Preparation method and application of negative electrode material

Abstract

The invention provides a preparation method and application of a negative electrode material, and the preparation method comprises the following steps: calculating m according to a formula: n = a * (m) 2 + b * m + c; wherein a is-0.0077, b is 0.9108, c is 326.8, n is the preset gram volume of the prepared negative electrode material, and the unit is mAh / g; petroleum coke with the mass percentage content of medium aromatic hydrocarbon being m% is selected and subjected to graphitization treatment, and the negative electrode material is obtained. According to the preparation method, the preparation raw materials are regulated and controlled through a specific relational expression, the negative electrode material close to the preset gram volume can be prepared, the preparation method is novel, the preparation process is simple, controllability is high, and industrial production of the negative electrode material is facilitated.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a method for preparing a negative electrode material and its application. Background Art

[0002] At present, lithium-ion batteries are widely used in many fields such as electronic equipment and transportation due to their advantages of high energy density and excellent cycle performance. Artificial graphite is a common negative electrode material for lithium-ion batteries. Different application scenarios have different requirements for the gram capacity of graphite negative electrode materials. In the prior art, it is difficult to directly prepare graphite negative electrode materials that are highly adapted to the gram capacity required for different application scenarios, which is not conducive to promoting the commercial application of graphite negative electrode materials. Therefore, it is necessary to provide a method for preparing a negative electrode material that can adjust the preparation process according to the required gram capacity to obtain a gram capacity as close as possible to the required negative electrode material, thereby improving the degree of adaptation for multi-scenario applications. Summary of the invention

[0003] In view of this, the present application provides a method for preparing a negative electrode material and its application. The preparation method can prepare a negative electrode material with a capacity close to a preset gram capacity by regulating the preparation raw materials through a specific relationship. The preparation method is novel, the preparation process is simple, and the controllability is high, which is conducive to the industrial production of negative electrode materials.

[0004] In a first aspect, the present application provides a method for preparing a negative electrode material, comprising:

[0005] According to the formula: n = a × (m) 2 +b×m+c, m is calculated; where a is -0.0077, b is 0.9108, c is 326.8, and n is the preset gram capacity of the pre-prepared negative electrode material, in mAh / g;

[0006] Petroleum coke with a mass percentage of m% of medium-weight aromatic hydrocarbons is selected and graphitized to obtain the negative electrode material. The medium-weight aromatic hydrocarbons include polycyclic aromatic hydrocarbons and cycloalkanes with 2 to 4 benzene rings.

[0007] Optionally, n is 340 mAh / g-355 mAh / g, and the mass percentage of the medium-weight aromatic hydrocarbons is 20%-75%.

[0008] Optionally, the temperature of the graphitization treatment is 2800°C-3100°C.

[0009] Optionally, the particle size D50 of the petroleum coke is 9 μm-17 μm.

[0010] Optionally, the sulfur content of the petroleum coke is less than or equal to 3%, and the volatile matter of the petroleum coke is less than or equal to 14%.

[0011] The preparation method provided in the present application can prepare negative electrode materials with a preset gram capacity by regulating the composition of the prepared raw materials through a specific relationship between the prepared raw materials and the preset gram capacity of the pre-prepared negative electrode materials. The preparation process is simple and has better controllability, which is conducive to the commercial application of negative electrode materials.

[0012] In a second aspect, the present application provides a method for predicting the gram capacity of a negative electrode material, comprising: obtaining the mass percentage content m% of medium-quality aromatic hydrocarbons in petroleum coke; according to the formula: n = a × (m) 2 +b×m+c, and n is calculated; wherein a is -0.0077, b is 0.9108, c is 326.8, and n is the predicted gram capacity of the negative electrode material, in units of mAh / g. The present application provides a method for predicting the gram capacity of a negative electrode material, which can directly predict the gram capacity of the prepared negative electrode material from the perspective of preparing raw materials, thereby achieving the purpose of simplifying the process flow.

[0013] In a third aspect, the present application provides a method for selecting petroleum coke based on a preset gram capacity of a negative electrode material, comprising: determining a preset gram capacity n of a pre-prepared negative electrode material in units of mAh / g; according to the formula: n=a×(m) 2 +b×m+c, m is calculated; wherein a is -0.0077, b is 0.9108, and c is 326.8; and m is the mass percentage of medium aromatics in petroleum coke.

