CN113725415A - Power type graphite-silicon oxide composite material and preparation method and application thereof - Google Patents

Power type graphite-silicon oxide composite material and preparation method and application thereof Download PDF

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CN113725415A
CN113725415A CN202111012053.1A CN202111012053A CN113725415A CN 113725415 A CN113725415 A CN 113725415A CN 202111012053 A CN202111012053 A CN 202111012053A CN 113725415 A CN113725415 A CN 113725415A
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composite material
graphite
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silicon oxide
silica
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CN113725415B (en
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冯昂
卢孟萍
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Changzhou Qidai Technology Co ltd
Changzhou Xitai Energy Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • 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

Abstract

The invention discloses a preparation method of a power type graphite-silicon oxide composite material, which comprises the following steps: step one, preparing a surfactant aqueous solution; secondly, adding the sulfonated asphalt powder into a surfactant aqueous solution, and stirring to obtain a mixed system; adding artificial graphite powder and silicon monoxide powder, and uniformly stirring to obtain mixed slurry; step four, spray granulation; step five, pre-carbonization treatment; step six, airflow crushing to break adhesion among particles; step seven, carrying out high-temperature carbonization treatment to obtain a graphite-silicon oxide composite material; the invention also discloses a lithium ion battery with the power type graphite-silicon oxide composite material; the composite material prepared by the invention has uniform slurry and is easy to mix and coat; the obtained battery is suitable for high-power charge and discharge.

Description

Power type graphite-silicon oxide composite material and preparation method and application thereof
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a power type graphite-silicon oxide composite material and a preparation method and application thereof.
Background
Lithium ion batteries have the advantages of high energy density, long cycle life, and the like, and have been widely used in the fields of consumer electronics, electric vehicles, and energy storage in recent years. In particular, lithium ion batteries for electric vehicles have been rapidly developed under the large background of carbon neutralization. The electric vehicle comprises a pure Electric Vehicle (EV) and a Hybrid Electric Vehicle (HEV) which are used as compromise schemes for the overall transition from a fuel vehicle to the pure electric vehicle, and the HEV has wide market prospects.
Unlike EV battery products, HEV batteries must have the characteristics of high-rate charge and discharge, ultra-long cycle life, and the like, to accommodate frequent kinetic energy recovery and instantaneous power requests during starting and acceleration. Compared with graphite materials, the hard carbon materials have larger interlayer spacing, allow lithium ions to be rapidly inserted and removed, and realize high-rate charge and discharge and safe charge at low temperature; meanwhile, the hard carbon material has a more stable structure than graphite, has small volume deformation in the lithium ion deintercalation process, and can realize an ultra-long cycle life. Therefore, hard carbon materials are well suited for HEV battery products and are expected to become the mainstream in this field. Hard carbon materials also have some disadvantages: (1) the first efficiency is low, and is only about 80%; (2) the gram capacity is low, and is only about 280 mAh/g. This has led to batteries using pure hard carbon materials, with generally low energy densities. In order to realize higher energy density and simultaneously keep the characteristic of high-rate charge and discharge, the existing solution generally adopts a hard carbon material and a graphite material which are physically blended according to a certain proportion for reuse.
Besides, the negative electrode is also a solution using artificial graphite with small particles with a particle size of less than 2 μm or nano-silica with a particle size of 50 to 200nm, but the small particles of graphite or silica material have great difficulty in mixing and coating because of large specific surface area. Meanwhile, the cyclic expansion of the silicon oxide material is large, which affects the cycle life of the battery. Therefore, it is urgent to find a material having high capacity characteristics of graphite and silica while simultaneously satisfying rate capability of hard carbon.
Disclosure of Invention
The invention aims to provide a preparation method of a power type graphite-silicon oxide composite material.
In order to solve the technical problem, the technical scheme of the invention is as follows: a preparation method of a power type graphite-silicon oxide composite material comprises the following steps:
step one, preparing a surfactant aqueous solution;
step two, adding sulfonated asphalt powder into the surfactant aqueous solution obtained in the step one, stirring, and filtering to remove particles to obtain a mixed system;
step three, adding artificial graphite powder and silicon monoxide powder into the mixed system in the step two, and uniformly stirring to obtain mixed slurry;
step four, spraying and granulating the mixed slurry obtained in the step three;
step five, heating and pre-carbonizing the particles obtained in the step four under inert atmosphere;
step six, airflow crushing step five to obtain a pre-carbonized composite material, and breaking adhesion among particles;
step seven, carrying out high-temperature carbonization treatment on the particles obtained in the step six to obtain a graphite-silicon oxide composite material;
the treatment temperature of the high-temperature carbonization in the seventh step is 900-1500 ℃.
