CN112768668A - Lithium ion battery silicon-carbon negative electrode material and preparation process and equipment thereof - Google Patents

Lithium ion battery silicon-carbon negative electrode material and preparation process and equipment thereof Download PDF

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CN112768668A
CN112768668A CN202110137754.1A CN202110137754A CN112768668A CN 112768668 A CN112768668 A CN 112768668A CN 202110137754 A CN202110137754 A CN 202110137754A CN 112768668 A CN112768668 A CN 112768668A
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silicon
carbon
lithium ion
ion battery
plate
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言伟雄
袁建陵
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Zhuzhou Fullad 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
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
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    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • C23C16/513—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using plasma jets
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/54—Apparatus specially adapted for continuous coating
    • 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
    • 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 silicon-carbon negative electrode material of a lithium ion battery and a preparation process and equipment thereof, wherein the negative electrode material comprises a base material and nano-silicon deposited on the surface of the base material, the base material is a carbon material, the nano-silicon is deposited on the surface of the base material through a plasma enhanced chemical vapor deposition process, the base material is in a fluidized motion state in a deposition area in the plasma enhanced chemical vapor deposition process, the plasma enhanced chemical vapor deposition process is carried out in a fluidized plasma vapor deposition furnace, a positive plate and a negative plate are arranged in the fluidized plasma vapor deposition furnace, the deposition area is arranged between the positive plate and the negative plate, and the base material is in fluidized motion in the deposition area under the vibration action of the negative plate. According to the invention, the base material is fluidized and flows in the deposition process, so that the nano silicon is uniformly and firmly distributed on the carbon material, the problem of agglomeration of the nano silicon due to dissociation is solved, and the nano silicon serving as the negative electrode material of the lithium ion battery can effectively improve the working performance of the battery.

Description

Lithium ion battery silicon-carbon negative electrode material and preparation process and equipment thereof
Technical Field
The invention relates to the technical field of lithium ion battery cathode materials, in particular to a lithium ion battery silicon-carbon cathode material and a preparation process and equipment thereof.
Background
The lithium ion battery is a mature secondary battery, and with the continuous progress and development of society, the requirements of people on the negative electrode material of the lithium ion battery are higher and higher, and the traditional graphite negative electrode material cannot further meet the miniaturization requirements of electronic equipment and the high-power and high-energy density requirements of the vehicle battery because the capacity is close to the theoretical capacity of 372 mAh/g. The silicon-carbon negative electrode material is an advanced lithium ion battery negative electrode material capable of replacing a graphite negative electrode material, and the market share of the silicon-carbon negative electrode material is rapidly increasing.
The existing silicon-carbon cathode material preparation process generally adopts a high-energy grinding process to prepare silicon oxide nanoparticles in a silicon-carbon cathode material, and as the nano silicon oxide and a carbon material are in a free state, the phenomenon of agglomeration of the nano silicon oxide cannot be solved, so that the nano silicon oxide cannot be uniformly distributed in the carbon material, and in addition, the combination of the nano silicon oxide particles and the carbon is not tight or the bonding force is not strong, so that the quick charge performance and the service life of a lithium ion battery are seriously influenced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a silicon-carbon cathode material of a lithium ion battery, which comprises a base material and simple substance nano-silicon particles deposited on the surface of the base material, wherein the base material flows in a fluidization manner in the deposition process, and a plasma enhanced chemical vapor deposition process is adopted, so that the nano-silicon can be uniformly and firmly distributed on the surface of the base material, and the rapid charge-discharge performance and the cycle performance of the lithium ion battery are effectively improved on the premise of ensuring the high capacity and the high energy density of the lithium ion battery.
The invention also aims to provide the preparation process of the silicon-carbon cathode material of the lithium ion battery, which has the advantages of simple process, uniform and consistent prepared cathode material, large-scale industrial production and realization of industrialization.
