A method for preparing a lithium metal battery based on in-situ solidification

Abstract

The application relates to a preparation method of a lithium metal battery based on in-situ solidification, and belongs to the field of solid-state lithium metal battery preparation. The application adopts a strategy of constructing a double-interface layer with a self-repairing function on the interface between an in-situ solid-state electrolyte and lithium metal through the synergistic effect of double Lewis acids, a first protective layer is first grown on the surface of lithium metal by dropping a solution containing a first Lewis acid, an A-SEI film containing LiCl or LiBr or LiI is in-situ grown, side reactions of lithium metal and the in-situ solid-state electrolyte are inhibited, a second Lewis acid is added in the in-situ solid-state electrolyte solidification liquid, raw materials for constructing a lithium-containing alloy with high lithium ion diffusion and a high-modulus interface layer rich in LiF are continuously provided, defects of the double-interface layer are self-repaired, and a second protective layer is constructed. The application solves the problem of extremely unstable interface of the in-situ solid-state lithium metal battery, compatible high-performance in-situ solid-state electrolyte is prepared, and a lithium metal battery with high energy density, high coulomb efficiency and super-long cycle life is obtained.

Description

Technical Field

[0001] This invention belongs to the field of solid-state lithium metal battery preparation, specifically relating to a method for preparing lithium metal batteries based on in-situ solidification, which uses the synergistic effect of two Lewis acids to construct a self-healing dual interface layer at the interface between the solid electrolyte and the lithium metal. Background Technology

[0002] With the gradual depletion of fossil fuels and the increasingly serious environmental problems such as the greenhouse effect, the development of efficient and environmentally friendly new energy sources is particularly important. The demand for new energy storage has spurred the development of energy storage systems, among which lithium-ion battery energy storage systems have received widespread research and application due to their excellent cycle performance. Traditional liquid electrolyte lithium-ion batteries are limited in application due to serious safety issues, while solid-state electrolytes effectively solve the leakage and flammability problems of traditional electrolytes. Therefore, developing high-energy-density, ultra-long-cycle-performance solid-state electrolyte batteries will become a key future development direction for lithium-ion batteries, and further exploring high-capacity, lightweight or small-volume, and stable solid-state battery systems is crucial.

[0003] Solid-state battery systems mainly consist of a positive electrode, a solid electrolyte, and a negative electrode. A positive electrode material with a high theoretical specific capacity, when paired with a negative electrode material of similar high theoretical specific capacity, will result in higher energy density for battery systems (such as lithium-sulfur batteries and lithium-air batteries). Lithium metal, with its high theoretical specific capacity, ultra-low electrochemical potential, and low density, is an excellent negative electrode material. Solid electrolytes are further divided into inorganic solid electrolytes and polymer electrolytes. While inorganic solid electrolytes exhibit high ionic conductivity and strong cycle life, their large-scale industrialization is limited by their brittleness, difficulty in large-scale production, and poor compatibility with the electrode interface. Polymer electrolytes are divided into in-situ polymer electrolytes and ex-situ solid polymer electrolytes. In-situ polymer electrolytes offer better interfacial compatibility with the electrode, and their simpler preparation process and environmentally friendly production flow make them more promising for commercial applications.

[0004] In-situ solid polymer electrolytes (SPEs) offer high energy density in lithium metal batteries and are a key technology for next-generation lithium batteries. However, the reactive nature of lithium metal and the instability of SPEs lead to instability at the lithium metal-electrolyte interface. The native solid electrolyte interphase (SEI) layer is porous and has low viscosity, making it prone to detachment, loss of activity, and the formation of dead lithium. Simultaneously, newly exposed lithium metal continuously reacts with the SPE, causing a continuous increase in interfacial impedance in the solid lithium metal battery system, prominent lithium dendrite growth, low coulombic efficiency, and short cycle life. Summary of the Invention

[0005] The purpose of this invention is to address the problems of poor solid electrolyte performance and poor electrode-electrolyte interface stability in existing in-situ solid polymer lithium metal batteries mentioned in the background art, and to propose a method for preparing lithium metal batteries based on in-situ curing. This invention employs a strategy of constructing a self-healing dual-interface layer at the interface between the in-situ solid electrolyte and lithium metal using the synergistic effect of two Lewis acids. First, a solid electrolyte interface (A-SEI) is grown in-situ as a first protective layer by dropping a solution containing a first Lewis acid onto the lithium metal surface. Then, a second Lewis acid is added to the in-situ solid electrolyte curing solution to form a second protective layer on the lithium metal surface. Simultaneously, the Lewis acid inorganic additive promotes lithium salt dissociation and provides self-healing for the SEI film on the lithium metal surface, effectively improving the cycle life of the in-situ solid lithium metal battery.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a lithium metal battery based on in-situ solidification includes the following steps:

