer material for a lithium metal battery comprises the following steps:

[0034] (1) Weigh 0.15 g of cyclic titanium oxide clusters and dissolve them in 2 mL of dichloromethane. Then, add 1 mL of 4-hydroxybutyl vinyl ether to the solution and stir to obtain a uniform and transparent solution. Add 20 mL of acetone and centrifuge to separate a white precipitate. Then, add 2 mL of dichloromethane to dissolve the solution to obtain solution A.

[0035] (2) Add 2 g of polyethylene glycol diacrylate and 0.005 g of initiator azobisisobutyronitrile to the solution A obtained in step (1), and stir thoroughly to obtain a polymer solution.

[0036] (3) Weigh 0.15 g of lithium bis(fluorosulfonyl)imide and 0.05 g of lithium difluorooxalatoborate and add them to the polymer solution obtained in step (2), and stir them thoroughly at 50° C. for 1 h to obtain a protective layer material.

[0037] (4) The protective layer material is uniformly coated on the surface of the high-nickel ternary positive electrode and the surface of the lithium metal negative electrode, and then heated and dried on a heating table at 70° C. to obtain a positive electrode and a negative electrode with a protective layer.

[0038] Example 2

[0039] A method for preparing a metal oxide cluster polymer protective layer material for a lithium metal battery comprises the following steps:

[0040] (1) 0.12 g of cyclic aluminum oxide clusters were weighed and dissolved in 2 mL of chloroform. Then, 1.5 mL of triethylene glycol divinyl ether was added to the solution and stirred to obtain a uniform transparent solution. 20 mL of N-methylpyrrolidone was added and centrifuged to separate a white precipitate. Then, 2 mL of chloroform was added to dissolve the solution to obtain solution A.

[0041] (2) Add 2 g of polyethylene glycol dimethacrylate and 0.007 g of initiator azobisisoheptanenitrile to the solution A obtained in step (1), and stir thoroughly to obtain a polymer solution.

[0042] (3) Weigh 0.2 g of lithium perchlorate and 0.1 g of lithium tetrafluoroborate and add them to the polymer solution obtained in step (2), and stir them thoroughly at 50° C. for 1 h to obtain a protective layer material.

[0043] (4) The protective layer material is uniformly coated on the surface of the high-nickel ternary positive electrode and the surface of the lithium metal negative electrode, and then heated and dried on a heating table at 60° C. to obtain a positive electrode and a negative electrode with a protective layer.

[0044] Example 3

[0045] A method for preparing a metal oxide cluster polymer protective layer material for a lithium metal battery comprises the following steps:

[0046] (1) 0.1 g of cyclic titanium oxide clusters was weighed and dissolved in 3 mL of dimethyl sulfoxide. Then, 1 mL of 3-chloroethyl vinyl ether was added to the solution and stirred to obtain a uniform transparent solution. 20 mL of tetrahydrofuran was added and centrifuged to separate a white precipitate. Then, 3 mL of dimethyl sulfoxide was added to dissolve the solution to obtain solution A.

[0047] (2) Add 3 g of diaminopolyethylene glycol and 0.005 g of initiator azobisisobutyronitrile to the solution A obtained in step (1), and stir thoroughly to obtain a polymer solution.

[0048] (3) Weigh 0.25 g of lithium bis(trifluoromethylsulfonyl)imide and 0.1 g of lithium perchlorate and add them to the polymer solution obtained in step (2), and stir them thoroughly at 50° C. for 1 h to obtain a protective layer material.

[0049] (4) The protective layer material is uniformly coated on the surface of the high-nickel ternary positive electrode and the surface of the lithium metal negative electrode, and then heated and dried on a heating table at 60° C. to obtain a positive electrode and a negative electrode with a protective layer.