[0014] The present application provides a method for selecting petroleum coke based on a preset gram capacity of a negative electrode material, which can select petroleum coke based on a preset gram capacity of a negative electrode material, and is conducive to obtaining a negative electrode material with an ideal gram capacity.

[0015] In a fourth aspect, the present application provides a negative electrode material, which is prepared by the preparation method described in the first aspect.

[0016] In a fifth aspect, the present application provides a negative electrode plate, which includes the negative electrode material prepared by the preparation method described in the first aspect or the negative electrode material described in the fourth aspect.

[0017] In a sixth aspect, the present application provides a battery, comprising a positive electrode plate and the negative electrode plate described in the fifth aspect.

[0018] In a seventh aspect, the present application provides an electrical device, wherein the electrical device comprises the battery described in the sixth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the prior art description. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0020] Figure 1 A flowchart of extracting aromatics from petroleum coke provided in one embodiment of the present application;

[0021] Figure 2 This is the aromatics distribution diagram after three expansions in one embodiment of the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The present application provides a method for preparing a negative electrode material, comprising: according to the formula: n = a × (m) 2 +b×m+c, m is calculated; wherein, a is -0.0077, b is 0.9108, c is 326.8, and n is the preset gram capacity of the pre-prepared negative electrode material, in units of mAh / g; petroleum coke with a mass percentage of medium aromatic hydrocarbons of m% is selected, and the negative electrode material is obtained after graphitization. The preparation method provided in the present application selects petroleum coke that meets the relationship according to a specific relationship formed by the mass percentage of medium aromatic hydrocarbons in petroleum coke and the preset gram capacity of the pre-prepared negative electrode material, and obtains a negative electrode material as close to the preset gram capacity as possible after graphitization. The present application regulates the preparation of raw materials by preparing a specific relationship formed by the preset gram capacity of the raw materials and the negative electrode material, and the prepared negative electrode material has a test gram capacity that is very close to the preset gram capacity, thereby improving the adaptability of the negative electrode material to different application scenarios. The preparation method is novel, the preparation process is simple, the controllability is high, and it is conducive to the wide application of negative electrode materials.

[0024] In one embodiment of the present application, the preset gram capacity of the pre-prepared negative electrode material is n mAh / g. The mass percentage of the required medium-quality aromatics in the petroleum coke is calculated by the above formula. According to the calculated mass percentage of the medium-quality aromatics, the petroleum coke that meets the mass percentage requirement of the medium-quality aromatics is selected. After graphitization treatment, a negative electrode material as close to the preset gram capacity as possible can be obtained. In one embodiment of the present application, the preset gram capacity of the pre-prepared negative electrode material is 348.1 mAh / g. Substituting into the specific formula: n = a × (m) 2+b×m+c, a is -0.0077, b is 0.9108, c is 326.8, and the mass percentage of the required medium-weight aromatics in the petroleum coke is calculated to be 29.94% (m%). The petroleum coke containing 29.94% of the mass percentage of the medium-weight aromatics is selected, and after graphitization treatment, the negative electrode material is obtained. The gram capacity of the negative electrode material is tested to be 345 mAh / g, and the gram capacity of the obtained negative electrode material is close to the preset gram capacity of the negative electrode material. In some embodiments, the preset gram capacity of the pre-prepared negative electrode material is n mAh / g. The mass percentage of the required medium-weight aromatics in the petroleum coke is calculated by the above formula, and the mass percentage of the medium-weight aromatics of two different values ​​can be obtained. Any petroleum coke that meets the mass percentage requirements of the medium-weight aromatics can be selected, and after graphitization treatment, a negative electrode material as close to the preset gram capacity as possible can be obtained.

[0025] In one embodiment of the present application, the preset gram capacity (n) of the negative electrode material is 340mAh / g-355mAh / g. Specifically, the preset gram capacity of the negative electrode material may be, but is not limited to, 340mAh / g, 342mA h / g, 344mA h / g, 346mA h / g, 348mA h / g, 350mA h / g, 352mA h / g or 355mA h / g, etc. In one embodiment of the present application, the preset gram capacity (n) of the negative electrode material may be 340mA h / g-350mA h / g. In another embodiment of the present application, the preset gram capacity (n) of the negative electrode material may be 347mA h / g-355mAh / g.

