CN113428849B - Modified lithium iron phosphate cathode material and preparation method and application thereof - Google Patents
Modified lithium iron phosphate cathode material and preparation method and application thereof Download PDFInfo
- Publication number
- CN113428849B CN113428849B CN202110664806.0A CN202110664806A CN113428849B CN 113428849 B CN113428849 B CN 113428849B CN 202110664806 A CN202110664806 A CN 202110664806A CN 113428849 B CN113428849 B CN 113428849B
- Authority
- CN
- China
- Prior art keywords
- source
- iron phosphate
- preparation
- lithium
- lithium iron
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- H01M4/58—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
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
-
- 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
- C01P2006/11—Powder tap density
-
- 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
- C01P2006/12—Surface area
-
- 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
-
- 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 modified lithium iron phosphate positive electrode material and a preparation method and application thereof. The preparation method of the modified lithium iron phosphate anode material comprises the following steps: s1: grinding a feed liquid containing a lithium source, an iron source, a phosphorus source, an organic carbon source and an organic hydrophobic modifier to obtain a slurry; s2: and adding the slurry into a high-temperature thermal decomposition spraying device for spray pyrolysis reaction to obtain the modified lithium iron phosphate anode material. The modified lithium iron phosphate cathode material has the advantages of uniform particle size distribution, ppm saturated water absorption, excellent hydrophobic property and the like, has extremely low water absorption under the conventional storage condition, has good storage stability, does not need to carry out drying treatment on the cathode material when preparing the lithium ion battery cathode, can realize the preparation of the lithium ion battery under the condition of no humidity control, simplifies the preparation process of the battery on the premise of ensuring the performance of the lithium ion battery, and reduces the manufacturing cost of the battery at the same time.
Description
Technical Field
The invention relates to the technical field of anode materials, in particular to a modified lithium iron phosphate anode material and a preparation method and application thereof.
Background
A lithium ion battery is a secondary battery that mainly operates by movement of lithium ions between a positive electrode and a negative electrode. Lithium iron phosphate is an electrode material of a lithium ion battery and has a chemical formula of LiFePO4The lithium ion battery electrode material has the advantages of large discharge capacity, high safety, stable cycle performance, low price, environmental friendliness and the like, so the lithium ion battery electrode material is generally considered to be the most promising lithium ion battery electrode material.
However, the density of lithium iron phosphate is far lower than that of electrode materials such as lithium cobaltate, the capacity and energy density of the lithium ion battery are greatly reduced due to the lower stacking density, and the volume of the battery is remarkably increased, so that the improvement of the stacking density and the volume specific capacity of the lithium iron phosphate has great significance for the practical application of the lithium iron phosphate material. Because the particle morphology, the particle size and the distribution of the material directly influence the bulk density of the material, in order to solve the defects of low compacted density of the lithium iron phosphate material, the existing research mostly focuses on how to optimize the morphology and the particle size distribution of the lithium iron phosphate material.
Meanwhile, the conductivity of lithium iron phosphate is poor, the high-current discharge performance of the battery is poor due to low conductivity, and the method for solving the problem mainly comprises the step of modifying the lithium iron phosphate, wherein the modification method comprises the steps of doping conductive carbon or coating carbon on the surface of lithium iron phosphate particles and the like. In addition, because lithium iron phosphate has certain hygroscopicity, it is usually required to be dried before the lithium ion battery is prepared, so as to ensure various performances of the lithium ion battery; however, the drying process of the lithium iron phosphate material not only increases the complexity of the process, but also increases the manufacturing cost of the battery. Although the existing optimization and modification mode aiming at the lithium iron phosphate material can overcome the problem of hygroscopicity of the material to a certain extent, the saturated water absorption capacity of the material is still large, and the use requirement of the battery anode material can not be well met without drying treatment.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a modified lithium iron phosphate positive electrode material, and a preparation method and application thereof.
The invention provides a preparation method of a modified lithium iron phosphate anode material, which comprises the following steps:
s1: grinding a feed liquid containing a lithium source, an iron source, a phosphorus source, an organic carbon source and an organic hydrophobic modifier to obtain a slurry;
s2: and adding the slurry into a high-temperature thermal decomposition spraying device for spray pyrolysis reaction to obtain the modified lithium iron phosphate anode material.
