Graphite negative electrode material and preparation method therefor, and battery

Abstract

A graphite negative electrode material and a preparation method therefor, and a battery. The method comprises the following steps: preparing a precursor and a catalyst, and mixing the precursor and the catalyst to obtain a first product; and heating the first product to obtain a graphite negative electrode material, wherein the mass ratio of the precursor to the catalyst is 2.33 to 19; and the catalyst comprises A parts of ferric oxide, B parts of boron oxide, and C parts of silicon carbide, where 0≤A≤10, 0≤B≤10, 0<C≤10, and A+B>0.

Description

Graphite negative electrode material, preparation method thereof and battery

[0001] This application claims priority to Chinese Patent Application No. 202410799883.0, filed on June 20, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application belongs to the technical field of negative electrode materials, and particularly relates to a graphite negative electrode material, a preparation method thereof and a battery. BACKGROUND

[0003] In recent years, with the continuous development of the new energy vehicle industry, the battery industry has also been continuously progressing. Solving the range anxiety is an urgent demand of customers, and solving the range anxiety puts higher requirements on the fast charging performance and energy density of the battery.

[0004] Catalytic graphitization not only can improve the graphitization degree and capacity, thereby improving the energy density, but also can enrich the surface with pores, increase the transmission channel of lithium ions, reduce the tortuosity, and improve the rate performance.

[0005] In some related technologies, for example, Chinese Patent Document CN116514118A discloses a catalytic petroleum calcined coke graphitization method and application. Petroleum calcined coke is selected as a precursor, and a metal element or an oxide or carbide is used as a catalyst in the graphitization process. The technical solution disclosed in the patent effectively shortens the graphitization time and improves the graphitization yield.

[0006] For another example, Chinese Patent Document CN110416544B discloses a method for preparing a high-capacity artificial powder material. First, a silicon-based catalyst is mixed with a pore former to form a catalyst / pore former composite. Then, coke is mixed with the catalyst / pore former composite and a binder to form a mixture. The mixture is then pressed into a block by isostatic pressing, and then heated and carbonized. Then, the block is placed in an Acheson furnace for catalytic graphitization. Finally, the block is crushed, graded, de-magnetized, and sieved to obtain a high-capacity artificial powder material. TECHNICAL PROBLEM

[0007] Therefore, the present application provides a graphite negative electrode material, a preparation method thereof and a battery, aiming to balance the electrochemical performance and powder performance of the graphite negative electrode material. TECHNICAL SOLUTION

[0008] In a first aspect, the present application provides a preparation method of a graphite negative electrode material, including the following steps: preparing a precursor and a catalyst;

[0009] The precursor and the catalyst are mixed according to a preset mass ratio to obtain a first product;

[0010] subjecting the first product to a heating treatment to obtain the graphite negative electrode material;

[0011] The mass ratio of the precursor to the catalyst is 2.33-19.

[0012] The raw materials for preparing the catalyst include, in terms of mass fraction, A parts of diiron trioxide, B parts of boron oxide, and C parts of silicon carbide; wherein, 0≤A≤10; 0≤B≤10; 0

[0013] In a second aspect, the embodiments of the present application provide a graphite negative electrode material prepared by the graphite negative electrode material preparation method.

[0014] Preparation of the precursor and the catalyst;

[0015] Mixing the precursor and the catalyst according to a preset mass ratio to obtain a first product;

[0016] Subjecting the first product to a heating treatment to obtain the graphite negative electrode material;

[0017] The mass ratio of the precursor to the catalyst is 2.33-19.

[0018] The raw materials for preparing the catalyst include, in terms of mass fraction, A parts of diiron trioxide, B parts of boron oxide, and C parts of silicon carbide; wherein, 0≤A≤10; 0≤B≤10; 0

[0019] In a third aspect, the embodiments of the present application provide a battery comprising the negative electrode prepared by the graphite negative electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0021] FIG. 1 is a flow chart of the graphite negative electrode material preparation method provided by the embodiments of the present application;

[0022] FIG. 2 is a picture of a graphite negative electrode material provided by the embodiments of the present application;

[0023] FIGS. 3a-3c are SEM pictures of the graphite negative electrode material as an example provided by the embodiments of the present application;

[0024] Figure 4 is a plot of the catalytic factor values versus particle size D50 data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0025] Figure 5 is a plot of the catalytic factor values versus specific surface data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0026] Figure 6 is a plot of the catalytic factor values versus tap density data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0027] Figure 7 is a plot of the catalytic factor values versus graphitization degree data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0028] Figure 8 is a plot of the catalytic factor values versus capacity data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0029] Figure 9 is a plot of the catalytic factor values versus first efficiency data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0030] Figure 10 is a plot of the catalytic factor values versus 1C rate discharge capacity data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0031] Figure 11 is a plot of the catalytic factor values versus 2C rate discharge capacity data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0032] Figure 12 is a plot of the catalytic factor values versus 1C rate discharge capacity retention data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0033] Figure 13 is a plot of the catalytic factor values versus 2C rate discharge capacity retention data fitted with A equal to 1 according to embodiments 101-130 of the present application;

[0034] Figure 14 is a plot of the catalytic factor values versus particle size D50 data fitted with B equal to 1 according to embodiments 201-230 of the present application;

[0035] Figure 15 is a plot of the catalytic factor values versus specific surface data fitted with B equal to 1 according to embodiments 201-230 of the present application;

[0036] Figure 16 is a plot of the catalytic factor values versus tap density data fitted with B equal to 1 according to embodiments 201-230 of the present application;

[0037] Figure 17 is a plot of the catalytic factor values versus graphitization degree data fitted with B equal to 1 according to embodiments 201-230 of the present application;

[0038] FIG. 18 is a plot of catalytic factor values versus capacity data for B equal to 1, according to embodiments 201-230 of the application;

[0039] FIG. 19 is a plot of catalytic factor values versus initial capacity data for B equal to 1, according to embodiments 201-230 of the application;

[0040] FIG. 20 is a plot of catalytic factor values versus 1C rate discharge capacity data for B equal to 1, according to embodiments 201-230 of the application;

[0041] FIG. 21 is a plot of catalytic factor values versus 2C rate discharge capacity data for B equal to 1, according to embodiments 201-230 of the application;

[0042] FIG. 22 is a plot of catalytic factor values versus 1C rate discharge capacity retention data for B equal to 1, according to embodiments 201-230 of the application;

[0043] FIG. 23 is a plot of catalytic factor values versus 2C rate discharge capacity retention data for B equal to 1, according to embodiments 201-230 of the application;

[0044] FIG. 24 is a plot of catalytic factor values versus particle size D50 data for A equal to 1.5, according to embodiments 301-330 of the application;

[0045] FIG. 25 is a plot of catalytic factor values versus specific surface area data for A equal to 1.5, according to embodiments 301-330 of the application;

[0046] FIG. 26 is a plot of catalytic factor values versus tap density data for A equal to 1.5, according to embodiments 301-330 of the application;

[0047] FIG. 27 is a plot of catalytic factor values versus graphitization degree data for A equal to 1.5, according to embodiments 301-330 of the application;

[0048] FIG. 28 is a plot of catalytic factor values versus capacity data for A equal to 1.5, according to embodiments 301-330 of the application;

