Anthracite-based fast-charging type carbon negative electrode material and preparation method thereof

Abstract

The invention discloses an anthracite-based fast-charging carbon negative electrode material and a preparation method thereof.The preparation method comprises the steps that firstly, component separation is conducted on anthracite, meanwhile, the dual effects of reducing ash content and separating maceral components are achieved, then grading treatment is conducted by means of the density and hardness difference of vitrinite and inertinite, small-particle-size vitrinite is further sufficiently enriched, and the carbon negative electrode material is obtained. The content of vitrinite in the auxiliary material B is larger than or equal to 96 wt%, and then the auxiliary material B is subjected to hot air oxidation treatment to be subjected to a cross-linking reaction, so that the auxiliary material B is promoted to form a hard-carbon-like structure in the high-temperature carbonization process; meanwhile, collecting a mixed material containing 50-70wt% of vitrinite and 30-40wt% of inertinite as a main material A, and graphitizing the main material A; the graphitized main material A, the oxidized auxiliary material B and a binder are heated, fused and carbonized to form a graphite / hard-like carbon hybrid structure, and the anthracite-based fast-charging carbon negative electrode material with excellent electrochemical performance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of negative electrode material preparation, and more specifically, to a carbon negative electrode material and a preparation method thereof. Background Art

[0002] With the rapid economic development and the acceleration of the industrialization process, the global energy consumption and demand have increased sharply. The energy resource crisis and environmental problems have made it urgent to develop clean, efficient, and sustainable renewable energy. Therefore, new energy sources such as wind energy and solar energy have attracted much attention. The transportation industry, as one of the main sources of global greenhouse gases, has also become the focus of global attention. Achieving electrified transportation is crucial for achieving the carbon neutrality goal. Electric vehicles and plug-in hybrid vehicles driven by lithium-ion batteries have gradually become the focus of people's attention. According to the prediction of the International Energy Agency (IEA), the global electric vehicle industry will experience significant growth in the next decade, and the global electric vehicle ownership is expected to reach 230 million by 2030. At present, although electric vehicles have made rapid progress in terms of long mileage and low cost, they still lack consumer acceptance and have a low market penetration rate. One of the reasons is that the charging time of electric vehicles is relatively long, and the range anxiety problem cannot be effectively solved.

[0003] Since it is difficult to significantly improve the battery capacity in a short time, developing lithium-ion batteries with fast charging capabilities has become the cornerstone for further promoting the marketization of electric vehicles. Fast charging is expected to charge the battery in a few minutes like a gas station, but most electric vehicles on the market require 2-6 hours to be fully charged, which results in a poor driving experience. Therefore, the lithium-ion batteries currently used in the electric vehicle market need to be greatly improved to meet the requirements of fast charging. Some commercial high-power batteries can discharge at 10C, but the maximum charging rate of most lithium-ion batteries is limited to 3C. Commonly used graphite has poor kinetics and a low working potential (0.1V vs Li / Li + )), and serious problems will occur at high charging rates exceeding 1C, such as mechanical cracks, electrolyte side reactions, and anode polarization, which will cause lithium deposition and heat generation, leading to performance degradation and safety problems. Therefore, the key challenge in designing fast-charging lithium-ion batteries is to construct negative electrode materials with high rate capabilities and high safety.

[0004] The limiting factors for fast charging can generally be divided into two aspects: the first is mass transfer, including the transport of Li + in the electrolyte and the electrode material; the other is charge transfer, which involves the solvation / desolvation of Li + and Li +Diffusion across the cathode-electrolyte interface (CEI) and the anode-electrolyte interface (AEI). In order to improve the fast charging performance of lithium-ion batteries, researchers have also done a lot of research. For example, the invention patent with publication number CN118198338A provides a method for preparing a graphite negative electrode material, mixing raw materials including graphite, coating carbon material and Li3PO4, and heat treating them under a protective atmosphere at a temperature of 900 to 1250°C for 2 to 5 hours to obtain a graphite negative electrode material; by making Li3P evenly distributed in amorphous carbon and coated on the surface of graphite, and during use, Li3N is deposited on the surface of the amorphous carbon layer by electrochemical action, and under the dual synergistic effect of the fast ion conductor Li3N / Li3P, the fast charging performance of the lithium-ion battery is improved.

[0005] For example, the invention patent with publication number CN118213602A provides a method for preparing a fast-charging negative electrode material and a lithium-ion battery, including graphitizing a mixture of a coke raw material and a potassium compound, followed by washing to obtain a first precursor; pre-lithiation treatment of the first precursor to obtain a second precursor; and depositing amorphous carbon on the outer layer of the second precursor to obtain a fast-charging negative electrode material; the invention can utilize potassium molecules decomposed from potassium compounds during the graphitization process to increase the interlayer spacing of graphite to improve the fast-charging performance of the fast-charging negative electrode material.

[0006] For another example, the invention patent with publication number CN118306989A provides a method for preparing a modified graphite negative electrode material, which comprises graphitizing flaky natural graphite at 2600°C to 3000°C under a protective atmosphere to prepare a first intermediate; depositing nano-carbon material on the surface of the first intermediate to prepare a second intermediate; and thermally reducing the second intermediate at 500°C to 1000°C under a protective atmosphere to prepare a modified graphite negative electrode material. The invention improves the crystal integrity by graphitizing flaky natural graphite; then depositing nano-carbon material on the surface and performing thermal reduction treatment to improve the conductivity and structural stability of the graphite material, thereby obtaining a negative electrode material with good rate performance and cycle stability, which is suitable for high-rate fast-charging batteries.

[0007] For example, the invention patent with publication number CN118198325A provides a modified artificial graphite negative electrode material and a preparation method. First, pre-oxidation is performed to form rich oxygen-containing functional groups on the surface of the artificial graphite, and then a dense lithium titanate coating layer is formed by ball milling with lithium titanate; then a concentrated sulfuric acid oxidation step is performed to obtain a porous structure and increase the interlayer spacing of the artificial graphite; the synthesized modified artificial graphite has excellent fast charging capability, and the reversible specific capacity of 10C charge and discharge is greater than 250mAh / g.

