CN107706387B - Composite negative electrode material, preparation method thereof and lithium ion battery - Google Patents
Composite negative electrode material, preparation method thereof and lithium ion battery Download PDFInfo
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- CN107706387B CN107706387B CN201710929220.6A CN201710929220A CN107706387B CN 107706387 B CN107706387 B CN 107706387B CN 201710929220 A CN201710929220 A CN 201710929220A CN 107706387 B CN107706387 B CN 107706387B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a composite negative electrode material, a preparation method thereof and a lithium ion battery. The composite anode material comprises a mosaic structure carbonaceous material formed by inlaying first carbon component small particles in a second carbon component frame carrier; wherein the first carbon component is converted from a small particle precursor (green coke and/or cooked coke and/or carbon microspheres) and the second carbon component framework support is converted from a binder. The composite negative electrode material has an embedded structure and a gradient crystal structure, small particles with different shapes are embedded in a thicker frame carrier to form larger particles, the small particles embedded in the frame carrier are of a graphite structure with the best crystal form, the frame carrier is of a graphite structure with a common crystal form, and the outermost layer can also be coated with an amorphous carbon structure with the worst crystal form. The composite negative electrode material has the advantages of stable structure, good orientation, low expansion, high rate performance, excellent liquid absorption performance and cycle performance, and can meet various requirements in application.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery cathode materials, and relates to a composite cathode material, a preparation method thereof and a lithium ion battery, in particular to a composite cathode material, a preparation method thereof, a cathode material prepared from the composite cathode material and a lithium ion battery.
Background
As an electrochemical power system with mature technology, lithium ion batteries have been applied to various aspects of people's daily life, but their performance still cannot meet various requirements in application. The lithium ion battery cathode material which is most widely applied and has the best performance belongs to graphite materials, and has a good layered structure, a stable discharge platform, small volume change in the lithium desorption process and no voltage hysteresis. However, from another perspective, the graphite-based negative electrode material has an upper limit value of capacity, which is difficult to break through; poor compatibility with electrolyte, resulting in poor battery cycling stability; and the large-current charging and discharging performance is poor, and the multiplying power performance needs to be improved. Therefore, research and development personnel have conducted decades of modification researches on graphite as a negative electrode material of a lithium ion battery, and successful modification methods such as oxidation or halogenation on the surface of a graphite matrix, coating of amorphous carbon, metal and oxides thereof, polymers and the like on the surface, or doping of metal or nonmetal elements can achieve the purpose of improving the comprehensive performance of the graphite negative electrode by simultaneously modifying the composition and the surface state of the graphite matrix.
The difference of the rate charge and discharge of the lithium ion battery depends on the diffusion rate of lithium ions in the material and the conduction speed of electrons. For graphite materials, the conductivity of the graphite materials is good, and the conduction rates of electrons are basically in the same order of magnitude; however, the conduction rates of lithium ions are very different and are mainly influenced by the size, particle size distribution, orientation, surface state, and other factors. For example, the lithium ion diffusion path is greatly shortened due to smaller particles and more concentrated particle size distribution, the concentration polarization of lithium ions is reduced, and the rapid charging and discharging and the cycling stability of the battery are facilitated; for example, the existence of amorphous carbon on the surface of the particles can effectively adsorb electrolyte, and is more beneficial to the diffusion of lithium ions, especially the charging performance at low temperature; therefore, selecting a proper process to control the composition and structure of the material and obtain the improvement of the comprehensive performance of the cathode material is a technical problem to be solved in the field.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a composite negative electrode material, a preparation method thereof, a negative electrode material prepared from the composite negative electrode material and a lithium ion battery. The composite negative electrode material has the advantages of stable structure, good orientation, low expansion, high rate performance, excellent liquid absorption performance and cycle performance.
In order to realize the purpose of the invention, the following technical scheme is adopted:
in a first aspect, the present invention provides a composite anode material comprising a mosaic structure carbonaceous material formed by mosaic of first carbon component small particles in a second carbon component frame carrier;
wherein the first carbon component small particles are converted from small particle precursors, and the small particle precursors are green coke and/or cooked coke and/or carbon microspheres, namely the combination of any 1 or at least 2 of the green coke, the cooked coke or the carbon microspheres; the second carbon component framework support is converted from a binder.
In the composite negative electrode material of the present invention, the "combination of at least 2 of green coke, cooked coke, or carbon microspheres" includes, for example: combinations of green coke and cooked coke, combinations of cooked coke and carbon microspheres, combinations of green coke, cooked coke and carbon microspheres, and the like.
In the composite negative electrode material, the graphite crystal structures of the first carbon component small particles and the second carbon component frame carrier are sequentially poor.
The composite negative electrode material provided by the invention has an embedded structure and a gradient crystal structure, wherein the embedded structure refers to that: the small particles (namely, the first carbon component small particles) with different morphologies are embedded in the thicker frame carrier (namely, the second carbon component frame carrier) to form a larger particle (namely, the embedded structure carbonaceous material) stable and uniform composite system, and the material structure of the composite system is different from a core-shell structure formed by surface coating of the traditional cathode material. The structure of the gradient crystal form refers to that: the small particles (i.e. the small particles of the first carbon component) embedded inside are of the best crystal form graphite structure, and the framework carrier (i.e. the framework carrier of the second carbon component) is of the general crystal form graphite structure. It can be seen that the graphite crystal structures of the first carbon component small particles and the second carbon component framework support are sequentially deteriorated.
As a preferable technical scheme of the composite anode material, the composite anode material further comprises an amorphous carbon coating layer coated on the outermost layer of the mosaic structure carbonaceous material.
In this preferred technical scheme, the graphite crystal structures of the first carbon component small particles, the second carbon component framework carrier and the amorphous carbon coating layer are deteriorated in sequence.
In this preferred technical scheme, the composite negative electrode material (which includes a carbonaceous material with an inlaid structure and an amorphous carbon coating layer coated on the outer layer of the carbonaceous material with the inlaid structure) has both an "inlaid" structure and a "gradient crystal form" structure, and a structural schematic diagram of the composite negative electrode material with an amorphous carbon coating layer on the surface is shown in fig. 1. The embedded structure is as follows: small particles of different morphologies (i.e., small particles of the first carbon component) are embedded within the thicker frame support (i.e., the second carbon component frame support) to form one larger particle (i.e., the mosaic structure carbonaceous material). The structure of the gradient crystal form refers to that: the small particles (i.e., the first carbon component small particles) embedded inside are of the best crystal form graphite structure, the framework support (i.e., the second carbon component framework support) is of the general crystal form graphite structure, and the outermost carbon coating layer is of the worst amorphous carbon structure, so that it is known that the graphite crystal form structures of the first carbon component small particles, the second carbon component framework support and the amorphous carbon coating layer are sequentially deteriorated.
