CN115448305A - Graphite matrix and preparation method thereof, and quick-charging graphite and preparation method thereof - Google Patents
Graphite matrix and preparation method thereof, and quick-charging graphite and preparation method thereof Download PDFInfo
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- CN115448305A CN115448305A CN202211136873.6A CN202211136873A CN115448305A CN 115448305 A CN115448305 A CN 115448305A CN 202211136873 A CN202211136873 A CN 202211136873A CN 115448305 A CN115448305 A CN 115448305A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 126
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 104
- 239000010439 graphite Substances 0.000 title claims abstract description 104
- 239000011159 matrix material Substances 0.000 title claims abstract description 49
- 238000002360 preparation method Methods 0.000 title claims abstract description 28
- 239000002243 precursor Substances 0.000 claims abstract description 147
- 239000002245 particle Substances 0.000 claims abstract description 54
- 239000011164 primary particle Substances 0.000 claims abstract description 19
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 18
- 238000009818 secondary granulation Methods 0.000 claims abstract description 13
- 238000002156 mixing Methods 0.000 claims abstract description 11
- 238000012216 screening Methods 0.000 claims abstract description 8
- 239000011248 coating agent Substances 0.000 claims abstract description 7
- 238000000576 coating method Methods 0.000 claims abstract description 7
- 239000010426 asphalt Substances 0.000 claims description 31
- 239000000047 product Substances 0.000 claims description 27
- 239000011230 binding agent Substances 0.000 claims description 24
- 229910052799 carbon Inorganic materials 0.000 claims description 22
- 239000010410 layer Substances 0.000 claims description 22
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 21
- 239000013067 intermediate product Substances 0.000 claims description 16
- 239000011259 mixed solution Substances 0.000 claims description 15
- 239000011347 resin Substances 0.000 claims description 15
- 229920005989 resin Polymers 0.000 claims description 15
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 14
- 230000004927 fusion Effects 0.000 claims description 9
- 238000000227 grinding Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 9
- 238000005087 graphitization Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 238000009817 primary granulation Methods 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 8
- 239000000758 substrate Substances 0.000 claims description 8
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 claims description 7
- 238000007599 discharging Methods 0.000 claims description 7
- 239000003502 gasoline Substances 0.000 claims description 7
- 239000003350 kerosene Substances 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000011331 needle coke Substances 0.000 claims description 6
- 229910021382 natural graphite Inorganic materials 0.000 claims description 5
- 239000002006 petroleum coke Substances 0.000 claims description 5
- 239000006253 pitch coke Substances 0.000 claims description 5
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 4
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 claims description 4
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 claims description 4
- 239000003822 epoxy resin Substances 0.000 claims description 4
- 239000007849 furan resin Substances 0.000 claims description 4
- 239000005011 phenolic resin Substances 0.000 claims description 4
- 229920001568 phenolic resin Polymers 0.000 claims description 4
- 229920000647 polyepoxide Polymers 0.000 claims description 4
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 claims description 4
- 239000012790 adhesive layer Substances 0.000 claims description 2
- 238000007873 sieving Methods 0.000 claims 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 37
- 229910052744 lithium Inorganic materials 0.000 abstract description 37
- 230000002687 intercalation Effects 0.000 abstract description 22
- 238000009830 intercalation Methods 0.000 abstract description 22
- 238000012545 processing Methods 0.000 abstract description 4
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 230000004069 differentiation Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 238000000498 ball milling Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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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
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/205—Preparation
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
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Abstract
The invention discloses a graphite matrix and a preparation method thereof, and quick-charging graphite and a preparation method thereof, and relates to the technical field of lithium batteries. The graphite matrix comprises a primary precursor, a secondary precursor and a bonding layer, wherein the bonding layer wraps the primary precursor, and the secondary precursor is adhered to the bonding layer; the grain diameter of the first-level precursor is larger than that of the second-level precursor. The graphite matrix adheres the secondary precursor with smaller particle size to the bonding layer of the primary precursor with larger particle size, and increases the lithium-embedded end face by utilizing the two-stage precursors with different particle sizes. The preparation method of the graphite matrix comprises the steps of primarily screening ground carbon materials, processing a primary precursor with larger particle size, and then granulating for one time to reduce the expansion of the primary precursor in the Y direction; then mixing the primary particles with the secondary precursor and carrying out secondary granulation to increase the lithium intercalation end face of the graphite particles and improve the lithium intercalation speed; and graphitizing the graphite matrix, and finally, improving the lithium intercalation path and the rate capability through surface coating.
