CN113247963A - Preparation method of high-compaction high-rate high-voltage lithium cobalt oxide positive electrode material - Google Patents

Preparation method of high-compaction high-rate high-voltage lithium cobalt oxide positive electrode material Download PDF

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CN113247963A
CN113247963A CN202110717774.6A CN202110717774A CN113247963A CN 113247963 A CN113247963 A CN 113247963A CN 202110717774 A CN202110717774 A CN 202110717774A CN 113247963 A CN113247963 A CN 113247963A
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grading
sintering
lithium cobaltate
crushing
compaction
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CN113247963B (en
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廖达前
唐朝辉
吴涛
曾文赛
胡柳泉
周友元
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Hunan Changyuan Lithium New Energy Co ltd
Hunan Changyuan Lico Co Ltd
Jinchi Energy Materials Co Ltd
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Hunan Changyuan Lithium New Energy Co ltd
Hunan Changyuan Lico Co Ltd
Jinchi Energy Materials Co Ltd
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    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/40—Cobaltates
    • C01G51/70—Cobaltates containing rare earth, e.g. LaCoO3
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
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    • C01—INORGANIC CHEMISTRY
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    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E60/10—Energy storage using batteries

Abstract

The invention discloses a preparation method of a lithium cobaltate positive electrode material, which adopts the steps of solid-phase mixing, sintering and crushing grading, reasonably controls process parameters to prepare a single crystal lithium cobaltate material with D50 of 11.1-15.0 mu m and a single crystal-like lithium cobaltate material with D50 of 3.0-5.0 mu m, and carries out secondary sintering, coarse crushing and dissociation after the two materials are graded and mixed with a coating to obtain the required lithium cobaltate positive electrode material. The preparation method disclosed by the invention is simple and easy to control in process, low in production cost, environment-friendly, high in production efficiency and excellent in product performance, the particle size D50 of the prepared anode material is 6.0-14.0 mu m, and the compaction density is 3.96-4.1 g/cm3The full cell assembled by the positive electrode material has excellent cycle performance and rate capability within the voltage test range of 3.0-4.45V, and can meet the requirements of high compaction and high rateMultiplying power and high charge-discharge voltage.

Description

Preparation method of high-compaction high-rate high-voltage lithium cobalt oxide positive electrode material
Technical Field
The invention belongs to the field of lithium ion battery materials, and particularly relates to a preparation method of a high-compaction high-rate high-voltage lithium cobalt oxide positive electrode material.
Background
With the rapid development of electronic technology, the energy density of lithium cobalt oxide batteries is required to be higher and higher as electronic products are continuously upgraded and updated. At present, it is a great trend to improve the energy density of a battery by improving the charging and discharging voltage of lithium cobaltate, the voltage of the battery is improved to 4.4V and higher voltage, the capacity of the battery can be obviously improved under the condition of not increasing active substances in the battery, the method is one of effective ways for improving the energy density of the battery, and the method has great significance for meeting the high energy density and endurance requirements of high-end portable equipment, so that the domestic lithium cobaltate battery material is developing towards the high voltage direction. In addition, increasing the compaction density of the lithium cobaltate material, thereby increasing the capacity per unit volume, is another way to increase the energy density of a lithium cobaltate battery.
Lithium cobaltate is the earliest commercialized lithium ion battery anode material and is widely applied to the battery fields of mobile phones, digital codes and the like. With the continuous expansion of the application range, the requirements of lithium ion batteries using lithium cobaltate as the anode material are continuously updated. In the fields of vehicle models, model airplanes, ship models, electronic cigarettes, electric automobiles and the like, which are emerging at present, lithium ion batteries using lithium cobaltate as a positive electrode material are also used as power sources. These commercial products require continuous large current charging and discharging to meet their use requirements, and therefore, in these new application fields, there is also a higher demand for rate capability of lithium cobaltate.
The inventor applies for the invention of CN 109326781A relating to the high-voltage lithium cobalt oxide cathode material, the compaction density of the high-voltage lithium cobalt oxide product can reach 4.1g/cm3～4.15g/cm3However, the rate performance of the product still needs to be improved, for example, the rate performance of 1C/0.2C in the embodiment 1 and the embodiment 2 of the invention is 95.25-95.44%, and the rate performance can not meet the requirement of the rate type product on large-current charging and discharging. In addition, in the invention of 'a preparation method of a high-rate, high-compaction and high-voltage lithium cobaltate cathode material' which is applied by the inventor, although the rate performance of the lithium cobaltate cathode material 20C/0.2C is more than or equal to 97.0 percent and the requirement of rate type products on large-current charging and discharging is completely met, the compaction density of the product of the invention can reach 3.7g/cm3～3.95g/cm3Higher levels of (a) and higher volumetric energy density requirements for batteries require higher compaction densities of the lithium cobaltate material. The high-compaction high-rate high-voltage lithium cobalt oxide cathode material prepared by the invention makes full use of the advantages of large-particle-size and small-particle-size materials, and carries out grading on large and small particles according to a certain proportion to improve the compaction density of the material, wherein the compaction density of the material can reach 3.96g/cm3～4.1g/cm3To further increase the volumetric energy density; meanwhile, the large particles are in single crystal shapes, and the small particles are in single crystal-like shapes, so that the advantages of different shapes are fully exerted, and the high-voltage material which is higher in compaction and has the advantages of multiplying power, first coulombic efficiency, capacity and cycle performance is prepared.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of a high-compaction high-rate high-voltage lithium cobalt oxide positive material, which has the advantages of simple and easily-controlled process, low production cost, environmental friendliness, high production efficiency and excellent product performance.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a preparation method of the high-compaction high-rate high-voltage lithium cobalt oxide cathode material, which comprises the following steps of:
(1) preparing a large-particle-size lithium cobalt oxide material A: mixing materials by adopting a solid-phase mixing method, then carrying out primary sintering, carrying out coarse crushing, and carrying out crushing and grading by adopting a fluidized bed jet milling and grading integrated machine to prepare a material A with D50 of 11.1-15.0 mu M, wherein the material A is a lithium cobaltate material co-doped with M and M'; the shape of the lithium cobaltate material is a single crystal;
(2) preparing a small-particle-size lithium cobaltate material B: mixing materials by adopting a solid-phase mixing method, then carrying out primary sintering, carrying out coarse crushing, and carrying out crushing and grading by adopting a fluidized bed jet milling and grading integrated machine to prepare a material B with D50 of 3.0-5.0 mu M, wherein the material B is a lithium cobaltate material co-doped with M and M', and the shape of the lithium cobaltate material is similar to a single crystal;
(3) preparing a large-particle mixed material C: mixing the material A and the material B according to a certain proportion to obtain a mixed material C;
(4) secondary batching and mixing: uniformly mixing the mixed material C and the coating to obtain a secondary mixed material;
(5) and (3) secondary sintering: and (4) carrying out secondary sintering on the secondary mixture obtained in the step (4) in air, and carrying out coarse crushing and dissociation on the obtained blocky secondary sintered material to obtain the material.
The doping element M is selected from one or more of Al, Ti and Mg. The introduction of doping elements of aluminum, titanium and magnesium ions can improve the structure of the layered anode material, reduce the preparation difficulty, improve the conductivity and the structural stability of the anode material, improve the rate capability and the cycle life of the anode material.
The doping element M' is selected from Pr and Ce. On one hand, most elements Pr and Ce are added during primary sintering to dope and replace Co3+Part of the lithium ion battery forms a large-aperture ion channel, so that the lithium ion conduction is promoted, and the charge rate performance and the discharge capacity of the lithium battery are remarkably improved; on the other handSmall amounts of Pr and Ce do not enter the crystal lattice of lithium cobaltate, but form a surface coating layer. In general, in the process of preparing lithium cobaltate, doping is finished in the primary sintering process, and cladding is finished in the secondary sintering process, but the invention selects Pr and Ce to be added in the primary sintering process, thereby not only playing the role of doping, but also playing the role of surface cladding, and playing the role of double protection on lithium cobaltate together with other cladding substances added in the secondary sintering process.
