CN113683072B - Preparation method and application of spherical lithium iron phosphate positive electrode material - Google Patents

Preparation method and application of spherical lithium iron phosphate positive electrode material Download PDF

Info

Publication number
CN113683072B
CN113683072B CN202110927429.5A CN202110927429A CN113683072B CN 113683072 B CN113683072 B CN 113683072B CN 202110927429 A CN202110927429 A CN 202110927429A CN 113683072 B CN113683072 B CN 113683072B
Authority
CN
China
Prior art keywords
mixed solution
lithium
iron phosphate
dimethyl sulfoxide
polyaniline
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
Application number
CN202110927429.5A
Other languages
Chinese (zh)
Other versions
CN113683072A (en
Inventor
黄勇平
胡振宇
金磊
陈佳敏
邵国祥
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Inner Mongolia Shengvanadium Technology New Energy Co ltd
Original Assignee
Inner Mongolia Shengvanadium Technology New Energy Co ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Inner Mongolia Shengvanadium Technology New Energy Co ltd filed Critical Inner Mongolia Shengvanadium Technology New Energy Co ltd
Priority to CN202110927429.5A priority Critical patent/CN113683072B/en
Publication of CN113683072A publication Critical patent/CN113683072A/en
Application granted granted Critical
Publication of CN113683072B publication Critical patent/CN113683072B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • 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
    • 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
    • H01M4/624—Electric conductive fillers
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • 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
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • 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

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention provides a preparation method of a spherical lithium iron phosphate anode material; the method comprises the following steps: (1) Wet grinding an iron source, a lithium source and a phosphorus source to obtain a mixed solution A; (2) Adding a carbon source to disperse in the mixed solution A to obtain a mixed solution B; (3) Dissolving polyaniline fiber in dimethyl sulfoxide to obtain polyaniline mixed dimethyl sulfoxide solution; (4) Dispersing a solution of polyaniline mixed with dimethyl sulfoxide into the mixed solution B to obtain a mixed solution C; (5) Spray drying the mixed solution C to obtain a spray material; (6) Freeze-drying the spray material to obtain a sintering precursor; (7) Sintering the precursor obtained in the step (6) at a high temperature under the condition of reducing atmosphere to obtain a finished product. According to the invention, the polyaniline conductive agent is introduced in the dispersing stage, so that the conductivity of a finished product after sintering can be greatly enhanced; the invention has simple process, can effectively improve the appearance of the anode material and improve the electrochemical performance of the material.

