CN114843508A - Modified natural graphite material, preparation method thereof, negative electrode plate and lithium ion battery - Google Patents
Modified natural graphite material, preparation method thereof, negative electrode plate and lithium ion battery Download PDFInfo
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Classifications
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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
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
Abstract
The application provides a modified natural graphite material, a preparation method thereof, a negative electrode plate and a lithium ion battery, and relates to the technical field of battery negative electrode materials. The modified natural graphite material comprises a natural graphite matrix; non-graphitized carbon, at least a portion of the pores within the natural graphite matrix being filled with the non-graphitized carbon; the pore volume of the modified natural graphite material is 0.004cm 3 /g～0.009cm 3 (ii) in terms of/g. The problems of high expansion rate and poor cycle performance of the conventional natural graphite cathode material can be solved.
Description
Technical Field
The application relates to the technical field of battery negative electrode materials, in particular to a modified natural graphite material, a preparation method thereof, a negative electrode plate and a lithium ion battery.
Background
At present, in order to reduce the dependence on petroleum and improve the national energy safety, the development of pure electric vehicles has become a Chinese national strategy. However, the existing pure electric vehicles still do not realize real marketization due to high cost. Among them, the power battery is an important component of the electric vehicle, and the power battery generally occupies 1/3 or more of the cost of the whole vehicle, so how to reduce the cost of the power battery becomes a major concern of the industry.
The negative electrode material is an important component of the power battery and determines the performance and cost of the battery. At present, the main material of the negative electrode material is still graphite material, and graphite can be divided into artificial graphite and natural graphite according to different material preparation processes or sources. Among them, artificial graphite is generally obtained through a heat treatment process at about 3000 ℃, which is costly, thus resulting in a high price of artificial graphite. The natural graphite comes from nature, the raw material has very high graphitization degree, the graphitization process is not carried out, and the cost is relatively low. However, since the natural graphite particles are obtained by crushing flake graphite, compared with artificial graphite, the natural graphite particles have a very large number of pore structures inside, when the natural graphite particles are used as a negative electrode material, electrolyte can permeate into the material particles, and a large number of side reactions can be generated in the lithium ion intercalation process, so that the defects of poor cycle performance, poor safety performance and the like of the battery are caused. Therefore, how to improve the application properties of natural graphite has become an important research topic.
Although some methods for modifying natural graphite, such as a method using solid phase coating, have been developed in the prior art. However, the coating modification mode adopted at the present stage cannot effectively improve the internal pores of the natural graphite particles, so that side reactions repeatedly occur in the circulation process, and the natural graphite cathode material has high expansion rate and poor circulation performance. Therefore, it is necessary to develop a new method for modifying natural graphite and a new modified natural graphite material, thereby improving the cycle performance of natural graphite and reducing the expansion rate of a natural graphite electrode.
Disclosure of Invention
The application aims to provide a modified natural graphite material and a preparation method thereof, a negative electrode plate and a lithium ion battery, wherein the modified natural graphite material has a particle section structure similar to artificial graphite, and the novel negative electrode material containing the modified natural graphite material has lower expansion rate and more outstanding cycle performance by the structure, so that the problems of high expansion rate and poor cycle performance of the conventional natural graphite negative electrode material can be solved.
In order to achieve the purpose, the technical scheme adopted by the application is as follows:
according to a first aspect of the present application there is provided a modified natural graphite material comprising:
a natural graphite matrix;
non-graphitized carbon, at least a portion of the pores within the natural graphite matrix being filled with the non-graphitized carbon;
the pore volume of the modified natural graphite material is 0.004cm 3 /g～0.009cm 3 /g。
According to the modified natural graphite material, the non-graphitized carbon enters the natural graphite matrix, namely at least part of pores in the natural graphite matrix are filled with the non-graphitized carbon, so that the pore volume of the modified natural graphite material is greatly reduced, and the modified natural graphite material with a particle section structure similar to that of artificial graphite can be obtained. Therefore, the problems that the internal surface of the natural graphite pore cannot be effectively improved by adopting a coating modification mode at the present stage, so that side reactions repeatedly occur in the circulation process, and the natural graphite cathode material has high expansion rate and poor circulation performance can be solved.
In one possible embodiment, the modified natural graphite material has at least one of the following features a) to c):
a) the non-graphitized carbon is arranged on at least part of the outer surface of the natural graphite matrix;
b) the non-graphitized carbon is formed by carbonizing and converting carbon-containing organic matters;
c) the softening point temperature of the carbon-containing organic matter is 20-300 ℃; and/or the carbon-containing organic matter comprises at least one of petroleum asphalt, coal asphalt, mesophase asphalt, phenolic resin, epoxy resin, coal tar and heavy oil.
The pores in the natural graphite matrix of the modified natural graphite material are filled with non-graphitized carbon, and the surface of the natural graphite matrix of the modified natural graphite material can also be coated with the non-graphitized carbon.
In a possible embodiment, the modified natural graphite material has at least one of the following features d) to f):
d) the particle size D50 of the modified natural graphite material is 8-25 μm;
e) the tap density of the modified natural graphite material is 1.0 g/cc-1.3 g/cc;
f) the specific surface area of the modified natural graphite material is 0.8m 2 /g～1.4m 2 /g。
According to a second aspect of the present application, there is provided a method of preparing a modified natural graphite material, comprising the steps of:
mixing a natural graphite raw material with a first modifier to obtain a first mixture;
heating the first mixture to a first temperature, vacuumizing, and sequentially carrying out first heat preservation, heating to a second temperature, second heat preservation and cooling to a third temperature; and
adding a second modifier to the first mixture to obtain a second mixture;
heating the second mixture to a first temperature, vacuumizing, and sequentially carrying out primary heat preservation, heating to a second temperature, secondary heat preservation and cooling to a third temperature to obtain the modified natural graphite material;
wherein the modified natural graphite material comprises a natural graphite matrix and non-graphitized carbon; at least a portion of the pores within the natural graphite matrix are filled with the non-graphitizing carbon;
the pore volume of the modified natural graphite material is 0.004cm 3 /g～0.009cm 3 /g。
According to the preparation method, through the design of vacuumizing, namely negative pressure, multiple times of dipping and the like, the improver can enter the natural graphite, the pores in the natural graphite are greatly reduced, and a particle section structure similar to that of artificial graphite is obtained, so that the problems that the inner surfaces of the pores of the natural graphite cannot be effectively improved by adopting a coating modification mode at the present stage, side reactions repeatedly occur in the circulation process, and the natural graphite cathode material is high in expansion rate and poor in circulation performance can be solved.
