WO2015032294A1 - Method for preparing electrode active material of lithium-ion battery - Google Patents

Method for preparing electrode active material of lithium-ion battery Download PDF

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WO2015032294A1
WO2015032294A1 PCT/CN2014/085609 CN2014085609W WO2015032294A1 WO 2015032294 A1 WO2015032294 A1 WO 2015032294A1 CN 2014085609 W CN2014085609 W CN 2014085609W WO 2015032294 A1 WO2015032294 A1 WO 2015032294A1
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particles
lithium
active material
electrode active
lithium titanate
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PCT/CN2014/085609
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French (fr)
Chinese (zh)
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付安安
高剑
李建军
王莉
何向明
尚玉明
王要武
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江苏华东锂电技术研究院有限公司
清华大学
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Publication of WO2015032294A1 publication Critical patent/WO2015032294A1/en

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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
    • H01M4/366—Composites as layered products
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/003—Titanates
    • C01G23/005—Alkali titanates
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/30—Three-dimensional structures
    • C01P2002/32—Three-dimensional structures spinel-type (AB2O4)
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • 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

Definitions

  • the invention relates to a preparation method of an electrode active material for a lithium ion battery, in particular to a method for preparing a lithium titanate electrode active material.
  • spinel lithium titanate (Li 4 Ti 5 O 12 ) has received increasing attention as an electrode active material for new energy storage batteries because spinel lithium titanate is involved in lithium ion intercalation-deintercalation.
  • the crystal structure can maintain a high degree of stability.
  • the lithium ion is a spinel structure before and after embedding, and the lattice constant changes little, and the volume change is small. Therefore, lithium titanate is called a "zero strain" electrode active material.
  • the titanic acid Lithium has excellent cycle properties.
  • the lithium titanate active material is a semiconductor material, and its electronic conductivity is low. When charging and discharging at a large rate, the capacity is seriously attenuated, so improving the conductivity of the material is still a hot research topic.
  • the methods for preparing spinel lithium titanate mainly include a sol-gel method and a solid phase synthesis method.
  • the sol-gel method can realize the atomic-level mixing of the raw material for synthesizing lithium titanate, and prepare the nano-titanium titanate with good conductivity, but the raw material cost is high, the organic reagent is consumed too much, and the operability is poor.
  • the solid phase synthesis method is simple in process and low in cost, and is suitable for large-scale production, but the lithium titanate particles synthesized by the solid phase method are easy to agglomerate and have non-uniform size, and the activity is not high, thereby causing electrochemical performance of the lithium titanate material. not tall.
  • a method for preparing a lithium ion battery electrode active material comprising the steps of: providing a lithium source and titanium dioxide, mixing a lithium source and titanium dioxide to form a mixture, and grinding the mixture for the first time to obtain precursor particles;
  • the precursor particles are calcined at 500 ° C to 600 ° C to obtain a first intermediate;
  • the plurality of first intermediates are subjected to a second grinding, and the second sintering is performed at 800 ° C to 1000 ° C to obtain the first a second intermediate; and subjecting the second intermediate to a third grinding and performing a third sintering at 500 ° C to 700 ° C to obtain spinel lithium titanate particles.
  • the present invention adopts a method of combining multiple grinding and multiple sintering to prepare lithium titanate particles, especially the third grinding of the second intermediate particles before the third sintering, which can be controlled by
  • the conditions of the grinding make the particle size of the second intermediate particles smaller and make the distribution more uniform, so that the lithium titanate crystal having a regular morphology, a small particle size and a uniform distribution is obtained after the third sintering.
  • the second intermediate particles are subjected to a third grinding to further refine the second intermediate particles, so that the second intermediate particles can be sufficiently contacted with oxygen during the third sintering process to compensate for the second sintering process.
  • the lithium niobate crystal oxygen deficiency formed by the higher sintering temperature finally obtains the surface carbon package with regular morphology, small particle size and uniform distribution, high tap density, less lattice defects, high capacity and good cycle performance.
  • Lithium titanate electrode active material Lithium titanate electrode active material.
  • FIG. 1 is a flow chart showing the preparation of an electrode active material for a lithium ion battery according to a first embodiment of the present invention.
  • Example 2 is an XRD test chart of lithium titanate particles prepared in Example 1 of the present invention.
  • Figure 3 is a scanning electron micrograph of lithium titanate particles prepared in Example 1 of the present invention.
  • Fig. 5 is a graph showing the specific capacity test of the first charge and discharge of the battery using the lithium titanate electrode active material prepared in Example 1 of the present invention as a negative electrode at different magnifications.
  • Fig. 6 is a graph showing the cycle performance test of a battery using a lithium titanate electrode active material prepared in Example 1 of the present invention as a negative electrode at different magnifications.
  • Figure 7 is a transmission electron micrograph of carbon-coated lithium titanate particles prepared in Example 1 of the present invention.
  • Figure 8 is a transmission electron micrograph of carbon-coated lithium titanate particles prepared in Example 2 of the present invention.
  • a first embodiment of the present invention provides a method for preparing a lithium ion battery electrode active material, which comprises the following steps:
  • the precursor particles are calcined at 500 ° C to 600 ° C to obtain a plurality of first intermediate particles
  • the plurality of second intermediate particles are subjected to a third grinding, and the third sintering is performed at 500 ° C to 700 ° C to obtain a plurality of spinel lithium titanate particles.
  • the lithium source may be a lithium salt, lithium hydroxide (LiOH) or a mixture of a lithium salt and lithium hydroxide.
  • the lithium salt may be one or more selected from lithium salts commonly used for preparing lithium ion battery electrode active materials, such as lithium carbonate, lithium sulfate, lithium nitrate, lithium chloride, and lithium oxalate, and is not limited to the listed ones.
  • the lithium source is one or more of lithium carbonate, lithium chloride and lithium hydroxide.
  • the lithium source can be in the form of a powder or granules, preferably a nano-sized powder or granule.
  • the titanium dioxide may be a mixture of one or both of rutile type titanium dioxide and anatase type titanium dioxide, preferably anatase type titanium dioxide.
  • the titanium dioxide may be in the form of a powder or granules, preferably a nano-sized powder or granule, preferably having a particle size ranging from 10 nm to 20 nm.
  • the molar ratio of Li:Ti 0.81:1 to 1:1 in the lithium source and titanium dioxide, preferably, the molar ratio may be 0.81:1 to 0.85:1.
  • the purpose of the first grinding is to refine the lithium source particles and the titanium dioxide particles, so that the mixing of the lithium source and the titanium dioxide is more uniform, and it is advantageous to form a product having a regular morphology and a uniform phase.
  • the first grinding further comprises adding a dispersing agent to the mixture for grinding to obtain a mixture slurry.
  • a dispersant for grinding can make the dispersion of the precursor particles better and make the grinding more uniform.
  • the dispersing agent in the mixture slurry only covers the surface of the mixture.
  • the dispersing agent may be one or more of water, ethanol, and acetone.
  • the mass ratio of the dispersant to the precursor particles may range from 2:1 to 1.5:1.
  • the mixture slurry can also be ultrasonically dispersed, dried and sieved, and ultrasonic dispersion can reduce the agglomeration of the precursor particles in the mixture slurry, and the sieve can sieve the larger particle size precursor particles.
  • the ultrasonic dispersion may be carried out for a period of from 0.5 hours to 3 hours.
  • the drying may be naturally air dried, oven dried, vacuum dried or spray dried, preferably vacuum dried.
  • the screen mesh used for the screening may range from 400 mesh to 500 mesh.
  • the grinding can be any manner of grinding, preferably ball milling.
  • the ball mill can have a rotational speed ranging from 450 r/min to 500 r/min and a ball milling time of from 3 hours to 4 hours.
  • the lithium source and the titanium oxide may be initially subjected to a preliminary reaction at a relatively low temperature to avoid a large amount of volatilization of the lithium source at a high temperature.
  • the calcination temperature may range from 500 ° C to 600 ° C, preferably from 500 ° C to 550 ° C, and the calcination temperature of the examples of the present invention is 500 ° C.
  • the pre-firing heating method may directly raise the precursor particles after being placed in the reaction furnace, and the heating rate may range from 5 ° C/min to 10 ° C/min.
  • the calcination time varies depending on the calcination temperature.
  • the calcination time may be from 4 hours to 10 hours, preferably from 6 hours to 8 hours, and the calcination time of the embodiment of the present invention is 6 hours.
  • the calcination can be carried out under normal pressure.
  • the pre-burning atmosphere may be an oxygen-containing atmosphere, preferably an air atmosphere.
  • the above step S2 further includes a step of cooling the first intermediate particles.
  • the cooling may be directly cooled in the reaction furnace or may be taken out from the reaction furnace and naturally cooled in the air.
  • the first intermediate particles can be cooled to room temperature.
  • the purpose of the second grinding is to refine the first intermediate particles agglomerated together during the calcination process, thereby increasing the reactivity of the first intermediate particles, thereby reducing the second The temperature of the secondary sintering and the time to shorten the second sintering.
  • the second grinding further comprises adding a dispersant to the first intermediate particles for milling to obtain a first intermediate slurry.
  • the addition of a dispersant for grinding can make the dispersion of the first intermediate particles better and make the grinding more uniform.
  • the dispersing agent in the mixed slurry only covers the surface of the mixture.
  • the dispersing agent may be one or more of water, ethanol, and acetone.
  • the mass ratio of the dispersant to the first intermediate particles is in the range of 2:1 to 1.5:1.
  • the first intermediate slurry may be ultrasonically dispersed, dried and sieved, and the ultrasonic dispersion may reduce the agglomeration of the first intermediate particles in the first intermediate slurry, and the sieve may have a larger particle size.
  • An intermediate particle is screened.
  • the time for the ultrasonic dispersion may be from 0.5 to 3 hours.
  • the drying can be naturally air dried, oven dried, vacuum dried or spray dried, preferably vacuum dried.
  • the screen mesh used for the screening may range from 400 mesh to 500 mesh.
  • the grinding can be any manner of grinding, preferably ball milling.
  • the ball mill can have a rotational speed ranging from 450 r/min to 500 r/min and a ball milling time of from 3 hours to 4 hours.
  • the temperature of the second sintering may range from 800 ° C to 1000 ° C, preferably from 800 ° C to 900 ° C, and the second sintering temperature of the embodiment of the present invention is 800 ° C.
  • the heating method of the second sintering may be performed after the first intermediate particles are placed in the reaction furnace and the temperature is raised to a predetermined temperature at a constant speed, and the heating rate may range from 5 ° C/min to 10 ° C/min.
  • the time of the second sintering varies depending on the sintering temperature.
  • the second sintering time may be from 10 hours to 18 hours, preferably from 10 hours to 14 hours, and the second sintering time of the embodiment of the present invention is 12 hours.
  • the second sintering can be carried out under normal pressure.
  • the atmosphere of the second sintering may be an oxygen-containing atmosphere, preferably an air atmosphere.
  • the above step S3 further includes a step of cooling the second intermediate particles.
  • the cooling may be directly cooled in the reaction furnace or may be taken out from the reaction furnace and naturally cooled in the air.
  • the second intermediate particles can be cooled to room temperature.
  • the third grinding may further refine the second intermediate particles agglomerated together in the second sintering process.
  • the smaller particle size electrode active material can provide a shorter lithium ion diffusion path and a larger contact area between the electrolyte and the two phases of the electrode, which is favorable for the electrochemical reaction, and has a good morphology and uniform particle size distribution.
  • Spherical materials have higher tap density and better flow. Due to the higher temperature of the second sintering, the particles tend to agglomerate during the sintering process, resulting in a larger particle size, an irregular morphology and a very uneven particle size distribution.