In the invention, a lithium source, an iron source and a phosphorus source are mainly used for synthesizing lithium iron phosphate; it is not strictly limited, and a lithium source, an iron source, a phosphorus source, which are conventional in the art, may be used. Specifically, the lithium source may be selected from at least one of lithium hydroxide, lithium dihydrogen phosphate, and lithium carbonate, for example, lithium carbonate; the iron source and the phosphorus source may be at least one selected from ferrous sulfate, iron phosphate and phosphoric acid, for example, iron phosphate. In addition, the molar ratio of the lithium source, the iron source and the phosphorus source in the feed liquid can be controlled to be 1: (0.8-1.2): (0.8-1.2), for example 1: 1: 1; meanwhile, the mass content of the lithium source in the feed liquid can be controlled to be 7-8%; the mass content of the iron source is 28-32%; the mass content of the phosphorus source is 28-32%.
In the invention, the organic carbon source is mainly used for doping and/or coating conductive carbon in the lithium iron phosphate material, thereby improving the conductivity of the lithium iron phosphate. The organic carbon source is not particularly limited, and may be selected from at least one of glucose monohydrate, sucrose and polyvinyl alcohol, for example, glucose monohydrate; in addition, the mass content of the organic carbon source in the feed liquid can be controlled to be 2-4%.
In the invention, the organic hydrophobic modifier is mainly used for pyrolysis/cracking in spray pyrolysis reaction and loading a hydrophobic group on the lithium iron phosphate material, thereby improving the hydrophobic property of the lithium iron phosphate material; the kind of the organic hydrophobic modifier and the type of the hydrophobic group are not strictly limited. Specifically, the organic hydrophobic modifier may be selected from at least one of polyvinylidene fluoride (PVDF) and a polyoxyalkylene copolymer; wherein the PVDF has the chemical formula of- (C)2H2F2)n-, the polyoxyalkylene copolymer has the formula- (C)2H4O)a-(C3H6O)b-(C2H4O)c-, the hydrophobic group thereof is a polyoxypropylene group; the carbon number of the PVDF and the polyoxyalkylene copolymer is not particularly limited, and may be, for example, 8 to 18; in addition, the mass content of the organic hydrophobic modifier in the feed liquid can be controlled to be 0.5-0.6%.
The research shows that: when the organic hydrophobic modifier is subjected to spray pyrolysis reaction in a high-temperature pyrolysis spraying device, the organic hydrophobic modifier is pyrolyzed but not completely carbonized by controlling the reaction conditions of the spray pyrolysis reaction, at least part of hydrophobic groups in the organic hydrophobic modifier can be loaded on a lithium iron phosphate material, and then a modified lithium iron phosphate anode material with certain carbon content and hydrophobic performance can be formed; particularly, when the specific organic hydrophobic modifier is selected, the modified lithium iron phosphate cathode material has excellent hydrophobic property, the saturated water absorption is less than 150ppm, and the lithium iron phosphate cathode material with ppm-level hydrophobic capability is realized.
In step S1 of the present invention, the method for preparing the feed liquid may include:
A) adding an organic carbon source into part of the pure water, and uniformly stirring to obtain a first mixture;
B) adding the rest pure water, a lithium source, an iron source and a phosphorus source into the first mixture, and uniformly stirring to obtain a feed liquid; wherein, the adding time of the organic hydrophobic modifier is not strictly limited, and for example, the organic hydrophobic modifier can be added after the organic carbon source and/or the phosphorus source are added; particularly, when more than two organic hydrophobic modifiers are adopted, different organic hydrophobic modifiers can be added after the organic carbon source and the phosphorus source are added respectively, so that the organic hydrophobic modifiers are fully mixed.
Specifically, the conductivity of the adopted pure water is less than or equal to 0.165 mu s/cm; in the step A), the stirring time can be 10-20 min; in step B), the stirring time can be 1-2 h.
The grinding mode of the feed liquid is not strictly limited; conventional grinding means in the art may be employed. Specifically, the grinding may include rough grinding and fine grinding which are performed in this order; wherein, the D50 of the material liquid after coarse grinding can be controlled to be less than or equal to 1.2 μm, and the D50 of the material liquid after fine grinding can be controlled to be 0.45-0.50 μm.
In step S2 of the present invention, the spray pyrolysis reaction of the feed liquid containing the lithium source, the iron source, the phosphorus source, the organic carbon source and the organic hydrophobic modifier in the pyrolysis spray apparatus is a reaction that can atomize the feed liquid in the high temperature furnace, and make the feed liquid react, synthesize and pyrolyze instantly to obtain the powder product; the pyrolysis spray apparatus to be used is not particularly limited, and an apparatus conventional in the art may be used.