Preferably, step (1) comprises: the preparation method comprises the steps of mixing a cobalt source with the grain diameter D50 of 4.1-6.0 microns, a lithium source, a compound containing a doping element M and a compound containing a doping element M' according to a certain proportion, mixing by using a coulter type mixer to obtain a primary mixture, sintering in an air atmosphere for the first time, coarsely crushing the sintered material, and crushing and grading by using a fluidized bed crushing and grading integrated machine. The amount of the conventional doping element M is 0.01-10 wt% of the weight of the secondary sintering product, and the doping amount of the unconventional doping element M' is 0.005-3 wt% of the weight of the secondary sintering product; the molar ratio n (Li) of the lithium element in the lithium source to the cobalt element in the cobalt source is 1.1-0.9: 1; primary sintering conditions are as follows: the ventilation amount is 10 to 20m3Performing primary sintering in air of/h, wherein the sintering main temperature of the primary sintering is controlled to be 960-1160 ℃, and the sintering time of a main temperature zone is 6-10 hours; the technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of the grinding gas is 0.54-0.57 MPa, the frequency of a grading motor is 36-38 Hz, the frequency of a feeding motor is 10-11 Hz, and the pressure of a grinding body is-0.5-1.0 KPa.
Preferably, step (2) comprises: the preparation method comprises the steps of mixing a cobalt source with the grain diameter D50 of 3.0-4.0 mu M, a lithium source, a compound containing a doping element M and a compound containing a doping element M' according to a certain proportion, mixing by using a coulter type mixer to obtain a primary mixture, sintering in an air atmosphere for the first time, coarsely crushing the sintered material, and crushing and grading by using a fluidized bed crushing and grading integrated machine. The amount of the conventional doping element M is 0.01-10 wt% of the weight of the secondary sintering product, and the doping amount of the doping element M' with large unconventional ionic radiusIs 0.005-3 wt% of the weight of the secondary sintering product; the molar ratio n (Li) of the lithium element in the lithium source to the cobalt element in the cobalt source is 1.1-0.9: 1; the primary sintering conditions are as follows: the ventilation amount is 10 to 20m3Performing primary sintering in air at the temperature of 900-1000 ℃, wherein the sintering time of a primary temperature zone is 6-10 hours; the technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of the grinding gas is 0.50-0.53 MPa, the frequency of a grading motor is 34-36 Hz, the frequency of a feeding motor is 9-10 Hz, and the pressure of a grinding body is-2.0-2.5 KPa.
Preferably, in the step (3), the material A and the material B are graded according to the mass ratio of 4: 1-1: 1, and are mixed by a coulter mixer.
Preferably, in step (4), the coating comprises Co (OH)2And Y2O3；Co(OH)20.5 to 4.5wt% of the weight of the mixed material C, and Y2O3Wherein Y is 0.05-0.4 wt% of the weight of the mixed material C; and mixing the coating and the mixed material C by adopting a high-speed mixer. After heat treatment, the coating Co (OH)2With excess Li on the surface+The reaction forms active lithium cobaltate which can reduce the activity of the surface of the lithium cobaltate cathode material, and part of Co (OH)2After heat treatment, a uniform coating layer is formed on the surface of the particle, and a coating object Y2O3With surface-rich Li in doped lithium cobaltate+Reacting to generate uniform coating LiYO2The coating layer has high chemical diffusion coefficient and structural stability, and is favorable for rate capability and high voltage performance of products.
Preferably, in the step (5), the specific operation of the secondary sintering process includes: the ventilation amount is 2 to 9m3Heating the secondary mixture to 900-950 ℃ at a heating rate of 2-4 ℃/min in air, keeping the temperature for 6-10 hours, then cooling to 775-825 ℃ at a cooling rate of 2-4 ℃/min, keeping the temperature for 1-3 hours, then reducing to room temperature at a rate of 2-4 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by a jaw crusher and a counter roll machine,and dissociating by an ACM dissociating mill to obtain the high-compaction high-rate high-voltage lithium cobalt oxide cathode material.
The particle size D50 of the lithium cobaltate positive electrode material prepared by the method is 6.0-14.0 mu m, and the numerical values of D0 are all larger than 1.4 mu m and far larger than 0.5 mu m; the compacted density is 3.96g/cm3～4.1g/cm3(ii) a The specific surface area is 0.20 to 0.50m2The discharge capacity of 0.2C of the full battery assembled by the obtained cathode material is higher than 193.2mAh/g in a voltage test range of 3.0V-4.45V, the capacity retention rate of 500-cycle under 1C charge-discharge conditions is not lower than 97.0%, and the rate performance of 20C/0.2C is higher than 96.4%.
According to the invention, two materials A, B with different grain sizes are graded and mixed to obtain a material C, and then the material C is subjected to secondary sintering and coating. Because the particle sizes of the materials contained in the material C are different, in order to realize that the coating can be tightly coated on the surfaces of the base materials with different particle sizes, the temperature is increased and decreased at the speed of 2-4 ℃/min in the secondary sintering process, and meanwhile, the temperature is maintained for 1-3 hours at 775-825 ℃ in the temperature reduction process, so that the base materials with different particle sizes can be promoted to react with the coating material on the surface, and the coating can absorb primary particles to generate different stresses; meanwhile, the coating material is tightly attached to the surfaces of the base materials with different particle sizes through high-temperature atomic diffusion, so that the falling-off of the coating material caused by the expansion/contraction of the volumes of the base materials with different particle sizes in the electrochemical circulation process is avoided, the composite compound in the coating material is connected with the base materials with different particle sizes through chemical bonds, and the bonding strength between the coating structure and the base materials with different particle sizes is strengthened.
In the above preparation method, preferably, the cobalt source in step (1) and step (2) mainly includes one or more of cobalt carbonate, cobaltosic oxide, cobalt oxyhydroxide, cobaltous oxide, cobaltous hydroxide, cobalt chloride, and cobalt oxalate. The cobalt source particle size D50 of the lithium cobaltate material A with the large particle size prepared by the method is 4.1-6.0 mu m, and the lithium cobaltate material A is a conventional and universal raw material in the industry, and the preparation process is mature. However, the cobalt source for preparing the small-particle-size lithium cobaltate material B has the particle size D50 of 3.0-4.0 μm, and the difficulty of the preparation process is increased due to the small particle size of the raw material, which mainly shows that the difficulty is increased in the aspects of crystallization control, sphericity control, filtration, drying and the like.
The D50 of the small-particle-size lithium cobalt oxide material B is 3.0-5.0 mu m, if the material B adopts single secondary mixing and secondary sintering, due to small particle size and poor fluidity, if the secondary sintering material treatment also adopts a fluidized bed type airflow crushing and grading integrated machine for crushing and grading, the material is easy to block in production, and the control difficulty is high. Therefore, the invention adopts the method that the large-particle-size lithium cobalt oxide material A and the small-particle-size lithium cobalt oxide material B are graded to obtain the material C, and the material C is subjected to secondary blending and secondary sintering and then is dissociated by an ACM dissociation mill, so that the problem of difficult processing of the secondary sintering material of the small-particle-size material can be avoided. The technical parameters of the ACM dissociation mill are as follows: the dissociation frequency is 63-67 Hz, the grading motor frequency is 58-62 Hz, the feeding motor frequency is 33-37 Hz, and the induced air frequency is 48-52 Hz; the grain size requirement of the secondary sintering dissociation material is as follows: d0 is not less than 0.5 μm, D50 is 6.0 μm to 14.0 μm, preferably D0 is not less than 1.0 μm, and D50 is 8.0 μm to 12.0 μm.
The invention adopts the process route of grading the large and small particles and then carrying out secondary sintering coating, and has obvious advantages compared with the process route of grading the large and small particles after respectively carrying out secondary sintering coating. The reason is that after the large and small particles are mixed, the secondary burdening and mixing are carried out, the coating and the graded material are uniformly mixed, and then the large and small particles have a chemical process of 'fusion' in the high-temperature treatment process of secondary sintering, so that the gaps among the large and small particles are reduced, the bulk density of the mixed material is improved, and the improvement of the material compaction density is facilitated. And the large and small particles are respectively subjected to secondary sintering coating and then are graded, and because the large and small particles are only mechanically and physically mixed together, certain gaps exist among the large and small particles, which is not beneficial to improving the compacted density of the material.
In the invention, the fluidized bed type airflow crushing and grading integrated machine is adopted to crush and grade in the step (1) and the step (2), and the superfine powder generated in the process is collected by the pulse dust cleaning and collecting device and does not enter the process of secondary proportioning and mixing, thereby being beneficial to controlling the fine powder particles in the finished product from the source. In addition, in the step (5), the ACM dissociation mill is adopted for dissociation, products with different grain diameters are obtained by adjusting the rotating speed of the grading wheel and the air volume of the fan, and the device has the advantages of high yield, reliable performance, stable operation and convenience in maintenance. The basic working principle of the ACM dissociation mill is that a quantitative feeding system conveys materials into a dissociation cavity, the materials entering the dissociation cavity collide between a movable piece and a fixed piece which rotate at high speed, and the materials are instantaneously thinned under the impact and the shearing of high-pressure airflow. The dissociated materials enter the pre-grading area under the drive of the airflow to carry out self-shunting grading, a part of the materials enter the forced grading area through the fairing to carry out grading, the qualified materials after grading are collected through the cyclone and the dust remover, and the unqualified materials return to the dissociation area again to be dissociated. Because the equipment comprises the built-in grading device, excessive dissociation can not be generated on the materials, and the generation of the ultrafine powder in the process can be avoided.