In one possible embodiment, the modified natural graphite material has at least one of the following features a) to f):
a) the non-graphitized carbon is arranged on at least part of the outer surface of the natural graphite matrix;
b) the first modifier and the second modifier are both carbon-containing organic matters, and the non-graphitized carbon is converted from the carbon-containing organic matters through carbonization treatment;
c) the softening point temperature of the carbon-containing organic matter is 20-300 ℃; and/or the carbon-containing organic matter comprises at least one of petroleum asphalt, coal asphalt, mesophase asphalt, phenolic resin, epoxy resin, coal tar and heavy oil;
d) the particle size D50 of the modified natural graphite material is 8-25 μm, and further can be 9-19 μm;
e) the tap density of the modified natural graphite material is 1.0g/cc to 1.3g/cc, and further 1.05g/cc to 1.2 g/cc; (ii) a
f) The specific surface area of the modified natural graphite material is 0.8m 2 /g～1.4m 2 A total of 0.85 to 1.25m 2 /g。
The pore volume of the modified natural graphite material can be further 0.0042-0.0085 cm 3 /g。
In a possible embodiment, the preparation method satisfies at least one of the following conditions g) to m):
g) the pressure of the vacuum environment is-0.15 MPa to-0.05 MPa;
h) the first temperature is at least 30 ℃ above the softening point temperature of the first modifier/second modifier;
i) the first heat preservation time is 1-3 h;
j) the second temperature is 620-680 ℃;
k) the time for the second heat preservation is 1-3 h;
l) the third temperature is the softening point temperature of the first/second modifier;
m) the ratio of the mass of the natural graphite raw material to the total mass of the first modifier and the second modifier is 95: 5-70: 30.
in a possible embodiment, the method further comprises the step of pretreating the natural graphite raw material before mixing the natural graphite raw material with the first modifier;
and/or, the pre-treatment comprises crushing, grading and shaping the natural graphite raw material;
and/or the natural graphite raw material comprises at least one of scale-shaped natural graphite, microcrystalline graphite and spherical natural graphite.
In one possible embodiment, the pretreated natural graphite starting material has at least one of the following characteristics p) to t):
p) the particle size D50 of the pretreated natural graphite raw material is 6-25 μm;
q) the particle size D90/D10 of the pretreated natural graphite raw material is 1.5-3.5;
s) the tap density of the pretreated natural graphite raw material is 0.7 g/cc-1.0 g/cc;
t) the specific surface area of the pretreated natural graphite raw material is 6m 2 /g～10m 2 /g。
Optionally, the pretreated natural graphite raw material may be in the form of particles, and further may be in the form of at least one of spheres, spheroidal (approximately spherical), ovoid, and the like.
The preparation method of the invention can not only fill gaps in natural graphite particles such as spherical particles or quasi-spherical particles, but also achieve the effect of coating the surfaces of the particles.
Optionally, the mixing manner may be mechanical mixing.
Optionally, the method further comprises a post-treatment step, and the temperature can be reduced by adopting a condensation temperature reduction mode before the post-treatment step.
Optionally, the post-processing comprises: and sequentially carrying out heat treatment, crushing and sieving treatment on the obtained material to obtain the modified natural graphite material.
Wherein the temperature of the heat treatment is 950 ℃ to 1350 ℃, and further 1000 ℃ to 1300 ℃.
It is to be noted that the above numerical ranges are inclusive of the endpoints.
According to a third aspect of the present application, there is provided a negative electrode tab comprising a modified natural graphite material as described above.
Specifically, the negative electrode plate comprises a current collector and a negative active material coated on the current collector, wherein the negative active material comprises the modified natural graphite material.
According to a fourth aspect of the present application, there is provided a lithium ion battery comprising a negative electrode sheet as described above.
The lithium ion battery comprises a negative pole piece, a positive pole piece, a diaphragm, electrolyte and a shell, wherein the negative pole piece comprises a current collector and a negative active material coated on the current collector, and the negative active material comprises the modified natural graphite material.
The lithium ion battery provided by the fourth aspect of the invention has a low electrode expansion rate and excellent cycle performance.
Compared with the prior art, the technical scheme provided by the application can achieve the following beneficial effects:
the modified natural graphite material and the preparation method thereof provided by the application have the advantages that the design of vacuumizing, namely negative pressure operation, multiple times of impregnation and the like is carried out, the modifier can be fully filled in the pores in the natural graphite, the particle section structure similar to the artificial graphite can be obtained, namely, at least part of pores in the natural graphite matrix can be filled with non-graphitized carbon, the pores in the natural graphite are greatly reduced, and therefore the modification is greatly reducedThe pore volume of the natural graphite material is reduced to 0.004-0.009 cm 3 In the range of/g. In addition, the preparation method can achieve the effect of coating the graphite surface while filling the internal pores of the graphite, and can realize the synchronous modification and integration of the defect sites on the internal and external surfaces of the natural graphite, thereby improving the cycle performance and other electrochemical properties of the natural graphite material and relieving the problem of high expansion rate of a natural graphite electrode. The modified natural graphite material is suitable for lithium ion batteries for electronic equipment such as mobile phones, computers, digital cameras and the like and lithium ion batteries for electric automobiles. The preparation method of the modified natural graphite material has the advantages of simple process, low cost, easy operation and control, higher practicability and suitability for expanded large-scale production.
The negative pole piece and the lithium ion battery comprise the modified natural graphite material, have all the characteristics and advantages of the modified natural graphite material and the preparation method thereof, and are not repeated herein.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
In order to more clearly illustrate the detailed description of the present application or the technical solutions in the prior art, the drawings needed to be used in the detailed description of the present application or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a scanning electron microscope test chart of a pretreated natural graphite raw material provided in example 1 of the present application;
fig. 2 is a scanning electron microscope test chart of a modified natural graphite material provided in example 1 of the present application;
fig. 3 is a scanning electron microscope test chart of the modified natural graphite material provided in comparative example 1 of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the following embodiments and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. Those who do not specify the conditions are performed according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
It should be noted that:
the term "and/or" as used herein is merely an associative relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone.
In the present invention, all the embodiments and preferred methods mentioned herein can be combined with each other to form a new technical solution, if not specifically stated. In the present invention, all the technical features mentioned herein and preferred features may be combined with each other to form a new technical solution, if not specifically stated.
In the present invention, unless otherwise stated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, including a and b, and both a and b are real numbers. For example, a numerical range of "20 to 300" means that all real numbers between "20 to 300" have been listed herein, and "20 to 300" is simply a shorthand representation of the combination of these values. The "ranges" disclosed herein may have one or more lower limits and one or more upper limits, respectively, in the form of lower limits and upper limits.
Unless defined or indicated otherwise, technical and scientific terms used herein have the same meaning as is familiar to those skilled in the art. In addition, any methods or materials similar or equivalent to those described herein can also be used in the present invention.
Currently, in lithium ion batteries, a negative electrode material, particularly a negative electrode active material, is one of key materials influencing the electrochemical performance of the lithium ion battery, and plays a key role in the comprehensive performance of the battery. The negative active material of the current commercial lithium ion battery is still the graphite material, but the internal of the existing natural graphite material has a great number of pore structures, which affect the application performance of the material and need to be modified. However, as understood by those skilled in the art, as mentioned in the background art, the coating modification adopted at the present stage cannot effectively improve the inner surface of the pores of the natural graphite material, so that side reactions repeatedly occur in the circulation process, and the natural graphite negative electrode material has high expansion rate and poor circulation performance.
Therefore, in order to overcome the defects of the prior art, the technical scheme of the embodiment of the invention provides a modified natural graphite material, a preparation method thereof, a negative electrode plate and a lithium ion battery, so as to obtain the modified natural graphite negative electrode material with a highly compact interior, wherein the material has a particle section structure similar to artificial graphite, and the structure enables the novel negative electrode material to have a lower expansion rate and more outstanding cycle performance.
