CN117416955A - Graphite anode material precursor, graphite anode material, and preparation method and application thereof - Google Patents

Graphite anode material precursor, graphite anode material, and preparation method and application thereof Download PDF

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CN117416955A
CN117416955A CN202311460147.4A CN202311460147A CN117416955A CN 117416955 A CN117416955 A CN 117416955A CN 202311460147 A CN202311460147 A CN 202311460147A CN 117416955 A CN117416955 A CN 117416955A
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graphite
treatment
anode material
hours
ball milling
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张劲斌
顾凯
钱佳丽
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Shanghai Shanshan Technology Co Ltd
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Shanghai Shanshan Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • 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
    • C01B32/21—After-treatment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/04—Processes of manufacture in general

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Materials Engineering (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention discloses a graphite anode material precursor, a graphite anode material, and a preparation method and application thereof. The preparation method of the graphite anode material precursor mainly comprises the following steps: ball milling graphite and metal oxide, and then heat treatment and acid washing treatment; wherein, the metal oxide accounts for 2-46% of the mass of the graphite, and the percentage refers to the mass percentage of the metal oxide in the graphite; in the ball milling treatment, the rotational speed of the ball milling is 400-1000rpm. According to the invention, through a method combining mechanical activation and chemical catalysis, the lithium ion transmission channel of the prepared graphite anode material precursor is increased, and the further prepared graphite anode material has excellent discharge capacity and quick charge performance when being applied to a lithium ion battery.

Description

Graphite anode material precursor, graphite anode material, and preparation method and application thereof
Technical Field
The invention relates to a graphite anode material precursor, a graphite anode material, and a preparation method and application thereof.
Background
Graphite has the advantages of good conductivity, good charge-discharge voltage platform, higher specific capacity, low price and the like, and becomes a cathode material of the commercial main stream of lithium ion batteries, and the performance of the cathode material has important influence on the performance of the lithium batteries. Along with the continuous improvement of the use convenience requirements of new energy automobiles and electronic products, the rapid charging technology for improving the lithium ion battery has become a necessary trend.
However, in the process of charging graphite, lithium ions are preferentially intercalated into a graphite layer from the end face and then diffused into particles, the reactive sites of the material in the process of charging and discharging are limited, the diffusion path is prolonged, the rapid intercalation of lithium ions into graphite is not facilitated, and lithium is easy to separate out, so that the safety problem is caused. At present, improving the performance of graphite becomes a key path for improving the safety and quick charging performance of a lithium battery cathode.
CN115832292a discloses a modified quick-charging graphite negative electrode material, a modification method and application thereof, and graphite is added in CO 2 Pretreating under atmosphere, compounding with graphite by using fungus dreg extract, bamboo source and the like, and then carrying out hydrothermal treatment and carbonization to obtain the modified quick-charging graphite. The patent adopts biomass fungus residues, bamboo sources and other raw materials to have the defects of high ash content and unstable sources, so that the stability of the raw materials is difficult to effectively control, and the performance of the negative electrode is seriously influenced.
CN114784273a discloses a preparation method and application of graphite cathode material. The graphite modification is realized by the following steps: (1) Sequentially mixing, heating and rinsing graphite and a chemical etchant to obtain porous graphite; (2) And (3) coating a polydopamine layer on the porous graphite surface in the step (1), and drying to obtain the graphite anode material. The patent adopts alkaline or strong acid to realize etching modification of the graphite cathode, but has higher corrosiveness and requirements on equipment and higher safety risk when being applied to the production process. In addition, polydopamine is expensive and difficult to adapt for mass production.
CN116053442a discloses a fast-charging artificial graphite negative electrode material, a preparation method thereof and a lithium ion battery. The patent obtains the graphite cathode of the lithium ion battery through mechanical stirring modification and coating modification. When the method is applied to resin coating, the graphite is in poor contact with the hard carbon due to the structural characteristic difference of the graphite and the hard carbon, and the coating layer is easy to fall off in the charging and discharging process of the lithium ion battery.
CN114094079a provides a method for preparing a fast-charging graphite negative electrode material and a method for preparing a lithium ion battery. The patent adopts the steps of etching graphite by alkali solution, mixing and coating conductive agents and the like to obtain the quick-charging graphite. The patent has higher equipment requirement by etching graphite with alkali solution, and meanwhile, the whole stable structure is difficult to form between the coating agent and the graphite, so that the performance of the lithium ion battery is influenced.