[0049] FIG. 29 is a plot of catalytic factor values versus initial capacity data for A equal to 1.5, according to embodiments 301-330 of the application;

[0050] FIG. 30 is a plot of catalytic factor values versus 1C rate discharge capacity data for A equal to 1.5, according to embodiments 301-330 of the application;

[0051] FIG. 31 is a plot of catalytic factor values versus 2C rate discharge capacity data for A equal to 1.5, according to embodiments 301-330 of the application;

[0052] Figure 32 is a graph of the catalytic factor value versus 1C rate discharge capacity retention data fit for A equal to 1.5, according to embodiments 301-330 of the application;

[0053] Figure 33 is a graph of the catalytic factor value versus 2C rate discharge capacity retention data fit for A equal to 1.5, according to embodiments 301-330 of the application;

[0054] Figure 34 is a graph of the catalytic factor value versus particle size D50 data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0055] Figure 35 is a graph of the catalytic factor value versus specific surface data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0056] Figure 36 is a graph of the catalytic factor value versus tap density data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0057] Figure 37 is a graph of the catalytic factor value versus graphitization degree data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0058] Figure 38 is a graph of the catalytic factor value versus capacity data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0059] Figure 39 is a graph of the catalytic factor value versus first efficiency data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0060] Figure 40 is a graph of the catalytic factor value versus 1C rate discharge capacity data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0061] Figure 41 is a graph of the catalytic factor value versus 2C rate discharge capacity data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0062] Figure 42 is a graph of the catalytic factor value versus 1C rate discharge capacity retention data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0063] Figure 43 is a graph of the catalytic factor value versus 2C rate discharge capacity retention data fit for B equal to 1.5, according to embodiments 401-430 of the application;

[0064] Figure 44 is a graph of the catalytic factor value versus particle size D50 data fit for A equal to 2.1, according to embodiments 501-530 of the application;

[0065] FIG. 45 is a curve graph of the catalytic factor value versus the specific surface data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0066] FIG. 46 is a curve graph of the catalytic factor value versus the tap density data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0067] FIG. 47 is a curve graph of the catalytic factor value versus the graphitization degree data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0068] FIG. 48 is a curve graph of the catalytic factor value versus the capacity data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0069] FIG. 49 is a curve graph of the catalytic factor value versus the initial efficiency data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0070] FIG. 50 is a curve graph of the catalytic factor value versus the 1C rate discharge capacity data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0071] FIG. 51 is a curve graph of the catalytic factor value versus the 2C rate discharge capacity data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0072] FIG. 52 is a curve graph of the catalytic factor value versus the 1C rate discharge capacity retention rate data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0073] FIG. 53 is a curve graph of the catalytic factor value versus the 2C rate discharge capacity retention rate data with A equal to 2.1 according to embodiments 501-530 of the present application;

[0074] FIG. 54 is a curve graph of the catalytic factor value versus the particle size D50 data with B equal to 2.1 according to embodiments 601-630 of the present application;

[0075] FIG. 55 is a curve graph of the catalytic factor value versus the specific surface data with B equal to 2.1 according to embodiments 601-630 of the present application;

[0076] FIG. 56 is a curve graph of the catalytic factor value versus the tap density data with B equal to 2.1 according to embodiments 601-630 of the present application;

[0077] FIG. 57 is a curve graph of the catalytic factor value versus the graphitization degree data with B equal to 2.1 according to embodiments 601-630 of the present application;

[0078] FIG. 58 is a curve graph of the catalytic factor value versus the capacity data with B equal to 2.1 according to embodiments 601-630 of the present application;

[0079] FIG. 59 is a plot of catalytic factor values versus first-cycle data for B equal to 2.1, according to embodiments 601-630 of the application;

[0080] FIG. 60 is a plot of catalytic factor values versus 1C-rate discharge capacity data for B equal to 2.1, according to embodiments 601-630 of the application;

[0081] FIG. 61 is a plot of catalytic factor values versus 2C-rate discharge capacity data for B equal to 2.1, according to embodiments 601-630 of the application;

[0082] FIG. 62 is a plot of catalytic factor values versus 1C-rate discharge capacity retention data for B equal to 2.1, according to embodiments 601-630 of the application;

[0083] FIG. 63 is a plot of catalytic factor values versus 2C-rate discharge capacity retention data for B equal to 2.1, according to embodiments 601-630 of the application;

[0084] FIG. 64 is a plot of catalytic factor values versus specific surface area / 1C-rate discharge capacity data for A equal to 1, according to embodiments 101-130 of the application;

[0085] FIG. 65 is a plot of catalytic factor values versus specific surface area / 2C-rate discharge capacity data for A equal to 1, according to embodiments 101-130 of the application;

[0086] FIG. 66 is a plot of catalytic factor values versus specific surface area / 1C-rate discharge capacity retention data for A equal to 1, according to embodiments 101-130 of the application;

[0087] FIG. 67 is a plot of catalytic factor values versus specific surface area / 2C-rate discharge capacity retention data for A equal to 1, according to embodiments 101-130 of the application;

[0088] FIG. 68 is a plot of catalytic factor values versus specific surface area / 2C-rate discharge capacity data for A equal to 1.5, according to embodiments 301-330 of the application;

[0089] FIG. 69 is a plot of catalytic factor values versus specific surface area / 2C-rate discharge capacity retention data for A equal to 1.5, according to embodiments 301-330 of the application;

[0090] FIG. 70 is a plot of catalytic factor values versus specific surface area / 2C-rate discharge capacity data for A equal to 2.1, according to embodiments 501-530 of the application;

[0091] FIG. 71 is a plot of the catalytic factor value versus the specific surface area / 2C-rate discharge capacity retention data fitting curve when A is equal to 2.1 according to embodiments 501-530 of the present application. DETAILED DESCRIPTION

[0092] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, any other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of the present application. In addition, it should be understood that the specific implementations described herein are merely for the purpose of illustrating and explaining the present application, and are not intended to limit the present application.

[0093] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing the specific embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0094] In the present application, the orientation words such as "upper" and "lower" refer to the upper and lower positions of the device in the actual use or working state, and specifically refer to the directions of the drawing surface in the drawings, and the "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish sequences.

[0095] In the present application, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural.

[0096] In the present application, "at least one" means one or more, and "multiple" means two or more. "One or more", "at least one of the following" or similar expressions mean any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

[0097] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the range described has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies to any range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fraction or integer) within the indicated range.

[0098] Referring to FIG. 1, the preparation method of the graphite negative electrode material of the present application comprises the following steps:

[0099] S101: The precursor and the catalyst are weighed and mixed uniformly according to a preset mass ratio to obtain a first product.

[0100] S102: The first product is placed into a heating furnace for graphitization treatment to obtain the graphite negative electrode material.

[0101] In step S101, the mass ratio of the precursor to the catalyst ranges from 2.33 to 19.

[0102] Furthermore, the raw materials for preparing the catalyst include A parts of diiron trioxide, B parts of boron oxide, and C parts of silicon carbide, wherein 0≤A≤10; 0≤B≤10; 0

[0103] The above scheme can adjust the mass ratio of A parts of diiron trioxide, B parts of boron oxide, and C parts of silicon carbide in the catalyst to make the catalytic factor of the catalyst within the corresponding range, so as to select a graphite negative electrode material with appropriate performance under the premise of considering the electrochemical performance and powder performance of the graphite negative electrode material.

