CN117080444A - High-capacity lithium ion battery negative electrode material with quick charge function and preparation method thereof - Google Patents
High-capacity lithium ion battery negative electrode material with quick charge function and preparation method thereof Download PDFInfo
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- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 40
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000007773 negative electrode material Substances 0.000 title description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 93
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 73
- 239000010439 graphite Substances 0.000 claims abstract description 73
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- 238000010438 heat treatment Methods 0.000 claims abstract description 40
- 239000010405 anode material Substances 0.000 claims abstract description 39
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- 238000001816 cooling Methods 0.000 claims abstract description 16
- 238000001354 calcination Methods 0.000 claims abstract description 15
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- 230000000630 rising effect Effects 0.000 claims description 3
- 239000011163 secondary particle Substances 0.000 abstract description 25
- 239000000463 material Substances 0.000 abstract description 23
- 229910021385 hard carbon Inorganic materials 0.000 abstract description 7
- 230000001105 regulatory effect Effects 0.000 abstract description 5
- 239000003792 electrolyte Substances 0.000 abstract description 4
- 230000001276 controlling effect Effects 0.000 abstract description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 29
- 239000002131 composite material Substances 0.000 description 11
- 229910021389 graphene Inorganic materials 0.000 description 11
- 239000010410 layer Substances 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 238000005303 weighing Methods 0.000 description 8
- 229910052814 silicon oxide Inorganic materials 0.000 description 7
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
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- 229910052799 carbon Inorganic materials 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application discloses a high-capacity and quick-charging lithium ion battery anode material and a preparation method thereof, relating to the technical field of lithium ion batteries and comprising the following steps: uniformly mixing graphite and resin in a certain proportion, and carrying out low-temperature heat treatment to obtain first mixed particles; adding a certain amount of silicon into the first mixed particles, continuously heating and stirring for a certain time, and cooling to obtain second mixed particles; and uniformly mixing the second mixed particles with the soft carbon precursor at normal temperature, and calcining for a certain time in a high-temperature inert gas environment to obtain the high-capacity and fast-charging lithium ion battery anode material. The capacity of the anode material is regulated and controlled by regulating and controlling the proportion of silicon and graphite; the resin enables silicon to be uniformly dispersed in graphite secondary particles, and the quick charge performance of the whole material can be improved; the surface coated soft carbon not only can reduce the specific surface of the material, but also can further inhibit the volume expansion of silicon, avoid direct contact between electrolyte and hard carbon, and improve the high-temperature performance.
Description
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to a high-capacity and fast-charging lithium ion battery negative electrode material and a preparation method thereof.
Background
The negative electrode material of the lithium ion battery is one of key factors limiting the performances of the lithium ion battery, and the theoretical specific capacity of the current commercial negative electrode graphite material is only 372mAh/g, so that the requirement of a high-energy-density power battery cannot be met. The theoretical lithium intercalation capacity of the silicon material at normal temperature is up to 3579mAh/g, the storage is rich, the price is low, and the silicon material is a lithium ion battery cathode material with great potential. However, the huge volume effect and the characteristics of the semiconductor make the cycle performance and the multiplying power of the battery worse, which limits the application. At present, silicon is mainly considered to be added into a graphite negative electrode as an additive, so that on one hand, the gram capacity of the material can be improved, and the surface density of a negative electrode sheet can be reduced, thereby improving the quick charge capacity; on the other hand, the volume expansion of silicon can be relieved, and the cycle performance of the material is improved.
The patent CN106784755A proposes a new method, which comprises the steps of preparing a graphite/silicon/graphene composite material with a three-layer sandwich structure by compounding graphite and graphene with silicon, and the preparation method comprises the following steps: adding graphene powder and a dispersing agent into an NMP solution, and carrying out ultrasonic oscillation to uniformly disperse the graphene powder and the dispersing agent so as to obtain a graphene dispersion liquid; sequentially adding nano silicon, asphalt and graphite into a mixer, and heating under stirring to obtain a graphite/silicon composite material; and continuously stirring the graphene dispersion liquid and the graphite/silicon composite material in a mixer, and drying, calcining, crushing and grading the obtained material to obtain the graphite/silicon/graphene composite material. In the material, nano silicon is fixed between graphite and graphene, inner-layer graphite is used as a framework, outer-layer graphene is used as a buffer layer, and the design of the special structure improves the volume effect of the silicon material in the charge-discharge process, and improves the first efficiency and the cycle performance of the material. However, in the second step of the preparation process, the process of mixing nano silicon, graphite and asphalt cannot ensure that the nano silicon is uniformly distributed on the surface of the graphite, and under the action of the asphalt, a large irregular material is easy to generate, so that the graphene coated later is uneven; in addition, graphene is expensive and is not beneficial to industrial application.
