A negative electrode material, a preparation method of a coating reagent, and a negative electrode material

Abstract

The application belongs to the technical field of batteries, and particularly relates to a negative electrode material, a preparation method of a coating reagent and the negative electrode material. The raw material of the coating reagent comprises a first type of carbonaceous raw material and a second type of carbonaceous raw material with mass ratios of M1 and M2, respectively, the first type of carbonaceous raw material is composed of a saturated fraction Sa1, an aromatic fraction Ar1, a resin fraction Re1 and an asphaltene fraction As1, the second type of carbonaceous raw material is composed of a saturated fraction Sa2, an aromatic fraction Ar2, a resin fraction Re2 and an asphaltene fraction As2, and the following conditions are met: 0.43 <= Sa1M1+Sa2M2+Ar1M1+Ar2M2 <= 0.49, and 0.50 <= Re1M1+Re2M2+As1M1+As2M2 <= 0.57. The application uses two types of carbonaceous raw materials to prepare the negative electrode material with good consistency, good charge-discharge rate and cycle life, and relatively low cost.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a negative electrode material, a method for preparing a coating reagent, and the negative electrode material itself. Background Technology

[0002] With the popularization of new energy vehicles, lithium-ion batteries are being used more and more widely. Charging anxiety and range anxiety have led to increasingly higher market demands for the fast-charging capabilities of lithium-ion batteries. Graphite is currently a commonly used anode material for lithium-ion batteries, and improving the fast-charging performance of graphite anode materials has a significant impact on the charging capacity of lithium-ion batteries. Current graphite anode materials typically consist of a layer of amorphous soft carbon or hard carbon material coated on the graphite surface. After high-temperature carbonization, a core-shell structure is obtained, with graphite as the core and amorphous soft or hard carbon material as the shell. This reduces the interfacial impedance of the graphite anode material, thereby improving charging performance.

[0003] Currently, typical coating reagents are byproducts of petrochemical or coal chemical processes, such as asphalt and tar. As typical mixtures, these materials have complex compositions and come from a wide range of sources. The composition of asphalt and tar prepared from crude oil or coal from different origins varies significantly, making it difficult to ensure component consistency. Consequently, it is difficult to control the consistency of the coating process and the structure after carbonization. Therefore, to ensure the consistency and stability of the coating raw materials, it is necessary to provide a technical solution to address these problems. Summary of the Invention

[0004] The present invention aims to solve the above problems and provides a method for preparing a negative electrode material and a coating reagent, and the negative electrode material can ensure the consistency and stability of the coating raw materials.

[0005] According to the technical solution of the present invention, the preparation method of the negative electrode material includes the following steps:

[0006] S1: Provide carbonaceous raw materials, said carbonaceous raw materials including a first type of carbonaceous raw material and a second type of carbonaceous raw material, wherein the first type of carbonaceous raw material and the second type of carbonaceous raw material satisfy the following conditions:

[0007] 0.43≤Sa1M1+Sa2M2+Ar1M1+Ar2M2≤0.49,

[0008] 0.50≤Re1M1+Re2M2+As1M1+As2M2≤0.57;

[0009] Wherein, M1 and M2 are the mass proportions of the first type of carbonaceous raw material and the second type of carbonaceous raw material, respectively, and M1+M2=1;

[0010] Sa1, Ar1, Re1, and As1 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction, and asphaltenes in the first type of carbonaceous raw material, respectively. Sa1 is 0.1–0.3, Ar1 is 0.2–0.4, Re1 is 0.2–0.5, and As1 is 0–0.05, and Sa1+Ar1+Re1+As1=1.

[0011] Sa2, Ar2, Re2 and As2 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction and asphaltenes in the second type of carbonaceous raw material, respectively. Sa2 is 0.1 to 0.2, Ar2 is 0.1 to 0.3, Re2 is 0.2 to 0.4 and As2 is 0.1 to 0.3, and Sa2+Ar2+Re2+As2=1;

[0012] S2: The first type of carbonaceous raw material, the second type of carbonaceous raw material and graphite are mixed and then subjected to thermal polymerization to obtain a semi-finished product;

[0013] S3: Carbonize and graphitize the semi-finished product to obtain the negative electrode material.

