Composite artificial SEI layer and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a composite artificial SEI layer and a preparation method and application thereof. The composite artificial SEI layer is prepared from the following raw materials: a halogen functionalized metal-organic framework material, nitrate and a polymer binder, the nitrate is selected from one or more of silver nitrate, magnesium nitrate and indium nitrate, and the atom number ratio of halogen elements to metal elements in the halogen functionalized metal-organic framework material is greater than or equal to 2. According to the lithium ion battery prepared by adopting the composite artificial SEI layer, a composite SEI interface layer of Li-M / Li3N / LiX (M = Ag, Mg and In, and X = F, Cl, Br and I) can be spontaneously constructed on the surface of a lithium metal negative electrode, so that the growth of lithium dendrites is remarkably inhibited, the interface impedance is reduced, and the cycle coulombic efficiency of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a composite artificial SEI layer and a preparation method and application thereof. Background Art

[0002] As the core material of high-energy-density batteries, lithium metal anode has a high theoretical specific capacity (3860 mAh g -1 ), an extremely low redox potential (-3.04 V) relative to the standard hydrogen electrode, and lightweight properties (density 0.534 g cm -3 ), becoming an ideal choice for breaking through the energy density bottleneck of lithium-ion batteries. However, its practical application still faces multiple challenges. For example, the uneven deposition and stripping of lithium ions during cycling can trigger the growth of lithium dendrites, which can not only pierce the separator and cause internal short circuits, but also form electrochemically inactive "dead lithium" due to dendrite breakage, resulting in irreversible loss of active material. These problems collectively lead to shortened battery cycle life, accelerated capacity decay, and even safety hazards such as thermal runaway. In the related art, constructing an artificial solid electrolyte interface (SEI) layer on the surface of the lithium metal negative electrode can promote the homogenization of lithium ion flux and achieve stable deposition and stripping of lithium ions, thereby effectively inhibiting the growth of lithium dendrites and side reactions. However, the artificial SEI layer constructed so far is usually rich in a single component of inorganic matter, which cannot meet the requirements of inducing uniform deposition of lithium ions while reducing the overpotential of lithium ion deposition and stripping. For example, the SEI layer rich in LiF, LiF has high interfacial energy and low electronic conductivity, which can effectively inhibit dendrite growth, but the extremely low ionic conductivity of LiF will lead to a large overpotential for lithium ion deposition and stripping, thereby affecting the rate performance and cycle life of the battery. In addition, the traditional solid electrolyte interface layer also has problems such as insufficient ionic conductivity and low mechanical strength. It continues to break and regenerate during the cycle, which can further aggravate side reactions and reduce Coulombic efficiency.

[0003] Based on this, there is an urgent need for a composite artificial SEI layer with high ionic conductivity, high electrochemical stability and low interfacial impedance to achieve uniform distribution of lithium ions and induce uniform deposition of lithium ions, thereby effectively inhibiting lithium dendrite growth and side reactions. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a composite artificial SEI layer, its preparation method, and its application. This composite artificial SEI layer can spontaneously construct a composite SEI interface layer of Li-M / Li3N / LiX (X = F, Cl, Br, I) on the surface of a lithium metal anode, which helps significantly inhibit the growth of lithium dendrites, reduce interfacial impedance, and thus improve the battery's cycle Coulombic efficiency.

[0005] In a first aspect of the present invention, a composite artificial SEI layer is provided, wherein the raw materials for preparing the composite artificial SEI layer include: a halogen-functionalized metal-organic framework material (hereinafter referred to as halogen-functionalized MOFs), a nitrate, and a polymer binder; The nitrate is selected from one or more of silver nitrate, magnesium nitrate, and indium nitrate, and the ratio of the number of atoms of the halogen element to the metal element in the halogen-functionalized metal-organic framework material is ≥2.

[0006] In some embodiments of the present invention, the ratio of the number of atoms of the halogen element to the metal element in the halogen-functionalized metal-organic framework material is ≤6.

[0007] In some embodiments of the present invention, the halogen atoms in the halogen-functionalized metal-organic framework material are selected from one or more of fluorine, chlorine, bromine and iodine.

[0008] In some embodiments of the present invention, the metal element is selected from one or more of zirconium, cerium, and hafnium.

[0009] In some embodiments of the present invention, the method for preparing the halogen-functionalized metal-organic framework material comprises: The organic ligand containing the halogen atom, the metal salt and the pH regulator are mixed in a solvent, reacted, washed and dried to obtain the product.

[0010] In some embodiments of the present invention, the solvent is selected from one or more of water, N,N-dimethylformamide, ethanol, and methanol.