[0026] In the present application, petroleum coke includes medium-quality aromatic hydrocarbons, which are mainly polycyclic aromatic hydrocarbons with 2-4 benzene rings, and a small amount of cycloalkanes. The mass percentage content (m) of medium-quality aromatic hydrocarbons is 20%-75%. The appropriate content of medium-quality aromatic hydrocarbons can improve the kinetics of the intermediate phase fusion during the graphitization treatment of petroleum coke, improve the degree of crystallization of the negative electrode material, and thus improve the gram capacity of the negative electrode material. If the content of medium-quality aromatic hydrocarbons is too low, the aromaticity is low, the carbonization rate is low during the graphitization treatment, the intermediate phase cannot be well fused, and it is not easy to generate a good streamlined structure. If the content of medium-quality aromatic hydrocarbons is too high, the aromaticity is increased, the carbonization rate is increased, and the intermediate phase has no time to fuse, and a good streamlined structure cannot be obtained, which further affects the gram capacity of the negative electrode material. Specifically, the mass percentage content of medium-quality aromatic hydrocarbons can be, but is not limited to, 20%, 30%, 40%, 50%, 60%, 70% or 75%, etc. In one embodiment of the present application, the mass content of medium-quality aromatic hydrocarbons can be 20%-55%. In another embodiment of the present application, the mass content of the medium-weight aromatics may be 50%-75%.

[0027] In one embodiment of the present application, the test gram capacity of the negative electrode material is the preset gram capacity of the negative electrode material ±3 mAh / g. Due to the gram capacity test instrument, method and other reasons, there is a certain error between the preset gram capacity and the test gram capacity. The error between the test gram capacity of the negative electrode material and the preset gram capacity of the negative electrode material can be within ±3 mA h / g. The gram capacity of the negative electrode material can be accurately predicted by the preparation method provided in the present application, thereby improving the adaptability of multiple scene applications.

[0028] See also Figure 1 , which is a flow chart for extracting aromatics from petroleum coke provided in one embodiment of the present application, comprising:

[0029] Mix petroleum coke and n-heptane and filter to obtain insoluble matter;

[0030] The insoluble matter is mixed with toluene, filtered and concentrated to obtain concentrated aromatics;

[0031] The concentrated aromatics are developed and separated to obtain medium aromatics. In one embodiment of the present application, 3 g of petroleum coke powder is mixed with 30 ml of n-heptane, stirred and extracted for 1 hour, and the filter residue is filtered and collected to obtain insoluble matter; the insoluble matter is mixed with 30 ml of toluene, stirred and extracted for 2 hours, the filtrate is filtered and collected, and concentrated by rotary evaporation to obtain concentrated aromatics; the concentrated aromatics are placed on a silica gel column of a four-component analyzer, and light aromatics, medium aromatics and heavy aromatics are obtained after development and separation, and placed in a hydrogen flame ionization detector (FID) to obtain the mass percentage of medium aromatics.

[0032] In one embodiment of the present application, the expansion and separation process includes one expansion, two expansions and three expansions, and the principle of like dissolves like is used, that is, the solubility or adsorption force of each component in the concentrated aromatics on the silica gel column and in different solvents is different. After three expansion processes, the concentrated aromatics are separated into light aromatics, medium aromatics and heavy aromatics. Figure 2 As shown, it is the aromatic hydrocarbon distribution diagram after three expansions in one embodiment of the present application.

[0033] In one embodiment of the present application, a first developing solution is used for a development, the first developing solution is a mixed solution of n-heptane and toluene with a volume ratio of 95:5, and the time for a development is 35min-45min. The light aromatic hydrocarbons in the concentrated aromatic hydrocarbons can be separated by a development. Specifically, the time for a development can be, but is not limited to, 35min, 37min, 39min, 40min, 42min or 45min. In one embodiment of the present application, the time for a development can be 35min-40min. In another embodiment of the present application, the time for a development can be 40min-45min.

[0034] In one embodiment of the present application, a second developing solution is used for secondary development, the second developing solution is a mixed solution of n-heptane and toluene in a volume ratio of 80:20, the time of secondary development is 12min-17min, and the secondary development can separate the medium-quality aromatic hydrocarbons in the concentrated aromatic hydrocarbons. Specifically, the time of secondary development can be but not limited to 12min, 13min, 14min, 15min, 16min or 17min, etc. In one embodiment of the present application, the time of secondary development can be 12min-15min. In another embodiment of the present application, the time of secondary development can be 14min-17min.

