CN111029535A - Composite positive electrode material of lithium ion battery and preparation method thereof - Google Patents
Composite positive electrode material of lithium ion battery and preparation method thereof Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims abstract description 65
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 239000007774 positive electrode material Substances 0.000 title claims description 17
- 239000000463 material Substances 0.000 claims abstract description 70
- 239000011247 coating layer Substances 0.000 claims abstract description 42
- IIZCGXHPYXZBRV-UHFFFAOYSA-N [Li+].B([O-])([O-])[O-].[Co+2] Chemical compound [Li+].B([O-])([O-])[O-].[Co+2] IIZCGXHPYXZBRV-UHFFFAOYSA-N 0.000 claims abstract description 38
- 239000001301 oxygen Substances 0.000 claims abstract description 25
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 24
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 20
- 239000010405 anode material Substances 0.000 claims abstract description 15
- 239000003153 chemical reaction reagent Substances 0.000 claims abstract description 13
- 239000007788 liquid Substances 0.000 claims abstract description 13
- 238000002156 mixing Methods 0.000 claims abstract description 13
- 238000000227 grinding Methods 0.000 claims abstract description 12
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 11
- 229910052796 boron Inorganic materials 0.000 claims abstract description 10
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000011737 fluorine Substances 0.000 claims abstract description 9
- 238000001694 spray drying Methods 0.000 claims abstract description 9
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 8
- 239000010941 cobalt Substances 0.000 claims abstract description 8
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims abstract description 7
- 238000005245 sintering Methods 0.000 claims abstract description 7
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 42
- 238000000034 method Methods 0.000 claims description 26
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 18
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 16
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 10
- 239000004327 boric acid Substances 0.000 claims description 10
- 229940011182 cobalt acetate Drugs 0.000 claims description 10
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 10
- 229910032387 LiCoO2 Inorganic materials 0.000 claims description 8
- 229910002099 LiNi0.5Mn1.5O4 Inorganic materials 0.000 claims description 8
- 229910002097 Lithium manganese(III,IV) oxide Inorganic materials 0.000 claims description 8
- QEWYKACRFQMRMB-UHFFFAOYSA-N fluoroacetic acid Chemical compound OC(=O)CF QEWYKACRFQMRMB-UHFFFAOYSA-N 0.000 claims description 8
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 8
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 8
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 6
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 6
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 6
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims description 4
- 229910014333 LiNi1-x-yCoxMyO2 Inorganic materials 0.000 claims description 4
- 229910014832 LiNi1−x−yCoxMyO2 Inorganic materials 0.000 claims description 4
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 4
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims description 4
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 claims description 4
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 claims description 4
- RIUWBIIVUYSTCN-UHFFFAOYSA-N trilithium borate Chemical compound [Li+].[Li+].[Li+].[O-]B([O-])[O-] RIUWBIIVUYSTCN-UHFFFAOYSA-N 0.000 claims description 4
- 229910021503 Cobalt(II) hydroxide Inorganic materials 0.000 claims description 3
- 229910021446 cobalt carbonate Inorganic materials 0.000 claims description 3
- 229910000428 cobalt oxide Inorganic materials 0.000 claims description 3
- 229940044175 cobalt sulfate Drugs 0.000 claims description 3
- 229910000361 cobalt sulfate Inorganic materials 0.000 claims description 3
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 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
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims description 3
- VCYZVXRKYPKDQB-UHFFFAOYSA-N ethyl 2-fluoroacetate Chemical compound CCOC(=O)CF VCYZVXRKYPKDQB-UHFFFAOYSA-N 0.000 claims description 3
- RJBYSQHLLIHSLT-UHFFFAOYSA-N methyl 2-fluoroacetate Chemical compound COC(=O)CF RJBYSQHLLIHSLT-UHFFFAOYSA-N 0.000 claims description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 2
- 230000014759 maintenance of location Effects 0.000 description 33
- 238000012360 testing method Methods 0.000 description 32
- 239000002585 base Substances 0.000 description 27
- 238000000576 coating method Methods 0.000 description 14
- 239000000758 substrate Substances 0.000 description 13
- 229910013716 LiNi Inorganic materials 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 10
- 239000010406 cathode material Substances 0.000 description 9
- 239000000126 substance Substances 0.000 description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 229910011456 LiNi0.80Co0.15Al0.05O2 Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 238000001354 calcination Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical group [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 229910002991 LiNi0.5Co0.2Mn0.3O2 Inorganic materials 0.000 description 2
- 229910011328 LiNi0.6Co0.2Mn0.2O2 Inorganic materials 0.000 description 2
- 229910015746 LiNi0.88Co0.09Al0.03O2 Inorganic materials 0.000 description 2