Preferably, in the first step, the mass fraction of the surfactant in the surfactant aqueous solution is 1.2% to 2%. The surfactant of the invention can uniformly disperse the artificial graphite powder and the silicon oxide powder in water. The addition amount of the surfactant is more than 2%, the viscosity of the whole system is too high, the subsequent granulation is not facilitated, the addition amount is less than 1.2%, and the artificial graphite powder and the silicon oxide powder cannot be stably dispersed in water.
Preferably, the artificial graphite powder in the third step is needle coke-based artificial graphite and is prepared by crushing; d of artificial graphite powder500.5 μm to 1.5 μm;
the D50 of the silica is 50nm to 200 nm.
The needle coke-based artificial graphite selected by the invention has the advantages of gram capacity of more than 358mAh/g, good rate capability, low cyclic expansion and the like, and is suitable for being used as the main component of the invention. D of artificial graphite powder50Less than 0.5 μm, high processing difficulty and difficulty in water dispersion; d of artificial graphite powder50Larger than 1.5 μm, and the particle size is too large to facilitate the lithium ion intercalation and deintercalation, which affects the rate capability of the composite material. D of the artificial graphite powder in consideration of processability and rate capability50Is 0.5 μm to 1.5. mu.m.
D of the silica of the invention50The grain size range is 50nm to 200nm, and the grain size range is selected to balance the processing difficulty and the material expansion electrochemical performance.
D of the granules obtained by spray granulation in preferred step four50Is 15 μm to 30 μm. After the composite material obtained by the invention is carbonized at high temperature, the volume is shrunk by about 70-80%, and the particle size of the final finished product is controlled between 3-8 μm, so that the processing of the material is facilitated, and meanwhile, the better rate performance is kept. Therefore, the particle size before the high-temperature carbonization is controlled to 15 μm to 30 μm.
The preferable process conditions of the step five pre-carbonization are as follows:
the temperature is 500 ℃ to 700 ℃ and the time is 8 hours to 16 hours.
The sulfonic group and other oxygen-containing functional groups in the sulfonated asphalt are removed in the pre-carbonization stage, the composite material precursor particles are continuously shrunk in the process, and pre-carbonization is carried out at 500-700 ℃, so that the removal of the oxygen-containing functional groups can be ensured, and the particles are prevented from being cracked due to the excessively high removal speed of the functional groups at an excessively high temperature.
The treatment time for the seven-step high-temperature carbonization is preferably 12 hours to 24 hours.
The high-temperature carbonization in the invention is to further remove non-carbon miscellaneous functional groups on the basis of pre-carbonization, and simultaneously, the carbonization at higher temperature can improve the first efficiency of the sulfonated asphalt-based hard carbon. The carbonization temperature cannot be too high, and the rate capability of the hard carbon is reduced after the carbonization temperature exceeds 1500 ℃.
Preferably, the mixed slurry obtained in the third step comprises the following components in parts by weight:
40-60 parts of artificial graphite powder;
1 to 3 parts of silica;
30 to 60 portions of sulfonated asphalt powder.
The surfactant aqueous solution is 2 to 4 times of the total mass of the artificial graphite powder, the silica and the sulfonated asphalt powder. The surfactant ensures the full dispersion of the artificial graphite powder and the silica fume.
The invention aims to provide a power type graphite-silicon oxide composite material which is high in integral gram volume and good in rate capability.
In order to solve the technical problem, the technical scheme of the invention is as follows: a power type graphite-silica composite material, the composite material being in particulate form; d of the composite505 to 8 μm, and a tap density of 0.7g/cm3To 1.2g/cm3。
The invention aims to provide a lithium ion battery which is suitable for high-power charging and discharging.
In order to solve the technical problem, the technical scheme of the invention is as follows: a lithium ion battery comprises a negative plate, and the negative plate comprises the composite material prepared by the invention.