Disclosure of Invention
The invention aims to overcome the defects of the graphite anode material in the prior art and provide a graphite anode material precursor, a graphite anode material and a preparation method and application thereof. According to the invention, through a method combining mechanical activation and chemical catalysis, the lithium ion transmission channel of the prepared graphite anode material precursor is increased, and the further prepared graphite anode material has excellent discharge capacity and quick charge performance when being applied to a lithium ion battery.
The invention solves the technical problems through the following technical scheme.
The inventor of the application finds that the metal oxide and the graphite are ball-milled in the research, so that the surface defect of the graphite can be increased, and the catalytic action of the metal oxide can be utilized to etch and pore the surface of the graphite, so that the lithium ion diffusion channel on the surface of the graphite is effectively increased.
The invention provides a preparation method of a graphite anode material precursor, which mainly comprises the following steps: ball milling graphite and metal oxide, and then heat treatment and acid washing treatment;
wherein, the metal oxide accounts for 2-46% of the mass of the graphite, and the percentage refers to the mass percentage of the metal oxide in the graphite; in the ball milling treatment, the rotation speed of the ball milling is 400-1000rpm.
In the invention, the graphite can be artificial graphite or natural graphite.
In the present invention, it is preferable that Dmax of the graphite is 75 μm or less.
In the present invention, preferably, the graphite has a D50.ltoreq.50. Mu.m, more preferably a D50.ltoreq.45. Mu.m, for example, a D50 of 10.5. Mu.m. In the present invention, dmax is the maximum particle diameter of the material, and D50 is the average diameter of the material.
In the present invention, other parameters of the graphite may be as follows: ash content less than or equal to 0.5%, tap density more than or equal to 0.9g/cm 3 Specific surface area of 0.8-3.2m 2 The per gram, the capacity is more than or equal to 340mAh/g, and the first coulomb efficiency is more than or equal to 90 percent.
In some preferred embodiments, the parameters of the graphite are as follows: ash content 0.1%, particle diameter D50 10.5 μm, dmax less than or equal to 31.2 μm, tap density 1.01g/cm 3 Specific surface area 1.83m 2 The capacity per gram is 355mAh/g, and the initial coulomb efficiency is 94.5%.
In the present invention, it is preferable that Dmax of the metal oxide is not more than 100. Mu.m, and more preferable that Dmax of the metal oxide is not more than 76. Mu.m.
In the present invention, preferably, the D50 of the metal oxide is 75 μm or less, preferably 38.4 μm.
In the present invention, the metal in the metal oxide may be selected from one or more of Na, ca, fe, V, ni, li, co, mn, K, mg and Al, for example Ca. In the present invention, the metal in the metal oxide may be a metal conventional in the art.
In the present invention, preferably, the metal oxide accounts for 5-45% of the mass of the graphite, for example, 5%, 15%, 30% or 45%, and the percentage refers to the mass percentage of the metal oxide in the graphite.
In the present invention, the apparatus for the ball milling treatment may be conventional in the art, such as a high-energy ball mill, a planetary ball mill, or a bead mill. The ball milling process can achieve uniform distribution of metal oxides in graphite.
In the ball milling treatment, the rotational speed of the ball milling is preferably 300 to 1000ppm, for example 400rpm, 600rpm, 800rpm or 1000rpm.
In the ball milling treatment, the time of ball milling may be 1 to 12 hours, preferably 1 to 10 hours, for example 1 hour, 4 hours, 7 hours or 10 hours.
In the ball milling process, zirconia or carbide materials, such as tungsten carbide, may be used as the ball milling medium in the present invention.
In the ball milling treatment, the ball matching ratio of the big ball and the small ball in the ball milling medium is (7-9): (3-1), e.g., 7:3.
In the invention, the ball milling treatment process can also comprise the operation of introducing inert atmosphere.
Wherein the inert atmosphere may be conventional in the art, such as nitrogen or helium.
Wherein the inert atmosphere may have a gas flow of 0.2-2L/h, for example 1L/h.
In the present invention, the apparatus for the heat treatment may be conventional in the art, such as an atmosphere furnace. The heat treatment has a certain influence on the etching and pore-forming rate of the graphite surface.
In the present invention, the heat treatment may be performed under an oxidizing atmosphere.
Wherein the oxidizing atmosphere may be air or oxygen.
Wherein the gas flow rate of the oxidizing atmosphere may be 2-30L/h, for example 2L/h, 9L/h, 16L/h, 23L/h or 30L/h.
In the present invention, the temperature of the heat treatment may be 300 to 900 ℃, preferably 400 to 800 ℃, for example 400 ℃, 500 ℃, 600 ℃ or 700 ℃.
In the present invention, the time of the heat treatment may be 1 to 10 hours, preferably 2 to 8 hours, for example, 2 hours, 4 hours, 6 hours or 8 hours.