[0011] In some embodiments of the present invention, the organic ligand is selected from one or more of difluoroterephthalic acid, dichloroterephthalic acid, dibromoterephthalic acid, tetrafluoroterephthalic acid, tetrachloroterephthalic acid, tetrabromoterephthalic acid, tetraiodoterephthalic acid, 2-(trifluoromethoxy)terephthalic acid, 2-(trifluoromethyl)terephthalic acid, 2,5-bis(trifluoromethyl)terephthalic acid, 3-(trifluoromethyl)benzoic acid, and 3,5-bis(trifluoromethyl)benzoic acid.

[0012] In some embodiments of the present invention, the metal salt is selected from one or more of zirconium oxynitrate hydrate, cerium ammonium nitrate, hafnium chloride, and zirconium chloride.

[0013] In some embodiments of the present invention, the pH adjuster is selected from one or more of acetic acid, hydrofluoric acid, and glacial acetic acid.

[0014] In some embodiments of the present invention, the polymer binder is selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polystyrene butadiene copolymer, polyacrylic acid, polyethylene oxide, and sodium carboxymethyl cellulose.

[0015] In some embodiments of the present invention, the ratio of the halogen-functionalized metal-organic framework material, the nitrate, and the polymer binder is 80-95:1-20:1-20 by mass.

[0016] In some preferred embodiments of the present invention, the ratio of the halogen-functionalized metal-organic framework material, the nitrate, and the polymer binder is 85-90:5-10:10-15 by mass.

[0017] In some embodiments of the present invention, in the composite artificial SEI layer, by mass ratio, the halogen-functionalized metal-organic framework material is ≥80 wt %, the nitrate is ≥5 wt %, and the polymer binder is ≥10 wt %.

[0018] In some embodiments of the present invention, the raw materials for preparing the composite artificial SEI layer further include an organic solvent.

[0019] In some embodiments of the present invention, the organic solvent is selected from one or more of N-methylpyrrolidone, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0020] A second aspect of the present invention provides a method for preparing the composite artificial SEI layer according to any one of the first aspects of the present invention, comprising the following steps: The raw materials for preparing the composite artificial SEI layer are mixed, coated on a substrate, and dried to obtain the composite artificial SEI layer.

[0021] In some embodiments of the present invention, the substrate comprises a lithium copper composite material.

[0022] In some embodiments of the present invention, the thickness of the composite artificial SEI layer satisfies the following relationship: T = k × (M1 / M2); Wherein, k=0.15~0.2; M1 is the mass of the halogen-functionalized metal-organic framework material in the composite artificial SEI layer; M2 is the mass of the nitrate in the composite artificial SEI layer; and T is the thickness of the composite artificial SEI layer, in μm.

[0023] Although a too-thin composite artificial SEI layer can reduce interfacial impedance, it lacks mechanical strength and is prone to rupture, leading to localized lithium dendrite growth and exacerbated interfacial side reactions. A moderate composite artificial SEI thickness balances mechanical stability and ion transport efficiency. Excessively thick composite artificial SEI layers increase lithium ion transport pathways, leading to increased polarization and uneven lithium ion deposition.

[0024] In some embodiments of the present invention, the value range of M1 is: 80≤M1≤95. Specifically, the value of M1 can be 80, 82, 85, 88, 90, 92 or 95.

[0025] In some embodiments of the present invention, the value range of M2 is: 1≤M2≤20. Specifically, the value of M2 can be 1, 2, 5, 8, 10, 12, 15, 18 or 20.

[0026] When the ratio of M1 to M2 (M1 / M2) falls within a certain range (0.15 ≤ k ≤ 0.20), the thickness (T) of the composite artificial SEI layer can optimize ion transport efficiency and mechanical stability, avoiding lithium dendrite growth caused by being too thin and increased polarization caused by being too thick. Specifically, a moderate composite artificial SEI layer thickness can balance mechanical strength and ion transport pathways, thereby improving battery performance. When the M1 / M2 ratio is within an appropriate range, it can effectively improve the stability of the SEI layer, ensuring that it is not easily broken during battery use, reducing interfacial side reactions, and at the same time enhancing ion transport capabilities, thereby improving the battery's cycle life and safety.

[0027] When the thickness of the composite artificial SEI layer and the ratio between M1 and M2 satisfy the above relationship, where k=0.15~0.2, the fast ion transport channels after the high-density halogen sites in the metal-organic framework react with nitrates can form an interpenetrating network structure. The metal-organic framework material inhibits the growth of lithium dendrites through the rigid skeleton and the high interfacial energy and shear modulus rich in LiX components, while the excellent lithium affinity of Li-M / Li3N formed by the reaction of nitrate components induces uniform lithium deposition and reduces the interfacial impedance, thereby promoting uniform deposition of lithium ions.