Description

Preparation method and application of spherical lithium iron phosphate positive electrode material
Technical Field
The invention belongs to the technical field of energy storage materials, and particularly relates to a preparation method and application of a spherical lithium iron phosphate positive electrode material.
Background
With the continuous development of human society, environmental problems are increasingly prominent, and with the rise of national new energy strategy, lithium ion batteries are widely used as clean energy sources from the beginning of the 90 th century to the present due to the advantages of small volume, high energy density, safety, environmental protection and the like.
The lithium iron phosphate serving as the lithium ion battery anode material has the advantages of wide raw material source, low price, good material thermal stability, high voltage platform, long cycle life, no toxicity, no harm, high safety and the like, and is a choice for the current power-shaped and energy-storage-type lithium ion battery anode materials.
However, the energy density and the circulation stability of the energy-saving type energy-saving device can meet the market requirements by further improving the energy density and the circulation stability, and the technical problem to be solved is urgent.
At present, high-temperature drying is needed before sintering by a high-temperature solid-phase method, but precursor generated after drying is extremely easy to adhere, so that agglomeration phenomenon of a sintered product is serious, and the overall appearance and the electrical property are influenced.
Disclosure of Invention
In view of the above, the invention aims to provide a preparation method and application of a spherical lithium iron phosphate anode material, so as to overcome the defects of the prior art. The spray material is freeze-dried before sintering, and the volatilization of dimethyl sulfoxide can greatly reduce the aggregation of the precursor and the aggregation growth of spherical particles during sintering.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
a preparation method of spherical lithium iron phosphate anode material comprises the following steps,
(1) Wet grinding an iron source, a lithium source and a phosphorus source to obtain a mixed solution A;
(2) Adding a carbon source to disperse in the mixed solution A to obtain a mixed solution B;
(3) Polyaniline fiber (conductive agent) is dissolved in dimethyl sulfoxide to obtain a solution of polyaniline mixed with dimethyl sulfoxide (which is convenient for uniform mixing with the precursor);
(4) Dispersing a solution of polyaniline mixed with dimethyl sulfoxide into the mixed solution B to obtain a mixed solution C;
(5) Spray drying the mixed solution C to obtain a spray material;
(6) Freeze-drying the spray material (greatly removing water and dimethyl sulfoxide) to obtain a sintering precursor;
(7) Sintering the precursor obtained in the step (6) at a high temperature under the condition of reducing atmosphere to obtain a finished product.
According to the preparation method provided by the invention, the polyaniline conductive agent is introduced in the step (4), so that the conductivity of a finished product after sintering can be greatly enhanced, and the electrochemical performance of the product is improved; the spray material is freeze-dried before sintering in the step (6), so that agglomeration growth of spherical particles during sintering can be reduced; the carbon quantity taken away by the volatilization of the moisture during the sintering of the spray material is greatly reduced, and the carbon source cost is saved.
The following preferred technical solutions are used as the present invention, but not as limitations on the technical solutions provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solutions.
Preferably, the iron source in the step (1) is iron phosphate or ferric oxide, the lithium source is lithium carbonate or lithium nitrate, and the phosphorus source is phosphoric acid or iron phosphate.
Preferably, in the step (1), the molar ratio of elements of Li to Fe to P in the reaction raw material containing lithium, iron and phosphorus is (1 to 1.1): (0.9 to 1.0): 1, for example, 1:0.9:1, 1.05:0.95:1, 1.1:0.9:1, 1.1:0.95:1, 1.05:1:1 or 1.1:1:1, but not limited to the listed values, and other non-listed values in the range of the values are equally applicable.
Preferably, in step (2), the carbon source comprises any one or a combination of at least two of sucrose, glucose, starch, citric acid or polypropylene.