[0035] In one embodiment of the present application, three developments are performed using a third developing solution, the third developing solution is a mixed solution of n-heptane and toluene in a volume ratio of 50:50, the time for the three developments is 3 min-5 min, and the three developments can separate heavy aromatics from concentrated aromatics. Specifically, the time for the three developments can be, but is not limited to, 3 min, 3.5 min, 4 min, 4.5 min or 5 min, etc. In one embodiment of the present application, the time for the three developments can be 3 min-4.5 min. In another embodiment of the present application, the time for the three developments can be 4 min-5 min.

[0036] In one embodiment of the present application, the particle size D50 of the petroleum coke is 9μm-17μm, and the obtained negative electrode material has a test gram capacity that is very close to the preset gram capacity, which improves the adaptability of the negative electrode material to different application scenarios. Specifically, the particle size D50 of the petroleum coke can be, but is not limited to, 9μm, 10μm, 11μm, 13μm, 15μm or 17μm, etc. In one embodiment of the present application, the particle size D50 of the petroleum coke can be 9μm-15μm. In another embodiment of the present application, the particle size D50 of the petroleum coke can be 13μm-17μm.

[0037] In one embodiment of the present application, the sulfur content of petroleum coke is less than or equal to 3%, and the obtained negative electrode material has a test gram capacity that is very close to the preset gram capacity, which improves the adaptability of the negative electrode material to different application scenarios. Specifically, the sulfur content of petroleum coke can be, but is not limited to, less than or equal to 3%, less than or equal to 2.5%, less than or equal to 2%, less than or equal to 1.5%, or less than or equal to 1%, etc. In one embodiment of the present application, the sulfur content of petroleum coke can be less than or equal to 2.5%. In another embodiment of the present application, the sulfur content of petroleum coke can be less than or equal to 2%.

[0038] In one embodiment of the present application, the negative electrode material obtained by the volatile matter of petroleum coke is less than or equal to 14% has a test gram capacity very close to the preset gram capacity, which improves the adaptability of the negative electrode material to different application scenarios. Specifically, the volatile matter of petroleum coke can be, but is not limited to, less than or equal to 14%, less than or equal to 12%, less than or equal to 10%, less than or equal to 8%, less than or equal to 6%, or less than or equal to 4%. In one embodiment of the present application, the volatile matter of petroleum coke can be less than or equal to 8%. In another embodiment of the present application, the volatile matter of petroleum coke can be less than or equal to 6%. In some embodiments, the national standard for testing volatile matter in petroleum coke is SH / T0026-90.

[0039] The present application also provides a method for predicting the gram capacity of negative electrode materials, comprising: obtaining the mass percentage content m% of medium-quality aromatic hydrocarbons in petroleum coke; according to the formula: n = a × (m) 2 +b×m+c, and n is calculated; where a is -0.0077, b is 0.9108, c is 326.8, and n is the predicted gram capacity of the negative electrode material, in mAh / g. This method can be used to predict the gram capacity of the prepared negative electrode material starting from petroleum coke, avoiding the complex process of preparing and testing the negative electrode material to obtain its gram capacity, and simplifying the process flow.

[0040] The present application also provides a method for selecting petroleum coke based on a preset gram capacity of a negative electrode material, comprising: determining a preset gram capacity n of a pre-prepared negative electrode material in units of mAh / g; according to the formula: n=a×(m) 2 +b×m+c, m is calculated; where a is -0.0077, b is 0.9108, c is 326.8; m is the mass percentage (%) of medium-weight aromatics in petroleum coke. This method can directly preset the gram capacity of the negative electrode material, and the formula can be used to select the petroleum coke that can produce the negative electrode material that meets the preset gram capacity.

[0041] The present application also provides a negative electrode material, which is prepared by the preparation method described in any one of the above embodiments. The preparation cost of the negative electrode material is low, and the specific capacity performance is excellent, which is conducive to the multi-scenario application of the negative electrode material.

[0042] The present application also provides a negative electrode plate, comprising the negative electrode material described in any of the above embodiments.

[0043] In one embodiment of the present application, the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer disposed on the surface of the negative electrode current collector, and the negative electrode active material layer comprises the negative electrode material described in any of the above embodiments. The negative electrode plate provided by the present application has high capacity and good cycle stability.

