A composite lithium metal anode structure, its preparation method and application

Abstract

This invention provides a composite lithium metal anode structure, its preparation method, and its application. The composite lithium metal anode structure is sheet-like, comprising interconnected photocurable regions and composite lithium metal regions. The photocurable regions are made of a lithiophilic framework material and a photocurable material; the composite lithium metal regions are made of a lithiophilic framework material and lithium metal. The composite lithium metal anode structure provided by this invention effectively suppresses lithium dendrite growth, improves battery cycle stability, enhances battery safety, and reduces manufacturing costs, thus facilitating large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and relates to a lithium metal anode structure, and more particularly to a composite lithium metal anode structure, its preparation method and application. Background Technology

[0002] Over the past two decades, lithium-ion batteries have revolutionized portable electronic devices and have the potential to have a significant impact on automotive electrification. Despite the enormous potential of lithium-ion batteries, the most advanced lithium-ion batteries currently available (such as LiCoO2 / graphite batteries) cannot fully meet the actual needs of automotive electrification, that is, they cannot simultaneously meet the requirements of high energy density, high power density, and long cycle life.

[0003] In recent years, lithium metal has been used by researchers as a negative electrode material for high energy density batteries due to its high specific capacity (3860 mAh / g) and low redox potential (-3.04 Ev, vs. standard hydrogen electrode). However, the lithium metal anode structure has the following problems in preparation and use: (1) During the cycling process of secondary batteries, lithium metal has dendrite growth, infinite volume change and continuous reaction between electrolyte and fresh lithium metal, resulting in extremely poor battery cycle stability and short cycle life; (2) When dendrites continue to grow and pierce the separator, connecting the positive and negative electrodes and causing a short circuit, it will cause safety accidents such as explosion and fire; (3) When using a die to stamp lithium metal anode to manufacture unit electrodes, the soft characteristics of lithium metal will cause burrs formed during stamping to pierce the separator and cause safety accidents; (4) During stamping, the lithium metal skeleton must also be cut into unit electrodes, but considering the strength of the cutting blade of the stamping die, the lithium metal skeleton also has the risk of forming burrs during stamping; (5) During the process of liquid lithium wetting the skeleton, a part of the skeleton area needs to be reserved for welding the tabs.

[0004] To eliminate the technical challenge of lithium dendrite formation, researchers both domestically and internationally have adopted methods primarily in the following four aspects: (1) physically modifying the lithium metal surface by doping, for example, using lithium-aluminum alloys to suppress dendrite formation; (2) coating the lithium metal surface with a protective coating; (3) changing the electrolyte formulation to dissolve dendrites; and (4) using solid electrolytes and employing physical forces to prevent dendrites from piercing the separator. However, various studies over the past decade have yielded no results, dendrites still exist, and short circuits remain difficult to avoid.

[0005] In addition, the common methods for dealing with lithium metal and skeleton burrs are to perform laser punching during the stamping process of lithium metal electrode sheets, or to perform rolling or other processes after stamping to flatten the residual lithium metal in the form of burrs. This results in problems of low cost and low process efficiency.

[0006] Therefore, how to provide a lithium metal anode structure and its preparation method that can effectively suppress lithium dendrite growth, improve battery cycle stability, enhance battery safety, and reduce preparation costs has become an urgent problem for those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a composite lithium metal anode structure, its preparation method, and its application. The composite lithium metal anode structure effectively suppresses lithium dendrite growth, improves the cycle stability of the battery, enhances the safety of battery use, and reduces the preparation cost, which is conducive to large-scale promotion and application.

[0008] To achieve this objective, the present invention employs the following technical solution:

[0009] In a first aspect, the present invention provides a composite lithium metal anode structure, wherein the composite lithium metal anode structure is sheet-like and includes a photocurable region and a composite lithium metal region connected to each other.

[0010] The material of the photocurable region includes a lithiophilic framework material and a photocurable material.

[0011] The composite lithium metal region is made of a lithiophilic framework material and lithium metal.