Description
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a graphite matrix and a preparation method thereof, and quick-charging graphite and a preparation method thereof.
Background
The lithium battery has the characteristics of long service life, high energy density and high safety coefficient, and becomes a preferred power supply product for electronic equipment in life. Nowadays, fast pace life also puts higher and higher requirements on the charging speed and the charging time of the lithium battery. The graphite negative electrode is used as a key component of the lithium battery, and has a remarkable influence on the improvement of the charging speed. However, the graphite is generally in a layered structure, lithium ions can only enter and exit from the graphite layer from the edge end face, and cannot enter and exit from the direction perpendicular to the graphite layer, the transfer speed is limited, the charging capability is affected, and the requirement of large-rate charge and discharge cannot be met.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a graphite matrix and a preparation method thereof, and quick-charging graphite and a preparation method thereof.
The invention discloses a graphite matrix, which comprises a primary precursor, a secondary precursor and a bonding layer, wherein the bonding layer wraps the primary precursor, and the secondary precursor is adhered to the bonding layer; wherein the grain diameter of the primary precursor is larger than that of the secondary precursor.
According to one embodiment of the invention, the bonding layer comprises asphalt mixed liquor and a binder, wherein the asphalt mixed liquor comprises the following components in a mass ratio of (8-10): (2-5): (1-2): (0.5-1) asphalt, gasoline, kerosene and industrial benzene, wherein the binder comprises the following components in percentage by mass (12-13): (15-20) aluminum nitrate and ethanol.
According to one embodiment of the invention, the primary precursor and the secondary precursor are obtained by grinding and screening carbon materials, wherein the particle size of the primary precursor is 7-9 μm, and the particle size of the secondary precursor is 3-5 μm.
According to an embodiment of the present invention, the carbon material is one or more of needle coke, petroleum coke, pitch coke, and natural graphite.
The invention discloses a preparation method of the graphite matrix, which comprises the following steps:
grinding the carbon material, and screening to obtain a primary precursor and a secondary precursor, wherein the particle size of the primary precursor is larger than that of the secondary precursor;
mixing and stirring the primary precursor, the asphalt mixed solution and the binder to obtain a primary intermediate product, wherein the mass ratio of the primary precursor to the asphalt mixed solution to the binder is (120-150): (11.5 to 18): (28-33);
performing primary granulation on the primary intermediate product to obtain primary particles, and discharging the primary particles into a fusion machine;
and (3) adding the secondary precursor into a fusion machine for treatment, and finishing secondary granulation to obtain a graphite matrix, wherein the mass ratio of the secondary precursor to the primary precursor is (50-100): (120 to 150).
According to an embodiment of the present invention, after the primary granulation is completed, the asphalt mixture and the binder form a bonding layer on the surface of the primary precursor.
The invention discloses quick-charging graphite, which comprises a graphitized product and a carbon source, wherein the carbon source is coated on the surface of the graphitized product, and the graphitized product is prepared by graphitizing the graphite matrix.
The invention discloses a preparation method of quick-charging graphite, which comprises the following steps:
placing the graphite matrix in a graphitization furnace for graphitization treatment to prepare a graphitized product;
and mixing the graphitized product with a carbon source, and heating to complete surface coating to obtain the rapidly-filled graphite.
According to one embodiment of the present invention, the mass ratio of the graphitized article to the carbon source is (50 to 100): (1-30).
According to one embodiment of the invention, the carbon source is one or more of rosin, alpha-terpene resin, beta-terpene resin, phenolic resin, epoxy resin, furan resin.