Preferably, the mass of the carbon source in the step (1) is 1 to 15 wt% of the mass of the reaction raw material containing lithium, iron and phosphorus, for example, 1wt%, 2 wt%, 3 wt%, 5wt%, 7 wt%, 9wt%, 10 wt%, 12 wt%, 14 wt% or 15 wt%, etc., but not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.
According to experimental study, in the step (2) of the preparation method provided by the invention, if the addition amount of the carbon source is too large, the coating layer is too thick, the internal resistance of the material is increased, and the total amount of active substances is reduced; if the carbon source is added in an excessively small amount, the carbon coating is not uniform, and the conductivity of the material is affected.
Preferably, in the step (3), the mass of the polyaniline fiber (conductive agent) is 0.5 to 2 wt% of the mass of the reaction raw material containing lithium, iron and phosphorus, for example, 0.5wt%, 0.75 wt%, 1wt%, 1.2 wt%, 1.5wt%, 1.7 wt%, 1.9wt% or 2 wt%, etc., but not limited to the recited values, and other non-recited values within the range of the values are equally applicable; the mass of dimethyl sulfoxide is 0.5 to 2 wt% of the mass of the reaction raw material containing lithium, iron and phosphorus, for example, 0.5wt%, 0.75 wt%, 1wt%, 1.2 wt%, 1.5wt%, 1.7 wt%, 1.9wt% or 2 wt%, etc., but the present invention is not limited to the listed values, and other non-listed values within the range of the values are applicable.
Preferably, in the step (4), the solution of polyaniline mixed with dimethyl sulfoxide is dispersed in the mixed solution B, and the mixing time is 2 hours;
preferably, the spray drying tower in step (5) has an inlet temperature of 120 to 300 ℃, for example 120 ℃, 130 ℃, 140 ℃, 150 ℃, 175 ℃,200 ℃, 225 ℃, 250 ℃, or 300 ℃, etc., but is not limited to the recited values, other non-recited values within the range are equally applicable, and an outlet temperature of 50 to 100 ℃, for example 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, or 100 ℃, etc., but is not limited to the recited values, other non-recited values within the range are equally applicable;
preferably, in step (6), the freeze-drying comprises the steps of,
a. firstly, placing the material to be freeze-dried into a freeze-drying box cooled to the temperature of minus 10 ℃ to minus 50 ℃ for 3 to 5 hours, and freezing the material; b. when the vacuum diffusion pump is started and the pressure is reduced to 1.3-13 and Pa, the ice starts to sublimate, and sublimated water vapor is formed into ice crystals in the condenser; to ensure sublimation of ice, the heating system is turned on and the shelves are heated to 30-60 ℃.
The freeze-drying box temperature ranges from-10 ℃ to-50 ℃, such as-10 ℃, -20 ℃, -30 ℃, -40 ℃, -50 ℃, and the like, but is not limited to the recited values, and other non-recited values within the range are equally applicable.
The freezing time ranges from 3 to 5h, such as 3h, 3.5h, 4h, 4.5 h, 5h, etc., but are not limited to the recited values, as other non-recited values within the range are equally applicable.
The vacuum diffusion pump pressure ranges from 1.3 to 13 Pa, for example, from 1.3Pa, 2.3 Pa, 4.3 Pa, 6.3 Pa, 8.3 Pa, 10.3 Pa, 12 Pa, 13 Pa, etc., but are not limited to the recited values, and other non-recited values within the range are equally applicable.
The shelf heating temperature ranges from 30℃to 60℃such as 30℃35℃40℃45℃50℃55℃60℃and the like, but is not limited to the values recited, and other values not recited in the ranges are equally applicable.
Preferably, in the step (7), the reducing atmosphere is nitrogen and/or argon; the sintering temperature is 600-800 ℃, preferably 650-750 ℃; the sintering time is 5-8 h.
The sintering temperature is, for example, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, or the like, but is not limited to the values recited, and other values not recited in the range are equally applicable.
The sintering time is, for example, 5h, 6 h, 6.5 h, 7 h, or 8h, etc., but is not limited to the recited values, and other non-recited values within the range are equally applicable.
The average particle size of the lithium iron phosphate material prepared by the preparation method of the present invention is 3 to 15 μm, for example, 3 μm, 5 μm, 7 μm, 9 μm, 10 μm, 12 μm or 15 μm, etc., but is not limited to the recited values, and other non-recited values within the range of the values are equally applicable.
The invention also provides the spherical lithium iron phosphate material obtained by the preparation method.
The invention also provides an application of the spherical lithium iron phosphate material prepared by the preparation method in a lithium ion battery.