Preferably, deionized water is added into the composite material, and the mixture is stirred to obtain negative electrode slurry.
By adopting the technical scheme, the invention has the beneficial effects that:
the composite material prepared by the invention has smaller D50The lithium ion is convenient to rapidly insert and remove, and the composite material obtained by the invention has excellent rapid charge and discharge performance; meanwhile, the tap density equivalent to that of the artificial graphite material is kept, and the material is ensured to have better processing performance;
in the preparation process, the artificial stone toner and the silica powder are insoluble in water and can only be dispersed in water in a particle shape, and the sulfonated asphalt can be completely dissolved in water, so that the sulfonated asphalt can completely wrap artificial graphite particles and silica particles as a precursor of hard carbon; in the spray granulation stage, the particle morphology is controlled by controlling the spray speed and the temperature of a drying chamber, so that a composite material similar to a pomegranate structure is obtained; the invention has the advantages of preparing blocky shape instead of spherical shape, being beneficial to improving the integral tap density and reducing the dosage of the conductive agent when preparing the negative pole piece.
The invention constructs a composite material with a structure similar to the structure of the pomegranate, wherein small-particle artificial graphite and nano-silicon oxide are used for improving the integral gram capacity of the material, and water-soluble sulfonated asphalt-based hard carbon is used as a connecting tissue and a shell between the small-particle artificial graphite and the nano-silicon oxide particles, so that the rapid insertion and extraction of lithium ions are ensured, and meanwhile, the expansion of the artificial graphite and the silicon oxide particles can be effectively inhibited by the whole hard carbon tissue, so that the cycle life of the composite material is prolonged;
compared with the prior art, the power type composite material has the advantages that the excellent rate performance and the higher energy density are both considered, and meanwhile, the preparation process of the material uses pure water to replace an organic solvent, so that the power type composite material is green and environment-friendly.
Thereby achieving the above object of the present invention.
Drawings
FIG. 1 is an SEM image of a graphite-silica composite material prepared in example 1 of the present invention.
Detailed Description
In order to further explain the technical solution of the present invention, the present invention is explained in detail by the following specific examples.
Example 1
The embodiment discloses a preparation method of a power type graphite-silicon oxide composite material, which comprises the following steps:
step one, preparing a surfactant aqueous solution;
preparing 30 parts of a Tween 80 aqueous solution with the mass percent of 1.5%;
step two, adding 30 parts by weight of sulfonated asphalt powder into the surfactant aqueous solution obtained in the step one, stirring for 2 hours, and filtering to remove particles to obtain a mixed system;
step three, adding artificial graphite powder and silicon monoxide powder into the mixed system in the step two, and uniformly stirring to obtain mixed slurry;
selecting needle coke-based artificial graphite, crushing the artificial graphite by using a ball mill or a sand mill, screening 40 parts of fine powder with D50 of 0.5-1.5 mu m, and selecting 1 part of commercially available silica material with D50 of 50-200 nm;
adding the graphite-making fine powder and the silica material into the mixed solution of the sulfonated asphalt and the Tween 80, and stirring for 5 hours;
step four, spraying and granulating the mixed slurry obtained in the step three;
step five, heating and pre-carbonizing the particles obtained in the step four under inert atmosphere;
the pre-carbonization treatment temperature is 550 ℃, and the treatment time is 12 hours;
step six, airflow crushing step five to obtain a pre-carbonized composite material, and breaking adhesion among particles;
step seven, carrying out high-temperature carbonization treatment on the particles obtained in the step six to obtain a graphite-silicon oxide composite material;
the high-temperature carbonization treatment temperature is 1500 ℃, the treatment time is 24 hours, the high-temperature carbonization treatment is carried out in the nitrogen atmosphere, and finally the power type graphite-silicon oxide composite material is obtained.