[0014] In this invention, a mixture of first-type and second-type carbonaceous raw materials is used as the coating material. The saturated components Sa1 and Sa2 and the aromatic components Ar1 and Ar2 are usually mainly composed of some saturated hydrocarbons or aromatic hydrocarbons with fewer carbon rings. These molecules have small molecular weights and good fluidity during high-temperature carbonization in the coating process. Carbonaceous raw materials with high saturated and aromatic content usually have good fluidity. The resinous components Re1 and Re2 and the asphaltenes As1 and As2 are usually composed of some polycyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons. They generally have a high molecular weight and are the main components that form amorphous carbon structures during high-temperature carbonization in the coating process. Carbonaceous materials with high resinous and asphaltenes content generally have a high molecular weight and belong to heavy components. Therefore, if the range of Sa1M1+Sa2M2+Ar1M1+Ar2M2 is greater than 0.49, the carbon yield of the coating layer will generally be too low, making it difficult to obtain a suitable coating thickness. If the range of Sa1M1+Sa2M2+Ar1M1+Ar2M2 is less than 0.43, the fluidity of the coating layer will be deviated, making it difficult to ensure coating uniformity. Similarly, if Re1M1+Re2M2+As1M1+As2M2 is too large (greater than 0.57) or too small (less than 0.50), it will also be difficult to ensure that the coating layer has both uniformity and a suitable thickness.

[0015] Furthermore, the range of M1:M2 is 0.4-0.6:0.4-0.6, meaning that in the carbonaceous raw materials, the mass ratio of the first type of carbonaceous raw materials and the second type of carbonaceous raw materials is both 0.4-0.6.

[0016] Furthermore, Sa1M1+Sa2M2+Ar1M1+Ar2M2 can be 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, or any range of values ​​formed by any two of the above points;

[0017] Re1M1+Re2M2+As1M1+As2M2 can be 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, etc., or the range value formed by any two of the above points.

[0018] Furthermore, after graphitization treatment, the graphitization degree of the first type of carbonaceous raw material is ≥80%, and the yield is ≥30wt%.

[0019] After graphitization treatment, the graphitization degree of the second type of carbonaceous raw material is ≤80%, and the yield is ≤20wt%.

[0020] Furthermore, in step S2, the total mass ratio of the first type of carbonaceous raw material and the second type of carbonaceous raw material to the mass ratio of graphite is 1:9 to 49, for example, it can be 1:9 (10:90), 1:19 (5:95), 1:49 (2:98), etc.

[0021] Furthermore, in step S2, the thermal polymerization is carried out under an inert atmosphere, and the temperature of the thermal polymerization is 120 to 300°C, for example, 120°C, 150°C, 200°C, 250°C, 300°C, etc.; the time is 2 to 8 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0022] Furthermore, in step S3, carbonization is carried out in an inert atmosphere, and the carbonization temperature is 900-1200℃, for example, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, etc.; the time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h, 3h, etc.

[0023] Specifically, the inert atmosphere is selected from one or more of nitrogen, argon, helium, etc.

[0024] A second aspect of the present invention provides a method for preparing a negative electrode material coating reagent, comprising the following steps:

[0025] S1: Provide carbonaceous raw materials, said carbonaceous raw materials including a first type of carbonaceous raw material and a second type of carbonaceous raw material, wherein the first type of carbonaceous raw material and the second type of carbonaceous raw material satisfy the following conditions:

[0026] 0.43≤Sa1M1+Sa2M2+Ar1M1+Ar2M2≤0.49,

[0027] 0.50≤Re1M1+Re2M2+As1M1+As2M2≤0.57;

[0028] Wherein, M1 and M2 are the mass proportions of the first type of carbonaceous raw material and the second type of carbonaceous raw material, respectively, and M1+M2=1;

[0029] Sa1, Ar1, Re1, and As1 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction, and asphaltenes in the first type of carbonaceous raw material, respectively. Sa1 is 0.1–0.3, Ar1 is 0.2–0.4, Re1 is 0.2–0.5, and As1 is 0–0.05, and Sa1+Ar1+Re1+As1=1.

