CN114620707A - Preparation method of long-cycle lithium ion battery cathode material - Google Patents
Preparation method of long-cycle lithium ion battery cathode material Download PDFInfo
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
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- H—ELECTRICITY
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- 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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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- C—CHEMISTRY; METALLURGY
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
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- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
Abstract
The invention provides a preparation method of a long-cycle lithium ion battery cathode material, which takes waste graphitized auxiliary materials as raw materials, namely waste auxiliary materials generated in the graphitizing production process, such as scrapped resistor materials, crucible crushed materials, electrode crushed materials and the like, as carbon materials, and the carbon materials are firstly subjected to the process treatments of crushing, grinding, shaping, demagnetizing and the like, so that the standard of the lithium ion battery cathode material can be preliminarily achieved. Because the lithium ion battery cathode material is subjected to a graphitization process during the use as a graphitization auxiliary material, the lithium ion battery cathode material does not need to be graphitized again during the conversion process, so that the material has extremely high cost performance, and the finally obtained lithium ion battery cathode material with a long cycle function and low cost has good charge-discharge and long cycle performance. The invention adopts the raw materials and the working procedures to meet the requirements of manufacturing and using the lithium ion battery, the battery manufactured by the process also has excellent cycle performance, and meanwhile, the material has unusual cost performance because the high-cost graphitization working procedure is not needed.
Description
The technical field is as follows:
the invention relates to the field of a negative electrode material for a lithium ion battery and a preparation method thereof, which are prepared by taking waste graphitizing auxiliary materials as raw materials, in particular to a preparation method of a long-cycle negative electrode material for the lithium ion battery.
Background art:
the lithium ion battery mainly comprises a transition metal oxide with lithium embedded in a positive electrode material, a highly graphitized carbon and diaphragm polyolefin microporous membrane and an electrolyte material.
With the increasing popularity of lithium ion batteries in the market and the increasing scale of the usage of lithium ion batteries, the types of lithium ion batteries are further subdivided. In different fields, the performance requirements for lithium ion batteries are also different, some seek high energy density, some seek high-rate charge and discharge, and some seek long cycle life, but for the middle and low-end broad population of the general public, the low cost and high cost performance are the mainstream direction of the development of the lithium ion batteries and the related materials thereof. The negative electrode material is an important component of the lithium ion secondary battery, and plays a considerable role in the manufacturing cost of the lithium ion battery. With the fire explosion of new energy market in recent years, the prices of the raw materials of traditional negative electrode materials such as natural graphite, petroleum coke, needle coke and the like are increased, and the processing and manufacturing cost of each process in the negative electrode industry is also increased year by year. Therefore, many manufacturers of lithium ion batteries have looked to the development of cost-effective products with low cost. Especially in the area of cost-effective material development. The cost reduction pressure is great for the existing products, so that the development of products with high performance and low cost is the key point.
For example, the chinese patent publication No. CN 102255077a discloses a negative electrode material for lithium ion battery and a method for preparing the same, which comprises coating a carbon compound on a surface of a graphite fine powder as a core material to form a first coating layer, then coating the first coating layer with the carbon compound to form a second coating layer, and graphitizing the second coating layer to form a graphite material with a core-shell structure. The novel negative electrode material is synthesized by a secondary granulation method, so that the lithium precipitation phenomenon is reduced or even avoided when the lithium ion battery is charged and discharged at low temperature, and the irreversible loss of Li in the battery charging and discharging process at low temperature is reduced.
With the recent great improvement of the graphitization capacity of the lithium ion battery cathode material, the consumption of auxiliary materials such as furnace end electrodes, resistor materials and graphite crucibles in the corresponding graphitization process is also greatly increased. The furnace end electrode mainly takes petroleum coke and needle coke as raw materials and is responsible for transmitting electricity to the graphitization furnace; the resistance material is generally petroleum coke green coke coarse particles, the furnace temperature is raised to meet the temperature requirement required by graphitization processing due to self heat generation in the power-on process, and the resistivity is greatly reduced due to gradual graphitization of the resistance material in the power-on process, so that the resistance material cannot meet the use requirement of the resistance material and is scrapped; the graphite crucible is used for holding the cathode material and completing graphitization in the graphitization furnace, and the crucible is inevitably worn and scrapped due to loss in the long-term use process. The conventional common treatment mode of the materials is to sell the materials as carburant after being scrapped, so that the materials are low in price and low in added value of products.
For such as scrap resistor material, broken graphite crucible, electrode crushed material, the graphitization degree and carbon content are not low, the basic requirement of being used as the negative electrode material is met, if the scrap can be converted into the negative electrode material through further processing and then treated, the part of the scrap can obtain higher added value, and the enterprise obtains greater profit. However, due to the defects of the material, when the material is made into the graphite cathode material of the lithium ion battery, compared with the graphite cathode material of the lithium ion battery in the traditional sense, the material has the problems of low capacity, low first charge efficiency, poor cycle stability and the like, and is far from the performance of the common graphite cathode material of the lithium ion battery. How to recycle the lithium ion battery effectively is a practical problem in lithium ion battery enterprises today with increasingly competitive industry. The reasonable use of the graphite can change waste into valuable, reduce the loss of consumables in the graphitization process and realize sustainable development of resource utilization.
Therefore, how to provide a preparation method of a low-cost long-cycle lithium ion battery cathode material is provided, waste auxiliary materials such as scrapped resistor materials, crucible crushed materials, electrode crushed materials and the like generated in a graphitization production process are taken as carbon materials, namely, the waste graphitization auxiliary materials are taken as raw materials, and the morphology of the waste graphitization auxiliary materials is improved and optimized through technological treatment such as crushing, grinding, shaping and demagnetizing, so that the waste graphitization auxiliary materials initially reach the standard of being used as the lithium ion battery cathode material. Because the carbon material is subjected to the graphitization process during the use as the graphitization auxiliary material, the carbon material does not need to be graphitized again during the process of converting the carbon material into the lithium ion battery cathode material, so that the production cost is greatly reduced, the material has extremely high cost performance, and the low-end cathode material manufactured by taking the carbon material as the carbon material has unusual competitiveness in price. The finally obtained low-cost lithium ion battery cathode material with the long cycle function has good charge-discharge and long cycle performance.