Compared with the prior art, the graphite matrix and the preparation method thereof, and the quick-charging graphite and the preparation method thereof have the following advantages:
according to the graphite matrix, the secondary precursor with a small particle size is adhered to the primary precursor with a large particle size, and the lithium intercalation end face is increased by using the two-stage precursors with different particle sizes, so that the lithium intercalation speed is increased.
The preparation method of the graphite matrix comprises the steps of primarily screening ground carbon materials, processing a primary precursor with larger particle size, and then granulating for one time so as to ensure the isotropy of the particles and reduce the expansion of the particles in the Y direction; then mixing the primary particles and the secondary precursor and carrying out secondary granulation to increase the lithium intercalation end faces of the graphite particles and improve the lithium intercalation speed; graphitizing the graphite matrix to enhance the structural stability of the particles and reduce the cycle thickness expansion; and finally, the graphite lithium intercalation path and the rate capability are further improved through surface coating.
In addition, the quick-charging graphite is prepared from a graphite matrix, the transfer speed of lithium ions can be greatly improved, the charging capacity of the lithium battery is further improved, and the requirement of high-rate charging and discharging is met.
Drawings
The accompanying drawings, which are described herein to provide a further understanding of the application, are included in the following description:
FIG. 1 is a schematic structural view of a graphite substrate;
FIG. 2 is a schematic diagram of a process for preparing a graphite substrate;
FIG. 3 is a schematic diagram of a process for preparing rapid-charging graphite;
FIG. 4 is a graph comparing the cycle capacity retention rate curves;
FIG. 5 is a comparison of cyclic thickness expansion curves.
Description of reference numerals:
1. a first-stage precursor; 2. a secondary precursor; 3. a tie layer; 4. a first-order intermediate product; 5. primary particles; 6. a graphite matrix; 7. graphitizing the product; 8. and (5) quickly filling graphite.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments of the invention. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, such implementation details are not necessary. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Example one
Referring to fig. 1, the graphite substrate includes a primary precursor 1, a secondary precursor 2, and a bonding layer 3, the primary precursor 1 is wrapped by the bonding layer 3, the secondary precursor 2 is adhered to the bonding layer 3, and the particle size of the primary precursor 1 is larger than that of the secondary precursor 2.
In this embodiment, the graphite substrate is configured such that the second-stage precursor having a smaller particle size is adhered to the adhesive layer of the first-stage precursor having a larger particle size, and the two-stage precursors having different particle sizes are used to increase the lithium intercalation end surface, thereby increasing the lithium intercalation speed.
Specifically, the primary precursor 1 and the secondary precursor 2 are obtained by grinding and screening carbon materials, wherein the carbon materials are one or more of needle coke, petroleum coke, pitch coke and natural graphite, the particle size of the primary precursor 1 is 7-9 μm, and the particle size of the secondary precursor 2 is 3-5 μm.
In this embodiment, the particle size range of the two-stage precursor is defined, firstly, to ensure that sufficient lithium intercalation end faces can be formed, and secondly, to control the processing difficulty. If the particle size of the two-stage precursor is larger than the limited particle size range, the lithium intercalation end face is correspondingly reduced, so that the lithium intercalation speed is reduced, and the charging capacity of the lithium battery is further influenced; if the particle size of the two-stage precursor is smaller than the limited particle size range, the processing difficulty is increased, the product quality is difficult to control, and the production cost is increased. In addition, the difference of the particle diameters of the two-stage precursors is 2-6 μm, the adhesion effect of the two-stage precursors within the range of the particle diameter difference is good, and if the particle diameters exceed the range, the adhesion between the two-stage precursors is influenced, and the quality and the performance are influenced.
Example two
This example provides a method for preparing a graphite substrate, which can be used to prepare the graphite substrate in example one.
