CN114835100A - Preparation method of lithium battery positive electrode material and lithium battery positive electrode material - Google Patents
Preparation method of lithium battery positive electrode material and lithium battery positive electrode material Download PDFInfo
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 62
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 33
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000000203 mixture Substances 0.000 claims abstract description 65
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 39
- 239000011574 phosphorus Substances 0.000 claims abstract description 39
- 150000001875 compounds Chemical class 0.000 claims abstract description 27
- 238000001035 drying Methods 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000000843 powder Substances 0.000 claims abstract description 18
- 238000001354 calcination Methods 0.000 claims abstract description 16
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 15
- 238000002156 mixing Methods 0.000 claims abstract description 15
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 13
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 claims abstract description 13
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims abstract description 12
- 238000006243 chemical reaction Methods 0.000 claims abstract description 12
- 239000008103 glucose Substances 0.000 claims abstract description 12
- 238000005406 washing Methods 0.000 claims abstract description 7
- 238000007664 blowing Methods 0.000 claims abstract description 6
- 238000001914 filtration Methods 0.000 claims abstract description 6
- 238000000227 grinding Methods 0.000 claims abstract description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 26
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 17
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 12
- 229910052742 iron Inorganic materials 0.000 claims description 12
- 229910052700 potassium Inorganic materials 0.000 claims description 12
- 239000011591 potassium Substances 0.000 claims description 12
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 10
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 claims description 6
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 5
- OXZWZJDYOIQKBI-UHFFFAOYSA-L dipotassium sulfate hydrate Chemical compound O.[K+].[K+].[O-]S([O-])(=O)=O OXZWZJDYOIQKBI-UHFFFAOYSA-L 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 238000007605 air drying Methods 0.000 claims description 2
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 abstract description 37
- 229910001414 potassium ion Inorganic materials 0.000 abstract description 22
- 239000000463 material Substances 0.000 abstract description 21
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 abstract description 16
- 239000010405 anode material Substances 0.000 abstract description 16
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 12
- 229910001416 lithium ion Inorganic materials 0.000 description 12
- 230000005540 biological transmission Effects 0.000 description 8
- 150000002500 ions Chemical class 0.000 description 8
- 239000010406 cathode material Substances 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 238000007599 discharging Methods 0.000 description 5
- 230000005012 migration Effects 0.000 description 5
- 238000013508 migration Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 230000010287 polarization Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000000047 product Substances 0.000 description 4
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- 239000002002 slurry Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 229910001448 ferrous ion Inorganic materials 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000010450 olivine Substances 0.000 description 2
- 229910052609 olivine Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910052493 LiFePO4 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
-
- 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
- H01M4/362—Composites
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
- C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a preparation method of a lithium battery anode material, which comprises the following steps: s1: dissolving a lithium source compound, a ferrous salt, a potassium salt and a phosphorus source compound in pure water and mixing to obtain a mixture I; s2: placing the mixture I in a hydrothermal reaction kettle, and placing the hydrothermal reaction kettle in an air-blowing drying box for reaction to obtain a mixture II; s3: washing, filtering and drying the mixture II by using pure water to obtain powder of the mixture II; s4: mixing and grinding the powder of the mixture II and glucose to obtain a mixture III; s5: and calcining the mixture III in a vacuum environment to obtain the lithium battery positive electrode material. The potassium ion doped lithium iron phosphate anode material prepared by the preparation method can improve the ionic conductivity of the material and improve the multiplying power performance of the material. The invention also provides a lithium battery anode material.
Description
Technical Field
The invention relates to the technical field of battery manufacturing, in particular to a preparation method of a lithium battery anode material and the lithium battery anode material.
Background
To better cope with the growing energy crisis, Lithium Ion Batteries (LIBs) are beginning to play an increasingly important role in energy storage and conversion. The important core part of the lithium ion battery, namely the positive electrode material, can be said that the improvement of the performance of the lithium ion battery depends on the improved performance of the positive electrode material to a great extent. Therefore, the focus of lithium ion battery research in the future is to continuously develop an anode material with excellent performance, environmental friendliness, harmlessness and no pollution.