The invention content is as follows:
the invention aims to overcome the defects of the prior art and provides a preparation method of a long-cycle lithium ion battery cathode material. Because the lithium ion battery cathode material is subjected to a graphitization process during the use as a graphitization auxiliary material, the lithium ion battery cathode material does not need to be graphitized again during the conversion process, so that the material has extremely high cost performance, and the finally obtained lithium ion battery cathode material with a long cycle function and low cost has good charge-discharge and long cycle performance.
The invention provides a preparation method of a long-cycle lithium ion battery cathode material, which takes waste graphitized auxiliary materials as raw materials, obtains graphite powder through processing the raw materials, is doped with boron, and is coated twice, and the preparation method comprises the following steps:
1) preparing a raw material grinding material, namely processing the waste graphitized auxiliary material into the raw material grinding material with certain particle size and tap density through the procedures of coarse crushing, shaping, grading and demagnetizing;
2) preparing cathode base material powder, namely mixing the raw material grinding powder in the step 1) with a resin polymer and a boron-doped agent, and putting the mixture into a VC mixer to be uniformly mixed to obtain cathode base material powder;
3) preparing a precursor material, namely transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneading machine to be stirred and mixed, kneading at normal temperature until the material is in a uniform and particle-free slurry state, and then increasing the oil temperature of the kneading machine to heat and evaporate the solvent in the slurry to dryness to obtain the precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), cooling, scattering the obtained lump material, and screening to obtain the pre-carbonized precursor;
5) preparing a cathode material of a crude lithium battery, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, continuously stirring and heating the material to a certain temperature, slowly pouring preheated liquid tar into the high-pressure reaction kettle, keeping the temperature, uniformly mixing in an inert atmosphere, stopping stirring, pressurizing and dipping under the condition of pressure, decompressing and cooling, transferring into a roller kiln for high-temperature secondary carbonization treatment, and cooling to obtain the cathode material of the crude lithium battery;
6) preparing a lithium ion battery cathode material, scattering the coarse lithium battery cathode material obtained in the step 5), and sieving to obtain the lithium ion battery cathode material.
The preparation method of the low-cost long-cycle lithium ion battery cathode material comprises the step 1) of performing coarse crushing treatment by adopting a roller jaw crushing integrated machine device, controlling the particle size of coarse crushed granules to be less than or equal to 2mm, and controlling the graphitization degree to be more than or equal to 91.
Preferably, the grinding, shaping and grading processes in the step 1) are carried out, a grinding and shaping machine is used for processing, after coarse broken particles are further crushed and shaped, fine powder is removed through a combined grading device, and raw material grinding powder meeting the requirements is obtained; the median particle diameter of the raw material grinding powder is controlled to be D50 between 3.0 and 30.0 mu m, and the tap density is controlled to be 0.70-1.055g/cm3。
Further preferably, the demagnetization process in the step 1) is implemented, wherein the demagnetization mode is current demagnetization or permanent magnet demagnetization, the demagnetization equipment is connected with a horizontal or vertical mixed screening machine, the uniformity of the material after the demagnetization is ensured, and the content of magnetic substances in the raw material grinding powder after the demagnetization is controlled to be less than or equal to 5.0 ppm.
The preparation method of the low-cost long-cycle lithium ion battery cathode material comprises the following steps of 2) preparing cathode substrate powder, namely mixing the raw material grinding powder in the step 1) with a resin polymer and a boron-doped agent, putting the mixture into a VC mixer, and uniformly mixing to obtain cathode substrate powder; controlling the mass ratio of the raw material grinding powder to the resin polymer and the boron-doped agent to be 100: 1-20: 0.1-2, and controlling the mass concentration of the aqueous solution of sodium carboxymethylcellulose (CMC) to be 0.1-3.5 Wt%; the mass ratio of the raw material grinding powder to the aqueous solution of sodium carboxymethylcellulose (CMC) is controlled to be 100: 20-200.
Preferably, the precursor material in the step 3) is prepared, the heating temperature of the kneading device is controlled to be 100-250 ℃, and the kneading, stirring and mixing time is controlled to be 1-6 hours.
Preferably, the method comprises the step 4) of preparing a pre-carbonized precursor material, wherein the primary pre-carbonization treatment is to control the temperature of the low-temperature pre-carbonization treatment to be 480-680 ℃ under the inert atmosphere, and the temperature rise rate of the low-temperature pre-carbonization treatment to be 1-8 ℃/min; the low-temperature carbonization treatment and the heat preservation time are controlled to be 5-18 h.
The invention relates to a preparation method of a long-cycle lithium ion battery cathode material, which comprises the following steps of 5) preparing a crude lithium battery cathode material, putting a pre-carbonization precursor material obtained in the step 4) into a high-pressure reaction kettle, heating the material to 80-300 ℃, slowly pouring tar preheated to be in a liquid state into the high-pressure reaction kettle, keeping the temperature, uniformly mixing in an inert atmosphere, stopping stirring, carrying out pressurized impregnation for 0.5-3 h under the pressure of 0.2-1.5Mp, carrying out pressure relief cooling, transferring into a roller kiln, then heating the roller kiln to 950-1200 ℃ in the inert atmosphere at the heating rate of 1-7 ℃/min for carrying out high-temperature secondary carbonization treatment, controlling the high-temperature secondary carbonization and heat preservation time to be 12-24 hours, wherein the tar is coal tar or petroleum tar, the coking value of the tar is 20-30%, and cooling to obtain the crude lithium battery cathode material.
The preparation method of the long-cycle lithium ion battery cathode material controls the water content of the coarsely crushed raw material grinding material to be less than or equal to 0.50 Wt%, the ash content to be less than or equal to 0.40 Wt%, and the resistance of the raw material grinding material to be less than or equal to 130m omega. The coarse crushed particles are the raw material grinding powder, the same as below.
