CN110828824B - Long-life natural graphite negative electrode material and preparation method thereof - Google Patents
Long-life natural graphite negative electrode material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a preparation method of a long-life natural graphite cathode material, which adopts a natural graphite raw material, and carries out densification treatment on the natural graphite raw material to obtain blocky graphite; then, carrying out ultrahigh-temperature treatment on the blocky graphite in a heating furnace to obtain an ultrahigh-temperature precursor; the ultra-high temperature precursor is broken in a breaking device to obtain a broken precursor; and fully mixing the shattered precursor with a coating agent, then carbonizing in a kiln, and finally screening and demagnetizing to obtain the natural graphite cathode material with the particle surface coated with the low-crystallinity amorphous carbon. The natural graphite cathode material prepared by the method has the advantages of good cycle performance, good low-temperature rate capability, low production cost and the like.
Description
Technical Field
The invention relates to a carbon material and a preparation method thereof, in particular to a lithium ion battery cathode material and a preparation method thereof.
Background
The natural graphite is one of the most commonly used cathode materials in the lithium ion battery industry, and has the advantages of high crystallization degree, high specific capacity, high compaction density, good processing performance and the like; as higher and higher requirements are provided for the cycle life of the cathode material in the fields of consumer electronics, energy storage and power batteries, the cycle life under normal temperature and high temperature conditions is generally required to be prolonged; natural graphite has poor cycle life, especially high temperature cycle life, due to more pores and defects inside the particles; therefore, the natural graphite needs to be specially treated, so that the internal defects are reduced, and the cycle life is prolonged.
In order to overcome the defects of the natural graphite cathode material, people generally adopt methods of raw material pretreatment, particle surface modification, particle modification and high-temperature heat treatment to further improve the electrochemical performance, and most researches are carried out on the surface coating treatment of the natural graphite. Market placeIn order to improve the cycle performance, the above natural graphite negative electrode material is usually subjected to pretreatment, and the surface of particles is coated with amorphous carbon or artificial graphite; based on the existing research thought and preparation method, the two targets of reducing the internal pores of the particles and reducing the defects of the particles are difficult to be considered simultaneously; the existence of pores and particle defects inside the particles enables the negative electrode material to easily generate side reaction with the electrolyte, and particularly, the cycle life is finally attenuated or the water jumps are caused under the high-temperature condition; the internal pores of the particles can be characterized by adopting the total volume of the mesopores (BJH method), the particle defects can be characterized by adopting Raman spectrum, the D peak of the Raman spectrum represents the defects of crystal lattices, and the I representsD/IGThe proportion of lattice defects can be characterized; while cycle life is improved, it is necessary to ensure that the low temperature performance and rate capability of the material are not adversely affected, and manufacturing costs are also taken into account.
Patent document CN200510034330 discloses a preparation method of a natural graphite cathode material, which comprises the steps of fully mixing spherical natural graphite and a carbon material precursor, and then heating to 600-. The method has the advantages of simple process, more pores and defects in the particles, and incapability of solving the problem of poor cycle performance, especially high-temperature cycle.
Patent document CN201210516768 discloses a preparation method of a natural graphite negative electrode material, which comprises the steps of pretreating spherical natural graphite at the temperature of 500-600 ℃, then uniformly mixing the spherical natural graphite with a catalyst and asphalt, and finally performing catalytic graphitization high-temperature treatment to prepare modified natural graphite with a core-shell structure and a surface coated with high-crystallinity artificial graphite. The natural graphite prepared by the method has higher gram capacity, but more pores are still arranged in the particles, and the improvement of the cycle performance is limited; meanwhile, the crystallization degree of the particle coating layer is high, so that the low-temperature and rate performance is poor.
Patent document CN201610851984 discloses a preparation method of a high-rate natural graphite cathode material, which comprises the steps of uniformly mixing spherical natural graphite with a catalyst and a binder, heating, kneading, hot isostatic pressing, and finally performing catalytic graphitization high-temperature treatment to prepare modified natural graphite with a core-shell structure and a surface coated with high-crystallinity artificial graphite. The natural graphite prepared by the method has high gram capacity, but the high-temperature cycle performance is negatively influenced due to the large use of the adhesive; meanwhile, the crystallization degree of the particle coating layer is high, so that the low-temperature and rate performance is poor.