Therefore, the fluidized bed type airflow crushing and grading integrated machine is adopted for crushing and grading in the steps (1) and (2), the ACM dissociation mill is adopted for dissociation in the step (5), and double protection is adopted to strictly control the content of fine powder with the particle size of less than 0.5 micrometer in the product while ensuring that the D50 of the lithium cobaltate positive electrode material meets the requirement of 6.0-14.0 micrometers.
Generally, in the design of the lithium battery positive electrode material, three performances of high multiplying power, high compaction and high voltage are realized at the same time, which has extremely high difficulty, and because the preparation technology of the material realizes certain performances, other performances are influenced. For example, in the industry, to improve the rate capability of a material, lithium cobaltate with a polycrystalline morphology with small primary particles is generally prepared; however, the material with the polycrystalline morphology is easy to cause electrochemical side reaction between the material and electrolyte under high voltage due to the large specific surface, and the exposed fresh internal surface and the electrolyte are crushed, pulverized and separated in the circulating processThe reaction continues to generate other phases, which cause the deterioration of electrical properties and affect the high voltage performance; meanwhile, aggregate particles with polycrystalline morphology are easy to crush when being used for manufacturing batteries, so that the compaction density is generally 3.6g/cm3The following is a requirement for high compaction.
The large particles are in single crystal shape, the small particles are in single crystal-like shape, and the advantages of different shapes can be fully exerted. In addition, the invention adopts the technology of grading the large and small particles to prepare two lithium cobaltate materials with different particle sizes, namely a large-particle-size lithium cobaltate material A (D50 is 11.1-15.0 mu m) and a small-particle-size lithium cobaltate material B (D50 is 3.0-5.0 mu m), and A, B, and the two materials are graded according to a certain proportion. This is mainly because a single large-particle-size lithium cobalt oxide material and a single small-particle-size lithium cobalt oxide material each have advantages and disadvantages. The single lithium cobaltate material with large particle size has the advantages that the particle size is large, the compaction density is improved, meanwhile, the specific surface area is small, the side reaction with the electrolyte is reduced, the improvement of the high-voltage cycle performance is facilitated, but the high-rate performance is reduced due to the large particle size, and the discharge efficiency is reduced; the single small-particle-size lithium cobalt oxide material has the advantages that the particle size is small, the compaction density is reduced, the high-rate performance is improved, the processing performance is poor, and the safety performance and the cycle performance are reduced. The high-compaction high-rate high-voltage lithium cobalt oxide cathode material prepared by the invention makes full use of the advantages of large-particle-size materials and small-particle-size materials, and carries out grading on large and small particles according to a certain proportion to improve the compaction density of the material, thereby increasing the volume energy density of the material.
Compared with the prior art, the invention has the following beneficial effects:
1. the compacted density of the lithium cobaltate cathode material prepared by the method can reach 3.96g/cm3～4.1g/cm3The level of the zinc oxide, the chemical components and the phase components are uniform, the granularity and the appearance are easy to control, the electrochemical performance is excellent, and the zinc oxide has the characteristics of high multiplying power, high compaction and high voltage.
2. The preparation method has low requirement on equipment, is simple and convenient to operate, has high production efficiency, simple synthesis flow and easy control of process conditions, and can obviously improve the consistency of products, thereby ensuring the stable quality of products in different batches.
In conclusion, the preparation method has the characteristics of simple and easily-controlled process, high efficiency and the like, and the product has uniform components, stable quality and excellent physicochemical and electrical properties.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is an SEM image of a high-compaction-magnification-type high-voltage lithium cobaltate cathode material prepared by the method of example 1 of the present invention.
Fig. 2 is an SEM image of the high-compaction-magnification-type high-voltage lithium cobaltate cathode material prepared by the method of example 2 of the present invention.
Fig. 3 is an SEM image of the high-compaction-magnification-type high-voltage lithium cobalt oxide positive electrode material prepared by the method of example 3 of the present invention.
Fig. 4 is an SEM image of the high-compaction-magnification-type high-voltage lithium cobaltate cathode material prepared by the method of example 4 of the present invention.
Fig. 5 is an SEM image of the high-compaction high-voltage lithium cobaltate positive electrode material prepared by the method of comparative example 1.
Fig. 6 is an SEM image of the rate-type high-voltage lithium cobaltate positive electrode material prepared by the method of comparative example 3.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
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:
the high-compaction rate type high-voltage lithium cobaltate cathode material has the D50 of 9.01 mu m and the specific surface area of 0.36m2(ii)/g, compacted density 4.02g/cm3. The SEM image of the material of this example is shown in FIG. 1. As can be seen from figure 1, the lithium cobaltate material with large particle size and small particle size is graded, the large particle size is in a single crystal shape, the small particle size is in a single crystal-like shape, and meanwhile, the small particle size material fully fills gaps among the large particle size material in a tiled state, so that 4.02g/cm is realized when a full battery is manufactured3High compaction density of (2). Tests show that the material has a 0.2C discharge capacity of 194.2mAh/g, a capacity retention rate of 97.3% after 500-week circulation under 1C charge-discharge conditions and a rate capability of 97.1% after 20C/0.2C in a test range of 25 ℃ and 3.0V-4.45V.
The preparation method of the high-compaction rate type high-voltage lithium cobalt oxide cathode material in the embodiment includes the following steps:
(1) preparing a large-particle-size lithium cobalt oxide material A: d50 of A is 11.5 μm, and the preparation method adopted is as follows: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 5.0. mu.m2O3MgO and Pr2O3And (2) proportioning, and then mixing by using a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium hydroxide to cobalt element in cobalt carbonate is n (Li): (n) (Co) =1.07: 1, the addition amount of Al is 0.2wt% of the weight of the secondary sintering product, the addition amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the addition amount of Pr is 0.1wt% of the weight of the secondary sintering product. Placing the uniformly mixed materials in a ventilation volume of 15m3Performing primary sintering in air at the main sintering temperature of 1000 ℃ for 8 hours in a main temperature region, coarsely crushing the primary sintered material by a jaw crusher and a double-roller crusher, and performing powder grinding by a fluidized bed type jet milling and grading integrated machineCrushing and grading to obtain the required lithium cobaltate semi-finished product A. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.55MPa, the frequency of a grading motor is 37Hz, the frequency of a feeding motor is 10Hz, and the pressure of a grinding body is-0.8 KPa;
(2) preparing a small-particle-size lithium cobaltate material B: d50 of B was 3.5 μm, and the preparation method used was: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 3.4 μm2O3MgO and Pr2O3Proportioning, and then mixing by adopting a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium hydroxide to cobalt element in cobalt carbonate is n (Li): (n) (Co) =1.07: 1, the adding amount of Al is 0.2wt% of the weight of the secondary sintering product, the adding amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the adding amount of Pr is 0.1wt% of the weight of the secondary sintering product; placing the uniformly mixed materials in a ventilation volume of 15m3And (2) performing primary sintering in air, controlling the sintering main temperature at 950 ℃, controlling the sintering time of a main temperature zone to be 8 hours, coarsely crushing the materials subjected to primary sintering by a jaw crusher and a double-roller machine, and crushing and grading by a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product B. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.52MPa, the frequency of a grading motor is 35Hz, the frequency of a feeding motor is 9Hz, and the pressure of a grinding body is-2.2 KPa;
(3) preparing a large-particle mixed material C: and (3) grading the A, B materials obtained in the steps (1) and (2) according to a certain proportion, mixing by adopting a coulter type mixer, wherein the mass ratio of A to B is 4:1, and uniformly mixing to obtain a material C.
(4) Secondary batching and mixing: mixing the material C obtained in the step (3) and a coating according to a certain proportion, and then mixing the material C and the coating by a high-speed mixer to obtain a secondary mixture, wherein the coating is Co (OH)2And Y2O3Wherein Co (OH)24.5wt% of the weight of the primary sintered product, Y2O3Y in (3) is 0.2wt% of the weight of the primary sintered product.
