An anti-dendrite lithium metal anode, its preparation method and a solid-state battery

Abstract

The present invention provides a dendrite-resistant lithium metal anode, a preparation method thereof, and a solid-state battery. The lithium metal anode of the present invention has a three-layer structure, which sequentially includes: a current collector, an active material layer, and a control layer. The active material layer is a lithium metal and / or lithium alloy layer, and the control layer is a layer with a three-dimensional network structure containing boron nitride nanotubes and a solid electrolyte material. The solid electrolyte material includes a polymer matrix, an inorganic reinforcing material, a lithium salt, a thickening agent, and a hydrophilic additive. In the control layer, the boron nitride nanotubes are nanoscale fibrous structures, and their lattice structure and polarity significantly reduce the energy barrier for lithium surface diffusion, promote the reversible reaction of lithium ions, help achieve uniform lithium ion flux, and inhibit dendrite growth. The solid electrolyte material has high ionic conductivity, and synergistically acts with the boron nitride nanotubes to increase the flexibility of the boron nitride nanotubes and improve the compatibility of the lithium metal anode with various solid-state battery electrolytes.

Description

Technical Field

[0001] The present invention relates to the field of lithium metal batteries, and particularly to a dendrite-resistant lithium metal anode, a preparation method thereof, and a solid-state battery. Background Art

[0002] In recent years, with the increasingly serious problems of fossil energy depletion and environmental pollution, the new energy industry has received more and more attention. Compared with common electrochemical secondary batteries such as lead-acid batteries and nickel-metal hydride batteries, lithium-ion batteries have the advantages of high energy density, long cycle life, and no memory effect. As a new type of lithium battery, lithium metal batteries have a higher specific energy density and theoretical specific capacity, and are expected to be applied to the next generation of high-energy density power batteries. However, due to problems such as the high chemical activity and low melting point of lithium metal, lithium metal also faces many challenges when used as a battery anode: 1. When polarizing lithium metal with a large current during charge and discharge, dendrites will inevitably be generated due to uneven deposition of lithium ions. The gradual growth of lithium dendrites will pierce the separator and cause a short circuit; 2. During the charge and discharge cycle of the battery, a series of side reactions will occur between the electrolyte and the lithium metal anode to form a SEI film, consuming lithium ions. As the reaction progresses, the SEI film gradually thickens, increasing the interfacial resistance and reducing the Coulombic efficiency of the battery; 3. A large amount of heat will be generated during the charge and discharge process of the lithium metal anode, especially when charging and discharging at a high rate, the heat generation increases sharply, which is likely to cause thermal runaway and damage the battery. Therefore, developing a lithium metal battery anode material with good safety performance, low production cost, excellent electrical performance, and strong dendrite resistance has become one of the research hotspots.

[0003] CN119050486A discloses a method for constructing a SEI layer of a lithium metal battery and a lithium metal battery. The preparation method includes dissolving KI, InCl3, and crown ether in water to prepare a crown ether KInI4 filler; adding it to a PEO-based solid electrolyte to prepare a lithium metal battery; constructing a co-grown LiF-LiI-LiInO2 SEI layer through the charge and discharge cycle of the lithium metal battery. This method can significantly reduce the crystallinity of PEO by introducing a co-grown LiF-LiI-LiInO2 SEI layer, significantly improve the ionic conductivity, improve the migration rate of lithium ions, reduce the interfacial impedance, and improve the cycle performance of the battery. However, this method cannot control the thickness of the artificial SEI layer, and its application is limited to polymer solid electrolytes, which has little effect on improving the safety performance of the battery. Therefore, the research on lithium metal batteries needs to be considered from multiple aspects to improve the interfacial strength, safety performance, and cycle performance of the battery. Summary of the Invention

[0004] The present invention aims to solve the following technical problems: During the high-rate charge and discharge process of a battery, lithium metal anode materials are prone to growing lithium dendrites, which can pierce the solid electrolyte or separator, causing a short circuit between the positive and negative electrodes of the battery. In addition, due to the high reactivity of lithium metal, a series of side reactions will occur when it comes into contact with the electrolyte or the electrolyte of a solid-state battery, releasing a large amount of heat. At the same time, a SEI film is generated to inhibit the occurrence of side reactions and protect the negative electrode. As the reaction progresses, the SEI film gradually thickens and ruptures, consuming a large amount of lithium ions. Therefore, a control layer needs to be set on the surface of the lithium metal anode. The control layer has high mechanical strength, inhibits the growth of lithium dendrites and the expansion of lithium metal, has a three-dimensional structure that can store and regulate the deposition and deintercalation of lithium ions, has high thermal conductivity, prevents the battery from experiencing thermal runaway, improves the affinity between lithium metal and various electrolytes, and ensures the consistency of the multi-layer structure of the bipolar solid-state battery.

[0005] The inventors found that: Boron nitride nanotubes (BNNTs) can form various nanostructures, whose properties do not change with size and chirality. Their electronic properties are similar to those of hexagonal boron nitride, with a large bandgap of about 6 eV, which conducts lithium ions but not electrons and has electrical insulation. At the same time, boron nitride nanotubes have high mechanical strength, with a theoretical modulus reaching 1.1 TPa. As a control layer, it has extremely high mechanical strength to inhibit the growth of lithium dendrites. Its thermal stability can promote the conduction process of lithium ions, reduce the interfacial impedance, and facilitate the diffusion of reaction heat. Combining boron nitride nanotubes with a solid electrolyte can build a stable three-dimensional network structure as a control layer. The network structure regulates the deposition of lithium ions, constructs a storage layer for lithium ions, reduces the stress concentration phenomenon caused by the accumulation of lithium ions. The solid electrolyte can improve the lithium ion mobility, increase the ionic conductivity, form a stable lithium ion pathway, and improve the cycle and rate performance of the lithium metal anode in multiple aspects.

[0006] Specifically, the present invention provides a dendrite-resistant lithium metal anode, where the anode includes an active material layer and a control layer disposed on and in contact with the active material layer. Among them, the active material layer is a lithium metal and / or lithium alloy layer; the control layer is a layer with a three-dimensional network structure containing boron nitride nanotubes and a solid electrolyte material, and the boron nitride nanotubes and the solid electrolyte material are uniformly mixed in the control layer; the diameter of the boron nitride nanotubes is 10 - 500 nm, the length is 1 - 100 μm, and the Young's modulus ≥ 0.5 TPa; the solid electrolyte material includes a polymer matrix, an inorganic reinforcing material, a lithium salt, a thickening agent, and a hydrophilic additive; the mass ratio of the polymer substrate, the inorganic reinforcing material, the lithium salt, the thickening agent, and the hydrophilic additive is (1 - 10):(1 - 5):(1 - 5):(1 - 5):(1 - 5); the mass ratio of the boron nitride nanotubes to the solid electrolyte is (0.5 - 5):1.