[0028] In some embodiments of the present invention, the composite artificial SEI layer spontaneously constructs a Li-M / Li3N / LiX layer on the surface of the lithium metal negative electrode, wherein the M is selected from any one of Ag, Mg, and In; and the X is selected from any one of F, Cl, Br, and I.

[0029] The third aspect of the present invention provides a negative electrode material comprising the composite artificial SEI layer according to any one of the first aspects of the present invention.

[0030] In some embodiments of the present invention, the thickness of the composite artificial SEI layer is 0.1 to 1000 μm. Specifically, the thickness of the composite artificial SEI layer is 0.1, 0.5, 1, 3, 5, 10, 20, 50, 100, 200, 500 or 1000 μm.

[0031] A fourth aspect of the present invention provides use of the composite artificial SEI layer as described in any one of the first aspects of the present invention in the preparation of a lithium-containing battery.

[0032] The beneficial effects of the present invention include at least the following: (1) Batteries made using the composite artificial SEI layer of the present invention have low overpotential and excellent electrical performance. The halogen-functionalized MOFs used as raw materials for preparation have high porosity and uniform pore structure, which helps to improve the wettability of the electrolyte and promote the uniformity of lithium ion flux. In addition, the organic ligands in the halogen-functionalized MOFs used in the present invention contain electron-rich halogen elements, which can accelerate the transmission of lithium ions by interacting with anions. Moreover, the halogen elements in the halogen-functionalized MOFs can form a LiX (X = F, Cl, Br, I)-rich SEI layer on the surface of lithium metal, which has high interfacial energy and shear modulus with lithium-stabilized LiX, and can effectively inhibit the growth of lithium dendrites.

[0033] (2) The battery made with the composite artificial SEI layer of the present invention has the advantage of low impedance. The present invention uses nitrate as a preparation raw material. During the charge and discharge process, the metal ions (M) in the nitrate are reduced by metallic lithium to form a Li-M (M = Ag, Mg, In) alloy on the surface of the lithium metal negative electrode. The excellent lithium affinity of the Li-M alloy induces uniform lithium deposition, and the NO3 dissociated from the nitrate - A Li3N-rich SEI layer is formed on the surface of the lithium metal anode, and the high ionic conductivity of Li3N helps promote the + Diffusion in the SEI layer can reduce the interface impedance.

[0034] (3) Batteries made with the composite artificial SEI layer of the present invention have excellent cycling performance. During the battery cycle, the composite artificial SEI layer spontaneously constructs a composite SEI interface layer of Li-M / Li3N / LiX (X = F, Cl, Br) on the surface of the lithium metal negative electrode, which helps to inhibit the growth of lithium dendrites and reduce interfacial impedance, thereby improving the battery's cycling Coulombic efficiency.

[0035] Other features and advantages of the present invention will be set forth in the description that follows. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0037] The terms "preferably," "more preferably," and the like, used herein refer to embodiments of the present invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the present invention.

[0038] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.

[0039] In the description of the present invention, the reference term "and / or" includes all and any combinations of one or more of the associated listed items.

[0040] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0041] In the description of the present invention, room temperature refers to 25±5°C. If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0042] Example 1: This embodiment provides a preparation method of a halogen-functionalized metal-organic framework (MOF) material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0043] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this embodiment includes the following steps: S1. Dissolve 1.27 g of 2,5-difluoroterephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0044] The ratio of the number of atoms of the halogen element fluorine to the metal element zirconium in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0045] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this embodiment uses the halogen-functionalized metal-organic framework material prepared above as a raw material for coating preparation. The raw materials for preparing the composite artificial SEI layer coating include, by weight: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of silver nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0046] Wherein, the polymer binder is polyvinylidene fluoride.

[0047] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, silver nitrate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry; S2. The coating slurry is coated on a lithium-copper composite tape (Tianjin Zhongneng Lithium Industry Co., Ltd.), and after drying, a lithium-copper composite tape modified with a composite artificial SEI layer is obtained, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0048] Example 2: This embodiment provides a method for preparing a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0049] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material in this embodiment differs from that in Example 1 in that 1.27 g of 2,5-difluoroterephthalate is replaced by 1.48 g of 2,5-dichloro-p-dibenzoic acid, and the remaining steps are the same, as follows: S1. Dissolve 1.48 g of 2,5-dichloro-p-dibenzoic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0050] The ratio of the number of atoms of the halogen element chlorine to the metal element zirconium in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0051] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this embodiment uses the halogen-functionalized metal-organic framework material prepared above as a raw material for coating preparation. The raw materials for preparing the composite artificial SEI layer coating include, by weight: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of silver nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0052] Wherein, the polymer binder is polyvinylidene fluoride.

