Negative electrode material, preparation method and application thereof

Abstract

The application provides a negative electrode material and a preparation method and application thereof, and the negative electrode material comprises graphite and a porous carbon coating layer coated on the surface of the graphite, and the porous carbon coating layer has non-metal elements in addition to carbon elements. The negative electrode material provided by the application has non-metal elements in addition to carbon elements in the porous carbon coating layer, the number of ion transmission channels is increased, the ion diffusion path is shortened, the conductivity and rate performance of the negative electrode material are improved, the charging efficiency of the negative electrode sheet is improved, the charging time of the battery is shortened, and the battery is conducive to wide application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] At present, the charging speed of batteries has become a hot spot in the field of batteries. The negative electrode material is one of the important factors affecting the fast charging performance of batteries. Graphite has good reversibility, safety and low cost, and is one of the widely used negative electrode materials in batteries. However, when the graphite negative electrode is subjected to fast charging, it often cannot withstand excessive current, resulting in problems such as metal deposition and generation of a large amount of by-products, thereby reducing the fast charging capacity. SUMMARY

[0003] In view of this, the present application provides a negative electrode material and a preparation method and 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 channels, shortens the ion diffusion path, improves the rate performance and fast charging performance of the negative electrode material, and is beneficial to shorten the charging time of the battery and improve the charging rate of the battery.

[0004] In a first aspect, the present application provides a negative electrode material, which comprises graphite and a porous carbon coating layer coated on the surface of the graphite, and the porous carbon coating layer has non-metallic elements other than carbon elements.

[0005] Optionally, the specific surface area of the negative electrode material is greater than 900 m 2 / g.

[0006] Optionally, the porous carbon coating layer has pores, and the pore size of the pores is 0.5 nm-1 nm.

[0007] Optionally, the non-metallic elements include at least one of nitrogen elements, phosphorus elements, sulfur elements and boron elements.

[0008] Optionally, the mass percentage of the non-metallic elements in the porous carbon coating layer is 10%-15%.

[0009] Optionally, the non-metallic elements include nitrogen elements, and the existence form of the nitrogen elements in the negative electrode material includes at least one of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen.

[0010] Optionally, the mass ratio of the pyridine nitrogen, the pyrrole nitrogen and the graphite nitrogen is (3-4):(3-4):(2-3).

[0011] Optionally, in the X-ray photoelectron spectroscopy of the negative electrode material, the characteristic peak of the pyridine nitrogen is located at 398.1 eV-399.3 eV, the characteristic peak of the pyrrole nitrogen is located at 399.8 eV-401.2 eV, and the characteristic peak of the graphite nitrogen is located at 401.1 eV-408.7 eV.

[0012] Optionally, the area ratio of the characteristic peaks of the pyridine nitrogen, the pyrrole nitrogen and the graphite nitrogen is (3-4):(3-4):(2-3).

[0013] Optionally, in the Raman spectrum of the negative electrode material, the G peak is located at 1570 cm -1 -1585 cm -1 , and the D peak is located at 1320 cm -1 -1350 cm -1 .

[0014] Optionally, the area ratio of the G peak and the D peak is (0.9-1.1):1.

[0015] Optionally, when the non-metallic element includes a nitrogen element, the shape of the negative electrode material includes at least one of a dodecahedron structure, a cube, a sphere and a tubular shape.

[0016] Optionally, in the negative electrode material, the mass ratio of the graphite and the porous carbon coating layer is (8-9):(1-2).

[0017] Optionally, the particle size D50 of the negative electrode material is 13-17 μm.

[0018] Optionally, the thickness of the porous carbon coating layer is 0.5-1 μm.

[0019] The negative electrode material provided in the application has a porous carbon coating layer with non-metallic elements other than carbon elements, which increases the number of ion transmission channels, shortens the ion diffusion path, and improves the rate performance of the negative electrode material.

[0020] In a second aspect, the application provides a preparation method of a negative electrode tab, comprising:

[0021] mixing a porous carbon coating layer precursor and graphite to obtain a negative electrode material precursor;

[0022] sintering the negative electrode material precursor to obtain a negative electrode material, the negative electrode material comprising graphite and a porous carbon coating layer coated on the surface of the graphite, and the porous carbon coating layer having non-metallic elements other than carbon elements.

[0023] Optionally, the porous carbon coating layer precursor comprises a first precursor and a second precursor.

[0024] Optionally, the first precursor comprises a non-metallic organic compound.

[0025] Optionally, the non-metallic organic compound comprises at least one of 2-methylimidazole, 2-ethylimidazole, 4,5-dichloroimidazole, pyrazole, triazole and benzimidazole.

[0026] Optionally, the second precursor comprises a metal salt.

[0027] Optionally, the metal salt comprises at least one of zinc nitrate hexahydrate, zinc acetate and zinc sulfate.

[0028] Optionally, the molar ratio of the first precursor to the second precursor is (2-2.4):1.

[0029] Optionally, the mass ratio of the porous carbon coating precursor to the graphite is (8-10):(92-90).

[0030] Optionally, the porous carbon coating precursor comprises a metal-organic framework compound.

[0031] The preparation method of the negative electrode material provided in the application is novel, simple in preparation process, low in preparation cost, high in conductivity of the prepared negative electrode material, and good in rate performance.

[0032] In a third aspect, the negative electrode sheet comprises a negative electrode active material layer, and the negative electrode active material layer comprises the negative electrode material of the first aspect or the negative electrode material prepared by the preparation method of the second aspect.

[0033] The negative electrode sheet provided in the application is good in rate performance and fast charging performance, high in conductivity, good in safety, and excellent in electrochemical performance.

[0034] In a fourth aspect, the application provides a battery comprising the negative electrode sheet of the third aspect.

[0035] The battery provided in the application is excellent in electrochemical performance, long in service life, can realize fast charging, and is conducive to the wide application of the battery.

[0036] In a fifth aspect, the application provides an electric device comprising the battery of the fourth aspect.