[0012] The composite lithium metal anode structure provided by this invention uses a lithiophilic framework material as the main structure, which facilitates the uniform injection of lithium metal into the framework in the form of liquid lithium metal during the preparation process. This enables the composite lithium metal anode structure to suppress lithium dendrite growth and provide lithium deposition space, significantly improving the cycle stability of the battery. In addition, the photocurable material in the photocurable region plays a good confinement role for lithium metal in the framework structure, that is, it fixes the range of the composite lithium metal region, so that the lithium content of each anode structure is similar to each other, and thus the capacity of each battery is similar to each other, improving the consistency of the process.

[0013] Preferably, the composite lithium metal anode structure includes a bonding area, a photocuring area, and a composite lithium metal area connected in sequence.

[0014] Preferably, the material of the bonding area includes a lithium-loving framework material.

[0015] The present invention reserves an area in the lithium-loving skeleton material for welding the adapter piece, i.e., the bonding area, which makes it easier to assemble the battery.

[0016] In a second aspect, the present invention provides a method for preparing a composite lithium metal anode structure as described in the first aspect, the method comprising the following steps:

[0017] (1) The surface of the framework material is modified to obtain a lithium-loving framework material;

[0018] (2) A photocurable material is coated and cured on at least one surface of the lithiophilic framework material;

[0019] (3) Melt lithium metal into liquid lithium metal and uniformly coat the liquid lithium metal onto the surface of a lithium-loving framework material, wherein the coating area of ​​the liquid lithium metal does not exceed the coating area of ​​the photocurable material, thereby obtaining a composite lithium metal structure;

[0020] (4) The composite lithium metal structure is stamped into a unit electrode, and the force application area of ​​the stamping is located within the coating area of ​​the photocurable material to obtain a composite lithium metal anode structure.

[0021] The preparation method provided by this invention first prepares a lithiophilic framework material through modification treatment, and then sequentially coats the surface of the obtained lithiophilic framework material with a photocurable material and liquid lithium metal, so that the photocurable material and liquid lithium metal are immersed in the interior of the framework material to form a composite structure. Finally, the negative electrode structure is obtained by stamping process, and the force application area of ​​stamping is located within the coating area of ​​the photocurable material. That is, the cutting blade used by the stamping die acts directly on the photocurable material, avoiding direct cutting of the lithium metal and framework material, thereby preventing lithium metal residue from remaining on the surface of the cutting blade. At the same time, it prevents burrs generated by lithium metal and / or framework material during stamping from piercing the separator and causing a short circuit, improving the safety of battery use and facilitating large-scale promotion and application.

[0022] Preferably, the skeleton material in step (1) includes any one or a combination of at least two of graphene, carbon nanotubes, carbon fibers, carbon paper, carbon cloth, bacterial cellulose, copper, nickel, aluminum, iron, or stainless steel. Typical but non-limiting combinations include combinations of graphene and carbon nanotubes, carbon nanotubes and carbon fibers, carbon fibers and carbon paper, carbon paper and carbon cloth, carbon cloth and bacterial cellulose, bacterial cellulose and copper, copper and nickel, nickel and aluminum, or aluminum and iron.

[0023] Preferably, the modification treatment in step (1) is an electrochemical deposition method, specifically including: placing the framework material and metallic copper as the two electrodes of the electrochemical deposition system in an electrochemical deposition solution, so that the framework material is at the reduction potential and voltage is applied to the two electrodes respectively, controlling the deposition time to obtain a lithiophilic framework material.

[0024] Preferably, the electrochemical deposition solution is prepared by dissolving a copper-containing electrolyte in an acid solution.

[0025] Preferably, the copper-containing electrolyte comprises any one or a combination of at least two of copper sulfate, copper chloride, copper nitrate, copper carbonate, basic copper carbonate, basic copper sulfate, copper acetate, copper oxide, copper bromide, or copper iodide. Typical but non-limiting combinations include combinations of copper sulfate and copper chloride, copper chloride and copper nitrate, copper nitrate and copper carbonate, copper carbonate and basic copper carbonate, basic copper sulfate and copper acetate, copper acetate and copper oxide, copper oxide and copper bromide, and copper bromide and copper iodide.