[0104] Specifically, the raw materials for preparing the precursor include at least one of coking raw materials and microcrystalline graphite.

[0105] Specifically, the particle size of the precursor ranges from 1 to 20 μm.

[0106] Specifically, the mass ratio of the coking raw materials to the microcrystalline graphite ranges from 0.11 to 9.

[0107] Specifically, the stirring speed when mixing the precursor and the catalyst ranges from 100 to 800 rpm.

[0108] Specifically, the stirring time when mixing the precursor and the catalyst is 30 to 200 min.

[0109] Specifically, the heating temperature of the first product in the heating treatment is 2500-3500℃.

[0110] Specifically, in the heating treatment of the first product, a heating furnace is used for the heating treatment, and the heating furnace includes an Acheson furnace, a box furnace, an inner string furnace, or a continuous graphite furnace.

[0111] Specifically, the catalyst includes A% of diiron trioxide, B% of boron oxide, and C% of silicon carbide in terms of mass percentage, and the ratio of A+B to C is defined as a catalyst factor, and the catalyst factor is 0.11-10.

[0112] As a more specific scheme, in step S101, the mixing of the precursor and the catalyst uses a VC mixer, the stirring speed is 100-800 rpm, 200-700 rpm, or 300-600 rpm, and the stirring time is 30-200 min or 60-120 min.

[0113] The D50 particle size of the precursor is 1-20 pm, 8-10 pm, and preferably the median particle size D50 is 3-10 pm.

[0114] As a specific scheme, the total mass of the precursor and the catalyst is 100%, and the catalyst includes A% of diiron trioxide, B% of boron oxide, and C% of silicon carbide in terms of mass percentage.

[0115] Wherein, the value range of (A+B) / C is 0.1-10. Wherein, the value range of A is 0≤A≤10; and / or the value range of B is 0≤B≤10; the value range of C is 0<C≤10, the values of A and B are not 0 at the same time, and the value range of A+B is 0<A+B≤10.

[0116] The technical scheme of the present application is as follows:

[0117] In a first aspect, referring to FIG. 1, the embodiment of the present application provides a preparation method of a graphite negative electrode material.

[0118] Step one: the precursor and the catalyst are weighed and uniformly mixed according to a predetermined mass ratio to obtain a first product.

[0119] Wherein, the mixing of the precursor and the catalyst uses a VC mixer, the stirring speed is 100-800 rpm, 200-700 rpm, or 300-600 rpm, and the stirring time is 30-200 min or 60-120 min.

[0120] The mass ratio of the precursor to the catalyst is 2.33-19.

[0121] The precursor comprises coke raw material and / or microcrystalline graphite. The mass ratio of the coke raw material and the microcrystalline graphite in the precursor ranges from 0.11 to 9. The D50 particle size of the precursor ranges from 1 to 20 microns, 8 to 10 microns, and preferably the median particle size D50 ranges from 3 to 10 microns.

[0122] The catalyst comprises A parts of diiron trioxide, B parts of boron oxide and C parts of silicon carbide; wherein, 0≤A≤10; 0≤B≤10; 0<C≤10; A+B>0.

[0123] The total mass of the precursor and the catalyst is denoted as 100%, the mass percentage of diiron trioxide relative to the total mass of the precursor and the catalyst is A%, the mass percentage of boron oxide relative to the total mass of the precursor and the catalyst is B%, and the mass percentage of silicon carbide relative to the total mass of the precursor and the catalyst is C%.

[0124] The present application adjusts the mass ratio of A parts of diiron trioxide, B parts of boron oxide and C parts of silicon carbide in the catalyst, so that the catalytic factor of the catalyst is within the corresponding range, thereby selecting a graphite negative electrode material with appropriate performance under the premise of considering the electrochemical performance and powder performance of the graphite negative electrode material.

[0125] Wherein, the value range of (A+B) / C is 0.1-10. Wherein, the value range of A is 0≤A≤10; the value range of B is 0≤B≤10; the value range of C is 0<C≤10, the value of A is different from 0 when the value of B is different from 0, and the value range of A+B is 0<A+B≤10.

[0126] In step S102, the heating furnace adopts an Acheson furnace, a box furnace, an internal string furnace or a continuous graphitization furnace.

[0127] Specifically, the temperature of the graphitization treatment ranges from 2500 to 3500 degrees Celsius, and 2800 to 3200 degrees Celsius.

[0128] In a second aspect, with reference to FIGS. 2 and 3a-3c, the present application further provides a graphite negative electrode material prepared by the preparation method of the first aspect.

[0129] In a third aspect, the present application provides a battery prepared by the graphite negative electrode material of the second aspect.

[0130] The battery of the present application comprises a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator film; wherein, the negative electrode sheet is prepared by the graphite negative electrode material described above. The battery includes but is not limited to lithium ion batteries, sodium ion batteries, sodium lithium ion batteries, etc.

[0131] Specifically, the battery of the present application is prepared by the following method:

[0132] The above graphite negative electrode material is prepared into a slurry in a certain proportion of graphite negative electrode material: carbon black conductive agent SP: binder (SBR), mechanically stirred, coated on a copper foil current collector, dried and cold-pressed to prepare an electrode sheet, and then assembled into a lithium ion button cell for constant current charge and discharge test. The lithium sheet is used as the counter electrode, and the battery is assembled in a glove box.

[0133] In the present application, (A+B) / C is defined as the catalytic factor, and the change of the catalytic factor represents the change of the relative relationship of the ternary components of the iron sesquioxide, boron oxide and silicon carbide in the catalyst. After testing, it is found that the catalytic factor has an influence on the particle size D50, specific surface, tap density, graphitization degree, capacity of secondary battery, initial efficiency, 1C rate discharge capacity, 2C rate discharge capacity, 1C rate discharge capacity retention rate, and 2C rate discharge capacity retention rate of the prepared graphite negative electrode material.

[0134] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application. If the technology or condition is not specified in the embodiments, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0135] The present application provides some embodiments of the preparation method of graphite negative electrode materials with different catalytic factors, and the obtained graphite negative electrode materials are tested. In order to make a parallel comparison, the micrometric particles of the present application and the microcrystalline graphite both use particles with D50=8μm as raw materials, and the graphitization process uses Acheson furnace with a temperature of 3000 degrees.

[0136] As shown in Table 1, in Examples 101 to 130, the sum of the mass of the precursor and the catalyst is 100%, and the catalyst includes, in terms of mass percentage, iron sesquioxide A%, boron oxide B%, and silicon carbide C% of the total mass of the precursor and the catalyst. The mass ratio of the precursor to the catalyst is 94%:6%. The precursor uses micrometric particles, the mass of the precursor is 94g, and the mass of the catalyst is 6g. Among them, A is constant at 1, the value of C is changed by changing B, because A+B+C is always 6, so C=6-1-B, and then the value range of the catalytic factor (A+B) / C is changed.

