Artificial graphite and method for producing the same and use thereof

Abstract

The application discloses artificial graphite and a preparation method and application thereof. The preparation method of the artificial graphite according to the embodiment of the application comprises the following steps: heat treating a graphite raw material to obtain artificial graphite; wherein, the environmental atmosphere of the heat treatment is a mixed gas of at least one gas selected from oxygen and water vapor and a chemical inert gas; and during the heat treatment, the graphite raw material is in a moving state. The preparation method of the artificial graphite according to the embodiment of the application controls the heat treatment conditions of the graphite raw material, including the atmosphere of the heat treatment and the state of the graphite raw material, so that at least the surface of the graphite raw material is modified, thereby making the artificial graphite powder itself and the formed active layer have high compactness. The artificial graphite according to the application can be used as a negative active material and in a negative electrode and a battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a kind of artificial graphite and its preparation method and application. BACKGROUND

[0002] Energy saving and emission reduction is the key to the sustainable development of automobile industry, and electric vehicles become an important part of the sustainable development of automobile industry due to their energy saving and environmental protection advantages.For electric vehicles, battery technology is an important factor for its development.

[0003] And with the increasing popularity of battery applications, the requirements for related performance such as energy density of the battery are getting higher and higher, and with the increasing market share of electric new energy vehicles, the current demand for endurance is getting higher and higher.

[0004] Among them, electrode material is one of the important factors affecting the related performance of battery.For example, in the battery with carbon as negative electrode material, carbon negative electrode material has important influence on the related performance of battery, especially the performance such as energy density.Among them, graphite has been widely concerned due to its abundant resources, low price, high reversible capacity, low charge and discharge voltage platform, no voltage hysteresis and excellent conductivity, and the research and application of graphite material are not few.However, the publicly reported graphite has low compaction density, which leads to low compaction density of electrode, so that the energy density of electrode and battery is low, thereby affecting the improvement of energy density of battery and restricting the application of battery. SUMMARY

[0005] In view of the above problems, the present application provides a kind of artificial graphite and its preparation method and application to solve the technical problem that the existing graphite leads to low compaction density of electrode.

[0006] In the first aspect, the present application provides a kind of artificial graphite preparation method.The artificial graphite preparation method of the present application comprises the following steps:

[0007] heat treatment of graphite raw material to obtain artificial graphite;

[0008] Among them, the environment atmosphere of heat treatment is a mixed gas of at least one gas including oxygen, water vapor and chemical inert gas;And during the heat treatment process, the graphite raw material is in motion.

[0009] The artificial graphite preparation method of the present application controls the heat treatment conditions of graphite raw material, including the atmosphere of heat treatment and the state of graphite raw material, realizes the modification treatment of at least the surface of graphite raw material, so that the compaction density of artificial graphite powder itself is improved, and at the same time, the electrode active layer prepared by taking the artificial graphite of the present application as active material has high compaction density.

[0010] In some embodiments, the temperature of the heat treatment is 400-900℃.

[0011] In some embodiments, the temperature of the heat treatment is 400-900℃, and the time of the heat treatment is 10-60min.

[0012] By controlling and adjusting the temperature of the heat treatment or further controlling and adjusting the time, the degree of the heat treatment of the graphite is controlled, so as to improve the compaction density of the artificial graphite powder itself and further improve the compaction density of the electrode active layer formed by using the artificial graphite powder as the negative active material.

[0013] In some embodiments, the graphite is in a moving state during the heat treatment. By heat treating the graphite to be treated in a moving state, the modification effect of the heat treatment of the graphite is improved, so as to improve the compaction density of the electrode active layer prepared by using the artificial graphite of the embodiments of the present application as the active material.

[0014] In further embodiments, the moving state is at least one of a continuous fluidized state or a tumbling state.

[0015] In further embodiments, the tumbling state is achieved by rotating the furnace tube, and the rotating speed of the furnace tube is 1-8r / min.

[0016] By heat treating the graphite raw material to be treated in the moving state, the effect of the heat treatment of the graphite is improved.

[0017] In some embodiments, the at least one of the oxygen and the water vapor in the mixed gas accounts for 5%-40% of the total volume of the mixed gas.

[0018] In some embodiments, the mixed gas is introduced at a flow rate of 0-10m 3 / h during the heat treatment.

[0019] By controlling and adjusting the component of the heat treatment atmosphere gas and the flow rate of the introduction, the modification effect of the heat treatment on the graphite raw material is improved.

[0020] In some embodiments, the particle size D v 50 of the graphite raw material is 16.0-24.0μm.

[0021] In some embodiments, the graphite is an artificial graphite material.

[0022] By further selecting the particle size and the type of the graphite raw material, the above heat treatment effect is improved, so as to further improve the compaction density of the artificial graphite powder itself and the compaction density of the active layer.

[0023] In a further embodiment, the method for preparing the artificial graphite material comprises the following steps:

[0024] The solid carbon source is crushed to obtain a granular solid carbon source;

[0025] The granular solid carbon source is shaped to obtain shaped particles;

[0026] The shaped particles are graphitized to obtain an artificial graphite raw material.

[0027] The artificial graphite raw material prepared according to the method can effectively control and adjust the surface, morphology, and particle size of the graphite raw material, thereby improving the heat treatment effect of the graphite raw material by the heat treatment described above, and further improving the compaction density of the artificial graphite and the compaction density of the active layer.

[0028] In a further embodiment, the particle size D of the granular solid carbon source is 16.0-24.0 μm. V 50 is 16.0-24.0 μm. By controlling the particle size of the granular solid carbon source, the particle size of the artificial graphite raw material generated by graphitization can be controlled.

[0029] In a further embodiment, the solid carbon source comprises at least one of petroleum coke, needle coke, pitch coke, and metallurgical coke. These solid carbon sources can be effectively graphitized, and their surface, particle size, and morphology can be flexibly controlled as needed.

[0030] In a further embodiment, before the shaped particles are graphitized, the shaped particles are further subjected to a granulation treatment. By granulating the shaped particles, the surface, particle size, and morphology of the shaped particles can be further controlled and adjusted, thereby controlling and adjusting the surface, particle size, and morphology of the artificial graphite raw material to improve the modification effect of the artificial graphite raw material by heat treatment.

[0031] In a further embodiment, the method for granulation treatment comprises the following steps:

[0032] The carbon source binder is mixed with the shaped particles and then subjected to granulation and molding treatment.

[0033] By this method, the carbon source particles obtained by granulation and molding treatment can improve the modification effect of the artificial graphite raw material by heat treatment after graphitization.

[0034] In a further embodiment, the temperature of the graphitization treatment is 2800-3200 °C. The graphitization treatment can improve the graphitization degree and the effect of heat treatment of the artificial graphite material.

[0035] In a second aspect, the embodiments of the present application provide a kind of artificial graphite.For the artificial graphite prepared by the artificial graphite preparation method of the above application embodiments.

[0036] Since the artificial graphite of the present application is the artificial graphite prepared by the artificial graphite preparation method of the above application embodiments, the artificial graphite material powder itself has high compaction density, thereby endowing the active layer prepared with it as active material with high compaction density.

[0037] In some embodiments, the compaction density and particle size of the artificial graphite of the embodiments of the present application satisfy the following relationship:

[0038] ks=P 5k / (D V 50*G), and 100≤ks≤150;

[0039] wherein, the P 5k is the compaction density of the artificial graphite powder under the pressure of 5000 kg, and the unit is g / cm 3 ; the D V 50 is the average particle size of the artificial graphite, and the unit is μm; the G is the graphitization degree of the artificial graphite, and the unit of the ks is kg / cm 4 .

[0040] When the compaction density P 5k , the particle size D V 50 and the graphitization degree of the artificial graphite of the embodiments of the present application satisfy the above relationship, the artificial graphite powder itself has higher compaction density, and the compaction density of the active layer can be further improved, and the compaction density of the active layer is further improved.