Preferably, the small particles of the first carbon component have different morphologies, e.g., the first carbon component is composed of small particles having different morphologies such as spheroidal, elongated, and plate-like shapes.
Preferably, the small particles of the first carbon component have a particle size of 1 μm to 10 μm, for example, 1 μm, 2 μm, 3 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or the like.
In the composite negative electrode material, the first carbon component small-particle graphite with different appearances is inlaid in the carbon material serving as the frame carrier to form a larger inlaid structure carbon material, and the small-particle graphite has different appearances and different orientations, so that isotropization is shown macroscopically, and the direction selectivity of the small-particle graphite is eliminated in the lithium ion transfer process; the small-particle graphite has small particle size, so that the diffusion path of lithium ions is greatly shortened, and the electrochemical performance of the lithium ion battery prepared by the small-particle graphite is improved; meanwhile, the crystallinity of the graphite material used as the frame carrier is general, and the amorphous carbon with the worst crystallinity at the outermost layer shows larger graphite interlayer spacing and more defect vacancies, so that the charge-discharge rate performance of the battery is greatly improved by the characteristics, and the battery is more favorable for quick charge. Because the frame carrier is a graphitized derivative of a large amount of adhesive, the small particles are firmly wrapped together, the structural stability is good, the expansion of a pole piece is low in the charge and discharge process of the battery, and the represented cycling stability is very good. And because the raw coke and/or the cooked coke and/or the carbon microsphere precursor are used as raw materials, some organic gases are volatilized in the graphitized crystal forming process, so that a microporous structure is left in the composite material, and the liquid absorption performance of the composite material is improved.
Preferably, the composite anode material has an average particle size D50 of 5 to 30 μm, for example 5, 10, 12, 15, 18, 20, 25, or 30 μm.
Preferably, the sphericity S50 of the composite negative electrode material is 0.8-0.9, such as 0.8, 0.82, 0.85, 0.88, 0.89, or 0.9.
Preferably, the dispersion of the particle size distribution of the composite anode material is 0.5-2.0, such as 0.5, 0.6, 0.8, 0.9, 1.0, 1.3, 1.5, 1.7 or 2.0. If the dispersion of the particle size distribution is more than 2.0, the powder contains a large amount of micro powder and large particles, the powder is settled during the manufacture of the pole piece, the qualified rate of the battery manufacture is low, the material capacity is low, the first effect is low, and the multiplying power charging and the cycle performance of the battery are poor.
Preferably, the specific surface area of the composite anode material is 2m2/g～20m2In g, e.g. 2m2/g、5m2/g、7.5m2/g、10m2/g、12m2/g、13m2/g、15m2/g、17m2/g、18m2G or 20m2And/g, etc.
Preferably, the mass percentage content of the first carbon component small particles is 60% to 90%, for example, 60%, 63%, 65%, 67%, 70%, 75%, 78%, 80%, 82%, 84%, 85%, 88%, or 90% or the like, based on 100% of the total mass of the composite anode material.
Preferably, the second carbon component frame support is present in an amount of 10 to 30% by mass, for example 10%, 12%, 15%, 17.5%, 20%, 22%, 24%, 26%, 28%, 38%, etc., based on 100% by mass of the composite anode material.
Preferably, the amorphous carbon coating layer is contained in an amount of 0.5% to 10% by mass, for example, 0.5%, 1%, 2%, 2.5%, 3%, 4%, 5%, 6.5%, 7%, 8%, 10%, or the like, based on 100% by mass of the composite anode material.
Preferably, the amorphous carbon coating has a thickness of 10nm to 1000nm, for example 10nm, 50nm, 80nm, 100nm, 150nm, 200nm, 220nm, 240nm, 270nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 800nm, 850nm, 950nm, 1000nm, or the like.
In a second aspect, the present invention provides a method for preparing a composite anode material according to the first aspect, the method comprising the steps of:
(1) simultaneously adding the small-particle precursor and the binder in a molten state into kneading equipment, and carrying out kneading treatment to obtain a kneaded material;
(2) graphitizing the kneaded material under a protective atmosphere or vacuum condition to obtain a carbonaceous material with an embedded structure, namely a composite negative electrode material;
optionally performing step (3): coating the surface of the carbon material with the mosaic structure to obtain a composite negative electrode material, wherein the composite negative electrode material comprises the carbon material with the mosaic structure and an amorphous carbon coating layer coated on the outer layer of the carbon material (namely the carbon material with the mosaic structure);
wherein, the small particle precursor is green coke and/or cooked coke and/or carbon microspheres, namely the combination of any 1 or at least 2 of the green coke, the cooked coke or the carbon microspheres.
In the method of the present invention, the "optional step (3)" means: step (3) may be performed, or step (3) may not be performed.
In the method, the high-temperature graphitization treatment in the step (2) converts small particle precursors (green coke and/or cooked coke and/or carbon microspheres) into graphite structures with the best crystal form, and the binder is converted into graphite structures with common crystal forms, and the structures of the two are recombined to form an embedded structure containing a plurality of small particle graphite materials.
As a preferable embodiment of the method of the present invention, the small particle precursor in step (1) has an average particle size of 1 μm to 10 μm, for example, 1 μm, 2 μm, 2.5 μm, 3 μm, 3.2 μm, 3.5 μm, 4.0 μm, 4.25 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 8 μm, 8.5 μm, 9 μm or 10 μm, etc., and if the particle size is smaller than 1 μm, the particle size is too small, which results in poor adhesion effect and failure to form a "mosaic" particle structure; if the particle diameter is larger than 10 μm, the particles are too large to cause the particles to collectively "agglomerate", and kneading treatment cannot be performed.
Preferably, the volatility of the small particle precursor in step (1) is 2% to 20%, for example, 2%, 5%, 8%, 10%, 15%, or 20%, and if the volatility is less than 2%, less organic components are released during graphitization, and the composite negative electrode material forms fewer micropores, which also results in poor binding effect of the small particle precursor, poor liquid absorption performance of the composite negative electrode material, influence on diffusion of lithium ions during charging and discharging, and decrease in cycle performance of the battery; if the volatile component is higher than 20%, the volatile component is too high, so that the byproducts such as smoke, oil stain and the like in the manufacturing process are too many, and the normal production is not facilitated.
Preferably, the ash content of the small particle precursor in step (1) is 0.5% or less.
