CN114975954A - Lithium cobaltate positive electrode material, preparation method, positive plate and battery - Google Patents

Lithium cobaltate positive electrode material, preparation method, positive plate and battery Download PDF

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CN114975954A
CN114975954A CN202210701195.7A CN202210701195A CN114975954A CN 114975954 A CN114975954 A CN 114975954A CN 202210701195 A CN202210701195 A CN 202210701195A CN 114975954 A CN114975954 A CN 114975954A
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lithium
lithium cobaltate
positive electrode
electrode material
particle
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蒋珊
张昌明
胡大林
廖兴群
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Huizhou Highpower Technology Co Ltd
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Huizhou Highpower Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/36—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention discloses a lithium cobaltate positive electrode material, a preparation method, a positive plate and a battery, wherein the lithium cobaltate positive electrode material comprises a lithium cobaltate core and a lithium boron oxide coating layer; the lithium boron oxide coating layer is coated on the surface of the lithium cobaltate core. The lithium cobaltate positive electrode material wraps a lithium oxide boron coating layer (xLi) with a protection effect on the surface of a lithium cobaltate inner core 2 O·yB 2 O 3 ) The electrolyte has the function of a physical barrier, can effectively reduce the side reaction of the electrolyte on the surface of lithium cobaltate, and prevents Co from being used under the condition of high voltage 4+ The oxidation of the electrolyte is carried out,the structural stability of the lithium cobaltate material in the high-voltage charging and discharging process is enhanced, so that the lithium cobaltate material has good cycle performance under high voltage; in addition, the boron ion of the lithium oxide has good conductivity, improves the uniformity of lithium removal and insertion of the lithium cobaltate, has better rate performance, and improves the cycle stability and high-temperature stability of the lithium cobaltate under high voltage.

Description

Lithium cobaltate positive electrode material, preparation method, positive plate and battery
Technical Field
The invention relates to the technical field of secondary batteries, in particular to a lithium cobaltate positive electrode material, a preparation method, a positive plate and a battery.
Background
Lithium cobaltate is widely applied to various portable electronic devices such as notebook computers, mobile phones, tablet computers and the like due to high volumetric specific energy density. With the trend of 5G popularization and the trend of making portable electronic devices light and thin, the market has higher and higher requirements on energy density, and the demand for increasing the upper limit voltage of lithium cobaltate charging is urgent.
The existing lithium cobaltate material has poor structural stability under high voltage, for example, when the charging voltage of a battery cell reaches 4.50V, the lithium removal amount is about 75%, the phase change reversibility of the lithium cobaltate material is poor, and meanwhile, oxygen in the lithium cobaltate also participates in charge transfer, so that the structural stability is reduced, thereby the discharge specific capacity of the battery cell is sharply attenuated, and the use under high voltage cannot be met. Therefore, it is urgently required to improve the electrochemical performance of lithium cobaltate at a high voltage.
Disclosure of Invention
The invention aims to provide a lithium cobaltate positive electrode material, a preparation method, a positive plate and a battery.
The invention discloses a lithium cobaltate cathode material, which comprises a lithium cobaltate core and a lithium boron oxide coating layer; the lithium oxide boron coating layer is coated on the surface of the lithium cobaltate core.
Optionally, the lithium cobaltate core is doped with aluminum and magnesium.
Optionally, the lithium cobaltate core is doped with titanium.
Optionally, the D50 particle size of the lithium cobaltate positive electrode material is 5-7 μm.
Optionally, the D50 particle size of the lithium cobaltate positive electrode material is 18-20 μm.
Alternatively, the chemical formula of lithium cobaltate doped with aluminum, magnesium and titanium is LiCo a Al b Mg c Ti d B e O 2 (ii) a Wherein a is more than or equal to 0.95 and less than or equal to 0.999, b is more than or equal to 0.005 and less than or equal to 0.05, c is more than or equal to 0.001 and less than or equal to 0.005, d is more than or equal to 0.0001 and less than or equal to 0.005, and e is more than or equal to 0.0001 and less than or equal to 0.005.
The invention also discloses a positive plate which comprises the lithium cobaltate positive electrode material.