The purpose of the invention is realized by the following technical scheme:
a silicon-carbon negative electrode material of a lithium ion battery comprises a base material and nano silicon deposited on the surface of the base material, wherein the base material is a carbon material, the nano silicon is deposited on the surface of the base material through a plasma enhanced chemical vapor deposition process, the base material is in a fluidized motion state in a deposition area in the plasma enhanced chemical vapor deposition process, the plasma enhanced chemical vapor deposition process is performed in a fluidized plasma vapor deposition furnace, a positive plate and a negative plate are arranged in the fluidized plasma vapor deposition furnace, the deposition area is arranged between the positive plate and the negative plate, the negative plate has a vibration material conveying function, and the base material is in fluidized motion in the deposition area under the vibration action of the negative plate.
Furthermore, the number of the positive plates is more than 1, and each positive plate can be independently connected with working gas and a plasma generator; the vibration frequency and the vibration amplitude of the negative plate are respectively and independently adjustable.
Further, the base material is at least one of graphene, carbon nanosheets, carbon nanotubes, carbon fibers, artificial graphite, natural graphite, mesophase microspheres, soft carbon and hard carbon.
Furthermore, the nano silicon is granular and has the granularity of 1-200 nm.
In the deposition process, the carbon matrix material is used as a carrier, so that the deposited nano silicon and the substrate form a relatively fixed position relation, the dissociative nano silicon is eliminated, the technical problem of nano silicon agglomeration is thoroughly solved, the substrate is in a fluidized motion state in the deposition area, the nano silicon can be uniformly and stably distributed on the surface of the substrate, and the substrate is also favorable for absorbing the volume expansion of the nano silicon in the charging and discharging processes.
A preparation process of the silicon-carbon negative electrode material of the lithium ion battery comprises the following steps:
s1, placing a base material into a fluidized plasma vapor deposition furnace, and vacuumizing the deposition furnace;
s2, heating the deposition furnace, and making the base material perform fluidized motion in a deposition area under the vibration action of the negative plate;
s3, introducing diluent gas into the deposition furnace, switching on a plasma generator, then adding silicon source gas, and depositing nano silicon on the surface of the substrate to obtain a product A;
and S4, screening and filtering the product A to obtain a product A1, and coating the product A1 to obtain the lithium ion battery silicon-carbon cathode material.
Further, the coating treatment in the step S4 is liquid phase coating, and the lithium ion battery silicon carbon negative electrode material B1 is obtained by carbonizing, screening and filtering the liquid phase coated a 1.
Further, in the step S4, the coating treatment is to coat the surface with the nano-carbon in a gas phase, and the lithium ion battery silicon-carbon negative electrode material B2 is obtained after the a1 coated with the nano-carbon in the gas phase is sieved and filtered.
Further, the carbon source gas with the surface gas phase coated with the nano-carbon comprises at least one of methane, ethylene and acetylene.
Further, the nanocarbon in the surface vapor-phase-coated nanocarbon is in a granular shape and/or a film shape.
Further, the preparation process comprises the step of carrying out liquid phase coating treatment on the B2, and drying, carbonizing, screening and filtering the liquid phase coated B2 to obtain the lithium ion battery silicon carbon negative electrode material B3.
Further, the pressure in the fluidized plasma vapor deposition furnace is 0.01-2 torr in the step S1, and the temperature of the deposition furnace is 350-600 ℃ in the step S2.
Further, in the step S3, the volume ratio of the diluent gas to the silicon source gas is 0.2-6: 1, and the pressure in the fluidized plasma vapor deposition furnace is 2-10 torr.
Further, the silicon source gas in step S3 includes SiH4、SiHCl3、SiH2Cl2At least one of (1).
Further, the diluent gas comprises at least one of hydrogen, nitrogen, argon, helium.
Further, the plasma generator used by the fluidized plasma vapor deposition furnace comprises a capacitive radio frequency power supply with direct current bias, namely the direct current power supply is connected with a radio frequency power supply load capacitor in parallel, the negative electrode of the direct current power supply is in electric contact with a negative plate, and the negative plate is in contact with the substrate.
The silicon-carbon cathode material for lithium ion battery is prepared by mixing or blending the silicon-carbon cathode materials B1, B2 and B3 of lithium ion battery in any proportion.