[0037] The electric device provided in the application is high in charging rate, good in safety performance, and conducive to the industrial application of the electric device. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. The specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0039] Figure 1 A cross-sectional schematic view of the negative electrode material according to an embodiment of the present application.

[0040] Figure 2 A flow chart of the preparation of the negative electrode material according to an embodiment of the present application.

[0041] Figure 3 A cross-sectional schematic view of the negative electrode sheet according to an embodiment of the present application.

[0042] Figure 4 A Raman spectrum of the negative electrode material according to Example 1 of the present application.

[0043] Figure 5 An adsorption isotherm of the negative electrode material according to Example 1 of the present application.

[0044] Figure 6 A pore size characterization of the negative electrode material according to Example 1 of the present application.

[0045] Figure 7 A scanning electron microscope image of the negative electrode material according to Example 1 of the present application.

[0046] Figure 8 A scanning electron microscope image of the negative electrode material according to Example 1 of the present application. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0048] The present application provides a negative electrode material. Please refer to Figure 1 The negative electrode material 10 according to an embodiment of the present application includes graphite 11 and a porous carbon coating layer 12 coated on the surface of the graphite 11, and the porous carbon coating layer 12 has a non-metallic element. The graphite in the negative electrode material can provide ion deintercalation sites, improve the conductivity and specific capacity of the negative electrode material, and reduce 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 a non-metallic element in addition to carbon elements, so that the number of defects of the porous carbon coating layer increases, the diffusion path of ions is shortened, the number of diffusion paths of ions is increased, the ionic conductivity and electronic conductivity are improved, which is beneficial to improving the rate performance and fast charging performance of the negative electrode material.

[0049] In the present application, the graphite has a layered structure, which can increase the number of ion insertion / extraction, and is beneficial to improve the specific capacity of the negative electrode material; the graphite has good electrical conductivity, which is beneficial to improve the electrical conductivity of the negative electrode material; the graphite has low cost, which is beneficial to reduce the preparation cost of the negative electrode material. In an embodiment of the present application, the graphite can include at least one of natural graphite and artificial graphite, but is not limited to this. In an embodiment of the present application, the graphite can be natural graphite. In another embodiment of the present application, the graphite can be artificial graphite.

[0050] In the present application, the graphite is a primary particle, and / or a secondary particle formed by agglomeration of a plurality of primary particles. In an embodiment of the present application, the particle size D50 of the graphite is 13-17 μm. Specifically, the particle size D50 of the graphite can be, but is not limited to, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 16 μm or 17 μm, etc. In an embodiment of the present application, the particle size D50 of the graphite can be 13-15 μm. In another embodiment of the present application, the particle size D50 of the graphite can be 14-17 μm.

[0051] In an embodiment of the present application, the mass percentage of the graphite in the negative electrode material is 80-90%. The appropriate mass percentage of the graphite can improve the specific capacity of the negative electrode material, and further improve the energy density of the negative electrode plate. Specifically, the mass percentage of the graphite in the graphite material can be, but is not limited to, 80%, 82%, 84%, 86%, 88% or 90%, etc. In an embodiment of the present application, the mass percentage of the graphite in the negative electrode material can be 80-86%. In another embodiment of the present application, the mass percentage of the graphite in the negative electrode material can be 85-90%.

[0052] In the present application, the porous carbon coating layer has a plurality of pores, which increases the specific surface area of the negative electrode material, increases the number of ion transmission channels, and is beneficial to improve the electrochemical performance of the negative electrode material. In an embodiment of the present application, the pore size of the pores is 0.5-1 nm, which can improve the adsorption capacity of the porous carbon coating layer, and further improve the ion transmission speed of the negative electrode material. Specifically, the pore size of the pores can be, but is not limited to, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm or 1 nm, etc. In an embodiment of the present application, the pore size of the pores can be 0.5-0.85 nm. In another embodiment of the present application, the pore size of the pores can be 0.7-1 nm.

[0053] In an embodiment of the present application, the thickness of the porous carbon coating layer is 0.5-1 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, etc. In an embodiment of the present application, the thickness of the porous carbon coating layer can be 0.5-0.8 μm. In another embodiment of the present application, the thickness of the porous carbon coating layer can be 0.7-1 μm.

[0054] In an embodiment of the present application, the mass percentage of the porous carbon coating layer in the negative electrode material is 10-20%. An appropriate amount of the porous carbon coating layer can improve the conductivity and safety of the negative electrode material. Specifically, the mass percentage of the porous carbon coating layer in the negative electrode material can be, but is not limited to, 10%, 12%, 14%, 16%, 18% or 20%, etc. In an embodiment of the present application, the mass percentage of the porous carbon coating layer in the negative electrode material can be 10-18%. In another embodiment of the present application, the mass percentage of the porous carbon coating layer in the negative electrode material can be 15-20%.

[0055] In the present application, the porous carbon coating layer has non-metallic elements in addition to carbon elements, which can effectively adjust the physical and chemical properties of the porous carbon coating layer. The non-metallic elements are uniformly distributed in the porous carbon coating layer, which produces more defect holes on the surface of the porous carbon coating layer, shortens the diffusion path of ions, increases the number of ion diffusion channels, and improves the ion conductivity. The non-metallic elements doped in the porous carbon coating layer change the distribution of the electron cloud around the porous carbon coating layer, improve the electronic conductivity of the porous carbon coating layer, and are beneficial to improve the fast charging performance and rate performance of the negative electrode material.

[0056] In an embodiment of the present application, the non-metallic elements can include, but are not limited to, at least one of nitrogen elements, phosphorus elements, sulfur elements and boron elements. In an embodiment of the present application, the non-metallic elements can be nitrogen elements, which can further improve the conductivity and rate performance of the negative electrode material. In another embodiment of the present application, the non-metallic elements can be phosphorus elements.