[0053] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, silver nitrate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0054] Example 3: This embodiment provides a method for preparing a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0055] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material in this embodiment differs from that in Example 1 in that 1.27 g of 2,5-difluoroterephthalate is replaced by 2.04 g of 2,5-dibromoterephthalic acid, and the remaining steps are the same, as follows: S1. Dissolve 2.04 g of 2,5-dibromoterephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0056] The ratio of the number of atoms of the halogen element bromine to the metal element zirconium in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0057] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this embodiment uses the halogen-functionalized metal-organic framework material prepared above as a raw material for coating preparation. The raw materials for preparing the composite artificial SEI layer coating include, by weight: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of silver nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0058] Wherein, the polymer binder is polyvinylidene fluoride.

[0059] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, silver nitrate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0060] Example 4: This embodiment provides a method for preparing a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0061] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this embodiment includes the following steps: S1. Dissolve 1.27 g of 2,5-difluoroterephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0062] The ratio of the number of halogen element fluorine to the number of metal element zirconium atoms in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0063] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this embodiment uses the halogen-functionalized metal-organic framework material prepared above as a coating preparation raw material. The raw materials for preparing the composite artificial SEI layer coating differ from those in Example 1 in that silver nitrate is replaced by magnesium nitrate. The raw materials for preparing the composite artificial SEI layer coating, calculated in parts by mass, include: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of magnesium nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0064] Wherein, the polymer binder is polyvinylidene fluoride.

[0065] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, magnesium nitrate, and a polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry. S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0066] Example 5: This embodiment provides a method for preparing a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0067] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this embodiment includes the following steps: S1. Dissolve 1.90 g of 2,5-bis(trifluoromethyl)terephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0068] The ratio of the number of atoms of the halogen element fluorine to the metal element zirconium in the halogen-functionalized metal-organic framework material synthesized by the above method is 6.

[0069] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this embodiment uses the halogen-functionalized metal-organic framework material prepared above as a raw material for preparing the coating. The raw materials for preparing the composite artificial SEI layer coating differ from those in Example 1 in that silver nitrate is replaced by indium nitrate. The raw materials for preparing the composite artificial SEI layer coating, calculated in parts by mass, include: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of indium nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0070] Wherein, the polymer binder is polyvinylidene fluoride.

[0071] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, indium nitrate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0072] Comparative Example 1: This comparative example provides a preparation method of a non-halogen functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0073] 1. Preparation of halogen-free functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this comparative example comprises the following steps: S1. Dissolve 1.32 g of terephthalic acid and 0.93 g of zirconium chloride in 24 mL of N,N-dimethylformamide by ultrasonication to obtain a mixture. S2. Add 0.67 mL of concentrated hydrochloric acid to the mixture, place the mixed solution in a 50 mL autoclave, and heat at 220°C for 16 h. Then, wash the mixture with N,N-dimethylformamide and ethanol by centrifugation, and dry it under vacuum at 80°C for 24 h. Afterwards, collect the powder to obtain a non-halogen-functionalized metal-organic framework.

[0074] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this comparative example uses the non-halogen functionalized metal-organic framework material prepared above as a coating preparation raw material. The raw materials for preparing the composite artificial SEI layer coating, calculated by weight, include: 85 parts of non-halogen functionalized metal-organic framework materials; 5 parts of silver nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0075] Wherein, the polymer binder is polyvinylidene fluoride.

[0076] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the non-halogen-functionalized metal-organic framework material, silver nitrate, and a polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry. S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0077] Comparative Example 2: This comparative example provides a preparation method of a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0078] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this comparative example comprises the following steps: S1. Dissolve 1.27 g of 2,5-difluoroterephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0079] The ratio of the number of atoms of the halogen element fluorine to the metal element zirconium in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0080] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this comparative example uses the halogen-functionalized metal-organic framework material prepared above as a coating preparation raw material. The raw materials for preparing the composite artificial SEI layer coating differ from those in Example 1 in that silver nitrate is replaced by lithium nitrate. The raw materials for preparing the composite artificial SEI layer coating, calculated in parts by mass, include: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of lithium nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0081] Wherein, the polymer binder is polyvinylidene fluoride.

