Negative electrode material, and preparation method therefor and use thereof

Abstract

A negative electrode material, and a preparation method therefor and the use thereof. The negative electrode material comprises a silicon-carbon core, wherein the silicon-carbon core comprises a porous silicon matrix and a carbon material arranged in pores of the porous silicon matrix, and the total pore volume of the silicon-carbon core is smaller than or equal to 0.0001 ml / g. The silicon-carbon core in the negative electrode material is of a compact structure, thereby reducing the specific surface area of the negative electrode material, improving the mechanical strength and specific capacity of the negative electrode material and facilitating the widespread use of the negative electrode material.

Description

Negative electrode material, preparation method and application thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 8, 2024, with application number 202410281501.5 and application name “Negative Electrode Materials, Preparation Methods and Applications Thereof”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of batteries, and in particular to a negative electrode material and a preparation method and application thereof. Background Art

[0003] Silicon negative electrode materials have high specific capacity and low deintercalation potential, making them ideal materials for preparing high energy density batteries. However, silicon negative electrode materials are prone to particle breakage during use, causing the electrodes to pulverize, leading to battery capacity decay and performance degradation, and shortening service life. In order to increase the cycle life of the battery, silicon negative electrode materials can be structurally designed, such as porous silicon negative electrode materials, to alleviate stress damage and electrochemical performance degradation caused by the charge and discharge process. However, porous silicon negative electrode materials have low mechanical strength and large specific surface area, and the resulting negative electrode sheets are easily broken, resulting in reduced cycle performance and lower charge and discharge specific capacity. Therefore, it is necessary to develop a negative electrode material with high mechanical strength, good specific capacity and low specific surface area.

[0004] Summary of the Invention

[0005] In view of this, the present application provides a negative electrode material, a preparation method and an application thereof. The negative electrode material includes a silicon-carbon core, which improves the mechanical strength and charge-discharge capacity of the negative electrode material, reduces the specific surface area of ​​the negative electrode material, and is conducive to the wide application of the negative electrode material.

[0006] In a first aspect, the present application discloses a negative electrode material, which includes a silicon-carbon core, which includes a porous silicon matrix and a carbon material, and the carbon material is arranged in the pores of the porous silicon matrix, and the total pore volume of the silicon-carbon core is less than or equal to 0.0001 ml / g.

[0007] Optionally, the particle size D50 of the porous silicon substrate is 5 μm-10 μm.

[0008] Optionally, the porous silicon substrate has a plurality of grains, and the grain size is less than or equal to 2 nm.

[0009] Optionally, the specific surface area of ​​the porous silicon substrate is greater than or equal to 750 m 2 / g.

[0010] Optionally, in the porous silicon matrix, the micropore volume accounts for 70%-80% of the total pore volume of the porous silicon matrix, the mesopore volume accounts for 5%-10% of the total pore volume of the porous silicon matrix, and the macropore volume accounts for 15%-25% of the total pore volume of the porous silicon matrix.

[0011] Optionally, in the silicon-carbon core, the mass percentage of the porous silicon matrix is ​​30%-60%, and the mass percentage of the carbon material is 40%-70%.

[0012] Optionally, the specific surface area of ​​the silicon carbon core is less than or equal to 10m 2 / g.

[0013] Optionally, the particle size D50 of the silicon carbon core is 5 μm-10 μm.

[0014] Optionally, the negative electrode material further includes carbon particles, and the mass percentage of the carbon particles in the negative electrode material is 85%-95%.

[0015] Optionally, the negative electrode material further includes a carbon coating layer, and the carbon coating layer is arranged on the surface of the silicon-carbon core.

[0016] Optionally, the carbon coating layer has a thickness of 10 nm to 20 nm.

[0017] Optionally, in the negative electrode material, the mass percentage of the carbon coating layer is 0.5%-2%.

[0018] Optionally, the coverage rate of the carbon coating layer is 80%-100%.

[0019] Optionally, the tap density of the negative electrode material is greater than or equal to 0.9 g / cm 3 .

[0020] Optionally, the compaction density of the negative electrode material is greater than or equal to 1.7 g / cm 3 .

[0021] Optionally, the Young's modulus of the negative electrode material is 260 MPa-300 MPa.

[0022] In the second aspect, the present application discloses a method for preparing a negative electrode material, comprising: carbon deposition on a porous silicon substrate to form a silicon-carbon core to obtain a negative electrode material; the silicon-carbon core comprises the porous silicon substrate and a carbon material disposed in the porous silicon substrate, and the total pore volume of the silicon-carbon core is less than or equal to 0.0001 ml / g.

[0023] Optionally, the gas flow rate of the carbon deposition is 1 L / min-10 L / min.

[0024] Optionally, the carbon deposition time is 10 hours to 15 hours.

[0025] Optionally, the temperature of the carbon deposition is 400°C-700°C.

[0026] Optionally, the preparation method further comprises: performing carbon coating treatment on the silicon-carbon core to form a carbon coating layer on the surface of the silicon-carbon core to obtain the negative electrode material.

[0027] Optionally, the gas flow rate of the carbon coating treatment is 0.05 L / min-1 L / min.

[0028] Optionally, the carbon coating treatment time is 0.5h-1h.

[0029] Optionally, the temperature of the carbon coating treatment is 400°C-700°C.

[0030] In a third aspect, the present application provides a negative electrode plate, which includes a negative electrode active material layer, and the negative electrode active material layer includes the negative electrode material described in the first aspect or the negative electrode material prepared by the preparation method described in the second aspect.

[0031] In a fourth aspect, the present application provides a battery comprising a positive electrode sheet and the negative electrode sheet described in the third aspect.

[0032] In a fifth aspect, the present application provides an electrical device, which includes the battery described in the fourth aspect.

[0033] In the negative electrode material provided in the present application, the silicon-carbon core includes a porous silicon matrix and a carbon material arranged in the pores of the porous silicon matrix. The total pore volume of the silicon-carbon core is less than or equal to 0.0001 ml / g. In such a negative electrode material system, the silicon-carbon core forms a dense structure, which improves the mechanical strength and specific capacity of the negative electrode material and reduces the specific surface area of ​​the negative electrode material, which is conducive to obtaining a negative electrode material with excellent electrochemical properties. It can improve the discharge specific capacity, stability and service life of the negative electrode sheet formed by using the negative electrode material, increase the capacity of the battery, improve the electrochemical performance of the battery, and is conducive to the industrial application of the battery and enhance product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. The specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0035] FIG1 is a schematic cross-sectional view of a negative electrode material provided in one embodiment of the present application.

