A negative electrode material, a preparation method thereof, a lithium ion battery, and an electric device

Abstract

The application provides a negative electrode material and a preparation method thereof, a lithium ion battery and an electric device. The negative electrode material comprises sheet-shaped nanosilicon, carbon nanotubes and amorphous carbon. The sheet-shaped nanosilicon comprises a hole structure, at least part of the carbon nanotubes passes through the hole structure, and the carbon nanotubes and the hole structure are connected by the amorphous carbon. The negative electrode material provided by the application comprises sheet-shaped nanosilicon. The sheet-shaped nanosilicon is a two-dimensional nano structure, which can stabilize the structure of the silicon material, make the expansion uniform, and be beneficial to improving the cycle performance of the battery. The two-dimensional nano structure can be in surface contact with the active material, which is beneficial to improving the rate performance of the battery. The carbon nanotubes pass through the hole structure of the sheet-shaped nanosilicon and are fixed by the amorphous carbon. This can improve the electronic conductivity of the negative electrode material and can also bind the expansion of the silicon material, thereby improving the capacity of the battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of lithium ion batteries, and particularly relates to a negative electrode material and a preparation method thereof, a lithium ion battery and an electric device. BACKGROUND

[0002] At present, most of the negative electrode materials of power batteries use graphite materials, which are difficult to meet market demand. Silicon material, as a new negative electrode material, has become the most potential negative electrode material due to its high theoretical capacity, low lithium intercalation platform and rich resources. However, the silicon material will have large-scale volume expansion during lithium intercalation, which will cause the structure of the silicon material to be pulverized and the stability of the solid electrolyte interface (SEI) to be poor, and finally lead to the reduction of lithium intercalation capacity. In order to alleviate the lithium intercalation scale effect of the silicon material, the silicon material is usually nano-sized to reduce the size of the silicon material to alleviate the lithium intercalation expansion. Although the lithium intercalation of nano-silicon has small strain, the specific surface area of nano-silicon is high, which leads to strong surface activity of the silicon material and easy side reactions with the electrolyte, thereby reducing the capacity of the material. SUMMARY

[0003] In view of the problems in the prior art, the application provides a negative electrode material and a preparation method thereof, a lithium ion battery and an electric device.

[0004] In order to solve the above problems, the application provides the following technical solutions:

[0005] In a first aspect, the application provides a negative electrode material, comprising sheet-shaped nano-silicon, carbon nanotubes and amorphous carbon, the sheet-shaped nano-silicon comprising a pore structure, at least part of the carbon nanotubes penetrating through the pore structure, and the carbon nanotubes and the pore structure being connected by the amorphous carbon.

[0006] In some embodiments, the diameter of the carbon nanotubes is 1 nm-5 nm; and the size of the pore structure is 5 nm-15 nm.

[0007] In some embodiments, the negative electrode material further comprises a coating layer, the coating layer being coated on the surface of the sheet-shaped nano-silicon, the carbon nanotubes and the amorphous carbon; and the coating layer comprises at least one of lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide and aluminum fluoride.

[0008] In some embodiments, the content of the coating layer is 5 w.t.%-15 w.t.% based on the total mass of the negative electrode material; and / or, the thickness of the coating layer is 5 nm-8 nm.

[0009] In some embodiments, the specific surface area of the sheet-shaped nano-silicon is 2 m 2 / g-8 m 2 / g.

[0010] In some embodiments, the flaky nanosilicon comprises silicon grains with a size of 0.5-1.5 nm.

[0011] In some embodiments, the flaky nanosilicon has a thickness of 10-20 nm and a length of 50-250 nm.

[0012] In some embodiments, the flaky nanosilicon has a length to thickness ratio of 2.5-25.

[0013] In some embodiments, the ratio of the total area of the pore structure to the area of the flaky nanosilicon is (1-2):5.

[0014] In a second aspect, the present application provides a preparation method of the negative electrode material according to the first aspect, comprising the following steps:

[0015] S1: obtaining a flaky nanosilicon precursor;

[0016] S2: performing pore-making on the flaky nanosilicon precursor to obtain the flaky nanosilicon;

[0017] S3: mixing the flaky nanosilicon and the carbon nanotube;

[0018] S4: introducing a carbon source into the mixed material to obtain the negative electrode material.

[0019] In some embodiments, the preparation method comprises the following steps:

[0020] S1: in a vacuum environment, adding flaky graphene, metal particles, NaSi and NH4Br into an organic solvent to react, to obtain a flaky nanosilicon precursor;

[0021] S2: adding the obtained flaky nanosilicon precursor into an acid solution to perform acid washing treatment, to obtain the flaky nanosilicon, which comprises the pore structure;

[0022] S3: mixing the above flaky nanosilicon with the carbon nanotube and performing vibration treatment;

[0023] S4: introducing a carbon source into the mixture after vibration treatment to react, the reaction being performed in a protective gas to obtain the negative electrode material.

[0024] In some embodiments, after step S4, further comprising adding one or more of lithium polyacrylate powder, lithium carboxymethyl cellulose powder, lithium meta-aluminate powder, aluminum oxide powder and aluminum fluoride powder into the negative electrode material to perform heating treatment, to obtain a negative electrode material with a coating layer, the coating layer comprising one or more of lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide and aluminum fluoride.

[0025] In some embodiments, the heating treatment is at a temperature of 280-520 DEG C for 30-120 minutes.

[0026] In some embodiments, in step S1, the organic solvent comprises nitrogen benzene and ethylene glycol dimethyl ether.

[0027] In some embodiments, in step S1, the reaction is at a temperature of 180-380 DEG C for 10-40 hours.

[0028] In some embodiments, in step S2, the acid solution comprises a hydrochloric acid solution or a sulfuric acid solution, and / or the pickling treatment is for 1-3 hours.

[0029] In some embodiments, in step S3, the vibration treatment is at a frequency of 18-42 Hz for 1-3 hours.

[0030] In some embodiments, in step S4, the carbon source comprises acetylene and / or methane; the reaction is at a temperature of 600-800 DEG C for 1-5 hours.

[0031] In some embodiments, in step S4, the protective gas comprises at least one of argon, nitrogen and helium, and the protective gas and the carbon source are introduced synchronously or the protective gas is introduced before the carbon source.

[0032] In some embodiments, the flow rate of the carbon source is 20-60 sccm, and the ratio of the flow rate of the protective gas to the flow rate of the carbon source is 0.5-5.

