CN117080429A - Lithium cobalt oxide positive electrode material, preparation method thereof, positive electrode plate, secondary battery and power utilization device - Google Patents
Lithium cobalt oxide positive electrode material, preparation method thereof, positive electrode plate, secondary battery and power utilization device Download PDFInfo
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- CN117080429A CN117080429A CN202311231750.5A CN202311231750A CN117080429A CN 117080429 A CN117080429 A CN 117080429A CN 202311231750 A CN202311231750 A CN 202311231750A CN 117080429 A CN117080429 A CN 117080429A
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- 229910000625 lithium cobalt oxide Inorganic materials 0.000 title claims abstract description 104
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 title claims abstract description 104
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 76
- 238000002360 preparation method Methods 0.000 title abstract description 20
- 239000000843 powder Substances 0.000 claims abstract description 69
- 229910000428 cobalt oxide Inorganic materials 0.000 claims abstract description 23
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims abstract description 23
- 238000005056 compaction Methods 0.000 claims abstract description 14
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 124
- 229910052744 lithium Inorganic materials 0.000 claims description 124
- 238000005245 sintering Methods 0.000 claims description 75
- 229910017052 cobalt Inorganic materials 0.000 claims description 70
- 239000010941 cobalt Substances 0.000 claims description 70
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 70
- 239000000463 material Substances 0.000 claims description 67
- 238000000034 method Methods 0.000 claims description 45
- UBEWDCMIDFGDOO-UHFFFAOYSA-N cobalt(2+);cobalt(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Co+2].[Co+3].[Co+3] UBEWDCMIDFGDOO-UHFFFAOYSA-N 0.000 claims description 39
- 239000000654 additive Substances 0.000 claims description 24
- 230000000996 additive effect Effects 0.000 claims description 24
- 239000010405 anode material Substances 0.000 claims description 22
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 21
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 21
- 239000002245 particle Substances 0.000 claims description 20
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 239000010406 cathode material Substances 0.000 claims description 14
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 12
- 238000009826 distribution Methods 0.000 claims description 9
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 238000010586 diagram Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 3
- 229910021503 Cobalt(II) hydroxide Inorganic materials 0.000 claims description 3
- 229910002651 NO3 Inorganic materials 0.000 claims description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 3
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 3
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 3
- 229910021446 cobalt carbonate Inorganic materials 0.000 claims description 3
- -1 cobalt oxyhydroxide Chemical compound 0.000 claims description 3
- ZOTKGJBKKKVBJZ-UHFFFAOYSA-L cobalt(2+);carbonate Chemical compound [Co+2].[O-]C([O-])=O ZOTKGJBKKKVBJZ-UHFFFAOYSA-L 0.000 claims description 3
- ASKVAEGIVYSGNY-UHFFFAOYSA-L cobalt(ii) hydroxide Chemical compound [OH-].[OH-].[Co+2] ASKVAEGIVYSGNY-UHFFFAOYSA-L 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 3
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 3
- 150000002910 rare earth metals Chemical class 0.000 claims description 3
- 229910052723 transition metal Inorganic materials 0.000 claims description 3
- 150000003624 transition metals Chemical class 0.000 claims description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 32
- 230000008569 process Effects 0.000 description 29
- 239000004408 titanium dioxide Substances 0.000 description 16
- 239000012071 phase Substances 0.000 description 15
- 239000000047 product Substances 0.000 description 14
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 12
- 238000002156 mixing Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 239000012535 impurity Substances 0.000 description 11
- 239000002994 raw material Substances 0.000 description 9
- 238000007873 sieving Methods 0.000 description 8
- 238000005303 weighing Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 6
- 238000004064 recycling Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 239000003513 alkali Substances 0.000 description 4
- 239000000395 magnesium oxide Substances 0.000 description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 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
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000010902 jet-milling Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000012958 reprocessing Methods 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G51/00—Compounds of cobalt
- C01G51/40—Cobaltates
- C01G51/42—Cobaltates containing alkali metals, e.g. LiCoO2
-
- 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
- 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
- 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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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a lithium cobalt oxide positive electrode material, a preparation method thereof, a positive electrode plate, a secondary battery and an electric device, wherein the content of cobalt oxide hetero-phase in the lithium cobalt oxide positive electrode material is 1100ppm-1700ppm, and lithium cobalt oxide fine powder existing in a free form is attached to the surface of the lithium cobalt oxide positive electrode material. The content of the cobalt oxide hetero-phase in the lithium cobalt oxide positive electrode material is obviously reduced, and the electrical property of the lithium cobalt oxide positive electrode material is obviously improved; meanwhile, the surface of the lithium cobalt oxide positive electrode material is also attached with lithium cobalt oxide fine powder existing in a free form, and the existence of the lithium cobalt oxide fine powder can improve the specific surface area, half-peak width and compaction density of the lithium cobalt oxide positive electrode material, so that the specific capacity, energy density and multiplying power performance of the lithium cobalt oxide positive electrode material are improved.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium cobalt oxide positive electrode material, a preparation method thereof, a positive electrode plate, a secondary battery and an electric device.