Specifically, embodiments of the present application provide a modified natural graphite material that can be used as a negative active material. The modified natural graphite material comprises a natural graphite matrix and non-graphitized carbon, wherein at least part of pores in the natural graphite matrix are filled with the non-graphitized carbon; the pore volume of the modified natural graphite material is 0.004cm 3 /g～0.009cm 3 /g。
The non-graphitized carbon in the modified natural graphite material enters the natural graphite matrix, namely most of the pores in the natural graphite matrix are filled with the non-graphitized carbon, so that the pore volume of the modified natural graphite material is greatly reduced, and the modified natural graphite material with a particle section structure similar to that of artificial graphite can be obtained. Therefore, the modified natural graphite material can inhibit the volume expansion of the material and improve the cycle performance of the material.
In addition, the non-graphitized carbon is filled in the internal pores of the natural graphite matrix of the modified natural graphite material, and the surface of the natural graphite matrix of the modified natural graphite material can also be coated with the non-graphitized carbon.
Wherein, the modified dayThe pore volume of the graphite material was 0.004cm 3 /g～0.009cm 3 A,/g, further 0.0042cm 3 /g～0.0085cm 3 (ii)/g; typically, but not by way of limitation, the pore volume of the modified natural graphite material may be 0.004cm 3 /g、0.0042cm 3 /g、0.0045cm 3 /g、0.0048cm 3 /g、0.005cm 3 /g、0.0055cm 3 /g、0.006cm 3 /g、0.0065cm 3 /g、0.0068cm 3 /g、0.007cm 3 /g、0.0075cm 3 /g、0.008cm 3 /g、0.0085cm 3 /g、0.009cm 3 And/g, etc. The inventors found that the pore volume of the modified natural graphite material was controlled to 0.004cm 3 /g～0.009cm 3 In the range of/g, most of pores in the natural graphite matrix can be filled with non-graphitized carbon, the compactness in the modified natural material is improved, the structural stability of the material is further improved, the volume expansion of the material is reduced, and the cycle performance of the material is improved.
The modified natural graphite material also has the following characteristics:
the particle size D50 of the modified natural graphite material is 8-25 μm, and further can be 9-19 μm; typically, but not by way of limitation, the particle size D50 of the modified natural graphite material may be 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, 18 μm, 19 μm, 20 μm, 22 μm, 25 μm, and the like. Through multiple experiments, the inventor finds that the particle size D50 of the modified natural graphite material is controlled within the range of 8-25 μm, which is beneficial to reducing the volume expansion of the material and improving the cycle performance of the material, and moreover, the particle size is beneficial to reducing the cost and reducing the operation difficulty of the process in consideration of the preparation cost and the process difficulty, so that the shape fixing effect in the processing process is ideal.
The Kangta tap density (1000 times) of the modified natural graphite material is 1.0 g/cc-1.3 g/cc, and further 1.05 g/cc-1.2 g/cc; typically, but not by way of limitation, the Congta tap density of the modified natural graphite material can be 1.0g/cc, 1.05g/cc, 1.1g/cc, 1.15g/cc, 1.18g/cc, 1.2g/cc, 1.25g/cc, 1.3g/cc, and the like. Through a plurality of experiments, the inventor finds that the tap density of the modified natural graphite material is controlled within the range of 1.0 g/cc-1.3 g/cc, so that the volume expansion of the material is favorably reduced, the cycle performance of the material is improved, and the processing performance of the modified natural graphite material is influenced when the tap density of the modified natural graphite material is controlled out of the range provided by the invention.
The specific surface area of the modified natural graphite material is 0.8m 2 /g～1.4m 2 (ii)/g, further may be 0.85m 2 /g～1.25m 2 The modified natural graphite material may have a specific Mac surface area of 0.8 m/g, which is typical but not limiting 2 /g、0.85m 2 /g、0.9m 2 /g、1.0m 2 /g、1.1m 2 /g、1.2m 2 /g、1.25m 2 /g、1.3m 2 /g、1.4m 2 And/g, etc. Through a plurality of experiments, the inventor finds that the specific surface area of the modified natural graphite material is controlled to be 0.8m 2 /g～1.4m 2 In the range of/g, the volume expansion of the material is favorably reduced, the cycle performance of the material is improved, and the first coulombic efficiency of the modified natural graphite material is influenced when the specific surface area control of the modified natural graphite material is out of the range provided by the invention.
As an alternative solution, at least part of the outer surface of the natural graphite substrate is provided with the non-graphitized carbon.
In the modified natural graphite material, non-graphitized carbon is filled in pores inside particles of the natural graphite matrix, and the outer surfaces of the particles of the natural graphite matrix can be coated with the non-graphitized carbon. Thus, the modification of the natural graphite material can be better realized, the tap density of the material is improved, the volume expansibility of the material is reduced, and the cycle performance of the material is improved.
Wherein the non-graphitized carbon is formed by carbonizing and converting carbon-containing organic matters.
As an optional technical scheme of the application, the softening point temperature of the carbon-containing organic matter is 20-300 ℃; and/or the carbon-containing organic matter comprises at least one of petroleum asphalt, coal asphalt, mesophase asphalt, phenolic resin, epoxy resin, coal tar and heavy oil.
The non-graphitic carbon and carbon-containing organic materials will be described in detail below with reference to the preparation method of the modified natural graphite material.
The embodiment of the application also provides a preparation method of the modified natural graphite material, which comprises the following steps:
mixing a natural graphite raw material with a first modifier to obtain a first mixture;
heating the first mixture to a first temperature, vacuumizing, and sequentially carrying out first heat preservation, heating to a second temperature, second heat preservation and cooling to a third temperature; and
adding a second modifier to the first mixture to obtain a second mixture;
heating the second mixture to a first temperature, vacuumizing, and sequentially carrying out first heat preservation, heating to a second temperature, second heat preservation and cooling to a third temperature to obtain the modified natural graphite material;
wherein the modified natural graphite material comprises a natural graphite matrix and non-graphitized carbon; at least a portion of the pores within the natural graphite matrix are filled with the non-graphitizing carbon;
the pore volume of the modified natural graphite material is 0.004cm 3 /g～0.009cm 3 /g。
According to the preparation method, through the design of vacuumizing, namely negative pressure, multiple times of dipping and the like, the improver can enter the natural graphite, the pores in the natural graphite are greatly reduced, and a particle section structure similar to that of artificial graphite is obtained, so that the problems that the inner surfaces of the pores of the natural graphite cannot be effectively improved by adopting a coating modification mode at the present stage, side reactions repeatedly occur in the circulation process, and the natural graphite cathode material is high in expansion rate and poor in circulation performance can be solved.
Specifically, in some embodiments, the method comprises the steps of:
(a) mixing the pretreated natural graphite raw material with a first modifier to obtain a first mixture, and adding the first mixture into a reaction device;
(b) heating the reaction device to a first temperature, vacuumizing the reaction device, and carrying out primary heat preservation in a vacuum environment;
(c) after the first heat preservation is finished, heating to a second temperature, and carrying out second heat preservation;
(d) after the second heat preservation is finished, cooling to a third temperature, adding a second modifier into the reaction device, and obtaining a second mixture after the second modifier is added;
then heating the reaction device to the first temperature, vacuumizing the reaction device, and carrying out primary heat preservation in a vacuum environment; after the first heat preservation is finished, heating to a second temperature, and carrying out second heat preservation; after the second heat preservation is finished, cooling to a third temperature; that is, after the second modifier is added, the steps (b) to (c) are repeatedly performed at least once.
(e) And carrying out post-treatment to obtain the modified natural graphite material.