The invention also discloses a preparation method of the lithium cobaltate positive electrode material, which comprises the following steps:
step A: weighing a cobalt source precursor and a lithium source precursor as precursors, uniformly mixing, and performing primary sintering and primary crushing in an air atmosphere to obtain an intermediate product lithium cobaltate particle;
and B: weighing the boron additive, uniformly mixing the boron additive with the intermediate product lithium cobaltate particles, and sintering for the second time to obtain the lithium cobaltate cathode material with the lithium oxide boron coating layer.
Optionally, step a specifically includes: weighing an aluminum-doped cobalt source precursor and a lithium source precursor as precursors, adding a magnesium additive, uniformly mixing, and performing primary sintering and primary crushing in an air atmosphere to obtain an intermediate large-particle lithium cobalt oxide;
weighing an aluminum-doped cobalt source precursor and a lithium source precursor as precursors, adding a magnesium additive and a titanium additive, uniformly mixing, and performing first sintering and first crushing in an air atmosphere to obtain an intermediate product, namely small-particle lithium cobalt oxide.
The invention also discloses a battery, which comprises the positive plate.
According to the lithium cobaltate positive electrode material, the surface of the lithium cobaltate inner core is coated with the lithium oxide boron coating layer (xLi 2O. yB2O3) with a protection effect, so that the lithium cobaltate positive electrode material has a physical barrier effect, can effectively reduce side reactions of electrolyte on the surface of lithium cobaltate, prevents Co4+ from oxidizing the electrolyte under a high-voltage condition, enhances the structural stability of the lithium cobaltate material in a high-voltage charging and discharging process, and has good cycle performance under the high voltage; in addition, the boron ion conductivity of the lithium oxide is good, the uniformity of lithium intercalation and deintercalation of the lithium cobaltate is improved, the rate performance is good, and the cycle stability and the high-temperature stability of the lithium cobaltate under high voltage are improved.
Detailed Description
It is to be understood that the terminology, the specific structural and functional details disclosed herein are for the purpose of describing particular embodiments only, and are representative, but that the present invention may be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.
The invention is described in detail below with reference to alternative embodiments.
The invention discloses a lithium cobaltate positive electrode material as an embodiment of the invention, which comprises a lithium cobaltate core and a lithium boron oxide coating layer; the lithium oxide boron coating layer is coated on the surface of the lithium cobaltate core.
The lithium cobaltate positive electrode material wraps a lithium oxide boron coating layer (xLi) with a protection effect on the surface of a lithium cobaltate inner core 2 O·yB 2 O 3 ) The electrolyte has the function of a physical barrier, can effectively reduce the side reaction of the electrolyte on the surface of lithium cobaltate, and prevents Co from being used under the condition of high voltage 4+ The oxidation of the electrolyte enhances the structural stability of the lithium cobaltate material in the high-voltage charge-discharge process, so that the lithium cobaltate material has good cycle performance under high voltage; in addition, the boron ion of the lithium oxide has good conductivity, improves the uniformity of lithium removal and insertion of the lithium cobaltate, has better rate performance, and improves the cycle stability and high-temperature stability of the lithium cobaltate under high voltage.
Specifically, the lithium boron oxide coating layer is generated in situ on the surface of the lithium cobaltate core, namely, the boron additive directly reacts with residual lithium oxide on the surface of the lithium cobaltate core to generate lithium boron oxide, the combination is tight, and the side reaction of the electrolyte on the surface of the lithium cobaltate can be effectively reduced. The boron additive may be selected from boron oxide, boric acid, and the like. Specifically, the molar ratio of B/Co between boron in the lithium oxide boron coating layer and cobalt in the lithium cobaltate core is 0.0005 to 0.005.
Specifically, the lithium cobaltate core is doped with aluminum and magnesium. In the scheme, the lithium cobaltate core is doped with aluminum and magnesium, the radius of the 3-valent aluminum ion is equivalent to that of the 3-valent cobalt ion, and the aluminum occupies a cobalt position, so that the structural stability of the lithium cobaltate can be enhanced, and the phase change of the lithium cobaltate after lithium removal is inhibited; after magnesium is added, the introduction type P-type semiconductor doping is generated, and meanwhile, partial lithium vacancies are generated, so that the electronic conductivity can be improved to a certain extent; magnesium itself is a non-electrochemically active material and can also act to inhibit phase change. Specifically, the magnesium additive for doping magnesium may be one or more selected from magnesium oxide, magnesium carbonate, and magnesium hydroxide.