  • the second intermediate particles are subjected to the third grinding, and the second intermediate particles can be made smaller in particle size and more uniformly distributed by controlling the grinding conditions, so that the morphology and particle size are obtained after the third sintering. Smaller and uniformly distributed lithium titanate crystals.
  • the second sintering process since the agglomerated particles are not in sufficient contact with oxygen, and the high sintering temperature is liable to cause decomposition of the generated second intermediate particles, the finally obtained second intermediate particles are present. More oxygen defects, the loss of oxygen in the lithium titanate crystal structure will reduce the cycle performance of lithium titanate.
  • the second intermediate particles are subjected to a third grinding to further refine the second intermediate particles, so that the second intermediate particles can be sufficiently contacted with oxygen during the third sintering process, thereby avoiding the prior art solid
  • the second intermediate particles obtained after the third grinding may have a particle diameter ranging from 300 nm to 400 nm.
  • the third grinding further comprises adding a dispersant to the second intermediate particles for milling to obtain a second intermediate slurry.
  • a dispersing agent for grinding can make the dispersion of the second intermediate particles better and make the grinding more uniform.
  • the dispersing agent in the mixed slurry only covers the surface of the mixture.
  • the dispersing agent may be one or more of water, ethanol, and acetone.
  • the dispersant second intermediate particle mass ratio may range from 2:1 to 1.5:1.
  • the second intermediate slurry may be ultrasonically dispersed, dried and sieved, and the ultrasonic dispersion may reduce the agglomeration of the second intermediate particles in the second intermediate slurry, and the sieve may have a larger particle size.
  • the second intermediate particles are sieved.
  • the ultrasonic dispersion may be carried out for a period of from 0.5 hours to 3 hours.
  • the drying can be naturally air dried, oven dried, vacuum dried or spray dried, preferably vacuum dried.
  • the screen mesh used for the screening may range from 400 mesh to 500 mesh.
  • the grinding can be any manner of grinding, preferably ball milling.
  • the ball mill can have a rotational speed ranging from 450 rmp to 500 rpm and a ball milling time of from 3 hours to 4 hours.
  • the purpose of the third sintering is to compensate for the oxygen deficiency of the lithium titanate crystal structure formed by the agglomeration of the particles during the second sintering.
  • the temperature of the third sintering may not be too high, and the excessive temperature is unfavorable for forming a crystal structure of lithium titanate having less oxygen defects, and the particles are easily agglomerated during sintering.
  • the temperature of the third sintering may range from 500 ° C to 700 ° C, preferably from 600 ° C to 700 ° C. More preferably, the temperature of the third sintering is higher than the temperature of the calcination.
  • the third sintering temperature used in the examples of the present invention was 700 °C.
  • the temperature rising method of the third sintering may be performed after the precursor particles are placed in the reaction furnace and the temperature is raised at a uniform rate, and the temperature rising rate may range from 5 ° C/min to 10 ° C/min.
  • the time of the third sintering differs depending on the third sintering temperature. Generally, the third sintering time may be from 2 hours to 8 hours, preferably from 3 hours to 5 hours, and the third sintering time employed in the examples of the present invention is 4 hours.
  • the third sintering can be carried out under normal pressure.
  • the atmosphere for the third sintering may be an oxygen-containing atmosphere, preferably an air atmosphere.
  • the above step S4 further includes a step of introducing an oxygen-containing atmosphere during the third sintering.
  • This step enables the particles to be sufficiently contacted with oxygen during the third sintering process, so that the finally obtained lithium titanate crystal has less oxygen defects, enables lithium titanate to have better cycle performance, and is introduced at a constant flow rate.
  • the oxygen atmosphere also acts to prevent particle agglomeration.
  • the oxygen-containing atmosphere may be introduced at a flow rate of 40 ml/min to 60 ml/min during the third sintering.
  • the lithium titanate electrode active material obtained by the production method of the present invention is a spherical particle.
  • the spherical particles have a regular morphology, a small particle size and a uniform distribution.
  • the spherical particles have a particle size ranging from 300 nm to 400 nm.
  • a second embodiment of the present invention provides a method for preparing a lithium ion battery electrode active material, which comprises the following steps:
  • the precursor particles are calcined at 500 ° C to 600 ° C to obtain a plurality of first intermediate particles
  • the plurality of second intermediate particles are subjected to a third grinding, and the third sintering is performed at 500 ° C to 700 ° C to obtain a plurality of spinel lithium titanate particles.
  • the method for preparing the lithium ion battery electrode active material provided by the embodiment of the present invention is substantially similar to the steps and principles of the method for preparing the lithium ion battery electrode active material provided by the first embodiment of the present invention.
  • steps S1 to S4 lithium titanate particles having a regular morphology, a small particle size and uniform distribution, a high tap density, a small lattice defect, and a high capacity can be obtained.
  • Surface carbon coating of the lithium titanate particles can further improve the conductivity of the lithium titanate electrode active material, thereby obtaining regular morphology, small and uniform particle size, high tap density, and low lattice defects. A higher capacity surface carbon coated lithium titanate electrode active material.
  • the method of surface carbon coating may include a solid phase method and a liquid phase method.
  • the solid phase method can mix and grind lithium titanate particles with solid carbon source particles and then perform high temperature treatment under inert gas protection. During high temperature treatment, the carbon source is decomposed and carbon coated on the surface of the lithium titanate particles. Floor.
  • the liquid phase method includes a dipping method and an in-situ polymerization method.
  • the dipping method may dissolve a carbon source in a solvent, and then add lithium titanate particles under stirring to obtain lithium titanate particles coated with a carbon source material; dry with natural air, oven, vacuum dry or spray. Drying and other drying methods: evaporating the solvent; the lithium titanate particles coated with the carbon source material are treated under high temperature under high temperature treatment, and the carbon source coated on the surface of the lithium titanate particles is decomposed and titanium in the high temperature treatment process. A surface of the lithium acid particles forms a carbon coating layer.
  • the in-situ polymerization method can place lithium titanate particles in an organic polymer monomer solution, and initiate polymerization of the organic polymer monomer on the surface of the lithium titanate particles under stirring to form a surface-coated organic polymer.
  • Lithium titanate particles; the lithium titanate particles coated with the organic polymer are subjected to high temperature treatment under the protection of an inert gas, and the organic polymer on the surface of the lithium titanate particles is decomposed and on the surface of the lithium titanate particles during the high temperature treatment.
  • a carbon coating layer is formed.
  • the present invention uses in situ polymerization to prepare carbon coated lithium titanate particles, the specific steps are:
  • the organic monomer is one or more of a conjugated diene, a vinyl monomer, and a functional monomer.
  • the conjugated diene is selected from the group consisting of 1,3-butadiene, 2-methyl-1,3 butadiene, 2,3-dimethyl-1,3-butadiene, and isoprene.
  • One or more of the vinyl monomers are one or more selected from the group consisting of ethylene, propylene, isobutylene, acrylonitrile, styrene, and methyl styrene.
  • the functional monomer is one selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylamide, and methacrylamide.
  • the solvent can dissolve the organic monomer and the initiator.
  • the solvent is preferably an organic solvent.
  • the organic solvent is one or more of an alkane, an alcohol, an ether, a ketone, an aromatic hydrocarbon, a halogenated hydrocarbon, a heterocyclic compound, a nitrogen-containing compound, and a sulfur-containing compound.
  • Preferred are one or more of toluene, cyclohexane, dichloromethane, ethanol, petroleum ether, propylene oxide, trichloroethylene, dimethyl sulfoxide, and nitrogen nitroformamide.
  • the initiator is used to initiate polymerization between the organic polymer monomers, and may be one or more of an organic peroxide initiator, an inorganic peroxide initiator, an azo initiator, and a redox initiator.
  • the organic peroxide initiator may be one or more selected from the group consisting of benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, t-butyl peroxyacetate, and cumene peroxide.
  • the inorganic peroxide initiator may be one or more selected from the group consisting of potassium persulfate, sodium persulfate, and ammonium persulfate.
  • the azo initiator may be one or more selected from the group consisting of azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate.
  • the redox initiator may be selected from the group consisting of benzoyl peroxide/sucrose, t-butyl hydroperoxide/carved white block, t-butyl hydroperoxide/sodium metabisulfite, and benzoyl peroxide/N,N-dimethyl One or more of the anilines.
  • the method of uniformly dispersing the organic polymer precursor solution on the surface of the lithium titanate particles may be stirring or ultrasonic dispersion.
  • the initiator when the organic polymer precursor solution is heated to a certain temperature under stirring, the initiator is thermally decomposed into a radical, and the organic monomer is polymerized to finally form a surface-coated organic polymerization.
  • the heating temperature may be from 50 ° C to 150 ° C.
  • the specific heating temperature is determined according to the nature of the organic monomer and the decomposition temperature of the initiator. For example, when styrene is used as the monomer or benzoyl peroxide is used as the initiator, the polymerization temperature may be 80 °C. When acrylonitrile is used as the monomer and azobisisobutyronitrile is used as the initiator, the polymerization temperature can be 70 °C.
  • the separation method may be filtration or suction filtration.
  • the step (3) further includes a step of purifying the lithium titanate particles coated with the surface-coated organic polymer.
  • the purification method may be washing the surface-coated organic polymer lithium titanate particles with a volatile organic solvent.
  • the volatile organic solvent may be one or more of methanol, ethanol, dichloromethane, n-heptane, and toluene.
  • the drying method may be natural air drying, oven drying, vacuum drying or spray drying, preferably vacuum drying.
  • the drying temperature needs to be lower than 200 °C.
  • the inert gas may be one or more of nitrogen, helium, neon, argon, helium, and neon.
  • the formed carbon coating layer is uniformly continuous.
  • each of said lithium titanate particles is coated with a uniform continuous carbon layer.
  • the carbon coating layer may have a thickness ranging from 3 nm to 8 nm.
  • the surface carbon-coated lithium titanate electrode active material has a particle diameter ranging from 400 nm to 500 nm.
  • the surface carbon-coated lithium titanate electrode active material is obtained by the preparation method of the present invention as spherical particles.
  • the spherical particles have a regular morphology, a small particle size and a uniform distribution, and a uniform carbon coating on the surface.
  • This Comparative Example 1 is substantially the same as the above-described Embodiment 1, except that the precursor particles are not subjected to the second grinding and the third grinding in the subsequent sintering process, and the second sintering and the third sintering are directly performed.
  • FIG. 2 and FIG. 3 are respectively an XRD test chart and a scanning electron micrograph of the lithium titanate particles prepared in Example 1 of the present invention.
  • 4 is a scanning electron micrograph of lithium titanate particles prepared in Comparative Example 1.
  • the lithium titanate particles prepared by the method of the present invention have no impurity phase, no impurity peak, and good crystallinity.
  • the lithium titanate particles prepared by the method of the present invention have a particle diameter of less than 500 nm, a small particle diameter and a uniform particle size distribution, and the lithium titanate particles prepared in the comparative example 1 have a particle diameter of more than 1 um.
  • the particle size distribution is uneven and there is a significant agglomeration.
  • FIG. 5 is a graph showing the specific capacity test of the first charge and discharge of the battery using the lithium titanate electrode active material prepared in Example 1 of the present invention as the negative electrode active material at different magnifications
  • the ratio of the battery at a ratio of 0.1 C, 1 C, and 5 C is used.
  • the average capacity is 158mAh/g, 150 mAh/g and 92mAh/g, which has better rate performance. It can be seen from Fig.