The patent application CN106486650A proposes a new method, which comprises the steps of coating a silicon material with a polymer material, and then mixing with the artificial graphite and the material of the coating layer; and (3) putting the mixture into a roller furnace or a coating kettle for modification pretreatment, and carbonizing to obtain the artificial graphite/silicon composite anode material. The silicon material in the artificial graphite/silicon composite anode material prepared by the application is inlaid in the gaps of the composite particle structure formed by bonding the artificial graphite and the artificial graphite, and has the characteristics of small expansion, high gram capacity and good circulation. However, in the mixing process of silicon and artificial graphite, the method is difficult to control the uniform distribution of silicon materials, and can cause the phenomenon of agglomeration of a large amount of silicon materials to influence the circulation stability of the materials.
The patent CN103022446B proposes a new method, which is characterized in that a silicon oxide/carbon anode material of a lithium ion battery and a preparation method thereof are adopted, so that a three-layer composite material with a core-shell structure is obtained, a graphite material is an inner core, a porous silicon oxide is an intermediate layer, and organic pyrolytic carbon is an outermost coating layer. When the method is used for preparing the silicon particle, active metal is added to reduce part of SiOx, and the obtained product structure carries out self-absorption on the volume expansion effect of the silicon particles in the charge and discharge process, so that the volume expansion effect of the silicon particles is greatly reduced, and the charge and discharge efficiency and the cycle stability of the silicon particles for the first time are obviously improved. However, when the silicon oxide and the graphite are mixed to obtain a mixture, the simple mixing process cannot uniformly disperse the silicon oxide on the surface of the graphite, so that the silicon oxide is easy to agglomerate, and the performance of the material is reduced; in addition, the silicon oxide is partially reduced and then carbon coated, so that a part of pore structures are filled with a carbon source, the expansion space of the silicon oxide is reduced, and the circulation stability is reduced.
Disclosure of Invention
In order to solve the problems of low capacity and low quick charge performance of the existing negative electrode material, the application provides a technical scheme that silicon is uniformly adhered in graphite secondary particles by resin in the preparation process, gram capacity of the material is improved, volume expansion of the silicon is relieved, a soft carbon precursor such as asphalt is used for coating the composite structure, the carbonized resin is converted into hard carbon, and integral quick charge performance of the material is improved.
Specifically, in order to achieve the above technical solution, in a first aspect, the present application provides a preparation method of a high-capacity and fast-charging lithium ion battery anode material, which includes the following steps:
uniformly mixing graphite and resin in a certain proportion, and carrying out low-temperature heat treatment to obtain first mixed particles;
adding a certain amount of silicon into the first mixed particles, continuously heating and stirring for a certain time, and cooling to obtain second mixed particles;
and uniformly mixing the second mixed particles with the soft carbon precursor at normal temperature, and calcining for a certain time in a high-temperature inert gas environment to obtain the high-capacity and fast-charging lithium ion battery anode material.
Preferably, the graphite is one or more of artificial graphite, natural graphite and expanded graphite, the particle size of the graphite is 5-15 μm, and the low-temperature heat treatment is carried out in a granulating device comprising one of a horizontal granulating kettle, a vertical granulating kettle, a kneader and the like.
Preferably, the graphite is artificial graphite having a particle size of 7-12 μm.
Preferably, the low temperature heat treatment is performed at a temperature of 100-300 ℃ for a time of 0.5-3 hours.
Preferably, the mass ratio of graphite to resin is at 97%:3% -70%: between 30%.
Preferably, the carbon residue in the resin of the first mixed particles is 10-30% and the carbon residue in the graphite is 0.5% -2%.
Preferably, the silicon is nano silicon, and the mass of the silicon is 3% -15% of the mass of the graphite.
Preferably, the continuous heating is carried out at a temperature of 300-500 ℃ for a time of 1-3 hours.