Specifically, the lithium cobaltate core is doped with titanium. When the lithium cobaltate is synthesized, the titanium can inhibit the growth of lithium cobaltate crystal grains, and small-particle lithium cobaltate with smaller particle size is obtained. That is, when the lithium cobaltate core is not doped with titanium, the synthesized lithium cobaltate has a larger particle size, and large-particle lithium cobaltate with a larger particle size can be obtained; when titanium is doped, small-particle lithium cobaltate with a small particle size can be obtained. According to the invention, two lithium cobaltates with different particle sizes, namely large-particle lithium cobaltate and small-particle lithium cobaltate, can be obtained by doping titanium or not. When the positive plate is prepared by adopting the positive electrode material of the lithium cobaltate particle material, the method can be adopted to simultaneously prepare large-particle lithium cobaltate and small-particle lithium cobaltate, the large-particle lithium cobaltate is not doped with titanium, and the small-particle lithium cobaltate is doped with titanium, so that different particle diameters of the large-particle lithium cobaltate and the small-particle lithium cobaltate are controlled. Large granule lithium cobaltate and granule lithium cobaltate can gomphosis each other in the coating, improve tap density, and the positive plate is the compaction more easily, consequently in the compaction, can reduce the compaction force of applying to the positive plate, and positive plate structure destruction is less when the compaction force reduces then the electric core preparation, improves electric core performance.
Specifically, when the lithium cobaltate kernel is doped with titanium, the D50 particle size of the lithium cobaltate particle material positive electrode material is 5-7 μm, and when the lithium cobaltate kernel is not doped with titanium, the D50 particle size of the lithium cobaltate particle material positive electrode material is 18-20 μm.
More specifically, the lithium cobaltate positive electrode material is divided into a large-particle lithium cobaltate part and a small-particle lithium cobaltate part, the D50 particle size of the large-particle lithium cobaltate is preferably 18-20 μm, and the D50 particle size of the small-particle lithium cobaltate is preferably 5-7 μm. When the large-particle lithium cobalt oxide and the small-particle lithium cobalt oxide are matched in a proper proportion, the tap density can be improved, and the positive plate is easier to compact. Compared with single-particle lithium cobalt oxide, the roller pressure degree can be reduced by the lithium cobalt oxide matched with the large and small particles in the same pressing process, the damage degree of the lithium cobalt oxide particles is smaller, and the performance of the battery core can be improved. More specifically, a small particle portion of the lithium cobaltate core is doped with titanium. When synthesizing small-particle lithium cobaltate, the titanium additive is added, and the titanium can play a role in inhibiting the growth of lithium cobaltate crystal grains. In particular, the titanium additive is selected from titanium dioxide.
Specifically, the chemical formula of lithium cobaltate doped with aluminum, magnesium and titanium is LiCo a Al b Mg c Ti d B e O 2 (ii) a Wherein a is more than or equal to 0.95 and less than or equal to 0.999, b is more than or equal to 0.005 and less than or equal to 0.05, c is more than or equal to 0.001 and less than or equal to 0.005, d is more than or equal to 0.0001 and less than or equal to 0.005, and e is more than or equal to 0.0001 and less than or equal to 0.005.
The invention also discloses a positive plate which comprises the lithium cobaltate positive electrode material. Specifically, the positive plate contains a lithium cobaltate positive electrode material with a larger particle size and a lithium cobaltate positive electrode material with a smaller particle size, namely large-particle lithium cobaltate and small-particle lithium cobaltate, so that the tap density of the lithium cobaltate can be improved, and the positive plate is easier to compact. Therefore, when the lithium cobaltate is compacted, the pressure applied to the positive plate can be reduced, the damage to the lithium cobaltate structure is small, and the performance of the battery cell can be improved.