In the present invention, preferably, the specific surface area of the product after the heat treatment is 1.3 to 7.4m 2 /g。
In the present invention, it is preferable that the particle diameter D50 of the product after the heat treatment is 20 to 30. Mu.m, for example 25. Mu.m.
In the present invention, the acid washing treatment may include the steps of: washing the heat treated product with acid and water to neutrality. The purpose of the acid washing is to remove metal oxides therefrom.
Wherein, in the pickling treatment process, the acid can be dilute hydrochloric acid. The concentration of the dilute hydrochloric acid may be 0.5 to 3mol/L, for example 1mol/L.
Wherein, in the pickling treatment process, mechanical stirring can be carried out simultaneously. The speed of agitation may be in the range of 100-1000rpm.
Wherein, the temperature can be controlled between 30 ℃ and 80 ℃ during the pickling treatment, such as 60 ℃.
Wherein the time of the acid washing treatment may be 1 to 24 hours, for example 10 hours.
In the invention, after the acid washing treatment, the method can also comprise the operation of drying.
Wherein the temperature of the drying may be 100-120 ℃, for example 110 ℃.
The invention also provides a graphite anode material precursor which is prepared by the preparation method.
The invention also provides a preparation method of the graphite anode material, which mainly comprises the following steps: and coating and carbonizing the graphite anode material precursor.
In the present invention, the coating process may include the steps of: and carrying out fusion treatment on the graphite anode material precursor, the coating agent and the cross-linking agent, and then carrying out depolymerization treatment.
Wherein, the coating agent can be resin or high molecular polymer.
The resin may be a thermoplastic or thermosetting resin, preferably one or more of phenolic, epoxy, vinyl, urea-formaldehyde and melamine-formaldehyde resins, for example phenolic.
The high molecular polymer can be one or more of polyaniline, polypyrrole and polyethylene.
Wherein the coating agent may be used in an amount of 1-15%, for example 1%, 5%, 10% or 15%.
Wherein the cross-linking agent may be polyoxymethylene. After the cross-linking agent is added, the cross-linking of graphite and resin can be realized by utilizing fusion treatment, and the structural stability of the hard carbon coated graphite is further improved.
Wherein the crosslinking agent may be used in an amount of 0.1 to 6%, preferably 0.5 to 6%, for example 0.5%, 2%, 4% or 6%.
The apparatus for the fusion process may be conventional in the art, such as a mechanical fusion machine.
Wherein the rotational speed of the fusion treatment may be 200-1100ppm, preferably 300-900rpm, such as 300rpm, 600rpm or 900rpm.
Wherein the time of the fusion treatment may be 200-900s, preferably 200-800s, such as 200s, 400s, 600s or 800s.
Wherein the depolymerization treatment may be performed using a breaker conventional in the art. The depolymerization treatment can control the particle size, is beneficial to improving the compaction density and unit loading capacity of the material and increases the energy density of the battery.
In the present invention, it is preferable that the particle diameter D50 of the product after the heat treatment is 8 to 17. Mu.m, for example 9.8. Mu.m.
In the present invention, the apparatus for the carbonization treatment may be conventional in the art, such as a tube furnace.
In the present invention, the carbonization treatment may be performed under an inert atmosphere.
Wherein the inert atmosphere may be conventional in the art, such as nitrogen, argon or helium.
Wherein the inert atmosphere may have a gas flow rate of 2-20L/h, for example 8.3L/h.
In the present invention, the carbonization treatment may be carried out at a temperature of 800 to 1300 ℃, preferably 900 to 1200 ℃, for example 900 ℃, 1000 ℃, 1100 ℃, or 1200 ℃.
In the present invention, the carbonization treatment may be carried out for a period of 1 to 8 hours, preferably 2 to 6 hours, for example 2 hours, 4 hours or 6 hours.
In the present invention, after the carbonization treatment, a shaping treatment may be further included. The shaping process may be performed using a shaper conventional in the art.
The invention also provides a graphite anode material which is prepared by the preparation method.
In the present invention, the graphite anode material may have a particle diameter of 9.8 to 12.4 μm, for example, 9.8 μm, 10.1 μm, 10.2 μm, 10.3 μm, 10.4 μm, 10.5 μm, 10.6 μm, 10.7 μm, 10.8 μm, 10.9 μm, 11.0 μm, 11.1 μm, 11.2 μm, 11.3 μm, 11.4 μm, 11.5 μm, 11.6 μm, 11.7 μm, 11.9 μm, 12.2 μm or 12.4 μm.