[0007] Optionally, the thickness of the control layer is 1 - 100 μm and the elastic modulus ≥ 6 GPa.

[0008] Optionally, the boron nitride nanotubes in the control layer include one or a combination of at least two of single-walled boron nitride nanotubes, multi-walled boron nitride nanotubes, and boron nitride nanoribbons.

[0009] The solid electrolyte material in the control layer includes a polymer matrix, an inorganic reinforcing material, a lithium salt, a thickening agent, and a hydrophilic additive;

[0010] Optionally, the polymer matrix includes one or a copolymer or mixture of several of polystyrene-butadiene copolymer, polyethylene oxide, polyvinylidene fluoride, epoxy resin, polyurethane, polyacrylonitrile, polyimide, polycarbonate, polyvinylidene difluoride, copolymer of polyvinylidene difluoride and hexafluoropropylene, polyacrylate, polyaniline, polyethersulfone, cellulose acetate, polylactic acid, polycaprolactone, polytrimethylene carbonate, polyethylene terephthalate, and polylactic acid-glycolic acid;

[0011] Optionally, the inorganic reinforcing material includes one or a mixture of several of alumina, silica, magnesia, titanium dioxide, graphene-based materials, and carbon nanotube-based materials, or a mixture of one or more of such mixtures.

[0012] Optionally, the lithium salt includes one or a combination of several of lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium carbonate, lithium oxalate, lithium hydrogencarbonate, lithium acetate, lithium halide, lithium sulfate, and lithium hydroxide.

[0013] Combining boron nitride nanotubes with a solid electrolyte can construct a stable three-dimensional network-like fiber structure, providing a large number of active sites for the transport of lithium ions, assisting the migration of lithium ions, promoting the dissociation of lithium salts, and improving the ionic conductivity and battery cycle performance.

[0014] Optionally, the thickening agent includes one or more of carboxymethyl cellulose, sesbania gum, sodium starch phosphate, triethyl phosphate, and sodium polyacrylate.

[0015] Optionally, the hydrophilic additive includes one or a combination of several of polyethylene glycol, polyvinyl alcohol, polyoxyethylene ether, carboxylate, sulfonate, sulfate ester salt, phosphate ester salt, imidazole-based ionic liquid, pyridine-based ionic liquid, quaternary ammonium-based ionic liquid, quaternary phosphonium-based ionic liquid, pyrrolidine-based ionic liquid, and piperidine-based ionic liquid.

[0016] Adding a thickening agent and a hydrophilic additive can increase the uniformity and hydrophilicity of the slurry, prevent the control layer slurry from settling, reduce the hydrophilic angle, increase the wettability of the slurry with the lithium metal strip or the carrier layer, and facilitate the process operation.

[0017] Optionally, the mass ratio of the polymer substrate, inorganic reinforcing material, lithium salt, thickening agent and hydrophilic additive is (5 - 10):(2 - 3):(2 - 3):(2 - 3):(1 - 3).

[0018] Optionally, the mass ratio of the boron nitride nanotubes to the solid electrolyte is (0.5 - 2):1.

[0019] Optionally, the active material layer comprises one or a combination of two of a metallic lithium layer and a lithium alloy layer; preferably, the lithium alloy layer comprises an alloy of lithium and one or more of silicon, indium, silver, carbon, magnesium, aluminum, boron, tin, gallium, cobalt, gold, barium, bismuth, calcium, germanium, mercury, platinum, zinc, lead, antimony, cadmium, cobalt.

[0020] Optionally, the thickness of the active material layer is 3 μm - 300 μm, preferably 10 μm - 100 μm.

[0021] Optionally, the thickness ratio of the control layer to the active material layer is (0.001 - 1):1, preferably (0.01 - 0.1):1.

[0022] Optionally, the lithium metal negative electrode further comprises a current collector, and the current collector comprises at least one of copper foil, aluminum foil, stainless steel foil, nickel foil, tin foil, carbon nanotube paper, carbon fiber paper, copper mesh, aluminum mesh, stainless steel mesh, nickel foam, and an organic fiber membrane plated with metal on the surface.

[0023] Another aspect of the present invention provides a method for preparing the dendrite-resistant lithium metal negative electrode as described above, and the method includes:

[0024] (1) Performing plasma cleaning and drying and dehumidifying on the boron nitride nanotubes and the solid electrolyte material;

[0025] (2) Weighing the corresponding proportions of boron nitride nanotubes, polymer matrix and inorganic reinforcing material for mixing, refining the powder particles, and mixing evenly;

[0026] (3) Weighing a certain amount of solvent, first adding the lithium salt, thickening agent and hydrophilic additive according to the corresponding mass fraction, mixing and stirring, and then adding the mixture of boron nitride nanotubes, polymer matrix and inorganic reinforcing material obtained in step (2), mixing and stirring to obtain a uniformly viscous slurry;

[0027] (4) Setting the slurry obtained in step (3) on the surface of the active material layer to form a uniform coating, and drying to obtain the dendrite-resistant lithium metal negative electrode.

[0028] Optionally, the gas used for the plasma cleaning in step (1) comprises one or a combination of two of hydrogen, oxygen, nitrogen, argon, helium, etc.

[0029] Optionally, the plasma cleaning time described in step (1) is 3 - 5 min.

[0030] The plasma acts on the powder, which can effectively change the physical and chemical properties of the powder, increase the hydrophilicity of the powder surface, or improve the wettability of the powder particle surface, enhance the interfacial compatibility of the powder particles in the medium, and make the particles easily dispersed in water or organic compounds.

[0031] Optionally, the drying and dehumidifying temperature described in step (1) is 60 - 100 °C, and the drying time is 1 - 5 h.

[0032] Optionally, the method for mixing boron nitride nanotubes, polymer matrix and inorganic reinforcing material described in step (2) includes ball milling method, chemical precipitation method, sol - gel method, ultrasonic mixing method, preferably the ball milling method.

