CN110620214B - Lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material, and preparation method and application thereof - Google Patents
Lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material, and preparation method and application thereof Download PDFInfo
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 62
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 60
- 239000002131 composite material Substances 0.000 title claims abstract description 60
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 53
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 52
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 43
- 238000002360 preparation method Methods 0.000 title claims abstract description 28
- 239000002245 particle Substances 0.000 claims abstract description 81
- 238000000034 method Methods 0.000 claims abstract description 48
- 239000007921 spray Substances 0.000 claims abstract description 31
- 239000000463 material Substances 0.000 claims abstract description 30
- 238000000227 grinding Methods 0.000 claims abstract description 24
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- 239000011247 coating layer Substances 0.000 claims abstract description 7
- 239000002296 pyrolytic carbon Substances 0.000 claims abstract description 5
- 239000002002 slurry Substances 0.000 claims description 44
- 238000001694 spray drying Methods 0.000 claims description 35
- 239000002243 precursor Substances 0.000 claims description 25
- 239000012298 atmosphere Substances 0.000 claims description 22
- 239000011248 coating agent Substances 0.000 claims description 19
- 238000000576 coating method Methods 0.000 claims description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 229910001416 lithium ion Inorganic materials 0.000 claims description 16
- 238000005469 granulation Methods 0.000 claims description 15
- 230000003179 granulation Effects 0.000 claims description 15
- 239000000843 powder Substances 0.000 claims description 14
- 239000007774 positive electrode material Substances 0.000 claims description 13
- 239000007787 solid Substances 0.000 claims description 13
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims description 12
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 11
- 239000005955 Ferric phosphate Substances 0.000 claims description 9
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 9
- 229940032958 ferric phosphate Drugs 0.000 claims description 9
- 229910000399 iron(III) phosphate Inorganic materials 0.000 claims description 9
- 239000012300 argon atmosphere Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 7
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- 239000002994 raw material Substances 0.000 claims description 7
- 239000002270 dispersing agent Substances 0.000 claims description 6
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 6
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 4
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- IMQLKJBTEOYOSI-GPIVLXJGSA-N Inositol-hexakisphosphate Chemical compound OP(O)(=O)O[C@H]1[C@H](OP(O)(O)=O)[C@@H](OP(O)(O)=O)[C@H](OP(O)(O)=O)[C@H](OP(O)(O)=O)[C@@H]1OP(O)(O)=O IMQLKJBTEOYOSI-GPIVLXJGSA-N 0.000 claims description 4
- IMQLKJBTEOYOSI-UHFFFAOYSA-N Phytic acid Natural products OP(O)(=O)OC1C(OP(O)(O)=O)C(OP(O)(O)=O)C(OP(O)(O)=O)C(OP(O)(O)=O)C1OP(O)(O)=O IMQLKJBTEOYOSI-UHFFFAOYSA-N 0.000 claims description 4
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 4
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- 239000001307 helium Substances 0.000 claims description 4
- 229910052734 helium Inorganic materials 0.000 claims description 4
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 4
- 229910052743 krypton Inorganic materials 0.000 claims description 4
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 claims description 4
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 claims description 4
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 4
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 4
- 229910052754 neon Inorganic materials 0.000 claims description 4
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 claims description 4
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- 229940068041 phytic acid Drugs 0.000 claims description 4
- 229910052724 xenon Inorganic materials 0.000 claims description 4
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 3
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- 239000011246 composite particle Substances 0.000 claims description 2
- 239000010450 olivine Substances 0.000 claims description 2
- 229910052609 olivine Inorganic materials 0.000 claims description 2
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- 238000005056 compaction Methods 0.000 abstract description 11
- 239000013543 active substance Substances 0.000 abstract description 3
- 230000003213 activating effect Effects 0.000 abstract 1
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- 230000000052 comparative effect Effects 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
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- 239000011574 phosphorus Substances 0.000 description 4
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
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- 239000006245 Carbon black Super-P Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- ZZVLXFDQIYFYED-UHFFFAOYSA-N P(=O)([O-])([O-])[O-].[NH4+].O.O.[NH4+].[NH4+] Chemical compound P(=O)([O-])([O-])[O-].[NH4+].O.O.[NH4+].[NH4+] ZZVLXFDQIYFYED-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000006183 anode active material Substances 0.000 description 1
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- 150000002500 ions Chemical class 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
- 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
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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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
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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
- H01M4/58—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
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention discloses a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material, a preparation method and application thereof. The composite material comprises: the lithium iron phosphate composite material comprises a lithium iron phosphate core and a coating layer coated on the surface of the core, wherein the coating layer is composed of lithium hexafluorozirconate and pyrolytic carbon, and the composite material comprises at least two composite material particles with different particle size ranges. The method of the invention comprises the following steps: 1) pulping, grinding and activating a lithium source, a ferrophosphorus source, a carbon source and lithium hexafluorozirconate; 2) producing spheres with at least two particle size ranges by using a spray dryer; (3) and sintering to obtain the lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material. The method can obviously improve the compaction density of the material, and the full battery prepared by adopting the composite material as the positive active substance has excellent first-turn capacity, cycle performance and low-temperature performance.
Description
Technical Field
The invention relates to the field of lithium ion battery positive electrode materials, and relates to a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material, a preparation method and application thereof, in particular to a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material with high compaction density and good electrochemical performance, a preparation method thereof and application as a lithium ion positive electrode material.
Background
As a cathode material that has been commercialized, a lithium iron phosphate material has problems of low electron conductivity and low ion transfer rate. Lithium iron phosphate power batteries also need further optimization due to low actual energy density.
