CN111483995A - Preparation method of lithium iron phosphate - Google Patents
Preparation method of lithium iron phosphate Download PDFInfo
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- CN111483995A CN111483995A CN202010308430.5A CN202010308430A CN111483995A CN 111483995 A CN111483995 A CN 111483995A CN 202010308430 A CN202010308430 A CN 202010308430A CN 111483995 A CN111483995 A CN 111483995A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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- 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 discloses a preparation method of lithium iron phosphate. Adding phosphorus-iron slag smelted by phosphorus into a crusher for crushing, sieving, adding oversize materials into a sand mill for sand milling, performing magnetic separation, adding phosphoric acid and lithium carbonate into an obtained magnetic separation material, mixing and stirring, drying, calcining the obtained dried material in a rotary kiln, introducing air, adding a glucose solution into a first calcined material obtained after calcination, stirring, adding the mixture into the sand mill for sand milling until the particle size of the slurry is 300-450nm, performing spray drying, introducing inert gas into an obtained dried material furnace for calcination, crushing, sieving, removing iron and packaging to obtain the lithium iron phosphate. The lithium iron phosphate material is obtained by taking the phosphorus-iron slag as a raw material, and the lithium iron phosphate obtained by the method has high capacity, excellent electrical property and low cost.
Description
Technical Field
The invention relates to a preparation method of lithium iron phosphate, belonging to the field of new energy materials of lithium batteries.
Background
The phosphorus-iron slag is a phosphorus chemical industry byproduct, is large in quantity and low in price, mainly comprises a mixture of phosphorus and iron phosphide, generates millions of tons every year, and effectively utilizes the waste with high added value, thereby becoming one of important topics of phosphorus chemical industry production.
The lithium iron phosphate is applied to energy storage, and is mainly benefited from low price, good circulation and high capacity, and a symbolic sign of inflection point appearing in the technical prospects of various energy storage batteries is that the cost of each kilowatt-hour (KWh) generating unit is lower than 1500 yuan, so that the price of the lithium iron phosphate is greatly reduced.
Disclosure of Invention
In view of the above, the invention provides a preparation method of lithium iron phosphate, which uses phosphorus-iron slag as a raw material, obtains a phosphorus-iron compound with higher purity by magnetic separation after levigating, then adds lithium carbonate, then mixes phosphoric acid, adjusts the iron-phosphorus ratio, and carries out oxidation sintering, thereby obtaining an iron-phosphorus-lithium mixture, then carries out carbon preparation, and then carries out sand grinding, spray drying and calcination, thereby obtaining a lithium iron phosphate material.
The invention solves the technical problems by the following technical means:
a preparation method of lithium iron phosphate comprises the steps of adding phosphorus iron slag smelted by phosphorus into a crusher for crushing, then sieving through a 200-grade and 300-grade sieve, adding oversize materials into a sand mill for sand grinding until the particle size of the materials is 300-grade and 500nm, then carrying out 3-5-grade magnetic separation, adding phosphoric acid and lithium carbonate into the obtained magnetic separation materials, mixing, stirring and drying, calcining the obtained dry materials in a rotary kiln, simultaneously introducing air, calcining at the temperature of 500-grade and 600 ℃ for 3-5h, adding glucose solution into the obtained first calcined materials, stirring, then adding into the sand mill for sand grinding until the particle size of the slurry is 300-grade and 450nm, then carrying out spray drying, introducing inert gas into the obtained dry material kiln for calcining, crushing, sieving, deironing and packaging to obtain the lithium iron phosphate.
The total mass fraction of iron and phosphorus in the ferrophosphorus slag is more than or equal to 80%, the nickel-cobalt content is lower than 50ppm, and the copper-zinc-chromium content is lower than 100 ppm.
Adding the oversize material into a sand mill, namely adding pure water into the oversize material to pulp, then adding a dispersing agent accounting for 0.1-0.3% of the total mass of the pulp, wherein the mass fraction of solids in the pulp is 40-45%, stirring, then feeding into the sand mill, lining ceramic in the sand mill, adding zirconium balls with the diameter of 0.3-0.5mm into a cavity, and filling volume of the zirconium balls accounts for 75-85% of the volume of the cavity of the sand mill.
