Preparation method of a high-safety composite lithium metal anode and anode interface-derived solid-state battery

Abstract

The present invention discloses a method for preparing a high-safety composite lithium metal negative electrode and a negative electrode interface-derived solid-state battery. The high-safety composite lithium metal negative electrode is composed of lithium metal, metal X and a polymer substrate film. The polymer substrate film is a polymer film modified with polar functional groups. There is a strong interaction between the polar functional groups and the metal layer X, which acts as a molecular welding agent to anchor the metal layer. The lithium metal and the metal layer X spontaneously form an alloy layer, thereby obtaining a chemically connected multilayer composite lithium metal negative electrode, which helps to improve the problem of mechanical pulverization of lithium metal during long-term cycling. The present invention proposes an innovative solid-state battery preparation strategy. Through the catalytic action of the alloy compound, the formation of a solid electrolyte is directly promoted on the negative electrode side, thereby achieving a close combination of the negative electrode and the solid electrolyte interface. By optimizing material selection and preparation process, the present invention can further improve the performance of solid-state batteries and meet the growing demand for energy storage.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials and relates to a method for preparing a lithium metal anode and a solid-state battery, and specifically relates to a method for preparing a stable lithium metal anode with continuous ion / electron transmission and a high-safety solid-state battery. Background Art

[0002] As the global demand for efficient energy storage systems continues to rise, the research and development of rechargeable battery technology should focus on improving energy density and ensuring safety. Lithium metal anode has excellent specific capacity (3861mAh g -1 ) and extremely low electrochemical potential (-3.041V vs. standard hydrogen electrode), it is considered to be an ideal choice for the next generation of battery negative electrode materials, which can meet the needs of future batteries in terms of energy density, cycle life and cost-effectiveness. However, the lithium metal negative electrode faces the problem of volume expansion and contraction during the deposition and stripping of lithium ions, which may lead to mechanical pulverization of the electrode material. During the deposition and stripping process of lithium, the formation of lithium dendrites not only accelerates the decomposition of the electrolyte, but also may cause poor contact between lithium metal filaments, resulting in cracks or gaps. In addition, the moss-like growth of lithium dendrites increases its surface area, thereby exacerbating the reactivity with oxygen and causing serious safety risks.

[0003] To address this issue, many recent design strategies, such as regulating the artificial construction of solid electrolyte interface membranes, optimizing electrolyte formulations, developing solid electrolytes, and designing three-dimensional current collectors, can inhibit the growth of lithium dendrites and improve the electrochemical performance of lithium metal batteries to a certain extent. However, it is difficult to simultaneously achieve excellent (electro)chemical stability, mechanical stability, and uniform and rapid ion transport, and there is still a certain gap from practical application. Therefore, the design of efficient and stable composite lithium metal electrodes is of great significance for improving the cycle performance and safety performance of lithium metal batteries. Summary of the Invention

[0004] To address the safety issues caused by uneven lithium deposition and lithium metal pulverization during the cycling of lithium metal negative electrodes, the present invention provides a method for preparing a high-safety composite lithium metal negative electrode and a negative electrode interface-derived solid-state battery. The high-safety composite lithium metal negative electrode prepared by the present invention is composed of lithium metal, metal X, and a polymer substrate membrane. The polymer substrate membrane is a polymer membrane modified with polar functional groups. There is a strong interaction between the polar functional groups and the metal layer X, which acts as a molecular welding agent to anchor the metal layer. The lithium metal and the metal layer X spontaneously form an alloy layer, thereby obtaining a chemically connected multilayer composite lithium metal negative electrode, which helps to improve the problem of mechanical pulverization of lithium metal during long-term cycling. The present invention proposes an innovative solid-state battery preparation strategy, which involves an integrated manufacturing method for in-situ growth of a solid electrolyte using a composite lithium metal negative electrode. Through the catalytic action of the alloy compound, the formation of the solid electrolyte is directly promoted on the negative electrode side, thereby achieving a close bond between the negative electrode and the solid electrolyte interface. This integrated preparation process not only significantly reduces the interfacial resistance between the electrode and the electrolyte, but also ensures the continuity of ion transfer, regulates the uniformity of lithium ion deposition, and inhibits the formation of lithium dendrites, which is crucial for improving the cycle stability and safety of solid-state batteries. In addition, the present invention also demonstrates its application potential in extreme environments, providing a new direction for the development of high-performance energy storage devices in the future. By optimizing material selection and preparation processes, the present invention can further improve the performance of solid-state batteries and meet the growing demand for energy storage.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a high-safety composite lithium metal anode, the high-safety composite lithium metal anode comprising a lithium metal layer, a metal X layer, and a polymer substrate film, wherein: the lithium metal layer and the metal X layer spontaneously form an alloy layer, and the metal X layer and the polymer substrate film are connected via polar functional groups. The specific preparation steps are as follows:

[0007] Step 1: Preparation of functional group-modified polymer substrate membrane

[0008] Step 11: Specialize the functional groups on the surface of the polymer substrate membrane using a chemical reaction method: add 1-2g of an amide monomer to a mixed solution of 2-4ml of an organic acid and 15-20ml of an inorganic acid, then add the mixed solution to 100-120ml of deionized water, and transfer the mixture to a round-bottom flask equipped with a magnetic stirring bar. Stir vigorously at 10-15°C for 3-8h to form a mixed transparent solution. The purpose of this step is to form a soluble aniline salt by combining the protonated nitrogen-containing functional groups with the deprotonated organic acid, wherein:

[0009] The amide monomer is one of aniline, acrylamide, and N-hydroxyethyl acrylamide;

[0010] The organic acid is one of phytic acid, humic acid, malic acid and citric acid;

[0011] The inorganic acid solution is hydrochloric acid or sulfuric acid, and its mass fraction is 30-38wt.%;

[0012] Step 1 and 2: Add an initiator to the above-mentioned mixed transparent solution to obtain a preliminary polymerization reaction precursor, and immediately evenly coat the preliminary polymerization precursor on the polymer base film. Further initiate the reaction at a temperature of 40 to 70°C to obtain a polymer base film with a surface modified with polar functional groups. The purpose of this step is to improve the mechanical strength of the polymer base film through further polymerization reaction, wherein:

[0013] The initiator is one of ammonium persulfate, potassium persulfate, etc., and its addition amount is 0.2-1% of the mass of the amide monomer;

[0014] The polymer substrate film is one or more combinations of polyvinylidene fluoride (PVDF), polyamideimide (PAI), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyimide (PI), and polystyrene (PS);

[0015] Step 13: Place the polymer base film with a surface modified with polar functional groups obtained in step 12 in a vacuum oven and dry it to obtain a functional group-modified polymer base film, wherein:

[0016] The drying temperature is 100-110°C and the drying time is 12-20 hours;

[0017] The thickness of the functional group modified polymer base film is 5 to 80 μm;

[0018] Step 2: Preparation of Metal X Layer

[0019] A metal X layer is deposited on the functional group-modified polymer substrate obtained in step 1, thereby obtaining a polymer substrate to which the metal X layer is attached. The metal X layer and the organic acid polar functional groups have a strong interaction (metal X…O), which is beneficial to increasing the bonding strength between the alloy layer and the substrate, thereby ensuring stability and continuity during the electrode cycle process and preventing safety issues caused by pulverization during long-term cycling.

[0020] The metal X is a metal that can react with metallic lithium to form an alloy, specifically one of silver, aluminum, gallium, zinc, germanium, tin, etc.;

[0021] The method of depositing the metal X layer is vacuum evaporation, gas sublimation, physical vapor deposition, solution reaction, plasma etching, liquid metal filling, etc.