[0008] In summary, in order to effectively solve the fast charging problem of lithium-ion batteries, a large number of studies have focused on methods such as pre-lithiation, surface activation for pore formation, nano-carbon coating, and oxidation modification. However, these methods require the addition of a large amount of expensive nano-materials or the use of chemical reagents such as acids and alkalis, which pose more requirements for equipment resistance to acids and alkalis, further increase costs, and may also face certain engineering and technical problems. Summary of the Invention

[0009] In view of the above, in order to overcome the problems in the prior art such as the need for special pore formation and the introduction of new element doping modification to obtain fast-charging carbon anode materials, the present invention provides an anthracite-based fast-charging carbon anode material and a preparation method thereof. By effectively regulating the macerals of anthracite, an anthracite-based fast-charging carbon anode material is obtained.

[0010] The present invention provides an anthracite-based fast-charging carbon anode material, which is a material with a graphite / hard carbon-like composite structure: the inside is a material with a graphite structure, and the material with a graphite structure is formed after graphitization of anthracite containing 50-70 wt% of vitrinite and 30-40 wt% of inertinite; the outside is a hard carbon-like structure material, and the hard carbon-like structure material is formed after oxidation of anthracite containing ≥96 wt% of vitrinite.

[0011] The material with a graphite structure is formed after graphitization of anthracite containing 65 wt% of vitrinite and 34 wt% of inertinite.

[0012] The material with a graphite structure is formed after graphitization of anthracite containing 60 wt% of vitrinite and 30 wt% of inertinite.

[0013] The macerals of coal can be divided into organic macerals and inorganic macerals. Among them, the organic macerals can be divided into vitrinite, inertinite, and exinite. The physical properties and chemical compositions of different macerals are different, and there are also obvious differences in their physical and chemical evolution pathways. A large number of research results show that different macerals have different responses to temperature and change with the degree of coal metamorphism. The macerals and coal microstructure will change significantly. Therefore, the maceral composition may be an important reason for the difference in coal graphitization. Among them, some studies have confirmed that vitrinite and inertinite have obvious differential effects on the graphitization of anthracite. Vitrinite is more likely to be graphitized than inertinite. Based on this, in the present invention, a component with a relatively high vitrinite content is selected inside the anthracite-based fast-charging carbon anode material, which is beneficial to the formation of a graphitized structure inside the particles. However, when the vitrinite content ≥ 96 wt%, a single too-high vitrinite component is prone to cross-linking due to the influence of internal oxygen-containing functional groups and forms a relatively hard carbon structure, making it difficult to be graphitized. Therefore, using this characteristic, the present invention selects a hybrid of a mixed material with a relatively low content of inertinite and a relatively high content of vitrinite as the internal material, which is beneficial to the graphitization of the internal material and forms a graphite structure. The external material of the anthracite-based fast-charging carbon anode material uses a vitrinite material with a content ≥ 96 wt% to form a hard carbon-like structure, which is beneficial to improving the lithium-ion transmission rate. The influence of other macerals other than vitrinite and inertinite on the formation of the graphitized structure of the internal material and the hard carbon-like structure of the external material can be ignored.

[0014] The present invention provides a preparation method of an anthracite-based fast-charging carbon anode material, comprising the following steps:

[0015] (1) Crush anthracite and reduce its ash content to 5-10 wt% through coal preparation technology to obtain clean coal;

[0016] (2) Grind the clean coal to 200-500 mesh, and use component separation technology to increase its vitrinite content to 70-80 wt% and reduce its ash content to 0.5-2 wt% at the same time to obtain ultra-low ash anthracite;

[0017] (3) After drying the ultra-low ash anthracite, perform shaping and classification. The main material A collected in the receiving bin of the classifier after classification is a mixed material containing 50-70 wt% of vitrinite and 30-40 wt% of inertinite, and the secondary material B collected in the dust collector of the classifier is a material containing a vitrinite content ≥ 96 wt%;

[0018] (4) Pre-carbonize the main material A under a protective gas. The pre-carbonization temperature is 800 - 1000 °C, and then carry out graphitization treatment in a graphitization furnace at 2800 - 3200 °C to obtain graphitized main material A; at the same time, carry out oxidation treatment on the secondary material B in hot air to obtain oxidized secondary material B;

[0019] (5) Mix the graphitized main material A, the oxidized secondary material B and the binder evenly, then carry out heating and fusion for 0.5 - 2 h, and finally carry out final carbonization treatment at a constant temperature of 1200 - 1500 °C for 0.5 - 2 h to obtain an anthracite-based fast-charging carbon negative electrode material.

[0020] The carbon content in the anthracite is ≥ 80 wt%; preferably, the sulfur content in the anthracite is less than 1.0 wt% and the carbon content is ≥ 88 wt%.

[0021] Among them, the ash content of the preferably ultra-low-ash anthracite is 0.5 - 1.0 wt%.

[0022] Among them, the anthracite in step (1) is crushed to 6 - 13 mm. The crushing means include jaw crushing, hammer crushing, cone crushing, roller crushing, ball milling, high-pressure grinding, impact crushing and compound crushing.

[0023] The coal preparation technology includes ultrasonic coal preparation, dense medium coal preparation or jigging coal preparation technology. Preferably, dense medium coal preparation or ultrasonic coal preparation technology without introducing magnetic foreign matters is adopted.

[0024] The equipment for fine coal pulverization includes Raymond mill, ball mill, vibration mill, hanging roller mill and mechanical mill. Preferably, Raymond mill or mechanical mill is adopted.