In the magnetic separation process, a magnet with the magnetic strength of 12000-20000GS is selected for magnetic separation.
And (3) adding phosphoric acid and lithium carbonate into the magnetic separation material to obtain lithium in the mixture: iron: the molar ratio of phosphorus is 1.02-1.05:1: 1.003-1.005.
And (3) during the calcination process of the dried material in the rotary kiln, introducing air to maintain the volume fraction of oxygen in the atmosphere in the rotary kiln to be more than or equal to 18%.
The mass fraction of glucose in the glucose solution is 10-15%, the mass fraction of the dispersant is 0.5-1%, and the dispersant is polyethylene glycol.
The spray drying process adopts a centrifugal spray dryer, the air inlet temperature is 200-280 ℃, the discharging temperature is less than or equal to 90 ℃, and the discharging particle size is 0.5-5 mu m.
The obtained dry material is calcined in inert gas, the calcination period is 25-30h, the calcination is divided into a temperature rise section, a heat preservation section and a temperature reduction section, the temperature rise rate of the temperature rise section is 120 ℃ per hour, the temperature of the heat preservation section is 720 ℃ and 750 ℃, the heat preservation time is 10-15h, the temperature is reduced to the material temperature which is less than 100 ℃, then the material is discharged, the inert gas in the calcination process is nitrogen, the adding amount of the nitrogen per hour is 5-10 times of the volume of a cavity of the kiln, the pressure in the kiln in the calcination process is maintained to be higher than the atmospheric pressure by 150 Pa, and the gas humidity in the heat preservation section is lower than 3%.
The invention takes the ferrophosphorus slag as the raw material, after being milled, the ferrophosphorus and other magnetic substances are dissociated out, then obtaining a phosphorus-iron compound with higher purity (the content of phosphorus and iron is more than 98 percent) by magnetic separation, then mixing lithium carbonate and phosphoric acid, adjusting the molar ratio of lithium, iron and phosphorus in the mixture, then oxidizing iron and phosphorus into trivalent state and pentavalent state by oxidizing calcination, then mixing a carbon source, carrying out spray drying after levigating, sanding until the particle size of the slurry is 300-450nm, carrying out spray drying to form a spray-dried material, in the spray drying process, fog drops are generally formed firstly, the fog drops are slurry containing carbon source solution, in the spray drying process, water is evaporated, carbon source is crystallized and separated out and is coated on the surface of solid particles, then introducing inert gas into the kiln for calcination to obtain the lithium iron phosphate, wherein the whole calcination process comprises the following steps: the calcination period is 25-30h, the calcination is divided into a temperature rising section, a heat preservation section and a temperature reduction section, the temperature rising rate of the temperature rising section is 120 ℃/h, the temperature of the heat preservation section is 720-750 ℃, the heat preservation time is 10-15h, the material is discharged after being cooled to the temperature of less than 100 ℃, the inert gas in the calcination process is nitrogen, the adding amount of the nitrogen per hour is 5-10 times of the volume of the cavity of the kiln, the pressure in the kiln in the calcination process is maintained to be 150 Pa higher than the atmospheric pressure, and the gas humidity in the heat preservation section is lower than 3%.
The lithium iron phosphate is obtained by twice calcination, namely, oxidizing calcination for one time to oxidize iron and phosphorus, and performing high-temperature calcination for the second time in an inert atmosphere to form lithium iron phosphate and a carbon coating layer, and then crushing, screening, deironing and packaging.
The invention has the beneficial effects that: the method comprises the steps of taking ferrophosphorus slag as a raw material, carrying out magnetic separation after levigating to obtain a ferrophosphorus compound with high purity, then adding lithium carbonate, mixing phosphoric acid, adjusting the iron-phosphorus ratio, carrying out oxidation sintering to obtain an iron-phosphorus-lithium mixture, then carrying out carbon preparation, carrying out sand grinding, carrying out spray drying, and calcining to obtain a lithium iron phosphate material.