[0082] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, lithium nitrate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0083] Comparative Example 3: This comparative example provides a preparation method of a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0084] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this comparative example comprises the following steps: S1. Dissolve 1.27 g of 2,5-difluoroterephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0085] The ratio of the number of atoms of the halogen element fluorine to the metal element zirconium in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0086] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this comparative example uses the halogen-functionalized metal-organic framework material prepared above as a coating preparation raw material. The raw materials for preparing the composite artificial SEI layer coating differ from those in Example 1 in that silver nitrate is replaced by silver acetate. The raw materials for preparing the composite artificial SEI layer coating, calculated in parts by mass, include: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of silver acetate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0087] Wherein, the polymer binder is polyvinylidene fluoride.

[0088] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, silver acetate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0089] Comparative Example 4: This comparative example provides a preparation method of a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0090] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this comparative example comprises the following steps: S1. Dissolve 1.27 g of 2,5-difluoroterephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0091] The ratio of the number of atoms of the halogen element fluorine to the metal element zirconium in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0092] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this comparative example uses the halogen-functionalized metal-organic framework material prepared above as a coating raw material. The raw materials used to prepare the composite artificial SEI layer coating differ from those in Example 1 in that no silver nitrate is added, and the mass ratio of the halogen-functionalized metal-organic framework material to the polymer binder polyvinylidene fluoride is adjusted to 90:10. The raw materials used to prepare the composite artificial SEI layer coating, in parts by mass, include: 90 parts of halogen-functionalized metal-organic framework materials; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0093] Wherein, the polymer binder is polyvinylidene fluoride.

[0094] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material and the polymer binder (polyvinylidene fluoride) are thoroughly stirred and mixed at a mass ratio of 90:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0095] Comparative Example 5: This comparative example provides a preparation method of a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0096] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation of the halogen-functionalized metal-organic framework material of this comparative example comprises the following steps: S1. Dissolve 1.27 g of 2,5-difluoroterephthalic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0097] The ratio of the number of halogen element fluorine to the number of metal element zirconium atoms in the halogen-functionalized metal-organic framework material synthesized by the above method is 2.

[0098] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer in this comparative example uses the halogen-functionalized metal-organic framework material prepared above as the raw material for preparing the coating. The difference between the raw materials for preparing the composite artificial SEI layer coating and those in Example 1 is that the mass ratio of the halogen-functionalized metal-organic framework material, silver nitrate, and polymer binder is adjusted to 80:10:10.

[0099] The raw materials for preparing the composite artificial SEI layer coating include, by weight: 80 parts of halogen-functionalized metal-organic framework materials; 10 parts of silver nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0100] Wherein, the polymer binder is polyvinylidene fluoride.

[0101] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, silver nitrate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 80:10:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0102] Comparative Example 6: This comparative example provides a preparation method of a halogen-functionalized metal-organic framework material and its application in a composite artificial SEI layer, which specifically includes the following contents.

[0103] 1. Preparation of halogen-functionalized metal-organic framework materials The preparation method of the halogen-functionalized metal-organic framework material in this comparative example differs from that in Example 1 in that 1.27 g of 2,5-difluoroterephthalate is replaced with 1.16 g of 2-fluoro-p-dibenzoic acid, and the remaining steps are the same. Specifically, the following steps are performed: S1. Dissolve 1.16 g of 2-fluoro-p-dibenzoic acid in 50 mL of deionized water and 2.25 g of zirconium oxynitrate hydrate (ZrO(NO3)2•xH2O, CAS No.: 14985-18-3) in 50 mL of deionized water by ultrasonication, and then mix the two solutions to obtain a mixture; S2. Add 12.5 mL of acetic acid to the mixture, stir at room temperature for 48 h, then wash with deionized water and ethanol by centrifugation, and collect the powder after vacuum heating and drying at 80° C. for 24 h to obtain a halogen-functionalized metal-organic framework material.

[0104] The ratio of the number of halogen element fluorine to the number of metal element zirconium atoms in the halogen functionalized metal-organic framework material synthesized by the above method is 1.

[0105] 2. Preparation of composite artificial SEI layer The composite artificial SEI layer of this comparative example uses the halogen-functionalized metal-organic framework material prepared above as a coating preparation raw material. The raw materials for preparing the composite artificial SEI layer coating, calculated by weight, include: 85 parts of halogen-functionalized metal-organic framework materials; 5 parts of silver nitrate; 10 parts of polymer binder; 100 parts of N-methylpyrrolidone.

[0106] Wherein, the polymer binder is polyvinylidene fluoride.