Patent document CN201710186011 discloses a preparation method of a high-capacity natural graphite negative electrode material, which comprises shaping flake graphite, mixing with coal tar or petroleum tar for the first time, performing heat treatment, graphitizing, mixing with petroleum pitch or coal pitch for the second time, and finally performing carbonization heat treatment to prepare modified natural graphite with a core-shell structure and surface coated with amorphous carbon. The natural graphite prepared by the method has more working procedures, so that the manufacturing cost is higher; the tar and the asphalt are used for a large amount of times, which is not beneficial to improving the high-temperature cycle performance; the pores inside the particles are still more and the improvement of the cycle performance is limited.
Patent document CN201711330054 discloses a preparation method of a natural graphite-based modified composite material, which comprises isotropizing spherical natural graphite, controlling particle size, shaping, mixing with a modifier, and finally carbonizing to prepare the modified natural graphite with good cycle performance and low expansion. The natural graphite prepared by the method can effectively reduce the pores in the particles through isotropic treatment, but the particle defects cannot be reduced remarkably only through mixing with a modifier and then carbonizing; in practice, the cycle performance is difficult to be improved to an optimum level, particularly the high-temperature cycle performance.
From the present situation, none of the prior art achieves satisfactory results from an industrialization point of view, can not simultaneously consider the two objectives of reducing the internal porosity of the particles and reducing the defects of the particles, and does not improve the cycle life to an optimum level; some technical routes have certain negative effects on low-temperature performance and rate performance, and some technical routes have complex processes and higher production cost.
Disclosure of Invention
The invention aims to solve the problems in the background art and provides a preparation method of a natural graphite negative electrode material with long service life.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a long-life natural graphite negative electrode material comprises the following steps:
s1, carrying out densification treatment on the natural graphite raw material, wherein no adhesive is required to be added in the densification treatment process, no mixing or kneading treatment is required, and the bulk density of the natural graphite raw material is 1.2-1.8 cm after the densification treatment3-block graphite per gram;
s2, subjecting the blocky graphite obtained in the step 1 to ultrahigh temperature treatment in a heating furnace, wherein the temperature range of the ultrahigh temperature treatment is 1800-3300 ℃, and thus obtaining an ultrahigh temperature precursor;
s3, crushing the ultrahigh-temperature precursor obtained in the step 2 to a certain particle size specification in crushing equipment to obtain a crushed precursor;
s4, fully mixing the disintegrated precursor obtained in the step 3 with a coating agent to form a mixture; wherein the mass of the coating agent is 5-15% of the mass of the whole mixture; then carbonizing the mixture in a kiln at 800-1350 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite negative electrode material with the particle surface coated with the low-crystallinity amorphous carbon.
Preferably, in the step S1, the natural graphite raw material is one or more of flake natural graphite or spherical natural graphite, and the particle size of the natural graphite raw material is 6-20 um.
Preferably, in step S1, the densifying process is performed by using one of an isostatic pressing machine, a compression molding machine, an extrusion molding machine, and a vibration molding machine, and the working pressure is 50 to 150 Mpa.
Preferably, in step S2, the block ultra-high temperature treatment is performed by using a heating furnace, and the heating furnace is one of an acheson graphitization furnace, an inner-series graphitization furnace, a box graphitization furnace, a direct current high temperature electric calcining furnace, and a medium frequency induction heating furnace.
Preferably, step (a)In step S2, Raman spectrum I of the ultra-high temperature precursorD/IG≤0.10。
Preferably, in step S3, the disintegration apparatus is one of a universal pulverizer, an impact mill, a roller mill, a rotary wheel mill or other mechanical coarse disintegration apparatuses, and the particle size diameter of the disintegration precursor is 8-20 um.
Preferably, in step S4, the coating agent is one or more of petroleum asphalt, coal asphalt, resin or other hydrocarbons.
Preferably, in step S4, the kiln is one of a box furnace, a pusher kiln, a roller kiln, and a rotary furnace.
