Lithium metal sheet with interface protection layer as well as preparation method and application of lithium metal sheet

Abstract

The invention discloses a lithium metal sheet with an interface protection layer and a preparation method and application thereof. The lithium metal sheet comprises a lithium metal sheet body and the interface protection layer attached to the surface of the lithium metal sheet body, the interface protection layer is prepared from the following materials: a reaction monomer, a crosslinking monomer, an additive, an initiator, a plasticizer and lithium salt; wherein the reaction monomer is set to be of a structure containing a carbonyl functional group. According to the lithium metal sheet with the interface protection layer provided by the invention, relatively good electrochemical performance can be shown through a synergistic effect among the components, and stable work of a battery cell is realized.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a lithium metal sheet with an interface protection layer, a preparation method and an application thereof. Background Art

[0002] Lithium-ion batteries, as the energy core of modern mobile electronic devices and electric vehicles, have become a hot topic of global research and development. The working principle of lithium-ion batteries is based on the reciprocating movement of lithium ions between the positive and negative electrodes; during the discharge process, lithium ions move from the negative electrode to the positive electrode, while electrons flow from the negative electrode to the positive electrode through an external circuit to provide power; during the charging process, lithium ions and electrons move in the opposite direction. The positive electrode material is usually composed of lithium metal oxide (such as LiCoO2, LiMn2O4, LiFePO4, etc.), and the negative electrode material is mostly graphite. The electrolyte is the medium for the movement of lithium ions inside the battery, and the diaphragm serves as an isolation layer between the positive and negative electrodes, preventing short circuits while allowing lithium ions to pass.

[0003] In recent years, with the advancement of science and technology and market demand, the research and development focus of lithium-ion batteries has gradually shifted to improving energy density, extending life, reducing costs and improving safety. For example, the development of new high-capacity battery materials, optimization of electrolytes and diaphragms, innovation of battery structure and design, advancement of system integration and management technology, and multi-scale modeling and simulation.

[0004] The positive electrode ternary material can significantly increase the material's gram capacity by increasing the Ni content; at the same time, the surface is coated to isolate the corrosion and reaction between the material and the electrolyte, thereby improving the material's stability; the material's capacity can also be improved by optimizing the material's preparation process, particle size distribution and morphology; the design of a stable single crystal structure can also improve the material's stability and cycle performance. Lithium manganese iron phosphate, which combines the safety of lithium iron phosphate and the high energy density of ternary materials, has also been a hot research subject in recent years. Currently, some low-speed two-wheel lithium batteries have begun to introduce this type of material.

[0005] The competitive materials for negative electrode materials have gradually shifted from graphite to silicon materials. The Si negative electrode based on the conversion reaction can easily achieve the goal of high gram capacity, which greatly improves the energy density of the battery cell. However, this type of material is accompanied by huge volume changes (300%) and rapid capacity decay during the charging and discharging process, which limits its development and promotion. Researchers realize the application of materials by nano-processing the materials, building porous structures and developing silicon-carbon / silicon-oxygen materials.

[0006] At the same time, lithium metal based on chemical conversion reactions has also become a current research hotspot. This type of material has the characteristics of high specific capacity, low discharge potential and low density, which can greatly improve the energy density of the battery cell. Due to the particularity of the outer electrons of lithium metal (1S22S1), the material has extremely high chemical reactivity. Researchers use inorganic chemical reactions, atomic layer deposition and electrolyte modification to achieve the use of lithium metal. However, the inorganic chemical reaction and atomic layer deposition schemes usually require the support of high-precision equipment. During the entire experimental process, the requirements for the environment and target materials are extremely harsh; and the electrolyte modification scheme, on the one hand, needs to break the existing lithium-ion battery design, and on the other hand, it also needs to face the chemical reaction between lithium metal and electrolyte.

[0007] Therefore, there is an urgent need to provide a lithium metal sheet with an interface protection layer and a preparation method and application thereof to solve the above-mentioned technical problems. Summary of the invention

[0008] The present application provides a lithium metal sheet with an interface protection layer, a preparation method and an application thereof, which promote the uniform deposition of lithium ions on the surface of the lithium metal through a synergistic effect, improve the electrochemical performance of the battery, and achieve stable operation of the battery cell.