Preferably, the green coke and/or the cooked coke is any 1 or at least 2 combinations of petroleum coke, pitch coke and coal coke, typical but non-limiting examples of which are: petroleum coke and pitch coke, petroleum coke and coal coke, petroleum coke, pitch coke and coal coke, and the like.
Preferably, the carbon microspheres are any 1 or 2 combination of petroleum-based mesophases or coal-based mesophases.
As a preferred embodiment of the method of the present invention, the method further comprises a step of mixing the small particle precursors before step (1), and the mixing is preferably uniform mixing.
Preferably, in the step of mixing the small particle precursor, the mixing time is 10min to 180min, such as 10min, 20min, 30min, 45min, 50min, 60min, 75min, 80min, 90min, 100min, 120min, 135min, 150min, 165min or 180 min.
Preferably, in the step of mixing the small particle precursor, the mixing is performed using any 1 of a V-type mixer, a trough type mixer, a drum mixer, a conical twin-screw mixer, or a double cone mixer.
Preferably, the binder in step (1) is any 1 or combination of at least 2 of asphalt, resin, high molecular material or polymer, preferably any 1 or combination of at least 2 of coal asphalt, petroleum asphalt, natural asphalt, mesophase asphalt, resin, high molecular material or polymer.
Preferably, in the step (1), the content of the binder in the molten state is 5 to 40% by mass, for example, 5%, 10%, 12%, 15%, 20%, 25%, 27.5%, 30%, 33%, 35%, 37%, 40%, or the like, based on 100% by mass of the total mass of the small particle precursor and the binder in the molten state. If the content is less than 5%, the used binder is too little, so that the binding and wrapping effects of the particles are poor, the particles are poor in forming, and the charging rate and the cycle performance of the material are seriously affected; if it exceeds 40%, too much binder is used, resulting in collective "agglomeration" of particles and failure to carry out kneading treatment.
Preferably, the kneading temperature in step (1) is 50 to 300 ℃, for example, 50 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 115 ℃, 130 ℃, 150 ℃, 165 ℃, 180 ℃, 200 ℃, 220 ℃, 230 ℃, 245 ℃, 260 ℃, 275 ℃, 285 ℃ or 300 ℃, etc.
Preferably, the kneading time in step (1) is 1 to 10 hours, such as 1 hour, 2 hours, 3 hours, 3.5 hours, 4 hours, 5 hours, 5.5 hours, 7 hours, 8 hours, 10 hours, and the like.
Preferably, the method further comprises a step of heating the binder before the step (1) to prepare the binder in a molten state at a temperature of 50 ℃ to 300 ℃, for example, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 120 ℃, 150 ℃, 170 ℃, 180 ℃, 200 ℃, 220 ℃, 230 ℃, 240 ℃, 260 ℃, 280 ℃, 300 ℃ or the like.
In the present invention, there is no particular limitation on the heating apparatus, and any container having a heating function is suitable for use in the present invention.
Preferably, the graphitization treatment in step (2) adopts 1 device selected from an internal cascade graphitization furnace or an Acheson graphitization furnace.
Preferably, the protective atmosphere in step (2) is any 1 or a combination of at least 2 of a helium atmosphere, a neon atmosphere, an argon atmosphere, or a nitrogen atmosphere.
Preferably, the graphitization treatment in step (2) is carried out at a temperature of 2700 ℃ to 3300 ℃, for example 2700 ℃, 2800 ℃, 2850 ℃, 2900 ℃, 2950 ℃, 3000 ℃, 3100 ℃, 3150 ℃, 3200 ℃, 3250 ℃ or 3300 ℃, etc.
Preferably, the carbon source used for surface coating in step (3) is any 1 or a combination of at least 2 of furan resin, urea resin, melamine resin, phenolic resin, epoxy resin, polyvinyl alcohol, polyethylene glycol, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, polystyrene rubber, cellulose, coke, coal pitch, petroleum pitch or natural pitch.
Preferably, the heat treatment temperature of the surface coating in the step (3) is 700 ℃ to 1300 ℃, such as 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1000 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, or 1300 ℃.
As a preferable embodiment of the method of the present invention, the method further comprises performing step (a) after the kneading treatment of step (1) and before the graphitization treatment of step (2): crushing and particle shaping.
Preferably, the method further comprises performing step (B) after the spheroidizing treatment of step (2) and before the surface coating of step (3): crushing and shaping the particles, wherein the sphericity S50 of the obtained particles is preferably 0.8-0.9, and the dispersion of the particle size distribution is preferably 0.5-2.0.
Preferably, the crushing and particle shaping in step (a) and step (B) are carried out by using 1 kind of equipment independently selected from a turbine type crusher, a gas flow vortex pulverizer, a super cyclone vortex mill, a winnowing crusher and a double-rod crusher. By using the above-described apparatus, particle reshaping can be achieved while crushing.
In the method of the invention, the required granularity can be obtained; through particle shaping, the sphericity can be improved, the particle size distribution is centralized, the particle size distribution dispersion is preferably 0.5-2.0, the content of micro powder and large particles in powder is reduced, the sedimentation phenomenon in the process of manufacturing a pole piece is relieved, the qualification rate of battery manufacturing is improved, and the battery can effectively exert high capacity, high first efficiency and excellent charge rate and cycle performance.
As a preferable technical solution of the method of the present invention, the method further includes a step of sieving the obtained composite anode material.
As a further preferred technical solution of the method of the present invention, the method comprises the steps of:
(1) mixing small-particle precursors with the average particle size of 1-10 mu m to obtain uniformly mixed small-particle precursors; heating the binder to obtain a molten binder;
simultaneously adding the uniformly mixed small-particle precursor and the binder in a molten state into kneading equipment, carrying out kneading treatment for 1-10 h at 50-300 ℃, and then carrying out crushing and particle shaping to obtain a kneaded material;
(2) graphitizing the kneaded material at 2700-3300 ℃ in a protective atmosphere to obtain a mosaic structure carbonaceous material;
(3) crushing and shaping the mosaic structure carbonaceous material, mixing the mosaic structure carbonaceous material with a carbon source, carrying out heat treatment at 700-1300 ℃ to realize surface coating, and carrying out screening treatment to obtain a composite negative electrode material with the average particle size D50 of 5-30 mu m;
wherein, the small particle precursor is any 1 or the combination of at least 2 of green coke, cooked coke or carbon microspheres.