[0022] The thickness of the metal X layer is 0.5 to 4 μm;

[0023] Step 3: Preparation of multilayer composite lithium metal anode

[0024] A composite of metallic lithium and a polymer-metal X layer is prepared by a composite method. The metallic lithium spontaneously reacts with the metal X layer in step 2 to form an alloy layer, thereby obtaining a multilayer composite lithium metal negative electrode, wherein:

[0025] The composite method is one of a chemical mechanical method, an electrodeposition method, a mechanical rolling method, an evaporation method, a chemical reaction method, etc.;

[0026] The thickness of the multi-layer composite lithium metal negative electrode is 10 to 50 μm.

[0027] A method for preparing a negative electrode interface-derived solid-state battery comprises the following steps:

[0028] Step 1: Mix a certain amount of electrolyte No. 1 solvent and electrolyte No. 2 solvent, immediately add the additive to the mixed solvent, then add a certain amount of lithium salt, and stir at room temperature for 2 to 6 hours to prepare an electrolyte mixed solution, wherein:

[0029] The electrolyte solvent No. 1 is one of 1,3-dioxolane (DOL), tetrahydrofuran (THF), dimethyltetrahydrofuran (MeTHF), fluoroethylene carbonate (FEC), ethylene carbonate (EC), and propylene carbonate (PC);

[0030] The electrolyte No. 2 solvent is a mixture of ethylene glycol dimethyl ether (DME), ethylene glycol dibutyl ether (EGDE), n-butyl methyl ether (MNBE), diethyl carbonate (DEC), and dimethyl carbonate (DMC);

[0031] The volume ratio of the electrolyte No. 1 solvent to the electrolyte No. 2 solvent is 2-8:8-2;

[0032] The additive is one of lithium nitrate, lithium bis(trimethylsilyl)amide, hexamethyldisilazane, trimethylsilyl isocyanate, and thiocyanic acid, and the amount added is 0.1 to 1 wt.% of the mass of the electrolyte mixed solution;

[0033] The lithium salt is one or more of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalatoborate) (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium hexafluoroarsenate (LiAsF6), and the concentration of the lithium salt is 0.6 to 3M.

[0034] Step 2: In a glove box, take the multilayer composite lithium metal obtained in the above step 3 as the negative electrode, drip 10-25 μL of the electrolyte mixed solution prepared in step 1 on the side containing the alloy layer, use the commercial active material as the positive electrode, and then place it at a temperature of 30-60°C for 4-10 hours to obtain a solid-state battery. The purpose of this step is to initiate the polymerization reaction of the electrolyte solution through the Lewis acidity of the alloy to obtain a solid electrolyte derived from the negative electrode alloy interface and realize the integrated preparation of the negative electrode and the electrolyte, wherein:

[0035] The positive electrode is lithium cobalt oxide, lithium-rich manganese-based, lithium nickel cobalt manganese oxide (such as LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.83 Co 0.05 Mn 0.12 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2) and so on.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. The composite lithium metal anode prepared by this invention creatively utilizes polar functional groups in organic acids as molecular welding agents between the alloy layer and the polymer substrate membrane, ensuring high continuity of the electrode during cycling. This plays a key role in mitigating lithium metal pulverization and effectively preventing the resulting safety risks, which is crucial for the practical application of high-capacity anode materials. Furthermore, the anti-corrosion properties of the organic acid solution significantly improve the compatibility between the electrode and electrolyte interface, thereby enhancing the long-term cycling stability of the battery.

[0038] 2. The polymer base film introduced in the present invention has high thermal stability and flame retardant properties, can effectively block heat transfer under extreme conditions such as thermal runaway of the battery cell, shows better cycle stability and thermal safety under practical test conditions, prevents the occurrence of thermal runaway, and can reduce the weight of the battery to a certain extent and improve the battery energy density.

[0039] 3. The preparation method of the interface-derived electrolyte introduced in this invention can be extended to other alkali metal batteries, greatly improving the interfacial compatibility of solid-state batteries and enhancing interfacial charge transfer kinetics, which is conducive to promoting the operation of solid-state batteries at low temperatures. More importantly, the interfacial alloy component reacts to dissolve contacting dendrites, effectively preventing further growth and preventing complete battery failure.