The invention discloses a preparation method of a long-cycle lithium ion battery cathode material, which adopts the lithium ion battery cathode material prepared by the preparation method and has the following beneficial effects that:
according to the invention, waste graphitized auxiliary material raw materials are treated to obtain graphite powder, and then a series of operations such as boron doping, twice coating, crushing, shaping, grading, demagnetizing and the like are performed, so that the surface defects of the material are effectively optimized, the grain composition is optimized, the compact packing is realized, and the effect of improving the tap density is achieved;
the method comprises the following steps of firstly, taking waste graphitized auxiliary materials as raw materials, wherein the waste graphitized auxiliary materials comprise waste resistor materials, crucible crushed materials, electrode crushed materials and the like as carbon materials, and the waste graphitized auxiliary materials are any one or more of the waste resistor materials, waste graphite crucibles and electrode crushed materials. The lithium ion battery cathode material is processed into the lithium ion battery cathode material by a corresponding process method, so that the production cost of the lithium ion battery cathode material is greatly reduced, and the production cost of a lithium battery is also reduced; because the existence of the magnetic substance in the scrapped graphitized auxiliary material can seriously affect the performance impurity components of the lithium ion negative electrode material, if the material contains a plurality of metal elements and other metal materials, namely the content of the magnetic substance, the chemical performance of the precursor is directly affected, and further the performance of the lithium ion negative electrode material is also affected. Therefore, the invention controls the content of the magnetic substance in the degaussing electrode material, namely the raw material grinding material, to be less than or equal to 1.0-5.0ppm by controlling the degaussing electrode material, and simultaneously controls the graphitization degree to be more than or equal to 90; controlling the water content of the coarse crushed granules to be less than or equal to 0.50 Wt%, the ash content of the coarse crushed granules to be less than or equal to 0.40 Wt% and the resistance of the coarse crushed granules to be less than or equal to 130m omega; thus, the prepared long-cycle lithium ion battery cathode material is prepared; the discharge capacity of the prepared lithium ion battery reaches above 348mAh/g, and the capacity retention rate of 1C charge-discharge for 1000 weeks reaches above 96.8 percent; specific properties and performance data for the comparative examples are shown in table 1;
secondly, because the waste graphitized auxiliary material is graphitized, the texture is soft, the powder obtained after milling has more surface defects and a large number of open pores are formed inside the particles, so that the specific surface area is high, the tap density is low, the mechanical strength is too low, and the specific surface area is too high, so that the battery consumes a large amount of electrolyte in the process of forming an SEI film by first charging, the first efficiency of the battery is low, the tap density is too low, the energy density of the battery can be seriously influenced, and the mechanical strength is too low, so that the subsequent battery processing is not facilitated. The surface of the particle can be modified by introducing the resin polymer to form the hard carbon coating layer, the surface appearance of the particle is repaired, the tap density of the particle is improved, the specific surface area is reduced, and the discharge capacity and the first efficiency are both increased to a certain extent. By introducing the boron-doped agent, the surface defects of the negative electrode substrate are further reduced and the graphitization degree of the negative electrode substrate is improved under the catalytic action of boron, and the specific surface area of the material is further reduced through the composite reaction of boron and the surface of the negative electrode substrate, so that the high-temperature and low-temperature performance is obviously improved;
and the tar is used as a coating agent, so that the formed coating layer is more uniform, and the tar and the primary coated hard carbon and boron dopant act together, so that the structural stability and the cyclicity of the obtained composite graphite cathode material are greatly improved. The method comprises the steps of carrying out pressure impregnation within the temperature range of 80-300 ℃, filling the graphite pores with tar oil with good fluidity and wettability at the temperature, wherein a certain volume shrinkage is generated in the process, and a certain pressure is given to the graphite pores in the impregnation process, so that the tar oil of which the periphery is not converted to a mesophase is further filled and solidified, and the method is used for specifically repairing the characteristics that the surface defects of carbon materials mainly comprising scrapped resistor materials, crucible crushed materials, electrode crushed materials and the like are more and a large number of open pores exist in the particles.
Fourthly, because the cost of the raw materials is low, and the lithium ion battery cathode material with reliable performance can be obtained without graphitization treatment, the production cost of the lithium ion battery cathode material can be greatly reduced, and the advantage of the lithium ion battery cathode material is obvious. Meanwhile, water is used as a solvent, so that no additional pollution is caused in the evaporation process, and the method is more environment-friendly.
The method has simple steps, easy popularization, good high-temperature performance and good low-temperature performance, thereby preparing the long-cycle lithium ion battery cathode material; the discharge capacity of the prepared lithium ion battery reaches above 348mAh/g, and the capacity retention rate of 1C charge-discharge for 1000 weeks reaches above 96.8 percent; specific properties and performance data for the comparative examples are shown in table 1;
description of the drawings:
FIG. 1: FIG. 1 is an SEM image of a long-cycle lithium ion battery negative electrode material prepared in example 1;
fig. 2 is a first charge-discharge curve of a long-cycle lithium ion battery negative electrode material obtained in example 1 of a negative electrode material preparation method according to the present invention;
fig. 3 is an electrical cycle curve of 1000 charge and discharge cycles at 1C rate of the graphite negative electrode material obtained according to example 1 and comparative example 1, that is, the low-cost long-cycle lithium ion battery negative electrode material prepared according to the present invention.
The specific implementation mode is as follows:
the present invention will be further described with reference to the following detailed description, and in order to make the technical problems, technical solutions and advantages solved by the present invention more apparent, the present invention will be further described with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a preparation method of a circulating lithium ion battery cathode material, which takes waste graphitized auxiliary materials as raw materials, obtains graphite powder through processing the raw materials, and kneads the graphite powder to prepare a precursor, and is characterized by comprising the following steps:
1) preparing a raw material grinding material, namely processing the waste graphitized auxiliary material into the raw material grinding material with certain particle size and tap density through the procedures of coarse crushing, shaping, grading, demagnetizing and the like; during coarse crushing, the particle size of the coarse crushed granules is controlled to be 0.2-2mm, the graphitization degree is more than or equal to 91, and when the crushing, shaping, grading and demagnetizing are finished, the median particle size of the processed powder is controlled to be D50 to be 3.0-30.0 mu m, the tap density is 0.70-1.05g/cm3, the content of magnetic substances is less than or equal to 5.0ppm, and the processed powder is used as raw material grinding powder.
