Lithium metal composite material, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a lithium metal composite material, and a preparation method therefor and the use thereof. The lithium metal composite material comprises a lithium-containing core, wherein a modification layer is arranged on the surface of the lithium-containing core; the modification layer comprises carbon nanotubes and a carbon fluoride material; and the carbon nanotubes are interwoven to form a cage-shaped structure, and the carbon fluoride material is present on at least one of the surface of the lithium-containing core, the surface of the cage-shaped structure and pores in the cage-shaped structure. The carbon nanotubes in the modification layer are interwoven to form the cage-shaped structure, which can provide space for the volume change of the lithium-containing core and can also provide support for the carbon fluoride material. Fluorine in the carbon fluoride material reacts with the lithium in the lithium-containing core in situ to generate lithium fluoride, thereby constructing a stable SEI film on the surface of the lithium-containing core. The modification layer constructs a stable electron transport network while modifying the surface of the lithium-containing core, thereby effectively regulating the current density and solving the problem of lithium dendrites generated due to a non-uniform current.

Description

A lithium metal composite material and its preparation method and use Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and in particular to a metal lithium composite material and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are rechargeable secondary batteries widely used in products such as mobile phones, laptops, and new energy vehicles. Lithium metal is one of the preferred negative electrode materials for lithium batteries, but it suffers from volume expansion and lithium dendrites, resulting in a short cycle life and limiting its application in high-energy-density lithium batteries.

[0003] At present, the research on metallic lithium mainly focuses on two aspects: (1) using lithium alloy as negative electrode or composite negative electrode; (2) setting a volume expansion mitigation layer on the surface of metallic lithium. Among them, CN114300654A discloses a uniformly distributed three-dimensional lithium alloy negative electrode and its preparation method, the preparation method comprising the following steps: (1) melting metallic lithium and other metals at high temperature to obtain an alloy material; (2) rolling the alloy material through a roller to obtain an alloy strip, and roughening the alloy strip; (3) polishing the surface of the pure lithium strip and then performing surface roughness treatment; (4) composite rolling the treated alloy strip and the pure lithium strip, embedding the grooves and the protrusions, and then rolling the composite strip to obtain a composite strip; (5) heat treating the rolled composite strip to obtain a uniformly distributed three-dimensional lithium alloy negative electrode material. The three-dimensional lithium alloy negative electrode material prepared by this method significantly improves its cycle life and significantly improves the problem of lithium dendrites, but does not solve the problem of metallic lithium / alloy volume expansion.

[0004] CN116504973A discloses a lithium-carbon material, its preparation method, and a lithium-ion battery. This lithium-carbon material has a cocoon structure comprising a cocoon body formed from a structural carbon material and one or more lithium metal particles contained within the cocoon body. Each lithium metal particle consists of a lithium metal core and an organic conductive layer coated on the core surface. This lithium-carbon material can effectively address the problem of lithium metal dendrites and the volume change of lithium metal during battery charge and discharge. While the organic conductive layer can effectively transport lithium ions and electrons, it cannot stabilize the interface between the lithium metal particles, resulting in poor interface stability during charge and discharge.

[0005] In addition, the current methods for improving the interfacial stability of metallic lithium negative electrodes mainly include the following: (1) inhibiting the corrosion of the electrolyte on the surface of the lithium negative electrode through a surface protective layer, such as CN116565210A; (2) using conductive carbon nanotubes as a carrier of the lithium negative electrode to alleviate the volume expansion problem of metallic lithium, such as CN116504973A; (3) constructing a multi-level pore structure, constructing a multi-level electrolyte and metallic lithium contact interface, and at the same time dividing and confining the metallic lithium in a micron-scale space, which is conducive to the full reaction and deposition of metallic lithium; the multi-level structure provides a three-dimensional path for the conduction of electrons, inhibiting the growth of metallic lithium dendrites, such as CN107732204A.

[0006] Each of these methods has its advantages and disadvantages. For example, a surface protective layer alone cannot effectively address the volume expansion of metallic lithium. Untreated conductive carbon nanotubes hinder the uniform deposition of metallic lithium, leading to the formation and growth of lithium dendrites. Furthermore, the construction of a multi-level pore structure requires complex manufacturing processes and is costly.

[0007] Based on this, how to modify powdered lithium-containing materials such as metallic lithium powder to solve the problems of volume expansion and uneven deposition of metallic lithium, while enhancing the interface stability between metallic lithium particles, has become an urgent problem to be solved.

[0008] Summary of the Invention

[0009] To address the above technical issues, the present invention provides a lithium metal composite material, its preparation method, and its use. The composite material comprises a modified layer comprising carbon nanotubes and a fluorinated carbon material on the surface of a lithium-containing core. This modified layer simultaneously addresses the issues of volume expansion, uneven deposition, and interfacial instability between lithium-containing core particles in powdered lithium-containing materials such as lithium metal powder, significantly improving the cycling performance of the lithium metal composite material.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] In a first aspect, the present invention provides a metal lithium composite material, which includes a lithium-containing core, and a modified layer is provided on the surface of the lithium-containing core; the modified layer includes carbon nanotubes and a fluorinated carbon material, the carbon nanotubes are intertwined to form a cage structure, and the fluorinated carbon material is present at least one position on the surface of the lithium-containing core, on the surface of the cage structure, or in the pores of the cage structure; the mass ratio of the carbon nanotubes to the fluorinated carbon material is 1:(0.1-100).

[0012] In this invention, the modified layer comprises a fluorinated carbon material and carbon nanotubes. The carbon nanotubes intertwine to form a cage-like structure, allowing lithium ion transport, providing space for the volume expansion of the lithium-containing core, and providing support for the fluorinated carbon material. Furthermore, the carbon nanotubes can simultaneously transport lithium ions and electrons, providing dual regulation of current density and lithium ion transport.

[0013] In the present invention, the fluorine in the carbon fluoride material located on the surface of the lithium-containing core, in the portion directly in contact with the lithium-containing core surface, reacts with the active lithium on the lithium-containing core surface to generate lithium fluoride, thereby in-situ constructing a stable SEI. Simultaneously, the carbon in the carbon fluoride material can conduct electrons, effectively regulating the interface state between the lithium-containing cores and the uniform distribution of current density. The carbon fluoride material located on the surface of the cage structure and / or in the pores of the cage structure acts as a fluorine source, reacting with the active lithium during the charge and discharge process to continuously generate lithium fluoride, stabilizing the interface of the composite material. Furthermore, it can also form a conductive network with carbon nanotubes to regulate the uniform deposition of metallic lithium.