(5) Two timesAnd (3) sintering: placing the secondary mixture obtained in the step (4) in a ventilation volume of 5m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 950 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 8 hours, then cooling to 800 ℃ at a cooling rate of 3 ℃/min, keeping the temperature for 2 hours, then cooling to room temperature at a rate of 3 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by using a jaw crusher and a double-roll crusher, and then dissociating by using an ACM (acid-activated mechanical grinding) to obtain the high-compaction high-magnification type high-voltage lithium cobalt oxide cathode material. The dissociation process parameters are as follows: the dissociation frequency is 65Hz, the grading motor frequency is 60Hz, the feeding motor frequency is 35Hz, and the induced air frequency is 50 Hz.
Example 2:
the high-compaction rate type high-voltage lithium cobaltate cathode material has the D50 of 10.44 mu m and the specific surface area of 0.35m2(ii)/g, compacted density 4.05g/cm3. The SEM image of the material of this example is shown in FIG. 2. As can be seen from figure 2, the lithium cobaltate material with large particle size and small particle size is graded, the large particle size is in a single crystal shape, the small particle size is in a single crystal-like shape, and meanwhile, the small particle size material fully fills gaps among the large particle size material in a tiled state, so that 4.05g/cm is realized when the full-electric cell is manufactured3High compaction density of (2). Tests show that the material has a 0.2C discharge capacity of 194.0mAh/g, a capacity retention rate of 97.6% after 500-week circulation under 1C charge-discharge conditions and a rate capability of 97.0% at 20C/0.2C within the test range of 25 ℃ and 3.0V-4.45V.
The preparation method of the high-compaction rate type high-voltage lithium cobalt oxide cathode material of the embodiment comprises the following steps:
(1) preparing a large-particle-size lithium cobalt oxide material A: d50 of A is 12.9 μm, and the preparation method adopted is as follows: tricobalt tetraoxide with a particle size D50 of 4.5 μm, lithium carbonate and TiO2、Mg(OH)2And CeO2Proportioning, mixing by a colter mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium carbonate to cobalt element in cobaltosic oxide is n (Li): (n) (Co) =1.05: 1, the addition amount of Ti is 0.1wt% of the weight of the secondary sintering product, and the addition amount of Mg is 0.1wt% of the weight of the secondary sintering productThe weight of the Ce is 0.15wt% of that of the secondary sintering product, and the addition amount of the Ce is 0.05 wt% of that of the secondary sintering product; placing the uniformly mixed materials in a ventilation volume of 18m3And performing primary sintering in air, controlling the sintering main temperature at 1020 ℃, controlling the sintering time of a main temperature zone to be 8 hours, roughly crushing the materials subjected to primary sintering by using a jaw crusher and a double-roll crusher, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product A. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.57MPa, the frequency of a grading motor is 37Hz, the frequency of a feeding motor is 11Hz, and the pressure of a grinding body is-1.0 KPa;
(2) preparing a small-particle-size lithium cobaltate material B: d50 of B was 3.2 μm, and the preparation method used was: tricobalt tetraoxide with a particle size D50 of 3.1 μm, lithium carbonate and TiO2、Mg(OH)2And CeO2Proportioning, and then mixing by adopting a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium carbonate to cobalt element in cobaltosic oxide is n (Li): n (Co) =1.05: 1, the addition amount of Ti is 0.1wt% of the weight of the secondary sintering product, the addition amount of Mg is 0.15wt% of the weight of the secondary sintering product, and the addition amount of Ce is 0.05 wt% of the weight of the secondary sintering product; placing the uniformly mixed materials in a ventilation volume of 12m3And (2) performing primary sintering in air, controlling the sintering main temperature at 920 ℃, controlling the sintering time of a main temperature zone to be 10 hours, roughly crushing the materials subjected to primary sintering by using a jaw crusher and a double-roll crusher, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product B. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.53MPa, the frequency of a grading motor is 36Hz, the frequency of a feeding motor is 10Hz, and the pressure of a grinding body is-2.0 KPa;
(3) preparing a large-particle mixed material C: blending the A, B materials obtained in the steps (1) and (2) according to a certain proportion, and mixing by using a coulter mixer, wherein A: the mass ratio of B is 4:1, and the material C is obtained after uniform mixing.
(4) Secondary batching and mixing: will be described in detail(3) Mixing the obtained material C and a coating material according to a certain proportion, and then mixing the mixture by a high-speed mixer to obtain a secondary mixture, wherein the coating material is Co (OH)2And Y2O3Wherein Co (OH)23.5wt% of the weight of the primary sintered product, Y2O3Y in (1) is 0.1wt% of the weight of the primary sintered product.
(5) And (3) secondary sintering: placing the secondary mixture obtained in the step (4) in a ventilation volume of 5m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 920 ℃ at the heating rate of 4 ℃/min, keeping the temperature for 10 hours, then cooling to 820 ℃ at the cooling rate of 4 ℃/min, keeping the temperature for 3 hours, then cooling to room temperature at the rate of 4 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by using a jaw crusher and a double-roll crusher, and then dissociating by using an ACM (activated carbon M) dissociating mill to obtain the high-compaction high-magnification type high-voltage lithium cobalt oxide cathode material. The dissociation process parameters are as follows: the dissociation frequency is 67Hz, the grading motor frequency is 62Hz, the feeding motor frequency is 37Hz, and the induced air frequency is 52 Hz.
Example 3:
the high-compaction multiplying power type high-voltage lithium cobaltate cathode material has the D50 of 9.21 mu m and the specific surface area of 0.45m2(ii)/g, compacted density 4.07g/cm3. The SEM image of the material of this example is shown in FIG. 3. As can be seen from FIG. 3, the lithium cobaltate material with large particle size and small particle size is graded, the large particle size is in a single crystal shape, the small particle size is in a single crystal-like shape, and meanwhile, the small particle size material fully fills gaps among the large particle size material in a tiled state, so that 4.07g/cm is realized during full battery manufacturing3High compaction density of (2). Tests show that the material has 0.2C discharge capacity of 194.6mAh/g, capacity retention rate of 500-week circulation under 1C charge-discharge conditions of 97.0% and 20C/0.2C rate performance of 97.5% in the test ranges of 25 ℃ and 3.0V-4.45V.
The preparation method of the high-compaction rate type high-voltage lithium cobalt oxide cathode material in the embodiment includes the following steps:
(1) preparing a large-particle-size lithium cobalt oxide material A: a. theD50 of (2) was 14.5 μm, and the preparation method used was: cobalt oxyhydroxide, lithium nitrate and TiO with a particle size D50 of 5.0 mu m2MgO and Pr2O3And (2) batching, and then mixing by adopting a colter type mixer to obtain a primary mixed material, wherein the molar ratio of lithium element in lithium nitrate to cobalt element in cobalt oxyhydroxide is n (Li): (n) (Co) =1.03: 1, the addition amount of Ti is 0.25wt% of the weight of the secondary sintering product, the addition amount of Mg is 0.15wt% of the weight of the secondary sintering product, and the addition amount of Pr is 0.15wt% of the weight of the secondary sintering product. Placing the uniformly mixed materials in a ventilation volume of 18m3And performing primary sintering in air, controlling the sintering main temperature at 1040 ℃, controlling the sintering time in a main temperature zone to be 10 hours, coarsely crushing the materials subjected to primary sintering by using a jaw crusher and a double-roll crusher, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product A. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.56MPa, the frequency of a grading motor is 36Hz, the frequency of a feeding motor is 11Hz, and the pressure of a grinding body is-0.8 KPa.
(2) Preparing a small-particle-size lithium cobaltate material B: d50 of B was 3.7 μm, and the preparation method used was: cobalt oxyhydroxide, lithium nitrate and TiO with a particle size D50 of 3.5 mu m2MgO and Pr2O3And (2) batching, and then mixing by adopting a colter type mixer to obtain a primary mixed material, wherein the molar ratio of lithium element in lithium nitrate to cobalt element in cobalt oxyhydroxide is n (Li): (n) (Co) =1.03: 1, the addition amount of Ti is 0.25wt% of the weight of the secondary sintering product, the addition amount of Mg is 0.15wt% of the weight of the secondary sintering product, and the addition amount of Pr is 0.15wt% of the weight of the secondary sintering product. Placing the uniformly mixed materials in a ventilation volume of 12m3And (2) performing primary sintering in air, controlling the sintering main temperature to be 965 ℃, controlling the sintering time of a main temperature zone to be 10 hours, performing coarse crushing on the materials subjected to primary sintering by using a jaw crusher and a pair roller, and performing crushing and grading by using a fluidized bed type jet milling and grading integrated machine to obtain the required lithium cobaltate semi-finished product B. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of the grinding gas is 0.51MPa, and the frequency of the grading motor is 35Hz, the frequency of the feeding motor is 9Hz, and the pressure of the grinding body is-2.4 KPa.