Compared with the prior art, the preparation method of the spherical lithium iron phosphate anode material has the following advantages:
(1) According to the invention, the polyaniline conductive agent is introduced in the dispersing stage, so that the conductivity of a finished product after sintering can be greatly enhanced, and the electrochemical performance of the product is improved; the spray material is subjected to freeze drying before sintering, so that aggregation of precursors is greatly reduced, and aggregation growth of spherical particles during sintering is reduced; the carbon quantity taken away by the volatilization of the moisture during the sintering of the spray material is greatly reduced, and the carbon source cost is saved.
(2) The invention has simple process, can effectively improve the appearance of the anode material and improve the electrochemical performance of the material. Compared with the cooling and drying process without cooling and drying, the secondary spherical appearance of the material is regular after the cooling and drying process of the spray material is added, and the cycle retention rate is improved from 85% to 93% in 2000 weeks.
Drawings
Fig. 1 is an SEM image of lithium iron phosphate obtained in example 1 of the present invention.
Fig. 2 is an SEM magnified view of a single lithium iron phosphate sphere obtained in example 1 of the present invention.
FIG. 3 is an SEM image of a sample of comparative example 1 of the present invention.
Detailed Description
For better illustrating the present invention, the technical scheme of the present invention is convenient to understand, and the present invention is further described in detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
Unless defined otherwise, technical terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.
The following are representative but non-limiting examples of the present invention.
Example 1
This example prepares lithium iron phosphate as follows:
(1) Wet grinding ferric phosphate and lithium carbonate to obtain a mixed solution A, wherein the molar ratio of elements of Li to Fe to P in the reaction raw materials containing lithium, iron and phosphorus is 1:0.9:1;
(2) Adding sucrose to disperse in the mixed solution A to obtain a mixed solution B, wherein the mass of the sucrose is 1wt% of the mass of the reaction raw materials containing lithium, iron and phosphorus;
(3) Polyaniline fiber (conductive agent) is dissolved in dimethyl sulfoxide to obtain a solution of polyaniline mixed with dimethyl sulfoxide (which is convenient for uniform mixing with the precursor);
(4) Dispersing a solution of polyaniline mixed with dimethyl sulfoxide into the mixed solution B to obtain a mixed solution C, wherein the mass of polyaniline fiber (conductive agent) is 0.5wt% of the mass of the reaction raw material containing lithium, iron and phosphorus, and the mass of dimethyl sulfoxide is 0.5wt% of the mass of the reaction raw material containing lithium, iron and phosphorus;
(5) And (3) spray-drying the mixed solution C to obtain a spray material, wherein the inlet temperature of a spray drying tower is 260 ℃ and the outlet temperature of the spray drying tower is 80 ℃.
(6) Freeze-drying the spray material (greatly removing water and dimethyl sulfoxide) to obtain a sintering precursor, wherein the freeze-drying comprises the following steps,
a. firstly, placing the material to be freeze-dried into a freeze-drying box cooled to-10 ℃ for 3 hours, and freezing the material; b. when the vacuum diffusion pump is started and the pressure is reduced to 1.3Pa, the ice starts to sublimate, and sublimated water vapor is formed into ice crystals in the condenser; in order to ensure sublimation of ice, a heating system is started, a shelf is heated to 30 ℃, the temperature range of the freeze-drying box is-10 ℃, and the freezing time is 3 hours;
(7) And (3) sintering the precursor obtained in the step (6) under the condition of nitrogen atmosphere at 700 ℃ to obtain a finished product.
The performance test results of the lithium iron phosphate material prepared in this example are shown in table 1.
FIGS. 1 and 2 are SEM images of the product obtained in this example, and it can be seen from the figures that the overall sphericity is good, the dispersion is uniform, the individual spherical particles are well grown, and the average particle size of the spherical particles is 6.5. Mu.m.
Example 2
In this example, the same materials and operations as in example 1 were carried out except that the molar ratio of Li to Fe to P in step (3) was 1.05:1:1.