The invention also discloses a preparation method of the lithium cobaltate positive electrode material, which comprises the following steps:
step A: weighing a cobalt source precursor and a lithium source precursor as precursors, uniformly mixing, and performing primary sintering and primary crushing in an air atmosphere to obtain an intermediate product lithium cobaltate particle;
and B: weighing the boron additive, uniformly mixing the boron additive with the intermediate product lithium cobaltate particles, and sintering for the second time to obtain the lithium cobaltate cathode material with the lithium oxide boron coating layer.
According to the preparation method of the lithium cobaltate cathode material, a cobalt source precursor and a lithium source precursor are subjected to primary sintering in an air atmosphere, and an intermediate product lithium cobaltate, namely a lithium cobaltate core, is obtained through reaction; and (3) sintering the intermediate product lithium cobaltate particles and the boron additive for the second time in the air atmosphere, reacting to obtain the lithium cobaltate positive electrode material with the lithium oxide boron coating layer, and coating the lithium oxide boron coating layer on the surface of the lithium cobaltate core.
The lithium cobaltate positive electrode material prepared by the method generates a lithium oxide boron coating layer with a protective effect in situ on the surface of a lithium cobaltate core, and lithium oxideThe boron coating layer plays a role of physical barrier and prevents Co under high voltage condition 4+ The oxidation of the electrolyte enhances the structural stability of the material in the high-voltage charge and discharge process, so that the material has good cycle performance under high voltage; in addition, the conductivity of the lithium oxide boron ions is good, the uniformity of lithium removal and insertion of lithium cobaltate is improved, and the rate performance is good.
The lithium cobaltate core prepared by the method is in a single crystal or single crystal-like shape, gram capacity is exerted to be more than 185mAh/g in a 4.5V electric core system, the capacity retention rate of circulating 1000cls under 4.5V can be more than or equal to 80%, the lithium cobaltate core has the characteristics of stable structure and small circulating capacity attenuation in the high-voltage charging and discharging process, no liquid phase is added in the preparation process, no waste water is generated, the process is simple, the implementation is convenient, and the obtained lithium cobaltate anode material has excellent electrochemical performance.
Specifically, the step a specifically comprises: weighing an aluminum-doped cobalt source precursor and a lithium source precursor as precursors, adding a magnesium additive, uniformly mixing, sintering for the first time in an air atmosphere, and crushing for the first time to obtain an intermediate product large-particle lithium cobalt oxide. In the scheme, magnesium is added into an aluminum-doped cobalt source precursor to perform magnesium doping, so that an aluminum and magnesium-doped lithium cobaltate core is obtained, the 3-valent aluminum ion radius is similar to the 3-valent cobalt ion radius, and aluminum occupies a cobalt position, so that the structural stability of the lithium cobaltate can be enhanced, and the phase change of the lithium cobaltate after lithium removal is inhibited; magnesium is added to generate introduction type P-type semiconductor doping, and meanwhile, partial lithium vacancies are generated, so that the electron conductivity can be improved to a certain extent; magnesium itself is a non-electrochemically active material and can also act to inhibit phase change.
Specifically, an aluminum-doped cobalt source precursor and a lithium source precursor are weighed as precursors, a magnesium additive and a titanium additive are added, and after uniform mixing, first sintering and first crushing are carried out in an air atmosphere to obtain an intermediate product, namely small-particle lithium cobalt oxide.
Specifically, the cobalt source precursor may be cobaltosic oxide, the lithium source precursor may be lithium carbonate, and the magnesium additive is one or more selected from magnesium oxide, magnesium carbonate and magnesium hydroxide.