2) Preparing cathode substrate powder, mixing the raw material grinding powder in the step 1) with a resin polymer and a boron doping agent, putting the mixture into a VC mixer, uniformly mixing, controlling the mixing time of the VC mixer to be 1-3h, and controlling the mass ratio of the raw material grinding powder to the resin polymer to the boron doping agent to be 100: 1-40: 1-10, which is negative electrode base material powder;
3) preparing a precursor material, transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneading machine, kneading at normal temperature until the material is in a uniform and particle-free slurry state, increasing the temperature of the kneading machine to evaporate the solvent in the slurry, controlling the oil temperature of the kneading machine to be 100-250 ℃, controlling the normal-temperature kneading and stirring mixing time to be 1-6 hours, and controlling the mass concentration of the sodium carboxymethylcellulose (CMC) aqueous solution to be 0.1-3.5 Wt%; controlling the mass ratio of the negative electrode base material powder to the aqueous solution of sodium carboxymethylcellulose (CMC) to be 100: 20-200 to obtain a precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), and cooling to obtain a pre-carbonized precursor; step 4) preparing a pre-carbonized precursor material, wherein the low-temperature carbonization treatment is to control the temperature of the low-temperature carbonization treatment to be 480-680 ℃ under the inert atmosphere and control the heating rate of the low-temperature carbonization treatment to be 2-8 ℃/min; the low-temperature carbonization treatment and the heat preservation time are controlled to be 5-18 h. Obtaining a pre-carbonized precursor material;
5) preparing a cathode material of a coarse lithium battery, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, heating the material to 80-300 ℃, slowly pouring tar preheated to be in a liquid state into the high-pressure reaction kettle, and mixing the pre-carbonized precursor and the tar according to the mass ratio of 100: 1-20, keeping the temperature, mixing for 1-3h in an inert atmosphere, stopping stirring, then pressurizing and dipping for 0.5-3 h under the pressure of 0.2-1.5Mp, decompressing, cooling, transferring into a roller kiln for high-temperature secondary carbonization treatment, and cooling to obtain the crude lithium battery negative electrode material;
6) preparing a lithium ion battery cathode material, scattering the crude lithium battery cathode material obtained in the step 5), and sieving with a 200-mesh and 400-mesh sieve to obtain the lithium ion battery cathode material.
Preferably, the boron doping agent is one of boron compound boric acid and boron oxide.
Preferably, the resin polymer includes, but is not limited to, polymers formed from phenolic resins, furan resins, furfural resins, furfuryl ketone resins, furfuryl alcohol resins.
Preferably, the inert atmosphere may include, but is not limited to, inert gases such as nitrogen, argon, helium, etc., which are not susceptible to chemical reactions;
preferably, the selected tar comprises coal tar, petroleum coke oil and the like, and the carbon residue value is preferably 20-30%.
Preferably, the water content of the coarsely crushed raw material powder is controlled to be less than or equal to 0.50 Wt%, the ash content is controlled to be less than or equal to 0.40 Wt%, the content of the magnetic substance is controlled to be less than or equal to 1.0-5.0ppm, and the resistance of the raw material powder is controlled to be less than or equal to 130m omega, namely the resistance of the demagnetized raw material powder.
The long-cycle lithium ion battery cathode material prepared by the method is suitable for long-cycle use; the first efficiency is improved. The embodiments disclosed in the following embodiments are not described in detail in the same way as the above-described embodiments. The specific embodiments or examples are mass or mass ratio.
Example 1:
the invention discloses a preparation method of a long-cycle lithium ion battery cathode material, which takes waste graphitized auxiliary materials as raw materials, selects scrapped resistance materials as the raw materials of specific example 1, hereinafter referred to as resistance materials for short,
1) preparing raw material grinding powder, and preparing the scrapped resistance material into the resistance material raw material grinding powder through the working procedures of coarse crushing, shaping, grading, demagnetizing and the like; during coarse crushing, controlling the particle size of coarse crushed granules to be less than or equal to 2.0mm and the graphitization degree to be 93.1, and then performing crushing, shaping, grading and demagnetizing treatment to obtain resistance material raw material powder, wherein the particle size Dmin is 2.0-3.0 mu m, the D50 is 13.0-16.0 mu m, the tap density is 0.87/cm3, and the content of magnetic substances is 0.8 ppm; namely the resistance material grinding powder
2) Preparing negative electrode base material powder, mixing the resistance material grinding powder in the step 1) with phenolic resin polymer and boric acid powder, putting the mixture into a VC mixer together, uniformly mixing, controlling the mixing time of the VC mixer to be 2h, and controlling the mass ratio of the raw material grinding powder to the phenolic resin polymer and the boric acid powder to be 100: 3.0: 0.5, namely negative electrode substrate powder;
3) preparing a primary precursor material, transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneader, kneading for 3 hours at normal temperature until the material is in a uniform and particle-free slurry state, heating kneader oil to 200 ℃, evaporating the solvent in the slurry to dryness, wherein the concentration of the prepared sodium carboxymethylcellulose (CMC) aqueous solution is 1.2%; controlling the mass ratio of the negative electrode base material powder to the aqueous solution of sodium carboxymethylcellulose (CMC) to be 100:100, namely obtaining a primary precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), and cooling to obtain a pre-carbonized precursor; step 4) preparing a pre-carbonized precursor material, wherein the low-temperature carbonization treatment is to control the temperature of the low-temperature carbonization treatment to be 550 ℃ under the inert atmosphere and control the heating rate of the low-temperature carbonization treatment to be 2 ℃/min; the continuous heat preservation time is 2 h. Cooling and scattering the mixture and passing the mixture through a 325-mesh screen to obtain a pre-carbonized precursor;
5) preparing a lithium battery negative electrode material, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, heating the material to 200 ℃, slowly pouring tar preheated to be in a liquid state into the high-pressure reaction kettle, and mixing the pre-carbonized precursor and the tar according to the mass ratio of 100: 6, keeping the temperature at N2Mixing in inert atmosphere for 2h, stopping stirring, pressurizing and soaking under 1.0Mp for 2h, relieving pressure, cooling, transferring into roller kiln, heating to 1150 deg.C under inert atmosphere at 2 deg.C/min, and heating to high temperatureCarrying out warm carbonization treatment, keeping the temperature for 5 hours, and cooling to obtain a crude lithium battery negative electrode material;
6) preparing a lithium ion battery cathode material, scattering the coarse lithium battery cathode material, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material; namely the long-cycle lithium ion battery cathode material product prepared by the preparation method of the low-cost long-cycle lithium ion battery cathode material.