In the preferred technical scheme, small-particle green coke and/or cooked coke and/or carbon microspheres are firstly used as raw materials to be uniformly mixed, a certain proportion of a binder in a molten state is subjected to high-temperature kneading, and then crushing and particle shaping are carried out according to the particle size requirement to obtain a kneaded material; directly carrying out high-temperature graphitization on the kneaded material, wherein in the graphitization process, small-particle green coke and/or cooked coke and/or carbon microsphere precursors are converted into graphite structures with the best crystal forms, the binder is converted into a graphite structure with a common crystal form, and the small-particle green coke and/or cooked coke and/or carbon microsphere precursors are structurally recombined to form an embedded structure containing a plurality of small-particle graphite materials; then crushing and particle shaping are carried out, and the sphericity and particle size distribution centralization are improved; and coating the surface, forming a layer of amorphous carbon structure with the worst crystal form on the outermost layer, and finally screening to obtain the composite anode material.
In a third aspect, the present invention provides a lithium ion battery, wherein the negative electrode material component of the lithium ion battery comprises the composite negative electrode material of the first aspect as a negative electrode active material. The composite negative electrode material serving as the active material has better lithium ion diffusion performance, and is more favorable for eliminating the generation of internal polarization of the battery, so that an additional conductive agent is omitted in the manufacturing process of the lithium ion battery, more active materials can be placed in a limited battery space, and the energy density of the battery is increased.
Preferably, the negative electrode material component of the lithium ion battery comprises the composite negative electrode material as a negative electrode active material, and no additional conductive agent is added, for example, only the composite negative electrode material of the first aspect as a negative electrode active material and a binding additive may be contained, and no additional conductive agent is contained; it is also possible to contain both the composite anode material according to the first aspect and the binder additive and the additional conductive agent.
In the present invention, when the "combination of at least 2" means a mixture of at least 2 substances, there is no particular limitation on the mixing ratio, and the selection of any one specific ratio falls within the scope of the present invention.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method of the invention firstly uses small-particle green coke and/or cooked coke and/or carbon microspheres as raw materials to be uniformly mixed, high-temperature kneading is carried out on a certain proportion of a binder in a molten state, then the kneaded material is directly graphitized at high temperature, during the graphitization process, the small-particle green coke and/or cooked coke and/or carbon microsphere precursors are converted into graphite structures with the best crystal form, the binder is converted into graphite structures with common crystal forms, and the two structures are structurally recombined to form an embedded structure and a gradient crystal form structure, wherein the embedded structure and the gradient crystal form structure contain a plurality of small-particle graphite materials. And preferably, surface coating is carried out, so that a layer of amorphous carbon structure with the worst crystal form is formed on the outermost layer, and the composite negative electrode material with the outermost layer of amorphous carbon coating layer and the structures of 'mosaic' and 'gradient crystal form' is obtained.
(2) The composite negative electrode material has the advantages of stable structure, good orientation, low expansion and good liquid absorption performance, and the pole piece is made of the composite negative electrode material and rolled until the compacted density of the pole piece is 1.65g/cm3The liquid absorption time of the pole piece is less than or equal to 180 s.
(3) When the composite cathode material is used as an active substance to prepare the lithium ion battery, an additional conductive agent can be omitted, the energy density of the battery is improved, and the lithium ion battery prepared from the composite cathode material has high rate performance and excellent cycle performance.
The lithium ion simulation battery prepared by the composite negative electrode material is tested, and the reversible specific capacity is more than or equal to 350 mAh/g; the first coulombic efficiency is more than or equal to 90 percent.
The lithium ion full cell prepared by the composite cathode material has the rate charging performance of 8C/0.5C more than or equal to 80 percent and the 1C/1C cycle capacity retention rate of more than or equal to 90 percent in 500 weeks.
(4) The method provided by the invention gets rid of the traditional process method of coating the surface of the cathode material, adopts a brand new production flow, is simple and accurate in process control, has no harsh conditions, and is easy to industrialize.
Drawings
Fig. 1 is a schematic structural view of a composite anode material having an amorphous carbon coating layer as an outermost layer in the present invention.
Fig. 2 is an SEM image of the composite anode material prepared in example 1 of the present invention.
Fig. 3.1 is a charge-discharge curve diagram obtained by preparing a lithium ion simulation battery by using the composite negative electrode material prepared in example 1 of the present invention and testing, wherein a charge line 1, a charge line 2, and a charge line 3 represent charge curves of cycles 1, 2, and 3, respectively, and a discharge line 1, a discharge line 2, and a discharge line 3 represent discharge curves of cycles 1, 2, and 3, respectively.
FIG. 3.2 is an enlarged view of detail 1 of FIG. 3.1;
FIG. 3.3 is an enlarged view of detail 2 of FIG. 3.1;
fig. 4 is a graph of different rate charge curves for the composite anode material prepared in example 1 of the present invention.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
The composite negative electrode materials and the batteries prepared in the examples and the comparative examples are tested according to the following methods:
(1) microscopic state:
the surface morphology was tested by using a KYKY-2800B scanning electron microscope, a Chinese science instrument.
(2) Particle size and particle size distribution dispersion:
the average particle size is measured by a British Malvern-Mastersizer 2000 type laser particle size analyzer, and the composite negative electrode material of each embodiment has the average particle size D50 of 5-30 μm.
The formula for calculating the dispersion of the particle size distribution is as follows:
the dispersion of the particle size distribution is (D90-D10)/D50, and the dispersion of the composite anode material of each example is 0.5 to 2.0.
(3) Sphericity:
the sphericity of the composite negative electrode material prepared in each example was measured using a german QICPIC particle size particle shape analyzer and was between 0.8 and 0.9 in terms of sphericity S50.
(4) Specific surface area:
the specific surface area of the composite negative electrode material of each embodiment is 2.0-20.0 m by adopting a nitrogen adsorption BET method and measuring the specific surface area by using an American Congta Nova 1000e specific surface area/aperture analyzer2/g。
(5) And (3) electrochemical performance testing:
A. the lithium ion simulation battery prepared by using the composite negative electrode materials of the embodiments and the comparative examples specifically comprises the following steps:
the composite negative electrode materials of the embodiments and the comparative examples are used as negative electrode active substances of the lithium ion battery, carboxymethyl cellulose CMC is used as a thickening agent, styrene butadiene rubber SBR is used as a binder, and a conductive agent is not added to prepare an electrode material, wherein the composite negative electrode materials are used as the active substances according to the mass ratio: CMC: SBR 96.5:1.5: 2. Adding a proper amount of deionized water, uniformly mixing into paste by using a paste mixer, coating on a copper foil by using a coating machine, coating the copper foil with the thickness of 200 mu m, and punching into a pole piece with the diameter of 8.4mm after drying.