[0033] Optionally, the ball milling speed of the ball milling method is 100 - 600 rpm, and the ball milling time is 3 - 6 h.

[0034] Optionally, the solvent described in step (3) includes any one or a combination of at least two of N - methylpyrrolidone, tetrahydrofuran, dimethyl ether, dichloromethane, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, dimethyl sulfate, polyether ketone.

[0035] Optionally, the mass ratio of the lithium salt, thickener, hydrophilic additive to the solvent in step (3) is (1 - 5):(1 - 5):(1 - 5):(85 - 97). If the mass ratio of the lithium salt to the solvent is too small, the ionic conduction performance of the lithium salt cannot be exerted; if the mass ratio of the lithium salt to the solvent is too large, the lithium salt concentration is too high, affecting the infiltration of the electrolyte; if the mass ratio of the thickener to the solvent is too small, a stable and uniform three - dimensional network structure cannot be formed; if the mass ratio of the thickener to the solvent is too large, the powder is prone to agglomeration; if the mass ratio of the hydrophilic additive to the solvent is too small, the improvement effect on the hydrophilicity of the slurry is small; if the mass ratio of the hydrophilic additive to the solvent is too large, it affects the cycle performance of the battery, preferably (2 - 3):(2 - 3):(1 - 3):(91 - 95).

[0036] Optionally, the mass ratio of the boron nitride nanotubes, polymer matrix, inorganic reinforcing material to the solvent described in step (3) is (0.5 - 2):(0.1 - 2):(0.1 - 1):(95 - 99.3), preferably (0.5 - 1.5):(0.1 - 1):(0.1 - 0.5):(97 - 99.3). If the mass ratio of the boron nitride nanotubes to the solvent is too small, the slurry concentration is low, the three-dimensional network structure of the boron nitride nanotubes is sparse, and its excellent mechanical strength and lithium storage performance cannot be exerted. If the mass ratio of the boron nitride nanotubes to the solvent is too large, the slurry concentration is high, the mechanical strength of the control layer is high and it does not fit well with the lithium metal anode, the fibers are intertwined, increasing the interfacial impedance and affecting the battery cycle performance. If the mass ratio of the polymer substrate material and the inorganic reinforcing material to the solvent is too small, the stability of the three-dimensional network structure is low. If the mass ratio of the polymer matrix, inorganic reinforcing material to the solvent is too large, the solid content of the slurry increases, it is not easy to coat evenly, and it is easy to agglomerate.

[0037] Optionally, the rotation speed of the mixing and stirring of the lithium salt, thickening agent and hydrophilic additive added in step (3) is above 1100 rpm, and the stirring time is 1 - 20 h.

[0038] Optionally, the rotation speed of the mixing and stirring of the boron nitride nanotubes, polymer matrix and inorganic reinforcing material added in step (3) is above 1200 rpm, and the stirring time is 1 - 20 h.

[0039] Optionally, the method of setting the slurry in step (3) on the active material layer described in step (4) includes any one or a combination of at least two of coating, film transfer printing, spraying, spin coating, roll pressing, and infiltration.

[0040] Optionally, the method of setting the coating on the active material layer is the film transfer printing method. The slurry is evenly coated on the surface of the release film, transferred to the surface of the active material layer, and vacuum dried at 50°C - 60°C for 8 - 12 h.

[0041] Another aspect of the present invention provides a solid-state battery, which includes a positive electrode, a negative electrode, and a solid electrolyte disposed between the positive electrode and the negative electrode; wherein, the negative electrode is the anti-dendrite lithium metal negative electrode as described above.

[0042] Optionally, the active material of the positive electrode is any one or a combination of at least two of layered oxides, polyanion-based active materials, lithium-rich oxides, or spinel oxides.

[0043] Optionally, the solid-state battery includes a lithium-sulfur solid-state battery, a bipolar solid-state battery, a sulfide solid-state battery, a polymer solid-state battery, a halide solid-state battery, an oxide solid-state battery, or an organic-inorganic composite solid-state battery.

[0044] Optionally, the solid-state battery is a bipolar solid-state battery, which is composed of n (n = 2 - 20) layers stacked in the structure of "current collector - positive electrode - solid electrolyte - negative electrode - current collector - positive electrode - solid electrolyte - negative electrode" to form a bipolar solid-state battery.

[0045] The present invention has at least one of the following beneficial technical effects:

[0046] (1) A control layer is provided on the surface of the lithium metal negative electrode. The boron nitride nanotubes in the control layer are mixed with the solid electrolyte to form a stable three-dimensional network structure, which can provide extremely high mechanical strength for the negative electrode interface of the lithium metal battery. Moreover, a lithium ion storage channel is provided to regulate the uniform deposition of lithium ions, inhibit the generation and growth of dendrites, and relieve the swelling of lithium metal, thereby improving the cycling performance of the lithium metal battery.

[0047] (2) A control layer is provided on the surface of the lithium metal negative electrode. The boron nitride nanotubes in the control layer have thermal stability and thermal conductivity, ensuring the safety performance during the battery cycling process. It has multiple active sites, adjusts the conduction rate of lithium ions, provides multiple diffusion paths for lithium ions, and reduces the reaction overpotential.

[0048] (3) A control layer is provided on the surface of the lithium metal negative electrode. The control layer acts as an artificial SEI protective layer for the lithium metal negative electrode, isolating the direct contact between lithium and the solid electrolyte, making lithium metal compatible with various solid electrolytes, reducing the occurrence of side reactions, and can be applied to various solid-state batteries.

[0049] (4) The dendrite-resistant lithium metal negative electrode interface is stable, especially suitable for application in solid-state batteries, especially bipolar solid-state batteries. The multi-layer structure of the bipolar solid-state battery ensures cycling stability.