At present, carbon coating has become a main means for improving the electrochemical performance of lithium iron phosphate cathode materials in industry. However, the coated carbon layer reduces the overall compacted density of the material, resulting in a lower volumetric energy density of the lithium iron phosphate battery. In addition, the inactive lithium sites in the graphite cathode can cause the lithium iron phosphate cathode material to lose a part of lithium ions in the charging and discharging process, so that the first-circle capacity of the full battery is reduced, and the normal performance of the battery is influenced. Among the technical means disclosed, there have been few researches for the targeted solution of the above-mentioned problems.
CN 106252635 a discloses graphene-coated lithium iron phosphate and a preparation method thereof, the method comprising: s1, mixing deionized water and graphene oxide to prepare a graphene oxide dispersion liquid, and mixing the graphene oxide dispersion liquid with a nitrogen source to obtain a mixture A; s2, mixing deionized water with a lithium source, a phosphorus source and an iron source to prepare a lithium source dispersion liquid, a phosphorus source dispersion liquid and an iron source dispersion liquid, sequentially adding the prepared lithium source dispersion liquid, phosphorus source dispersion liquid and iron source dispersion liquid into the mixture A, and stirring to obtain a mixture B; s3, drying the mixture B to obtain a nitrogen-doped graphene-coated lithium iron phosphate precursor; s4, preheating and sintering the nitrogen-doped graphene-coated lithium iron phosphate precursor to obtain the nitrogen-doped graphene-coated lithium iron phosphate cathode material. However, the surface coating of the pure nitrogen-doped graphene has the problems of high cost, difficulty in dispersion of the graphene and difficulty in uniform coating, so that the coating effect is not ideal, the volumetric specific energy of the product is reduced, and the electrochemical performance of the lithium iron phosphate is affected finally, which limits the application of the lithium iron phosphate in coating of electrode materials.
CN 014766956 a discloses a preparation method of a nickel-coated lithium iron phosphate positive electrode material, in which nickel is uniformly coated on the surface of the lithium iron phosphate material in an electroplating manner, so as to improve the capacity and cycle performance of the material. However, the coating means only solves the problem of poor electrochemical performance of the material per se, but does not effectively solve the problems of low first efficiency, poor low-temperature performance, low first-cycle capacity and the like of the battery in the charging and discharging processes.
Therefore, it is of great significance to seek a reasonable technical means to improve the pole piece compaction density, the first-turn capacity, the cycle performance and the low-temperature performance of the lithium iron phosphate material.
Disclosure of Invention
In view of the above problems in the prior art, the present invention aims to provide a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material, a preparation method and applications thereof, and in particular, to provide a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material with high compaction density and good electrochemical performance, a preparation method thereof and applications thereof as a lithium ion positive electrode material.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite, characterized in that the composite comprises: the lithium iron phosphate core comprises a lithium iron phosphate core and a coating layer coated on the surface of the core, wherein the coating layer consists of lithium hexafluorozirconate and pyrolytic carbon;
wherein the composite material comprises composite particles of at least two different particle size ranges.
The composite material comprises at least two composite material particles with different particle size ranges, the particles with different sizes are naturally mixed, the small balls fill the gaps of the large balls, the space utilization rate of active substances is optimized, the pole piece compaction density of the material is improved, and the volume energy density of the material is indirectly improved. F in lithium hexafluorozirconate-The strong electronegativity allows lithium hexafluorozirconate and a carbon source to form an Fe-F-C bond on the surface of the positive electrode material so as to provide new Li+A storage location. These new Li sites will store additional active Li+During the first charging cycle, the active Li sites and SEI interface film of the negative electrode are filled in one step to reduce the Li content in the positive electrode material+Loss in the charging and discharging process improves the capacity of the first circle of the full battery.
As a preferred technical scheme of the composite material, the composite material comprises large particles and small particles with different particle size ranges.
Preferably, the large particles have a particle size in the range of 7 μm to 20 μm, such as 7 μm, 8 μm, 10 μm, 11.5 μm, 12 μm, 14 μm, 15 μm, 17 μm, 18 μm, or 20 μm, etc.; the small particles have a particle size in the range of 500nm to 5 μm, for example, 500nm, 750nm, 1 μm, 2 μm, 3 μm, 3.5 μm, 4 μm or 5 μm.
Preferably, the mass ratio of large particles to small particles is from 4:6 to 6:4, such as 4:6, 4.2:5.8, 4.5:5.5, 5.7:4.3 or 6:4, and the like.
According to the scheme, the granularity and the mass ratio of the large particles to the small particles are matched, so that the compaction density of the pole piece can be better improved, and the electrochemical performance of the material can be improved.
The composite material is spherical particles.
Preferably, the crystal form of the lithium iron phosphate is olivine.
Preferably, the mass percentage of the lithium iron phosphate is 96% to 98%, for example, 96%, 96.5%, 97%, 97.5%, 98%, or the like, based on 100% of the total mass of the composite material.
Preferably, the mass percent of the lithium hexafluorozirconate is 0.1% to 1%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or the like, based on 100% of the total mass of the composite.
Preferably, the pyrolytic carbon is present in an amount of 1% to 3.9% by mass, for example 1%, 1.5%, 2%, 2.2%, 2.4%, 2.5%, 2.7%, 3.0%, 3.3%, 3.5%, 3.6%, 3.8%, 3.9%, or the like, based on 100% by mass of the total composite material.