The long-life natural graphite negative electrode material is characterized in that: the long-life natural graphite cathode material is prepared by the preparation method of the long-life natural graphite cathode material as claimed in any one of claims 1 to 8, wherein the average particle size of the graphite cathode material is 8-20 microns, and the tap density is more than or equal to 1.0cm3Per g, specific surface area less than or equal to 3.0m2G, gram capacity is more than or equal to 360mAh/g, primary efficiency is more than or equal to 92 percent, and the volume of total mesoporous pores of the BJH method is less than or equal to 8.0 x 10-3cm3G, Raman Spectroscopy ID/IGLess than or equal to 0.15, capacity retention rate of 1500 circles in 1C/1C circulation at 25 ℃ is more than or equal to 80 percent, capacity retention rate of 800 circles in 1C/1C circulation at 45 ℃ is more than or equal to 80 percent, and DCR at low temperature of 0.3C at minus 20 ℃ is less than or equal to 500m omega.
The invention has the following beneficial effects:
the natural graphite raw material is adopted, the densification treatment is directly carried out, no adhesive is added, no mixing or kneading treatment is needed, and the process is simple; the densification treatment can effectively reduce the internal pores of the particles, which is particularly characterized in that the total pore volume of the particles is obviously reduced, and the tap density of the particles is obviously increased. After the densification treatment, the block ultrahigh temperature treatment is carried out, and the advantage of the block ultrahigh temperature treatment is that the charging density is high, thereby being beneficial to reducing the production cost; the ultrahigh temperature treatment can effectively reduce particle defects, and is particularly characterized in that the Raman spectrum ID/IG is obviously reduced. After the block-shaped ultrahigh temperature treatment, the surface of the particles is coated with the amorphous carbon, so that the low-temperature rate performance of the material can be ensured, the normal-temperature cycle life and the high-temperature cycle life are improved, and the defects of unobvious cycle life improvement, negative influence on the low-temperature rate performance, high production cost and the like in the prior art are overcome.
The graphite cathode material prepared by the method has the advantage of long service life, and is good in low-temperature rate capability, low in production cost and easy to realize large-scale mass production. The gram capacity of the graphite cathode material prepared by the method is more than or equal to 360mAh/g, the primary efficiency is more than or equal to 92%, and the total pore volume of the mesoporous prepared by the BJH method is less than or equal to 8.0 x 10-3cm3The Raman spectrum ID/IG is less than or equal to 0.15, the capacity retention rate of 1500 cycles at 25 ℃ and 1C/1C is more than or equal to 80 percent, the capacity retention rate of 800 cycles at 45 ℃ and 1C/1C is more than or equal to 80 percent, and the DCR at-20 ℃ and 0.3C is less than or equal to 500m omega.
Drawings
FIG. 1 is a scanning electron microscope image of the graphite cathode material prepared by the method of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.
Example 1
Adopting spherical natural graphite with the average grain diameter of 10um to carry out densification treatment in an isostatic pressing forming machine, setting the working pressure of the isostatic pressing forming machine to be 100MPa, and obtaining the volume density of 1.5cm3Block graphite per gram. And carrying out ultrahigh-temperature treatment on the blocky graphite in an Acheson graphitizing furnace at the working temperature of 3000 ℃ to obtain an ultrahigh-temperature precursor, wherein the Raman spectrum ID/IG of the ultrahigh-temperature precursor is 0.06. And (3) crushing the ultrahigh-temperature precursor in an impact mill to obtain the material with the average particle size of 11 um. Uniformly mixing the shatter precursor with petroleum asphalt in a mixing mass ratio of 90: 10; then carbonizing in a pushed slab kiln at the carbonization temperature of 1000 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite cathode material. Weighing 50g of the sample, mixing the sample powder, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) in a mass ratio of 96:2:2 to prepare a pole piece, drying the pole piece in vacuum to be used as a negative pole, using a metal lithium piece as a positive pole, and measuring the first discharge capacity of 361.2mAh/g in a 0.1C charge-discharge test, wherein the first discharge capacity is maintained in a ternary system at 25 ℃ and 1C/1C circulation capacity of 1500 circlesThe rate is 84.5 percent, and the capacity retention rate of the ternary system at 25 ℃ and 1C/1C cycle is 800 circles is 82.6 percent.