[0137] Table 1

[0138] Example 101:

[0139] A preparation method of a graphite negative electrode material, comprising the following steps:

[0140] The precursor and the catalyst are mixed according to a preset mass ratio to obtain a first product;

[0141] The sum of the mass of the precursor and the catalyst is recorded as 100%, and the catalyst includes, in terms of mass percentage, A% of Fe2O3, B% of B2O3, and C% of SiC in the entire mass of the precursor and the catalyst; the mass ratio of the precursor to the catalyst is 94:6.

[0142] The precursor is coke microparticles, the mass of the precursor is 94g, and the mass of the catalyst is 6g.

[0143] The catalyst includes 1g of Fe2O3, 0g of B2O3, and 5g of SiC.

[0144] The precursor and the catalyst are added into a VC machine for mixing, the stirring speed is 300rpm, the mixing time is 60min, and the first product is obtained. In the formula, A is 1, B is 0, C is 5, A+B+C=6, and (A+B) / C=0.2 is satisfied.

[0145] The first product is placed into a heating furnace for graphitization treatment to obtain a graphite negative electrode material; the heating furnace is an Acheson furnace, and the temperature is 3000 degrees.

[0146] Example 102:

[0147] This example is basically the same as example 101, except that:

[0148] The catalyst includes 0.5g of B2O3 and 0.45g of SiC.

[0149] In the formula, B is 0.5, C is 0.45, and (A+B) / C=0.33 is satisfied.

[0150] Example 103

[0151] This example is basically the same as example 101, except that:

[0152] The catalyst includes 1g of B2O3 and 1g of SiC.

[0153] In the formula, B is 1, C is 4, and (A+B) / C=0.5 is satisfied.

[0154] Example 104

[0155] This example is basically the same as example 101, except that:

[0156] The catalyst includes 1.5g of B2O3 and 3.5g of SiC.

[0157] Wherein, B is 2.3, C is 2.7, and (A+B) / C=1.22 is satisfied.

[0158] Example 105

[0159] This example is basically the same as Example 101, except that:

[0160] The catalyst includes: 2.3g boron oxide, 2.7g silicon carbide;

[0161] Wherein, B is 2.3, C is 2.7, and (A+B) / C=1.22 is satisfied.

[0162] Example 106

[0163] This example is basically the same as Example 101, except that:

[0164] The catalyst includes: 2.5g boron oxide, 2.5g silicon carbide;

[0165] Wherein, B is 2.5, C is 2.5, and (A+B) / C=1.4 is satisfied.

[0166] Example 107

[0167] This example is basically the same as Example 101, except that:

[0168] The catalyst includes: 2.7g boron oxide, 2.3g silicon carbide;

[0169] Wherein, B is 2.7, C is 2.3, and (A+B) / C=1.61 is satisfied.

[0170] Example 108

[0171] This example is basically the same as Example 101, except that:

[0172] The catalyst includes: 2.9g boron oxide, 2.1g silicon carbide;

[0173] Wherein, B is 2.9, C is 2.1, and (A+B) / C=1.86 is satisfied.

[0174] Example 109

[0175] This example is basically the same as Example 101, except that:

[0176] The catalyst includes: 2.9g boron oxide, 2.1g silicon carbide;

[0177] Wherein, B is 2.9, C is 2.1, and (A+B) / C=1.86 is satisfied.

[0178] Example 110

[0179] This example is substantially the same as example 101, except that:

[0180] The catalyst comprises: 3.2 g of boron oxide, 1.8 g of silicon carbide;

[0181] wherein B is 3.2, C is 1.8, and (A+B) / C = 2.33 is satisfied.

[0182] Example 111

[0183] This example is substantially the same as example 101, except that:

[0184] The catalyst comprises: 3.3 g of boron oxide, 1.7 g of silicon carbide;

[0185] wherein B is 3.3, C is 1.7, and (A+B) / C = 2.53 is satisfied.

[0186] Example 112

[0187] This example is substantially the same as example 101, except that:

[0188] The catalyst comprises: 3.4 g of boron oxide, 1.6 g of silicon carbide;

[0189] wherein B is 3.4, C is 1.6, and (A+B) / C = 2.75 is satisfied.

[0190] Example 113

[0191] This example is substantially the same as example 101, except that:

[0192] The catalyst comprises: 3.5 g of boron oxide, 1.5 g of silicon carbide;

[0193] wherein B is 3.5, C is 1.5, and (A+B) / C = 3 is satisfied.

[0194] Example 114

[0195] This example is substantially the same as example 101, except that:

[0196] The catalyst comprises: 3.6 g of boron oxide, 1.4 g of silicon carbide;

[0197] wherein B is 3.6, C is 1.4, and (A+B) / C = 3.14 is satisfied.

[0198] Example 115

[0199] This example is substantially the same as example 101, except that:

[0200] The catalyst comprises: 3.7 g of boron oxide, 1.3 g of silicon carbide;

[0201] wherein B is 3.6, C is 1.4, and (A+B) / C = 3.29 is satisfied.

[0202] Example 116

[0203] This example is basically the same as Example 101, except that:

[0204] The catalyst includes: 3.7 g of boron oxide, 1.3 g of silicon carbide;

[0205] wherein B is 3.7, C is 1.3, and (A+B) / C = 3.62 is satisfied.

[0206] Example 117

[0207] This example is basically the same as Example 101, except that:

[0208] The catalyst includes: 3.75 g of boron oxide, 1.25 g of silicon carbide;

[0209] wherein B is 3.75, C is 1.25, and (A+B) / C = 3.8 is satisfied.

[0210] Example 118

[0211] This example is basically the same as Example 101, except that:

[0212] The catalyst includes: 3.8 g of boron oxide, 1.2 g of silicon carbide;

[0213] wherein B is 3.8, C is 1.2, and (A+B) / C = 4 is satisfied.

[0214] Example 119

[0215] This example is basically the same as Example 101, except that:

[0216] The catalyst includes: 3.85 g of boron oxide, 1.15 g of silicon carbide;

[0217] wherein B is 3.85, C is 1.15, and (A+B) / C = 4.22 is satisfied.

[0218] Example 120

[0219] This example is basically the same as Example 101, except that:

[0220] The catalyst includes: 3.9 g of boron oxide, 1.1 g of silicon carbide;

[0221] wherein B is 3.9, C is 1.1, and (A+B) / C = 4.45 is satisfied.

[0222] Example 121

[0223] This example is basically the same as example 101, except that:

[0224] The catalyst comprises: 3.95 g boron oxide, 1.05 g silicon carbide;

[0225] Where B is 3.95, C is 1.05, and (A+B) / C = 4.71 is satisfied.

[0226] Example 122

[0227] This example is basically the same as example 101, except that:

[0228] The catalyst comprises: 4 g boron oxide, 1 g silicon carbide;

[0229] Where B is 4, C is 1, and (A+B) / C = 5 is satisfied.

[0230] Example 123

[0231] This example is basically the same as example 101, except that:

[0232] The catalyst comprises: 4.1 g boron oxide, 0.9 g silicon carbide;

[0233] Where B is 4.1, C is 0.9, and (A+B) / C = 5.67 is satisfied.