The composite material obtained had a D50 of 6 μm and a tap density of 1.0g/cm3。
Example 2
The embodiment discloses a preparation method of a power type graphite-silicon oxide composite material, which comprises the following steps:
step one, preparing a surfactant aqueous solution;
preparing 31 parts of a tween 80 aqueous solution with the mass percent of 1.5%;
step two, adding sulfonated asphalt powder into the surfactant aqueous solution obtained in the step one, stirring, and filtering to remove particles to obtain a mixed system;
adding 30 parts of sulfonated asphalt powder into a surfactant aqueous solution, stirring for 2 hours, and removing insoluble particles;
step three, adding artificial graphite powder and silicon monoxide powder into the mixed system in the step two, and uniformly stirring to obtain mixed slurry;
selecting needle coke-based artificial graphite, crushing the artificial graphite by using a ball mill or a sand mill, and screening D5040 parts of fine powder with the particle size of 0.5-1.5 μm, and selecting commercial D502 parts of silicon oxide material between 50 and 200 nm;
adding the artificial graphite fine powder and the silica material into the mixed solution of the sulfonated asphalt and the tween 80, and stirring for 5 hours;
step four, spraying and granulating the mixed slurry obtained in the step three; the resulting particles D50At 15 μm to 30 μm;
step five, heating and pre-carbonizing the particles obtained in the step four under inert atmosphere;
the temperature of the pre-carbonization treatment is 550 ℃, the treatment time is 12 hours, and the pre-carbonization treatment is carried out in the nitrogen atmosphere;
step six, airflow crushing step five to obtain a pre-carbonized composite material, and breaking adhesion among particles;
step seven, carrying out high-temperature carbonization treatment on the particles obtained in the step six to obtain a graphite-silicon oxide composite material;
and the treatment temperature of the high-temperature carbonization in the step seven is 1500 ℃, and the treatment time is 24 hours.
Example 3
The embodiment discloses a preparation method of a power type graphite-silicon oxide composite material, which comprises the following steps:
step one, preparing a surfactant aqueous solution;
43 parts of a tween 80 aqueous solution with the mass percent of 1.5 percent is prepared;
step two, adding sulfonated asphalt powder into the surfactant aqueous solution obtained in the step one, stirring, and filtering to remove particles to obtain a mixed system;
adding 60 parts of sulfonated asphalt powder into a surfactant solution, stirring for 2 hours, and removing insoluble particles;
step three, adding artificial graphite powder and silicon monoxide powder into the mixed system in the step two, and uniformly stirring to obtain mixed slurry;
selecting needle coke-based artificial graphite, and pulverizing the artificial graphite by using a ball mill or a sand millScreening D5040 parts of fine powder with the particle size of 0.5-1.5 μm, and selecting commercial D501 part of silicon oxide material between 50 and 200 nm;
adding the artificial graphite fine powder and the silica material into the mixed solution of the sulfonated asphalt and the tween 80, and stirring for 5 hours;
step four, spraying and granulating the mixed slurry obtained in the step three; d of the resulting granules50Between 15 μm and 30 μm;
step five, heating and pre-carbonizing the particles obtained in the step four under inert atmosphere;
the temperature of the pre-carbonization treatment is 550 ℃, the treatment time is 12 hours, and the pre-carbonization treatment is carried out in the nitrogen atmosphere;
step six, airflow crushing step five to obtain a pre-carbonized composite material, and breaking adhesion among particles;
step seven, carrying out high-temperature carbonization treatment on the particles obtained in the step six to obtain a graphite-silicon oxide composite material;
and seventhly, performing high-temperature carbonization at 1500 ℃ for 24 hours in a nitrogen atmosphere.
Comparative example 1
The preparation method of the composite material comprises the following steps:
step one, selecting needle coke-based artificial graphite, crushing the artificial graphite by using a ball mill or a sand mill, and screening D5050 portions of fine powder between 0.5 and 1.5 mu m, and the commercial D is selected501 part of silicon oxide material between 50 and 200 nm;
and step two, uniformly mixing the two materials to obtain the graphite-silicon oxide physical composite material.
Comparative example 2
Selecting commercially available needle coke-based artificial graphite D50Is 14 μm to 17 μm.
Button cells were prepared using the composites obtained in examples 1 to 3 and comparative examples 1 and 2:
(1) mixing the composite materials prepared in the examples 1 to 3 and the comparative example 1 with a binder of polyvinylidene fluoride (PVDF) and conductive carbon black according to a mass ratio of 93:4:3, adding N-methyl pyrrolidone (NMP), stirring to prepare slurry, coating the slurry on a copper foil, drying, tabletting and punching to prepare a negative plate with the diameter of 1 cm;
(2) and baking the negative plate in a vacuum oven at 110 ℃ for 12h, taking a metal lithium plate as a counter electrode, a polypropylene film with the thickness of 25 mu m as a separation film, and taking a mixed solvent (EC: DMC: EMC 1:1:1) containing L mol/L LiPF6 as an electrolyte. Assembling the semi-cells in a glove box filled with argon;
(3) and testing the first reversible capacity and the first coulombic efficiency of the half-cell at 0.2C, wherein the first coulombic efficiency is calculated according to a formula of first coulombic efficiency which is first charging capacity/first discharging capacity.
