CN111620331A - Artificial graphite negative electrode material, preparation method thereof and application thereof in lithium ion battery - Google Patents

Artificial graphite negative electrode material, preparation method thereof and application thereof in lithium ion battery Download PDF

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CN111620331A
CN111620331A CN202010478553.3A CN202010478553A CN111620331A CN 111620331 A CN111620331 A CN 111620331A CN 202010478553 A CN202010478553 A CN 202010478553A CN 111620331 A CN111620331 A CN 111620331A
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petroleum coke
particles
temperature
artificial graphite
stirring
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朱智渊
张伟康
郭孟星
刘范芬
苑丁丁
吕正中
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Hubei Eve Power Co Ltd
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    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
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Abstract

The invention relates to an artificial graphite negative electrode material, a preparation method thereof and application thereof in a lithium ion battery. The method comprises the following steps: (1) mixing petroleum coke particles, resin and a dispersing agent, stirring and heating to obtain petroleum coke secondary particles; (2) mixing the petroleum coke secondary particles with the calcined needle coke particles to obtain an artificial graphite precursor; (3) and carrying out a graphitization process on the artificial graphite precursor to obtain the artificial graphite cathode material. The coating method adopted by the invention has strong repeatability, can be used for continuous production, and has stable and easily controlled process; the graphite cathode material obtained by the invention has the advantages of excellent cycle performance, continuous production, stable and easily controlled process, high production efficiency, stable crystal structure of graphite discharged from a furnace, small specific surface area and the like.

Description

Artificial graphite negative electrode material, preparation method thereof and application thereof in lithium ion battery
Technical Field
The invention belongs to the technical field of battery materials, and particularly relates to an artificial graphite cathode material, a preparation method thereof and application thereof in a lithium ion battery.
Background
In a battery energy storage system, lithium ion batteries are distinguished by the characteristics of high energy density, long cycle life, environmental friendliness and the like. The negative electrode material is a carrier of lithium ions and electrons in the process of charging and discharging of the battery and plays a role in storing and releasing energy. In the cost of the battery, the negative electrode material accounts for 5-15% and is one of the important raw materials of the lithium ion battery, the most widely and mature negative electrode material in commercial application at present is a graphite negative electrode material, and the requirement of the energy storage lithium ion battery on the negative electrode material is long-term stable cycle performance so as to ensure the continuous and stable normal operation of an energy storage system in long-term cycle use. However, due to structural limitation, the graphite negative electrode material has many defects in the actual use process, firstly, the compatibility of graphite and electrolyte is poor, larger irreversible capacity exists, secondly, lithium ions and an organic solvent generate a co-intercalation reaction in a graphite negative electrode layer sheet, and the phenomena of swelling, collapse, particle pulverization and the like of a graphite sheet layer are accelerated by repeated intercalation and side reactions, so that the cycle performance of the graphite negative electrode is reduced. In order to overcome the problems, some domestic graphite cathode manufacturers adopt high-temperature asphalt for modification and coating to solve certain circulation problems, but the rheological property is poor, and the practical application is difficult.
CN107039654A adopts liquid phase coating modification and carbon coating treatment after high-temperature graphitization, and the method can improve the phenomenon of nonuniform coating caused by the conventional coating method to a certain extent, but cannot substantially change the crystal structure of graphite, and later circulation can cause the conditions of collapse of the internal structure of graphite particles and the like.
The CN106495144A is a method for exploring the coating treatment of various raw coke and various coating agents under certain pressure, and some methods in the scheme are actually methods widely applied in the industry at present, but are partially poor in consistency.
CN109935778A generalCoating the mixture by combining the stearic acid and the high-temperature asphalt, and mixing Fe in the later period3O4Although the problem of coating uniformity is solved to a certain extent, the raw material of the petroleum coke is pure petroleum coke, and the petroleum coke has high content of internal volatile components and impurities, and high content of impurities such as nitrogen, sulfur, hydrogen and the like at the later stage, so that the cycle performance is greatly influenced.
CN106848316A coats natural graphite through high-temperature asphalt and phenolic resin modification, and because the natural graphite is a sheet structure, the structure is easy to swell and collapse in the process of graphite charging and discharging, and the graphite structure is damaged, so that the cycle performance is poor due to the rapid capacity attenuation.