Preferably, the soft carbon precursor is one or more of asphalt, glucose, dopamine and the like, the soft carbon precursor is added in a proportion according to the soft carbon residue, the soft carbon residue after carbonization is ensured to be 0.5% -5%, the mixing equipment of the second mixed particles and the soft carbon precursor comprises one of a mixer, a VC mixer and a kneader, and the mixing time of the second mixed particles and the soft carbon precursor is 1-5h.
Preferably, the inert gas in the high-temperature inert gas environment is argon or nitrogen, the temperature rising rate of the high-temperature inert gas environment is 1-10 ℃/min, the calcination temperature is 600-1200 ℃, and the calcination time is 1-5h.
In a second aspect, the application provides a high-capacity and fast-charging lithium ion battery anode material, which is prepared by the preparation method of the high-capacity and fast-charging lithium ion battery anode material according to any embodiment of the application.
The application has the following beneficial effects: the preparation method comprises the steps of granulating graphite after softening resin, distributing the resin on the surface of the graphite to enable the surface of the graphite to be sticky, adding silicon particles to enable the silicon particles to be uniformly stuck to the surface of graphite secondary particles and internal gaps, continuously increasing the temperature at the moment to volatilize most volatile matters in the resin, and bonding and fixing the cooled silicon and the graphite through the resin to avoid agglomeration of the silicon particles; the method can regulate and control the capacity of the anode material by regulating and controlling the proportion of silicon and graphite, and the graphite secondary particles can relieve the volume expansion of silicon; when the graphite and the silicon are granulated, the resin enables the silicon to be uniformly dispersed in the graphite secondary particles, and the quick charge performance of the whole material can be improved; the surface coated with soft carbon can not only reduce the specific surface of the material, but also further inhibit the volume expansion of silicon, avoid direct contact between electrolyte and hard carbon, and improve the high-temperature performance; the whole preparation process is very simple, and is beneficial to batch production.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application.
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of a preparation method of a high-capacity and fast-charging lithium ion battery anode material according to an embodiment of the application;
fig. 2 is a schematic structural diagram of a high-capacity and fast-charging lithium ion battery anode material prepared in example 1 of the present application.
Reference numerals:
1. artificial graphite; 2. nano silicon; 3. a hard carbon layer; 4. soft carbon coating.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application; it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments, and that all other embodiments obtained by persons of ordinary skill in the art without making creative efforts based on the embodiments in the present application are within the protection scope of the present application.
In the description of the present application, it should be noted that the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Chinese meaning of english abbreviations appearing
SOC: the remaining capacity of the battery.
Referring to fig. 1, in a preferred embodiment of the present application, a method for preparing a high-capacity and fast-charging lithium ion battery anode material includes the following steps:
s1: uniformly mixing graphite and resin in a certain proportion, and carrying out low-temperature heat treatment to obtain first mixed particles; in the step, graphite is one or more of artificial graphite, natural graphite and expanded graphite, the particle size of the graphite is 5-15 mu m, low-temperature heat treatment is carried out in granulation equipment, the granulation equipment comprises one of a horizontal granulation kettle, a vertical granulation kettle, a kneader and the like, specifically, a certain proportion of graphite and resin are placed in the granulation equipment to be uniformly mixed, and heat low-temperature treatment is carried out for 0.5-3 hours at 100-300 ℃ to obtain first mixed particles (graphite secondary particle structure). The softening point of the resin is between 100 and 300 ℃, and the carbon residue is between 10 and 30 percent; the ratio of graphite to resin is 97% -3% -70% -30%, and the carbon residue in the graphite is ensured to be 0.5% -2% according to the carbon residue of the resin.
S2: adding a certain amount of silicon into the first mixed particles obtained in the step S1, continuously heating and stirring for a certain time, and then cooling to obtain second mixed particles;
in the step, the silicon is nano silicon, specifically, 3-15% of the mass of graphite in the step S1 is taken and added into the first mixed particles, and the mixture is continuously heated in granulating equipment, so that the temperature is 300-500 ℃, and the mixture is heated for 1-3 hours, thus obtaining second mixed particles (silicon/graphite secondary particles).