[0033] In a third aspect, the present application provides a lithium ion battery comprising the negative electrode material of the first aspect or the negative electrode material prepared by the preparation method of the second aspect.

[0034] In a fourth aspect, the present application provides an electrical equipment comprising the lithium ion battery of the third aspect.

[0035] The negative electrode material provided by the present application has the following technical effects: the negative electrode material provided by the present application comprises sheet-shaped nanosilicon, the sheet-shaped nanosilicon has a two-dimensional nanostructure, the structure of the silicon material is stable, the expansion is uniform, which is conducive to improving the cycle performance of the battery, the two-dimensional nanostructure can be in surface contact with the active material, which is conducive to improving the rate performance of the battery; the carbon nanotube penetrates the pore structure of the sheet-shaped nanosilicon and is fixed by amorphous carbon, which can improve the electronic conductivity of the negative electrode material and restrain the expansion of the silicon material, thereby improving the capacity of the battery. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention:

[0037] Figure 1 This is a schematic diagram of the structure of the negative electrode material in one embodiment of this application;

[0038] Figure 2 This is a schematic diagram of the electronic conduction path of sheet-like nano-silicon in existing technology;

[0039] Figure 3 This is a schematic diagram of the sheet-like nano-silicon electron conduction path structure in one embodiment of this application.

[0040] Figure labeling: A - sheet-like nano-silicon; B - carbon nanotubes; C - pore structure. Detailed Implementation

[0041] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0042] This invention provides a negative electrode material, see [link to relevant documentation]. Figure 1 The negative electrode material includes sheet-like nano-silicon A, carbon nanotubes B, and amorphous carbon (not shown in the figure). The sheet-like nano-silicon A includes a pore structure C. At least a portion of the carbon nanotubes B pass through the pore structure C on the sheet-like nano-silicon A. The carbon nanotubes B and the pore structure C are connected by the amorphous carbon.

[0043] Specifically, sheet-like nano-silicon refers to two-dimensional planar nano-silicon materials with a small thickness. Sheet-like nano-silicon can be of any shape, including but not limited to curled, unfolded, partially curled, or partially unfolded forms. Sheet-like nano-silicon includes crystalline and amorphous structures. The shape of the pore structure on the sheet-like nano-silicon is not limited, including but not limited to circular, elliptical, rectangular, or other irregular shapes. At least some carbon nanotubes penetrate the pore structure of the sheet-like nano-silicon, including carbon nanotubes penetrating the sheet-like nano-silicon with their two ends on different faces of the two-dimensional sheet-like nano-silicon; and / or one end of the carbon nanotube is in the pore structure of the sheet-like nano-silicon, and the other end is outside the pore structure; and / or both ends of the carbon nanotube are in the pore structure of the sheet-like nano-silicon; and / or both ends of the carbon nanotube penetrate the pore structure of the sheet-like nano-silicon, with their two ends on the same face of the sheet-like nano-silicon. The carbon nanotubes and the pore structure are fixedly connected by amorphous carbon to prevent the carbon nanotubes from moving.

[0044] The negative electrode material provided by the application has the following effects. The negative electrode material provided by the application comprises sheet-shaped nanosilicon. The sheet-shaped nanosilicon has a two-dimensional nano structure, which makes the structure of the silicon material stable and uniform in expansion, and is beneficial to improving the cycle performance of the battery. The two-dimensional nano structure can be in surface contact with the active material, which is beneficial to improving the rate performance of the battery. The carbon nanotube penetrates through the pore structure of the sheet-shaped nanosilicon and is fixed by amorphous carbon. This can improve the electronic conductivity of the negative electrode material and can also bind the expansion of the silicon material, thereby improving the capacity of the battery.

[0045] In some embodiments, the sheet-shaped nanosilicon comprises a curved surface shape and / or a planar shape.

[0046] Specifically, the sheet-shaped nanosilicon in a planar shape is laid flat, which is beneficial to relieving the volume expansion of the silicon material and further improving the cycle performance of the battery. The sheet-shaped nanosilicon in a curved surface shape is curled. Since the sheet-shaped nanosilicon is a two-dimensional nano structure and has a relatively small thickness, it will be in a curved surface shape when subjected to force in the battery. The sheet-shaped nanosilicon in a curved surface shape can better wrap other active materials, improve the compaction density of the electrode sheet, strengthen the conductive network, and further improve the cycle performance of the battery.

[0047] In some embodiments, the diameter of the carbon nanotube B is 1 nm-5 nm, and the size of the pore structure C is 5 nm-15 nm.

[0048] Specifically, the diameter of the carbon nanotube can be, but is not limited to, 1 nm, 2 nm, 3 nm, 4 nm, or 5 nm. The size of the pore structure of the sheet-shaped nanosilicon refers to the distance between the two most distant points on the pattern formed by the pore structure on the sheet-shaped nanosilicon, that is, the maximum dimension of the pattern formed by the pore structure on the sheet-shaped nanosilicon. The shape of the pore structure is not limited in the application and can be circular, elliptical, rectangular, or other irregular patterns. The size of the pore structure can be, but is not limited to, 5 nm, 7 nm, 9 nm, 12 nm, 14 nm, or 15 nm. The diameter of the carbon nanotube and the size of the pore structure in this range can better enable the carbon nanotube to penetrate through the sheet-shaped nanosilicon and better fix the carbon nanotube.

[0049] In some preferred embodiments, the negative electrode material further comprises a coating layer, which is coated on the surface of the sheet-shaped nanosilicon, the carbon nanotube, and the amorphous carbon. The coating layer comprises at least one of lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide, and aluminum fluoride.

[0050] Specifically, the coating layer can be fully coated or partially coated on the surface of the sheet-shaped nanosilicon, carbon nanotube and amorphous carbon; the lithium polyacrylate (PAA-Li), lithium carboxymethyl cellulose (CMC-Li), lithium metaaluminate (LiAlO2), aluminum oxide (Al2O3) and aluminum fluoride (AlF3) are ion conductors, which can improve the electronic conductivity and ionic conductivity of the material, and further improve the capacity of the battery.

[0051] In some embodiments, the content of the coating layer is 5 w.t.%-15 w.t.% based on the total mass of the negative electrode material; and / or, the thickness of the coating layer is 5 nm-8 nm.