Example 2
The scale natural graphite with the average grain diameter of 10um is adopted to be processed in a compression molding machine for densification, the working pressure of the compression molding machine is 80MPa, and the volume density is 1.4cm3Block graphite per gram. And carrying out ultrahigh-temperature treatment on the blocky graphite in an inner-series graphitization furnace at the working temperature of 2800 ℃ to obtain an ultrahigh-temperature precursor, wherein the Raman spectrum ID/IG of the ultrahigh-temperature precursor is 0.07. And (3) crushing the ultrahigh-temperature precursor in a rolling mill to obtain the material with the average particle size of 11 um. Uniformly mixing the shatter precursor with petroleum asphalt in a mixing mass ratio of 85: 15; then carbonizing in a roller kiln at 1050 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite cathode material. Weighing 50g of the sample, mixing the sample powder, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) according to a mass ratio of 96:2:2 to prepare a pole piece, performing vacuum drying to obtain a negative pole, using a metal lithium piece as a positive pole, wherein the first discharge capacity of a 0.1C charge-discharge test is 360.5mAh/g, the capacity retention rate of a ternary system is 83.2 percent at 25 ℃ and 1C/1C circulation cycles of 1500, and the capacity retention rate of the ternary system is 81.8 percent at 25 ℃ and 1C/1C circulation cycles of 800.
Example 3
Spherical natural graphite with the average grain diameter of 16 mu m is adopted to be densified in an isostatic pressing machine, the working pressure of the isostatic pressing machine is 150MPa, and the volume density is 1.8cm3Block graphite per gram. And carrying out ultrahigh-temperature treatment on the blocky graphite in an Acheson graphitizing furnace at the working temperature of 3300 ℃ to obtain an ultrahigh-temperature precursor, wherein the Raman spectrum ID/IG of the ultrahigh-temperature precursor is 0.04. And (3) crushing the ultrahigh-temperature precursor in an impact mill to obtain the material with the average particle size of 17 um. Uniformly mixing the shatter precursor with petroleum asphalt in a mixing mass ratio of 95: 5; then carbonizing in a roller kiln at 1200 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite cathode material. Weighing 50g of the sample, mixing the sample powder, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) in a mass ratio of 96:2:2 to prepare the sampleThe sheet is used as a negative electrode after vacuum drying, the metal lithium sheet is used as a positive electrode, the first discharge capacity is 368.4mAh/g in a 0.1C charge-discharge test, the capacity retention rate of a ternary system is 87.8 percent at 25 ℃ and 1C/1C circulation for 1500 circles, and the capacity retention rate of the ternary system at 25 ℃ and 1C/1C circulation for 800 circles is 85.4 percent.
Example 4
Spherical natural graphite with the average grain diameter of 16um is adopted to be subjected to densification treatment in an isostatic pressing machine, the working pressure of the isostatic pressing machine is 120MPa, and the volume density is 1.7cm3Block graphite per gram. And carrying out ultrahigh-temperature treatment on the blocky graphite in a box-type graphitization furnace at the working temperature of 3000 ℃ to obtain an ultrahigh-temperature precursor, wherein the Raman spectrum ID/IG of the ultrahigh-temperature precursor is 0.05. And (3) crushing the ultrahigh-temperature precursor in an impact mill to obtain the material with the average particle size of 17 um. Uniformly mixing the shatter precursor with petroleum asphalt in a mixing mass ratio of 92: 8; then carbonizing in a roller kiln at 1150 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite cathode material. Weighing 50g of the sample, mixing the sample powder, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) according to a mass ratio of 96:2:2 to prepare a pole piece, performing vacuum drying to obtain a negative pole, using a metal lithium piece as a positive pole, and performing 0.1C charge-discharge test to obtain a first discharge capacity of 365.1mAh/g, wherein the capacity retention rate of a ternary system at 25 ℃ and 1C/1C circulation cycles of 1500 circles is 88.4%, and the capacity retention rate of the ternary system at 25 ℃ and 1C/1C circulation cycles of 800 circles is 84.1%.
Example 5
Adopts spherical natural graphite with the average grain diameter of 16um to carry out densification treatment in an extrusion forming machine, and the working pressure of an isostatic pressing forming machine is 80MPa, so as to obtain the graphite with the volume density of 1.6cm3Block graphite per gram. And carrying out ultrahigh-temperature treatment on the blocky graphite in a direct-current high-temperature electric calcining furnace at the working temperature of 2500 ℃ to obtain an ultrahigh-temperature precursor, wherein the Raman spectrum ID/IG of the ultrahigh-temperature precursor is 0.08. And (3) crushing the ultrahigh-temperature precursor in an impact mill to obtain the material with the average particle size of 17 um. Uniformly mixing the shatter precursor with the coal pitch, wherein the mixing mass ratio is 92: 8; then carbonizing in a roller kiln at 1100 ℃ to obtain a carbon-coated product; screening and demagnetizing of carbon-coated productAnd then, obtaining the natural graphite negative electrode material. Weighing 50g of the sample, mixing the sample powder, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) according to a mass ratio of 96:2:2 to prepare a pole piece, performing vacuum drying to obtain a negative pole, using a metal lithium piece as a positive pole, and performing 0.1C charge-discharge test to obtain a first discharge capacity of 364.3mAh/g, wherein the capacity retention rate of a ternary system at 25 ℃ and 1C/1C circulation cycles of 1500 circles is 89.3%, and the capacity retention rate of the ternary system at 25 ℃ and 1C/1C circulation cycles of 800 circles is 83.7%.