[0009] According to some embodiments, the present application provides a lithium metal sheet with an interface protective layer, comprising: a lithium metal sheet body, and an interface protective layer attached to the surface of the lithium metal sheet body; the material of the interface protective layer includes: a reactive monomer, a cross-linking monomer, an additive, an initiator, a plasticizer and a lithium salt; wherein the reactive monomer is configured as a structure containing a carbonyl functional group.

[0010] A preferred solution is that, in terms of weight percentage: the molar ratio of the reactive monomer to the cross-linking monomer is (82-95):(5-18); the amount of the initiator added is 1.0-2.0% of the total amount of the reactive monomer and the cross-linking monomer; the amount of the additive added is 8.0-12.0% of the total amount of the reactive monomer and the cross-linking monomer; the mass ratio of the plasticizer to the lithium salt is (1-2):(1-2).

[0011] A preferred solution is that the reactive monomer includes at least one of glycidyl methacrylate, glycidyl acrylate, and methyl methacrylate; and / or the cross-linking monomer includes at least one of pentaerythritol triacrylate, 1,6-hexanediol diacrylate, and tri(ethylene glycol) diacrylate.

[0012] A preferred solution is that the initiator is azobisisobutyronitrile; and / or the additive includes at least one of succinonitrile, 2-butenenitrile, and dicyanoethylene; and / or the plasticizer includes at least one of dioxolane and trioxymethylene; and / or the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium perchlorate.

[0013] According to some embodiments, the present application also provides a method for preparing the lithium metal sheet with an interface protection layer, the method comprising the following steps:

[0014] Mixing the reaction monomer and the cross-linking monomer, and adding the first solvent, the initiator and the additive to obtain a precursor solution;

[0015] The obtained precursor solution is polymerized under the protection of a protective gas to obtain a first solution;

[0016] removing impurities from the first solution obtained under a heating environment to obtain a polymer;

[0017] dissolving the obtained polymer in a second solvent, and adding a plasticizer and a lithium salt to obtain a second solution;

[0018] The obtained second solution is dispersed on the surface of the lithium metal sheet body to obtain a lithium metal sheet with an interface protection layer in a dry environment.

[0019] A preferred solution is that the first solvent includes at least one of ethylene glycol diethyl ether, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate;

[0020] And / or, the second solvent includes at least one of acetonitrile solution, dimethyl sulfoxide, and tetrahydrofuran.

[0021] A preferred solution is that the polymerization conditions are set as: stirring under 50-70°C oil bath heating conditions.

[0022] A preferred solution is that the conditions of the heating environment are set as: blast baking at 50-70°C for 9-12 hours and baking at 40-60°C under vacuum conditions for 1-3 hours.

[0023] According to some embodiments, the present application also provides an application of the lithium metal sheet with an interface protection layer and the method for preparing the lithium metal sheet with an interface protection layer in a secondary lithium battery.

[0024] A preferred solution is that the lithium metal sheet with an interface protection layer is used as the negative electrode; and / or the secondary lithium battery is selected from any one of a lithium sulfur battery, a lithium nickel cobalt manganese oxide battery, and a lithium iron phosphate battery.

[0025] Compared with the prior art, this application has the following beneficial effects:

[0026] The lithium metal sheet with an interface protective layer of the present application, on the one hand, introduces additives and plasticizers to improve the lithium ion migration number while promoting the dissociation of lithium salts, and similarly improves the crystallinity of the interface protective layer; on the other hand, the reaction monomer used has a carbonyl functional group structure, which can also promote the dissociation of lithium ions. Therefore, through the synergistic effect between the various components, the effect of promoting uniform deposition of lithium ions is achieved, thereby improving the electrochemical performance of the battery and then achieving stable operation of the battery cell.