Therefore, there is a need in the art to develop a novel graphite anode material having the advantages of excellent cycle performance, easy control of the production process, high production efficiency, etc.
Disclosure of Invention
Aiming at the problem of poor cycle performance of the conventional graphite cathode material in the lithium ion battery industry, the invention aims to provide an artificial graphite cathode material, a preparation method thereof and application thereof in a lithium ion battery. The graphite cathode material has the advantages of excellent cycle performance, continuous production, stable and easily-controlled process, high production efficiency, stable structure of graphite crystal discharged from a furnace, small specific surface area and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
one of the purposes of the invention is to provide a preparation method of an artificial graphite negative electrode material, which comprises the following steps:
(1) mixing petroleum coke particles, resin and a dispersing agent, stirring and heating to obtain petroleum coke secondary particles;
(2) mixing the petroleum coke secondary particles with the calcined needle coke particles to obtain an artificial graphite precursor;
(3) and carrying out a graphitization process on the artificial graphite precursor to obtain the artificial graphite cathode material.
The resin adopted by the invention has high bonding strength and good permeability, not only improves the granulation strength and ensures the structural stability of secondary graphite particles in the later cycle process, but also can modify the internal pore structure of the graphite to ensure that the internal crystal structure cannot collapse due to graphite expansion in the later cycle process, and the coating method has strong repeatability, can be used for continuous production, and has stable and easily controlled process; after the calcined needle coke is calcined at high temperature, the impurity content of the calcined needle coke is extremely low, and the calcined needle coke has a more compact internal structure and fewer internal gaps of particles, so that the side reaction with electrolyte can be reduced, and the cycle performance can be obviously improved; because petroleum coke volatile matter content is higher, can seriously agglomerate in the graphitization process, and secondary particle isotropy is better, OI value is lower, and lithium ion gets into graphite particle passageway more in the cycle process, so secondary particle circulation performance is better, can reduce the volatile matter content in the petroleum coke through the granulation simultaneously, reduces the graphitization in-process caking risk, and needle coke particle after calcining can remedy the not enough defect of petroleum coke circulation and can improve needle coke processability after calcining with the mixing of petroleum coke particle.
Preferably, the petroleum coke particles in step (1) have a particle size of 8-12 μm, such as 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm or 11.5 μm.
The grain size of the selected petroleum coke particles is 8-12 mu m, and the capacity is quickly attenuated due to long-term circulation because the grain size is too small and the edge structure has more defects.
Preferably, the preparation process of the petroleum coke particles in the step (1) comprises the following steps: the petroleum coke is subjected to primary crushing, grinding and grading crushing to obtain petroleum coke particles.
Preferably, the resin of step (1) comprises a phenolic resin.
The invention can achieve the optimal technical effect by selecting the phenolic resin.
Preferably, the dispersant in step (1) is absolute ethyl alcohol.
The content of the dispersant is not particularly limited, as long as the mixed material can be dispersed, and the dispersant can be selected by a person skilled in the art according to actual needs, wherein 1-10 mL is selected exemplarily in the invention.
Preferably, the mass ratio of the petroleum coke particles to the resin in the step (1) is (2-9): 1, such as 3:1, 4:1, 5:1, 6:1, 7:1 or 8: 1.
The mass ratio of the petroleum coke particles to the resin is (2-9): 1, the mass ratio is too small, the petroleum coke particles are too few, the resin is too much, the coating is excessive, the insertion and the extraction of lithium ions are hindered by an excessively thick coating layer, the particle coating is not uniform due to the too small addition amount of the phenolic resin, the volume expansion and the fracture of graphite are caused in the circulation process, and the circulation performance is influenced; if the mass ratio is too large, the petroleum coke particles are too much, and the resin is too little, the coating is incomplete.
Preferably, in the stirring and temperature raising process in the step (1), the stirring speed is 15-35 Hz, such as 17Hz, 19Hz, 20Hz, 21Hz, 23Hz, 25Hz, 27Hz, 29Hz, 30Hz, 31Hz, 33Hz, and the like.
The stirring speed is controlled to be 15-35 Hz, excessive coating can be caused by excessively high stirring speed, and uneven coating can be caused by excessively low stirring speed.