- 229910015872 LiNi0.8Co0.1Mn0.1O2 Inorganic materials 0.000 description 2
- 229910001228 Li[Ni1/3Co1/3Mn1/3]O2 (NCM 111) Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007580 dry-mixing Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000010416 ion conductor Substances 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910001512 metal fluoride Inorganic materials 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 229910001463 metal phosphate Inorganic materials 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- -1 oxygen ions Chemical class 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- 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)
- Composite Materials (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a composite anode material of a lithium ion battery, which comprises an anode base material and a lithium cobalt borate coating layer. The invention also provides a preparation method of the lithium ion battery composite anode material, which comprises the following steps: adding a cobalt source, a boron source and a fluorine source into a liquid reagent according to a molar ratio (1-B) of Co to B to F, wherein B is more than or equal to 0 and less than or equal to 0.9, grinding and mixing uniformly, then adding a positive electrode base material, grinding and mixing uniformly, adding a lithium source, grinding and mixing uniformly, and performing spray drying to obtain a mixture; and sintering the mixture for 2-20 h at 400-1100 ℃ in an oxygen-containing atmosphere to obtain the lithium ion battery composite anode material comprising the anode base material and the lithium cobalt borate coating layer.
Description
Technical Field
The invention belongs to the technical field of lithium battery anode materials, and particularly relates to a lithium ion battery composite anode material and a preparation method thereof.
Background
With the rapid development of portable electronic devices and electric vehicles, the market demand of lithium ion batteries is increasing, and as one of core materials of lithium ion batteries, the demand of cathode materials is also increasing. The surface structure stability and surface residual lithium of the anode material, such as lithium hydroxide and lithium carbonate, bring some hidden troubles to the service life and safety of the lithium ion battery, especially the surface residual lithium of the high nickel ternary material (the mole fraction of Ni is more than or equal to 0.6) is high, and the structure stability is also poor. Therefore, it is necessary to develop methods for improving the surface structure stability of the cathode material, and at the same time, the method can reduce the residual alkali and can not cause the electrochemical performance of the material to be reduced.
Coating is a method for improving the surface structure stability of the cathode material, for example, patent with application number CN200810216339 discloses a lithium cobaltate composite cathode material and a preparation method thereof, and a secondary lithium ion battery, wherein the matrix material is lithium cobaltate, and the coating layer is lithium manganate. For another example, patent application No. CN201510067722 discloses a coating modification method for a lithium ion battery cathode material, in which a material completely the same as a base material is used as a coating layer, such as lithium cobaltate coated lithium cobaltate, lithium manganate coated lithium manganate, and the like. For another example, patent application No. CN201611200002 discloses a coated lithium ion battery cathode material and a preparation method thereof, in which a high nickel activity cathode material is coated in a metal oxide and/or a lithium ion conductor compound.
The coating method is roughly divided into two methods, one is to coat a layer of metal oxide, fluoride or phosphate on the surface of the material, which can reduce the side reaction of the electrolyte and the positive electrode material, thereby improving the cycle performance and the safety performance, but the coating method usually adopts a method of dry mixing and then secondary sintering, realizes point coating, cannot isolate the contact of the electrolyte and the positive electrode material, and can cause the reduction of the capacity of the material if the usage amount is slightly more; in another coating method, wet coating is performed in solvents such as ethanol, methanol, water and the like, the coating uniformity of the method is good, but the solvent is usually removed by stirring and drying, the efficiency is low, the recovery of the solvent is difficult, the coated particles on the surface are large, and the reaction can be completed only by high secondary sintering temperature.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a composite positive electrode material of a lithium ion battery, which comprises a positive electrode base material and a lithium cobalt borate coating layer. The positive electrode substrate material is coated and compounded by the lithium cobalt borate coating layer, so that the rate performance and the cycle life of the material are obviously improved, residual lithium on the surface of the material is reduced to a certain extent, and the capacity, the coulombic efficiency, the safety performance and the like of the material are effectively improved.
The invention also aims to provide a preparation method of the composite cathode material of the lithium ion battery.
In order to achieve the purpose, the invention adopts the following technical scheme:
a composite anode material of a lithium ion battery comprises an anode base material and a lithium cobalt borate coating layer; the anode matrix material is LiCoO2、LiNi1-x-yCoxMyO2、LiMn2O4、LiNi0.5Mn1.5O4Wherein M is at least one of Al and Mn, 0<x≤0.5，0<y≤0.5，0<x + y is less than or equal to 0.8; the lithium cobalt borate coating layer has a general formula of LiaCo1- bBbO2-c/2Fc0.5-1.2, 0<b≤0.9，0≤c≤0.1。
Further, the mass fraction of the lithium cobalt borate coating layer in the lithium ion battery composite positive electrode material is 0.1-20%, preferably 0.1-10%.
Further, the median particle diameter D of the positive electrode base material50Not more than 20 μm, preferably not more than 15 μm.
A preparation method of the composite anode material of the lithium ion battery comprises the following steps:
adding a cobalt source, a boron source and a fluorine source into a liquid reagent according to a molar ratio (1-B) of Co to B to F, wherein B is more than or equal to 0 and less than or equal to 0.9, grinding and mixing uniformly, then adding a positive electrode base material, grinding and mixing uniformly, adding a lithium source, grinding and mixing uniformly, and performing spray drying to obtain a mixture;
and sintering the mixture for 2-20 h at 400-1100 ℃ in an oxygen-containing atmosphere to obtain the lithium ion battery composite anode material comprising the anode base material and the lithium cobalt borate coating layer.
Further, the lithium source is one or more of lithium hydroxide, lithium carbonate, lithium acetate, lithium sulfate or lithium nitrate, wherein the addition amount of the lithium source is controlled according to the amount of the lithium cobalt borate coating layer.
Further, the cobalt source is one or more of cobalt hydroxide, cobalt oxide, cobalt nitrate, cobalt carbonate, cobalt sulfate or cobalt acetate.
Further, the boron source is one or more of boric acid and lithium borate.
Further, the fluorine source is one or more of hydrofluoric acid, lithium fluoride, ammonium fluoride, fluoroacetic acid, methyl fluoroacetate, and ethyl fluoroacetate.
Further, the positive electrode matrix material is LiCoO2、LiNi1-x-yCoxMyO2、LiMn2O4、LiNi0.5Mn1.5O4One or more of, 0<x≤0.5，0<y≤0.5，0<x+y≤0.8。
Further, the mass fraction of the lithium cobalt borate coating layer in the lithium ion battery composite positive electrode material is 0.1-20%, preferably 0.1-10%.
Further, the liquid reagent is one or more of water, ethanol, methanol, propanol and isopropanol.
Further, the mass ratio z of the liquid reagent to the positive electrode base material is: 0.1< z <15, preferably 0.5< z < 3.
Further, the concentration of oxygen in the oxygen-containing atmosphere is not less than 20%, the remaining gas component of the oxygen-containing atmosphere is nitrogen, the concentration of oxygen is selected according to the kind of the positive electrode base material, and for LiNi1-x-yCoxMyO2，0<x + y is less than or equal to 0.4, the concentration of oxygen is not less than 50%, and the concentration of oxygen used in the rest of the anode base material is 20-50%.
The invention provides a composite anode material of a lithium ion battery, which is characterized in that a lithium cobalt borate coating layer is coated on the surface of an anode base material. The invention also provides a preparation method of the lithium ion battery anode material, wherein a cobalt source, a boron source, a fluorine source and a lithium source are uniformly coated on the surface of the anode base material by a spray drying method, and a lithium cobalt borate coating layer is formed after secondary sintering. According to the coating method, the lithium cobalt borate coating layer can be infiltrated into the internal pores of the anode base material in the preparation process by mixing in the liquid reagent, and is not limited to the surface, so that uniform and complete coating is realized, and the improvement of the cycle performance, the storage performance and the safety performance of the anode base material is facilitated. Compared with the traditional mode of removing the solvent by heating and evaporating, the spray drying method can obtain coating substances with finer particles, is favorable for forming more uniform coating layers in the secondary sintering process, has higher spray drying speed, is easy to recover the used liquid reagent, and has great advantages in the aspects of price and capacity. The spray drying method is suitable for liquid phase coating of the cathode material, and the coating is not limited to lithium cobalt borate.
The positive electrode material combines the advantages of a positive electrode base material and a lithium cobalt borate coating layer, forms surface micro-doping of Co, B and F on the positive electrode base material, and forms uniform and complete coating on the inner pores and the surface of the positive electrode base material, thereby generating an enhanced synergistic effect. The composite anode material has the following advantages:
(1) the invention takes spray drying as a method, and can form a very uniform and complete coating layer on the anode substrate material, thereby improving the storage performance and the safety performance of the material and being beneficial to improving the cycle life.
(2) The lithium cobalt borate coating layer formed on the positive electrode base material has high electrochemical activity, the electronic conductivity and the lithium ion diffusion rate of the lithium cobalt borate coating layer are high, and abundant variable valence ions can be provided for the positive electrode base material, so that more active lithium can be extracted and embedded, and the rate capability, the coulombic efficiency and the charge-discharge capacity of the material are effectively improved.
(3) The invention can remove residual lithium such as lithium hydroxide and lithium carbonate on the surface of the anode base material to a certain extent, and improves the storage performance and the safety performance of the material.
(4) The lithium cobalt borate coating layer formed in the invention is doped with fluorine, and meanwhile, the surface micro-doping of Co, B and F is formed on the anode base material in the preparation process, the existence of Co is beneficial to inhibiting the mixed arrangement of surface lithium ions, the existence of B can improve the diffusion rate of the surface ions, the existence of F can enhance the stability of a lattice structure formed by metal ions and oxygen ions, can also reduce the charge transfer resistance and improve the conductivity, and the lithium cobalt borate coating layer and the anode base material generate an enhanced synergistic effect, so that the rate capability and the cycle performance of the material are well improved.
Drawings
Fig. 1 is an SEM image of the sample before modification in example 1.
Fig. 2 is an SEM image of the spray dried sample in example 1.
Fig. 3 is an SEM image of the sample after modification in example 1.
FIG. 4 is a graph of rate performance for samples before and after the improvement in example 1.
FIG. 5 is a 100-cycle performance curve for the samples before and after the improvement in example 1.
Detailed Description
In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.
The following examples, in which the method of the present invention is used to prepare the lithium ion battery composite positive electrode material to be protected, specifically include:
example 1
The anode base material selects LiNi with the median particle diameter of about 10 mu m0.8Co0.1Mn0.1O2The sample, i.e., the sample before modification, is shown in FIG. 1.
Adding 0.06mol of cobalt acetate, 0.04mol of boric acid and 0.002mol of hydrofluoric acid into 150g of ethanol, grinding and mixing uniformly, and then adding 1mol of LiNi0.8Co0.1Mn0.1O2And grinding and mixing uniformly, then adding 0.08mol of lithium hydroxide, grinding and mixing uniformly, and then carrying out spray drying to obtain a mixture, namely a spray-dried sample, as shown in figure 2. Calcining the spray-dried sample at 700 ℃ for 10h in an atmosphere of 99.5 percent oxygen to obtain Li0.8Co0.6B0.4O1.99F0.02Coated LiNi0.8Co0.1Mn0.1O2The composite positive electrode material is characterized in that the mass fraction of the lithium cobalt borate coating layer in the composite positive electrode material is about 7.4%. As shown in fig. 3, a uniform lithium cobalt borate coating layer was observed on the surface of the sample to improve the morphology of the sample. In this example, the mass ratio c of the liquid reagent to the positive electrode base material was 1.5.
The materials before and after the improvement are made into pole pieces which are used as working electrodes to assemble a half-cell, the cell is subjected to charge and discharge tests, the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks. The rate performance curve of the sample is shown in fig. 4, and it can be seen that the rate performance of the sample after improvement is obviously improved. The cycle performance is shown in fig. 5, and it can be seen that the cycle performance of the improved sample is also improved to some extent.