[0041] In some embodiments, the ks is 110≤ks≤130.When the ks is in this range, the compaction density of the artificial graphite powder itself and the compaction density of the active layer of the embodiments of the present application can be further improved.

[0042] In some embodiments, the P 5k is 1.8-2.10 g / cm 3 .

[0043] In further embodiments, the P 5k is 1.85-2.05 g / cm 3 .

[0044] The compaction density of the artificial graphite powder itself of the embodiments of the present application is high.

[0045] In some embodiments, the D V 50 is 16-24.0 μm.

[0046] In further embodiments, the D V 50 is 16.0-18.0 μm.

[0047] The artificial graphite of the embodiments of the present application has a higher compaction density of the artificial graphite itself and a higher compaction density of the active layer formed.

[0048] In some embodiments, the G is 91%-96%.

[0049] In further embodiments, the G is 92%-95%.

[0050] The artificial graphite of the embodiments of the present application has a high graphitization degree.

[0051] In some embodiments, the volume average particle size D v 10 is 4.0-15.0 μm.

[0052] In some embodiments, the volume average particle size D v 90 is 20.0-40.0 μm.

[0053] In some embodiments, the number average particle size D N 10 is 2.0-8.0 μm.

[0054] The artificial graphite of the embodiments of the present application has the above-mentioned particle size characteristics, which can further improve the compaction density of the artificial graphite itself and the compaction density of the active layer.

[0055] In some embodiments, the artificial graphite further has at least one of the following properties:

[0056] The artificial graphite has a gram capacity of 340-365 mAh / g;

[0057] The artificial graphite has a specific surface area of 1.5-2.5 m 2 / g;

[0058] The artificial graphite has a tap density of 0.80-1.20 g / cm 3 .

[0059] In further embodiments, the artificial graphite further has at least one of the following properties:

[0060] The artificial graphite has a gram capacity of 345-363 mAh / g;

[0061] The artificial graphite has a specific surface area of 1.6-2.3 m 2 / g;

[0062] The artificial graphite has a tap density of 0.82-1.18 g / cm 3 .

[0063] The artificial graphite according to the embodiments of the present application has the above-mentioned P 5k In addition to the parameters of the compaction density, particle size and graphitization degree, and the high compaction density of the self powder and the formed active layer, the artificial graphite according to the embodiments of the present application also has the characteristics of high specific surface area and particle morphology such as high tap density, and has high gram capacity.

[0064] In a third aspect, the embodiments of the present application provide a negative electrode material. The negative electrode material according to the embodiments of the present application comprises the artificial graphite according to the embodiments of the present application.

[0065] The negative electrode material according to the embodiments of the present application has high compaction density, and the compaction density is stable, and the formed negative electrode active layer has high compaction density.

[0066] In a fourth aspect, the embodiments of the present application provide a negative electrode. The negative electrode according to the embodiments of the present application comprises the negative electrode material according to the embodiments of the present application.

[0067] Since the negative electrode material contained in the negative electrode according to the embodiments of the present application contains the artificial graphite according to the embodiments of the present application, the active layer has high compaction density, has high energy density and rate characteristics, and has good cycle performance.

[0068] In a fifth aspect, the embodiments of the present application provide a battery. The battery according to the embodiments of the present application comprises the negative electrode according to the embodiments of the present application. Since the battery according to the embodiments of the present application contains the negative electrode according to the embodiments of the present application, the secondary battery has high energy density, high rate and good cycle stability.

[0069] In a sixth aspect, the embodiments of the present application provide an electric device. The electric device according to the embodiments of the present application comprises the battery according to the embodiments of the present application, and the battery is used to provide electric energy. The electric device according to the embodiments of the present application has long standby or endurance time.

[0070] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0071] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not to be considered as limitations on the present application. Moreover, in all the drawings, like reference numerals refer to like parts throughout the several views. In the drawings:

[0072] Figure 1This is a schematic diagram of the preparation method of artificial graphite material according to an embodiment of this application;

[0073] Figure 2 This is a schematic diagram of one embodiment of the secondary battery of this application;

[0074] Figure 3 for Figure 2 The diagram shows an exploded view of the secondary battery.

[0075] Figure 4 This is a schematic diagram of one embodiment of the battery module of this application;

[0076] Figure 5 This is a schematic diagram of one embodiment of the battery pack of this application;

[0077] Figure 6 for Figure 5 The diagram shows the exploded structure of the battery pack.

[0078] Figure 7 This is a schematic diagram of one embodiment of an electrical device that uses a secondary battery as a power source, as described in the present application.

[0079] The reference numerals in the detailed embodiments are as follows:

[0080] 10. Secondary battery cell; 11. Casing; 12. Electrode assembly; 13. Cover plate;

[0081] 20. Battery module;

[0082] 30. Battery pack; 31. Housing; 32. Lower housing. Detailed Implementation

[0083] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0084] 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 pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0085] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly specified and limited.

[0086] Reference herein to "embodiments" means that the particular features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily a separate or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0087] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after it.

[0088] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0089] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0090] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connection", "fixing", and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0091] The related definition explained by the embodiments of the present application is as follows:

[0092] Graphitization degree (G): refers to the degree of carbon atoms forming a dense hexagonal graphite crystal structure, the closer the lattice size is to the ideal graphite lattice parameter, the higher the graphitization degree. The graphitization degree is generally calculated by X-ray diffraction (XRD) method to measure the lattice constant of graphite, and the calculation formula is as follows:

[0093] G=(3.440-d 002 ) / (3.440-3.354);

[0094] Wherein, d 002 is the interplanar spacing of graphite (002) plane obtained by X-ray diffraction, 3.440 is the interplanar spacing of (002) plane of completely non-graphitized carbon, and 3.354 is the interplanar spacing of (002) plane of ideal graphitized carbon.

[0095] Compacted density: refers to the ratio of the surface density of artificial graphite forming active layer to the thickness of the compressed electrode sheet, such as compacted density = surface density / (thickness of the compressed electrode sheet - thickness of the current collector), unit: g / cm 3

[0096] Tap density: refers to the mass per unit volume of artificial graphite powder measured after being vibrated in a container under specified conditions, unit: g / cm 3 .

[0097] Particle size D V 50: refers to the particle size corresponding to 50% of the volume distribution of artificial graphite.

[0098] At present, from the development of market situation, the application of power battery is more and more widely. Power battery is not only applied to energy storage power supply system of hydropower, thermal power, wind power and solar power station, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, military equipment, aerospace and other fields. With the continuous expansion of the application field of power battery, the demand of its market is also increasing, especially in the field of new energy vehicles and unmanned aerial vehicles, the requirement for endurance is getting higher and higher, so the requirement for energy density of battery is getting higher and higher.

[0099] As the lithium ion battery prepared by using carbon material as negative electrode material exhibits certain safety and stability performance, the research on carbon material has attracted the attention of researchers all over the world. The carbon material mainly includes graphite carbon material, non-graphite carbon material, doped carbon material and coated carbon material. Among the numerous carbon negative electrode materials, graphite is rapidly widely concerned due to its abundant resources, low price, high reversible capacity, low charge-discharge voltage platform, no voltage hysteresis, excellent conductivity and other characteristics. Among them, artificial graphite as negative electrode material has good cycle performance and rate performance, and good selectivity to electrolyte.

[0100] However, the inventors found through analysis that the existing artificial graphite mainly focuses on the defects caused by the two-dimensional structure of the graphite material itself in an attempt to improve the cycle performance and rate performance of the graphite, but the effect of the compaction density of the graphite material itself is not obvious or even leads to a decrease in energy density.