In the invention, the tap density of the graphite anode material can be 0.92-1.09g/cm 3 For example 0.92g/cm 3 、0.98g/cm 3 、1.01g/cm 3 、1.02g/cm 3 、1.03g/cm 3 、1.04g/cm 3 、1.05g/cm 3 、1.06g/cm 3 、1.07g/cm 3 、1.08g/cm 3 Or 1.09g/cm 3 。
In the invention, the specific surface area of the graphite anode material can be 2.0-3.4m 2 /g, e.g. 2.0m 2 /g、2.1m 2 /g、2.2m 2 /g、2.3m 2 /g、2.4m 2 /g、2.5m 2 /g、2.6m 2 /g、2.7m 2 /g、2.8m 2 /g、2.9m 2 /g、3.0m 2 /g、3.1m 2 /g、3.2m 2 /g、3.3m 2 /g or 3.4m 2 /g。
The invention also provides an application of the graphite anode material precursor or the graphite anode material in a lithium ion battery.
On the basis of conforming to the common knowledge in the field, the above preferred conditions can be arbitrarily combined to obtain the preferred examples of the invention.
The reagents and materials used in the present invention are commercially available.
The invention has the positive progress effects that:
(1) The invention increases the surface defect and active site of the graphite material by using the ball milling process, reduces the activation energy of the graphite material, changes the surface structure of the graphite and increases the lithium ion transmission channel on the surface of the graphite; and then, the catalytic action of the metal oxide on the carbon material and air or oxygen is utilized, so that the etching and pore-forming of the graphite surface are realized, and the lithium ion migration channel is increased, thereby improving the charging efficiency of the subsequent battery.
(2) Further, by utilizing the characteristics of a pore structure rich in hard carbon and a short-range carbon layer stack, the migration distance of the lithium ion battery is shortened, and the transmission channel of lithium ions is increased; in the coating treatment process, the composite of the coating layer and the graphite matrix is realized, and the bonding strength of the coating layer and the graphite matrix is enhanced; and a three-dimensional reticular coating structure is formed after carbonization, so that the overall structural stability of the negative electrode hard carbon coated negative electrode is improved, and the effective improvement of the rate performance charging efficiency of the negative electrode of the lithium battery is realized.
(3) According to the invention, through a method combining mechanical activation and chemical catalysis, the lithium ion transmission channel of the prepared graphite anode material precursor is increased, and the further prepared graphite anode material has excellent discharge capacity and quick charge performance when being applied to a lithium ion battery.
Drawings
Fig. 1 is an SEM image of the graphite anode material prepared in example 1.
Detailed Description
The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications.
In the examples and comparative examples of the present invention, graphite characteristics used were as follows: ash content 0.1%, particle diameter D50 10.5 μm, dmax less than or equal to 31.2 μm, tap density 1.01g/cm 3 Specific surface area 1.83m 2 The capacity per gram is 355mAh/g, and the initial coulomb efficiency is 94.5%.
Example 1
S1: ball milling: taking a certain amount of graphite and metal oxide (calcium oxide, particle size: dmax is less than or equal to 76 mu m, D50 is 38.4 mu m), wherein the mass of the metal oxide accounts for 15% of the mass of the graphite, and directly loading the graphite and the metal oxide into a high-energy ball mill. Introducing nitrogen with the flow of 1L/h, performing ball milling treatment, adopting tungsten carbide as a ball milling medium, wherein the ball mixing ratio of the large ball to the small ball is 7:3, the rotating speed of the ball mill is 800rpm, and the ball milling time is 7h. And (5) obtaining a mixture of graphite and metal oxide after ball milling.
S2: and (3) heat treatment: and (3) placing the mixture of graphite and metal oxide into an atmosphere furnace, heating to 600 ℃ in air atmosphere at the air flow rate of 9L/h, and preserving heat for 6h to obtain a heat treatment product after heat treatment is finished. The specific surface area of the product was 4.1m 2 The particle diameter D50 is 25 μm.
S3: acid washing: and (3) carrying out acid washing on the heat treatment product under the condition of 60 ℃ by adopting dilute hydrochloric acid with the concentration of 1mol/L for 10 hours, washing with water after washing, washing to neutrality, removing metal oxide, and drying at the temperature of 110 ℃ to obtain the coating precursor.
S4: coating: the coating precursor, 5% of phenolic resin and 4% of trioxymethylene are added into a fusion machine to be fused, and the fusion parameters are as follows: rotational speed 600rpm, time 400s. And after the fusion is finished, carrying out depolymerization treatment by adopting a scattering machine. The particle size D50 of the product was 9.8. Mu.m.