[0057] In an embodiment of the present application, carbon-non-metallic element covalent bonds are formed between the carbon elements and the non-metallic elements in the porous carbon coating layer, which improves the synergistic effect between the carbon elements and the non-metallic elements, and is beneficial to improve the conductivity and rate performance of the negative electrode material. In an embodiment of the present application, X-X covalent bonds (X-X covalent bonds include, but are not limited to, covalent bonds formed between any two of carbon, oxygen, nitrogen, sulfur, boron, phosphorus, etc.) are formed in the porous carbon coating layer.

[0058] In an embodiment of the present application, when the non-metallic element is nitrogen element, that is, the porous carbon coating layer has nitrogen element, the nitrogen element is uniformly distributed on the surface of the porous carbon coating layer. The atomic size of the nitrogen element is close to that of carbon atom, and the nitrogen element has five valence electrons, which is easy to form a strong valence bond with carbon atom, 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 being conducive to improving the fast charging performance and rate performance of the battery.

[0059] In an embodiment of the present application, the mass percentage of the non-metallic element in the porous carbon coating layer is 10%-15%. The mass percentage of the non-metallic element can be measured by elemental analysis and energy dispersive X-ray spectroscopy (EDS). Specifically, the mass percentage of the non-metallic element in the porous carbon coating layer can be, but is not limited to, 10%, 11%, 12%, 13%, 14% or 15%, etc. In an embodiment of the present application, the mass percentage of the non-metallic element in the porous carbon coating layer can be 10%-14%. In another embodiment of the present application, the mass percentage of the non-metallic element in the porous carbon coating layer can be 13%-15%. In some embodiments, the content of the non-metallic element can be measured by an elemental analyzer. Based on different physical and chemical methods, the non-metallic element in the sample is separated, enriched and detected to obtain the content of the non-metallic element. The working principle is as follows: in a high-temperature combustion furnace, the nitrogen-containing sample is oxidized and combusted at high temperature to generate nitrogen, nitrogen oxide, carbon dioxide and water. In this process, the organic elements in the sample are converted into corresponding gas oxides; the combustion-generated gas is pushed into the separation and detection unit by the carrier gas, and after the non-nitrogen element compounds are adsorbed and retained in the adsorption column, the nitrogen oxide is reduced to nitrogen gas and detected by the detector, and other element oxides are separated and detected in the order of carbon and hydrogen after the adsorption-desorption column adsorption and desorption, that is, the contents of different elements can be obtained.

[0060] In an embodiment of the present application, when the non-metallic element includes nitrogen element, the existing form of the nitrogen element in the negative electrode material includes at least one of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen.

[0061] In an embodiment of the present application, when the porous carbon coating layer comprises nitrogen elements, the forms of the nitrogen elements include pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen. In the electron distribution of a nitrogen atom, the five outer electrons can form strong valence bonds with the porous carbon coating layer, and have high binding capacity; two of the five outer electrons form sigma bonds with the porous carbon coating layer, and the other two form lone pairs of electrons, and the fifth electron is a pi orbital lone pair electron. The pyridinic nitrogen is usually located at the edge of the porous carbon coating layer, and due to the presence of the pi orbital lone pair electron, the pyridinic nitrogen can become an electron acceptor and interact with the metal component; the pyrrolic nitrogen is unstable and gradually changes into nitrogen oxide and graphitic nitrogen under the influence of temperature; the graphitic nitrogen has five outer electrons, four of which can form sigma bonds and pi bonds, and the fifth electron is in a higher energy pi* orbital, so that the graphitic nitrogen can become an electron donor.

[0062] In an embodiment of the present application, the mass ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the graphitic nitrogen is (3-4):(3-4):(2-3). Specifically, the mass ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the 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 an embodiment of the present application, the mass ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the graphitic nitrogen can be (3-3.7):(3-3.6):(2-2.5). In another embodiment of the present application, the mass ratio of the pyridinic nitrogen, the pyrrolic nitrogen and the graphitic nitrogen can be (3.4-4):(3.5-4):(2.4-3).

[0063] X-ray photoelectron spectroscopy is an important basis for characterizing the non-metallic element doped porous carbon coating layer. In an embodiment of the present application, when the non-metallic element is nitrogen element, in the X-ray photoelectron spectroscopy of the negative electrode material, the characteristic peak position of the nitrogen element is about 400 eV, and the characteristic peak position of the carbon element is about 284 eV, and the form of the nitrogen element in the porous carbon coating layer can be judged from the ratio of the peak intensities of the characteristic peaks of the nitrogen element and the carbon element. The form of the nitrogen element can be further subdivided according to the characteristic peak of the nitrogen element in the X-ray photoelectron spectroscopy. In an embodiment of the present application, in the X-ray photoelectron spectroscopy of the negative electrode material, the characteristic peak of the pyridinic nitrogen is located at 398.1 eV-399.3 eV, the characteristic peak of the pyrrolic nitrogen is located at 399.8 eV-401.2 eV, and the characteristic peak of the graphitic nitrogen is located at 401.1 eV-408.7 eV.

[0064] In an embodiment of the present application, the ratio of the characteristic peak area of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen in the X-ray photoelectron spectrum of the negative electrode material is (3-4):(3-4):(2-3). Specifically, the ratio of the characteristic peak area 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 an embodiment of the present application, the ratio of the characteristic peak area 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 ratio of the characteristic peak area of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen can be (3.4-4):(3.5-4):(2.4-3).

[0065] In an embodiment of the present application, in the Raman spectrum of the negative electrode material, both D peak and G peak are characteristic peaks of carbon atoms, D-peak represents defects of carbon atoms, and the characteristic peak position is about 1350 cm -1 -1370 cm -1 -1; and G peak represents in-plane stretching vibration of sp2 hybrid carbon atoms, and the characteristic peak position is about 1580 cm -1 -1600 cm -1 -1. Whether the non-metallic element is doped can be judged by the intensity ratio and the characteristic peak position shift of the D peak and the G peak.