[0050] (5) The preparation method of the dendrite-resistant lithium metal negative electrode is simple, easy to implement, and efficient. Description of the Drawings

[0051] Figure 1 It is a schematic diagram of lithium ion deposition when the dendrite-resistant lithium metal negative electrode of the present invention is applied to a solid-state battery;

[0052] Figure 2 It is a schematic structural diagram of the dendrite-resistant lithium metal negative electrode of the present invention applied to a bipolar solid-state battery;

[0053] Figure 3 It is an SEM image of the boron nitride nanotube fiber structure in the control layer prepared in Example 1;

[0054] Figure 4 It is a topographic image and Young's modulus test image of the control layer prepared in Example 1 under an atomic force microscope;

[0055] Figure 5Cycling test curves of the dendrite-resistant negative electrode in Examples 1, 2, 3 and Comparative Example 1 at a charge-discharge current of 0.3C;

[0056] Among them, 1 - current collector, 2 - positive electrode, 3 - solid electrolyte, 4 - control layer, 5 - active material layer. Detailed implementation manners

[0057] For the convenience of understanding the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0058] Taking the dendrite-resistant lithium metal negative electrode provided by the present invention as an example, its structural schematic diagram is as Figure 1 shown. The dendrite-resistant lithium metal negative electrode includes a control layer 4 and an active material layer 5.

[0059] Figure 2 It is a structural schematic diagram of a bipolar solid-state battery as a whole, including n layers of repeating structural units (2 ≤ n ≤ 20), and each structural unit includes a current collector 1, a positive electrode 2, a solid electrolyte 3, a control layer 4 and an active material layer 5.

[0060] Example 1

[0061] This example provides a dendrite-resistant lithium metal negative electrode, and the negative electrode structure is sequentially stacked in the order of current collector, active material layer, and control layer;

[0062] The control layer includes boron nitride nanotubes with a diameter of 200 nm, a length of 5 μm, and an elastic modulus of 0.6 TPa, polyethylene oxide (PEO), aluminum oxide (Al2O3), lithium hexafluorophosphate (LiPF6), carboxymethyl cellulose (CMC), a hydrophilic additive polyethylene glycol (PEG), and the solvent is N-methylpyrrolidone (NMP). The mass ratio of boron nitride nanotubes, PEO, Al2O3, LiPF6, CMC, PEG, and NMP is 8:5:2:2:1:1:81. The thickness of the control layer is 5 μm, and the Young's modulus is 8 GPa. The active material layer is a 50-μm lithium metal layer, and the current collector is copper foil.

[0063] The preparation method of the dendrite-resistant lithium metal negative electrode includes the following steps:

[0064] (1) Perform nitrogen plasma cleaning on boron nitride nanotubes, PEO, and Al2O3 for 3 min, and dry them in a vacuum drying oven at 80 °C for 3 h;

[0065] (2) Weigh 8 g of boron nitride nanotubes, 5 g of PEO, and 2 g of Al2O3 materials and put them into a ball mill for ball milling at 500 rpm for 3 h to refine and mix the powder particles evenly;

[0066] (3) Weigh 81 g of NMP, add 2 g of LiPF6, 1 g of CMC, and 1 g of PEG, stir at 1100 rpm for 12 h, then add the powder mixture evenly obtained in step (2), and stir at 1200 rpm for 12 h to obtain a uniformly viscous slurry;

[0067] (4) Transfer the slurry in step (3) onto the surface of the active material layer to form a uniform coating, and dry it in vacuum at 50 °C for 8 h, then cool it down to room temperature to obtain the dendrite-resistant lithium metal anode. Assemble the prepared anode into a all-solid-state battery.

[0068] Example 2

[0069] This example provides a dendrite-resistant lithium metal anode, and the anode structure is sequentially laminated in the order of current collector, active material layer, and control layer;

[0070] The control layer includes boron nitride nanotubes with a diameter of 300 nm, a length of 10 μm, and an elastic modulus of 0.8 TPa, styrene-butadiene copolymer (SBR), silicon dioxide (SiO2), lithium bis(fluorosulfonyl)imide (LiFSI), carboxymethyl cellulose (CMC), hydrophilic additive sodium dodecylbenzenesulfonate (SDBS), and the solvent is 1,2-dimethoxyethane (DME). The mass ratio of boron nitride nanotubes, SBR, SiO2, LiFSI, CMC, SDBS, and DME is 9:5:3:2:1:80. The thickness of the control layer is 5 μm, and the Young's modulus is 10 GPa. The active material layer is a 50-μm lithium metal layer, and the current collector is copper foil.

[0071] The preparation method of the dendrite-resistant lithium metal anode includes the following steps:

[0072] (1) Perform nitrogen plasma cleaning on boron nitride nanotubes, SBR, and SiO2 for 3 min, and dry them in a vacuum drying oven at 80 °C for 3 h;

[0073] (2) Weigh 9 g of boron nitride nanotubes, 5 g of SBR, and 3 g of SiO2 materials, put them into a ball mill, and ball mill at 300 rpm for 3 h to refine and mix the powder particles evenly;

[0074] (3) Weigh 80 g of DME, add 3 g of LiFSI, 2 g of CMC, and 1 g of SDBS, stir at 1100 rpm for 12 h, then add the powder mixture evenly obtained in step (2), and stir at 1200 rpm for 12 h to obtain a uniformly viscous slurry;

[0075] (4) Transfer the slurry in step (3) onto the surface of the active material layer to form a uniform coating, and dry it in vacuum at 50 °C for 8 h, then cool it down to room temperature to obtain the dendrite-resistant lithium metal anode. Assemble the prepared anode into a all-solid-state battery.

[0076] Example 3

[0077] This embodiment provides a dendrite-resistant lithium metal anode, and the anode structure is sequentially laminated in the order of current collector, active material layer, and control layer;

[0078] The control layer includes boron nitride nanotubes with a diameter of 500 nm, a length of 20 μm, and an elastic modulus of 1 TPa, polyvinylidene fluoride (PVDF), magnesium oxide (MgO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), triethyl phosphate (TEP), hydrophilic additive 1-methylimidazole chloride, and the solvent is dimethyl carbonate. The mass ratio of boron nitride nanotubes, PVDF, MgO, LiTFSI, TEP, 1-methylimidazole chloride, and dimethyl carbonate is 9:5:3:2:1:80. The thickness of the control layer is 5 μm, and the Young's modulus is 12 GPa. The active material layer is a 50-μm lithium metal layer, and the current collector is copper foil.