Lithium iron phosphate (LiFePO4, LFP) belongs to an olivine structure of an orthorhombic system, LiFePO 4 The crystal structure has stronger three-dimensional chemical bonds formed by P-O covalent bond delocalization, so that the material has excellent thermodynamic and kinetic stability, O in crystal lattices of the material is not easy to escape in the charging and discharging working process, and the safety is greatly improved. In addition, due to the induction of Fe-O-P bonds, Fe is reduced 3+ /Fe 2+ The Fermi level of the redox couple is LiFePO 4 The material provides a higher potential for lithium deintercalation. Therefore, LFP is considered as a potential positive electrode material. However, LFP has many advantages, but due to the special structure of lithium iron phosphate, the diffusion rate of lithium ions is slow, the electronic conductivity is poor, and it is not suitable for large current charging and discharging, and the application of power type lithium ion power battery is hindered, and these characteristics of lithium iron phosphate seriously hinder the commercial production of lithium iron phosphate cathode material.
The patent publication No. CN108390057A describes a method for preparing manganese-doped lithium iron phosphate electrode material, and the first charge-discharge specific capacity of the material is 162 mAh.g at 0.2C -1 However, the product has more impurities and serious agglomeration, so that the capacity of the product is low at a high rate, and the problem of poor rate performance of the lithium iron phosphate is not improved. Patent CN110620217A describes a zinc-doped lithium iron phosphate/carbon composite material and a preparation method thereof, wherein the initial discharge capacity is 158 mAh.g at 0.1C -1 However, the cycling stability is poor, and the structural change of the material is serious in the charging and discharging process. At present, no breakthrough progress is made for improving the problem of poor rate capability of lithium iron phosphate.
Therefore, there is a need to provide a novel method for preparing a positive electrode material of a lithium battery and a positive electrode material of a lithium battery to solve the above problems in the prior art.
Disclosure of Invention
The invention aims to provide a preparation method of a lithium battery anode material and the lithium battery anode material.
In order to achieve the above object, the method for preparing the lithium battery positive electrode material of the present invention comprises the following steps:
s1: dissolving a lithium source compound, a ferrous salt, a potassium salt and a phosphorus source compound in pure water and mixing to obtain a mixture I;
s2: placing the mixture I in a hydrothermal reaction kettle, and placing the hydrothermal reaction kettle in an air-blowing drying box for reaction to obtain a mixture II;
s3: washing, filtering and drying the mixture II by using pure water to obtain powder of the mixture II;
s4: mixing and grinding the powder of the mixture II and glucose to obtain a mixture III;
s5: and calcining the mixture III in a vacuum environment to obtain the lithium battery cathode material.
The preparation method of the lithium battery anode material has the beneficial effects that: the potassium ion-doped lithium iron phosphate anode material prepared by the preparation method of the invention introduces potassium ions on iron positions, can improve ion transmission, purposefully changes an ion transmission channel to improve the migration concentration of lithium ions, thereby reducing the electrochemical impedance and electrode polarization of the material and achieving the purposes of improving the ionic conductivity and multiplying power performance of the material.
Optionally, the lithium source compound comprises lithium hydroxide, the ferrous salt comprises ferrous sulfate heptahydrate, the potassium salt comprises potassium sulfate hydrate, and the phosphorus source comprises phosphoric acid.
Optionally, the molar ratio of lithium to phosphorus in the mixture I is controlled to be 2.8: 1-3.2: 1, the molar ratio of potassium to phosphorus is controlled to be 0.8: 1-1.2: 1, and the molar ratio of iron to phosphorus is controlled to be 0.8: 1-1.2: 1.
Optionally, the step of dissolving the lithium source compound, the ferrous salt, the potassium salt and the phosphorus source compound in pure water and mixing further comprises:
s11: dissolving the lithium source compound in pure water and stirring, and adding the phosphorus source compound;
s12: and (4) mixing the ferrous salt and the potassium salt, and adding the mixture into the mixed solution obtained in the step S11.
Optionally, the step S12 and the step S5 are performed under an inert gas protection. The step S12 and the step S5 are performed under the protection of inert gas, so that ferrous ions can be prevented from being oxidized, and the purity of the product is improved.