The preparation methods in the following examples are the same as the methods and procedures and technical parameter control disclosed in the above specific embodiments or example 1, unless otherwise specified.
Example 2
In the embodiment of the invention, the waste materials of the resistance materials are selected as the raw materials of the specific embodiment 2, namely the electrode crushed materials are the raw materials of the low-cost long-cycle lithium ion battery cathode material of the embodiment, and the raw materials are hereinafter referred to as the electrode materials for short
1) Preparing raw material grinding powder, and preparing the electrode crushed material into the electric resistance material raw material grinding powder through the working procedures of coarse crushing, shaping, grading, demagnetizing and the like; during coarse crushing, controlling the particle size of coarse crushed granules to be less than or equal to 2.0mm and the graphitization degree to be 92.3, and then performing crushing, shaping, grading and demagnetizing treatment to obtain resistance material raw material powder, wherein the particle size Dmin is 1.5-2.5 mu m, the D50 is 11.0-14.0 mu m, the tap density is 0.85/cm3, and the content of magnetic substances is 0.3 ppm; namely the electrode material grinding powder
2) Preparing cathode substrate powder, mixing the resistance material grinding powder in the step 1), the furfural resin polymer and the boric acid powder, putting the mixture into a VC mixer, uniformly mixing, controlling the mixing time of the VC mixer to be 2 hours, and controlling the mass ratio of the raw material grinding powder to the furfural resin polymer and the boric acid powder to be 100: 2.5: 0.5, namely negative electrode substrate powder;
3) preparing a primary precursor material, transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneader, kneading for 3 hours at normal temperature until the material is in a uniform and particle-free slurry state, heating kneader oil to 220 ℃, evaporating the solvent in the slurry to dryness, wherein the concentration of the prepared sodium carboxymethylcellulose (CMC) aqueous solution is 1.5%; controlling the mass ratio of the negative electrode base material powder to the aqueous solution of sodium carboxymethylcellulose (CMC) to be 100:120 to obtain a primary precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), and cooling to obtain a pre-carbonized precursor; step 4) preparing a pre-carbonized precursor material, wherein the low-temperature carbonization treatment is to control the temperature of the low-temperature carbonization treatment to be 550 ℃ under the inert atmosphere and control the heating rate of the low-temperature carbonization treatment to be 2 ℃/min; the continuous heat preservation time is 2 h. Cooling and scattering the mixture and passing the mixture through a 325-mesh screen to obtain a pre-carbonized precursor;
5) preparing a lithium battery negative electrode material, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, heating the material to 200 ℃, slowly pouring tar preheated to be in a liquid state into the high-pressure reaction kettle, and mixing the pre-carbonized precursor and the tar according to the mass ratio of 100:7, keeping the temperature, mixing for 2 hours in an inert atmosphere, stopping stirring, then pressurizing and dipping for 2 hours under the pressure of 0.8Mp, decompressing and cooling, transferring into a roller kiln, heating to 1200 ℃ in the inert atmosphere at the heating speed of 2.5 ℃/min, carrying out high-temperature carbonization treatment, keeping the temperature for 5 hours, and cooling to obtain the crude lithium battery negative electrode material;
6) preparing a lithium ion battery cathode material, scattering the coarse lithium battery cathode material, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material; namely the long-cycle lithium ion battery cathode material product prepared by the preparation method of the low-cost long-cycle lithium ion battery cathode material.
Example 3
In the embodiment of the invention, crucible material waste, namely waste graphite crucible material, is selected as the raw material in the embodiment 3, and is referred to as crucible material hereinafter
1) Preparing raw material grinding powder, and preparing the electrode crushed material into the electric resistance material raw material grinding powder through the working procedures of coarse crushing, shaping, grading, demagnetizing and the like; during coarse crushing, controlling the particle size of coarse crushed granules to be less than or equal to 2.0mm and the graphitization degree to be 92.3, and then performing crushing, shaping, grading and demagnetizing treatment to obtain resistance material raw material powder, wherein the particle size Dmin is 1.0-2.0 mu m, the D50 is 14.0-17.0 mu m, the tap density is 0.83/cm3, and the content of magnetic substances is 0.5 ppm; namely the electrode material grinding powder
2) Preparing negative electrode substrate powder, mixing the resistance material grinding powder in the step 1) with phenolic resin polymer and boron oxide powder, putting the mixture into a VC mixer, uniformly mixing, controlling the mixing time of the VC mixer to be 2h, and controlling the mass ratio of the raw material grinding powder to the phenolic resin polymer and the boron oxide powder to be 100: 4.0: 0.6, namely negative electrode substrate powder;
3) preparing a primary precursor material, transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneader, kneading for 3 hours at normal temperature until the material is in a uniform and particle-free slurry state, heating kneader oil to 180 ℃, evaporating the solvent in the slurry to dryness, wherein the concentration of the prepared sodium carboxymethylcellulose (CMC) aqueous solution is 1.0%; controlling the mass ratio of the negative electrode base material powder to the aqueous solution of sodium carboxymethylcellulose (CMC) to be 100:70, and obtaining a primary precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), and cooling to obtain a pre-carbonized precursor; step 4) preparing a pre-carbonized precursor material, wherein the low-temperature carbonization treatment is to control the temperature of the low-temperature carbonization treatment to be 550 ℃ under the inert atmosphere and control the heating rate of the low-temperature carbonization treatment to be 2 ℃/min; the continuous heat preservation time is 2 h. Cooling and scattering the mixture and passing the mixture through a 325-mesh screen to obtain a pre-carbonized precursor;
5) preparing a lithium battery negative electrode material, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, heating the material to 200 ℃, slowly pouring tar preheated to be in a liquid state into the high-pressure reaction kettle, and mixing the pre-carbonized precursor and the tar according to the mass ratio of 100:12, keeping the temperature, mixing for 2 hours in an inert atmosphere, stopping stirring, then pressurizing and dipping for 2 hours under the pressure of 1.2Mp, decompressing and cooling, transferring into a roller kiln, heating to 1200 ℃ in the inert atmosphere at the heating speed of 2.5 ℃/min, carrying out high-temperature carbonization treatment, keeping the temperature for 5 hours, and cooling to obtain the crude lithium battery negative electrode material;
6) preparing a lithium ion battery cathode material, scattering the coarse lithium battery cathode material, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material; namely the long-cycle lithium ion battery cathode material product prepared by the preparation method of the low-cost long-cycle lithium ion battery cathode material.