[0036] FIG2 is a schematic cross-sectional view of a negative electrode material provided in another embodiment of the present application.

[0037] FIG3 is a schematic cross-sectional view of a porous silicon substrate provided in one embodiment of the present application.

[0038] FIG4 is a schematic cross-sectional view of a silicon-carbon core provided in accordance with an embodiment of the present application.

[0039] FIG5 is a schematic cross-sectional view of a negative electrode sheet provided in one embodiment of the present application.

[0040] FIG6 is a scanning electron microscope image of the porous silicon substrate provided in Example 1.

[0041] FIG7 is a scanning electron microscope image of the negative electrode material provided in Example 1.

[0042] FIG8 is a scanning electron microscope image of the negative electrode material and a silicon element distribution analysis result diagram of the battery provided in Example 1 after 1000 cycles.

[0043] FIG9 is a schematic diagram showing the positional relationship among the positive electrode sheet, the separator, and the negative electrode sheet in one embodiment of the present application.

[0044] FIG10 is a schematic structural diagram of an electrical device provided in one embodiment of the present application.

[0045] Description of labels:

[0046] Negative electrode material-100, silicon-carbon core-10, porous silicon substrate-11, carbon material-12, carbon coating layer-20, negative electrode plate-200, negative electrode current collector-30, negative electrode active material layer-40, positive electrode plate-50, separator-60, battery-70, electrical equipment-80. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0048] Please refer to Figure 1, which is a cross-sectional schematic diagram of the negative electrode material provided in one embodiment of the present application. The negative electrode material 100 includes a silicon-carbon core 10, which includes a porous silicon matrix and a carbon material disposed in the pores of the porous silicon matrix. The total pore volume of the silicon-carbon core 10 is less than or equal to 0.0001 ml / g. The total pore volume of the silicon-carbon core is less than or equal to 0.0001 ml / g. It can be considered that the silicon-carbon core is a dense structure. That is, the carbon material disposed in the porous silicon matrix can transform the loose and porous porous silicon matrix into a dense silicon-carbon core, thereby improving the mechanical strength of the negative electrode material and keeping the negative electrode material from breaking easily under high compaction conditions. At the same time, the carbon material fills the porous silicon matrix more fully, thereby significantly reducing the specific surface area of ​​the silicon-carbon core, which is beneficial to the improvement of the first-cycle coulomb efficiency and further improving the specific capacity of the negative electrode material. The negative electrode material provided in the present application has high mechanical strength, high specific capacity and low specific surface area, which is conducive to the wide application of negative electrode materials.

[0049] In one embodiment of the present application, the particle size D50 of the porous silicon substrate is 5μm-10μm, which is beneficial to improving the tap density and compaction density of the negative electrode material. Specifically, the particle size D50 of the porous silicon substrate may not be limited to 5μm, 6μm, 7μm, 8μm, 9μm and 10μm. In one embodiment of the present application, the particle size D50 of the porous silicon substrate may be 5μm-8μm. In another embodiment of the present application, the particle size D50 of the porous silicon substrate may be 7μm-10μm.

[0050] In one embodiment of the present application, the porous silicon substrate has a plurality of silicon grains, and the silicon grain size is less than or equal to 2nm, which can reduce the expansion stress generated during the charge and discharge process, improve the structural stability of the silicon-carbon core, and make the negative electrode material have no obvious cracking after a long cycle, which is conducive to the use of the negative electrode material. Specifically, the silicon grain size of the porous silicon substrate can be, but is not limited to, less than or equal to 2nm, less than or equal to 1.8nm, less than or equal to 1.6nm, less than or equal to 1.5nm, or less than or equal to 1.2nm. In one embodiment of the present application, the silicon grain size of the porous silicon substrate can be less than or equal to 1.5nm. In another embodiment of the present application, the silicon grain size of the porous silicon substrate can be less than or equal to 1.2nm.

[0051] Specifically, the grain size in the porous silicon matrix can be measured by X-ray diffraction (XRD). Specifically, based on the XRD test results, the grain size in the porous carbon matrix can be calculated by the Scherrer formula, which is as follows:

[0052] Where D is the grain size (in nm), K is the Scherrer constant, which is 0.89; λ is the wavelength of the X-ray (the wavelength λ of the commonly used CuKα radiation is 0.154056 nm), β is the half-height width of the diffraction peak; and θ is the Bragg diffraction angle.

[0053] In one embodiment of the present application, in the silicon-carbon core, the mass percentage of the porous silicon matrix is ​​30%-60%, which is beneficial to improving the specific capacity and energy density of the negative electrode material. At the same time, the porous silicon matrix serves as a skeleton structure, which is beneficial to the arrangement of the carbon material and helps to improve the conductivity of the negative electrode material. Specifically, the mass percentage of the porous silicon matrix can be, but is not limited to, 30%, 35%, 40%, 45%, 50%, 55% or 60%, etc. In one embodiment of the present application, the mass percentage of the porous silicon matrix can be 40%-50%, which can further improve the performance of the negative electrode material. In another embodiment of the present application, the mass percentage of the porous silicon matrix can be 40%-60%.

[0054] In one embodiment of the present application, the mass percentage of the carbon material in the silicon-carbon core is 40%-70%. The carbon material can increase the density of the silicon-carbon core, reduce the pore volume of the silicon-carbon core, and improve the conductivity of the negative electrode material. Specifically, the mass percentage of the carbon material can be, but is not limited to, 40%, 45%, 50%, 55%, 60%, or 70%. In one embodiment of the present application, the mass percentage of the carbon material can be 40%-55%. In another embodiment of the present application, the mass percentage of the carbon material is 50%-70%.