[0040] 4. The present invention is applicable to large-scale production and provides a feasible approach for the large-scale application of high-safety lithium metal batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the preparation process of composite lithium metal anode;

[0042] Figure 2 This is the SEM of the composite lithium metal negative electrode prepared in Example 1;

[0043] Figure 3 Impedance test of lithium symmetrical batteries assembled for Example 1 and Comparative Example 1;

[0044] Figure 4 Long cycle test of lithium symmetric batteries assembled for Example 1 and Comparative Example 1;

[0045] Figure 5 Schematic diagram of the solid-state battery structure;

[0046] Figure 6 Long cycle test of the full batteries assembled for Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described below with reference to the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for preparing a high-safety composite lithium metal negative electrode, such as Figure 1 As shown, the method includes the following steps:

[0050] Step 1: Preparation of functional group-modified polymer substrate membrane

[0051] Step 11: Utilize a chemical reaction method to perform specialized functional group treatment on the polymer substrate membrane surface: 1g of aniline is added to a mixed solution of 3ml of phytic acid and 16ml of hydrochloric acid, which is then added to 100ml of deionized water. The mixture is then transferred to a round-bottom flask equipped with a magnetic stir bar and vigorously stirred at 10°C for 4 hours to form a mixed transparent solution. The purpose of this step is to form a soluble aniline salt by combining the protonated nitrogen-containing functional groups with the deprotonated organic acid. The mass fraction of the hydrochloric acid is 30wt%.

[0052] Steps 1 and 2: Add ammonium persulfate (0.2% by weight of the aniline monomer) as an initiator to the above-mentioned mixed transparent solution to obtain a preliminary polymer precursor. This is then evenly coated on a polyamide-imide (PAI) substrate film and further initiated at 70°C for polymerization. Further cross-linking of the macromolecular polymer chains yields a polymer substrate film with high mechanical strength and modified with polar functional groups. The polymer substrate film is then dried in a vacuum oven at 100°C for 15 hours to a thickness of 20 μm.

[0053] Step 2: Preparation of metal germanium layer

[0054] By using vacuum evaporation method to deposit metal germanium on the surface of polymer substrate film: at 5.8×10 -3 Under a vacuum state of 1.5 Pa, metallic germanium particles with a purity of 99.9% are placed in a crucible, heated to melt, and continuously heated until vaporized. The functional group-modified polymer substrate film obtained in step 1 is placed in this vacuum state. The vaporized metal particles are rapidly deposited onto the polymer substrate film in a linear motion with essentially no collision. After repeated vacuum coating, a metallic germanium layer with a thickness of 2.5 μm is formed on the surface of the polymer substrate film. Due to the chelation effect between the polar functional groups in phytic acid and the metal (metal X…O), the metallic germanium layer and the polymer film generate a strong interaction force, increasing the bonding strength between the metal layer and the substrate film, thereby ensuring stability and continuity during the electrode cycle and preventing safety issues caused by pulverization during long-term cycling.

[0055] Step 3: Preparation of multilayer composite lithium metal anode

[0056] A simple and easy rolling method was used to prepare a composite of metallic lithium and polymer-metal germanium. The rolled metallic lithium formed an alloy layer with metallic germanium through a spontaneous alloying reaction, thereby preparing a multi-layer composite lithium metal negative electrode. The SEM image of the composite is shown in FIG. Figure 2 As shown. The thickness of the lithium metal negative electrode is 20 μm. The composite lithium metal negative electrode prepared in this embodiment has a low interface impedance. Its impedance at different temperatures is shown as follows: Figure 3 Assemble it into a symmetrical battery and test the long cycle stability performance as shown in Figure 4 shown.