[0026] Preferably, the acid solution includes any one or a combination of at least two of sulfuric acid solution, hydrochloric acid solution, nitric acid solution, acetic acid solution, carbonic acid solution, bromic acid, hydrobromic acid, or hydroiodic acid. Typical but non-limiting combinations include combinations of sulfuric acid solution and hydrochloric acid solution, combinations of hydrochloric acid solution and nitric acid solution, combinations of nitric acid solution and acetic acid solution, combinations of acetic acid solution and carbonic acid solution, combinations of carbonic acid solution and bromic acid, combinations of bromic acid and hydrobromic acid, and combinations of hydrobromic acid and hydroiodic acid.

[0027] Preferably, the concentration of the copper-containing electrolyte in the electrochemical deposition solution is 0.01-3 mol / L, for example, it can be 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L or 3 mol / L, more preferably 0.1-1 mol / L, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] Preferably, the H in the acid solution + The concentration is 0.01-3 mol / L, for example, it can be 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L or 3 mol / L, more preferably 0.1-1.5 mol / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] Preferably, the applied voltage range is 0.1-5V, for example, it can be 0.1V, 0.5V, 1V, 1.5V, 2V, 2.5V, 3V, 3.5V, 4V, 4.5V or 5V, more preferably 1-3V, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] Preferably, the deposition time is 0.5-20 min, for example, it can be 0.5 min, 1 min, 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min or 20 min, more preferably 3-10 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0031] Preferably, the photocurable material in step (2) includes an ultraviolet-curable material, and the ultraviolet-curable material is cured by irradiation with ultraviolet light.

[0032] Preferably, the UV-curable material comprises oligomers and / or prepolymers with a viscosity of 10-100 cps, for example, the viscosity may be 10 cps, 15 cps, 20 cps, 25 cps, 30 cps, 35 cps, 40 cps, 45 cps, 50 cps, 55 cps, 60 cps, 65 cps, 70 cps, 75 cps, 80 cps, 85 cps, 90 cps, 95 cps or 100 cps, more preferably 50-100 cps, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] Preferably, the oligomer is selected from at least one of the group consisting of epoxy groups, urethane groups, acrylate groups, siloxane groups, hydroxyl groups, and acrylic acid derivatives.

[0034] Preferably, the prepolymer is selected from at least one of the group consisting of unsaturated polyester-based materials and polyacrylate-based materials.

[0035] In this invention, the prepolymer may be polyester acrylate, epoxy acrylate, polyurethane acrylate or polyurethane, but is not limited to these.

[0036] Preferably, the oligomers and / or prepolymers are polymerized by mixing with a crosslinking agent and a photoinitiator.

[0037] In this invention, the crosslinking agent can be any conventionally known crosslinking agent without limitation, and examples may be at least one selected from the group consisting of isocyanate-based compounds, epoxy compounds, aziridinyl compounds, acrylate-based compounds (e.g., TMSPA, i.e., 3-(trimethoxysilyl)propyl acrylate), and metal chelate-based compounds.

[0038] In this invention, the photoinitiator can be any conventionally known photoinitiator without limitation, and examples may be selected from benzophenone, acetophenone, chloroacetophenone, diethoxyacetophenone (DEAP), benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoylbenzoic acid, methyl benzoylbenzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthraphenone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloroanthraquinone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane. At least one of the group consisting of {2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one}, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylprop-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-prop-1-one, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1-phenyl-2-hydroxy-2-methylpropanone (HMPP), α-aminoacetophenone, thioxanthone, and 2-ethylanthraquinone (2-ETAQ).

[0039] In some cases, UV-curable materials can be added to the corresponding parts with a pre-selected thickener added as a monomer.