S5: high-temperature carbonization treatment: and placing the product after the coating treatment in a tube furnace, introducing nitrogen, wherein the flow rate of the nitrogen is 8.3L/h, heating to 1100 ℃, preserving heat for 4 hours, after carbonization treatment, shaping treatment by a shaping machine, and obtaining the required graphite anode material after treatment, wherein the anode material D50 is 10.5 mu m.
An SEM image of the prepared graphite anode material is shown in fig. 1.
Example 2
Example 2 differs from example 1 in the parameter step in that the amount of metal oxide added in step S1 (see table 1) was adjusted, and the rest of the process was the same as in example 1.
TABLE 1
Examples Addition amount of metal oxide (%)
Example 2.1 5
Example 2.2 15
Example 2.3 30
Example 2.4 45
Example 3
Example 3 differs from example 1 in the parameter step in that the rotational speed of the ball mill in step S1 (see table 2) was adjusted, and the rest of the process was the same as in example 1.
TABLE 2
Example 4
Example 4 differs from example 1 in the parameter step in that the ball milling time in step S1 (see table 3) was adjusted and the rest of the process was the same as example 1.
TABLE 3 Table 3
Examples Ball milling time (h)
Example 4.1 1
Example 4.2 4
Example 4.3 7
Example 4.4 10
Example 5
Example 5 differs from example 1 in the parameter step in that the flow rate of the oxidizing gas in step S2 (see table 4) was adjusted, and the rest of the process was the same as in example 1.
TABLE 4 Table 4
Examples Flow (L/h)
Example 5.1 2
Example 5.2 9
Example 5.3 16
Example 5.4 23
Example 5.5 30
Example 6
Example 6 differs from example 1 in the parameter step in that the heat treatment temperature is adjusted in step S2 (see table 5), and the rest of the process is the same as example 1.
TABLE 5
Examples Heat treatment temperature (. Degree. C.)
Example 6.1 400
Example 6.2 500
Example 6.3 600
Example 6.4 700
Example 7
Example 7 differs from example 1 in the parameter step in that the incubation time in step S2 (see table 6) was adjusted and the rest of the process was the same as example 1.
TABLE 6
Examples Time of thermal insulation (h)
Example 7.1 2
Example 7.2 4
Example 7.3 6
Example 7.4 8
Example 8
Example 8 differs from example 1 in the parameter step in that the fusion speed in step S4 (see table 7) was adjusted, and the rest of the process was the same as example 1.
TABLE 7
Examples Fusion speed (rpm)
Example 8.1 300
Example 8.2 600
Example 8.3 900
Example 9
Example 9 differs from example 1 in the parameter step in that the fusion time in step S4 (see table 8) was adjusted, and the rest of the process was the same as example 1.
TABLE 8
Examples Fusion time(s)
Example 9.1 200
Example 9.2 400
Example 9.3 600
Example 9.4 800
Example 10
Example 10 differs from example 1 in the parameter step in that the amount of the phenolic resin of the coating agent added in step S4 (see table 9) was adjusted, and the rest of the process was the same as in example 1.
TABLE 9
Examples Additive amount of coating agent (%)
Example 10.1 1
Example 10.2 5
Example 10.3 10
Example 10.4 15
Example 11
Example 11 differs from example 1 in the parameter step in that the amount of trioxymethylene added in step S4 (see table 10) was adjusted, and the rest of the process was the same as example 1.
Table 10
Examples Addition amount of trioxymethylene (%)
Example 11.1 0.5
EXAMPLE 11.2 2
Example 11.3 4
Example 11.4 6
Example 12
Example 12 differs from example 1 in the step of adjusting the carbonization temperature in step S5 (see table 11), and the rest of the process is the same as example 1.
TABLE 11
Examples Carbonization temperature (. Degree. C.)
Example 12.1 900
Example 12.2 1000
Example 12.3 1100
Example 12.4 1200
Example 13
Example 13 differs from example 1 in the parameter step of adjusting the carbonization incubation time in step S5 (see table 12), and the rest of the process is the same as example 1.
Table 12
Examples Time of thermal insulation (h)
Example 13.1 2
Example 13.2 4
Example 13.3 6
Comparative example 1
S1: ball milling: taking a certain amount of graphite and metal oxide (calcium oxide, particle size: dmax is less than or equal to 76 mu m, D50 is 38.4 mu m), wherein the mass of the metal oxide accounts for 15% of the mass of the graphite, and directly loading the graphite and the metal oxide into a high-energy ball mill. Introducing nitrogen with the flow of 1L/h, performing ball milling treatment, adopting tungsten carbide as a ball milling medium, wherein the ball mixing ratio of the large ball to the small ball is 7:3, the rotating speed of the ball mill is 100rpm, and the ball milling time is 1h. And (5) obtaining a mixture of graphite and metal oxide after ball milling.