[0008] Step 1: Pre-treat the surface of the lithium metal anode and grow an A-SEI film in situ;

[0009] 1.1 The first Lewis acid is added to dimethyl sulfoxide and stirred for 2 hours to mix evenly, to obtain mixture A; wherein the content of the first Lewis acid in dimethyl sulfoxide is 0.1-0.5 wt.%.

[0010] 1.2 Add the mixture A obtained in step 1.1 dropwise to the surface of the lithium metal anode, at a rate of 1 cm. 2 Add 20-50 μL of mixed solution A to the lithium metal anode, tilt the lithium metal anode so that it is completely covered by mixed solution A, and keep it for 5-10 seconds;

[0011] 1.3 Clean the lithium metal anode treated in step 1.2 with tetrahydrofuran to remove residual mixture A;

[0012] 1.4 Dry the lithium metal anode treated in step 1.3 in an argon-filled glove box for 1–3 days;

[0013] Step 2: Preparation of the in-situ solidification precursor solution for solid electrolyte;

[0014] 2.1 Mix 10-20 parts by weight of monomer and 2-8 parts by weight of multifunctional crosslinking agent, stir for 10 minutes to mix evenly, and obtain mixture B;

[0015] 2.2 Add 1 to 5 parts by mass of lithium salt to mixture B, stir for 30 min to mix evenly, and store the resulting mixture C at 2 to 8℃.

[0016] 2.3 Add 1.56–3.96 parts by mass of the second Lewis acid to mixture C, and stir for 1–3 hours to obtain mixture D;

[0017] 2.4 Add 0.02 to 0.14 parts by weight of initiator and 62.90 to 85.24 parts by weight of plasticizer to mixture D, stir for 30 min to obtain the in-situ solidification precursor solution of solid electrolyte;

[0018] Step 3: After sequentially stacking the positive electrode sheet, the porous framework film, and the lithium metal negative electrode treated in Step 1, encapsulate them with an aluminum-plastic film to obtain a battery cell with a porous framework film; then inject the in-situ curing precursor solution prepared in Step 2 into the battery cell with the porous framework film, every 1 cm 2 Add 20–50 μL to the solution and solidify in situ at 45–80 °C for 0.5–8 h to form a solid electrolyte, thus completing the preparation of a lithium metal battery based on in-situ solidification.

[0019] The first Lewis acid is one of CuCl2, CuI2, FeCl3, AlCl3, AlBr3, and AlI3; the second Lewis acid is one of CuF2, AlF3, and FeF3.

[0020] The monomer is one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, methyl acrylate, ethyl acrylate, ethylene ethylene carbonate, and vinylene carbonate; the multifunctional crosslinking agent is one of pentaerythritol tetraacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate; and the lithium salt is one of LiTFSI, LiFSI, LiClO4, LiPF6, LiDFOB, and LiBOB.

[0021] The plasticizer is a 0.8–4 mol / L lithium salt solution, wherein the solute of the lithium salt solution is one or two of LiTFSI, LiFSI, LiClO4, LiPF6, LiDFOB, and LiBOB, and the solvent is one or more of ethylene carbonate (EC), propylene carbonate (PC), 1,3-dioxolane (DOL), ethylene glycol dimethyl ether (DME), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC); and the initiator is one of azobisisobutyronitrile, azobisisovalerate, and azobisisoheptanenitrile.

[0022] The porous framework membrane is one of the following: lignocellulose membrane, electrospun polyimide membrane, glass fiber membrane, polyethylene diaphragm, polypropylene diaphragm, and electrospun polyvinylidene fluoride membrane, with a thickness of less than 100 μm; the active material of the positive electrode is one of the following: lithium iron phosphate, lithium cobalt oxide, nickel-cobalt-manganese ternary positive electrode, and sulfur positive electrode.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention provides a method for preparing lithium metal batteries based on in-situ solidification. It employs a strategy of constructing a self-healing dual-interface layer at the interface between the in-situ solid electrolyte and lithium metal using the synergistic effect of two Lewis acids. First, a solution containing a first Lewis acid is dropped onto the lithium metal surface to grow an A-SEI film containing LiCl, LiBr, or LiI as a first protective layer, suppressing side reactions between lithium metal and the in-situ solid electrolyte. Then, a second Lewis acid is added to the solidified solution of the in-situ solid electrolyte, continuously providing raw materials for constructing a lithium-containing alloy with high lithium-ion diffusion and a high-modulus LiF-rich interface layer, thus self-healing defects in the dual-interface layer and constructing a second protective layer. This invention solves the problem of extremely unstable interfaces in in-situ solid lithium metal batteries, resulting in a compatible, high-performance in-situ solid electrolyte and a lithium metal battery with high energy density, high coulombic efficiency, and ultra-long cycle life. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the solid electrolyte system in the lithium metal batteries obtained in Example 1 and Comparative Example 1, where M represents Cu, Fe, and Al, and X represents Cl, Br, and I.