S3: uniformly mixing the second mixed particles with the soft carbon precursor at normal temperature, and calcining for a certain time in a high-temperature inert gas environment to obtain a high-capacity and fast-charging lithium ion battery anode material; in the step, the soft carbon precursor is one or a mixture of more of asphalt, glucose, dopamine and the like, specifically, the second mixed particles obtained in the step S2 and the soft carbon precursor are uniformly mixed at normal temperature, and calcined for 1-5 hours in an inert gas filled with argon or nitrogen and the like at a high temperature environment with a temperature rising rate of 1-10 ℃/min and a temperature of 600-1200 ℃ to obtain a high-capacity and fast-charging lithium ion battery anode material; the soft carbon precursor adding proportion ensures that the soft carbon residue amount is 0.5-5% after carbonization according to the soft carbon residue amount, and the mixing equipment of the second mixed particles and the soft carbon precursor comprises one of a mixer, a VC mixer and a kneader, wherein the mixing time of the second mixed particles and the soft carbon precursor is 1-5h.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a high-capacity and fast-charging lithium ion battery anode material prepared in embodiment 1 of the present application, wherein the anode material comprises an artificial graphite 1, nano silicon 2, a hard carbon layer 3 and a soft carbon coating layer 4, specifically, the artificial graphite 1 and resin are combined with the nano silicon 2 through a granulating device to form a silicon-ink composite structure, the resin is carbonized and then converted into the hard carbon layer 3 on the surface of the silicon-ink composite structure, and finally, a soft carbon precursor such as asphalt is used for coating and carbonizing the silicon-ink composite structure to form the soft carbon coating layer 4.
Example 1
(1) And (3) weighing the artificial graphite 1 and the resin in a mass ratio of 95:5, uniformly mixing, adding into a kneader, heating to 200 ℃, and preserving heat for 1 hour to obtain graphite secondary particles (first mixed particles).
(2) And weighing nano silicon 2 accounting for 5% of the mass of graphite, adding the nano silicon 2 into a kneader, continuously heating to 400 ℃ after 1h, preserving heat for 2h, and cooling to obtain silicon-graphite secondary particles (second mixed particles).
(3) Mixing the silicon-graphite secondary particles with asphalt at 97:3, uniformly mixing in a mixer, transferring into a magnetic boat, calcining in a tube furnace under nitrogen atmosphere, heating to 1000 ℃ at a heating rate of 2 ℃/min, preserving heat for 3 hours, and naturally cooling after finishing to obtain the high-capacity and fast-charging lithium ion battery anode material.
Example 2
(1) And (3) weighing the artificial graphite 1 and the resin in a mass ratio of 95:5, uniformly mixing, adding into a kneader, heating to 200 ℃, and preserving heat for 1 hour to obtain graphite secondary particles (first mixed particles).
(2) And weighing nano silicon 2 accounting for 10% of the mass of graphite, adding the nano silicon 2 into a kneader, continuously heating to 400 ℃ after 1h, preserving heat for 2h, and cooling to obtain silicon-graphite secondary particles (second mixed particles).
(3) Mixing the silicon-graphite secondary particles with asphalt at 97:3, uniformly mixing in a mixer, transferring into a magnetic boat, calcining in a tube furnace under nitrogen atmosphere, heating to 1000 ℃ at a heating rate of 2 ℃/min, preserving heat for 3 hours, and naturally cooling after finishing to obtain the high-capacity and fast-charging lithium ion battery anode material.
Example 3
(1) And (3) weighing the artificial graphite 1 and the resin in a mass ratio of 95:5, uniformly mixing, adding into a kneader, heating to 200 ℃, and preserving heat for 1 hour to obtain graphite secondary particles (first mixed particles).
(2) And weighing nano silicon 2 accounting for 5% of the mass of graphite, adding the nano silicon 2 into a kneader, continuously heating to 400 ℃ after 1h, preserving heat for 2h, and cooling to obtain silicon-graphite secondary particles (second mixed particles).
(3) Mixing the silicon-graphite secondary particles with asphalt at a ratio of 95: and 5, uniformly mixing in a mixer, transferring into a magnetic boat, calcining in a tube furnace under the nitrogen atmosphere, heating to 1000 ℃ at a heating rate of 2 ℃/min, preserving heat for 3 hours, and naturally cooling after finishing to obtain the high-capacity and quick-charging lithium ion battery anode material.
Example 4
(1) And (3) weighing the artificial graphite 1 and the resin in a mass ratio of 90:10, uniformly mixing, adding into a kneader, heating to 200 ℃, and preserving heat for 1 hour to obtain graphite secondary particles (first mixed particles).