Background
Lithium cobaltate is one of the most attractive positive electrode materials for lithium ion batteries because it has superior cycle stability, superior reversibility and high energy density, and is easy to prepare. Lithium ion batteries using lithium cobaltate as a positive electrode material play a key role in the rapid development of various portable electronic products, such as mobile phones, notebook computers, electric tools, small unmanned aerial vehicles, and the like.
In the related art, a solid phase method is generally adopted to prepare lithium cobaltate, and the preparation process is simple and low in cost. However, 1 to 5% of lithium cobaltate fine powder is generated in the air current crushing or mechanical crushing process in the high voltage lithium cobaltate production process, and the capacity cycle retention rate of lithium cobaltate is low when working in a high voltage environment, so that the lithium cobaltate needs to be separated from normal materials. The main component of the lithium cobalt oxide fine powder is still lithium cobalt oxide, but the residual alkali content is generally 0.04% -1.1%, which is obviously higher than that of normal materials, so that the processing performance is poor when the battery positive plate is manufactured, and the battery positive plate cannot be used as a normal positive plate material.
Disclosure of Invention
Based on the above, it is necessary to provide a lithium cobalt oxide positive electrode material, a method for producing the same, a positive electrode sheet, a secondary battery, and an electric device, so that lithium cobalt oxide fine powder is used for producing the lithium cobalt oxide positive electrode material, and the recycling of the lithium cobalt oxide fine powder is realized.
The first aspect of the invention provides a lithium cobalt oxide positive electrode material, the content of cobalt oxide hetero-phase in the lithium cobalt oxide positive electrode material is 1100ppm-1700ppm, and lithium cobalt oxide fine powder existing in a free form is attached to the surface of the lithium cobalt oxide positive electrode material.
In some embodiments, the lithium cobaltate positive electrode material has at least one of the following features:
(1) The average particle diameter D50 of the lithium cobalt oxide positive electrode material is 3-9 mu m, and the half-peak width of the peak in the particle diameter distribution diagram is 1.45-1.6;
(2) The specific surface area of the lithium cobalt oxide positive electrode material is 0.52m 2 /g-0.60m 2 /g；
(3) The compaction density of the lithium cobalt oxide positive electrode material under 150MPa is 3.34m 2 /g-3.6g/cm 3 。
The second aspect of the invention provides a preparation method of the lithium cobalt oxide anode material of the first aspect of the invention, which comprises the following steps:
and (3) performing first-stage sintering treatment on the mixed material comprising the cobalt source, the lithium source and the lithium cobalt oxide fine powder, and performing second-stage sintering treatment after heating to prepare the lithium cobalt oxide positive electrode material.
In some embodiments, the first stage sintering process is at a temperature of 500 ℃ to 900 ℃ for a time of 1h to 5h; and/or
The temperature of the second-stage sintering treatment is 950-1100 ℃ and the time is 4-9 h.
In some embodiments, the mass of the lithium cobaltate powder is 0.1% -12% of the mass of the cobalt source.
In some embodiments, the method of preparing a lithium cobaltate cathode material includes at least one of the following conditions:
(1) The molar ratio of the lithium element contained in the lithium source to the cobalt element contained in the cobalt source is 1-1.08:1;
(2) The lithium source comprises one or more of lithium hydroxide, lithium carbonate and lithium oxalate;
(3) The cobalt source comprises one or more of cobalt hydroxide, cobaltosic oxide, cobalt carbonate and cobalt oxyhydroxide;
(4) The mixture further comprises an additive, wherein the additive comprises one or more of an oxide, a hydroxide, a nitrate, a sulfate, a carbonate and a composite oxide containing a metal element M;
optionally, the metal element M includes one or more of a transition metal, an alkaline earth metal, and a rare earth metal;
optionally, the mass of the additive accounts for 1000ppm-4000ppm of the mass of the cobalt source.
In some embodiments, the method of making further comprises: crushing the sintered material after the second-stage sintering treatment;
optionally, the crushing treatment is performed by air stream crushing.
The third aspect of the invention provides a positive electrode sheet comprising the lithium cobalt oxide positive electrode material of the first aspect of the invention or prepared by the method of the second aspect of the invention.
A fourth aspect of the present invention provides a secondary battery comprising the positive electrode tab of the third aspect of the present invention.
A fifth aspect of the invention provides an electric device comprising the secondary battery of the fourth aspect of the invention.