[0101] For example, in a disclosed artificial graphite negative electrode material, the preparation method mainly includes: etching the surface of artificial graphite with strong acid or strong base to obtain graphite material A with a porous structure on the surface; mechanically mixing artificial graphite material A, amorphous carbon precursor and conductive agent to obtain graphite-coated precursor B; carbonizing and crushing the graphite-coated precursor B to obtain a surface-coated high-power lithium ion battery graphite negative electrode material.

[0102] The inventors found in the research on the negative electrode material that the surface oxidation treatment by etching with strong acid or strong base and the amorphous carbon coating treatment can improve the large-rate charge-discharge performance of artificial graphite, but the surface oxidation treatment directly leads to a decrease in compaction density and cycle performance, and the compaction density of the amorphous carbon coating layer is also low, thereby the compaction density of the anode electrode sheet decreases and is unstable, further losing energy density. At the same time, the crushing treatment also increases the surface defects, which deteriorates the compaction density and cycle performance of the negative electrode material.

[0103] In order to meet the market requirements for endurance and improve the energy density of the battery, the inventors found in the research that treating the graphite material, such as surface treatment, can effectively improve the compaction density of the graphite material.

[0104] The inventors further study that the improvement of the compaction density of the artificial graphite material itself does not necessarily improve the compaction density of the negative electrode active layer when the artificial graphite material is used as the negative electrode active material. In order to improve the compaction density of the active layer formed by the artificial graphite used as the negative electrode material, the inventors find that the control of the heat treatment conditions of the graphite raw material can at least modify the surface structure or the functional groups contained in the graphite raw material, so that the compaction density of the modified graphite itself is improved, and the compaction density of the negative electrode active layer formed by the modified graphite used as the negative electrode active material is also improved. Thus, the artificial graphite and the preparation method thereof according to the embodiments of the present application are proposed to improve the compaction density of the active layer formed by the artificial graphite used as the negative electrode active material while improving the compaction density of the artificial graphite material itself, so as to improve the energy density of the electrode and the battery.

[0105] Preparation method of artificial graphite

[0106] In a first aspect, the embodiments of the present application provide a preparation method of artificial graphite. The preparation method of the artificial graphite according to the embodiments of the present application comprises the following steps:

[0107] heat-treating the graphite raw material to obtain the artificial graphite;

[0108] In the heat treatment process, the graphite raw material is in a moving state.

[0109] The preparation method of the artificial graphite according to the embodiments of the present application controls the heat treatment atmosphere to be a mixed atmosphere formed by at least one of oxygen and water vapor and a chemical inert gas, and the mixed atmosphere contains components with certain oxidation or other modification effects, such as oxygen and water vapor, so that a reaction can occur between the heat treatment atmosphere and the graphite raw material, and at least the surface of the graphite raw material is modified. In addition, the moving state of the graphite raw material means that the graphite raw material itself is moving, that is, the substrate supporting the graphite raw material is moving.

[0110] Therefore, the preparation method of the artificial graphite according to the embodiments of the present application can modify the graphite raw material including the surface and the morphology of the graphite raw material by heat-treating the graphite raw material in the above atmosphere and in a moving state, so that the artificial graphite powder itself has a high compaction density. When the artificial graphite is used as the negative electrode active material, the compaction density of the active layer formed thereby can be improved.

[0111] In an embodiment, the temperature of the heat treatment can be 400-900°C. In exemplary, but non-limiting, embodiments, the temperature of the heat treatment can be 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, etc. In an embodiment, when the temperature of the heat treatment is 400-900°C, the time of the heat treatment can be 10-60 min. By controlling and adjusting the temperature of the heat treatment or further the time, the modification degree of the heat treatment of the graphite raw material can be controlled, such as to at least improve the modification effect on the surface of the graphite raw material, thereby improving the compaction density of the artificial graphite powder itself, etc. In combination with the particle size of the artificial graphite and the graphitization degree, the range of ks below is further adjusted, thereby improving the compaction density of the artificial graphite powder itself, and improving the compaction density of the active layer formed by using the artificial graphite powder as the active material of the negative electrode, thereby improving the energy density of the negative electrode.

[0112] In some embodiments, the motion state of the graphite can be at least one of a fluidized state or a tumbling state. In an exemplary embodiment, the fluidized state can be achieved by a fluidized bed. The tumbling state can be achieved not only by rotation of the furnace tube, such as rotation of the furnace tube of a horizontal pot or a rotary kiln, but also by other means, such as by loading the graphite raw material to be treated into a rotary kiln and controlling the rotation of the rotary kiln to achieve the motion state of the graphite raw material to be treated.

[0113] When the motion state of the graphite raw material to be treated during the heat treatment is a tumbling state, the tumbling state is achieved by rotation of the furnace tube. In an embodiment, the rotation speed of the furnace tube is 1-8 r / min. By controlling the speed of the tumbling state of the graphite raw material, the modification effect of the heat treatment of the graphite raw material can be improved, and the efficiency and uniformity of the heat treatment can be improved, thereby improving the compaction density of the artificial graphite itself and the compaction density of the active layer formed by using the artificial graphite as the active material of the negative electrode.

[0114] In some embodiments, in the mixed gas of the heat treatment atmosphere for the graphite raw material, at least one of oxygen and water vapor accounts for 5%-40% of the total volume of the mixed gas. By controlling the concentration of oxygen and water vapor in the mixed gas, the modification effect and degree of the heat treatment can be adjusted, thereby improving the modification effect of the heat treatment to further improve the compaction density of the artificial graphite itself and the compaction density of the active layer formed by using the artificial graphite as the active material. In addition, the chemically inert gas in the mixed gas can be nitrogen or an inert gas.

[0115] In some embodiments, during the heat treatment, the mixed gas can be introduced into the heat treatment environment at a flow rate of 0-10 m 3 / h to improve the stability of the heat treatment environment, thereby improving the modification effect of the heat treatment on the graphite raw material.

[0116] In some embodiments, the particle size D of the graphite raw material is 50 v 50 is 16.0-24.0 μm, and further can be 50 V 50 is 16.0-18.0 μm. In other embodiments, the graphitization degree G of the graphite raw material is 91%-96%, and further can be 92%-95%. By further controlling the particle size and the graphitization degree of the graphite raw material, the modification effect of the graphite raw material in the above heat treatment environment can be improved, and the compaction density of the artificial graphite can be increased, and the compaction density and the particle size and the graphitization degree of the artificial graphite can be synergistically increased, so as to adjust and optimize the range of ks value below, such as controlling 100≤ks≤150, so as to further improve the compaction density of the active layer formed by the artificial graphite as the negative active material.

[0117] In some embodiments, the graphite raw material can be an artificial graphite raw material. By selecting the type of the graphite raw material to be heat treated, the modification effect of the above heat treatment can be improved, so as to further improve the compaction density of the artificial graphite itself and the compaction density of the active layer formed by the artificial graphite as the active material. Of course, the above heat treatment can also be directly performed on the natural graphite as the raw material to achieve the modification treatment.

[0118] When the graphite raw material to be heat treated is an artificial graphite raw material, in embodiments, the preparation method of the artificial graphite raw material is as shown in Figure 1 and includes the following steps:

[0119] S01: crushing a solid carbon source to obtain a particulate solid carbon source;

[0120] S02: shaping the particulate solid carbon source to obtain shaped particles;

[0121] S03: graphitizing the shaped particles to obtain an artificial graphite raw material.

[0122] The artificial graphite raw material prepared according to the method can effectively control and adjust the surface, morphology, particle size, etc. of the graphite raw material, so as to improve the modification effect of the above heat treatment on the graphite raw material, and further improve the compaction density of the active layer formed by the artificial graphite as the negative active material.