[0030] Sa2, Ar2, Re2 and As2 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction and asphaltenes in the second type of carbonaceous raw material, respectively. Sa2 is 0.1 to 0.2, Ar2 is 0.1 to 0.3, Re2 is 0.2 to 0.4 and As2 is 0.1 to 0.3, and Sa2+Ar2+Re2+As2=1;

[0031] S2: The first type of carbonaceous raw material and the second type of carbonaceous raw material are mixed and then subjected to thermal polymerization to obtain an intermediate phase product;

[0032] S3: Carbonize and graphitize the intermediate phase product to obtain the coating reagent for the negative electrode material.

[0033] Furthermore, the range of M1:M2 is 0.4-0.6:0.4-0.6.

[0034] Furthermore, after graphitization treatment, the graphitization degree of the first type of carbonaceous raw material is ≥80%, and the yield is ≥30wt%.

[0035] After graphitization treatment, the graphitization degree of the second type of carbonaceous raw material is ≤80%, and the yield is ≤20wt%.

[0036] A third aspect of the present invention provides a negative electrode material, which is a negative electrode material prepared by the preparation method of the first aspect or includes a negative electrode material prepared by the preparation method of the second aspect, coated with a reagent.

[0037] Compared with the prior art, the technical solution of the present invention has the following advantages: The present invention uses two carbonaceous raw materials to make the prepared negative electrode coating material have good consistency, good charge and discharge rate and cycle life by reasonably matching materials. Attached Figure Description

[0038] Figure 1 This is a transmission electron microscope (TEM) image of the negative electrode material obtained in Example 1.

[0039] Figure 2 This is a transmission electron microscope (TEM) image of the negative electrode material obtained in Example 7. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0041] Existing coating reagents are complex in composition, mainly consisting of mixtures of hydrocarbons and aromatic compounds. They can generally be divided into two categories: light components and heavy components. Light components typically have small molecular weights and good flowability, which helps improve the flowability of the coating reagent. Good flowability facilitates the formation of a uniform surface coating layer during the coating process. However, their low fixed carbon content leads to low coating layer yield. After coating the graphite surface, high-temperature carbonization causes significant volatilization of the coating reagent, resulting in high energy consumption and a thin coating layer, making it difficult to obtain a suitable coating thickness. Heavy components generally have large molecular weights and high fixed carbon content, resulting in high yield after carbonization. They form the main structural part of the amorphous layer coated on the graphite surface after high-temperature carbonization. However, heavy components have poor flowability, leading to poor coating uniformity and making it difficult to obtain a uniform and stable coating layer. Given the different characteristics of these two components, the desired coating layer is one that combines the easy and uniform coating properties of light components with the high carbon content and suitable thickness of heavy components, resulting in a uniformly coated fast-charging material.

[0042] Based on this, the present invention provides a negative electrode material coating reagent by customizing these two components, and its preparation method includes the following steps:

[0043] S1: Provides both Type I and Type II carbonaceous raw materials.

[0044] Among them, the mass proportions of the first type of carbonaceous raw material and the second type of carbonaceous raw material are M1 and M2 respectively, and M1+M2=1;

[0045] The first type of carbonaceous raw material includes: saturated component Sa1 of 0.1 to 0.3, aromatic component Ar1 of 0.2 to 0.4, resinous component Re1 of 0.2 to 0.5, asphaltenes As1 of 0 to 0.05, and Sa1+Ar1+Re1+As1=1;

[0046] The first type of carbonaceous raw material includes: saturated component Sa2 of 0.1-0.2, aromatic component Ar2 of 0.1-0.3, resinous component Re2 of 0.2-0.4, asphaltenes As2 of 0.1-0.3, and Sa2+Ar2+Re2+As2=1;

[0047] The content of saturated components, aromatic components, resins, and asphaltenes can be obtained by testing according to the testing standard NB / SH1T0509-2010.