[0026] Figure 2 The rate performance of the lithium metal batteries in Example 1 and Comparative Example 1 is shown.

[0027] Figure 3 The lithium metal batteries of Example 1 and Comparative Example 1 demonstrate long charge-discharge cycle performance at 3C rate.

[0028] Figure 4 The lithium metal batteries of Example 4 and Comparative Example 2 are shown to have long charge-discharge cycle performance at 3C rate. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to some comparative examples and embodiments. It should be noted that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0030] Example 1

[0031] A method for preparing a lithium metal battery based on in-situ solidification includes the following steps:

[0032] Step 1: Pre-treat the surface of the lithium metal anode in an argon-filled glove box and grow an A-SEI film in situ.

[0033] 1.1 Add AlI3 to dimethyl sulfoxide and stir for 2 hours to mix evenly to obtain mixture A; wherein, the content of the first Lewis acid in dimethyl sulfoxide is 0.12 wt.%.

[0034] 1.2 Add the mixture A obtained in step 1.1 dropwise to the surface of the lithium metal anode, at a rate of 1 cm. 2 Add 25 μL of mixture A to the lithium metal anode, tilt the lithium metal anode so that it is completely covered by mixture A, and keep it for 10 s;

[0035] 1.3 Clean the lithium metal anode treated in step 1.2 with 10 mL of tetrahydrofuran to remove residual mixture A;

[0036] 1.4 The lithium metal anode processed in step 1.3 was dried in an argon-filled glove box for 2 days for later use;

[0037] Step 2: Preparation of the in-situ solidification precursor solution for solid electrolyte;

[0038] 2.1 In an argon glove box, 20 parts by weight of methyl methacrylate and 5 parts by weight of pentaerythritol tetraacrylate were mixed and stirred for 10 minutes to obtain a homogeneous mixture B.

[0039] 2.2 Add 3 parts by mass of LiFSI to mixture B, stir for 30 min to mix evenly, and store the resulting mixture C at 2-8℃.

[0040] 2.3 Add 1.56 parts by mass of AlF3 to mixture C and stir for 2 hours to obtain mixture D;

[0041] 2.4 Add 0.05 parts by mass of azobisisobutyronitrile initiator and 70.39 parts by mass of plasticizer (1 mol / L lithium salt solution, solute is LiFSI, solvent is a mixture of 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME) in a volume ratio of 1:1) to mixture D, stir for 30 min to obtain a solid electrolyte in-situ curing precursor solution containing Lewis acid additive;

[0042] Step 3: After processing the lithium metal anode and lithium iron phosphate cathode in step 1, nickel and aluminum tabs are welded on respectively. Then, the lithium iron phosphate cathode, electrospun polyimide film and lithium metal anode processed in step 1 are stacked in the order of stacking. The lithium metal anode is then encapsulated with aluminum-plastic film, leaving an injection port to obtain a battery cell with a porous skeleton film.

[0043] Step 4: Inject the in-situ curing precursor solution prepared in Step 2 into the battery cell with the porous framework membrane, at a rate of 1 cm. 2 Add 40 μL, then vacuum, seal, stand for 12 h, and then solidify in situ at 65 °C for 2 h to form a solid electrolyte, thus completing the preparation of a lithium metal battery based on in-situ solidification.

[0044] The lithium metal battery obtained in Example 1 was activated at 0.1C for 3 cycles and then subjected to a long cycle at 3C on a LAND charge-discharge tester, with an average coulombic efficiency of 99.97% and a cycle life of 345 cycles.

[0045] Example 2

[0046] The difference between this embodiment and Example 1 is that the first Lewis acid is changed to AlCl3, while the rest of the steps are exactly the same as in Example 1.