[0123] Step S01:

[0124] The solid carbon source in step S01 refers to a carbon source that can be used to prepare graphite. In the embodiments, the solid carbon source can include at least one of petroleum coke, needle coke, pitch coke, and metallurgical coke. The solid carbon source can be effectively graphitized, and its surface, particle size, and morphology can be flexibly controlled as needed, thereby improving the graphitization effect, improving the surface, particle size, and morphology of the graphite raw material, and improving the modification effect of the heat treatment, thereby ultimately improving the electrochemical properties of the artificial graphite, including the compaction density.

[0125] The solid carbon source can be crushed according to the particle size requirements to obtain a corresponding particle size. In the embodiments, the particle size D of the granular solid carbon source obtained by crushing is 0.1-1.0 mm. V The particle size D of the granular solid carbon source can be 0.1-1.0 mm. By controlling the particle size of the granular solid carbon source, the particle size of the artificial graphite material generated by the graphitization process can be controlled, thereby controlling the particle size of the artificial graphite obtained by heat treatment in the range of 16.0-24.0 μm.

[0126] In the embodiments, the crushing process can be performed by a crusher.

[0127] Step S02:

[0128] The shaping process of the granular solid carbon source in step S01 can further adjust the surface, particle size, and morphology of the granular solid carbon source, thereby further adjusting the surface, particle size, and morphology of the artificial graphite material, improving the modification effect of the heat treatment of the artificial graphite material, and ultimately improving the electrochemical properties of the artificial graphite, including the compaction density.

[0129] In the embodiments, the shaping process can be a process in which the solid carbon source particles are moved and rubbed against each other, thereby achieving the purpose of particle shaping. For example, a shaper can be used to process the granular solid carbon source.

[0130] In some embodiments, after the shaping process, that is, before the graphitization process of the shaped particles, a granulation process of the shaped particles is further included. The granulation process of the shaped particles can further control and adjust the surface, particle size, and morphology of the shaped particles, thereby controlling and adjusting the surface, particle size, and morphology of the artificial graphite material, improving the modification effect of the heat treatment of the artificial graphite raw material, and ultimately improving the electrochemical properties of the artificial graphite obtained by heat treatment, including the compaction density.

[0131] In the embodiments, the granulation process can include the following steps:

[0132] The carbon source binder is mixed with the shaped particles and then granulated and formed.

[0133] After the carbon source binder is mixed with the shaped particles, the binder can effectively coat and bond the shaped particles. After granulation and molding, the surface, particle size and morphology of the shaped particles can be adjusted, or particles with too small a size can be bonded to form secondary particles. Thus, the carbon source particles obtained by granulation and molding are further improved in surface, particle size and morphology after graphitization, further improving the modification effect of the artificial graphite material by heat treatment, and ultimately improving the electrochemical properties, including the compaction density, of the artificial graphite obtained by heat treatment.

[0134] In the embodiment, the carbon source binder can be mixed with the shaped particles at a ratio of 5-15% of the mass of the carbon source binder to the shaped particles.

[0135] In the exemplary embodiment, the carbon source binder can include at least one of pitch, phenolic resin, and epoxy resin. When the carbon source binder is pitch, the molten pitch is mixed with the shaped particles to ensure that the molten pitch is fully dispersed in the shaped particles.

[0136] The carbon source particles obtained by granulation and molding should ensure that the particle size D v 50 is 16.0-24.0 μm.

[0137] Step S03:

[0138] In step S03, the shaped particles or the carbon source particles obtained by granulation are graphitized to form artificial graphite material. Moreover, the shaped particles or the carbon source particles are precursors of the artificial graphite material, and thus the surface, particle size and morphology of the artificial graphite material obtained by graphitization are further improved, further improving the effect of the artificial graphite material by heat treatment, and ultimately improving the electrochemical properties, including the compaction density, of the artificial graphite obtained by heat treatment.

[0139] In the embodiment, the temperature of the graphitization process can be 2800-3200°C. By controlling and adjusting the temperature of the graphitization process or further controlling and adjusting the time, the surface, particle size and morphology of the artificial graphite material can be further improved to further improve the modification effect of the artificial graphite material by heat treatment. For example, the degree of graphitization G of the artificial graphite material obtained by the graphitization process can be 91-96%, and further can be 92-95%.

[0140] Artificial graphite material

[0141] In a second aspect, the embodiments of the present application provide an artificial graphite. The artificial graphite of the embodiments of the present application is prepared by the artificial graphite preparation method of the above embodiments of the present application.

[0142] The artificial graphite of the present application is prepared by the method described above. Therefore, the surface properties and other characteristics of the artificial graphite of the present application are modified compared to conventional artificial graphite. The artificial graphite of the present application has a high compaction density, and when used as an active material, the active layer formed therefrom also has a high compaction density.

[0143] In some embodiments, the inventors have found that the compaction density and particle size of the artificial graphite of the present application satisfy the following relationship:

[0144] ks = P 5k / (D V 50*G), and 100≤ks≤150.

[0145] wherein P 5k is the compaction density of the artificial graphite of the present application at a pressure of 5000 kg, and in some embodiments, P 5k may be the compaction density of the artificial graphite of the present application at a pressure of 5000 kg for 30 s and a pressure release time of 10 s, and is expressed in g / cm 3 ;

[0146] D V 50 is the average particle size of the artificial graphite of the present application, and is expressed in μm;

[0147] G is the graphitization degree of the artificial graphite of the present application;

[0148] ks is expressed in kg / cm 4 .

[0149] The inventors have found that when the compaction density P 5k , the average particle size D V 50 and the graphitization degree of the artificial graphite of the present application satisfy the above relationship, the artificial graphite of the present application has a high compaction density, and the active layer formed therefrom also has a high compaction density. Thus, when used as a negative electrode material, the energy density of the negative electrode and the battery can be improved.

[0150] In some embodiments, the inventors have further found that by adjusting the conditions of the heat treatment in the method described above, the compaction density P 5k , the average particle size D V 50 and the graphitization degree of the artificial graphite of the present application can be controlled.50 and its graphitization degree is adjusted so that ks is 110-130, that is, 110≤ks≤130. When ks is in this range, the compaction density of the artificial graphite material of the embodiments of the present application is higher, the bonding strength between the artificial graphite particles is high, and the compaction density is stable. At the same time, the active layer formed also has a higher compaction density.

[0151] In some embodiments, it is detected that the artificial graphite of the embodiments of the present application has at least the following properties:

[0152] The P 5k of the artificial graphite of the embodiments of the present application is 1.80-2.10 g / cm 3 , and can further be 1.85-2.05 g / cm 3 . Specifically, it can be 1.80 g / cm 3 , 1.83 g / cm 3 , 1.85 g / cm 3 , 1.90 g / cm 3 , 1.95 g / cm 3 , 2 g / cm 3 , 2.05 g / cm 3 , 2.10 g / cm 3 , etc. 5k The compaction density of the artificial graphite of the embodiments of the present application and the active layer formed is high, and the P 5k compaction density in this range, together with the particle size and graphitization degree data, can control the ks value in the above to be 100≤ks≤150, and can further be controlled to be 110≤ks≤130. Among them, the P 5k value is the compaction density value of the powder of the artificial graphite of the embodiments of the present application under a pressure of 5000 kg for 30 s and a pressure relief of 10 s.

[0153] The D V 50 of the artificial graphite of the embodiments of the present application can be 16-24.0 μm, and can further be 16.0-18.0 μm; as in the exemplary examples, it can be 16.0 μm, 17.0 μm, 18.0 μm, 19.0 μm, 20.0 μm, 21.0 μm, 22.0 μm, 23.0 μm, 24.0 μm, etc. V The D V 50 particle size in this range can simultaneously improve the compaction density of the artificial graphite of the embodiments of the present application and the active layer formed.

[0154] The graphitization degree G of the artificial graphite in the embodiments of the present application can be controlled to be 91% to 96%, and further can be 92% to 95%; for example, in the exemplary embodiments, the graphitization degree can be 91%, 92%, 93%, 94%, 95%, 96%, and the like, which are typical but not limiting. Therefore, the graphitization degree of the artificial graphite in the embodiments of the present application is high, and in combination with the above-mentioned D V 50 and P 5k The value of ks is controlled and optimized to the above-mentioned range, so as to further improve the compaction density of the artificial graphite itself and the active layer formed.