  • the battery under the conditions of 0.1C, 1C and 5C, respectively, with the increase of the number of cycles, the battery The specific capacity decline is small. It can be seen from Table 1 that the battery has a high first efficiency under the conditions of 0.1 C, 1 C, and 5 C, respectively. It is shown that the lithium titanate electrode active material prepared in Example 1 has high first efficiency, good cycle performance, and capacity retention even at a high rate.
  • FIG. 7 and FIG. 8 are transmission electron micrographs of carbon-coated lithium titanate particles prepared in Example 2 and Example 3, respectively.
  • Table 2 is a comparison table of electrochemical cycle performance of the carbon-coated lithium titanate particles prepared in Examples 2 and 3 and the carbon-coated lithium titanate particles prepared in Example 1. It can be seen from Fig. 7 and Fig. 8 that the thickness of the carbon-coated lithium titanate particles is about 5 nm, and the thickness is relatively uniform. It can be seen from Table 1 that the carbon-coated lithium titanate particles have better electrochemical performance than the uncoated carbon lithium titanate, indicating that the lithium titanate having a uniform carbon coating layer can be obtained by the carbon coating method of the present invention. The particles and the conductivity of the lithium titanate material can be further improved, and the finally obtained carbon-coated lithium titanate electrode material has high tap density, good fluidity and workability.
  • Example 1 LTO 158mAh/g 92mAh/g 97.7%
  • Example 2 Carbon coated LTO 162mAh/g 98mAh/g 99.2%
  • Example 3 Carbon coated LTO 164mAh/g 102mAh/g 98.9%
  • the invention adopts a method of combining multiple grinding and multiple sintering to prepare lithium titanate particles, and surface carbon coating of the lithium titanate particles, preparing a regular shape, a small particle size and uniform distribution, and tapping.
  • a lithium titanate electrode active material having a high density, a small lattice defect, and a uniform carbon coating layer and a high capacity.

Abstract

A method for preparing an electrode active material of a lithium-ion battery. The method comprises the following steps: providing a lithium source and titanium oxide, and mixing the lithium source and titanium oxide into a mixture, performing first grinding on the mixture, so as to obtain multiple precursor particles; performing pre-sintering on the precursor particles at a temperature of 500 to 600 degrees centigrade, so as to obtain multiple first intermediate particles; performing second grinding on the multiple first intermediate particles, and performing second sintering at a temperature of 800 to 1000 degrees centigrade, so as to obtain multiple second intermediate particles; and performing third grinding on the multiple second intermediate particles, and performing third sintering at a temperature of 500 to 700 degrees centigrade, so as to obtain spinel lithium titanate particles.

Description

锂离子电池电极活性材料的制备方法Method for preparing lithium ion battery electrode active material 技术领域Technical field
本发明涉及一种锂离子电池电极活性材料的制备方法，尤其涉及一种钛酸锂电极活性材料的制备方法。The invention relates to a preparation method of an electrode active material for a lithium ion battery, in particular to a method for preparing a lithium titanate electrode active material.
背景技术Background technique
近年来，尖晶石型钛酸锂（Li4Ti5O12）作为新型储能电池的电极活性材料日益受到重视，这是因为尖晶石型钛酸锂在锂离子嵌入-脱嵌过程中晶体结构能够保持高度的稳定性，锂离子嵌入前后都为尖晶石结构，且晶格常数变化很小，同时体积变化很小，所以钛酸锂被称为“零应变”电极活性材料。这能够避免充放电循环中，由于电极活性材料的来回伸缩而导致结构的破坏，从而提高电极的循环性能和使用寿命，减少了随循环次数的增加而带来比容量幅度的衰减，使钛酸锂具有优异的循环性能。然而钛酸锂活性材料是一种半导体材料，其电子电导率较低，在大倍率充放电时，容量衰减严重，因此提高材料的导电性仍是目前研究的热点。In recent years, spinel lithium titanate (Li 4 Ti 5 O 12 ) has received increasing attention as an electrode active material for new energy storage batteries because spinel lithium titanate is involved in lithium ion intercalation-deintercalation. The crystal structure can maintain a high degree of stability. The lithium ion is a spinel structure before and after embedding, and the lattice constant changes little, and the volume change is small. Therefore, lithium titanate is called a "zero strain" electrode active material. This can avoid the destruction of the structure due to the back and forth expansion of the electrode active material in the charge and discharge cycle, thereby improving the cycle performance and the service life of the electrode, and reducing the attenuation of the specific capacity amplitude as the number of cycles increases, so that the titanic acid Lithium has excellent cycle properties. However, the lithium titanate active material is a semiconductor material, and its electronic conductivity is low. When charging and discharging at a large rate, the capacity is seriously attenuated, so improving the conductivity of the material is still a hot research topic.
制备纳米钛酸锂、细化钛酸锂晶粒是提高钛酸锂材料导电性的方法之一，因为较小颗粒尺寸的电极活性材料能够提供较短的锂离子扩散路径以及较大的电解质与电极两相之间的接触面积，有利于电化学反应的进行。目前制备尖晶石钛酸锂的方法主要有溶胶凝胶法和固相合成法。其中，溶胶凝胶法可以使合成钛酸锂的原料实现原子级的混合，制备出导电性较好的纳米钛酸锂，但由于原料成本高、消耗过多有机试剂、可操作性不佳等问题使这种方法难以用于工业化生产。而固相合成法的工艺简单、成本较低，适合大规模生产，但是固相法合成的钛酸锂颗粒易团聚且尺寸不均一，且活性不高，从而导致钛酸锂材料的电化学性能不高。Preparation of lithium nanotitanate and refinement of lithium titanate crystallites is one of the methods to improve the conductivity of lithium titanate materials, because electrode active materials with smaller particle sizes can provide shorter lithium ion diffusion paths and larger electrolytes. The contact area between the two phases of the electrode facilitates the progress of the electrochemical reaction. At present, the methods for preparing spinel lithium titanate mainly include a sol-gel method and a solid phase synthesis method. Among them, the sol-gel method can realize the atomic-level mixing of the raw material for synthesizing lithium titanate, and prepare the nano-titanium titanate with good conductivity, but the raw material cost is high, the organic reagent is consumed too much, and the operability is poor. The problem makes this method difficult to use in industrial production. The solid phase synthesis method is simple in process and low in cost, and is suitable for large-scale production, but the lithium titanate particles synthesized by the solid phase method are easy to agglomerate and have non-uniform size, and the activity is not high, thereby causing electrochemical performance of the lithium titanate material. not tall.
发明内容Summary of the invention
有鉴于此，确有必要提供一种锂离子电池电极活性材料的制备方法，通过该制备方法可获得具有规则形貌、粒径较小且均匀分布、振实密度高、晶格缺陷少且容量较高的钛酸锂电极活性材料。In view of this, it is indeed necessary to provide a method for preparing an active material of a lithium ion battery, by which a regular morphology, a small particle size and a uniform distribution, a high tap density, a small lattice defect, and a capacity can be obtained. Higher lithium titanate electrode active material.
一种锂离子电池电极活性材料的制备方法，其包括以下步骤：提供锂源和二氧化钛，将锂源和二氧化钛混合形成一混合物，并对该混合物进行第一次研磨，获得前驱体颗粒；将所述前驱体颗粒在500℃至600℃进行预烧，获得第一中间体；将所述多个第一中间体进行第二次研磨，并在800℃至1000℃进行第二次烧结，获得第二中间体；以及将所述第二中间体进行第三次研磨，并在500℃至700℃进行第三次烧结，获得尖晶石钛酸锂颗粒。A method for preparing a lithium ion battery electrode active material, comprising the steps of: providing a lithium source and titanium dioxide, mixing a lithium source and titanium dioxide to form a mixture, and grinding the mixture for the first time to obtain precursor particles; The precursor particles are calcined at 500 ° C to 600 ° C to obtain a first intermediate; the plurality of first intermediates are subjected to a second grinding, and the second sintering is performed at 800 ° C to 1000 ° C to obtain the first a second intermediate; and subjecting the second intermediate to a third grinding and performing a third sintering at 500 ° C to 700 ° C to obtain spinel lithium titanate particles.
相对于现有技术，本发明采用多次研磨与多次烧结相结合的方法来制备钛酸锂颗粒，特别是在第三次烧结前将第二中间体颗粒进行第三次研磨，可通过控制研磨的条件使第二中间体颗粒粒径变小并使其分布更均匀，使第三次烧结后得到形貌规则、粒径较小且分布均匀的钛酸锂晶体。将第二中间体颗粒进行第三次研磨，进一步细化第二中间体颗粒，能使第二中间体颗粒在第三次烧结过程中和氧气进行充分的接触，弥补第二次烧结过程中由于较高的烧结温度而形成的钛酸锂晶体氧缺陷，最终获得形貌规则、粒径较小且均匀分布、振实密度高、晶格缺陷少、容量较高且循环性能好的表面碳包覆钛酸锂电极活性材料。Compared with the prior art, the present invention adopts a method of combining multiple grinding and multiple sintering to prepare lithium titanate particles, especially the third grinding of the second intermediate particles before the third sintering, which can be controlled by The conditions of the grinding make the particle size of the second intermediate particles smaller and make the distribution more uniform, so that the lithium titanate crystal having a regular morphology, a small particle size and a uniform distribution is obtained after the third sintering. The second intermediate particles are subjected to a third grinding to further refine the second intermediate particles, so that the second intermediate particles can be sufficiently contacted with oxygen during the third sintering process to compensate for the second sintering process. The lithium niobate crystal oxygen deficiency formed by the higher sintering temperature finally obtains the surface carbon package with regular morphology, small particle size and uniform distribution, high tap density, less lattice defects, high capacity and good cycle performance. Lithium titanate electrode active material.
附图说明DRAWINGS
图1为本发明第一实施方式提供的锂离子电池电极活性材料的制备流程图。1 is a flow chart showing the preparation of an electrode active material for a lithium ion battery according to a first embodiment of the present invention.
图2是本发明实施例1制备的钛酸锂颗粒的XRD测试图。2 is an XRD test chart of lithium titanate particles prepared in Example 1 of the present invention.
图3是本发明实施例1制备的钛酸锂颗粒的扫描电镜照片。Figure 3 is a scanning electron micrograph of lithium titanate particles prepared in Example 1 of the present invention.
图4是本发明对比例1制备的钛酸锂颗粒的扫描电镜照片。4 is a scanning electron micrograph of lithium titanate particles prepared in Comparative Example 1 of the present invention.
图5为采用本发明实施例1制备的钛酸锂电极活性材料作为负极的电池在不同倍率下首次充放电的比容量测试曲线图。Fig. 5 is a graph showing the specific capacity test of the first charge and discharge of the battery using the lithium titanate electrode active material prepared in Example 1 of the present invention as a negative electrode at different magnifications.
图6为采用本发明实施例1制备的钛酸锂电极活性材料作为负极的电池在不同倍率下循环性能测试曲线图。Fig. 6 is a graph showing the cycle performance test of a battery using a lithium titanate electrode active material prepared in Example 1 of the present invention as a negative electrode at different magnifications.
图7是本发明实施例1制备的碳包覆的钛酸锂颗粒的透射电镜照片。Figure 7 is a transmission electron micrograph of carbon-coated lithium titanate particles prepared in Example 1 of the present invention.
图8是本发明实施例2制备的碳包覆的钛酸锂颗粒的透射电镜照片。Figure 8 is a transmission electron micrograph of carbon-coated lithium titanate particles prepared in Example 2 of the present invention.
具体实施方式detailed description
以下将结合附图详细说明本发明锂离子电池电极活性材料的制备方法。Hereinafter, a method for preparing a lithium ion battery electrode active material of the present invention will be described in detail with reference to the accompanying drawings.