[0048] And it meets the following conditions:

[0049] 0.43≤Sa1M1+Sa2M2+Ar1M1+Ar2M2≤0.49,

[0050] 0.50≤Re1M1+Re2M2+As1M1+As2M2≤0.57;

[0051] S2: Mix the first type of carbonaceous raw material and the second type of carbonaceous raw material, and carry out thermal polymerization at 120-300℃ under an inert atmosphere for 2-8 hours to obtain an intermediate phase product;

[0052] S3: Carbonize the obtained intermediate phase product under an inert atmosphere at a temperature of 900–1200 °C for 1–3 h to obtain the negative electrode material coating reagent.

[0053] This application utilizes two types of carbonaceous raw materials, including various materials with different degrees of graphitization. Some are easily graphitized (Type I carbonaceous raw materials), while others are difficult to graphitize (Type II carbonaceous raw materials). Type I carbonaceous raw materials include cross-linked resins with special structures that undergo pyrolysis at around 1000℃. Even at temperatures above 2500℃, this type of carbon is difficult to obtain highly graphitized coke. It has good fluidity, ensuring uniform coating, but its carbon content is low, resulting in a high degree of defect in the coating layer. Type II carbonaceous raw materials possess coking ability, ensuring the density of the coating layer. This invention uses a combination of two different materials to coat graphite materials and perform co-carbonization, thereby screening and confirming the main composition and structure of the materials, resulting in a negative electrode material with excellent performance.

[0054] Preferably, the range of M1:M2 is 0.4-0.6:0.4-0.6.

[0055] Preferably, after graphitization treatment, the graphitization degree of the first type of carbonaceous raw material is ≥80%, and the yield is ≥30wt%.

[0056] The second type of carbonaceous raw material, after graphitization treatment, has a graphitization degree of ≤80% and a yield of ≤20wt%.

[0057] The coating reagent for this anode material can be used to prepare the anode material, and the preparation method of this anode material is as follows:

[0058] S1: Provide the above-mentioned first type of carbonaceous raw materials and second type of carbonaceous raw materials;

[0059] S2: Mix the first type of carbonaceous raw material and the second type of carbonaceous raw material, add graphite, and carry out thermal polymerization at 120-300℃ under an inert atmosphere for 2-8 hours to obtain a semi-finished product;

[0060] S3: Carbonize the semi-finished product in an inert atmosphere at a temperature of 900–1200℃ for 1–3 hours to obtain the negative electrode material.

[0061] The mass ratio of graphite to coating reagent raw materials (carbonaceous raw materials, including type I carbonaceous raw materials and type II carbonaceous raw materials) is 9 to 49:1.

[0062] The resulting negative electrode material has the structural advantages of both type I and type II carbon raw materials, which can improve initial efficiency, capacity and service life, and also enable fast charging.

[0063] By placing the negative electrode material on at least one side of a foil, a negative electrode sheet can be obtained. The resulting negative electrode sheet can be used in electrochemical devices, such as lithium-ion batteries and coin cells.

[0064] The electrochemical device specifically includes a positive electrode, a separator, an electrolyte, and the aforementioned negative electrode.

[0065] The positive electrode includes a current collector and an active material layer coated on the current collector. The active material layer may be, but is not limited to, a chemical formula such as Li. a Ni x Co y M z O 2-b N b (Where 0.95≤a≤1.2, x>0, y≥0, z≥0, and x+y+z=1, 0≤b≤1, M is selected from one or more combinations of Mn and Al, and N is selected from one or more combinations of F, P, and S) The positive electrode active material may also be, but is not limited to, LiCoO2, LiNiO2, LiVO2, LiCrO2, LiMn2O4, LiCoMnO4, Li2NiMn3O8, LiNi 0.5 Mn 1.5The positive electrode active material can be one or more combinations thereof, including O4, LiCoPO4, LiMnPO4, LiFePO4, LiNiPO4, LiCoFSO4, CuS2, FeS2, MoS2, NiS, and TiS2. The positive electrode active material can also be modified. Methods for modifying the positive electrode active material are known to those skilled in the art. For example, coating, doping, and other methods can be used to modify the positive electrode active material. The materials used for modification can be one or more combinations thereof, including but not limited to Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, and W. The positive electrode current collector is typically a structure or component that collects current. The positive electrode current collector can be any material suitable for use as a positive electrode current collector in electrochemical devices, for example, it can be including but not limited to metal foil.