[0025] Among them, the component separation technology includes triboelectrostatic separation technology, solvent extraction, and high-gravity density flotation. Preferably, the component separation technology uses solvent extraction. Among them, the friction materials for triboelectrostatic separation include polyamide resin, copper, aluminum, and stainless steel. The ambient temperature is 25 - 60 °C, the ambient humidity is 25 - 85%, the feeding speed for separation is 5 - 72 kg / h, and the separation voltage is 20 - 50 kV. The solvents used for solvent extraction include one or more solvents selected from ethers, aliphatic hydrocarbons, aromatic hydrocarbons, pyridines, furans, ketones, and inorganic solvents. Among them, the ether solvents include petroleum ether, methyl ether, ethyl ether, butyl ether, isopropyl ether, and cyclopentyl ether. The aliphatic hydrocarbon solvents include pentane, octane, and n-hexane. The aromatic hydrocarbon solvents include toluene, o-xylene, m-xylene, p-xylene, naphthalene, anthracene, and pyrene. The pyridine solvents include pyridine, methylpyridine, ethylpyridine, isopropylpyridine, and azacyclopentanepyridine. The furan solvents include tetrahydrofuran, methylfuran, ethylfuran, and amylfuran. The ketone solvents include cyclohexanone, N-methylpyrrolidone, acetone, butanone, hexanone, and heterocyclic ketones containing nitrogen and sulfur heteroatoms. The inorganic solvents include carbon disulfide and carbon tetrachloride. Among them, the high-gravity density flotation method uses a centrifuge to apply high-gravity, and the density of the flotation liquid is 1.2 - 1.8 g / cm 3 .

[0026] Among them, for the main material A in step (3), D50 ≤ 10 μm and Dmax ≤ 40 μm.

[0027] Among them, the particle shape of the main material A in step (3) is spherical-like.

[0028] Preferably, for the main material A in step (3), D50 is 6 ± 2 μm and Dmax ≤ 35 μm.

[0029] Among them, for the secondary material B in step (3), D50 is 0.02 - 0.3 μm and Dmax ≤ 0.5 μm.

[0030] Among them, the particle shape of the secondary material B in step (3) is irregular.

[0031] Preferably, for the secondary material B in step (3), D50 is 0.1 ± 0.05 μm and Dmax < 0.3 μm.

[0032] After the ultra-low ash anthracite is dried, it is shaped and classified in a shaping and grading machine. Under the mechanical grinding action, the raw material is ground with the grinding disc and the material, etc., and the sharp angular structures in the material are gradually ground into obtuse angles, and after multiple grindings, a spherical-like structure is formed. After meeting the particle size and particle shape requirements, the materials with larger particle sizes enter the receiving bin of the shaping and grading machine through a cyclone separator to become the main material A; while the small particle size materials that fall from the edges or corners of the material enter the bag filter of the shaping and grading machine to become the secondary material B.

[0033] Among them, different from traditional gasification, liquefaction, etc. where the coal particle size is in the millimeter or centimeter level, in the present invention, anthracite is ground to a particle size range less than 50 μm. The vitrinite and inertinite in anthracite are effectively dissociated. Within this particle size scale, particles rich in vitrinite and particles rich in inertinite can be obtained respectively. Since the density of vitrinite is less than that of inertinite, the density of particles rich in vitrinite is correspondingly less than that of particles rich in inertinite. When the particle size is large, both types of particles can be collected by the cyclone separator of the shaping classifier and become the main material A; when the particle size is small and near the lower limit of collection by the cyclone separator of the shaping classifier, due to the small density, most of the particles rich in vitrinite will enter the bag filter behind the cyclone separator and become the secondary material B, while most of the particles rich in inertinite will be collected by the cyclone separator and become the main material A, so that the secondary material B is mainly composed of vitrinite.

[0034] After the main material A is graphitized, an anthracite-based graphite anode material will be formed. For graphite anode particles, the edge plane has higher chemical reactivity than the basal plane, and its edge plane is the main position for lithium intercalation and deintercalation. Therefore, the small particle size of the main material A provides a shorter transmission path for lithium ions, improving the fast charging characteristics of the material. Moreover, the shaped main material A has a spherical-like structure. According to the theory of close-packed stacking, it can provide a good stacking structure for the graphite anode after graphitization, thereby improving the tap density and compaction density of the material; at the same time, the ultra-small particle size of the secondary material B can, on the one hand, promote its full contact with the oxidation medium in the subsequent process; on the other hand, it is convenient to adhere to the surface of the main material A under the action of the binder, further improving the transmission rate of lithium ions.

[0035] At the same time, the oxidized secondary material B formed after the oxidation of the ultra-small particle size secondary material B has a smaller particle size than the graphitized main material A formed after the graphitization of the small particle size main material A. The ultra-small particle size oxidized secondary material B adheres to the outside of the small particle size graphitized main material A, forming a graded structure, which is more conducive to the rapid transmission of lithium ions.

[0036] Among them, the pre-carbonization of the main material A in step (4) is a gradient heating program: the heating rate from room temperature to 400 °C is 5 - 20 °C / min; the heating rate from 400 °C to 700 °C is 1 - 3 °C / min; the heating rate from 700 °C to the pre-carbonization temperature is 5 - 20 °C / min.

[0037] Preferably, the pre-carbonization of the main material A in step (4) is a gradient heating program: the heating rate from room temperature to 400 °C is 15 - 20 °C / min; the heating rate from 400 °C to 700 °C is 1 - 1.5 °C / min; the heating rate from 700 °C to the pre-carbonization temperature is 15 °C / min.

[0038] Among them, the protective gas for the pre-carbonization of the main material A in step (4) is nitrogen or argon.