More specifically, large-particle aluminum-doped cobaltosic oxide and lithium carbonate are used as precursors, magnesium carbonate is added, after uniform mixing, primary sintering and primary crushing are carried out in the air atmosphere, and then the intermediate product large-particle lithium cobaltate, namely a lithium cobaltate core with a larger particle size, is obtained;
adopting small-particle aluminum-doped cobaltosic oxide and lithium carbonate as precursors, adding magnesium carbonate and titanium dioxide, uniformly mixing, and performing primary sintering and primary crushing in an air atmosphere to obtain an intermediate small-particle lithium cobaltite, namely a lithium cobaltite core with a smaller particle size;
adding large-particle lithium cobaltate, small-particle lithium cobaltate and boron oxide according to a certain proportion, uniformly mixing at a high speed, then carrying out secondary sintering, and crushing for the second time to obtain a finished product lithium cobaltate, wherein the finished product lithium cobaltate comprises a lithium cobaltate positive electrode material with a lithium oxide boron coating layer and a small particle size. The inner core of lithium cobaltate is doped with aluminum and magnesium, the surface of the inner core is coated with a lithium oxide boron coating layer, and the chemical formula of the lithium cobaltate is LiCo a Al b Mg c Ti d B e O 2 (ii) a Wherein a is more than or equal to 0.95 and less than or equal to 0.999, b is more than or equal to 0.005 and less than or equal to 0.05, c is more than or equal to 0.001 and less than or equal to 0.005, d is more than or equal to 0.0001 and less than or equal to 0.005, and e is more than or equal to 0.0001 and less than or equal to 0.005.
Specifically, the first crushing and the second crushing do not crush the lithium cobaltate core and the lithium cobaltate positive electrode material itself, but separate the lithium cobaltate core bonded to each other and separate the lithium cobaltate positive electrode material bonded to each other.
Specifically, the lithium carbonate and the large-particle cobaltosic oxide are prepared according to the Li/Co molar ratio of 1.03-1.08, the magnesium additive is added according to the Mg/Co molar ratio of 0.001-0.005, and the magnesium additive is one or more selected from magnesium oxide, magnesium carbonate and magnesium hydroxide.
According to the method, lithium carbonate and small-particle cobaltosic oxide are prepared according to the molar ratio of Li to Co of 1.02-1.07, the magnesium additive is added according to the molar ratio of Mg to Co of 0.001-0.005, the magnesium additive is one or more selected from magnesium oxide, magnesium carbonate and magnesium hydroxide, the titanium additive is added according to the molar ratio of Ti to Co of 0.0001-0.002, and the titanium additive is selected from titanium dioxide.
The first sintering process of the intermediate product large-particle lithium cobalt oxide comprises the following steps: sintering for 8-16 h under the condition of air atmosphere and 950-1100 ℃, and then carrying out airflow crushing to obtain an intermediate product large-particle lithium cobaltate D50 with the particle size of 13-20 microns.
The first sintering process of the small-particle lithium cobalt oxide as the intermediate product in the method comprises the following steps: sintering for 8-16 h under the condition of 900-1050 ℃ in an air atmosphere, and then carrying out airflow crushing to obtain intermediate product large and small lithium cobaltate D50 particles with the particle size of 3-8 mu m.
According to the method, the molar ratio of boron to cobalt is 0.0005-0.005. The temperature of the second sintering is 900-1000 ℃, and the time is 6-12 h.
The invention also discloses a battery, which comprises the positive plate.
The following are given by way of specific examples and comparative examples.
Example 1
(1) Adding lithium carbonate and large-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the lithium carbonate and the cobaltosic oxide with the Al/Co molar ratio of 1.06, simultaneously adding magnesium carbonate into the lithium carbonate and the cobaltosic oxide with the Mg/Co molar ratio of 0.002, and mixing the mixture at high speed by adopting a super mixer to obtain a primary mixture which is uniformly dispersed;
(2) boxing the primary mixture, sintering for 12 hours at 1050-1080 ℃ in air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintered large-particle lithium cobalt oxide, wherein the average particle size (D50) is controlled to be 18-20 mu m;
(3) adding lithium carbonate and small-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the lithium carbonate and the small-particle cobaltosic oxide with the Li/Co molar ratio of 1.05, simultaneously adding magnesium carbonate into the lithium carbonate and the small-particle cobaltosic oxide with the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by adopting a super mixer to obtain a primary mixture which is uniformly dispersed;
(4) boxing the primary mixture, sintering for 10 hours at 950-980 ℃ in an air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintering small-particle lithium cobaltate, wherein the average particle size (D50) is controlled to be 5-7 mu m;
(5) adding the primary sintered large-particle lithium cobalt oxide obtained in the step (2) and the primary sintered small-particle lithium cobalt oxide obtained in the step (4) according to a ratio of 8:2, simultaneously adding boron oxide according to a B/Co molar ratio of 0.001, and mixing the mixture at a high speed by using a super mixer to obtain a uniformly dispersed secondary mixture;
(6) and (3) boxing the secondary mixture, sintering for 8 hours at 950-980 ℃ in an air atmosphere, crushing the obtained secondary sinter by using airflow crushing equipment, and sieving to obtain a finished product of lithium cobaltate.