[0234] Example 124

[0235] This example is basically the same as example 101, except that:

[0236] The catalyst comprises: 4.15 g boron oxide, 0.85 g silicon carbide;

[0237] Where B is 4.15, C is 0.85, and (A+B) / C = 6.06 is satisfied.

[0238] Example 125

[0239] This example is basically the same as example 101, except that:

[0240] The catalyst comprises: 4.2 g boron oxide, 0.8 g silicon carbide;

[0241] Where B is 4.2, C is 0.8, and (A+B) / C = 6.5 is satisfied.

[0242] Example 126

[0243] This example is basically the same as example 101, except that:

[0244] The catalyst includes 4.25 g of boron oxide, 0.75 g of silicon carbide;

[0245] wherein B is 4.25, C is 0.75, and (A+B) / C = 7 is satisfied.

[0246] Example 127

[0247] This example is substantially the same as Example 101, except that:

[0248] The catalyst includes 4.3 g of boron oxide, 0.7 g of silicon carbide;

[0249] wherein B is 4.3, C is 0.7, and (A+B) / C = 7.57 is satisfied.

[0250] Example 128

[0251] This example is substantially the same as Example 101, except that:

[0252] The catalyst includes 4.35 g of boron oxide, 0.65 g of silicon carbide;

[0253] wherein B is 4.35, C is 0.65, and (A+B) / C = 8.23 is satisfied.

[0254] Example 129

[0255] This example is substantially the same as Example 101, except that:

[0256] The catalyst includes 4.4 g of boron oxide, 0.6 g of silicon carbide;

[0257] wherein B is 4.4, C is 0.6, and (A+B) / C = 9 is satisfied.

[0258] Example 130

[0259] This example is substantially the same as Example 101, except that:

[0260] The catalyst includes 4.45 g of boron oxide, 0.55 g of silicon carbide;

[0261] wherein B is 4.45, C is 0.55, and (A+B) / C = 9.91 is satisfied.

[0262] As shown in Table 2, in Examples 201-230, the sum of the mass of the precursor and the catalyst is 100%, the catalyst includes, in mass percentage: the mass percentage of the ferroferric oxide in the whole precursor and catalyst is A%, the mass percentage of the boron oxide in the whole precursor and catalyst is B%, and the mass percentage of the silicon carbide in the whole precursor and catalyst is C%; the mass ratio of the precursor and the catalyst is: 94%:6%. The precursor adopts coke microparticles, the mass of the precursor is 94g, and the mass of the catalyst is 6g. Among them, B is constant at 1, C changes by changing A, because A+B+C is always 6, so C=6-1-A. By changing the value range of A and C, the value range of the catalytic factor (A+B) / C is changed.

[0263] The difference between Table 2 and Table 1 is that in Table 1, A is constant at 1, B is changed to change the catalytic factor, while in Table 2, B is constant at 1, and the catalytic factor is changed by changing A.

[0264] Table 2

[0265] Example 201

[0266] A preparation method of a graphite negative electrode material, comprising the following steps:

[0267] Mixing the precursor and the catalyst according to a preset mass ratio to obtain a first product;

[0268] The sum of the mass of the precursor and the catalyst is 100%, the catalyst includes, in mass percentage: the mass percentage of the ferroferric oxide in the whole precursor and catalyst is A%, the mass percentage of the boron oxide in the whole precursor and catalyst is B%, and the mass percentage of the silicon carbide in the whole precursor and catalyst is C%; the mass ratio of the precursor and the catalyst is: 94%:6%.

[0269] The precursor adopts coke microparticles, the mass of the precursor is 94g, and the mass of the catalyst is 6g.

[0270] Among them, the catalyst includes: 0g of ferroferric oxide, 1g of boron oxide, and 5g of silicon carbide.

[0271] Mixing the precursor and the catalyst in a VC machine, the stirring speed is 300rpm, and the mixing time is 60min to obtain a first product. Among them, A is 0, B is 1, C is 5, A+B+C=6, and (A+B) / 5=0.2 is satisfied.

[0272] Placing the first product into a heating furnace for graphitization treatment to obtain a graphite negative electrode material; the heating furnace adopts an Acheson furnace, and the temperature is 3000 degrees.

[0273] Examples 202-230

[0274] As shown in Table 2, examples 202-230 are basically the same as example 201, except that:

[0275] In the catalyst, the value of A is different from the value of A in example 201, and then the value of C is different from the value of C in example 201, and then the value of the catalytic factor is different from the value of C in example 201, see Table 2 for details.

[0276] As shown in Table 3, in examples 301-330, the sum of the mass of the precursor and the catalyst is 100%, the catalyst includes, according to the mass percentage: the mass percentage of ferric oxide in the whole precursor and catalyst is A%, the mass percentage of boron oxide in the whole precursor and catalyst is B%, and the mass percentage of silicon carbide in the whole precursor and catalyst is C%; the mass ratio of the precursor and the catalyst is 91%:9%. The precursor uses coke microparticles, the mass of the precursor is 91g, and the mass of the catalyst is 9g. Among them, A is constant 1.5, by changing B, the value of C is changed, because A+B+C is always 9, so C=9-1.5-B, and then the value range of the catalytic factor (A+B) / C is changed.

[0277] The difference between Table 3 and Table 1 is that in Table 3, the mass ratio of the precursor and the catalyst is 91%:9%. The mass of the precursor is 91g, and the mass of the catalyst is 9g. Among them, A is constant 1.5, and A+B+C is always 9.

[0278] Table 3

[0279] Example 301

[0280] A method for preparing a graphite negative electrode material, comprising the following steps:

[0281] Mixing the precursor and the catalyst according to a predetermined mass ratio to obtain a first product;

[0282] The sum of the mass of the precursor and the catalyst is 100%, the catalyst includes, according to the mass percentage: the mass percentage of ferric oxide in the whole precursor and catalyst is A%, the mass percentage of boron oxide in the whole precursor and catalyst is B%, and the mass percentage of silicon carbide in the whole precursor and catalyst is C%; the mass ratio of the precursor and the catalyst is 91%:9%.

[0283] The precursor uses coke microparticles, the mass of the precursor is 91g, and the mass of the catalyst is 9g.

[0284] Among them, the catalyst includes: 1.5g of ferric oxide, 0g of boron oxide, and 7.5g of silicon carbide.

[0285] The precursor and the catalyst are added into the VC machine for mixing, the stirring speed is 300 rpm, the mixing time is 60 min, and the first product is obtained. Among them, A is 1.5, B is 0, C is 7.5, A+B+C=9, and (A+B) / 5=0.2 is satisfied.

[0286] The first product is placed into a heating furnace for graphitization treatment to obtain a graphite negative electrode material; the heating furnace is an Acheson furnace, and the temperature is 3000 degrees.

[0287] Examples 302-330

[0288] As shown in Table 3, examples 302-330 are basically the same as example 301, the difference is that:

[0289] In the catalyst, the value of B is different from the value of B in example 301, and then the value of C is different from the value of C in example 301, and then the value of the catalyst factor is different from the value of C in example 301, see Table 3 for details.