[0057] This embodiment also provides a method for preparing an interface-derived solid-state battery, wherein the solid-state battery comprises a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode comprises the above-mentioned negative electrode material, and the electrolyte is prepared by deriving the negative electrode material. The specific steps are as follows:

[0058] Step 1: In a glove box, take 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME) solvents, mix them in a volume ratio of 7:3, immediately add 0.2% of the electrolyte mass of the additive bis(trimethylsilyl)amide lithium, then add a certain amount of lithium salt LiFSI, and stir at room temperature for 3 hours to form an electrolyte mixed solution with a concentration of 1.4M.

[0059] Step 2: In a glove box, take the multilayer composite lithium metal obtained in step 3 above as the negative electrode, drip 15 μL of the electrolyte mixed solution prepared in step 1 on the side containing the alloy layer, and use commercial active material lithium cobalt oxide as the positive electrode package. Then, place it at a temperature of 50°C and react for 4 hours to obtain a solid-state battery. Its structural diagram is shown below. Figure 5 The purpose of this step is to initiate the polymerization reaction of the electrolyte solution through the Lewis acidity of the alloy, obtain a solid electrolyte derived from the negative electrode alloy interface, and realize the integrated preparation of the negative electrode and electrolyte, further improving the interface compatibility problem of the solid-state battery. Figure 6 The excellent long-cycle stability shown proves that the solid-state battery assembled with the multilayer composite lithium metal negative electrode prepared in this embodiment is superior to the conventional lithium metal negative electrode.

[0060] Example 2:

[0061] This embodiment provides a method for preparing a high-safety composite lithium metal negative electrode, such as Figure 1 As shown, the method includes the following steps:

[0062] Step 1: Preparation of functional group-modified negative electrode base membrane

[0063] Step 11: Utilize a chemical reaction method to perform specialized functional group treatment on the polymer substrate surface: 1g of N-hydroxyethyl acrylamide is added to a mixture of 4ml of phytic acid and 20ml of hydrochloric acid. This mixture is then added to 100ml of deionized water. The mixture is then transferred to a round-bottom flask equipped with a magnetic stir bar and vigorously stirred at 15°C for 7 hours to form a mixed, transparent solution. The hydrochloric acid concentration is 30 wt.%.

[0064] Steps 1 and 2: Add ammonium persulfate (0.2% by weight of the N-hydroxyethyl acrylamide monomer) as an initiator to the aforementioned mixed transparent solution to obtain a preliminary polymer precursor. This precursor is then evenly coated onto a polyamideimide (PAI) substrate film. Polymerization is further initiated at 70°C, and the macromolecular polymer chains undergo further crosslinking to produce a polymer substrate film with high mechanical strength and surface modifications containing polar functional groups. The polymer substrate film is then dried in a vacuum oven at 100°C for 10 hours, resulting in a polymer substrate film with a thickness of 12 μm.

[0065] Step 2: Preparation of a metal aluminum layer attached to the surface of the basement membrane

[0066] The polymer substrate membrane was placed in 99.99% pure gaseous aluminum chloride at a concentration of 3.5 g L -1 A metal aluminum layer with a thickness of 2 μm is formed on the surface of the polymer base film at a temperature of 178°C. The amount of the deposited metal aluminum layer can be controlled by controlling the exposure time. After cooling, the polymer base film with the metal aluminum layer attached can be obtained.

[0067] Step 3: Preparation of multilayer composite lithium metal anode

[0068] A composite of metallic lithium and polymer-metal aluminum was prepared using a simple roll-pressing method. The rolled metallic lithium spontaneously alloyed with the aluminum to form an alloy layer, resulting in a multilayer composite lithium metal anode with a thickness of 25 μm.

[0069] This embodiment also provides a method for preparing an interface-derived solid-state battery, wherein the solid-state battery comprises a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode comprises the above-mentioned negative electrode material, and the electrolyte is prepared by deriving the negative electrode material. The specific steps are as follows:

[0070] Step 1: Take 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME) solvents, mix them in a volume ratio of 7:3, immediately add 0.2% of the electrolyte mass of trimethylsilyl isocyanate additive, then add a certain amount of lithium salt LiFSI, stir at room temperature for 3 hours to form an electrolyte mixed solution with a concentration of 1.4M.