In step S2 of the present invention, the conditions of the spray pyrolysis reaction should be such that the organic hydrophobic modifier is decomposed to release its hydrophobic group and complete carbonization does not occur, for example, complete carbonization can be avoided by controlling the conditions of reaction temperature, time, pressure, etc.; specifically, the spray pyrolysis reaction can be carried out under the protection of high-purity nitrogen, and in addition, the temperature of the spray pyrolysis reaction can be controlled to be 350-450 ℃, the pressure is 1-3Mpa, and the time is 3-6 h; as can be understood, the high-purity nitrogen is nitrogen with the purity of more than or equal to 99.99 percent; preferably, during the spray pyrolysis reaction, the continuous displacement exhaust can be carried out under the condition that the nitrogen flow is 80-120L/min. Under the reaction conditions, the organic hydrophobic modifier can decompose and at least partially support the hydrophobic groups on the lithium iron phosphate material, and the organic hydrophobic modifier cannot be completely carbonized under the conditions, so that at least partially remaining hydrophobic groups can be supported on the lithium iron phosphate material.
The specific surface area of the modified lithium iron phosphate anode material prepared by the invention is more than or equal to 1.48m2(ii)/g; the carbon content is 1.0-3.5%; the compacted density is 1.0-3.0g/cm3. In addition, the particle size distribution of the modified lithium iron phosphate cathode material is as follows: d10 is more than or equal to 0.4 mu m, D50 is more than or equal to 1.0 mu m, D90 is less than 10 mu m, and D100 is less than 25 mu m; preferably, the modified lithium iron phosphate cathode material D50 is 1.0-2.5 μm.
The invention also provides a modified lithium iron phosphate cathode material prepared by the preparation method. The modified lithium iron phosphate cathode material has a certain carbon content and excellent hydrophobic property, has the advantages of uniform particle size distribution, ppm-level saturated water absorption, excellent hydrophobic property and the like, and has extremely low water absorption under conventional storage conditions (less than 150ppm) and good storage stability.
The invention also provides application of the modified lithium iron phosphate cathode material in preparation of a lithium ion battery. Because the modified lithium iron phosphate cathode material has excellent hydrophobic property and extremely low water absorption amount (less than 150ppm) under the conventional storage condition, the cathode material does not need to be dried when the lithium ion battery cathode is prepared, and the lithium ion battery can be prepared under the condition of no humidity control, so that the preparation process of the battery is simplified and the manufacturing cost of the battery is reduced on the premise of ensuring the performance of the lithium ion battery.
The implementation of the invention has at least the following advantages:
1. according to the preparation method, feed liquid containing a lithium source, an iron source, a phosphorus source, an organic carbon source and an organic hydrophobic modifier is subjected to spray pyrolysis reaction, hydrophobic modification is performed on the lithium iron phosphate while the lithium iron phosphate is synthesized, the organic hydrophobic modifier is decomposed in the reaction process, and at least part of hydrophobic groups are loaded on the lithium iron phosphate material, so that the hydrophobic property of the lithium iron phosphate anode material is remarkably improved, and the saturated water absorption reaches the ppm level (<150 ppm);
2. the specific surface area of the modified lithium iron phosphate anode material is more than or equal to 1.48m2Per g, carbon content of 1.0-3.5%, pressureThe solid density is 1.0-3.0g/cm3D50 is 1.0-2.5 μm, has uniform particle size distribution, is favorable for improving the capacity and energy density of the lithium iron phosphate material and reducing the volume of the lithium ion battery, and is particularly favorable for the practical application of the lithium iron phosphate material;
3. the modified lithium iron phosphate anode material disclosed by the invention is excellent in hydrophobic property, the water absorption amount is extremely low when the modified lithium iron phosphate anode material is stored under a conventional condition, drying treatment is not required before preparation, meanwhile, anode material slurry mixing can be carried out under a humidity-free control condition to prepare anode slurry mixing, and a coated anode plate is simply baked and volatilized to remove a solvent, so that the preparation process of a battery is simplified, and the manufacturing cost of the battery is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is an SEM image of a modified lithium iron phosphate positive electrode material prepared in example 5;
fig. 2 is an XRD pattern of the modified lithium iron phosphate positive electrode material prepared in example 5;
fig. 3 is a BET test result graph of the modified lithium iron phosphate positive electrode material prepared in example 5;
fig. 4 is a particle size distribution diagram of the modified lithium iron phosphate cathode material prepared in example 5 when water is used as a dispersion medium;
fig. 5 is a particle size distribution diagram of the modified lithium iron phosphate positive electrode material prepared in example 5 when alcohol is used as a dispersion medium.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms also include the plural forms unless the context clearly dictates otherwise, and further, it is understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and/or combinations thereof.