Preferably, in the stirring temperature rise process in step (1), the temperature rise mode is as follows: the time for raising the temperature from normal temperature to 300 ℃ is 0.5-2 h (for example, 0.6h, 0.8h, 1h, 1.1h, 1.2h, 1.3h, 1.5h, 1.6h or 1.8h, etc.), then the time for raising the temperature from 300 ℃ to 500 ℃ is 0.5-1.5 h (for example, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h or 1.4h, etc.), finally the time for raising the temperature from 500 ℃ to 600-700 ℃ is 1-3 h (for example, 1.1h, 1.3h, 1.5h, 1.7h, 1.9h, 2.1h, 2.3h, 2.5h, 2.7h, 2.8h or 2.9h, etc.), and the temperature is maintained for 3-5 h, for example, 3.1h, 3.3h, 3.5h, 3.4 h, 4.4 h, 4h, 4.4 h, etc.
According to the invention, the petroleum coke particles are coated and bonded by volatile matters of the petroleum coke to form secondary particles, and at the temperature, the phenolic resin permeates into the petroleum coke particles and among the particles along with the increase of the temperature, so that the bonding force among graphite particles is enhanced, the granulation structure strength is high, and the coating of the petroleum coke particles is further improved by modifying the internal pores.
Preferably, before the stirring temperature rise in the step (1), a vacuum drying process is further included.
Preferably, the mixing in the step (1) is mixing by a high-speed stirring mixer.
Preferably, the particle size of the calcined needle coke particles in step (2) is 10-15 μm, such as 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm or 14.5 μm.
Preferably, the preparation process of the calcined needle coke particles in the step (2) comprises the following steps: and (3) primarily breaking, grinding and grading the calcined needle coke to obtain calcined needle coke particles.
The invention removes fine powder by classification to reduce the influence of fine powder particles on later circulation.
Preferably, the mass ratio of the petroleum coke secondary particles to the calcined needle coke particles in the step (2) is (0.6-1.5): 1, such as 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1 or 1.4: 1.
The mass ratio of the petroleum coke secondary particles to the calcined needle coke particles is (0.6-1.5): 1, if the petroleum coke proportion is higher, the material circulation performance is weakened, and if the calcined needle coke particles proportion is higher, the material processing performance is poorer.
Preferably, the mixing in the step (2) is stirring mixing, preferably the stirring speed is 15-30 Hz, such as 16Hz, 17Hz, 18Hz, 19Hz, 20Hz, 21Hz, 22Hz, 23Hz, 24Hz, 25Hz, 26Hz, 27Hz, 28Hz or 29Hz, etc.
Preferably, the mixing of step (2) is performed in a horizontal mixer.
Preferably, the temperature of the graphitization process in the step (3) is 2600-3000 ℃, such as 2650 ℃, 2700 ℃, 2750 ℃, 2800 ℃, 2850 ℃, 2900 ℃, 2950 ℃ and the like.
Preferably, the time of the graphitization process in the step (3) is 20-50 h, such as 22h, 25h, 28h, 30h, 32h, 35h, 38h, 40h, 42h, 45h or 48 h.
Too long time or too high temperature in the graphitization process can cause too low d002 (interlayer spacing of graphite), large expansion of graphite particles in the circulation process, too short time or too low temperature can cause insufficient crystallization of the graphite particles, and the graphitization degree is insufficient, thereby affecting the later circulation.
Preferably, the graphitization process in step (3) is performed in a vertical graphitization furnace.
The continuous graphitization mode of the vertical graphitization furnace is adopted, the rapid cooling mode is adopted, the problem that the internal structure of the graphite crystal expands because the conventional graphitized graphite particles are in a high-temperature state for a long time can be solved, the continuous graphitization cooling is high in production efficiency, the graphite crystal discharged from the furnace is stable in structure and small in specific surface area, the irreversible capacity is reduced, meanwhile, the later-stage cyclic exertion is facilitated, and meanwhile, the nitrogen protection is adopted in the whole process of the continuous graphitization process, so that the risk of later-stage cyclic water-skipping with the large specific surface area caused by graphite oxidation due to high temperature is reduced.