Drawings
FIG. 1 is an SEM image of a product of example 1 of the present invention.
FIG. 2 is an SEM image of the product of example 2 of the present invention.
FIG. 3 is an SEM image of a product of example 3 of the present invention.
Figure 4 is an XRD pattern of the products of examples 1 and 2 of the invention.
Detailed Description
The invention will be described in detail with reference to specific examples, in which the method for preparing lithium iron phosphate of this example includes adding the phosphorous iron slag from phosphorous smelting into a pulverizer to pulverize, then sieving with a 200-plus-300-mesh sieve, adding the oversize material into a sand mill for sand milling until the particle size of the material is 300-plus-500 nm, then, after 3-5 levels of magnetic separation, adding phosphoric acid and lithium carbonate into the obtained magnetic separation material, mixing and stirring the mixture, drying the mixture, calcining the obtained dried material in a rotary kiln, simultaneously introducing air, calcining at the temperature of 500-450 ℃ for 3-5h, adding the obtained first calcined material into a glucose solution, stirring, adding into a sand mill, sanding until the particle size of the slurry is 300-450nm, and then spray drying, introducing inert gas into the obtained dry material kiln for calcination, and obtaining the lithium iron phosphate through crushing, screening, iron removal and packaging.
The total mass fraction of iron and phosphorus in the ferrophosphorus slag is more than or equal to 80%, the nickel-cobalt content is lower than 50ppm, and the copper-zinc-chromium content is lower than 100 ppm.
Adding the oversize material into a sand mill, namely adding pure water into the oversize material to pulp, then adding a dispersing agent accounting for 0.1-0.3% of the total mass of the pulp, wherein the mass fraction of solids in the pulp is 40-45%, stirring, then feeding into the sand mill, lining ceramic in the sand mill, adding zirconium balls with the diameter of 0.3-0.5mm into a cavity, and filling volume of the zirconium balls accounts for 75-85% of the volume of the cavity of the sand mill.
In the magnetic separation process, a magnet with the magnetic strength of 12000-20000GS is selected for magnetic separation.
And (3) adding phosphoric acid and lithium carbonate into the magnetic separation material to obtain lithium in the mixture: iron: the molar ratio of phosphorus is 1.02-1.05:1: 1.003-1.005.
And (3) during the calcination process of the dried material in the rotary kiln, introducing air to maintain the volume fraction of oxygen in the atmosphere in the rotary kiln to be more than or equal to 18%.
The mass fraction of glucose in the glucose solution is 10-15%, the mass fraction of the dispersant is 0.5-1%, and the dispersant is polyethylene glycol.
The spray drying process adopts a centrifugal spray dryer, the air inlet temperature is 200-280 ℃, the discharging temperature is less than or equal to 90 ℃, and the discharging particle size is 0.5-5 mu m.
The obtained dry material is calcined in inert gas, the calcination period is 25-30h, the calcination is divided into a temperature rise section, a heat preservation section and a temperature reduction section, the temperature rise rate of the temperature rise section is 120 ℃ per hour, the temperature of the heat preservation section is 720 ℃ and 750 ℃, the heat preservation time is 10-15h, the temperature is reduced to the material temperature which is less than 100 ℃, then the material is discharged, the inert gas in the calcination process is nitrogen, the adding amount of the nitrogen per hour is 5-10 times of the volume of a cavity of the kiln, the pressure in the kiln in the calcination process is maintained to be higher than the atmospheric pressure by 150 Pa, and the gas humidity in the heat preservation section is lower than 3%.
Example 1
A preparation method of lithium iron phosphate comprises the steps of adding phosphorus iron slag smelted by phosphorus into a pulverizer for pulverization, then sieving with a 250-mesh sieve, adding oversize materials into a sand mill for sand grinding until the particle size of the materials is 450nm, then carrying out 4-level magnetic separation, adding phosphoric acid and lithium carbonate into the obtained magnetic separation materials, mixing and stirring, drying, calcining the obtained dried materials in a rotary kiln, simultaneously introducing air, introducing a glucose solution into the obtained first calcined material at the calcining temperature of 550 ℃ for 4 hours, stirring, adding the mixture into the sand mill for sand grinding until the particle size of slurry is 420nm, carrying out spray drying, introducing an inert gas into the obtained dried material kiln for calcination, and obtaining the lithium iron phosphate through pulverization, screening, iron removal and packaging.