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood 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.
Example 1
The preparation method of the modified lithium iron phosphate cathode material of the embodiment is as follows:
1. preparation of the slurry
Adding 3.0kg of monohydrate dextrose and 520g of PVDF (carbon number 12) into 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), stirring for 15min, adding 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), 7.5kg of lithium carbonate and 30.0kg of iron phosphate, and circularly stirring and dispersing for 1h to obtain a feed liquid.
And (3) carrying out monomer circulation coarse grinding on the feed liquid, and setting the pressure, coarse grinding frequency and feeding amount of a diaphragm pump according to empirical values (the coarse grinding frequency and the feeding amount cannot be subjected to single grinding by an air machine) to obtain the coarse grinding liquid with the D50 being less than or equal to 1.2 mu m.
And then, carrying out monomer fine grinding on the coarse grinding liquid for multiple times, setting the pressure of a diaphragm pump, the fine grinding frequency and the feeding amount according to empirical values (the coarse grinding liquid cannot be subjected to single grinding by an air machine), and controlling the discharging D50 to be 0.45-0.50 mu m to obtain the slurry.
2. Preparation of modified lithium iron phosphate cathode material
Adding the prepared slurry into a high-temperature thermal decomposition spraying device, carrying out spray pyrolysis reaction for 5h under the conditions of 400 ℃, 2MPa and high-purity nitrogen protection, and continuously replacing and exhausting gas at the nitrogen flow rate of about 100L/min in the reaction process to obtain the modified lithium iron phosphate cathode material.
Example 2
The preparation method of the modified lithium iron phosphate cathode material of the embodiment is as follows:
1. preparation of the slurry
Adding 2.0kg of dextrose monohydrate and 600g of PVDF (carbon number is 8) into 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), stirring for 15min, then adding 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), 7kg of lithium carbonate and 28.0kg of iron phosphate, and circularly stirring and dispersing for 1.5h to obtain a feed liquid.
And (3) carrying out monomer circulation coarse grinding on the feed liquid, and setting the pressure, coarse grinding frequency and feeding amount of a diaphragm pump according to empirical values (the coarse grinding frequency and the feeding amount cannot be subjected to single grinding by an air machine) to obtain the coarse grinding liquid with the D50 being less than or equal to 1.2 mu m.
And then, carrying out monomer fine grinding on the coarse grinding liquid for multiple times, setting the pressure of a diaphragm pump, the fine grinding frequency and the feeding amount according to empirical values (the coarse grinding liquid cannot be subjected to single grinding by an air machine), and controlling the discharging D50 to be 0.45-0.50 mu m to obtain the slurry.
2. Preparation of modified lithium iron phosphate cathode material
Adding the prepared slurry into a high-temperature thermal decomposition spraying device, carrying out spray pyrolysis reaction for 6h under the conditions of 350 ℃, 3MPa and high-purity nitrogen protection, and continuously replacing and exhausting gas at the nitrogen flow rate of about 100L/min in the reaction process to obtain the modified lithium iron phosphate cathode material.
Example 3
The preparation method of the modified lithium iron phosphate cathode material of the embodiment is as follows:
1. preparation of the slurry
Adding 2.0kg of dextrose monohydrate and 500g of PVDF (carbon number is 18) into 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), stirring for 15min, then adding 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), 8kg of lithium carbonate and 32.0kg of iron phosphate, and circularly stirring and dispersing for 2h to obtain a feed liquid.
And (3) carrying out monomer circulating coarse grinding on the feed liquid, and setting the pressure, coarse grinding frequency and feeding amount of the diaphragm pump according to empirical values (non-available machine single grinding) to obtain a coarse grinding liquid with D50 being less than or equal to 1.2 mu m.
And then, carrying out monomer fine grinding on the coarse grinding liquid for multiple times, setting the pressure of a diaphragm pump, the fine grinding frequency and the feeding amount according to empirical values (the coarse grinding liquid cannot be subjected to single grinding by an air machine), and controlling the discharging D50 to be 0.45-0.50 mu m to obtain the slurry.
2. Preparation of modified lithium iron phosphate cathode material
Adding the prepared slurry into a high-temperature thermal decomposition spraying device, carrying out spray pyrolysis reaction for 4h under the conditions of 450 ℃, 1MPa and high-purity nitrogen protection, and continuously replacing and exhausting gas at the nitrogen flow rate of about 100L/min in the reaction process to obtain the modified lithium iron phosphate cathode material.