[0050] Example 4

[0051] A method for preparing a metal oxide cluster polymer protective layer material for a lithium metal battery comprises the following steps:

[0052] (1) Weigh 0.1 g of cyclic thiocyanate clusters and dissolve them in 2 mL of dimethyl carbonate. Then, add 1 mL of isobutyl vinyl ether to the solution and stir to obtain a uniform and transparent solution. Add 15 mL of tetrahydrofuran and centrifuge to separate a white precipitate. Then, add 2 mL of dimethyl carbonate to dissolve the solution to obtain solution A.

[0053] (2) Add 2 g of dicarboxyl polyethylene glycol and 0.005 g of initiator benzoyl peroxide to the solution A obtained in step (1), and stir thoroughly to obtain a polymer solution.

[0054] (3) Weigh 0.35 g of lithium tetrafluoroborate and 0.15 g of lithium imide bis(fluorosulfonate) and add them to the polymer solution obtained in step (2), and stir them at 50° C. for 1.5 h to obtain a protective layer material.

[0055] (4) The protective layer material is uniformly coated on the surface of the high-nickel ternary positive electrode and the surface of the lithium metal negative electrode, and then heated and dried on a 65° C. heating table to obtain a positive electrode and a negative electrode with a protective layer.

[0056] Example 5

[0057] A method for preparing a metal oxide cluster polymer protective layer material for a lithium metal battery comprises the following steps:

[0058] (1) 0.15 g of cyclic magnesium oxide clusters were weighed and dissolved in 2 mL of dichloropropane, and then 1 mL of 4-hydroxybutyl vinyl ether was added to the solution. After stirring, a uniform transparent solution was obtained. After adding 25 mL of tetrahydrofuran, a white precipitate was separated by centrifugation, and then 2 mL of dichloropropane was added to dissolve the solution to obtain solution A.

[0059] (2) Add 2 g of polyethylene glycol diglycidyl ether and 0.005 g of initiator azobisisoheptanenitrile to the solution A obtained in step (1), and stir thoroughly to obtain a polymer solution.

[0060] (3) Weigh 0.35 g of lithium bis(fluorosulfonyl)imide and 0.05 g of lithium perchlorate and add them to the polymer solution obtained in step (2), and stir them thoroughly at 50° C. for 1 h to obtain a protective layer material.

[0061] (4) The protective layer material is uniformly coated on the surface of the high-nickel ternary positive electrode and the surface of the lithium metal negative electrode, and then heated and dried on a 65° C. heating table to obtain a positive electrode and a negative electrode with a protective layer.

[0062] Comparative Example 1

[0063] A method for preparing a polymer coating comprises the following steps:

[0064] (1) Weigh 1 mL of 4-hydroxybutyl vinyl ether and dissolve it in 2 mL of dichloromethane. Stir to obtain a uniform and transparent solution A.

[0065] (2) Add 2 g of polyethylene glycol diacrylate and 0.005 g of initiator azobisisobutyronitrile to solution A of step (1), and stir thoroughly to obtain a polymer solution.

[0066] (3) Weigh 0.3 g of bis(fluorosulfonyl)imide and 0.1 g of lithium difluorooxalatoborate, add them to the polymer solution prepared in step (2), and stir them thoroughly at 50° C. for 1 h to obtain a precursor solution.

[0067] (4) coating the precursor solution obtained in step (3) on the surface of the positive electrode and the surface of the lithium metal negative electrode, and then heating and drying on a heating table at 70° C. to obtain a positive electrode or a negative electrode with a polymer protective layer.

[0068] Results Analysis

[0069] 1. Morphology test

[0070] (1) Macromorphology test

[0071] The present invention takes the polymer interface protection layer materials prepared in Example 1 and Comparative Example 1 as examples, and tests the macroscopic morphology thereof. The test results are as follows: Figure 1 As shown, the left picture is the protective layer material prepared in Example 1, and the right picture is the protective layer material prepared in Comparative Example 1.