Example 2
Following example 1 except that no hydrofluoric acid was added, a composite was obtained in which the lithium cobalt borate coating layer had the chemical formula Li0.8Co0.6B0.4O2. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 3
Following example 1 except that the amount of hydrofluoric acid was changed to 0.01mol, the chemical formula of the lithium cobalt borate coating layer in the obtained composite was Li0.8Co0.6B0.4O1.95F0.1. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 4
Following example 1 except that boric acid was not added, the amount of cobalt acetate added was changed to 0.1mol, and the chemical formula of the lithium cobalt borate coating layer in the obtained composite was Li0.8Co1.0O1.99F0.02. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 5
Following example 1 except that the amount of cobalt acetate added was changed to 0.01mol and the amount of boric acid was changed to 0.09mol, the chemical formula of the lithium cobalt borate coating layer in the resulting composite was Li0.8Co0.1B0.9O1.99F0.02. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 6 to 7
Following example 1 except that the amounts of lithium hydroxide added were changed to 0.05mol and 0.12mol, respectively, a composite was obtained in which the chemical formulas of the lithium cobalt borate coating layers were Li, respectively0.5Co0.6B0.4O1.99F0.02And Li1.2Co0.6B0.4O1.99F0.02. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 8 to 9
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Respectively replaced with a considerable amount of LiNi1/3Co1/3Mn1/3O2And LiNi0.5Co0.2Mn0.3O2Wherein the particle diameters are about 10 μm, and oxygen atmosphere with concentration of 20% is used. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 10
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Substitution with a considerable amount of LiNi0.6Co0.2Mn0.2O2The median particle diameter was about 10 μm, and an oxygen atmosphere with a concentration of 50% was used. Will be provided withThe obtained composite material is used as a working electrode to be assembled into a half-cell, and the charge-discharge test is carried out on the cell, wherein the voltage range is 2.8-4.25V, the first-week charge-discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 11 to 13
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Successively replacing with a considerable amount of LiNi0.88Co0.09Mn0.03O2、LiNi0.80Co0.15Al0.05O2、LiNi0.88Co0.09Al0.03O2Wherein the particle sizes are all about 10 μm, and the oxygen concentration is unchanged. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 14
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Replacement by a considerable amount of LiCoO2The median particle diameter was about 10 μm, and an oxygen atmosphere having a concentration of 20% was used. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 3.0-4.35V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 15
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Substitution with a considerable amount of LiNi0.5Mn1.5O4The median particle diameter was about 10 μm, and an oxygen atmosphere having a concentration of 20% was used. Assembling the obtained composite material as a working electrode into a half cell, and performing charge-discharge test on the cellThe voltage range is 3.0-4.4V, the first-week charge-discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 16
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Replacement by a considerable amount of LiMn2O4The median particle diameter was about 10 μm, and an oxygen atmosphere having a concentration of 20% was used. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 3.5-4.8V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 17
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Replacement with LiNi0.80Co0.15Al0.05O2And LiMn2O4The materials are mixed according to the ratio of 2:1, the total amount of the mixed materials is 1mol, the median particle diameter is about 10 mu m, and the oxygen concentration is unchanged. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 18
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2Replacement with LiNi0.88Co0.09Mn0.03O2、LiCoO2、LiNi0.5Mn1.5O4The materials are mixed according to the ratio of 1:1:1, the total amount of the mixed materials is 1mol, the median particle diameter is about 10 mu m, and the oxygen concentration is unchanged. The obtained composite material is used as a working electrode to assemble a half battery, and the battery is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25VThe first-week charge-discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 19
By following example 1 except that the amounts of cobalt acetate, boric acid, hydrofluoric acid and lithium hydroxide added were changed to 0.00075mol, 0.0005mol, 0.000025mol and 0.001mol, respectively, the mass fraction of the lithium cobalt borate coating layer in the composite material was about 0.1%. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 20
The mass fraction of the lithium cobalt borate coating layer in the composite material was about 20% by following example 1 except that the amounts of cobalt acetate, boric acid, hydrofluoric acid, and lithium hydroxide added were changed to 0.189mol, 0.126mol, 0.0063mol, and 0.25mol, respectively. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 21
Following example 1, the positive electrode substrate material LiNi was used0.8Co0.1Mn0.1O2The median particle diameter of (2) is about 20 μm. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 22 to 25