[0055] In the present application, the total pore volume of the silicon-carbon core is less than or equal to 0.0001 ml / g. The total pore volume in the present application includes the volume of all pores in the silicon-carbon core. The smaller the total pore volume, the fewer pores in the silicon-carbon core and the higher the density of the silicon-carbon core. Specifically, the total pore volume of the silicon-carbon core may be, but is not limited to, less than or equal to 0.0001 ml / g, less than or equal to 0.00009 ml / g, less than or equal to 0.00008 ml / g, less than or equal to 0.00007 ml / g, less than or equal to 0.00006 ml / g, less than or equal to 0.00005 ml / g, less than or equal to 0.00004 ml / g, less than or equal to 0.00003 ml / g, less than or equal to 0.00002 ml / g, less than or equal to 0.00001 ml / g, etc. In one embodiment of the present application, the total pore volume of the silicon-carbon core may be less than or equal to 0.00008 ml / g. In another embodiment of the present application, the total pore volume of the silicon carbon core may be less than or equal to 0.00005 ml / g.

[0056] In one embodiment of the present application, the specific surface area of ​​the silicon carbon core is less than or equal to 10m 2 / g. The smaller the specific surface area of ​​the silicon-carbon core, the fewer the pores in the silicon-carbon core, and the higher the filling degree of carbon material in the silicon-carbon core; the specific surface area of ​​the silicon-carbon core is 10m 2 / g or less is beneficial to improving the coulombic efficiency and mechanical strength of the negative electrode material. Specifically, the specific surface area of ​​the silicon-carbon core can be, but is not limited to, less than or equal to 10m 2 / g, less than or equal to 9m 2 / g, less than or equal to 8m 2 / g, less than or equal to 7m 2 / g or less than or equal to 5m 2 / g, etc. In one embodiment of the present application, the specific surface area of ​​the silicon carbon core can be 2m 2 / g-7m 2 / g, which is beneficial to improve the density of the silicon carbon core, thereby further improving the mechanical strength and coulombic efficiency of the negative electrode material. In another embodiment of the present application, the specific surface area of ​​the silicon carbon core can be less than or equal to 5m 2 / g.

[0057] In one embodiment of the present application, the particle size D50 of the silicon-carbon core is 5 μm-10 μm, which is beneficial to improving the tap density and compaction density of the negative electrode material. Specifically, the particle size D50 of the silicon-carbon core may be limited to 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm. In one embodiment of the present application, the particle size D50 of the silicon-carbon core may be 5 μm-8 μm. In another embodiment of the present application, the particle size D50 of the silicon-carbon core may be 7 μm-10 μm.

[0058] Unless otherwise specified, the particle size D50 of the material (such as the particle size D50 of the porous carbon matrix or the particle size D50 of the silicon-carbon core, etc.) refers to the particle size Dv50 of the material. Dv50 indicates the particle size of the particles starting from the small particle size side in the volume-based particle size distribution of the material when the volume accumulation reaches 50%, which can be measured by a laser particle size distribution analyzer.

[0059] Please refer to Figure 2, which is a cross-sectional schematic diagram of a negative electrode material provided in another embodiment of the present application. The negative electrode material 100 also includes a carbon coating layer 20, which is arranged on the surface of the silicon-carbon core 10. The silicon-carbon core has a dense structure, which improves the mechanical strength of the negative electrode material; the carbon coating layer can absorb and buffer the stress expansion during the charge and discharge process, improve the structural stability of the negative electrode material, and the particles do not significantly break after multiple cycles; the carbon coating layer passivates the defects that may exist on the surface of the silicon-carbon core, prevents direct contact between the electrolyte and the defects, improves the stability of the negative electrode plate, and further improves the cycle performance of the negative electrode material. In one embodiment of the present application, the carbon coating layer has an amorphous structure, which can effectively absorb and buffer the expansion stress generated by the porous silicon matrix during the use of the negative electrode material, further improving the structural stability of the negative electrode material.

[0060] In one embodiment of the present application, the thickness of the carbon coating layer is 10nm-20nm, which not only ensures the mechanical properties of the negative electrode material but also improves the cycle performance of the negative electrode material. Specifically, the thickness of the carbon coating layer can be, but is not limited to, 10nm, 12nm, 14nm, 16nm, 18nm, or 20nm. In one embodiment of the present application, the thickness of the carbon coating layer can be 10nm-16nm. In another embodiment of the present application, the thickness of the carbon coating layer can be 13nm-20nm.

[0061] In one embodiment of the present application, the coverage of the carbon coating layer is 80%-100%. This can further improve the structural stability of the negative electrode material, which is beneficial to improving the cycle stability of the negative electrode material. Specifically, the coverage of the carbon coating layer can be, but is not limited to, 80%, 85%, 90%, 92%, 95% or 100%. In one embodiment of the present application, the coverage of the carbon coating layer can be 80%-95%. In another embodiment of the present application, the coverage of the carbon coating layer can be 90%-100%.

[0062] In one embodiment of the present application, the mass percentage of the carbon coating layer in the negative electrode material is 0.5%-2%. This can improve the structural stability of the negative electrode material and enhance the cycle performance of the negative electrode material. Specifically, the mass percentage of the carbon coating layer can be, but is not limited to, 0.5%, 0.6%, 0.8%, 1%, 1.5% or 2%. In one embodiment of the present application, the mass percentage of the carbon coating layer can be 0.5%-1.6%. In another embodiment of the present application, the mass percentage of the carbon coating layer can be 1.2%-2%.

[0063] In one embodiment of the present application, the mass percentage of the silicon-carbon core in the negative electrode material may be 98%-99.5%. Specifically, the mass percentage of the silicon-carbon core may be, but is not limited to, 98%, 98.5%, 98.7%, 98.9%, 99%, and 99.5%. In one embodiment of the present application, the mass percentage of the silicon-carbon core may be 98%-99%. In another embodiment of the present application, the mass percentage of the silicon-carbon core may be 98.5%-99%.

[0064] In one embodiment of the present application, the tap density of the negative electrode material is greater than or equal to 0.9 g / cm 3 , which is beneficial to improving the specific capacity of the negative electrode material. Specifically, the tap density of the negative electrode material can be, but is not limited to, greater than or equal to 0.9 g / cm 3 , greater than or equal to 0.92g / cm 3 , greater than or equal to 0.95g / cm 3 , greater than or equal to 0.97g / cm 3 or greater than or equal to 1g / cm 3In one embodiment of the present application, the tap density of the negative electrode material can be 0.9 g / cm 3 -0.97g / cm 3 In another embodiment of the present application, the tap density of the negative electrode material is greater than or equal to 0.95 g / cm 3 .