The preparation methods in the following examples are the same as the methods and procedures and technical parameter control disclosed in the above specific embodiments or example 1, unless otherwise specified.
Example 4
The embodiment of the invention selects the resistance material waste as the resistance material grinding powder prepared in the step 1) in the specific embodiment 1, and the resistance material waste is referred to as resistance material
1) Preparing raw material grinding powder, namely the resistance material prepared in the specific example 1, wherein the grain diameter Dmin is 2.0-3.0 mu m, the D50 is 13.0-16.0 mu m, the tap density is 0.87/cm3, the content of a magnetic substance is 0.8ppm, and the graphitization degree is 93.1; namely the resistance material grinding powder
2) Preparing cathode substrate powder, mixing the resistance material grinding powder in the step 1) with furfuryl alcohol resin polymer and boron oxide powder, putting the mixture into a VC mixer, uniformly mixing, controlling the mixing time of the VC mixer to be 2h, and controlling the mass ratio of the raw material grinding powder to the furfuryl alcohol resin polymer and the boron oxide powder to be 100: 4: 0.6, namely negative electrode substrate powder;
3) preparing a primary precursor material, transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneader, kneading for 3 hours at normal temperature until the material is in a uniform and particle-free slurry state, heating kneader oil to 180 ℃, evaporating the solvent in the slurry to dryness, wherein the concentration of the prepared sodium carboxymethylcellulose (CMC) aqueous solution is 1.0%; controlling the mass ratio of the negative electrode base material powder to the aqueous solution of sodium carboxymethylcellulose (CMC) to be 100:80, namely obtaining a primary precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), and cooling to obtain a pre-carbonized precursor; step 4) preparing a pre-carbonized precursor material, wherein the low-temperature carbonization treatment is to control the temperature of the low-temperature carbonization treatment to be 500 ℃ under the inert atmosphere and control the heating rate of the low-temperature carbonization treatment to be 2 ℃/min; the continuous heat preservation time is 2 h. Cooling and scattering the mixture and passing the mixture through a 325-mesh screen to obtain a pre-carbonized precursor;
5) preparing a lithium battery negative electrode material, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, heating the material to 200 ℃, slowly pouring tar preheated to be in a liquid state into the high-pressure reaction kettle, and mixing the pre-carbonized precursor and the tar according to the mass ratio of 100:4, keeping the temperature, mixing for 2 hours in an inert atmosphere, stopping stirring, then pressurizing and dipping for 2 hours under the pressure of 1.0Mp, decompressing and cooling, transferring into a roller kiln, heating to 1150 ℃ in the inert atmosphere at the heating speed of 2 ℃/min, carrying out high-temperature carbonization treatment, keeping the temperature for 5 hours, and cooling to obtain the crude lithium battery cathode material;
6) preparing a lithium ion battery cathode material, scattering the coarse lithium battery cathode material, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material; namely the long-cycle lithium ion battery cathode material product prepared by the preparation method of the low-cost long-cycle lithium ion battery cathode material.
Example 5
The embodiment of the invention selects the resistance material waste as the electrode material grinding powder prepared by the step 1) in the specific embodiment 2, and the electrode material grinding powder is hereinafter referred to as electrode material
1) Preparing raw material grinding powder, namely the resistance material prepared in the specific example 2, wherein the grain diameter Dmin is 1.5-2.5 mu m, the D50 is 11.0-14.0 mu m, the tap density is 0.85/cm3, the content of a magnetic substance is 0.3ppm, and the graphitization degree is 92.3; namely the resistance material grinding powder
2) Preparing cathode substrate powder, mixing the resistance material grinding powder in the step 1), furan resin polymer and boric acid powder, putting the mixture into a VC mixer, uniformly mixing, controlling the mixing time of the VC mixer to be 2h, and controlling the mass ratio of the raw material grinding powder to the furfuryl alcohol resin polymer and the boric acid powder to be 100: 3.5: 0.3, namely negative electrode substrate powder;
3) preparing a primary precursor material, transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneader, kneading for 3 hours at normal temperature until the material is in a uniform and particle-free slurry state, heating kneader oil to 180 ℃, evaporating the solvent in the slurry to dryness, wherein the concentration of the prepared sodium carboxymethylcellulose (CMC) aqueous solution is 1.0%; controlling the mass ratio of the negative electrode base material powder to the aqueous solution of sodium carboxymethylcellulose (CMC) to be 100:80, namely obtaining a primary precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), and cooling to obtain a pre-carbonized precursor; step 4) preparing a pre-carbonized precursor material, wherein the low-temperature carbonization treatment is to control the temperature of the low-temperature carbonization treatment to be 500 ℃ under the inert atmosphere and control the heating rate of the low-temperature carbonization treatment to be 2 ℃/min; the continuous heat preservation time is 2 h. Cooling and scattering the mixture and passing the mixture through a 325-mesh screen to obtain a pre-carbonized precursor;
5) preparing a lithium battery negative electrode material, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, heating the material to 200 ℃, slowly pouring tar preheated to be in a liquid state into the high-pressure reaction kettle, and mixing the pre-carbonized precursor and the tar according to the mass ratio of 100:4, keeping the temperature, mixing for 2 hours in an inert atmosphere, stopping stirring, then pressurizing and dipping for 2 hours under the pressure of 0.8Mp, decompressing and cooling, transferring into a roller kiln, heating to 1150 ℃ in the inert atmosphere at the heating speed of 2 ℃/min, carrying out high-temperature carbonization treatment, keeping the temperature for 5 hours, and cooling to obtain the crude lithium battery cathode material;
6) preparing a lithium ion battery cathode material, scattering the coarse lithium battery cathode material, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material; namely the long-cycle lithium ion battery cathode material product prepared by the preparation method of the low-cost long-cycle lithium ion battery cathode material.