[0052] Specifically, the mass content of the coating layer refers to the mass of the coating layer accounting for the total mass of the negative electrode material, and the content of the coating layer can be but is not limited to 5 w.t.%, 6 w.t.%, 7 w.t.%, 8 w.t.%, 9 w.t.%, 10 w.t.%, 11 w.t.%, 12 w.t.%, 13 w.t.%, 14 w.t.%, 15 w.t.%, and the mass content of the coating layer within this range is beneficial to improve the electronic conductivity and ionic conductivity of the negative electrode material; the thickness of the coating layer can be but is not limited to 5 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, and the thickness of the coating layer within this range is beneficial to reduce the side reaction of the sheet-shaped nanosilicon and improve the ionic conductivity and electronic conductivity of the negative electrode material.

[0053] In this application, the mass content of the coating layer can be obtained by ash determination method; and the thickness of the coating layer can be obtained by TEM transmission electron microscopy.

[0054] In some embodiments, the specific surface area of the sheet-shaped nanosilicon A is 2 m 2 / g-8 m 2 / g.

[0055] Specifically, the specific surface area of the sheet-shaped nanosilicon can be but is not limited to 2 m 2 / g, 3 m 2 / g, 4 m 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, and the specific surface area of the sheet-shaped nanosilicon within this range is beneficial to reduce the side reaction of the sheet-shaped nanosilicon material, increase the contact area with the active material, and improve the rate performance of the battery.

[0056] In the present application, the specific surface area of the sheet-shaped nanometer silicon can be obtained by GB / T 19587-2017 "Determination of Specific Surface Area of Solid Substances by Gas Adsorption BET Method".

[0057] In some embodiments, the sheet-shaped nanometer silicon A comprises silicon grains, and the size of the silicon grains is 0.5 nm-1.5 nm.

[0058] Specifically, the sheet-shaped nanometer silicon comprises part of silicon crystals, and the silicon crystals are in the form of silicon grains, which are in a granular shape. The size of the silicon grains refers to the size of the silicon crystal particles in a crystalline state. The size of the silicon grains can be, but is not limited to, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1.0 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm. The size of the silicon grains in this range is beneficial to reduce the lithium intercalation expansion of the sheet-shaped nanometer silicon material and improve the battery performance.

[0059] In the present application, the size of the silicon grains can be calculated according to the Scherrer formula, wherein the calculation method is: D = Kλ / βcosθ, D is the size of the grains, K is a constant (0.89), λ is the wavelength of X-rays, β is the half-height width of the diffraction peak, and θ is the diffraction angle.

[0060] In some embodiments, the thickness of the sheet-shaped nanometer silicon A is 10 nm-20 nm, and the length of the sheet-shaped nanometer silicon A is 50 nm-250 nm.

[0061] Specifically, the thickness of the sheet-shaped nanometer silicon refers to the thickness of the two-dimensional nanometer silicon material. The thickness of the sheet-shaped nanometer silicon can be, but is not limited to, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, or 20 nm. The length of the sheet-shaped nanometer silicon refers to the length of the longest side in the two-dimensional sheet plane formed by the sheet-shaped nanometer silicon. The length of the sheet-shaped nanometer silicon can be, but is not limited to, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, or 250 nm. The thickness and length of the sheet-shaped nanometer silicon in this range are beneficial to reduce the lithium intercalation expansion of the sheet-shaped nanometer silicon material, alleviate the lithium intercalation size effect of the silicon material, improve the flexibility of the sheet-shaped nanometer silicon material, and improve the battery capacity.

[0062] In some embodiments, the ratio of the length to the thickness of the sheet-shaped nanometer silicon A is 2.5-25.

[0063] Specifically, the ratio of the length and thickness of the flaky nanosilicon can be, but is not limited to, 2.5, 5, 10, 15, 20, 25. The ratio of the length and thickness of the flaky nanosilicon within this range is beneficial to relieving the lithium intercalation expansion of the flaky nanosilicon material, enhancing the flexibility of the flaky nanosilicon material, thereby improving the capacity of the battery; and can improve the conductivity of the negative electrode material, further improving the conductive network of the electrode.

[0064] In some embodiments, the ratio of the total area of the hole structure C to the area of the flaky nanosilicon A is (1-2):5.

[0065] Specifically, the total area of the hole structure refers to the area of the hole structure on the surface of the two-dimensional flaky nanosilicon, and the area of the flaky nanosilicon refers to the surface area of the two-dimensional flaky nanosilicon. The ratio of the total area of the hole structure to the area of the flaky nanosilicon can be, but is not limited to, 1:5, 1.5:5, 2:5. The ratio of the total area of the hole structure to the area of the flaky nanosilicon within this range can ensure the flexibility of the negative electrode material and the amount of carbon nanotubes passing through, thereby improving the conductivity of the negative electrode material.

[0066] In a second aspect, the present application provides a preparation method of the negative electrode material described above, comprising the following steps:

[0067] S1: obtaining a flaky nanosilicon precursor;

[0068] S2: performing pore making on the flaky nanosilicon precursor to obtain a flaky nanosilicon;

[0069] S3: mixing the flaky nanosilicon and the carbon nanotubes;

[0070] S4: introducing a carbon source into the mixed material to obtain a negative electrode material.

[0071] Specifically, in step S1, the flaky nanosilicon precursor refers to a flaky nanosilicon without a hole structure. The method for obtaining the flaky nanosilicon precursor is not limited, including but not limited to generating silicon element through Li+SiCl4 reaction, DTAB+SiCl4 reaction, Mg2Si+SiCl4 reaction, Mg2Si+ bromine reaction, and NaSi and NH4Br reaction, then depositing the silicon element on the flaky material through a template method to form the flaky nanosilicon precursor. In step S2, the pore making method for the flaky nanosilicon is not limited, which can be pore making through a physical method, a chemical method, or a combination of physical and chemical methods to form the flaky nanosilicon of the present application. The preparation method of the negative electrode material provided by the present application is simple, easy to operate, low in energy consumption, easy to industrialize, and reduces the production cost.

[0072] In some embodiments, the preparation method comprises the following steps:

[0073] S1: adding flaky graphene, metal particles, NaSi and NH4Br into an organic solvent to react in a vacuum environment to obtain a flaky nano-silicon precursor;

[0074] S2: adding the obtained flaky nano-silicon precursor into an acid solution to perform acid washing treatment to obtain flaky nano-silicon, the flaky nano-silicon comprising a pore structure;

[0075] S3: mixing the flaky nano-silicon with carbon nanotubes and performing vibration treatment;

[0076] S4: introducing a carbon source into the mixture after vibration treatment to perform a reaction, the reaction being performed in a protective gas to obtain a negative electrode material.