本发明第一实施方式提供一种锂离子电池电极活性材料的制备方法，其包括以下步骤：A first embodiment of the present invention provides a method for preparing a lithium ion battery electrode active material, which comprises the following steps:
S1，提供锂源和二氧化钛，将锂源和二氧化钛混合形成一混合物，并对该混合物进行第一次研磨，获得多个前驱体颗粒；S1, providing a lithium source and titanium dioxide, mixing a lithium source and titanium dioxide to form a mixture, and performing the first grinding on the mixture to obtain a plurality of precursor particles;
S2，将所述前驱体颗粒在500℃至600℃进行预烧，获得多个第一中间体颗粒；S2, the precursor particles are calcined at 500 ° C to 600 ° C to obtain a plurality of first intermediate particles;
S3，将所述多个第一中间体颗粒进行第二次研磨，并在800℃至1000℃进行第二次烧结，获得多个第二中间体颗粒；以及S3, performing the second grinding of the plurality of first intermediate particles, and performing a second sintering at 800 ° C to 1000 ° C to obtain a plurality of second intermediate particles;
S4，将所述多个第二中间体颗粒进行第三次研磨，并在500℃至700℃进行第三次烧结，获得多个尖晶石钛酸锂颗粒。S4, the plurality of second intermediate particles are subjected to a third grinding, and the third sintering is performed at 500 ° C to 700 ° C to obtain a plurality of spinel lithium titanate particles.
在上述步骤S1中，所述锂源可为锂盐、氢氧化锂(LiOH)或锂盐与氢氧化锂的混合物。该锂盐可为选自碳酸锂、硫酸锂、硝酸锂、氯化锂以及草酸锂等制备锂离子电池电极活性材料常用的锂盐中的一种或几种，且并不限于该所列举的几种。优选地，该锂源为碳酸锂、氯化锂以及氢氧化锂中的一种或几种。该锂源可为粉末或颗粒状，优选为纳米级粉末或颗粒。所述二氧化钛可为金红石型二氧化钛以及锐钛矿型二氧化钛的一种或两种的混合物，优选为锐钛矿型二氧化钛。所述二氧化钛可为粉末或颗粒状，优选为纳米级粉末或颗粒，其粒径范围优选为10nm到20nm。所述锂源和二氧化钛中摩尔比Li:Ti=0.81:1至1:1，优选地，所述摩尔比可为0.81:1至0.85:1。In the above step S1, the lithium source may be a lithium salt, lithium hydroxide (LiOH) or a mixture of a lithium salt and lithium hydroxide. The lithium salt may be one or more selected from lithium salts commonly used for preparing lithium ion battery electrode active materials, such as lithium carbonate, lithium sulfate, lithium nitrate, lithium chloride, and lithium oxalate, and is not limited to the listed ones. Several. Preferably, the lithium source is one or more of lithium carbonate, lithium chloride and lithium hydroxide. The lithium source can be in the form of a powder or granules, preferably a nano-sized powder or granule. The titanium dioxide may be a mixture of one or both of rutile type titanium dioxide and anatase type titanium dioxide, preferably anatase type titanium dioxide. The titanium dioxide may be in the form of a powder or granules, preferably a nano-sized powder or granule, preferably having a particle size ranging from 10 nm to 20 nm. The molar ratio of Li:Ti = 0.81:1 to 1:1 in the lithium source and titanium dioxide, preferably, the molar ratio may be 0.81:1 to 0.85:1.
在上述步骤S1中，所述第一次研磨的目的是细化锂源颗粒和二氧化钛颗粒，使所述锂源和二氧化钛的混合更均匀，有利于形成具有规则形貌且物相均匀的产物。In the above step S1, the purpose of the first grinding is to refine the lithium source particles and the titanium dioxide particles, so that the mixing of the lithium source and the titanium dioxide is more uniform, and it is advantageous to form a product having a regular morphology and a uniform phase.
所述第一次研磨进一步包括在所述混合物中加入分散剂进行研磨，得到混合物浆料。加入分散剂进行研磨可以使前驱体颗粒的分散效果更好，使研磨更均匀。所述混合物浆料中的分散剂仅仅覆盖所述混合物表面即可。所述分散剂可为水、乙醇以及丙酮的一种或几种。所述分散剂与所述前驱体颗粒的质量比可在2:1到1.5:1的范围内。进一步地，还可以将混合物浆料进行超声分散、干燥和过筛，超声分散可以减少混合物浆料中前驱体颗粒的团聚，过筛可以将粒径较大的前驱体颗粒筛除。所述超声分散的时间可为0.5小时至3小时。所述干燥可以是自然风干、用烤箱烘干、真空干燥或喷雾干燥，优选为真空干燥。所述过筛使用的筛网目数范围可为400目到500目。所述研磨可以是任何方式的研磨，优选为球磨。所述球磨的转速范围可为450r/min到500r/min，球磨时间可为3小时到4小时。The first grinding further comprises adding a dispersing agent to the mixture for grinding to obtain a mixture slurry. The addition of a dispersant for grinding can make the dispersion of the precursor particles better and make the grinding more uniform. The dispersing agent in the mixture slurry only covers the surface of the mixture. The dispersing agent may be one or more of water, ethanol, and acetone. The mass ratio of the dispersant to the precursor particles may range from 2:1 to 1.5:1. Further, the mixture slurry can also be ultrasonically dispersed, dried and sieved, and ultrasonic dispersion can reduce the agglomeration of the precursor particles in the mixture slurry, and the sieve can sieve the larger particle size precursor particles. The ultrasonic dispersion may be carried out for a period of from 0.5 hours to 3 hours. The drying may be naturally air dried, oven dried, vacuum dried or spray dried, preferably vacuum dried. The screen mesh used for the screening may range from 400 mesh to 500 mesh. The grinding can be any manner of grinding, preferably ball milling. The ball mill can have a rotational speed ranging from 450 r/min to 500 r/min and a ball milling time of from 3 hours to 4 hours.
在上述步骤S2中，锂源和二氧化钛可先在相对较低温度下进行初步反应，以避免锂源在高温下的大量挥发。所述预烧的温度范围可为500℃至600℃，优选为500℃至550℃，本发明实施例的预烧温度为500℃。所述预烧的升温方法可以将所述前驱体颗粒置于反应炉后直接匀速升温，升温速度范围可以是5℃/min到10℃/min。所述预烧时间根据预烧温度的不同而不同。一般地，所述预烧时间可以是4小时至10小时，优选为6小时至8小时，本发明实施例的所述预烧时间为6小时。所述预烧可以在常压下进行。所述预烧气氛可以是含氧气氛，优选为空气气氛。In the above step S2, the lithium source and the titanium oxide may be initially subjected to a preliminary reaction at a relatively low temperature to avoid a large amount of volatilization of the lithium source at a high temperature. The calcination temperature may range from 500 ° C to 600 ° C, preferably from 500 ° C to 550 ° C, and the calcination temperature of the examples of the present invention is 500 ° C. The pre-firing heating method may directly raise the precursor particles after being placed in the reaction furnace, and the heating rate may range from 5 ° C/min to 10 ° C/min. The calcination time varies depending on the calcination temperature. Generally, the calcination time may be from 4 hours to 10 hours, preferably from 6 hours to 8 hours, and the calcination time of the embodiment of the present invention is 6 hours. The calcination can be carried out under normal pressure. The pre-burning atmosphere may be an oxygen-containing atmosphere, preferably an air atmosphere.
上述步骤S2进一步包括一冷却所述第一中间体颗粒的步骤。所述冷却可以在反应炉中直接冷却，也可以从反应炉取出在空气中自然冷却。所述第一中间体颗粒可冷却至室温。The above step S2 further includes a step of cooling the first intermediate particles. The cooling may be directly cooled in the reaction furnace or may be taken out from the reaction furnace and naturally cooled in the air. The first intermediate particles can be cooled to room temperature.
在上述步骤S3中，所述第二次研磨的目的是细化预烧过程中团聚在一起的第一中间体颗粒，提高所述第一中间体颗粒的反应活性，从而可降低所述第二次烧结的温度和缩短第二次烧结的时间。In the above step S3, the purpose of the second grinding is to refine the first intermediate particles agglomerated together during the calcination process, thereby increasing the reactivity of the first intermediate particles, thereby reducing the second The temperature of the secondary sintering and the time to shorten the second sintering.
所述第二次研磨进一步包括在第一中间体颗粒中加入分散剂进行研磨，得到第一中间体浆料。加入分散剂进行研磨可以使第一中间体颗粒的分散效果更好，使研磨更均匀。所述混合浆料中的分散剂仅仅覆盖所述混合物表面即可。所述分散剂可以是水、乙醇以及丙酮的一种或几种。所述分散剂与第一中间体颗粒的质量比在2:1到1.5:1的范围内。进一步地，还可以将第一中间体浆料进行超声分散、干燥和过筛，超声分散可以减少第一中间体浆料中第一中间体颗粒的团聚，过筛可以将粒径较大的第一中间体颗粒筛除。所述超声分散的时间可为0.5-3小时。所述干燥可为自然风干、用烤箱烘干、真空干燥或喷雾干燥，优选为真空干燥。所述过筛使用的筛网目数范围可为400目到500目。所述研磨可以是任何方式的研磨，优选为球磨。所述球磨的转速范围可为450 r/min到500r/min，球磨时间可为3小时到4小时。The second grinding further comprises adding a dispersant to the first intermediate particles for milling to obtain a first intermediate slurry. The addition of a dispersant for grinding can make the dispersion of the first intermediate particles better and make the grinding more uniform. The dispersing agent in the mixed slurry only covers the surface of the mixture. The dispersing agent may be one or more of water, ethanol, and acetone. The mass ratio of the dispersant to the first intermediate particles is in the range of 2:1 to 1.5:1. Further, the first intermediate slurry may be ultrasonically dispersed, dried and sieved, and the ultrasonic dispersion may reduce the agglomeration of the first intermediate particles in the first intermediate slurry, and the sieve may have a larger particle size. An intermediate particle is screened. The time for the ultrasonic dispersion may be from 0.5 to 3 hours. The drying can be naturally air dried, oven dried, vacuum dried or spray dried, preferably vacuum dried. The screen mesh used for the screening may range from 400 mesh to 500 mesh. The grinding can be any manner of grinding, preferably ball milling. The ball mill can have a rotational speed ranging from 450 r/min to 500 r/min and a ball milling time of from 3 hours to 4 hours.
在上述步骤S3中，所述第二次烧结的温度范围可为800℃至1000℃，优选为800℃至900℃，本发明实施例的第二次烧结温度为800℃。所述第二次烧结的升温方法可以将第一中间体颗粒置于反应炉后匀速升温到预定温度，升温速度范围可为5℃/min到10℃/min。所述第二次烧结的时间根据烧结温度的不同而不同。所述第二次烧结时间可为10小时至18小时，优选为10小时至14小时，本发明实施例的第二次烧结时间为12小时。所述第二次烧结可以在常压下进行。所述第二次烧结的气氛可以是含氧气氛，优选为空气气氛。In the above step S3, the temperature of the second sintering may range from 800 ° C to 1000 ° C, preferably from 800 ° C to 900 ° C, and the second sintering temperature of the embodiment of the present invention is 800 ° C. The heating method of the second sintering may be performed after the first intermediate particles are placed in the reaction furnace and the temperature is raised to a predetermined temperature at a constant speed, and the heating rate may range from 5 ° C/min to 10 ° C/min. The time of the second sintering varies depending on the sintering temperature. The second sintering time may be from 10 hours to 18 hours, preferably from 10 hours to 14 hours, and the second sintering time of the embodiment of the present invention is 12 hours. The second sintering can be carried out under normal pressure. The atmosphere of the second sintering may be an oxygen-containing atmosphere, preferably an air atmosphere.