Optionally, the step of placing the hydrothermal reaction kettle in a forced air drying oven for reaction comprises: the reaction temperature is controlled to be 170-190 ℃, and the reaction time is controlled to be 9-11 hours.
Optionally, the step of washing, filtering and drying the mixture II with pure water comprises: the drying temperature is controlled to be 70-90 ℃, and the drying time is 11-13 hours.
Optionally, the mass ratio of the powder of the mixture II to the glucose is 4: 1-6: 1.
Optionally, the step of calcining the mixture III in a vacuum environment comprises: the calcination temperature is controlled to be 640-660 ℃, and the calcination time is controlled to be 5-7 hours.
The invention also provides a lithium battery anode material which is prepared by the preparation method of any one of the lithium battery anode materials.
The positive electrode material of the lithium battery provided by the invention has the following beneficial effects: the potassium ion-doped lithium iron phosphate cathode material provided by the invention introduces potassium ions at iron positions, can improve ion transmission, purposefully changes an ion transmission channel to improve the migration concentration of lithium ions, thereby reducing the electrochemical impedance and electrode polarization of the material, and achieving the purposes of improving the ionic conductivity and multiplying power performance of the material.
Drawings
Fig. 1 is a flow chart of a preparation method of a potassium ion doped lithium iron phosphate positive electrode material provided by the invention;
fig. 2 is an electron microscope scanning picture of an undoped lithium iron phosphate positive electrode material;
fig. 3 is an electron microscope scanning picture of the potassium ion doped lithium iron phosphate cathode material prepared by the present invention;
FIG. 4 is a graph comparing the rate performance of undoped lithium iron phosphate and potassium ion doped lithium iron phosphate at 2.5-4.2V;
fig. 5 is a long cycle rate performance graph of potassium ion doped lithium iron phosphate 5C of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the word "comprising" and similar words are intended to mean that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items.
Fig. 1 is a flow chart of a preparation method of a potassium ion doped lithium iron phosphate positive electrode material provided by the invention. Referring to fig. 1, the method for preparing the positive electrode material for a lithium battery of the present invention includes the steps of:
s1: dissolving a lithium source compound, a ferrous salt, a potassium salt and a phosphorus source compound in pure water and mixing to obtain a mixture I;
s2: placing the mixture I in a hydrothermal reaction kettle, and placing the hydrothermal reaction kettle in an air-blowing drying box for reaction to obtain a mixture II;
s3: washing, filtering and drying the mixture II by using pure water to obtain powder of the mixture II;
s4: mixing and grinding the powder of the mixture II and glucose to obtain a mixture III;
s5: and calcining the mixture III in a vacuum environment to obtain the lithium battery positive electrode material.
Due to the fact that cation doping can enlarge the lithium layer spacing of lithium titanate, the diffusion speed of lithium ions is increased, lattice distortion occurs inside the material, and the process does not change the crystal structure of the material. Therefore, the potassium ion is introduced into the potassium ion doped lithium iron phosphate positive electrode material at the iron position to improve ion transmission, and an ion transmission channel is purposefully changed to improve the migration concentration of lithium ions, so that the electrochemical impedance and electrode polarization of the material are reduced, and the purposes of improving the ionic conductivity of the material and improving the multiplying power performance of the material are achieved.
Similar effects can be achieved by replacing the potassium ions with metal ions with similar radiuses and chemical properties. The lithium source compound is a lithium-containing compound, and the phosphorus source compound is a phosphorus-containing compound.
In some embodiments, the lithium source compound comprises lithium hydroxide, the ferrous salt comprises ferrous sulfate heptahydrate, the potassium salt comprises potassium sulfate hydrate, and the phosphorus source comprises phosphoric acid.
In some embodiments, the molar ratio of lithium to phosphorus in the mixture I is controlled to be 2.8:1 to 3.2:1, the molar ratio of potassium to phosphorus is controlled to be 0.8:1 to 1.2:1, and the molar ratio of iron to phosphorus is controlled to be 0.8:1 to 1.2: 1.
In some embodiments, the molar ratio of lithium to phosphorus in the mixture I is controlled to be 2.8:1, the molar ratio of potassium to phosphorus is controlled to be 0.8:1, and the molar ratio of iron to phosphorus is controlled to be 0.8: 1.
In some embodiments, the molar ratio of lithium to phosphorus, the molar ratio of potassium to phosphorus, and the molar ratio of iron to phosphorus in the mixture I are controlled to be 3.2:1, 1.2:1, and 1.2:1, respectively.
In some embodiments, the molar ratio of lithium to phosphorus, the molar ratio of potassium to phosphorus, and the molar ratio of iron to phosphorus in the mixture I are controlled to be 3:1, 1:1, and 1:1, respectively.
In some embodiments, the molar ratio of lithium to phosphorus, the molar ratio of potassium to phosphorus, and the molar ratio of iron to phosphorus in the mixture I are controlled to be 3:1, 0.99:1, and 1:1, respectively.
In some embodiments, the step of dissolving and mixing the lithium source compound, the ferrous salt, the potassium salt, and the phosphorus source compound in pure water further includes:
s11: dissolving the lithium source compound in pure water and stirring, and adding the phosphorus source compound;
s12: and (4) mixing the ferrous salt and the potassium salt, and adding the mixture into the mixed solution obtained in the step S11.
In some embodiments, the step S12 and the step S5 are performed under an inert gas protection.
The step S12 and the step S5 are performed under the protection of inert gas, so that ferrous ions can be prevented from being oxidized, and the purity of the product is improved.
In some embodiments, the hydrothermal reaction kettle is placed in an air-blowing drying oven to react at the temperature of 170-190 ℃ for 9-11 hours. In some embodiments, the reaction temperature is 170 degrees celsius and the reaction time is 11 hours. In yet other embodiments, the reaction temperature is 190 degrees celsius and the reaction time is 9 hours.
In some embodiments, the mixture II is washed with pure water, filtered and dried at 70-90 ℃ for 11-13 hours. In some embodiments, the drying temperature is 70 degrees celsius and the drying time is 13 hours. In still other embodiments, the drying temperature is 90 degrees celsius and the drying time is 11 hours.
In some embodiments, the mass ratio of the powder of the mixture II to the glucose is between 4:1 and 6: 1. In some embodiments, the mass ratio of the powder of the mixture II to the glucose is 5: 1. In some embodiments, the mass ratio of the powder of the mixture II to the glucose is 4: 1. In still other embodiments, the mass ratio of the powder of the mixture II to the glucose is 6: 1.
In some embodiments, the mixture III is placed in a vacuum environment for calcination at 640-660 ℃ for 5-7 hours. In some embodiments, the calcination temperature is 640 degrees celsius and the calcination time is 7 hours. In still other embodiments, the calcination temperature is 660 degrees celsius and the calcination time is 5 hours.
The following provides a specific embodiment of the method for preparing the lithium battery positive electrode material of the present invention.
Weighing lithium hydroxide, ferrous sulfate heptahydrate, potassium sulfate hydrate and phosphoric acid, wherein the molar ratio of lithium to phosphorus is controlled to be 3:1, the molar ratio of potassium to phosphorus is controlled to be 1:1, and the molar ratio of iron to phosphorus is controlled to be 1: 1;
adding the lithium hydroxide into a three-neck flask, dissolving the lithium hydroxide into pure water, fully stirring the lithium hydroxide under a magnetic stirrer, and then adding the phosphoric acid, wherein the solution is changed into a white suspension;
adding the ferrous sulfate heptahydrate and the hydrated ferrous sulfate with corresponding doping amount into the white suspension, wherein the adding process of the ferrous sulfate heptahydrate and the hydrated ferrous sulfate with corresponding doping amount is carried out under the argon protection environment, so as to obtain a mixture I;
pouring the mixture I into a hydrothermal reaction kettle, placing the hydrothermal reaction kettle in an air-blowing drying oven, setting the reaction temperature to be 180 ℃, and setting the reaction time to be 10 hours to obtain a mixture II, wherein the obtained mixture II is a solution with powder;
washing the mixture II with pure water for 3 times or 5 times, repeatedly performing suction filtration for 3 times or 5 times, and drying a filter cake at 80 ℃ for 12 hours to obtain powder of the mixture II;
fully grinding the powder of the mixture II and glucose together, wherein the mass ratio of the powder of the mixture II to the glucose is 5:1, so as to obtain a mixture III;
and putting the mixture III into a vacuum tube furnace with argon protection, and calcining for 6 hours at 650 ℃ to obtain the potassium ion doped lithium iron phosphate anode material.