[0027] The preparation method of the lithium metal sheet with an interface protection layer of the present application uses a material prepared by a reaction monomer and a cross-linking monomer to be coated on the surface of the lithium metal sheet body to exhibit good electrochemical properties. Since the prepared acrylic polymer has a cross-linked interpenetrating structure, the added additives and plasticizers reduce the crystallinity of the material. At the same time, the structure of the material itself can promote the dissociation of lithium ions, freeing more lithium ions to participate in the electrochemical process, and exhibiting good electrochemical properties macroscopically. In addition, the preparation method is low-cost, simple and easy to operate, and is convenient for large-scale industrial production to realize the use of metallic lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a schematic flow chart of a method for preparing a lithium metal sheet with an interface protection layer in an embodiment of the present application. DETAILED DESCRIPTION

[0030] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the embodiments of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation of the present application should not be construed as any limitation, and the various embodiments can be combined with each other and quoted from each other without contradiction.

[0031] In an embodiment of the present application, a lithium metal sheet with an interface protection layer is provided, comprising: a lithium metal sheet body, and an interface protection layer attached to the surface of the lithium metal sheet body; the material of the interface protection layer comprises: a reactive monomer, a cross-linking monomer, an additive, an initiator, a plasticizer and a lithium salt; wherein the reactive monomer is configured as a structure containing a carbonyl functional group.

[0032] In this embodiment, on the one hand, by introducing additives and plasticizers, the lithium ion migration number is improved while promoting the dissociation of lithium salts, and similarly, the crystallinity of the interface protective layer is improved; on the other hand, the reaction monomer used has a carbonyl functional group structure, which can also promote the dissociation of lithium ions, and then achieve the effect of promoting the uniform deposition of lithium ions through the synergistic effect between the various components, thereby improving the electrochemical performance of the battery, achieving stable operation of the battery cell, and then realizing the use of metallic lithium.

[0033] In this embodiment, it should be noted that, in terms of weight percentage: the molar ratio of the reactive monomer to the cross-linking monomer is (82-95):(5-18); the amount of the initiator added is 1.0-2.0% of the total amount of the reactive monomer and the cross-linking monomer; the amount of the additive added is 8.0-12.0% of the total amount of the reactive monomer and the cross-linking monomer; the mass ratio of the plasticizer to the lithium salt is (1-2):(1-2).

[0034] By adjusting the ratio between reactive monomers, cross-linking monomers, additives, plasticizers, initiators and lithium salts, it is possible to achieve uniform deposition of lithium ions on the surface of lithium metal and improve the electrochemical performance of the battery.

[0035] In some embodiments, the reactive monomer includes at least one of glycidyl methacrylate, glycidyl acrylate, and methyl methacrylate;

[0036] The crosslinking monomer includes at least one of pentaerythritol triacrylate, 1,6-hexanediol diacrylate, and tri(ethylene glycol) diacrylate;

[0037] The initiator is azobisisobutyronitrile; the initiator is also called a free radical initiator, which refers to a class of compounds that are easily decomposed into free radicals (i.e., primary free radicals) by heat, and can be used to initiate free radical polymerization and copolymerization reactions of olefin and diene monomers, and can also be used for cross-linking and curing of unsaturated polyesters and polymer cross-linking reactions.

[0038] The additive includes at least one of succinonitrile, 2-butenenitrile and dicyanoethylene; the use of the additive can enhance the dissociation of lithium salt and improve the lithium ion migration number.

[0039] The plasticizer includes at least one of dioxolane and trioxymethylene. The use of the plasticizer can reduce the glass transition temperature and the crystallinity.

[0040] The lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium perchlorate.

[0041] Please refer to Figure 1 As shown, this embodiment also provides a method for preparing a lithium metal sheet with an interface protection layer, the method comprising the following steps:

[0042] S201: mixing the reaction monomer and the cross-linking monomer, and adding the first solvent, the initiator and the additive to obtain a precursor solution;

[0043] S202: polymerizing the obtained precursor liquid under the protection of a protective gas to obtain a first solution;

[0044] S203: heating the obtained first solution to remove impurities and obtain a polymer;

[0045] S204: dissolving the obtained polymer in a second solvent, and adding a plasticizer and a lithium salt to obtain a second solution;

[0046] S205: dispersing the obtained second solution on the surface of the lithium metal sheet body to obtain a lithium metal sheet with an interface protection layer in a dry environment.