[0065] In one embodiment of the present application, the compaction density of the negative electrode material is greater than or equal to 1.7 g / cm 3 , which is beneficial to improving the specific capacity of the negative electrode material. Specifically, the compaction density of the negative electrode material can be, but is not limited to, greater than or equal to 1.7 g / cm 3 , greater than or equal to 1.75g / cm 3 , greater than or equal to 1.8g / cm 3 , greater than or equal to 1.85g / cm 3 , greater than or equal to 1.9g / cm 3 or greater than or equal to 2g / cm 3 In one embodiment of the present application, the compaction density of the negative electrode material is greater than or equal to 1.78 g / cm 3 In another embodiment of the present application, the compaction density of the negative electrode material is greater than or equal to 1.9 g / cm 3 .

[0066] In one embodiment of the present application, the Young's modulus of the negative electrode material is 260MPa-300MPa. The large Young's modulus makes the negative electrode material less likely to deform. This is beneficial to improving the structural stability of the negative electrode material, improving the high compaction performance of the negative electrode material, and further improving the specific capacity of the negative electrode material. The Young's modulus of the negative electrode material is measured by atomic force microscopy. Specifically, the Young's modulus of the negative electrode material may be, but is not limited to, 260MPa, 270MPa, 280MPa, 290MPa or 300MPa, etc. In one embodiment of the present application, the Young's modulus of the negative electrode material may be 260MPa-285MPa. In another embodiment of the present application, the Young's modulus of the negative electrode material may be 280MPa-300MPa.

[0067] In one embodiment of the present application, the negative electrode material further includes carbon particles, which can further improve the conductivity of the negative electrode material. Specifically, the carbon particles can be, but are not limited to, at least one of graphite, soft carbon, hard carbon, carbon black, and graphene. In one embodiment of the present application, the carbon particles can be graphite, which can further improve the conductivity of the negative electrode material and thereby increase the energy density of the negative electrode sheet.

[0068] In one embodiment of the present application, the mass percentage of the carbon particles is 85%-95%. Specifically, the mass percentage of the carbon particles can be, but is not limited to, 85%, 88%, 90%, 92%, 94%, or 95%. In one embodiment of the present application, the mass percentage of the carbon particles can be 85%-90%. In another embodiment of the present application, the mass percentage of the carbon particles can be 90%-95%.

[0069] The present application also provides a method for preparing a negative electrode material, comprising depositing carbon on a porous silicon substrate to form a silicon-carbon core to obtain the negative electrode material; the silicon-carbon core comprises a porous silicon substrate and a carbon material disposed within the porous silicon substrate, and the total pore volume of the silicon-carbon core is less than or equal to 0.0001 ml / g. The preparation method provided in the present application is novel and simple in process, and is conducive to producing a negative electrode material with high mechanical strength, good specific capacity, and low specific surface area. The preparation method can be used to prepare the negative electrode material in any of the above embodiments.

[0070] In one embodiment of the present application, the preparation method of the porous silicon substrate may include, but is not limited to, at least one of a magnesium thermal reduction method, an electrochemical method, a silica sol method, a template method, and a catalyst method to treat the silicon material to obtain a porous silicon substrate. In one embodiment of the present application, the preparation method of the porous silicon substrate may be a magnesium thermal reduction method. Specifically, magnesium powder and silicon material are mixed, calcined at a high temperature under the protection of an inert gas, and then pickled and etched, washed with water multiple times, and then vacuum dried to obtain a porous silicon substrate. In another embodiment of the present application, the preparation method of the porous silicon substrate may be an electrochemical method.

[0071] In one embodiment of the present application, the particle size D50 of the silicon material is 5μm-10μm. The particle size of the silicon material determines the particle size of the porous silicon matrix, which can affect the tap density and compaction density of the negative electrode material. Specifically, the particle size D50 of the silicon material can be, but is not limited to, 5μm, 6μm, 7μm, 8μm, 9μm and 10μm. In one embodiment of the present application, the particle size D50 of the silicon material can be 5μm-8μm. In another embodiment of the present application, the particle size D50 of the silicon material can be 7μm-10μm.

[0072] In one embodiment of the present application, the silicon material includes at least one of elemental silicon, a silicon-carbon material, a silicon-oxygen material, and a silicon alloy. Specifically, the silicon material may include, but is not limited to, at least one of elemental silicon, silicon carbide, silicon tetrachloride, silicon dioxide, silicon oxide, silicon aluminum, ferrosilicon, or silicon manganese. In one embodiment of the present application, the silicon material may be elemental silicon. In another embodiment of the present application, the silicon material may be silicon dioxide.

[0073] Please refer to FIG3, which is a cross-sectional view of a porous silicon substrate provided in one embodiment of the present application. The porous silicon substrate 11 is a porous structure. In one embodiment of the present application, the specific surface area of ​​the porous silicon substrate is greater than or equal to 750 m 2 / g, the larger the specific surface area of ​​the porous silicon substrate, the more pores there are in the porous silicon substrate. The porous silicon substrate has a loose porous structure, which is conducive to the placement of carbon materials. Specifically, the specific surface area of ​​the porous silicon substrate can be, but is not limited to, greater than or equal to 750m 2 / g, greater than or equal to 760m 2 / g, greater than or equal to 770m 2 / g, greater than or equal to 780m 2 / g or greater than or equal to 790m 2 In one embodiment of the present application, the specific surface area of ​​the porous silicon substrate can be greater than or equal to 755 m 2 In another embodiment of the present application, the specific surface area of ​​the porous silicon substrate can be greater than or equal to 770 m 2 / g.

[0074] In one embodiment of the present application, the porous silicon matrix includes micropores, mesopores and macropores, wherein micropores are pores with a pore diameter of less than 2 nm, mesopores are pores with a pore diameter of 2 nm-50 nm, and macropores are pores with a pore diameter greater than 50 nm. In one embodiment of the present application, the volume of micropores in the porous silicon matrix accounts for 70%-80% of the total pore volume of the porous silicon matrix. Specifically, the volume of micropores in the total pore volume of the porous silicon matrix may be, but is not limited to, 70%, 72%, 74%, 75%, 78%, 79% and 80%, etc. In one embodiment of the present application, the volume of micropores in the total pore volume of the porous silicon matrix may be 70%-76%. In another embodiment of the present application, the volume of micropores in the total pore volume of the porous silicon matrix may be 75%-80%. In one embodiment of the present application, the volume of mesopores in the porous silicon matrix accounts for 5%-10% of the total pore volume of the porous silicon matrix. Specifically, the mesopore volume may account for, but is not limited to, 5%, 6%, 7%, 8%, 9% or 10% of the total pore volume of the porous silicon matrix. In one embodiment of the present application, the mesopore volume may account for 5%-8.5% of the total pore volume of the porous silicon matrix. In another embodiment of the present application, the mesopore volume may account for 7.8%-10% of the total pore volume of the porous silicon matrix. In one embodiment of the present application, the macropore volume in the porous silicon matrix accounts for 15%-25% of the total pore volume of the porous silicon matrix. Specifically, the macropore volume may account for, but is not limited to, 15%, 18%, 19%, 20%, 22% or 25% of the total pore volume of the porous silicon matrix. In one embodiment of the present application, the macropore volume may account for, but is not limited to, 15%-21% of the total pore volume of the porous silicon matrix. In another embodiment of the present application, the macropore volume may account for 19%-25% of the total pore volume of the porous silicon matrix.

[0075] In one embodiment of the present application, carbon deposition utilizes a gaseous carbon source. The molecular diameter of the gaseous carbon source is small, which facilitates deposition and filling of the narrow pores of the porous silicon substrate. Specifically, the carbon source for carbon deposition may include, but is not limited to, at least one of methane, ethane, ethylene, propylene, acetylene, and propyne. In one embodiment of the present application, the carbon source for carbon deposition may be methane. In another embodiment of the present application, the carbon source for carbon deposition may be acetylene, which can further deposit and fill the porous silicon substrate, thereby increasing the density of the silicon-carbon core.

[0076] In one embodiment of the present application, the gas flow rate of carbon deposition (i.e., the flow rate of the gaseous carbon source used in the carbon deposition process) is 1L / min-10L / min, which is beneficial to improving the density and mechanical strength of the silicon-carbon core. Specifically, the gas flow rate of carbon deposition can be, but is not limited to, 1L / min, 2L / min, 4L / min, 6L / min, 8L / min or 10L / min, etc. In one embodiment of the present application, the gas flow rate of carbon deposition can be 5L / min-7L / min, which can further improve the deposition of carbon materials in the porous silicon matrix and improve the density of the silicon-carbon core. In another embodiment of the present application, the gas flow rate of carbon deposition can be 4L / min-10L / min.

[0077] In one embodiment of the present application, the carbon deposition time is 10 hours to 15 hours, which helps improve the mechanical strength of the silicon-carbon core. Specifically, the carbon deposition time can be, but is not limited to, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or 15 hours. In one example of the present application, the carbon deposition time can be 10 hours to 14 hours. In another example of the present application, the carbon deposition time can be 13 hours to 15 hours.

[0078] In one embodiment of the present application, the carbon deposition temperature is 400°C-700°C. Specifically, the carbon deposition temperature may be, but is not limited to, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, or 700°C. In one embodiment of the present application, the carbon deposition temperature may be 500°C-700°C, which is beneficial for improving the mechanical strength of the negative electrode material. In another embodiment of the present application, the carbon deposition temperature may be 450°C-550°C.

[0079] In one embodiment of the present application, the carbon deposition apparatus may be, but is not limited to, a rotary kiln, a tubular furnace, or a fluidized bed. In one embodiment of the present application, the carbon deposition apparatus may be a tubular furnace. In another embodiment of the present application, the carbon deposition apparatus may be a fluidized bed, which may further enhance the carbon deposition effect on the porous silicon substrate and increase the density of the silicon-carbon core.

[0080] Please refer to Figure 4, which is a schematic cross-sectional view of a silicon-carbon core according to one embodiment of the present application. The silicon-carbon core 10 comprises a porous silicon substrate 11 and a carbon material 12 disposed within the porous silicon substrate. The carbon material fills the pores of the porous silicon substrate, increasing the density of the silicon-carbon core, reducing the specific surface area of ​​the negative electrode material, and further enhancing the mechanical strength and specific capacity of the negative electrode material, thereby facilitating its widespread application.

[0081] In one embodiment of the present application, carbon deposition is followed by a carbon coating process to form a carbon coating layer on the surface of the silicon-carbon core, which is beneficial for improving the cycle performance of the negative electrode material. Specifically, the carbon source for the carbon coating process may include, but is not limited to, at least one of methane, ethane, ethylene, propylene, acetylene, and propyne. In one embodiment of the present application, the carbon source for the carbon coating process may be methane. In another embodiment of the present application, the carbon source for the carbon coating process may be acetylene.

[0082] In one embodiment of the present application, the gas flow rate of the carbon coating treatment (i.e., the flow rate of the carbon source gas used in the carbon coating treatment process) is 0.05L / min-1L / min, so that a thinner carbon coating layer can be obtained, which not only improves the stability of the negative electrode material, but also maintains the high mechanical properties of the negative electrode material, which is conducive to obtaining a negative electrode material with excellent comprehensive performance. Specifically, the gas flow rate of the carbon coating can be, but is not limited to, 0.05L / min, 0.1L / min, 0.3L / min, 0.6L / min, 0.8L / min or 1L / min, etc. In one embodiment of the present application, the gas flow rate of the carbon coating can be 0.05L / min-0.7L / min. In another embodiment of the present application, the gas flow rate of the carbon coating can be 0.5L / min-1L / min.

[0083] In one embodiment of the present application, the carbon coating treatment time is 0.5h-1h, so that the thickness of the carbon coating layer can be controlled and the electrochemical performance of the negative electrode material can be improved. Specifically, the carbon coating time can be, but is not limited to, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h or 1h. In one embodiment of the present application, the carbon coating time can be 0.5h-0.8h. In another embodiment of the present application, the carbon coating time can be 0.7h-1h.

[0084] In one embodiment of the present application, the temperature of the carbon coating treatment is 400°C-700°C. Specifically, the temperature of the carbon coating treatment may be, but is not limited to, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, or 700°C. In one embodiment of the present application, the temperature of the carbon coating treatment may be 500°C-700°C, which is beneficial for improving the mechanical strength of the negative electrode material. In another embodiment of the present application, the temperature of the carbon coating treatment may be 450°C-550°C.