上述步骤S3进一步包括一冷却所述第二中间体颗粒的步骤。所述冷却可以在反应炉中直接冷却，也可以从反应炉取出在空气中自然冷却。所述第二中间体颗粒可冷却至室温。The above step S3 further includes a step of cooling the second intermediate particles. The cooling may be directly cooled in the reaction furnace or may be taken out from the reaction furnace and naturally cooled in the air. The second intermediate particles can be cooled to room temperature.
上述步骤S4中，所述第三次研磨可进一步细化第二次烧结过程中团聚在一起的第二中间体颗粒。较小颗粒尺寸的电极活性材料能够提供较短的锂离子扩散路径以及较大的电解质与电极两相之间的接触面积，有利于电化学反应的进行，而且形貌良好且粒径均匀分布的球形材料拥有更高的振实密度和更好的流动性。由于第二次烧结的温度较高，在烧结过程中颗粒易团聚，从而导致获得的第二中间体颗粒粒径较大、形貌不规则且粒径分布极不均匀。此时将第二中间体颗粒进行第三次研磨，可通过控制研磨的条件使第二中间体颗粒粒径变小并使其分布更均匀，使第三次烧结后得到形貌规则、粒径较小且分布均匀的钛酸锂晶体。另外，在第二次烧结过程中由于团聚在一起的颗粒不能和氧气进行充分的接触，并且烧结温度高也容易导致生成的第二中间体颗粒发生分解，因此最终获得的第二中间体颗粒存在较多的氧缺陷，钛酸锂晶体结构中氧的缺失会使钛酸锂的循环性能降低。将第二中间体颗粒进行第三次研磨，进一步细化第二中间体颗粒，能使第二中间体颗粒在第三次烧结过程中和氧气进行充分的接触，从而避免了现有技术中固相法在高温烧结的过程中因颗粒的团聚而形成的钛酸锂晶体结构的氧缺陷。本发明中，第三次研磨后获得的第二中间体颗粒的粒径范围可为300nm到400nm。In the above step S4, the third grinding may further refine the second intermediate particles agglomerated together in the second sintering process. The smaller particle size electrode active material can provide a shorter lithium ion diffusion path and a larger contact area between the electrolyte and the two phases of the electrode, which is favorable for the electrochemical reaction, and has a good morphology and uniform particle size distribution. Spherical materials have higher tap density and better flow. Due to the higher temperature of the second sintering, the particles tend to agglomerate during the sintering process, resulting in a larger particle size, an irregular morphology and a very uneven particle size distribution. At this time, the second intermediate particles are subjected to the third grinding, and the second intermediate particles can be made smaller in particle size and more uniformly distributed by controlling the grinding conditions, so that the morphology and particle size are obtained after the third sintering. Smaller and uniformly distributed lithium titanate crystals. In addition, in the second sintering process, since the agglomerated particles are not in sufficient contact with oxygen, and the high sintering temperature is liable to cause decomposition of the generated second intermediate particles, the finally obtained second intermediate particles are present. More oxygen defects, the loss of oxygen in the lithium titanate crystal structure will reduce the cycle performance of lithium titanate. The second intermediate particles are subjected to a third grinding to further refine the second intermediate particles, so that the second intermediate particles can be sufficiently contacted with oxygen during the third sintering process, thereby avoiding the prior art solid The oxygen deficiency of the lithium titanate crystal structure formed by the agglomeration of particles during the high-temperature sintering process. In the present invention, the second intermediate particles obtained after the third grinding may have a particle diameter ranging from 300 nm to 400 nm.
所述第三次研磨进一步包括在第二中间体颗粒中加入分散剂进行研磨，得到第二中间体浆料。加入分散剂进行研磨可以使第二中间体颗粒的分散效果更好，使研磨更均匀。所述混合浆料中的分散剂仅仅覆盖所述混合物表面即可。所述分散剂可为水、乙醇以及丙酮的一种或几种。所述分散剂第二中间体颗粒质量比可在2:1到1.5:1的范围内。进一步地，还可以将第二中间体浆料进行超声分散、干燥和过筛，超声分散可以减少第二中间体浆料中第二中间体颗粒的团聚，过筛可以将粒径较大的第二中间体颗粒筛除。所述超声分散的时间可为0.5小时至3小时。所述干燥可为自然风干、用烤箱烘干、真空干燥或喷雾干燥，优选为真空干燥。所述过筛使用的筛网目数范围可为400目到500目。所述研磨可以是任何方式的研磨，优选为球磨。所述球磨的转速范围可为450 rmp到500rmp，球磨时间可为3小时到4小时。The third grinding further comprises adding a dispersant to the second intermediate particles for milling to obtain a second intermediate slurry. The addition of a dispersing agent for grinding can make the dispersion of the second intermediate particles better and make the grinding more uniform. The dispersing agent in the mixed slurry only covers the surface of the mixture. The dispersing agent may be one or more of water, ethanol, and acetone. The dispersant second intermediate particle mass ratio may range from 2:1 to 1.5:1. Further, the second intermediate slurry may be ultrasonically dispersed, dried and sieved, and the ultrasonic dispersion may reduce the agglomeration of the second intermediate particles in the second intermediate slurry, and the sieve may have a larger particle size. The second intermediate particles are sieved. The ultrasonic dispersion may be carried out for a period of from 0.5 hours to 3 hours. The drying can be naturally air dried, oven dried, vacuum dried or spray dried, preferably vacuum dried. The screen mesh used for the screening may range from 400 mesh to 500 mesh. The grinding can be any manner of grinding, preferably ball milling. The ball mill can have a rotational speed ranging from 450 rmp to 500 rpm and a ball milling time of from 3 hours to 4 hours.
在上述步骤S4中，所述第三次烧结的目的是弥补第二次烧结过程中因颗粒的团聚而形成的钛酸锂晶体结构的氧缺陷。所述第三次烧结的温度不能过高，温度过高不利于形成氧缺陷少的钛酸锂晶体结构，且烧结过程中颗粒易团聚。所述第三次烧结的温度范围为可500℃至700℃，优选的600℃至700℃。更为优选地，所述第三次烧结的温度高于所述预烧的温度。本发明实施例所使用的第三次烧结温度为700℃。所述第三次烧结的升温方法可以将前驱体颗粒置于反应炉后进行匀速升温，升温速度范围可为5℃/min到10℃/min。所述第三次烧结的时间根据第三次烧结温度的不同而不同。一般所述第三次烧结时间可为2小时至8小时，优选为3小时至5小时，本发明实施例所采用的第三次烧结时间为4小时。所述第三次烧结可以在常压下进行。所述第三次烧结的气氛可以是含氧气氛，优选为空气气氛。In the above step S4, the purpose of the third sintering is to compensate for the oxygen deficiency of the lithium titanate crystal structure formed by the agglomeration of the particles during the second sintering. The temperature of the third sintering may not be too high, and the excessive temperature is unfavorable for forming a crystal structure of lithium titanate having less oxygen defects, and the particles are easily agglomerated during sintering. The temperature of the third sintering may range from 500 ° C to 700 ° C, preferably from 600 ° C to 700 ° C. More preferably, the temperature of the third sintering is higher than the temperature of the calcination. The third sintering temperature used in the examples of the present invention was 700 °C. The temperature rising method of the third sintering may be performed after the precursor particles are placed in the reaction furnace and the temperature is raised at a uniform rate, and the temperature rising rate may range from 5 ° C/min to 10 ° C/min. The time of the third sintering differs depending on the third sintering temperature. Generally, the third sintering time may be from 2 hours to 8 hours, preferably from 3 hours to 5 hours, and the third sintering time employed in the examples of the present invention is 4 hours. The third sintering can be carried out under normal pressure. The atmosphere for the third sintering may be an oxygen-containing atmosphere, preferably an air atmosphere.
上述步骤S4进一步包括一在第三次烧结过程中通入含氧气氛的步骤。本步骤可使第三次烧结过程中颗粒与氧气进行充分地接触，使最终获得的钛酸锂晶体的氧缺陷更少，使钛酸锂具有更好的循环性能，并且以恒定流速通入含氧气氛也能起到防止颗粒团聚的作用。在第三次烧结过程中可以40ml/min到60ml/min的流速通入所述含氧气氛。The above step S4 further includes a step of introducing an oxygen-containing atmosphere during the third sintering. This step enables the particles to be sufficiently contacted with oxygen during the third sintering process, so that the finally obtained lithium titanate crystal has less oxygen defects, enables lithium titanate to have better cycle performance, and is introduced at a constant flow rate. The oxygen atmosphere also acts to prevent particle agglomeration. The oxygen-containing atmosphere may be introduced at a flow rate of 40 ml/min to 60 ml/min during the third sintering.
利用本发明制备方法获得的钛酸锂电极活性材料为球形颗粒。所述球形颗粒形貌规则、粒径较小且均匀分布。所述球形颗粒的粒径范围为300nm到400nm。The lithium titanate electrode active material obtained by the production method of the present invention is a spherical particle. The spherical particles have a regular morphology, a small particle size and a uniform distribution. The spherical particles have a particle size ranging from 300 nm to 400 nm.
本发明第二实施方式提供一种锂离子电池电极活性材料的制备方法，其包括以下步骤：A second embodiment of the present invention provides a method for preparing a lithium ion battery electrode active material, which comprises the following steps:
S1，提供锂源和二氧化钛，将锂源和二氧化钛混合形成一混合物，并对该混合物进行第一次研磨，获得多个前驱体颗粒；S1, providing a lithium source and titanium dioxide, mixing a lithium source and titanium dioxide to form a mixture, and performing the first grinding on the mixture to obtain a plurality of precursor particles;
S2，将所述前驱体颗粒在500℃至600℃进行预烧，获得多个第一中间体颗粒；S2, the precursor particles are calcined at 500 ° C to 600 ° C to obtain a plurality of first intermediate particles;
S3，将所述多个第一中间体颗粒进行第二次研磨，并在800℃至1000℃进行第二次烧结，获得多个第二中间体颗粒；以及S3, performing the second grinding of the plurality of first intermediate particles, and performing a second sintering at 800 ° C to 1000 ° C to obtain a plurality of second intermediate particles;
S4，将所述多个第二中间体颗粒进行第三次研磨，并在500℃至700℃进行第三次烧结，获得多个尖晶石钛酸锂颗粒。S4, the plurality of second intermediate particles are subjected to a third grinding, and the third sintering is performed at 500 ° C to 700 ° C to obtain a plurality of spinel lithium titanate particles.
S5，对所述尖晶石钛酸锂颗粒进行表面碳包覆。S5, surface carbon coating of the spinel lithium titanate particles.
本发明实施方式提供的锂离子电池电极活性材料的制备方法其步骤S1到S4与本发明第一实施例提供的锂离子电池电极活性材料的制备方法的步骤和原理基本类似。本发明通过步骤S1到S4，可以获得形貌规则、粒径较小且均匀分布、振实密度高、晶格缺陷少且容量较高的钛酸锂颗粒。对所述钛酸锂颗粒进行表面碳包覆可进一步提高该钛酸锂电极活性材料的导电性，从而获得形貌规则、粒径较小且均匀分布、振实密度高、晶格缺陷少且容量更高的表面碳包覆钛酸锂电极活性材料。The method for preparing the lithium ion battery electrode active material provided by the embodiment of the present invention is substantially similar to the steps and principles of the method for preparing the lithium ion battery electrode active material provided by the first embodiment of the present invention. According to the present invention, through steps S1 to S4, lithium titanate particles having a regular morphology, a small particle size and uniform distribution, a high tap density, a small lattice defect, and a high capacity can be obtained. Surface carbon coating of the lithium titanate particles can further improve the conductivity of the lithium titanate electrode active material, thereby obtaining regular morphology, small and uniform particle size, high tap density, and low lattice defects. A higher capacity surface carbon coated lithium titanate electrode active material.