The total mass fraction of iron and phosphorus in the ferrophosphorus slag is more than or equal to 80%, the nickel-cobalt content is lower than 50ppm, and the copper-zinc-chromium content is lower than 100 ppm.
Adding the oversize material into a sand mill, adding pure water into the oversize material to pulp, then adding a dispersing agent accounting for 0.15% of the total mass of the pulp, wherein the mass fraction of solids in the pulp is 42%, stirring, then feeding into the sand mill, lining the sand mill with ceramic, adding zirconium balls with the diameter of 0.3mm into a cavity, and filling volume of the zirconium balls accounts for 80% of the volume of the cavity of the sand mill.
And in the magnetic separation process, a 12500GS magnet with magnetic strength is selected for magnetic separation.
And (3) adding phosphoric acid and lithium carbonate into the magnetic separation material to obtain lithium in the mixture: iron: the molar ratio of phosphorus was 1.03:1: 1.004.
And (3) during the calcination process of the dried material in the rotary kiln, introducing air to maintain the volume fraction of oxygen in the atmosphere in the rotary kiln to be more than or equal to 18%.
The mass fraction of glucose in the glucose solution is 12%, a dispersing agent is added into the glucose solution, the mass fraction of the dispersing agent is 0.8%, and the dispersing agent is polyethylene glycol.
The spray drying process adopts a centrifugal spray dryer, the air inlet temperature is 260 ℃, the discharging temperature is less than or equal to 90 ℃, and the discharged particle size is 0.95 mu m.
Calcining the obtained dry material in inert gas for 28h, wherein the calcining period is divided into a temperature rising section, a heat preservation section and a temperature reduction section, the temperature rising rate of the temperature rising section is 110 ℃/h, and the temperature of the heat preservation section is 740
The heat preservation time is 14 hours, the temperature is reduced to the temperature of the material to be less than 100 ℃, then the material is discharged, the inert gas in the calcining process is nitrogen, the adding amount of the nitrogen per hour is 8 times of the volume of the cavity of the kiln, the pressure in the kiln is kept to be 180Pa higher than the atmospheric pressure in the calcining process, and the humidity of the gas in the heat preservation section is lower than 3%.
The detection data of the finally obtained lithium iron phosphate are as follows:
example 2
A preparation method of lithium iron phosphate comprises the steps of adding phosphorus iron slag smelted by phosphorus into a pulverizer for pulverization, then sieving with a 225-mesh sieve, adding oversize materials into a sand mill for sand grinding until the particle size of the materials is 400nm, then carrying out 5-level magnetic separation, adding phosphoric acid and lithium carbonate into the obtained magnetic separation materials, mixing and stirring, drying, calcining the obtained dried materials in a rotary kiln, simultaneously introducing air, calcining at 580 ℃ for 4.5 hours, adding glucose solution into the obtained first calcined material, stirring, then adding the mixture into the sand mill for sand grinding until the particle size of the slurry is 400nm, then carrying out spray drying, introducing inert gas into the obtained dried material kiln for calcination, and obtaining the lithium iron phosphate through pulverization, screening, iron removal and packaging.
The total mass fraction of iron and phosphorus in the ferrophosphorus slag is more than or equal to 80%, the nickel-cobalt content is lower than 50ppm, and the copper-zinc-chromium content is lower than 100 ppm.
Adding the oversize material into a sand mill, adding pure water into the oversize material to pulp, then adding a dispersing agent accounting for 0.15% of the total mass of the pulp, wherein the mass fraction of solids in the pulp is 43%, stirring, then feeding into the sand mill, lining the sand mill with ceramic, adding zirconium balls with the diameter of 0.4mm into a cavity, and filling volume of the zirconium balls accounts for 80% of the volume of the cavity of the sand mill.
And in the magnetic separation process, a magnet with the magnetic strength of 15000GS is selected for magnetic separation.