[0290] As shown in Table 4, in examples 401 to 430, the sum of the mass of the precursor and the catalyst is 100%, the catalyst includes: the mass percentage of ferric oxide in the whole precursor and catalyst is A%, the mass percentage of boron oxide in the whole precursor and catalyst is B%, and the mass percentage of silicon carbide in the whole precursor and catalyst is C%; the mass ratio of the precursor to the catalyst is 91:9. The precursor uses coke micron particles, the mass of the precursor is 91g, and the mass of the catalyst is 9g. Among them, B is 1.5, by changing the value of A, the value of C is changed, because A+B+C is always 9, so C=9-1.5-A, and then the value range of the catalyst factor (A+B) / C is changed.

[0291] The difference between Table 4 and Table 3 is that in Table 3, A is always 1.5, B is changed, so as to realize the change of the catalyst factor, while in Table 4, B is always 1.5, and the change of the catalyst factor is realized by changing A.

[0292] Table 4

[0293] Example 401

[0294] A preparation method of a graphite negative electrode material, comprising the following steps:

[0295] The precursor and the catalyst are mixed according to the predetermined mass ratio to obtain a first product;

[0296] The sum of the mass of the precursor and the catalyst is 100%, and the catalyst includes, in terms of mass percentage, iron sesquioxide accounting for A% of the mass percentage of the entire precursor and catalyst, boron oxide accounting for B% of the mass percentage of the entire precursor and catalyst, and silicon carbide accounting for C% of the mass percentage of the entire precursor and catalyst; the mass ratio of the precursor and the catalyst is 91%:9%.

[0297] The precursor adopts coke microparticles, the mass of the precursor is 91 g, and the mass of the catalyst is 9 g.

[0298] The catalyst includes 0 g of iron sesquioxide, 1.5 g of boron oxide, and 7.5 g of silicon carbide.

[0299] The precursor and the catalyst are added into a VC machine for mixing, the stirring speed is 300 rpm, the mixing time is 60 min, and the first product is obtained. Among them, A is 0, B is 1.5, C is 7.5, A+B+C=9, and (A+B) / 5=0.2 is satisfied.

[0300] The first product is placed into a heating furnace for graphitization treatment to obtain a graphite negative electrode material; the heating furnace adopts an Acheson furnace, and the temperature is 3000 degrees.

[0301] Examples 402-430

[0302] As shown in Table 4, examples 402-430 are basically the same as example 401, the difference is that:

[0303] In the catalyst, the value of A is different from the value of A in example 401, and then the value of C is different from the value of C in example 401, and then the value of the catalyst factor is different from the value of C in example 401, see Table 4 for details.

[0304] As shown in Table 5, in examples 501-530, the sum of the mass of the precursor and the catalyst is 100%, and the catalyst includes, in terms of mass percentage, iron sesquioxide accounting for A% of the mass percentage of the entire precursor and catalyst, boron oxide accounting for B% of the mass percentage of the entire precursor and catalyst, and silicon carbide accounting for C% of the mass percentage of the entire precursor and catalyst; the mass ratio of the precursor and the catalyst is 87.4%:12.6%. The precursor adopts coke microparticles, the mass of the precursor is 87.4 g, and the mass of the catalyst is 12.6 g. Among them, A is always 2.1, the value of C is changed by changing the value of B, because A+B+C is always 12.6, so C=12.6-2.1-B, and then the value range of the catalyst factor (A+B) / C is changed.

[0305] Table 5 differs from Table 1 in that in Table 5, the mass ratio of the precursor to the catalyst is 87.4%:12.6%. The mass of the precursor is 87.4 g, and the mass of the catalyst is 12.6 g. Among them, A is constant 2.1, and A+B+C is always 12.6.

[0306] Table 5

[0307] Example 501

[0308] A method for preparing a graphite negative electrode material, comprising the following steps:

[0309] Mixing the precursor and the catalyst according to a preset mass ratio to obtain a first product;

[0310] The sum of the mass of the precursor and the catalyst is 100%, and the catalyst includes, by mass percentage, 2.1% of ferrous oxide, 0% of boron oxide, and 10.5% of silicon carbide. The mass ratio of the precursor to the catalyst is 87.4%:12.6%.

[0311] The precursor uses coke microparticles, the mass of the precursor is 87.4 g, and the mass of the catalyst is 12.6 g.

[0312] Among them, the catalyst includes 2.1 g of ferrous oxide, 0 g of boron oxide, and 10.5 g of silicon carbide.

[0313] Mixing the precursor and the catalyst in a VC machine, the stirring speed is 300 rpm, the mixing time is 60 min, and the first product is obtained. Among them, A is 2.1, B is 0, C is 10.5, A+B+C=12.6, and (A+B) / 5=0.2 is satisfied.

[0314] Placing the first product in a heating furnace for graphitization treatment to obtain a graphite negative electrode material; the heating furnace uses an Acheson furnace, and the temperature is 3000 degrees.

[0315] Examples 502-530

[0316] As shown in Table 5, examples 502-530 are basically the same as example 501, and the difference is that:

[0317] In the catalyst, the value of B is different from the value of B in example 501, which in turn makes the value of C different from the value of C in example 501, and in turn makes the value of the catalyst different from the value of C in example 501, see Table 5 for details.

[0318] As shown in Table 6, in the embodiments 601 to 630, the sum of the mass of the precursor and the catalyst is recorded as 100%, the catalyst includes, in terms of mass percentage: the mass percentage of the diiron trioxide in the whole precursor and catalyst is A%, the mass percentage of the boron oxide in the whole precursor and catalyst is B%, and the mass percentage of the silicon carbide in the whole precursor and catalyst is C%; the mass ratio of the precursor and the catalyst is: 87.4%:12.6%. The precursor adopts coke microparticles, the mass of the precursor is 87.4g, and the mass of the catalyst is 12.6g. Among them, B is constant at 2.1, the value of C is changed by changing A, because A+B+C is always 12.6, so C=12.6-2.1-A, and then the value range of the catalytic factor (A+B) / C is changed.

[0319] The difference between Table 6 and Table 5 is that in Table 5, A is constant at 2.1, B is changed to change the catalytic factor, while in Table 6, B is constant at 2.1, and the catalytic factor is changed by changing A.

[0320] Table 6

[0321] Embodiment 601

[0322] A preparation method of a graphite negative electrode material, comprising the following steps:

[0323] Mixing the precursor and the catalyst according to a preset mass ratio to obtain a first product;

[0324] The sum of the mass of the precursor and the catalyst is recorded as 100%, the catalyst includes, in terms of mass percentage: the mass percentage of the diiron trioxide in the whole precursor and catalyst is A%, the mass percentage of the boron oxide in the whole precursor and catalyst is B%, and the mass percentage of the silicon carbide in the whole precursor and catalyst is C%; the mass ratio of the precursor and the catalyst is: 87.4%:12.6%.

[0325] The precursor adopts coke microparticles, the mass of the precursor is 87.4g, and the mass of the catalyst is 12.6g.

[0326] Among them, the catalyst includes: 0g of diiron trioxide, 2.1g of boron oxide, and 10.5g of silicon carbide.

[0327] Mixing the precursor and the catalyst in a VC machine, the stirring speed is 300rpm, and the mixing time is 60min to obtain the first product. Among them, A is 0, B is 2.1, C is 10.5, A+B+C=12.6, and (A+B) / 5=0.2 is satisfied.