在上述步骤S5中，所述表面碳包覆的方法可包括固相法和液相法。所述固相法可以将钛酸锂颗粒与固体碳源颗粒进行混合研磨后在惰性气体保护下进行高温处理，在高温处理过程中，碳源发生分解并在钛酸锂颗粒表面形成碳包覆层。In the above step S5, the method of surface carbon coating may include a solid phase method and a liquid phase method. The solid phase method can mix and grind lithium titanate particles with solid carbon source particles and then perform high temperature treatment under inert gas protection. During high temperature treatment, the carbon source is decomposed and carbon coated on the surface of the lithium titanate particles. Floor.
所述液相法包括浸渍法和原位聚合法。所述浸渍法可以将碳源溶于溶剂中，然后在搅拌条件下加入钛酸锂颗粒，得到表面包覆有碳源物质的钛酸锂颗粒；用自然风干、烤箱烘干、真空干燥或喷雾干燥等干燥方法蒸干溶剂；将表面包覆有碳源物质的钛酸锂颗粒在惰性气体保护下高温处理，在高温处理过程中，钛酸锂颗粒表面包覆的碳源发生分解并在钛酸锂颗粒表面形成碳包覆层。The liquid phase method includes a dipping method and an in-situ polymerization method. The dipping method may dissolve a carbon source in a solvent, and then add lithium titanate particles under stirring to obtain lithium titanate particles coated with a carbon source material; dry with natural air, oven, vacuum dry or spray. Drying and other drying methods: evaporating the solvent; the lithium titanate particles coated with the carbon source material are treated under high temperature under high temperature treatment, and the carbon source coated on the surface of the lithium titanate particles is decomposed and titanium in the high temperature treatment process. A surface of the lithium acid particles forms a carbon coating layer.
所述原位聚合法可以将钛酸锂颗粒置于有机聚合物单体溶液中，在搅拌的条件下引发有机聚合物单体在钛酸锂颗粒表面发生聚合反应，形成表面包覆有机聚合物的钛酸锂颗粒；将表面包覆有机聚合物的钛酸锂颗粒在惰性气体保护下高温处理，在高温处理过程中，钛酸锂颗粒表面的有机聚合物发生分解并在钛酸锂颗粒表面形成碳包覆层。The in-situ polymerization method can place lithium titanate particles in an organic polymer monomer solution, and initiate polymerization of the organic polymer monomer on the surface of the lithium titanate particles under stirring to form a surface-coated organic polymer. Lithium titanate particles; the lithium titanate particles coated with the organic polymer are subjected to high temperature treatment under the protection of an inert gas, and the organic polymer on the surface of the lithium titanate particles is decomposed and on the surface of the lithium titanate particles during the high temperature treatment. A carbon coating layer is formed.
优选地，本发明用原位聚合法来制备碳包覆的钛酸锂颗粒，具体步骤为：Preferably, the present invention uses in situ polymerization to prepare carbon coated lithium titanate particles, the specific steps are:
（1）将所述钛酸锂颗粒均匀分散于有机聚合物前驱体溶液中，所述有机聚合物前驱体溶液包括有机聚合物单体、溶剂和引发剂；(1) uniformly dispersing the lithium titanate particles in an organic polymer precursor solution, the organic polymer precursor solution comprising an organic polymer monomer, a solvent and an initiator;
（2）在搅拌和加热的条件下使所述有机聚合物前驱体溶液中的有机聚合物单体发生聚合反应，获得含有表面包覆有机聚合物的钛酸锂颗粒的混合溶液；(2) polymerizing the organic polymer monomer in the organic polymer precursor solution under stirring and heating to obtain a mixed solution of lithium titanate particles containing the surface-coated organic polymer;
（3）分离所述混合溶液，得到多个表面包覆有机聚合物的钛酸锂颗粒；以及(3) separating the mixed solution to obtain a plurality of lithium titanate particles coated with an organic polymer;
（4）干燥所述表面包覆有机聚合物的钛酸锂颗粒，在惰性气体保护下于600℃至800℃下烧结1小时至3小时，得到表面碳包覆钛酸锂颗粒的电极活性材料。(4) drying the lithium titanate particles coated with the surface-coated organic polymer, and sintering at 600 ° C to 800 ° C for 1 hour to 3 hours under an inert gas atmosphere to obtain an electrode active material of surface carbon-coated lithium titanate particles. .
在所述步骤（1）中，所述有机物单体为共轭二烯烃、乙烯基单体以及功能型单体中的一种或几种。所述共轭二烯烃为选自1，3-丁二烯、2-甲基-1，3丁二烯、2，3-二甲基-1，3-丁二烯以及异戊二烯的一种或几种，所述乙烯基单体为选自乙烯、丙烯、异丁烯、丙烯腈、苯乙烯以及甲基苯乙烯的一种或几种。所述功能型单体为选自丙烯酸甲酯、甲基丙烯酸甲酯、丙烯酸乙酯、甲基丙烯酸乙酯、丙烯酸丁酯、甲基丙烯酸丁酯、丙烯酰胺以及甲基丙烯酰胺的一种或几种。In the step (1), the organic monomer is one or more of a conjugated diene, a vinyl monomer, and a functional monomer. The conjugated diene is selected from the group consisting of 1,3-butadiene, 2-methyl-1,3 butadiene, 2,3-dimethyl-1,3-butadiene, and isoprene. One or more of the vinyl monomers are one or more selected from the group consisting of ethylene, propylene, isobutylene, acrylonitrile, styrene, and methyl styrene. The functional monomer is one selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylamide, and methacrylamide. Several.
所述溶剂可以溶解所述有机物单体和所述引发剂。该溶剂优选为有机溶剂。该有机溶剂为烷烃、醇、醚、酮、芳香烃、卤代烃、杂环化合物、含氮化合物以及含硫化合物中的一种或几种。优选为甲苯、环己烷、二氯甲烷、乙醇、石油醚、环氧丙烷、三氯乙烯、二甲基亚砜以及氮氮二甲基甲酰胺的一种或几种。The solvent can dissolve the organic monomer and the initiator. The solvent is preferably an organic solvent. The organic solvent is one or more of an alkane, an alcohol, an ether, a ketone, an aromatic hydrocarbon, a halogenated hydrocarbon, a heterocyclic compound, a nitrogen-containing compound, and a sulfur-containing compound. Preferred are one or more of toluene, cyclohexane, dichloromethane, ethanol, petroleum ether, propylene oxide, trichloroethylene, dimethyl sulfoxide, and nitrogen nitroformamide.
所述引发剂用于引发所述有机聚合物单体之间的聚合，可以为有机过氧化物引发剂、无机过氧化物引发剂、偶氮类引发剂以及氧化还原引发剂的一种或几种。所述有机过氧化物引发剂可为选自过氧化苯甲酰、过氧化月桂酰、叔丁基过氧化氢、过氧化乙酸叔丁酯以及过氧化异丙苯的一种或几种。所述无机过氧化物引发剂可为选自过硫酸钾、过硫酸钠以及过硫酸铵中的一种或几种。所述偶氮类引发剂可为选自偶氮二异丁腈、偶氮二异庚腈以及偶氮二异丁酸二甲酯中的一种或几种。所述氧化还原引发剂可为选自氧化苯甲酰/蔗糖、叔丁基过氧化氢/雕白块、叔丁基过氧化氢/焦亚硫酸钠以及过氧化苯甲酰/N，N-二甲基苯胺中的一种或几种。The initiator is used to initiate polymerization between the organic polymer monomers, and may be one or more of an organic peroxide initiator, an inorganic peroxide initiator, an azo initiator, and a redox initiator. Kind. The organic peroxide initiator may be one or more selected from the group consisting of benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, t-butyl peroxyacetate, and cumene peroxide. The inorganic peroxide initiator may be one or more selected from the group consisting of potassium persulfate, sodium persulfate, and ammonium persulfate. The azo initiator may be one or more selected from the group consisting of azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate. The redox initiator may be selected from the group consisting of benzoyl peroxide/sucrose, t-butyl hydroperoxide/carved white block, t-butyl hydroperoxide/sodium metabisulfite, and benzoyl peroxide/N,N-dimethyl One or more of the anilines.
将所述有机聚合物前驱体溶液均匀分散于钛酸锂颗粒表面的方法可为搅拌或超声分散。The method of uniformly dispersing the organic polymer precursor solution on the surface of the lithium titanate particles may be stirring or ultrasonic dispersion.
在上述步骤（2）中，在搅拌的条件下，当有机聚合物前驱体溶液被加热到一定温度时，引发剂受热分解为自由基，并引发有机物单体聚合，最终形成表面包覆有机聚合物的钛酸锂颗粒。所述加热温度可为50℃至150℃。具体加热温度根据有机物单体的性质和引发剂的分解温度来确定，例如当采用苯乙烯为单体、过氧化苯甲酰为引发剂时，聚合反应的温度可为80℃。当采用丙烯腈为单体、偶氮二异丁腈为引发剂时，聚合反应的温度可为70℃。In the above step (2), when the organic polymer precursor solution is heated to a certain temperature under stirring, the initiator is thermally decomposed into a radical, and the organic monomer is polymerized to finally form a surface-coated organic polymerization. Lithium titanate particles. The heating temperature may be from 50 ° C to 150 ° C. The specific heating temperature is determined according to the nature of the organic monomer and the decomposition temperature of the initiator. For example, when styrene is used as the monomer or benzoyl peroxide is used as the initiator, the polymerization temperature may be 80 °C. When acrylonitrile is used as the monomer and azobisisobutyronitrile is used as the initiator, the polymerization temperature can be 70 °C.
在上述步骤（3）中，所述分离方法可以为过滤或抽滤。In the above step (3), the separation method may be filtration or suction filtration.
所述步骤（3）进一步包括一纯化所述表面包覆有机聚合物的钛酸锂颗粒的步骤。具体地，所述纯化方式可以为用挥发性有机溶剂对表面包覆有机聚合物的钛酸锂颗粒进行洗涤。所述挥发性有机溶剂可以为甲醇、乙醇、二氯甲烷、正庚烷以及甲苯中的一种或几种。The step (3) further includes a step of purifying the lithium titanate particles coated with the surface-coated organic polymer. Specifically, the purification method may be washing the surface-coated organic polymer lithium titanate particles with a volatile organic solvent. The volatile organic solvent may be one or more of methanol, ethanol, dichloromethane, n-heptane, and toluene.
在上述步骤（4）中，所述干燥方法可以为自然风干、用烤箱烘干、真空干燥或喷雾干燥，优选为真空干燥。为防止包覆的有机聚合物在干燥过程中分解，干燥温度需低于200℃。In the above step (4), the drying method may be natural air drying, oven drying, vacuum drying or spray drying, preferably vacuum drying. In order to prevent the coated organic polymer from decomposing during the drying process, the drying temperature needs to be lower than 200 °C.
所述惰性气体可以为氮气、氦气、氖气、氩气、氪气及氙气中的一种或多种。在烧结过程中，包覆在钛酸锂颗粒表面的有机聚合物发生分解碳化，由于有机聚合物在钛酸锂颗粒表面均匀包覆，从而形成表面均匀碳包覆的钛酸锂颗粒电极活性材料。The inert gas may be one or more of nitrogen, helium, neon, argon, helium, and neon. During the sintering process, the organic polymer coated on the surface of the lithium titanate particles is decomposed and carbonized, and the organic polymer is uniformly coated on the surface of the lithium titanate particles to form a surface-uniform carbon-coated lithium titanate particle electrode active material. .
所述表面碳包覆钛酸锂电极活性材料中，形成的碳包覆层均匀连续。优选地，每个所述钛酸锂颗粒表面均包覆有均匀连续的碳层。所述碳包覆层的厚度范围可为3nm至8nm。表面碳包覆钛酸锂电极活性材料的粒径范围为400nm到500nm。In the surface carbon-coated lithium titanate electrode active material, the formed carbon coating layer is uniformly continuous. Preferably, each of said lithium titanate particles is coated with a uniform continuous carbon layer. The carbon coating layer may have a thickness ranging from 3 nm to 8 nm. The surface carbon-coated lithium titanate electrode active material has a particle diameter ranging from 400 nm to 500 nm.
利用本发明制备方法获得表面碳包覆钛酸锂电极活性材料为球形颗粒。所述球形颗粒形貌规则、粒径较小且均匀分布，并且其表面具有均匀的碳包覆层。The surface carbon-coated lithium titanate electrode active material is obtained by the preparation method of the present invention as spherical particles. The spherical particles have a regular morphology, a small particle size and a uniform distribution, and a uniform carbon coating on the surface.
实施例1Example 1
（a）取2.7281g碳酸锂与7.2989g锐钛矿型二氧化钛，20ml乙醇溶液，一起置于玛瑙罐中，加入适量玛瑙球，以400rmp的转速球磨4h得到混合浆料，将混合浆料进行强力超声1h，减小粒子的团聚，在60 ℃下真空干燥2小时，然后用400目的筛网过筛，得到多个前驱体颗粒；(a) Take 2.7281g of lithium carbonate and 7.2989g of anatase type titanium dioxide, 20ml of ethanol solution, put them together in an agate tank, add an appropriate amount of agate ball, ball milled at 400rmp for 4h to obtain a mixed slurry, and mix the slurry. Ultrasonic for 1 h, reducing the agglomeration of the particles, drying under vacuum at 60 ° C for 2 hours, and then sieving through a 400 mesh sieve to obtain a plurality of precursor particles;
（b）将上述前驱体颗粒置于马弗炉中，在常压下于空气环境中在5℃/min速度下升温至500℃保温6h，保温完毕后自然冷却，得到多个第一中间体颗粒；(b) The precursor particles are placed in a muffle furnace, heated to 500 ° C for 6 h under an atmospheric pressure at a temperature of 5 ° C / min, and naturally cooled after the completion of the heat preservation to obtain a plurality of first intermediates. Granule
（c）将上述第一中间体颗粒置于玛瑙罐中，加入适量玛瑙球，以500 rmp的转速球磨4 h，进行第二次研磨，第二次研磨后置于马弗炉中，在常压下于空气环境中在5℃/min速度下升温至800℃保温12h，保温完毕后自然冷却，得到多个第二中间体颗粒；(c) placing the first intermediate granules in an agate tank, adding an appropriate amount of agate balls, ball milling at 500 rpm for 4 h, performing a second grinding, and placing the second grinding in a muffle furnace, usually Pressed in an air environment at a temperature of 5 ° C / min, the temperature is raised to 800 ° C for 12 h, after the completion of the insulation, it is naturally cooled to obtain a plurality of second intermediate particles;
（d）将上述第二中间体颗粒置于玛瑙罐中，加入适量玛瑙球，以500rmp的转速球磨3h，进行第三次研磨，第三次研磨后置于马弗炉中，在常压下于空气环境中在5℃/min速度下升温至在700℃保温4h，保温完毕后自然冷却，即得到尖晶石型钛酸锂电极活性材料。(d) placing the second intermediate granules in an agate tank, adding an appropriate amount of agate balls, ball milling at 500 rpm for 3 hours, performing a third grinding, and placing the third grinding in a muffle furnace under normal pressure. The temperature is raised at a temperature of 5 ° C / min in an air environment to be kept at 700 ° C for 4 h, and after the completion of the heat preservation, it is naturally cooled, that is, a spinel type lithium titanate electrode active material is obtained.
对比例1Comparative example 1
本对比例1与上述实施例1基本相同，其区别仅在于，前驱颗粒在后续的烧结过程中没有进行第二次研磨和第三次研磨，直接进行第二次烧结和第三次烧结。This Comparative Example 1 is substantially the same as the above-described Embodiment 1, except that the precursor particles are not subjected to the second grinding and the third grinding in the subsequent sintering process, and the second sintering and the third sintering are directly performed.
请参阅图2到图6，图2和图3分别为本发明实施例1制备的钛酸锂颗粒的XRD测试图和扫描电镜照片。图4为对比例1制备的钛酸锂颗粒的扫描电镜照片。从图2可知，采用本发明方法制备的钛酸锂颗粒无杂相、无杂峰，结晶度良好。从图3和图4得知，采用本发明方法制备的钛酸锂颗粒粒径小于500nm，粒径较小且粒径分布均匀，而对比例1制备的钛酸锂颗粒其粒径大于1um，粒径分布不均匀并且有明显的团聚现象。Please refer to FIG. 2 to FIG. 6. FIG. 2 and FIG. 3 are respectively an XRD test chart and a scanning electron micrograph of the lithium titanate particles prepared in Example 1 of the present invention. 4 is a scanning electron micrograph of lithium titanate particles prepared in Comparative Example 1. As can be seen from FIG. 2, the lithium titanate particles prepared by the method of the present invention have no impurity phase, no impurity peak, and good crystallinity. 3 and FIG. 4, the lithium titanate particles prepared by the method of the present invention have a particle diameter of less than 500 nm, a small particle diameter and a uniform particle size distribution, and the lithium titanate particles prepared in the comparative example 1 have a particle diameter of more than 1 um. The particle size distribution is uneven and there is a significant agglomeration.
请参阅图5、图6和表1，图5为采用本发明实施例1制备的钛酸锂电极活性材料作为负极活性材料的电池在不同倍率下首次充放电的比容量测试曲线图，图6为采用本发明实施例1制备的钛酸锂电极活性材料作为负极活性材料的电池在不同倍率下循环性能测试曲线图，从图中可以看出，在0.1C、1C、5C倍率下电池的比容量平均为158mAh/g、150 mAh/g和92mAh/g，具有较好的倍率性能，从图6可以看出，分别在0.1C、1C、5C的条件下，随着循环次数的增多，电池的比容量下降较小。从表1可以看出，分别在0.1C、1C、5C的条件下，电池具有较高的首次效率。表明实施例1制备的钛酸锂电极活性材料即使高倍率仍然具有较高的首次效率、较好的循环性能以及容量保持率。Please refer to FIG. 5, FIG. 6 and Table 1. FIG. 5 is a graph showing the specific capacity test of the first charge and discharge of the battery using the lithium titanate electrode active material prepared in Example 1 of the present invention as the negative electrode active material at different magnifications, FIG. A graph showing the cycle performance test of a battery using the lithium titanate electrode active material prepared in Example 1 of the present invention as a negative electrode active material at different magnifications. As can be seen from the figure, the ratio of the battery at a ratio of 0.1 C, 1 C, and 5 C is used. The average capacity is 158mAh/g, 150 mAh/g and 92mAh/g, which has better rate performance. It can be seen from Fig. 6 that under the conditions of 0.1C, 1C and 5C, respectively, with the increase of the number of cycles, the battery The specific capacity decline is small. It can be seen from Table 1 that the battery has a high first efficiency under the conditions of 0.1 C, 1 C, and 5 C, respectively. It is shown that the lithium titanate electrode active material prepared in Example 1 has high first efficiency, good cycle performance, and capacity retention even at a high rate.
表1 实施例1钛酸锂电极活性材料作为负极的电池的首次效率Table 1 Example 1 Lithium titanate electrode active material First efficiency of a battery as a negative electrode
0.1C首次效率0.1C first efficiency 1C首次效率1C first efficiency 5C首次效率5C first efficiency
实施例1Example 1 97.0%97.0% 98.1%98.1% 97.7%97.7%
实施例2Example 2
（a）在三颈烧瓶中分别加入50ml乙醇，1g 实施例1制备的钛酸锂颗粒（LTO），0.3725g苯乙烯单体与0.0077g过氧化苯甲酰（BPO）引发剂，用磁力搅拌器搅拌使其混合均匀；(a) 50 ml of ethanol, 1 g of lithium titanate particles (LTO) prepared in Example 1, 0.3725 g of styrene monomer and 0.0077 g of benzoyl peroxide (BPO) initiator were magnetically stirred in a three-necked flask. Stirring to make it evenly mixed;
（b）在搅拌条件下加热至80℃，在80℃温度下反应2h，然后置于恒温装置中150度保温10h，得到含有表面包覆聚苯乙烯的钛酸锂颗粒的混合溶液；(b) heating to 80 ° C under stirring conditions, reaction at 80 ° C temperature for 2h, and then placed in a thermostat at 150 degrees for 10h, to obtain a mixed solution containing surface coated polystyrene lithium titanate particles;
（c）抽滤上述混合溶液，得到表面包覆聚苯乙烯的钛酸锂颗粒，用甲醇洗涤上述钛酸锂颗粒；(c) suctioning the above mixed solution to obtain lithium titanate particles coated with polystyrene on the surface, and washing the above lithium titanate particles with methanol;
（d）将包覆聚苯乙烯的钛酸锂颗粒在80℃真空干燥12h后，置于管式炉中N2保护，600℃烧结1h，即得到碳包覆的钛酸锂颗粒。(d) The polystyrene-coated lithium titanate particles were vacuum dried at 80 ° C for 12 h, placed in a tube furnace for N 2 protection, and sintered at 600 ° C for 1 h to obtain carbon-coated lithium titanate particles.
实施例3Example 3
（a）在三颈烧瓶中分别加入20ml二甲基亚砜（DMSO），1g实施例1制备的钛酸锂颗粒（LTO），0.5306g丙烯腈单体与0.0111g偶氮二异丁腈（AIBN）引发剂，用磁力搅拌器搅拌使其混合均匀；(a) 20 ml of dimethyl sulfoxide (DMSO), 1 g of lithium titanate particles (LTO) prepared in Example 1, 0.5306 g of acrylonitrile monomer and 0.0111 g of azobisisobutyronitrile were respectively added to a three-necked flask ( AIBN) initiator, stirred with a magnetic stirrer to make it evenly mixed;
（b）在搅拌条件下将上述混合溶液加热至70℃，在70℃温度下反应3h得到含有表面包覆聚苯乙烯的钛酸锂颗粒的混合溶液；(b) heating the above mixed solution to 70 ° C under stirring, and reacting at 70 ° C for 3 h to obtain a mixed solution of lithium titanate particles containing surface-coated polystyrene;
（c）抽滤该混合溶液，得到表面包覆聚苯乙烯的钛酸锂颗粒，用甲醇洗涤上述钛酸锂颗粒；(c) suction-filtering the mixed solution to obtain lithium titanate particles coated with polystyrene on the surface, and washing the lithium titanate particles with methanol;
（d）将包覆聚苯乙烯的钛酸锂颗粒在80℃真空干燥12h后，置于管式炉中N2保护，600℃烧结1h，即得到碳包覆的钛酸锂颗粒。(d) The polystyrene-coated lithium titanate particles were vacuum dried at 80 ° C for 12 h, placed in a tube furnace for N 2 protection, and sintered at 600 ° C for 1 h to obtain carbon-coated lithium titanate particles.