[0079] The preparation method of the dendrite-resistant lithium metal anode includes the following steps:

[0080] (1) Perform nitrogen plasma cleaning on boron nitride nanotubes, PVDF, and MgO for 3 min, and dry them in a vacuum drying oven at 80 °C for 3 h;

[0081] (2) Weigh 9 g of boron nitride nanotubes, 5 g of PVDF, and 3 g of MgO materials, put them into a ball mill, and mill them at 500 rpm for 3 h to refine and mix the powder particles evenly;

[0082] (3) Weigh 80 g of dimethyl carbonate, add 3 g of LiTFSI, 2 g of TEP, and 1 g of 1-methylimidazole chloride, stir at 1100 rpm for 12 h, then add the powder evenly mixed in step (2), and stir at 1200 rpm for 12 h to obtain a uniform and viscous slurry;

[0083] Transfer the slurry in step (3) onto the surface of the active material layer to form a uniform coating, dry it in a vacuum at 50 °C for 8 h, and cool it to room temperature to obtain the dendrite-resistant lithium metal anode. Assemble the prepared anode into a all-solid-state battery.

[0084] Example 4

[0085] Compared with Example 1, the difference is only that the mass ratio of boron nitride nanotubes in the slurry is replaced with 30%, and the other conditions remain unchanged.

[0086] Example 5

[0087] Compared with Example 1, the difference is only that the mass ratio of boron nitride nanotubes in the slurry is replaced with 6%, and the other conditions remain unchanged.

[0088] Example 6

[0089] Compared with Example 1, the difference is only that the mass ratio of PEO in the slurry is replaced with 10%, and the other conditions remain unchanged.

[0090] Example 7

[0091] Compared with Example 1, the difference is only that the mass ratio of PEO in the slurry is replaced with 2%, and the other conditions remain unchanged.

[0092] Example 8

[0093] Compared with Example 1, the difference is only that the mass ratio of Al2O3 in the slurry is replaced with 5%, and the other conditions remain unchanged.

[0094] Example 9

[0095] Compared with Example 1, the difference is only that the mass ratio of Al2O3 in the slurry is replaced with 1%, and the other conditions remain unchanged.

[0096] Example 10

[0097] Compared with Example 1, the difference is only that the mass ratio of LiPF6 in the slurry is replaced with 5%, and the other conditions remain unchanged.

[0098] Example 11

[0099] Compared with Example 1, the difference is only that the mass ratio of LiPF6 in the slurry is replaced with 1%, and the other conditions remain unchanged.

[0100] Example 12

[0101] Compared with Example 1, the difference is only that the mass ratio of CMC in the slurry is replaced with 3%, and the other conditions remain unchanged.

[0102] Example 13

[0103] Compared with Example 1, the difference is only that the mass ratio of CMC in the slurry is replaced with 0.5%, and the other conditions remain unchanged.

[0104] Example 12

[0105] Compared with Example 1, the difference is only that the mass ratio of PEG in the slurry is replaced with 3%, and the other conditions remain unchanged.

[0106] Example 13

[0107] Compared with Example 1, the difference is only that the mass ratio of PEG in the slurry is replaced with 0.5%, and the other conditions remain unchanged.

[0108] Example 14

[0109] Compared with Example 1, the difference is only that the thickness of the control layer is replaced with 1 μm, and the other conditions remain unchanged.

[0110] Example 15

[0111] Compared with Example 1, the only difference is that the thickness of the control layer is replaced with 50 μm, and the other conditions remain unchanged.

[0112] Example 16

[0113] Compared with Example 1, the only difference is that the thickness of the active material layer is replaced with 5 μm, and the other conditions remain unchanged.

[0114] Example 17

[0115] Compared with Example 1, the only difference is that the thickness of the active material layer is replaced with 100 μm, and the other conditions remain unchanged.

[0116] Example 18

[0117] Compared with Example 1, the only difference is that the lithium metal strip in the active material layer is replaced with a lithium-magnesium alloy strip, and the other conditions remain unchanged.

[0118] Example 19

[0119] Compared with Example 1, the only difference is that 8 g of boron nitride nanotubes, 5 g of PEO, and 2 g of Al2O3 materials are weighed and mixed using the ultrasonic mixing method, and the other conditions remain unchanged.

[0120] Example 20

[0121] Compared with Example 1, the only difference is that the control layer is set on the active material layer using the coating method, and the control layer slurry is evenly coated on the active material layer at a speed of 25 m / min using a 50-μm coating blade on the coater, and the other conditions remain unchanged.

[0122] Example 21

[0123] Compared with Example 1, the only difference is that the prepared dendrite-resistant negative electrode is used to assemble a bipolar battery.

[0124] Comparative Example 1

[0125] This comparative example provides a all-solid-state battery that directly uses a 50-μm lithium metal strip as the negative electrode.

[0126] Comparative Example 2

[0127] This comparative example provides a all-solid-state battery that directly uses a 50-μm lithium-magnesium alloy strip as the negative electrode.

[0128] Comparative Example 3

[0129] This comparative example provides a all-solid-state battery. Compared with Example 1, boron nitride nanotubes are not added to the dendrite-resistant negative electrode structure, and the other conditions are the same as those in Example 1.

[0130] Comparative Example 4

[0131] This comparative example provides a all-solid-state battery. Compared with Example 1, no solid electrolyte material is added to the dendrite-resistant anode structure, and the other conditions are the same as those in Example 1.

[0132] Comparative Example 5

[0133] This comparative example provides a all-solid-state battery. Compared with Example 1, no polymer matrix is added to the solid electrolyte material in the dendrite-resistant anode structure, and the other conditions are the same as those in Example 1.

[0134] Comparative Example 6

[0135] This comparative example provides a all-solid-state battery. Compared with Example 1, no inorganic reinforcing material is added to the solid electrolyte material in the dendrite-resistant anode structure, and the other conditions are the same as those in Example 1.

[0136] Comparative Example 7

[0137] This comparative example provides a all-solid-state battery. Compared with Example 1, no thickening agent is added to the solid electrolyte material in the dendrite-resistant anode structure, and the other conditions are the same as those in Example 1.

[0138] Comparative Example 8

[0139] This comparative example provides a all-solid-state battery. Compared with Example 1, no hydrophilic additive is added to the solid electrolyte material in the dendrite-resistant anode structure, and the other conditions are the same as those in Example 1.

[0140] Comparative Example 9

[0141] This comparative example provides a all-solid-state battery. Compared with Example 1, no plasma cleaning is performed on the boron nitride nanotubes and the solid electrolyte material in the dendrite-resistant anode structure, and the other conditions are the same as those in Example 1.