Comparative example 1
The densification and disintegration processes were eliminated on the basis of example 1. Spherical natural graphite with the average particle size of 10 mu m is adopted to be subjected to ultra-high temperature treatment in an Acheson graphitizing furnace at the working temperature of 3000 ℃ to obtain an ultra-high temperature precursor, and the Raman spectrum ID/IG of the ultra-high temperature precursor is 0.06. Uniformly mixing the ultrahigh-temperature precursor with petroleum asphalt in a mixing mass ratio of 90: 10; then carbonizing in a pushed slab kiln at the carbonization temperature of 1000 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite cathode material. Weighing 50g of the sample, mixing the sample powder, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) according to a mass ratio of 96:2:2 to prepare a pole piece, performing vacuum drying to obtain a negative pole, using a metal lithium piece as a positive pole, and performing a 0.1C charge-discharge test to obtain a first discharge capacity of 360.1mAh/g, wherein the capacity retention rate of a ternary system at 25 ℃ and 1C/1C circulation 1500 circles is 75.6%, and the capacity retention rate of the ternary system at 25 ℃ and 1C/1C circulation 800 circles is 72.3%.
Comparative example 2
The ultra-high temperature process was removed on the basis of example 1. Spherical natural graphite with the average grain diameter of 10um is adopted to be subjected to densification treatment in an isostatic pressing machine, the working pressure of the isostatic pressing machine is 100MPa, and the volume density is 1.5cm3Block graphite per gram. The block graphite is disintegrated in an impact mill, and the average grain diameter of the obtained material is 11 um. Uniformly mixing the shatter precursor with petroleum asphalt in a mixing mass ratio of 90: 10; then carbonizing in a pushed slab kiln at the carbonization temperature of 1000 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite cathode material. Weighing 50g of the sample, mixing the sample powder with carboxymethyl cellulose (A), (B), (C)CMC) and Styrene Butadiene Rubber (SBR) are mixed according to the mass ratio of 96:2:2 to prepare a pole piece, the pole piece is used as a negative pole after vacuum drying, a metal lithium piece is used as a positive pole, the first discharge capacity is 357.6mAh/g in a 0.1C charge-discharge test, the capacity retention rate of a ternary system is 76.7 percent at 25 ℃ and 1C/1C circulation at 1500 cycles, and the capacity retention rate of the ternary system at 25 ℃ and 1C/1C circulation at 800 cycles is 73.2 percent.
Performance testing
First, the powder indexes of the graphite negative electrode materials prepared in the above examples and comparative examples are shown in table 1 below:
TABLE 1
Secondly, the graphite negative electrode materials prepared in the above examples and comparative examples are made into battery negative electrode sheets, and electrochemical tests are performed, wherein the performances of the battery negative electrode sheets are shown in table 2:
TABLE 2
As can be seen from tables 1 and 2, the gram capacity of the graphite cathode material prepared by the method is more than or equal to 360mAh/g, the primary efficiency is more than or equal to 92%, and the total pore volume of the mesoporous prepared by the BJH method is less than or equal to 8.0 x 10-3cm3The Raman spectrum ID/IG is less than or equal to 0.15, the capacity retention rate of 1500 cycles at 25 ℃ and 1C/1C is more than or equal to 80 percent, the capacity retention rate of 800 cycles at 45 ℃ and 1C/1C is more than or equal to 80 percent, and the DCR at-20 ℃ and 0.3C is less than or equal to 500m omega. The product of the invention has the advantages of long cycle life, good low-temperature rate capability and low production cost.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (9)
1. The preparation method of the natural graphite negative electrode material with the long service life is characterized by comprising the following steps:
s1, carrying out densification treatment on one or more of crystalline flake natural graphite or spherical natural graphite by using any one of an isostatic pressing forming machine, a compression molding machine, an extrusion molding machine and a vibration forming machine, wherein no adhesive is added in the densification treatment process, no mixing or kneading treatment is needed, and the bulk density is obtained after the densification treatment of 1.2-1.8 cm3-block graphite per gram;
s2, subjecting the blocky graphite obtained in the step 1 to ultrahigh temperature treatment in a heating furnace, wherein the temperature range of the ultrahigh temperature treatment is 1800-3300 ℃, and thus obtaining an ultrahigh temperature precursor;
s3, crushing the ultrahigh-temperature precursor obtained in the step 2 to a certain particle size specification in crushing equipment to obtain a crushed precursor;
s4, fully mixing the disintegrated precursor obtained in the step 3 with a coating agent to form a mixture; wherein the mass of the coating agent is 5-15% of the mass of the whole mixture; then carbonizing the mixture in a kiln at 800-1350 ℃ to obtain a carbon-coated product; and (4) screening and demagnetizing the carbon-coated product to obtain the natural graphite negative electrode material with the particle surface coated with the low-crystallinity amorphous carbon.