S2: and (3) heat treatment: placing the mixture of graphite and metal oxide into an atmosphere furnace, heating to 300 ℃ in air atmosphere at air flow rate of 9L/h, and preserving heat for 1h to obtain a heat treatment product after heat treatment. The specific surface area of the product was 1.7m 2 The particle diameter D50 was 32. Mu.m.
S3: acid washing: and (3) carrying out acid washing on the heat treatment product under the condition of 60 ℃ by adopting dilute hydrochloric acid with the concentration of 1mol/L for 10 hours, washing with water after washing, washing to neutrality, removing metal oxide, and drying at the temperature of 110 ℃ to obtain the coating precursor.
S4: coating: the coating precursor, 1% of phenolic resin and 0.1% of trioxymethylene are added into a fusion machine for fusion treatment, and the fusion parameters are as follows: rotational speed 200rpm, time 400s. And after the fusion is finished, carrying out depolymerization treatment by adopting a scattering machine. The particle size D50 of the product was 10.9. Mu.m.
S5: high-temperature carbonization treatment: and placing the product after the coating treatment in a tube furnace, introducing nitrogen, wherein the flow rate of the nitrogen is 8.3L/h, heating to 800 ℃, preserving heat for 4 hours, after carbonization treatment, shaping treatment by a shaping machine, and obtaining the required graphite anode material after treatment, wherein the D50 of the anode material is 10.3 mu m.
Comparative example 2
S1: ball milling: taking a certain amount of graphite and metal oxide (calcium oxide, the grain diameter is Dmax is less than or equal to 76 mu m, D50 is 38.4 mu m), wherein the mass of the metal oxide accounts for 50% of the mass of the graphite, and directly loading the graphite and the metal oxide into a high-energy ball mill. Introducing nitrogen with the flow of 1L/h, performing ball milling treatment, adopting tungsten carbide as a ball milling medium, wherein the ball mixing ratio of the big ball to the small ball is 7:3, the rotating speed of the ball mill is 1100rpm/min, and the ball milling time is 10h. And (5) obtaining a mixture of graphite and metal oxide after ball milling.
S2: and (3) heat treatment: and (3) placing the graphite and metal oxide mixture into an atmosphere furnace, heating to 800 ℃ in the air atmosphere at the air flow rate of 9L/h, and preserving the heat for 12h to obtain a heat treatment product after the heat treatment is finished. The specific surface area of the product was 8.3m 2 The particle diameter D50 is 28 μm.
S3: acid washing: and (3) carrying out acid washing on the heat treatment product under the condition of 60 ℃ by adopting dilute hydrochloric acid with the concentration of 1mol/L for 10 hours, washing with water after washing, washing to neutrality, removing metal oxide, and drying at the temperature of 110 ℃ to obtain the coating precursor.
S4: coating: the coating precursor, 1% of phenolic resin and 0.1% of trioxymethylene are added into a fusion machine for fusion treatment, and the fusion parameters are as follows: the rotation speed is 1100rmp rpm, and the time is 900s. And after the fusion is finished, carrying out depolymerization treatment by adopting a scattering machine. The particle size D50 of the product was 11.2. Mu.m.
S5: high-temperature carbonization treatment: and placing the product after the coating treatment in a tube furnace, introducing nitrogen, wherein the flow rate of the nitrogen is 8.3L/h, heating to 1300 ℃, preserving heat for 2h, after carbonization treatment, shaping treatment by a shaping machine, and obtaining the required graphite anode material after treatment, wherein the D50 of the anode material is 10.7 mu m.
Comparative example 3
The graphite was not treated.
Effect examples
Particle size was measured using a Markov Mastersizer 3000, BET was measured using a Mitstar IIplus, and tap density was measured using a Dandong hundred BT-310 series tap densitometer.
The electrochemical performance test procedure was as follows:
the prepared graphite cathode material, conductive carbon black and PVDF are mixed according to the following proportion of 90:4:2, dissolving the mixture into a certain amount of NMP, stirring for 30min, coating the slurry on an aluminum foil, and drying in a vacuum drying oven for 24h. After drying, the aluminum foil was cut into 12mm disks with a loading of 26.8 μg. The positive electrode adopts the treated material, the negative electrode adopts a lithium sheet, the diaphragm adopts a Celgard2500 polypropylene film, the electrolyte adopts 1mol/L lithium hexafluorophosphate (New Safton), and the lithium ion battery is assembled according to a 2032 type battery (the technical personnel in the field know that under normal conditions, when the material to be tested and the metal lithium are assembled into a half battery, the material to be tested is often used as the positive electrode due to lower hydrogen standard potential of the metal lithium).