The silicon-carbon cathode material for the lithium ion battery is formed by mixing or blending the silicon-carbon cathode materials B1, B2 and B3 of the lithium ion battery and the carbon cathode material of the lithium ion battery in any proportion.
The equipment is a fluidized plasma gas phase deposition furnace, a furnace body of the deposition furnace is provided with a feed inlet and a discharge outlet, positive plates and negative plates are arranged inside the furnace body, the number of the positive plates is more than 1, each positive plate can be independently connected with working gas and a plasma generator, the positive plates are arranged above the negative plates and keep a certain working distance with the negative plates, and a plasma gas phase deposition area is arranged between the positive plates and the negative plates; the feeding plate and the discharging plate are connected between the negative plate and the feeding hole and between the negative plate and the discharging hole respectively, the feeding plate, the discharging plate and the negative plate are connected with the vibrating device, the vibrating device has a vibrating material conveying function, an electric heating element is arranged below the negative plate, the substrate is discharged from the discharging hole after being deposited in the deposition furnace for a material conveying period, and the substrate is sent to the feeding hole again through a circulating mechanism outside the deposition furnace, so that the circulating flow of the substrate in a deposition area and the continuous deposition of the substrate by the deposition furnace are realized.
Compared with the prior art, the invention has the following beneficial effects:
in the invention, the base material moves in a fluidization manner in the deposition process, so that the nano silicon is uniformly distributed on the surface of the base material in the form of nano particles, and gaps are formed among the particles, thereby effectively inhibiting the deposited silicon from forming a film on the surface of the base material to block the contact of lithium ions and the base material; on the other hand, the deposited silicon is uniformly distributed on the surface of the base material in the form of nano particles, so that local over expansion of silicon element in the silicon-carbon negative electrode material in the lithium ion battery can be effectively inhibited, and the service life of the lithium ion battery is prolonged.
According to the invention, a plasma enhanced chemical vapor deposition process is adopted in the deposition process, so that the nano silicon and the substrate are firmly bonded together, and the nano silicon and the substrate form a relative position relationship, thereby limiting the dissociation of the nano silicon and solving the problem of agglomeration of the nano silicon due to the dissociation. The invention adopts surface deposition, the distribution area of the nano-silicon is wide, the reaction area with the electrolyte is large, the lithium ion battery has excellent rate performance, and the rapid charge and discharge performance and the cycle performance of the lithium ion battery are effectively improved on the premise of ensuring the high capacity and the high density of the lithium ion battery.
Drawings
FIG. 1 is a schematic structural view of a fluidized plasma vapor deposition furnace;
FIG. 2 is an electron microscope image of the morphological effect of fluidized plasma gas-phase deposition of nano-silicon;
FIG. 3 is a graph of the dispersion performance of fluidized plasma vapor deposition of nano-silicon;
wherein, 1 is a negative plate, 2 is a heating element, 3 is a positive plate, 4 is a furnace body, 4001 is a feeding hole, 4002 is a discharging hole.
Detailed Description
In order to facilitate understanding of the present invention, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following specific examples.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1
As shown in fig. 1, the present embodiment provides a fluidized plasma vapor deposition furnace, a furnace body 4 is provided with a feed inlet 4001 and a discharge outlet 4002, a positive plate 3 and a negative plate 1 are arranged inside the furnace body 4, the number of the positive plates 3 is more than 1, each positive plate can be independently connected with a working gas and a plasma generator, the positive plate 3 is arranged above the negative plate 1 and keeps a certain working distance with the negative plate 1, and a parallel space or an approximately parallel space between the positive plate 3 and the negative plate 1 is a plasma vapor deposition region. A feeding plate and a discharging plate are respectively connected between the negative plate 1 and the feeding hole 4001 and the discharging hole 4002, the feeding plate, the discharging plate and the negative plate 1 are connected with a vibrating device, the vibrating device has a vibrating material conveying function, and an electric heating element 2 is arranged below the negative plate 1. And a circulating mechanism is arranged outside the deposition furnace, the base material is discharged from a discharge hole 4002 after being deposited in the deposition furnace for a conveying period, and the base material is conveyed to a feeding hole 4001 again through the circulating mechanism, so that the circulating flow of the base material in a deposition area and the continuous deposition of the deposition furnace on the base material are realized.
In this embodiment, the plasma generator used in the deposition furnace is a capacitive radio frequency power supply with dc bias, i.e., the dc power supply is connected in parallel with a radio frequency power supply load capacitor, the positive electrode of the dc power supply is electrically connected to the positive plate 3, the negative electrode is electrically connected to the negative plate 1, and the negative plate 1 is in contact with the substrate. Under a plurality of positive plate modes, the negative plate that contacts with the substrate is public part, and independent plasma generator can be inserted alone to every positive plate, also can a plasma generator of a plurality of positive plates sharing, and independent work air supply can be inserted alone to every positive plate, also one set of work air supply of a plurality of positive plates sharing.
Specifically, the working process of the fluidized plasma vapor deposition furnace provided by the embodiment is as follows:
the base material enters the deposition furnace from a feed inlet 4001, is preheated by a feed plate and is conveyed to the position above a negative plate 1, the negative plate 1 enables the base material to reach a deposition area through vibration material conveying, and the base material is in a fluidized motion state in the deposition area under the vibration action of the negative plate 1; then, silicon source gas and diluent gas enter the deposition furnace from the positive plate 3, the silicon source gas is decomposed into silicon ions to collide with the surface of the base material at a high speed under the action of conditions such as a directional electric field, temperature, vacuum and the like, the process of vapor deposition of nano silicon on the surface of the base material is realized, the base material on the negative plate is always kept at a certain distance from the positive plate in the deposition process, and the base material is discharged from a discharge hole 4002 after the base material is deposited in a deposition area in a material conveying period; and a circulating mechanism is arranged outside the deposition furnace, the substrate is conveyed to the feeding hole 4001 again through the circulating mechanism, the circulating flow of the substrate in a deposition area and the continuous deposition of the substrate by the deposition furnace are realized, after the deposition of the substrate in the deposition furnace is finished, the circulating mechanism outside the deposition furnace is closed, and the substrate with the surface deposited with the nano silicon is discharged from the furnace through the discharging hole 4002.
The present embodiment has the advantages that the deposition furnace 4 is designed to be tunnel type, the areas of the negative plate 1 and the positive plate 3 are large, that is, the deposition area between the negative plate and the positive plate is large, so as to improve the deposition efficiency; or a plurality of positive plates 3 with smaller areas can be arranged above one negative plate 1 with larger area, so that multi-point simultaneous deposition is realized, and the deposition efficiency is improved.
Example 2
The embodiment provides a preparation process of a silicon-carbon cathode material of a lithium ion battery, wherein the weight of silicon accounts for about 3% of the total weight of the cathode material, and the preparation process is completed based on a fluidized plasma vapor deposition furnace in the embodiment 1, and the preparation process specifically comprises the following steps:
s1, placing 93kg of base material into a hopper at the upper end of a feeding hole 4001 of a fluidized plasma vapor deposition furnace, waiting for feeding, wherein the base material is artificial graphite particles, D50 is 15 microns, and vacuumizing the deposition furnace until the pressure in the furnace is 0.01-2 torr;
s2, electrifying an electric heating element, heating the deposition furnace to 500 ℃, enabling a feeding plate, a negative plate and a discharging plate to be in a vibration material conveying state, opening a feeding hole 4001 and a discharging hole 4002, sequentially conveying the base materials to the negative plate 1 in a flow-controllable mode, enabling the base materials to reach a deposition area below the positive plate 3, and enabling the base materials to be in a fluidized motion state in the deposition area under the vibration effect of the negative plate;
s3, introducing diluent gas hydrogen into the deposition furnace, switching on a plasma generator, and then adding silicon source gas silane SiH4Hydrogen flow 10L/min, SiH4Flow rate of (3) is 5L/min, hydrogen and SiH4The volume ratio of (A) is 2:1, the vacuum is kept in the range of 4-7 torr, the process of depositing the nano silicon on the surface of the base material is carried out, the total deposition time of introducing silane is 8 hours, and a product A-1 is obtained, wherein the silicon-carbon ratio in the product A-1 is 3:93, and the total weight is 96 kg;
s4, discharging the deposited product A-1 from a discharge port, screening and filtering the product A-1, removing lumps generated in the deposition process to obtain a product A1-1, coating the product A1-1 with a liquid phase, drying, carbonizing, screening and filtering after the coating is finished, and obtaining 100kg of the lithium ion battery silicon-carbon negative electrode material B1 with silicon content of about 3% and the total residual carbon content in the coating material of 4kg after the carbonization treatment.
This embodiment is at the deposition process, through the contained angle between adjustment feeding plate, negative plate 1, play flitch and the horizontal plane, and feeding plate, negative plate 1, play flitch vibration frequency and vibration amplitude can adjust substrate deposition time.
The nano silicon on the surface of the silicon-carbon cathode material substrate of the lithium ion battery prepared by the embodiment is granular, the granularity is 20-80nm, and the silicon-carbon ratio is 3: 97.
Example 3
The embodiment provides a preparation process of a silicon-carbon cathode material of a lithium ion battery, wherein the weight of silicon accounts for about 5% of the total weight of the cathode material, and the preparation process is completed based on a fluidized plasma vapor deposition furnace in the embodiment 1, and the preparation process specifically comprises the following steps:
s1, putting 90kg of base material into a hopper at the upper end of a feeding hole of a fluidized plasma vapor deposition furnace, waiting for feeding, vacuumizing the deposition furnace until the pressure in the furnace is 0.01-2 torr, wherein the base material is natural crystalline flake graphite particles and D50 is 11 microns;
s2, electrifying the electric heating element, heating the deposition furnace to 480 ℃, enabling the feeding plate, the negative plate and the discharging plate to be in a vibration material conveying state, opening the feeding plate and the discharging plate, conveying the base material to the negative plate 1 in a flow-controllable mode, enabling the base material to reach a deposition area below the positive plate 3, and enabling the base material to be in a fluidized motion state in the deposition area under the vibration action of the negative plate;
s3, introducing diluent gas hydrogen into the deposition furnace, switching on a plasma generator, and then adding silicon source gas silane SiH4Hydrogen flow 10L/min, SiH4Flow rate of 10L/min, hydrogen and SiH4The volume ratio of (A) is 1:1, the vacuum is kept within the range of 4-7 torr, the process of depositing the nano silicon on the surface of the substrate is carried out, the total deposition time of introducing silane is 7 hours, and a product A-2 is obtained, wherein the silicon-carbon ratio in the product A-2 is 5:90, and the total weight is 95 kg;
s4, discharging the deposited product A-2 from a discharge port, screening and filtering the product A-2, removing lumps generated in the deposition process to obtain a product A1-2, coating CVD gas phase on the surface of the product A1-2 with nano carbon, specifically, using methane as a carbon source gas, wherein the total carbon content in a coating material on the surface of A1-2 is 5kg, and screening and filtering the A1-2 coated with the nano carbon on the surface to obtain 100kg of a lithium ion battery silicon-carbon cathode material B2 with silicon content of about 5%.
The nano-silicon on the surface of the silicon-carbon negative electrode material B2 of the lithium ion battery prepared in the embodiment is granular, the granularity is 20-80nm, the nano-carbon in the nano-carbon coated by the surface gas phase is granular and film-shaped, and the ratio of silicon to carbon is 5: 95.
Example 4
In this embodiment, referring to example 3, a preparation process of a silicon-carbon negative electrode material for a lithium ion battery is provided, which includes, on the basis of the preparation process of example 3, performing an asphalt liquid phase coating treatment on B2, where a weight ratio of a total carbon amount in asphalt and a solvent to B2 is 3: 100, drying, carbonizing, screening and filtering the B2 coated with the asphalt liquid phase to obtain 103kg of lithium ion battery silicon-carbon negative electrode material B3.
In the embodiment, the liquid-phase-coated asphalt carbon is coated on the surface of the B2 in a film form, so that CVD (chemical vapor deposition) coating leak points can be repaired, the surface of a coating layer is compact, side reactions caused by contact of nano silicon and electrolyte can be effectively prevented, the service life of a battery can be prolonged, and the silicon-carbon ratio of the silicon-carbon cathode material B3 is 5: 98.
The lithium ion battery silicon-carbon negative electrode material prepared in the embodiment 2-4 is used as a working electrode, a lithium sheet is used as a counter electrode, 1mol/L LiPF6 and EC and DEC mixed solution with the volume ratio of 1:1 are used as electrolyte, a battery is assembled in an argon atmosphere glove box, and the battery is pressed, sealed and fully placed.
The electrochemical performance data obtained when the lithium ion battery silicon carbon negative electrode material prepared by the method is used for a lithium ion battery is shown in table 1.
TABLE 1
Figure BDA0002927679290000071
As can be seen from the table one, when the silicon carbon negative electrode material prepared by the technology of the present invention is used in a lithium ion battery, the first effect and the 50-cycle capacity retention rate are higher, and the silicon carbon negative electrode of example 4 after liquid phase coating is improved in the first effect and the 50-cycle capacity retention rate compared with the silicon carbon negative electrode material of example 3 without liquid phase coating.
The lithium ion battery silicon-carbon negative electrode materials B1, B2 and B3 prepared in the application can be mixed or blended at any proportion, and can also be mixed or blended with carbon negative electrode materials at any proportion to form various silicon-carbon negative electrode material products.
It should be understood that the above examples are only for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (18)

1. The silicon-carbon negative electrode material is characterized by comprising a base material and nano silicon deposited on the surface of the base material, wherein the base material is a carbon material, the nano silicon is deposited on the surface of the base material through a plasma enhanced chemical vapor deposition process, the base material is in a fluidized motion state in a deposition area in the plasma enhanced chemical vapor deposition process, the plasma enhanced chemical vapor deposition process is performed in a fluidized plasma vapor deposition furnace, a positive plate and a negative plate are arranged in the fluidized plasma vapor deposition furnace, the deposition area is arranged between the positive plate and the negative plate, the negative plate has a vibration material conveying function, and the base material is in fluidized motion in the deposition area under the vibration action of the negative plate.
2. The silicon-carbon negative electrode material of the lithium ion battery as claimed in claim 1, wherein the number of the positive plates is more than 1, and each positive plate can be independently connected with a working gas and a plasma generator; the vibration frequency and the vibration amplitude of the negative plate are respectively and independently adjustable.
3. The silicon-carbon anode material for the lithium ion battery according to claim 1, wherein the substrate is at least one of graphene, carbon nanosheets, carbon fibers, carbon nanotubes, artificial graphite, natural graphite, mesophase microspheres, soft carbon and hard carbon.
4. The silicon-carbon anode material for the lithium ion battery according to claim 1, wherein the nano silicon is granular and has a particle size of 1-200 nm.
5. The preparation process of the silicon-carbon anode material of the lithium ion battery as claimed in any one of claims 1 to 4, characterized by comprising the following steps:
s1, placing a base material into a fluidized plasma vapor deposition furnace, and vacuumizing the deposition furnace;
s2, heating the deposition furnace, and making the base material perform fluidized motion in a deposition area under the vibration action of the negative plate;
s3, introducing diluent gas into the deposition furnace, switching on a plasma generator, then adding silicon source gas, and depositing nano silicon on the surface of the substrate to obtain a product A;
and S4, screening and filtering the product A to obtain a product A1, and coating the product A1 to obtain the lithium ion battery silicon-carbon cathode material.
6. The preparation process of claim 5, wherein the coating treatment in the step S4 is liquid phase coating, and the liquid phase coated A1 is carbonized, sieved and filtered to obtain the lithium ion battery silicon carbon negative electrode material B1.
7. The preparation process of claim 5, wherein the coating treatment in step S4 is to coat the surface with the nanocarbon in a vapor phase, and the A1 coated with the nanocarbon in the vapor phase is sieved and filtered to obtain the silicon-carbon negative electrode material B2 of the lithium ion battery.
8. The preparation process according to claim 7, wherein the carbon source gas with the surface coated with the nanocarbon in the gas phase comprises at least one of methane, ethylene and acetylene.
9. The production process according to claim 7, wherein the nanocarbon in the surface vapor-coated nanocarbon is in a granular form and/or a film form.
10. The preparation process of claim 7, further comprising performing liquid phase coating treatment on the B2, and drying, carbonizing, screening and filtering the liquid phase coated B2 to obtain the lithium ion battery silicon carbon negative electrode material B3.
11. The process according to claim 5, wherein the pressure in the fluidized plasma vapor deposition furnace in step S1 is 0.01 to 2 Torr, and the temperature in the deposition furnace in step S2 is 350 to 600 ℃.
12. The process according to claim 5, wherein the volume ratio of the diluent gas to the silicon source gas in step S3 is 0.2-6: 1, and the pressure in the fluidized plasma vapor deposition furnace is 2-10 Torr.
13. The process of claim 5, wherein the silicon source gas in step S3 comprises SiH4、SiHCl3、SiH2Cl2At least one of (1).
14. The process of claim 5, wherein the diluent gas in step S3 comprises at least one of hydrogen, nitrogen, argon, and helium.
15. The process of claim 5, wherein the plasma generator of the fluidized plasma vapor deposition furnace comprises a capacitive RF power source with DC bias, i.e., a DC power source is connected in parallel with a RF power source load capacitor, the negative pole of the DC power source is electrically connected with a negative plate, and the negative plate is in contact with the substrate.
16. The silicon-carbon cathode material for the lithium ion battery is characterized by being formed by mixing or blending B1, B2 and B3 which are silicon-carbon cathode materials for the lithium ion battery in any proportion.
17. The lithium ion battery silicon-carbon negative electrode material is characterized by being formed by mixing or blending lithium ion battery silicon-carbon negative electrode materials B1, B2 and B3 and lithium ion battery carbon negative electrode materials in any proportion.
18. The equipment is characterized in that the equipment is a fluidized plasma gas phase deposition furnace, a feed inlet and a discharge outlet are arranged on a furnace body of the deposition furnace, positive plates and negative plates are arranged inside the furnace body, the number of the positive plates is more than 1, each positive plate can be independently connected with working gas and a plasma generator, the positive plates are arranged above the negative plates and keep a certain working distance with the negative plates, and a plasma gas phase deposition area is arranged between the positive plates and the negative plates; the feeding plate and the discharging plate are connected between the negative plate and the feeding hole and between the negative plate and the discharging hole respectively, the vibrating device is connected on the feeding plate, the discharging plate and the negative plate, the vibrating device has a vibrating material conveying function, an electric heating element is arranged below the negative plate, the substrate is discharged from the discharging hole after being deposited in the deposition furnace for a material conveying period, and the substrate is sent to the feeding hole again through a circulating mechanism outside the deposition furnace, so that the circulating flow of the substrate in a deposition area and the continuous deposition of the deposition furnace on the substrate are realized.
CN202110137754.1A 2021-02-01 2021-02-01 Lithium ion battery silicon-carbon negative electrode material and preparation process and equipment thereof Withdrawn CN112768668A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023093448A1 (en) * 2021-11-25 2023-06-01 湖南中科星城石墨有限公司 Silicon-carbon negative electrode material of lithium-ion battery, preparation method therefor and application thereof
CN116995219A (en) * 2023-09-18 2023-11-03 昆明理工大学 Porous silicon-carbon composite anode material and preparation method and application thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023093448A1 (en) * 2021-11-25 2023-06-01 湖南中科星城石墨有限公司 Silicon-carbon negative electrode material of lithium-ion battery, preparation method therefor and application thereof
CN116995219A (en) * 2023-09-18 2023-11-03 昆明理工大学 Porous silicon-carbon composite anode material and preparation method and application thereof

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