[0071] Step 2: In a glove box, take the multilayer composite lithium metal obtained in the above step 3 as the negative electrode, drip 10μL of the electrolyte mixed solution prepared in step 1 on the side containing the alloy layer, and use commercial active material lithium cobalt oxide as the positive electrode package. Then place it at a temperature of 50°C and react for 4 hours to obtain a solid-state battery.

[0072] Example 3:

[0073] The difference between this embodiment and embodiment 1 is that the polymer base film selected is polyimide (PI).

[0074] Example 4:

[0075] The difference between this embodiment and embodiment 1 is that the specific steps of the interface-derived solid-state battery are as follows:

[0076] Step 1: Take ethylene carbonate (EC) and dimethyl carbonate (DMC) solvents, mix them in a volume ratio of 5:2, and then introduce a certain amount of lithium salt LiFSI to form an electrolyte mixed solution with a concentration of 2M.

[0077] Step 2: In a glove box, take a multilayer composite lithium metal as the negative electrode, drop 10 μL of the electrolyte mixed solution prepared in step 1 on the side containing the alloy layer, and use commercial active material lithium nickel cobalt manganese oxide (such as LiNi 0.8 Co 0.1 Mn 0.1 O2) as the positive electrode to assemble a battery, which is then placed at a temperature of 50°C for 4 hours to obtain a solid-state battery.

[0078] Example 5:

[0079] The difference between this embodiment and embodiment 1 is that the composite method of the lithium metal negative electrode in step 3 is an electrochemical deposition method.

[0080] Comparative Example 1:

[0081] The difference between this comparative example and Example 1 is that the negative electrode material selected is a lithium copper composite strip with a thickness of 50 μm. The test results are as follows: Figure 3 、 Figure 4 and Figure 6 shown.

[0082] Comparative Example 2:

[0083] The difference between this comparative example and Example 1 is that there is no step of preparing the integrated negative electrode of the interface-derived electrolyte, and the conventional polymer solid electrolyte is directly used to assemble the battery.

Claims

1. A method for preparing a high-safety composite lithium metal negative electrode, characterized in that The method comprises the following steps: Step 1: Preparation of functional group-modified polymer substrate membrane Step 1: Specialize the functional groups on the surface of the polymer substrate membrane using a chemical reaction method: add 1-2 g of an amide monomer to a mixed solution of 2-4 ml of an organic acid and 15-20 ml of an inorganic acid. Then, add the mixed solution to 100-120 ml of deionized water. Transfer the mixture to a round-bottom flask equipped with a magnetic stirring bar and vigorously stir at 10-15°C for 3-8 hours to form a mixed transparent solution. Step 12: Add an initiator to the above-mentioned mixed transparent solution to obtain a preliminary polymerization reaction precursor, and immediately and evenly coat the preliminary polymerization precursor on the polymer substrate film, and further initiate the reaction at a temperature of 40-70°C to obtain a polymer substrate film with a surface modified with polar functional groups; Step 13: drying the polymer base film with a surface modified with polar functional groups obtained in step 12 in a vacuum oven to obtain a functional group-modified polymer base film; Step 2: Preparation of Metal X Layer Depositing a metal X layer on the functional group-modified polymer substrate film obtained in step 1, thereby obtaining a polymer substrate film with the metal X layer attached, wherein: the metal X is a metal that can react with metallic lithium to form an alloy; Step 3: Preparation of multilayer composite lithium metal anode A composite of metallic lithium and polymer-metal X layer is prepared by a composite method. The metallic lithium spontaneously chemically reacts with the metal X layer in step 2 to form an alloy layer, thereby obtaining a multilayer composite lithium metal negative electrode.