[0107] The preparation method of the composite artificial SEI layer specifically comprises the following steps: S1. In an N-methylpyrrolidone solvent system, the halogen-functionalized metal-organic framework material, silver nitrate, and polymer binder (polyvinylidene fluoride) were thoroughly stirred and mixed in a mass ratio of 85:5:10 to obtain a coating slurry; S2. Apply the coating slurry on a lithium-copper composite tape, and after drying, obtain a lithium-copper composite tape modified with a composite artificial SEI layer, wherein the thickness of the composite artificial SEI layer is 3 μm.

[0108] Test Example 1: Deposition / stripping cycle performance test This test example tests the deposition / stripping cycle performance of the lithium-lithium symmetrical cells of Examples 1-5 and Comparative Examples 1-6. The specific test method is as follows: The lithium-copper composite tapes modified with the composite artificial SEI layer prepared in Examples 1-5 and Comparative Examples 1-6 were cut into 16 mm diameter discs and assembled into symmetrical CR2032 cells using a 19 mm diameter commercial polypropylene separator. The electrolyte used was an ethylene carbonate (EC) / ethyl methyl carbonate (EMC) system containing 1 M LiPF6, with a volume ratio of EC to EMC of 3:7. The electrolyte volume was 50 μL.

[0109] The cycle performance test method is as follows: the assembled CR2032 symmetrical battery is charged at a current density of 0.5 mA cm -2 The battery was charged and discharged at a constant current for 1 hour each, and the cycle was repeated several times. The criterion for judging the cycling performance was: if the voltage suddenly increased during the cycle, it indicated that the lithium dendrites had grown seriously, and the time corresponding to this moment was determined as the cycling performance.

[0110] The overpotential detection method is as follows: the assembled battery is charged at a current density of 0.5 mA cm -2 The overpotential of the symmetrical battery was calculated by charging and discharging at constant current for 1 hour each cycle. The overpotential after 100 cycles was recorded. Repeat 5 times per group and take the average value. The absolute value of the lowest potential of the symmetrical battery after 100 cycles of constant current discharge is the overpotential of the symmetrical battery.

[0111] Table 1 shows the experimental results of the deposition / stripping cycle performance of lithium-lithium symmetric cells of Examples 1-5 and Comparative Examples 1-6.

[0112] Table 1:

[0113] The test results in Table 1 demonstrate that the cycling performance of symmetrical cells fabricated using lithium-copper composite ribbons modified with the composite artificial SEI layer of Examples 1-5 of the present invention is superior to that of the corresponding symmetrical cells fabricated in Comparative Examples 1-6. Longer cycling times indicate a greater number of cycles. Furthermore, after 100 cycles, the overpotentials of the symmetrical cells of Examples 1-5 are all lower than those of Comparative Examples 1-6. The excellent cycling performance and low overpotential of the symmetrical cells of Examples 1-5 demonstrate that the composite artificial SEI layer constructed on the surface of the lithium metal anode effectively inhibits lithium dendrite growth and induces uniform lithium ion deposition.

[0114] Compared with Example 1, Comparative Example 1 uses a non-halogen functionalized metal-organic framework material as the SEI layer raw material. The results show that the cycle performance of its symmetrical battery is significantly reduced. It is speculated that this is because the composite artificial SEI layer in Comparative Example 1 lacks LiF, which causes its interfacial energy to be significantly reduced, making it difficult to effectively inhibit the growth of lithium dendrites, ultimately leading to a decrease in cycle performance and a high overpotential.

[0115] Compared with Example 1, Comparative Example 2 replaces the raw material silver nitrate with lithium nitrate, and Comparative Example 3 replaces silver nitrate with silver acetate. The results show that the cycle performance of the symmetrical batteries in Comparative Examples 2 and 3 is significantly reduced. It is speculated that this is because compared with the Li-M / Li3N / LiX composite artificial SEI layer formed in Example 1, the composite artificial SEI layer in Comparative Example 2 lacks Li-M alloy (M is Ag), and the composite artificial SEI layer in Comparative Example 3 lacks Li3N, which leads to the growth of lithium dendrites and the formation of dead lithium, and the corresponding overpotentials are also greater than those in the embodiments.

[0116] Compared with Example 1, no silver nitrate was added during the preparation of the composite artificial SEI layer of Comparative Example 4, and the mass ratio of the halogen-functionalized metal-organic framework material and the polymer binder polyvinylidene fluoride was adjusted to 90:10. The results showed that the overpotential of the symmetrical battery of Comparative Example 4 after 100 cycles was significantly increased, reaching 269 mV. It is speculated that this is due to the lack of Li-M alloy and Li3N in the composite artificial SEI in Comparative Example 4, which leads to an increase in the relative proportion of LiF; the extremely low ionic conductivity of LiF leads to a large overpotential for lithium ion deposition and stripping.