[0047] The material prepared by the method in this embodiment can exhibit good electrochemical performance when coated on the surface of lithium metal.

[0048] Each step is described in detail below:

[0049] S201: mixing the reaction monomer and the cross-linking monomer, and adding the first solvent, the initiator and the additive to obtain a precursor solution;

[0050] In this embodiment, it should be noted that the reaction monomer and the cross-linking monomer are mixed in a certain proportion, and a certain amount of the first solvent, the initiator and the additive are added and mixed evenly to obtain a precursor liquid; wherein the molar ratio of the reaction monomer and the cross-linking monomer is adjusted from 95:5 to 82:18, the amount of the first solvent added is four times the total amount of the reaction monomer and the cross-linking monomer, the amount of the initiator added is 1.5% of the total amount of the reaction monomer and the cross-linking monomer, and the amount of the additive added is 10.0% of the total amount of the reaction monomer and the cross-linking monomer.

[0051] S202: polymerizing the obtained precursor liquid under the protection of a protective gas to obtain a first solution;

[0052] In this embodiment, it should be noted that the precursor liquid obtained in S201 is transferred to a three-necked flask, and air and moisture are removed by passing a protective gas such as Ar gas, and polymerization is carried out under high-speed stirring under heating conditions at 60°C in an oil bath to obtain a first solution.

[0053] S203: removing impurities from the obtained first solution under a heating environment to obtain a polymer;

[0054] In this embodiment, it should be noted that the first solution obtained in S202 is transferred to a convection oven, and is convection-baked at 60°C for 10 hours, and then baked at 50°C under vacuum conditions for 2 hours to remove impurities, thereby obtaining a polymer, which is an acrylic ester polymer.

[0055] S204: dissolving the obtained polymer in a second solvent, and adding a plasticizer and a lithium salt to obtain a second solution;

[0056] In this embodiment, it should be noted that the polymer with a mass fraction of 3.0% obtained in S203 is dissolved in the second solvent, and a plasticizer and a lithium salt are added and mixed uniformly to obtain a second solution.

[0057] S205: dispersing the obtained second solution on the surface of the lithium metal sheet body to obtain a lithium metal sheet with an interface protection layer in a dry environment.

[0058] In this embodiment, it should be noted that the second solution obtained in S204 is evenly dispersed on the surface of the lithium metal sheet body, and then the lithium metal sheet with the interface protection layer is obtained in a dry environment such as vacuum drying.

[0059] Embodiment 1:

[0060] This embodiment 1 provides a method for preparing a lithium metal sheet having an interface protection layer. The specific preparation method is as follows:

[0061] Step 1: Mix 7.107 g of glycidyl methacrylate and 1.491 g of pentaerythritol triacrylate, and then add 34.39 g of ethylene glycol diethyl ether; after mixing evenly, add 0.129 g of azobisisobutyronitrile and 0.860 g of succinonitrile, and mix evenly to obtain a precursor solution;

[0062] Step 2: The precursor solution obtained in step 1 is transferred into a three-necked flask, and then Ar gas is introduced to remove air and moisture, and high-speed stirring is performed under heating conditions of 60° C. in an oil bath to obtain a first solution;

[0063] Step 3: The first solution obtained in step 2 is transferred into a blast oven, and then baked at 60° C. for 10 hours, and then baked at 50° C. for 2 hours under vacuum conditions to remove impurities in the first solution and obtain a polymer;

[0064] Step 4: Weigh 1 g of the polymer and dissolve it in 32.3 g of acetonitrile solution, then add 0.3 g of 1,3-dioxolane and 0.3 g of lithium hexafluorophosphate, stir and dissolve thoroughly to obtain a second solution;

[0065] Step 5: Disperse the second solution obtained in step 4 on the surface of the metallic lithium negative electrode, and obtain a lithium metal sheet containing an artificial interface protective layer after vacuum drying.

[0066] Embodiment 2:

[0067] This embodiment 2 provides a method for preparing a lithium metal sheet with an interface protection layer. The specific preparation method is as follows:

[0068] Step 1: Mix 6.407 g of glycidyl acrylate and 1.491 g of pentaerythritol triacrylate, and then add 31.59 g of ethylene glycol diethyl ether; after mixing evenly, add 0.118 g of azobisisobutyronitrile and 0.790 g of succinonitrile, and mix evenly to obtain a precursor solution;

[0069] Step 2: The precursor solution obtained in step 1 is transferred into a three-necked flask, and then Ar gas is introduced to remove air and moisture, and high-speed stirring is performed under heating conditions of 60° C. in an oil bath to obtain a first solution;

[0070] Step 3: The first solution obtained in step 2 is transferred to a blast oven, and is blast-baked at 60° C. for 10 hours, and then baked at 50° C. under vacuum conditions for another 2 hours to remove impurities in the first solution, thereby obtaining a polymer;

[0071] Step 4: Weigh 1 g of the polymer and dissolve it in 32.3 g of acetonitrile solution, then add 0.3 g of 1,3-dioxolane and 0.3 g of lithium hexafluorophosphate, stir and dissolve thoroughly to obtain a second solution;

[0072] Step 5: Disperse the second solution obtained in step 4 on the surface of the metallic lithium negative electrode, and obtain a lithium metal sheet containing an artificial interface protective layer after vacuum drying.

[0073] Embodiment 3:

[0074] This embodiment 3 provides a method for preparing a lithium metal sheet with an interface protection layer. The specific preparation method is as follows:

[0075] Step 1: Mix 5.006 g of methyl methacrylate and 1.491 g of pentaerythritol triacrylate, and then add 25.99 g of ethylene glycol diethyl ether; after mixing evenly, add 0.097 g of azobisisobutyronitrile and 0.650 g of succinonitrile, and mix evenly to obtain a precursor solution;

[0076] Step 2: The precursor solution obtained in step 1 is transferred into a three-necked flask, Ar gas is introduced to remove air and moisture, and the solution is stirred at high speed under heating conditions at 60° C. in an oil bath to obtain a first solution;

[0077] Step 3: The first solution obtained in step 2 is transferred to a blast oven, and is blast-baked at 60° C. for 10 hours, and then baked at 50° C. under vacuum conditions for another 2 hours to remove impurities in the first solution, thereby obtaining a polymer;

[0078] Step 4: Weigh 1 g of polymer 1 and dissolve it in 32.3 g of acetonitrile solution, then add 0.3 g of 1,3-dioxolane and 0.3 g of lithium hexafluorophosphate, stir and dissolve thoroughly to obtain a second solution;

[0079] Step 5: Disperse the second solution obtained in step 4 on the surface of the metallic lithium negative electrode, and obtain a lithium metal sheet containing an artificial interface protective layer after vacuum drying.

[0080] Comparative Example 1:

[0081] Step 1: Mix 8.599 g of pentaerythritol triacrylate and 34.396 g of ethylene glycol diethyl ether; add 0.129 g of azobisisobutyronitrile and 0.860 g of succinonitrile after mixing evenly, and mix evenly to obtain a precursor solution;

[0082] Step 2: The precursor solution obtained in step 1 was transferred into a three-necked flask, Ar gas was introduced to remove air and moisture, and the solution was stirred at high speed under heating conditions at 60° C. in an oil bath to obtain a first solution;

[0083] Step 3: The first solution was transferred into a forced air oven and was subjected to forced air baking at 60° C. for 10 hours, and then baked at 50° C. under vacuum conditions for 2 hours to remove impurities and obtain a polymer;

[0084] Step 4: Weigh 1 g of polymer 1 and dissolve it in 32.3 g of acetonitrile solution, then add 0.3 g of 1,3-dioxolane and 0.3 g of lithium hexafluorophosphate, stir and dissolve thoroughly to obtain a second solution;

[0085] Step 5: Disperse the second solution on the surface of the metallic lithium negative electrode, and obtain a lithium metal sheet containing an artificial interface protective layer after vacuum drying.

[0086] Comparative Example 2:

[0087] Step 1: Weigh 1 g of polyethylene oxide (Mv=30000) and dissolve it in 32.3 g of acetonitrile solution, then add 0.3 g of 1,3-dioxolane and 0.3 g of lithium hexafluorophosphate, stir and dissolve thoroughly to obtain a second solution;

[0088] Step 2: Disperse the second solution on the surface of the metallic lithium negative electrode, and obtain a lithium metal sheet containing an artificial interface protective layer after vacuum drying.

[0089] Comparative Example 3:

[0090] Step 1: Weigh 1 g of poly(vinylidene fluoride-co-hexafluoropropylene) (Mv=30000) and dissolve it in 32.3 g of N,N-dimethylformamide solution, then add 0.3 g of 1,3-dioxolane and 0.3 g of lithium hexafluorophosphate, stir and dissolve them thoroughly to obtain a second solution;

[0091] Step 2: Disperse the second solution on the surface of the metallic lithium negative electrode, and obtain a lithium metal sheet containing an artificial interface protective layer after vacuum drying.

[0092] Analysis Notes:

[0093] The lithium metal sheets prepared in the above examples 1-3 and comparative examples 1-3 were used to assemble the battery. The positive electrode was ternary 811 (Rongbai Technology), and the separator was Celgard2320 (PP / PE / PP) with a specification of 20um. The positive electrode formula was as follows: active material: conductive agent: binder = 96:2:2; the electrolyte formula was as follows: ethylene carbonate: dimethyl carbonate: methyl ethyl carbonate = 1:1:1, and the molar concentration of LiPF6 was 1.03 mol L -1 , 5% mass fraction FEC.

[0094] The charge and discharge test system is as follows: activation, voltage range 2.8V-4.3V, current density 0.2C / 0.2C; cycle, voltage range 2.8V-4.3V, current density 0.3C / 0.5C, test temperature 25°C, the test results are shown in Table 1 below:

[0095] Table 1 Battery charge and discharge test results

[0096]

[0097] As shown in the battery charge and discharge test results in Table 1, when the lithium metal sheets prepared in Examples 1-3 are used to form batteries, the charge specific capacity, discharge specific capacity, first coulomb efficiency and cycle number @ 80% capacity retention rate are all higher than the battery performance of the lithium metal sheets prepared in Comparative Examples 1-3.

[0098] In metal lithium batteries, Li-Li symmetric batteries are usually used to evaluate the intrinsic stability of the negative electrode. The lithium metal sheets prepared in the above Examples 1-3 and Comparative Examples 1-3 are used to prepare non-blocked symmetric Li-Li batteries. The separator is Celgard2320 (PP / PE / PP) with a specification of 20 um. The electrolyte formula is as follows: ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate = 1:1:1, and the molar concentration of LiPF6 is 1.03 mol L -1, 5% mass fraction FEC. The constant current charge and discharge system is as follows, the current density is 0.5mA cm-2, the surface capacity is 0.5mAh cm-2, and the test results are shown in Table 2 below:

[0099] Table 2 Symmetrical battery test results

[0100] 0.5mA cm*2, 0.5mAh cm*2 short circuit cycles Example 1 216 Example 2 177 Example 3 161 Comparative Example 1 103 Comparative Example 2 98 Comparative Example 3 73

[0101] As shown in the symmetrical battery test results in Table 2, the materials prepared by using the reaction monomer and the cross-linking monomer in Examples 1-3, or the material prepared by using the cross-linking monomer alone in Comparative Example 1, exhibit a higher cycle life (greater than 98 weeks); among them, the test results in Example 1 show that the battery short-circuited after 216 cycles, which is also higher than the test results of other Examples and Comparative Examples.

[0102] The above results show that the material prepared by the method in this embodiment can show good electrochemical performance when coated on the surface of lithium metal. This is because the prepared acrylic polymer has a cross-linked interpenetrating structure, and the added additives and plasticizers reduce the crystallinity of the material. At the same time, the structure of the material itself can promote the dissociation of lithium ions, freeing more lithium ions to participate in the electrochemical process, and showing good electrochemical performance in the macroscopic way.

[0103] It should be understood that the above specific embodiments of the present application are only used to illustrate or explain the principles of the present application, and do not constitute a limitation to the present application. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present application should be included in the protection scope of the present application. In addition, the claims attached to the present application are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A lithium metal sheet having an interface protection layer, characterized in that: include: A lithium metal sheet body, and an interface protection layer attached to the surface of the lithium metal sheet body; The material of the interface protection layer includes: reactive monomers, cross-linking monomers, additives, initiators, plasticizers and lithium salts; Wherein, the reaction monomer is configured to have a structure containing a carbonyl functional group.

2. The lithium metal sheet with an interface protection layer according to claim 1, characterized in that: In weight percent: The molar ratio of the reactive monomer to the crosslinking monomer is (82-95):(5-18); The amount of the initiator added is 1.0-2.0% of the total amount of the reactive monomer and the cross-linking monomer; The additive is added in an amount of 8.0-12.0% of the total amount of the reactive monomer and the cross-linking monomer; The mass ratio of the plasticizer to the lithium salt is (1-2):(1-2).

3. The lithium metal sheet with an interface protection layer according to claim 1, characterized in that: The reactive monomer includes at least one of glycidyl methacrylate, glycidyl acrylate, and methyl methacrylate; And / or, the cross-linking monomer includes at least one of pentaerythritol triacrylate, 1,6-hexanediol diacrylate, and tri(ethylene glycol) diacrylate.

4. The lithium metal sheet with an interface protection layer according to claim 1, characterized in that: The initiator is azobisisobutyronitrile; And / or, the additive includes at least one of succinonitrile, 2-butenenitrile, and dicyanoethylene; And / or, the plasticizer includes at least one of dioxolane and trioxymethylene; And / or, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium perchlorate.

5. A method for preparing a lithium metal sheet having an interface protection layer as claimed in any one of claims 1 to 4, characterized in that: The method comprises the following steps: Mixing the reaction monomer and the cross-linking monomer, and adding the first solvent, the initiator and the additive to obtain a precursor solution; The obtained precursor solution is polymerized under the protection of a protective gas to obtain a first solution; removing impurities from the first solution obtained under a heating environment to obtain a polymer; dissolving the obtained polymer in a second solvent, and adding a plasticizer and a lithium salt to obtain a second solution; The obtained second solution is dispersed on the surface of the lithium metal sheet body to obtain a lithium metal sheet with an interface protection layer in a dry environment.

6. The method for preparing a lithium metal sheet having an interface protection layer according to claim 5, characterized in that: The first solvent comprises at least one of ethylene glycol diethyl ether, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; And / or, the second solvent includes at least one of acetonitrile solution, dimethyl sulfoxide, and tetrahydrofuran.

7. The method for preparing a lithium metal sheet having an interface protection layer according to claim 5, characterized in that: The polymerization conditions are set as: stirring under 50-70° C. oil bath heating conditions.

8. The method for preparing a lithium metal sheet having an interface protection layer according to claim 5, characterized in that: The conditions of the heating environment are set as follows: baking at 50-70° C. for 9-12 hours with forced air, and baking at 40-60° C. for 1-3 hours under vacuum conditions.

9. Use of a lithium metal sheet with an interface protection layer as claimed in any one of claims 1 to 4 and a method for preparing a lithium metal sheet with an interface protection layer as claimed in claims 5 to 8 in a secondary lithium battery.

10. The use according to claim 9, characterized in that: The lithium metal sheet with the interface protection layer is used as the negative electrode; And / or, the secondary lithium battery is selected from any one of a lithium sulfur battery, a lithium nickel cobalt manganese oxide battery, and a lithium iron phosphate battery.

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