The lithium cobalt oxide anode material, the preparation method thereof, the anode plate, the secondary battery and the power utilization device have the advantages that the content of the cobalt oxide impurity phase in the lithium cobalt oxide anode material is obviously reduced, and the electrical property of the lithium cobalt oxide anode material is obviously improved; meanwhile, the surface of the lithium cobalt oxide positive electrode material is also attached with lithium cobalt oxide fine powder existing in a free form, and the existence of the lithium cobalt oxide fine powder can improve the specific surface area, PSD (particle size distribution) half-peak width and compaction density of the lithium cobalt oxide positive electrode material, so that the specific capacity, energy density and rate capability of the lithium cobalt oxide positive electrode material are improved.
In addition, when the lithium cobaltate anode material is prepared, a two-stage sintering process is adopted, so that the full reaction degree of raw materials can be effectively improved, the content of cobalt oxide impurity phases in the product is reduced, and the electrical property of the finished product is effectively improved; meanwhile, the lithium cobaltate fine powder, the cobalt source and the lithium source are added simultaneously, so that the process complexity can be reduced, and the specific surface area, half-peak width and compaction density of the prepared lithium cobaltate positive electrode material can be improved; the specific capacity, the energy density and the multiplying power performance of the 4.25V multiplying power lithium cobalt oxide material can be effectively improved by adopting the preparation method. In addition, the preparation method of the lithium cobalt oxide positive electrode material realizes the recycling of the lithium cobalt oxide fine powder, and reduces the overall production cost of the lithium cobalt oxide.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a graph showing a particle size distribution of a lithium cobalt oxide positive electrode material in example 1 of the present invention.
Fig. 2 is a scanning electron microscope image of a lithium cobaltate cathode material in example 1 of the present invention.
Fig. 3 is a scanning electron microscope image of the lithium cobaltate cathode material in comparative example 1 of the present invention.
Detailed Description
In order that the invention may be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Preferred embodiments of the present invention are given below. 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. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
In the invention, the technical characteristics described in an open mode comprise a closed technical scheme composed of the listed characteristics and also comprise an open technical scheme comprising the listed characteristics.
In the present invention, the numerical ranges are referred to as continuous, and include the minimum and maximum values of the ranges, and each value between the minimum and maximum values, unless otherwise specified. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.
Only a few numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form a range not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and any upper limit may be combined with any other upper limit to form a range not explicitly recited. Furthermore, each separately disclosed point or individual value may itself be combined as a lower limit or upper limit with any other point or individual value or with other lower limit or upper limit to form a range not explicitly recited.
The temperature parameter in the present invention is not particularly limited, and may be a constant temperature treatment or a treatment within a predetermined temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.
In the description of the invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
All embodiments of the invention and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified. All technical features and optional technical features of the invention may be combined with each other to form new technical solutions, unless specified otherwise.
All the steps of the present invention may be performed sequentially or randomly, preferably sequentially, unless otherwise specified.
The main component of the lithium cobaltate fine powder is still lithium cobaltate, but the residual alkali content is generally 0.04% -1.1%, which is obviously higher than that of normal materials, so that the processing performance is poor when the battery positive plate is manufactured, and the battery positive plate cannot be used as a normal positive material; however, the lithium cobaltate fine powder is stable in working in a low-voltage environment, has the advantage of multiplying power performance and has the possibility of recycling. At present, the following treatment modes of the lithium cobaltate fine powder mainly exist:
1. the lithium cobaltate fine powder is sold in a cobalt oxide manufacturer as waste product for recycling and reprocessing, and the processing mode can obviously increase the production cost of the lithium cobaltate.
2. The lithium cobaltate fine powder is directly added into the low-voltage lithium cobaltate finished product to be uniformly mixed for use, but as the fine powder is mainly small particles stripped from the surface of larger particles through crushing equipment, the surface of the fine powder is damaged, the residual alkali is very high, and the first week coulomb efficiency and the circulation capacity retention rate of the material are affected by directly adding back the finished product.
3. A small amount of lithium source is added into the lithium cobalt oxide fine powder, and after mixing, sintering and jet milling, a certain amount of cobalt source is added into the lithium cobalt oxide fine powder, and after mixing, sintering is carried out, so that the particle size D50, pH and electrical property of the lithium cobalt oxide fine powder reach the level of commercial lithium cobalt oxide, but the method has a complex process, and the lithium cobalt oxide fine powder needs to be pretreated, so that the method is not beneficial to large-scale industrial production.
4. The method is characterized in that the method adopts conventional crushing equipment except that the production process is complex, so that the added fine powder is separated again in a large amount, and the effect of reducing the cost is weak.
In addition, a high-temperature one-stage sintering mode, namely a sintering mode of heating to a certain temperature (generally more than 1000 ℃) and preserving heat for a certain time and then cooling is adopted in the industry. The nucleation temperature of the cobalt source and the lithium source is 500-900 ℃, and the growth of lithium cobaltate crystal nucleus is more facilitated when the higher temperature is more than 1000 ℃, so that when the set heat preservation temperature is higher by adopting a one-stage sintering process, the generated lithium cobaltate starts to grow rapidly when insufficient nucleation is carried out, the reaction is insufficient, more cobalt oxide impurity phases exist in the finished product, and the electrical performance is poor.