[0155] In addition, the P 5k The compaction density, particle size and graphitization degree parameter range, and the ks value in the above-mentioned embodiments of the present application can be controlled to be 100≤ks≤150, and further can be controlled to be 110≤ks≤130. That is, by optimizing the respective ranges of the three, the comprehensive performance of the artificial graphite material in the embodiments of the present application can be comprehensively improved, such as improving the surface characteristics, improving the compaction density and other performances of the artificial graphite in the embodiments of the present application, and enhancing the bonding strength between the artificial graphite particles.

[0156] In some embodiments, the inventors further research and test to find that the artificial graphite in the embodiments of the present application has at least one particle size characteristic as follows:

[0157] The volume average particle size D v 10 of the artificial graphite can be 4.0 to 15.0 μm, and further can be 6.0 to 10.0 μm; for example, in the exemplary embodiments, the D V 10 particle size can be 4.0 μm, 5.0 μm, 6.0 μm, 7.0 μm, 8.0 μm, 9.0 μm, 10.0 μm, 11.0 μm, 12.0 μm, 13.0 μm, 14.0 μm, 15.0 μm, and the like, which are typical but not limiting. V

[0158] The volume average particle size D v 90 of the artificial graphite can be 20.0 to 40.0 μm, and further can be 24.0 to 35.0 μm; for example, in the exemplary embodiments, the D V 90 particle size can be 20.0 μm, 21.0 μm, 22.0 μm, 23.0 μm, 24.0 μm, 25.0 μm, 26.0 μm, 27.0 μm, 28.0 μm, 29.0 μm, 30.0 μm, 31.0 μm, 32.0 μm, 33.0 μm, 34.0 μm, 35.0 μm, 36.0 μm, 37.0 μm, 38.0 μm, 39.0 μm, 40.0 μm, and the like, which are typical but not limiting. V

[0159] The number average particle size D N10 can be 2.0–8.0 μm, and more specifically 3.0–5.0 μm; in the exemplary examples, it can be typical but non-limiting D such as 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, 6.0 μm, 7.0 μm, and 8.0 μm. N 10 particle size.

[0160] In this application embodiment, the artificial graphite has the above-mentioned P... 5k Within the range of compaction density, particle size, and degree of graphitization parameters, it also possesses the aforementioned particle size characteristics, thereby further improving the compaction density of the artificial graphite in the embodiments of this application and enhancing the bonding strength between artificial graphite particles.

[0161] In some embodiments, the inventors further investigated and tested, and found that the artificial graphite in the above embodiments of this application also has at least one of the following features:

[0162] The BET specific surface area of ​​artificial graphite can range from 1.5 to 2.5 m². 2 / g, and further can be 1.6–2.3m 2 / g; In the example, it can be 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g, 2.0m 2 / g、2.1m 2 / g, 2.2m 2 / g, 2.3m 2 / g, 2.4m 2 / g, 2.5m 2 Typical but not limiting specific surface areas include / g, etc.

[0163] The tap density of artificial graphite can range from 0.80 to 1.20 g / cm³. 3 Furthermore, it can be 0.82–1.18 g / cm³. 3 In the example, it could be 0.80 g / cm³. 3 0.85g / cm 3 0.90g / cm 3 0.95g / cm 3 1.00g / cm 3 1.05g / cm 3 1.10 g / cm 3 1.15g / cm 3 1.20g / cm 3 Typical but not limiting tap density.

[0164] The artificial graphite can have a gravimetric capacity of 340-365 mAh / g, further 345-363 mAh / g; in exemplary embodiments, it can have a gravimetric capacity of 340 mAh / g, 343 mAh / g, 345 mAh / g, 348 mAh / g, 350 mAh / g, 353 mAh / g, 355 mAh / g, 358 mAh / g, 360 mAh / g, 362 mAh / g, 365 mAh / g, etc.

[0165] Therefore, the artificial graphite itself and the active layer formed by the artificial graphite according to the embodiments of the present application have high tap density, and the artificial graphite has high P 5k The tap density, particle size, and graphitization degree can satisfy the above relationship, and the artificial graphite has high specific surface area and high tap density, which can further improve the tap density of the artificial graphite itself and the active layer formed by the artificial graphite, and enhance the bonding strength between the artificial graphite particles. Moreover, the artificial graphite has high gravimetric capacity.

[0166] Negative electrode material

[0167] In a third aspect, the embodiments of the present application provide a negative electrode material. The negative electrode material according to the embodiments of the present application comprises artificial graphite.

[0168] In the negative electrode material according to the embodiments of the present application, the artificial graphite contained therein is the artificial graphite according to the embodiments of the present application. Thus, the negative electrode material itself and the active layer formed by the negative electrode material have high tap density, the bonding strength between the negative electrode material particles is high, the tap density is stable, and the electrode containing the negative electrode material has high energy density.

[0169] Of course, the negative electrode material according to the embodiments of the present application can contain other negative electrode materials or additives that can assist the negative electrode material in playing its role, in addition to the artificial graphite according to the embodiments of the present application. The other negative electrode materials or additives that can be compounded with the artificial graphite to play the active role of the negative electrode material or assist the artificial graphite in playing its active role of the negative electrode material are within the scope disclosed in the embodiments of the present application.

[0170] Negative electrode

[0171] In a fourth aspect, the embodiments of the present application provide a negative electrode. The negative electrode material contained in the negative electrode according to the embodiments of the present application comprises the artificial graphite according to the embodiments of the present application or the negative electrode material according to the embodiments of the present application.

[0172] Since the negative electrode material contained in the negative electrode of the embodiment contains the artificial graphite of the embodiment, the negative electrode active layer formed by the negative electrode material has high compactness, low compactness rebound, and good electrical conductivity, thereby giving the negative electrode of the embodiment high energy density and rate characteristics, and good cycle performance.

[0173] In the embodiment, the negative electrode of the embodiment can include a negative current collector and a negative electrode active layer combined on the negative current collector.

[0174] In the embodiment, the negative electrode of the embodiment can include a negative current collector and a negative electrode active layer combined on the negative current collector.

[0175] In the embodiment, the negative electrode of the embodiment can include a negative current collector and a negative electrode active layer combined on the negative current collector.

[0176] In the embodiment, the negative electrode of the embodiment can include a negative current collector and a negative electrode active layer combined on the negative current collector.

[0177] In the embodiment, the negative electrode of the embodiment can include a negative current collector and a negative electrode active layer combined on the negative current collector.

[0178] In the embodiment, the negative electrode of the embodiment can include a negative current collector and a negative electrode active layer combined on the negative current collector.

[0179] Battery

[0180] In the embodiment, the negative electrode of the embodiment can include a negative current collector and a negative electrode active layer combined on the negative current collector.

[0181] In the example, the battery in this application embodiment can be a secondary battery. When the battery in this application embodiment is a secondary battery, it includes a positive electrode, a separator, and a negative electrode. That is, the negative electrode contained in the secondary battery is the negative electrode of the above application embodiment, that is, the negative electrode contains the artificial graphite of the above application embodiment.

[0182] Thus, the battery in the embodiments of this application, specifically a secondary battery, has high energy density, as well as high rate capability and good cycle stability.

[0183] In the embodiments of this application, the secondary battery may include any one of a battery cell, a battery module, or a battery pack.

[0184] Here, a battery cell refers to both the battery casing and the battery cell encapsulated within it. There are no particular restrictions on the shape of a battery cell; it can be cylindrical, square, or any other arbitrary shape. For example... Figure 2 The shown is a square-structured battery cell 10.