Example 4
The preparation method of the modified lithium iron phosphate cathode material of the embodiment is as follows:
1. preparation of the slurry
3.0kg of monohydrate dextrose and 520g of polyoxy olefin copolymer (carbon number is 11) are added into 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), after stirring for 15min, 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), 7.5kg of lithium carbonate and 30.0kg of iron phosphate are added, and the mixture is circularly stirred and dispersed for 1h, so that the feed liquid is obtained.
And (3) carrying out monomer circulation coarse grinding on the feed liquid, and setting the pressure, coarse grinding frequency and feeding amount of a diaphragm pump according to empirical values (the coarse grinding frequency and the feeding amount cannot be subjected to single grinding by an air machine) to obtain the coarse grinding liquid with the D50 being less than or equal to 1.2 mu m.
And then, carrying out monomer fine grinding on the coarse grinding liquid for multiple times, setting the pressure of a diaphragm pump, the fine grinding frequency and the feeding amount according to empirical values (the coarse grinding liquid cannot be subjected to single grinding by an air machine), and controlling the discharging D50 to be 0.45-0.50 mu m to obtain the slurry.
2. Preparation of modified lithium iron phosphate cathode material
Adding the prepared slurry into a high-temperature thermal decomposition spraying device, carrying out spray pyrolysis reaction for 5 hours under the conditions of 400 ℃, 1.5MPa and high-purity nitrogen protection, and continuously replacing and exhausting gas at the nitrogen flow rate of about 100L/min in the reaction process to obtain the modified lithium iron phosphate cathode material.
Example 5
The preparation method of the modified lithium iron phosphate cathode material of the embodiment is as follows:
1. preparation of the slurry
Adding 3.0kg of monohydrate dextrose and 300g of PVDF (carbon number 12) into 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), stirring for 15min, then adding 50kg of pure water (the conductivity is less than or equal to 0.165us/cm), 7.5kg of lithium carbonate and 30.0kg of iron phosphate, stirring for 15min, then adding 220g of polyoxyalkene copolymer (the carbon number is 11), circularly stirring and dispersing for 1h to obtain the feed liquid.
And (3) carrying out monomer circulation coarse grinding on the feed liquid, and setting the pressure, coarse grinding frequency and feeding amount of a diaphragm pump according to empirical values (the coarse grinding frequency and the feeding amount cannot be subjected to single grinding by an air machine) to obtain the coarse grinding liquid with the D50 being less than or equal to 1.2 mu m.
And then, carrying out monomer fine grinding on the coarse grinding liquid for multiple times, setting the pressure of a diaphragm pump, the fine grinding frequency and the feeding amount according to empirical values (the coarse grinding liquid cannot be subjected to single grinding by an air machine), and controlling the discharging D50 to be 0.45-0.50 mu m to obtain the slurry.
2. Preparation of modified lithium iron phosphate cathode material
Adding the prepared slurry into a high-temperature thermal decomposition spraying device, carrying out spray pyrolysis reaction for 5h under the conditions of 400 ℃, 2MPa and high-purity nitrogen protection, and continuously replacing and exhausting gas at the nitrogen flow rate of about 100L/min in the reaction process to obtain the modified lithium iron phosphate cathode material.
The SEM picture of the prepared modified lithium iron phosphate cathode material is shown in figure 1, and the XRD picture is shown in figure 2.
The specific surface area, carbon content and particle size distribution detection results of the prepared modified lithium iron phosphate cathode material are shown in table 1 and fig. 3 to 5.
Table 1 quality test results of modified lithium iron phosphate positive electrode material
Comparative example 1
The preparation method is basically the same as the embodiment 1 except that the organic hydrophobic modifier PVDF is not added in the step of preparing the slurry, so that the lithium iron phosphate cathode material is prepared.
Comparative example 2
The preparation method of the lithium iron phosphate cathode material of the comparative example is as follows:
adding the slurry obtained in the embodiment 1 into a high-temperature thermal decomposition spraying device, and reacting for 5 hours at 300 ℃ and 2MPa to obtain the lithium iron phosphate cathode material.
Comparative example 3
The preparation method of the lithium iron phosphate cathode material of the comparative example is as follows:
adding the slurry obtained in the example 1 into a hydrothermal reaction kettle, and reacting for 5 hours at 400 ℃ and under 2 MPa; and after the reaction is finished, spray drying is carried out on the reaction product to obtain the modified lithium iron phosphate anode material.