And (3) adding phosphoric acid and lithium carbonate into the magnetic separation material to obtain lithium in the mixture: iron: the molar ratio of phosphorus was 1.04:1: 1.005.
And (3) during the calcination process of the dried material in the rotary kiln, introducing air to maintain the volume fraction of oxygen in the atmosphere in the rotary kiln to be more than or equal to 18%.
The mass fraction of glucose in the glucose solution is 14%, a dispersing agent is added into the glucose solution, the mass fraction of the dispersing agent is 0.8%, and the dispersing agent is polyethylene glycol.
The spray drying process adopts a centrifugal spray dryer, the air inlet temperature is 245 ℃, the discharging temperature is less than or equal to 90 ℃, and the discharged particle size is 1.2 mu m.
The obtained dry material is calcined in inert gas, the calcination period is 28 hours, the calcination is divided into a temperature rising section, a heat preservation section and a temperature reduction section, the temperature rising rate of the temperature rising section is 114 ℃/h, the temperature of the heat preservation section is 735 ℃, the heat preservation time is 14 hours, the temperature is reduced to the material temperature which is less than 100 ℃, then the material is discharged, the inert gas in the calcination process is nitrogen, the adding amount of the nitrogen per hour is 10 times of the volume of a cavity of the kiln, the pressure in the kiln in the calcination process is kept higher than atmospheric pressure by 165Pa, and the humidity of the gas in the heat preservation section is lower than 3%.
The detection data of the finally obtained lithium iron phosphate are as follows:
example 3
A preparation method of lithium iron phosphate comprises the steps of adding phosphorus iron slag smelted by phosphorus into a pulverizer for pulverization, then sieving with a 300-mesh sieve, adding oversize materials into a sand mill for sand grinding until the particle size of the materials is 500nm, then carrying out 4-level magnetic separation, adding phosphoric acid and lithium carbonate into the obtained magnetic separation materials, mixing and stirring, drying, calcining the obtained dried materials in a rotary kiln, simultaneously introducing air, introducing a glucose solution into the obtained first calcined material at a calcination temperature of 580 ℃ for 5h, stirring, adding the mixture into the sand mill for sand grinding until the particle size of the slurry is 420nm, carrying out spray drying, introducing an inert gas into the obtained dried material kiln for calcination, and obtaining the lithium iron phosphate through pulverization, screening, iron removal and packaging.
The total mass fraction of iron and phosphorus in the ferrophosphorus slag is more than or equal to 80%, the nickel-cobalt content is lower than 50ppm, and the copper-zinc-chromium content is lower than 100 ppm.
Adding the oversize material into a sand mill, adding pure water into the oversize material to pulp, then adding a dispersing agent accounting for 0.15% of the total mass of the pulp, wherein the mass fraction of solids in the pulp is 45%, stirring, then feeding into the sand mill, lining the sand mill with ceramic, adding zirconium balls with the diameter of 0.45mm into a cavity, and filling volume of the zirconium balls accounts for 85% of the volume of the cavity of the sand mill.
And in the magnetic separation process, a magnet with the magnetic strength of 15000GS is selected for magnetic separation.
And (3) adding phosphoric acid and lithium carbonate into the magnetic separation material to obtain lithium in the mixture: iron: the molar ratio of phosphorus was 1.035:1: 1.0045.
And (3) during the calcination process of the dried material in the rotary kiln, introducing air to maintain the volume fraction of oxygen in the atmosphere in the rotary kiln to be more than or equal to 18%.
The mass fraction of glucose in the glucose solution is 13%, a dispersing agent is added into the glucose solution, the mass fraction of the dispersing agent is 0.8%, and the dispersing agent is polyethylene glycol.
The spray drying process adopts a centrifugal spray dryer, the air inlet temperature is 240 ℃, the discharging temperature is less than or equal to 90 ℃, and the discharging particle size is 2.1 mu m.