According to the preparation method, through the design of vacuumizing, namely negative pressure, multiple times of dipping and the like, under the specific process operation, the improver can enter the natural graphite through the cooperative matching of the steps, the pores in the natural graphite are greatly reduced, and the particle section structure similar to that of the artificial graphite is obtained, so that the problems that the inner surfaces of the pores of the natural graphite cannot be effectively improved by adopting a coating modification mode at the present stage, side reactions repeatedly occur in the circulation process, and the natural graphite cathode material is high in expansion rate and poor in circulation performance are solved. The preparation method has the advantages of simple process, easy operation, high practicability and easy realization of large-scale production.
By adopting the preparation method, under the conditions of negative pressure and certain temperature, the modifier can be impregnated into the pores inside the natural graphite particles and can be coated on the surfaces of the natural graphite particles, so that the synchronous modification of the defect sites on the inner surface and the outer surface of the natural graphite material is realized, the circulation stability of the natural graphite is improved, and the expansion of the natural graphite electrode is reduced. That is, the pores inside the particles of the modified natural graphite material prepared by the method are filled with non-graphitized carbon, and the surfaces of the particles of the modified natural graphite material can also be coated with the non-graphitized carbon.
It is noted that the first modifier and the second modifier herein are preferably the same modifier, or collectively referred to as modifiers. Alternatively, in other embodiments, the first modifier and the second modifier can also be different types of modifiers.
Specifically, in an embodiment of the present invention, the step (a) includes: pretreating a natural graphite raw material, wherein the pretreatment comprises the operations of crushing, grading, shaping and the like on the natural graphite raw material;
mixing the obtained pretreated natural graphite raw material with a first modifier according to a certain proportion, wherein the mixing mode can be mechanical mixing, for example, the mixing mode can be VC mixing, and the mixing time can be 10-60 min, for example, 10min, 20min, 30min, 40min, 50min, 60min and the like;
the resulting first mixture can then be fed to a reaction apparatus such as a reaction kettle, which is equipped with stirring, heating and good sealing functions.
In the embodiment of the present invention, in the step (a), the natural graphite raw material may be flake natural graphite, microcrystalline graphite, spherical natural graphite, or the like, and for example, the flake natural graphite may be mechanically crushed and classified, and then shaped by a spheroidizing device to obtain a spherical or spheroidal graphite material; alternatively, the microcrystalline graphite may be subjected to a treatment such as pulverization and shaping to obtain a spherical or spheroidal graphite material. The pretreated natural graphite raw material can be granular, and further can be at least one of spherical, spheroidal (approximately spherical), oval and the like.
In the step (a), the pretreated natural graphite raw material may have the following characteristics:
the particle size D50 of the pretreated natural graphite material may be 6 to 25 μm, more preferably 8 to 20 μm, for example, 6, 8, 10, 15, 20, 22, 25 μm. The pretreated natural graphite material D90/D10 is 1.5-3.5, and further 2.0-3.2, for example, 1.5, 1.8, 2.0, 2.3, 2.5, 2.6, 3.0, 3.1, 3.2, 3.5, etc. Through multiple experiments, the inventor finds that the particle size D50 of the pretreated natural graphite raw material is controlled within the range of 6-25 μm, and the particle size D90/D10 is controlled within the range of 1.5-3.5, so that the method is beneficial to improving the solid effect in the processing process and improving the rate capability of the modified natural graphite material.
The Tap density Tap of the pretreated natural graphite raw material is 0.7g/cm 3 ～1.0g/cm 3 (g/cc), further, may be 0.8g/cc to 0.95g/cc, and for example, may be 0.7g/cc, 0.75g/cc, 0.8g/cc, 0.85g/cc, 0.87g/cc, 0.9g/cc, 0.91g/cc, 0.95g/cc, 1.0g/cc or the like. Through a plurality of experiments, the inventor finds that the tap density of the pretreated natural graphite raw material is controlled to be 0.7g/cm 3 ～1.0g/cm 3 In the range of (g/cc), the modified natural graphite material with the required tap density can be obtained, the volume expansion of the material can be reduced, the cycle performance of the material can be improved, and the processing performance of the modified natural graphite material can be improved.
The specific surface area SSA of the pretreated natural graphite raw material is 6m 2 /g～10m 2 (ii)/g, further may be 7m 2 /g～9.7m 2 A value of/g, for example, 6m 2 /g、7m 2 /g、7.5m 2 /g、7.8m 2 /g、8m 2 /g、8.6m 2 /g、9m 2 /g、9.2m 2 /g、9.7m 2 /g、10m 2 And/g, etc. Through a plurality of experiments, the inventor finds that the specific surface area of the pretreated natural graphite raw material is controlled to be 6m 2 /g～10m 2 In the range of/g, the modified natural graphite material with the required specific surface area is obtained, so that the volume expansion of the material is reduced, the cycle performance of the material is improved, and the first coulombic efficiency of the modified natural graphite material can be improved.
In the embodiment of the present invention, the first modifier/the second modifier is a modifier having a softening point of 20 to 300 ℃, and the first modifier and the second modifier are both carbon-containing organic materials, and the softening point thereof is, for example, any value in a range of 20 ℃, 30 ℃, 50 ℃, 70 ℃, 80 ℃, 100 ℃, 120 ℃, 160 ℃, 180 ℃, 200 ℃, 250 ℃, 285 ℃, 300 ℃ or any two of these values. The carbon-containing organic matter (modifier) comprises any one or a mixture of at least two of petroleum asphalt, coal asphalt, mesophase asphalt, phenolic resin, epoxy resin, coal tar or heavy oil. But not limited to the above-listed modifiers, other modifiers satisfying the following conditions may also be used in the present invention: softening and flowing at a certain temperature to enable one part of the natural graphite to be filled in the internal pores of the natural graphite and adsorbed on the internal surface, and the other part of the natural graphite to be left on the surface of the natural graphite; and the carbon is converted into non-graphitized carbon through carbonization treatment.
Typical but non-limiting examples of such mixtures of modifiers are: mixtures of coal pitch and petroleum pitch, mixtures of coal pitch and mesophase pitch, mixtures of phenolic resin and epoxy resin, mixtures of coal tar and heavy oil, mixtures of phenolic resin, epoxy resin and petroleum resin, mixtures of coal pitch, petroleum pitch, mesophase pitch, phenolic resin, epoxy resin and heavy oil, mixtures of coal pitch, petroleum resin, coal tar and heavy oil, and the like.
Since the properties of the modifier materials such as petroleum pitch, coal pitch, phenol resin, epoxy resin, and the like are similar, the effects of the respective materials on the natural graphite material are similar. Therefore, when the modifier comprises a mixture formed by mixing any two or more of petroleum asphalt, coal asphalt, phenolic resin, epoxy resin and the like, all the components can be mixed according to any proportion; for example, when the modifier is a mixture of petroleum asphalt and coal asphalt, the petroleum asphalt and the coal asphalt can be mixed in any proportion without affecting the performance of the natural graphite material, and the specific proportion or content thereof is not particularly limited and can be adjusted by a person skilled in the art according to the actual situation.
In the embodiment of the invention, the mass ratio of the natural graphite raw material to the total mass of the first modifier and the second modifier is 95: 5-70: 30, and further may be 90: 10-75: 25, further may be 85: 15-80: 20, for example, may be 95: 5. 92: 8. 90: 10. 88: 12. 85: 15. 82: 18. 80: 20. 75: 25. 70: 30, etc.