[0185] In some embodiments, such as Figure 3 As shown, the outer packaging of the battery cell 10 may include a housing 11 and a cover plate 13. The housing 11 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the cover plate 13 is used to cover the opening to close the receiving cavity. The positive electrode, separator and negative electrode contained in the secondary battery of this application embodiment may be formed into an electrode assembly 12 by a winding process and / or a stacking process. The electrode assembly 12 is encapsulated in the receiving cavity. Electrolyte is immersed in the electrode assembly 12. The number of electrode assemblies 12 contained in the battery cell 10 may be one or more, which can be adjusted according to actual needs.

[0186] The method for preparing the battery cell 10 is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form the battery cell 10. As an example, the positive electrode, the separator, and the negative electrode can be formed into an electrode assembly 12 by a winding process or a stacking process. The electrode assembly 12 is placed in an outer package, dried, and then injected with an electrolyte. After vacuum sealing, settling, formation, shaping, and other processes, the battery cell 10 is obtained.

[0187] A battery module is assembled from the battery cell 10, which means it can contain multiple battery cells 10. The specific number can be adjusted according to the application and capacity of the battery module.

[0188] In some embodiments, Figure 4 This is a schematic diagram of battery module 20 as an example. (See diagram for example.) Figure 4As shown, in the battery module 20, a plurality of battery cells 10 can be arranged in sequence along the length direction of the battery module 20. Of course, the plurality of battery cells 10 can also be arranged in any other manner. The plurality of battery cells 10 can be fixed by fasteners.

[0189] Optionally, the battery module 20 can also include a housing having an accommodation space, and the plurality of battery cells 10 are accommodated in the accommodation space.

[0190] A battery pack refers to an assembly of the above battery cells 10, i.e., can contain a plurality of battery cells 10, wherein the plurality of battery cells 10 can be assembled into the above battery module 20. The number of battery cells 10 or battery modules 20 contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0191] As an example, Figure 5 and Figure 6 is a schematic diagram of a battery pack 30 as an example. The battery pack 30 can include a battery box and a plurality of battery modules 20 arranged in the battery box. The battery box includes an upper box body 31 and a lower box body 32, the upper box body 31 is used to cover the lower box body 32, and forms a closed space for accommodating the battery modules 20. The plurality of battery modules 20 can be arranged in the battery box in any manner.

[0192] Electric device

[0193] In a sixth aspect, the embodiments of the present application also provide an electric device, which includes the secondary battery of the above embodiments of the present application. The secondary battery can be used as a power supply of the electric device, or can be used as an energy storage unit of the electric device. Therefore, the electric device of the embodiments of the present application has a long standby or endurance time.

[0194] The electric device can be, but is not limited to, a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc. The electric device can select a secondary battery, a battery module or a battery pack according to its use requirements.

[0195] Figure 7 is a schematic diagram of an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of high power and high energy density of the electric device, a battery pack or a battery module can be used.

[0196] As another example of an electric device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The electric device usually requires thin and light, and a secondary battery can be used as a power supply.

[0197] Examples

[0198] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are for the purpose of explanation only and are not to be taken as limiting the present application. In the examples, where a specific technique or condition is not mentioned, the technique or condition described in the literature in the field or according to the product manual is used. Where the manufacturer of a reagent or instrument is not mentioned, a conventional product available from the market is used.

[0199] 1. Artificial graphite and method for producing the same

[0200] Example A1

[0201] The present example provides an artificial graphite and a method for producing the same. The method for producing the artificial graphite of the present example includes the following steps:

[0202] S1. Preparation of artificial graphite raw material:

[0203] S11: Coarsely crush the petroleum coke raw material with a jaw crusher, finely crush the material with a mechanical mill, and then classify the material to obtain a particulate solid carbon source;

[0204] S12: Perform a shaping treatment on the particulate solid carbon source in step S11 to obtain shaped particles having a Dv50 of 12 μm;

[0205] S13: Mix the shaped particles in step S12 with a binder pitch (Dv50 of 5 μm to 8 μm) in an amount of 10% by mass of the shaped particles, and perform a mixing treatment at a stirring speed of 1200 r / min and a temperature of 560°C to obtain carbon source particles having a particle size of 20 μm;

[0206] S14: Perform a graphitization treatment at 3000°C on the carbon source particles obtained in step S13, and then sieve the particles to obtain an artificial graphite;

[0207] S2. Heat treatment:

[0208] Increase the temperature of the rotary kiln to 400°C, rotate the tube at a speed of 5 r / min, and supply a mixed gas of O2 and N2 (O2 content of 40%) at a flow rate of 8 m 3 / h, and uniformly feed the artificial graphite raw material prepared in step S1 into the cavity of the rotary kiln from the feed inlet of the rotary kiln at a constant speed to perform a heat treatment for 60 min. After completing the surface treatment in the cavity, cool the material to obtain an artificial graphite.

[0209] Example A2

[0210] The present example provides an artificial graphite and a method for producing the same. The method for producing the artificial graphite of the present example includes the following steps:

[0211] S1. Preparation of artificial graphite raw material: refer to step S1 of Example A1.

[0212] S2. Heat treatment:

[0213] The rotary kiln was heated to 500℃, the furnace tube rotation speed was 7r / min, the mixed gas of O2 and N2 (O2 content was 30%) gas flow was 5m 3 / h, the artificial graphite raw material prepared in step S1 was uniformly fed into the cavity of the rotary kiln through the rotary feeder from the feeding port of the rotary kiln for heat treatment for 45min, and after the surface treatment was completed in the cavity, cooling was performed to obtain artificial graphite.

[0214] Example A3

[0215] The present embodiment provides a kind of artificial graphite and its preparation method.The artificial graphite preparation method of the present embodiment includes the following steps:

[0216] S1. Preparation of artificial graphite raw material: refer to step S1 of Example A1.

[0217] S2. Heat treatment:

[0218] The rotary kiln was heated to 600℃, the furnace tube rotation speed was 2r / min, the mixed gas of O2 and N2 (O2 content was 20%) gas flow was 8m 3 / h, the artificial graphite raw material prepared in step S1 was uniformly fed into the cavity of the rotary kiln through the rotary feeder from the feeding port of the rotary kiln for heat treatment for 25min, and after the surface treatment was completed in the cavity, cooling was performed to obtain artificial graphite.

[0219] Example A4

[0220] The present embodiment provides a kind of artificial graphite and its preparation method.The artificial graphite preparation method of the present embodiment includes the following steps:

[0221] S1. Preparation of artificial graphite raw material: refer to step S1 of Example A1.

[0222] S2. Heat treatment:

[0223] The rotary kiln was heated to 650℃, the furnace tube rotation speed was 3r / min, the mixed gas of water vapor and N2 (water vapor volume content was 40%) gas flow was 3m 3 / h, the artificial graphite raw material prepared in step S1 was uniformly fed into the cavity of the rotary kiln through the rotary feeder from the feeding port of the rotary kiln for heat treatment for 20min, and after the surface treatment was completed in the cavity, cooling was performed to obtain artificial graphite.

[0224] Example A5

[0225] The present embodiment provides a kind of artificial graphite and its preparation method.The compacted density P5k D V The graphitization degree G, specific surface area S, and specific capacity are shown in Table 1 below.

[0226] The method for preparing artificial graphite in this embodiment includes the following steps:

[0227] S1. Preparation of artificial graphite raw materials: Refer to step S1 of Example A1;

[0228] S2. Heat treatment:

[0229] The rotary kiln is heated to 700℃, the furnace tube speed is 3 r / min, and the O2 and N2 mixed gas (O2 content 5% and gas flow rate 3 m) is used. 3 / h, the artificial graphite raw material prepared in step S1 is fed into the rotary kiln cavity at a uniform speed through the rotary kiln feed port by a rotary feeder for heat treatment for 45 minutes. After surface treatment is completed in the cavity, it is cooled to obtain artificial graphite.