[0039] The main material A is pre-carbonized by gradient heating. In the range of 400-700 °C, low-speed heating is adopted to enable the volatiles in the anthracite to escape fully, improve the density of anthracite-based graphite. At the same time, in the carbonization process with a low heating rate and low gas flow rate, the volatiles can be deposited and decomposed on the surface of the hot pre-carbonized material to generate fixed carbon, thereby closing the pores generated during the pre-carbonization of anthracite, avoiding the formation of a disordered pore structure during the pre-carbonization of anthracite, resulting in an excessively high specific surface area of anthracite-based graphite and causing the problem of too low initial efficiency.

[0040] Among them, the oxidation treatment of the secondary material B in step (4) is carried out in hot air at 200-400 °C, and the oxygen content of the oxidized secondary material B obtained is 4-10 wt%, and the specific surface area is 10-100 m 2 / g.

[0041] Among them, in step (5), the mass ratio of the graphitized main material A to the oxidized secondary material B is 1:0.05-0.25; the particle size of the binder is D50≤5 μm, and its mass is 0.5-3 wt% of the sum of the masses of the graphitized main material A and the oxidized secondary material B.

[0042] Preferably, in step (5), the mass ratio of the graphitized main material A to the oxidized secondary material B is 1:0.05-0.15.

[0043] Among them, in step (5), the heating and fusion temperature ≤ the softening point of the binder + 100 °C; the binder is one of petroleum pitch, coal pitch, petroleum coke or polymer materials; the polymer material is one of polyacrylonitrile, polyamide and polyphenylene sulfide.

[0044] The beneficial effects of the present invention are:

[0045] (1) First, the components of the anthracite are separated, and at the same time, the dual effects of reducing ash content and microscopic component separation are achieved, solving the problems such as poor material performance stability caused by high ash content of anthracite and easy spraying furnace during graphitization.

[0046] (2) The present invention forms different structures by controlling different components and their contents in anthracite: by utilizing the density and hardness differences between vitrinite and inertinite, it conducts classification treatment to fully enrich vitrinite in the secondary material B with small particle size, and its content is ≥ 96 wt%. Then, it conducts hot air oxidation treatment on it. Through this oxidation treatment, cross-linking reaction occurs in the secondary material B rich in vitrinite, promoting the formation of a quasi-hard carbon structure during the high-temperature carbonization process. At the same time, a mixed material containing 50 - 70 wt% of vitrinite and 30 - 40 wt% of inertinite is used as the main material A, which can realize the regulation of the graphitization degree of the material during the graphitization process and form a graphite structure.

[0047] (3) By regulating the macerals of anthracite, heating and fusing the graphitization main material A and the oxidized secondary material B with a binder and carbonizing them, a graphite / quasi-hard carbon hybrid structure is formed, endowing it with excellent electrochemical performance, achieving a high initial efficiency, and improving the tap density and rate performance.

[0048] (4) The particles with a graphite structure formed after the graphitization of the main material A inside have a small particle size, which can shorten the lithium ion migration path, while the particles with a quasi-hard carbon structure formed after the oxidation of the secondary material B outside have an even smaller particle size, providing rich channels for lithium ions to quickly enter the interior of the negative electrode body phase, forming a grading structure and improving the rate performance.

[0049] (5) In the present invention, both graphite and quasi-hard carbon structures are generated from anthracite without other doping substances, effectively realizing the high-yield and high-value utilization of anthracite. The obtained anthracite-based fast-charging carbon negative electrode material has good rate performance and can improve the fast-charging performance of lithium-ion batteries. Description of the Drawings

[0050] Figure 1 It is a scanning electron microscope picture of the anthracite-based fast-charging carbon negative electrode material prepared in Example 1.

[0051] Figure 2 It is a scanning electron microscope picture of the anthracite-based graphite prepared in Comparative Example 2.

[0052] Figure 3 It is a rate performance graph of the anthracite-based fast-charging carbon negative electrode material prepared in Example 3.

[0053] Figure 4 It is an XRD comparison graph of the anthracite-based fast-charging carbon negative electrode materials prepared in Example 3 and Comparative Example 1. Detailed Embodiments

[0054] The embodiments of the present application will be described in more detail below. The application can be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein, but rather these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0055] Embodiment 1:

[0056] (1) using a hammer crusher to crush anthracite to 6 mm, and then using ultrasonic coal separation to reduce the ash content to 8 wt %, to obtain clean coal, the fixed carbon content of which is 85 wt % after industrial analysis;

[0057] (2) crushing the clean coal into 300 meshes using a ball mill, and using triboelectric separation technology, using copper as the friction medium, the ambient temperature is 25° C., the humidity is 70%, the separation feed rate is 72 kg / h, and the separation voltage is 20 kV to separate the components, and after separation, ultra-low ash anthracite with a vitrinite content of 70 wt% and an ash content of 0.5 wt% is obtained;

[0058] (3) After drying the ultra-low ash anthracite, the anthracite is shaped and classified. The main material A collected in the classifier receiving bin after classification is a mixture containing 70 wt% of vitrinite and 30 wt% of inertinite, with a D50 of 10 μm and a Dmax of 35 μm; the by-material B collected in the dust collector of the classifier is a material containing 96 wt% of vitrinite, with a D50 of 0.1 μm and a Dmax of 0.3 μm;

[0059] (4) The main material A is pre-carbonized in a nitrogen atmosphere at a pre-carbonization temperature of 800°C, wherein the pre-carbonization gradient temperature program is: a heating rate of 20°C / min from room temperature to 400°C, a heating rate of 1.5°C / min from 400°C to 700°C, and a heating rate of 20°C / min from 700°C to 800°C; then, the main material A is graphitized in a graphitization furnace at 2800°C to obtain a graphitized main material A; and the by-material B is oxidized in a fluidized bed in hot air at 200°C to obtain an oxidized by-material B having an oxygen content of 6wt% and a specific surface area of ​​45m 2 / g;

[0060] (5) Petroleum asphalt with a softening point of 80°C is crushed to a particle size D50 of 3 μm, and then added into a heatable mechanical fusion machine according to 1wt% of the sum of the mass of the graphitized main material A and the oxidized by-material B, and fully mixed with the graphitized main material A and the oxidized by-material B, wherein the mass ratio of the graphitized main material A to the oxidized by-material B is 1:0.05, and then fused for 0.5h, and finally subjected to a final carbonization treatment at 1500°C for 2h to obtain an anthracite-based fast-charging carbon negative electrode material.