The average particle size of the particles was 6.8. Mu.m.
The performance test results of the lithium iron phosphate material prepared in this example are shown in table 1.
Example 3
This example was identical to example 1 except that lithium carbonate was replaced with lithium nitrate in step (4).
The average particle size of the particles was 7.2. Mu.m.
The performance test results of the lithium iron phosphate material prepared in this example are shown in table 1.
Example 4
This example is identical to example 1 except that sucrose is replaced with glucose in step (5).
The average particle size of the particles was 8.7. Mu.m.
The performance test results of the lithium iron phosphate material prepared in this example are shown in table 1.
Example 5
This example prepares lithium iron phosphate as follows:
(1) Wet grinding ferric phosphate and lithium nitrate to obtain a mixed solution A, wherein the molar ratio of elements of Li to Fe to P in the reaction raw materials containing lithium, iron and phosphorus is 1.1:0.9:1;
(2) Adding sucrose to disperse in the mixed solution A to obtain a mixed solution B, wherein the mass of the sucrose is 1.4 percent wt percent of the mass of the reaction raw materials containing lithium, iron and phosphorus;
(3) Polyaniline fiber (conductive agent) is dissolved in dimethyl sulfoxide to obtain a solution of polyaniline mixed with dimethyl sulfoxide (which is convenient for uniform mixing with the precursor);
(4) Dispersing a solution of polyaniline mixed with dimethyl sulfoxide into the mixed solution B to obtain a mixed solution C, wherein the mass of polyaniline fiber (conductive agent) is 1.5wt% of the mass of the reaction raw material containing lithium, iron and phosphorus, and the mass of dimethyl sulfoxide is 1.2 wt% of the mass of the reaction raw material containing lithium, iron and phosphorus;
(5) Spray drying the mixed solution C to obtain a spray material, wherein the inlet temperature of a spray drying tower is 220 ℃ and the outlet temperature of the spray drying tower is 90 ℃;
(6) Freeze-drying the spray material (greatly removing water and dimethyl sulfoxide) to obtain a sintering precursor, wherein the freeze-drying comprises the following steps:
a. firstly, placing the material to be freeze-dried into a freeze-drying box cooled to-20 ℃ for 4 hours, and freezing the material; b. when the vacuum diffusion pump is started and the pressure is reduced to 1.7Pa, the ice starts to sublimate, and sublimated water vapor is formed into ice crystals in the condenser; in order to ensure sublimation of ice, a heating system is started, a shelf is heated to 30 ℃, the temperature range of the freeze-drying box is-15 ℃, and the freezing time is 4 hours;
(7) And (3) sintering the precursor obtained in the step (6) under the condition of nitrogen atmosphere at 750 ℃ to obtain a finished product.
The average particle size of the particles was 4.7. Mu.m.
The performance test results of the lithium iron phosphate material prepared in this example are shown in table 1.
Example 6
This example prepares lithium iron phosphate as follows:
(1) Grinding ferric phosphate and lithium phosphate by a wet method to obtain a mixed solution A, wherein the molar ratio of elements of Li to Fe to P in the reaction raw materials containing lithium, iron and phosphorus is 1.05:0.95:1;
(2) Adding citric acid to disperse in the mixed solution A to obtain a mixed solution B, wherein the mass of sucrose is 1.8 percent wt percent of the mass of the reaction raw materials containing lithium, iron and phosphorus;
(3) Polyaniline fiber (conductive agent) is dissolved in dimethyl sulfoxide to obtain a solution of polyaniline mixed with dimethyl sulfoxide (which is convenient for uniform mixing with the precursor);
(4) Dispersing a solution of polyaniline mixed with dimethyl sulfoxide into the mixed solution B to obtain a mixed solution C, wherein the mass of polyaniline fiber (conductive agent) is 1.9wt% of the mass of the reaction raw material containing lithium, iron and phosphorus, and the mass of dimethyl sulfoxide is 0.4 wt% of the mass of the reaction raw material containing lithium, iron and phosphorus;
(5) Spray drying the mixed solution C to obtain a spray material, wherein the inlet temperature of a spray drying tower is 290 ℃ and the outlet temperature of the spray drying tower is 80 ℃;
(6) Freeze-drying the spray material (greatly removing water and dimethyl sulfoxide) to obtain a sintering precursor, wherein the freeze-drying comprises the following steps,