请参阅图7、图8和表2，图7和图8分别为本发明实施例2和实施例3制备的碳包覆钛酸锂颗粒的透射电镜照片。表2为实施例2和3制备的碳包覆钛酸锂颗粒和实施例1制备的未经碳包覆的钛酸锂颗粒的电化学循环性能对比表。从图7和图8可以看出，碳包覆钛酸锂颗粒厚度均在5nm左右，且厚度较为均匀。从表1中可以看出，碳包覆钛酸锂颗粒比未包覆碳的钛酸锂电化学性能更好，说明采用本发明的碳包覆方法可以得到具有均匀碳包覆层的钛酸锂颗粒，并且可以进一步提高钛酸锂材料的导电性，且最终获得的碳包覆钛酸锂电极材料具有较高的振实密度，较好的流动性及可加工性。Please refer to FIG. 7, FIG. 8 and Table 2. FIG. 7 and FIG. 8 are transmission electron micrographs of carbon-coated lithium titanate particles prepared in Example 2 and Example 3, respectively. Table 2 is a comparison table of electrochemical cycle performance of the carbon-coated lithium titanate particles prepared in Examples 2 and 3 and the carbon-coated lithium titanate particles prepared in Example 1. It can be seen from Fig. 7 and Fig. 8 that the thickness of the carbon-coated lithium titanate particles is about 5 nm, and the thickness is relatively uniform. It can be seen from Table 1 that the carbon-coated lithium titanate particles have better electrochemical performance than the uncoated carbon lithium titanate, indicating that the lithium titanate having a uniform carbon coating layer can be obtained by the carbon coating method of the present invention. The particles and the conductivity of the lithium titanate material can be further improved, and the finally obtained carbon-coated lithium titanate electrode material has high tap density, good fluidity and workability.
表2碳包覆钛酸锂和未包覆碳的钛酸锂的电化学性能循环对比表Table 2 Comparison of electrochemical performance of carbon coated lithium titanate and uncoated carbon lithium titanate
0.1C放电比容量0.1C discharge specific capacity 5C放电比容量5C discharge specific capacity 0.1C首次效率0.1C first efficiency
实施例1 LTOExample 1 LTO 158mAh/g158mAh/g 92mAh/g92mAh/g 97.7%97.7%
实施例2碳包覆LTOExample 2 Carbon coated LTO 162mAh/g162mAh/g 98mAh/g98mAh/g 99.2%99.2%
实施例3碳包覆LTOExample 3 Carbon coated LTO 164mAh/g164mAh/g 102mAh/g102mAh/g 98.9%98.9%
。.
本发明采用多次研磨与多次烧结相结合的方法来制备钛酸锂颗粒，并对钛酸锂颗粒进行表面碳包覆，制备出了形貌规则、粒径较小且均匀分布、振实密度高、晶格缺陷少、具有均匀碳包覆层且容量较高的钛酸锂电极活性材料。The invention adopts a method of combining multiple grinding and multiple sintering to prepare lithium titanate particles, and surface carbon coating of the lithium titanate particles, preparing a regular shape, a small particle size and uniform distribution, and tapping. A lithium titanate electrode active material having a high density, a small lattice defect, and a uniform carbon coating layer and a high capacity.
另外，本领域技术人员还可在本发明精神内作其它变化，当然这些依据本发明精神所作的变化，都应包含在本发明所要求保护的范围内。In addition, those skilled in the art can make other changes within the spirit of the invention, and it is to be understood that these changes are intended to be included within the scope of the invention.

Claims (12)

  1. 一种锂离子电池电极活性材料的制备方法，其包括：A method for preparing a lithium ion battery electrode active material, comprising:
    提供锂源和二氧化钛，将锂源和二氧化钛混合形成一混合物，并对该混合物进行第一次研磨，获得多个前驱体颗粒；Providing a lithium source and titanium dioxide, mixing a lithium source and titanium dioxide to form a mixture, and performing the first grinding on the mixture to obtain a plurality of precursor particles;
    将所述前驱体颗粒在500℃至600℃进行预烧，获得多个第一中间体颗粒；The precursor particles are calcined at 500 ° C to 600 ° C to obtain a plurality of first intermediate particles;
    将所述多个第一中间体颗粒进行第二次研磨，并在800℃至1000℃进行第二次烧结，获得多个第二中间体颗粒；以及Performing a second grinding of the plurality of first intermediate particles and performing a second sintering at 800 ° C to 1000 ° C to obtain a plurality of second intermediate particles;
    将所述多个第二中间体颗粒进行第三次研磨，并在500℃至700℃进行第第三次烧结，获得多个尖晶石钛酸锂颗粒。The plurality of second intermediate particles are subjected to a third grinding and subjected to a third sintering at 500 ° C to 700 ° C to obtain a plurality of spinel lithium titanate particles.
  2. 如权利要求1所述的锂离子电池电极活性材料的制备方法，其特征在于，所述二氧化钛为金红石型二氧化钛或锐钛矿型二氧化钛中的一种或几种。The method for producing a lithium ion battery electrode active material according to claim 1, wherein the titanium oxide is one or more selected from the group consisting of rutile-type titanium dioxide and anatase-type titanium oxide.
  3. 如权利要求1所述的锂离子电池电极活性材料的制备方法，其特征在于，所述第三次研磨进一步包括加入分散剂进行研磨，得到第二中间体浆料，将所述第二中间体浆料进行超声分散、干燥和过筛。The method for preparing a lithium ion battery electrode active material according to claim 1, wherein the third grinding further comprises adding a dispersing agent to perform grinding to obtain a second intermediate slurry, wherein the second intermediate is obtained. The slurry is ultrasonically dispersed, dried and sieved.
  4. 如权利要求3所述的锂离子电池电极活性材料的制备方法，其特征在于，所述超声分散的时间为0.5到3小时，所述过筛使用的筛网目数为400目到500目。The method of preparing a lithium ion battery electrode active material according to claim 3, wherein the ultrasonic dispersion is carried out for 0.5 to 3 hours, and the sieve used for the screening is 400 mesh to 500 mesh.
  5. 如权利要求3所述的锂离子电池电极活性材料的制备方法，其特征在于，所述第三次研磨为球磨，所述球磨速度为200 rmp 到1000rmp，球磨时间为2小时到8小时。The method of preparing a lithium ion battery electrode active material according to claim 3, wherein the third grinding is ball milling, the ball milling speed is from 200 rmp to 1000 rpm, and the ball milling time is from 2 hours to 8 hours.
  6. 如权利要求1所述的锂离子电池电极活性材料的制备方法，其特征在于，所述第二中间体颗粒在第三次研磨后的颗粒粒径为300nm到400nm。 The method for preparing a lithium ion battery electrode active material according to claim 1, wherein the second intermediate particles have a particle diameter of 300 nm to 400 nm after the third grinding.
  7. 如权利要求1所述的锂离子电池电极活性材料的制备方法，其特征在于，所述第三次烧结的温度高于所述预烧的温度且低于所述第二次烧结的温度。The method of producing a lithium ion battery electrode active material according to claim 1, wherein the temperature of the third sintering is higher than the temperature of the calcination and lower than the temperature of the second sintering.
  8. 如权利要求1所述的锂离子电池电极活性材料的制备方法，其特征在于，所述预烧、所述第二次烧结和所述第三次烧结的气氛为含氧气氛。 The method of producing a lithium ion battery electrode active material according to claim 1, wherein the atmosphere of the calcination, the second sintering, and the third sintering is an oxygen-containing atmosphere.
  9. 如权利要求8所述的锂离子电池电极活性材料的制备方法，其特征在于，在第三次烧结过程中以40ml/min到60ml/min的流速通入所述含氧气氛。 The method of producing a lithium ion battery electrode active material according to claim 8, wherein the oxygen-containing atmosphere is introduced at a flow rate of from 40 ml/min to 60 ml/min during the third sintering.
  10. 一种锂离子电池电极活性材料的制备方法，其包括： A method for preparing a lithium ion battery electrode active material, comprising:
    提供锂源和二氧化钛，将锂源和二氧化钛混合形成一混合物，并对该混合物进行第一次研磨，获得多个前驱体颗粒；Providing a lithium source and titanium dioxide, mixing a lithium source and titanium dioxide to form a mixture, and performing the first grinding on the mixture to obtain a plurality of precursor particles;
    将所述前驱体颗粒在500℃到600℃进行预烧，获得多个第一中间体颗粒；Pre-firing the precursor particles at 500 ° C to 600 ° C to obtain a plurality of first intermediate particles;
    将所述多个第一中间体颗粒进行第二次研磨，并在800℃到1000℃进行第二次烧结，获得多个第二中间体颗粒；Performing a second grinding of the plurality of first intermediate particles, and performing a second sintering at 800 ° C to 1000 ° C to obtain a plurality of second intermediate particles;
    将所述多个第二中间体颗粒进行第三次研磨，并在500℃到700℃进行第三次烧结，获得多个尖晶石钛酸锂颗粒；以及Performing a third grinding of the plurality of second intermediate particles and performing a third sintering at 500 ° C to 700 ° C to obtain a plurality of spinel lithium titanate particles;
    对所述尖晶石钛酸锂颗粒进行表面碳包覆，得到表面碳包覆钛酸锂颗粒。The spinel lithium titanate particles were subjected to surface carbon coating to obtain surface carbon-coated lithium titanate particles.
  11. 如权利要求10所述的锂离子电池电极活性材料的制备方法，其特征在于，对所述尖晶石钛酸锂颗粒进行表面碳包覆的方法包括：The method for preparing a lithium ion battery electrode active material according to claim 10, wherein the method for surface carbon coating of the spinel lithium titanate particles comprises:
    将所述钛酸锂颗粒均匀分散于有机聚合物前驱体溶液中，所述有机聚合物前驱体溶液包括有机聚合物单体、溶剂和引发剂；Dispersing the lithium titanate particles uniformly in an organic polymer precursor solution, the organic polymer precursor solution comprising an organic polymer monomer, a solvent and an initiator;
    在搅拌和加热的条件下使所述有机聚合物前驱体溶液中的有机聚合物单体发生聚合反应，获得含有表面包覆有机聚合物的钛酸锂颗粒的混合溶液；The organic polymer monomer in the organic polymer precursor solution is polymerized under stirring and heating to obtain a mixed solution of lithium titanate particles containing a surface-coated organic polymer;
    分离所述混合溶液，得到多个表面包覆有机聚合物的钛酸锂颗粒；以及Separating the mixed solution to obtain a plurality of lithium titanate particles coated with an organic polymer;
    干燥所述表面包覆有机聚合物的钛酸锂颗粒，在惰性气体保护下于600℃到800℃下烧结1小时到3小时，得到表面碳包覆钛酸锂颗粒的电极活性材料。The lithium titanate particles coated with the surface-coated organic polymer are dried and sintered at 600 ° C to 800 ° C for 1 hour to 3 hours under an inert gas atmosphere to obtain an electrode active material of surface carbon-coated lithium titanate particles.
  12. 如权利要求11所述的锂离子电池电极活性材料的制备方法，其特征在于，所述表面碳包覆钛酸锂颗粒的粒径为400 nm到500 nm，碳包覆层厚度为3nm到8nm。 The method for preparing a lithium ion battery electrode active material according to claim 11, wherein the surface carbon-coated lithium titanate particles have a particle diameter of 400 nm to 500 nm, and the carbon coating layer has a thickness of 3 nm to 8 nm. .
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