After the assembled battery is stood for 24 hours, testing is carried out above a new Wei battery CT-4000 test, and the testing conditions are as follows: before the test, the activation is carried out by using 0.05C small current, and then 200 circles of test are carried out under the conditions of 0.1C and 8C respectively, so as to obtain the first capacity and the capacity retention rate under different multiplying powers.
The test results are shown in table 13 below:
TABLE 13
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As is clear from the above table, examples 1 to 13 can achieve a 0.1C discharge capacity of 352.4 to 358.2mAh, an 8C discharge capacity of 308.9 to 324.7mAh, and an 8C/0.1C capacity retention rate of 87.00 to 90.99%.
Comparative examples 1 and 2 can maintain comparable discharge capacities at 0.1C as compared with examples 1 to 13; however, when the current was increased to 8C, the discharge capacity was 295.6 to 297.2mAh, and the capacity retention rate of 8C/0.1C was 84% or so, which was significantly lower than in examples 1 to 13. This is probably due to the fact that the ball milling speed in comparative example 1 is too low under the condition of high multiplying power, so that the etching degree of the graphite surface is insufficient, the lithium ion rapid transmission channels are fewer, and the requirement under the condition of high multiplying power cannot be met. In comparative example 2, however, the excessive addition of metal oxide caused excessive reaction of graphite with air/oxygen due to too high ball milling speed, and resulted in more defects. The specific capacity is related to the graphitization degree, and the graphitization degree is reduced by etching and pore forming, so that the capacity and the capacity retention rate are reduced under the condition of high multiplying power.
Example 2 the addition amount of the metal oxide was changed on the basis of example 1, and the 0.1C discharge capacities did not differ much with the increase of the addition amount of the metal oxide; the 8C discharge capacity and the 8C/0.1C capacity retention rate are increased and then reduced, and when the addition amount of the metal oxide is 15%, the discharge capacity and the capacity retention rate reach the highest, namely 321.1mAh and 90.78%, respectively.
Examples 3 to 13 each had varied the rotational speed of the ball mill, the ball milling time, the flow rate of the oxidizing gas, the heat treatment temperature, the holding time, the fusion rotational speed, the fusion time, the addition amount of the coating agent resin, the addition amount of the trioxymethylene, the carbonization temperature and the carbonization holding time on the basis of example 1, and had fluctuation in the conventional ranges of the 0.1C discharge capacity, the 8C discharge capacity and the 8C/0.1C capacity retention rate.

Claims (10)

1. The preparation method of the graphite anode material precursor is characterized by mainly comprising the following steps: ball milling graphite and metal oxide, and then heat treatment and acid washing treatment;
wherein, the metal oxide accounts for 2-46% of the mass of the graphite, and the percentage refers to the mass percentage of the metal oxide in the graphite; in the ball milling treatment, the rotation speed of the ball milling is 400-1000rpm.
2. The method for preparing a graphite anode material precursor according to claim 1, wherein the graphite is artificial graphite or natural graphite;
and/or Dmax of the graphite is less than or equal to 75 mu m;
and/or D50 of the graphite is less than or equal to 50 mu m; preferably, D50.ltoreq.45. Mu.m;
and/or, other parameters of the graphite are as follows: ash content less than or equal to 0.5%, tap density more than or equal to 0.9g/cm 3 Specific surface area of 0.8-3.2m 2 The per gram, the capacity is more than or equal to 340mAh/g, and the first coulomb efficiency is more than or equal to 90%;
and/or Dmax of the metal oxide is less than or equal to 100 mu m; preferably, the particle size Dmax of the metal oxide is less than or equal to 76 mu m;
and/or D50 of the metal oxide is less than or equal to 75 mu m;
and/or, in the metal oxide, a metal is selected from one or more of Na, ca, fe, V, ni, li, co, mn, K, mg and Al, such as Ca;
and/or, the metal oxide accounts for 5-45%, such as 5%, 15%, 30% or 45% of the mass of the graphite, and the percentage refers to the mass percentage of the metal oxide to the graphite.