[0142] Comparative Example 10

[0143] This comparative example provides a all-solid-state battery. Compared with Example 1, the control layer of the dendrite-resistant anode structure is replaced with a transferred PEO coating, and the other conditions are the same as those in Example 1.

[0144] Comparative Example 11

[0145] This comparative example provides a all-solid-state battery. Compared with Example 1, the control layer of the dendrite-resistant anode structure is replaced with a transferred Al2O3 coating, and the other conditions are the same as those in Example 1.

[0146] Comparative Example 12

[0147] This comparative example provides a all-solid-state battery. Compared with Example 1, the dendrite-resistant anode structure control layer is replaced with a transferred carbon fiber coating, and the other conditions are the same as those in Example 1.

[0148] Comparative Example 13

[0149] This comparative example provides a all-solid-state battery. Compared with Example 1, the boron nitride nanotubes in the dendrite-resistant anode structure control layer are replaced with boron nitride particles with a particle size of 200 nm, and the other conditions are the same as those in Example 1.

[0150] Comparative Example 14

[0151] This comparative example provides a bipolar solid-state battery, and the dendrite-resistant anode is arranged in the same way as in Comparative Example 1.

[0152] Preparation of all-solid-state battery:

[0153] The obtained battery is a mold battery, and the electrode active area is 0.8 cm 2 .

[0154] The preparation method of the solid electrolyte is as follows: Take 100 mg of lithium phosphorus sulfur chlorine-based sulfide (LSPCl) electrolyte, and press it in a Teflon pressing mold at a pressure of 300 MPa to obtain an electrolyte layer;

[0155] The preparation method of the positive electrode is as follows: Mix 20 mg of LiNi 0.8 Co 0.1 Mn 0.1 O2, small-particle-size LSPCl electrolyte, and carbon black evenly at a mass ratio of 75:25:2, and press it in a Teflon pressing mold at a pressure of 300 MPa to obtain a positive electrode plate of the battery;

[0156] The preparation method of the all-solid-state battery is as follows: Press the obtained positive electrode plate on one side of the LSPCl electrolyte at a pressure of 300 MPa, and then press the functional lithium metal negative electrode on the other side of the electrolyte layer at 20 MPa to obtain an all-solid-state battery.

[0157] The preparation method of the bipolar solid-state battery is as follows: Press the obtained positive electrode plate on one side of the solid electrolyte layer at a pressure of 300 MPa, and then press the functional lithium metal negative electrode on the other side of the electrolyte layer to obtain a layer of repeating structural units. Place current collectors between multiple repeating structural units, stack the repeating structural units, and externally apply a pressure of 20 MPa to assemble them into a bipolar solid-state battery.

[0158] Performance test of the negative electrode of the solid-state battery:

[0159] The negative electrodes provided in Examples 1-20 and Comparative Examples 1-12 were respectively assembled into solid-state batteries for cyclic performance testing. The specific testing method was as follows: At 25 °C, constant current charging and discharging were adopted, the charge-discharge voltage range was 2.7-4.3 V, the charge-discharge rate was 0.3C or 2C, the initial capacity of the battery was denoted as C0, and when the battery completed a full charge and discharge cycle, it was recorded as one cycle; charging and discharging were carried out according to the above method, and the capacity of the battery after each cycle was tested until the capacity of the battery reached 80% C0 or the battery short-circuited or the charge-discharge efficiency was lower than 98%, and the number of cycles at this time was recorded.

[0160] The negative electrodes provided in Example 21 and Comparative Example 13 were respectively assembled into bipolar solid-state batteries for cyclic performance testing. The specific testing method was as follows: At 25 °C, constant current charging and discharging were adopted, the charge-discharge voltage range was 5.0-8.5 V, the charge-discharge rate was 0.3C or 2C, the initial capacity of the battery was denoted as C1, and when the battery completed a full charge and discharge cycle, it was recorded as one cycle; charging and discharging were carried out according to the above method, and the capacity of the battery after each cycle was tested until the capacity of the battery reached 80% C1 or the battery short-circuited or the charge-discharge efficiency was lower than 98%, and the number of cycles at this time was recorded.

[0161] Young's modulus test:

[0162] The control layer was set on the lithium metal negative electrode, and the Young's modulus of the negative electrode interface was tested. Using an atomic force microscope, one end of the microcantilever that was extremely sensitive to weak forces was fixed, and there was a tiny tip at the other end. The tip gently contacted the interface. During scanning, the repulsive force between the tip and the interface was controlled to be constant. The microcantilever with the tip would move up and down in the direction perpendicular to the interface corresponding to the equipotential surface of the atomic force between the tip and the interface atoms. By using the optical detection method or the tunneling current detection method, the position changes of the microcantilever corresponding to each point of the scan could be measured, so that the sample morphology could be obtained and the Young's modulus could be calculated.

[0163] The cyclic performance test results of the all-solid-state batteries assembled with the functional lithium metal negative electrodes prepared in Examples 1-21 and Comparative Examples 1-14 are shown in Table 1.

[0164] Table 1 Cyclic performance test results of the battery

[0165]

[0166]

[0167] Analysis results of the cyclic performance test of the battery:

[0168] (1) Comparison between Examples 1-3 and Comparative Example 1

[0169] Examples 1-3 show that adding the control layer of the present invention to the surface of the lithium metal negative electrode improves the cycle performance of the all-solid-state battery. The control layer is composed of boron nitride nanotubes + solid electrolyte. Since the boron nitride material conducts ions, lithium ions are deposited between the bottom of the control layer and the active material layer. Figure 3 The figure shows a 3000-fold magnified SEM image of boron nitride nanotubes. It can be seen from the figure that the boron nitride nanotubes present a fibrous structure, with multiple fibers interwoven together to form a network structure that is relatively loose. Boron nitride nanotubes are combined with solid electrolytes to form a stable network structure that can act as a lithium ion storage layer to alleviate the expansion of lithium metal. The types and combinations of polymer matrices, inorganic reinforcing materials, thickeners, hydrophilic additives, and solvents in the solid electrolyte materials of Examples 1-3 are different. Compared with the use of pure lithium metal strip as the negative electrode in Comparative Example 1, the lithium metal negative electrode with an additional control layer significantly improves the battery's cycle performance at 0.3C and 2C charge and discharge rates. According to Table 1 and Figure 5 According to the data, at a charge and discharge rate of 0.3C, the pure lithium belt can only be cycled 60 times, and the anti-dendritic lithium metal negative electrode can be cycled 224 times; at a charge and discharge rate of 2C, the pure lithium belt can be cycled 30 times, and the anti-dendritic lithium metal negative electrode can be cycled 156 times. Figure 4 This is the morphology of the control layer under an atomic force microscope. The Young's modulus of the control layer is calculated to be 7.772 GPa, which shows that the control layer has an extremely high Young's modulus, which is higher than the Young's modulus of 4 GPa of the original SEI layer of pure lithium metal. It can effectively inhibit the generation and growth of lithium dendrites and improve the cycle performance of the battery.