In a second aspect, the present invention provides a method for preparing a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite as described in the first aspect, characterized in that the method comprises the steps of:
(1) adding a lithium source, a ferrophosphorus source and a coating material source into a grinding tank, and adding a dispersing agent to adjust the solid content to obtain precursor slurry;
(2) grinding the precursor slurry until the particle size of the precursor slurry is in a nanometer level so as to activate the lithium iron phosphate reaction raw material and the coating material source;
(3) utilizing a spray dryer to manufacture spheres with at least two particle size ranges;
(4) collecting the powder obtained in the step (3), and sintering to obtain a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material;
wherein the coating material source comprises a carbon source and lithium hexafluorozirconate.
The method of the invention firstly adjusts the precursor slurry to proper viscosity to grind and realize the activation of the raw material and the coating treatment source, then utilizes a spray dryer to atomize and form large and small spheres with at least two particle size ranges, takes the large spheres as the main body and small spheres as the assistance, naturally mixes the large and small spheres in the atomizing process, optimizes the space utilization rate of active substances in a mode of filling gaps between the large spheres by the small spheres to improve the pole piece compaction density of the material, and indirectly improves the volume energy density of the material. Using F in the calcination process-The strong electronegativity enables the activated lithium hexafluorozirconate and a carbon source to form Fe-F-C bonds on the surface layer of the positive electrode material so as to provide new Li+A storage location. These new Li sites will store additional active Li+In the process of charging in the first circle, the inactive Li sites and the SEI interface film of the negative electrode can be filled in one step, so that the loss of the positive electrode material Li + in the process of charging and discharging is reduced, and the capacity of the first circle of the full battery is improved.
As a preferable technical scheme of the method of the invention, the lithium source in the step (1) comprises any one or a combination of at least two of lithium carbonate, lithium acetate, lithium hydroxide, lithium chloride or lithium nitrate.
Preferably, the ferrophosphorus source in step (1) includes any one or a combination of at least two of anhydrous ferric phosphate, ferric phosphate dihydrate or hydrated ammonium ferric phosphate, but is not limited to the above-listed ferrophosphorus sources, and other ferrophosphorus sources that can provide both elemental phosphorus and elemental iron can also be used in the present invention.
Preferably, in the coating material source in step (1), the carbon source is any one or a combination of at least two of glucose, sucrose, polyethylene glycol, polyvinyl alcohol or phytic acid. The carbon sources selected by the method are all organic carbon sources, and compared with inorganic carbon sources, the organic carbon sources can form more defect sites in the carbonization process, thereby being beneficial to forming new Li+A storage location.
Preferably, the dispersant in step (1) comprises any one or a combination of at least two of water, ethanol or acetone, and the water is preferably deionized water and/or pure water.
Preferably, step (1) adjusts the solid content to 15% to 45%, for example, 15%, 17%, 22%, 30%, 33%, 36%, 38%, 40%, 42.5%, or 45%, etc., within which sand mill clogging can be avoided, slurry can be sufficiently dispersed and ground, and actual productivity can be secured.
Preferably, the molar ratio of the lithium source, the ferrophosphorus source, the carbon source and the lithium hexafluorozirconate is Li: Fe: C: Zr (1.01 to 1.05):1 (1.0 to 1.4): 0.001 to 0.1, for example, 1.01:1:1.4:0.1, 1.05:1:1.1:0.005, 1.03:1:1.3:0.1 or 1.02:1:1.1: 0.008.
Preferably, the step (2) is carried out until the particle size of the precursor slurry is in the range of 50nm to 500nm, such as 50nm, 75nm, 85nm, 100nm, 120nm, 145nm, 160nm, 180nm, 200nm, 230nm, 265nm, 300nm, 350nm, 400nm, 450nm or 500nm, etc., preferably 130nm to 180 nm.
Preferably, the inlet temperature of the spray drying in step (3) is 180 ℃ to 360 ℃, such as 180 ℃, 200 ℃, 225 ℃, 270 ℃, 300 ℃, 320 ℃, 340 ℃ or 360 ℃, etc.
Preferably, the outlet temperature of said spray drying of step (3) is 60 ℃ to 120 ℃, such as 60 ℃, 70 ℃, 80 ℃, 95 ℃, 100 ℃, 110 ℃ or 120 ℃ and the like.
Preferably, the method for producing the spheres with at least two particle size ranges in the step (3) is as follows: spray drying is carried out by means of multi-pipe air inlet and multi-pipe air inlet. The invention can realize the preparation of spheres with different particle size ranges by controlling different air inlet speeds of the air inlet pipes and different feeding speeds of the feeding pipes.
For example, the multi-tube air inlet and multi-tube feeding mode of the invention can be carried out as follows:
the number of the spray drying air inlet pipes and the number of the feed pipes are at least 2, the air inlet pipes and the feed pipes need to be matched for use, one air inlet pipe corresponds to one feed pipe so as to form a spray drying unit group, and for at least 2 air inlet pipes, at least 2 different flow rates in the at least 2 air inlet pipes need to be ensured (the air inlet flow rate can be controlled by respectively installing gas flow meters on air inlet pipelines); for at least 2 feed pipes, it is necessary to ensure that there are at least 2 different feed volumes (which can be fed from the same barrel of slurry by connecting peristaltic pumps to the feed pipe lines).