Comparative example 1
Comparative example 1 the same raw material as in example 1 was used according to a conventional method, which was coated with asphalt, except that; meanwhile, the direct coating high-temperature asphalt is adopted for high-temperature carbonization, and the total carbon content of the coating agent in the comparative example 1 is the same as that of the coating agent in the example 1; the specific process is as follows:
1) uniformly mixing the resistance material obtained in the example 1 and the mixed asphalt of the high-temperature asphalt according to the mass ratio of 100: 3.5; 2) heating the resistance material in the step (1) to 1200 ℃ at a heating rate of 2.5 ℃/min in an inert atmosphere, and carrying out high-temperature carbonization treatment for 5 hours;
5) and cooling, scattering, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material.
Comparative example 2
Comparative example 2 coating with asphalt was carried out according to a conventional method using the same raw materials as example 2 except that: the material obtained after the step (3) of the example 2 is directly coated with the medium-temperature asphalt for high-temperature carbonization, and the total carbon content of the coating agent of the comparative example 2 is the same as that of the coating agent of the example 2. The specific process is as follows:
1) uniformly mixing the shaped electrode material in the embodiment 2 with the medium-temperature mixed asphalt according to the mass ratio of 100: 4.5;
2) raising the temperature of the electrode material in the step (1) to 1200 ℃ at a temperature raising speed of 2.5 ℃/min in an inert atmosphere, and carrying out high-temperature carbonization treatment for 5 hours; 5) and cooling, scattering, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material.
Comparative example 3
Comparative example 3 coating with bitumen was carried out according to the conventional method using the same raw materials as in example 3, except that: the material obtained after the step (3) of the example 3 is directly coated with the medium-temperature asphalt for high-temperature carbonization, and the total carbon content of the coating agent of the comparative example 3 is the same as that of the coating agent of the example 3. The specific process is as follows:
1) uniformly mixing the shaped crucible material in the embodiment 3 with high-temperature asphalt according to the mass ratio of 100: 4;
2) raising the temperature of the electrode material in the step (1) to 1150 ℃ at a temperature raising speed of 4 ℃/min in an inert atmosphere, and carrying out high-temperature carbonization treatment for 5 hours;
5) and cooling, scattering, sieving with a 325-mesh sieve, and sieving to obtain the lithium ion battery cathode material.
The results of the examples of the present invention and the comparative examples show that in Table 1, although the raw materials used in the comparative examples and the raw materials used in the present invention are the same, the performance requirements after the raw materials are different, for example, the ash content of the coarsely crushed raw material powder of the present invention is not more than 0.40 Wt%, the magnetic substance content is not more than 1.0-5.0ppm, and the electrical resistance of the raw material powder is not more than 130m Ω; whereas none of the comparative examples was treated. Other different comparative examples and examples have been described.
The graphite negative electrode materials prepared in the examples and the comparative examples were subjected to a physical and electrochemical property test, and the obtained physical and electrochemical properties are shown in table 1:
table 1 shows the physical and electrochemical performance results of the prepared graphite cathode material, namely the long-cycle lithium ion battery cathode material prepared by the method of the invention is compared with the lithium battery cathode material prepared by the comparative example and the prior art,
table 1;
description of the drawings: the same raw materials were used for example 1 and comparative example 1, example 2 and comparative example 2, and example 3 and comparative example 3, respectively. The technical scheme provided by the invention is adopted, the conventional technical scheme is adopted for the comparative example, the same raw materials are coated by adopting the scheme provided by the invention, and all indexes are improved compared with the conventional technical route.
As the invention is subjected to the processes of demagnetization treatment and the like, the capacity is improved to a certain extent and the coulombic efficiency is improved for the first time compared with the comparative examples 1 and 2, namely, the embodiment 1 and the embodiment 2 are improved for the reduction of the specific surface area. This is because the larger specific surface area of the comparative example consumes more electrolyte and lithium ions, resulting in a lower coulombic efficiency for the first time, and further, in the 1000-cycle capacity retention rate experiment under the 1C charge-discharge condition, examples 1 and 2 are slightly better than the comparative example.
The method takes waste materials such as scrapped resistance materials, crucible crushed materials, electrode crushed materials and the like generated in the graphitization processing process as materials, optimizes the materials from the material selection stage, improves the particle appearance through rough crushing, shaping and magnetization, and can modify the particle surface by introducing resin polymers to form a hard carbon coating layer, repair the particle surface appearance, improve the tap density of the particles and reduce the specific surface area; the doping of boron is introduced, the surface defects of the cathode substrate are further reduced through the catalytic action of boron, and the specific surface area of the material is further reduced through the composite reaction of boron and the surface of the cathode substrate, so that the high-temperature and low-temperature performance is obviously improved. According to the invention, liquid tar is selected as a secondary coating soft carbon material, the carbon residue value of the tar is lower than that of the traditional coating asphalt, so that a thinner coating layer can be formed, the formed coating layer can be more uniform by using the tar as a coating agent, and the structural stability and the cyclicity of the obtained composite graphite cathode material are greatly improved under the combined action of the hard carbon coated at one time and the boron doping agent. From SEM picture, it can be seen that the surface defect of the material is repaired, the burr is reduced, the porosity is reduced, and the material is improved in high capacity; because the material does not need to be graphitized, the production cost is greatly reduced. The method has ultrahigh cost performance for the field of energy storage batteries which need low cost, high cycle and high stability.
The above embodiments are merely illustrative of the present invention, and are not intended to limit the present invention, and other experimental results achieved by the claims or similar features of the present invention are included in the present invention. The battery is subjected to a multiplying power charge-discharge cycle test, and the cycle capacity retention rate of the battery is shown in a curve figure 3.