[0047] The lithium metal battery obtained in Example 2 was activated at 0.1C for 3 cycles and then subjected to a long cycle at 3C on a LAND charge-discharge tester, with an average coulombic efficiency of 99.98% and a cycle life of 370 cycles.

[0048] Example 3

[0049] The difference between this embodiment and Embodiment 1 is that the second Lewis acid is changed to CuF2, while the remaining steps are exactly the same as in Embodiment 1.

[0050] The lithium metal battery obtained in Example 3 was first activated at 0.1C for 3 cycles on a LAND charge-discharge tester, followed by a long cycle at 3C, with an average coulombic efficiency of 99.92% and a cycle life of 274 cycles.

[0051] Example 4

[0052] A method for preparing a lithium metal battery based on in-situ solidification includes the following steps:

[0053] Step 1: Pre-treat the surface of the lithium metal anode in an argon-filled glove box and grow an A-SEI film in situ.

[0054] 1.1 FeCl3 was added to dimethyl sulfoxide and stirred for 2 hours to obtain a homogeneous mixture A; wherein, the content of the first Lewis acid in dimethyl sulfoxide was 0.12 wt.%.

[0055] 1.2 Add the mixture A obtained in step 1.1 dropwise to the surface of the lithium metal anode, at a rate of 1 cm. 2 Add 25 μL of mixture A to the lithium metal anode, tilt the lithium metal anode so that it is completely covered by mixture A, and keep it for 10 s;

[0056] 1.3 Clean the lithium metal anode treated in step 1.2 with 10 mL of tetrahydrofuran to remove residual mixture A;

[0057] 1.4 The lithium metal anode processed in step 1.3 was dried in an argon-filled glove box for 2 days for later use;

[0058] Step 2: Preparation of the in-situ solidification precursor solution for solid electrolyte;

[0059] 2.1 In an argon glove box, 20 parts by weight of vinylene carbonate and 5 parts by weight of pentaerythritol tetraacrylate were mixed and stirred for 10 minutes to obtain a homogeneous mixture B.

[0060] 2.2 Add 3 parts by mass of LiTFSI to mixture B, stir for 30 min to mix evenly, and store the resulting mixture C at 2-8℃.

[0061] 2.3 Add 1.56 parts by mass of AlF3 to mixture C and stir for 2 hours to obtain mixture D;

[0062] 2.4 Add 0.05 parts by mass of azobisisobutyronitrile initiator and 70.39 parts by mass of plasticizer (1 mol / L lithium salt solution, solute is LiTFSI, solvent is a mixture of 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME) in a volume ratio of 1:1) to mixture D, stir for 30 min to obtain a solid electrolyte in-situ curing precursor solution containing Lewis acid additive;

[0063] Step 3: After processing the lithium metal anode and lithium iron phosphate cathode in step 1, nickel and aluminum tabs are welded on respectively. Then, the lithium iron phosphate cathode, lignocellulose membrane and lithium metal anode processed in step 1 are stacked in the order of stacking, packaged with aluminum-plastic film, leaving the liquid injection port, to obtain a battery cell with a porous skeleton membrane.

[0064] Step 4: Inject the in-situ curing precursor solution prepared in Step 2 into the battery cell with the porous framework membrane, at a rate of 1 cm. 2 Add 40 μL of the solution, then vacuum the container, seal it, let it stand for 12 hours, and then solidify it in situ at 70°C for 5 hours to form a solid electrolyte, thus completing the preparation of a lithium metal battery based on in-situ solidification.

[0065] The lithium metal battery obtained in Example 4 was first activated at 0.1C for 3 cycles on a LAND charge-discharge tester, followed by a long cycle at 3C, with an average coulombic efficiency of 99.89% and a cycle life of 234 cycles.

[0066] Example 5

[0067] A method for preparing a lithium metal battery based on in-situ solidification includes the following steps:

[0068] Step 1: Pre-treat the surface of the lithium metal anode in an argon-filled glove box and grow an A-SEI film in situ.