(3) Preparing a large-particle mixed material C: and (3) grading the obtained lithium cobaltate semi-finished product A, B according to a proportion, and mixing by using a plough blade type mixer, wherein A: the mass ratio of B is 1:1, and the material C is obtained after uniform mixing.
(4) Secondary batching and mixing: mixing the mixed material C and a coating according to a certain proportion, and then mixing the mixed material C and the coating by a high-speed mixer to obtain a secondary mixed material, wherein the coating is Co (OH)2And Y2O3Wherein Co (OH)23.5wt% of the weight of the primary sintered product, Y2O3Y in (3) is 0.15wt% of the weight of the primary sintered product.
(5) And (3) secondary sintering: placing the secondary mixture obtained in the step (4) in a ventilation capacity of 8m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 940 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 8 hours, then cooling to 810 ℃ at a cooling rate of 3 ℃/min, keeping the temperature for 2 hours, then cooling to room temperature at a rate of 3 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by using a jaw crusher and a double-roll crusher, and then dissociating by using an ACM (activated carbon M) dissociating mill to obtain the high-compaction high-magnification type high-voltage lithium cobalt oxide cathode material. The dissociation process parameters are as follows: the dissociation frequency was 64Hz, the classification motor frequency was 59Hz, the feeding motor frequency was 34Hz, and the induced air frequency was 49 Hz.
Example 4:
the high-compaction rate type high-voltage lithium cobaltate cathode material has the D50 of 8.31 mu m and the specific surface area of 0.42m2(ii)/g, compacted density 4.01g/cm3. The SEM image of the material of this example is shown in FIG. 4. As can be seen from FIG. 4, the lithium cobaltate material with large particle size and small particle size is graded, the large particle size is in a single crystal shape, the small particle size is in a single crystal-like shape, and meanwhile, the small particle size material fully fills gaps among the large particle size material in a tiled state, so that 4.01g/cm is realized during full battery manufacturing3High compaction density of (2). The material is tested to be in the test range of 25 ℃ and 3.0V-4.45V,the 0.2C discharge capacity is 194.8mAh/g, the capacity retention rate of 500-week circulation under the 1C charge-discharge condition is 97.0%, and the rate performance of 20C/0.2C is 97.9%.
The preparation method of the high-compaction rate type high-voltage lithium cobalt oxide cathode material in the embodiment includes the following steps:
(1) preparing a large-particle-size lithium cobalt oxide material A: d50 of A is 12.0 μm, and the preparation method adopted is as follows: cobalt chloride, lithium oxalate and Al with the particle size D50 of 5.8 mu m2O3、TiO2、Mg(OH)2And CeO2Proportioning, and then mixing by adopting a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium oxalate to cobalt element in cobalt chloride is n (Li): (n) (Co) =1.09: 1, the adding amount of Al is 0.1wt% of the weight of the secondary sintering product, the adding amount of Ti is 0.1wt% of the weight of the secondary sintering product, the adding amount of Mg is 0.15wt% of the weight of the secondary sintering product, and the adding amount of Ce is 0.15wt% of the weight of the secondary sintering product; placing the uniformly mixed materials in a ventilation volume of 18m3And performing primary sintering in air at 980 ℃ for 10 hours in a main temperature area, coarsely crushing the materials subjected to primary sintering by using a jaw crusher and a pair roller, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product A. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.55MPa, the frequency of a grading motor is 37Hz, the frequency of a feeding motor is 11Hz, and the pressure of a grinding body is-0.6 KPa.
(2) Preparing a small-particle-size lithium cobaltate material B: d50 of B was 3.4 μm, and the preparation method used was: cobalt chloride, lithium oxalate and Al with the particle size D50 of 3.2 mu m2O3、TiO2、Mg(OH)2And CeO2Proportioning, mixing by a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium oxalate to cobalt element in cobalt chloride is n (Li): (n) (Co) =1.09: 1, the adding amount of Al is 0.1wt% of the weight of the secondary sintering product, the adding amount of Ti is 0.1wt% of the weight of the secondary sintering product, the adding amount of Mg is 0.15wt% of the weight of the secondary sintering product, and the adding amount of Ce is 0.15wt% of the weight of the secondary sintering product0.15wt% of the weight of the product; placing the uniformly mixed materials in a ventilation volume of 10m3And performing primary sintering in air at the sintering main temperature of 920 ℃, wherein the sintering time in a main temperature zone is 8 hours, coarsely crushing the materials subjected to primary sintering by using a jaw crusher and a double-roll crusher, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product B. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.52MPa, the frequency of a grading motor is 36Hz, the frequency of a feeding motor is 10Hz, and the pressure of a grinding body is-2.2 KPa.
(3) Preparing a large-particle mixed material C: blending the A, B materials obtained in the steps (1) and (2) according to a certain proportion, and mixing by using a coulter mixer, wherein A: the mass ratio of B is 1:1, and the material C is obtained after uniform mixing.
(4) Secondary batching and mixing: mixing the material C obtained in the step (3) and a coating according to a certain proportion, and then mixing the material C and the coating by a high-speed mixer to obtain a secondary mixture, wherein the coating is Co (OH)2And Y2O3Wherein Co (OH)23.8wt% of the weight of the primary sintered product, Y2O3Y in (3) is 0.15wt% of the weight of the primary sintered product.
(5) And (3) secondary sintering: placing the secondary mixture obtained in the step (4) in a ventilation capacity of 8m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 920 ℃ at the heating rate of 4 ℃/min, keeping the temperature for 7 hours, then cooling to 790 ℃ at the cooling rate of 4 ℃/min, keeping the temperature for 3 hours, then cooling to room temperature at the rate of 4 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by using a jaw crusher and a double-roll crusher, and then dissociating by using an ACM (activated carbon M) dissociating mill to obtain the high-compaction high-magnification type high-voltage lithium cobalt oxide cathode material. The dissociation process parameters are as follows: the dissociation frequency is 66Hz, the grading motor frequency is 62Hz, the feeding motor frequency is 36Hz, and the induced air frequency is 51 Hz.
As can be seen from examples 1-4, materials with similar physical properties and electrochemical properties can be prepared in different examples although the raw materials and process parameters used in the preparation process are changed.
Comparative example 1:
the high-compaction high-voltage lithium cobaltate cathode material has the D50 of 17.2 mu m and the specific surface area of 0.19m2(ii)/g, compacted density 4.17g/cm3. The SEM image of the material of this comparative example is shown in FIG. 5. As can be seen from FIG. 5, the lithium cobaltate material with large particle size and small particle size is graded, the large particle size is in a single crystal shape, the small particle size is in a single crystal-like shape, and meanwhile, the small particle size material fully fills gaps among the large particle size material in a tiled state, so that 4.17g/cm is realized during full battery manufacturing3High compaction density of (2). Tests show that the material has a 0.2C discharge capacity of 192.5mAh/g, a capacity retention rate of 97.8% after 500-week circulation under 1C charge-discharge conditions and a rate capability of 82.4% at 20C/0.2C within the test range of 25 ℃ and 3.0V-4.45V.