Claims (9)
1. A preparation method of a long-cycle lithium ion battery cathode material is characterized by taking waste graphitizing auxiliary materials as raw materials, processing the raw materials to obtain graphite powder, doping the graphite powder with boron, and coating the graphite powder twice, and comprises the following steps:
1) preparing a raw material grinding material, namely processing the waste graphitized auxiliary material into the raw material grinding material with certain particle size and tap density through the procedures of coarse crushing, shaping, grading and demagnetizing;
2) preparing cathode base material powder, namely mixing the raw material powder grinding material in the step 1) with a resin polymer and a boron doping agent, and putting the mixture into a VC mixer to be uniformly mixed to obtain cathode base material powder;
3) preparing a precursor material, namely transferring the negative electrode base material powder prepared in the step 2) and a sodium carboxymethylcellulose (CMC) aqueous solution into a kneading machine to be stirred and mixed, kneading at normal temperature until the material is in a uniform and particle-free slurry state, and then increasing the oil temperature of the kneading machine to heat and evaporate the solvent in the slurry to dryness to obtain the precursor material;
4) preparing a pre-carbonized precursor, namely performing low-temperature pre-carbonization treatment on the precursor material obtained in the step 3), cooling, scattering the obtained lump material, and screening to obtain the pre-carbonized precursor;
5) preparing a coarse lithium battery cathode material, namely putting the pre-carbonized precursor obtained in the step 4) into a high-pressure reaction kettle, continuously stirring, heating the material to a certain temperature, slowly pouring tar preheated to a liquid state into the high-pressure reaction kettle, keeping the temperature, uniformly mixing in an inert atmosphere, stopping stirring, then pressurizing and dipping under the condition of pressure, decompressing and cooling, transferring into a roller kiln, and performing high-temperature secondary carbonization treatment, and cooling to obtain the coarse lithium battery cathode material;
6) preparing a lithium ion battery cathode material, scattering the coarse lithium battery cathode material obtained in the step 5), and sieving to obtain the lithium ion battery cathode material.
2. The preparation method of the long-cycle lithium ion battery anode material as claimed in claim 1, wherein the step 1) is to perform coarse crushing treatment by using a roller jaw crushing integrated machine device, the particle size of coarse crushed granules is controlled to be less than or equal to 2mm, and the graphitization degree is controlled to be greater than or equal to 91.
3. The preparation method of the long-cycle lithium ion battery negative electrode material as claimed in claim 1, wherein the grinding, shaping and grading processes in step 1) are carried out by a grinding and shaping machine, coarse broken particles are further crushed and shaped, and fine powder is removed by a combined grading device to obtain raw material grinding powder meeting the requirements; controlling the median particle diameter of the raw material powder to D503.0-30.0 μm, tap density of 0.70-1.055g/cm3。
4. The preparation method of the long-cycle lithium ion battery negative electrode material according to claim 1, characterized in that the demagnetization process in step 1) is current demagnetization or permanent magnet demagnetization, the demagnetization equipment is connected with a horizontal or vertical mixing and screening machine to ensure the uniformity of the material after the demagnetization is completed, and the content of magnetic substances in the ground material of the demagnetized raw material is controlled to be less than or equal to 5.0 ppm.
5. The preparation method of the negative electrode material of the long-cycle lithium ion battery according to claim 1, wherein the preparation of the negative electrode substrate powder in the step 2) is that the raw material ground powder in the step 1) is mixed with the resin polymer and the boron-doped agent and is put into a VC mixer to be uniformly mixed to obtain the negative electrode substrate powder; controlling the mass ratio of the raw material grinding powder to the resin polymer and the boron-doped agent to be 100: 1-20: 0.1-2, and controlling the mass concentration of the aqueous solution of sodium carboxymethylcellulose (CMC) to be 0.1-3.5 Wt%; the mass ratio of the raw material grinding powder to the aqueous solution of sodium carboxymethylcellulose (CMC) is controlled to be 100: 20-200.
6. The preparation method of the long-cycle lithium ion battery negative electrode material as claimed in claim 1 or 5, characterized in that the precursor material in step 3) is prepared by controlling the heating temperature of the kneading device to be 100-250 ℃ and the kneading, stirring and mixing time to be 1-6 hours.
7. The preparation method of the long-cycle lithium ion battery negative electrode material as claimed in claim 1, wherein the preparation method of the long-cycle lithium ion battery negative electrode material is characterized in that in the step 4), the pre-carbonization precursor material is prepared, the temperature of the primary pre-carbonization treatment is controlled to be 480-680 ℃ under the inert atmosphere, and the temperature rise rate of the low-temperature pre-carbonization treatment is controlled to be 1-8 ℃/min; the low-temperature carbonization treatment and the heat preservation time are controlled to be 5-18 h.
8. The preparation method of the long-cycle lithium ion battery anode material according to claim 1, the method is characterized in that step 5) of preparing the cathode material of the crude lithium battery is to put the pre-carbonized precursor material obtained in step 4) into a high-pressure reaction kettle and heat the material to 80-300 ℃, slowly pouring the tar preheated to liquid state into a high-pressure reaction kettle, keeping the temperature, uniformly mixing in an inert atmosphere, stopping stirring, pressurizing and dipping for 0.5-3 h under the pressure of 0.2-1.5Mp, transferring into a roller kiln after pressure relief and cooling, then heating the roller kiln to 950-1200 ℃ in inert atmosphere at the heating rate of 1-7 ℃/min to carry out high-temperature secondary carbonization treatment, controlling the high-temperature secondary carbonization and heat preservation time to be 12-24 h, the tar is coal tar or petroleum tar, the coking value of the tar is 20-30%, and the crude lithium battery negative electrode material is obtained after cooling.
9. The method for preparing a long-cycle lithium ion battery negative electrode material according to claim 1 or 2, characterized in that the coarsely crushed raw material powder is controlled to have a moisture content of 0.50 Wt% or less, an ash content of 0.40 Wt% or less, a magnetic substance content of 1.0-5.0ppm or less, and a resistance of 130m Ω or less.
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