[0044] In one embodiment of the present application, the negative electrode current collector may include, but is not limited to, at least one of copper, aluminum, nickel and stainless steel. In one embodiment of the present application, the negative electrode current collector may be copper foil.

[0045] In one embodiment of the present application, the negative electrode active material layer also includes a negative electrode conductive agent, which can increase the conductivity of the negative electrode material and improve the electronic conductivity. Specifically, the negative electrode conductive agent may include but is not limited to at least one of graphite, carbon black, acetylene black and graphene. In one embodiment of the present application, the negative electrode conductive agent may be graphite. In another embodiment of the present application, the negative electrode conductive agent may be carbon black.

[0046] In one embodiment of the present application, the negative electrode active material layer also includes a negative electrode binder, which can improve the binding ability of the components in the negative electrode active material layer and improve the binding ability between the negative electrode active material layer and the current collector. Specifically, the negative electrode binder can be, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polybutadiene, acrylic resin, epoxy resin, polyethylene oxide, sodium carboxymethyl cellulose and styrene-butadiene latex. In one embodiment of the present application, the negative electrode binder can be polyvinylidene fluoride. In another embodiment of the present application, the negative electrode binder can be sodium carboxymethyl cellulose. The present application also provides a battery, including the negative electrode sheet provided in any of the above embodiments.

[0047] In one embodiment of the present application, the battery further comprises a positive electrode sheet. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material.

[0048] In one embodiment of the present application, the positive electrode current collector may be, but is not limited to, at least one of copper, aluminum, nickel and stainless steel. In one embodiment of the present application, the positive electrode current collector may be aluminum foil.

[0049] In one embodiment of the present application, the positive electrode active material can improve the conductivity, gram capacity and cycle stability of the positive electrode plate. The specific positive electrode active material can include but is not limited to at least one of lithium iron phosphate material, lithium iron manganese phosphate, lithium cobalt oxide material, lithium manganese oxide material, nickel cobalt manganese material and nickel cobalt aluminum material. In one embodiment of the present application, the positive electrode active material can be a lithium cobalt oxide material.

[0050] In one embodiment of the present application, the positive electrode active material layer also includes a positive electrode conductive agent. The positive electrode conductive agent can increase the conductivity between the active materials and improve the electronic conductivity. Specifically, the positive electrode conductive agent may include but is not limited to at least one of graphite, carbon black, acetylene black and graphene. In one embodiment of the present application, the positive electrode conductive agent may be graphite. In another embodiment of the present application, the positive electrode conductive agent may be carbon black.

[0051] In one embodiment of the present application, the positive electrode active material layer also includes a positive electrode binder, which can improve the binding ability of the components in the positive electrode active material layer and improve the binding ability between the positive electrode active material layer and the positive electrode current collector. Specifically, the positive electrode binder can be, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polybutadiene, acrylic resin, epoxy resin, polyethylene oxide, sodium carboxymethyl cellulose and styrene-butadiene latex. In one embodiment of the present application, the positive electrode binder can be polyvinylidene fluoride.

[0052] In one embodiment of the present application, the battery further includes a separator disposed between the positive electrode sheet and the negative electrode sheet. Specifically, the separator may be, but is not limited to, a woven membrane, a non-woven fabric, a microporous membrane, a composite membrane, a rolled membrane, or a separator paper. In one embodiment of the present application, the battery further includes an electrolyte. Among them, at least part of the positive electrode sheet and at least part of the negative electrode sheet are immersed in the electrolyte. The electrolyte of the present application is not particularly limited, and may be, but is not limited to, a substance that can be used as a battery electrolyte in the art.

[0053] The present application also provides an electric device, which includes a battery provided by any one of the above embodiments. The electric device of the present application may refer to a vehicle, an electronic device, an energy storage system, etc.

[0054] The effect of the technical solution of the present application is further illustrated below through specific examples.

[0055] Example 1

[0056] The preset gram capacity of the pre-prepared negative electrode material is 352.5 mAh / g, according to n = a × (m) 2 +b×m+c, a is -0.0077, b is 0.9108, c is 326.8, and m is calculated to be 46.65. Petroleum coke with a mass percentage of medium-weight aromatics of 46.65% is selected, and after graphitization treatment at 3000°C, it is ground and sieved to obtain the negative electrode material.