[0230] Example A6

[0231] This embodiment provides an artificial graphite and its preparation method. The artificial graphite preparation method of this embodiment includes the following steps:

[0232] S1. Preparation of artificial graphite raw materials: Refer to step S1 of Example A1;

[0233] S2. Heat treatment:

[0234] The rotary kiln is heated to 850℃, the furnace tube speed is 8 r / min, and the flow rate of the mixed gas of water vapor and N2 (water vapor content is 5%) is 3 m³ / min. 3 / h, the artificial graphite raw material prepared in step S1 is fed into the rotary kiln cavity at a uniform speed through the rotary kiln feed port by a rotary feeder for heat treatment for 30 minutes. After surface treatment is completed in the cavity, it is cooled to obtain artificial graphite.

[0235] Example A7

[0236] This embodiment provides an artificial graphite and its preparation method. The artificial graphite preparation method of this embodiment includes the following steps:

[0237] S1. Preparation of artificial graphite raw materials: Refer to step S1 of Example A1;

[0238] S2. Heat treatment:

[0239] The rotary kiln is heated to 850℃, the furnace tube speed is 1 r / min, and the flow rate of the mixed gas of water vapor and N2 (water vapor content is 10%) is 5 m³ / min. 3 / h, the artificial graphite raw material prepared in step S1 was uniformly fed into the cavity of the rotary kiln through a rotary feeder from the rotary kiln feeding port for heat treatment for 15 min, and after the surface treatment was completed in the cavity, the artificial graphite was obtained after cooling.

[0240] Example A8

[0241] The present embodiment provides an artificial graphite and a preparation method thereof. The artificial graphite preparation method of the present embodiment comprises the following steps:

[0242] S1. Preparation of artificial graphite raw material: refer to step S1 of Example A1;

[0243] S2. Heat treatment:

[0244] The rotary kiln was heated to 900℃, the rotary speed of the furnace tube was 3r / min, and the gas flow of the mixed gas of water vapor and N2 (the water vapor content was 5%) was 5m 3 / h, the artificial graphite raw material prepared in step S1 was uniformly fed into the cavity of the rotary kiln through a rotary feeder from the rotary kiln feeding port for heat treatment for 10 min, and after the surface treatment was completed in the cavity, the artificial graphite was obtained after cooling.

[0245] Comparative Example A1

[0246] The present comparative example provides an artificial graphite and a preparation method thereof. The artificial graphite of the present comparative example is the artificial graphite prepared in step S1 of Example A1.

[0247] The artificial graphite preparation method of the present comparative example comprises the following steps:

[0248] The artificial graphite was prepared according to step S1 of the artificial graphite preparation method of Example A1.

[0249] Comparative Example A2

[0250] The present comparative example provides an artificial graphite and a preparation method thereof. The artificial graphite preparation method of the present comparative example comprises the following steps:

[0251] S1. Preparation of artificial graphite raw material: refer to step S1 of Example A1;

[0252] S2. Heat treatment:

[0253] The rotary kiln was heated to 300℃, the rotary speed of the furnace tube was 5r / min, and the gas flow of pure oxygen was 5m 3 / h, the artificial graphite raw material prepared in step S1 was uniformly fed into the cavity of the rotary kiln through a rotary feeder from the rotary kiln feeding port for heat treatment for 30 min, and after the surface treatment was completed in the cavity, the artificial graphite was obtained after cooling.

[0254] Comparative Example A3

[0255] The comparative example provides a kind of artificial graphite and its preparation method.The artificial graphite preparation method of comparative example includes the following steps:

[0256] S1. Preparation of artificial graphite raw material: refer to step S1 of example A1;

[0257] S2. Heat treatment:

[0258] The rotary kiln is heated to 600 DEG C, the speed of furnace tube is 2r / min, the pure nitrogen gas flow is 12m 3 / h, the artificial graphite raw material prepared in step S1 is uniformly entered into the cavity of rotary kiln through rotary feeder from the feeding port of rotary kiln for heat treatment for 120min, and the surface treatment is completed in the cavity, and then cooled to obtain artificial graphite.

[0259] Comparative example A4

[0260] The comparative example provides a kind of artificial graphite and its preparation method.The artificial graphite preparation method of comparative example includes the following steps:

[0261] S1. Preparation of artificial graphite raw material: refer to step S1 of example A1;

[0262] S2. Heat treatment:

[0263] The rotary kiln is heated to 550 DEG C, the speed of furnace tube is 2r / min, the pure nitrogen gas flow is 12m 3 / h, the artificial graphite raw material prepared in step S1 is uniformly entered into the cavity of rotary kiln through rotary feeder from the feeding port of rotary kiln for heat treatment for 180min, and the surface treatment is completed in the cavity, and then cooled to obtain artificial graphite.

[0264] Comparative example A5

[0265] The comparative example provides a kind of artificial graphite and its preparation method.The artificial graphite of comparative example has the compaction density P 5k , D V 50 and graphitization degree G, specific surface area S, gram capacity respectively as shown in table 1.

[0266] The artificial graphite preparation method of comparative example includes the following steps:

[0267] S1. Preparation of artificial graphite raw material: refer to step S1 of example A1;

[0268] S2. Heat treatment:

[0269] The rotary kiln is heated to 800 DEG C, the speed of furnace tube is 2r / min, the pure oxygen gas flow is 12m 3 / h, the artificial graphite raw material prepared in step S1 is uniformly fed into the cavity of the rotary kiln through a rotary feeder from the rotary kiln feeding port for heat treatment, and after the surface treatment is completed in the cavity, the artificial graphite is obtained after cooling.

[0270] Comparative Example A6

[0271] The comparative example provides an artificial graphite and a preparation method thereof. The tap density P of the comparative example artificial graphite 5k , D V 50 and the graphitization degree G, the specific surface area S and the gravimetric capacity are shown in Table 1 as follows.

[0272] The preparation method of the comparative example artificial graphite comprises the following steps:

[0273] S1. Preparation of artificial graphite raw material: refer to step S1 of Example A1;

[0274] S2. Heat treatment:

[0275] The rotary kiln is heated to 950℃, the rotary tube speed is 10r / min, the pure nitrogen gas flow rate is 1m 3 / h, the artificial graphite raw material prepared in step S1 is uniformly fed into the cavity of the rotary kiln through a rotary feeder from the rotary kiln feeding port for heat treatment, and after the surface treatment is completed in the cavity, the artificial graphite is obtained after cooling.

[0276] 2. Secondary battery cell examples

[0277] Examples B1 to B8 and Comparative Examples B1 to B6.

[0278] The examples B1 to B18 and comparative examples B1 to B6 respectively provide a secondary battery cell, each secondary battery cell comprising an electrode core formed by a positive electrode, a separator and a negative electrode, and further comprising an electrolyte. Among them,

[0279] The positive electrode is prepared according to the following method:

[0280] The positive electrode active material LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), a conductive agent (Super P) and a binder PVDF are fully stirred and mixed in a proper amount of NMP at a weight ratio of 96.2:2.7:1.1 to form a uniform positive electrode slurry; the positive electrode slurry is coated on the surface of the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained; the tap density of the positive electrode is measured to be 3.45g / cm 3 ;

[0281] The negative electrode is prepared according to the following method:

[0282] The artificial graphite, conductive agent (Super P), binder (SBR), thickening agent (CMC-Na) were mixed in a proper amount of deionized water in a mass ratio of 96.2:0.8:1.8:1.2, and stirred sufficiently to form a uniform negative electrode slurry; the negative electrode slurry was coated on the surface of the negative electrode current collector copper foil, and after drying and cold pressing, a negative electrode sheet was obtained, wherein the artificial graphite was the artificial graphite provided in the above examples A1 to A8 and the artificial graphite provided in the above comparative examples A1 to A6, and the artificial graphite provided in example A1 was used to make the negative electrode contained in the secondary battery monomer in example B1, the artificial graphite provided in example A2 was used to make the negative electrode contained in the secondary battery monomer in example B2, and so on, and the artificial graphite provided in comparative example A1 was used to make the negative electrode contained in the secondary battery monomer in comparative example B1; and the compaction density and the area density of the negative electrode were shown in Table 1, respectively.