It should be noted that, in the preparation method, the modifier may be added in a batch manner, for example, the first modifier may be added in step (a) and the second modifier may be added in step (d), and in general, the mass ratio of the natural graphite raw material to the total mass of the first modifier and the second modifier may be 95: 5-70: 30. the mass ratio of the first modifier added in the step (a) to the second modifier added in the step (d) can be (0.5-5): 1, further may be (0.8-2): 1, further may be (1 to 1.5): 1, for example, may be 0.5: 1. 0.8: 1. 1: 1. 1.5:1. 2:1. 3: 1. 4: 1.5:1, etc. By adopting the mode of adding the modifier in batches, the modifier can be more fully filled into the natural graphite matrix, the porosity inside the natural graphite matrix is greatly reduced, and the pore volume of the modified natural graphite material is more favorably reduced, so that the volume expansion rate of the material is favorably reduced, and the cycle performance of the material is improved.
Specifically, in an embodiment of the present invention, the step (b) includes: after the feeding is finished, the reaction kettle adopts a gradual heating-up mode, the heating-up speed can be 1 ℃/min to 4 ℃/min, for example, 1 ℃/min, 2 ℃/min, 3 ℃/min, 4 ℃/min and the like, the reaction kettle is kept in a uniform-speed stirring state while heating, the reaction kettle is heated up to a first temperature, the reaction kettle is vacuumized after the temperature is raised to a preset temperature, namely, the reaction kettle is vacuumized, and then the first heat preservation is carried out in a vacuum environment.
In this step (b), the first temperature is selected in relation to the softening point of the modifier, and is not lower than the softening point of the modifier, and is such that the modifier changes at this temperature. Illustratively, the first temperature is at least 30 ℃ higher than the softening point temperature of the modifying agent, e.g., 30 ℃, 35 ℃, 40 ℃, 50 ℃, 60 ℃, or more than 60 ℃ higher than the softening point temperature of the modifying agent. That is, the first temperature is greater than or equal to 30 ℃ higher than the softening point temperature of the modifier, for example, the temperature of the modifier is 250 ℃, the first temperature is greater than or equal to 250+30 ℃, that is, the first temperature is greater than or equal to 280 ℃. The pressure in the vacuum environment may be-0.15 MPa to-0.05 MPa, more preferably-0.12 MPa to-0.08 MPa, still more preferably-0.10 MPa, and examples thereof may include-0.15 MPa, -0.12MPa, -0.10MPa, -0.09MPa, -0.08MPa, -0.16MPa, and-0.05 MPa. The first heat-retaining time is 1 to 3 hours, further 1.5 to 2.5 hours, further 2 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, and the like.
Specifically, in an embodiment of the present invention, the step (c) comprises: and after the first heat preservation is finished, heating the reaction kettle to a second temperature, and carrying out second heat preservation.
The second temperature is 620 to 680 ℃, 640 to 660 ℃, 650 ℃, 620 ℃, 630 ℃, 640 ℃, 650 ℃, 660 ℃, 670 ℃, 680 ℃ or the like. The time for the second heat preservation is 1 to 3 hours, further 1.5 to 2.5 hours, further 2 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, and the like.
Specifically, in an embodiment of the present invention, the step (d) includes: after the second heat preservation is finished, the temperature of the reaction kettle is reduced to a third temperature, then the second modifier is slowly added into the reaction kettle, and after the second modifier is added, the steps (b) to (c) are repeatedly executed at least once, for example, the steps (b) to (c) can be repeatedly executed once, twice or more, and preferably, the steps (b) and (c) are repeatedly executed once. Illustratively, after the second heat preservation is finished, the reaction kettle is cooled to a third temperature, then a second modifier is slowly added into the reaction kettle, after the second modifier is added, the reaction kettle is heated to the first temperature, the reaction kettle is vacuumized after the temperature is raised to a preset temperature, then heat preservation is carried out in a vacuum environment, after the heat preservation is finished, the reaction kettle is heated to the second temperature, heat preservation is carried out, and then the reaction kettle can be cooled by adopting a condensation cooling mode.
Wherein the third temperature is the softening point temperature of the modifying agent, e.g., the softening point temperature of the modifying agent is 250 ℃, the third temperature is 250 ℃.
Specifically, in an embodiment of the present invention, step (e) includes: and cooling the reaction kettle materials, and performing post-treatment, wherein the post-treatment comprises heat treatment, crushing and sieving in sequence to obtain the modified natural graphite material.
The temperature of the heat treatment is 950 to 1350 ℃, and further 1000 to 1300 ℃, and for example, 950 ℃, 980 ℃, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1350 ℃ or the like can be mentioned.
Under the specific process operation of the preparation method, the microstructure or the performance of the obtained modified natural graphite material can be effectively adjusted in the range through the cooperative matching of the steps and the adjustment of specific operation parameters such as pressure, temperature and the like, so that the modified natural graphite material with excellent electrochemical performance is obtained.
The preparation method has the advantages of simple process, low cost, easy operation and control, higher practicability and suitability for expanded large-scale production.
The embodiment of the invention also provides a negative pole piece which comprises the modified natural graphite material.
Specifically, the negative electrode plate comprises a current collector and a negative active material coated on the current collector, wherein the negative active material comprises the modified natural graphite material.
The embodiment of the invention also provides a lithium ion battery, which comprises the negative pole piece.
The lithium ion battery comprises a negative pole piece, a positive pole piece, a diaphragm, electrolyte and a shell, wherein the negative pole piece comprises a current collector and a negative active material coated on the current collector, and the negative active material comprises the modified natural graphite material.
The lithium ion battery has low expansion rate and excellent cycle performance.
The following examples are intended to illustrate the invention in more detail. The embodiments of the present invention are not limited to the following specific examples. The present invention can be modified and implemented as appropriate within the scope of the main claim.
Example 1
First, 100 mesh flake graphite was mechanically pulverized, and then classified and shaped, and the parameters of the shaped powder were as follows (D50 ═ 15.6 μm, Tap ═ 0.912g/cc, D90/D10 ═ 3.1, SSA 8.6m 2 G, cross-sectional view shown in FIG. 1, pore volume of 0.018cm 3 /g)。
Then, the obtained natural graphite raw material and the first modifier coal pitch (softening point 160 ℃) are mixed according to the proportion of 0.85:0.07, and the mixing is carried out in a VC mixing mode for 30 min.
Then, putting the mixed materials into a reaction kettle, heating the reaction kettle at a temperature of 2 ℃/min in a gradual heating mode, keeping the reaction kettle in a uniform stirring state while heating, heating to 190 ℃, pumping the reaction kettle to a pressure of-0.1 Mpa, and then preserving heat for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; then cooling the reaction kettle to about 160 ℃, slowly adding a second modifier into the reaction kettle, wherein the mass ratio of the addition amount of the second modifier to the first modifier is 8:7, after the second modifier is completely filled, heating the reaction kettle to 190 ℃ again, pumping the reaction kettle to the pressure of-0.1 MPa, and then preserving the heat for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; and then cooling by adopting a condensation cooling mode.
And finally, carrying out 1300 ℃ heat treatment on the materials treated by the process, and crushing and sieving the heat-treated samples to obtain the final samples, namely the modified natural graphite material.