[0057] Example 2-Example 20

[0058] The only difference between Example 2 to Example 20 and Example 1 is that the preset gram capacity of the pre-prepared negative electrode material and the mass percentage content of the corresponding selected medium-quality aromatic hydrocarbons in petroleum coke are different.

[0059] Performance Testing

[0060] The negative electrode material prepared in the above-mentioned Examples 1 to 20 was mixed with styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and conductive carbon black (SP) to prepare a negative electrode slurry, wherein the mass ratio of the negative electrode material, styrene-butadiene rubber, carboxymethyl cellulose and conductive carbon black was 95.5:2:1.5:1; the negative electrode slurry was coated on the negative electrode collector (copper foil), and the negative electrode sheet was obtained after drying and roll pressing, and assembled with the metal lithium sheet into a button battery.

[0061] The batteries prepared in the above-mentioned Examples 1 to 20 were subjected to electrochemical performance tests, and the test process was as follows: the gram capacity of the button-type battery was tested under the conditions of 0.1C constant current charge and discharge and charge and discharge voltage of 0.05-2.0V. The test results are shown in Table 1.

[0062] Table 1 Performance test results of negative electrode materials

[0063]

[0064]

[0065] According to Examples 1 to 20 of the present application, it can be seen that the method for preparing the negative electrode material provided by the present application can calculate the mass percentage of the medium-quality aromatic hydrocarbons in the required petroleum coke by presetting the gram capacity, select the petroleum coke according to the calculated value, and prepare the negative electrode material. The test gram capacity of the prepared negative electrode material is close to the preset gram capacity. In other words, the method for preparing the negative electrode material provided by the present application can be used to prepare a negative electrode material with an ideal gram capacity, or the relationship can be used to achieve the purpose of screening raw materials by presetting the gram capacity, or the relationship can be used to control the mass content of the medium-quality aromatic hydrocarbons in the petroleum coke to obtain a negative electrode material with a preset gram capacity.

[0066] The above is a preferred embodiment of the present application, but it should not be understood as limiting the scope of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A method for preparing a negative electrode material, characterized in that: include: According to the formula: n = a × (m) 2 +b×m+c, m is calculated; where a is -0.0077, b is 0.9108, c is 326.8, and n is the preset gram capacity of the pre-prepared negative electrode material, in mAh / g; Petroleum coke with a mass percentage of m% of medium-weight aromatic hydrocarbons is selected and graphitized to obtain the negative electrode material. The medium-weight aromatic hydrocarbons include polycyclic aromatic hydrocarbons and cycloalkanes with 2 to 4 benzene rings.

2. The preparation method according to claim 1, characterized in that n is 340mA h / g-355mAh / g, and the mass percentage of the medium-weight aromatic hydrocarbons is 20%-75%.

3. The preparation method according to claim 1, characterized in that: The temperature of the graphitization treatment is 2800°C-3100°C.

4. The preparation method according to claim 1, characterized in that: The particle size D50 of the petroleum coke is 9 μm-17 μm; the sulfur content of the petroleum coke is less than or equal to 3%; and the volatile matter of the petroleum coke is less than or equal to 14%.

5. A method for predicting the gram capacity of a negative electrode material, characterized in that: include: Obtain the mass percentage content m% of medium aromatic hydrocarbons in petroleum coke; According to the formula: n = a × (m) 2 +b×m+c, and n is calculated; wherein a is -0.0077, b is 0.9108, and c is 326.8, and n is the predicted gram capacity of the negative electrode material, in mAh / g.

6. A method for selecting petroleum coke based on a preset gram capacity of anode material, characterized in that: include: Determine the preset gram capacity n of the pre-prepared negative electrode material in mAh / g; According to the formula: n = a × (m) 2 +b×m+c, calculate m; where a is -0.0077, b is 0.9108, and c is 326.8; The m is the mass percentage of medium-quality aromatics in petroleum coke.

7. A negative electrode material, characterized in that: The negative electrode material is prepared by the preparation method according to any one of claims 1 to 4.

8. A negative electrode plate, characterized in that: The negative electrode plate comprises the negative electrode material prepared by the preparation method according to any one of claims 1 to 4 or the negative electrode material according to claim 7.

9. A battery, characterized in that: The battery comprises the negative electrode sheet according to claim 8.

10. An electrical device, characterized in that: The electrical device comprises the battery according to claim 9.

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