The preparation method of the high-compaction high-voltage lithium cobalt oxide positive electrode material of the comparative example comprises the following steps:
(1) preparing a large-particle-size lithium cobalt oxide material A: d50 of A was 19.5 μm, and the preparation method used was: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 5.0. mu.m2O3MgO and Pr2O3And (2) proportioning, and then mixing by using a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium hydroxide to cobalt element in cobalt carbonate is n (Li): (n) (Co) =1.07: 1, the addition amount of Al is 0.2wt% of the weight of the secondary sintering product, the addition amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the addition amount of Pr is 0.1wt% of the weight of the secondary sintering product. Placing the uniformly mixed materials in a ventilation volume of 15m3And performing primary sintering in air, controlling the sintering main temperature at 1180 ℃, controlling the sintering time of a main temperature zone to be 8 hours, roughly crushing the materials subjected to primary sintering by using a jaw crusher and a pair roller, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product A. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the grinding gas pressure is 0.58MPa, the frequency of a grading motor is 40Hz, the frequency of a feeding motor is 12Hz,the pressure of the grinding body is-1.0 KPa;
(2) preparing a small-particle-size lithium cobaltate material B: d50 of B was 3.5 μm, and the preparation method used was: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 3.3 μm2O3MgO and Pr2O3Proportioning, and then mixing by adopting a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium hydroxide to cobalt element in cobalt carbonate is n (Li): (n) (Co) =1.07: 1, the adding amount of Al is 0.2wt% of the weight of the secondary sintering product, the adding amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the adding amount of Pr is 0.1wt% of the weight of the secondary sintering product; placing the uniformly mixed materials in a ventilation volume of 15m3And (2) performing primary sintering in air, controlling the sintering main temperature at 950 ℃, controlling the sintering time of a main temperature zone to be 8 hours, coarsely crushing the materials subjected to primary sintering by a jaw crusher and a double-roller machine, and crushing and grading by a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product B. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.52MPa, the frequency of a grading motor is 35Hz, the frequency of a feeding motor is 9Hz, and the pressure of a grinding body is-2.2 KPa;
(3) preparing a large-particle mixed material C: and (3) grading the A, B materials obtained in the steps (1) and (2) according to a certain proportion, mixing by adopting a coulter type mixer, wherein the mass ratio of A to B is 4:1, and uniformly mixing to obtain a material C.
(4) Secondary batching and mixing: mixing the material C obtained in the step (3) and a coating according to a certain proportion, and then mixing the material C and the coating by a high-speed mixer to obtain a secondary mixture, wherein the coating is Co (OH)2And Y2O3Wherein Co (OH)24.5wt% of the weight of the primary sintered product, Y2O3Y in (3) is 0.2wt% of the weight of the primary sintered product.
(5) And (3) secondary sintering: placing the secondary mixture obtained in the step (4) in a ventilation volume of 5m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 950 ℃ at the heating rate of 3 ℃/min, and keeping the temperature for 8 hoursThen, the temperature is reduced to 800 ℃ at the cooling rate of 3 ℃/min, the heat preservation time is 2 hours, then the temperature is reduced to room temperature at the rate of 3 ℃/min, a blocky secondary sintering material is obtained, and after the secondary sintering material is roughly crushed by a jaw crusher and a counter roll machine, the secondary sintering material is dissociated by an ACM (acid-activated metal) dissociation mill, and the lithium cobaltate cathode material is obtained. The dissociation process parameters are as follows: the dissociation frequency is 68Hz, the grading motor frequency is 64Hz, the feeding motor frequency is 39Hz, and the induced air frequency is 50 Hz.
The main differences between the preparation processes of this comparative example and example 1 include the difference in the one-firing temperature and D50 of the large-particle-size lithium cobaltate material. The primary sintering temperature of the large-particle-size material in the comparative example 1 is increased to 1180 ℃ and is increased by 180 ℃ compared with that in the example 1; the large-particle-size material of comparative example 1 had a D50 of 19.5 μm, which was 8 μm larger than the D50 of the large-particle-size material of example 1. Although the small particle size lithium cobaltate material preparation process and the gradation ratio of the grade mixed material C are the same for the comparative example and example 1, the D50 of the comparative example product is 8.19 μm greater than the D50 of the example 1 product. The physical properties and electrochemical properties of the positive electrode material products of the comparative example and example 1 are compared as shown in Table 1.
TABLE 1 comparison of physical Properties and electrochemical Properties of the products of comparative example 1 and example 1 cathode materials
Figure 638448DEST_PATH_IMAGE001
As can be seen from the results in Table 1, since D50 in comparative example 1 was large and the specific surface area was small, the compacted density was advantageous and was 0.15 g/cm larger than that in example 13. However, the high rate performance is obviously reduced due to the larger particle size, the 20C/0.2C rate performance is 14.7% lower than that of the example 1, the discharge efficiency is reduced due to the larger particle size, and the 0.2C discharge capacity is reduced by 1.7 mAh/g. Since the rate performance of comparative example 1 is excessively lowered, it has not been suitable for the field of high rate. In fact, the grading ratio and the particle size of the product of comparative example 1 belong to the category of energy density type products in the industry, and the product is characterized by high compaction and high voltage performance, but cannot give consideration to high rate performance.
Comparative example 2:
the high-compaction multiplying power type high-voltage lithium cobaltate cathode material has the D50 of 9.07 mu m and the specific surface area of 0.28m2(ii)/g, compacted density of 3.90g/cm3. Tests show that the material has a 0.2C discharge capacity of 194.3mAh/g, a capacity retention rate of 97.8% after 500-week circulation under 1C charge-discharge conditions and a rate capability of 97.4% at 20C/0.2C within the test range of 25 ℃ and 3.0V-4.45V.
The preparation method of the high-compaction rate type high-voltage lithium cobalt oxide cathode material of the comparative example comprises the following steps:
(1) preparing a lithium cobaltate semi-finished product: the adopted preparation method comprises the following steps: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 5.0. mu.m2O3MgO and Pr2O3And (2) proportioning, and then mixing by using a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium hydroxide to cobalt element in cobalt carbonate is n (Li): (n) (Co) =1.07: 1, the addition amount of Al is 0.2wt% of the weight of the secondary sintering product, the addition amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the addition amount of Pr is 0.1wt% of the weight of the secondary sintering product. Placing the uniformly mixed materials in a ventilation volume of 15m3And performing primary sintering in air, controlling the sintering main temperature at 970 ℃, controlling the sintering time of a main temperature zone to be 8 hours, coarsely crushing the materials subjected to primary sintering by a jaw crusher and a double-roller machine, and crushing and grading by a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.54MPa, the frequency of a grading motor is 35Hz, the frequency of a feeding motor is 10Hz, and the pressure of a grinding body is-0.8 KPa;
(2) secondary batching and mixing: mixing the lithium cobaltate semi-finished product obtained in the step (1) and a coating according to a certain proportion, and then mixing the mixture by using a high-speed mixer to obtain a secondary mixture, wherein the coating is Co (OH)2And Y2O3Wherein Co (OH)24.5wt% of the weight of the primary sintered product, Y2O3Y in (3) is 0.2wt% of the weight of the primary sintered product.
(3) Second burningAnd (3) knot: placing the secondary mixture obtained in the step (3) in a ventilation volume of 5m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 950 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 8 hours, then cooling to 800 ℃ at a cooling rate of 3 ℃/min, keeping the temperature for 2 hours, then cooling to room temperature at a rate of 3 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by using a jaw crusher and a double-roll crusher, and then dissociating by using an ACM (acid-activated mechanical grinding) to obtain the lithium cobaltate cathode material. The dissociation process parameters are as follows: the dissociation frequency was 67Hz, the classification motor frequency was 62Hz, the feeding motor frequency was 36Hz, and the induced air frequency was 52 Hz.
The main difference between the preparation processes of the present comparative example and example 1 is that no grading process is used, but single-size particles are prepared. Comparative example 2 has a D50 of 9.07 μm, close to D50 of the product of example 1. The physical properties and electrochemical properties of the positive electrode material products of the comparative example and example 1 are compared as shown in Table 2.
TABLE 2 comparison of physical Properties and electrochemical Properties of the products of the positive electrode materials of comparative example 2 and example 1
Figure 991299DEST_PATH_IMAGE002
From the results of Table 2, it can be seen that since comparative example 2 does not employ a process of grading with a large-and-small-sized lithium cobaltate material but employs a process of making a single particle, although D50 of the comparative example 2 and the example 1 materials are close, since there is not sufficient filling of the gap with a small-sized lithium cobaltate material, the compacted density is significantly reduced, and is reduced by 0.12 g/cm compared to that of example 13This is a significant disadvantage of this approach.
Comparative example 3:
the multiplying-power type high-voltage lithium cobaltate positive electrode material of the comparative example has a D50 value of 3.56 μm and a specific surface area of 0.70m2(ii)/g, compacted density of 3.40g/cm3. SEM photographs of the materials of this comparative example are shown in FIG. 6. As can be seen from fig. 6, the material is a single-particle material, and the morphology thereof is a single-crystal-like morphology. Tested the materialIn the test range of 25 ℃ and 3.0V-4.45V, the 0.2C discharge capacity is 194.6mAh/g, the capacity retention rate of 500-week circulation under the 1C charge-discharge condition is 92.1%, and the rate performance of 20C/0.2C is 97.9%.