[0117] Compared with Example 1, in the preparation process of the composite artificial SEI layer of Comparative Example 5, the mass ratio of the halogen-functionalized metal-organic framework material, nitrate, and polymer binder polyvinylidene fluoride was adjusted to 80:10:10. The results showed that its cycle performance decreased to varying degrees, and the overpotential also increased significantly, indicating that this ratio is not conducive to the battery cycle performance and the improvement of the inhibition effect on lithium dendrites.

[0118] Compared with Example 1, Comparative Example 6 replaces 1.27 g of 2,5-difluoroterephthalate in Example 1 with 1.16 g of 2-fluoro-p-dibenzoic acid, and the ratio of halogen to metal in the synthesized halogen-functionalized metal-organic framework material is 1. By comparing Example 1 and Comparative Example 6, it is found that when the ratio of halogen to metal in the halogen-functionalized metal-organic framework material is less than 2, the cycle performance of the symmetrical battery decreases and the overpotential is higher. This is because the reduction of halogen atoms in MOFs reduces the LiF content in the composite artificial SEI layer formed on the lithium metal surface, reducing the dendrite resistance of lithium dendrites, thereby resulting in decreased cycle performance and a higher overpotential.

[0119] Test Example 2: Impedance Test This test example tests the impedance of symmetrical batteries made with the composite artificial SEI layer of Examples 1-5 and Comparative Examples 1-6. The specific test method is as follows: Referring to the method of Test Example 1 above, the lithium-copper composite tapes modified with the composite artificial SEI layer prepared in Examples 1-5 and Comparative Examples 1-6 were cut into small discs with a diameter of 16 mm. A symmetrical CR2032 battery was assembled using a commercial polypropylene separator with a diameter of 19 mm. The electrolyte used was an ethylene carbonate (EC) / ethyl methyl carbonate (EMC) system containing 1 M LiPF6, with a volume ratio of EC to EMC of 3:7. The electrolyte dosage was 50 μL.

[0120] The assembled symmetrical cell was tested at a current density of 0.5 mA cm -2 The cells were charged and discharged at a constant current for 1 h each for 5 cycles. The AC impedance test was then performed to obtain the impedance of the symmetrical cells with different composite artificial SEI layers. Each group was repeated 5 times and the average value was taken.

[0121] Table 2 shows the impedance of the symmetrical batteries of Examples 1-5 and Comparative Examples 1-6.

[0122] Table 2:

[0123] As can be seen from the test results in Table 2, the impedance of the symmetrical batteries prepared using the composite artificial SEI layers of Examples 1-5 is lower than that of Comparative Examples 1-6. This is presumably due to the reduced interfacial reaction between the constructed composite artificial SEI layer and the electrolyte, resulting in the formation of a stable composite artificial SEI interface layer. In addition, the low impedance of the symmetrical battery also indicates that the composite SEI layer of the embodiments of the present invention can accelerate and induce uniform lithium deposition, and reduce the overpotential of lithium deposition.

[0124] Compared to Example 1, Comparative Examples 1-3 failed to spontaneously form a composite SEI layer of Li-M / Li3N / LiX on the lithium metal anode surface. For example, the composite artificial SEI layer in Comparative Example 1 lacked LiX, the composite artificial SEI layer in Comparative Example 2 lacked the Li-M alloy, and the composite artificial SEI layer in Comparative Example 3 lacked Li3N, failing to form the composite artificial SEI layer described in the examples. The synergistic effect of the composite artificial SEI layer effectively reduced the impedance of the symmetrical battery.

[0125] The impedance of the symmetrical battery of Comparative Example 4 is the largest, which is attributed to the increase in the relative proportion of LiF in the composite artificial SEI in Comparative Example 4. The extremely low ionic conductivity of LiF leads to slow diffusion of lithium ions, resulting in high impedance of the symmetrical battery.

[0126] Compared with Comparative Example 5, the symmetrical battery of Example 1 has lower impedance, indicating that when the ratio of halogen-functionalized metal-organic framework material: nitrate: polymer binder is 85:5:10, the performance is better and it is more conducive to accelerating and inducing uniform deposition of lithium, thereby inhibiting lithium dendrites.

[0127] Further by comparing Example 1 and Comparative Example 6, it can be seen that when the ratio of halogen elements to metal elements in the halogen-functionalized metal-organic framework material is less than 2, the impedance of the symmetrical battery will increase significantly. It is speculated that the presence of halogens will affect the proportion of each component in the composite artificial SEI layer, thereby leading to the growth of dendrites and the diffusion of lithium ions, and thus the impedance increases.