3. The method for preparing a graphite anode material precursor according to claim 1, wherein in the ball milling treatment, the rotational speed of the ball milling is 300-1000ppm, such as 400rpm, 600rpm, 800rpm or 1000rpm;
and/or, in the ball milling treatment, the ball milling time is 1 to 12 hours, preferably 1 to 10 hours, for example 1 hour, 4 hours, 7 hours or 10 hours;
and/or, in the ball milling treatment, zirconia or carbide materials are adopted as a ball milling medium;
and/or, in the ball milling treatment, the ball matching ratio of the big ball and the small ball in the ball milling medium is (7-9): (3-1);
and/or, the ball milling treatment process further comprises the operation of introducing inert atmosphere; the gas flow rate of the inert atmosphere is preferably 0.2-2L/h.
4. The method for preparing a graphite anode material precursor according to claim 1, wherein the heat treatment is performed under an oxidizing atmosphere; the oxidizing atmosphere is preferably air or oxygen; the gas flow rate of the oxidizing atmosphere is preferably 2 to 30L/h, for example 2L/h, 9L/h, 16L/h, 23L/h or 30L/h;
and/or the temperature of the heat treatment is 300-900 ℃, preferably 400-800 ℃, such as 400 ℃, 500 ℃, 600 ℃ or 700 ℃;
and/or the heat treatment is for a period of time of 1 to 10 hours, preferably 2 to 8 hours, for example 2 hours, 4 hours, 6 hours or 8 hours;
and/or, after the heat treatment, the specific surface area of the product is 1.3-7.4m 2 /g；
And/or, after said heat treatment, the product has a particle size D50 of 20-30 μm, for example 25 μm.
5. The method for preparing a graphite anode material precursor according to claim 1, wherein the acid washing treatment comprises the steps of: washing the heat-treated product with acid and water to neutrality;
wherein, in the pickling treatment process, the acid is preferably dilute hydrochloric acid; the concentration of the dilute hydrochloric acid is preferably 0.5-3mol/L;
wherein, in the pickling treatment process, mechanical stirring can be carried out simultaneously; the speed of stirring is preferably 100-1000rpm;
wherein, in the pickling treatment process, the temperature is preferably controlled at 30-80 ℃;
wherein the time of the acid washing treatment is preferably 1-24 hours;
and/or, after the pickling treatment, the method further comprises the operation of drying; the temperature of the drying is preferably 100-120 ℃.
6. A graphite anode material precursor, characterized in that it is produced by the production method according to any one of claims 1 to 5.
7. The preparation method of the graphite anode material is characterized by mainly comprising the following steps of: the graphite anode material precursor according to claim 6 is subjected to coating treatment and carbonization treatment.
8. The method for preparing a graphite anode material according to claim 7, wherein the coating treatment comprises the steps of: carrying out fusion treatment on the graphite anode material precursor, a coating agent and a crosslinking agent, and then carrying out depolymerization treatment;
wherein the coating agent is preferably resin or high molecular polymer;
the resin is preferably a thermoplastic or thermosetting resin, more preferably one or more of a phenolic resin, an epoxy resin, a vinyl resin, a urea resin and a melamine formaldehyde resin;
the high molecular polymer is preferably one or more of polyaniline, polypyrrole and polyethylene;
wherein the coating agent is preferably used in an amount of 1-15%, such as 1%, 5%, 10% or 15%;
wherein the cross-linking agent is preferably trioxymethylene;
wherein the crosslinking agent is preferably used in an amount of 0.1-6%, more preferably 0.5-6%, such as 0.5%, 2%, 4% or 6%;
wherein the rotational speed of the fusion treatment is preferably 200-1100ppm, more preferably 300-900rpm, such as 300rpm, 600rpm or 900rpm;
wherein the time of the fusion treatment is preferably 200-900s, more preferably 200-800s, such as 200s, 400s, 600s or 800s;
and/or, after said heat treatment, the product has a particle size D50 of 8-17 μm;
and/or, the carbonization treatment is performed under an inert atmosphere; the gas flow rate of the inert atmosphere is preferably 2-20L/h;
and/or the carbonization treatment is carried out at a temperature of 800-1300 ℃, preferably 900-1200 ℃, such as 900 ℃, 1000 ℃, 1100 ℃ or 1200 ℃;
and/or the carbonization treatment is carried out for a period of time ranging from 1 to 8 hours, preferably from 2 to 6 hours, for example 2 hours, 4 hours or 6 hours;
and/or, after the carbonization treatment, a shaping treatment is further included.
9. A graphite anode material, characterized in that it is produced by the production method according to claim 7 or 8.
10. Use of a graphite anode material precursor according to claim 6 or a graphite anode material according to claim 9 in a lithium ion battery.
CN202311460147.4A 2023-11-03 2023-11-03 Graphite anode material precursor, graphite anode material, and preparation method and application thereof Pending CN117416955A (en)

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