Typical data for the modified natural graphite material obtained in example 1: d50 ═ 16.5 μm, Congta tap (1000 times) 1.16g/cc, and Mach specific surface area 0.89m 2 Per g, pore volume was reduced to 0.00565cm 3 The sectional view is shown in FIG. 2.
Example 2
First, 100 mesh flake graphite was mechanically pulverized, and then classified and shaped, and the parameters of the shaped powder were as follows (D50 ═ 8.1 μm, Tap ═ 0.874g/cc, D90/D10 ═ 2.3, and SSA 9.7m 2 /g。
Then, the obtained natural graphite raw material and the first modifier petroleum asphalt (the softening point is 250 ℃) are mixed according to the proportion of 0.92:0.04, and the mixing is carried out in a VC mixing mode for 30 min.
Then, putting the mixed materials into a reaction kettle, heating the reaction kettle at a temperature of 2 ℃/min in a gradual heating mode, keeping the reaction kettle in a uniform stirring state while heating, heating to 280 ℃, pumping the reaction kettle to a pressure of-0.1 Mpa, and then keeping the temperature for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; then cooling the reaction kettle to about 250 ℃, slowly adding a second modifier into the reaction kettle, wherein the mass ratio of the addition amount of the second modifier to the first modifier is 4:4, after the second modifier is completely filled, heating the reaction kettle to 280 ℃ again, pumping the reaction kettle to the pressure of-0.1 MPa, and then preserving the heat for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; and then cooling by adopting a condensation cooling mode.
And finally, carrying out 1000 ℃ heat treatment on the materials treated by the process, and crushing and sieving the heat-treated samples to obtain the final samples.
Typical data for the modified natural graphite material obtained in example 2: d50 ═ 9.3 μm, Congtar tap (1000 times) 1.08g/cc, and Mach specific surface area 1.25m 2 Per g, pore volume was reduced to 0.00812cm 3 /g。
Example 3
First, 100 mesh flake graphite was mechanically pulverized, and then classified and shaped, and the parameters of the shaped powder were as follows (D50 ═ 17.4 μm, Tap ═ 0.902g/cc, D90/D10 ═ 2.6, and SSA 7.85m 2 /g。
Then, the obtained natural graphite raw material and the first modifier petroleum asphalt (softening point 130 ℃) are mixed according to the proportion of 0.88:0.04, and the mixing is carried out in a VC mixing mode for 30 min.
Then, putting the mixed materials into a reaction kettle, heating the reaction kettle at a temperature of 2 ℃/min in a gradual heating mode, keeping the reaction kettle in a uniform stirring state while heating, heating to 160 ℃, pumping the reaction kettle to a pressure of-0.1 Mpa, and then keeping the temperature for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; then cooling the reaction kettle to about 130 ℃, slowly adding a second modifier into the reaction kettle, wherein the mass ratio of the addition amount of the second modifier to the first modifier is 8:4, after the second modifier is completely filled, heating the reaction kettle to 160 ℃, pumping the reaction kettle to the pressure of-0.1 MPa, and then preserving the heat for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; and then cooling by adopting a condensation cooling mode.
And finally, carrying out 1000 ℃ heat treatment on the materials treated by the process, and crushing and sieving the heat-treated samples to obtain the final samples.
Typical data for the modified natural graphite material obtained in example 3: d50 ═ 17.9 μm, congta tap (1000 times) 1.17g/cc, specific surface area of microphone is 0.89 square meter/g, pore volume is reduced to 0.00427cm 3 /g。
Example 4
Firstly, 100-mesh crystalline flake graphite is mechanically crushed, and then classified and shaped, and the parameters of the shaped powder are as follows (D50 is 17.4 mu m, Tap is 0.902g/cc, D90/D10 is 2.6, and SSA is 7.85 square meters per gram.
Then, the obtained natural graphite raw material and a first modifier phenolic resin (softening point 100 ℃) and (part of) a first modifier petroleum asphalt (softening point 120 ℃) are mixed according to the proportion of 0.85:0.03:0.03, and the mixing is carried out by adopting a VC mixing mode, and the mixing time is 30 min.
Then, putting the mixed materials into a reaction kettle, heating the reaction kettle at a temperature of 2 ℃/min in a gradual heating mode, keeping the reaction kettle in a uniform stirring state while heating, heating to 150 ℃, pumping the reaction kettle to a pressure of-0.1 Mpa, and then keeping the temperature for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; then cooling the reaction kettle to about 120 ℃, slowly adding a second modifier petroleum asphalt into the reaction kettle, wherein the mass ratio of the addition amount of the second modifier petroleum asphalt to the first modifier petroleum asphalt is 9:3, after the second modifier is completely added, heating the reaction kettle to 150 ℃ again, pumping the reaction kettle to the pressure of-0.1 Mpa, and then preserving the heat for 2 hours; after the heat preservation is finished, heating the reaction kettle to 650 ℃, and preserving the heat for 2 hours; and then cooling by adopting a condensation cooling mode.
And finally, carrying out 1000 ℃ heat treatment on the materials treated by the process, and crushing and sieving the heat-treated samples to obtain the final samples.
Typical data for the modified natural graphite material obtained in example 4: d50 ═ 18.1 μm, Congtar tap (1000 times) 1.12g/cc, and Mach specific surface area 0.98m 2 Per g, pore volume was reduced to 0.00648cm 3 /g。
Example 5
First, 100 mesh flake graphite was mechanically pulverized, and then classified and shaped, and the parameters of the shaped powder were as follows (D50 ═ 14.7 μm, Tap ═ 0.886g/cc, D90/D10 ═ 2.56, SSA 8.05m 2 /g。
Then, the obtained natural graphite raw material and the first modifier coal pitch (softening point 110 ℃) are mixed according to the proportion of 0.9:0.05, and the mixing is carried out in a VC mixing mode for 30 min.
Then, putting the mixed materials into a reaction kettle, heating the reaction kettle at a temperature of 2 ℃/min in a gradual heating mode, keeping the reaction kettle in a uniform stirring state while heating, heating to 140 ℃, pumping the reaction kettle to a pressure of-0.15 Mpa, and then keeping the temperature for 2 hours; after the heat preservation is finished, heating the reaction kettle to 630 ℃, and preserving the heat for 2 hours; then cooling the reaction kettle to about 110 ℃, slowly adding a second modifier into the reaction kettle, wherein the mass ratio of the addition amount of the second modifier to the first modifier is 5:5, after the second modifier is completely filled, heating the reaction kettle to 140 ℃ again, pumping the reaction kettle to the pressure of-0.15 MPa, and then preserving the heat for 2 hours; after the heat preservation is finished, heating the reaction kettle to 630 ℃, and preserving the heat for 2 hours; and then cooling by adopting a condensation cooling mode.
And finally, carrying out heat treatment on the materials treated by the process at 1200 ℃, and crushing and sieving the heat-treated samples to obtain the final samples.
Typical data for the modified natural graphite material obtained in example 5: d50 ═ 16.1 μm, Congta tap (1000 times) 1.16g/cc, and Mach specific surface area 1.02m 2 Per g, pore volume was reduced to 0.00695cm 3 /g。
Example 6
Firstly, the 100-mesh crystalline flake graphite is mechanically crushed, then classified and shaped, and then the whole is carried outThe powder parameters after forming were as follows (D50 ═ 14.7 μm, Tap ═ 0.886g/cc, D90/D10 ═ 2.56, SSA 8.05m 2 /g。
Then, the obtained natural graphite raw material and the first modifier petroleum asphalt (with a softening point of 200 ℃) are mixed according to the proportion of 0.88:0.08, and the mixing is carried out in a VC mixing mode for 30 min.