② a simulation battery with pure lithium sheet as counter electrode and the above-mentioned pole piece as working electrode, adopting Celgard 2400 type PE/PP/PE composite diaphragm and assembling them into mould type (the diameter of positive electrode stainless steel pad is 8.4mm, and the diameter of negative electrode copper pad is 11.4mm) in Germany Braun glove box, H2O and O2The bias voltage was below 1 ppm. The electrolyte adopts 1M LiPF6Solution of/EC + DMC + EMC.
B. A charging and discharging test cabinet of Wuhanjinnuo Land CT 2001A is used for carrying out a simulation battery charging and discharging performance test with segmented current density in a voltage range of 0.001-1.5V. Test methods and data were calculated as follows:
the first lithium intercalation specific capacity: a capacitance/mass of the negative electrode active material charged to 0.005V at a current density of 0.1C and then charged to 0.001V at a current density of 0.02C;
first lithium removal specific capacity: discharge to a capacity of 2.0V/mass of the negative electrode active material at a current density of 0.1C;
reversible specific capacity means: the first charging specific capacity, namely the first lithium removal specific capacity.
(6) Evaluation of the performance of the full cell:
A. the method for preparing the lithium ion full battery by using the composite negative electrode material for the lithium ion battery comprises the following steps:
firstly, the composite negative electrode materials of all the examples and the comparative examples are used as negative electrode active substances of the lithium ion battery, no conductive agent is added, Styrene Butadiene Rubber (SBR) is used as a binder, and carboxymethyl cellulose (CMC) is used as a thickening agent to prepare an electrode material; the three are active substances according to mass ratio: CMC: SBR 96.5:1.5: 2. Adding a proper amount of deionized water, uniformly mixing into paste by using a paste mixer, then coating on a copper foil by using a coating machine, and drying in vacuum to obtain the lithium ion full battery cathode.
② lithium cobaltate LiCoO2Lithium nickelate LiNiO2Or spinel lithium manganate LiMn2O4Is a positive electrode material; with 1M LiPF6the/EC + DMC + EMC is electrolyte; the Celgard 2400 type PE/PP/PE composite membrane is taken as a diaphragm; the whole battery is assembled by adopting the conventional 18650 type single battery production process.
B. The charging and discharging test cabinet is used for charging and discharging with the Wuhanjinnuo Land CT 2001A, and charging and discharging tests are carried out with different current densities within the voltage range of 3.0-4.35V. The performance evaluation and test method is as follows:
evaluating the liquid absorption performance of the pole piece: the graphene-based composite negative electrode material prepared by the method is coated according to the requirements, and is dried to form a pole piece, and the pole piece is rolled to a compaction density of 1.65g/cm3And moving the electrode plate into a German Braun glove box, dripping 10 mu L of electrolyte on the plane of the electrode plate by using a liquid gun, starting timing until the electrolyte is completely soaked on the surface of the electrode plate, and ending timing. The test was performed three times and the average value was taken.
Evaluation of battery rate charging performance: constant current charging is carried out on the full battery at the current density of 0.5C, then constant current charging is carried out at the current densities of 5C and 8C respectively, and the capacity proportion under different charging multiplying factors is calculated:
5C/0.5C represents the ratio of 5C multiplying power constant current charging capacity to 0.5C multiplying power constant current charging capacity;
8C/0.5C represents the ratio of 8C rate constant current charge capacity to 0.5C rate constant current charge capacity.
The larger the two ratios are, the higher the capacities at different charging rates are, the better the rate performance of the 18650 type full cell is, and the better the electrochemical performance of the composite negative electrode material is.
Example 1
(1) Putting the small-particle precursor (petroleum coke, volatile component 7.5%, ash content 0.45%, average particle size D501.5 μm) into a V-shaped mixer, and mixing for 10min to obtain a uniformly-mixed small-particle precursor;
heating the binder (coal tar pitch, softening point-50 ℃) to 60 ℃ to obtain the binder in a molten state;
simultaneously adding the uniformly mixed small-particle precursor and the binder in a molten state into kneading equipment, and carrying out kneading treatment at 50 ℃ for 2h to obtain a kneaded material;
wherein, the mass percentage of the binder in the molten state is 5 percent based on the total mass of the small particle precursor and the binder in the molten state as 100 percent;
(2) putting the kneaded material into an Acheson graphitizing furnace, graphitizing at 2700 ℃ under argon atmosphere, then crushing and shaping particles in a turbine type crusher to enable the average particle size D50 to be 11.05 mu m, the sphericity S50 to be 0.805 and the dispersion of particle size distribution to be 1.44, and obtaining the carbon material with the mosaic structure, namely the composite negative electrode material;
the physical properties of the composite negative electrode material of this example were measured, and the test results are shown in table 3.
More specifically, fig. 2 is an SEM image of the composite anode material of the present embodiment, and it can be seen that large particles are wrapped by small particles having different shapes and have a microporous structure.
The composite negative electrode material of the embodiment is used for preparing a lithium ion simulation battery and testing, and the test results are shown in table 1.
More specifically, the specific charge capacity, specific discharge capacity and efficiency of the charge-discharge cycle number of 1-3 are shown in table 1, and the charge-discharge curve is shown in fig. 3.1-3.3; in the figure, charge line 1, charge line 2 and charge line 3 represent the charge curves of cycles 1, 2 and 3, respectively, and discharge line 1, discharge line 2 and discharge line 3 represent the discharge curves of cycles 1, 2 and 3, respectively.
TABLE 1
The composite negative electrode material of the embodiment is adopted to prepare a pole piece, and the pole piece is rolled until the compaction density is 1.65g/cm3The test results are shown in table 3.
A lithium ion full cell was prepared and tested using the composite negative electrode material of this example, and the test results are shown in table 3.
More specifically, the charging curves with different multiplying powers are shown in fig. 4, and it can be seen from the graph that 8C multiplying power charging can reach more than 80%, and has a very good quick charging capability.
Example 2
(1) Adding a small-particle precursor (a mixture of petroleum coke and coal coke, 10.2% of volatile components, 0.45% of ash and 502.8 mu m of average particle size) into a trough mixer, and mixing for 30min to obtain a uniformly-mixed small-particle precursor;
heating the binder (petroleum asphalt, softening point-250 ℃) to 300 ℃ to obtain the binder in a molten state;
simultaneously adding the uniformly mixed small-particle precursor and the binder in a molten state into kneading equipment, and kneading for 1h at 280 ℃ to obtain a kneaded material;
wherein, the mass percentage content of the binder in the molten state is 10 percent based on the total mass of the small particle precursor and the binder in the molten state as 100 percent;
(2) putting the kneaded material into an internal series graphitizing furnace, graphitizing at 2800 ℃ in a nitrogen atmosphere, then crushing and shaping particles in an airflow vortex micro-pulverizer to enable the average particle size D50 to be 5.36 mu m, the sphericity S50 to be 0.85 and the particle size distribution dispersion to be 0.51, and obtaining the carbon material with the mosaic structure, namely the composite negative electrode material.