[0040] In this invention, the thickener may be carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, polyvinyl acrylate, or similar substances.

[0041] Preferably, the coating width of the photocurable material in step (2) is 2-5 mm, for example, it can be 2 mm, 2.25 mm, 2.5 mm, 2.75 mm, 3 mm, 3.25 mm, 3.5 mm, 3.75 mm, 4 mm, 4.25 mm, 4.5 mm, 4.75 mm or 5 mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the difference between the coating thickness of the photocurable material and the thickness of the lithiophilic framework material in step (2) is within ±50μm, for example, it can be ±5μm, ±10μm, ±15μm, ±20μm, ±25μm, ±30μm, ±35μm, ±40μm, ±45μm or ±50μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0043] Preferably, the curing time of the photocurable material in step (2) is 3-20s, for example, it can be 3s, 4s, 6s, 8s, 10s, 12s, 14s, 16s, 18s or 20s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the melting and coating of liquid lithium metal in step (3) are carried out independently in an inert gas atmosphere.

[0045] Preferably, the inert gas includes helium and / or argon.

[0046] Preferably, the temperature of the liquid lithium metal in step (3) is 180-500℃, for example, it can be 180℃, 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃, 460℃, 480℃ or 500℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] As a preferred embodiment of the second aspect of the present invention, the preparation method includes the following steps:

[0048] (1) Using a framework material and metallic copper as the two electrodes of an electrochemical deposition system, the framework material is placed in an electrochemical deposition solution. The framework material is brought to a reduction potential, and a voltage of 1-3V is applied to each electrode. The deposition time is controlled to be 3-10 minutes. The surface of the framework material is modified to obtain a lithiophilic framework material. The framework material includes any one or at least two combinations of graphene, carbon nanotubes, carbon fibers, carbon paper, carbon cloth, bacterial cellulose, copper, nickel, aluminum, iron, or stainless steel. The electrochemical deposition solution is prepared by dissolving a copper-containing electrolyte in an acid solution. The copper-containing electrolyte includes any one or at least two combinations of copper sulfate, copper chloride, copper nitrate, copper carbonate, basic copper carbonate, basic copper sulfate, copper acetate, copper oxide, copper bromide, or copper iodide, with a concentration of 0.1-1 mol / L in the electrochemical deposition solution. The acid solution includes any one or at least two combinations of sulfuric acid solution, hydrochloric acid solution, nitric acid solution, acetic acid solution, carbonic acid solution, bromic acid, hydrobromic acid, or hydroiodic acid. + The concentration is 0.1-1.5 mol / L;

[0049] (2) A UV-curable material is coated and cured on at least one side of the lithiophilic framework material; the UV-curable material comprises an oligomer and / or a prepolymer with a viscosity of 10-100 cps, wherein the oligomer is selected from at least one of the group consisting of epoxy groups, urethane groups, acrylate groups, siloxane groups, hydroxyl groups, and acrylic acid derivatives, and the prepolymer is selected from at least one of the group consisting of unsaturated polyester-based materials and polyacrylate-based materials, and the oligomer and / or prepolymer is polymerized by mixing with a crosslinking agent and a photoinitiator; the coating width of the UV-curable material is 2-5 mm, and the difference between the coating thickness and the thickness of the lithiophilic framework material is within ±50 μm, and the curing time is 3-20 s;

[0050] (3) In an atmosphere of helium and / or argon, metallic lithium is melted into liquid metallic lithium at a temperature of 180-500℃, and the liquid metallic lithium is uniformly coated on the surface of a lithiophilic framework material, wherein the coating area of ​​the liquid metallic lithium does not exceed the coating area of ​​the photocurable material, thereby obtaining a composite lithium metal structure.

[0051] (4) The composite lithium metal structure is stamped into a unit electrode, and the force application area of ​​the stamping is located within the coating area of ​​the photocurable material to obtain a composite lithium metal anode structure.