[0066] The negative electrode includes a current collector and a negative electrode material coated on the current collector. The negative electrode current collector is usually a structure or component that collects current. It can be any material suitable for use as a negative electrode current collector in an electrochemical device, including but not limited to metal foil.

[0067] The diaphragm can be any material suitable for electrochemical devices, including, but not limited to, polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers.

[0068] The electrochemical device also includes an electrolyte, which comprises an organic solvent, an electrolyte lithium salt, and additives. The electrolyte lithium salt can be LiPF6 and / or LiBOB used in high-temperature electrolytes; it can also be at least one of LiBF4, LiBOB, and LiPF6 used in low-temperature electrolytes; it can also be at least one of LiBF4, LiBOB, LiPF6, and LiTFSI used in overcharge-resistant electrolytes; or it can be at least one of LiClO4, LiAsF6, LiCF3SO3, and LiN(CF3SO2)2. The organic solvent can be a cyclic carbonate, including PC and EC; it can also be a chain carbonate, including DFC, DMC, or EMC; or it can be a carboxylic acid ester, including MF, MA, EA, MP, etc. The additives include, but are not limited to, at least one of film-forming additives, conductive additives, flame-retardant additives, overcharge-resistant additives, additives for controlling the H2O and HF content in the electrolyte, additives for improving low-temperature performance, and multifunctional additives.

[0069] Example 1:

[0070] This embodiment provides a button cell, the preparation process of which is as follows:

[0071] 1. Positive electrode: Lithium metal sheet is used as the positive electrode.

[0072] 2. Preparation of the negative electrode:

[0073] 2.1 The preparation of the negative electrode material includes the following steps:

[0074] The mass percentages of each component in the first type of carbonaceous raw material are as follows: saturated component Sa1 is 0.25, aromatic component Ar1 is 0.31, resin Re1 is 0.41, and asphaltenes As1 is 0.03.

[0075] The mass percentages of each component in the second type of carbonaceous raw material are as follows: saturated component Sa2 is 0.18, aromatic component Ar2 is 0.21, resin Re2 is 0.32, and asphaltenes As2 is 0.29.

[0076] By mass fraction, 52% of the first type of carbonaceous raw material and 48% of the second type of carbonaceous raw material were mixed, wherein Sa1M1+Sa2M2+Ar1M1+Ar2M2=0.4784; Re1M1+Re2M2+As1M1+As2M2=0.5216. The mixture was thermally polymerized at 200℃ for 5 hours under an inert atmosphere (N2) to obtain an intermediate product. The intermediate product was then uniformly mixed with graphite at a mass ratio of 95:5, and the resulting mixture was carbonized at 1000℃ for 1 hour.

[0077] The electron microscope image of the obtained negative electrode material is as follows: Figure 1 As shown, a coating reagent is uniformly coated around the graphite core.

[0078] 2.2 The anode material obtained above is ground into powder, and the particle size is controlled using a 400-mesh sieve. Using N-methylpyrrolidone as a solvent, the anode material is mixed with carbon black and PVDF in a ratio of 85:5:10 to prepare a homogeneous solution of a certain concentration. This solution is then coated onto an 8μm copper foil and vacuum dried at 60℃ for 12 hours. After drying, the electrode sheet is pressed using a roller press to a compaction density of 1.50, and then punched into 12mm diameter sheets. 2 The circular wafer is then used to obtain the negative electrode.

[0079] 3. Separator: A porous polyethylene film with a thickness of 7μm was selected as the separator.

[0080] 4. Preparation of electrolyte: Lithium hexafluorophosphate (LiPF6) is dissolved in a mixed solvent of dimethyl carbonate (DEC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) (mass ratio of the three is 3:5:2) to obtain the electrolyte.

[0081] 5. Battery fabrication: In a glove box, the positive electrode, separator, and negative electrode are wound into a cell with a capacity of approximately 5Ah. The separator is located between adjacent positive and negative electrode plates. The positive electrode is led out by spot welding with aluminum tabs, and the negative electrode is led out by spot welding with nickel tabs. The cell is then placed in an aluminum-plastic packaging bag, baked, and then injected with the electrolyte. After encapsulation, formation, and capacity testing, a button cell is finally manufactured.