Comparative example 4
The preparation method of the lithium iron phosphate cathode material of the comparative example is as follows:
adding the slurry obtained in the example 1 into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 6h at 180 ℃; after the reaction is finished, separating, washing, drying, and calcining at the temperature of about 700 ℃ for 1h to obtain the lithium iron phosphate anode material.
Test example 1 hydrophobic property test
The modified lithium iron phosphate positive electrode materials prepared in examples 1 to 5 and the lithium iron phosphate positive electrode materials prepared in comparative examples 1 to 4 were placed in the air, and the water absorption amount of each material was measured after 7 days and 1 month, respectively.
The results of the water absorption measurements are shown in Table 2.
Table 2 detection results of water content/water absorption of each lithium iron phosphate positive electrode material
As can be seen from the results of table 2:
1. in comparative example 1, when the organic hydrophobic modifier is not added, the prepared lithium iron phosphate cathode material has high water absorption, needs to be dried to meet the use requirement of the battery cathode material, and needs to be subjected to humidity control to ensure various performances of the lithium ion battery when the battery is prepared;
2. in comparative example 2, if the reaction temperature is too low and fails to reach the pyrolysis temperature of the organic hydrophobic modifier PVDF, a PVDF coating layer can only be formed on the surface of the lithium iron phosphate material, but a hydrophobic group cannot be directly loaded on the lithium iron phosphate material, so that the hydrophobic property of the material is greatly reduced;
3. in comparative example 3, the hydrophobic property of the lithium iron phosphate material can be improved to a certain extent by performing the pyrolysis reaction and then performing spray drying, but the improvement range is limited;
4. in comparative example 4, calcination at a higher temperature results in complete carbonization of the organic hydrophobic modifier PVDF, at which time substantially no hydrophobic group is supported on the lithium iron phosphate material, and although a carbonized layer is formed on the lithium iron phosphate material, the degree of improvement in the hydrophobic property of the material is low;
5. in examples 1 to 5, the feed liquid was atomized by a high-temperature pyrolysis spray apparatus and instantaneously reacted, synthesized, and thermally decomposed, so that the organic hydrophobic modifier was pyrolyzed but not completely carbonized, and at least part of the hydrophobic groups in the organic hydrophobic modifier could be supported on the lithium iron phosphate material, thereby forming a modified lithium iron phosphate positive electrode material having a certain carbon content and a hydrophobic property, wherein the water absorption amount of the material was less than 150ppm, and the hydrophobic property was excellent.
Test example 2 Battery Performance test
The modified lithium iron phosphate positive electrode materials of the embodiments 1 to 5 are adopted, the positive electrode material slurry is prepared under the conditions of no drying and no humidity control, the positive electrode slurry is coated, and the coated positive electrode plate is simply baked and the solvent is volatilized.
The results of the performance tests of each of the batteries prepared are shown in tables 3 to 5.
Table 3 results of performance test of each battery
Table 4 results of performance test of each battery
Table 5 results of performance test of each battery
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (19)
1. A preparation method of a modified lithium iron phosphate cathode material is characterized by comprising the following steps:
s1: grinding a feed liquid containing a lithium source, an iron source, a phosphorus source, an organic carbon source and an organic hydrophobic modifier to obtain a slurry; wherein, the organic hydrophobic modifier is selected from at least one of PVDF and a polyoxyalkylene copolymer;
s2: adding the slurry into a high-temperature thermal decomposition spraying device for spray pyrolysis reaction to obtain a modified lithium iron phosphate anode material; wherein, the spray pyrolysis reaction is carried out under the protection of high-purity nitrogen, the temperature of the spray pyrolysis reaction is controlled to be 350-450 ℃, the pressure is 1-3MPa, and the time is 3-6 h.
2. The preparation method of claim 1, wherein the organic hydrophobic modifier comprises PVDF and a polyoxyalkene copolymer, and the mass ratio of the PVDF to the polyoxyalkene copolymer in the organic hydrophobic modifier is 3: (2-2.5).
3. The preparation method according to claim 1, wherein the mass content of the organic hydrophobic modifier in the feed liquid is controlled to be 0.5-0.6%.
4. The production method according to claim 1, characterized in that the lithium source is selected from at least one of lithium hydroxide, lithium dihydrogen phosphate, and lithium carbonate; the iron source and the phosphorus source are at least one selected from ferrous sulfate, ferric phosphate and phosphoric acid.