[0052] Thirdly, the present invention provides an application of the composite lithium metal anode structure as described in the first aspect in lithium-ion batteries.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The composite lithium metal anode structure provided by the present invention uses a lithium-loving framework material as the main structure, which makes it easy for lithium metal to be uniformly poured into the framework in the form of liquid lithium metal during the preparation process. This makes the composite lithium metal anode structure have the performance of suppressing lithium dendrite growth and providing lithium deposition space, which significantly improves the cycle stability of the battery.

[0055] (2) The photocurable material in the photocurable region plays a good confinement role for lithium metal in the skeleton structure, that is, it fixes the range of the composite lithium metal region, so that the lithium content of each negative electrode structure is close to each other, and thus the capacity of each battery is close to each other, improving the consistency of the process.

[0056] (3) The preparation method provided by the present invention first prepares a lithiophilic framework material through modification treatment, and then coats the surface of the obtained lithiophilic framework material with a photocurable material and liquid lithium metal in sequence, so that the photocurable material and liquid lithium metal are immersed in the interior of the framework material to form a composite structure. Finally, the negative electrode structure is obtained by stamping process, and the force application area of ​​stamping is located within the coating area of ​​the photocurable material. That is, the cutting blade used by the stamping die acts directly on the photocurable material, avoiding direct cutting of lithium metal and framework material, thereby preventing lithium metal residue on the surface of the cutting blade, and preventing burrs generated by lithium metal and / or framework material during stamping from piercing the separator and causing a short circuit, thus improving the safety of battery use and facilitating large-scale promotion and application. Attached Figure Description

[0057] Figure 1 This is a flowchart of the preparation method of the composite lithium metal anode structure provided in Examples 1-3;

[0058] Figure 2 This is a flowchart of the preparation method of the composite lithium metal anode structure provided in Example 4.

[0059] Wherein: 1-photocuring area; 2-composite lithium metal area; 3-attachment area. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0061] Example 1

[0062] This embodiment provides a composite lithium metal anode structure and its preparation method, the preparation method including the following steps:

[0063] (1) The surface of the nickel foam was cleaned with ethanol. Nickel foam and metallic copper were placed in the electrochemical deposition solution as the two electrodes of the electrochemical deposition system. The nickel foam was brought to its reduction potential, and a voltage of 2V was applied to each electrode. The deposition time was controlled to be 5 minutes to modify the surface of the nickel foam, thus obtaining lithium-loving nickel foam. The electrochemical deposition solution was prepared by dissolving copper sulfate in sulfuric acid solution, and the concentration of copper sulfate was 0.1 mol / L. + The concentration is 0.2 mol / L;

[0064] (2) A layer of UV-curable material is coated on each of the two surfaces approximately 20 mm from the edge of the lithium-loving nickel foam, and cured by UV irradiation for 10 seconds. The UV-curable material comprises ETPTA (ethoxylated trimethylolpropane triacrylate) with a viscosity of 60 cps, TMSPA (3-(trimethoxysilyl)propyl acrylate) as a crosslinking agent, and 2-hydroxy-2-methylphenylacetone as a photoinitiator, and the mass ratio of the three is 10:0.5:0.5. The coating width of the UV-curable material is 3 mm, and the difference between the coating thickness and the thickness of the lithium-loving nickel foam is within ±30 μm.

[0065] (3) In an argon atmosphere, metallic lithium is melted into liquid metallic lithium at a temperature of 210°C, and the liquid metallic lithium is uniformly coated on the surface of lithium-loving nickel foam, and the coating area of ​​the liquid metallic lithium does not exceed the coating area of ​​the ultraviolet curing material, thereby obtaining a composite lithium metal structure.

[0066] (4) The composite lithium metal structure is stamped into a unit electrode, and the force application area of ​​the stamping is located within the coating area of ​​the ultraviolet curing material, that is, the cutting blade used by the stamping die directly acts on the ultraviolet curing material to obtain the composite lithium metal anode structure.