Then, putting the mixed materials into a reaction kettle, heating the reaction kettle at a temperature of 2 ℃/min in a gradual heating mode, keeping the reaction kettle in a uniform stirring state while heating, heating to 230 ℃, pumping the reaction kettle to a pressure of-0.12 Mpa, and then keeping the temperature for 2 hours; after the heat preservation is finished, heating the reaction kettle to 670 ℃, and preserving the heat for 2 hours; then cooling the reaction kettle to about 200 ℃, slowly adding a second modifier into the reaction kettle, wherein the mass ratio of the addition amount of the second modifier to the first modifier is 8:4, after the modifier is completely filled, heating the reaction kettle to 230 ℃, pumping the reaction kettle to the pressure of-0.12 MPa, and then preserving the heat for 2 hours; after the heat preservation is finished, heating the reaction kettle to 670 ℃, and preserving the heat for 2 hours; and then cooling by adopting a condensation cooling mode.
And finally, carrying out heat treatment on the materials treated by the process at 1200 ℃, and crushing and sieving the heat-treated samples to obtain the final samples.
Typical data for the modified natural graphite material obtained in example 6: d50 ═ 16.5 μm, Congta tap (1000 times) 1.18g/cc, and Mach specific surface area 0.89m 2 Per g, pore volume was reduced to 0.00612cm 3 /g。
Comparative example 1
Firstly, 100-mesh crystalline flake graphite is mechanically crushed, and then classified and shaped, parameters of the shaped powder are as follows (D50 is 15.6 mu m, Tap is 0.912g/cc, D90/D10 is 3.1, SSA is 8.6 square meter/g, a sectional view is as shown in figure 1, and the pore volume is 0.018cm 3 /g)。
Then, the obtained natural graphite raw material and the modifier coal pitch (softening point 160 ℃) are mixed according to the proportion of 0.85:0.15, and the mixing is carried out by adopting a VC mixing mode, and the mixing time is 30 min.
And (3) carrying out 1300 ℃ heat treatment on the materials treated by the processes, and crushing and sieving the heat-treated samples to obtain the final samples.
Typical data for the final sample obtained in comparative example 1: d50 is 15.9 μm, Congta tap (1000 times) is 0.953g/cc, and Mac specific surface area is 0.92m 2 Per g, pore volume reduced to 0.00625cm 3 The sectional view is shown in FIG. 3.
Electrochemical performance test sample preparation:
the material obtained in example 1 was used as an anode active material, and the ratio of the anode active material: CMC: and uniformly mixing SBR (styrene butadiene rubber) in a mass ratio of 96.5:1.5:2, coating the mixture on a copper foil current collector, and drying to obtain a negative pole piece for later use.
The method comprises the steps of firstly, carrying out button cell test on an obtained pole piece, assembling the cell in an argon glove box, taking a metal lithium piece as a negative electrode, taking 1mol/L LiPF6+ EC + EMC as electrolyte, taking a polyethylene/propylene composite microporous membrane as a membrane, carrying out electrochemical performance on a cell test instrument, wherein the charge-discharge voltage is 0.01-1.5V, the charge-discharge rate is 0.1C, the capacity and the first efficiency obtained by the test are 353mAh/g, and the first coulombic efficiency is 95.2%.
The material has a 20-week cyclic expansion rate of 24.3 percent through an in-situ expansion rate test, and the expansion rate is greatly reduced by 26 percent compared with the conventional natural graphite.
Testing a finished battery: and (3) mixing the modified natural graphite material obtained in the example 1, a conductive agent, CMC and SBR according to the mass ratio of 95:1.5:1.5:2, and coating the mixture on copper foil to obtain a negative pole piece. And uniformly mixing the positive active material NCM523, the conductive agent and the PVDF according to the mass ratio of 96.5:2:1.5, and coating the mixture on an aluminum foil to obtain the positive pole piece. The electrolyte is 1mol/L LiPF6+ EC + EMC, the diaphragm is a polyethylene/propylene composite microporous membrane, and the electrolyte is charged and discharged at normal temperature at the multiplying power of 1C, and the voltage range is 2.75-4.2V.
Through tests, the finished product lithium ion battery has the capacity grading expansion of 18.3 percent, which is obviously lower than that of the traditional natural graphite, and further confirms the low expansion characteristic of the new material, and the 1C/1C cycle test result shows that the capacity retention rate of the material is still 80.5 percent after 2000 cycles, and the cycle performance of the material is greatly improved compared with that of the traditional natural graphite.
Accordingly, examples 2 to 6 and comparative example 1 were tested under the same test conditions and methods as in example 1 above, and the test results of each example and comparative example are shown in table 1.
TABLE 1 test results of examples and comparative examples
As can be seen from the data in table 1, compared with comparative example 1, the modified natural graphite material provided in the embodiment of the present invention can improve the problem of high expansion rate of the existing natural graphite negative electrode material, improve cycle performance and first coulombic efficiency, and further improve the electrochemical performance of the material.
In addition, the inventor proves that compared with the existing natural graphite cathode material, the modified natural graphite material provided by the invention has better electrochemical performance, and the cycle expansion rate of the material after in-situ expansion rate test is less than or equal to 24.8% after 20 weeks, and the expansion rate is greatly reduced by 26% compared with the traditional natural graphite. The material is applied to a lithium ion battery, and the measured volume expansion of the finished battery is about 18.3 percent, which is obviously lower than that of the traditional natural graphite, so that the low expansion characteristic of the new material is further proved; in addition, the 1C/1C cycle test result shows that the capacity retention rate of the material can still reach at least 80.5% after 2000 cycles, and the cycle performance of the material is greatly improved compared with that of the traditional natural graphite.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
It is noted that a portion of this patent application contains material which is subject to copyright protection. The copyright owner reserves copyright rights except for copies of patent documents or patent document contents of records at the patent office.
Claims (10)
1. A modified natural graphite material, comprising:
a natural graphite matrix;
non-graphitizing carbon, at least a portion of pores inside the natural graphite matrix being filled with the non-graphitizing carbon;
the pore volume of the modified natural graphite material is 0.004cm 3 /g～0.009cm 3 /g。
2. The modified natural graphite material of claim 1, wherein the modified natural graphite material has at least one of the following characteristics a) to c):
a) the non-graphitized carbon is arranged on at least part of the outer surface of the natural graphite matrix;
b) the non-graphitized carbon is formed by carbonizing and converting carbon-containing organic matters;
c) the softening point temperature of the carbon-containing organic matter is 20-300 ℃; and/or the carbon-containing organic matter comprises at least one of petroleum asphalt, coal asphalt, mesophase asphalt, phenolic resin, epoxy resin, coal tar and heavy oil.