As a preferred technical scheme, the preparation method of the graphite negative electrode material comprises the following steps:
(1) primarily crushing, grinding and classifying petroleum coke into petroleum coke particles with the particle size of 8-12 mu m;
(2) primarily breaking, grinding and grading the calcined needle coke into calcined needle coke particles of 10-15 mu m;
(3) mixing the petroleum coke particles prepared in the step (1), resin and a dispersing agent, wherein the mass ratio of the petroleum coke particles to the resin is (2-9): 1, mixing the petroleum coke particles and the resin by a high-speed stirring mixer, and then volatilizing the dispersing agent by adopting vacuum drying;
(4) putting the petroleum coke particles prepared in the step (3) into a horizontal reaction kettle, stirring and heating, wherein the stirring speed is 15-35 Hz, and the heating mode is as follows: the temperature is raised from the normal temperature to 300 ℃ for 0.5-2 h, then the temperature is raised from 300 ℃ to 500 ℃ for 0.5-1.5 h, finally the temperature is raised from 500 ℃ to 600-700 ℃ for 1-3 h, and the temperature is kept for 3-5 h to obtain petroleum coke secondary particles;
(5) stirring and mixing the petroleum coke secondary particles and the calcined needle coke particles obtained in the step (2) according to the mass ratio of (0.6-1.5) to 1 by using a horizontal mixer at the stirring speed of 15-30 Hz to obtain an artificial graphite precursor;
(6) and carrying out a graphitization process on the artificial graphite precursor through a vertical graphitization furnace, wherein the temperature of the graphitization process is 2600-3000 ℃, and the time of the graphitization process is 20-50 h, so as to obtain the artificial graphite negative electrode material.
The second object of the present invention is to provide an artificial graphite negative electrode material obtained by the production method according to the first object.
Preferably, the particle size D50 of the artificial graphite negative electrode material is 13-17 μm.
The third object of the present invention is to provide a lithium ion battery comprising the artificial graphite negative electrode material of the second object.
Compared with the prior art, the invention has the following beneficial effects:
(1) the phenolic resin adopted by the invention has high bonding strength and good permeability, ensures the structural stability of secondary graphite particles in the later cycle process, ensures that the internal crystal structure cannot collapse due to graphite expansion in the later cycle process, has strong repeatability, can be used for continuous production, and has stable and easily controlled process.
(2) After the calcined needle coke is calcined at high temperature, the side reaction with electrolyte can be reduced, and the cycle performance can be obviously improved; meanwhile, the volatile content in the petroleum coke can be reduced through granulation, the caking risk in the graphitization process is reduced, and the calcined needle coke particles and the petroleum coke particles are mixed to make up the defect of insufficient petroleum coke circulation and improve the processability of the calcined needle coke.
(3) The continuous graphitization method adopts the continuous graphitization mode of the vertical graphitization furnace and adopts the rapid cooling mode, so that the problem of expansion of the internal structure of the graphite crystal can be avoided, the continuous graphitization cooling has high production efficiency, the graphite crystal discharged from the furnace has stable structure and small specific surface area, the irreversible capacity is reduced, the later-period cyclic exertion is facilitated, and the nitrogen protection is adopted in the whole process of the continuous graphitization process, so that the risk of later-period cyclic water-jumping with larger specific surface area caused by graphite oxidation due to high temperature is reduced.
Drawings
FIG. 1 is a graph showing a comparison of 25 ℃ storage properties of artificial graphite negative electrode materials obtained in example 1 of the present invention and comparative example 1;
FIG. 2 is a graph comparing 30 ℃ cycle performance of the artificial graphite anode materials obtained in example 1 of the present invention and comparative example 1.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The preparation method of the graphite negative electrode material comprises the following steps:
(1) the petroleum coke is primarily crushed, ground and classified to be crushed into petroleum coke particles with the average particle size of 10 mu m;
(2) primarily breaking, grinding and grading the calcined needle coke into calcined needle coke particles with the average particle size of 12 mu m;
(3) mixing the petroleum coke particles prepared in the step (1), phenolic resin and absolute ethyl alcohol, wherein the mass ratio of the petroleum coke particles to the phenolic resin is 4:1, mixing the petroleum coke particles and the phenolic resin by a high-speed stirring mixer, and then volatilizing the absolute ethyl alcohol by adopting vacuum drying;
(4) putting the petroleum coke particles prepared in the step (3) into a horizontal reaction kettle, stirring and heating, wherein the stirring speed is 20Hz, and the heating mode is as follows: heating from normal temperature to 300 ℃ for 1.5h, then heating from 300 ℃ to 500 ℃ for 1h, finally heating from 500 ℃ to 650 ℃ for 2h, and preserving heat for 4h to obtain petroleum coke secondary particles;
(5) stirring and mixing the petroleum coke secondary particles and the calcined needle coke particles obtained in the step (2) according to the mass ratio of 1:1 by a horizontal mixer at the stirring speed of 20Hz to obtain an artificial graphite precursor;
(6) and carrying out a graphitization process on the artificial graphite precursor through a vertical graphitization furnace, wherein the temperature of the graphitization process is 2800 ℃, and the time of the graphitization process is 40h, so as to obtain the artificial graphite cathode material.