[0072] (2) Micromorphology test

[0073] The present invention takes the lithium metal with a polymer protective layer formed by coating the polymer interface protective layer material prepared in Example 1 on the surface of lithium metal and drying it as an example, and tests are conducted on the microscopic morphology of its surface and cross section, and the test results are as follows: Figure 2 and Figure 3 shown.

[0074] Figure 2 The surface scanning electron micrographs of the artificial polymer protective layer on the surface of lithium metal prepared in Example 1 (Figure A) and Comparative Example 1 (Figure B) are shown in FIG. Figure 2It can be seen that the surface of lithium metal has an obvious polymer protective layer, indicating that a lithium metal negative electrode with polymer protection has been successfully prepared, and compared with Comparative Example 1, the polymer interface film with the addition of cyclic metal oxide clusters is flatter and more uniform, indicating that the polymer interface protection layer material prepared by the present invention can be applied to the negative electrode and used as an artificial solid polymer protective layer for lithium metal.

[0075] Figure 3 is the cross section of the lithium metal modified with the polymer protective layer in Example 1, Figure 3 It can be seen that the protective film fits tightly to the lithium metal surface and has good interface compatibility.

[0076] 2. Mechanical properties

[0077] Figure 4 is a bar graph of the mechanical strength of Examples 1-5 and Comparative Example 1 measured by atomic force microscopy. Figure 4 It can be clearly seen that the addition of cyclic metal oxide clusters significantly improves the mechanical properties of the polymer film, which is attributed to the three-dimensional network structure constructed by them as cross-linked cores.

[0078] 3. Cycle performance test

[0079] The present invention uses the lithium metal with a polymer protective layer obtained in Example 1 and Comparative Example 1 as the negative electrode, and uses the high nickel ternary material with a polymer protective layer obtained in Example 1 and Comparative Example 1 as the positive electrode, and tests the cycle performance thereof according to the following test method, and the test results are as follows: Figure 5 shown.

[0080] Test method: Use a 16mm diameter lithium sheet with a polymer protective layer and 1M LiPF electrolyte 6 Dissolved in a mixed solution of EC and DEC in a volume ratio of 1:1 and an electrolyte with 5% FEC added, the separator is a PP separator (polypropylene separator), and the battery shell model is CR2032.

[0081] Test conditions: The first two cycles were charged and discharged at a rate of 0.1C to activate the battery, and then the charge and discharge cycle test was performed at a rate of 1C. The NCM811 electrode used had a loading of 12 mg / cm 2 The charge and discharge voltage range is 3.0~4.3V.

[0082] And by Figure 5 The test results show that after 400 cycles, the battery assembled in Example 1 still has a specific capacity retention rate of 82%, which is greatly improved compared to 56% in Comparative Example 1, indicating that the prepared polymer protective layer can improve the cycle stability of the battery.

[0083] 4. Rate performance test

[0084] The present invention assembles the negative electrode with a polymer protective layer and the high nickel ternary positive electrode with a polymer protective layer obtained in Example 1 and Comparative Example 1 into a button battery according to the following method, and tests the rate performance thereof respectively, and the test results are as follows: Figure 6 shown.

[0085] Test method: Use a 16mm diameter lithium sheet with a polymer protective layer and 1M LiPF electrolyte 6 Dissolved in a mixed solution of EC and DEC in a volume ratio of 1:1 and an electrolyte with 5% FEC added, the separator is a PP separator (polypropylene separator), and the battery shell model is CR2032.

[0086] Test conditions: The charge and discharge tests were carried out at current densities of 0.2, 0.5, 1, 2, 3, and 4C, increasing first and then decreasing (1C = 200mAh / g). The NCM811 electrode used had a loading of 12mg / cm 2 The charge and discharge voltage range is 3.0~4.3V.

[0087] And by Figure 6 It can be seen from the test results that the polymer protective layer obtained in Example 1 can make the battery have better rate performance, which greatly alleviates the specific capacity attenuation of the lithium metal battery under high rate charge and discharge.