The invention also provides a lithium battery anode material which is prepared by the preparation method of any one of the lithium battery anode materials. The potassium ion-doped lithium iron phosphate cathode material provided by the invention introduces potassium ions at iron positions, can improve ion transmission, purposefully changes an ion transmission channel to improve the migration concentration of lithium ions, thereby reducing the electrochemical impedance and electrode polarization of the material, and achieving the purposes of improving the ionic conductivity and multiplying power performance of the material.
Performance evaluation:
fig. 2 is an electron microscope scanning picture of an undoped lithium iron phosphate positive electrode material, fig. 3 is an electron microscope scanning picture of a potassium ion doped lithium iron phosphate positive electrode material prepared by the present invention, and referring to fig. 2 and fig. 3, it can be seen that lithium iron phosphate primary particles are aggregated together to form a larger aggregation, and the particle size of the co-doped material is significantly reduced and the distribution is uniform. According to the invention, potassium ions are successfully doped into the crystal of the lithium iron phosphate material, the lattice parameter is changed under the condition that the olivine type crystal structure of the lithium iron phosphate is not damaged, the potassium ions are successfully doped, the lithium layer spacing is enlarged, the lithium ion migration is promoted, and the multiplying power performance of the lithium iron phosphate anode material can be effectively improved.
Charging and discharging and cycle testing:
weighing the potassium ion doped lithium iron phosphate positive electrode material prepared in the embodiment of the invention, mixing the positive electrode material with acetylene black and polyvinylidene fluoride dissolved in N-methylpyrrolidone, grinding the mixture into slurry, uniformly coating the slurry on copper foil, drying the slurry in a vacuum drying box at 110 ℃ to obtain a pole piece, assembling the pole piece into a button battery in a glove box by using metal lithium as a counter electrode, and carrying out charging and discharging and cycle testing on a blue testing system.
Fig. 4 is a graph comparing the multiplying power performance of undoped lithium iron phosphate and potassium ion doped lithium iron phosphate at different rates of 2.5-4.2V, where a broken line 1 represents the multiplying power performance of undoped lithium iron phosphate, and a broken line 2 represents the multiplying power performance of potassium ion doped lithium iron phosphate. Referring to fig. 4, it is seen that the specific discharge capacity of the undoped lithium iron phosphate sample at 0.2C is 159.9mAh g -1 At 10C, 89.4mAh · g -1 . The specific discharge capacity of the potassium ion doped lithium iron phosphate sample at 0.2 ℃ is 167.4 mAh.g -1 And a specific discharge capacity at 10C of 124.5mAh g -1 . Therefore, the potassium ion doped lithium iron phosphate can improve the rate capability of the material.
Fig. 5 is a long cycle rate performance graph of potassium ion doped lithium iron phosphate 5C of the present invention. Referring to fig. 5, it can be seen that the first-cycle discharge capacity of the potassium ion-doped lithium iron phosphate in the 5C long cycle was 145.7mAh g -1 The rate capability is obviously improved.
Although the embodiments of the present invention have been described in detail hereinabove, it is apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it is to be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the following claims. Moreover, the invention as described herein is capable of other embodiments and of being practiced or of being carried out in various ways.
Claims (10)
1. The preparation method of the lithium battery positive electrode material is characterized by comprising the following steps of:
s1: dissolving a lithium source compound, a ferrous salt, a potassium salt and a phosphorus source compound in pure water and mixing to obtain a mixture I;
s2: placing the mixture I in a hydrothermal reaction kettle, and placing the hydrothermal reaction kettle in an air-blowing drying box for reaction to obtain a mixture II;
s3: washing, filtering and drying the mixture II by using pure water to obtain powder of the mixture II;
s4: mixing and grinding the powder of the mixture II and glucose to obtain a mixture III;
s5: and calcining the mixture III in a vacuum environment to obtain the lithium battery positive electrode material.