a. firstly, placing the material to be freeze-dried into a freeze-drying box cooled to the temperature of minus 28 ℃ for 3.5 hours, and freezing the material; b. when the vacuum diffusion pump is started and the pressure is reduced to 1.8Pa, the ice starts to sublimate, and sublimated water vapor is formed into ice crystals in the condenser; in order to ensure sublimation of ice, a heating system is started, the shelf is heated to 50 ℃, the temperature range of the freeze-drying box is minus 25 ℃, and the freezing time is 3.5 hours;
(7) And (3) sintering the precursor obtained in the step (6) at 710 ℃ under the condition of nitrogen atmosphere to obtain a finished product.
The average particle size of the particles was 9.4. Mu.m.
The performance test results of the lithium iron phosphate material prepared in this example are shown in table 1.
Comparative example 1
The comparative example was a blank control group without lyophilization.
The average particle size of the particles was 18.7. Mu.m.
The performance test results of the lithium iron phosphate material prepared in this comparative example are shown in table 1.
Fig. 3 is an SEM image of the product obtained in this example, from which it can be seen that the occurrence of severe blocking of the spherical particles greatly affects the overall morphology and electrical properties.
The performance test method comprises the following steps:
the lithium iron phosphate materials prepared in each example and comparative example were subjected to the following performance tests:
(1) Whisker size test: measuring the diameter and length of the sample whisker by using an electron scanning microscope;
(2) Electrochemical testing: the lithium iron phosphate material prepared by the invention is prepared into a positive pole piece, the negative pole is a graphite negative pole, the diaphragm is Celgard2400, and the electrolyte is LiPF of 1mol/L 6 And mixing dimethyl carbonate and ethyl methyl carbonate (volume ratio is 1:1:1) to form the 18650 cylindrical single battery. The preparation process of the positive pole piece comprises the following steps: mixing the positive electrode material, the conductive agent acetylene black and the binder PVDF according to the mass percentage of 94:3:3, and using N-methyl pyrrolidone as a solvent to prepare the cathode materialCoating the slurry on an aluminum foil, and vacuum drying to obtain the positive pole piece. The preparation process of the negative electrode plate comprises the steps of carrying out negative electrode proportioning on graphite, a thickening agent CMC, a binding agent SBR and conductive carbon powder according to a weight ratio of 95:1:2:2 under a water system to obtain uniform negative electrode slurry, uniformly coating the prepared negative electrode slurry on a negative electrode current collector Cu foil, and cooling to obtain the negative electrode plate. And under normal temperature conditions, testing the prepared cylindrical battery on a LAND battery testing system of the Wuhan Jino electronic limited company, wherein the charging and discharging voltage interval is 2.0-3.65V, and under the condition of 1C current density, testing the first discharging specific capacity and the 2000 th cyclic discharging specific capacity of the battery, and calculating the 2000 th cyclic capacity retention rate, wherein 2000 th cyclic capacity retention rate=2000 th cyclic discharging specific capacity/first discharging specific capacity.
The test results are shown in table 1 below:
table 1 test results
Project Average particle size (nm) 1C first discharge specific capacity (mAh/g) Specific discharge capacity (mAh/g) of 2000 th cycle Capacity retention for 2000 cycles (%)
Example 1 6.5 156.4 147.0 93.98
Example 2 6.8 158.7 149.9 94.45
Example 3 7.2 156.1 146.9 94.10
Example 4 8.7 157.6 148.3 94.10
Example 5 4.7 157.2 147.5 93.83
Example 6 9.4 156.8 146.4 93.37
Comparative example 1 18.7 136.0 101.1 74.34
As can be seen from Table 1, the lithium iron phosphate materials prepared in examples 1 to 6 of the present invention have good electrochemical properties, because the preparation method of the above examples is to obtain spherical lithium iron phosphate by freeze-drying and then sintering at high temperature, which can significantly improve the electrochemical properties of the materials.
As can be seen from table 1, comparative example 1 was lower in specific capacity for first discharge, specific capacity for 2000 th cycle discharge, and retention rate for 2000 th cycle capacity relative to example 1, because no freeze-drying was added to comparative example 1.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (8)