[0085] In one embodiment of the present application, a negative electrode sheet includes a negative electrode active material layer, which includes the negative electrode material described in any of the above embodiments. The negative electrode sheet provided by the present application, due to its high mechanical strength, good cycle stability, and high specific capacity, improves the cycle life and charge-discharge specific capacity of the negative electrode sheet. Please refer to Figure 5, which is a cross-sectional schematic diagram of a negative electrode sheet provided in one embodiment of the present application. The negative electrode sheet 200 includes a negative electrode current collector 30 and a negative electrode active material layer 40 disposed on the surface of the negative electrode current collector 30. The negative electrode active material layer 40 includes the negative electrode material described in any of the above embodiments. The negative electrode sheet provided by the present application, due to its high mechanical strength, good cycle stability, and high specific capacity, improves the cycle life and charge-discharge specific capacity of the negative electrode sheet. In one embodiment of the present application, the negative electrode current collector may include, but is not limited to, at least one of copper, aluminum, nickel, and stainless steel. In one example of the present application, the negative electrode current collector may be copper foil.

[0086] In one embodiment of the present application, the negative electrode active material layer also includes a binder. The binder can improve the binding ability of the components in the negative electrode active material layer and improve the binding ability between the negative electrode active material layer and the current collector. Specifically, the binder can be, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polybutadiene, acrylic resin, epoxy resin, polyethylene oxide, sodium carboxymethyl cellulose, and styrene-butadiene latex. In one embodiment of the present application, the binder can be polyvinylidene fluoride. In another embodiment of the present application, the binder can be sodium carboxymethyl cellulose. In one embodiment of the present application, the mass ratio of the negative electrode material to the binder is (60-99.9):(0.1-20). Specifically, the mass ratio of the negative electrode material to the binder can be, but is not limited to, 60:1, 60:10, 60:15, 70:5, 75:10, 80:5, 90:3, 99.9:20, etc. In one embodiment of the present application, the mass ratio of the negative electrode material to the binder can be (75-85):(1-3), which can further improve the bonding ability and conductivity of the electrode sheet. In another embodiment of the present application, the mass ratio of the negative electrode material to the binder can be (60-95):(1-5). In yet another embodiment of the present application, the mass ratio of the negative electrode material to the binder can be (90-99.9):(0.1-10).

[0087] In one embodiment of the present application, the negative electrode active material layer further includes a conductive agent, which can increase the conductivity of the negative electrode material and improve the electronic conductivity. Specifically, the conductive agent may include, but is not limited to, at least one of graphite, carbon black, acetylene black and graphene. In one embodiment of the present application, the conductive agent may be graphite. In another embodiment of the present application, the conductive agent may be carbon black. In one embodiment of the present application, the mass ratio of the negative electrode material, the conductive agent and the binder is (60-99.9):(1-20):(0.1-20). Specifically, the mass ratio of the negative electrode material, the conductive agent and the binder may be, but is not limited to, 60:1:0.1, 60:1:1, 70:1:3, 75:5:4, 80:5:6, 60:4:7, 80:10:1, 90:15:10, 95:3:5, 99.9:20:20, etc. In one embodiment of the present application, the mass ratio of the negative electrode material, the conductive agent, and the binder can be (75-85):(1-3):(1-5). In another embodiment of the present application, the mass ratio of the negative electrode material, the conductive agent, and the binder can be (60-95):(1-10):(1-10).

[0088] The present application also provides a battery comprising a positive electrode sheet and a negative electrode sheet provided by any of the above embodiments. The negative electrode sheet has a long cycle life and a high charge-discharge specific capacity. Therefore, the battery provided by the present application has a high capacity and excellent cycle performance, which is conducive to the wide application of the battery.

[0089] In one embodiment of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material. Specifically, the positive electrode current collector may be, but is not limited to, at least one of copper, aluminum, nickel, and stainless steel; the positive electrode active material may be, but is not limited to, at least one of lithium cobalt oxide, lithium manganese oxide, nickel-cobalt-manganese oxide, and nickel-cobalt-aluminum oxide. In one embodiment of the present application, the positive electrode current collector may be aluminum foil, and the positive electrode active material may be lithium cobalt oxide.

[0090] In one embodiment of the present application, as shown in FIG9 , the battery further includes a separator 60 disposed between the positive electrode sheet 50 and the negative electrode sheet 200. Specifically, the separator 60 may be, but is not limited to, a woven membrane, a non-woven fabric, a microporous membrane, a composite membrane, a rolled membrane, or a separator paper. In one embodiment of the present application, the battery further includes an electrolyte. At least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet are immersed in the electrolyte. The electrolyte of the present application is not particularly limited and may be, but is not limited to, any substance that can be used as a battery electrolyte in the art.

[0091] The present application also provides an electric device, as shown in Figure 10, the electric device 80 includes the battery 70 provided by any of the above-mentioned embodiments. The electric device provided by the present application has excellent comprehensive performance and strong market competitiveness. The electric device 80 of the present application may refer to a vehicle, an electronic device, an energy storage system, etc., and the above-mentioned electrochemical device (i.e., the battery 70) may be provided in the electric device in the form of a single cell, a battery module, a battery pack, a capacitor, etc. In one embodiment of the present application, the battery 70 can be used in a vehicle to improve the safety of the vehicle's electricity use. In another embodiment of the present application, the battery 70 can also be used in an electronic device to increase the battery capacity of the electronic device and improve the battery life.

[0092] The effects of the technical solution of this application are further illustrated below through specific examples.

[0093] Example 1

[0094] 40 g of magnesium powder and 50 g of silica powder (particle size D50: 8.15 μm) were weighed, mixed evenly, and placed in a tube furnace. Under argon protection, the temperature was increased to 700°C at a heating rate of 5°C / min. After holding for 5 h, the mixture was naturally cooled to room temperature. The resulting powder was etched in a 1 mol / L hydrochloric acid solution for 5 h, then washed with water three times and dried in a vacuum oven at 80°C to obtain a porous silicon substrate.