[0066] In an embodiment of the present application, in the Raman spectrum of the negative electrode material, the characteristic peak of pyridine nitrogen is G peak, and the G peak is located at 1570 cm -1 -1585 cm -1 -1. Specifically, the position of the G peak can be, but is not limited to, 1570 cm -1 , 1572 cm -1 , 1575 cm -1 , 1578 cm -1 , 1580 cm -1 , 1582 cm -1 or 1585 cm -1 , etc. In an embodiment of the present application, the position of the G peak can be 1570 cm -1 -1580 cm -1 -1. In another embodiment of the present application, the position of the G peak can be 1575 cm -1 -1585 cm -1 .

[0067] In an embodiment of the present application, in the Raman spectrum of the negative electrode material, the characteristic peak of pyrrole nitrogen is D peak, and the D peak is located at 1320 cm -1 -1350 cm -1 -1. Specifically, the position of the D peak can be, but is not limited to, 1320 cm -1 , 1325 cm-1 , 1330 cm -1 , 1335 cm -1 , 1340 cm -1 , 1345 cm -1 , or 1350 cm -1 , etc. In an embodiment of the present application, the position of the D peak can be 1320 cm -1 -1340 cm -1 . In another embodiment of the present application, the position of the D peak can be 1335 cm -1 -1350 cm -1 .

[0068] In an embodiment of the present application, the area ratio of the G peak and the D peak is (0.9-1.1):1. Specifically, the area ratio of the G peak and the D peak can 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, etc. In an embodiment of the present application, the area ratio of the G peak and the D peak can be (0.9-1):1. In another embodiment of the present application, the area ratio of the G peak and the D peak can be (1-1.1):1.

[0069] In an embodiment of the present application, the shape of the negative electrode material can include but is not limited to at least one of a dodecahedron structure, a cube, a sphere, and a tubular shape. In an embodiment of the present application, the shape of the negative electrode material can include a dodecahedron structure, which improves the specific surface area of the negative electrode material, further improves the mass transfer efficiency and loading capacity of the negative electrode material, and is conducive to improving the electrochemical performance and stability of the negative electrode sheet. In the present application, the micro-morphology of the negative electrode material can be tested by a scanning electron microscope.

[0070] In an embodiment of the present application, the mass ratio of graphite and the porous carbon coating layer in the negative electrode material is (8-9):(2:1). Specifically, the mass ratio of graphite and 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 an embodiment of the present application, the mass ratio of graphite and 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 and the porous carbon coating layer can be (8.5-9):(1.5-2).

[0071] In an embodiment of the present application, the particle size D50 of the negative electrode material is 13-17 μm. Specifically, the particle size D50 of the negative electrode material can be but is not limited to 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 16 μm, or 17 μm, etc. In an embodiment of the present application, the particle size D50 of the negative electrode material can be 13-15 μm. In another embodiment of the present application, the particle size D50 of the negative electrode material can be 14-17 μm.

[0072] In an 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 conducive to improving the energy density of the negative electrode sheet. In an embodiment of the present application, the BET specific surface area of the negative electrode material is greater than or equal to 900 m 2 / g, specifically, the specific surface area of the negative electrode material can be, but is not limited to, greater than or equal to 900 m 2 / g, greater than or equal to 950 m 2 / g, greater than or equal to 1000 m 2 / g, greater than or equal to 1050 m 2 / g, greater than or equal to 1100 m 2 / g, greater than or equal to 1100 m 2 / g, or greater than or equal to 1200 m 2 / g, etc. 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 higher the mass transfer capacity of the negative electrode material, which is conducive 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 1200 m 2 / g, greater than or equal to 1250 m 2 / g, greater than or equal to 1300 m 2 / g, greater than or equal to 1350 m 2 / g, greater than or equal to 1400 m 2 / g, greater than or equal to 1450 m 2 / g, or greater than or equal to 1500 m 2 / g, etc. In some embodiments, the Langmuir specific surface area is derived from the monolayer adsorption theory, which assumes that surface adsorption is a monolayer positioning adsorption, the surface is uniform, and there is no interaction between the molecules in the adsorption layer. At this time, 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 amount, and b is a constant related to the adsorption heat; the actual adsorption amount V of nitrogen 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 amount V m , and the specific surface area, also known as the Langmuir specific surface area, is calculated.

[0073] Please refer to Figure 2A preparation flowchart of the negative electrode material provided in an embodiment of the present application includes:

[0074] S101: mixing the porous carbon coating layer precursor and graphite to obtain a negative electrode material precursor;

[0075] S102: sintering the negative electrode material precursor to obtain the negative electrode material.

[0076] The present application provides a novel preparation method, a simple preparation process, low preparation cost, high conductivity of the prepared negative electrode material, and good rate performance. The negative electrode material described in any one of the embodiments can be prepared by the method.

[0077] In an embodiment of the present application, the porous carbon coating layer precursor includes a first precursor and a second precursor, and can form a porous carbon coating layer. The present application uses a solvothermal method to synthesize the porous carbon coating layer, which is easy to obtain raw materials, simple to operate, and easy to realize large-scale production. 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-metallic doped carbon five-membered ring, which can expose abundant non-metallic active sites, increase the number of defects of 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-methyl imidazole, 2-ethyl imidazole, 4,5-dichloro imidazole, pyrazole, triazole, and benzimidazole. In an embodiment of the present application, when the first precursor is a non-metallic organic matter, the first precursor can be 2-methyl imidazole. In another embodiment of the present application, when the first precursor is a non-metallic organic matter, the first precursor can be dichloro imidazole.

[0078] In an embodiment of the present application, the second precursor includes a metal salt. Exemplarily, the metal salt can include, but is not limited to, at least one of zinc nitrate hexahydrate, zinc acetate, and zinc sulfate. The boiling point of zinc salt is low, and it is easy to volatilize during sintering, which is beneficial to improve the purity of the negative electrode material and reduce the adverse effects caused by excessive element doping. In an embodiment of the present application, when the second precursor is a metal salt, the second precursor can be zinc sulfate. In another embodiment of the present application, when the second precursor is a metal salt, the second precursor can be zinc acetate.