In this embodiment, the preparation method of the graphite matrix includes the following steps:
grinding the carbon material, and screening to obtain a primary precursor and a secondary precursor;
adding the primary precursor and the binder into the asphalt mixed solution, and stirring to obtain a primary intermediate product, wherein the mass ratio of the primary precursor to the asphalt mixed solution to the binder is (120-150): (11.5 to 18): (28 to 33); preferably, the primary precursor is added into the asphalt mixed solution to fully wrap the surface of the primary precursor by the asphalt mixed solution, and then the binder is added into the mixture of the primary precursor and the asphalt mixed solution for stirring;
performing primary granulation on the primary intermediate product to obtain primary particles, and discharging the primary particles into a fusion machine;
and (3) adding the secondary precursor into a fusion machine for treatment, and finishing secondary granulation to obtain a graphite matrix, wherein the mass ratio of the secondary precursor to the primary precursor is (50-100): (120 to 150).
Please refer to fig. 2, which is a schematic diagram of a process for preparing a graphite substrate. Wherein, when the primary precursor 1, the asphalt mixed solution and the binder are mixed and stirred, the primary precursor is wrapped by the mixture of the asphalt mixed solution and the binder after stirring and mixing to form a primary intermediate product 4.
After primary granulation is carried out, a bonding layer is formed on the surface of the primary precursor 1 by the mixture of the asphalt mixed solution and the binder, namely, the primary precursor is wrapped by the bonding layer, and meanwhile, a plurality of primary precursors included by the bonding layer are mutually bonded to form primary particles 5.
After the secondary granulation, the secondary precursor 2 is bonded to the primary particles 1, that is, the secondary precursor is bonded to the bonding layer of the primary precursor 1, so as to form the graphite matrix 6.
In this example, the carbon material is one or more of needle coke, petroleum coke, pitch coke, and natural graphite. When the carbon material is ground, coarse crushing, fine grinding or ball milling shaping can be adopted, in other words, the carbon material is ground by coarse crushing, fine grinding or ball milling shaping, so that the carbon material is ground into a primary precursor and a secondary precursor with different particle sizes, and the particle size of the primary precursor is larger than that of the secondary precursor.
In the embodiment, the asphalt mixed solution comprises asphalt, gasoline, kerosene and industrial benzene, and the mass ratio of the asphalt, the gasoline, the kerosene and the industrial benzene is (8-10): (2-5): (1-2): (0.5-1). The adhesive comprises aluminum nitrate and ethanol, and the mass ratio of the aluminum nitrate to the ethanol is (12-13): (15 to 20). Mixing and stirring the primary precursor, the asphalt mixed solution and the binder, wherein the stirring temperature is 150-200 ℃.
The first-stage intermediate product is granulated once by adopting a spray drying method, and the method comprises the following steps: transferring the primary intermediate product to a sprayer, spraying the primary intermediate product to a drying tower through the sprayer, forming powdery primary particles by the atomized primary intermediate product at 200-300 ℃, and discharging the primary particles into a fusion machine after the primary particles descend.
When the secondary granulation is carried out, the treatment temperature of the secondary granulation is 100-200 ℃, the treatment rotating speed is 500-1500 rpm, and the treatment time is 10-60 min. The purpose of the secondary granulation is to slightly melt the surface of the pitch binder on the primary particles to create tack, further binding the secondary precursor.
EXAMPLE III
The embodiment provides a quick-charging graphite, which comprises a graphitized product and a carbon source, wherein the carbon source is coated on the surface of the graphitized product, and the graphitized product is prepared by graphitizing the graphite matrix as in the first embodiment.
Example four
The embodiment provides a preparation method of fast-charging graphite, which can be used for preparing the fast-charging graphite in the third embodiment.
In this embodiment, the preparation method of the fast graphite includes the following steps:
placing the graphite matrix in a graphitization furnace for graphitization treatment to prepare a graphitized product;
and mixing the graphitized product with a carbon source, and heating to ensure that the carbon source is wrapped on the surface of the graphitized product, thereby obtaining the finished product of the quick-charging graphite.
Please refer to fig. 3, which is a schematic diagram of a process for preparing the fast-charging graphite. After the graphite matrix 6 is graphitized, the carbon atoms inside the graphite matrix are changed from disorder to ordered arrangement to form a graphitized product 7. After the graphitized article 7 and the carbon source are mixed and heated, the carbon source is coated on the surface of the graphitized article 7 to form the fast-charging graphite 8.
In this example, the treatment temperature of the graphitization furnace is 2500 to 3000 ℃ and the treatment time is 12 to 60 hours in the production of a graphitized article.
In this example, the mass ratio of the graphitized article to the carbon source was (50 to 100): (1-30). Wherein the carbon source is one or more of rosin, alpha-terpene resin, beta-terpene resin, phenolic resin, epoxy resin and furan resin. When the graphitized product and a carbon source are mixed and heated, the heating is carried out in an inert atmosphere, the heating temperature is 250-300 ℃, and the heating time is 0.5-5 h.
Eleven samples of fast-filled graphite are provided for further illustration of the invention.
Sample No
The quick-charging graphite provided by the sample I comprises a graphitized product and a carbon source, wherein the carbon source is wrapped on the surface of the graphitized product, and the graphitized product is prepared by graphitizing a graphite matrix. The graphite matrix adopted in the first sample comprises a primary precursor, a secondary precursor and a bonding layer, wherein the primary precursor is wrapped by the bonding layer, the secondary precursor is adhered to the bonding layer, the particle size of the primary precursor is 9 micrometers, and the particle size of the secondary precursor is 5 micrometers.
The preparation method of the quick-charging graphite comprises two preparation processes, namely, preparing a graphite matrix and preparing the quick-charging graphite by using the prepared graphite matrix, and comprises the following specific preparation steps:
(1) Preparation of graphite matrix
Grinding the needle coke, and screening to obtain a primary precursor and a secondary precursor;
adding 120g of the primary precursor and 33g of the binder into 12g of asphalt mixed liquor in sequence, and stirring at 180 ℃ to obtain a primary intermediate product, wherein the binder comprises 13g of aluminum nitrate and 20g of ethanol, and the asphalt mixed liquor comprises 8g of asphalt, 2g of gasoline, 1g of kerosene and 1g of industrial benzene;
transferring the primary intermediate product to a sprayer, spraying the primary intermediate product to a drying tower through the sprayer, forming powdery primary particles by the atomized primary intermediate product at 250 ℃, and discharging the primary particles into a fusion machine after the primary particles descend;
and adding 80g of the secondary precursor into a fusion machine, and treating for 60min at the treatment temperature of 150 ℃ and the treatment rotating speed of 1000rpm to finish secondary granulation to obtain the graphite matrix.
(2) Preparation of fast-charging graphite
Placing the obtained graphite matrix in a graphitization furnace, and treating at 3000 ℃ for 24h to obtain a graphitized product;
and (2) mixing the graphitized product with alpha-terpene resin in a mass ratio of 50.
In the preparation of the graphite matrix, needle coke is selected as a carbon material, the practicability of the carbon material is superior to that of petroleum coke, pitch coke or natural graphite, and the performance of the lithium battery can be ensured.
In the preparation of the quick-charging graphite, alpha-terpene resin is selected as a carbon source, and compared with rosin, beta-terpene resin, phenolic resin, epoxy resin or furan resin, the surface coating effect of the alpha-terpene resin is better.
Sample No. 2
The main difference between the two samples as compared with the first sample is that the particle size of the primary precursor is 8 μm and the particle size of the secondary precursor is 4 μm in the graphite matrix.
Sample three
The main difference between the three phases of the sample and the first sample is that the particle size of the primary precursor is 7 μm and the particle size of the secondary precursor is 3 μm in the graphite matrix.
Sample No. 4
The main difference between sample four and sample one is that the total amount of bitumen-mixed liquor is 15g, which contains 9g of bitumen, 3.5g of gasoline, 1.5g of kerosene and 1g of industrial benzene.
Sample five
The main difference between sample five and sample one is that the total amount of asphalt mixture is 18g, which includes 10g of asphalt, 5g of gasoline, 2g of kerosene and 1g of industrial benzene.
Sample six
Sample six differs from sample one primarily in that the total amount of binder is 29.5g, including 12.5g of aluminum nitrate and 17g of ethanol.
Sample seven
The main difference between sample seven and sample one is that the total amount of binder is 27g, which includes 12g of aluminum nitrate and 15g of ethanol.
Sample eight
The main difference between sample eight and sample one is that the amount of the primary precursor is 130g and the amount of the secondary precursor is 65g.
Sample No. nine
The main difference between sample nine and sample one is that the amount of the primary precursor is 150g, and the amount of the secondary precursor is 50g.
Sample ten
The main difference between sample ten and sample one is that the mass ratio of the graphitized article to the α -terpene resin is 25:1.
sample eleven
The main difference between sample eleven and sample one is that the mass ratio of the graphitized article to the α -terpene resin is 100:1.
samples one to eleven were analyzed as follows, with the following specific results:
referring to table 1, it can be seen by comparison that the difference between the fast-charging graphites of samples one to three is that the particle size of the primary precursor is different from that of the secondary precursor, and the particle size of the two-stage precursor is smaller from sample one to sample three.
TABLE 1 Distinguishing Table for samples one to three
And (3) taking samples of the quick-charging graphite prepared by the first to third samples, preparing lithium batteries respectively by the same method, and testing the performance of the lithium batteries to research the influence of the quick-charging graphite on the performance of the lithium batteries.
Referring to fig. 4 and 5, fig. 2 is a graph comparing the cycle capacity retention rate curves, and fig. 3 is a graph comparing the cycle thickness expansion curves. In combination with the two figures, the smaller the particle size of the two-stage precursor for preparing the quick-charging graphite is, the better the cycle capacity retention rate of the prepared lithium battery is, and meanwhile, the smaller the cycle thickness expansion is, which shows that the charging capacity of the lithium battery is obviously improved. Generally speaking, the smaller the particle size of the two-stage precursor used for preparing the quick-charging graphite is, the better the charging performance of the lithium battery can be improved.
Referring to table 2, it can be seen by comparison that the fast-charging graphites of samples one, four and five are different in the total amount of the pitch mixed solution.
TABLE 2 differentiation of samples one, four and five
The asphalt mixed liquid plays a role in bonding, the total amount of the asphalt mixed liquid is increased, the primary precursors can be fully wrapped, better bonding between the primary precursors can be realized during primary granulation, and meanwhile, the secondary precursors can be better bonded on the primary precursors during secondary granulation.
Referring to table 3, it can be seen by comparison that the fast graphite of samples one, six and seven are different in the total amount of the pitch mixed liquid.
TABLE 3 differentiation of samples I, six and seven
The binder also plays a role in binding, the total amount of the binder is increased, the primary precursors can be fully wrapped, the primary precursors can be better bound during primary granulation, and the secondary precursors can be better bound on the primary precursors during secondary granulation.
Referring to table 4, it can be seen by comparison that the fast-charging graphites of samples one, eight and nine are different in the amount of the primary precursor and the secondary precursor.
TABLE 4 distinction of samples one, eight and nine
As can be seen from the above table, the mass ratios of the first-stage precursor to the second-stage precursor in the first, eighth, and ninth samples are 1.5: 1. 2: 1. 3:1, the larger the mass ratio of the primary precursor to the secondary precursor, the smaller the amount of the secondary precursor bonded to the primary precursor, and accordingly, the lithium intercalation end face and the lithium intercalation speed are reduced.
Referring to table 5, it can be seen by comparison that the fast-charging graphites of samples one, ten and eleven are different in the mass ratio of the graphitized article to the α -terpene resin.
TABLE 5 differentiation of samples one, ten and eleven
The alpha-terpene resin plays a role in coating, so that the lithium intercalation path and rate capability of the graphite are improved. The larger the mass ratio of the graphitized product to the alpha-terpene resin is, the more completely the graphitized product is coated, and the lithium intercalation path and the rate performance of the graphite are better improved.
In summary, the graphite matrix is granulated twice to adhere the secondary precursor with smaller particle size to the primary precursor with larger particle size, and the two-stage precursors with different particle sizes are used to increase the lithium intercalation end face, thereby increasing the lithium intercalation speed. Secondly, the preparation method of the graphite matrix is to primarily screen the ground carbon material, process the primary precursor with larger particle size and then granulate the primary precursor once, so as to ensure the isotropy of the particles and reduce the expansion of the particles in the Y direction; then mixing the primary particles with the secondary precursor and carrying out secondary granulation to increase the lithium intercalation end face of the graphite particles and improve the lithium intercalation speed; graphitizing the graphite matrix to enhance the structural stability of the particles and reduce the cycle thickness expansion; and finally, the graphite lithium intercalation path and rate capability are further improved through surface coating. In addition, the quick-charging graphite is prepared from a graphite matrix, the transfer speed of lithium ions can be greatly improved, the charging capacity of the lithium battery is further improved, and the requirement of high-rate charging and discharging is met.
The above description is only an embodiment of the present invention, and is not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (10)
1. A graphite matrix is characterized by comprising a primary precursor, a secondary precursor and a bonding layer, wherein the bonding layer wraps the primary precursor, and the secondary precursor is adhered to the bonding layer; wherein the particle size of the primary precursor is larger than that of the secondary precursor.
2. The graphite matrix according to claim 1, wherein the bonding layer comprises an asphalt mixture and a binder, and the asphalt mixture comprises the following components in a mass ratio of (8-10): (2-5): (1-2): (0.5-1) asphalt, gasoline, kerosene and industrial benzene, wherein the binder comprises the following components in percentage by mass (12-13): (15-20) aluminum nitrate and ethanol.
3. The graphite matrix according to claim 1, wherein the primary precursor and the secondary precursor are obtained by grinding and sieving carbon materials, the particle size of the primary precursor is 7 to 9 μm, and the particle size of the secondary precursor is 3 to 5 μm.
4. The graphite matrix of claim 3, wherein the carbon material is one or more of needle coke, petroleum coke, pitch coke, natural graphite.
5. A method for preparing the graphite matrix according to any one of claims 1 to 4, comprising the steps of:
grinding the carbon material, and screening to obtain a primary precursor and a secondary precursor, wherein the particle size of the primary precursor is larger than that of the secondary precursor;
mixing and stirring the primary precursor, the asphalt mixed solution and the binder to obtain a primary intermediate product, wherein the mass ratio of the primary precursor to the asphalt mixed solution to the binder is (120-150): (11.5-18): (28-33);
performing primary granulation on the primary intermediate product to obtain primary particles, and discharging the primary particles into a fusion machine;
and (2) adding the secondary precursor into a fusion machine for treatment, and finishing secondary granulation to obtain the graphite matrix, wherein the mass ratio of the secondary precursor to the primary precursor is (50-100): (120-150).
6. The method of producing a graphite substrate according to claim 5, wherein the pitch mixture and the binder form the adhesive layer on the surface of the primary precursor after the primary granulation.
7. A quick-charging graphite, which comprises a graphitized article and a carbon source, wherein the carbon source is coated on the surface of the graphitized article, and the graphitized article is prepared by graphitizing the graphite matrix according to any one of claims 1 to 4.
8. The preparation method of the quick-charging graphite according to claim 7, characterized by comprising the following steps:
placing the graphite matrix in a graphitization furnace for graphitization treatment to prepare a graphitized product;
and (3) mixing the graphitized product with a carbon source, and then heating to complete surface coating, thereby obtaining the quick-charging graphite.
9. The method for preparing the quick-charging graphite according to claim 8, wherein the mass ratio of the graphitized product to the carbon source is (50-100): (1-30).
10. The method for preparing the quick-charging graphite according to claim 8, wherein the carbon source is one or more of rosin, alpha-terpene resin, beta-terpene resin, phenolic resin, epoxy resin and furan resin.
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