1. A preparation method of a spherical lithium iron phosphate positive electrode material is characterized by comprising the following steps: comprises the following steps of the method,
(1) Wet grinding an iron source, a lithium source and a phosphorus source to obtain a mixed solution A;
(2) Adding a carbon source to disperse in the mixed solution A to obtain a mixed solution B;
(3) Dissolving polyaniline fiber in dimethyl sulfoxide to obtain polyaniline mixed dimethyl sulfoxide solution; the mass of polyaniline is 0.5-2 wt% of the mass of the reaction raw materials containing lithium, iron and phosphorus in the mixed solution A, and the mass of dimethyl sulfoxide is 0.5-2 wt% of the mass of the reaction raw materials containing lithium, iron and phosphorus in the mixed solution A;
(4) Dispersing a solution of polyaniline mixed with dimethyl sulfoxide into the mixed solution B to obtain a mixed solution C;
(5) Spray drying the mixed solution C to obtain a spray material;
(6) Freeze-drying the spray material to obtain a sintering precursor;
the freeze-drying operation method comprises the following steps:
a. firstly, placing the material to be freeze-dried into a freeze-drying box cooled to the temperature of minus 10 ℃ to minus 50 ℃ for 3 to 5 hours, and freezing the material;
b. when the vacuum diffusion pump is started and the pressure is reduced to 1.3-13 and Pa, the ice starts to sublimate, and sublimated water vapor is formed into ice crystals in the condenser; in order to ensure sublimation of ice, a heating system is started, and the shelf is heated to 30-60 ℃;
(7) Sintering the precursor obtained in the step (6) at a high temperature under the condition of reducing atmosphere to obtain a finished product; the reducing atmosphere is nitrogen, the sintering temperature is 600-800 ℃, and the sintering time is 8-10 h.
2. The method for preparing the spherical lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: the iron source in the step (1) is ferric phosphate or ferric oxide, the lithium source is lithium carbonate or lithium nitrate, and the phosphorus source is phosphoric acid or ferric phosphate.
3. The method for preparing the spherical lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: in the reaction raw materials of iron, lithium and phosphorus in the step (1), the element molar ratio of Li to Fe to P is (1-1.1): (0.9-1.0): 1.
4. The method for preparing the spherical lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: the carbon source in the step (2) comprises any one or a combination of at least two of sucrose, glucose, starch, citric acid and polypropylene, the mass of the carbon source is 1-15 wt% of the mass of the reaction raw materials containing lithium, iron and phosphorus, and the dispersing time is 2 hours.
5. The method for preparing the spherical lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: in the step (4), the solution of the polyaniline fiber mixed with dimethyl sulfoxide is dispersed in the mixed solution B, and the mixing time is 2 hours.
6. The method for preparing the spherical lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: and (3) drying in the step (5) by using a spray drying tower, wherein the inlet temperature of the spray drying tower is 120-300 ℃ and the outlet temperature of the spray drying tower is 50-100 ℃.
7. The spherical lithium iron phosphate positive electrode material obtained by the preparation method according to any one of claims 1-6.
8. The application of the spherical lithium iron phosphate anode material prepared by the preparation method according to any one of claims 1-6 in a lithium ion battery.
CN202110927429.5A 2021-08-13 2021-08-13 Preparation method and application of spherical lithium iron phosphate positive electrode material Active CN113683072B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110927429.5A CN113683072B (en) 2021-08-13 2021-08-13 Preparation method and application of spherical lithium iron phosphate positive electrode material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110927429.5A CN113683072B (en) 2021-08-13 2021-08-13 Preparation method and application of spherical lithium iron phosphate positive electrode material