[0061] Embodiment 2:

[0062] (1) using a jaw crusher to crush anthracite to 13 mm, and then using heavy medium coal to reduce the ash content to 10 wt% to obtain clean coal, the fixed carbon content of which is 82 wt% after industrial analysis;

[0063] (2) crushing the clean coal to 200 meshes using a suspended roller mill, and using solvent extraction technology to prepare a mixed extraction solvent with petroleum ether and CS2 in a volume ratio of 1:1 for component sorting, and obtaining an ultra-low ash anthracite with a vitrinite content of 80wt% and an ash content of 0.8wt% after sorting;

[0064] (3) After drying the ultra-low ash anthracite, the anthracite is shaped and classified. The main material A collected in the classifier receiving bin after classification is a mixture containing 60 wt% of vitrinite and 30 wt% of inertinite, with a D50 of 8 μm and a Dmax of 25 μm; the by-material B collected in the dust collector of the classifier is a material containing 98 wt% of vitrinite, with a D50 of 0.02 μm and a Dmax of 0.1 μm;

[0065] (4) The main material A is pre-carbonized in a nitrogen atmosphere at a pre-carbonization temperature of 900°C, wherein the pre-carbonization gradient temperature program is: a temperature rise rate of 15°C / min from room temperature to 400°C, a temperature rise rate of 3°C / min from 400°C to 700°C, and a temperature rise rate of 10°C / min from 700°C to 900°C; then, the main material A is graphitized in a graphitization furnace at 3000°C to obtain a graphitized main material A; and the by-material B is oxidized in a fixed bed at 350°C hot air to obtain an oxidized by-material B having an oxygen content of 8wt% and a specific surface area of ​​100m 2 / g;

[0066] (5) Polyphenylene sulfide with a softening point of 240°C was crushed to a particle size D50 of 5 μm, and then added into a heatable mechanical fusion machine according to 3 wt% of the sum of the mass of the graphitized main material A and the oxidized by-material B, and fully mixed with the graphitized main material A and the oxidized by-material B, wherein the mass ratio of the graphitized main material A to the oxidized by-material B was 1:0.15, and then fused for 1 hour, and finally subjected to a final carbonization treatment at 1200°C for 2 hours to obtain an anthracite-based fast-charging carbon negative electrode material.

[0067] Embodiment 3:

[0068] (1) No. 3 anthracite is crushed to 7 mm using an impact crusher, and then the ash content is reduced to 5 wt% by heavy medium coal separation to obtain clean coal, and the fixed carbon content thereof is 89 wt% after industrial analysis;

[0069] (2) The clean coal was crushed to 400 mesh using a suspended roller mill, and the ultra-gravity density flotation technology was used. The centrifuge was used to apply ultra-gravity, and the density of the flotation liquid was 1.2 g / cm 3 After multiple flotation, an ultra-low ash anthracite with a vitrinite content of 78 wt% and an ash content of 1.8 wt% was obtained;

[0070] (3) After drying the ultra-low ash anthracite, it is shaped and classified. After classification, the main material A collected in the classifier receiving bin is a mixture containing 50 wt% of vitrinite and 40 wt% of inertinite, and its D50 is 6 μm and Dmax is 15 μm; the by-material B collected in the classifier dust collector is a material containing 97 wt% of vitrinite, and its D50 is 0.15 μm and Dmax is 0.2 μm;

[0071] (4) The main material A is pre-carbonized in an argon atmosphere at a pre-carbonization temperature of 1000°C, wherein the pre-carbonization gradient temperature increase program is: a temperature increase rate of 5°C / min from room temperature to 400°C, a temperature increase rate of 1°C / min from 400°C to 700°C, and a temperature increase rate of 5°C / min from 700°C to 1000°C; then, the main material A is graphitized in a 3200°C graphitization furnace to obtain a graphitized main material A; the by-material B is simultaneously dried and oxidized in a thin-layer oxidation fixed bed furnace and in hot air at 400°C, and the oxygen content of the oxidized by-material B obtained is 10wt%, and the specific surface area is 10m 2 / g;

[0072] (5) The binder coal tar with a softening point of 200°C is crushed to a particle size D50 of 2 μm, and then added into a heatable mechanical fusion machine according to 0.5 wt% of the sum of the mass of the graphitized main material A and the oxidized by-material B, and fully mixed with the graphitized main material A and the oxidized by-material B, wherein the mass ratio of the graphitized main material A to the oxidized by-material B is 1:0.20, and then subjected to mechanical fusion treatment for 2 hours, and finally subjected to a final carbonization treatment at 1200°C for 2 hours to obtain an anthracite-based fast-charging carbon negative electrode material.