The physical properties of the composite negative electrode material of this example were measured, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is used for preparing a lithium ion simulation battery and testing, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is adopted to prepare a pole piece, and the pole piece is rolled until the compaction density is 1.65g/cm3The test results are shown in table 3.
A lithium ion full cell was prepared and tested using the composite negative electrode material of this example, and the test results are shown in table 3.
Example 3
(1) Putting the small-particle precursor (petroleum asphalt spherical non-graphitized product, 12.6% of volatile components, 0.30% of ash content and D509.8 mu m of average particle size) into a roller mixer to be mixed for 60min to obtain a uniformly-mixed small-particle precursor;
heating the binder (resins) to 100 ℃ to obtain a binder in a molten state;
simultaneously adding the uniformly mixed small-particle precursor and the binder in a molten state into kneading equipment, and kneading for 5 hours at 100 ℃ to obtain a kneaded material;
wherein the mass percentage of the binder in the molten state is 20 percent, based on 100 percent of the total mass of the small particle precursor and the binder in the molten state;
(2) putting the kneaded material into an Acheson graphitizing furnace, graphitizing at 3000 ℃ under a vacuum condition, and then crushing and shaping particles in a super cyclone vortex mill to ensure that the average particle size D50 is 15.67 mu m, the sphericity S50 is 0.82 and the particle size distribution dispersion is 0.99, thus obtaining the carbon material with the mosaic structure, namely the composite negative electrode material.
The physical properties of the composite negative electrode material of this example were measured, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is used for preparing a lithium ion simulation battery and testing, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is adopted to prepare a pole piece, and the pole piece is rolled until the compaction density is 1.65g/cm3The test results are shown in table 3.
A lithium ion full cell was prepared and tested using the composite negative electrode material of this example, and the test results are shown in table 3.
Example 4
(1) Putting the small-particle precursor (coal pitch spherical non-graphitized product, volatile component 2.1%, ash content 0.21%, average particle size D505.7 μm) into a conical double-screw mixer, and mixing for 120min to obtain a uniformly-mixed small-particle precursor;
heating the binder (natural asphalt, softening point-120 ℃) to 150 ℃ to obtain the binder in a molten state;
simultaneously adding the uniformly mixed small-particle precursor and the binder in a molten state into kneading equipment, and carrying out kneading treatment at 150 ℃ for 7h to obtain a kneaded material;
wherein, the mass percentage content of the binder in the molten state is 30 percent based on the total mass of the small particle precursor and the binder in the molten state as 100 percent;
(2) putting the kneaded material into an internal series type graphitization furnace, carrying out graphitization treatment at 3100 ℃ in neon atmosphere, then carrying out crushing and particle shaping in a winnowing crusher to ensure that the average particle size D50 is 22.41 mu m, the sphericity S50 is 0.87 and the particle size distribution dispersion is 1.96, thus obtaining the mosaic structure carbonaceous material, namely the composite negative electrode material.
The physical properties of the composite negative electrode material of this example were measured, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is used for preparing a lithium ion simulation battery and testing, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is adopted to prepare a pole piece, and the pole piece is rolled until the compaction density is 1.65g/cm3The test results are shown in table 3.
A lithium ion full cell was prepared and tested using the composite negative electrode material of this example, and the test results are shown in table 3.
Example 5
(1) Putting the small-particle precursor (pitch coke and petroleum asphalt system spherical non-graphitized product, the volatile component is 17.5 percent, the ash content is 0.10 percent, and the average particle size is D507.1 mu m) into a double cone mixer to be mixed for 180min to obtain a uniformly-mixed small-particle precursor;
heating a binder (a mixture of petroleum asphalt and a polymer, the softening point of which is 250 ℃) to 250 ℃ to obtain the binder in a molten state;
simultaneously adding the uniformly mixed small-particle precursor and the binder in a molten state into kneading equipment, and carrying out kneading treatment at 250 ℃ for 10h to obtain a kneaded material;
wherein, the mass percentage content of the binder in the molten state is 40 percent based on the total mass of the small particle precursor and the binder in the molten state as 100 percent;
(2) and (3) putting the kneaded material into an Acheson graphitization furnace, performing graphitization treatment at 3300 ℃ in a helium atmosphere, and then performing crushing and particle shaping in a double-rod crusher to obtain the carbon material with the mosaic structure, namely the composite negative electrode material, wherein the average particle size D50 is 29 mu m, the sphericity S50 is 0.898, and the particle size distribution dispersion is 1.80.
The physical properties of the composite negative electrode material of this example were measured, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is used for preparing a lithium ion simulation battery and testing, and the test results are shown in table 3.
The composite negative electrode material of the embodiment is adopted to prepare a pole piece, and the pole piece is rolled until the compaction density is 1.65g/cm3The test results are shown in table 3.
A lithium ion full cell was prepared and tested using the composite negative electrode material of this example, and the test results are shown in table 3.
Example 6
In this example, after the composite negative electrode material was prepared, carbon coating was continued to prepare a composite material having an amorphous carbon coating layer as the outermost layer. See table 2 for specific parameters.
Example 7
In this example, after the composite negative electrode material was prepared, carbon coating was continued to prepare a composite material having an amorphous carbon coating layer as the outermost layer. See table 2 for specific parameters.
Example 8
In this example, after the composite negative electrode material was prepared, carbon coating was continued to prepare a composite material having an amorphous carbon coating layer as the outermost layer. See table 2 for specific parameters.
Comparative example 1
The composition of the other raw materials, preparation method and conditions were the same as in example 1 except that the volatile content of the small particle precursor was 1.4%.
Comparative example 2
The composition of the raw materials, the preparation method and the conditions were the same as those in example 2, except that the content of the binder in a molten state was 4% by mass.
Comparative example 3
The composition of the raw materials, preparation method and conditions were the same as those in example 3 except that crushing and particle-sizing were performed so that the dispersion of particle size distribution was 2.2.
Comparative example 4
The preparation method was the same as in example 1 except that the small particle precursor was replaced with resins.
Comparative example 5
The preparation method and conditions were the same as in example 1 except that the coal pitch in a molten state was replaced with the coal pitch in an ordinary temperature state (non-molten state).