5. The production method according to claim 1, wherein the lithium source is lithium carbonate; the iron source and the phosphorus source are iron phosphate.
6. The preparation method according to claim 1, wherein the molar ratio of the lithium source, the iron source and the phosphorus source in the feed liquid is controlled to be 1: (0.8-1.2): (0.8-1.2).
7. The preparation method according to claim 1, wherein the mass content of the lithium source in the feed liquid is controlled to be 7-8%; the mass content of the iron source is 28-32%; the mass content of the phosphorus source is 28-32%.
8. The method according to claim 1, wherein the organic carbon source is at least one selected from the group consisting of glucose monohydrate, sucrose and polyvinyl alcohol.
9. The method according to claim 1, wherein the organic carbon source is glucose monohydrate.
10. The method according to claim 1, wherein the mass content of the organic carbon source in the feed liquid is controlled to be 2 to 4%.
11. The method according to claim 1, wherein the step S1 is a method for preparing the feed liquid, comprising:
A) adding an organic carbon source into part of the pure water, and uniformly stirring to obtain a first mixture;
B) adding the rest pure water, a lithium source, an iron source and a phosphorus source into the first mixture, and uniformly stirring to obtain a feed liquid; wherein the organic hydrophobic modifier is added after the organic carbon source and/or the phosphorus source is added.
12. The method according to claim 11, wherein in step a), the stirring time is 10 to 20 min; in the step B), the stirring time is 1-2 h.
13. The production method according to claim 1, wherein in step S1, the grinding includes coarse grinding and fine grinding which are performed in this order; wherein, the D50 of the material liquid after coarse grinding is controlled to be less than or equal to 1.2 μm, and the D50 of the material liquid after fine grinding is controlled to be 0.45-0.50 μm.
14. The process according to claim 1, wherein in step S2, the flow rate of nitrogen gas is controlled to 80 to 120L/min.
15. The preparation method according to claim 1, wherein in step S2, the specific surface area of the modified lithium iron phosphate positive electrode material is not less than 1.48m2(ii)/g; the carbon content is 1.0-3.5%; the compacted density is 1.0-3.0g/cm3。
16. The preparation method according to claim 1, wherein the particle size distribution of the modified lithium iron phosphate positive electrode material is as follows: d10 is more than or equal to 0.4 mu m, D50 is more than or equal to 1.0 mu m, D90 is less than 10 mu m, and D100 is less than 25 mu m.
17. The preparation method according to claim 1, wherein the modified lithium iron phosphate positive electrode material D50 is 1.0-2.5 μm.
18. A modified lithium iron phosphate cathode material, characterized by being prepared by the preparation method of any one of claims 1 to 17.
19. The use of the modified lithium iron phosphate positive electrode material of claim 18 in the preparation of a lithium ion battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110664806.0A CN113428849B (en) | 2021-06-16 | 2021-06-16 | Modified lithium iron phosphate cathode material and preparation method and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110664806.0A CN113428849B (en) | 2021-06-16 | 2021-06-16 | Modified lithium iron phosphate cathode material and preparation method and application thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113428849A CN113428849A (en) | 2021-09-24 |
| CN113428849B true CN113428849B (en) | 2022-05-06 |
Family
ID=77756050
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110664806.0A Active CN113428849B (en) | 2021-06-16 | 2021-06-16 | Modified lithium iron phosphate cathode material and preparation method and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113428849B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113582151B (en) * | 2021-07-28 | 2024-03-22 | 段镇忠 | Lithium iron manganese phosphate anode material and preparation method and application thereof |
| CN114497565A (en) * | 2022-01-11 | 2022-05-13 | 中科锂电新能源有限公司 | High-capacity lithium ferric manganese phosphate cathode material and processing technology |
| CN115513515B (en) * | 2022-09-29 | 2023-12-29 | 欣旺达动力科技股份有限公司 | Secondary battery and preparation method thereof |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090155689A1 (en) * | 2007-12-14 | 2009-06-18 | Karim Zaghib | Lithium iron phosphate cathode materials with enhanced energy density and power performance |
| CA2614634C (en) * | 2007-12-14 | 2013-04-30 | Phostech Lithium Inc. | Lithium iron phosphate cathode materials with enhanced energy density and power performance |