[0073] Embodiment 4:

[0074] (1) using a drum crusher to crush anthracite to 10 mm, and then reducing the ash content to 6 wt% by jigging to obtain clean coal, the fixed carbon content of which is 87 wt% after industrial analysis;

[0075] (2) The clean coal was crushed into 250 meshes by a ball mill, and the components were separated by triboelectric separation technology, with PA as the friction medium, the ambient temperature being 60° C., the humidity being 25%, the separation feed rate being 5 kg / h, and the separation voltage being 50 kV, to obtain ultra-low ash anthracite with a vitrinite content of 80 wt% and an ash content of 0.6 wt%;

[0076] (3) After drying the ultra-low ash anthracite, it is shaped and classified. The main material A collected in the classifier receiving bin after classification is a mixed material containing 65wt% of vitrinite and 34wt% of inertinite, and its D50 is 4μm and Dmax is 12μm; the by-material B collected in the classifier dust collector is a material containing 98wt% of vitrinite, and its D50 is 0.3μm and Dmax is 0.5μm;

[0077] (4) The main material A is pre-carbonized in an argon atmosphere at a pre-carbonization temperature of 1000°C, wherein the pre-carbonization gradient temperature increase program is: the temperature increase rate from room temperature to 400°C is 10°C / min, the temperature increase rate from 400 to 700°C is 2.5°C / min, and the temperature increase rate from 700 to 1000°C is 15°C / min; then, the main material A is graphitized in a graphitization furnace at 3100°C to obtain the graphitized main material A; the by-material B is simultaneously dried and oxidized in a thin-layer oxidation fixed bed furnace and hot air at 380°C, and the oxygen content of the oxidized by-material B obtained is 9wt%, and the specific surface area is 84m 2 / g;

[0078] (5) The binder polyamide with a softening point of 140°C is crushed to a particle size D50 of 2.5 μm, and then added into a heatable mechanical fusion machine according to 3.0 wt% of the sum of the mass of the graphitized main material A and the oxidized by-material B, and fully mixed with the graphitized main material A and the oxidized by-material B, wherein the mass ratio of the graphitized main material A to the oxidized by-material B is 1:2, and then subjected to mechanical fusion treatment for 2 hours, and finally subjected to a final carbonization treatment at 1400°C for 2 hours to obtain an anthracite-based fast-charging carbon negative electrode material.

[0079] Embodiment 5:

[0080] (1) using a cone crusher to crush No. 3 anthracite with a sulfur content of 1.0 wt% and a carbon content of 88 wt% to 9 mm, and then reducing the ash content to 6 wt% by ultrasonic coal separation to obtain clean coal;

[0081] (2) The clean coal is crushed into 500 meshes by a mechanical mill, and the components are separated by a triboelectric separation technology, with polyamide resin as the friction medium, an ambient temperature of 30° C., a humidity of 30%, a separation feed rate of 20 kg / h, and a separation voltage of 45 kV, to obtain an ultra-low ash anthracite with a vitrinite content of 75 wt% and an ash content of 1.0 wt%;

[0082] (3) After drying the ultra-low ash anthracite, it is shaped and classified. After classification, the main material A collected in the classifier receiving bin is a mixture containing 55wt% of vitrinite and 40wt% of inertinite, and its D50 is 5μm and Dmax is 10μm; the by-material B collected in the classifier dust collector is a material containing 98wt% of vitrinite, and its D50 is 0.09μm and Dmax is 0.2μm;

[0083] (4) The main material A is pre-carbonized in a nitrogen atmosphere at a pre-carbonization temperature of 950°C, wherein the pre-carbonization gradient temperature program is: room temperature to 400°C at a heating rate of 10°C / min; 400 to 700°C at a heating rate of 2°C / min; 700 to 950°C at a heating rate of 20°C / min; then graphitized in a graphitization furnace at 2900°C to obtain a graphitized main material A; the by-material B is simultaneously dried and oxidized in a static oxidation furnace and hot air at 400°C, and the oxygen content of the oxidized by-material B obtained is 4wt%, and the specific surface area is 38m 2 / g;

[0084] (5) The binder petroleum asphalt with a softening point of 80°C is crushed to a particle size D50 of 3 μm, and then added into a heatable mechanical fusion machine according to 1wt% of the sum of the mass of the graphitized main material A and the oxidized by-material B, and fully mixed with the graphitized main material A and the oxidized by-material B, wherein the mass ratio of the graphitized main material A to the oxidized by-material B is 1:0.05, and then subjected to mechanical fusion treatment for 0.5h, and finally subjected to a final carbonization treatment at 1500°C for 2h to obtain an anthracite-based fast-charging carbon negative electrode material.

[0085] Embodiment 6:

[0086] (1) using a hammer crusher to crush anthracite to 9 mm, and then using ultrasonic coal separation to reduce the ash content to 6 wt% to obtain clean coal, the fixed carbon content of which is 92 wt% after industrial analysis;

[0087] (2) The clean coal was crushed to 400 mesh using a mechanical mill, and gravity density flotation technology was used to prepare zinc chloride with a density of 1.8 g / cm 3 The density liquid is used to separate the coal components, and after separation, an ultra-low ash anthracite with a vitrinite content of 78wt% and an ash content of 2.0wt% is obtained;

[0088] (3) After drying the ultra-low ash anthracite, it is shaped and classified. After classification, the main material A collected in the classifier receiving bin is a mixed material containing 60wt% of vitrinite and 35wt% of inertinite, and its D50 is 10μm and Dmax is 40μm; the by-material B collected in the classifier dust collector is a material containing 97wt% of vitrinite, and its D50 is 0.2μm and Dmax is 0.5μm;

[0089] (4) The main material A is pre-carbonized in an argon atmosphere at a pre-carbonization temperature of 1000°C, wherein the pre-carbonization gradient temperature increase program is: the temperature increase rate from room temperature to 400°C is 15°C / min, the temperature increase rate from 400°C to 700°C is 2.5°C / min, and the temperature increase rate from 700°C to 1000°C is 15°C / min; then, the main material A is graphitized in a 3200°C graphitization furnace to obtain the graphitized main material A; the by-material B is simultaneously dried and oxidized in a thin-layer oxidation fixed bed furnace and hot air at 350°C, and the oxygen content of the oxidized by-material B obtained is 7wt%, and the specific surface area is 65m 2 / g;

[0090] (5) The binder petroleum asphalt with a softening point of 250°C is crushed to a particle size D50 of 2 μm, and then added into a heatable mechanical fusion machine according to 3 wt% of the sum of the mass of the graphitized main material A and the oxidized by-material B, and fully mixed with the graphitized main material A and the oxidized by-material B, wherein the mass ratio of the graphitized main material A to the oxidized by-material B is 1:0.25, and then subjected to mechanical fusion treatment for 2 hours, and finally subjected to a final carbonization treatment at 1500°C for 2 hours to obtain an anthracite-based fast-charging carbon negative electrode material.

[0091] Comparative Example 1: The vitrinite content of the clean coal is not controlled to be 70-80wt%, and the vitrinite content of the main material B is less than 96wt%:

[0092] (1) using a jaw crusher to crush anthracite to 6 mm, and then using ultrasonic coal separation to reduce the ash content to 9 wt% to obtain clean coal, the fixed carbon content of which is 87 wt% after industrial analysis;

[0093] (2) crushing the clean coal to 300 mesh using a ball mill, and reducing its ash content to 0.5 wt% using chemical means to obtain ultra-low ash anthracite;

[0094] (3) After drying the ultra-low ash anthracite, the anthracite is shaped and classified. The main material A collected in the classifier receiving bin after classification is a mixture containing 80 wt% of vitrinite and 15 wt% of inertinite, with a D50 of 7 μm and a Dmax of 20 μm; the by-material B collected in the dust collector of the classifier is a material containing 80 wt% of vitrinite, with a D50 of 0.2 μm and a Dmax of 0.5 μm;

[0095] (4) The main material A is pre-carbonized in an argon atmosphere at a pre-carbonization temperature of 1000°C, wherein the pre-carbonization gradient temperature increase program is: the temperature increase rate from room temperature to 400°C is 10°C / min, the temperature increase rate from 400 to 700°C is 3°C / min, and the temperature increase rate from 700 to 1000°C is 20°C / min; then, the main material A is graphitized in a graphitization furnace at 2800°C to obtain the graphitized main material A; the by-material B is simultaneously dried and oxidized in a fluidized bed and hot air at 300°C, and the oxygen content of the oxidized by-material B obtained is 4wt%, and the specific surface area is 91m 2 / g;

[0096] (5) The binder petroleum asphalt with a softening point of 220°C is crushed to a particle size D50 of 2 μm, and then added into a heatable mechanical fusion machine according to 3 wt% of the sum of the mass of the graphitized main material A and the oxidized by-material B, and fully mixed with the graphitized main material A and the oxidized by-material B, wherein the mass ratio of the graphitized main material A to the oxidized by-material B is 1:0.15, and then subjected to mechanical fusion treatment for 2 hours, and finally subjected to a final carbonization treatment at 1400°C for 2 hours to obtain an anthracite-based fast-charging carbon negative electrode material.

[0097] Comparative Example 2: Only using the main material A to obtain graphitized material:

[0098] (1) using a cone crusher to crush anthracite to 12 mm, and then reducing the ash content to 8 wt% by ultrasonic coal separation;

[0099] (2) crushing the clean coal to 200 meshes using a ball mill, and reducing the ash to 2 wt% using a chemical method to obtain ultra-low ash anthracite;

[0100] (3) After drying the ultra-low ash anthracite, it is shaped and classified. The main material A collected in the classifier receiving bin after classification is a mixed material containing 70wt% of vitrinite and 25wt% of inertinite, with a D50 of 8μm and a Dmax of 24μm; the by-material B collected in the dust collector of the classifier is directly treated as solid waste;

[0101] (4) The main material A is pre-carbonized in an argon atmosphere at a pre-carbonization temperature of 1000°C, wherein the pre-carbonization gradient temperature increase program is: room temperature to 400°C at a heating rate of 12°C / min, 400 to 700°C at a heating rate of 2°C / min, and 700 to 1000°C at a heating rate of 12°C / min; and then graphitized in a graphitization furnace at 3000°C to obtain an anthracite-based graphite material.

[0102] Among them, the oxidized by-product B in the examples and comparative examples of the present invention is all prepared from the by-product B obtained in the same preparation, or from the by-product B obtained in the same preparation mixed with the by-product B obtained in other batches.

[0103] As Figure 1 and Figure 2 shown, the anthracite-based fast-charging carbon anode material prepared by the method of the present invention obviously has a smaller particle size, which is more conducive to electron conductivity. From Figure 4 it can be seen that the characteristic diffraction peak intensity of the anthracite-based fast-charging carbon anode material prepared by the method of the present invention in Example 3 is greater than that of the anthracite-based fast-charging carbon anode material prepared in Comparative Example 1 without controlling the vitrinite content of the clean coal and the vitrinite content of the main material B, indicating that the graphitization degree of the anthracite-based fast-charging carbon anode material obtained in Example 3 is higher.

[0104] Table 1 shows the performance test data of the final obtained materials in Examples 1-6 and Comparative Examples 1-2. Among them, the specific capacity and the first efficiency are tested by the coin-type half-cell test method. Specifically: Mix the coal-based graphite material, conductive carbon black, carboxymethyl cellulose CMC and styrene-butadiene rubber SBR binder with a mass ratio of 91:2:2:5 in a mortar and mix evenly, coat it on a copper foil, and put the coated electrode sheet into a vacuum drying oven at 110°C for 24 hours of vacuum drying for standby. The coin-type half-cell is assembled in a German Braun glove box filled with argon. The electrolyte is a 1M-LiPF6 EC / DMC / DEC solution with a volume ratio of 1:1:1. The metal lithium sheet is used as the counter electrode, and a polypropylene membrane PP Celgard 2400 is selected as the separator. The electrochemical performance test is carried out on a Blue Electric Tester, and the charge-discharge voltage range is 0.005 to 2.0V, and the charge-discharge rate is 0.1C. Among them, the ratio of the constant current charging capacity is tested by the full-cell test method: Using the coal-based graphite anode material as the negative electrode and the ternary NCM811 as the positive electrode, a 1M-LiPF6 EC:DMC:EMC solution with a volume ratio of 1:1:1 is used as the electrolyte to assemble a soft-pack full cell, and the constant current charging capacities corresponding to 0.2C and 5C are respectively tested.