[0170] (2) Comparison between Example 1 and Examples 4-17

[0171] Examples 4-17 show the effects of changes in the content of boron nitride nanotubes in the control layer and the content of each component material of the solid electrolyte on the cycle life of the all-solid-state battery. From the data in Table 1, it can be seen that when the content of boron nitride nanotubes is too high, the mechanical strength of the control layer increases, but the fit with the lithium negative electrode is not tight, the fiber nanotubes are staggered, and the interface impedance increases; when the content of boron nitride nanotubes is low, the three-dimensional network structure is loose, and the storage of lithium ions is small, all of which will affect the cycle performance of the battery. If the content of each component material of the solid electrolyte is too high or too low, it will affect the stability of the three-dimensional network structure and the mobility of lithium ions, thereby reducing the cycle performance of the battery. In addition, the thickness of the control layer and the thickness of the active material layer should also be precisely controlled. If the thickness of the control layer is too thick, the interface impedance of the lithium metal battery will increase; if the thickness of the control layer is too thin, the protection effect on the lithium negative electrode interface is weak. This shows that the content of each material in the control layer of the present invention and the thickness of the control layer and the active material layer should be adjusted and determined to ensure excellent results.

[0172] (3) Comparison between Example 1 and Examples 19-20

[0173] Examples 19 - 20 illustrate the influence of different processes on the performance of all - solid - state batteries. In Example 19, different powder mixing methods are adopted, and the uniform mixing of solid powders has little influence on the battery cycle performance. In Example 20, the transfer printing method is changed to the coating method. As long as the uniformity of the control layer coated on the active material layer is ensured and the surface tension of the lithium metal strip during drying is controlled, the influence on the battery cycle performance is small.

[0174] (4)Comparison between Example 18 and Comparative Example 2

[0175] Example 18 and Comparative Example 2 illustrate the influence of setting a control layer on the lithium alloy layer on the cycle performance of all - solid - state batteries. The lithium alloy layer is doped with one or more metal elements compared with the pure metal lithium strip, which improves the cycle performance of metallic lithium. From the data in Table 1, after setting the control layer on the alloy layer, the cycle performance of the lithium metal battery is greatly improved. At a charge - discharge rate of 0.3C, the cycle life is increased by 149 cycles, and at a charge - discharge rate of 2C, the cycle life is increased by 116 cycles.

[0176] (5)Comparison between Example 1 and Comparative Examples 3 - 9

[0177] Comparative Examples 3 - 9 illustrate the importance of the constituent materials of the control layer provided by the present invention and the influence of different materials on the cycle performance of all - solid - state batteries. From the data in Table 1, when different control layer materials are missing, the battery cycles all decrease. When only boron nitride nanotubes or solid electrolyte materials exist, the improvement of the battery cycle performance compared with the pure lithium strip is less.

[0178] (6)Comparison between Example 1 and Comparative Examples 10 - 12

[0179] Comparative Examples 10 - 12 illustrate the influence of replacing the control layer materials with polymer materials, inorganic reinforcing materials, and carbon nanofibers on the performance of all - solid - state batteries. The control layer materials provided by the present invention can inhibit the growth of lithium dendrites, relieve the swelling of lithium metal, improve lithium - ion conduction, enhance the interfacial mechanical strength, and set up lithium - ion storage spaces. After replacing the control layer materials, the improvement of the cycle performance of the lithium metal battery is less.

[0180] (7)Comparison between Example 1 and Comparative Example 13

[0181] Example 1 and Comparative Example 13 show the effect of replacing boron nitride nanotubes in the control layer with boron nitride nanoparticles on the cycling performance of all-solid-state batteries. From the data in Table 1, it can be seen that boron nitride nanoparticles have a relatively small improvement in the battery cycling performance. The main reason is that boron nitride nanoparticles are usually two-dimensional flakes or zero-dimensional particles, without the three-dimensional network structure of boron nitride nanotubes. The protective layer prepared from boron nitride nanoparticles has a loose structure, poor uniformity, low mechanical strength, weak ability to inhibit lithium dendrites, and weak effect on improving the uniformity of lithium ion distribution. Therefore, the improvement of the battery cycling performance is limited.

[0182] (8)Comparison between Example 21 and Comparative Example 14

[0183] Example 21 and Comparative Example 14 show the application of the control layer provided by the present invention to bipolar batteries, which improves the cycling performance of bipolar batteries. It can be seen from Table 1 that at a charge-discharge rate of 0.3C, the battery cycle life is increased by 117 cycles, and at a charge-discharge rate of 2C, the battery cycle life is increased by 96 cycles. The control layer reduces the side reactions occurring due to the direct contact between lithium metal and the solid electrolyte, and at the same time improves the consistency of the multi-layer interface. The combined ability to inhibit dendrite growth and regulate lithium ion deposition is improved, and the cycle life improvement effect is obvious.

[0184] According to the disclosure and teachings of the above specification, those skilled in the art to which the present invention pertains can make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. An anti-dendritic lithium metal negative electrode, characterized in that The negative electrode includes an active material layer and a control layer disposed on and in contact with the active material layer; Wherein, the active material layer is a lithium metal and / or lithium alloy layer; The control layer is a layer of a three-dimensional network structure including boron nitride nanotubes and solid electrolyte materials, and the boron nitride nanotubes and the solid electrolyte materials are uniformly mixed in the control layer; The boron nitride nanotube has a diameter of 10-500 nm, a length of 1-100 μm, and an elastic modulus of ≥0.5 TPa; The solid electrolyte material comprises a polymer matrix, an inorganic reinforcing material, a lithium salt, a thickener and a hydrophilic additive; The mass ratio of the polymer matrix, the inorganic reinforcing material, the lithium salt, the thickener and the hydrophilic additive is (1-10): (1-5): (1-5): (1-5): (1-5); The mass ratio of the boron nitride nanotubes to the solid electrolyte material is (0.5-5):

1.