In order to obtain particles (referred to as large particles and small particles for short) with two different particle size ranges, for example, for preparing small particles, the air inflow amount of at least 2 air inlet pipes can be in the range of 10 to 30NL/min, and the feeding amount of at least 2 feeding pipes corresponding to the at least 2 air inlet pipes one by one can be in the range of 1 to 8 ml/min. In order to prepare large particles, the air inflow range of at least 2 air inlet pipes is 50-100 NL/min, and the feeding amount range of the feeding pipes corresponding to the at least 2 air inlet pipes in a one-to-one mode is 10-20 ml/min. The air inflow of the at least 2 air inlet pipes is not completely the same but falls within the range of 10-30 NL/min, and the feeding amount of the corresponding at least 2 feeding pipes is not completely the same but falls within the range of 1-8 ml/min.
In addition, the positions of the air inlet pipe, the feeding pipe and the nozzle interface do not influence the experimental effect. In order to ensure the productivity, the number of the air inlet pipes for preparing the small particles is less than or equal to that of the air inlet pipes for preparing the large particles, and the air inlet pipes and the feeding pipes are matched in a one-to-one mode for spray granulation, so that the number of the feeding pipes for preparing the small particles is less than or equal to that of the feeding pipes for preparing the large particles under the condition.
More specific but non-limiting examples are given to illustrate the preparation of large and small particles:
first turn on N2Gas flowmeter and corresponding N2A peristaltic pump of each feeding pipe regulates and controls the granularity to be a certain set granularity between 7 and 20 mu m; and recording parameters of the flow meter and the peristaltic pump after the granularity is stable. Then, turn off N2A gas flow meter and corresponding peristaltic pump, and then the remaining N1Gas flow meter and corresponding N1The peristaltic pump of each feeding pipe regulates and controls a certain set granularity between 500 mu m and 5 mu m. After the particle size is stabilized, the parameters of the gas flowmeter and the corresponding peristaltic pump are recordedBefore opening N2A gas flow meter and a peristaltic pump (N)1And N2All positive integers).
More preferably, the spray drying in step (3) is carried out by means of two-pipe air inlet and two-pipe feeding, and spheres with two size ranges of large and small are produced, which are also realized by adjusting the air inlet speed of each air inlet pipe and the feeding speed of each feeding pipe.
Preferably, the spray drying in the step (3) is carried out by multi-pipe air inlet and multi-pipe feeding, wherein the feeding amount of one air inlet pipe and the feeding pipe matched with the air inlet pipe for spray granulation is respectively 10 NL/min-30 NL/min and 1 ml/min-8 ml/min, and the air inlet amount of the other air inlet pipe and the feeding pipe matched with the air inlet pipe for spray granulation are respectively 50 NL/min-100 NL/min and 10 ml/min-20 ml/min.
In the preferred technical proposal, the air input quantity of one air inlet pipe is 10 NL/min-30 NL/min, such as 10NL/min, 15NL/min, 17NL/min, 18NL/min, 20NL/min, 22NL/min, 25NL/min, 28NL/min or 30 NL/min; the intake air amount of the other intake pipe is 50NL/min to 100NL/min, for example, 50NL/min, 65NL/min, 80NL/min, 90NL/min, or 100 NL/min.
In the preferred technical scheme, the feeding amount of one feeding pipe is 1 ml/min-8 ml/min, such as 1ml/min, 2ml/min, 3ml/min, 5ml/min, 6ml/min or 8 ml/min; the feeding amount of the other feeding port is 10 ml/min-20 ml/min, such as 10ml/min, 12ml/min, 15ml/min, 17ml/min, 18ml/min, 19ml/min or 20 ml/min.
More preferably, in the step (3), the spray drying is carried out by feeding the mixture through two air inlets and two air pipes, wherein the air inflow of one air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 20 NL/min-25 NL/min and 2 ml/min-4 ml/min, and the air inflow of the other air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 50 NL/min-60 NL/min and 15 ml/min-18 ml/min.
In the method, in the spray drying process in the step (3), the temperature of the feeding hole, the temperature of the discharging hole, the feeding rate and the air input are all key parameters for controlling the atomization formation of the spheres with different particle size ranges, and the combination performance of the atomization granulation can also be influenced.
Preferably, the sintering of step (4) is performed under an inert atmosphere, which includes any one of a nitrogen atmosphere, an argon atmosphere, a helium atmosphere, a neon atmosphere, a krypton atmosphere, or a xenon atmosphere, or a combination of at least two atmospheres.
Preferably, the sintering in step (4) is performed in a controlled temperature electric furnace.
Preferably, the sintering temperature in step (4) is 600 ℃ to 800 ℃, such as 600 ℃, 650 ℃, 700 ℃, 720 ℃, 750 ℃, 775 ℃, 785 ℃, or 800 ℃, etc.
Preferably, the sintering time in step (4) is 2h to 24h, such as 2h, 3h, 4h, 5h, 6.5h, 8h, 10h, 12h, 15h, 18h, 20h, 22h or 24h, etc., preferably 8h to 12 h.