Lithium ion batteries were prepared using the materials obtained in examples 1 to 3 and comparative examples 1 and 2:
(1) manufacture of positive plate
Adding 94 percent, 3 percent and 3 percent of D50 which is 2-4 mu m nickel cobalt lithium manganate (NCM111), conductive carbon black and PVDF into a proper amount of N-methylpyrrolidone (NMP) solvent according to mass percentage, and stirring to obtain positive electrode slurry with the solid content of 76 percent. The positive plate is prepared through the working procedures of coating, rolling and die cutting.
(2) Negative electrode sheet fabrication (examples 1 to 3 and comparative examples 1 to 2, respectively, as negative electrode materials)
Adding the composite material, the conductive carbon black, the CMC and the SBR, removing the solvent into a proper amount of deionized water according to the pure substance proportion of 95.2 percent, 1.5 percent and 1.8 percent, and stirring to obtain the cathode slurry with the solid content of 48 percent. And coating, rolling and die cutting to obtain the negative plate.
(3) The soft package laminated battery is prepared by using a polypropylene film with the porosity of 45% through the working procedures of lamination, prewelding, tab welding, top side sealing, vacuum baking, liquid injection, formation and capacity grading.
Performance tests were performed using the lithium ion batteries prepared using the composite materials obtained in examples 1 to 3 and comparative examples 1 and 2, and specifically included the following test items:
(1) and (3) rate discharge test: and (3) fully charging the finished soft package laminated battery at normal temperature, discharging at 0.5C and 10C multiplying power respectively, recording discharge capacity, and calculating the percentage of 10C discharge capacity/0.5C discharge capacity respectively.
(2) And (3) cycle testing: and (3) carrying out 5C charging and 5C discharging cycle test on the battery at the temperature of 25 ℃, and counting the capacity retention rate and the expansion rate of the soft package battery which are cycled for 100 times.
TABLE 1 comparison of the properties of button cells and laminate pouch cells obtained from the composites obtained in examples 1 to 3 and comparative example 1
Figure BDA0003239279260000101
As can be seen from table 1, in examples 1 to 3, power type composite materials with different gram capacities and first efficiencies can be prepared by adjusting the mixture ratio of the artificial graphite, the silica and the sulfonated asphalt. In example 2, compared with example 1, the content of the silica is increased, the gram volume is obviously increased, and the corresponding rate performance and cycle performance are slightly deteriorated. Example 3 compared to example 1, the sulfonated asphalt content increased, the gram volume decreased, and the corresponding rate capability and cycle performance became better.
Examples 1 to 3 compared to comparative example 1, the graphite-silica composite obtained by the process of the present invention has more excellent electrochemical performance than the simple physical mixing of graphite/silica.
The performance test of the lithium ion battery prepared by using the composite materials obtained in examples 1 to 3 and comparative example 2 specifically includes the following test items:
(1) and (3) low-temperature charging test: the batteries were left to stand at 25 deg.C, -20 deg.C, -40 deg.C for 24 hours, respectively, and then the batteries were charged, and the percentage of the charge capacity at low temperature was calculated with the charge capacity at 25 deg.C as 100%.
(2) And (3) low-temperature discharge test: after the battery is fully charged at normal temperature, the battery is respectively placed at 25 ℃, 20 ℃ and 40 ℃ for standing for 24 hours, then the battery is discharged, the discharge capacity at 25 ℃ is taken as 100%, and the discharge capacity percentage at low temperature is calculated.
TABLE 2 comparison of the performances of the laminate pouch batteries obtained in examples 1 to 3 and comparative example 2
Figure BDA0003239279260000111
As can be seen from table 2, the batteries of comparative example 2 used conventional artificial graphite, compared to the batteries of examples 1 to 3 using the composite material prepared according to the present invention, the low temperature charge and discharge performance was greatly improved, indicating that the composite material prepared according to the present invention can be applied to the low temperature field.