Comparative example 6
The preparation method and conditions were the same as in example 3, except that the average particle size D50 of the small particle precursor was 0.5 μm.
Comparative example 7
The preparation method and conditions were the same as in example 3, except that the average particle size D50 of the small particle precursor was 50 μm.
In order to make the specific preparation processes and parameters of the examples and comparative examples of the present invention more clear, the specific preparation process conditions and parameters of examples 1 to 8 and comparative examples 1 to 7 are summarized in table 2 below.
TABLE 2
Table 3 results of physical and electrochemical performance tests of composite anode materials of examples and comparative examples
The results of the physical and electrochemical performance tests of examples 1 to 8 and comparative examples 1 to 7 show that:
the composite negative electrode material obtained in the comparative example 1 has low raw material volatile components, less organic components released in the graphitization process, less micropores formed, and poor bonding effect of small particles, so that the liquid absorption performance of the composite negative electrode material is poor, the diffusion of lithium ions in the charging and discharging process is influenced, and the cycle performance of a battery is poor.
The composite negative electrode material obtained in the comparative example 2 has poor particle bonding and wrapping effects and poor particle forming due to too little binder used in the kneading process, and the charging rate and the cycle performance of the material are seriously affected.
The composite negative electrode material obtained in the comparative example 3 has too large dispersion degree of particle size distribution due to poor control of material crushing and particle shaping processes after graphitization, a large amount of micro powder and large particles are contained in powder, a sedimentation phenomenon is generated during the preparation of a pole piece, the qualified rate of battery preparation is low, the material capacity is low, the first efficiency is low, and the multiplying power charging and the cycle performance of the battery are poor.
The composite negative electrode material obtained in the comparative example 4 is prepared by replacing non-raw coke, cooked coke and carbon microsphere precursor materials with resin materials, so that the final composite product is a non-graphite material, and has poor crystallinity, large specific surface area, low specific capacity, low first effect and poor cycle performance.
The composite negative electrode material obtained in the comparative example 5 has the advantages that the particles cannot be compounded because the binder is not heated and melted and is directly kneaded by the solid binder, an embedded structure is not achieved, the qualified rate of battery manufacturing is low, the specific capacity is low, the first effect is low, and the rate charging and the cycle performance are poor.
The composite negative electrode material obtained in the comparative example 6 has poor bonding effect due to too small average particle size of raw materials, cannot form an embedded particle structure, has low qualification rate of battery manufacture, low specific capacity, low first effect and poor rate charging and cycle performance.
The composite negative electrode material obtained in comparative example 7 has a large average particle size of the raw material, which causes the particles to be collectively agglomerated and not to be kneaded, and finally causes the particles to be large and not to be evaluated.
The composite negative electrode material obtained in the embodiments 1 to 8 has better electrochemical performance: the reversible specific capacity is more than or equal to 350mAh/g, the first coulombic efficiency is more than or equal to 90 percent and is 1.65g/cm3The liquid absorption time of the pole piece under the compacted density is less than or equal to 180s, the rate charging performance is more than or equal to 80 percent at 8C/0.5C, and the cycle capacity retention rate at 1C/1C at 500 weeks is more than or equal to 90 percent. Therefore, the composite negative electrode material for the lithium ion battery has the outstanding advantages in various performances, such as stable structure, good orientation, low expansion, high rate performance, excellent liquid absorption performance and cycle performance, and can be used as the preferred negative electrode material of future energy storage batteries and power batteries.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (39)
1. A composite anode material, characterized in that the composite anode material comprises a mosaic structure carbonaceous material formed by mosaic of first carbon component small particles in a second carbon component frame carrier;
wherein the first carbon component small particles are converted from small particle precursors, and the small particle precursors are green coke and/or cooked coke and/or carbon microspheres, namely the combination of any 1 or at least 2 of the green coke, the cooked coke or the carbon microspheres; the volatile component of the small particle precursor is 2-20%; the average particle size of the small-particle precursor is 1-10 mu m; the second carbon component frame carrier is converted from a binder in a molten state, and the content of the binder in the molten state is 5-40% by mass based on 100% by mass of the small particle precursor and the binder in the molten state;
the graphite crystal structures of the first carbon component small particles and the second carbon component frame carrier are sequentially deteriorated.
2. The composite anode material of claim 1, further comprising an amorphous carbon coating layer coated on the outer layer of the mosaic structure carbonaceous material.
3. The composite anode material according to claim 2, wherein the graphite crystal structure of the first carbon component small particle, the second carbon component framework support and the amorphous carbon coating layer are deteriorated in order.
4. The composite anode material according to claim 1, wherein the particle diameter of the small particles of the first carbon component is 1 μm to 10 μm.
5. The composite anode material according to claim 1, wherein the composite anode material has an average particle size D50 of 5 to 30 μm.
6. The composite negative electrode material according to claim 1, wherein the sphericity S50 of the composite negative electrode material is 0.8 to 0.9.
7. The composite anode material according to claim 1, wherein the dispersion of the particle size distribution of the composite anode material is 0.5 to 2.0.
8. The composite anode material according to claim 1, wherein the specific surface area of the composite anode material is 2m2/g～20m2/g。
9. The composite anode material according to claim 1, wherein the mass percentage of the small particles of the first carbon component is 60 to 90% based on 100% of the total mass of the composite anode material.
10. The composite anode material according to claim 1, wherein the second carbon component framework support is contained in an amount of 10 to 30% by mass based on 100% by mass of the composite anode material.
11. The composite anode material according to claim 3, wherein the amorphous carbon coating layer is contained in an amount of 0.5 to 10% by mass based on 100% by mass of the composite anode material.
12. The composite anode material according to claim 3, wherein the amorphous carbon coating layer has a thickness of 10nm to 1000 nm.
13. A method for preparing a composite anode material according to any one of claims 1 to 12, characterized in that the method comprises the steps of:
(1) simultaneously adding a small-particle precursor and a binder in a molten state into kneading equipment, and carrying out kneading treatment to obtain a kneaded material, wherein the volatile content of the small-particle precursor is 2-20%;
(2) graphitizing the kneaded material under a protective atmosphere or vacuum condition to obtain a carbonaceous material with an embedded structure, namely a composite negative electrode material;
wherein, the small particle precursor is green coke and/or cooked coke and/or carbon microspheres, namely the combination of any 1 or at least 2 of the green coke, the cooked coke or the carbon microspheres.
14. The method of claim 13, further comprising performing step (3) after step (2): and coating the surface of the carbon material with the mosaic structure to obtain the composite negative electrode material with the amorphous carbon coating layer on the outermost layer.