[0014] In the present invention, the carbon nanotubes and the fluorinated carbon material work together to create a modified layer that simultaneously addresses the issues of uneven lithium metal deposition, volume expansion of lithium metal, and interface instability between the lithium-containing core and the metal. The metal-lithium composite material exhibits excellent cycling performance and safety. The modified layer can be varied according to the size of the lithium-containing core, enabling modification of the lithium-containing core at nanometer, submicron, and micrometer scales.

[0015] In the present invention, the modified layer constructed of carbon nanotubes and fluorinated carbon materials in a specific mass ratio enables the metal lithium composite material to have good cycling performance. The mass ratio can be 1:0.1, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:2.5, 1:5, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:75, 1:90 or 1:100, including but not limited to the listed values. If the mass ratio is too large, the amount of fluorinated carbon material is small, the SEI constructed on the surface of the lithium-containing core is small, and the effect of interface regulation is limited; if the mass ratio is too small, the amount of carbon nanotubes is small, the volume expansion of the lithium-containing core is limited, and the effect of regulating lithium ions and current density uniformity is poor.

[0016] Optionally, the fluorinated carbon material includes at least one of fluorinated graphite, fluorinated carbon, fluorinated carbon black, fluorinated carbon fiber, fluorinated nanocarbon fiber VGCF, fluorinated graphene microsheets, fluorinated graphene oxide or fluorinated carbon nanotubes.

[0017] Optionally, the atomic ratio of carbon to fluorine in the fluorinated carbon material is greater than 0 and less than 1.25, for example, it can be 0.1, 0.25, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2 or 1.25, including but not limited to the listed point values. The atomic ratio can take into account both the in situ construction of a complete SEI and the regulation of electron transport, and is preferably 0.5-1.

[0018] Optionally, the size of the carbon fluoride material is 1 nm to 50 μm, preferably a nanoscale carbon fluoride material with a size of 3 nm to 500 nm, more preferably 5 to 300 nm. It should be noted that the nanoscale in the nanoscale carbon fluoride material only requires that the size in at least one of the three-dimensional directions is nanoscale.

[0019] As a preferred technical solution of the present invention, the mass ratio of the carbon nanotubes to the fluorinated carbon material is 1:(0.5-50), preferably 1:(1-20).

[0020] Optionally, the lithium-containing core comprises metallic lithium powder and / or lithium alloy powder, with an average particle size of 1-100 μm, preferably 10-50 μm.

[0021] Optionally, the alloying elements in the lithium alloy powder include at least one of tin, gold, barium, bismuth, calcium, germanium, platinum, lead, antimony, silver, boron, magnesium, indium, gallium, aluminum, or zinc. During lithium extraction from the metal-lithium composite material, the alloying elements remain in place and do not participate, thereby improving the stability of the core. The alloying elements have an affinity for lithium, which can regulate the uniform deposition of the metallic lithium during deposition.

[0022] Optionally, based on the mass of the metal lithium composite material being 100%, the mass fraction of the core in the metal lithium composite material is greater than 50%, preferably greater than 70%, and more preferably greater than 85%.

[0023] Optionally, the carbon nanotubes are 0.5 μm to 50 μm in length, preferably 1-20 μm in length. If the carbon nanotubes are too short, it is difficult to form a continuous and stable modified layer. If the carbon nanotubes are too long, they are difficult to disperse evenly, resulting in an uneven modified layer.

[0024] Optionally, the number of layers (number of walls) of the carbon nanotubes is less than or equal to 15 layers, preferably 1-10 layers.

[0025] Optionally, the outer diameter of the carbon nanotube is less than 30 nm, preferably 4-20 nm.

[0026] Optionally, the carbon nanotubes contain lithium-phobic elements, and the lithium-phobic elements include at least one of copper, nickel, titanium, chromium, vanadium, cobalt, manganese or iron. In the prior art, the regulation of the deposition of metallic lithium is concentrated on the deposition site where lithium affinity is introduced. In the present invention, the inventors found during the experiment that the use of carbon nanotubes containing a lithium-phobic element modification layer can also achieve the regulation of metallic lithium deposition. The reason is speculated to be: the uneven deposition of metallic lithium is caused by the uneven current density on the surface of the material. Although the lithium-phobic element modification layer cannot induce the uniform deposition of metallic lithium, it has good electronic conductivity, which makes the current density on the surface of the material more uniform, thereby solving the problem of uneven deposition of metallic lithium and the generation and growth of lithium dendrites; further, the composite material composed of the carbon nanotubes and the lithium alloy core constructs a lithium-philic-lithium-phobic gradient from the inside to the outside, regulates the preferential inward deposition of metallic lithium, and improves the structural stability and cycle stability of the metallic lithium composite material.

[0027] Optionally, based on the mass of the carbon nanotubes being 100%, the mass content of the lithium-phobic element is greater than 30%, preferably 50-80%. A lower mass content may limit the uniform deposition of metallic lithium, while a higher mass content may result in a lower gram capacity of the metallic lithium composite.

[0028] Optionally, the thickness of the modified layer ranges from 0.5 μm to 20 μm. A thicker thickness results in a lower metallic lithium content and a lower gram capacity of the metallic lithium composite material. A thinner thickness has limited effect on mitigating core volume expansion, and is preferably 1-10 μm. The thickness of the modified layer can be adjusted based on the mass ratio of the carbon nanotubes to the fluorinated carbon material, thereby simultaneously achieving effective control of ions and electrons and stabilizing the interface between the lithium-containing core.

[0029] Optionally, the modified layer is an interface stabilization layer, which includes a porous elastic skeleton integrally formed of single-walled carbon nanotubes and multi-walled carbon nanotubes and an interface stabilizer composed of the fluorinated carbon material.

[0030] When the interfacial stabilization layer comprises a porous elastic framework integrally formed from single-walled carbon nanotubes and multi-walled carbon nanotubes, the porous elastic framework combines the flexibility of single-walled carbon nanotubes with the rigidity of multi-walled carbon nanotubes, resulting in a stable structure that can accommodate the volume expansion of the lithium-containing core. Furthermore, the porous elastic framework allows for the transport of lithium ions and electrons simultaneously, providing dual regulation of current density and lithium ion transport, enabling the uniform deposition of metallic lithium.