2. The method for preparing a high-safety composite lithium metal negative electrode according to claim 1, characterized in that In the step 11, the amide monomer is one of aniline, acrylamide, and N-hydroxyethyl acrylamide; the organic acid is one of phytic acid, humic acid, malic acid, and citric acid; and the inorganic acid mixed solution is hydrochloric acid or sulfuric acid, with a mass fraction of 30-38 wt.%.

3. The method for preparing a high-safety composite lithium metal negative electrode according to claim 1, characterized in that In steps one and two, the initiator is one of ammonium persulfate and potassium persulfate, and the added amount is 0.2-1% of the mass of the amide monomer; the polymer base film is one or more combinations of polyvinylidene fluoride, polyamideimide, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyimide, and polystyrene.

4. The method for preparing a high-safety composite lithium metal negative electrode according to claim 1, characterized in that In steps 1 and 3, the drying temperature is 100-110° C. and the drying time is 12-20 h; the thickness of the functional group-modified polymer substrate film is 5-80 μm.

5. The method for preparing a high-safety composite lithium metal negative electrode according to claim 1, characterized in that In step 2, the metal X is one of silver, aluminum, gallium, zinc, germanium, and tin; the method for depositing the metal X layer is one of vacuum evaporation, gas sublimation, physical vapor deposition, solution reaction, plasma etching, and liquid metal filling; and the thickness of the metal X layer is 0.5 to 4 μm.

6. The method for preparing a high-safety composite lithium metal negative electrode according to claim 1, characterized in that In the step three, the composite method is one of a chemical mechanical method, an electrodeposition method, a mechanical rolling method, an evaporation method, and a chemical reaction method; and the thickness of the multilayer composite lithium metal negative electrode is 10 to 50 μm.

7. A high-safety composite lithium metal anode prepared by the method according to any one of claims 1 to 6.

8. A method for preparing a negative electrode interface-derived solid-state battery, characterized in that The method comprises the following steps: Step 1: Mix a certain amount of electrolyte No. 1 solvent and electrolyte No. 2 solvent, immediately add the additive to the mixed solvent, then add a certain amount of lithium salt, and stir at room temperature for 2 to 6 hours to prepare an electrolyte mixed solution, wherein: the volume ratio of electrolyte No. 1 solvent to electrolyte No. 2 solvent is 2 to 8:8 to 2, and the lithium salt concentration is 0.6 to 3 M; Step 2: In a glove box, take the multilayer composite lithium metal prepared by the method according to any one of claims 1 to 6 as the negative electrode, drip 10 to 25 μL of the electrolyte mixed solution prepared in step 1 on the side containing the alloy layer, use the commercial active material as the positive electrode, and then place it at a temperature of 30 to 60 ° C for 4 to 10 hours to obtain a solid-state battery.

9. The method for preparing a negative electrode interface-derived solid-state battery according to claim 8, characterized in that In the step 1, the electrolyte solvent No. 1 is one of 1,3-dioxolane, tetrahydrofuran, dimethyltetrahydrofuran, fluoroethylene carbonate, ethylene carbonate, and propylene carbonate; the electrolyte solvent No. 2 is a mixture of ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, n-butyl methyl ether, diethyl carbonate, and dimethyl carbonate; the additive is one of lithium nitrate, lithium bis(trimethylsilyl)amide, hexamethyldisilazane, trimethylsilyl isocyanate, and thiocyanic acid, and the addition amount is 0.1-1 wt.% of the mass of the electrolyte mixed solution; and the lithium salt is one or more combinations of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, bis(fluorosulfonyl)imide lithium salt, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium bis(trifluoromethanesulfonyl)imide, and lithium hexafluoroarsenate.

10. The method for preparing a negative electrode interface-derived solid-state battery according to claim 8, characterized in that In step 2, the positive electrode is one of lithium cobalt oxide, lithium-rich manganese oxide, and lithium nickel cobalt manganese oxide.

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