[0077] Specifically, the vacuum environment can avoid oxidation of the silicon material; the reaction of NaSi and NH4Br generates silicon atoms, which can grow better on the surface of the flaky graphene; the metal particles can be, but are not limited to, metal iron particles, metal aluminum particles, metal magnesium particles, and metal copper particles.

[0078] Compared with the prior art, the preparation method of the negative electrode material provided in the present application grows silicon on the surface of flaky graphene by a template method, from a point shape to a planar shape, and finally to a flaky nano-silicon material. The flaky nano-silicon material is two-dimensional and flaky. The metal particles form pores on the flaky nano-silicon material to form a pore structure. The flaky nano-silicon with the pore structure is physically mixed with carbon nanotubes to make the carbon nanotubes pass through the pore structure of the flaky nano-silicon to form a knitted mesh structure. The method is simple, easy to operate, and easy to mass-produce.

[0079] In some embodiments, after step S4, the method further comprises adding one or more of lithium polyacrylate powder, lithium carboxymethyl cellulose powder, lithium meta-aluminate powder, aluminum oxide powder, and aluminum fluoride powder to the negative electrode material to perform heating treatment, to obtain a negative electrode material with a coating layer, the coating layer comprising one or more of lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide, and aluminum fluoride.

[0080] Specifically, the lithium polyacrylate powder, lithium carboxymethyl cellulose powder, lithium meta-aluminate powder, aluminum oxide powder, and aluminum fluoride powder are added to perform heating treatment, so that the lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide, and aluminum fluoride are uniformly and stably coated on the surface of the flaky silicon material, the carbon nanotubes, and the amorphous carbon. The coating layer can enhance the electronic and ionic conductivity of the negative electrode material and improve the battery capacity.

[0081] In some embodiments, the temperature of the heating treatment is 280-520℃, and the time of the heating treatment is 30-120min.

[0082] Specifically, the temperature of the heating treatment can be, but is not limited to, 280℃, 300℃, 320℃, 350℃, 400℃, 450℃, 500℃, 520℃; the time of the heating treatment can be, but is not limited to, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min; the temperature and the time of the heating treatment in the range can make the lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide and aluminum fluoride more uniformly and stably coated on the surface of the sheet-shaped silicon material and / or the carbon nanotube.

[0083] In some embodiments, in step S1, the organic solvent includes nitrogen benzene and ethylene glycol dimethyl ether.

[0084] Specifically, the organic solvent provides a vacuum environment and is conducive to the growth of the silicon material on the surface of the sheet-shaped graphene.

[0085] In some embodiments, in step S1, the temperature of the reaction is 180℃-380℃, and the time of the reaction is 10h-40h.

[0086] Specifically, the reaction method in step S1 is a template method, the temperature of the reaction is 180℃-380℃, and the time of the reaction is 10h-40h, so that the silicon element grows around the sheet-shaped graphene, grows from a point shape to a plane shape, and finally grows into a sheet-shaped nanosilicon material precursor. The temperature of the reaction can be, but is not limited to, 180℃, 190℃, 200℃, 210℃, 220℃, 250℃, 280℃, 300℃, 320℃, 350℃, 380℃; the time of the reaction can be, but is not limited to, 10h, 15h, 20h, 25h, 30h, 35h, 40h.

[0087] In some embodiments, after step S1, the obtained sheet-shaped nanosilicon precursor is further cleaned with ethanol to remove impurities of the sheet-shaped nanosilicon precursor.

[0088] In some embodiments, in step S2, the acid solution includes a hydrochloric acid solution or a sulfuric acid solution, and / or the time of the pickling treatment is 1h-3h.

[0089] Specifically, the concentration of the acid solution is not limited, and a conventional acid concentration can be used for the pickling treatment, for example, the conventional acid concentration can be 1mol / L-6mol / L; in a normal temperature environment, the pickling treatment is performed by using the acid solution, and the time of the treatment can be, but is not limited to, 1h, 1.5h, 2h, 2.5h, 3h, so as to ensure that the metal particles completely react and form a pore structure on the sheet-shaped nanosilicon.

[0090] In some embodiments, in step S3, the frequency of the vibration treatment is 18-42 Hz, and the time of the vibration treatment is 1-3 h.

[0091] Specifically, after the carbon nanotubes are added, vibration treatment is performed in a vibration device to make the carbon nanotubes fully penetrate into the pore structure of the flaky nanosilicon to form a composite negative electrode material in which the carbon nanotubes penetrate through the flaky nanosilicon. The vibration frequency can be, but is not limited to, 18 Hz, 20 Hz, 25 Hz, 30 Hz, 35 Hz, 40 Hz or 45 Hz, and the vibration time can be, but is not limited to, 1.0 h, 1.5 h, 2.0 h, 2.5 h or 3.0 h. In some embodiments of the present application, the number of times of vibration is not limited as long as the carbon nanotubes can fully penetrate into the pore structure of the flaky nanosilicon. In some embodiments of the present application, the material can be vibrated in the upright position first and then in the inverted position, or the material can be vibrated in the inverted position first and then in the upright position.

[0092] In some embodiments, in step S4, the carbon source includes acetylene and / or methane; the temperature of the reaction is 600-800℃, and the time of the reaction is 1-5 h.

[0093] Specifically, the passing of the carbon source for reaction refers to a cracking reaction of the carbon source, the temperature of the reaction is 600-800℃, the time of the reaction is 1-5 h, the temperature of the reaction includes, but is not limited to, 600℃, 650℃, 700℃, 750℃ or 800℃, and the time of the reaction includes, but is not limited to, 1 h, 2 h, 3 h, 4 h or 5 h. The cracked carbon atoms are deposited at the contact interface of the carbon nanotubes and the flaky nanosilicon to fix the carbon nanotube material.

[0094] In some embodiments, in step S4, the protective gas includes at least one of argon, nitrogen and helium, and the protective gas and the carbon source are synchronously passed in, or the protective gas is passed in before the carbon source.

[0095] Specifically, the protective gas can be continuously passed in during the passing of the carbon source, or the protective gas can be passed in before the carbon source. The protective gas plays a role of protection and carrier gas and can make the deposition of the carbon source more uniform.