| US8187746B2 (en) * | 2008-05-16 | 2012-05-29 | Uchicago Argonne, Llc | Surface modification agents for lithium batteries |
| CN102148374A (en) * | 2010-02-08 | 2011-08-10 | 江西省金锂科技有限公司 | Method for adopting spray pyrolysis technology to prepare spherical anode material lithium iron phosphate |
| CN103000893B (en) * | 2012-12-20 | 2016-02-17 | 中国东方电气集团有限公司 | A kind of spray pyrolysis preparation method of lithium battery manganese-lithium phosphate anode material |
| CN103043639A (en) * | 2012-12-24 | 2013-04-17 | 彩虹集团公司 | Preparation method of spherical lithium iron phosphate anode materials |
| CN103050693A (en) * | 2012-12-24 | 2013-04-17 | 彩虹集团公司 | Preparation method for spherical LiMnPO4 anode material |
| CN104300119B (en) * | 2013-07-17 | 2019-05-24 | 东莞东阳光科研发有限公司 | A kind of preparation method of lithium iron phosphate positive material |
| CN105895877A (en) * | 2016-05-13 | 2016-08-24 | 合肥国轩高科动力能源有限公司 | Preparation method for hydrophobic conductive powder material coated composite ternary positive electrode material |
| CN109346709B (en) * | 2018-11-21 | 2021-10-15 | 湖北彩砼新材料有限公司 | Lithium ion battery anode material coated with super-hydrophobic material and preparation method thereof |
| CN111342015B (en) * | 2020-03-06 | 2022-05-06 | 合肥国轩高科动力能源有限公司 | High-compaction low-resistance lithium iron phosphate and preparation method thereof |
| CN112599767A (en) * | 2020-12-18 | 2021-04-02 | 湖北融通高科先进材料有限公司 | Preparation method of lithium iron phosphate material |
-
2021
- 2021-06-16 CN CN202110664806.0A patent/CN113428849B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN113428849A (en) | 2021-09-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113428849B (en) | Modified lithium iron phosphate cathode material and preparation method and application thereof | |
| CN113582151B (en) | Lithium iron manganese phosphate anode material and preparation method and application thereof | |
| KR20230125080A (en) | Lithium manganese iron phosphate precursor, lithium manganese iron phosphate cathode material and its manufacturing method and electrode material, electrode and lithium ion battery | |
| CN1967911A (en) | Preparing method of anode material of lithium cobalt, nickel, manganese, oxygen lithium ion battery | |
| CN109449429B (en) | Lithium iron phosphate/silicon carbide composite material and preparation method thereof | |
| WO2012020769A1 (en) | Method for producing nickel-containing complex compound | |
| CN113353909A (en) | Method for preparing lithium iron phosphate cathode material by utilizing recovered lithium | |
| CN116730317A (en) | Preparation method of lithium iron phosphate | |
| CN111162271A (en) | Multi-element anode material, preparation method thereof and lithium ion battery | |
| CN114613965A (en) | Preparation method and application of lithium iron phosphate/carbon composite material | |
| CN113594449B (en) | Modified lithium-containing phosphate positive electrode material and preparation method and application thereof | |
| CN108778990A (en) | The manufacturing method of phosphoric acid vanadium lithium | |
| CN116730310A (en) | Method for preparing lithium ion battery anode material lithium iron manganese phosphate | |
| CN115064676B (en) | Sodium ion battery anode material and preparation method and application thereof | |
| KR101893956B1 (en) | Methods of preparation for electrode active materials of lithium secondary batteries and lithium secondary batteries containing the electrode active materials | |
| CN114530591A (en) | Lithium ion battery cathode material, preparation method thereof and lithium ion battery | |
| CN113979475A (en) | Preparation method and application of chromium lithium titanate negative electrode material | |
| CN113764671A (en) | Anode material of lithium ion battery | |
| JP7159589B2 (en) | Method for producing positive electrode active material for non-aqueous electrolyte secondary battery, compact, and method for producing non-aqueous electrolyte secondary battery | |
| EP3678990B1 (en) | Process for producing particulate carbon-coated lithium iron phosphate, carbon coated lithiumiron phosphate and its uses | |
| JP7194891B2 (en) | Method for producing positive electrode active material for non-aqueous electrolyte secondary battery, compact, and method for producing non-aqueous electrolyte secondary battery | |
| KR20150118079A (en) | Method for Preparation of Olivine Type Lithium Iron Phosphate | |
| KR20020054534A (en) | Manganese composite hydroxide, method for preparing thereof and cathod active materials containing thereof | |
| KR101153360B1 (en) | Method of preparing positive active material for rechargeable lithium battery | |
| CN116282222A (en) | Nickel-iron-manganese layered oxide and preparation method and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |