CN114267834A - Modified lithium cobaltate and preparation method and application thereof - Google Patents
Modified lithium cobaltate and preparation method and application thereof Download PDFInfo
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- 150000002641 lithium Chemical class 0.000 title claims abstract description 54
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 62
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 62
- 239000000463 material Substances 0.000 claims abstract description 43
- 239000011247 coating layer Substances 0.000 claims abstract description 38
- FZHAPNGMFPVSLP-UHFFFAOYSA-N silanamine Chemical group [SiH3]N FZHAPNGMFPVSLP-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000007822 coupling agent Substances 0.000 claims abstract description 26
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 21
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 20
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 19
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 19
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 19
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 19
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 19
- 239000006087 Silane Coupling Agent Substances 0.000 claims abstract description 17
- 239000011159 matrix material Substances 0.000 claims abstract description 9
- 238000000576 coating method Methods 0.000 claims description 43
- 239000011248 coating agent Substances 0.000 claims description 42
- 239000002243 precursor Substances 0.000 claims description 42
- 239000000843 powder Substances 0.000 claims description 37
- 239000010410 layer Substances 0.000 claims description 36
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 26
- 239000002245 particle Substances 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 16
- 239000002904 solvent Substances 0.000 claims description 14
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 11
- 238000012216 screening Methods 0.000 claims description 11
- 229910052710 silicon Inorganic materials 0.000 claims description 11
- 239000010703 silicon Substances 0.000 claims description 11
- 239000003054 catalyst Substances 0.000 claims description 9
- 238000009768 microwave sintering Methods 0.000 claims description 7
- NHBRUUFBSBSTHM-UHFFFAOYSA-N n'-[2-(3-trimethoxysilylpropylamino)ethyl]ethane-1,2-diamine Chemical compound CO[Si](OC)(OC)CCCNCCNCCN NHBRUUFBSBSTHM-UHFFFAOYSA-N 0.000 claims description 7
- 238000010298 pulverizing process Methods 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 4
- 238000003980 solgel method Methods 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 238000010902 jet-milling Methods 0.000 claims 1
- 239000002120 nanofilm Substances 0.000 abstract description 6
- 239000003792 electrolyte Substances 0.000 abstract description 5
- 230000007797 corrosion Effects 0.000 abstract description 2
- 238000005260 corrosion Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 13
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 9
- 125000003277 amino group Chemical group 0.000 description 8
- 239000002585 base Substances 0.000 description 7
- 239000007774 positive electrode material Substances 0.000 description 7
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 5
- 235000011114 ammonium hydroxide Nutrition 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 239000010405 anode material Substances 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
- 238000003760 magnetic stirring Methods 0.000 description 4
- 238000007873 sieving Methods 0.000 description 4
- 238000009210 therapy by ultrasound Methods 0.000 description 4
- 238000001291 vacuum drying Methods 0.000 description 4
- 229910032387 LiCoO2 Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000005253 cladding Methods 0.000 description 3
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910012820 LiCoO Inorganic materials 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910010710 LiFePO Inorganic materials 0.000 description 1
- 229910015645 LiMn Inorganic materials 0.000 description 1
- 229910013292 LiNiO Inorganic materials 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
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- 238000005520 cutting process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 description 1
- IWICDTXLJDCAMR-UHFFFAOYSA-N trihydroxy(propan-2-yloxy)silane Chemical compound CC(C)O[Si](O)(O)O IWICDTXLJDCAMR-UHFFFAOYSA-N 0.000 description 1
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- 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
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Abstract
The invention discloses a modified lithium cobaltate and a preparation method and application thereof, wherein the modified lithium cobaltate comprises a lithium cobaltate base material and a coating layer formed on the outer surface of the base material, and the coating layer is composed of NQ-SiO2Wherein NQ is an aminosilane coupling agent. The modified SiO of the modified lithium cobaltate intermediate coating layer by amino silane coupling agent2Forming a non-polar molecular film on the surface of lithium cobaltate materialThe stability and the hydrophobicity of the coating layer are improved, so that the coating layer is more uniformly dispersed on the surface of the material, the corrosion of the electrolyte to the matrix material can be better isolated, and the structural stability of the lithium cobaltate is improved, so that the safety performance and the cycle performance of the lithium ion battery adopting the modified lithium cobaltate are improved.
Description
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to modified lithium cobaltate and a preparation method thereof, and further relates to application of the modified lithium cobaltate as a positive electrode material in a lithium ion battery.
Background
A Lithium-ion battery (Lithium-ion battery) is a rechargeable battery that mainly relies on Lithium ions moving between a positive electrode and a negative electrode to operate. The main common positive electrode materials currently used for lithium ion batteries are: lithium cobaltate (LiCoO)2) Lithium manganate (LiMn)2O4) Lithium nickelate (LiNiO)2) Lithium iron phosphate (LiFePO)4) And nickel cobalt manganese ternary materials (NCM), and the like.
Among them, lithium cobaltate LiCoO2Has excellent energy density, cycle performance and high and low temperature performance, and lithium cobaltate LiCoO2Have a high operating voltage and a high energy density and are widely used in lithium ion batteries. However, LiCoO2Under the condition of deep charge and discharge, the structural stability and the safety performance of the lithium ion battery have obvious defects. At present, the above problems are mainly solved by doping and surface coating methods, wherein the doping is mainly to improve the electrochemical performance of the material, and the surface coating can not only improve the electrochemical performance of the material, but also improve the safety performance of the material.
However, the materials for industrially producing the surface coating of the positive active material at home and abroad are mainly metal oxide powder, and the purpose of surface coating is achieved by mixing and sintering the coating material and the positive active material. Therefore, it is necessary to provide a method for coating and modifying lithium cobaltate by using a coating material having poor thermal conductivity and low moisture residual quantity, so as to obtain modified lithium cobaltate with high structural stability and good safety performance. It is noted that the conductivity of the cladding material is generally poor, and it is difficult to have high electronic and ionic conductivity at the same time, so that the thickness of the cladding material is generally required to be controlled in the nanometer range, and the mass percentage of the cladding material in the total mass of the material is as low as possible. The method not only increases the technical difficulty of uniform coating, but also easily causes the problems of local exposure and over-thick coating layer on the surface of the lithium cobaltate particles, is not beneficial to protecting the surface of the lithium cobaltate particles, and increases the interface impedance of the lithium cobaltate battery. Furthermore, the coating material generally has no electrochemical activity, and thus cannot provide capacity during the charge and discharge of the battery, and the thickness of the coating material is as thin as possible.
Chinese patent application publication No. CN111697223A discloses a surface-modified lithium ion battery cathode material, in which a surface of a base material is coated with a material, wherein the coating material is a hydrophobic organosilicon material, and the hydrophobic organosilicon material is a silane coupling agent KH560, so that the cathode material can be prevented from absorbing water and carbon dioxide while charging and discharging are completed by coating, the processability of the cathode material is improved, and the pH and surface residual alkali of the cathode material are reduced. However, the stability, uniformity and dispersibility of the coating layer in the scheme are not good, and the performance of the battery material is not favorably exerted.
Disclosure of Invention
In view of the above, the present invention is to provide a modified lithium cobaltate, which comprises a lithium cobaltate as a base material and a coating layer formed on the surface of the base material, wherein the coating layer is SiO modified by an aminosilane coupling agent2And a layer of non-polar molecular film is formed on the surface of the lithium cobaltate material, so that the stability and the hydrophobicity of the coating layer are improved, the coating layer is more uniformly dispersed on the surface of the material, the corrosion of electrolyte to a base material can be better isolated, the structural stability of the lithium cobaltate is improved, and the safety performance and the cycle performance of a lithium ion battery adopting the modified lithium cobaltate are improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention firstly provides modified lithium cobaltate, which comprises the following components:
a matrix material which is lithium cobaltate;
and a coating layer formed on the outer surface of the base material, wherein the coating layer is formed by NQ-SiO2Coupling agent modified SiO2The composition is that NQ is an amino silane coupling agent.
Further, the particle size of the matrix material is between 1 and 30 mu m.
Further, the thickness of the coating layer is between 20 and 40 nm.
In a further embodiment, the aminosilane coupling agent is selected from the group consisting of diethylenetriaminopropyltrimethoxysilane and N- (3- (trimethoxysilylethyl) ethylenediamine.
The invention further provides a preparation method of the modified lithium cobaltate, which comprises the following steps:
dissolving an aminosilane coupling agent, a silicon source precursor and an alkaline catalyst in an alcohol solvent by adopting a sol-gel method to form sol-like coating precursor liquid;
adding lithium cobaltate powder into the sol-like coating precursor solution, heating and stirring until the solvent is completely volatilized, and drying to obtain precursor powder;
microwave sintering, crushing and multilayer screening the precursor powder to obtain modified lithium cobaltate, namely, the surface of the modified lithium cobaltate is uniformly coated with NQ-SiO2Wherein NQ is an aminosilane coupling agent.
In the sol coating precursor solution, the volume ratio of each component is 15-20ml of silicon source precursor: 0.5-3ml of amino silane coupling agent: 1-2ml of basic catalyst: the alcohol solvent was prepared in a proportion of 150-200 ml.
Further, the temperature of the microwave sintering is 400-500 ℃ and the time is 1-10 h.
In a further scheme, the pulverization adopts air flow pulverization, the classification frequency of the air flow pulverization is 2-20Hz, and the feeding frequency is 5-30 Hz.
In a further scheme, the multilayer screening adopts 3-layer vibration screening, wherein the mesh number of a first layer of screen is 100 meshes, the mesh number of a second layer of screen is 200 meshes, and the mesh number of a third layer of screen is 325 meshes.
The invention further provides the application of the modified lithium cobaltate in the preparation of a lithium ion battery.
Compared with the prior art, the invention has the following beneficial effects:
the invention coats the surface of lithium cobaltate matrix material with amino silane coupling agent modified oxide material NQ-SiO2In the amino silane coupling agent, nitrogen atoms of amino groups and nano-oxide formed after hydrolysis of a silicon source precursor form hydrogen bonds, so that a stable nonpolar molecular film is formed on the surface of the lithium cobaltate material, and the stable nonpolar molecular film is more stably and uniformly dispersed on the surface of the anode material, so that the stability and hydrophobicity of the coating layer are improved, and the structural stability and high-temperature cycle performance of the lithium cobaltate can be better improved by more uniformly dispersing the stable nonpolar molecular film on the surface of the material.
The invention uniformly coats aminosilane coupling agent modified oxide NQ-SiO on the surface of lithium cobaltate powder by in-situ hydrolysis2Thereby forming a coating layer with the thickness of nanometer level, overcoming the defects of poor lithium ion transmission capability, over-thick coating layer and the like in the inert coating layer, reducing the side reaction of the anode material and the electrolyte, and simultaneously meeting the requirements of the anode material on the capacity, the high-temperature cycle performance and the safety performance under high voltage.
The preparation method of the modified lithium cobaltate provided by the invention is simple in process, high in production efficiency and suitable for industrial production.
Drawings
FIG. 1 is a scanning electron micrograph of a modified lithium cobaltate prepared in example 3;
fig. 2 is a graph showing cycle profiles of lithium ion batteries made of modified lithium cobaltates of example 1 and comparative example 1.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the specific embodiments illustrated. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
In a first aspect the present invention provides a modified lithium cobaltate comprising:
a matrix material which is lithium cobaltate;
and a coating layer formed on the outer surface of the base material, wherein the coating layer is formed by NQ-SiO2The coupling agent is used for modifying the oxide material, wherein NQ is an aminosilane coupling agent.