As a further preferred technical solution of the method of the present invention, the method comprises the steps of:
(1) adding a lithium source, a ferrophosphorus source, a carbon source and lithium hexafluorozirconate into a grinding tank according to the molar ratio of Li to Fe to C to Zr (1.01-1.05) to 1 (1.0-1.4) to (0.001-0.1), and adding a dispersing agent to adjust the solid content to obtain precursor slurry;
(2) grinding the precursor slurry until the particle size of the precursor slurry is 50-500 nm so as to activate the lithium iron phosphate reaction raw material, the carbon source and the lithium hexafluorozirconate;
(3) spray drying is carried out by utilizing a spray dryer in a mode of feeding materials through two pipes of air inlet and two pipes of air inlet, spheres with at least two particle size ranges are manufactured, and the specific parameters are as follows:
the air inflow of one air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 10 NL/min-30 NL/min and 1/min-8 ml/min, and the air inflow of the other air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 50 NL/min-100 NL/min and 10 ml/min-20 ml/min;
the inlet temperature of spray drying is 180-360 ℃, and the outlet temperature is 60-120 ℃;
(4) collecting the powder obtained in the step (3), and sintering the powder for 2 to 24 hours at the temperature of 600 to 800 ℃ in an inert atmosphere to obtain the lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material;
the inert atmosphere comprises any one of a nitrogen atmosphere, an argon atmosphere, a helium atmosphere, a neon atmosphere, a krypton atmosphere or a xenon atmosphere or a combination of at least two of the atmospheres.
In a third aspect, the present invention provides a positive electrode sheet comprising the lithium hexafluorozirconate described in the first aspect and a carbon-co-coated lithium iron phosphate composite as a positive electrode material.
Preferably, the positive electrode sheet further comprises a foil, a binder and a conductive agent.
In a fourth aspect, the present invention provides a lithium ion battery comprising the positive electrode sheet according to the third aspect of the present invention;
preferably, the lithium ion battery further comprises a negative electrode sheet, a separator and an electrolyte.
The reagents and equipment used in the methods of the invention are commercially available and do not require special customization.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material with a novel structure and a preparation method thereof, the method grinds precursor slurry of a lithium source, a ferrophosphorus source and a coating treatment source, can activate raw materials and a coating material, has a large atomization granulation process, and can improve the pole piece compaction density of the material by small sphere collocation; the coating material can form a 'Fe-F-C' bond on the surface layer of the lithium iron phosphate material to form new Li in the calcining process+The active site improves the first-turn capacity of the composite material in the charging and discharging process of the full battery; the preparation process of the composite material is simple, the energy consumption is low, no waste liquid is generated, and the prepared composite material has excellent electrochemical performance and is suitable for industrial production.
(2) The lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material is used as a positive electrode material to prepare a positive electrode plate and assembled into a battery, and the compaction density of the electrode plate is high and is 2.53g/cm3The above; the first circle of the battery has high capacity, good cycle performance and low-temperature performance, the capacity retention rate of 1000 circles of the battery is more than 95.3 percent,the capacity retention rate at-20 ℃ is more than 75.0%.
Drawings
FIG. 1 is a particle size distribution curve of an atomized and granulated powder of example 1.
Fig. 2 is an SEM image of the lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite prepared in example 1.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
Sequentially putting lithium carbonate, anhydrous iron phosphate, glucose and lithium hexafluorozirconate into a grinding tank according to the mol ratio of Li to Fe to C to Zr of 1.05 to 1 to 0.001, adding deionized water until the solid content of the slurry is 25%, and fully grinding the precursor slurry until the particle size is 100nm to realize activation.
Spray drying the obtained slurry in a spray dryer, and setting the inlet temperature and the outlet temperature to be 310 ℃ and 120 ℃ respectively; spraying by adopting a 4-fluid spray head, separately arranging flowmeters on two air inlet pipes, separately arranging peristaltic pumps on two inlet pipes, and feeding from the same barrel of slurry. The air inflow of one air inlet pipe is 30NL/min, and the feeding amount of the corresponding one feeding pipe is 5ml/min, so that small-particle-size particles can be prepared; the air intake quantity of the other air inlet pipe is 90 NL/min; the corresponding feed rate of one feed pipe was 18ml/min for the preparation of large-sized particles.
And sintering the powder obtained after spray drying in a nitrogen atmosphere at 700 ℃ for 12h in a temperature-controlled electric furnace, and naturally cooling to room temperature to obtain the required composite material, namely the lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material.
The particle size distribution curve of the atomized and granulated powder obtained after the spray drying step in this example is shown in fig. 1, and it can be seen from the graph that the particle sizes of the spheres are in bimodal distribution, wherein one part of the spheres are distributed in a concentrated manner at 1 μm, and the other part of the spheres are distributed in a concentrated manner at 8 μm, which indicates that in the atomization process in this example, spheres with two particle size ranges are prepared by adjusting the atomization parameters.
The SEM image of the lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material of this embodiment is shown in fig. 2, and it can be seen from the figure that the material morphology is dominated by large spheres, and some small spheres are distributed between the large spheres, and the small spheres can fill gaps between the large spheres in the processing process, so as to improve the pole piece compaction density of the material.
Example 2
Sequentially putting lithium hydroxide, ferric phosphate dihydrate, polyvinyl alcohol and lithium hexafluorozirconate into a grinding tank according to the mol ratio of Li, Fe, C, Zr of 1.01:1:1.4:0.1, adding pure water until the solid content of the slurry is 15%, and fully grinding the precursor slurry until the particle size is 300nm to realize activation.
Spray drying the obtained slurry in a spray dryer, and setting the inlet temperature and the outlet temperature to be 280 ℃ and 120 ℃ respectively; 8 fluid nozzles are adopted for spraying, the flow meters are separately arranged on 4 air inlet pipes, the peristaltic pumps are separately arranged on 4 feeding pipes, and feeding is carried out from the same barrel of slurry. Wherein the air inflow of 1 air inlet pipe is 10NL/min, the corresponding feeding amount of 1 feeding pipe is 5ml/min, and the air inlet pipe is used for preparing small-particle-size particles; the air inflow of the other 3 air inlet pipes is 60 NL/min; the corresponding feed rate of 3 feed pipes was 12ml/min for the preparation of large-sized particles.