[0079] In an embodiment of the present application, the molar ratio of the first precursor and the second precursor is (2-2.4):1. The appropriate molar ratio of the first precursor and the second precursor can facilitate 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 an 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.

[0080] In an 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 can 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 an embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, the graphite, and the solvent can 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 can be (9-10):(90.5-92).

[0081] In an embodiment of the present application, the porous carbon coating layer precursor, the graphite, and the solvent are mixed, and 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 an 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.

[0082] In an embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, the graphite, and the solvent is (8-10):(90-92):(200-400). Specifically, the mass ratio of the porous carbon coating layer precursor, the graphite, and the 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 an embodiment of the present application, the mass ratio of the porous carbon coating layer precursor, the graphite, and the 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, the graphite, and the solvent can be (9-10):(90.5-92):(250-400).

[0083] In an embodiment of the present application, the negative electrode material precursor comprises graphite and metal-organic framework compounds (MOFs) coated on the surface of the graphite. The metal-organic framework compounds are formed by the reaction of a first precursor and a second precursor, and are crystalline porous materials formed by the connection of organic or inorganic ligands and metals through coordination bonds, have adjustable pore structures, and form a porous carbon coating layer with non-metallic elements on the surface of the graphite after sintering, which is beneficial to improve the specific surface area and structural stability of the negative electrode material, and further improve the energy density of the negative electrode sheet. The micro-morphology of the negative electrode material is determined by the micro-morphology of the metal-organic framework compounds. Specifically, the metal-organic framework compounds can be, but are not limited to, at least one of zinc-2-ethyl imidazole (Zn(eim)2), zinc-dehydrobenzoimidazole (Zn(bim)2), zinc-pyrazole (Zn(pz)2), zinc-3-amino-1,2,4-triazole (Zn5(AmTAZ)6), zinc-imidazole-2-formaldehyde (Zn(ica)2), and zinc-1,2,4-triazole (Zn2(trz)4). In an embodiment of the present application, the material of the porous carbon coating layer can be zinc-2-ethyl imidazole (Zn(eim)2). In another embodiment of the present application, the material of the porous carbon coating layer can be zinc-imidazole-2-formaldehyde (Zn(ica)2).

[0084] In an embodiment of the present application, the present application further provides a preparation method of 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, and obtaining a negative electrode material precursor after drying, and obtaining a negative electrode material after sintering the negative electrode material precursor. In this way, the preparation efficiency of the negative electrode material can be improved, which is beneficial 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.

[0085] In an embodiment of the present application, the mass ratio of the first precursor to the first solvent is 1:(10-50). The appropriate mass ratio of the first precursor to the first solvent can improve the dispersion ability 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 an 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).

[0086] In an embodiment of the present application, the mass ratio of the second precursor, the graphite and the second solvent is 10:90:(100-500). Specifically, the mass ratio of the second precursor, the graphite and the second solvent can be, but is not limited to, 10:90:100, 10:90:200, 10:90:300, 10:90:400 or 10:90:500, etc. In an embodiment of the present application, the mass ratio of the second precursor, the graphite and the second solvent can be 10:90:(100-300). In another embodiment of the present application, the mass ratio of the second precursor, the graphite and the second solvent can be 10:90:(250-500).

[0087] In an embodiment of the present application, the stirring time of the mixed solution is 10h-15h, which can accelerate the reaction process and improve the reaction speed. Specifically, the stirring time of the mixed solution can be, but is not limited to, 10h, 11h, 12h, 13h, 14h or 15h, etc. In an embodiment of the present application, the stirring time of the mixed solution can be 12h, which can further accelerate the reaction rate. In another embodiment of the present application, the stirring time of the mixed solution can be 13h-15h.

[0088] In an embodiment of the present application, the sintering temperature is 600℃-800℃. Specifically, the sintering temperature can be, but is not limited to, 600℃, 650℃, 680℃, 690℃, 700℃, 720℃, 750℃, 780℃ or 800℃, etc. In an embodiment of the present application, the sintering temperature can be 600℃-780℃. In another embodiment of the present application, the sintering temperature can be 690℃-800℃.

[0089] In an embodiment of the present application, the sintering time can be 1h-4h. Specifically, the sintering time can be, but is not limited to, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h, etc. In an embodiment of the present application, the sintering time can be 2h, which can promote the synthesis of the negative electrode material. In another embodiment of the present application, the sintering time can be 2.5h-4h.

[0090] In an embodiment of the present application, the sintering atmosphere is an inert gas, which prevents the negative electrode material from being oxidized by environmental pollutants. Specifically, the sintering atmosphere can be, but is not limited to, at least one of argon, helium, neon and nitrogen. In an embodiment of the present application, the sintering atmosphere can be argon. In another embodiment of the present application, the sintering atmosphere can be nitrogen.

[0091] The present application also provides a negative electrode tab including a negative electrode active material layer, wherein the negative electrode active material includes the negative electrode material of any one of the above embodiments. Due to the high specific surface area, good electrical conductivity and excellent rate performance of the negative electrode material, the negative electrode tab has good fast-charging performance and excellent overall electrochemical performance.

[0092] Referring to Figure 3 A cross-sectional schematic view of a negative electrode tab provided in an embodiment of the present application is shown in FIG. 1. The negative electrode tab 100 includes a negative current collector 20 and a negative active material layer 30 disposed on the surface of the negative current collector 20. In an embodiment of the present application, the negative current collector can include, but is not limited to, at least one of copper, aluminum, nickel, and stainless steel. In an embodiment of the present application, the negative current collector can be a copper foil.

