CN110176585B - Silicon-carbon composite material and powder metallurgy preparation method thereof - Google Patents

Silicon-carbon composite material and powder metallurgy preparation method thereof Download PDF

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CN110176585B
CN110176585B CN201910403028.2A CN201910403028A CN110176585B CN 110176585 B CN110176585 B CN 110176585B CN 201910403028 A CN201910403028 A CN 201910403028A CN 110176585 B CN110176585 B CN 110176585B
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CN110176585A (en
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钟正刚
芦亚楠
豆大根
史利涛
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Henan Yingchuan New Material Inc
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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
    • 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
    • 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
    • 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
    • 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
    • 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 silicon-carbon composite powder material, belonging to the field of powder material preparation, and particularly relating to a preparation method of a silicon-carbon composite powder material by using a powder metallurgy production method and a mechanical grinding process, wherein the powder metallurgy method is to prepare (porous) silicon-carbon atomized powder by using a high-pressure water atomization system through water atomization, and then prepare silicon-carbon composite powder with stable carbon-silicon components and required granularity through the mechanical grinding process, the main particle components in the powder material are Si and C, silicon is a porous framework, carbon is filled in pore channels of the silicon and covers the surface of silicon-carbon particles in the form of a film, the silicon and the carbon are mainly in a free element state, and a small amount of SiC, SiO and SiO are covered on the surface of silicon-carbon particles2Etc., wherein the mass fraction of Si is 15-70%, and the mass fraction of C is 85-30%; powder end product D50Less than 5 microns, narrow particle size distribution, DmaxControlling the particle size within 30 micrometers; the tap density is 0.5-1.0g/cm3The method has the advantages of easily obtained and feasible raw materials, large-scale automatic clean production and potential application to the cathode of the battery, particularly the cathode of the lithium ion battery.

Description

Silicon-carbon composite material and powder metallurgy preparation method thereof
Technical Field
The invention belongs to the technical field of powder materials, and particularly relates to a silicon-carbon composite material and a powder metallurgy preparation method thereof.
Background
Regarding the preparation of lithium ion battery cathode materials, there are many studies and related documents in China, especially the preparation of fire heat by using silicon-carbon cathode materials, and the preparation method of the silicon-carbon cathode materials is researched, and the chemical vapor deposition method, the high-temperature solid-phase synthesis method, namely, the high-temperature pyrolysis method, the sol-gel method, the hydrothermal synthesis method, the electrostatic spinning method, the mechanical alloying and the like by using the vapor deposition method are generally seen, and carbon nano tubes, graphene, metallic aluminum, nickel, iron, copper and the like are introduced. The document with patent application number 201711050907.9 discloses a method for preparing silicon-carbon composite powder by vacuum atomization and pyrolysis of carbon source gas. The advantages of the method are not described again, but the method has the defects that samples can be made in small batches in a laboratory, but the industrialization is still difficult to realize, and from the current industrialization situation, only individual enterprises can make the mass fraction of silicon in the silicon-carbon composite anode material reach about 10%, but the problems of poor cyclicity and low reversible capacity retention rate of the lithium ion battery anode silicon-carbon composite material still exist.
Disclosure of Invention
The invention aims to provide a silicon-carbon composite material and a preparation method of powder metallurgy thereof.
In order to achieve the purpose, the invention adopts the technical scheme that:
a powder metallurgy preparation method of a silicon-carbon composite material comprises the following steps:
step 1) putting silicon into a medium-frequency induction furnace, heating and smelting the silicon into liquid, then adding a carburant into the smelted liquid, wherein the carburant is granular, the particle size of the carburant is 10-200 meshes, the adding proportion is 3-15% of the volume of the silicon liquid, then powering off and standing the mixed solution for 3-5min, removing surface scum, continuing to electrify while adjusting high-pressure water atomization pressure to 30-50MPa, atomizing the mixed solution into silicon-carbon water atomized powder, and sieving the dried powder by a 40-mesh sieve to obtain silicon-carbon original powder;
step 2), mixing silicon-carbon original powder and carbon powder according to the ratio of Si: c = (15% -70%): (30% -85%) wet-grinding in grinding equipment to DmaxThe silicon-carbon composite material is obtained when the particle size is less than 30 microns.
Further, in the step 1), the content of impurities in the original silicon-carbon powder is less than 5%, the mass percent of Si in the pure original silicon-carbon powder is 60-90%, the mass percent of C is 10-40%, and the powder particle size distribution D of the original silicon-carbon powder ismaxNot more than 150 μm, D50At 70 microns, the volume porosity of the powder particles is 5-20%, and the carbon particles which are not completely decomposed are embedded in the silicon base in a dispersed manner.
Further, in the step 2)The content of impurities in the silicon-carbon composite material is less than 5 percent, and the tap density is 0.5-1.0g/cm3。
Further, the working frequency of the medium-frequency induction furnace in the step 1) is 10-50 Hz, the heating temperature is 1550-1600 ℃, the raw material silicon is in a block shape with the purity of not less than 99.7%, the fixed carbon content of the carburant is more than 98%, the moisture content is less than 0.5%, the impurity content in the carburant is less than 0.5%, and the granularity is 10-200 meshes.
Further, in the step 2), the fixed carbon of the carbon powder is more than 99%, the impurity is less than 1%, the carbon powder and the silicon-carbon original powder are ground by a wet method, distilled water or purified water is used as a solvent, the grinding temperature is lower than 50 ℃, the size of a grinding medium is 5-20 mm, the ratio of the grinding medium to the grinding material is 4-10:1, the ratio of water to the grinding material is 3-5:1, the grinding time is not less than 50 hours, preferably 72 hours, and D is obtained50Is 0.5 micron.
A silicon-carbon composite material is prepared through filling the carbon in the core position in the particles of said composite material in the pores and distributing the carbon particles in the silicon matrix in network mode, and combining the carbon layer in the shell with the silicon-carbon body in the core position.
The invention has the advantages that: the invention uses (high pressure) water atomization method to prepare silicon-carbon atomized powder, and prepares silicon-carbon composite powder with stable carbon-silicon components through subsequent grinding. The main components of the particles in the powder material are Si and C, the silicon is a porous framework, and the carbon is filled in the pore channels of the silicon and covers the surfaces of the silicon-carbon particles in the form of a film. Silicon and carbon are mainly in free elemental state, and a small amount of SiC, SiO and SiO2And the like. Generally, the texture of the particles in the material is silicon and carbon, and both are mainly in a free state. The carbon is in graphite state and is distributed in silicon base in network form, the surface of the granule is inlaid with carbon element, and a small quantity of SiC, SiO and SiO2And the structure can effectively solve the defects of poor cyclicity and low reversible capacity retention rate of the lithium ion battery cathode silicon-carbon composite material.
Detailed Description
Example 1
A powder metallurgy preparation method of a silicon-carbon composite material comprises the following steps:
step 1) putting silicon in a 10-50 Hz medium-frequency induction furnace, heating to 1550-1600 ℃ to smelt into liquid, adding a carburant into the smelted liquid, wherein the carburant is granular, the particle size of the carburant is 10-200 meshes, the adding proportion is 3-15% of the volume of the silicon liquid, a small amount of gas (carbon monoxide or carbon dioxide or mixed gas) can be generated due to the contact of carbon and the high-temperature silicon liquid, then powering off and standing the mixed solution for 3-5min, removing surface scum, continuously electrifying while adjusting the high-pressure water pressure to 30-50MPa, atomizing the mixed solution into silicon-carbon powder by using high-pressure water, sieving the dried powder by using a 40-mesh sieve to obtain silicon-carbon original powder, wherein the content of impurities in the silicon-carbon original powder is less than 5%, the mass percent of Si in the pure silicon-carbon original powder is 60-90%, and the mass percent of C is 10-40%, powder particle size distribution D of silicon-carbon original powdermaxNot more than 150 μm, D50At 70 microns, the volume porosity of the powder particles is 5% -20%, and the carbon particles which are not completely decomposed are embedded in the silicon substrate in a dispersed manner;
step 2), mixing silicon-carbon original powder and carbon powder according to the ratio of Si: c = (15% -70%): (30% -85%) wet-grinding in grinding equipment to DmaxThe silicon-carbon composite material is obtained when the particle size is less than 30 micrometers, the content of impurities in the silicon-carbon composite material is less than 5%, the mass fraction of Si in the pure silicon-carbon composite material is 15% -70%, and the C content is 85% -30%; it D50Less than 5 microns, DmaxLess than 30 microns and tap density of 0.5-1.0g/cm3In the silicon-carbon original powder, the particles are rapidly solidified in the atomization process, so that the wrapping gas (CO and CO) appears in the particles2Etc.) are filled in the pore channel, carbon in the silicon-carbon particles is randomly distributed in the silicon base, the carbon particles form a network passage, the conductivity of the silicon particles is enhanced, and most importantly, when the silicon-carbon composite powder produced by the method is used for the negative electrode of the lithium battery, silicon in the superfine particles is probably prevented from directly contacting with electrolyte, and the stability of an SEI film is ensured.
Further, the operating frequency of the medium-frequency induction furnace in the step 1) is that the raw material silicon is in a block shape with the purity of not less than 99.7%, the fixed carbon content of the carburant is more than 98%, the water content is less than 0.5%, the impurity content is less than 0.5%, and the granularity is 10-200 meshes.
Further, in the step 2), the fixed carbon of the carbon powder is more than 99%, the impurity is less than 1%, the carbon powder and the silicon-carbon original powder are ground by a wet method, the grinding temperature is lower than 50 ℃, the size of a grinding medium is 5-20 mm, the ratio of the grinding medium to the grinding material is 4-10:1, the ratio of water to the grinding material is 3-5:1, the grinding time is not less than 50 hours, preferably about 72 hours, and D is obtained50And may be as low as about 0.5 microns. .
A silicon-carbon composite material is prepared by the above preparation method, wherein the core part of the silicon-carbon composite material is filled with carbon in pores or dispersed in silicon base in a micro-particle manner, and the shell carbon layer is combined with the silicon-carbon body of the core part in a rugged manner.
Example 2
The small intermediate frequency test smelting furnace has a furnace volume of 50 kg. Because the specific weight of silicon and carbon is light, the actual batching is 30 kg, and the burning loss value of silicon and carbon is estimated initially.
According to the formula, 25 kg (30 multiplied by 75%/90% =25 kg) of metal silicon, 10 kg (30 multiplied by 25%/75% =10 kg) of high-purity carburant and 35 kg of total weight of ingredients are weighed according to the formula that Si is C =75:25, the Si burning loss value is 10% and the C burning loss is 25%.
And (4) atomizing under high pressure water to prepare powder after smelting, and drying and screening to obtain silicon-carbon master powder. The composition detection shows that the Si content is 73.2%, the C content is 26.3%, and the 0.5% is impurities. The calculated Si burn-out was 13.84% and C17.97%, and the burn-out value was adjusted in production according to the results.
Sieving with 200 mesh sieve, and detecting with laser particle sizer for 3 times. It D5027.6, 29.3, 26.4 microns, average 27.8 microns.
Example 3
27.9 kg (30 x 80%/86% =27.9 kg) of metal silicon, 7.3 kg (30 x 20%/82% =7.3 kg) of high-purity carburant and 35.2 kg of the total weight of the ingredients are weighed according to Si: C =80:20, Si burning value 14% and C burning value 18% by using the small intermediate frequency smelting furnace.
And (4) directly casting ingots after smelting, directly crushing the ingots due to the fact that silicon is crisp, and sieving the crushed ingots to obtain silicon-carbon mother powder. Through component detection, the content of Si is 80.46%, the content of C is 19.43%, and the content of other impurities is also reliable.
Sieving with 200 mesh sieve, and detecting with laser particle sizer for 3 times. Its D50 was 38.63, 40.94, 41.31 microns, averaged 40.29 microns.
Example 4
Mixing the silicon-carbon mother powder and the high-purity graphite recarburizing agent according to the proportion of 1:1 for 20 kg, using a grinding medium with the thickness of 10 mm and the grinding medium and material ratio of 6:1, carrying out dry grinding and sieving, sampling for 30 hours, 40 hours, 50 hours, 60 hours and 70 hours, and analyzing the D content of the sample50And DmaxDistribution characteristics of (D) to an interval of 50-60 hours50And DmaxNear the turning point of the plateau to 70 hours D50And DmaxSubstantially maintained at about 0.68 microns and 28.9 microns.

Claims (3)

1. The powder metallurgy preparation method of the silicon-carbon composite material is characterized by comprising the following steps:
step 1) putting silicon into a medium-frequency induction furnace, heating and smelting the silicon into liquid, then adding a carburant into the smelted liquid, wherein the carburant is granular, the particle size of the carburant is 10-200 meshes, the adding proportion is 3-15% of the volume of the silicon liquid, then powering off and standing the mixed solution for 3-5min, removing surface scum, continuing to electrify while adjusting high-pressure water atomization pressure to 30-50MPa, atomizing the mixed solution into silicon-carbon water atomized powder, sieving the dried powder by a 40-mesh sieve to obtain silicon-carbon original powder, wherein the content of impurities in the silicon-carbon original powder is less than 5%, the mass percentage of Si in the pure silicon-carbon original powder is 60-90%, the mass percentage of C is 10-40%, and the powder granularity distribution D of the silicon-carbon original powder is DmaxNot more than 150 μm, D5070 microns, the volume porosity of the powder particles is 5-20%, and the carbon particles which are not completely decomposed are embedded in the silicon substrate in a dispersed state;
step 2), mixing silicon-carbon original powder and carbon powder according to the ratio of Si: c = (15% -70%): (30% -85%) wet-grinding in grinding equipment to DmaxThe silicon-carbon composite material is obtained with the particle size of less than 30 microns, the content of impurities in the silicon-carbon composite material is less than 5 percent, and the tap density is 0.5 to 1.0g/cm3The fixed carbon of the carbon powder is more than 99 percent, the impurity is less than 1 percent, and the carbon powder and the silicon carbonThe original powder is ground by a wet method, distilled water or purified water is used as a solvent, the grinding temperature is lower than 50 ℃, the size of a grinding medium is 5-20 mm, the ratio of the grinding medium to the grinding material is 4-10:1, the ratio of the water to the grinding material is 3-5:1, and the grinding time is not less than 50 hours.
2. The powder metallurgical preparation method of a silicon-carbon composite material according to claim 1, wherein: the working frequency of the medium-frequency induction furnace in the step 1) is 10-50 Hz, the heating temperature is 1550-1600 ℃, the raw material silicon is in a block shape with the purity of not less than 99.7%, the fixed carbon content of the recarburizing agent is more than 98%, the water content is less than 0.5%, and the impurity content in the recarburizing agent is less than 0.5%.
3. A silicon-carbon composite material, characterized in that, prepared by the preparation method of any one of claims 1-2, the core part carbon of the particle is distributed in a silicon substrate in a network shape, and the shell part carbon layer is combined with the silicon-carbon body of the core part in a rugged shape.
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WO2017024903A1 (en) * 2015-08-07 2017-02-16 田东 Preparation method for tin-carbon composite negative electrode material
CN107887582A (en) * 2017-10-31 2018-04-06 东莞市鸿德电池有限公司 A kind of silicon/carbon dust powder composite material and preparation method thereof and cell negative electrode material
CN109273680A (en) * 2018-08-29 2019-01-25 四川西丹孚能源科技有限公司 A kind of porous silicon-carbon cathode material and preparation method thereof and lithium ion battery

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Publication number Priority date Publication date Assignee Title
CN102437318A (en) * 2011-11-30 2012-05-02 奇瑞汽车股份有限公司 Preparation method for silicon-carbon composite material, prepared silicon-carbon composite material, lithium ion battery anode containing silicon-carbon composite material and battery
CN104979540A (en) * 2015-07-09 2015-10-14 东北师范大学 Preparation method and application of bicontinuous-structural nanocomposite material
WO2017024903A1 (en) * 2015-08-07 2017-02-16 田东 Preparation method for tin-carbon composite negative electrode material
CN107887582A (en) * 2017-10-31 2018-04-06 东莞市鸿德电池有限公司 A kind of silicon/carbon dust powder composite material and preparation method thereof and cell negative electrode material
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