Example 2
The difference from the example 1 is that the mass ratio of the petroleum coke particles to the resin in the step (3) is 2: 1.
Example 3
The difference from the example 1 is that the mass ratio of the petroleum coke particles and the resin in the step (3) is 9: 1.
Example 4
The difference from the example 1 is that the mass ratio of the petroleum coke particles and the resin in the step (3) is 1: 1.
Example 5
The difference from the example 1 is that the mass ratio of the petroleum coke particles to the resin in the step (3) is 10: 1.
Example 6
The difference from the example 1 is that the mass ratio of the petroleum coke secondary particles obtained in the step (5) to the calcined needle coke particles obtained in the step (2) is 0.6: 1.
Example 7
The difference from the example 1 is that the mass ratio of the petroleum coke secondary particles obtained in the step (5) to the calcined needle coke particles obtained in the step (2) is 1.5: 1.
Example 8
The difference from the example 1 is that the mass ratio of the petroleum coke secondary particles obtained in the step (5) to the calcined needle coke particles obtained in the step (2) is 0.5: 1.
Example 9
The difference from the example 1 is that the mass ratio of the petroleum coke secondary particles obtained in the step (5) to the calcined needle coke particles obtained in the step (2) is 2: 1.
Example 10
The preparation method of the graphite negative electrode material comprises the following steps:
(1) the petroleum coke is primarily crushed, ground and classified to be crushed into petroleum coke particles with the average particle size of 8 mu m;
(2) primarily breaking, grinding and grading the calcined needle coke into calcined needle coke particles with the average particle size of 10 mu m;
(3) mixing the petroleum coke particles prepared in the step (1), phenolic resin and absolute ethyl alcohol, wherein the mass ratio of the petroleum coke particles to the phenolic resin is 5:1, mixing the petroleum coke particles and the phenolic resin by a high-speed stirring mixer, and then volatilizing the absolute ethyl alcohol by adopting vacuum drying;
(4) putting the petroleum coke particles prepared in the step (3) into a horizontal reaction kettle, stirring and heating, wherein the stirring speed is 15Hz, and the heating mode is as follows: heating from normal temperature to 300 ℃ for 2h, then heating from 300 ℃ to 500 ℃ for 1.5h, finally heating from 500 ℃ to 600 ℃ for 3h, and preserving heat for 5h to obtain petroleum coke secondary particles;
(5) stirring and mixing the petroleum coke secondary particles and the calcined needle coke particles obtained in the step (2) according to the mass ratio of 1.5:1 by a horizontal mixer at the stirring speed of 15Hz to obtain an artificial graphite precursor;
(6) and carrying out a graphitization process on the artificial graphite precursor through a vertical graphitization furnace, wherein the temperature of the graphitization process is 2600 ℃, and the time of the graphitization process is 50h, so as to obtain the artificial graphite negative electrode material.