And sintering the powder obtained after spray drying in an argon atmosphere at 600 ℃ for 24h in a temperature-controllable electric furnace, and naturally cooling to room temperature to obtain the required composite material.
Example 3
Sequentially putting lithium acetate, ferric ammonium phosphate dihydrate, phytic acid and lithium hexafluorozirconate into a grinding tank according to the mol ratio of Li, Fe, C, Zr of 1.03, 1, 1.4 and 0.005, adding pure water until the solid content of the slurry is 40 percent, and fully grinding the precursor slurry until the particle size is 400 nm.
Spray drying the obtained slurry in a spray dryer, and setting the inlet temperature and the outlet temperature to be 300 ℃ and 120 ℃ respectively; adopt 6 fluid nozzle to spray, partial shipment flowmeter on 3 intake pipes, partial shipment peristaltic pump and follow the feeding in same bucket thick liquids on 3 inlet pipes. Wherein the air inflow of 1 air inlet pipe is 10NL/min, the corresponding feeding amount of 1 feeding pipe is 2ml/min, and the air inlet pipe is used for preparing small-particle-size particles; the air intake amount of the other 2 air inlet pipes is 70 NL/min; the corresponding feed rate of 3 feed pipes was 14ml/min for the preparation of large-sized particles.
And sintering the powder obtained after spray drying in an argon atmosphere at 750 ℃ for 6h in a temperature-controllable electric furnace, and naturally cooling to room temperature to obtain the required composite material.
Example 4
Sequentially putting lithium chloride, hydrated ammonium ferric phosphate, sucrose and lithium hexafluorozirconate into a grinding tank according to the mol ratio of Li to Fe to C to Zr of 1.03 to 1 to 1.1 to 0.005, adding deionized water until the solid content of the slurry is 30%, and fully grinding the precursor slurry until the granularity is 50nm to realize activation.
Spray drying the obtained slurry in a spray dryer, and setting the inlet temperature and the outlet temperature to be 350 ℃ and 100 ℃ respectively; spraying by using a 12-fluid spray head, subpackaging flow meters on 6 air inlet pipes, subpackaging peristaltic pumps on 6 feed pipes and feeding from the same barrel of slurry. Wherein the air inflow of 2 air inlet pipes is 25NL/min, the corresponding feeding amount of 2 feeding pipes is 3ml/min, and the air inlet pipes are used for preparing small-particle-size particles; the air intake amount of the other 4 air inlet pipes is 70 NL/min; the corresponding 4 feed pipes had a feed rate of 9ml/min for the preparation of large-sized particles.
And sintering the powder obtained after spray drying in a nitrogen atmosphere at 650 ℃ in a temperature-controlled electric furnace for 18h, and naturally cooling to room temperature to obtain the required composite material.
Example 5
Sequentially putting lithium nitrate, anhydrous iron phosphate, polyethylene glycol and lithium hexafluorozirconate into a grinding tank according to the mol ratio of Li to Fe to C to Zr of 1.02 to 1 to 1.2 to 0.1, adding pure water until the solid content of the slurry is 45%, and fully grinding the precursor slurry until the particle size is 150nm to realize activation.
Spray drying the obtained slurry in a spray dryer, and setting the inlet temperature and the outlet temperature to be 180 ℃ and 60 ℃ respectively; spraying by using a 16-fluid spray head, subpackaging 8 air inlet pipes with flow meters, subpackaging 8 feeding pipes with peristaltic pumps and feeding from the same barrel of slurry. Wherein the air inflow of 1 air inlet pipe is 10NL/min, the corresponding feeding amount of 1 feeding pipe is 2ml/min, and the air inlet pipe is used for preparing small-particle-size particles; the feeding amount of the other 1 gas inlet pipe is 10NL/min, and the feeding amount of the corresponding 1 gas inlet pipe is 8ml/min, so that small-particle-size particles can be prepared; the air inflow of the rest 6 air inlet pipes is 60 NL/min; the corresponding 6 feed pipes had a feed rate of 12ml/min for the preparation of large-sized particles.
And sintering the powder obtained after spray drying in an argon atmosphere at 780 ℃ in a temperature-controlled electric furnace for 3h, and naturally cooling to room temperature to obtain the required composite material.
Example 6
Sequentially putting lithium acetate, ferric phosphate dihydrate, phytic acid and lithium hexafluorozirconate into a grinding tank according to the mol ratio of Li to Fe to C to Zr of 1.03 to 1 to 1.1 to 0.005, adding pure water until the solid content of the slurry is 35 percent, and fully grinding the precursor slurry until the particle size is 500 nm.
Spray drying the obtained slurry in a spray dryer, and setting the inlet temperature and the outlet temperature to be 360 ℃ and 120 ℃ respectively; spraying by using a 16-fluid spray head, subpackaging 8 air inlet pipes with flow meters, subpackaging 8 feeding pipes with peristaltic pumps and feeding from the same barrel of slurry. Wherein the air inflow of 1 air inlet pipe is 20NL/min, the corresponding feeding amount of 1 feeding pipe is 8ml/min, and the air inlet pipe is used for preparing small-particle-size particles; the feeding amount of the other 1 gas inlet pipe is 10NL/min, and the feeding amount of the corresponding 1 gas inlet pipe is 8ml/min, so that small-particle-size particles can be prepared; 4 air inflow in the remaining 6 air inlet pipes is 90 NL/min; the feeding amount of the corresponding 4 feeding pipes is 18ml/min, so as to prepare large-particle-size particles; the air inflow of the rest 2 air inlet pipes is 80ml/min, and the feeding amount of the corresponding 2 feeding pipes is 12 ml/min.