Specifically, lithium cobaltate is used as a base material, a coating layer is formed on the surface of the lithium cobaltate, and the coating layer is made of an oxide material NQ-SiO modified by an aminosilane coupling agent2The composition can form a layer of nanoscale nonpolar molecular film on the surface of lithium cobaltate, and the stability, the dispersibility and the hydrophobicity of the coating material are improved, so that the structural stability and the high-temperature cycle performance of the lithium cobaltate are better improved. According to the embodiment of the present invention, the particle size of the matrix material lithium cobaltate is not particularly limited, and may be selected by those skilled in the art according to the actual situation, and in some specific embodiments of the present invention, the particle size of the matrix material is 1 to 30 μm, and preferably 8 to 28 μm.
According to the embodiment of the present invention, the thickness of the coating layer is not particularly limited, and may be adjusted by the amounts of the aminosilane coupling agent and the silicon source precursor, and may be selected by those skilled in the art according to the actual situation. Preferably, the traditional coating layer is too thick, so that the energy density of the battery is reduced, and meanwhile, the lithium ion transmission resistance is increased, which is not beneficial to the performance of the lithium ion battery; and if the coating layer is too thin, the coating on the surface of the lithium cobaltate particles is not uniform, so that the protection effect cannot be achieved. In some embodiments of the present invention, the thickness of the coating layer is 10 to 150nm, preferably 20 to 40 nm.
According to the embodiments of the present invention, the term "aminosilane coupling agent" means a silane coupling agent having an amino group in the structure, which can be classified into a single amino group, a double amino group, a triple amino group, a multiple amino group, and the like according to the difference of the amino group content, and the aminosilane coupling agent used herein can be conventionally selected in the art, preferably, in some specific embodiments of the present invention, the number of the amino group of the aminosilane coupling agent used is not less than 2, so that the coating layer can be coated on the surface of the lithium cobaltate positive electrode material in a more uniform dispersion manner, and specific examples include, but are not limited to, diethylenetriaminopropyltrimethoxysilane or N- (3- (trimethoxysilylethyl) ethylenediamine, and the like.
In a second aspect of the present invention, a method for preparing a modified lithium cobaltate is provided, which mainly comprises the following steps:
forming a coating precursor solution
Specifically, an aminosilane coupling agent, a silicon source precursor and an alkaline catalyst are dissolved in an alcohol solvent to form a sol-like coating precursor solution. The aminosilane coupling agent used is as described in the first aspect of the present invention and will not be described in detail here. The silicon source precursor, the alcohol solvent and the alkaline catalyst may be selected conventionally, wherein the silicon source precursor may be selected from materials conventionally used in the art for generating silicon dioxide by hydrolysis in a sol-gel method, and specific examples include, but are not limited to, tetraethyl orthosilicate, isopropyl orthosilicate, methyl orthosilicate, and the like, the alcohol solvent may be ethanol, and the alkaline catalyst may be ammonia water. According to the embodiment of the invention, the sol coating precursor liquid is prepared by the volume ratio of 15-20ml of silicon source precursor, 0.5-3ml of aminosilane coupling agent, 1-2ml of alkaline catalyst and 200ml of alcohol solvent.
Obtaining a precursor powder
Specifically, lithium cobaltate powder is added to the mixtureHeating the sol-like coating precursor solution until the solvent is completely volatilized, and drying to obtain the sol-like coating precursor solution; heating to make the solvent completely volatilize, in the solvent volatilizing process, under the condition of alkaline catalyst, the silicon source precursor can absorb the water content in the air, slowly hydrolyzing and drying so as to obtain the invented NQ-SiO2The surface of the lithium cobaltate powder is uniformly coated.
To obtain modified lithium cobaltate
Specifically, the precursor powder is subjected to microwave sintering, crushing and multilayer screening to obtain modified lithium cobaltate, namely, the surface of the modified lithium cobaltate is uniformly coated with NQ-SiO2The lithium cobaltate of (1). According to the embodiment of the invention, the raw material can be heated more rapidly by adopting microwave sintering, so that uniform coating can be realized in a shorter process time, and the production efficiency is higher, in some specific embodiments of the invention, the precursor powder is placed in a crucible, the crucible is placed in a microwave kiln for heating, and the temperature of the microwave sintering is between 400 and 500 ℃, and the time is 1-10h, preferably 9-10 h.
Further, according to the embodiment of the present invention, the sintered particles are preferably pulverized by using airflow, and the particles are driven by high-speed airflow to make the particles collide and rub against each other to achieve the pulverization effect, and the specific feeding and pulverizing frequency can be selected by those skilled in the art according to the actual situation, in some specific embodiments of the present invention, the classification frequency of the airflow pulverization is 2 to 20Hz, and the feeding frequency is 5 to 30 Hz.
According to the embodiment of the invention, the multilayer screening is performed to facilitate obtaining the silane coupling agent modified oxide coated lithium cobaltate with uniform granularity, and the specific screening particle size can be selected by those skilled in the art according to actual conditions such as battery performance requirements, and in some specific embodiments of the invention, the multilayer screening adopts 3-layer vibration screening, wherein the mesh number of the first layer of screen is 100 meshes, the mesh number of the second layer of screen is 200 meshes, and the mesh number of the third layer of screen is 325 meshes.
In a third aspect of the invention there is provided the use of a modified lithium cobaltate according to any one of the first aspect of the invention in the manufacture of a lithium ion battery. The modified lithium cobaltate is used as the anode material of the lithium ion battery, and the anode, the diaphragm, the electrolyte and the like can be selected by those skilled in the art according to actual conditions, the lithium ion battery can be assembled by adopting conventional means in the field, and the obtained lithium ion battery has gram capacity exertion and cycling stability.
The present invention is illustrated below by way of specific examples, which are intended to be illustrative only and not to limit the scope of the present invention in any way, and reagents and materials used therein are commercially available, unless otherwise specified, and conditions or steps thereof are not specifically described.
Example 1
The modified lithium cobaltate in the embodiment comprises a core and a coating layer coated on the surface of the core, wherein the core is the lithium cobaltate with the particle size of 8 mu m; the structural formula of the coating layer is NQ-SiO2The thickness was 20 nm.
The preparation method comprises the following specific steps:
mixing 15ml of tetraethyl orthosilicate, 0.5ml of diethylenetriaminopropyltrimethoxysilane, 1ml of ammonia water and 150ml of ethanol to prepare coating precursor liquid;
150g of lithium cobaltate powder with the particle size of 8 mu m is added into the coating precursor liquid, the ultrasonic treatment is carried out for 1h to ensure that the lithium cobaltate powder is uniformly dispersed in the coating precursor liquid, then the magnetic stirring is carried out until the ethanol is volatilized to be dry, and the aminosilane coupling agent and tetraethyl orthosilicate are hydrolyzed under the alkaline condition to form NQ-SiO which is uniformly attached to the surface of the lithium cobaltate2Vacuum drying at 100 deg.C for 6 hr to obtain coarse powder;
placing the coarse powder into a crucible, then placing the crucible into a microwave kiln, and heating for 10 hours at 400 ℃ to obtain modified lithium cobaltate, namely the aminosilane coupling agent modified SiO2A coated lithium cobaltate;
placing the modified lithium cobaltate in a pulverizer with the grading frequency of 2-20Hz and the feeding frequency of 5-30Hz to obtain pulverized powder;
sieving the pulverized powder with 3 layers of vibrating screen with vibration frequency of 1000HzWherein, the mesh number of the first layer of the 3 layers of vibrating screens is 100 meshes, the mesh number of the second layer of the vibrating screens is 200 meshes, the mesh number of the third layer of the vibrating screens is 325 meshes, and the obtained core has the grain diameter of 8 μm and the shell thickness of 20nm and has a structural formula of NQ-SiO2And (3) modifying the lithium cobaltate.
Example 2
The modified lithium cobaltate in the embodiment comprises a core and a coating layer coated on the surface of the core, wherein the core is the lithium cobaltate with the particle size of 11 mu m; the structural formula of the coating layer is NQ-SiO2The thickness was 40 nm.
The preparation method comprises the following specific steps:
preparing 16ml of tetraethyl orthosilicate, 0.8ml of diethylenetriaminopropyltrimethoxysilane, 1ml of ammonia water and 160ml of ethanol to obtain coating precursor liquid;
150g of lithium cobaltate powder with the particle size of 11 mu m is added into the coating precursor liquid, the ultrasonic treatment is carried out for 1h to ensure that the lithium cobaltate powder is uniformly dispersed in the coating precursor liquid, then the magnetic stirring is carried out until ethanol is volatilized to be dry, and the silane coupling agent and the tetraethoxysilane are hydrolyzed under the alkaline condition to form NQ-SiO which is uniformly attached to the surface of the lithium cobaltate2Vacuum drying at 100 deg.C for 6 hr to obtain coarse powder;
placing the coarse powder into a crucible, then placing the crucible into a microwave kiln, heating for 10h at 450 ℃ to obtain modified lithium cobaltate, namely the aminosilane coupling agent modified SiO2A coated lithium cobaltate;
placing the modified lithium cobaltate in a pulverizer with the grading frequency of 2-20Hz and the feeding frequency of 5-30Hz to obtain pulverized powder;
sieving the pulverized powder with 3 layers of vibrating screens with vibration frequency of 1000Hz, wherein the mesh number of the first layer of the 3 layers of vibrating screens is 100 meshes, the mesh number of the second layer of the vibrating screens is 200 meshes, the mesh number of the third layer of the vibrating screens is 325 meshes, and the obtained product has a core particle size of 11 μm and a shell thickness of 40nm and has a structure formula of NQ-SiO2And (3) modifying the lithium cobaltate.
Example 3
The modified lithium cobaltate in the embodiment comprises a core and a coating layer coated on the surface of the core, whereinThe inner core is lithium cobaltate with the grain diameter of 18 mu m; the structural formula of the coating layer is NQ-SiO2The thickness was 70 nm.
The preparation method comprises the following specific steps:
preparing 18ml of tetraethyl orthosilicate, 1ml of diethylenetriaminopropyltrimethoxysilane, 1ml of ammonia water and 180ml of ethanol to obtain coating precursor liquid;
150g of lithium cobaltate powder with the particle size of 18 mu m is added into the coating precursor liquid, the ultrasonic treatment is carried out for 1h to ensure that the lithium cobaltate powder is uniformly dispersed in the coating precursor liquid, then the magnetic stirring is carried out until ethanol is volatilized to be dry, and the silane coupling agent and the tetraethoxysilane are hydrolyzed under the alkaline condition to form NQ-SiO which is uniformly attached to the surface of the lithium cobaltate2Vacuum drying at 100 deg.C for 6 hr to obtain coarse powder;
placing the coarse powder in a crucible, and then placing the crucible in a microwave kiln to heat for 10 hours at 500 ℃ to obtain modified lithium cobaltate, namely the silane coupling agent coated lithium cobaltate;
placing the modified lithium cobaltate in a pulverizer with the grading frequency of 2-20Hz and the feeding frequency of 5-30Hz to obtain pulverized powder;
sieving the pulverized powder with 3 layers of vibrating screens with vibration frequency of 1000Hz, wherein the mesh number of the first layer of the 3 layers of vibrating screens is 100 meshes, the mesh number of the second layer of the vibrating screens is 200 meshes, the mesh number of the third layer of the vibrating screens is 325 meshes, and the obtained product has a core particle size of 18 μm and a shell thickness of 70nm and has a structure formula of NQ-SiO2And (3) modifying the lithium cobaltate.
Fig. 1 shows a scanning electron microscope image of the modified lithium cobaltate prepared in this example, and it can be seen that the lithium cobaltate particles modified and coated with the aminosilane coupling agent are uniformly distributed, have smooth surfaces and have no granular feel.
Example 4
The modified lithium cobaltate in the embodiment comprises a core and a coating layer coated on the surface of the core, wherein the core is the lithium cobaltate with the particle size of 28 microns; the structural formula of the coating layer is NQ-SiO2The thickness is 150 nm.
The preparation method comprises the following specific steps:
preparing 20ml of tetraethyl orthosilicate, 3ml of diethylenetriaminopropyltrimethoxysilane, 2ml of ammonia water and 200ml of ethanol to obtain coating precursor liquid;
150g of lithium cobaltate powder with the particle size of 20 mu m is added into the coating precursor liquid, the ultrasonic treatment is carried out for 1h to ensure that the lithium cobaltate powder is uniformly dispersed in the coating precursor liquid, then the magnetic stirring is carried out until ethanol is volatilized to be dry, and the silane coupling agent and the tetraethoxysilane are hydrolyzed under the alkaline condition to form NQ-SiO which is uniformly attached to the surface of the lithium cobaltate2Vacuum drying at 100 deg.C for 6 hr to obtain coarse powder;
placing the coarse powder in a crucible, and then placing the crucible in a microwave kiln to heat for 10 hours at 500 ℃ to obtain modified lithium cobaltate, namely the silane coupling agent coated lithium cobaltate;
placing the modified lithium cobaltate in a pulverizer with the grading frequency of 2-20Hz and the feeding frequency of 5-30Hz to obtain pulverized powder;
sieving the pulverized powder with 3 layers of vibrating screen with vibration frequency of 1000Hz, wherein the mesh number of the first layer of the 3 layers of vibrating screen is 100 meshes, the mesh number of the second layer of the vibrating screen is 200 meshes, and the mesh number of the third layer of the vibrating screen is 325 meshes, to obtain NQ-SiO with core particle diameter of 28 μm and shell thickness of 150nm2And (3) modifying the lithium cobaltate.
Comparative example 1
This comparative example is a lithium cobaltate material prepared without any coating treatment and having a particle size of 8 μm.
Comparative example 2
Lithium cobaltate with the particle size of 8 mu m and a silane coupling agent KH560 are provided, and the modified lithium cobaltate is prepared by adopting the technical scheme in the embodiment 1 in the publication number CN 11697223A.
Comparative example 3
This comparative example uses the same embodiment as example 1 except that: the adopted silane coupling agent is KH 560; and obtaining the modified lithium cobaltate.
Comparative example 4
This comparative example uses the same embodiment as example 1 except that: no aminosilane coupling agent is added into the coating precursor liquid; and obtaining the modified lithium cobaltate.
Test example
And (3) assembling the button-type half cell by taking the modified lithium cobaltate obtained in the embodiment and the comparative example as a positive electrode material and graphite as a negative electrode, and carrying out related performance tests. The method specifically comprises the following steps: the charge and discharge at 0.2C/0.2C are carried out under the conditions of 25 ℃ and the voltage interval of 3.0-4.48V, and the electrical property test results are shown in Table 1.
TABLE 1 button half-cell Electrical Performance test results
The test results in table 1 show that the first efficiency and cycle retention of the button half cell made of the coated and modified lithium cobaltate are higher than those of the modified lithium cobaltate in the comparative example, and that the lithium cobaltate coated by the modified oxide of the amino silane coupling agent has excellent performance; in addition, the embodiment shows that the coating amount has certain influence on the development of the gram volume of the material, and the coating with proper thickness can obviously improve the gram volume of the material and the cycling stability of the material.
Further, the modified lithium cobaltates of examples and comparative examples were used as positive electrode materials to fabricate a full cell, and the modified LiCoO was used2And a conductive agent Super P and a binder polyvinylidene fluoride (PVDF) in a mass ratio of 96: 2: 2, dispersing the mixture in a N-methyl pyrrolidone (NMP) solvent, uniformly stirring to obtain electrode slurry, coating the electrode slurry on the surface of an aluminum foil, baking the aluminum foil at 120 ℃ for 12 hours in vacuum, rolling and cutting to obtain a positive electrode plate; and matching with a graphite negative electrode, and using 1mol/L LiPF6/(EC + DEC + DMC) electrolyte (volume ratio is 1:1:1) to prepare the PP/PE/PP three-layer diaphragm into a flexible package battery. The charge and discharge tests were carried out at 25 ℃ and 45 ℃ at 4.48V/0.2C, respectively.
When the discharge capacity is tested at 25 ℃, the first discharge capacity of 4.48V is not lower than 180mAh/g, and the first efficiency is not lower than 97.0%; the capacity retention rate at 4.48V for 300 weeks tested at 45 c was not less than 80.0%, wherein the test results in example 1 and comparative examples 1-4 are shown in fig. 2 and table 2.
Table 2 full cell performance test in example 1 and comparative examples 1 to 4
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A modified lithium cobaltate, comprising:
a matrix material which is lithium cobaltate;
and a coating layer formed on the outer surface of the base material, wherein the coating layer is formed by NQ-SiO2Wherein NQ is an aminosilane coupling agent.
2. The modified lithium cobaltate of claim 1, wherein the particle size of the matrix material is between 1-30 μ ι η.
3. The modified lithium cobaltate of claim 1, wherein the coating layer has a thickness of between 20 and 40 nm.
4. The modified lithium cobaltate of claim 1, wherein the aminosilane coupling agent is selected from the group consisting of diethylenetriaminopropyltrimethoxysilane and N- (3- (trimethoxysilylethyl) ethylenediamine.
5. A preparation method of modified lithium cobaltate is characterized by comprising the following steps:
dissolving an aminosilane coupling agent, a silicon source precursor and an alkaline catalyst in an alcohol solvent by adopting a sol-gel method to form sol-like coating precursor liquid;
adding lithium cobaltate powder into the sol-like coating precursor solution, heating and stirring until the solvent is completely volatilized, and drying to obtain precursor powder;
microwave sintering, crushing and multilayer screening the precursor powder to obtain modified lithium cobaltate, namely, the surface of the modified lithium cobaltate is uniformly coated with NQ-SiO2Wherein NQ is an aminosilane coupling agent.
6. The method according to claim 5, wherein the sol coating precursor solution contains 15 to 20ml of the silicon source precursor: 0.5-3ml of amino silane coupling agent: 1-2ml of basic catalyst: the alcohol solvent was prepared in a proportion of 150-200 ml.
7. The method as claimed in claim 5, wherein the temperature of the microwave sintering is 400-500 ℃ for 1-10 h.
8. The method of claim 5, wherein the pulverization is carried out by jet milling at a classifying frequency of 2 to 20Hz and a feeding frequency of 5 to 30 Hz.
9. The method of claim 5, wherein the multi-layer screening uses 3-layer vibratory screening, wherein the first layer of screens has a mesh size of 100 mesh, the second layer of screens has a mesh size of 200 mesh, and the third layer of screens has a mesh size of 325 mesh.
10. Use of a modified lithium cobaltate according to any one of claims 1 to 4 in the preparation of a lithium ion battery.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103199242A (en) * | 2013-03-05 | 2013-07-10 | 东莞新能源科技有限公司 | Borosilicate coated and modified lithium cobaltate and preparation method thereof |
| CN108232129A (en) * | 2016-12-21 | 2018-06-29 | 深圳市比克动力电池有限公司 | Lithium ion battery negative material, negative plate and lithium ion battery |
| WO2021223635A1 (en) * | 2020-05-08 | 2021-11-11 | 北京当升材料科技股份有限公司 | Lithium cobaltate positive electrode material, preparation method therefor and use thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103199242A (en) * | 2013-03-05 | 2013-07-10 | 东莞新能源科技有限公司 | Borosilicate coated and modified lithium cobaltate and preparation method thereof |
| CN108232129A (en) * | 2016-12-21 | 2018-06-29 | 深圳市比克动力电池有限公司 | Lithium ion battery negative material, negative plate and lithium ion battery |
| WO2021223635A1 (en) * | 2020-05-08 | 2021-11-11 | 北京当升材料科技股份有限公司 | Lithium cobaltate positive electrode material, preparation method therefor and use thereof |
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