[0069] 1.1 Add AlBr3 to dimethyl sulfoxide and stir for 2 hours to mix evenly to obtain mixture A; wherein, the content of the first Lewis acid in dimethyl sulfoxide is 0.4 wt.%;

[0070] 1.2 Add the mixture A obtained in step 1.1 dropwise to the surface of the lithium metal anode, at a rate of 1 cm. 2 Add 25 μL of mixture A to the lithium metal anode, tilt the lithium metal anode so that it is completely covered by mixture A, and keep it for 10 s;

[0071] 1.3 Clean the lithium metal anode treated in step 1.2 with 10 mL of tetrahydrofuran to remove residual mixture A;

[0072] 1.4 The lithium metal anode processed in step 1.3 was dried in an argon-filled glove box for 2 days for later use;

[0073] Step 2: Preparation of the in-situ solidification precursor solution for solid electrolyte;

[0074] 2.1 In an argon glove box, 20 parts by weight of methyl methacrylate and 5 parts by weight of polyethylene glycol diacrylate were mixed and stirred for 10 minutes to obtain a homogeneous mixture B.

[0075] 2.2 Add 3 parts by mass of LiTFSI to mixture B, stir for 30 min to mix evenly, and store the resulting mixture C at 2-8℃.

[0076] 2.3 Add 1.56 parts by mass of FeF3 to mixture C and stir for 2 hours to obtain mixture D;

[0077] 2.4 Add 0.05 parts by mass of azobisisobutyronitrile initiator and 70.39 parts by mass of plasticizer (1 mol / L lithium salt solution, solute is LiTFSI, solvent is a mixture of 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME) in a volume ratio of 1:1) to mixture D, stir for 30 min to obtain a solid electrolyte in-situ curing precursor solution containing Lewis acid additive;

[0078] Step 3: After processing the lithium metal anode and sulfur cathode in Step 1, nickel and aluminum tabs are welded on respectively. Then, the sulfur cathode, electrospun polyimide film and lithium metal anode processed in Step 1 are stacked in the order of stacking, encapsulated with aluminum-plastic film, leaving the liquid injection port to obtain a battery cell with a porous skeleton film.

[0079] Step 4: Inject the in-situ curing precursor solution prepared in Step 2 into the battery cell with the porous framework membrane, at a rate of 1 cm. 2 Add 40 μL of the solution, then vacuum the container, seal it, let it stand for 12 hours, and then solidify it in situ at 70°C for 5 hours to form a solid electrolyte, thus completing the preparation of a lithium metal battery based on in-situ solidification.

[0080] The lithium metal battery obtained in Example 5 was activated at 0.1C for 3 cycles and then subjected to a long cycle at 1C on a LAND charge-discharge tester, achieving a coulombic efficiency of 99.94% and a cycle life of 286 cycles.

[0081] Comparative Example 1

[0082] Comparative Example 1 is set up to illustrate the impact of the dual-interface-layer strategy of the present invention on the optimization of solid-state lithium metal battery systems.

[0083] In Comparative Example 1, during the pretreatment of the lithium metal anode in step 1, no first Lewis acid was added; only dimethyl sulfoxide was used for treatment. In step 2, during the preparation of the curing precursor solution, no second Lewis acid was added. The remaining steps were exactly the same as in Example 1.

[0084] The lithium metal battery obtained in Comparative Example 1 was activated at 0.1C for 3 cycles and then subjected to a long cycle at 3C on a LAND charge-discharge tester. The average coulombic efficiency was 99.06% and the cycle life was 110 cycles.

[0085] Comparative Example 2

[0086] Comparative Example 2 is set up to demonstrate the different effects of the dual-interface-layer strategy on solid-state lithium metal battery systems compared to the single A-SEI strategy.

[0087] In Comparative Example 2, no second Lewis acid was added during step 2 of preparing the curing precursor solution. The remaining steps were exactly the same as in Example 4.

[0088] The lithium metal battery obtained in Comparative Example 2 was activated at 0.1C for 3 cycles and then subjected to a long cycle at 3C on a LAND charge-discharge tester. The average coulombic efficiency was 99.43% and the cycle life was 168 cycles.

[0089] Figure 1 This is a schematic diagram of the solid electrolyte system in the lithium metal battery obtained in Example 1 and Comparative Example 1, showing that the dual interface layer strategy can induce uniform lithium ion deposition, effectively suppress the growth of lithium dendrites, and greatly improve the interface problem between lithium metal and in-situ solid electrolyte. Figure 2 The rate performance of the lithium metal batteries in Example 1 and Comparative Example 1 demonstrates that the dual-interface layer exhibits higher lithium-ion diffusion capability, maintaining a high discharge specific capacity even at high rates. Furthermore, the dual-interface layer strategy significantly improves the cycle life of the in-situ solid-state lithium metal battery. Figure 3 As shown. Figure 4 The long-cycle performance of lithium metal batteries in Example 4 and Comparative Example 2 at 3C rate shows that a single A-SEI interface layer is easily broken and does not have self-repair capability. Meanwhile, the dual interface layer strategy can optimize the electrode-electrolyte interface of lithium metal batteries, thereby improving the energy density and cycle life of lithium metal batteries.