[0067] like Figure 1 As shown, this application uses a stamping process to cut uncoated liquid lithium metal foam nickel into splicing areas 3. The remaining part includes an interconnected photocurable area 1 and a composite lithium metal area 2. The material of the photocurable area 1 includes lithium-loving foam nickel and ultraviolet curing material, and the material of the composite lithium metal area 2 includes lithium-loving foam nickel and lithium metal.

[0068] The composite lithium metal anode structure obtained in this embodiment has a length of 90 mm and a width of 50 mm, where the width does not include the length of the bonding area 3.

[0069] Example 2

[0070] This embodiment provides a composite lithium metal anode structure and its preparation method. Except for changing the skeleton material from nickel foam to aluminum foam, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0071] Example 3

[0072] This embodiment provides a composite lithium metal anode structure and its preparation method. Except for changing the skeleton material from nickel foam to carbon fiber cloth, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0073] Example 4

[0074] This embodiment provides a composite lithium metal anode structure and its preparation method. The preparation method, except that no bonding area 3 is reserved during the stamping process (see...), Figure 2 The remaining steps and conditions are the same as in Example 1, so they will not be repeated here.

[0075] Comparative Example 1

[0076] This comparative example provides a lithium metal anode structure and its preparation method. In the preparation method, except that the foamed nickel is replaced with a solid metal copper foil, and step (1) is removed, that is, the photocurable material and liquid metal lithium are directly coated on the surface of the metal copper foil in sequence, the remaining steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0077] Comparative Example 2

[0078] This comparative example provides a lithium metal anode structure and its preparation method. Except for step (2), which is to remove the lithium-loving foam nickel before coating and curing the ultraviolet curing material, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0079] Lithium-ion batteries were prepared using the lithium metal anode structures obtained in Example 1 and Comparative Examples 1-2, respectively. The specific preparation process is as follows:

[0080] (1) The junction area 3 of the lithium metal anode structure is welded to the adapter to obtain a lithium metal anode sheet;

[0081] (2) A positive electrode mixture consisting of 90 wt% positive electrode active material (LiCoO2), 5 wt% Super-P (conductive material), and 5 wt% PVDF (binder) is added to NMP (N-methyl-2-pyrrolidone) as a solvent to prepare a positive electrode slurry. The obtained positive electrode slurry is then coated onto aluminum foil, and after baking, rolling, and cutting, a positive electrode sheet is obtained.

[0082] (3) Use the negative electrode obtained in step (1), the positive electrode obtained in step (2), the polyethylene film (Celgard, thickness: 20 μm) as a separator and the electrolyte (in which LiPF6 is dissolved in 1M in a mixed solvent of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a ratio of 1:2:1) to assemble 10 lithium-ion batteries.

[0083] The cycle test results of lithium-ion batteries assembled using the lithium metal anode structures obtained in Example 1 and Comparative Examples 1-2 are shown in Table 1 below.

[0084] Table 1

[0085]

[0086]

[0087] As shown in Table 1, compared with Comparative Examples 1-2, the lithium-ion battery assembled using the negative electrode structure obtained in Example 1 has better cycle stability and higher battery safety.

[0088] Therefore, the composite lithium metal anode structure provided by this invention uses a lithiophilic framework material as the main structure, which facilitates the uniform injection of lithium metal into the framework in the form of liquid lithium metal during the preparation process. This enables the composite lithium metal anode structure to suppress lithium dendrite growth and provide lithium deposition space, significantly improving the cycle stability of the battery. The photocurable material in the photocurable region plays a good confinement role for lithium metal in the framework structure, fixing the range of the composite lithium metal region. This makes the lithium content of each anode structure similar to each other, and thus makes the capacity of each battery similar to each other, improving the consistency of the manufacturing process.