[0031] The interfacial stabilization layer, a composite of single-walled carbon nanotubes, multi-walled carbon nanotubes, and fluorinated carbon materials, simultaneously addresses uneven lithium metal deposition, volume expansion of lithium metal, and interface instability between the lithium-containing core and the lithium-containing core. The metal-lithium composite material exhibits excellent cycling performance and safety. The interfacial stabilization layer can be adjusted based on the size of the lithium-containing core, enabling modification of the lithium-containing core at nanometer, submicrometer, and micrometer scales.

[0032] As a preferred technical solution of the present invention, the mass ratio of the single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated carbon material is 1: (0.05-100): (0.05-100), and the interface stabilization layer constructed by the single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated carbon material of the specific mass ratio has a stable structure and good interface contact, so that the metal lithium composite material has good cycle performance. The mass ratio can be 1: 0.05: 0.05, 1: 0.075: 0.05, 1: 0.1: 0.075, 1: 0.5: 0.5, 1: 1: 1, 1: 2: 5, 1: 5: 3, 1: 10: 5, 1: 20: 10, 1: 30: 50, 1: 40: 60, 1: 50: 50, 1: 60: 30, 1: 70: 80, 1: 90: 90 or 1: 100: 100, etc., including but not limited to the listed point values. Less fluorinated carbon material means less SEI formed on the surface of the lithium-containing core, which is effective for interface regulation but not conducive to improving the interface stability between the lithium-containing cores; less single-walled carbon nanotubes means a looser porous elastic skeleton, which has limited effect on alleviating the volume expansion of the lithium-containing core; more single-walled carbon nanotubes means that due to the greater flexibility of single-walled carbon nanotubes and the denser porous elastic skeleton, the effect of regulating lithium ions and current density uniformity is poor. The ratio is preferably 1:(0.1-50):(0.1-50), and more preferably 1:(0.5-20):(0.5-20).

[0033] Optionally, the length of the single-walled carbon nanotubes is 0.5 μm to 50 μm, preferably 1-20 μm. If the length of the single-walled carbon nanotubes is too short, it is difficult to form a continuous and stable interfacial stabilization layer. If the length of the single-walled carbon nanotubes is too long, it is difficult to disperse evenly, and the interfacial stabilization layer is unevenly distributed on the surface of the lithium-containing core.

[0034] Optionally, the outer diameter of the single-walled carbon nanotube is 1-2 nm.

[0035] Optionally, the number of layers (the number of walls) of the multi-walled carbon nanotubes is greater than or equal to 2 and less than or equal to 15 layers, preferably 2-10 layers.

[0036] Optionally, the outer diameter of the multi-walled carbon nanotubes is less than 30 nm, preferably 4-20 nm.

[0037] Optionally, the multi-walled carbon nanotubes contain a lithium-phobic element, and the lithium-phobic element includes at least one of copper, nickel, titanium, chromium, vanadium, cobalt, manganese or iron. In the prior art, the regulation of the deposition of metallic lithium is concentrated on the deposition site where lithium affinity is introduced. In the present invention, the inventors found during the experiment that the use of multi-walled carbon nanotubes containing a lithium-phobic element modification layer can also achieve the regulation of metallic lithium deposition. The reason is speculated to be: the uneven deposition of metallic lithium is caused by the uneven current density on the surface of the material. Although the lithium-phobic element modification layer cannot induce uniform deposition of metallic lithium, it has good electronic conductivity, which makes the current density on the surface of the material more uniform, thereby solving the problem of uneven deposition of metallic lithium and the generation and growth of lithium dendrites.

[0038] Optionally, based on the mass of the multi-walled carbon nanotubes being 100%, the mass content of the lithium-phobic element is greater than 30%, preferably 50-80%. A lower mass content may limit the uniform deposition of metallic lithium, while a higher mass content may result in a lower gram capacity of the metallic lithium composite.

[0039] Optionally, the thickness of the interfacial stabilization layer is between 0.5 μm and 30 μm. A thicker thickness results in a lower metallic lithium content and a lower gram capacity of the metallic lithium composite material. A thinner thickness has a limited effect on mitigating core volume expansion, and is preferably between 3 and 20 μm. The thickness of the interfacial stabilization layer can be adjusted based on the mass ratio of the single-walled carbon nanotubes, multi-walled carbon nanotubes, and fluorinated carbon material, thereby simultaneously achieving effective control of ions and electrons and stabilizing the interface between the lithium-containing cores.

[0040] In a second aspect, the present invention provides a method for preparing the metal lithium composite material as described in the first aspect, the preparation method comprising the following steps:

[0041] (1) mixing an organic solvent, carbon nanotubes, and a fluorinated carbon material to obtain a mixture;

[0042] (2) mixing the mixture with a lithium-containing powder material and spray drying the mixture to obtain the metal lithium composite material;

[0043] Alternatively, the mixture and the lithium-containing powder material are entangled at a high speed at a rotation speed of 5000 rpm or more to remove the organic solvent to obtain the metal lithium composite material; the organic solvent is inert to the lithium-containing powder material.

[0044] In the present invention, the organic solvent is not specifically limited, as long as it is inert to the lithium metal powder and / or lithium alloy powder, does not undergo violent chemical reactions, and can be used as a solvent. For example, it can be any one of liquid alkanes having 4 to 20 carbon atoms, liquid halogenated hydrocarbons having 4 to 20 carbon atoms, toluene, xylene, liquid paraffin, tetrahydrofuran, N,N-dimethylformamide, or silicone oil, or a combination of at least two thereof.

[0045] Optionally, step (1) includes the following operations: (a) pre-dispersing the carbon nanotubes in an organic solvent, and then adding the fluorinated carbon material to mix to obtain a mixture. Pre-dispersing the carbon nanotubes allows the single-walled carbon nanotubes to be more evenly dispersed, thereby better forming a stable and uniform modified layer with the fluorinated carbon material.

[0046] Optionally, the carbon nanotubes include single-walled carbon nanotubes and multi-walled carbon nanotubes, and step (1) includes the following operations: pre-dispersing the single-walled carbon nanotubes in an organic solvent, and then adding the multi-walled carbon nanotubes and the fluorinated carbon material to mix to obtain a mixture. Pre-dispersing the carbon nanotubes allows the single-walled carbon nanotubes to be more evenly dispersed, thereby better forming a stable and uniform interfacial stabilization layer with the multi-walled carbon nanotubes and the fluorinated carbon material.

[0047] Optionally, the mixing method in step (2) includes at least one of mechanical stirring, ultrasonic dispersion or high-speed winding at a rotation speed of 5000 rpm or above.

[0048] In a third aspect, the present invention provides an electrode comprising the metal lithium composite material described in the first aspect. The electrode may be an electrode made of a pure metal lithium composite material, or a pre-lithiated electrode or composite electrode comprising the metal lithium composite material and graphite or silicon-based materials.

[0049] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0050] 1. By using carbon nanotubes and carbon fluoride materials as a modifying layer to modify the lithium-containing core, the carbon nanotubes are interwoven to form a cage-like structure, which reduces the volume expansion problem of metallic lithium during charging and discharging, while providing support for the carbon fluoride material;

[0051] 2. Carbon nanotubes can conduct electrons and ions simultaneously, regulating lithium ion transmission and current density, effectively solving the problem of uneven lithium metal deposition and avoiding the generation and growth of lithium dendrites, thereby improving the safety and service life of lithium metal composite materials;

[0052] 3. The fluorine in the fluorinated carbon material located on the surface of the lithium-containing core can react with the active lithium in the metallic lithium or lithium alloy to generate lithium fluoride, which can in situ construct a stable SEI film and solve the problem of unstable interface between the lithium-containing cores; at the same time, the carbon in the fluorinated carbon material can improve electron conduction and solve the problem of lithium dendrite generation and growth; the fluorinated carbon material located on the surface of the cage structure and / or in the pores of the cage structure acts as a fluorine source, reacting with the active lithium during the charge and discharge process to continuously generate lithium fluoride, stabilize the interface of the composite material, and jointly construct a conductive network with the carbon nanotubes to regulate the uniform deposition of metallic lithium;

[0053] 4. The carbon nanotubes and the carbon fluoride material cooperate with each other at a specific mass ratio, and the cycle stability of the lithium metal composite material is better than the cycle performance of the lithium metal composite material modified with pure carbon nanotubes or carbon fluoride materials;

[0054] 5. By designing the mass ratio of carbon nanotubes and carbon fluoride materials, the thickness of the modified layer can be adjusted. The thickness of the modified layer, capacity and cycle performance of the lithium metal composite material can be adjusted and customized.

[0055] 6. By constructing a porous elastic skeleton formed by single-walled carbon nanotubes and multi-walled carbon nanotubes, the volume expansion problem of metallic lithium during charging and discharging is alleviated, and the effect is better than that of the porous skeleton formed by single-walled carbon nanotubes or multi-walled carbon nanotubes;

[0056] 7. The porous elastic skeleton can conduct electrons and ions simultaneously, regulate lithium ion transmission and current density, effectively solve the problem of uneven deposition of metallic lithium, avoid the growth of lithium dendrites, and thus improve the safety and service life of the battery;

[0057] 8. The metal lithium composite material comprises single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated carbon materials, and the cycle stability of the metal lithium composite material is better than the cycle performance of the metal lithium composite material modified by any two of single-walled carbon nanotubes, multi-walled carbon nanotubes or fluorinated carbon materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] FIG1 is a SEM image of the lithium metal composite material in Example 2;

[0059] FIG2 is a lithium extraction test curve of Example 1 and Example 2;

[0060] FIG3 is a test curve of symmetrical batteries of Example 1, Example 6 and Example 7;

[0061] FIG4 is a symmetrical battery test curve of Example 2, Example 3, Example 4 and Example 5;

[0062] FIG5 is a test curve of symmetrical batteries of Example 2, Example 8, Example 9 and Example 10;

[0063] FIG6 is a symmetrical battery test curve of Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 5;

[0064] FIG7 is a symmetrical battery test curve of Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5.

[0065] FIG8 is a test curve of symmetrical batteries of Example 12, Example 13 and Example 15;

[0066] FIG9 is a test curve of symmetrical batteries of Example 12, Example 16, and Example 17;

[0067] FIG10 is a symmetrical battery test curve of Example 12, Comparative Example 6, Comparative Example 7, and Comparative Example 8.

[0068] Note: Some discontinuous areas in the test curve are caused by different sampling parameter settings of the test equipment. DETAILED DESCRIPTION

[0069] The present invention will be further described in detail below with reference to the examples. The following examples are only used to explain the principle of the present invention and are not to be construed as limiting the present invention.

[0070] Example 1

[0071] This embodiment provides a metal lithium composite material, the metal lithium composite material comprising metal lithium powder, a surface of the metal lithium powder being provided with a modified layer of multi-walled carbon nanotubes and graphite fluoride in a mass ratio of 1:0.1, the modified layer having a thickness of 20 μm, and the mass fraction of the metal lithium powder being approximately 50%;

[0072] The preparation method of the metal lithium composite material comprises the following steps:

[0073] (1) adding 10 g of multi-walled carbon nanotubes (GT-400, outer diameter 20-30 nm, length 3-12 μm, Shandong Dazhan Nanomaterial Co., Ltd.) and 1 g of fluorinated graphite (Aladdin, F302204, specification or purity: ≥56 wt% F, D90 ≤8 μm) to 120 L of heptane, performing ultrasonic dispersion, and mixing uniformly to obtain a first mixture;

[0074] (2) adding 11 g of passivation metal lithium powder having an average particle size of 10 μm to the mixture, and mixing at a rotation speed of 9000 rpm for 30 min to obtain a second mixture;

[0075] (3) The second mixture was filtered to remove heptane, and then dried at 110° C. under vacuum conditions for 24 hours to obtain the metal lithium composite material.

[0076] Example 2

[0077] This embodiment provides a metal lithium composite material, the metal lithium composite material comprising metal lithium powder, a surface of the metal lithium powder being provided with a modification layer of single-walled carbon nanotubes and fluorinated carbon black in a mass ratio of 1:100, the modification layer having a thickness of 1 μm, and the mass fraction of the metal lithium powder being approximately 90%;

[0078] The preparation method of the metal lithium composite material comprises the following steps:

[0079] (1) 0.1 g of single-walled carbon nanotubes (Article No. 104477, outer diameter 1-2 nm, length 5-30 μm, Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.) and 10 g of fluorinated carbon black (Shanghai Furui Fine Chemical Co., Ltd., fluorine-carbon ratio 1.0, particle size 50-100 nm) were added to 150 L of p-xylene, and the mixture was dispersed at a speed of 9000 rpm and mixed uniformly to obtain a first mixture;

[0080] (2) adding 20.2 g of metallic lithium powder having an average particle size of 50 μm to the first mixture, and mechanically stirring the mixture at a rotation speed of 3000 rpm for 60 min to obtain a second mixture;

[0081] (3) The second mixture was spray-dried at an air inlet temperature of 240° C., an air outlet temperature of 90° C., an atomization pressure of 1.1 MPa, and an injection volume of 180 mL / min to obtain the metal lithium composite material.

[0082] The lithium metal composite material was characterized by SEM, as shown in Figure 1. As can be clearly seen from the figure, the modified layer of the lithium metal composite material includes single-walled carbon nanotubes (tubular material in the figure) and fluorinated carbon black (granular material in the figure). The single-walled carbon nanotubes are interwoven to form a cage-like structure, and the fluorinated carbon black is distributed at least one location on the surface of the lithium-containing core, on the surface of the cage structure, or within the pores of the cage structure.

[0083] The lithium metal composite materials of Examples 1 and 2 were pressed onto copper foam and combined with lithium sheets to form button-type batteries. The lithium extraction capacity was tested at 0.2 mA, and the test curves are shown in Figure 2. As can be seen from Figure 2, the lithium metal composite material of Example 1 had a lithium extraction capacity of 1699.77 mAh / g, while the lithium metal composite material of Example 2 had a lithium extraction capacity of 3337.34 mAh / g. This demonstrates that the capacity of the lithium metal composite material of the present invention is adjustable and customizable.

[0084] Example 3

[0085] Compared with Example 2, the only difference is that the mass ratio of single-walled carbon nanotubes to fluorinated carbon black is replaced with 1:0.5, and the other conditions are the same.

[0086] Example 4

[0087] Compared with Example 2, the only difference is that the mass ratio of single-walled carbon nanotubes to fluorinated carbon black is replaced with 1:20, and the other conditions are the same.

[0088] Example 5

[0089] Compared with Example 2, the only difference is that the mass ratio of single-walled carbon nanotubes to fluorinated carbon black is replaced with 1:50, and the other conditions are the same.

[0090] Example 6

[0091] Compared with Example 1, the only difference is that the multi-walled carbon nanotubes are replaced with copper-plated multi-walled carbon nanotubes (Beijing Dekedaojin Technology Co., Ltd., CNT813, copper content of 60% by mass, outer diameter 8-15 nm, length 50 μm), and the other conditions are the same.

[0092] Example 7

[0093] Compared with Example 1, the only difference is that the multi-walled carbon nanotubes are replaced with nickel-plated multi-walled carbon nanotubes (Beike Nano, HQNANO-CNTs-009-6A, nickel content greater than 60% by mass, outer diameter 8-15 nm, length 50 μm), and the other conditions are the same.

[0094] Example 8

[0095] Compared with Example 2, the only difference is that the metallic lithium powder is replaced by lithium-silver alloy powder (the mass fraction of silver is 1 wt%), and the other conditions are the same.

[0096] Example 9

[0097] Compared with Example 2, the only difference is that the metallic lithium powder is replaced with lithium-boron-silver alloy powder (the mass fraction of boron is 1 wt %, and the mass fraction of silver is 4%), and the other conditions are the same.

[0098] Example 10

[0099] Compared with Example 8, the only difference is that the single-walled carbon nanotubes are replaced by single-walled carbon nanotubes and nickel-plated multi-walled carbon nanotubes (Beike Nano, HQNANO-CNTs-009-6A, nickel content greater than 60% by mass, outer diameter 8-15 nm, length 50 μm) with a mass ratio of 2:1, and the other conditions are the same.

[0100] Comparative Example 1

[0101] Compared with Example 2, the only difference is that the modified layer contains only single-walled carbon nanotubes and does not contain fluorinated carbon black.

[0102] Comparative Example 2

[0103] Compared with Example 2, the only difference is that the modification layer contains only fluorinated carbon black and does not contain single-walled carbon nanotubes.

[0104] Comparative Example 3

[0105] Compared with Example 2, the only difference is that the modified layer includes an organic conductive layer and single-walled carbon nanotubes (lithium carbon material mentioned in CN116504973A in the background art), and does not contain fluorinated carbon black.

[0106] Comparative Example 4

[0107] Compared with Example 2, the only difference is that the modified layer includes single-walled carbon nanotubes and conductive carbon black (product model: MA-EN-CO-01, CLUDE experimental consumables), and does not contain fluorinated carbon black.

[0108] Comparative Example 5

[0109] Compared with Example 2, the only difference is that the metal lithium composite material does not include a modification layer, but only contains metal lithium powder.

[0110] Testing of the performance of metal lithium composite materials:

[0111] The lithium metal composite materials in Examples 1-10 and Comparative Examples 1-5 were pressed onto copper foam to make electrodes, and then assembled into symmetrical cells. The electrolyte was 1M LiTFSIDOL / DME (volume ratio 1:1), and the cycling performance was tested. 2 and 1mAh / cm 2 Under the conditions of , the test results are shown in Table 1. The test cutoff condition is that the overpotential exceeds 1V or a short circuit occurs.

[0112] Table 1

[0113] From Table 1 we can see that:

[0114] (1) The cycling performance of the lithium metal composite material of Example 1 is worse than that of Examples 6 and 7 (the test curve is shown in FIG3 ). This is because the multi-walled carbon nanotubes in Examples 6 and 7 contain a lithium-repelling element modification layer, which not only provides space for the volume expansion of lithium metal, but also has good electronic conductivity of lithium-repelling elements, making the current density on the surface of the material more uniform. The modification effect on lithium metal powder is better than that of the multi-walled carbon nanotubes in Example 1 that do not contain a lithium-repelling element modification layer.

[0115] (2) The cycling performance of the lithium metal composite materials of Examples 3-5 is better than that of Example 2 (the test curve is shown in FIG4 ). This is because the quality of the single-walled carbon nanotubes and the fluorinated carbon black in the modified layer of the lithium metal composite materials of Examples 3-5 is appropriate, and the two cooperate with each other to better solve the problems of volume expansion, uneven deposition, and generation and growth of lithium dendrites of lithium metal than in Example 2.

[0116] (3) The cycle performance of the metal lithium composite materials of Examples 8 and 9 is better than that of Example 2 (the test curve is shown in FIG5 ). This is because the core of Examples 8 and 9 is lithium alloy powder. When the metal lithium is stripped, the alloy elements do not participate in the lithium extraction and remain in place, playing a role in stabilizing the core. When the metal lithium is deposited, the alloy elements have an affinity for lithium and regulate the uniform deposition of the metal lithium.

[0117] (4) The cycle performance of the metal lithium composite material of Example 10 is better than that of Example 2 and Example 8 (the test curve is shown in Figure 5). This is because the core of Example 10 is lithium alloy powder, which induces the inward deposition of metal lithium. The multi-walled carbon nanotubes with a modified layer containing a lithium-phobic element are not affinity to metal lithium, forming a lithium affinity gradient, regulating the inward transmission of lithium ions, and at the same time regulating the uniformity of the current density on the surface. The single-walled carbon nanotubes, nickel-plated multi-walled carbon nanotubes and fluorinated carbon black cooperate with each other to jointly regulate the uniform deposition of metal lithium and the interface stability.

[0118] (5) The cycle performance of the metal lithium composite material of Example 2 is better than that of Comparative Examples 1-5 (the test curves are shown in Figures 6 and 7). This is because the modified layer of the metal lithium composite material in Comparative Example 1 contains only single-walled carbon nanotubes and does not contain fluorinated carbon black. There are only single-walled carbon nanotubes between the metal lithium powder particles, and lithium fluoride is not generated, resulting in an unstable interface. The modified layer of the metal lithium composite material in Comparative Example 2 contains only fluorinated carbon black and does not contain single-walled carbon nanotubes. The modified layer has limited relief on the volume expansion of metal lithium, and the lithium fluoride generated by fluorinated carbon black and active lithium has poor electronic conductivity. , there is no single-walled carbon nanotube to regulate electronic conductivity; Comparative Example 3 is a lithium-carbon material in the prior art. Although it has an organic conductive layer, it only transmits lithium ions and electrons and has no effect on the interface stability between the metal lithium powder particles; in Comparative Example 4, the modified layer of the metal lithium composite material includes single-walled carbon nanotubes and conductive carbon black, but does not contain fluorinated carbon black, and lithium fluoride cannot be generated on the surface of the metal lithium powder to construct the SEI film in situ, and the interface stability between the metal lithium powders is poor; in Comparative Example 5, there is only metal lithium powder without a modified layer, which characterizes the performance of the metal lithium powder itself.

[0119] In summary, the metal lithium composite material provided by the present invention is provided with a modification layer on the surface of the lithium-containing core, and the modification layer includes carbon nanotubes and a fluorinated carbon material. The fluorinated carbon material reacts with the lithium-containing core to generate lithium fluoride, thereby realizing in situ construction of an SEI film, so that the interface between the lithium-containing core particles is relatively stable; the carbon nanotubes are interwoven into a cage-like structure, which effectively alleviates the volume expansion of the lithium-containing core; in addition, the carbon nanotubes and the fluorinated carbon material cooperate with each other to simultaneously regulate lithium ion transmission and electron transmission, effectively solving the problems of volume expansion of the lithium-containing core, uneven deposition of metallic lithium, and generation and growth of lithium dendrites.

[0120] Example 11

[0121] This embodiment provides a metal lithium composite material, the metal lithium composite material comprising metal lithium powder, an interfacial stabilization layer of single-walled carbon nanotubes, multi-walled carbon nanotubes, and fluorinated carbon black in a mass ratio of 1:0.05:0.05 provided on the surface of the metal lithium powder, the interfacial stabilization layer having a thickness of 30 μm, and a mass fraction of the metal lithium powder of approximately 50%;

[0122] The preparation method of the metal lithium composite material comprises the following steps:

[0123] (1) 2 g of single-walled carbon nanotubes (Article No. 104477, outer diameter 1-2 nm, length 5-30 μm, Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.), 0.1 g of multi-walled carbon nanotubes (GT-400, outer diameter 20-30 nm, length 3-12 μm, Shandong Dazhan Nanomaterial Co., Ltd.) and 0.1 g of fluorinated carbon black (Shanghai Furui Fine Chemical Co., Ltd., fluorine-carbon ratio 1.0, particle size 50-100 nm) were added to 200 L of heptane, ultrasonically dispersed, and mixed uniformly to obtain a first mixture;

[0124] (2) adding 2.2 g of metallic lithium powder having an average particle size of 10 μm to the first mixture, and mixing at a rotation speed of 9000 rpm for 30 min to obtain a second mixture;

[0125] (3) The second mixture was filtered to remove heptane, and then dried at 100° C. for 24 hours under vacuum conditions to obtain the metal lithium composite material.

[0126] Example 12

[0127] This embodiment provides a metal lithium composite material, the metal lithium composite material comprising metal lithium powder, an interface stabilization layer of single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphite fluoride in a mass ratio of 1:100:100 provided on the surface of the metal lithium powder, the thickness of the interface stabilization layer being 1 μm, and the mass fraction of the metal lithium powder being approximately 90%;

[0128] The preparation method of the metal lithium composite material comprises the following steps:

[0129] (1) adding 0.01 g of single-walled carbon nanotubes (Article No. 104477, outer diameter 1-2 nm, length 5-30 μm, Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.), 1 g of multi-walled carbon nanotubes (GT-400, outer diameter 20-30 nm, length 3-12 μm, Shandong Dazhan Nanomaterial Co., Ltd.) and 1 g of fluorinated graphite (Aladdin, F302204, specification or purity: ≥56 wt% F, D90 ≤8 μm) to 150 L of p-xylene, dispersing at a high speed of 9000 rpm, and mixing uniformly to obtain a first mixture;

[0130] (2) adding 20.1 g of metallic lithium powder having an average particle size of 50 μm to the first mixture, and mechanically stirring the mixture at a speed of 3000 rpm for 60 min to obtain a second mixture;

[0131] (3) The second mixture was spray-dried at an air inlet temperature of 220° C., an air outlet temperature of 90° C., an atomization pressure of 1.2 MPa, and an injection volume of 150 mL / min to obtain the metal lithium composite material.

[0132] Example 13

[0133] Compared with Example 12, the only difference is that the mass ratio of single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated graphite is replaced with 1:0.5:0.5, and the other conditions are the same.

[0134] Example 14

[0135] Compared with Example 12, the only difference is that the mass ratio of single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated graphite is replaced with 1:20:20, and the other conditions are the same.

[0136] Example 15

[0137] Compared with Example 12, the only difference is that the mass ratio of single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated graphite is replaced with 1:50:50, and the other conditions are the same.

[0138] Example 16

[0139] Compared with Example 12, the only difference is that the mass ratio of single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated graphite is replaced with 1:0.01:0.01, and the other conditions are the same.

[0140] Example 17

[0141] Compared with Example 12, the only difference is that the mass ratio of single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated graphite is replaced with 1:200:200, and the other conditions are the same.

[0142] Example 18

[0143] Compared with Example 12, the only difference is that the multi-walled carbon nanotubes are replaced with nickel-plated multi-walled carbon nanotubes (Beike Nano, HQNANO-CNTs-009-6A, nickel content greater than 60% by mass, outer diameter 8-15 nm, length 50 μm), and the other conditions are the same.

[0144] Example 19

[0145] Compared with Example 12, the only difference is that the metallic lithium powder is replaced by lithium-zinc alloy powder (the mass fraction of zinc is 10 wt%), and the other conditions are the same.

[0146] Example 20

[0147] Compared with Example 12, the only difference is that the metallic lithium powder is replaced by lithium magnesium zinc alloy powder (the mass fraction of magnesium is 2 wt %, and the mass fraction of zinc is 3%), and the other conditions are the same.

[0148] Comparative Example 6

[0149] Compared with Example 12, the only difference is that the interface stabilization layer contains only single-walled carbon nanotubes and multi-walled carbon nanotubes, and does not contain fluorinated graphite.

[0150] Comparative Example 7

[0151] Compared with Example 12, the only difference is that the interface stabilization layer contains only fluorinated graphite and multi-walled carbon nanotubes, and does not contain single-walled carbon nanotubes.

[0152] Comparative Example 8

[0153] Compared with Example 12, the only difference is that the interface stabilization layer contains only fluorinated graphite and single-walled carbon nanotubes, but does not contain multi-walled carbon nanotubes.

[0154] Comparative Example 9

[0155] Compared with Example 12, the only difference is that the fluorinated graphite in the interface stabilization layer is replaced by ordinary graphite.

[0156] Comparative Example 10

[0157] Compared with Example 12, the only difference is that the metal lithium composite material does not include an interface stabilizing layer, but only contains metal lithium powder.

[0158] Comparative Example 11

[0159] Compared with Example 12, the only difference is that the interface stabilization layer contains only fluorinated graphite and does not contain single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0160] Comparative Example 12

[0161] Compared with Example 12, the only difference is that the interface stabilization layer contains only single-walled carbon nanotubes and does not contain fluorinated graphite and multi-walled carbon nanotubes.

[0162] Comparative Example 13

[0163] Compared with Example 12, the only difference is that the interface stabilization layer contains only multi-walled carbon nanotubes and does not contain fluorinated graphite and single-walled carbon nanotubes.

[0164] Testing of the performance of metal lithium composite materials:

[0165] The lithium metal composite materials in Examples 11-20 and Comparative Examples 6-13 were pressed onto copper foam to make electrodes, and then assembled into symmetrical cells. The electrolyte was 1M LiTFSIDOL / DME (volume ratio 1:1), and the cycling performance was tested. 2 and 1mAh / cm 2 Under the conditions of , the test results are shown in Table 2. The test cutoff condition is that the overpotential exceeds 1V or a short circuit occurs.

[0166] Table 2

[0167] From Table 2 we can see that:

[0168] (1) The cycling performance of the lithium metal composite material of Example 12 is worse than that of Examples 13 to 15 (the test curves of Examples 12, 13, and 15 are shown in FIG8 ). This is because the mass ratio of single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphite fluoride in Examples 13 to 15 is more conducive to constructing a stable interface modification layer, and the effect of regulating the volume expansion, uniform deposition, and interface stability between lithium metal powder particles during charge and discharge is better than that of Example 12.

[0169] (2) The cycling performance of the lithium metal composite materials in Examples 16 and 17 is poorer than that in Example 12 (the test curve is shown in FIG9 ). This is because the mass ratios of the single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphite fluoride in Examples 16 and 17 are not within the preferred range of the present invention, and are therefore limited in their effectiveness in solving the problems of volume expansion of lithium metal, uneven deposition, generation and growth of lithium dendrites, and interface stability between lithium metal powder particles.

[0170] (3) The cycling performance of the lithium metal composite material of Example 18 is better than that of Example 12. This is because nickel-plated multi-walled carbon nanotubes are used as one of the components of the interface stabilization layer in Example 18, which has good conductivity, making the surface current density of the material more uniform than that in Example 12, thereby solving the problem of uneven deposition of lithium metal and the generation and growth of lithium dendrites.

[0171] (4) The cycle performance of the metal lithium composite materials of Examples 19 and 20 is better than that of Example 12. This is because the core of Examples 19 and 20 is lithium alloy powder. When the metal lithium is stripped, the alloy elements do not participate in the lithium extraction and remain in place, playing a role in stabilizing the core; when the metal lithium is deposited, the alloy elements have an affinity for lithium and regulate the uniform deposition of the metal lithium;

[0172] (5) The cycle performance of the metal lithium composite material of Example 12 is better than that of Comparative Examples 6-13 (the symmetrical battery test curves of Example 12, Comparative Example 6, Comparative Example 7 and Comparative Example 8 are shown in Figure 10). This is because the interface stabilization layer in Comparative Examples 6-8 and Comparative Examples 11-13 is composed of any one or two of single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated graphite, and the interface stabilization layer of the present invention is not formed (the interface stabilization layer of the present invention includes a porous elastic skeleton and an interface stabilizer integrally formed by single-walled carbon nanotubes and multi-walled carbon nanotubes, and the interface stabilizer includes a fluorinated carbon material, and the fluorinated carbon material is present on the surface of the lithium-containing core, the outer surface, the inner surface and at least one position in the pores of the porous elastic skeleton). The structural stability and the interface stability between the metal lithium powder particles are worse than those in Example 12, and the effect of alleviating the volume expansion of metal lithium, regulating the uniform deposition of metal lithium and inhibiting the growth of lithium dendrites is worse than that of the present invention; Comparative Example 10 only has metal lithium powder and no interface stabilization layer, which characterizes the performance of the metal lithium powder itself.