Example 2
(1) Adding lithium carbonate and large-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the mixture according to the Li/Co molar ratio of 1.06, simultaneously adding magnesium carbonate into the mixture according to the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by a super mixer to obtain a primary mixture which is uniformly dispersed;
(2) boxing the primary mixture, sintering for 12 hours at 1050-1080 ℃ in air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintered large-particle lithium cobalt oxide, wherein the average particle size (D50) is controlled to be 18-20 mu m;
(3) adding lithium carbonate and small-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the mixture according to the Li/Co molar ratio of 1.05, simultaneously adding magnesium carbonate into the mixture according to the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by a super mixer to obtain a primary mixture which is uniformly dispersed;
(4) boxing the primary mixture, sintering for 10 hours at 950-980 ℃ in an air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintering small-particle lithium cobaltate, wherein the average particle size (D50) is controlled to be 5-7 mu m;
(5) adding the primary sintered large-particle lithium cobalt oxide obtained in the step (2) and the primary sintered small-particle lithium cobalt oxide obtained in the step (4) according to a ratio of 8:2, simultaneously adding boron oxide according to a B/Co molar ratio of 0.0015, and mixing the mixture at a high speed by using a super mixer to obtain a uniformly dispersed secondary mixture;
(6) and (3) boxing the secondary mixture, sintering for 8 hours at 950-980 ℃ in an air atmosphere, crushing the obtained secondary sinter by using airflow crushing equipment, and sieving to obtain a finished product of lithium cobaltate.
Example 3
(1) Adding lithium carbonate and large-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the mixture according to the Li/Co molar ratio of 1.06, simultaneously adding magnesium carbonate into the mixture according to the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by a super mixer to obtain a primary mixture which is uniformly dispersed;
(2) boxing the primary mixture, sintering for 12 hours at 1050-1080 ℃ in air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintered large-particle lithium cobalt oxide, wherein the average particle size (D50) is controlled to be 18-20 mu m;
(3) adding lithium carbonate and small-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the mixture according to the Li/Co molar ratio of 1.05, simultaneously adding magnesium carbonate into the mixture according to the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by a super mixer to obtain a primary mixture which is uniformly dispersed;
(4) boxing the primary mixture, sintering for 10 hours at 950-980 ℃ in an air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintering small-particle lithium cobaltate, wherein the average particle size (D50) is controlled to be 5-7 mu m;
(5) adding the primary sintered large-particle lithium cobalt oxide obtained in the step (2) and the primary sintered small-particle lithium cobalt oxide obtained in the step (4) according to a ratio of 8:2, simultaneously adding boron oxide according to a B/Co molar ratio of 0.002, and mixing the mixture at a high speed by using a super mixer to obtain a uniformly dispersed secondary mixture;
(6) and (3) boxing the secondary mixture, sintering for 8 hours at 950-980 ℃ in an air atmosphere, crushing the obtained secondary sinter by using airflow crushing equipment, and sieving to obtain a finished product of lithium cobaltate.