[0328] Placing the first product into a heating furnace for graphitization treatment to obtain a graphite negative electrode material; the heating furnace adopts an Acheson furnace, and the temperature is 3000 degrees.

[0329] Examples 602-630

[0330] As shown in Table 6, Examples 602-630 are substantially the same as Example 601, except that:

[0331] In the catalyst, the value of A is different from the value of A in Example 601, thereby making the value of C different from the value of C in Example 601, and thereby making the value of the catalytic factor different from the value of C in Example 601, see Table 6.

[0332] As the above graphite negative electrode material is one of the core components of the battery, the change of the catalytic factor not only affects the performance of the graphite negative electrode material itself, but also has an impact on the performance of the battery including the graphite negative electrode material.

[0333] Half-cell preparation and testing:

[0334] The above graphite negative electrode material is prepared into a slurry according to the mass ratio of graphite negative electrode material: carbon black conductive agent SP: binder (SBR) = 96.5:2:1.5, mechanically stirred at room temperature for 30 min at a stirring speed of 2000 r / min, the prepared slurry is coated on a copper foil current collector, and then baked in a 100°C oven for 30 min, and then dried in a 130°C vacuum drying oven for 8 h, the prepared electrode sheet is assembled into a lithium ion half-cell for constant current charge and discharge test, lithium sheet is used as the counter electrode, LiPF6 is dissolved in a mixed solvent of EC / DEC / EMC = 2:3:1 at a concentration of 1 mole / liter to form a non-aqueous electrolyte, wherein EC is ethylene carbonate, EMC is methyl ethyl carbonate, and DEC is diethyl carbonate, and the battery is assembled in a glove box. The change of the catalytic factor is tested for the capacity, initial efficiency, 1C rate discharge capacity, 2C rate discharge capacity, 1C rate discharge capacity retention rate, and 2C rate discharge capacity retention rate of the secondary battery.

[0335] As shown in Table 7, Table 7 is a test for the performance parameters of the secondary battery, specifically, the secondary battery in Table 7 includes the graphite negative electrode material prepared by the graphite negative electrode material preparation method of Examples 101-130. The test results for the secondary battery are shown in Table 7.

[0336] Table 7

[0337] As shown in Table 8, Table 8 is a test for the performance parameters of the secondary battery, specifically, the secondary battery in Table 8 includes the graphite negative electrode material prepared by the graphite negative electrode material preparation method of Examples 201-230. The test results for the secondary battery are shown in Table 8.

[0338] Table 8

[0339] As shown in Table 9, Table 9 is a test for a secondary battery performance parameter, specifically, the secondary battery in Table 9 includes the graphite negative electrode material prepared by the graphite negative electrode material preparation method of Examples 301-330. The test results for the secondary battery are shown in Table 9.

[0340] Table 9

[0341] As shown in Table 10, Table 10 is a test for a secondary battery performance parameter, specifically, the secondary battery in Table 10 includes the graphite negative electrode material prepared by the graphite negative electrode material preparation method of Examples 401-430. The test results for the secondary battery are shown in Table 10.

[0342] Table 10

[0343] As shown in Table 11, Table 11 is a test for a secondary battery performance parameter, specifically, the secondary battery in Table 11 includes the graphite negative electrode material prepared by the graphite negative electrode material preparation method of Examples 501-530. The test results for the secondary battery are shown in Table 11.

[0344] Table 11

[0345] As shown in Table 12, Table 12 is a test for a secondary battery performance parameter, specifically, the secondary battery in Table 12 includes the graphite negative electrode material prepared by the graphite negative electrode material preparation method of Examples 601-630. The test results for the secondary battery are shown in Table 12.

[0346] Table 12

[0347] As shown in FIGS. 4-63, the catalytic factor and the particle size of the graphite negative electrode material show a positive correlation, the catalytic factor and the tap density of the graphite negative electrode material and the graphitization degree show a negative correlation. The secondary battery (hereinafter referred to as secondary battery) prepared by the graphite negative electrode material of the present application shows a negative correlation between the capacity of the secondary battery, the initial efficiency and the catalytic factor, and a positive correlation between the 1C discharge capacity, the 2C discharge capacity, the 1C discharge capacity retention rate, the 2C discharge capacity retention rate of the secondary battery and the catalytic factor. Therefore, under the condition that the mass percentage of the catalyst in the whole precursor and catalyst is constant, the electrochemical performance and the powder performance of the graphite negative electrode material are realized by adjusting the catalytic factor.

[0348] As can be seen from the comparison of FIGS. 4-13 and 14-23, the comparison of FIGS. 24-33 and 34-43, and the comparison of FIGS. 44-53 and 54-63, when the mass ratio of the precursor to the catalyst is the same, the parameter changes of the graphite negative electrode material itself and the performance parameters of the secondary battery prepared from the graphite negative electrode material are directly related to the changes of the catalytic factor, and the component differences among the ferric oxide, boron oxide, and silicon carbide in the catalyst have relatively small effects on the parameter changes of the graphite negative electrode material itself and the performance parameters of the secondary battery.

[0349] For example, when the mass ratio of the precursor to the catalyst is 94g:6g, the changes of the catalytic factor can be realized by the changes of A or B. A is always 1, the value of C is changed by the change of B, and then the value range of the catalytic factor (A+B) / C is changed. Alternatively, B is always 1, the change of C is caused by the change of A, and the value range of the catalytic factor (A+B) / C is changed by the value range of A and C. As can be seen from the comparison of FIGS. 4-13 and 14-23, the parameter changes of the graphite negative electrode material itself and the performance parameters of the secondary battery prepared from the graphite negative electrode material are basically consistent in the above two ways of changing the catalytic factor. Therefore, it can be said that, in the preparation of the graphite negative electrode material, the balance of the performance of the graphite negative electrode material and the related secondary battery needs to focus on the catalytic factor range of the catalyst, and when the contents of the ferric oxide, boron oxide, and silicon carbide in the catalyst are the same, the performance of the graphite negative electrode material and the secondary battery is not greatly affected by the more or less of the three.

[0350] For the graphite negative electrode material, when the tap density is less than 0.9gcm -3 and the specific surface area is higher than 4gm -2 , it is not conducive to practical application. In the above examples provided in the application, all the examples meet the related requirements of the tap density, specific surface area, particle size D50, and graphitization degree. However, as mentioned above, the catalytic factor and the particle size of the graphite negative electrode material show a positive correlation change trend, the catalytic factor and the tap density and the graphitization degree of the graphite negative electrode material show a negative correlation change trend. The capacity (also called specific capacity) of the secondary battery prepared from the graphite negative electrode material, the initial efficiency, and the catalytic factor show a negative correlation change trend, and the 1C discharge capacity, 2C discharge capacity, 1C discharge capacity retention rate, and 2C discharge capacity retention rate of the secondary battery and the catalytic factor show a positive correlation change trend. In order to further improve the performance balance of the graphite negative electrode material, the balance of the negative correlation change parameters and the positive correlation change parameters needs to be further balanced by changing the catalytic factor.