The method is similar to example 1 except that lithium hydroxide is replaced by lithium carbonate, lithium acetate, lithium sulfate and lithium nitrate respectively, wherein the amount of the lithium acetate and the lithium nitrate is 0.08mol, and the amount of the lithium carbonate and the lithium sulfate is 0.04 mol. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 26
Following example 1, except that lithium hydroxide was changed to a lithium source in which lithium hydroxide and lithium acetate were mixed in a ratio of 1:1, the amount of lithium source added was kept constant. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 27 to 31
The method is similar to example 1 except that cobalt acetate is replaced by equivalent amounts of cobalt hydroxide, cobalt oxide, cobalt nitrate, cobalt carbonate and cobalt sulfate. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 32
The procedure of example 1 was followed except that cobalt acetate was changed to a cobalt source in which cobalt acetate and cobalt nitrate were mixed in a ratio of 1:1, and the amount of the cobalt source added was kept constant. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 33
Following example 1, except that boric acid was changed to a corresponding amount of lithium borate and no lithium hydroxide was added, a composite was obtained in which the lithium cobalt borate coating layer was formedHas a chemical formula of Li1.2Co0.6B0.4O1.99F0.02. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 34 to 38
The procedure of example 1 was followed except that hydrofluoric acid was replaced with equivalent amounts of lithium fluoride, ammonium fluoride, fluoroacetic acid, methyl fluoroacetate, and ethyl fluoroacetate, respectively, wherein, when lithium fluoride was used, the amount of lithium hydroxide added was replaced with 0.078mol, and the remainder was kept unchanged. The chemical formula of the lithium cobalt borate coating layer in the obtained compound is Li0.8Co0.6B0.4O1.99F0.02. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 39
Following example 1, except that hydrofluoric acid was changed to a fluorine source in which ammonium fluoride and fluoroacetic acid were mixed in a ratio of 1:1, the amount of fluorine source added was kept constant. The chemical formula of the lithium cobalt borate coating layer in the obtained compound is Li0.8Co0.6B0.4O1.99F0.02. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 40 to 43
The procedure of example 1 was followed except that ethanol was exchanged for a corresponding amount of water, methanol, propanol, isopropanol, respectively. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 44
As in example 1, except that ethanol was changed to a liquid reagent in which ethanol and water were mixed in a ratio of 1:1, the amount of the liquid reagent added was kept constant. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 45 to 46
The procedure is as in example 1, except that 150g of ethanol are exchanged for 10g or 1500 g. In the examples, the mass ratio c of the liquid reagent to the positive electrode base material was 0.1 and 15, respectively. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 47 to 48
Example 1 was followed except that the calcination temperatures were adjusted to 400 ℃ and 1100 ℃, respectively. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Examples 49 to 50
The example 1 is followed, except that the calcination times are adjusted to 2h and 20h, respectively. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
Example 51
Following example 1, except that boric acid was changed to a boron source in which boric acid and lithium borate were mixed in a ratio of 1:1, the amount of the boron source added was kept constant, and the amount of lithium hydroxide added was changed to 0.02 mol. The obtained composite material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
To fully illustrate the advancement of the composite positive electrode material of the present invention and the method of preparing the same, a number of comparative examples are listed below:
comparative examples 1 to 12
Using LiNi as a positive electrode base material0.8Co0.1Mn0.1O2、LiNi1/3Co1/3Mn1/3O2、LiNi0.5Co0.2Mn0.3O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.88Co0.09Mn0.03O2、LiNi0.80Co0.15Al0.05O2、LiNi0.88Co0.09Al0.03O2、LiCoO2、LiNi0.5Mn1.5O4、LiMn2O4、LiNi0.80Co0.15Al0.05O2:LiMn2O42:1 hybrid material, LiNi0.88Co0.09Mn0.03O2:LiCoO2:LiNi0.5Mn1.5O4The comparative examples 1 to 12 were made of 1:1:1 mixed materials, and the median particle diameters were all around 10 μm. Assembling a half cell by using a positive electrode substrate material as a working electrode, and carrying out charge and discharge tests on the cell, wherein the voltage ranges of comparative examples 1-7, 11 and 12 are 2.8-4.25V, the voltage range of comparative example 8 is 3.0-4.35V, the voltage range of comparative example 9 is 3.0-4.4V, and the voltage range of comparative example 10 is 3.5-4.8V, the first-week charge and discharge curves, the second-week charge and discharge curves and the second-week charge curves are all tested at 0.1C/0.1C, 0.2C/0.2C and 0.2C/1C respectivelyThe 100-week cycle capacity retention was tested at 1C/1C.
Comparative example 13
LiNi, a positive electrode base material having a median particle diameter of about 20 μm, was used0.8Co0.1Mn0.1O2As comparative example 13. The positive electrode base material is used as a working electrode to assemble a half-cell, and the cell is subjected to charge and discharge tests, wherein the voltage range is 2.8-4.25V, the first-week charge and discharge curve is tested at 0.1C/0.1C, the rate performance is tested at 0.1C/0.1C two weeks, 0.2C/0.2C two weeks and 0.2C/1C two weeks, and the cycle capacity retention rate is tested at 1C/1C for 100 weeks.