[0093] In an embodiment of the present application, the thickness of the negative current collector is 5-15 μm. Specifically, the thickness of the negative current collector can be, but is not limited to, 5 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, or 15 μm, etc. In an embodiment of the present application, the thickness of the negative current collector can be 5-10 μm. In another embodiment of the present application, the thickness of the negative current collector can be 9-15 μm.

[0094] In an embodiment of the present application, the negative active material layer further includes a negative conductive agent, which can improve the conductivity of the negative electrode tab. Specifically, the negative conductive agent can include, but is not limited to, at least one of carbon black, acetylene black, artificial graphite, carbon nanotube, and graphene. In an embodiment of the present application, the negative conductive agent can be acetylene black. In another embodiment of the present application, the negative conductive agent can be graphene.

[0095] In an embodiment of the present application, the negative active material layer further includes a negative binder, which can improve the adhesion between the negative active material layer and the negative current collector, and further improve the structural stability of the negative electrode tab. Specifically, the negative binder can include, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose, styrene butadiene rubber, and polyimide. In an embodiment of the present application, the negative binder can be polyvinylidene fluoride. In another embodiment of the present application, the negative binder can be carboxymethyl cellulose.

[0096] In an 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 component combination ability in the negative electrode active material layer, and improve the conductivity and rate capability 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 an 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 conductive agent and the negative electrode binder can be (102-105):(1.4-2):(4.5-5).

[0097] In an embodiment of the present application, the thickness of the negative electrode active material layer is 50-150 μm. Specifically, the thickness of the negative electrode active material layer can be, but is not limited to, 50 μm, 60 μm, 80 μm, 90 μm, 100 μm, 120 μm, 140 μm or 150 μm, etc. In an embodiment of the present application, the thickness of the negative electrode active material layer can be 50-100 μm. In another embodiment of the present application, the thickness of the negative electrode active material layer can be 90-150 μm.

[0098] In an embodiment of the present application, the compaction density of the negative electrode sheet is 1.2-1.7 mg / cm 3 . 3 This 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 , 1.3 mg / cm 3 , 1.4 mg / cm 3 , 1.5 mg / cm 3 , 1.6 mg / cm 3 or 1.7 mg / cm 3 , etc. In an embodiment of the present application, the compaction density of the negative electrode sheet can be 1.2-1.6 mg / cm 3 . 3 In another embodiment of the present application, the compaction density of the negative electrode sheet can be 1.5-1.7 mg / cm 3 . 3 .

[0099] In an embodiment of the present application, the preparation method of the negative electrode sheet comprises: mixing the negative electrode material, the negative electrode conductive agent and the negative electrode binder to obtain a negative electrode slurry, coating the negative electrode slurry on the surface of the negative electrode current collector, and obtaining the negative electrode sheet after drying. Specifically, the drying temperature is 100-120°C, and the drying time is 12-36h. For example, but not limited to, the drying temperature can be 100°C, 104°C, 108°C, 110°C, 115°C, 118°C or 120°C, etc.; and the drying time can be 12h, 18h, 20h, 22h, 25h, 28h, 30h or 36h, etc. In an embodiment of the present application, the drying temperature can be 100-110°C, and the drying time can be 12-25h. In another embodiment of the present application, the drying temperature can be 109-120°C, and the drying time can be 24-36h.

[0100] The present application also provides a battery, the negative electrode sheet of any one of the embodiments described above, because the negative electrode sheet has excellent rate performance, conductivity and energy density, reduces the charging time of the battery, improves the charging efficiency and service life, and is conducive to the wide application of the battery.

[0101] In an embodiment of the present application, the battery further comprises a positive electrode sheet, and the positive electrode sheet comprises 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 can be, but is not limited to, at least one of copper, aluminum, nickel and stainless steel. In an embodiment of the present application, the positive electrode current collector can be an aluminum foil. In an embodiment of the present application, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material can comprise, but is not limited to, at least one of lithium cobaltate material, lithium manganate material, nickel-cobalt-manganese material and nickel-cobalt-aluminum material. In an embodiment of the present application, the positive electrode active material can be lithium cobaltate material. In another embodiment of the present application, the positive electrode active material can be nickel-cobalt-manganese material. In an embodiment of the present application, the positive electrode active material layer further comprises a positive electrode conductive agent. The positive electrode conductive agent can increase the conductivity between the active materials and improve the electronic conductivity. Specifically, the positive electrode conductive agent can comprise, but is not limited to, at least one of graphite, carbon black, acetylene black and graphene. In an embodiment of the present application, the positive electrode conductive agent can be graphite. In another embodiment of the present application, the positive electrode conductive agent can be carbon black. In an embodiment of the present application, the positive electrode active material layer further comprises a positive electrode binder. The positive electrode binder can improve the binding ability of the components in the positive electrode active material layer and 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 butadiene-styrene latex. In an embodiment of the present application, the positive electrode binder can be polyvinylidene fluoride.

[0102] In an embodiment of the present application, the battery further comprises a separator arranged between the positive electrode sheet and the negative electrode sheet. Specifically, the separator can be, but is not limited to, a woven film, a non-woven fabric, a microporous film, a composite film, a calendered film, or a separator paper, etc. In an embodiment of the present application, the battery further comprises an electrolyte. At least part of the positive electrode sheet and at least part of the negative electrode sheet are soaked in the electrolyte. The electrolyte of the present application is not particularly limited and can be, but is not limited to, a substance capable of being used as a battery electrolyte in the art.

[0103] The present application also provides a power-consuming device comprising the battery of any one of the above embodiments. The power-consuming device provided by the present application has high energy density, high safety performance, excellent fast charging performance, and strong market competitiveness. The power-consuming device includes a mobile phone, a tablet, a watch, a VR glasses, a vehicle, etc. In an embodiment of the present application, the battery can be used in a vehicle, which can improve the safety and charging rate of the vehicle, improve the wide application of new energy vehicles, and be conducive to the construction of a green and environmentally friendly environment. In another embodiment of the present application, the battery can also be applied to a mobile phone, which can shorten the charging time of the mobile phone, realize the fast charging of the mobile phone, and improve the service life and safety of the battery. The power-consuming device of the present application can be a vehicle, an electronic device, an energy storage system, etc. The above electrochemical device can be arranged in the power-consuming device in the form of a single battery, a battery module, a battery pack, a capacitor, etc.