[0088] In summary, the present invention provides a polymer protective layer that can be applied to both high-voltage positive electrodes and lithium metal negative electrodes, wherein the prepared protective layer is a flexible cross-linked polymer protective layer, the oxygen-containing functional groups inside the molecules can promote the transmission of lithium ions, and the flexible polymer chains effectively buffer the volume changes of the positive and negative electrode materials during the charging and discharging process, and release the reaction stress. On the positive electrode side, the prepared polymer protective layer can effectively prevent the positive electrode sheet from cracking, ensuring the structural stability of the positive electrode during the cycle; on the negative electrode side, the prepared polymer protective layer can effectively inhibit the growth of lithium dendrites, promote the uniform deposition of lithium ions, protect lithium metal from side reactions with the electrolyte, and effectively improve the cycle stability and safety performance of lithium metal batteries.

[0089] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0090] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material, characterized in that: The following steps are involved: The cyclic metal oxygen cluster and vinyl ether are dissolved in a solvent to undergo a displacement reaction, and then a precipitant is added to separate the reaction product after the displacement, wherein the cyclic metal oxygen cluster has sixteen monodentate-connected ethylene glycol unstable sites; The vinyl ether is 4-hydroxybutyl vinyl ether or triethylene glycol divinyl ether; Adding a solvent, a polyethylene glycol derivative and an initiator to the reaction product, the polyethylene glycol derivative and the active functional groups on the metal oxygen cluster undergo free radical polymerization in the solvent to form a polymer with a cross-linked structure, and stirring to obtain a precursor polymer solution; The polyethylene glycol derivative is polyethylene glycol diacrylate or polyethylene glycol dimethacrylate; Adding lithium salt to the precursor polymer solution, heating and stirring to obtain a metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material; The type of the cyclic metal oxide cluster is one of a cyclic titanium oxide cluster, a cyclic zirconium oxide cluster, a cyclic aluminum oxide cluster, and a cyclic magnesium oxide cluster. When the replacement reaction occurs, the mass fraction of the cyclic metal oxide cluster in the solvent is 1-20%.

2. The method for preparing the metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material according to claim 1, characterized in that: The mass ratio of vinyl ether to cyclic metal oxide clusters is 5~50:

1.

3. The method for preparing the metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material according to claim 1, characterized in that: The mass ratio of the polyethylene glycol derivative to the cyclic metal oxide cluster is 10~100:

1.

4. The method for preparing the metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material according to claim 1, characterized in that: The lithium salt is one or a mixed salt of lithium perchlorate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium nitrate, wherein the mass of the lithium salt accounts for 5% to 30% of the total mass of the precursor polymer solution.

5. The method for preparing the metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material according to claim 1, characterized in that: The solvent in which the replacement reaction occurs is the same type of solvent as the solvent added to the reactant, the solvent is one of dimethyl carbonate, dichloropropane, dimethyl sulfoxide, N,N-dimethylacetamide, dichloromethane, and chloroform, the precipitant is one of N-methylpyrrolidone, acetone, and tetrahydrofuran, and the volume ratio of the solvent used in the replacement reaction to the precipitant is 1:5~20.

6. The method for preparing the metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material according to claim 1, characterized in that: The initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, diisotoluene peroxide, and benzoyl peroxide, wherein the mass of the initiator is 0.2% to 2% of the mass of the polyethylene glycol derivative, and the heating temperature is 40 to 100°C.

7. A metal oxide cluster in-situ cross-linked polymer solid electrolyte interface protection layer material prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material according to claim 7 in a high voltage lithium metal battery, characterized in that: The application method is: coating the metal oxygen cluster in-situ cross-linked polymer solid electrolyte interface protection layer material on the surface of the ternary positive electrode and the surface of the negative electrode, and heating and drying.

9. The use according to claim 8, characterized in that: The ternary positive electrode is a high-nickel ternary positive electrode, the negative electrode is a lithium metal negative electrode, the heating and drying temperature is 40~100℃, and the heating and drying time is 2~24 h.

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