The electrochemical cycling results of the above examples and comparative examples are shown in table 1, wherein the specific charge/discharge capacity is the charge/discharge capacity/mass of the composite electrode material:
TABLE 1 electrochemical cycling data
As can be seen from the above table, the lithium ion battery composite positive electrode material to be protected prepared by the method provided by the present invention has better charge-discharge specific capacity, coulombic efficiency and capacity retention rate than the positive electrode material prepared by the prior art in the comparative example, and has better effect. The reason is that the material improved according to the technical scheme of the invention can uniformly coat a lithium cobalt borate coating layer on the surface of the anode substrate material, the lithium cobalt borate coating layer has certain electrochemical activity, and the existence of the coating layer improves the surface structure stability and the charge transfer characteristic of the material, thereby improving the capacity and the cycle performance to a certain extent.
The above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and a person skilled in the art can modify the technical solution of the present invention or substitute the same without departing from the spirit and scope of the present invention, and the scope of the present invention should be determined by the claims.
Claims (10)
1. A composite anode material of a lithium ion battery comprises an anode base material and a lithium cobalt borate coating layer; the anode matrix material is LiCoO2、LiNi1-x-yCoxMyO2、LiMn2O4、LiNi0.5Mn1.5O4Wherein M is at least one of Al and Mn, 0<x≤0.5，0<y≤0.5，0<x + y is less than or equal to 0.8; the lithium cobalt borate coating layer has a general formula of LiaCo1- bBbO2-c/2Fc0.5-1.2, 0<b≤0.9，0≤c≤0.1。
2. The lithium ion battery composite positive electrode material according to claim 1, wherein the lithium cobalt borate coating layer accounts for 0.1 to 20% by mass, preferably 0.1 to 10% by mass of the lithium ion battery composite positive electrode material.
3. The lithium ion battery composite positive electrode material of claim 1, wherein the median particle diameter D of the positive electrode base material50Not more than 20 μm, preferably not more than 15 μm.
4. A preparation method of the composite anode material of the lithium ion battery comprises the following steps:
adding a cobalt source, a boron source and a fluorine source into a liquid reagent according to a molar ratio (1-B) of Co to B to F, wherein B is more than or equal to 0 and less than or equal to 0.9, grinding and mixing uniformly, then adding a positive electrode base material, grinding and mixing uniformly, adding a lithium source, grinding and mixing uniformly, and performing spray drying to obtain a mixture;
and sintering the mixture for 2-20 h at 400-1100 ℃ in an oxygen-containing atmosphere to obtain the lithium ion battery composite anode material comprising the anode base material and the lithium cobalt borate coating layer.
5. The method according to claim 4, wherein the lithium source is one or more of lithium hydroxide, lithium carbonate, lithium acetate, lithium sulfate, or lithium nitrate, wherein the amount of the lithium source added is controlled according to the amount of the lithium cobalt borate coating layer; the cobalt source is one or more of cobalt hydroxide, cobalt oxide, cobalt nitrate, cobalt carbonate, cobalt sulfate or cobalt acetate; the boron source is one or more of boric acid and lithium borate; the fluorine source is one or more of hydrofluoric acid, lithium fluoride, ammonium fluoride, fluoroacetic acid, methyl fluoroacetate and ethyl fluoroacetate.
6. The method of claim 4, wherein the positive matrix material is LiCoO2、LiNi1-x- yCoxMyO2、LiMn2O4、LiNi0.5Mn1.5O4Wherein 0 is<x≤0.5，0<y≤0.5，0<x+y≤0.8。
7. The method of claim 4, wherein the liquid reagent is one or more of water, ethanol, methanol, propanol, isopropanol.
8. The method of claim 4, wherein the mass ratio z of the liquid reagent to the positive electrode base material is: 0.1< z <15, preferably 0.5< z < 3.
9. The method of claim 4, wherein the oxygen-containing atmosphere has an oxygen concentration of not less than 20% and the remaining gas component of the oxygen-containing atmosphere is nitrogen.
10. The method of claim 9, wherein the concentration of oxygen is selected based on the type of positive electrode matrix material for LiNi1-x-yCoxMyO2，0<x + y is less than or equal to 0.4, the concentration of oxygen is not less than 50%, and the concentration of oxygen used in the rest of the anode base material is 20-50%.
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| CN113809287A (en) * | 2020-06-15 | 2021-12-17 | 天津国安盟固利新材料科技股份有限公司 | Washing-free coating method for high-nickel anode material |
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