The preparation method of the rate type high-voltage lithium cobalt oxide cathode material of the comparative example comprises the following steps:
(1) preparing a lithium cobaltate semi-finished product: the D50 is 3.50 μm, and the preparation method comprises the following steps: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 3.30 μm2O3MgO and Pr2O3Proportioning, and then mixing by adopting a colter type mixer to obtain a primary mixture, wherein the molar ratio of lithium element in lithium hydroxide to cobalt element in cobalt carbonate is n (Li): (n) (Co) =1.07: 1, the adding amount of Al is 0.2wt% of the weight of the secondary sintering product, the adding amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the adding amount of Pr is 0.1wt% of the weight of the secondary sintering product; placing the uniformly mixed materials in a ventilation volume of 15m3And performing primary sintering in air, controlling the sintering main temperature at 950 ℃, controlling the sintering time of a main temperature zone at 8 hours, coarsely crushing the materials subjected to primary sintering by using a jaw crusher and a double-roll crusher, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.52MPa, the frequency of a grading motor is 35Hz, the frequency of a feeding motor is 9Hz, and the pressure of a grinding body is-2.2 KPa;
(2) secondary batching and mixing: mixing the lithium cobaltate semi-finished product obtained in the step (1) and a coating according to a certain proportion, and then mixing the mixture by using a high-speed mixer to obtain a secondary mixture, wherein the coating is Co (OH)2And Y2O3Wherein Co (OH)24.5wt% of the weight of the primary sintered product, Y2O3Y in (3) is 0.2wt% of the weight of the primary sintered product.
(3) And (3) secondary sintering: placing the secondary mixture obtained in the step (3) in a ventilation volume of 5m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to the temperature of 3 ℃/minAnd (3) keeping the temperature for 8 hours at 950 ℃, then cooling to 800 ℃ at the cooling rate of 3 ℃/minute, keeping the temperature for 2 hours, then cooling to room temperature at the rate of 3 ℃/minute to obtain a blocky secondary sintering material, coarsely crushing by using a jaw crusher and a pair roller, and then dissociating by using an ACM (aluminum chloride) dissociation mill to obtain the lithium cobaltate cathode material. The dissociation process parameters are as follows: the dissociation frequency is 60Hz, the grading motor frequency is 55Hz, the feeding motor frequency is 30Hz, and the induced air frequency is 50 Hz.
The main difference between the preparation processes of the present comparative example and example 1 is that no grading process is used, but a single particle is prepared. Comparative example 3 had a D50 of 3.56 μm, which was 5.45 μm less than D50 of example 1. The physical properties and electrochemical properties of the positive electrode material products of the comparative example and example 1 are compared as shown in Table 3.
TABLE 3 comparison of physical Properties and electrochemical Properties of the products of the positive electrode materials of comparative example 3 and example 1
Figure 867988DEST_PATH_IMAGE003
As can be seen from the results of Table 3, since comparative example 3 does not employ the process of grading lithium cobaltate materials with large and small particle diameters, but employs the process of making single particles, the product of comparative example 3 has a significantly large specific surface area due to a significantly small particle size,
the cycling performance also decreased, as evidenced by a 5.2% decrease in capacity retention over a 500 week cycle. In addition, in comparative example 3, since the particle diameter was remarkably decreased, the reduction of the compacted density was also remarkable, and it was 0.62g/cm lower than that of example 13Without compromising high compaction performance.
Comparative example 4:
the preparation method of the lithium cobaltate cathode material of the comparative example is basically the same as that of the example 1, and is different in the step (5), the temperature of the secondary sintering process is increased and decreased at a high speed of 8 ℃/min, the temperature reduction process is cancelled, the temperature of 800 ℃ is maintained for 2 hours, other operation steps are completely the same as those of the example 1, and the specific process of the step (5) is as follows: placing the secondary mixture obtained in the step (4) in a ventilation volume of 5m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 950 ℃ at the heating rate of 8 ℃/min, keeping the temperature for 8 hours, then reducing the temperature to room temperature at the cooling rate of 8 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by a jaw crusher and a double-roll crusher, and dissociating by an ACM (activated carbon) dissociating mill to obtain the high-compaction high-rate high-voltage lithium cobaltate cathode material. The dissociation process parameters are as follows: the dissociation frequency is 65Hz, the grading motor frequency is 60Hz, the feeding motor frequency is 35Hz, and the induced air frequency is 50 Hz.
The lithium cobaltate cathode material prepared by the comparative example has D50 of 9.06 mu m and a specific surface area of 0.37m2(ii)/g, compacted density 4.02g/cm3. Tests show that the material has a 0.2C discharge capacity of 194.0mAh/g, a capacity retention rate of 80.1% in 500-week circulation under 1C charge-discharge conditions, and a rate capability of 96.5% in 20C/0.2C within a test range of 25 ℃ and 3.0-4.45V. The physical properties and electrochemical properties of the positive electrode material products of the comparative example and example 1 are compared as shown in Table 4.
Table 4 comparison of physical properties and electrochemical properties of the positive electrode material products of comparative example 4 and example 1
Figure 752767DEST_PATH_IMAGE004
From the results in table 4, it can be seen that, since the secondary sintering process of comparative example 4 increases and decreases the temperature at a higher rate of 8 ℃/min, and simultaneously cancels the temperature reduction process of 800 ℃ for 2 hours, the coating effect is significantly affected, so that the retention rate of the circulation capacity of 500 times is reduced by 17.2% compared with that of example 1. The temperature is increased and decreased at a low speed of 3 ℃/min in the secondary sintering process, and the temperature is maintained for 2 hours at 800 ℃ in the temperature decreasing process, so that the reaction between the base materials with different particle sizes and the coating material on the surface can be promoted, and the coating layer can adsorb primary particles to generate different stresses; meanwhile, the coating material is tightly attached to the surfaces of the base materials with different particle sizes through high-temperature atomic diffusion, so that the falling-off of the coating material caused by the expansion/contraction of the volumes of the base materials with different particle sizes in the electrochemical circulation process is avoided, the composite compound in the coating material is connected with the base materials with different particle sizes through chemical bonds, the bonding strength between the coating structure and the base materials with different particle sizes is reinforced, and the improvement of the 500-time circulation capacity retention rate is facilitated.
Comparative example 5:
the high-compaction high-voltage lithium cobaltate cathode material has the D50 of 12.9 mu m and the specific surface area of 0.21m2(ii)/g, compacted density 4.05g/cm3. Tests show that the material has 0.2C discharge capacity of 193.2mAh/g, capacity retention rate of 500-week circulation under 1C charge-discharge conditions of 92.4 percent and 20C/0.2C rate performance of 85.3 percent in the test ranges of 25 ℃ and 3.0V-4.45V voltage.
The preparation method of the high-compaction high-voltage lithium cobalt oxide positive electrode material of the comparative example comprises the following steps:
(1) preparing a large-particle-size lithium cobalt oxide material A: d50 of A is 15.5 μm, and the preparation method adopted is as follows: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 5.0. mu.m2O3MgO and Pr2O3And (3) burdening, and then mixing by adopting a colter type mixer to obtain a primary mixture, wherein the addition amount of Al is 0.2wt% of the weight of the secondary sintering product, the addition amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the addition amount of Pr is 0.1wt% of the weight of the secondary sintering product. Placing the uniformly mixed materials in a ventilation volume of 15m3And (2) performing primary sintering in air, controlling the sintering main temperature to 1170 ℃, controlling the sintering time of a main temperature zone to be 8 hours, roughly crushing the materials subjected to primary sintering by using a jaw crusher and a double-roll crusher, and crushing and grading by using a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product A. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.56MPa, the frequency of a grading motor is 37Hz, the frequency of a feeding motor is 11Hz, and the pressure of a grinding body is-1.0 KPa;
(2) preparing a small-particle-size lithium cobaltate material B: d50 of B was 2.5 μm, and the preparation method used was: cobalt carbonate, lithium hydroxide and Al each having a particle diameter D50 of 2.2 μm2O3MgO and Pr2O3Proportioning, mixing by coulter mixer to obtain primary mixture AlThe adding amount is 0.2wt% of the weight of the secondary sintering product, the adding amount of Mg is 0.25wt% of the weight of the secondary sintering product, and the adding amount of Pr is 0.1wt% of the weight of the secondary sintering product; placing the uniformly mixed materials in a ventilation volume of 15m3And (2) performing primary sintering in air, controlling the sintering main temperature at 890 ℃, controlling the sintering time of a main temperature zone at 8 hours, coarsely crushing the materials subjected to primary sintering by a jaw crusher and a double-roller machine, and crushing and grading by a fluidized bed type airflow crushing and grading integrated machine to obtain the required lithium cobaltate semi-finished product B. The technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of grinding gas is 0.53MPa, the frequency of a grading motor is 35Hz, the frequency of a feeding motor is 10Hz, and the pressure of a grinding body is-2.0 KPa;
(3) preparing a large-particle mixed material C: and (3) grading the A, B materials obtained in the steps (1) and (2) according to a certain proportion, mixing by adopting a coulter type mixer, wherein the mass ratio of A to B is 4:1, and uniformly mixing to obtain a material C.