In conclusion, the invention provides the graphite-silicon monoxide composite material with the pomegranate-like structure, materials with different electrochemical performances can be obtained by adjusting the proportion of corresponding components, and the material synthesis process is simple and environment-friendly. The composite material can be applied to the application fields of high-rate charge and discharge, low-temperature charge and discharge and the like.

Claims (10)

1. A preparation method of a power type graphite-silicon oxide composite material is characterized by comprising the following steps: the method comprises the following steps:
step one, preparing a surfactant aqueous solution;
step two, adding sulfonated asphalt powder into the surfactant aqueous solution obtained in the step one, stirring, and filtering to remove particles to obtain a mixed system;
step three, adding artificial graphite powder and silicon monoxide powder into the mixed system in the step two, and uniformly stirring to obtain mixed slurry;
step four, spraying and granulating the mixed slurry obtained in the step three;
step five, heating and pre-carbonizing the particles obtained in the step four under inert atmosphere;
step six, airflow crushing step five to obtain a pre-carbonized composite material, and breaking adhesion among particles;
step seven, carrying out high-temperature carbonization treatment on the particles obtained in the step six to obtain a graphite-silicon oxide composite material;
the treatment temperature of the high-temperature carbonization in the seventh step is 900-1500 ℃.
2. The method of claim 1, wherein the graphite-silica composite material comprises: in the first step, the mass fraction of the surfactant in the surfactant aqueous solution is 1.2-2%.
3. The method of claim 1, wherein the graphite-silica composite material comprises: in the third step, the artificial graphite powder is prepared by crushing needle coke-based artificial graphite; d of artificial graphite powder500.5 μm to 1.5 μm;
d of silicon monoxide50Is 50nm to 200 nm.
4. The method of claim 1, wherein the graphite-silica composite material comprises: d of the granules obtained in step four by spray granulation50Is 15 μm to 30 μm.
5. The method of claim 1, wherein the graphite-silica composite material comprises: the process conditions of the step five pre-carbonization are as follows:
the temperature is 500 ℃ to 700 ℃ and the time is 8 hours to 16 hours.
6. The method of claim 1, wherein the graphite-silica composite material comprises: the treatment time of the high-temperature carbonization in the step seven is 12 to 24 hours.
7. The method of claim 1, wherein the graphite-silica composite material comprises: the mixed slurry obtained in the third step comprises the following components in parts by weight:
40-60 parts of artificial graphite powder;
1 to 3 parts of silica;
30 to 60 portions of sulfonated asphalt powder.
The surfactant aqueous solution is 2 to 4 times of the total mass of the artificial graphite powder, the silica and the sulfonated asphalt powder.
8. A power type graphite-silica composite material produced by the production method according to any one of claims 1 to 7, characterized in that: the composite material is granular; d of the composite505 to 8 μm, and a tap density of 0.7g/cm3To 1.2g/cm3。
9. A lithium ion battery, characterized by: comprising a negative electrode sheet comprising the composite material prepared according to any one of claims 1 to 7.
10. The lithium ion battery of claim 9, wherein: and adding deionized water into the composite material, and stirring to obtain the cathode slurry.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102646819A (en) * 2012-05-03 2012-08-22 天津大学 Preparation method of carbon-coated natural crystalline flake graphite composite for lithium ion batteries
CN105836728A (en) * 2016-03-22 2016-08-10 福建翔丰华新能源材料有限公司 Preparation method for asphalt hard carbon negative electrode material for lithium ion battery
CN110391406A (en) * 2019-07-01 2019-10-29 深圳市比克动力电池有限公司 A kind of lithium ion battery silicon oxygen negative electrode material and preparation method thereof, lithium ion battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102646819A (en) * 2012-05-03 2012-08-22 天津大学 Preparation method of carbon-coated natural crystalline flake graphite composite for lithium ion batteries
CN105836728A (en) * 2016-03-22 2016-08-10 福建翔丰华新能源材料有限公司 Preparation method for asphalt hard carbon negative electrode material for lithium ion battery
CN110391406A (en) * 2019-07-01 2019-10-29 深圳市比克动力电池有限公司 A kind of lithium ion battery silicon oxygen negative electrode material and preparation method thereof, lithium ion battery

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