[0095] The porous silicon substrate was placed in a fluidized bed, acetylene gas was introduced at a gas flow rate of 6 L / min, and gas-phase carbon deposition was performed at 500 ° C for 12 hours. After the internal pores of the porous silicon substrate were filled, a silicon-carbon core was obtained; then the acetylene gas flow rate was gradually reduced to 0.05 L / min for surface carbon coating, and the carbon coating time was 0.5 hours to obtain the negative electrode material. The prepared porous silicon substrate and negative electrode material were subjected to scanning electron microscopy, and the results are shown in Figures 6 and 7. Figure 6 is a scanning electron microscope (SEM) image of the porous silicon substrate provided in Example 1. Figure 7 is a scanning electron microscope (SEM) image of the negative electrode material provided in Example 1. Combining the data in Tables 1 and 2, it can be seen that the appearance morphology between the porous silicon substrate and the negative electrode material has not changed significantly, but the specific surface area has been greatly reduced, indicating that the gas-phase carbon source is mainly deposited and filled in the pores of the porous silicon substrate, which improves the density of the silicon-carbon core and is beneficial to improving the mechanical strength of the negative electrode material.

[0096] Example 2

[0097] The difference from Example 1 is that the carbon deposition time is 15 hours.

[0098] Example 3

[0099] The difference from Example 1 is that the carbon deposition time is 10 h.

[0100] Example 4

[0101] The difference from Example 1 is that the equipment for carbon deposition is a rotary kiln.

[0102] Example 5

[0103] The difference from Example 1 is that the temperature of carbon deposition is 400°C.

[0104] Example 6

[0105] The difference from Example 1 is that the temperature of carbon deposition is 700°C.

[0106] Example 7

[0107] The difference from Example 1 is that the gas flow rate for carbon deposition is 1 L / min.

[0108] Example 8

[0109] The difference from Example 1 is that the gas flow rate for carbon deposition is 10 L / min.

[0110] Example 9

[0111] The difference from Example 1 is that acetylene gas is replaced by ethylene gas.

[0112] Example 10

[0113] The difference from Example 1 is that no carbon coating treatment is performed.

[0114] Comparative Example 1

[0115] The difference from Example 1 is that the D50 particle size of the silica powder is 3.73 μm.

[0116] Comparative Example 2

[0117] The difference from Example 1 is that the D50 particle size of the silica powder is 11.31 μm.

[0118] Comparative Example 3

[0119] The difference from Example 1 is that the gas flow rate for carbon deposition is 0.5 L / min.

[0120] Comparative Example 4

[0121] The difference from Example 1 is that the gas flow rate for carbon deposition and carbon coating is 0.1 L / min.

[0122] Comparative Example 5

[0123] The difference from Example 1 is that the porous silicon substrate is directly used as the negative electrode material.

[0124] Comparative Example 6

[0125] The difference from Example 1 is that silicon oxide is directly used as the negative electrode material.

[0126] Comparative Example 7

[0127] The difference from Example 1 is that the porous silicon material and the asphalt powder are physically mixed evenly, placed in a tubular furnace, and heated to 1000°C at a heating rate of 5°C / min under argon protection, kept warm for 5 hours, and then naturally cooled to room temperature.

[0128] Comparative Example 8

[0129] The difference from Example 1 is that the specific surface area is about 800m 2 g -1 The porous carbon material was placed in a fluidized bed, monosilane gas was introduced at a gas flow rate of 6 L / min, and vapor phase carbon deposition was performed at 500 ° C. After deposition for 12 hours, the monosilane gas flow rate was gradually reduced, and then the acetylene gas flow rate was gradually reduced to 0.05 L / min for surface carbon coating. The carbon coating time was 0.5 hours to obtain the negative electrode material.

[0130] Performance testing

[0131] According to GB / T 41949-2022, the particle size D50 of the porous silicon substrate and the negative electrode material prepared in Examples 1-10 and Comparative Examples 1-8 was measured using a Mastersizer 3000 laser particle size distribution analyzer; the thickness of the carbon coating layer of the negative electrode material prepared in Examples 1-10 and Comparative Examples 1-8 was measured using a transmission electron microscope (TEM); according to GB / T 19587-2017, the specific surface area of ​​the porous silicon substrate and the negative electrode material prepared in Examples 1-10 and Comparative Examples 1-8 was measured using the BET method; according to GB / T 40066-2021, an atomic force microscope was used to detect the mechanical strength of the porous silicon matrix and the negative electrode material prepared in Examples 1-10 and Comparative Examples 1-8 (the specific method for calculating the Young's modulus is as follows: 1. Select the constant force mode in the AFM and set a certain force constant. 2. Select an area to be tested, and then apply a constant force to the area. 3. Measure the surface deformation of the sample, generally by measuring the vertical displacement of the AFM probe. 4. Calculate the Young's modulus of the area by measuring the force and deformation of the sample), and the results are shown in Tables 1 and 2.

[0132] According to GB / T 19587-2017, the total pore volume of the silicon-carbon cores obtained in Examples 1-10 and Comparative Examples 1-8 was measured using a specific surface area and pore size analyzer (model: 3H-2000PS2), and the results are shown in Table 2. According to GB / T 5162-2021, the tap density of the negative electrode materials obtained in Examples 1-10 and Comparative Examples 1-8 was measured using a powder tap density meter, and the results are shown in Table 2. The negative electrode materials obtained in Examples 1-10 and Comparative Examples 1-8 were mixed with graphite in a mass ratio of 1:9, and then a fixed slurrying process was used to prepare a negative electrode sheet. The fixed negative electrode sheet surface density was 6 mg / cm 2 Under these conditions, the compaction density of the negative electrode sheet was tested, and the results are shown in Table 2.

[0133] The negative electrode materials prepared in Examples 1-10 and Comparative Examples 1-8 were mixed with graphite at a mass ratio of 1:9, and then a fixed pulping process was used to prepare the negative electrode sheets. A 5.2Ah battery was assembled using lithium cobalt oxide as the positive electrode. After formation, it was subjected to high-temperature charge-discharge cycle testing. The high-temperature charge-discharge cycle test conditions were 1C charge and 1C discharge (1C = 5.2A) at 45°C. The thickness expansion rate and capacity retention of the battery after 500 cycles at 45°C were also calculated. The test results are shown in Table 3.

[0134] Figure 8 is a scanning electron microscope (SEM) image of the negative electrode material and the silicon element distribution analysis result diagram of the battery provided in Example 1 after 1000 cycles. It can be seen that after a long period of cycling, the silicon element in the negative electrode material still remains evenly distributed, the negative electrode material does not crack or crush, and the structural stability is high.

[0135] Table 1 Test results of porous silicon substrate performance

[0136] Table 2 Negative electrode material performance test results

[0137] Table 3 Test results of battery performance

[0138] It can be seen that compared with the comparative example, the negative electrode material obtained in the embodiment of the present application has high mechanical strength, the thickness expansion rate of the manufactured battery is low, the capacity retention rate is high, and the comprehensive performance is excellent. According to the test results of Example 1 and Comparative Examples 7-8, due to the narrow pores of the porous silicon substrate, it is difficult to densely fill the porous silicon substrate with simple coating or conventional liquid-phase coating carbon, and vapor-deposited carbon can improve the filling effect of carbon in the porous silicon substrate, and improve the mechanical strength and compaction performance of the negative electrode material. According to the test results of Examples 1-8 and Comparative Examples 1-6, suitable porous silicon particle size, carbon deposition temperature, gas flow rate, time and equipment are conducive to improving the density, mechanical strength and tap density of the negative electrode material, and reducing the thickness expansion rate. According to the test results of Example 1 and Comparative Example 6, the negative electrode material provided by the present application can reduce the thickness expansion rate of the battery and improve the capacity retention rate of the battery during use compared with conventional negative electrode materials. The test results of Examples 1 and 9 indicate that the carbon source has a small gas-phase molecular diameter and low diffusion resistance, which allows it to better fill the narrow pores of the porous silicon matrix, improving the filling efficiency of the porous silicon matrix and facilitating the production of negative electrode materials with high mechanical strength, good tap density, and excellent electrochemical performance. The test results of Examples 1 and 10 indicate that the carbon coating can further improve the capacity retention and structural stability of the negative electrode material.

[0139] The above is a preferred embodiment of the present application, but it should not be construed as limiting the scope of the present application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present application, and such improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A negative electrode material (100), characterized in that The negative electrode material (100) comprises: A silicon-carbon core (10), comprising: porous silicon substrate (11); a carbon material (12), wherein the carbon material (12) is disposed in the pores of the porous silicon substrate (11), The total pore volume of the silicon-carbon core (10) is less than or equal to 0.0001 ml / g.

2. The negative electrode material (100) according to claim 1, characterized in that The particle size D50 of the porous silicon substrate (11) is 5 μm-10 μm; The porous silicon substrate (11) has a plurality of crystal grains, and the size of the crystal grains is less than or equal to 2 nm; The specific surface area of ​​the porous silicon substrate (11) is greater than or equal to 750 m 2 / g; In the porous silicon substrate (11), the micropore volume accounts for 70%-80% of the total pore volume of the porous silicon substrate (11), the mesopore volume accounts for 5%-10% of the total pore volume of the porous silicon substrate (11), and the macropore volume accounts for 15%-25% of the total pore volume of the porous silicon substrate (11).

3. The negative electrode material (100) according to claim 1 or 2, characterized in that In the silicon-carbon core (10), the mass percentage of the porous silicon matrix (11) is 30%-60%, and the mass percentage of the carbon material (12) is 40%-70%.

4. The negative electrode material (100) according to any one of claims 1 to 3, characterized in that The specific surface area of ​​the silicon-carbon core (10) is less than or equal to 10 m 2 / g, and the particle size D50 of the silicon carbon core (10) is 5μm-10μm.

5. The negative electrode material (100) according to any one of claims 1 to 4, characterized in that The negative electrode material (100) further comprises carbon particles, and the mass percentage of the carbon particles in the negative electrode material (100) is 85%-95%.

6. The negative electrode material (100) according to any one of claims 1 to 5, characterized in that The negative electrode material (100) further comprises a carbon coating layer (20), and the carbon coating layer (20) is arranged on the surface of the silicon-carbon core (10).

7. The negative electrode material (100) according to claim 6, characterized in that The thickness of the carbon coating layer (20) is 10 nm to 20 nm; In the negative electrode material (100), the mass percentage of the carbon coating layer (20) is 0.5%-2%, and the coverage rate of the carbon coating layer (20) is 80%-100%.

8. The negative electrode material (100) according to any one of claims 1 to 7, characterized in that The tap density of the negative electrode material (100) is greater than or equal to 0.9 g / cm 3 The compaction density of the negative electrode material (100) is greater than or equal to 1.7 g / cm 3 .

9. The negative electrode material (100) according to any one of claims 1 to 8, characterized in that The Young's modulus of the negative electrode material (100) is 260 MPa-300 MPa.

10. A method for preparing a negative electrode material (100), characterized in that: include: A porous silicon substrate (11) is subjected to carbon deposition to form a silicon-carbon core (10), thereby obtaining a negative electrode material (100); the silicon-carbon core (10) comprises the porous silicon substrate (11) and a carbon material (12) disposed in pores of the porous silicon substrate (11); and the total pore volume of the silicon-carbon core (10) is less than or equal to 0.0001 ml / g.

11. The preparation method according to claim 10, characterized in that The gas flow rate of the carbon deposition is 1 L / min-10 L / min, the time of the carbon deposition is 10 h-15 h, and the temperature of the carbon deposition is 400° C.-700° C.

12. The preparation method according to claim 10 or 11, characterized in that: The preparation method further comprises: The silicon-carbon core (10) is subjected to carbon coating treatment to form a carbon coating layer (20) on the surface of the silicon-carbon core (10), thereby obtaining the negative electrode material (100).

13. The preparation method according to any one of claims 10 to 12, characterized in that: The gas flow rate of the carbon coating treatment is 0.05 L / min-1 L / min, the time of the carbon coating treatment is 0.5 h-1 h, and the temperature of the carbon coating treatment is 400° C.-700° C.

14. A negative electrode plate, characterized in that: The negative electrode plate comprises a negative electrode active material layer (40), and the negative electrode active material layer (40) comprises the negative electrode material (100) according to any one of claims 1 to 9 or the negative electrode material (100) prepared by the preparation method according to any one of claims 10 to 13.

15. A battery (70), characterized in that The battery comprises a positive electrode sheet (50) and a negative electrode sheet (200) as claimed in claim 14.

16. An electrical device (80), characterized in that: The electric device (80) includes the battery (70) according to claim 15.

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