2. The method of claim 1, wherein the lithium source compound comprises lithium hydroxide, the ferrous salt comprises ferrous sulfate heptahydrate, the potassium salt comprises potassium sulfate hydrate, and the phosphorus source comprises phosphoric acid.
3. The method for preparing the positive electrode material for the lithium battery as claimed in claim 1, wherein the molar ratio of lithium to phosphorus, the molar ratio of potassium to phosphorus and the molar ratio of iron to phosphorus in the mixture I are controlled to be 2.8: 1-3.2: 1, 0.8: 1-1.2: 1 and 0.8: 1-1.2: 1, respectively.
4. The method for preparing a positive electrode material for a lithium battery according to claim 3, wherein the step of dissolving and mixing a lithium source compound, a ferrous salt, a potassium salt, and a phosphorus source compound in pure water further comprises:
s11: dissolving the lithium source compound in pure water and stirring, and adding the phosphorus source compound;
s12: and (4) mixing the ferrous salt and the potassium salt, and adding the mixture into the mixed solution obtained in the step S11.
5. The method of claim 4, wherein the steps S12 and S5 are performed under an inert gas atmosphere.
6. The method for preparing the positive electrode material of the lithium battery as claimed in claim 1, wherein the step of placing the hydrothermal reaction kettle in a forced air drying oven for reaction comprises the steps of:
the reaction temperature is controlled to be 170-190 ℃, and the reaction time is controlled to be 9-11 hours.
7. The method for preparing a positive electrode material for a lithium battery according to claim 1, wherein the step of washing, suction-filtering and drying the mixture II with pure water comprises:
the drying temperature is controlled to be 70-90 ℃, and the drying time is 11-13 hours.
8. The method for preparing the positive electrode material for the lithium battery as claimed in claim 1, wherein the mass ratio of the powder of the mixture II to the glucose is 4: 1-6: 1.
9. The method for preparing the positive electrode material of the lithium battery as claimed in claim 1, wherein the step of calcining the mixture III in a vacuum environment comprises:
the calcination temperature is controlled to be 640-660 ℃, and the calcination time is controlled to be 5-7 hours.
10. A lithium battery positive electrode material characterized by being produced by the method for producing a lithium battery positive electrode material according to any one of claims 1 to 9.
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| CN101121509A (en) * | 2007-07-23 | 2008-02-13 | 河北工业大学 | Hydro-thermal synthetic preparation method for lithium ion battery anode material lithium iron phosphate |
| CN101264874A (en) * | 2008-03-12 | 2008-09-17 | 周葛亮 | Doping synthesis method for anode material ferric lithium phosphate |
| CN101369659A (en) * | 2007-08-17 | 2009-02-18 | 深圳市比克电池有限公司 | Novel lithium iron phosphate anode material used for lithium ion battery and method of manufacturing the same |
| CN102249208A (en) * | 2011-05-06 | 2011-11-23 | 朱鸥鹭 | Hydrothermal synthesis method for lithium ferromanganese phosphate anode material of lithium ion battery |
| CN108470907A (en) * | 2018-03-19 | 2018-08-31 | 华南理工大学 | A kind of potassium ion doping lithium-rich anode material and preparation method thereof and the application in lithium ion battery |
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| CN101121509A (en) * | 2007-07-23 | 2008-02-13 | 河北工业大学 | Hydro-thermal synthetic preparation method for lithium ion battery anode material lithium iron phosphate |
| CN101369659A (en) * | 2007-08-17 | 2009-02-18 | 深圳市比克电池有限公司 | Novel lithium iron phosphate anode material used for lithium ion battery and method of manufacturing the same |
| CN101264874A (en) * | 2008-03-12 | 2008-09-17 | 周葛亮 | Doping synthesis method for anode material ferric lithium phosphate |
| CN102249208A (en) * | 2011-05-06 | 2011-11-23 | 朱鸥鹭 | Hydrothermal synthesis method for lithium ferromanganese phosphate anode material of lithium ion battery |
| CN108470907A (en) * | 2018-03-19 | 2018-08-31 | 华南理工大学 | A kind of potassium ion doping lithium-rich anode material and preparation method thereof and the application in lithium ion battery |
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