And sintering the powder obtained after spray drying in an argon atmosphere at 800 ℃ for 2h in a temperature-controlled electric furnace, and naturally cooling to room temperature to obtain the required composite material.
Comparative example 1
Sequentially putting lithium carbonate, anhydrous iron phosphate and glucose into a grinding tank according to the mol ratio of Li to Fe to C of 1.05 to 1, adding deionized water until the solid content of the slurry is 25%, and fully grinding the precursor slurry until the particle size is 400 nm. Spray-drying the obtained slurry in a spray dryer, setting inlet temperature and outlet temperature at 310 deg.C and 120 deg.C respectively, air inflow of all air inlet pipes at 30NL/min, and feeding amount of all feeding pipes at 8 ml/min. And sintering the powder obtained after spray drying in a nitrogen atmosphere at 700 ℃ for 12h in a temperature-controlled electric furnace, and naturally cooling to room temperature to obtain the required composite material.
The composite material prepared by the comparative example has a carbon coating layer on the surface, the inner layer is made of the anode material, and the shape is still spherical. Unlike the examples, the composite material had a single particle size distribution.
And (3) testing:
18650PC was assembled from the composite materials of examples 1 to 6 and comparative example 1 as positive electrode active materials by the following steps:
preparing a positive plate: in a 5L stirrer, anode active material, binder PVDF and conductive agent Super-P are subjected to anode batching according to a ratio of 94:3:3 under an oil system and vacuum condition to obtain uniform anode slurry, and the prepared anode slurry is uniformly coated on an anode current collector aluminum foil to obtain an anode plate.
Preparing a negative plate: and (2) carrying out negative electrode batching on graphite, a thickening agent CMC, a binder SBR and conductive carbon powder according to a weight ratio of 95:1:2:2 in a water system to obtain uniform negative electrode slurry, uniformly coating the prepared negative electrode slurry on a negative electrode current collector copper foil, and cooling to obtain a negative electrode sheet.
Preparing a lithium ion battery: winding the positive plate, the negative plate and the diaphragm prepared according to the process to prepare a lithium ion battery cell, and injecting a non-aqueous electrolyte to prepare a 18650PC cylindrical battery; wherein the nonaqueous electrolyte adopts LiPF with the concentration of 1.0mol/L6As the electrolyte, a mixture of ethylene carbonate and diethyl carbonate at a volume ratio of 1:1 was used as the nonaqueous solvent.
The lithium ion batteries prepared in the above examples and comparative examples were subjected to related processing and electrochemical performance tests, and table 1 below shows corresponding test data.
Table 1 electrochemical performance and pole piece compaction density test results;
as can be seen from table 1, in examples 1 to 6 of the present invention, the lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material prepared by grinding activation, multi-tube air intake, multi-tube feeding spraying mode and parameter adjustment can significantly increase the compacted density of the material, and the full cell prepared by using the composite material as the positive active material has excellent first-turn capacity, cycle performance and low-temperature performance. The composite material of comparative example 1 did not contain lithium hexafluorozirconate, and the multi-tube air intake and feed rates of spray drying were completely the same, resulting in a material that did not have particles of different particle size ranges, small tap density of the pole piece, and poor electrochemical performance.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (34)
1. A preparation method of a lithium iron phosphate composite material co-coated by lithium hexafluorozirconate and carbon is characterized by comprising the following steps of:
(1) adding a lithium source, a ferrophosphorus source and a coating material source into a grinding tank, and adding a dispersing agent to adjust the solid content to obtain precursor slurry;
(2) grinding the precursor slurry until the particle size of the precursor slurry is in a nanometer level so as to activate the lithium iron phosphate reaction raw material and the coating material source;
(3) utilizing a spray dryer to manufacture spheres with at least two particle size ranges;
(4) collecting the powder obtained in the step (3), and sintering to obtain a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material;
wherein the coating material source comprises a carbon source and lithium hexafluorozirconate;
the composite material comprises: the lithium iron phosphate core comprises a lithium iron phosphate core and a coating layer coated on the surface of the core, wherein the coating layer consists of lithium hexafluorozirconate and pyrolytic carbon;
wherein the composite material comprises composite particles of at least two different particle size ranges.
2. The method of claim 1, wherein the composite material comprises large particles and small particles of different size ranges.
3. The method according to claim 2, wherein the large particles have a particle size ranging from 7 μm to 20 μm, and the small particles have a particle size ranging from 500nm to 5 μm.
4. The method according to claim 2, wherein the mass ratio of the large particles to the small particles is 4:6 to 6: 4.
5. The method of claim 1, wherein the composite material is a spherical particle.
6. The preparation method according to claim 1, wherein the crystalline form of the lithium iron phosphate is an olivine form.
7. The preparation method of claim 1, wherein the mass percent of the lithium iron phosphate is 96-98% based on 100% of the total mass of the composite material.
8. The method of claim 1, wherein the lithium hexafluorozirconate is present in an amount of 0.1 to 1% by mass, based on 100% by mass of the total composite material.
9. The preparation method according to claim 1, wherein the mass percent of the pyrolytic carbon is 1-3.9% based on 100% of the total mass of the composite material.
10. The method according to claim 1, wherein the lithium source of step (1) comprises any one of lithium carbonate, lithium acetate, lithium hydroxide, lithium chloride or lithium nitrate or a combination of at least two thereof.