[0351] As shown in FIG. 4-63, as the catalytic factor increases from the graphite negative material, the 1C rate capacity, 2C rate capacity, 1C rate capacity retention, 2C rate capacity retention of the secondary battery are continuously improved. Generally speaking, higher rate discharge capacity means that the battery has higher discharge capacity and longer use time. While the secondary battery capacity and the initial efficiency are continuously decreased, especially when the catalytic factor is in the range of 0.1-2, the trend of decrease is faster. Therefore, in order to balance the performance of graphite negative material powder and the electrochemical performance of secondary battery, the parameters that change negatively and positively with the catalytic factor of the catalyst need to be balanced respectively.

[0352] As shown in FIG. 64-71, when the precursor and catalyst mass ratio is 94:6, the balance between the catalytic factor and the specific surface / 1C rate discharge capacity, specific surface / 2C rate discharge capacity, specific surface / 1C rate discharge capacity retention, specific surface / 2C rate discharge capacity retention. As shown in FIG. 64, the specific surface / 1C rate discharge capacity in the range of 0.2-6.5 ensures the balance between the specific surface and 1C rate discharge capacity, 1C rate discharge capacity retention.

[0353] However, the specific surface / 2C rate discharge capacity, 2C rate discharge capacity retention changes rapidly in the range of 1-4, and the specific surface and 2C rate discharge capacity, 2C rate discharge capacity retention cannot maintain relatively balanced performance, while the catalytic factor is in the range of 0.2-1 and 4-6, the balance between the specific surface / 1C rate discharge capacity, specific surface / 2C rate discharge capacity, specific surface / 1C rate discharge capacity retention, specific surface / 2C rate discharge capacity retention is ensured, in addition, in the range of 4-6, the 1C rate discharge capacity, 2C rate discharge capacity, 1C rate discharge capacity retention, 2C rate discharge capacity retention of the secondary battery can be at a relatively high value; in the range of 0.2-1, the capacity of the secondary battery is at a relatively high value.

[0354] The application compares the performance parameters of the graphite negative electrode material and the secondary battery with the catalytic factor when the mass ratio of the precursor to the catalyst is 94:6; the performance parameters of the graphite negative electrode material and the secondary battery with the catalytic factor when the mass ratio of the precursor to the catalyst is 91:9; the performance parameters of the graphite negative electrode material and the secondary battery with the catalytic factor when the mass ratio of the precursor to the catalyst is 87.4:12.6. The catalytic factor in the range of 0.1-10 can ensure the technical effect of balancing the performance of the graphite negative electrode material and the secondary battery during the preparation of the catalyst, especially when the catalytic factor makes the specific surface area, the rate discharge capacity and the rate discharge capacity retention rate relatively balanced, the performance of the other performance parameters with negative correlation and the performance parameters with positive correlation can also be balanced. Due to the limited length, the application does not show all the performance parameters, and the above table data can be obtained.

[0355] The above describes the technical solutions provided by the embodiments of the application in detail, and the principles and implementation manners of the application are described by using specific examples. The above description of the embodiments is only used to help understand the method of the application and its core idea; meanwhile, for those skilled in the art, the specific implementation manners and application ranges can be changed according to the idea of the application. In summary, the content of the specification should not be understood as a limitation of the application

Claims

1. A method for preparing a graphite negative electrode material, comprising the following steps: preparing a precursor and a catalyst; mixing the precursor and the catalyst according to a preset mass ratio to obtain a first product; and performing a heating treatment on the first product to obtain the graphite negative electrode material. The mass ratio of the precursor to the catalyst ranges from 2.33 to 19. The raw materials for preparing the catalyst include A parts of Fe 2 O 3, B parts of B 2 O 3 and C parts of SiC, wherein 0≤A≤10, 0≤B≤10, 0 2.The method for preparing the graphite negative electrode material according to claim 1, wherein the raw materials for preparing the precursor include at least one of coking raw materials and microcrystalline graphite. 3.The method for preparing the graphite negative electrode material according to claim 2, wherein the particle size of the precursor ranges from 1 to 20 μm. 4.The method for preparing the graphite negative electrode material according to claim 3, wherein the mass ratio of the coking raw materials to the microcrystalline graphite ranges from 0.11 to 9. wherein 5.The method for preparing the graphite negative electrode material according to claim 1, wherein the stirring speed when mixing the precursor and the catalyst ranges from 100 to 800 rpm. 6.The method for preparing the graphite negative electrode material according to claim 5, wherein the stirring time when mixing the precursor and the catalyst ranges from 30 to 200 min. 7.The method for preparing the graphite negative electrode material according to claim 1, wherein the heating temperature when performing the heating treatment on the first product ranges from 2500 to 3500 ℃. 8.The method for preparing the graphite negative electrode material according to claim 7, wherein the heating furnace used for performing the heating treatment on the first product includes an Acheson furnace, a box furnace, an inner string furnace or a continuous graphite furnace. The raw materials for preparing the catalyst include A parts of Fe 2 O 3, B parts of B 2 O 3 and C parts of SiC, wherein 0 10.The method for preparing the graphite negative electrode material according to claim 1, wherein the catalyst includes A% of Fe 2 O 3, B% of B 2 O 3 and C% of SiC in terms of mass percentage, and the ratio of A+B to C is defined as a catalytic factor, wherein the catalytic factor ranges from 0.11 to 10. The graphite negative electrode material is prepared by the following method, which comprises the following steps: preparing a precursor and a catalyst; mixing the precursor and the catalyst according to a preset mass ratio to obtain a first product; and performing a heating treatment on the first product to obtain the graphite negative electrode material. The mass ratio of the precursor to the catalyst ranges from 2.33 to 19. The raw materials for preparing the catalyst include A parts of Fe 2 O 3, B parts of B 2 O 3 and C parts of SiC, wherein 0≤A≤10, 0≤B≤10, 0 The raw materials for preparing the precursor include at least one of coking raw materials and microcrystalline graphite. ​ wherein ​ ​ wherein ​ ​ ​ ​ ​ 9. The method for preparing the graphite anode material according to claim 1, wherein, ​ ​ ​ 11. A graphite negative electrode material, characterized by, ​ ​ ​ ​ ​ ​ 12. The graphite negative electrode material of claim 11, wherein, ​ 13. The graphite negative electrode material of claim 12, wherein, The particle size of the precursor ranges from 1 to 20 microns.

14. The graphite negative electrode material of claim 13, wherein, The mass ratio of the coking raw material to the microcrystalline graphite ranges from 0.11 to 9.

15. The graphite negative electrode material of claim 11, wherein, The stirring speed when mixing the precursor and the catalyst ranges from 100 to 800 rpm.

16. The graphite negative electrode material of claim 15, wherein, The stirring time when mixing the precursor and the catalyst ranges from 30 to 200 minutes.

17. The graphite negative material of claim 11, wherein, The heating temperature for the first product ranges from 2500 to 3500 degrees Celsius.

18. The graphite negative material of claim 11, wherein, The raw materials for preparing the catalyst include A parts of ferric oxide, B parts of boron oxide and C parts of silicon carbide, wherein 0 < A ≤ 10, 0 < B ≤ 10, 0 < C ≤ 10, and A + B > 0.

19. A battery, characterized by The negative electrode prepared by the graphite negative electrode material of any one of claims 11 to 18.

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