The above-mentioned mixed phase of cobalt oxide refers to an unreacted cobalt source in the raw material and a cobalt oxide newly formed in the process of preparing a lithium cobalt oxide positive electrode material, and the residual alkali is a general term for compounds remaining on the surface of lithium cobalt oxide in the form of lithium hydroxide, lithium carbonate, or the like.
Based on the problems, the invention provides a preparation method of a lithium cobalt oxide positive electrode material, wherein lithium cobalt oxide fine powder is used as a raw material for preparing the lithium cobalt oxide positive electrode material, the lithium cobalt oxide fine powder, a lithium source and a cobalt source are simultaneously mixed to prepare a mixed material, and then the mixed material is sintered by adopting a two-stage sintering process, so that the recycling of the lithium cobalt oxide fine powder is effectively realized, the reaction sufficiency of the raw material is improved, the content of cobalt oxide impurity phases in a finished product is reduced, and the electrical property of the finished product is effectively improved.
The first aspect of the invention provides a lithium cobalt oxide positive electrode material, wherein the content of cobalt oxide hetero-phase in the lithium cobalt oxide positive electrode material is 1100ppm-1700ppm, and lithium cobalt oxide fine powder existing in a free form is attached to the surface of the lithium cobalt oxide positive electrode material.
The content of the cobalt oxide impurity phase in the lithium cobaltate positive electrode material may be, but is not limited to, 1100ppm, 1150ppm, 1200ppm, 1250ppm, 1300ppm, 1350ppm, 1400ppm, 1450ppm, 1500ppm, 1550ppm, 1600ppm, 1650ppm, 1700ppm or a range between any two of the above values.
It is understood that when the content of the cobalt oxide hetero-phase in the lithium cobalt oxide positive electrode material is within the above range, the electrical properties of the lithium cobalt oxide positive electrode material can be improved. When the content of the cobalt oxide impurity phase is higher than 1700ppm, the capacity of the lithium ion battery is reduced; if the content of the cobalt oxide impurity phase is lower than 1100ppm, the improvement of the cycle stability of the lithium ion battery is not facilitated.
Meanwhile, the surface of the lithium cobalt oxide positive electrode material is also attached with lithium cobalt oxide fine powder existing in a free form, namely the lithium cobalt oxide fine powder exists in a form of being free or gathered on the surface of the lithium cobalt oxide positive electrode material, and the existence of the lithium cobalt oxide fine powder can improve the specific surface area, half-peak width and compaction density of the lithium cobalt oxide positive electrode material, so that the specific capacity, energy density and rate capability of the lithium cobalt oxide positive electrode material are improved.
In some embodiments, the average particle size D50 of the lithium cobaltate positive electrode material is 3 μm to 9 μm; for example, but not limited to, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, or a range between any two of the above values. When the average particle diameter D50 of the lithium cobaltate cathode material is within the above range, the rate performance of the cathode material can be ensured. The half-peak width is 1.3-1.9; when the half-width is within the above range, the compaction density of the lithium cobalt oxide positive electrode material is favorably improved, thereby increasing the energy density of the battery positive electrode.
In some embodiments, the lithium cobaltate positive electrode material has a specific surface area of 0.52 to 0.60m 2 /g; when the specific surface area of the lithium cobalt oxide positive electrode material is in the range, the number of channels for lithium ion intercalation and deintercalation can be ensured, and the capacity and the multiplying power performance of the positive electrode material can be brought into play.
In some embodiments, the lithium cobaltate positive electrode material has a compacted density of 3.34-3.6g/cm at 150MPa 3 The method comprises the steps of carrying out a first treatment on the surface of the When the compaction density of the lithium cobalt oxide anode material under 150MPa is in the range, the energy density of the battery anode can be ensured under the condition that the material structure is not damaged.
The half-width of the lithium cobaltate cathode material referred to in the present invention refers to the degree of vergence of the particle size distribution of the particles.
The second aspect of the invention provides a preparation method of the lithium cobalt oxide anode material of the first aspect of the invention, which comprises the following steps:
and (3) performing first-stage sintering treatment on the mixed material comprising the cobalt source, the lithium source and the lithium cobalt oxide fine powder, and performing second-stage sintering treatment after heating to prepare the lithium cobalt oxide positive electrode material.
It should be noted that the above-mentioned "first stage sintering process" and "second stage sintering process" are used for descriptive purposes only, and are not to be construed as indicating or implying a relative importance or quantity, nor as implying an importance or quantity of the indicated technical features.
When the mixture material is prepared, the lithium cobaltate fine powder, a cobalt source and a lithium source are added simultaneously to be used as preparation raw materials. The preparation raw materials can be uniformly mixed by a high-speed mixer to obtain a mixed material. When sintering treatment is carried out, the mixed materials can be put into a track kiln for sintering.
The lithium cobaltate fine powder is a lithium cobaltate byproduct having a small particle size and separated by a crushing device in a crushing step of a lithium cobaltate production process. The average particle diameter D50 of the lithium cobaltate fine powder is 1 μm to 3 μm.
The part of the lithium cobalt oxide fine powder added in the preparation process is attached to the surface of the material in a free form in the finally prepared lithium cobalt oxide positive electrode material, so that the specific surface area, half-peak width and compaction density of the prepared lithium cobalt oxide positive electrode material can be improved, and the specific capacity, energy density and multiplying power performance of the lithium cobalt oxide positive electrode material are further improved.
Understandably, the lithium cobaltate fine powder is used as the raw material for preparing the lithium cobaltate anode material, so that the recycling of the lithium cobaltate fine powder is realized, and the overall production cost of the lithium cobaltate is reduced; when the lithium cobalt oxide anode material is prepared, a two-stage sintering process is adopted, so that the reaction sufficiency of raw materials can be effectively improved, the impurity phase content of cobalt oxide in a product is reduced, and the electrical property of a finished product is effectively improved; the lithium cobaltate fine powder, the cobalt source and the lithium source are added simultaneously, so that the process complexity can be reduced, and the specific surface area, half-peak width and compaction density of the prepared lithium cobaltate positive electrode material can be improved; in addition, the preparation method of the lithium cobalt oxide positive electrode material can effectively improve the specific capacity, the energy density and the multiplying power performance of the 4.25V multiplying power lithium cobalt oxide material.
The preparation method of the lithium cobalt oxide positive electrode material provided by the invention has the advantages of simple process, low production cost, easiness in realizing mass production, and stable product, and can meet the requirements of the commercial lithium cobalt oxide industry.
The above-mentioned rate performance means charge and discharge performance at different currents, and the larger the capacity of high-rate charge and discharge, the better the rate performance of the battery.
In some embodiments, the temperature of the first stage sintering process is 500 ℃ to 900 ℃; for example, but not limited to, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃ or a range between any two of the above values. When the temperature of the first-stage sintering treatment is within the above range, the cobalt source and the lithium source are fully reacted and nucleated. The sintering treatment time in the first stage is 1h-5h; for example, but not limited to, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, or a range between any two of the foregoing values. When the time of the first-stage sintering treatment is within the range, the cobalt source and the lithium source can be reacted for a sufficient time, and the impurity phase retention of the cobalt oxide is effectively reduced.
In some embodiments, the temperature of the second stage sintering process is 950 ℃ to 1100 ℃; for example, but not limited to 950 ℃, 960 ℃, 970 ℃, 980 ℃, 990 ℃, 1000 ℃, 1010 ℃, 1020 ℃, 1030 ℃, 1040 ℃, 1050 ℃, 1060 ℃, 1070 ℃, 1080 ℃, 1090 ℃, 1100 ℃, or a range between any two of the above values. And when the temperature of the second-stage sintering treatment is within the range, the growth of lithium cobaltate crystal nucleus is facilitated. The sintering treatment time of the second stage is 4-9 h; for example, but not limited to, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, or a range between any two of the foregoing values. When the time of the second-stage sintering treatment is within the range, the lithium cobaltate crystal nucleus is favorable for being sufficiently grown and engulfed, the number of crystal grains and crystal boundaries is effectively reduced, and the electrical performance of the finished product is favorable for being exerted.
In some embodiments, the atmosphere of the first stage sintering process and the atmosphere of the second stage sintering process are each independently an air atmosphere.
As one possible embodiment, the mass of the lithium cobaltate powder is 0.1% -12% of the mass of the cobalt source; for example, the range may be, but not limited to, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12% or any range between any two of the above. When the mass of the lithium cobaltate fine powder accounts for the mass of the cobalt source, the lithium cobaltate fine powder can be effectively consumed, the problem that the lithium cobaltate fine powder is difficult to recycle is solved, the production cost is reduced, and the product stability can meet the requirements of the commercial lithium cobaltate industry.
In some embodiments, the molar ratio of elemental lithium contained in the lithium source to elemental cobalt contained in the cobalt source is 1-1.08:1; for example, but not limited to, 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1, or ranges between any two of the foregoing values. When the molar ratio of the lithium element contained in the lithium source to the cobalt element contained in the cobalt source is within the above range, the reaction can be ensured to be more sufficient by the trace excess of the lithium source, and the production of the finished cobalt oxide can be effectively reduced.
In some embodiments, the lithium source comprises one or more of lithium hydroxide, lithium carbonate, and lithium oxalate.
In some embodiments, the cobalt source comprises one or more of cobalt hydroxide, cobalt tetraoxide, cobalt oxide, cobalt carbonate, and cobalt oxyhydroxide.
In some alternative embodiments, the mixture further comprises an additive comprising one or more of an oxide, hydroxide, nitrate, sulfate, carbonate, and composite oxide comprising the metal element M.
Alternatively, the metal element M includes one or more of a transition metal, an alkaline earth metal, and a rare earth metal.
Optionally, the mass of the additive accounts for 1000ppm-4000ppm of the mass of the cobalt source; for example, the concentration of the catalyst may be, but is not limited to, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, or a range between any two of the above values.
In some embodiments, the method of making further comprises: and crushing the sintered material after the second-stage sintering treatment.
In some alternative embodiments, the crushing process is carried out by air stream crushing; the airflow crushing equipment is adopted to crush the sintered material, so that the half-peak width of the peak in the particle size distribution diagram of the lithium cobalt oxide positive electrode material can be further improved, the effect of improving the compaction density of the material is achieved, and the production cost is effectively reduced.
The third aspect of the invention provides a positive electrode sheet comprising the lithium cobalt oxide positive electrode material of the first aspect or prepared by the method of the second aspect.
A fourth aspect of the present invention provides a secondary battery comprising the positive electrode tab of the third aspect of the present invention. The secondary battery of the invention comprises the lithium cobalt oxide positive electrode material and has excellent electrochemical performance.
A fifth aspect of the invention provides an electric device comprising the secondary battery of the fifth aspect of the invention.
The following describes the technical scheme of the present invention in detail with reference to specific examples.
1. Preparation of cathode Material
Example 1
Weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), lithium cobaltate fine powder, magnesium oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer together for uniform mixing to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1.025:1, the mass of the lithium cobaltate fine powder accounts for 3 percent of the mass of the cobalt source, the mass content of magnesium oxide relative to the cobalt source is 1200ppm, and the mass content of titanium dioxide relative to the cobalt source is 2000ppm.
And (3) placing the mixed material in a kiln, and adopting a two-stage sintering process to perform sintering treatment, wherein the first-stage sintering treatment is performed at 600 ℃ for 300min, the second-stage sintering treatment is performed at 1000 ℃ for 270min, and air atmosphere is introduced during sintering to obtain the sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material.
As shown in FIG. 1, the particle size distribution diagram of the lithium cobalt oxide positive electrode material obtained in example 1 shows that the average particle size D50 of the lithium cobalt oxide positive electrode material obtained in example 1 was 6.273. Mu.m, and the half-width was 1.491.
The scanning electron microscope image of the lithium cobaltate cathode material prepared in example 1 is shown in fig. 2, and it can be seen from fig. 2 that the lithium cobaltate fine powder is attached to the surface of the material in a free form.
Example 2
Weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), lithium cobaltate fine powder, yttrium oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer together for uniform mixing to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1.025:1, the mass percentage of the lithium cobaltate fine powder to the cobalt source is 6%, the mass content of yttrium oxide to the cobalt source is 500ppm, and the mass content of titanium dioxide to the cobalt source is 2000ppm.
And (3) placing the mixed material in a kiln, and adopting a two-stage sintering process to perform sintering treatment, wherein the first-stage sintering treatment is performed at 800 ℃ for 250min, the second-stage sintering treatment is performed at 950 ℃ for 380min, and air atmosphere is introduced during sintering to obtain the sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material. Example 3
Weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), lithium cobaltate fine powder, lanthanum oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer together for uniform mixing to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1.025:1, the mass of the lithium cobaltate fine powder accounts for 9 percent of the mass of the cobalt source, the mass content of lanthanum oxide relative to the cobalt source is 1000ppm, and the mass content of titanium dioxide relative to the cobalt source is 2000ppm.
And (3) placing the mixed material in a kiln, and adopting a two-stage sintering process to perform sintering treatment, wherein the first-stage sintering treatment is performed at 900 ℃ for 200min, the second-stage sintering treatment is performed at 1080 ℃ for 450min, and air atmosphere is introduced during sintering to obtain the sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material. Example 4
Weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), lithium cobaltate fine powder, lanthanum oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer together for uniform mixing to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1.08:1, the mass percentage of the lithium cobaltate fine powder to the mass of the cobalt source is 12%, the mass content of lanthanum oxide to the cobalt source is 1000ppm, and the mass content of titanium dioxide to the cobalt source is 2000ppm.
And placing the mixed material in a kiln, and adopting a two-stage sintering process to perform sintering treatment, wherein the first-stage sintering treatment is performed at 500 ℃ for 300min, the second-stage sintering treatment is performed at 1100 ℃ for 240min, and air atmosphere is introduced during sintering to obtain the sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material. Example 5
Weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), lithium cobaltate fine powder, yttrium oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer together for uniform mixing to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1.025:1, the mass percentage of the lithium cobaltate fine powder to the mass of the cobalt source is 6%, the mass content of yttrium oxide to the cobalt source is 500ppm, and the mass content of titanium dioxide to the cobalt source is 2000ppm.
And (3) placing the mixed material in a kiln, and adopting a two-stage sintering process to perform sintering treatment, wherein the first-stage sintering treatment is performed at 800 ℃ for 250min, the second-stage sintering treatment is performed at 950 ℃ for 380min, and air atmosphere is introduced during sintering to obtain the sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material.
Comparative example 1
Weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), lanthanum oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer together for uniform mixing to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1:1, the mass content of lanthanum oxide relative to the cobalt source is 1000ppm, and the mass content of titanium dioxide relative to the cobalt source is 2000ppm.
And (3) placing the mixed material in a kiln, and adopting a two-stage sintering process to perform sintering treatment, wherein the first-stage sintering treatment is performed at 700 ℃ for 200min, the second-stage sintering treatment is performed at 950 ℃ for 540min, and air atmosphere is introduced during sintering to obtain the sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material. A scanning electron microscope image of the lithium cobaltate cathode material prepared in comparative example 1 is shown in FIG. 3. As can be seen from fig. 3, the surface of the material was smooth, and no lithium cobaltate fine powder was adhered.
Comparative example 2
Weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), lithium cobaltate fine powder, magnesium oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer together for uniform mixing to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1.025:1, the mass percentage of the lithium cobaltate fine powder to the mass of the cobalt source is 6%, the mass content of the magnesium oxide to the cobalt source is 1200ppm, and the mass content of the titanium dioxide to the cobalt source is 2000ppm.
And (3) placing the mixed material in a kiln, performing sintering treatment by adopting a one-stage sintering process, preserving the temperature at 1000 ℃ for 650min, and introducing air atmosphere during sintering to obtain a sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material.
Comparative example 3
The lithium cobaltate positive electrode material prepared in comparative example 3 is prepared by mixing a precursor material and then adding lithium cobaltate fine powder, and the specific preparation method is as follows:
weighing lithium carbonate (serving as a lithium source), cobaltosic oxide (serving as a cobalt source), yttrium oxide (serving as an additive) and titanium dioxide (serving as an additive), and adding the materials into a high-speed mixer to be uniformly mixed; adding the lithium cobaltate fine powder into the mixture, and continuously and uniformly mixing the mixture to prepare a mixed material; wherein the molar ratio of the lithium element contained in the lithium carbonate to the cobalt element contained in the cobaltosic oxide is 1.025:1, the mass percentage of the lithium cobaltate fine powder to the mass of the cobalt source is 6%, the mass content of yttrium oxide to the cobalt source is 500ppm, and the mass content of titanium dioxide to the cobalt source is 2000ppm.
And (3) placing the mixed material in a kiln, and adopting a two-stage sintering process to perform sintering treatment, wherein the first-stage sintering treatment is performed at 800 ℃ for 250min, the second-stage sintering treatment is performed at 950 ℃ for 380min, and air atmosphere is introduced during sintering to obtain the sintered material.
And (3) carrying out roller pair and crushing on the sintered material, and then carrying out demagnetizing and sieving to obtain the lithium cobaltate anode material. The structural parameters of the lithium cobaltate cathode materials prepared in the above examples and comparative examples are shown in table 1 below.
The detection method of granularity, compaction density and specific surface area adopts the method described in GBT 20252-2014 lithium cobaltate.
The detection method of cobalt oxide comprises the following steps: 1.00+/-0.02 g of lithium cobaltate anode sample to be measured is weighed, then the sample is transferred into a 100mL sample bottle by using 20-30mL high-purity water, then 15-20mL hydrochloric acid solution is added until the sample is dissolved, the solution is filtered, concentrated hydrochloric acid and perchloric acid are added, the volume is fixed, and the content of cobalt oxide impurity phase is detected by using inductively coupled plasma.
TABLE 1
As can be seen from comparison of the results of examples 1-5 and comparative example 2 in Table 1, the use of the two-stage sintering method can effectively improve the reaction sufficiency of the raw materials and reduce the content of the cobalt oxide impurity phase in the lithium cobalt oxide positive electrode material.
As can be seen from the comparison of the results of examples 1 to 4 and comparative example 1 in Table 1, the addition of the lithium cobaltate fine powder, the cobalt source and the lithium source simultaneously produced the lithium cobaltate cathode material, and the particle size distribution range of the lithium cobaltate cathode material was increased, thereby increasing the compacted density thereof.
2. Preparation of a Battery
Mixing the lithium cobaltate anode material with acetylene black (serving as a conductive agent) and polyvinylidene fluoride (PVDF (serving as a binder) uniformly according to a mass ratio of 95:2:3, adding N-methyl pyrrolidone (NMP) to prepare slurry, uniformly coating the slurry on one side surface of an aluminum foil, and taking out a pressed sheet and a cut piece after vacuum drying for 10 hours at 105 ℃ to prepare the anode sheet. By metalLithium sheet is used as negative electrode, and 1M LiPF is used as electrolyte 6 EC/DMC (volume ratio 1:1), assembling the battery in a glove box filled with argon and performing an electrical performance test on the battery using a battery performance tester. The charge-discharge cut-off voltage is 3-4.25V, and the charge-discharge multiplying power is 0.2C, 0.5C, 1C, 2C and 5C. The test results are shown in Table 2.
TABLE 2
As can be seen from comparison of the results of examples 1 to 4 and comparative example 1 in Table 2, the addition of the lithium cobaltate fine powder in the preparation of the lithium cobaltate positive electrode material according to the present invention can effectively improve the rate capability of the lithium cobaltate positive electrode material, and as can be seen from the results of Table 1, the compaction density of the lithium cobaltate positive electrode material can also be improved by the addition of the lithium cobaltate fine powder; the technician analyzing the cause may be due to: the added lithium cobaltate fine powder is not engulfed by the reaction process of lithium carbonate and cobaltosic oxide, but exists in a free form or in a form of being attached to the surface of a material, so that on one hand, the particle size distribution range of the lithium cobaltate positive electrode material can be effectively improved, the compaction density of the lithium cobaltate positive electrode material is increased, and the energy density of the battery positive electrode is improved; on the other hand, the specific surface area of the lithium cobalt oxide anode material can be increased simultaneously, so that more lithium ions can be allowed to be extracted and intercalated simultaneously in the charging and discharging process of the battery, and the rate capability of the battery is improved.
As is evident from comparison of the results of examples 1 to 4 and comparative example 2, the specific discharge capacity of the battery can be significantly improved by adopting the two-stage sintering process.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. The lithium cobalt oxide anode material is characterized in that the content of cobalt oxide hetero-phase in the lithium cobalt oxide anode material is 1100ppm-1700ppm, and lithium cobalt oxide fine powder existing in a free form is attached to the surface of the lithium cobalt oxide anode material.
2. The lithium cobalt oxide positive electrode material according to claim 1, wherein the lithium cobalt oxide positive electrode material has at least one of the following characteristics:
(1) The average particle diameter D50 of the lithium cobalt oxide positive electrode material is 3-9 mu m, and the half-peak width of the peak in the particle diameter distribution diagram is 1.45-1.60;
(2) The specific surface area of the lithium cobalt oxide positive electrode material is 0.52m 2 /g-0.60m 2 /g；
(3) The compaction density of the lithium cobalt oxide positive electrode material under 150MPa is 3.34m 2 /g-3.6g/cm 3 。
3. A method for producing a lithium cobalt oxide positive electrode material according to any one of claims 1 to 2, comprising the steps of:
and (3) performing first-stage sintering treatment on the mixed material comprising the cobalt source, the lithium source and the lithium cobalt oxide fine powder, and performing second-stage sintering treatment after heating to prepare the lithium cobalt oxide positive electrode material.
4. The method according to claim 3, wherein the first stage sintering treatment is carried out at a temperature of 500 ℃ to 900 ℃ for a time of 1h to 5h; and/or
The temperature of the second-stage sintering treatment is 950-1100 ℃ and the time is 4-9 h.
5. The method according to claim 3, wherein the mass of the lithium cobaltate fine powder is 0.1-12% of the mass of the cobalt source.
6. The method of preparing a lithium cobaltate cathode material according to claim 3, wherein the method of preparing a lithium cobaltate cathode material comprises at least one of the following conditions:
(1) The molar ratio of the lithium element contained in the lithium source to the cobalt element contained in the cobalt source is 1-1.08:1, a step of;
(2) The lithium source comprises one or more of lithium hydroxide, lithium carbonate and lithium oxalate;
(3) The cobalt source comprises one or more of cobalt hydroxide, cobaltosic oxide, cobalt carbonate and cobalt oxyhydroxide;
(4) The mixture further comprises an additive, wherein the additive comprises one or more of an oxide, a hydroxide, a nitrate, a sulfate, a carbonate and a composite oxide containing a metal element M;
optionally, the metal element M includes one or more of a transition metal, an alkaline earth metal, and a rare earth metal;
optionally, the mass of the additive accounts for 1000ppm-4000ppm of the mass of the cobalt source.
7. A method of preparing according to claim 3, further comprising: crushing the sintered material after the second-stage sintering treatment;
optionally, the crushing treatment is performed by air stream crushing.
8. A positive electrode sheet, characterized by comprising the lithium cobalt oxide positive electrode material according to any one of claims 1 to 2 or prepared by the method according to any one of claims 3 to 7.
9. A secondary battery comprising the positive electrode tab of claim 8.
10. An electric device comprising the secondary battery according to claim 9.
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