[0082] Examples 2-7:

[0083] A button cell is provided, which differs from Example 1 in that: the mass percentage of each component of the first type of carbonaceous raw material is different, and the proportion of the first type of carbonaceous raw material is different, as shown in Table 1.

[0084] Comparative Examples 1-4:

[0085] A button cell is provided, which differs from Example 1 in that: the mass percentage of each component of the first type of carbonaceous raw material is different, and the proportion of the first type of carbonaceous raw material is different, as shown in Table 1.

[0086] Table 1

[0087]

[0088]

[0089] Performance testing:

[0090] The coin cells described in the above embodiments were tested for capacity retention and cycle life. Five EA batteries from each group were subjected to 5 charge-discharge cycles at 0.05C to activate the material. Then, 10 charge-discharge cycles were performed at 0.5C to achieve a constant capacity. Based on the constant capacity, three charge-discharge rates (0.5C, 1C, and 2C) were designed for charging and discharging, with 10 cycles at each rate. The discharge capacity retention was calculated based on the average value of the 10 cycles. For the cycle test, at 25°C, the prepared lithium-ion batteries were fully charged at 1C and fully discharged at 1C within a voltage range of 2.8V-4.3V. The cycle count was recorded when the capacity decayed to 80% of the rated capacity. The results are shown in Table 2 below.

[0091] Table 2

[0092]

[0093]

[0094] Combining Tables 1 and 2, it can be seen that when the components of the first and second types of carbonaceous raw materials meet the range conditions, and Sa1M1+Sa2M2+Ar1M1+Ar2M2 is in the range of 0.43–0.49, and Re1M1+Re2M2+As1M1+As2M2 is in the range of 0.50–0.57, the anode materials prepared in Examples 1-5 exhibit superior overall performance. A comparison between Examples 5 and 6 shows that when the components of the first and second types of carbonaceous raw materials meet the range conditions, and Sa1M1+Sa2M2+Ar1M1+Ar2M2 = 0.536 (greater than 0.49) and Re1M1+Re2M2+As1M1+As2M2 = 0.4637 (less than 0.50) in Example 6, the anode material exhibits excellent rate performance but extremely poor cycle performance. This is due to the uniform but thin coating layer. A comparison between Examples 5 and 7 shows that the components of the first and second types of carbonaceous raw materials meet the range conditions. In Example 7, Sa1M1+Sa2M2+Ar1M1+Ar2M2=0.426 (less than 0.43), Re1M1+Re2M2+As1M1+As2M2=0.5739 (greater than 0.57). The rate performance of the negative electrode material is relatively inferior to that of Example 5, but its cycle performance is better. This is due to the uneven coating layer. Figure 2 It is evident that the coating layer is not uniformly coated and has a relatively large thickness. However, the coating layer thickness is quite large. In Comparative Examples 1-4, when the components of the carbonaceous raw material are outside the specified range, and the mass ratio of M1:M2 exceeds the range of 0.4-0.6:0.4-0.6, and exceeds the ranges of 0.43 < Sa1M1 + Sa2M2 + Ar1M1 + Ar2M2 < 0.49 and 0.50 < Re1M1 + Re2M2 + As1M1 + As2M2 < 0.57, the rate performance or cycle performance of the prepared negative electrode material will decrease to varying degrees, resulting in poor overall performance of the negative electrode material. This is caused by the change in the content of each component of the carbonaceous raw material, which affects the uniformity and thickness of the coating layer.