(2) And weighing nano silicon 2 accounting for 5% of the mass of graphite, adding the nano silicon 2 into a kneader, continuously heating to 400 ℃ after 1h, preserving heat for 2h, and cooling to obtain silicon/graphite secondary particles (second mixed particles).
(3) The silicon/graphite secondary particles (second mixed particles) described above were mixed with pitch at 97:3, uniformly mixing in a mixer, transferring into a magnetic boat, calcining in a tube furnace under nitrogen atmosphere, heating to 1000 ℃ at a heating rate of 2 ℃/min, preserving heat for 3 hours, and naturally cooling after finishing to obtain the high-capacity and fast-charging lithium ion battery anode material.
Example 5
(1) The mass ratio of the artificial graphite 1 and the resin in example 1 was replaced with 97:3, replacing the temperature with 300 ℃ and the heat preservation time with 0.5 hour, otherwise, the method is consistent with the step (1) in the example 1;
(2) The mass of nano silicon 2 in the embodiment 1 is replaced by 15% of the mass of artificial graphite in the step (1), the temperature is continuously raised to 500 ℃ after 1h, the temperature is kept for 0.5h, and then the silicon-graphite secondary particles (second mixed particles) are obtained after cooling, and the other materials are identical to the step (2) in the embodiment 1.
(3) The ratio of silicon-graphite secondary particles (second mixed particles) to pitch was replaced with 97:3, uniformly mixing in a mixer, transferring into a magnetic boat, calcining in a tube furnace under nitrogen atmosphere, heating to a temperature of 10 ℃/min, heating to 1200 ℃, preserving heat for 1h, and naturally cooling after finishing to obtain the high-capacity and fast-charging lithium ion battery anode material.
Example 6
(1) The mass ratio of the artificial graphite 1 to the resin is replaced by 70:30, 100℃and 3 hours, otherwise identical to step (1) of example 1.
(2) The mass of nano silicon 2 is replaced by 3% of the mass of artificial graphite in the step (1), the temperature is continuously raised to 300 ℃ after 1h, the temperature is kept for 3h, and then the silicon-graphite secondary particles (second mixed particles) are obtained after cooling, and the other materials are the same as those in the step (2) in the embodiment 1.
(3) The ratio of silicon-graphite secondary particles (second mixed particles) to pitch was replaced with 70: and (3) uniformly mixing the materials in a mixer in a mass ratio, transferring the mixture into a magnetic boat, calcining the mixture in a tube furnace under the argon atmosphere, heating the mixture at a heating rate of 1 ℃/min, heating the mixture to 600 ℃, preserving the heat for 5 hours, and naturally cooling the mixture after the heating is finished to obtain the high-capacity and quick-charging lithium ion battery anode material.
Negative electrode tabs were prepared from the graphite-silicon-carbon composite materials obtained in examples 1 to 4, and electrochemical performance tests were performed by assembling button cells. The method comprises the following specific steps: the graphite-silicon-carbon composite materials obtained in examples 1-3 were mixed with conductive carbon black, sodium carboxymethylcellulose (CMC) and Styrene Butadiene Rubber (SBR) in a mass ratio of 90:5:2:3, and deionized water was added to stir until uniform. The slurry is coated on copper foil, baked for 24 hours in a vacuum drying oven at 90 ℃, then rolled by a pair of rollers, and finally manufactured into a pole piece with the diameter of 14mm by a punching machine. The electrode plate is assembled into a button cell with 2025 standard by taking metal lithium as a counter electrode, a used diaphragm is a polypropylene film (Celgard 2300), electrolyte is a mixed solution of 1mol/L lithium hexafluorophosphate dissolved in ethylene carbonate and dimethyl carbonate with equal volume ratio, the assembling process is carried out in a vacuum glove box filled with high-purity nitrogen, and electrochemical performance test is carried out after the assembling is completed.