2. The anti-dendritic lithium metal negative electrode according to claim 1, characterized in that The boron nitride nanotubes of the control layer include single-walled boron nitride nanotubes, multi-walled boron nitride nanotubes, and nanoribbon boron nitride, or a combination of at least two thereof; The control layer has a thickness of 1-100 μm and a Young's modulus of ≥6 GPa.

3. The anti-dendritic lithium metal negative electrode according to claim 1 or 2, characterized in that The polymer matrix includes one or more copolymers or mixtures of polystyrene butadiene copolymer, polyethylene oxide, polyvinylidene fluoride, epoxy resin, polyurethane, polyacrylonitrile, polyimide, polycarbonate, polyvinylidene fluoride, polytetrafluoroethylene, copolymer of polyvinylidene fluoride and hexafluoropropylene, polyacrylate, polyaniline, polyether sulfone, cellulose acetate, polylactic acid, polycaprolactone, polytrimethylene carbonate, polyethylene terephthalate and polylactic glycolic acid; The inorganic reinforcing material includes one or more of alumina, silicon dioxide, magnesium oxide, titanium dioxide, graphene, carbon nanotubes, or a mixture of a mixture of alumina, silicon dioxide, magnesium oxide, titanium dioxide, graphene, and carbon nanotubes; The lithium salt includes one or more combinations of lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(fluorosulfonyl imide), lithium bis(trifluoromethanesulfonyl imide), lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium carbonate, lithium oxalate, lithium bicarbonate, lithium acetate, lithium halide, lithium sulfate, and lithium hydroxide; The thickener includes one or more of carboxymethyl cellulose, sesbania gum, sodium starch phosphate, triethyl phosphate, and sodium polyacrylate; The hydrophilic additive includes one or more combinations of polyethylene glycol, polyvinyl alcohol, polyoxyethylene ether, carboxylates, sulfonates, sulfate esters, phosphate esters, imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium ionic liquids, quaternary phosphonium ionic liquids, pyrrolidine ionic liquids, and piperidine ionic liquids.

4. The anti-dendritic lithium metal negative electrode according to claim 1, characterized in that The active material layer includes a metal lithium layer, a lithium alloy layer, or a combination of the two; wherein the lithium alloy layer includes an alloy of lithium and one or more of silicon, indium, silver, carbon, magnesium, aluminum, boron, tin, gallium, cobalt, gold, barium, bismuth, calcium, germanium, mercury, platinum, zinc, lead, antimony, cadmium, and cobalt; The thickness of the active material layer is 3 μm-300 μm; The thickness ratio of the control layer to the active material layer is (0.001-1):

1.

5. The anti-dendritic lithium metal negative electrode according to claim 1, characterized in that The lithium metal negative electrode also includes a current collector, which includes at least one of copper foil, aluminum foil, stainless steel foil, nickel foil, tin foil, carbon nanotube paper, carbon fiber paper, copper mesh, aluminum mesh, stainless steel mesh, nickel foam, and an organic fiber film with a metal plated surface.

6. A method for preparing the anti-dendritic lithium metal negative electrode according to any one of claims 1 to 5, characterized in that: The method comprises: (1) Plasma cleaning and drying of boron nitride nanotubes and solid electrolyte materials; (2) Weigh corresponding proportions of boron nitride nanotubes, polymer matrix and inorganic reinforcement material, mix them, refine the powder particles and mix them evenly; (3) Weighing a certain amount of solvent, adding lithium salt, thickener and hydrophilic additive according to corresponding mass fractions, mixing and stirring, and then adding the mixture of boron nitride nanotubes, polymer matrix and inorganic reinforcing material obtained in step (2), mixing and stirring to obtain a uniform and viscous slurry; (4) The slurry obtained in step (3) is disposed on the surface of the active material layer to form a uniform coating, and then dried to obtain the anti-dendrite lithium metal negative electrode.

7. The method according to claim 6, characterized in that The gas used for plasma cleaning in step (1) includes one or a combination of two of hydrogen, oxygen, nitrogen, argon, and helium; The plasma cleaning time described in step (1) is 3-5 minutes; The drying and dehumidification temperature in step (1) is 60-100°C, and the drying time is 1-5h.

8. The method according to claim 6 or 7, characterized in that: The method for mixing the boron nitride nanotubes, the polymer matrix and the inorganic reinforcing material in step (2) includes ball milling, chemical precipitation, sol-gel and ultrasonic mixing, wherein the ball milling speed of the ball milling method is 100-600 rpm and the ball milling time is 3-6 hours; The solvent in step (3) includes any one of N-methylpyrrolidone, tetrahydrofuran, dimethyl ether, dichloromethane, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, dimethyl sulfate, polyether ketone, or a combination of at least two thereof; The mass ratio of the lithium salt, thickener, hydrophilic additive and solvent in step (3) is (1-5): (1-5): (1-5): (85-97); The mass ratio of the boron nitride nanotubes, polymer matrix, inorganic reinforcing material and solvent in step (3) is (0.5-2): (0.1-2): (0.1-1): (95-99.3); In step (3), lithium salt, thickener and hydrophilic additive are added and mixed at a speed of more than 1100 rpm for 1-20 hours; In step (3), boron nitride nanotubes are added, and the polymer matrix and the inorganic reinforcing material are mixed and stirred at a speed of more than 1200 rpm for a stirring time of 1-20 hours.

9. The method according to claim 6, characterized in that The method of disposing the slurry of step (3) on the active material layer in step (4) includes any one of coating, film transfer, spraying, spin coating, roller pressing, and immersion, or a combination of at least two of them.

10. A solid-state battery, characterized in that: The solid-state battery includes a positive electrode, a negative electrode and a solid electrolyte disposed between the positive electrode and the negative electrode; wherein the negative electrode is the anti-dendritic lithium metal negative electrode as described in any one of claims 1 to 5, and the active material of the positive electrode is any one of layered oxides, polyanion active materials, lithium-rich oxides or spinel oxides, or a combination of at least two thereof; the solid-state battery includes a lithium-sulfur solid-state battery, a bipolar solid-state battery, a sulfide solid-state battery, a polymer solid-state battery, a halide solid-state battery, an oxide solid-state battery, and an organic-inorganic composite solid-state battery.

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