[0283] Electrolyte: ethylene carbonate (EC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and then LiPF6 was uniformly dissolved in the above solution to obtain an electrolyte, wherein the concentration of LiPF6 was 1 mol / L;

[0284] Separator film: polyethylene (PE) film.

[0285] Secondary battery assembly: the positive electrode, the separator and the negative electrode were stacked in sequence to form an electric core, and the bare electric core was placed in an outer package, the above electrolyte was injected and packaged to obtain a secondary battery monomer, respectively.

[0286] Artificial graphite and secondary battery monomer related data test

[0287] The artificial graphite and secondary battery monomer provided in the above examples and comparative examples were tested for the related items in Table 1 as follows, and the test results were shown in Table 1 as follows:

[0288] Other properties in Table 1 were determined according to national standards or industry standards.

[0289] Table 1

[0290]

[0291]

[0292] As can be seen from Table 1, when the graphite raw material is subjected to the specific heat treatment according to the artificial graphite preparation method of the present application, the graphite raw material can be effectively modified at least in terms of surface properties, and the physical and electrochemical properties of the artificial graphite can be effectively changed, such as enabling the artificial graphite material itself and the active layer formed to have a high compaction density. On this basis, the compaction density P 5kand graphitization degree and particle size D V 50 meet the relationship shown by ks above, and ks is controlled between 100-150, or further controlled between 110-130, which can effectively further improve the compaction density of the artificial graphite forming active layer. The electrode compaction densities of Examples A1-A8 are all significantly higher than the electrode compaction densities of Comparative Examples A1-A6, and at the same time, the energy densities of the batteries are also significantly higher than the energy densities of the batteries in the comparative examples.

[0293] Therefore, according to the artificial graphite preparation method of the present application, the graphite raw material is subjected to a specific heat treatment according to the present application, which can effectively improve the compaction density of the modified artificial graphite itself and the corresponding active layer, and further control the η / P5k of the modified artificial graphite in an appropriate range, such as making the compaction density P 5k and graphitization degree and particle size D V 50 meet the relationship shown by ks above, and ks is controlled between 100-150, or further controlled between 110-130. When in this ks value range, the compaction density of the artificial graphite material of the present application is significantly improved, and the particles have strong adhesion and high conductivity, the negative electrode prepared therefrom contains a negative active layer with high compaction density, high energy density, and the negative active layer structure is stable, and has good cycle performance, thereby endowing the secondary battery monomer containing the negative electrode with high energy density, and also has high rate capability and good cycle stability.

[0294] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered in the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for producing artificial graphite, characterized by, The method comprises the following steps: The graphite raw material is subjected to heat treatment to obtain artificial graphite; The environment atmosphere of the heat treatment comprises a mixed gas of at least one of oxygen and water vapor and a chemical inert gas, and the chemical inert gas is nitrogen or an inert gas; and during the heat treatment, the graphite raw material is in a moving state.

2. The method of claim 1, wherein: The temperature of the heat treatment is 400-900℃; or The temperature of the heat treatment is 400-900℃, and the time of the heat treatment is 10-60 min.

3. The production method according to claim 1 or 2, characterized by: The moving state of the graphite raw material is at least one of a continuous fluidized state and a rolling state.

4. The method of claim 3, wherein: The rolling state is realized by rotation of a furnace tube or a mechanical rod, and the rotation speed of the furnace tube or the mechanical rod is 1-8 r / min.

5. The production method according to claim 1 or 2, characterized by: The at least one of oxygen and water vapor in the mixed gas accounts for 5%-40% of the total volume of the mixed gas; and / or The mixed gas is introduced at a flow rate of 0 to 10 m 3 / h during the heat treatment process.

6. The preparation method according to claim 1 or 2, characterized in that: The particle size D of the graphite raw material v 50 is 16.0 to 24.0 μm; and / or The graphite raw material is an artificial graphite raw material.

7. The method of claim 6, wherein: The preparation method of the artificial graphite raw material comprises the following steps: The solid carbon source is subjected to crushing treatment to obtain a granular solid carbon source; The granular solid carbon source is subjected to shaping treatment to obtain shaped particles; The shaped particles are subjected to graphitization treatment to obtain an artificial graphite raw material.

8. The method of claim 7, wherein: The particle size D of the particulate solid carbon source V 50 is 16.0 to 24.0 μm; and / or The solid carbon source comprises at least one of petroleum coke, needle coke, pitch coke and metallurgical coke; and / or The temperature of the graphitization treatment is 2800-3200℃; and / or Before the shaped particles are subjected to the graphitization treatment, the shaped particles are further subjected to granulation treatment.

9. The method of claim 8, wherein: The method of the granulation treatment comprises the following steps: The carbon source binder is mixed with the shaped particles and then subjected to granulation forming treatment.

10. Artificial graphite, characterized by, The artificial graphite is prepared by the preparation method of any one of claims 1-9.

11. Artificial graphite according to claim 10, characterized in that The artificial graphite satisfies the following relationship between the compacted density and the particle size: ks = P 5k / (D V 50*G), and 100≤ks≤150; Wherein, the P 5k is the compaction density of the artificial graphite powder under a pressure of 5000 kg, and the unit is g / cm 3 ; the D V 50 is the average particle size of the artificial graphite, and the unit is μm; the G is the graphitization degree of the artificial graphite, and the unit of the ks is kg / cm 4 .

12. Artificial graphite according to claim 11, characterized in that: The ks is 110≤ks≤130.

13. Artificial graphite according to any one of claims 11-12, characterized in that: The P 5k is 1.80-2.10 g / cm -3 ; and / or The D V 50 is 16.0 to 24.0 μm; and / or The G is 91%-96%.

14. Artificial graphite according to claim 13, characterized by: The P 5k is 1.85-2.05 g / cm -3 ; and / or The D V 50 is 16.0 to 18.0 μm; and / or The G is 92%-95%.

15. Artificial graphite according to any one of claims 10 to 12, characterized in that: The volume average particle diameter D of the artificial graphite is 0.1 to 10 μm. v 10 is 4.0 to 15.0 μm; and / or The volume average particle diameter D of the artificial graphite is 0.1 to 20 μm. v 90 is 20.0 to 40.0 μm; and / or The number average particle diameter D of the artificial graphite is 0.1 to 10 μm. N 10 is 2.0 to 8.0 μm.

16. Artificial graphite according to any one of claims 10 to 12, characterized in that: The artificial graphite further has at least one of the following properties: The gram capacity of the artificial graphite is 340-365 mAh / g; The specific surface area of the artificial graphite is 1.5-2.5 m 2 / g; The tap density of the artificial graphite is 0.80-1.20 g / cm 3 .

17. The artificial graphite according to claim 16, characterized by: The artificial graphite further has at least one of the following properties: The gram capacity of the artificial graphite is 345-363 mAh / g; The specific surface area of the artificial graphite is 1.6-2.3 m 2 / g; The tap density of the artificial graphite is 0.82-1.18 g / cm 3 .

18. A negative electrode material, characterized by: The negative electrode comprises the artificial graphite of any one of claims 10-17 or the negative electrode material of claim 18.

19. A negative electrode, characterized by: The negative electrode comprises the artificial graphite of any one of claims 10-17 or the negative electrode material of claim 18.

20. A battery, characterized by: The use electric device comprises the battery of claim 20, and the battery is used to provide electric energy.

21. An electrical device, comprising: ​

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