[0104] The effects of the technical solutions of the present application are further described below through specific examples.

[0105] Embodiment 1

[0106] The first precursor (2-methylimidazole) is dispersed and dissolved in the first solvent (methanol) to form a first mixed solution; the second precursor (zinc salt) and graphite are dispersed and dissolved in the second solvent (deionized water) to form a second mixed solution; the above two solutions are mixed and stirred for 12 h, and then dried to obtain a negative electrode material precursor. Under the protection of an inert atmosphere, sintering at 600-800°C for 2 h obtains a negative electrode material.

[0107] Embodiment 2

[0108] The difference between the embodiment 1 is that the first precursor is 2-ethylimidazole.

[0109] Embodiment 3

[0110] The difference between the embodiment 1 is that the first precursor is 4,5-dichloroimidazole.

[0111] Embodiment 4

[0112] The difference between the embodiment 1 is that the first precursor is pyrazole.

[0113] Embodiment 5

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

[0115] Example 6

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

[0117] Example 7

[0118] The difference from Example 1 is that the first precursor is a boron-containing organic compound, and the boron-containing organic compound is triphenylboron pyridine complex.

[0119] Comparative Example 1

[0120] The graphite is dispersed and dissolved in deionized water, stirred for 12 h, and then dried to obtain a negative electrode material precursor. Under the protection of an inert atmosphere, sintering at 600-800°C for 2 h obtains a negative electrode material.

[0121] Comparative Example 2

[0122] The difference from Example 1 is that the porous carbon coating layer of the negative electrode material only has carbon elements.

[0123] Performance detection

[0124] The negative electrode materials prepared in Examples 1-7 and Comparative Examples 1-2 above are subjected to BET specific surface area testing, and the test results are shown in Table 1. The negative electrode materials prepared in Examples 1-7 and Comparative Examples 1-2 above are subjected to particle size testing, and the test results are shown in Table 1. The negative electrode materials prepared in Examples 1-7 and Comparative Examples 1-2 above are subjected to mass testing, and the test results are shown in Table 1.

[0125] Preparation of negative electrode sheet: the negative electrode materials prepared in Examples 1-7 and Comparative Examples 1-2 above are mixed with a negative electrode conductive agent (conductive carbon black Super p) and a negative electrode binder (carboxymethyl cellulose and butadiene rubber with a mass ratio of 2:3) according to a mass ratio of 93:2:5 to obtain a composite negative electrode slurry; the composite negative electrode slurry is coated on a negative electrode current collector (carbon-coated copper foil) using a coating machine, dried, and rolled to obtain a negative electrode sheet, and the compaction density of the negative electrode sheet is 1.5 mg / cm 3 .

[0126] Preparation of positive electrode sheet: the positive electrode active material LiFePO4, a positive electrode binder (polyvinylidene fluoride), and a positive electrode conductive agent (conductive carbon black) are dispersed in a solvent (MMP) according to a mass ratio of 90:5:5, mixed uniformly to obtain a positive electrode slurry; the positive electrode slurry is coated on the opposite two sides of a positive electrode current collector (carbon-coated aluminum foil), dried, and rolled to obtain a positive electrode sheet.

[0127] Preparation of the battery: the negative electrode sheet, the positive electrode sheet and the electrolyte (wherein the electrolyte is an organic solvent containing lithium salt (specifically lithium hexafluorophosphate), wherein the lithium salt concentration is 1 mol / L, the organic solvent includes ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate and vinylene carbonate, the mass ratio of ethylene carbonate, methyl ethyl carbonate and dimethyl carbonate in the organic solvent is 3:6:1, and the mass fraction of vinylene carbonate is 1%) are assembled to obtain the battery.

[0128] The batteries prepared in the above examples 1-7 and comparative examples 1-2 are subjected to rate performance test, and the test process is as follows: the batteries are subjected to formation and distribution at room temperature, and are subjected to small current (0.05C) charge and discharge for 3 cycles (in the activation process, the voltage range of the first cycle is 2-4V, and the voltage range of the second and third cycles is 2-3.8V) to achieve the purpose of activation; the batteries are charged from 0% SOC (2.0V) to the upper limit of voltage (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, so as to obtain the charge rate of the battery, the charge rate = the maximum charge capacity of the battery at different rates / the maximum charge capacity of the battery at 0.33C x 100%, and the results are shown in Table 2.

[0129] The batteries prepared in the above examples 1-7 and comparative examples 1-2 are subjected to charge capacity test, and the test process is as follows: the batteries are subjected to formation and distribution at room temperature, and are subjected to small current (0.05C) charge and discharge for 3 cycles (in the activation process, the voltage range of the first cycle is 2-4V, and the voltage range of the second and third cycles is 2-3.8V) to achieve the purpose of activation; the potential between the negative electrode sheet and the metal lithium reference electrode is equal to 0 as the lithium precipitation boundary of the negative electrode, the maximum charge capacity of the battery at a certain charge rate under the condition of no lithium precipitation is tested, and the charge rate of the battery under the condition of no lithium precipitation at the corresponding current (the maximum charge capacity of the battery under the condition of no lithium precipitation / the maximum charge capacity of the battery at 0.33C x 100%) is obtained, and the results are shown in Table 3.

[0130] The negative electrode material is detected, wherein Figure 4 the Raman spectrum of the negative electrode material provided in example 1 of the present application, Figure 5 the adsorption isotherm curve of the negative electrode material provided in example 1 of the present application, Figure 6 the pore size characterization of the negative electrode material provided in example 1 of the present application, Figure 7 the scanning electron microscope image of the negative electrode material provided in example 1, Figure 8 the scanning electron microscope image of the negative electrode material provided in example 1. It can be seen that the specific surface area of the negative electrode material is large, and the pore size distribution is The micro-morphology presents dodecahedron, and the surface is wrinkled.