Example 4
(1) Adding lithium carbonate and large-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the mixture according to the Li/Co molar ratio of 1.06, simultaneously adding magnesium carbonate into the mixture according to the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by a super mixer to obtain a primary mixture which is uniformly dispersed;
(2) boxing the primary mixture, sintering for 12 hours at 1050-1080 ℃ in air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintered large-particle lithium cobalt oxide, wherein the average particle size (D50) is controlled to be 18-20 mu m;
(3) adding lithium carbonate and small-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the mixture according to the Li/Co molar ratio of 1.05, simultaneously adding magnesium carbonate into the mixture according to the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by a super mixer to obtain a primary mixture which is uniformly dispersed;
(4) boxing the primary mixture, sintering for 10 hours at 950-980 ℃ in an air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintering small-particle lithium cobaltate, wherein the average particle size (D50) is controlled to be 5-7 mu m;
(5) adding the primary sintered large-particle lithium cobalt oxide obtained in the step (2) and the primary sintered small-particle lithium cobalt oxide obtained in the step (4) according to a ratio of 8:2, simultaneously adding boron oxide according to a B/Co molar ratio of 0.003, and mixing the mixture at a high speed by using a super mixer to obtain a uniformly dispersed secondary mixture;
(6) and (3) boxing the secondary mixture, sintering for 8 hours at 950-980 ℃ in an air atmosphere, crushing the obtained secondary sinter by using airflow crushing equipment, and sieving to obtain a finished product of lithium cobaltate.
Comparative example 1
(1) Adding lithium carbonate and large-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the lithium carbonate and the cobaltosic oxide with the Al/Co molar ratio of 1.06, simultaneously adding magnesium carbonate into the lithium carbonate and the cobaltosic oxide with the Mg/Co molar ratio of 0.002, and mixing the mixture at high speed by adopting a super mixer to obtain a primary mixture which is uniformly dispersed;
(2) boxing the primary mixture, sintering for 12 hours at 1050-1080 ℃ in air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintered large-particle lithium cobalt oxide, wherein the average particle size (D50) is controlled to be 18-20 mu m;
(3) adding lithium carbonate and small-particle cobaltosic oxide with the Al/Co molar ratio of 0.015 into the mixture according to the Li/Co molar ratio of 1.05, simultaneously adding magnesium carbonate into the mixture according to the Mg/Co molar ratio of 0.002, and mixing the mixture at a high speed by a super mixer to obtain a primary mixture which is uniformly dispersed;
(4) boxing the primary mixture, sintering for 8 hours at 950-980 ℃ in an air atmosphere, crushing the obtained primary sinter by using airflow crushing equipment, and sieving to obtain primary sintering small-particle lithium cobaltate, wherein the average particle size (D50) is controlled to be 5-7 mu m;
(5) and (3) adding the primary sintered large-particle lithium cobalt oxide obtained in the step (2) and the primary sintered small-particle lithium cobalt oxide obtained in the step (4) according to the ratio of 8:2, and mixing the mixture at a high speed by using a super mixer to obtain a finished product lithium cobalt oxide.
Preparing the lithium cobaltate material prepared in the comparative example 1 and the examples 1 to 3 into a battery cell, and testing the battery cell;
uniformly mixing lithium cobaltate, a conductive agent SP and a binder polyvinylidene fluoride (PVDF) in a Nitrogen Methyl Pyrrolidone (NMP) solvent, wherein the mass ratio of the lithium cobaltate to the conductive agent to the binder is 97.0: 1.7: and 1.3, coating the uniformly mixed slurry on an aluminum foil through extrusion equipment, drying, rolling and splitting to obtain the lithium ion cell positive plate.
The artificial graphite negative electrode material, a dispersant sodium carboxymethyl cellulose (CMC) and a binder modified Styrene Butadiene Rubber (SBR) are mixed according to the mass ratio of 98: 1.0: 1.0, preparing materials, coating the uniformly mixed slurry on a copper foil through extrusion equipment, drying, rolling and splitting to obtain the lithium ion cell negative plate.