[0105] It can be seen from Table 1 that the anthracite-based fast-charging carbon anode material obtained in Comparative Example 2 has better specific capacity, first Coulomb efficiency and rate performance than the graphitized material obtained in Comparative Example 1, indicating that the anthracite-based fast-charging carbon anode material obtained from the graphitized main material A and the oxidized by-product B has better performance; however, Comparative Example 2 did not strictly control the vitrinite content of the oxidized by-product B ≥ 96wt%, while the anthracite-based fast-charging carbon anode materials prepared by Examples 1-6 using the present invention have better performance than Comparative Example 2, and their specific capacity, first Coulomb efficiency and rate performance have all increased significantly, and the D50 is all less than 20μm, and the tap density is all greater than 1.00g / cm 3, with a smaller particle size and better tap density, indicating that the anthracite-based fast-charging carbon anode material with a graphite / hard carbon-like structure obtained by controlling the microscopic components of the present invention has more excellent performance, achieving a high first-cycle efficiency and good rate performance.

[0106] Table 1 Performance test data of the finally obtained materials in Examples 1-6 and Comparative Examples 1-2

[0107]

[0108] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claimed rights.

Claims

1. A bituminous coal-based fast-charging carbon negative electrode material, characterized in that: The bituminous coal-based fast-charging carbon negative electrode material is a material with a graphite / hard carbon-like composite structure: the inner part is a material with a graphite structure, and the material with the graphite structure is formed by graphitizing bituminous coal containing 50-70 wt% of vitrinite and 30-40 wt% of inertinite; The outer part is a hard carbon-like structure material, and the hard carbon-like structure material is formed by oxidizing bituminous coal containing ≥96 wt% of vitrinite.

2. The anthracite-based fast-charging carbon anode material according to claim 1, characterized in that: The material with the graphite structure is formed by graphitizing bituminous coal containing 65 wt% of vitrinite and 34 wt% of inertinite.

3. The anthracite-based fast-charging carbon negative electrode material according to claim 1, wherein: The material with the graphite structure is formed by graphitizing bituminous coal containing 60 wt% of vitrinite and 30 wt% of inertinite.

4. A preparation method of a bituminous coal-based fast-charging carbon negative electrode material, characterized in that, It includes the following steps: (1) Crush bituminous coal and reduce its ash content to 5-10 wt% through coal preparation technology to obtain clean coal; (2) Grind the clean coal to 200-500 mesh, adopt component separation technology to increase its vitrinite content to 70-80 wt%, and at the same time reduce its ash content to 0.5-2 wt% to obtain ultra-low ash bituminous coal; (3) After drying the ultra-low ash bituminous coal, carry out shaping and classification. The main material A collected in the main material bin of the classifier after classification is a mixed material containing 50-70 wt% of vitrinite and 30-40 wt% of inertinite, and the secondary material B collected in the dust collector of the classifier is a material containing ≥96 wt% of vitrinite; (4) Carry out pre-carbonization of the main material A under a protective gas, the pre-carbonization temperature is 800-1000 °C, and then carry out graphitization treatment in a graphitization furnace at 2800-3200 °C to obtain graphitized main material A; at the same time, carry out oxidation treatment of the secondary material B in hot air to obtain oxidized secondary material B; (5) Mix the graphitized main material A, the oxidized secondary material B and the binder evenly, then carry out heating and fusion for 0.5-2 h, and finally carry out final carbonization treatment at a constant temperature of 1200-1500 °C for 0.5-2 h to obtain the bituminous coal-based fast-charging carbon negative electrode material.

5. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to claim 4, characterized in that, The fixed carbon content in the bituminous coal is ≥80 wt%.

6. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to claim 4, characterized in that, The bituminous coal in step (1) is crushed to 6-13 mm.

7. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to claim 4, characterized in that, The D50 of the main material A in step (3) is ≤10 μm, and Dmax is ≤40 μm.

8. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to any one of claims 4 or 7, characterized in that The particle shape of the main material A in step (3) is quasi-spherical.

9. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to claim 4, characterized in that, The D50 of the secondary material B in step (3) is 0.02-0.3 μm, and Dmax is ≤0.5 μm.

10. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to any one of claims 4 or 9, characterized in that The particle shape of the secondary material B in step (3) is irregular.

11. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to claim 4, characterized in that, The pre-carbonization of the main material A in step (4) is a gradient heating program: the heating rate from room temperature to 400 °C is 5-20 °C / min; the heating rate from 400-700 °C is 1-3 °C / min; the heating rate from 700 °C to the pre-carbonization temperature is 5-20 °C / min.

12. The preparation method of an anthracite-based fast-charging carbon anode material according to any one of claims 4 or 11, characterized in that, The protective gas for the pre-carbonization of the main material A in step (4) is nitrogen or argon.

13. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to claim 4, characterized in that, In step (4), the oxidation treatment of secondary material B in hot air is carried out in hot air at 200-400 °C, and the oxygen content of the oxidized secondary material B obtained is 4-10 wt%, and the specific surface area is 10-100 m 2 / g.

14. The preparation method of an anthracite-based fast-charging carbon negative electrode material according to claim 4, characterized in that, The mass ratio of the main graphitization material A to the oxidation by-product material B in the step (5) is 1:0.05 - 0.25; the particle size of the binder is D50 ≤ 5 μm, and the mass is 0.5 - 3 wt% of the sum of the masses of the main graphitization material A and the oxidation by-product material B.

15. The preparation method of an anthracite-based fast-charging carbon anode material according to claim 4, characterized in that, The heating and fusion temperature in the step (5) ≤ the softening point of the binder + 100 °C; the binder is one of petroleum pitch, coal pitch, petroleum coke or polymer material; the polymer material is one of polyacrylonitrile, polyamide and polyphenylene sulfide.

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