3. The modified natural graphite material according to claim 1 or 2, wherein the modified natural graphite material has at least one of the following features d) to f):
d) the particle size D50 of the modified natural graphite material is 8-25 μm;
e) the tap density of the modified natural graphite material is 1.0 g/cc-1.3 g/cc;
f) the specific surface area of the modified natural graphite material is 0.8m 2 /g～1.4m 2 /g。
4. A preparation method of a modified natural graphite material is characterized by comprising the following steps:
mixing a natural graphite raw material with a first modifier to obtain a first mixture;
heating the first mixture to a first temperature, vacuumizing, and sequentially carrying out first heat preservation, heating to a second temperature, second heat preservation and cooling to a third temperature; and
adding a second modifier to the first mixture to obtain a second mixture;
heating the second mixture to a first temperature, vacuumizing, and sequentially carrying out first heat preservation, heating to a second temperature, second heat preservation and cooling to a third temperature to obtain the modified natural graphite material;
wherein the modified natural graphite material comprises a natural graphite matrix and non-graphitized carbon; at least a portion of the pores within the natural graphite matrix are filled with the non-graphitizing carbon;
the pore volume of the modified natural graphite material is 0.004cm 3 /g～0.009cm 3 /g。
5. The method for preparing a modified natural graphite material according to claim 4, wherein the modified natural graphite material has at least one of the following characteristics a) to f):
a) the non-graphitized carbon is arranged on at least part of the outer surface of the natural graphite matrix;
b) the first modifier and the second modifier are both carbon-containing organic matters, and the non-graphitized carbon is converted from the carbon-containing organic matters through carbonization treatment;
c) the softening point temperature of the carbon-containing organic matter is 20-300 ℃; and/or the carbon-containing organic matter comprises at least one of petroleum asphalt, coal asphalt, mesophase asphalt, phenolic resin, epoxy resin, coal tar and heavy oil;
d) the particle size D50 of the modified natural graphite material is 8-25 μm;
e) the tap density of the modified natural graphite material is 1.0 g/cc-1.3 g/cc;
f) what is needed isThe specific surface area of the modified natural graphite material is 0.8m 2 /g～1.4m 2 /g。
6. The method for producing a modified natural graphite material according to any one of claims 4 to 5, wherein at least one of the following conditions g) to m) is satisfied:
g) the pressure of the vacuum environment is-0.15 MPa to-0.05 MPa;
h) the first temperature is at least 30 ℃ above the softening point temperature of the first modifier/second modifier;
i) the first heat preservation time is 1-3 h;
j) the second temperature is 620-680 ℃;
k) the time for the second heat preservation is 1-3 h;
l) the third temperature is the softening point temperature of the first/second modifier;
m) the ratio of the mass of the natural graphite raw material to the total mass of the first modifier and the second modifier is 95: 5-70: 30.
7. the method for producing a modified natural graphite material according to any one of claims 4 to 6, further comprising a step of pretreating the natural graphite raw material before mixing the natural graphite raw material with the first modifier;
and/or, the pre-treatment comprises crushing, grading and shaping the natural graphite raw material;
and/or the natural graphite raw material comprises at least one of scale-shaped natural graphite, microcrystalline graphite and spherical natural graphite.
8. The method for preparing a modified natural graphite material according to claim 7, wherein the pretreated natural graphite raw material has at least one of the following characteristics p) to t):
p) the particle size D50 of the pretreated natural graphite raw material is 6-25 μm;
q) the particle size D90/D10 of the pretreated natural graphite raw material is 1.5-3.5;
s) the tap density of the pretreated natural graphite raw material is 0.7 g/cc-1.0 g/cc;
t) the specific surface area of the pretreated natural graphite raw material is 6m 2 /g～10m 2 /g。
9. A negative electrode plate is characterized by comprising the modified natural graphite material according to any one of claims 1 to 3 or the modified natural graphite material obtained by the preparation method according to any one of claims 4 to 8.
10. A lithium ion battery, characterized in that the lithium ion battery comprises the negative electrode tab of claim 9.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116072853A (en) * | 2023-03-03 | 2023-05-05 | 溧阳紫宸新材料科技有限公司 | Composite graphite material and preparation method and application thereof |
| WO2024077522A1 (en) * | 2022-10-12 | 2024-04-18 | 宁德时代新能源科技股份有限公司 | Negative electrode active material preparation method, negative electrode active material, secondary battery and electric apparatus |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102709565A (en) * | 2012-05-30 | 2012-10-03 | 力芯（青岛）新能源材料有限公司 | Preparation method of lithium ion battery porous silicon carbon composite negative material |
| CN103078090A (en) * | 2013-03-01 | 2013-05-01 | 湖州创亚动力电池材料有限公司 | Lithium ion power battery composite cathode material and its preparation method |
| CN105977489A (en) * | 2016-03-22 | 2016-09-28 | 福建翔丰华新能源材料有限公司 | Preparation method of modified microcrystalline graphite anode material for lithium ion battery |
| CN108063229A (en) * | 2017-12-13 | 2018-05-22 | 深圳市贝特瑞新能源材料股份有限公司 | Natural graphite base modified composite material, its preparation method and the lithium ion battery comprising the modified composite material |
| CN109970052A (en) * | 2019-02-27 | 2019-07-05 | 福建翔丰华新能源材料有限公司 | A kind of method of natural graphite granulation and secondary coating modification |
| CN110828824A (en) * | 2019-11-26 | 2020-02-21 | 湖南中科星城石墨有限公司 | Long-life natural graphite negative electrode material and preparation method thereof |
| CN111333064A (en) * | 2020-03-25 | 2020-06-26 | 江西正拓新能源科技股份有限公司 | High-performance lithium ion battery graphite negative electrode material and preparation method thereof |
| CN111613785A (en) * | 2020-05-28 | 2020-09-01 | 贝特瑞新材料集团股份有限公司 | Composite coated negative electrode material, preparation method thereof and lithium ion battery |
-
2021
- 2021-02-02 CN CN202110141251.1A patent/CN114843508A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102709565A (en) * | 2012-05-30 | 2012-10-03 | 力芯（青岛）新能源材料有限公司 | Preparation method of lithium ion battery porous silicon carbon composite negative material |
| CN103078090A (en) * | 2013-03-01 | 2013-05-01 | 湖州创亚动力电池材料有限公司 | Lithium ion power battery composite cathode material and its preparation method |
| CN105977489A (en) * | 2016-03-22 | 2016-09-28 | 福建翔丰华新能源材料有限公司 | Preparation method of modified microcrystalline graphite anode material for lithium ion battery |
| CN108063229A (en) * | 2017-12-13 | 2018-05-22 | 深圳市贝特瑞新能源材料股份有限公司 | Natural graphite base modified composite material, its preparation method and the lithium ion battery comprising the modified composite material |
| CN109970052A (en) * | 2019-02-27 | 2019-07-05 | 福建翔丰华新能源材料有限公司 | A kind of method of natural graphite granulation and secondary coating modification |
| CN110828824A (en) * | 2019-11-26 | 2020-02-21 | 湖南中科星城石墨有限公司 | Long-life natural graphite negative electrode material and preparation method thereof |
| CN111333064A (en) * | 2020-03-25 | 2020-06-26 | 江西正拓新能源科技股份有限公司 | High-performance lithium ion battery graphite negative electrode material and preparation method thereof |
| CN111613785A (en) * | 2020-05-28 | 2020-09-01 | 贝特瑞新材料集团股份有限公司 | Composite coated negative electrode material, preparation method thereof and lithium ion battery |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024077522A1 (en) * | 2022-10-12 | 2024-04-18 | 宁德时代新能源科技股份有限公司 | Negative electrode active material preparation method, negative electrode active material, secondary battery and electric apparatus |
| CN116072853A (en) * | 2023-03-03 | 2023-05-05 | 溧阳紫宸新材料科技有限公司 | Composite graphite material and preparation method and application thereof |
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