The anode plate and the cathode plate are used, the electrolyte adopts 1.1mol/L solution of ethylene carbonate, propylene carbonate, fluoroethylene carbonate and the like of lithium hexafluorophosphate, the diaphragm adopts composite material of polyethylene, ceramic and binder with the thickness of 8 microns, 416080 winding type lithium ion battery cell is assembled, and the test voltage range is 3.0-4.50V. The performance test results of the lithium ion battery cell are shown in the following table 1:
TABLE 1
Figure BDA0003704290530000141
As shown in Table 1, examples 1 to 4, in which a lithium boron oxide coating layer was added, exhibited superior performance to comparative example 1 in 25 ℃ cycle performance, 45 ℃ cycle performance, rate discharge performance, and high temperature storage performance. Specifically, compared with lithium cobaltate which is not coated with a lithium oxide boron coating layer, the cycle and high-temperature performance of the lithium cobaltate cathode material obtained by the invention under high voltage are obviously improved; the boron additive added in the second sintering and the residual lithium source precursor on the surface of the lithium cobaltate core form a lithium oxide boron coating layer, which is different from the physical combination of common coating oxides, the lithium oxide boron coating layer is generated by reacting with the residual lithium oxide on the surface of the lithium cobaltate core, the combination is tight, and the side reaction of the electrolyte on the surface of the lithium cobaltate can be effectively reduced; in addition, due to the excellent ionic conductivity of the lithium oxide boron coating layer, the uniformity of lithium desorption and insertion is facilitated, and the rate discharge performance of lithium cobaltate is improved. In conclusion, the lithium cobaltate provided by the invention can effectively improve the cycle stability and high-temperature stability of the lithium cobaltate under high voltage.
It should be noted that, the limitations of the steps involved in the present disclosure are not considered to limit the order of the steps without affecting the implementation of the specific embodiments, and the steps written in the foregoing may be executed first, or executed later, or even executed simultaneously, and as long as the present disclosure can be implemented, all should be considered to belong to the protection scope of the present disclosure.
The foregoing is a more detailed description of the invention in connection with specific alternative embodiments, and the practice of the invention should not be construed as limited to those descriptions. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (10)

1. A lithium cobaltate positive electrode material is characterized by comprising a lithium cobaltate core and a lithium boron oxide coating layer; the lithium boron oxide coating layer is coated on the surface of the lithium cobaltate core.
2. The lithium cobaltate positive electrode material of claim 1, wherein the lithium cobaltate core is doped with aluminum and magnesium.
3. The lithium cobaltate positive electrode material according to claim 1 or 2, wherein the lithium cobaltate core is doped with titanium.
4. The lithium cobaltate positive electrode material according to claim 3, wherein a D50 particle size of the lithium cobaltate positive electrode material is 5 to 7 μm.
5. The lithium cobaltate positive electrode material according to claim 1 or 2, wherein a D50 particle size of the lithium cobaltate positive electrode material is 18 to 20 μm.
6. The lithium cobaltate positive electrode material according to claim 1, wherein the chemical formula of the lithium cobaltate doped with aluminum, magnesium and titanium is LiCo a Al b Mg c Ti d B e O 2 (ii) a Wherein a is more than or equal to 0.95 and less than or equal to 0.999, b is more than or equal to 0.005 and less than or equal to 0.05, c is more than or equal to 0.001 and less than or equal to 0.005, d is more than or equal to 0.0001 and less than or equal to 0.005, and e is more than or equal to 0.0001 and less than or equal to 0.005.
7. A positive electrode sheet comprising the lithium cobaltate positive electrode material according to any one of claims 1 to 6.
8. A preparation method of a lithium cobaltate positive electrode material is characterized by comprising the following steps:
step A: weighing a cobalt source precursor and a lithium source precursor as precursors, uniformly mixing, and performing primary sintering and primary crushing in an air atmosphere to obtain an intermediate product lithium cobaltate particle;
and B: weighing the boron additive, uniformly mixing the boron additive with the intermediate product lithium cobaltate particles, and sintering for the second time to obtain the lithium cobaltate cathode material with the lithium oxide boron coating layer.
9. The method for preparing a lithium cobaltate positive electrode material according to claim 8, wherein the step a specifically comprises:
weighing an aluminum-doped cobalt source precursor and a lithium source precursor as precursors, adding a magnesium additive, uniformly mixing, and performing primary sintering and primary crushing in an air atmosphere to obtain an intermediate large-particle lithium cobalt oxide;
weighing an aluminum-doped cobalt source precursor and a lithium source precursor as precursors, adding a magnesium additive and a titanium additive, uniformly mixing, and performing first sintering and first crushing in an air atmosphere to obtain an intermediate product, namely small-particle lithium cobalt oxide.
10. A battery comprising the positive electrode sheet according to claim 7.
CN202210701195.7A 2022-06-21 2022-06-21 Lithium cobaltate positive electrode material, preparation method, positive plate and battery Pending CN114975954A (en)

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