2. The preparation method of the long-life natural graphite negative electrode material as claimed in claim 1, wherein the preparation method comprises the following steps: in step S1, the particle size of the natural graphite raw material is 6-20 μm.
3. The preparation method of the long-life natural graphite negative electrode material as claimed in claim 1, wherein the preparation method comprises the following steps: the method is characterized in that: in step S1, the working pressure of the densification treatment is 50-150 MPa.
4. The preparation method of the long-life natural graphite negative electrode material as claimed in claim 1, wherein the preparation method comprises the following steps: in step S2, the ultra-high temperature treatment is performed by using a heating furnace, which is one of an acheson graphitization furnace, an inside-string graphitization furnace, a box graphitization furnace, a direct-current high-temperature electric calcining furnace, and a medium-frequency induction heating furnace.
5. The preparation method of the long-life natural graphite negative electrode material as claimed in claim 1, wherein the preparation method comprises the following steps: in step S2, Raman spectrum I of the ultra-high temperature precursorD/IG≤0.10。
6. The preparation method of the long-life natural graphite negative electrode material as claimed in claim 1, wherein the preparation method comprises the following steps: in step S3, the disintegration apparatus is one of a universal pulverizer, an impact mill, a roll mill, a rotary wheel mill or other mechanical coarse disintegration apparatuses, and the particle size of the disintegration precursor is 8 to 20 μm.
7. The preparation method of the long-life natural graphite negative electrode material as claimed in claim 1, wherein the preparation method comprises the following steps: in step S4, the coating agent is one or more of petroleum asphalt, coal asphalt, resin, or hydrocarbon.
8. The preparation method of the long-life natural graphite negative electrode material as claimed in claim 1, wherein the preparation method comprises the following steps: in step S4, the kiln is one of a box furnace, a pusher kiln, a roller kiln, and a rotary furnace.
9. The long-life natural graphite negative electrode material is characterized in that: the long-life natural graphite cathode material is prepared by the preparation method of the long-life natural graphite cathode material as claimed in any one of claims 1 to 8, the average particle size of the graphite cathode material is 8-20 microns, and the tap density is more than or equal to 1.0g/cm3Specific surface area less than or equal to 3.0m2G, gram capacity is more than or equal to 360mAh/g, primary efficiency is more than or equal to 92 percent, and the volume of total mesoporous pores of the BJH method is less than or equal to 8.0 x 10-3cm3G, Raman Spectroscopy ID/IGLess than or equal to 0.15, capacity retention rate of 1500 circles in 1C/1C circulation at 25 ℃ is more than or equal to 80 percent, capacity retention rate of 800 circles in 1C/1C circulation at 45 ℃ is more than or equal to 80 percent, and DCR at low temperature of 0.3C at minus 20 ℃ is less than or equal to 500m omega.
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| CN114223072A (en) | 2020-04-30 | 2022-03-22 | 宁德时代新能源科技股份有限公司 | Negative active material, method of preparing the same, secondary battery, and device including the secondary battery |
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| CN103855395A (en) * | 2012-12-05 | 2014-06-11 | 上海杉杉科技有限公司 | Natural graphite negative electrode material of lithium ion battery and preparation method thereof |
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