[0089] Furthermore, the preparation method provided by this invention first prepares a lithiophilic framework material through modification treatment, and then sequentially coats the surface of the obtained lithiophilic framework material with a photocurable material and liquid lithium metal, so that the photocurable material and liquid lithium metal are immersed in the interior of the framework material to form a composite structure. Finally, the negative electrode structure is obtained through a stamping process, and the force application area of ​​the stamping is located within the coating area of ​​the photocurable material. That is, the cutting blade used by the stamping die acts directly on the photocurable material, avoiding direct cutting of the lithium metal and the framework material, thereby preventing lithium metal residue from remaining on the surface of the cutting blade. At the same time, it prevents burrs generated by lithium metal and / or the framework material during stamping from piercing the separator and causing a short circuit, thus improving the safety of battery use and facilitating large-scale promotion and application.

[0090] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a composite lithium metal anode structure, characterized in that, The preparation method includes the following steps: A framework material and metallic copper are placed in an electrochemical deposition solution as the two electrodes of an electrochemical deposition system. The framework material is brought to a reduction potential, and a voltage of 1-3V is applied to the two electrodes. The deposition time is controlled to be 3-10 minutes. The surface of the framework material is modified to obtain a lithiophilic framework material. At least one surface of the lithiophilic framework material is coated and cured with an ultraviolet-cured material. The UV-curable material comprises oligomers and / or prepolymers with a viscosity of 10-100 cps, which are polymerized by mixing with a crosslinking agent and a photoinitiator; the coating width of the UV-curable material is 2-5 mm, and the difference between the coating thickness and the thickness of the lithiophilic framework material is within ±50 μm, and the curing time is 3-20 s. In an atmosphere of helium and / or argon, metallic lithium is melted into liquid metallic lithium at a temperature of 180-500℃, and the liquid metallic lithium is uniformly coated on the surface of the lithiophilic framework material, so that the photocurable material and the liquid metallic lithium are immersed in the interior of the framework material to form a composite structure, and the coating area of ​​the liquid metallic lithium does not exceed the coating area of ​​the UV-curable material, thus obtaining a composite lithium metal structure. The composite lithium metal structure is stamped into a unit electrode, and the force application area of ​​the stamping is located within the coating area of ​​the photocurable material. That is, the cutting blade used by the stamping die acts directly on the photocurable material, and avoids directly cutting the lithium metal and the skeleton material, thus obtaining a composite lithium metal anode structure.

2. The preparation method according to claim 1, characterized in that, The skeleton material includes any one or a combination of at least two of the following: graphene, carbon nanotubes, carbon fibers, carbon paper, carbon cloth, bacterial cellulose, copper, nickel, aluminum, iron, or stainless steel.

3. The preparation method according to claim 1, characterized in that, The electrochemical deposition solution was prepared by dissolving a copper-containing electrolyte in an acid solution; The copper-containing electrolyte includes any one or a combination of at least two of the following: copper sulfate, copper chloride, copper nitrate, copper carbonate, basic copper carbonate, basic copper sulfate, copper acetate, copper oxide, copper bromide, or copper iodide.

4. The preparation method according to claim 3, characterized in that, The acid solution includes any one or a combination of at least two of the following: sulfuric acid solution, hydrochloric acid solution, nitric acid solution, acetic acid solution, carbonic acid solution, bromic acid, or hydroiodic acid.

5. The preparation method according to claim 4, characterized in that, The concentration of the copper-containing electrolyte in the electrochemical deposition solution is 0.01-3 mol / L; the H+ in the acid solution... + The concentration is 0.01-3 mol / L.

6. The preparation method according to claim 1, characterized in that, The oligomer is selected from at least one of the group consisting of epoxy groups, urethane groups, acrylate groups, siloxane groups, and acrylic acid derivatives.

7. The preparation method according to claim 1, characterized in that, The prepolymer is selected from at least one of the group consisting of unsaturated polyester-based materials and polyacrylate-based materials.

8. A composite lithium metal anode structure, characterized in that, The composite lithium metal anode structure was obtained using the preparation method described in any one of claims 1-7.

9. A lithium-ion battery, characterized in that, Including the composite lithium metal anode structure as described in claim 8.

Images