11. The production method according to claim 1,
the ferrophosphorus source in the step (1) comprises any one or the combination of at least two of anhydrous ferric phosphate, ferric phosphate dihydrate or hydrated ammonium ferric phosphate.
12. The method according to claim 1, wherein in the coating material source in the step (1), the carbon source is any one or a combination of at least two of glucose, sucrose, polyethylene glycol, polyvinyl alcohol and phytic acid.
13. The method according to claim 1, wherein the dispersant in step (1) comprises any one of water, ethanol or acetone or a combination of at least two thereof.
14. The method of claim 13, wherein the water is deionized water and/or pure water.
15. The method of claim 1, wherein step (1) adjusts the solids content to 15% to 45%.
16. The method according to claim 1, wherein the molar ratio of the lithium source, the ferrophosphorus source, the carbon source, and the lithium hexafluorozirconate is Li: Fe: C: Zr = (1.01 to 1.05):1 (1.0 to 1.4): 0.001 to 0.1.
17. The preparation method according to claim 1, wherein the step (2) is carried out until the particle size of the precursor slurry is 50nm to 500 nm.
18. The preparation method according to claim 17, wherein the step (2) is carried out until the particle size of the precursor slurry is 130nm to 180 nm.
19. The method of claim 1, wherein the inlet temperature of the spray drying in step (3) is 180 ℃ to 360 ℃.
20. The method of claim 1, wherein the outlet temperature of the spray drying in step (3) is 60 ℃ to 120 ℃.
21. The method of claim 1, wherein the step (3) produces spheres of at least two size ranges by: spray drying is carried out by means of multi-pipe air inlet and multi-pipe air inlet.
22. The method of claim 21, wherein the spray drying of step (3) is carried out by two-tube feeding, i.e. two-tube feeding, to produce spheres with a size in two ranges, i.e. a large sphere and a small sphere.
23. The preparation method according to claim 21, wherein the spray drying is performed in step (3) by feeding the mixture through two air inlets and two air pipes, wherein the feeding amount of one air inlet pipe and the feeding pipe matched with the air inlet pipe for spray granulation is 10 NL/min-30 NL/min and 1 ml/min-8 ml/min, respectively, and the air inflow of the other air inlet pipe and the feeding pipe matched with the air inlet pipe for spray granulation are 50 NL/min-100 NL/min and 10 ml/min-20 ml/min, respectively.
24. The preparation method according to claim 21, wherein the spray drying is performed in the step (3) by feeding the mixture through two air inlets and two air pipes, wherein the air inlet amount of one air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 20 NL/min-25 NL/min and 2 ml/min-4 ml/min, and the air inlet amount of the other air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 50 NL/min-60 NL/min and 15 ml/min-18 ml/min.
25. The method according to claim 1, wherein the sintering in step (4) is performed in an inert atmosphere including any one of a nitrogen atmosphere, an argon atmosphere, a helium atmosphere, a neon atmosphere, a krypton atmosphere, or a xenon atmosphere, or a combination of at least two of the same.
26. The method according to claim 1, wherein the sintering of step (4) is performed in a controlled temperature electric furnace.
27. The method of claim 1, wherein the sintering temperature in step (4) is 600 ℃ to 800 ℃.
28. The preparation method according to claim 1, wherein the sintering time in the step (4) is 2-24 h.
29. The preparation method of claim 28, wherein the sintering time in the step (4) is 8-12 h.
30. The method for preparing according to claim 1, characterized in that it comprises the following steps:
(1) adding a lithium source, a ferrophosphorus source, a carbon source and lithium hexafluorozirconate into a grinding tank according to the mol ratio of Li to Fe to C to Zr = (1.01-1.05) to 1 (1.0-1.4) to (0.001-0.1), and adding a dispersing agent to adjust the solid content to obtain precursor slurry;
(2) grinding until the particle size of the precursor slurry is 50-500 nm to activate the lithium iron phosphate reaction raw material, a carbon source and lithium hexafluorozirconate;
(3) spray drying is carried out by utilizing a spray dryer in a mode of feeding materials through two pipes of air inlet and two pipes of air inlet, spheres with at least two particle size ranges are manufactured, and the specific parameters are as follows:
the air inflow of one air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 10 NL/min-30 NL/min and 1 ml/min-8 ml/min, and the air inflow of the other air inlet pipe and the feeding amount of the feeding pipe matched with the air inlet pipe for spray granulation are respectively 50 NL/min-100 NL/min and 10 ml/min-20 ml/min;
the inlet temperature of spray drying is 180-360 ℃, and the outlet temperature is 60-120 ℃;
(4) collecting the powder obtained in the step (3), and sintering for 2-24 h at 600-800 ℃ in an inert atmosphere to obtain a lithium hexafluorozirconate and carbon co-coated lithium iron phosphate composite material;
the inert atmosphere comprises any one of a nitrogen atmosphere, an argon atmosphere, a helium atmosphere, a neon atmosphere, a krypton atmosphere or a xenon atmosphere or a combination of at least two of the atmospheres.
31. A positive electrode sheet comprising the lithium hexafluorozirconate obtained by the production method according to any one of claims 1 to 30 and a carbon-co-coated lithium iron phosphate composite as a positive electrode material.
32. The positive electrode sheet according to claim 31, further comprising a foil, a binder, and a conductive agent.
33. A lithium ion battery comprising the positive electrode sheet according to claim 31.
34. The lithium ion battery of claim 33, further comprising a negative electrode sheet, a separator, and an electrolyte.
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