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 graphite and a porous carbon coating layer that coats the surface of the graphite, wherein the porous carbon coating layer comprises non-metallic elements except carbon.

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 29, 2024, with application number 202410381437.8 and application name “Negative Electrode Materials, Preparation Methods and Applications Thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

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

[0003] Currently, battery charging speed has become a hot topic in the battery industry. Anode materials are a key factor influencing battery fast-charging performance. Graphite, with its excellent reversibility, safety, and low cost, is a widely used anode material in batteries. However, during fast charging, graphite anodes often cannot withstand excessive currents, leading to metal precipitation and the formation of large amounts of byproducts, reducing their fast-charging capabilities.

[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 porous carbon coating layer of the negative electrode material has non-metallic elements other than carbon elements, which increases the number of ion transmission pathways, shortens the ion diffusion path, and improves the rate performance and fast charging performance of the negative electrode material, which is conducive to shortening the charging time of the battery and increasing the charging rate of the battery.

[0006] In a first aspect, the present application discloses a negative electrode material, which includes graphite and a porous carbon coating layer coated on the surface of the graphite, wherein the porous carbon coating layer has a non-metallic element other than carbon.

[0007] Optionally, the specific surface area of ​​the negative electrode material is greater than 900m 2 / g.

[0008] Optionally, the porous carbon coating layer has pores, and the pores have a pore diameter of 0.5 nm-1 nm.

[0009] Optionally, the non-metallic element includes at least one of nitrogen, phosphorus, sulfur and boron.

[0010] Optionally, the mass percentage of the non-metallic element in the porous carbon coating layer is 10%-15%.

[0011] Optionally, the non-metallic element includes nitrogen, and the nitrogen in the negative electrode material exists in a form including at least one of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen.

[0012] Optionally, the mass ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the graphitic nitrogen is (3-4): (3-4): (2-3).

[0013] Optionally, in the X-ray photoelectron spectrum of the negative electrode material, the characteristic peak of the pyridinic nitrogen is located at 398.1eV-399.3eV, the characteristic peak of the pyrrolic nitrogen is located at 399.8eV-401.2eV, and the characteristic peak of the graphitic nitrogen is located at 401.1eV-408.7eV.

[0014] Optionally, the characteristic peak area ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the graphitic nitrogen is (3-4): (3-4): (2-3).

[0015] Optionally, in the Raman spectrum of the negative electrode material, the G peak is located at 1570 cm -1 -1585cm -1 , D peak is located at 1320cm -1 -1350cm -1 .

[0016] Optionally, the area ratio of the G peak to the D peak is (0.9-1.1):1.

[0017] Optionally, when the non-metallic element includes nitrogen, the shape of the negative electrode material includes at least one of a dodecahedron structure, a cube, a sphere, and a tube.

[0018] Optionally, in the negative electrode material, the mass ratio of the graphite to the porous carbon coating layer is (8-9):(1-2).

[0019] Optionally, the particle size D50 of the negative electrode material is 13 μm-17 μm.

[0020] Optionally, the thickness of the porous carbon coating layer is 0.5 μm-1 μm.

[0021] The negative electrode material provided in the present application has a porous carbon coating layer having non-metallic elements other than carbon, which increases the number of ion transmission pathways, shortens the ion diffusion path, and improves the rate performance of the negative electrode material.

[0022] In a second aspect, the present application discloses a method for preparing a negative electrode sheet, comprising:

[0023] Mixing a porous carbon coating layer precursor and graphite to obtain a negative electrode material precursor;

[0024] The negative electrode material precursor is sintered to obtain a negative electrode material, wherein the negative electrode material comprises graphite and a porous carbon coating layer coated on the surface of the graphite, wherein the porous carbon coating layer contains non-metallic elements other than carbon.

[0025] Optionally, the porous carbon coating layer precursor includes a first precursor and a second precursor.

[0026] Optionally, the first precursor includes non-metallic organic matter.

[0027] Optionally, the non-metallic organic compound includes at least one of 2-methylimidazole, 2-ethylimidazole, 4,5-dichloroimidazole, pyrazole, triazole and benzimidazole.

[0028] Optionally, the second precursor includes a metal salt.

[0029] Optionally, the metal salt includes at least one of zinc nitrate hexahydrate, zinc acetate and zinc sulfate.

[0030] Optionally, the molar ratio of the first precursor to the second precursor is (2-2.4):1.

[0031] Optionally, the mass ratio of the porous carbon coating layer precursor to the graphite is (8-10):(92-90).

[0032] Optionally, the porous carbon coating layer precursor includes a metal-organic framework compound.

[0033] The preparation method of the negative electrode material provided in the present application is novel, the preparation process is simple, the preparation cost is low, and the prepared negative electrode material has high conductivity and good rate performance.

[0034] In a third aspect, the negative electrode plate 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.

[0035] The negative electrode plate provided in this application has good rate performance and fast charging performance, high conductivity, good safety, and excellent electrochemical performance.

[0036] In a fourth aspect, the present application provides a battery, comprising the negative electrode sheet described in the third aspect.

[0037] The battery provided in this application has excellent electrochemical performance, long service life, and can be quickly charged, which is conducive to the wide application of the battery.

[0038] In a fifth aspect, the present application provides an electrical device, which includes the battery described in the fourth aspect.

[0039] The electrical equipment provided in this application has a high charging rate and good safety performance, which is conducive to the industrial application of electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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.

[0041] FIG1 is a schematic cross-sectional view of a negative electrode material provided in one embodiment of the present application.

[0042] FIG2 is a flow chart of the preparation of the negative electrode material provided in one embodiment of the present application.

[0043] FIG3 is a schematic cross-sectional view of a negative electrode sheet provided in one embodiment of the present application.

[0044] FIG4 is a Raman spectrum of the negative electrode material provided in Example 1 of the present application.

[0045] FIG5 is an adsorption isotherm curve of the negative electrode material provided in Example 1 of the present application.

[0046] FIG6 is a pore size characterization of the negative electrode material provided in Example 1 of the present application.

[0047] FIG7 is a scanning electron microscope image of the negative electrode material provided in Example 1 of the present application.

[0048] FIG8 is a scanning electron microscope image of the negative electrode material provided in Example 1 of the present application. DETAILED DESCRIPTION

[0049] 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.

[0050] The present application provides a negative electrode material. Please refer to Figure 1, which shows the negative electrode material provided in one embodiment of the present application. The negative electrode material 10 includes graphite 11 and a porous carbon coating layer 12 coated on the surface of the graphite 11. The porous carbon coating layer 12 has non-metallic elements. The graphite in the negative electrode material can provide ion deintercalation sites, thereby improving the conductivity and specific capacity of the negative electrode material and reducing the preparation cost of the negative electrode material; the porous carbon coating layer improves the conductivity of the negative electrode material; the porous carbon coating layer has non-metallic elements other than carbon, which increases the number of defects in the porous carbon coating layer, shortens the diffusion path of the ions, increases the number of diffusion pathways for the ions, improves the ionic conductivity and electronic conductivity, and is beneficial to improving the rate performance and fast charging performance of the negative electrode material.

[0051] In this application, graphite has a layered structure, which can increase the number of ions inserted and removed, thereby improving the specific capacity of the negative electrode material. Graphite has good electrical conductivity, which is beneficial for improving the conductivity of the negative electrode material. Graphite is low in cost, which is beneficial for reducing the production cost of the negative electrode material. In one embodiment of this application, the graphite may include, but is not limited to, at least one of natural graphite and artificial graphite. In one embodiment of this application, the graphite may be natural graphite. In another embodiment of this application, the graphite may be artificial graphite.

[0052] In the present application, graphite primary particles, and / or secondary particles formed by agglomeration of multiple primary particles. In one embodiment of the present application, the particle size D50 of the graphite is 13μm-17μm. Specifically, the particle size D50 of the graphite may be, but is not limited to, 13μm, 13.5μm, 14μm, 14.5μm, 15μm, 16μm or 17μm, etc. In one embodiment of the present application, the particle size D50 of the graphite may be 13μm-15μm. In another embodiment of the present application, the particle size D50 of the graphite may be 14μm-17μm.

[0053] In one embodiment of the present application, the mass percentage of graphite in the negative electrode material is 80%-90%. An appropriate mass percentage of graphite can increase the specific capacity of the negative electrode material, thereby increasing the energy density of the negative electrode sheet. Specifically, the mass percentage of graphite in the graphite material can be, but is not limited to, 80%, 82%, 84%, 86%, 88%, or 90%. In one embodiment of the present application, the mass percentage of graphite in the negative electrode material can be 80%-86%. In another embodiment of the present application, the mass percentage of graphite in the negative electrode material can be 85%-90%.

[0054] In the present application, the porous carbon coating layer has a plurality of holes, which increases the specific surface area of ​​the negative electrode material and increases the number of ion transmission channels, which is beneficial to improving the electrochemical performance of the negative electrode material. In one embodiment of the present application, the pore size is 0.5nm-1nm, which can improve the adsorption capacity of the porous carbon coating layer and thus improve the ion transmission speed of the negative electrode material. Specifically, the pore size can be, but is not limited to, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm or 1nm. In one embodiment of the present application, the pore size can be 0.5nm-0.85nm. In another embodiment of the present application, the pore size can be 0.7nm-1nm.

[0055] In one embodiment of the present application, the thickness of the porous carbon coating layer is 0.5 μm-1 μm. The porous carbon coating layer can improve the conductivity of the negative electrode material. Specifically, the thickness of the porous carbon coating layer can be, but is not limited to, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm. In one embodiment of the present application, the thickness of the porous carbon coating layer can be 0.5 μm-0.8 μm. In another embodiment of the present application, the thickness of the porous carbon coating layer can be 0.7 μm-1 μm.

[0056] In one embodiment of the present application, in the negative electrode material, the mass percentage of the porous carbon coating layer is 10%-20%. An appropriate amount of porous carbon coating layer can improve the conductivity and safety of the negative electrode material. Specifically, in the negative electrode material, the mass percentage of the porous carbon coating layer can be, but is not limited to, 10%, 12%, 14%, 16%, 18% or 20%, etc. In one embodiment of the present application, in the negative electrode material, the mass percentage of the porous carbon coating layer can be 10%-18%. In another embodiment of the present application, in the negative electrode material, the mass percentage of the porous carbon coating layer can be 15%-20%.

[0057] In the present application, the porous carbon coating layer contains non-metallic elements other than carbon, which can effectively adjust the physical and chemical properties of the porous carbon coating layer. The non-metallic elements are evenly distributed in the porous carbon coating layer, so that more defective holes are generated on the surface of the porous carbon coating layer, which can shorten the diffusion path of ions, increase the number of ion diffusion channels, and improve ion conductivity. The non-metallic elements are doped in the porous carbon coating layer, which changes the electron cloud distribution around the porous carbon coating layer, improves the electronic conductivity of the porous carbon coating layer, and is conducive to improving the fast charging performance and rate performance of the negative electrode material.

[0058] In one embodiment of the present application, the non-metallic element may include, but is not limited to, at least one of nitrogen, phosphorus, sulfur, and boron. In one example of the present application, the non-metallic element may be nitrogen, which can further improve the conductivity and rate capability of the negative electrode material. In another example of the present application, the non-metallic element may be phosphorus.

[0059] In one embodiment of the present application, a carbon-non-metallic element covalent bond is formed between the carbon element and the non-metallic element in the porous carbon coating layer, thereby enhancing the synergistic effect between the carbon element and the non-metallic element, and facilitating improved conductivity and rate performance of the negative electrode material. In one embodiment of the present application, a doping element XX covalent bond is formed in the porous carbon coating layer (XX covalent bond includes but is not limited to a covalent bond formed between any two of carbon, oxygen, nitrogen, sulfur, boron, phosphorus, etc.).

[0060] In one embodiment of the present application, when the non-metallic element is nitrogen, that is, the porous carbon coating layer contains nitrogen, which is evenly distributed on the surface of the porous carbon coating layer. Nitrogen has an atomic size close to that of carbon atoms and has five valence electrons, which easily forms strong valence bonds with carbon atoms. This increases the number of defects on the surface of the porous carbon coating layer, shortens the ion diffusion path of the negative electrode material, and improves the conductivity of the negative electrode material, thereby facilitating improved fast charging performance and rate performance of the battery.

[0061] In one embodiment of the present application, the mass percentage of non-metallic elements in the porous carbon coating layer is 10%-15%. The mass percentage of non-metallic elements can be measured by elemental analysis and energy dispersive X-ray spectrometry (EDS). Specifically, the mass percentage of non-metallic elements in the porous carbon coating layer can be, but is not limited to, 10%, 11%, 12%, 13%, 14% or 15%, etc. In one embodiment of the present application, the mass percentage of non-metallic elements in the porous carbon coating layer can be 10%-14%. In another embodiment of the present application, the mass percentage of non-metallic elements in the porous carbon coating layer can be 13%-15%. In some embodiments, the content of non-metallic elements can be measured by an elemental analyzer, and based on different physical and chemical methods, the non-metallic elements in the sample are separated, enriched and detected to obtain the content of non-metallic elements. The working principle is as follows: In a high-temperature combustion furnace, a nitrogen-containing sample is oxidized and burned at high temperature to produce nitrogen, nitrogen oxides, carbon dioxide and water. During this process, the organic elements in the sample are converted into corresponding gaseous oxides; the gas generated by combustion enters the separation and detection unit under the push of the carrier gas. After the adsorption column adsorbs and retains the non-nitrogen element compounds, the nitrogen oxides are reduced to nitrogen gas and then measured by the detector. The oxides of other elements are then separated and measured in the order of carbon and hydrogen through the adsorption and desorption effect of the adsorption-desorption column, and the content of different elements can be obtained.

[0062] In one embodiment of the present application, when the non-metallic element includes nitrogen, the nitrogen in the negative electrode material exists in a form including at least one of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen.

[0063] In one embodiment of the present application, when the porous carbon coating layer includes nitrogen, the nitrogen element exists in the form of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen. In the electron distribution of the nitrogen atom, the five electrons in the outer layer can form a strong valence bond with the porous carbon coating layer and have a high binding ability; two of the electrons form a σ bond with the porous carbon coating layer, the other two electrons form a lone electron pair, and the fifth electron is a π orbital lone pair electron. Pyridinic nitrogen is usually located at the edge of the porous carbon coating layer. Due to the presence of the π orbital lone pair electrons, pyridinic nitrogen can become an electron acceptor and interact with the metal component; pyrrolic nitrogen is unstable and gradually transforms into nitrogen oxides and graphitic nitrogen under the influence of temperature; graphitic nitrogen has five outer electrons, four of which can form σ bonds and π bonds, and the fifth electron is in the higher energy π* orbital, allowing graphitic nitrogen to become an electron donor.

[0064] In one embodiment of the present application, the mass ratio of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen is (3-4): (3-4): (2-3). Specifically, the mass ratio of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen can be, but is not limited to, 3:3:2, 3.2:3.2:2.2, 3.5:3.5:2.5, 3.6:3.6:2.6, 3.8:3.6:2.7, 3.8:3.8:2.8 or 4:4:3, etc. In one embodiment of the present application, the mass ratio of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen can be (3-3.7): (3-3.6): (2-2.5). In another embodiment of the present application, the mass ratio of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen can be (3.4-4): (3.5-4): (2.4-3).

[0065] X-ray photoelectron spectroscopy is an important basis for characterizing the non-metallic element doped porous carbon coating. In one embodiment of the present application, when the non-metallic element is nitrogen, in the X-ray photoelectron spectrum of the negative electrode material, the characteristic peak position of the nitrogen element is about 400eV, and the characteristic peak position of the carbon element is about 284eV. The presence form of the nitrogen element in the porous carbon coating can be judged from the ratio of the peak intensities of the characteristic peaks of the nitrogen element and the carbon element. The presence form of the nitrogen element can be further subdivided according to the characteristic peak of the nitrogen element in the X-ray photoelectron spectrum. In one embodiment of the present application, in the X-ray photoelectron spectrum of the negative electrode material, the characteristic peak of pyridine nitrogen is located at 398.1eV-399.3eV, the characteristic peak of pyrrole nitrogen is located at 399.8eV-401.2eV, and the characteristic peak of graphite nitrogen is located at 401.1eV-408.7eV.

[0066] In one embodiment of the present application, in the X-ray photoelectron spectrum of the negative electrode material, the characteristic peak area ratio of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen is (3-4): (3-4): (2-3). Specifically, the characteristic peak area ratio of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen can be, but is not limited to, 3:3:2, 3.2:3.2:2.2, 3.5:3.5:2.5, 3.6:3.6:2.6, 3.8:3.6:2.7, 3.8:3.8:2.8 or 4:4:3, etc. In one embodiment of the present application, the characteristic peak area ratio of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen can be (3-3.7): (3-3.6): (2-2.5). In another embodiment of the present application, the characteristic peak area ratio of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen can be (3.4-4): (3.5-4): (2.4-3).

[0067] In one embodiment of the present application, in the Raman spectrum of the negative electrode material, the D peak and the G peak are both characteristic peaks of carbon atoms. The D-peak represents the defect of the carbon atom, and the characteristic peak position is about 1350 cm -1 The G peak represents the in-plane stretching vibration of the sp2 hybridized carbon atom, and the characteristic peak position is about 1580 cm -1 Whether there is doping of non-metallic elements can be determined by the intensity ratio of the characteristic peaks of D peak and G peak and the shift of the characteristic peak positions.

[0068] In one embodiment of the present application, in the Raman spectrum of the negative electrode material, the characteristic peak of pyridine nitrogen is the G peak, which is located at 1570 cm -1 -1585cm -1 Specifically, the position of the G peak can be, but is not limited to, 1570 cm -1 、1572cm -1 、1575cm -1 、1578cm -1 、1580cm -1 、1582cm -1 or 1585cm -1 In one embodiment of the present application, the position of the G peak can be 1570 cm -1 -1580cm -1 In another embodiment of the present application, the position of the G peak can be 1575 cm -1 -1585cm -1 .

[0069] In one embodiment of the present application, in the Raman spectrum of the negative electrode material, the characteristic peak of pyrrole nitrogen is the D peak, which is located at 1320 cm -1 -1350cm -1 Specifically, the position of the D peak can be, but is not limited to, 1320 cm -1 、1325cm-1 、1330cm -1 、1335cm -1 、1340cm -1 、1345cm -1 or 1350cm -1 In one embodiment of the present application, the position of the D peak may be 1320 cm -1 -1340cm -1 In another embodiment of the present application, the position of the D peak can be 1335 cm -1 -1350cm -1 .

[0070] In one embodiment of the present application, the area ratio of the G peak to the D peak is (0.9-1.1):1. Specifically, the area ratio of the G peak to the D peak may be, but is not limited to, 0.9:1, 0.92:1, 0.95:1, 0.98:1, 1:1, 1.05:1, or 1.1:1. In one embodiment of the present application, the area ratio of the G peak to the D peak may be (0.9-1):1. In another embodiment of the present application, the area ratio of the G peak to the D peak may be (1-1.1):1.

[0071] In one embodiment of the present application, the shape of the negative electrode material may include, but is not limited to, at least one of a dodecahedron, a cube, a sphere, and a tube. In one embodiment of the present application, the negative electrode material may include a dodecahedron structure, which increases the specific surface area of ​​the negative electrode material, further improving the mass transfer efficiency and load capacity of the negative electrode material, and facilitating improved electrochemical performance and stability of the negative electrode sheet. In the present application, the micromorphology of the negative electrode material may be tested using a scanning electron microscope.

[0072] In one embodiment of the present application, in the negative electrode material, the mass ratio of graphite to the porous carbon coating layer is (8-9): (2: 1). Specifically, the mass ratio of graphite to the porous carbon coating layer can be, but is not limited to, 8: 2, 8.2: 1.8, 8.5: 1.5, 8.8: 1.2 or 9: 1, etc. In one embodiment of the present application, the mass ratio of graphite to the porous carbon coating layer can be (8-8.6): (1-1.7). In another embodiment of the present application, the mass ratio of graphite to the porous carbon coating layer can be (8.5-9): (1.5-2).

[0073] In one embodiment of the present application, the particle size D50 of the negative electrode material is 13 μm-17 μm. Specifically, the particle size D50 of the negative electrode material may be, but is not limited to, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 16 μm, or 17 μm. In one embodiment of the present application, the particle size D50 of the negative electrode material may be 13 μm-15 μm. In another embodiment of the present application, the particle size D50 of the negative electrode material may be 14 μm-17 μm.

[0074] In one embodiment of the present application, the specific surface area of ​​the negative electrode material is greater than or equal to 900 m 2 / g, the higher the specific surface area of ​​the negative electrode material, the higher the mass transfer capacity of the negative electrode material, which is beneficial to improving the energy density of the negative electrode sheet. In one embodiment of the present application, the BET specific surface area of ​​the negative electrode material is greater than or equal to 900m 2 / g, specifically, the specific surface area of ​​the negative electrode material may be, but is not limited to, greater than or equal to 900 m 2 / g, greater than or equal to 950m 2 / g, greater than or equal to 1000m 2 / g, greater than or equal to 1050m 2 / g, greater than or equal to 1100m 2 / g, greater than or equal to 1100m 2 / g or greater than or equal to 1200m 2 In another embodiment of the present application, the Langmuir specific surface area of ​​the negative electrode material is greater than or equal to 1200 m 2 / g, the higher the specific surface area, the better the mass transfer capacity of the negative electrode material, which is beneficial to improving the energy density of the negative electrode sheet. Specifically, the Langmuir specific surface area of ​​the negative electrode material can be, but is not limited to, greater than or equal to 1200m 2 / g, greater than or equal to 1250m 2 / g, greater than or equal to 1300m 2 / g, greater than or equal to 1350m 2 / g, greater than or equal to 1400m 2 / g, greater than or equal to 1450m 2 / g or greater than or equal to 1500m 2 / g, etc. In some embodiments, the Langmuir specific surface area is derived from the monolayer adsorption theory, which assumes that surface adsorption is localized adsorption of a monolayer, the surface is uniform, and there is no interaction between molecules in the adsorption layer. In this case, the Langmuir adsorption isotherm equation is P / V = 1 / V m ×b+1 / V m ×P, where P is the nitrogen pressure, V is the actual adsorption amount, V m is the monolayer adsorption saturation capacity, b is a constant related to the adsorption heat; the actual nitrogen adsorption capacity V is measured at different nitrogen pressures P, and a straight line is obtained by plotting the Langmuir equation. The reciprocal of the slope of the straight line is the monolayer adsorption capacity V m , and then calculate the specific surface area, also known as the Langmuir specific surface area.

[0075] Please refer to FIG2 , which is a flow chart of the preparation of the negative electrode material provided in one embodiment of the present application, including:

[0076] S101: mixing a porous carbon coating layer precursor and graphite to obtain a negative electrode material precursor;

[0077] S102: Sintering the negative electrode material precursor to obtain the negative electrode material.

[0078] The present application provides a novel preparation method with a simple preparation process and low preparation cost. The prepared negative electrode material has high conductivity and good rate performance. The negative electrode material described in any of the above embodiments can be prepared by this method.

[0079] In one embodiment of the present application, the porous carbon coating layer precursor includes a first precursor and a second precursor, which can form a porous carbon coating layer. The present application adopts a solvent thermal method to synthesize the porous carbon coating layer. The raw materials are easily available, the operation is simple, and large-scale production is easy to achieve. Specifically, the first precursor includes a non-metallic organic matter, which can improve the conductivity of the negative electrode material. The non-metallic organic matter is a non-metal-doped carbon five-membered ring, which can expose rich non-metal active sites, increase the number of defects in the porous carbon coating layer, and improve the conductivity of the negative electrode material. Exemplarily, the non-metallic organic matter can include, but is not limited to, at least one of 2-methylimidazole, 2-ethylimidazole, 4,5-dichloroimidazole, pyrazole, triazole and benzimidazole. In one embodiment of the present application, when the first precursor is a non-metallic organic matter, the first precursor can be 2-methylimidazole. In another embodiment of the present application, when the first precursor is a non-metallic organic matter, the first precursor can be dichloroimidazole.

[0080] In one embodiment of the present application, the second precursor includes a metal salt. Exemplarily, the metal salt may be, but is not limited to, at least one of zinc nitrate hexahydrate, zinc acetate, and zinc sulfate. Zinc salts have a low boiling point and are easily volatilized during the sintering process, which is beneficial for improving the purity of the negative electrode material and reducing the adverse effects of excessive element doping. In one embodiment of the present application, when the second precursor is a metal salt, the second precursor may be zinc sulfate. In another embodiment of the present application, when the second precursor is a metal salt, the second precursor may be zinc acetate.

[0081] In one embodiment of the present application, the molar ratio of the first precursor and the second precursor is (2-2.4): 1. An appropriate molar ratio of the first precursor and the second precursor can promote the synthesis of the negative electrode material and improve the electrochemical performance of the negative electrode material. Specifically, the molar ratio of the first precursor and the second precursor can be, but is not limited to, 2: 1, 2.05: 1, 2.1: 1, 2.15: 1, 2.2: 1, 2.25: 1, 2.3: 1, 2.35: 1 or 2.4: 1, etc. In one embodiment of the present application, the molar ratio of the first precursor and the second precursor can be (2-2.3): 1. In another embodiment of the present application, the molar ratio of the first precursor and the second precursor can be (2.2-2.4): 1.

[0082] In one embodiment of the present application, the mass ratio of the porous carbon coating layer precursor and the graphite is (8-10): (90-92). Specifically, the mass ratio of the porous carbon coating layer precursor, the graphite and the solvent may be, but is not limited to, 8:90, 8.5:90.5, 8.8:90.8, 9:91, 9.5:91.5, 9.8:91.8 or 10:92, etc. In one embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, the graphite and the solvent may be (8-9): (90-91). In another embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, the graphite and the solvent may be (9-10): (90.5-92).

[0083] In one embodiment of the present application, a porous carbon coating layer precursor, graphite, and a solvent are mixed. The solvent can facilitate the synthesis of the negative electrode material precursor. Specifically, the solvent can be, but is not limited to, at least one of deionized water, methanol, and ethanol. In one embodiment of the present application, the solvent can be a mixed solution of methanol and deionized water. In another embodiment of the present application, the solvent can be deionized water.

[0084] In one embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, graphite and solvent is (8-10): (90-92): (200-400). Specifically, the mass ratio of the porous carbon coating layer precursor, graphite and solvent can be, but is not limited to, 8:90:200, 8.5:90.5:250, 8.8:90.8:290, 9:91:300, 9.5:91.5:320, 9.8:91.8:350 or 10:92:400, etc. In one embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, graphite and solvent can be (8-9): (90-91): (200-300). In another embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, graphite and solvent can be (9-10): (90.5-92): (250-400).

[0085] In one embodiment of the present application, the precursor of the negative electrode material includes graphite and a metal-organic framework compound (MOFs) coated on the surface of the graphite. The metal-organic framework compound is formed by the reaction of a first precursor and a second precursor, and is a crystalline porous material formed by organic or inorganic ligands and metals connected by coordination bonds. It has a controllable pore structure. After sintering, a porous carbon coating layer containing non-metallic elements is formed on the surface of the graphite, which is beneficial to increase the specific surface area and structural stability of the negative electrode material, thereby increasing the energy density of the negative electrode sheet. The micromorphology of the negative electrode material is determined by the micromorphology of the metal-organic framework compound. Specifically, the metal-organic framework compound may be, but is not limited to, at least one of zinc-2-ethylimidazole (Zn(eim)2), zinc-dehydrobenzimidazole (Zn(bim)2), zinc-pyrazole (Zn(pz)2), zinc-3-amino-1,2,4-triazole (Zn5(AmTAZ)6), zinc-imidazole-2-carboxaldehyde (Zn(ica)2), and zinc-1,2,4-triazole (Zn2(trz)4). In one embodiment of the present application, the material of the porous carbon coating layer may be zinc-2-ethylimidazole (Zn(eim)2). In another embodiment of the present application, the material of the porous carbon coating layer may be zinc-imidazole-2-carboxaldehyde (Zn(ica)2).

[0086] In one embodiment of the present application, the present application also provides a method for preparing a negative electrode material, comprising: mixing a first precursor and a first solvent to form a first mixed solution; mixing a second precursor, graphite, and a second solvent to form a second mixed solution; mixing the first mixed solution and the second mixed solution to obtain a mixed solution, drying the mixed solution to obtain a negative electrode material precursor, and sintering the negative electrode material precursor to obtain a negative electrode material. This can improve the preparation efficiency of the negative electrode material and is conducive to the industrial application of the negative electrode material. In some embodiments, the first solvent and the second solvent are independently selected from at least one of deionized water, methanol, and ethanol. For example, the first solvent can be deionized water and the second solvent can be methanol.

[0087] In one embodiment of the present application, the mass ratio of the first precursor to the first solvent is 1:(10-50). An appropriate mass ratio of the first precursor to the first solvent can improve the dispersibility of the first precursor in the first mixed solution and promote the formation of the negative electrode material. Specifically, the mass ratio of the first precursor to the first solvent can be, but is not limited to, 1:10, 1:20, 1:30, 1:40 or 1:50, etc. In one embodiment of the present application, the mass ratio of the first precursor to the first solvent can be 1:(10-40). In another embodiment of the present application, the mass ratio of the first precursor to the first solvent can be 1:(30-50).

[0088] In one embodiment of the present application, the mass ratio of the second precursor, graphite, and the second solvent is 10:90:(100-500). Specifically, the mass ratio of the second precursor, graphite, and the second solvent may be, but is not limited to, 10:90:100, 10:90:200, 10:90:300, 10:90:400, or 10:90:500. In one embodiment of the present application, the mass ratio of the second precursor, graphite, and the second solvent may be 10:90:(100-300). In another embodiment of the present application, the mass ratio of the second precursor, graphite, and the second solvent may be 10:90:(250-500).

[0089] In one embodiment of the present application, the stirring time of the mixed solution is 10 hours to 15 hours, which can accelerate the reaction process and increase the reaction rate. Specifically, the stirring time of the mixed solution can be, but is not limited to, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or 15 hours. In one embodiment of the present application, the stirring time of the mixed solution can be 12 hours, which can further accelerate the reaction rate. In another embodiment of the present application, the stirring time of the mixed solution can be 13 hours to 15 hours.

[0090] In one embodiment of the present application, the sintering temperature is 600°C-800°C. Specifically, the sintering temperature may be, but is not limited to, 600°C, 650°C, 680°C, 690°C, 700°C, 720°C, 750°C, 780°C, or 800°C. In one embodiment of the present application, the sintering temperature may be 600°C-780°C. In another embodiment of the present application, the sintering temperature may be 690°C-800°C.

[0091] In one embodiment of the present application, the sintering time may be 1 hour to 4 hours. Specifically, the sintering time may be, but is not limited to, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours. In one embodiment of the present application, the sintering time may be 2 hours, which may promote the synthesis of the negative electrode material. In another embodiment of the present application, the sintering time may be 2.5 hours to 4 hours.

[0092] In one embodiment of the present application, the sintering atmosphere is an inert gas to prevent the negative electrode material from being oxidized by environmental contamination. Specifically, the sintering atmosphere may include, but is not limited to, at least one of argon, helium, neon, and nitrogen. In one embodiment of the present application, the sintering atmosphere may be argon. In another embodiment of the present application, the sintering atmosphere may be nitrogen.

[0093] The present application also provides a negative electrode plate, comprising a negative electrode active material layer, wherein the negative electrode active material comprises the negative electrode material described in any of the above embodiments. Due to the high specific surface area, good conductivity, and excellent rate capability of the negative electrode material, the negative electrode plate has good fast charging performance and excellent overall electrochemical performance.

[0094] Please refer to Figure 3, which is a cross-sectional schematic diagram of a negative electrode sheet according to one embodiment of the present application. The negative electrode sheet 100 includes a negative electrode current collector 20 and a negative electrode active material layer 30 disposed on the surface of the negative electrode current collector 20. 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.

[0095] In one embodiment of the present application, the thickness of the negative electrode current collector is 5 μm to 15 μm. Specifically, the thickness of the negative electrode current collector may be, but is not limited to, 5 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, or 15 μm. In one embodiment of the present application, the thickness of the negative electrode current collector may be 5 μm to 10 μm. In another embodiment of the present application, the thickness of the negative electrode current collector may be 9 μm to 15 μm.

[0096] In one embodiment of the present application, the negative electrode active material layer further includes a negative electrode conductive agent to enhance the conductivity of the negative electrode plate. Specifically, the negative electrode conductive agent may be, but is not limited to, at least one of carbon black, acetylene black, artificial graphite, carbon nanotubes, and graphene. In one embodiment of the present application, the negative electrode conductive agent may be acetylene black. In another embodiment of the present application, the negative electrode conductive agent may be graphene.

[0097] In one embodiment of the present application, the negative electrode active material layer further includes a negative electrode binder, which can improve the bonding between the negative electrode active material layer and the negative electrode current collector, thereby improving the structural stability of the negative electrode sheet. Specifically, the negative electrode binder can be, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose, styrene butadiene rubber, and polyimide. In one embodiment of the present application, the negative electrode binder can be polyvinylidene fluoride. In another embodiment of the present application, the negative electrode binder can be carboxymethyl cellulose.

[0098] In one embodiment of the present application, the mass ratio of the negative electrode material, the negative electrode conductive agent, and the negative electrode binder is (100-105): (1-2): (4-5), which can promote the binding ability of the components in the negative electrode active material layer and improve the conductivity and rate performance of the negative electrode sheet. Specifically, the mass ratio of the negative electrode material, the negative electrode conductive agent, and the negative electrode binder can be, but is not limited to, 100:1:4, 101:1.2:4.2, 102:1.4:4.4, 103:1.5:4.5, 104:1.8:4.8, or 105:2:5, etc. In one embodiment of the present application, the mass ratio of the negative electrode material, the negative electrode conductive agent, and the negative electrode binder can be (100-103): (1-1.7): (4-4.7). In another embodiment of the present application, the mass ratio of the negative electrode material, the negative electrode conductor and the negative electrode binder can be (102-105):(1.4-2):(4.5-5).

[0099] In one embodiment of the present application, the thickness of the negative electrode active material layer is 50 μm to 150 μm. Specifically, the thickness of the negative electrode active material layer may be, but is not limited to, 50 μm, 60 μm, 80 μm, 90 μm, 100 μm, 120 μm, 140 μm, or 150 μm. In one embodiment of the present application, the thickness of the negative electrode active material layer may be 50 μm to 100 μm. In another embodiment of the present application, the thickness of the negative electrode active material layer may be 90 μm to 150 μm.

[0100] In one embodiment of the present application, the compaction density of the negative electrode sheet is 1.2 mg / cm 3 -1.7mg / cm 3 , which can improve the energy density of the battery. Specifically, the compaction density of the negative electrode sheet can be but is not limited to 1.2 mg / cm 3 , 1.3mg / cm 3 , 1.4mg / cm 3 , 1.5mg / cm 3 , 1.6mg / cm 3 or 1.7 mg / cm 3 In one embodiment of the present application, the compaction density of the negative electrode sheet can be 1.2 mg / cm 3 -1.6mg / cm 3 In another embodiment of the present application, the compaction density of the negative electrode sheet can be 1.5 mg / cm 3 -1.7mg / cm 3 .

[0101] In one embodiment of the present application, a method for preparing a negative electrode sheet includes: mixing a negative electrode material, a negative electrode conductive agent, and a negative electrode binder to obtain a negative electrode slurry, applying the mixture to the surface of a negative electrode current collector, and drying the mixture to obtain a negative electrode sheet. Specifically, the drying temperature is 100°C-120°C, and the drying time is 12 hours-36 hours. Exemplarily, the drying temperature may be, but is not limited to, 100°C, 104°C, 108°C, 110°C, 115°C, 118°C, or 120°C; and the drying time may be, but is not limited to, 12 hours, 18 hours, 20 hours, 22 hours, 25 hours, 28 hours, 30 hours, or 36 hours. In one embodiment of the present application, the drying temperature may be 100°C-110°C, and the drying time may be 12 hours-25 hours. In another embodiment of the present application, the drying temperature may be 109°C-120°C, and the drying time may be 24 hours-36 hours.

[0102] The present application also provides a battery. The negative electrode plate described in any of the above embodiments has excellent rate performance, conductivity and energy density, which reduces the charging time of the battery, improves the charging efficiency and service life, and is conducive to the wide application of the battery.

[0103] In one embodiment of the present application, the battery further includes a positive electrode sheet, which includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector. Specifically, the positive electrode current collector may be, but is not limited to, at least one of copper, aluminum, nickel, and stainless steel. In one embodiment of the present application, the positive electrode current collector may be aluminum foil. In one embodiment of the present application, the positive electrode active material layer includes a positive electrode active material, which 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 active material may be lithium cobalt oxide. In another embodiment of the present application, the positive electrode active material may be nickel-cobalt-manganese oxide. In one embodiment of the present application, the positive electrode active material layer further includes a positive electrode conductive agent. The positive electrode conductive agent can increase the electrical conductivity between the active materials and improve electronic conductivity. Specifically, the positive electrode conductive agent may be, but is not limited to, at least one of graphite, carbon black, acetylene black, and graphene. In one embodiment of the present application, the positive electrode conductive agent may be graphite. In another embodiment of the present application, the positive electrode conductive agent may be carbon black. In one embodiment of the present application, the positive electrode active material layer further includes a positive electrode binder. The positive electrode binder can improve the binding ability of the components in the positive electrode active material layer and improve the binding ability between the positive electrode active material layer and the positive electrode current collector. Specifically, the positive electrode 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 positive electrode binder can be polyvinylidene fluoride.

[0104] In one embodiment of the present application, the battery further comprises a separator disposed between the positive electrode sheet and the negative electrode sheet. Specifically, the separator may be, but is not limited to, a woven membrane, a non-woven fabric, a microporous membrane, a composite membrane, a rolled membrane, or separator paper. In one embodiment of the present application, the battery further comprises 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 in the present application is not particularly limited and may be, but is not limited to, any substance known in the art as a battery electrolyte.

[0105] The present application also provides an electric device, which includes the battery described in any one of the above embodiments. The electric device provided by the present application has high energy density, high safety performance, excellent fast charging performance, and strong market competitiveness. Electric devices include mobile phones, tablets, watches, VR glasses, vehicles, etc. In one embodiment of the present application, the battery can be used in vehicles, which can improve the safety of vehicle electricity use and charging rate, promote the widespread application of new energy vehicles, and contribute to the construction of a green and environmentally friendly environment. In another embodiment of the present application, the battery can also be used in mobile phones, which can shorten the charging time of mobile phones, realize fast charging of mobile phones, and improve the battery life and safety of use. The electric device of the present application may refer to vehicles, electronic equipment, energy storage systems, etc., and the above-mentioned electrochemical device may be provided in the electric device in the form of single cells, battery modules, battery packs, capacitors, etc.

[0106] The effects of the technical solution of this application are further illustrated below through specific examples.

[0107] Example 1

[0108] The first precursor (2-methylimidazole) is dispersed and dissolved in a first solvent (methanol) to form a first mixed solution. The second precursor (zinc salt) and graphite are dispersed and dissolved in a second solvent (deionized water) to form a second mixed solution. The two solutions are mixed and stirred for 12 hours and then dried to obtain the negative electrode material precursor. Under an inert atmosphere, the mixture is sintered at 600-800°C for 2 hours to obtain the negative electrode material.

[0109] Example 2

[0110] The difference from Example 1 is that the first precursor is 2-ethylimidazole.

[0111] Example 3

[0112] The difference from Example 1 is that the first precursor is 4,5-dichloroimidazole.

[0113] Example 4

[0114] The difference from Example 1 is that the first precursor is pyrazole.

[0115] Example 5

[0116] The difference from Example 1 is that the first precursor is triazole.

[0117] Example 6

[0118] The difference from Example 1 is that the first precursor is benzimidazole.

[0119] Example 7

[0120] The difference from Example 1 is that the first precursor is a boron-containing organic matter, and the boron-containing organic matter is a triphenylboron pyridine complex.

[0121] Comparative Example 1

[0122] Graphite was dispersed and dissolved in deionized water, stirred for 12 hours, and then dried to obtain a negative electrode material precursor. The negative electrode material was sintered at 600-800°C for 2 hours under an inert atmosphere.

[0123] Comparative Example 2

[0124] The difference from Example 1 is that the porous carbon coating layer of the negative electrode material only has carbon element.

[0125] Performance testing

[0126] The negative electrode materials prepared in Examples 1-7 and Comparative Examples 1-2 were subjected to a BET specific surface area test, and the test results are shown in Table 1. The negative electrode materials prepared in Examples 1-7 and Comparative Examples 1-2 were subjected to a particle size test, and the test results are shown in Table 1. The negative electrode materials prepared in Examples 1-7 and Comparative Examples 1-2 were subjected to a quality test, and the test results are shown in Table 1.

[0127] Preparation of negative electrode sheet: The negative electrode materials prepared in the above Examples 1-7 and Comparative Examples 1-2 were mixed with the negative electrode conductive agent (conductive carbon black Super P) and the negative electrode binder (carboxymethyl cellulose and styrene-butadiene rubber in a mass ratio of 2:3) in a mass ratio of 93:2:5 to obtain a composite negative electrode slurry; the composite negative electrode slurry was coated on the negative electrode current collector (carbon-coated copper foil) using a coating machine, dried, and rolled to obtain a negative electrode sheet. The compaction density of the negative electrode sheet was 1.5 mg / cm 3 .

[0128] Preparation of positive electrode sheets: The positive electrode active material LiFePO4, the positive electrode binder (polyvinylidene fluoride) and the positive electrode conductive agent (conductive carbon black) are dispersed in a solvent (MMP) in a mass ratio of 90:5:5, mixed evenly to obtain a positive electrode slurry; the positive electrode slurry is coated on the opposite sides of the positive electrode collector (carbon-coated aluminum foil), dried, and roll-pressed to obtain a positive electrode sheet.

[0129] Preparation of the battery: Assemble the negative electrode sheet, the positive electrode sheet and the electrolyte (wherein the electrolyte is an organic solvent containing a lithium salt (specifically lithium hexafluorophosphate), wherein the lithium salt concentration is 1 mol / L, and the organic solvent includes ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate and vinylene carbonate, and in the organic solvent, the mass ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 3:6:1, and the mass fraction of vinylene carbonate is 1%) to obtain a battery.

[0130] The batteries prepared in Examples 1-7 and Comparative Examples 1-2 were subjected to rate performance testing. The test process was as follows: the batteries were formed and capacity divided at room temperature, and were charged and discharged for three cycles with a low current (0.05C) (during the activation process, the voltage range of the first cycle was 2-4V, and the voltage range of the second and third cycles was 2-3.8V) to achieve the purpose of activation; the batteries were charged from 0% SOC (2.0V) to the voltage upper limit (3.8V) at different rates (0.33C, 1C, 2C, 3C, 4C, 5C, 6C) to obtain the maximum charge capacity of the batteries at different rates, thereby obtaining the charge ratio of the batteries, which is calculated as follows: charge ratio = maximum charge capacity of the batteries at different rates / maximum charge capacity of the batteries at 0.33C × 100%. The results are shown in Table 2.

[0131] The batteries prepared in Examples 1-7 and Comparative Examples 1-2 were subjected to a charging capacity test. The test process was as follows: the batteries were formed and capacity divided at room temperature, and charged and discharged for three cycles with a small current (0.05C) (during the activation process, the voltage range of the first cycle was 2-4V, and the voltage range of the second and third cycles was 2-3.8V) to achieve the purpose of activation; at a certain rate (as shown in Table 3), the potential between the negative electrode plate / metal lithium reference electrode was equal to 0 as the lithium deposition boundary of the negative electrode, and the maximum charge capacity of the battery at a certain charge rate without lithium deposition was tested, and the charge ratio of the battery under the condition of no lithium deposition at the corresponding current was obtained (maximum charge capacity of the battery under the condition of no lithium deposition / maximum charge capacity of the battery at 0.33C × 100%). The results are shown in Table 3.

[0132] The negative electrode material was tested, wherein Figure 4 is a Raman spectrum of the negative electrode material provided in Example 1 of the present application, Figure 5 is an adsorption isotherm curve of the negative electrode material provided in Example 1 of the present application, Figure 6 is a pore size characterization of the negative electrode material provided in Example 1 of the present application, Figure 7 is a scanning electron microscope image of the negative electrode material provided in Example 1, and Figure 8 is a scanning electron microscope image of the negative electrode material provided in Example 1. It can be seen that the negative electrode material has a large specific surface area and a pore size distribution. The microscopic morphology is dodecahedral and the surface is wrinkled.

[0133] Table 1 Test results of negative electrode materials

[0134] Table 2 Rate performance test results

[0135] Table 3 Charging capacity test results

[0136] According to Examples 1-7 and Comparative Examples 1-2, it can be seen that the porous carbon coating layer of the negative electrode material provided by the present application has non-metallic elements other than carbon elements, and the number of surface defects and the number of holes in the porous carbon coating layer increase, thereby increasing the specific surface area of ​​the negative electrode material and improving the rate performance and fast charging performance of the negative electrode material, which is beneficial to shortening the charging time of the battery and increasing the charging rate of the battery. According to Examples 1-4 and 5-7, it can be seen that a suitable precursor can increase the charging capacity of the battery at a high rate current, improve the charging ratio at a high rate current, and further improve the rate performance and fast charging performance of the negative electrode material. According to Example 1 and Comparative Examples 1-2, it can be seen that the porous carbon coating layer has non-metallic element doping, which increases the number of defects in the porous carbon coating layer, shortens the diffusion path of ions, increases the number of diffusion paths of ions, improves ionic conductivity and electronic conductivity, and can improve the rate performance and fast charging performance of the negative electrode material, thereby shortening the charging time of the battery and increasing the charging rate of the battery.

[0137] 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, characterized in that The negative electrode material includes graphite and a porous carbon coating layer coated on the surface of the graphite, and the porous carbon coating layer contains non-metallic elements other than carbon.

2. The negative electrode material according to claim 1, wherein The specific surface area of ​​the negative electrode material is greater than 900m 2 / g, the porous carbon coating layer has pores, and the pore diameter of the pores is 0.5nm-1nm.

3. The negative electrode material according to claim 1, wherein The non-metallic element includes at least one of nitrogen, phosphorus, sulfur and boron; Optionally, the mass percentage of the non-metallic element in the porous carbon coating layer is 10%-15%.

4. The negative electrode material according to claim 1, wherein The non-metallic element includes nitrogen, and the nitrogen in the negative electrode material exists in a form of at least one of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen.

5. The negative electrode material according to claim 4, wherein The nitrogen element in the negative electrode material exists in the form of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen; Optionally, the mass ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the graphitic nitrogen is (3-4):3-4:2-3.

6. The negative electrode material according to claim 5, characterized in that In the X-ray photoelectron spectrum of the negative electrode material, the characteristic peak of the pyridinic nitrogen is located at 398.1eV-399.3eV, the characteristic peak of the pyrrolic nitrogen is located at 399.8eV-401.2eV, and the characteristic peak of the graphitic nitrogen is located at 401.1eV-408.7eV; Optionally, the characteristic peak area ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the graphitic nitrogen is (3-4): (3-4): (2-3).

7. The negative electrode material according to any one of claims 4 to 6, characterized in that In the Raman spectrum of the negative electrode material, the G peak is located at 1570 cm -1 -1585cm -1 , D peak is located at 1320cm -1 -1350cm -1 ; Optionally, the area ratio of the G peak to the D peak is (0.9-1.1):

1.

8. The negative electrode material according to any one of claims 1 to 7, wherein When the non-metallic element includes nitrogen, the shape of the negative electrode material includes at least one of a dodecahedron structure, a cube, a sphere, and a tube.

9. The negative electrode material according to any one of claims 1 to 8, characterized in that In the negative electrode material, the mass ratio of the graphite to the porous carbon coating layer is (8-9):(1-2); Optionally, the particle size D50 of the negative electrode material is 13 μm-17 μm; Optionally, the thickness of the porous carbon coating layer is 0.5 μm-1 μm.

10. A method for preparing a negative electrode material, characterized in that: include: Mixing a porous carbon coating layer precursor and graphite to obtain a negative electrode material precursor; The negative electrode material precursor is sintered to obtain a negative electrode material, wherein the negative electrode material comprises graphite and a porous carbon coating layer coated on the surface of the graphite, wherein the porous carbon coating layer contains non-metallic elements other than carbon.

11. The preparation method according to claim 10, characterized in that The porous carbon coating layer precursor includes a first precursor and a second precursor; The first precursor includes a non-metallic organic compound, wherein the non-metallic organic compound includes at least one of 2-methylimidazole, 2-ethylimidazole, 4,5-dichloroimidazole, pyrazole, triazole and benzimidazole; The second precursor includes a metal salt, and the metal salt includes at least one of zinc nitrate hexahydrate, zinc acetate, and zinc sulfate; Optionally, the molar ratio of the first precursor to the second precursor is (2-2.4):

1.

12. The preparation method according to claim 10, wherein The mass ratio of the porous carbon coating layer precursor to the graphite is (8-10):(90-92).

13. The preparation method according to claim 10, wherein The porous carbon coating layer precursor includes a metal-organic framework compound.

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

15. A battery, characterized in that: The battery comprises the negative electrode sheet according to any one of claims 14.

16. An electrical device, characterized in that: The electric device comprises the battery according to claim 15.

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