[0173] In summary, the metal lithium composite material provided by the present invention is provided with an interface stabilization layer on the surface of the lithium-containing core, and the interface stabilization layer includes a porous elastic skeleton and an interface stabilizer integrally formed by single-walled carbon nanotubes and multi-walled carbon nanotubes, and the interface stabilizer includes a fluorinated carbon material, and the fluorinated carbon material is present on the surface of the lithium-containing core, the outer surface, the inner surface and the pores of the porous elastic skeleton. The fluorinated carbon material reacts with the lithium-containing core to generate lithium fluoride, thereby realizing in situ construction of the SEI film, so that the interface between the lithium-containing core particles is relatively stable; the porous elastic skeleton integrally formed by single-walled carbon nanotubes and multi-walled carbon nanotubes alleviates the problem of volume expansion of metal lithium during charging and discharging; the porous elastic skeleton can conduct electrons and ions at the same time, regulate lithium ion transmission and current density, effectively solve the problem of uneven deposition of metal lithium, and avoid the growth of lithium dendrites; single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated carbon materials cooperate with each other to simultaneously regulate lithium ion transmission and electron transmission, effectively solving the problems of volume expansion of the lithium-containing core, uneven deposition of metal lithium, and generation and growth of lithium dendrites.

Claims

1. A lithium metal composite material, characterized in that: The metal lithium composite material includes a lithium-containing core, and a modified layer is provided on the surface of the lithium-containing core; the modified layer includes carbon nanotubes and a fluorinated carbon material, the carbon nanotubes are intertwined to form a cage structure, and the fluorinated carbon material is present at at least one position on the surface of the lithium-containing core, on the surface of the cage structure, or in the pores of the cage structure; the mass ratio of the carbon nanotubes to the fluorinated carbon material is 1:(0.1-100).

2. The lithium metal composite material according to claim 1, wherein: The fluorinated carbon material comprises at least one of fluorinated graphite, fluorinated activated carbon, fluorinated carbon black, fluorinated carbon nanofibers, fluorinated graphene, fluorinated graphene oxide or fluorinated carbon nanotubes; Preferably, the atomic ratio of carbon to fluorine in the fluorinated carbon material is greater than 0 and less than 1.25, preferably 0.5-1; Preferably, the mass ratio of the carbon nanotubes to the fluorinated carbon material is 1:(0.5-50), preferably 1:(1-20).

3. The lithium metal composite material according to claim 1 or 2, characterized in that: The lithium-containing core comprises metallic lithium powder and / or lithium alloy powder, with an average particle size of 1-100 μm, preferably 10-50 μm; Preferably, the alloying elements in the lithium alloy powder include at least one of tin, gold, barium, bismuth, calcium, germanium, platinum, lead, antimony, silver, boron, magnesium, indium, gallium, aluminum or zinc.

4. The lithium metal composite material according to any one of claims 1 to 3, characterized in that: The length of the carbon nanotubes is 0.5 μm to 50 μm, preferably 1-20 μm.

5. The lithium metal composite material according to any one of claims 1 to 4, characterized in that: The number of layers of the carbon nanotubes is less than or equal to 15 layers, preferably 1-10 layers; Preferably, the outer diameter of the carbon nanotubes is less than 30 nm, preferably 1-20 nm.

6. The lithium metal composite material according to any one of claims 1 to 5, characterized in that: The carbon nanotubes contain lithium-phobic elements, and the lithium-phobic elements include at least one of copper, nickel, titanium, chromium, vanadium, cobalt, manganese or iron; Preferably, based on the mass of the carbon nanotubes being 100%, the mass content of the lithium-phobic element is greater than 30%, preferably 50-80%.

7. The lithium metal composite material according to any one of claims 1 to 6, characterized in that: The thickness of the modified layer is between 0.5 μm and 20 μm, preferably 1-10 μm; Preferably, based on the mass of the metal lithium composite material being 100%, the mass fraction of the lithium core in the metal lithium composite material is 50% or more, preferably 70% or more, and more preferably 85% or more.

8. The lithium metal composite material according to any one of claims 1 to 7, characterized in that: The modified layer is an interface stabilization layer, which includes a porous elastic skeleton and an interface stabilizer integrally formed by single-walled carbon nanotubes and multi-walled carbon nanotubes. The interface stabilizer includes the fluorinated carbon material, which is present on the surface of the lithium-containing core, the outer surface, the inner surface and at least one position in the pores of the porous elastic skeleton.

9. The lithium metal composite material according to claim 8, characterized in that: The mass ratio of the single-walled carbon nanotubes, multi-walled carbon nanotubes and fluorinated carbon material is 1:(0.05-100):(0.05-100), preferably 1:(0.1-50):(0.1-50), and more preferably 1:(0.5-20):(0.5-20).

10. The metal lithium composite material according to claim 8 or 9, characterized in that: The length of the single-walled carbon nanotubes is 0.5 μm to 50 μm, preferably 1-20 μm; The number of layers of the multi-walled carbon nanotubes is greater than or equal to 2 and less than or equal to 15 layers, preferably 2-10 layers; Preferably, the outer diameter of the multi-walled carbon nanotubes is less than 30 nm, preferably 4-20 nm.

11. The lithium metal composite material according to any one of claims 8 to 10, characterized in that: The multi-walled carbon nanotubes contain lithium-phobic elements, and the lithium-phobic elements include at least one of copper, nickel, titanium, chromium, vanadium, cobalt, manganese or iron; Preferably, based on 100% of the mass of the multi-walled carbon nanotubes, the mass content of the lithium-phobic element is above 30%, preferably 50-80%.

12. A method for preparing the metal lithium composite material according to any one of claims 1 to 11, characterized in that: The preparation method comprises the following steps: (1) mixing an organic solvent, carbon nanotubes, and a fluorinated carbon material to obtain a mixture; (2) mixing the mixture with a lithium-containing powder material and spray drying the mixture to obtain the metal lithium composite material; Alternatively, the mixture and the lithium-containing powder material are entangled at a high speed at a rotation speed of 5000 rpm or more to remove the organic solvent to obtain the metal lithium composite material; the organic solvent is inert to the lithium-containing powder material.

13. The preparation method according to claim 12, characterized in that: Step (1) includes the following operations: Pre-dispersing carbon nanotubes in an organic solvent, and then adding a fluorinated carbon material and mixing to obtain a mixture; Preferably, the mixing in step (2) comprises at least one of mechanical stirring, ultrasonic dispersion or high-speed winding at a rotation speed of 5000 rpm or above.

14. The preparation method according to claim 12, characterized in that: The carbon nanotubes include single-walled carbon nanotubes and multi-walled carbon nanotubes, and step (1) includes the following operations: The single-walled carbon nanotubes are pre-dispersed in an organic solvent, and then the multi-walled carbon nanotubes and the fluorinated carbon material are added and mixed to obtain a mixture.

15. An electrode, characterized in that: The electrode comprises the metal lithium composite material according to any one of claims 1 to 11.

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