[0128] In summary, the present invention provides a composite artificial SEI layer and its preparation method and application. By comparing Examples 1-5 and Comparative Examples 1-6, the present invention found that the composite artificial SEI layer prepared by using halogen-functionalized metal-organic framework materials, nitrates and binders, the composite artificial SEI layer spontaneously constructs a composite SEI interface layer of Li-M / Li3N / LiX on the surface of the lithium metal negative electrode, which can effectively induce the uniform deposition of lithium ions, reduce the overpotential of lithium ion deposition, and accelerate the rapid diffusion of lithium ions. In addition, the synergistic effect of multiple components in the composite artificial SEI layer can effectively inhibit the growth of lithium dendrites, wherein the excellent lithium affinity of the Li-M alloy accelerates the conduction of lithium ions and induces uniform lithium deposition; Li3N with high ionic conductivity promotes the diffusion of lithium ions in the SEI layer, reduces the deposition overpotential and interface impedance, and has a higher interface energy with lithium-stabilized LiX, which can effectively inhibit the growth of lithium dendrites and improve the cycle performance of the battery.

[0129] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A composite artificial SEI layer, characterized in that: The preparation raw materials include: halogen functionalized metal-organic framework material, nitrate, polymer binder; The nitrate is selected from one or more of silver nitrate, magnesium nitrate, and indium nitrate, and the ratio of the number of atoms of the halogen element to the metal element in the halogen-functionalized metal-organic framework material is ≥2.

2. The composite artificial SEI layer according to claim 1, characterized in that The halogen atoms in the halogen-functionalized metal-organic framework material are selected from one or more of fluorine, chlorine, bromine and iodine; And / or, the metal element is selected from one or more of zirconium, cerium, and hafnium.

3. The composite artificial SEI layer according to claim 2, characterized in that The preparation method of the halogen-functionalized metal-organic framework material comprises: The organic ligand containing the halogen atom, the metal salt and the pH regulator are mixed in a solvent, reacted, washed and dried to obtain the product.

4. The composite artificial SEI layer according to claim 3, characterized in that The solvent is selected from one or more of water, N,N-dimethylformamide, ethanol, and methanol; And / or, the organic ligand is selected from one or more of 2,5-difluoroterephthalic acid, 2,5-dichloroterephthalic acid, 2,5-dibromoterephthalic acid, 2,5-diiodoterephthalic acid, tetrafluoroterephthalic acid, tetrachloroterephthalic acid, tetrabromoterephthalic acid, tetraiodoterephthalic acid, 2-(trifluoromethoxy)terephthalic acid, 2-(trifluoromethyl)terephthalic acid, and 2,5-bis(trifluoromethyl)terephthalic acid; and / or, the metal salt is selected from one or more of zirconium oxynitrate hydrate, zirconium chloride, cerium ammonium nitrate, and hafnium chloride; And / or, the pH adjuster is selected from one or more of acetic acid, hydrofluoric acid, and glacial acetic acid.

5. The composite artificial SEI layer according to claim 1, characterized in that: The polymer binder is selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polystyrene butadiene copolymer, polyacrylic acid, polyethylene oxide, and sodium carboxymethyl cellulose.

6. The composite artificial SEI layer according to any one of claims 1 to 5, characterized in that: In terms of mass ratio, the ratio of the halogen-functionalized metal-organic framework material, the nitrate, and the polymer binder is 80-95:1-20:1-20.

7. The composite artificial SEI layer according to claim 6, characterized in that: The raw materials for preparing the composite artificial SEI layer also include an organic solvent.

8. The method for preparing a composite artificial SEI layer according to any one of claims 1 to 7, wherein: The following steps are involved: The raw materials for preparing the composite artificial SEI layer are mixed, coated on a substrate, and dried to obtain the composite artificial SEI layer.

9. The preparation method according to claim 8, characterized in that The thickness of the composite artificial SEI layer satisfies the following relationship: T = k × (M1 / M2); Wherein, k=0.15~0.20; M1 is the mass ratio of the halogen-functionalized metal-organic framework material in the composite artificial SEI layer; M2 is the mass ratio of the nitrate in the composite artificial SEI layer; and T is the thickness of the composite artificial SEI layer, in μm.

10. A negative electrode material, characterized in that: Comprising the composite artificial SEI layer according to any one of claims 1 to 7.

11. Use of the composite artificial SEI layer according to any one of claims 1 to 7 in preparing a lithium-containing battery.

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