[0095] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a negative electrode material, characterized in that, Includes the following steps S1: Provide carbonaceous raw materials, said carbonaceous raw materials including a first type of carbonaceous raw material and a second type of carbonaceous raw material, wherein the first type of carbonaceous raw material and the second type of carbonaceous raw material satisfy the following conditions: 0.43≤Sa1M1+Sa2M2+Ar1M1+Ar2M2≤0.49, 0.50≤Re1M1+Re2M2+As1M1+As2M2≤0.57; Wherein, M1 and M2 are the mass proportions of the first type of carbonaceous raw material and the second type of carbonaceous raw material, respectively, and M1+M2=1; Sa1, Ar1, Re1, and As1 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction, and asphaltenes in the first type of carbonaceous raw material, respectively. Sa1 is 0.1–0.3, Ar1 is 0.2–0.4, Re1 is 0.2–0.5, and As1 is 0–0.05, and Sa1+Ar1+Re1+As1=1. Sa2, Ar2, Re2 and As2 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction and asphaltenes in the second type of carbonaceous raw material, respectively. Sa2 is 0.1 to 0.2, Ar2 is 0.1 to 0.3, Re2 is 0.2 to 0.4 and As2 is 0.1 to 0.3, and Sa2+Ar2+Re2+As2=1; S2: The first type of carbonaceous raw material, the second type of carbonaceous raw material and graphite are mixed and then subjected to thermal polymerization to obtain a semi-finished product; S3: Carbonize the semi-finished product to obtain the negative electrode material.

2. The method for preparing the negative electrode material as described in claim 1, characterized in that, The range of M1:M2 is 0.4-0.6:04-0.

6.

3. The method for preparing the negative electrode material as described in claim 1, characterized in that, After graphitization treatment, the graphitization degree of the first type of carbonaceous raw material is ≥80%, and the yield is ≥30wt%. After graphitization treatment, the graphitization degree of the second type of carbonaceous raw material is ≤80%, and the yield is ≤20wt%.

4. The method for preparing the negative electrode material as described in claim 1, characterized in that, In step S2, the total mass ratio of the first type of carbonaceous raw material and the second type of carbonaceous raw material to the mass ratio of graphite is 1:9 to 49.

5. The method for preparing the negative electrode material as described in claim 1, characterized in that, In step S2, the thermal polymerization is carried out under an inert atmosphere, with a temperature of 120–300°C and a time of 2–8 hours.

6. The method for preparing the negative electrode material as described in claim 1, characterized in that, In step S3, carbonization is carried out under an inert atmosphere at a temperature of 900–1200°C for 1–3 hours.

7. A method for preparing a negative electrode material coating reagent, characterized in that, Includes the following steps: S1: Provide carbonaceous raw materials, said carbonaceous raw materials including a first type of carbonaceous raw material and a second type of carbonaceous raw material, wherein the first type of carbonaceous raw material and the second type of carbonaceous raw material satisfy the following conditions: 0.43≤Sa1M1+Sa2M2+Ar1M1+Ar2M2≤0.49, 0.50≤Re1M1+Re2M2+As1M1+As2M2≤0.57; Wherein, M1 and M2 are the mass proportions of the first type of carbonaceous raw material and the second type of carbonaceous raw material, respectively, and M1+M2=1; Sa1, Ar1, Re1, and As1 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction, and asphaltenes in the first type of carbonaceous raw material, respectively. Sa1 is 0.1–0.3, Ar1 is 0.2–0.4, Re1 is 0.2–0.5, and As1 is 0–0.05, and Sa1+Ar1+Re1+As1=1. Sa2, Ar2, Re2 and As2 are the mass fractions of saturated fraction, aromatic fraction, resinous fraction and asphaltenes in the second type of carbonaceous raw material, respectively. Sa2 is 0.1 to 0.2, Ar2 is 0.1 to 0.3, Re2 is 0.2 to 0.4 and As2 is 0.1 to 0.3, and Sa2+Ar2+Re2+As2=1; S2: The first type of carbonaceous raw material and the second type of carbonaceous raw material are mixed and then subjected to thermal polymerization to obtain an intermediate phase product; S3: Carbonize the intermediate phase product to obtain the negative electrode material coating reagent.

8. The method for preparing the negative electrode material coating reagent as described in claim 7, characterized in that, The range of M1:M2 is 0.4-0.6:04-0.

6.

9. The preparation method of the negative electrode material coating reagent as described in claim 7, characterized in that, After graphitization treatment, the graphitization degree of the first type of carbonaceous raw material is ≥80%, and the yield is ≥30wt%. After graphitization treatment, the graphitization degree of the second type of carbonaceous raw material is ≤80%, and the yield is ≤20wt%.

10. A negative electrode material, characterized in that, The preparation method according to any one of claims 1-6, or the negative electrode material coating reagent prepared by any one of claims 7-9.

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