Example 11
The preparation method of the graphite negative electrode material comprises the following steps:
(1) the petroleum coke is primarily crushed, ground and classified to be crushed into petroleum coke particles with the average particle size of 12 mu m;
(2) primarily breaking, grinding and grading the calcined needle coke into calcined needle coke particles with the average particle size of 15 mu m;
(3) mixing the petroleum coke particles prepared in the step (1), phenolic resin and absolute ethyl alcohol, wherein the mass ratio of the petroleum coke particles to the phenolic resin is 8:1, mixing the petroleum coke particles and the phenolic resin by a high-speed stirring mixer, and then volatilizing the absolute ethyl alcohol by adopting vacuum drying;
(4) putting the petroleum coke particles prepared in the step (3) into a horizontal reaction kettle, stirring and heating, wherein the stirring speed is 35Hz, and the heating mode is as follows: raising the temperature from normal temperature to 300 ℃ for 0.5h, then raising the temperature from 300 ℃ to 500 ℃ for 0.5h, finally raising the temperature from 500 ℃ to 700 ℃ for 1.5h, and preserving the heat for 3h to obtain petroleum coke secondary particles;
(5) stirring and mixing the petroleum coke secondary particles and the calcined needle coke particles obtained in the step (2) according to the mass ratio of 0.6:1 by a horizontal mixer at the stirring speed of 30Hz to obtain an artificial graphite precursor;
(6) and carrying out a graphitization process on the artificial graphite precursor through a vertical graphitization furnace, wherein the temperature of the graphitization process is 3000 ℃, and the time of the graphitization process is 20h, so as to obtain the artificial graphite cathode material.
Comparative example 1
(1) The petroleum coke is primarily crushed, ground and classified to be crushed into petroleum coke particles with the average particle size of 10 mu m;
(2) uniformly mixing the petroleum coke particles prepared in the step 1 and phenolic resin according to the proportion of 8:2, taking absolute ethyl alcohol as a dispersing agent, uniformly mixing the petroleum coke particles and the phenolic resin by a high-speed stirring mixer, and then completely volatilizing the absolute ethyl alcohol by adopting vacuum drying;
(3) putting the evenly mixed petroleum coke particles prepared in the step (2) into a vertical reaction kettle, wherein the stirring speed is 20Hz, and the temperature rising curve is as follows: the time from normal temperature to 300 ℃ is 1.5h, then the time from 300 ℃ to 650 ℃ is 3h, the temperature is kept constant at 650 ℃ for 2.5h, and petroleum coke coating granulation is completed by stirring and heating;
(4) graphitizing the artificial graphite precursor prepared in the step (3) by adopting an Acheson graphitizing furnace at 2800 ℃ for 40h at the highest temperature.
The preparation process comparative ratios of example 1 of the present invention and comparative example 1 are shown in table 1:
TABLE 1
Figure BDA0002516534170000121
FIG. 1 is a graph comparing the storage performance at 25 ℃ of the artificial graphite anode material obtained in example 1 of the present invention and that obtained in comparative example 1, under the following test conditions: under the environment of 25 +/-2 ℃, using 1C current to circulate for 13 weeks and fully charge (taking the average value of the discharge capacity of 11-13 weeks as the initial capacity), storing for 28 days under the environment of 25 +/-2 ℃, using 1C current to circulate for 5 weeks after the storage is finished (taking the discharge capacity of the first week as the retention capacity, taking the average value of the discharge capacity of 3-5 weeks as the recovery capacity), wherein the capacity retention rate is the percentage value of the retention capacity to the initial capacity, and the capacity recovery rate is the percentage value of the recovery capacity to the initial capacity; fig. 2 is a graph comparing 30 ℃ cycle performance of the artificial graphite anode material obtained in example 1 of the present invention and comparative example 1, and the test conditions are as follows: under the environment of 30 +/-2 ℃, 1C current charge-discharge circulation is used, the average value of the previous five weeks is taken as the initial capacity, the capacity retention rate is the percentage value of the weekly discharge capacity to the initial capacity, and the figure shows that the storage performance and the circulation performance of the embodiment 1 are obviously superior to those of the comparative example 1.
And (3) performance testing:
the artificial graphite negative electrode materials obtained in examples 1 to 11 and comparative example 1 were made into 505070 lithium iron phosphate soft-package batteries and subjected to 25 ℃ storage and 30 ℃ cycle test (test conditions are as described above), the positive and negative electrode formulations are shown in attached tables 2 and 3, and the performance test results are shown in table 4:
TABLE 2
Figure BDA0002516534170000122
Figure BDA0002516534170000131
TABLE 3
LFP SP CNT PVDF
Examples 1 to 11 96.8％ 0.5％ 0.7％ 2％
Comparative example 1 96.8％ 0.5％ 0.7％ 2％
TABLE 4
Figure BDA0002516534170000132
As can be seen from tables 1-4, the calcined needle coke raw material is added on the basis of the comparative example 1, on the premise of improving the capacity and compacting, the stability of the negative electrode in the circulation process can be ensured by the stable crystal structure of the calcined needle coke, meanwhile, the processability of the calcined needle coke can be improved by petroleum coke secondary particles, the comparative example 1 adopts a vertical reaction kettle for granulation, the granulation uniformity is poor, the particles are incompletely coated, the uncoated surface and electrolyte generate more side reactions in the circulation process, and the circulation water jump is easily caused, the Acheson graphitization mode adopted by the comparative example 1 has long time period and slow cooling speed, the graphitization degree difference of graphite particles at different positions of the same furnace is larger, the graphite particles are easily oxidized, the specific surface area of the oxidized graphite particles is increased, and the newly added pores caused by oxidation in the circulation process can generate more side reactions with the electrolyte because the newly added pores are not coated, the graphite crystal structure is damaged to cause circular water jumping, and the continuous graphitization mode adopted by the embodiment adopts whole-process nitrogen protection, so that the cooling speed is high, the graphitization degree of each position in the same furnace is uniform, and the integrity of particles is well protected.
As can be seen from Table 4, the electrochemical performance of examples 4-5 is inferior to that of example 1, because the mass ratio of the petroleum coke particles to the resin in example 4 is 1:1, the content of the petroleum coke particles is too low, the resin is too much, the coating is excessive, and the lithium ions are prevented from being inserted and extracted by the excessively thick coating layer; in example 5, the mass ratio of the petroleum coke particles to the resin is 10:1, the content of the petroleum coke particles is too much, and the resin is too little, so that the coating is not complete, and further, the electrochemical performance of examples 4-5 is inferior to that of example 1.
As can be seen from Table 4, the electrochemical performance of examples 8-9 is inferior to that of example 1, because the mass ratio of the petroleum coke secondary particles to the calcined needle coke particles in example 8 is 0.5:1, the content of the petroleum coke secondary particles is less, and the material processability is poor; in example 9, the mass ratio of the petroleum coke secondary particles to the calcined needle coke particles is 2:1, the content of the petroleum coke secondary particles is large, the material cycle performance is weakened, and further, the electrochemical performance of examples 8 to 9 is inferior to that of example 1.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (10)

1. A preparation method of an artificial graphite anode material is characterized by comprising the following steps:
(1) mixing petroleum coke particles, resin and a dispersing agent, stirring and heating to obtain petroleum coke secondary particles;
(2) mixing the petroleum coke secondary particles with the calcined needle coke particles to obtain an artificial graphite precursor;
(3) and carrying out a graphitization process on the artificial graphite precursor to obtain the artificial graphite cathode material.
2. The method according to claim 1, wherein the petroleum coke particles of step (1) have a particle size of 8 to 12 μm;
preferably, the preparation process of the petroleum coke particles in the step (1) comprises the following steps: the petroleum coke is subjected to primary crushing, grinding and grading crushing to obtain petroleum coke particles.
3. The method of claim 1 or 2, wherein the resin of step (1) comprises a phenolic resin;
preferably, the dispersant in the step (1) is absolute ethyl alcohol;
preferably, the mass ratio of the petroleum coke particles to the resin in the step (1) is (2-9): 1.
4. The preparation method according to any one of claims 1 to 3, wherein in the step (1), the stirring speed is 15 to 35Hz during the stirring and temperature raising;
preferably, in the stirring temperature rise process in step (1), the temperature rise mode is as follows: the temperature is raised from the normal temperature to 300 ℃ for 0.5-2 h, then the temperature is raised from 300 ℃ to 500 ℃ for 0.5-1.5 h, finally the temperature is raised from 500 ℃ to 600-700 ℃ for 1-3 h, and the temperature is kept for 3-5 h;
preferably, before the stirring and heating in the step (1), a vacuum drying process is further included;
preferably, the mixing in the step (1) is mixing by a high-speed stirring mixer.
5. The method according to any one of claims 1 to 4, wherein the calcined needle coke particles of step (2) have a particle size of 10 to 15 μm;
preferably, the preparation process of the calcined needle coke particles in the step (2) comprises the following steps: and (3) primarily breaking, grinding and grading the calcined needle coke to obtain calcined needle coke particles.
6. The method according to any one of claims 1 to 5, wherein the mass ratio of the petroleum coke secondary particles to the calcined needle coke particles in the step (2) is (0.6-1.5): 1;
preferably, the mixing in the step (2) is stirring mixing, and the preferable stirring speed is 15-30 Hz;
preferably, the mixing of step (2) is performed in a horizontal mixer.
7. The method according to any one of claims 1 to 6, wherein the temperature of the graphitization process in the step (3) is 2600 to 3000 ℃;
preferably, the time of the graphitization process in the step (3) is 20-50 h;
preferably, the graphitization process in step (3) is performed in a vertical graphitization furnace.
8. The method of any one of claims 1 to 7, wherein the method comprises the steps of:
(1) primarily crushing, grinding and classifying petroleum coke into petroleum coke particles with the particle size of 8-12 mu m;
(2) primarily breaking, grinding and grading the calcined needle coke into calcined needle coke particles of 10-15 mu m;
(3) mixing the petroleum coke particles prepared in the step (1), resin and a dispersing agent, wherein the mass ratio of the petroleum coke particles to the resin is (2-9): 1, mixing the petroleum coke particles and the resin by a high-speed stirring mixer, and then volatilizing the dispersing agent by adopting vacuum drying;
(4) putting the petroleum coke particles prepared in the step (3) into a horizontal reaction kettle, stirring and heating, wherein the stirring speed is 15-35 Hz, and the heating mode is as follows: the temperature is raised from the normal temperature to 300 ℃ for 0.5-2 h, then the temperature is raised from 300 ℃ to 500 ℃ for 0.5-1.5 h, finally the temperature is raised from 500 ℃ to 600-700 ℃ for 1-3 h, and the temperature is kept for 3-5 h to obtain petroleum coke secondary particles;
(5) stirring and mixing the petroleum coke secondary particles and the calcined needle coke particles obtained in the step (2) according to the mass ratio of (0.6-1.5) to 1 by using a horizontal mixer at the stirring speed of 15-30 Hz to obtain an artificial graphite precursor;
(6) and carrying out a graphitization process on the artificial graphite precursor through a vertical graphitization furnace, wherein the temperature of the graphitization process is 2600-3000 ℃, and the time of the graphitization process is 20-50 h, so as to obtain the artificial graphite negative electrode material.
9. An artificial graphite negative electrode material, characterized in that it is obtained by the production method according to any one of claims 1 to 8;
preferably, the particle size D50 of the artificial graphite negative electrode material is 13-17 μm.
10. A lithium ion battery comprising the artificial graphite negative electrode material according to claim 9.
CN202010478553.3A 2020-05-29 2020-05-29 Artificial graphite negative electrode material, preparation method thereof and application thereof in lithium ion battery Pending CN111620331A (en)

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CN112670472A (en) * 2020-12-22 2021-04-16 宁波杉杉新材料科技有限公司 Graphite negative electrode material, lithium ion battery, preparation method and application
CN113410449A (en) * 2021-06-25 2021-09-17 广东凯金新能源科技股份有限公司 Multiphase adjustable carbon-coated novel artificial graphite negative electrode material and preparation method thereof
CN113526500A (en) * 2021-07-20 2021-10-22 安徽科达新材料有限公司 Preparation method of high-performance artificial graphite negative electrode material
CN113830761A (en) * 2021-08-16 2021-12-24 山西沁新能源集团股份有限公司 Preparation method of artificial graphite negative electrode material
CN113921784A (en) * 2021-09-29 2022-01-11 湖北亿纬动力有限公司 Negative electrode material and preparation method and application thereof
CN114300644A (en) * 2021-11-24 2022-04-08 惠州市豪鹏科技有限公司 Negative plate, preparation method thereof and lithium ion battery

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CN112670472A (en) * 2020-12-22 2021-04-16 宁波杉杉新材料科技有限公司 Graphite negative electrode material, lithium ion battery, preparation method and application
CN113410449A (en) * 2021-06-25 2021-09-17 广东凯金新能源科技股份有限公司 Multiphase adjustable carbon-coated novel artificial graphite negative electrode material and preparation method thereof
CN113526500A (en) * 2021-07-20 2021-10-22 安徽科达新材料有限公司 Preparation method of high-performance artificial graphite negative electrode material
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CN114300644A (en) * 2021-11-24 2022-04-08 惠州市豪鹏科技有限公司 Negative plate, preparation method thereof and lithium ion battery

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Application publication date: 20200904