15. The method of claim 13, wherein the ash content of the small particle precursor of step (1) is 0.5% or less.
16. The method of claim 13, wherein the green coke and/or cooked coke is any 1 or a combination of at least 2 of petroleum coke, pitch coke, and coal coke.
17. The method of claim 13, wherein the carbon microspheres are a combination of any 1 or 2 of petroleum-based mesophases or coal-based mesophases.
18. The method of claim 13, further comprising the step of mixing small particle precursors prior to step (1).
19. The method of claim 18, wherein the mixing is homogeneous mixing.
20. The method of claim 18, wherein the step of mixing the small particle precursor comprises mixing for a time period of 10 to 180 minutes.
21. The method of claim 18, wherein in the step of mixing the small particle precursor, the mixing is performed using any 1 of a V-blender, a trough blender, a drum blender, a conical twin screw blender, or a double cone blender.
22. The method of claim 13, wherein the binder of step (1) is any 1 or a combination of at least 2 of asphalt, polymer material.
23. The method of claim 22, wherein the binder of step (1) is any 1 or a combination of at least 2 of coal tar pitch, petroleum pitch, natural pitch, mesophase pitch, or resin.
24. The method according to claim 13, wherein the temperature of the kneading process of step (1) is 50 ℃ to 300 ℃.
25. The method according to claim 13, wherein the kneading treatment of step (1) is carried out for a time of 1 to 10 hours.
26. The method according to claim 13, further comprising a step of heating the adhesive to prepare the adhesive in a molten state before the step (1), wherein the heating temperature is 50 ℃ to 300 ℃.
27. The method according to claim 13, wherein the graphitization treatment in step (2) is performed by using 1 apparatus selected from an internal cascade graphitization furnace and an Acheson graphitization furnace.
28. The method of claim 13, wherein the protective atmosphere of step (2) is any 1 or a combination of at least 2 of a helium atmosphere, a neon atmosphere, an argon atmosphere, or a nitrogen atmosphere.
29. The method according to claim 13, wherein the temperature of the graphitization treatment in step (2) is 2700 ℃ to 3300 ℃.
30. The method of claim 14, wherein the carbon source for the surface coating in step (3) is any 1 or a combination of at least 2 of furan resin, urea resin, melamine resin, phenol resin, epoxy resin, polyvinyl alcohol, polyethylene glycol, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, polystyrene rubber, cellulose, coke, coal tar pitch, petroleum pitch, or natural pitch.
31. The method of claim 14, wherein the temperature of the heat treatment of the surface coating in step (3) is 700 ℃ to 1300 ℃.
32. The method according to claim 13, further comprising performing step (a) after the kneading treatment of step (1) and before the graphitization treatment of step (2): crushing and particle shaping.
33. The method according to claim 14, further comprising performing step (B) after the graphitization treatment of step (2) and before the surface coating of step (3): and (3) crushing and shaping the particles to obtain particles with the particle size distribution dispersion degree of 0.5-2.0 and the sphericity S50 of 0.8-0.9.
34. The method of claim 33, wherein the crushing and particle sizing in step (B) is performed using any 1 of a turbo mill, a jet vortex mill, a super cyclone vortex mill, a winnowing mill, or a double-roll mill.
35. The method of claim 32, wherein the crushing and particle sizing in step (a) is performed using any 1 of a turbo mill, a jet vortex mill, a super cyclone vortex mill, a winnowing mill, or a double-roll mill.
36. The method of claim 13, further comprising the step of sieving the resulting composite anode material.
37. The method according to claim 13, characterized in that it comprises the steps of:
(1) mixing small-particle precursors with the average particle size of 1-10 mu m to obtain uniformly mixed small-particle precursors; heating the binder to obtain a molten binder;
simultaneously adding the uniformly mixed small-particle precursor and the binder in a molten state into kneading equipment, carrying out kneading treatment for 1-10 h at 50-300 ℃, and then carrying out crushing and particle shaping to obtain a kneaded material;
(2) graphitizing the kneaded material at 2700-3300 ℃ in a protective atmosphere to obtain a mosaic structure carbonaceous material;
(3) crushing and shaping the mosaic structure carbonaceous material, mixing the mosaic structure carbonaceous material with a carbon source, carrying out heat treatment at 700-1300 ℃ to realize surface coating, and carrying out screening treatment to obtain a composite negative electrode material with the average particle size D50 of 5-30 mu m;
wherein, the small particle precursor is any 1 or the combination of at least 2 of green coke, cooked coke or carbon microspheres.
38. A lithium ion battery, characterized in that a negative electrode material component of the lithium ion battery comprises the composite negative electrode material according to any one of claims 1 to 12 as a negative electrode active material.
39. The lithium ion battery according to claim 38, wherein the negative electrode material composition of the lithium ion battery comprises the composite negative electrode material according to any one of claims 1 to 12 as a negative electrode active material, and no additional conductive agent is added.
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| CN110963489B (en) * | 2018-09-28 | 2023-07-28 | 贝特瑞新材料集团股份有限公司 | Carbon negative electrode material, preparation method thereof and lithium ion battery |
| CN110970599B (en) * | 2018-09-28 | 2022-10-14 | 贝特瑞新材料集团股份有限公司 | Graphene-based composite negative electrode material, preparation method thereof and lithium ion battery |
| CN109950495B (en) * | 2019-03-27 | 2022-06-14 | 溧阳紫宸新材料科技有限公司 | Preparation method of high-rate graphite negative electrode material, negative electrode material and lithium ion battery |
| CN112531160A (en) * | 2019-09-19 | 2021-03-19 | 贝特瑞新材料集团股份有限公司 | Amorphous carbon negative electrode material and preparation method and application thereof |
| WO2021217617A1 (en) * | 2020-04-30 | 2021-11-04 | 宁德时代新能源科技股份有限公司 | Negative electrode active material, manufacturing method therefor, secondary battery, and device comprising secondary battery |
| CN114583119B (en) * | 2020-12-01 | 2024-02-27 | 湖南中科星城石墨有限公司 | Preparation method of composite particles, composite particles prepared by using preparation method and application of composite particles |
| CN112652753A (en) * | 2020-12-29 | 2021-04-13 | 湖州杉杉新能源科技有限公司 | Lithium ion battery negative electrode material, lithium ion battery and preparation method and application thereof |
| CN114300646A (en) * | 2021-12-14 | 2022-04-08 | 惠州锂威新能源科技有限公司 | Composite graphite negative electrode material and preparation method and application thereof |
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| JP2004063411A (en) * | 2002-07-31 | 2004-02-26 | Jfe Chemical Corp | Complex graphite material, its manufacturing method, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
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