During testing, 1 group of batteries are charged and discharged with the multiplying power of 0.1C, the voltage range is 0-1.5V, and the cycle times are 100 times; and the other group of batteries is subjected to constant-current and constant-voltage capacity test at the rate of 0.1C, and is subjected to constant-current charging at the current of 4C until 100% of SOC is cut off, and the rapid lithium charging point of the materials is analyzed through a dV/dQ curve, wherein the voltage range is 0-1.5V. The electrochemical properties of the materials obtained from the above examples are shown in the following table,
table 1: results of electrochemical Performance test of the materials of examples 1 to 4
From the data obtained by the test in the table 1, the capacity of the anode material is regulated and controlled by regulating and controlling the proportion of silicon and graphite, the highest capacity can reach 603.1mAh/g, and the volume expansion of silicon can be relieved by graphite secondary particles; when the graphite and the silicon are granulated, the resin enables the silicon to be uniformly dispersed in graphite secondary particles, and the quick charge performance of the whole material can be improved, and the 4C quick charge lithium-precipitation SOC reaches 61%; according to the application, the soft carbon is coated on the surface of the anode material, so that the specific surface of the material can be reduced, the volume expansion of silicon can be further inhibited, and the electrolyte is prevented from being in direct contact with hard carbon; on the premise of quick charge, a large amount of heat is generated by quick charge, the temperature rises, and the capacity retention rate reaches 87.1% at most after the embodiment of the application is circulated for 100 weeks, so that the high-temperature performance is improved.
The above is only a preferred embodiment of the present application; the scope of the application is not limited in this respect. Any person skilled in the art, within the technical scope of the present disclosure, may apply to the present application, and the technical solution and the improvement thereof are all covered by the protection scope of the present application.
Claims (10)
1. The preparation method of the lithium ion battery anode material with high capacity and quick charge is characterized by comprising the following steps:
uniformly mixing graphite and resin in a certain proportion, and carrying out low-temperature heat treatment to obtain first mixed particles;
adding a certain amount of silicon into the first mixed particles, continuously heating and stirring for a certain time, and then cooling to obtain second mixed particles;
and uniformly mixing the second mixed particles with the soft carbon precursor at normal temperature, and calcining for a certain time in a high-temperature inert gas environment to obtain the high-capacity and fast-charging lithium ion battery anode material.
2. The method for preparing the lithium ion battery anode material with high capacity and quick charge according to claim 1, wherein the graphite is one or a mixture of more than one of artificial graphite, natural graphite and expanded graphite, the particle size of the graphite is 5-15 μm, the low-temperature heat treatment is carried out in a granulating device, and the granulating device comprises one of a horizontal granulating kettle, a vertical granulating kettle, a kneader and the like.
3. The method for preparing the lithium ion battery anode material with high capacity and quick charge according to claim 1 or 2, wherein the temperature of the low-temperature heat treatment is 100-300 ℃, and the time of the low-temperature heat treatment is 0.5-3h.
4. The method for preparing the high-capacity and fast-charging lithium ion battery anode material according to claim 3, wherein the mass ratio of the graphite to the resin is 97%:3% -70%: between 30%.
5. The method for preparing the high-capacity and fast-charging lithium ion battery anode material according to claim 4, wherein the carbon residue in the resin of the first mixed particles is 10-30%, and the carbon residue in the graphite is 0.5% -2%.
6. The preparation method of the lithium ion battery anode material with high capacity and quick charge as claimed in claim 1, wherein the silicon is nano silicon, and the mass of the silicon is 3-15% of the mass of the graphite.
7. The method for preparing the high-capacity and fast-charging lithium ion battery anode material according to claim 6, wherein the continuous heating temperature is 300-500 ℃, and the continuous heating time is 1-3h.
8. The preparation method of the lithium ion battery anode material with high capacity and quick charge as claimed in claim 1, wherein the soft carbon precursor is one or more of asphalt, glucose, dopamine and the like, the soft carbon precursor is added in a proportion of 0.5-5% of soft carbon residue after carbonization according to the soft carbon residue, and the mixing equipment of the second mixed particles and the soft carbon precursor comprises one of a mixer, a VC mixer and a kneader, and the mixing time of the second mixed particles and the soft carbon precursor is 1-5h.
9. The preparation method of the lithium ion battery anode material with high capacity and fast charge as claimed in claim 8, wherein the inert gas in the high-temperature inert gas environment is argon or nitrogen, the temperature rising rate of the high-temperature inert gas environment is 1-10 ℃/min, the calcination temperature is 600-1200 ℃, and the calcination time is 1-5h.
10. The high-capacity and fast-charging lithium ion battery anode material is characterized in that the high-capacity and fast-charging lithium ion battery anode material is prepared by the preparation method of the high-capacity and fast-charging lithium ion battery anode material according to any one of claims 1-9.
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