(4) Secondary batching and mixing: mixing the material C obtained in the step (3) and a coating according to a certain proportion, and then mixing the material C and the coating by a high-speed mixer to obtain a secondary mixture, wherein the coating is Co (OH)2And Y2O3Wherein Co (OH)24.5wt% of the weight of the primary sintered product, Y2O3Y in (3) is 0.2wt% of the weight of the primary sintered product.
(5) And (3) secondary sintering: placing the secondary mixture obtained in the step (4) in a ventilation volume of 5m3The secondary sintering is carried out in air, and the specific operation of the secondary sintering process comprises the following steps: heating to 950 ℃ at a heating rate of 3 ℃/min, keeping the temperature for 8 hours, then cooling to 800 ℃ at a cooling rate of 3 ℃/min, keeping the temperature for 2 hours, then cooling to room temperature at a rate of 3 ℃/min to obtain a blocky secondary sintering material, coarsely crushing by using a jaw crusher and a double-roll crusher, and then dissociating by using an ACM (acid-activated mechanical grinding) to obtain the lithium cobaltate cathode material. The dissociation process parameters are as follows: the dissociation frequency is 67Hz, the grading motor frequency is 62Hz, the feeding motor frequency is 37Hz, and the induced air frequency is 50 Hz.
The physical properties and electrochemical properties of the positive electrode material products of the comparative example and example 1 are compared as shown in Table 5.
TABLE 5 comparison of physical Properties and electrochemical Properties of the products of the positive electrode materials of comparative example 5 and example 1
Figure 19801DEST_PATH_IMAGE005
From the results of table 5, it can be seen that although the particle size D50, specific surface area and compacted density of the product of comparative example 5 are all within the protection scope of the present invention, since the particle sizes of the intermediate materials a and B are not within the protection scope of the present invention, the cycle performance and rate performance of the final product are significantly deteriorated, and the requirements of the present invention are not met.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The preparation method of the high-compaction high-rate high-voltage lithium cobaltate positive electrode material is characterized in that the particle size D50 of the lithium cobaltate positive electrode material is 6.0-14.0 mu m, and the specific surface area is 0.20-0.50 m2The compacted density is 3.96-4.1 g/cm3The preparation method comprises the following steps:
(1) mixing materials by adopting a solid-phase mixing method, then carrying out primary sintering, carrying out coarse crushing, and carrying out crushing and grading by adopting a fluidized bed jet milling and grading integrated machine to prepare a material A with D50 of 11.1-15.0 mu M, wherein the material A is a lithium cobaltate material co-doped with M and M', and the shape of the material A is a single crystal;
(2) mixing materials by adopting a solid-phase mixing method, then carrying out primary sintering, carrying out coarse crushing, and carrying out crushing and grading by adopting a fluidized bed jet milling and grading integrated machine to prepare a material B with D50 of 3.0-5.0 mu M, wherein the material B is a lithium cobaltate material co-doped with M and M', and the shape of the material B is similar to a single crystal;
(3) mixing the material A and the material B according to a certain proportion to obtain a mixed material C;
(4) uniformly mixing the mixed material C and the coating to obtain a secondary mixed material;
(5) and carrying out secondary sintering on the secondary mixture in an air atmosphere, and coarsely crushing and dissociating the obtained blocky secondary sintered material to obtain the required lithium cobaltate cathode material.
2. The method for preparing a high-compaction high-rate high-voltage lithium cobaltate cathode material according to claim 1, wherein in the step (1), the method for preparing the material A comprises the following steps: the preparation method comprises the steps of taking a cobalt source with the grain diameter D50 of 4.1-6.0 mu M, a lithium source, a compound containing a doping element M and a compound containing a doping element M' as raw materials, uniformly mixing, carrying out primary sintering in an air atmosphere, coarsely crushing the sintered materials, and crushing and grading by adopting a fluidized bed crushing and grading integrated machine.
3. The method for preparing a high-compaction high-rate high-voltage lithium cobaltate cathode material according to claim 1, wherein in the step (2), the method for preparing the material B comprises the following steps: the method comprises the steps of taking a cobalt source with the grain diameter D50 of 3.0-4.0 mu M, a lithium source, a compound containing a conventional doping element M and a compound containing an unconventional doping element M' as raw materials, uniformly mixing, then sintering in an air atmosphere, coarsely crushing the sintered materials, and then crushing and grading by adopting a fluidized bed airflow crushing and grading integrated machine.
4. The method for preparing the high-compaction high-rate high-voltage lithium cobaltate cathode material according to any one of claims 1 to 3, wherein in the step (3), the mass ratio of the material A to the material B is 4: 1-1: 1; the mixing is carried out using a coulter mixer.
5. The method for preparing a high-compaction high-rate high-voltage lithium cobaltate cathode material according to any one of claims 1 to 3, wherein the method comprises the step of preparing a high-compaction high-rate high-voltage lithium cobaltate cathode materialIn the step (4), the coating material comprises Co (OH)2And Y2O3(ii) a The Co (OH)2The amount of Y is 0.5-4.5 wt% of the weight of the mixed material C2O3The amount of Y in the mixed material C is 0.05-0.4 wt% of the weight of the mixed material C; and the secondary mixture is obtained by mixing the two materials by a high-speed mixer.
6. The method for preparing the high-compaction high-rate high-voltage lithium cobaltate cathode material according to claim 2 or 3, wherein in the steps (1) and (2), the doping element M is one or more of Al, Ti and Mg; the doping amount of the doping element M is 0.01-10 w.t% of the secondary sintering product; the doping element M' is selected from Pr and/or Ce; the doping amount of the doping element M' is 0.005-3 wt% of the weight of the secondary sintering product;
the molar ratio of lithium element in the lithium source to cobalt element in the cobalt source is n (Li) to n (Co) is 1.1-0.9: 1.
7. The method for preparing a high-compaction high-rate high-voltage lithium cobaltate cathode material according to any one of claims 1 to 3 and 6, wherein in the step (5), the secondary sintering comprises: in an air atmosphere, heating to 900-950 ℃ at a heating rate of 2-4 ℃/min, keeping the temperature for 6-10 hours, then cooling to 775-825 ℃ at a cooling rate of 2-4 ℃/min, keeping the temperature for 1-3 hours, and then cooling to room temperature at a rate of 2-4 ℃/min, wherein the air ventilation of the secondary sintering is 2-9 m3/h。
8. The method for preparing the high-compaction high-rate high-voltage lithium cobaltate cathode material according to claim 2, wherein the air flow of the primary sintering is 10-20 m3The primary sintering temperature is controlled to be 960-1160 ℃, and the primary temperature zone sintering time is 6-10 hours;
the technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of the grinding gas is 0.54-0.57 MPa, the frequency of a grading motor is 36-38 Hz, the frequency of a feeding motor is 10-11 Hz, and the pressure of a grinding body is-0.5-1.0 KPa.
9. The method for preparing the high-compaction high-rate high-voltage lithium cobalt oxide positive electrode material according to claim 3, wherein the ventilation volume of the primary sintering is 10-20 m3The primary sintering temperature is controlled to be 900-1000 ℃, and the sintering time of a primary temperature zone is 6-10 hours;
the technological parameters of the fluidized bed jet milling and grading integrated machine for crushing and grading are as follows: the pressure of the grinding gas is 0.50-0.53 MPa, the frequency of a grading motor is 34-36 Hz, the frequency of a feeding motor is 9-10 Hz, and the pressure of a grinding body is-2.0-2.5 KPa.
10. The method for preparing the high-compaction high-rate high-voltage lithium cobaltate cathode material according to any one of claims 1 to 3, wherein in the step (5), the dissociation is performed by using an ACM dissociation mill, and the dissociation process parameters are as follows: the dissociation frequency is 63-67 Hz, the grading motor frequency is 58-62 Hz, the feeding motor frequency is 33-37 Hz, and the induced air frequency is 48-52 Hz; the particle size requirement of the product obtained after dissociation is as follows: d0 is more than or equal to 0.5 mu m, and D50 is between 6.0 and 14.0 mu m.
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