Claims

1. A method for preparing lithium metal batteries based on in-situ solidification, characterized in that, Includes the following steps: Step 1: Pre-treat the surface of the lithium metal anode; 1.1 The first Lewis acid is added to dimethyl sulfoxide and stirred until homogeneous to obtain mixture A; wherein the content of the first Lewis acid in dimethyl sulfoxide is 0.1~0.5 wt.%, and the first Lewis acid is one of CuCl2, CuI2, FeCl3, AlCl3, AlBr3, and AlI3; 1.2 The mixture A obtained in step 1.1 is added dropwise to the surface of the lithium metal anode, at a rate of 1 cm. 2 Add 20-50 μL of mixed solution A to the lithium metal anode and hold for 5-10 seconds; 1.3 Clean the lithium metal anode treated in step 1.2 with tetrahydrofuran and dry it in a glove box; Step 2: Preparation of the in-situ solidification precursor solution for solid electrolyte; 2.1 Mix 10-20 parts by weight of monomer and 2-8 parts by weight of multifunctional crosslinking agent, stir and mix evenly to obtain mixture B; 2.2 Add 1-5 parts by weight of lithium salt to mixture B, stir and mix evenly, and store the resulting mixture C at 2-8℃; 2.3 Add 1.56~3.96 parts by mass of a second Lewis acid to mixture C, stir, and obtain mixture D. The second Lewis acid is one of CuF2, AlF3, and FeF3. 2.4 Add 0.02~0.14 parts by weight of initiator and 62.90~85.24 parts by weight of plasticizer to mixture D, stir, and obtain the in-situ solidification precursor solution of solid electrolyte; Step 3: After sequentially stacking the positive electrode sheet, the porous framework film, and the lithium metal negative electrode treated in Step 1, encapsulate them with an aluminum-plastic film to obtain a battery cell with a porous framework film; then inject the in-situ curing precursor solution prepared in Step 2 into the battery cell with the porous framework film, every 1 cm 2 Add 20~50μL to the solution and solidify in situ at 45~80℃ for 0.5 h~8 h to form a solid electrolyte, thus completing the preparation of lithium metal battery based on in situ solidification; By adding a solution containing a first Lewis acid to the surface of the lithium metal anode, an A-SEI film containing LiCl, LiBr, or LiI is grown in situ as a first protective layer to suppress side reactions between lithium metal and the in-situ solid electrolyte. Then, a second Lewis acid is added to the in-situ solidification precursor solution of the solid electrolyte to continuously provide raw materials for constructing lithium-containing alloys with high lithium-ion diffusion and high-modulus interface layers rich in LiF, thereby self-repairing defects in the double interface layers and constructing a second protective layer.

2. The method for preparing a lithium metal battery based on in-situ solidification according to claim 1, characterized in that, The monomer is one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, methyl acrylate, ethyl acrylate, ethylene ethylene carbonate, and vinylene carbonate; the multifunctional crosslinking agent is one of pentaerythritol tetraacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate; the lithium salt is one of LiTFSI, LiFSI, LiClO4, LiPF6, LiDFOB, and LiBOB.

3. The method for preparing a lithium metal battery based on in-situ solidification according to claim 1, characterized in that, The plasticizer is a 0.8~4 mol / L lithium salt solution, wherein the solute of the lithium salt solution is one or two of LiTFSI, LiFSI, LiClO4, LiPF6, LiDFOB, and LiBOB, and the solvent is one or more of ethylene carbonate, propylene carbonate, 1,3-dioxolane, ethylene glycol dimethyl ether, diethyl carbonate, and methyl ethyl carbonate; and the initiator is one of azobisisobutyronitrile, azobisisovalerate, and azobisisoheptanenitrile.

4. The method for preparing a lithium metal battery based on in-situ solidification according to claim 1, characterized in that, The porous framework membrane is one of the following: lignocellulose membrane, electrospun polyimide membrane, glass fiber membrane, polyethylene diaphragm, polypropylene diaphragm, and electrospun polyvinylidene fluoride membrane, with a thickness of less than 100 μm; the active material of the positive electrode is one of the following: lithium iron phosphate, lithium cobalt oxide, nickel-cobalt-manganese ternary positive electrode, and sulfur positive electrode.

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