[0096] In some embodiments, the gas flow rate of the carbon source is 20-60 sccm, and the ratio of the gas flow rate of the protective gas to the gas flow rate of the carbon source is 0.5-5.

[0097] Specifically, the flow rate of the carbon source gas can be, but is not limited to, 20 sccm, 30 sccm, 40 sccm, 50 sccm, or 60 sccm. The flow rate of the carbon source gas in this range can make the cracked carbon atoms deposit on the contact interface between the carbon nanotube and the sheet-shaped nanosilicon, and fix the carbon nanotube material. The ratio of the flow rate of the protective gas to the flow rate of the carbon source gas can be, but is not limited to, 0.5, 1, 2, 3, or 5. The ratio of the flow rate of the protective gas to the flow rate of the carbon source gas in this range can make the cracked carbon atoms better deposit on the contact interface between the carbon nanotube and the sheet-shaped nanosilicon, and fix the carbon nanotube material.

[0098] In a third aspect, the present application provides a lithium ion battery comprising the negative electrode material described above or the negative electrode material prepared by the preparation method of the negative electrode material described above.

[0099] The lithium ion battery provided by the present application comprises a positive electrode sheet, a negative electrode sheet, and a separator and an electrolyte between the positive electrode sheet and the negative electrode sheet. It should be noted that the positive electrode sheet provided by the present application comprises a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer comprises a positive electrode active material, a conductive agent, and a binder. The positive electrode active material, the conductive agent, and the binder are all prior art and will not be described here. The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer comprises a negative electrode active material, a conductive agent, and a binder. The negative electrode active material comprises the negative electrode material in any of the embodiments described above or the negative electrode material prepared by the preparation method of the negative electrode material in any of the embodiments described above.

[0100] The electrolyte and the separator are not particularly limited in the present application, and can be, but are not limited to, substances that can be used as battery electrolytes and separators in the art.

[0101] The conductive agent and the binder are not particularly limited in the present application, and can be selected according to actual application requirements. Specifically, the conductive agent comprises, but is not limited to, one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, and carbon nanotube. The binder comprises, but is not limited to, one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene butadiene rubber, hydroxypropyl methyl cellulose, methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives.

[0102] In a fourth aspect, the present application provides a power-consuming device comprising the lithium ion battery described above.

[0103] Specifically, the power-consuming device comprises, but is not limited to, an electric vehicle, an electric motorcycle, an electric bicycle, a mobile power source, a drone, a mobile phone, a computer, a camera, an electric tool, a smart home, or a wearable device.

[0104] The application will be further described in detail by examples.

[0105] Example 1

[0106] The present embodiment is used to illustrate the negative electrode material and the preparation method thereof, the lithium ion battery and the electric equipment disclosed by the present application, which comprises the following steps:

[0107] (1) Preparation of the negative electrode material:

[0108] S1: Add organic solvents (specifically, nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into a vacuum reaction kettle, the dispersion solid content of the flaky graphene in the organic solvents is 0.5 w.t.%, and the content of the spherical metal magnesium particles in the organic solvents is 1 w.t.%; add NaSi and NH4Br into the organic solvents, and react at 280°C for 24 h to synthesize a flaky nano-silicon material precursor; collect the synthesized flaky nano-silicon material precursor, and clean it with ethanol for three times.

[0109] S2: Add the flaky nano-silicon material precursor collected by the reaction into a hydrochloric acid solution for acid washing treatment at room temperature, the concentration of the hydrochloric acid is 1 mol / L, and the acid washing treatment time is 3 h.

[0110] S3: Perform vibration mixing treatment on the flaky nano-silicon material after the acid washing treatment and carbon nanotubes in a vibration device, the vibration frequency is 30 Hz, the vibration time is 3 h, after completion, invert the materials in the vibration cavity to vibrate at a frequency of 30 Hz for 3 h; after each vibration is completed, continue to vibrate the cavity materials, and repeat four times to obtain the negative electrode material.

[0111] S4: Pass carbon source (acetylene, the reaction temperature is 800°C, and the reaction time is 1 h) and protective gas (argon) into the vibration cavity of the negative electrode material, the carbon source gas flow is 60 sccm, and the gas flow of the protective gas is 300 sccm.

[0112] Example 2

[0113] The difference from example 1 is that the preparation of the negative electrode material is different, specifically as follows:

[0114] S1: Add organic solvents (specifically, nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into a vacuum reaction kettle, the dispersion solid content of the flaky graphene in the organic solvents is 0.5 w.t.%, and the content of the spherical metal magnesium particles in the organic solvents is 1 w.t.%; add NaSi and NH4Br into the organic solvents, and react at 280°C for 24 h to synthesize a flaky nano-silicon material precursor; collect the synthesized flaky nano-silicon material precursor, and clean it with ethanol for three times.

[0115] S2: The flaky nanosilicon material precursor collected in the above reaction is added to a hydrochloric acid solution for acid washing treatment at room temperature, the concentration of the acid is 1 mol / L, and the acid washing treatment time is 3 h.

[0116] S3: The flaky nanosilicon material after the acid washing treatment is mixed with carbon nanotubes in a vibration device for vibration mixing treatment, the vibration frequency is 30 Hz, the vibration time is 3 h, and after completion, the materials in the vibration cavity are inverted for vibration at a frequency of 30 Hz for 3 h; after each vibration is completed, the cavity materials are inverted for continuous vibration, and the above steps are repeated four times to obtain the negative electrode material.

[0117] S4: The cracked carbon source (acetylene, reaction temperature is 800℃, and reaction time is 1 h) and protective gas (argon) are introduced into the vibration cavity of the above negative electrode material, the carbon source gas flow is 60 sccm, and the protective gas gas flow is 300 sccm.

[0118] S5: The negative electrode material collected in the above reaction is mixed with lithium polyacrylate polymer powder for heating treatment, the heating temperature is 400℃, the heating reaction time is 90 min, and the negative electrode material coated with a lithium polyacrylate coating layer is obtained.

[0119] Example 3

[0120] The difference between Example 2 is that the preparation of the negative electrode material is different, and the specific steps are as follows:

[0121] S1: In a vacuum reaction kettle, organic solvents (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical magnesium metal particles and flaky graphene are added, the dispersion solid content of the flaky graphene in the organic solvent is 0.5 w.t.%, and the content of the spherical magnesium metal particles in the organic solvent is 1 w.t.%; NaSi and NH4Br are added to the organic solvent, and the flaky nanosilicon material precursor is synthesized by reacting at 200℃ for 24 h; the synthesized flaky nanosilicon material precursor is washed with ethanol three times.

[0122] The remaining steps are the same as those of Example 2.

[0123] Example 4

[0124] The difference between Example 2 is that the preparation of the negative electrode material is different, and the specific steps are as follows:

[0125] S1: Add organic solvent (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into the vacuum reaction kettle, the dispersion solid content of flaky graphene in the organic solvent is 0.5 w.t.%, the content of spherical metal magnesium particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br into the organic solvent, react at 360°C for 24h to synthesize the precursor of flaky nanosilicon material; collect the synthesized precursor of flaky nanosilicon material, and clean it three times using ethanol.

[0126] The remaining steps are the same as those of Example 2.

[0127] Example 5

[0128] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0129] S1: Add organic solvent (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into the vacuum reaction kettle, the dispersion solid content of flaky graphene in the organic solvent is 0.5 w.t.%, the content of spherical metal magnesium particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br into the organic solvent, react at 160°C for 24h to synthesize the precursor of flaky nanosilicon material; collect the synthesized precursor of flaky nanosilicon material, and clean it three times using ethanol.

[0130] The remaining steps are the same as those of Example 2.

[0131] Example 6

[0132] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0133] S1: Add organic solvent (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into the vacuum reaction kettle, the dispersion solid content of flaky graphene in the organic solvent is 0.5 w.t.%, the content of spherical metal magnesium particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br into the organic solvent, react at 400°C for 24h to synthesize the precursor of flaky nanosilicon material; collect the synthesized precursor of flaky nanosilicon material, and clean it three times using ethanol.

[0134] The remaining steps are the same as those of Example 2.

[0135] Example 7

[0136] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0137] S1: Add organic solvent (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into the vacuum reaction kettle, the dispersion solid content of flaky graphene in the organic solvent is 0.5 w.t.%, the content of spherical metal magnesium particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br into the organic solvent, react at 280°C for 12h to synthesize the precursor of flaky nanosilicon material; collect the synthesized precursor of flaky nanosilicon material, and clean it three times using ethanol.

[0138] The remaining steps are the same as those of Example 2.

[0139] Example 8

[0140] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0141] S1: Add organic solvent (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into the vacuum reaction kettle, the dispersion solid content of flaky graphene in the organic solvent is 0.5 w.t.%, the content of spherical metal magnesium particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br into the organic solvent, react at 280°C for 36h to synthesize the precursor of flaky nanosilicon material; collect the synthesized precursor of flaky nanosilicon material, and clean it three times using ethanol.

[0142] The remaining steps are the same as those of Example 2.

[0143] Example 9

[0144] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0145] S1: Add organic solvent (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical metal magnesium particles and flaky graphene into the vacuum reaction kettle, the dispersion solid content of flaky graphene in the organic solvent is 0.5 w.t.%, the content of spherical metal magnesium particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br into the organic solvent, react at 280°C for 8h to synthesize the precursor of flaky nanosilicon material; collect the synthesized precursor of flaky nanosilicon material, and clean it three times using ethanol.

[0146] The remaining steps are the same as those of Example 2.

[0147] Example 10

[0148] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0149] S1: Add organic solvent (specifically nitrogen benzene and ethylene glycol dimethyl ether) into a vacuum reaction kettle, the organic solvent contains spherical magnesium particles and flaky graphene, the dispersion solid content of flaky graphene in the organic solvent is 0.5 w.t.%, the content of spherical magnesium particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br into the organic solvent, react at 280°C for 42h to synthesize a flaky nanosilicon material precursor; collect the synthesized flaky nanosilicon material precursor, and clean it three times using ethanol.

[0150] The remaining steps are the same as those in Example 2.

[0151] Example 11

[0152] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0153] S3: The flaky nanosilicon material after acid washing is mixed with carbon nanotubes in a vibration device, the vibration frequency is 20Hz, the vibration time is 3h, after completion, the materials in the vibration cavity are inverted to vibrate at a frequency of 20Hz for 3h; after each vibration is completed, the cavity materials are inverted and continue to vibrate, and the process is repeated four times to obtain the negative electrode material.

[0154] The remaining steps are the same as those in Example 2.

[0155] Example 12

[0156] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0157] S3: The flaky nanosilicon material after acid washing is mixed with carbon nanotubes in a vibration device, the vibration frequency is 40Hz, the vibration time is 3h, after completion, the materials in the vibration cavity are inverted to vibrate at a frequency of 40Hz for 3h; after each vibration is completed, the cavity materials are inverted and continue to vibrate, and the process is repeated four times to obtain the negative electrode material.

[0158] The remaining steps are the same as those in Example 2.

[0159] Example 13

[0160] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0161] S3: The flaky nanosilicon material after acid washing is mixed with carbon nanotubes in a vibration device, the vibration frequency is 16Hz, the vibration time is 3h, after completion, the materials in the vibration cavity are inverted to vibrate at a frequency of 16Hz for 3h; after each vibration is completed, the cavity materials are inverted and continue to vibrate, and the process is repeated four times to obtain the negative electrode material.

[0162] The remaining steps are the same as in Example 2.

[0163] Example 14

[0164] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0165] S3: The above acid-washed sheet-shaped nanosilicon material and carbon nanotubes are mixed and treated in a vibration device, the vibration frequency is 44 Hz, the vibration time is 3 h, after completion, the materials in the vibration cavity are inverted to vibrate at a frequency of 44 Hz for 3 h; after each vibration is completed, the cavity materials are inverted and continue to vibrate, and the above steps are repeated four times to obtain the negative electrode material.

[0166] The remaining steps are the same as in Example 2.

[0167] Example 15

[0168] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0169] S5: The above reaction collected negative electrode material is mixed with lithium polyacrylate polymer powder and heated, wherein the heating temperature is 300°C, and the heating reaction time is 90 min, to obtain a negative electrode material coated with a lithium polyacrylate coating layer.

[0170] The remaining steps are the same as in Example 2.

[0171] Example 16

[0172] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0173] S5: The above reaction collected negative electrode material is mixed with lithium polyacrylate polymer powder and heated, wherein the heating temperature is 500°C, and the heating reaction time is 90 min, to obtain a negative electrode material coated with a lithium polyacrylate coating layer.

[0174] The remaining steps are the same as in Example 2.

[0175] Example 17

[0176] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0177] S5: The above reaction collected negative electrode material is mixed with lithium polyacrylate polymer powder and heated, wherein the heating temperature is 260°C, and the heating reaction time is 90 min, to obtain a negative electrode material coated with a lithium polyacrylate coating layer.

[0178] The remaining steps are the same as in Example 2.

[0179] Example 18

[0180] The difference from Example 2 is that the preparation of the negative electrode material is different, specifically as follows:

[0181] S5: The negative electrode material collected from the above reaction is mixed with lithium polyacrylate polymer powder and subjected to heat treatment, wherein the heating temperature is 540°C, and the heating reaction time is 90 min, to obtain a negative electrode material coated with a lithium polyacrylate coating layer.

[0182] The remaining steps are the same as those of Example 2.

[0183] Comparative Example 1

[0184] S1: Add organic solvents (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing spherical magnesium metal particles and sheet-shaped graphene to a vacuum reaction kettle, wherein the dispersion solid content of the sheet-shaped graphene in the organic solvent is 0.5 w.t.%, and the content of the spherical magnesium metal particles in the organic solvent is 1 w.t.%; add NaSi and NH4Br to the organic solvent, and react at 280°C for 24 h to synthesize a sheet-shaped nanosilicon material precursor; collect the synthesized sheet-shaped nanosilicon material precursor, and wash it with ethanol three times.

[0185] S2: At room temperature, add the sheet-shaped nanosilicon material precursor collected from the above reaction to a hydrochloric acid solution for acid washing treatment, wherein the concentration of the acid is 1 mol / L, and the acid washing treatment time is 3 h.

[0186] S3: Introduce a cracked carbon source (acetylene, reaction temperature 800°C, reaction time 1 h) and a protective gas (argon) into the vibration cavity of the above negative electrode material, wherein the carbon source gas flow is 60 sccm, and the protective gas gas flow is 300 sccm.

[0187] S4: Mix the negative electrode material collected from the above reaction with lithium polyacrylate polymer powder and subject it to heat treatment, wherein the heating temperature is 400°C, and the heating reaction time is 90 min, to obtain a negative electrode material coated with a lithium polyacrylate coating layer.

[0188] Comparative Example 2

[0189] S1: Add organic solvents (specifically nitrogen benzene and ethylene glycol dimethyl ether) containing sheet-shaped graphene to a vacuum reaction kettle, wherein the dispersion solid content of the sheet-shaped graphene in the organic solvent is 0.5 w.t.%; add NaSi and NH4Br to the organic solvent, and react at 280°C for 24 h to synthesize a sheet-shaped nanosilicon material precursor; collect the synthesized sheet-shaped nanosilicon material precursor, and wash it with ethanol three times.

[0190] S2: The above-processed flaky nanosilicon material and carbon nanotubes are subjected to vibration mixing treatment in a vibration device, the vibration frequency is 30 Hz, the vibration time is 3 h, after completion, the materials in the vibration cavity are inverted to vibrate at a frequency of 30 Hz for 3 h; after each vibration is completed, the cavity materials are inverted and continue to vibrate, and the above steps are repeated four times to obtain the negative electrode material.

[0191] S4: A cracked carbon source (acetylene, reaction temperature is 800°C, reaction time is 1 h) and a protective gas (argon) are introduced into the vibration cavity of the above-mentioned negative electrode material, the flow rate of the carbon source gas is 60 sccm, and the flow rate of the protective gas is 300 sccm.

[0192] S5: The negative electrode material collected after the above reaction is mixed with a lithium polyacrylate polymer powder and subjected to heating treatment, wherein the heating temperature is 400°C, and the heating reaction time is 90 min, to obtain a negative electrode material coated with a lithium polyacrylate coating layer.

[0193] (1) Negative electrode material parameter test:

[0194] Flaky nanosilicon silicon grain size: XRD test, grain size is calculated by Scherrer formula, the specific calculation method is: D = Kλ / βcosθ, D is the grain size, K is a constant (0.89), λ is the wavelength of X-ray, β is the half-height width of the diffraction peak, and θ is the diffraction angle.

[0195] Specific surface area of flaky nanosilicon: The specific surface area test method refers to GB / T 19587-2017 "Gas adsorption BET method for measuring specific surface area of solid materials".

[0196] Length and thickness of flaky nanosilicon: Length is measured by TEM transmission electron microscope, and thickness is measured by FIB-TEM.

[0197] Pore structure size: TEM transmission electron microscope measurement statistics mean value.

[0198] Mass content of coating layer: ash content method test, the ash left after burning is the oxidized silicon material, the silicon content is calculated, and 1-silicon content is the sum of coating content and carbon nanotube content, and the content of the coating layer can be obtained by subtracting the content of the carbon nanotube.

[0199] Thickness of coating layer: TEM transmission electron microscope measurement average value.

[0200] Electrical conductivity: 2 g of powder material is placed in the jig cavity of the powder resistance meter, four-probe method is used for testing, the test pressure is 10 MPa, and the pressure maintaining time is 20 s.

[0201] The above test results are shown in Table 1.

[0202] (2) Battery production: the negative electrode material produced in Examples 1-18 and Comparative Examples 1-2 was mixed with acetylene black and sodium carboxymethyl cellulose at a ratio of 8:1:1, and then coated on a copper foil to obtain a negative electrode sheet; a lithium metal sheet was used as a positive electrode; a PE / PP composite separator was used as an ion exchange membrane, and a button cell was produced using conventional methods in the art.

[0203] Charge-discharge performance test

[0204] First coulombic efficiency: the button cell was discharged at a current of 0.01C to 0.005V at room temperature, and then charged at a current of 0.1C to 1.5V, the discharge capacity and charge capacity of the battery were recorded, and the charge-discharge efficiency (%) = first charge capacity / first discharge capacity x 100% was calculated, and the test results are shown in Table 2.

[0205] Capacity retention rate: the battery was charged at a current of 0.33C to 3.8V, and then discharged at a current of 0.33C to a discharge termination voltage of 2.0V, and then rested for 30min; the above two steps were repeated for a total of 100 times, and the discharge capacity of the first cycle was recorded as the battery discharge capacity C1, and the discharge capacity of the 100th cycle was C100; 100 cycle capacity retention rate (%) = (C100 / C1) x 100%

[0206] Swelling test: before assembling the button cell, the original thickness of each group of sample electrode sheets was measured using a micrometer. After 100 cycles, discharge to 0% SOC, disassemble the button cell, take out the negative electrode sheet, and clean it with DMC solution, dry and test the thickness, and calculate the swelling rate, swelling rate (%) = (100 cycle electrode sheet thickness-initial thickness) / initial thickness, and the test results are shown in Table 2.

[0207] Table 1: Negative electrode material parameters of each example and comparative example

[0208]

[0209] Table 2: Performance test results of each example and comparative example

[0210]

[0211] According to Examples 1-18 and Comparative Examples 1-2, the negative electrode material provided by the present application includes sheet-shaped nanosilicon and carbon nanotubes, the carbon nanotubes pass through the hole structure on the sheet-shaped nanosilicon, forming an interwoven network structure that can effectively improve the capacity, rate performance and cycle performance of the battery, and alleviate the swelling of the electrode sheet. According to Examples 2 and 3-18, suitable reaction temperature, reaction time, vibration frequency and heating temperature can further improve the capacity, rate performance and cycle performance of the battery.

[0212] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A negative electrode material, characterized by, The negative electrode material comprises flaky nanosilicon, carbon nanotubes and amorphous carbon, the flaky nanosilicon comprises a pore structure, at least part of the carbon nanotubes pass through the pore structure, and the carbon nanotubes and the pore structure are connected by the amorphous carbon.

2. The negative electrode material according to claim 1, characterized in that, The diameter of the carbon nanotubes is 1 nm-5 nm; and the size of the pore structure is 5 nm-15 nm.

3. The negative electrode material of claim 1, wherein, The negative electrode material further comprises a coating layer, the coating layer is coated on the surface of the flaky nanosilicon, the carbon nanotubes and the amorphous carbon; and the coating layer comprises at least one of lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide and aluminum fluoride.

4. The negative electrode material according to claim 3, the content of the coating layer is 5 w.t. %-15 w.t. % based on the total mass of the negative electrode material; and / or, the thickness of the coating layer is 5 nm-8 nm.

5. The negative electrode material of claim 1, wherein, The specific surface area of the platelet-shaped nanosilicon is 2 m 2 / g-8 m 2 / g.

6. The negative electrode material of claim 1, wherein, The flaky nanosilicon comprises silicon grains, and the size of the silicon grains is 0.5 nm-1.5 nm.

7. The negative electrode material of claim 1, wherein, The thickness of the flaky nanosilicon is 10 nm-20 nm, and the length of the flaky nanosilicon is 50 nm-250 nm.

8. The negative electrode material of claim 1, wherein, The ratio of the length to the thickness of the flaky nanosilicon is 2.5-25.

9. The negative electrode material of claim 1, wherein, The ratio of the total area of the pore structure to the area of the flaky nanosilicon is (1-2):

5.

10. A method of producing the negative electrode material according to any one of claims 1 to 9, characterized by, The method comprises the following steps: S1: obtaining a flaky nanosilicon precursor; S2: performing pore formation on the flaky nanosilicon precursor to obtain the flaky nanosilicon; S3: mixing the flaky nanosilicon and the carbon nanotubes; S4: introducing a carbon source into the mixed material to obtain the negative electrode material.

11. The method of producing a negative electrode material according to claim 10, wherein The preparation method comprises the following steps: S1: in a vacuum environment, flaky graphene, metal particles, NaSi and NH4Br are added into an organic solvent to react, thereby obtaining a flaky nanosilicon precursor; S2: the obtained flaky nanosilicon precursor is added into an acid solution to perform acid washing treatment, thereby obtaining the flaky nanosilicon, and the flaky nanosilicon comprises the pore structure; S3: the flaky nanosilicon and the carbon nanotubes are mixed to perform vibration treatment; S4: a carbon source is introduced into the mixture after the vibration treatment to react, and the reaction is performed in a protective gas, thereby obtaining the negative electrode material.

12. The method of producing a negative electrode material according to claim 10 or 11, wherein After step S4, one or more of lithium polyacrylate powder, lithium carboxymethyl cellulose powder, lithium meta-aluminate powder, aluminum oxide powder and aluminum fluoride powder are added into the negative electrode material to perform heating treatment, thereby obtaining a negative electrode material with a coating layer, and the coating layer comprises one or more of lithium polyacrylate, lithium carboxymethyl cellulose, lithium meta-aluminate, aluminum oxide and aluminum fluoride.

13. The method of claim 12, wherein the method further comprises a step of mixing the carbon material and the metal compound. The temperature of the heating treatment is 280 ℃-520 ℃, and the time of the heating treatment is 30 min-120 min.

14. The method of claim 11, wherein the method is characterized by: In step S1, the organic solvent comprises nitrogen benzene and ethylene glycol dimethyl ether.

15. The method of claim 11, wherein the method further comprises a step of mixing the carbon material and the metal compound. In step S1, the temperature of the reaction is 180 ℃-380 ℃, and the time of the reaction is 10 h-40 h.

16. The method of claim 11, wherein the method is characterized by: In step S2, the acid solution comprises a hydrochloric acid solution or a sulfuric acid solution, and / or the time of the acid washing treatment is 1 h-3 h.

17. The method of claim 11, wherein the method is characterized by: In step S3, the frequency of the vibration treatment is 18-42 Hz, and the time of the vibration treatment is 1-3 hours.

18. The method of claim 11, wherein the method is a method of preparing a negative electrode material. In step S4, the carbon source comprises acetylene and / or methane; the temperature of the reaction is 600-800℃, and the time of the reaction is 1-5 hours.

19. The method of claim 11, wherein the method is characterized by: The protective gas comprises at least one of argon, nitrogen and helium, and the protective gas and the carbon source are synchronously introduced, or the protective gas is introduced before the carbon source.

20. The method of claim 19, wherein the method further comprises: The flow rate of the carbon source gas is 20-60 sccm, and the ratio of the flow rate of the protective gas to the flow rate of the carbon source gas is 0.5-5.

21. A lithium-ion battery, characterized by, The negative electrode material comprises the negative electrode material of any one of claims 1-9, or the negative electrode material prepared by the preparation method of any one of claims 10-20.

22. An electrical device, comprising: The battery comprises the battery of claim 21.

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