Publications (2)

Publication Number Publication Date
CN113683072A CN113683072A (en) 2021-11-23
CN113683072B true CN113683072B (en) 2023-06-20

Family

ID=78579655

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110927429.5A Active CN113683072B (en) 2021-08-13 2021-08-13 Preparation method and application of spherical lithium iron phosphate positive electrode material

Country Status (1)

Country Link
CN (1) CN113683072B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117263161B (en) * 2023-11-03 2024-05-31 云南云天化股份有限公司 Preparation method of uniform carbon-coated lithium iron phosphate positive electrode material

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108878797A (en) * 2017-09-22 2018-11-23 久兆新能源科技股份有限公司 A kind of high compacted density lithium iron phosphate positive material and anode pole piece

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103208626B (en) * 2012-01-17 2016-03-02 深圳市沃特玛电池有限公司 A kind of method adopting aniline to prepare lithium iron phosphate/carbon composite material
CN104638242A (en) * 2015-02-06 2015-05-20 重庆特瑞电池材料股份有限公司 Method for synthesizing lithium ion battery cathode material lithium iron phosphate through in situ polymerizing and cladding
CN104716320B (en) * 2015-03-10 2017-06-16 中国科学院过程工程研究所 A kind of LiFePO4 of composite cladding, its preparation method and lithium ion battery
CN109935803B (en) * 2018-11-28 2021-04-27 万向一二三股份公司 Preparation method of lithium iron phosphate cathode material
EP3770996A1 (en) * 2019-07-23 2021-01-27 Formosa Plastics Transport Corporation Method for manufacturing lithium iron phosphate/carbon composite cathode material for secondary lithium ion battery
CN112768688B (en) * 2019-11-05 2023-06-06 贝特瑞（天津）纳米材料制造有限公司 Lithium iron phosphate material, preparation method thereof and lithium ion battery
CN112397698B (en) * 2020-11-16 2022-02-18 合肥国轩高科动力能源有限公司 Composite conductive agent coated lithium iron phosphate material and preparation method and application thereof

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108878797A (en) * 2017-09-22 2018-11-23 久兆新能源科技股份有限公司 A kind of high compacted density lithium iron phosphate positive material and anode pole piece

Also Published As

Publication number Publication date
CN113683072A (en) 2021-11-23

Similar Documents

Publication Publication Date Title
CN113363483A (en) Olivine-structure positive electrode material, preparation method and application thereof, and lithium ion battery
CN111029578B (en) Modified hard carbon negative electrode material and preparation method thereof
CN111211314A (en) Carbon-coated porous silicon-carbon composite material and preparation method thereof
CN114335532A (en) Lithium ion battery anode lithium supplementing method based on freeze drying and product
CN114497508A (en) Power type artificial graphite composite material and preparation method thereof
CN114735670B (en) Preparation method and application of high-performance lithium iron phosphate
CN115072703A (en) Composite negative electrode material and preparation method and application thereof
CN113683072B (en) Preparation method and application of spherical lithium iron phosphate positive electrode material
CN110010873B (en) Preparation method of mixed anode slurry
CN105845886A (en) Negative electrode material for ion battery and preparation method of negative electrode material
CN113690420B (en) Nitrogen-sulfur doped silicon-carbon composite material and preparation method and application thereof
CN112510179B (en) Battery negative electrode material and preparation method and application thereof
CN116741973B (en) Graphene-like coated silicon-carbon nanotube composite material and preparation method and application thereof
CN109473648B (en) Silicon-carbon composite material for lithium ion battery and preparation method thereof
CN111188022A (en) Preparation method of silicon cathode material coated by vapor deposition carbon nanotube
CN115159527B (en) Hard carbon coated silicon nanoparticle composite microsphere negative electrode material and preparation method and application thereof
CN111072012A (en) Microcrystalline graphite doped graphene negative electrode material of lithium ion battery and preparation method thereof
CN116314762A (en) Lithium iron manganese phosphate positive electrode material, and preparation method and application thereof
CN112391671B (en) Method for reconstructing ternary single crystal material from waste ternary polycrystalline material
CN114261951B (en) Vanadium-doped spindle-shaped lithium iron phosphate cathode material and self-propagating combustion preparation method thereof
CN114789998B (en) Negative electrode material, preparation method thereof and battery
CN112802998B (en) Silicon-based negative electrode and preparation method and application thereof
CN117476859A (en) Long-cycle anode material and preparation method and application thereof
CN118771442A (en) Low-temperature lithium ion battery negative electrode material and preparation method thereof
CN117712352A (en) Silicon-based composite material, preparation method and application thereof, negative electrode plate and battery

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