[0131] Table 1 negative electrode material test results

[0132]

[0133] Table 2 rate performance test results

[0134]

[0135]

[0136] Table 3 charge capacity test results

[0137] Straight charge current rate (C) Charge rate (%) under conditions in which lithium is not precipitated Example 1 2.3 79.5 Example 2 3.2 81.2 Example 3 5.0 82.0 Example 4 2.0 78.2 Example 5 0.7 77.6 Example 6 0.7 77.3 Example 7 2.5 76.0 Comparative Example 1 0.5 54.2 Comparative Example 2 0.5 50.1

[0138] According to Examples 1-7 and Comparative Examples 1-2, the porous carbon coating layer of the negative electrode material provided by the present application has non-metallic elements in addition to carbon elements, the number of surface defects and the number of pores of the porous carbon coating layer are increased, the specific surface area of the negative electrode material is increased, the rate performance and the fast charging performance of the negative electrode material are improved, which is beneficial to shorten the charging time of the battery and improve the charging rate of the battery. According to Examples 1-4 and Examples 5-7, the suitable precursor can improve the charge capacity of the battery under a large rate current, improve the charging rate under a large rate current, and further improve the rate performance and the fast charging performance of the negative electrode material. According to Examples 1 and Comparative Examples 1-2, the porous carbon coating layer has non-metallic element doping, which increases the number of defects of the porous carbon coating layer, shortens the diffusion path of ions, increases the number of ion diffusion paths, and improves the ion conductivity and the electronic conductivity, which can improve the rate performance and the fast charging performance of the negative electrode material, thereby shortening the charging time of the battery and improving the charging rate of the battery.

[0139] The above is the preferred embodiment of the present application, but it cannot be understood as limiting the scope of the present application. It should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which are also considered to be within the scope of protection of the present application.

Claims

1. A negative electrode material, characterized by, The negative electrode material includes graphite and a porous carbon coating layer coated on the surface of the graphite, the porous carbon coating layer has non-metallic elements other than carbon elements, in a Raman spectrum of the negative electrode material, a G peak is located at 1570 cm -1 -1585 cm -1 , a D peak is located at 1320 cm -1 -1350 cm -1 , and an area ratio of the G peak and the D peak is (0.9-1.1):

1.

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

3. The negative electrode material of claim 1, wherein, The non-metal element comprises at least one of a nitrogen element, a phosphorus element, a sulfur element and a boron element. The mass percentage of the non-metal element in the porous carbon coating layer is 10%-15%.

4. The negative electrode material of claim 1, wherein, The non-metal element comprises a nitrogen element, and the nitrogen element in the negative electrode material exists in at least one of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen.

5. The negative electrode material of claim 4, wherein the carbon-based material is selected from the group consisting of graphite, carbon black, and carbon nanotubes. The non-metal element comprises a nitrogen element, and the nitrogen element in the negative electrode material exists in at least one of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen. The mass ratio of the pyridine nitrogen, the pyrrole nitrogen and the graphite nitrogen is (3-4):(3-4):(2-3).

6. The negative electrode material of claim 5, wherein, In the X-ray photoelectron spectroscopy of the negative electrode material, the characteristic peak of the pyridine nitrogen is located at 398.1 eV-399.3 eV, the characteristic peak of the pyrrole nitrogen is located at 399.8 eV-401.2 eV, and the characteristic peak of the graphite nitrogen is located at 401.1 eV-408.7 eV. The characteristic peak area ratio of the pyridine nitrogen, the pyrrole nitrogen and the graphite nitrogen is (3-4):(3-4):(2-3).

7. The negative electrode material according to any one of claims 1 to 6, wherein the carbon material is a carbon material having a graphitization degree of 50% or more. When the non-metal element comprises a nitrogen element, the shape of the negative electrode material comprises at least one of dodecahedron structure, cube, sphere and tubular structure.

8. The negative electrode material according to any one of claims 1 to 7, wherein In the negative electrode material, the mass ratio of the graphite and the porous carbon coating layer is (8-9):(1-2). The particle size D50 of the negative electrode material is 13 μm-17 μm. The thickness of the porous carbon coating layer is 0.5 μm-1 μm.

9. A method of producing the negative electrode material according to any one of claims 1 to 8, characterized by, Comprising: mixing a porous carbon coating layer precursor and graphite to obtain a negative electrode material precursor; sintering the negative electrode material precursor to obtain a negative electrode material, the negative electrode material comprising graphite and a porous carbon coating layer coated on the surface of the graphite, the porous carbon coating layer having non-metal elements in addition to carbon elements.

10. The production method according to claim 9, wherein The porous carbon coating layer precursor comprises a first precursor and a second precursor. The first precursor comprises non-metallic organic matter, and the non-metallic organic matter comprises at least one of 2-methyl imidazole, 2-ethyl imidazole, 4,5-dichloro imidazole, pyrazole, triazole and benzimidazole. The second precursor comprises a metal salt, and the metal salt comprises at least one of zinc nitrate hexahydrate, zinc acetate and zinc sulfate. The molar ratio of the first precursor and the second precursor is (2-2.4):

1.

11. The production method according to claim 9, wherein The mass ratio of the porous carbon coating layer precursor and the graphite is (8-10):(90-92).

12. The production method according to claim 9, wherein The porous carbon coating layer precursor comprises a metal-organic framework compound.

13. A negative electrode sheet characterized by comprising: The negative electrode sheet comprises a negative electrode active material layer, and the negative electrode active material layer comprises the negative electrode material of any one of claims 1-8 or the negative electrode material prepared by the preparation method of any one of claims 9-12.

14. A battery, characterized by The battery comprises the negative electrode sheet of any one of claim 13.

15. An electrical device, characterized by The electrical equipment comprises the battery of claim 14.

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