The obtained dry material is calcined in inert gas, the calcination period is 28 hours, the calcination is divided into a temperature rising section, a heat preservation section and a temperature reduction section, the temperature rising rate of the temperature rising section is 115 ℃/h, the temperature of the heat preservation section is 735 ℃, the heat preservation time is 14 hours, the temperature is reduced to the material temperature which is less than 100 ℃, then the material is discharged, the inert gas in the calcination process is nitrogen, the adding amount of the nitrogen per hour is 8 times of the volume of a cavity of the kiln, the pressure in the kiln in the calcination process is kept to be 180Pa higher than the atmospheric pressure, and the humidity of the gas in the heat preservation section is lower than 3%.
The detection data of the finally obtained lithium iron phosphate are as follows:
| index (I) | Iron to phosphorus ratio | Moisture content | D10 | D50 | D90 |
| Numerical value | 0.993 | 657ppm | 2.35μm | 1.24μm | 6.78μm |
| Bulk density | Cd | Co | Pb | Ca | Na |
| 0.51g/mL | 15.4ppm | 13.9ppm | 11.3ppm | 68.8ppm | 31.8ppm |
| Si | Ni | Mg | Zn | Al | Ti |
| 224.8ppm | 23.5ppm | 214.9ppm | 22.8ppm | 45.6ppm | 127.4ppm |
| Li | Tap density | Sulfur | BET | C | |
| 4.43％ | 0.91g/mL | 93.6ppm | 19.6m2/g | 2.54％ |
The lithium iron phosphate prepared in examples 1 to 3 was used as SEM, and the results are shown in fig. 1 to 3, where the obtained iron phosphate was granular and nearly spherical, the surface was significantly coated with carbon, and the single crystal particles were between 200 and 500 nm.
As a result of XRD analysis of the lithium iron phosphate of examples 1 and 2, the lithium iron phosphate obtained in examples 1 and 2 was high-crystallinity lithium iron phosphate and had no distinct peaks as shown in fig. 4.
The lithium iron phosphate prepared in examples 1 to 3 was prepared into a snap-on battery, and the electrochemical performance was tested, the assembly of the positive plate was carried out by mixing the lithium iron phosphate prepared in examples 1 to 3 at a stoichiometric ratio of m (active material): m (acetylene black): m (polyvinylidene fluoride PVDF): 90: 5: 5, preparing a positive slurry from N-methylpyrrolidone (NMP) as a solvent, uniformly coating the slurry on an aluminum foil, drying at 110 ℃ for 12 hours, and stamping into a positive plate, the quality of the plate was strictly controlled between 60 and 70mg, in a glove box filled with argon, using a metal lithium plate as a negative electrode, an electrolyte of 1 mol/L of L iPF6/EC + DEC + EMC (volume ratio of 1: 1: 1), and a diaphragm of Celgard2400, and assembling into a button cell type CR2032, and using a DC-5C electrochemical performance tester manufactured by shanghai square electronics limited at 0.2C (0.2 mA/cm)2) And (3) carrying out charge-discharge test at a multiplying power and a temperature of 25 +/-5 ℃ and between 2.0 and 4.2V, circulating for 50 times, and detecting the electrochemical performance of each sample to finally obtain the following lithium iron phosphate results:
the testing method of the compaction density comprises the steps of weighing 1g of powder, placing the powder on a die on a compaction density tester, enabling the diameter of the die to be 3cm, pressing the powder under the condition that the pressure is 3T until the volume of the powder is not changed any more, and dividing the powder by the volume to obtain the compaction density of the powder.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.
Claims (9)
1. A preparation method of lithium iron phosphate is characterized in that phosphorus iron slag smelted by phosphorus is added into a crusher to be crushed, then the crushed phosphorus iron slag is sieved by a sieve with 200-fold and 300-fold meshes, oversize materials are added into a sand grinder to be ground until the particle size of the materials is 500nm, then the materials are subjected to 3-5-level magnetic separation, phosphoric acid and lithium carbonate are added into the obtained magnetic separation material, the obtained magnetic separation material is mixed, stirred and dried, the obtained dried material is calcined in a rotary kiln, air is introduced simultaneously, the calcination temperature is 500-fold and 600 ℃, the calcination time is 3-5h, the obtained first calcined material is added into glucose solution, the mixed material is added into the sand grinder and ground until the particle size of the slurry is 300-fold and 450nm, then spray drying is carried out, inert gas is introduced into the obtained dried material kiln to be calcined, and the lithium iron phosphate is obtained through.
2. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: the total mass fraction of iron and phosphorus in the ferrophosphorus slag is more than or equal to 80%, the nickel-cobalt content is lower than 50ppm, and the copper-zinc-chromium content is lower than 100 ppm.
3. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: adding the oversize material into a sand mill, namely adding pure water into the oversize material to pulp, then adding a dispersing agent accounting for 0.1-0.3% of the total mass of the pulp, wherein the mass fraction of solids in the pulp is 40-45%, stirring, then feeding into the sand mill, lining ceramic in the sand mill, adding zirconium balls with the diameter of 0.3-0.5mm into a cavity, and filling volume of the zirconium balls accounts for 75-85% of the volume of the cavity of the sand mill.
4. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: in the magnetic separation process, a magnet with the magnetic strength of 12000-20000GS is selected for magnetic separation.
5. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: and (3) adding phosphoric acid and lithium carbonate into the magnetic separation material to obtain lithium in the mixture: iron: the molar ratio of phosphorus is 1.02-1.05:1: 1.003-1.005.
6. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: and (3) during the calcination process of the dried material in the rotary kiln, introducing air to maintain the volume fraction of oxygen in the atmosphere in the rotary kiln to be more than or equal to 18%.
7. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: the mass fraction of glucose in the glucose solution is 10-15%, the mass fraction of the dispersant is 0.5-1%, and the dispersant is polyethylene glycol.
8. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: the spray drying process adopts a centrifugal spray dryer, the air inlet temperature is 200-280 ℃, the discharging temperature is less than or equal to 90 ℃, and the discharging particle size is 0.5-5 mu m.
9. The method for preparing lithium iron phosphate according to claim 1, wherein the method comprises the following steps: the obtained dry material is calcined in inert gas, the calcination period is 25-30h, the calcination is divided into a temperature rise section, a heat preservation section and a temperature reduction section, the temperature rise rate of the temperature rise section is 120 ℃ per hour, the temperature of the heat preservation section is 720 ℃ and 750 ℃, the heat preservation time is 10-15h, the temperature is reduced to the material temperature which is less than 100 ℃, then the material is discharged, the inert gas in the calcination process is nitrogen, the adding amount of the nitrogen per hour is 5-10 times of the volume of a cavity of the kiln, the pressure in the kiln in the calcination process is maintained to be higher than the atmospheric pressure by 150 Pa, and the gas humidity in the heat preservation section is lower than 3%.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112486128A (en) * | 2020-12-07 | 2021-03-12 | 广东琅菱智能装备有限公司 | Powder raw material manufacturing control method and system based on MES system |
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| US20110017947A1 (en) * | 2003-11-14 | 2011-01-27 | Gerhard Nuspl | Lithium metal phosphates, method for producing the same and use thereof as electrode material |
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| CN108163828A (en) * | 2018-01-02 | 2018-06-15 | 乳源东阳光磁性材料有限公司 | A kind of preparation method of spherical lithium iron phosphate anode material |
| CN109811125A (en) * | 2019-01-21 | 2019-05-28 | 湖南邦普循环科技有限公司 | The method of ferrorphosphorus and lithium compound is recycled from waste lithium iron phosphate material |
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| US20110017947A1 (en) * | 2003-11-14 | 2011-01-27 | Gerhard Nuspl | Lithium metal phosphates, method for producing the same and use thereof as electrode material |
| CN101651204A (en) * | 2009-09-24 | 2010-02-17 | 安徽工业大学 | Method for preparing multi-element doping lithium iron phosphate by taking ferrous metallurgy sludge as main raw material |
| CN108163828A (en) * | 2018-01-02 | 2018-06-15 | 乳源东阳光磁性材料有限公司 | A kind of preparation method of spherical lithium iron phosphate anode material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112486128A (en) * | 2020-12-07 | 2021-03-12 | 广东琅菱智能装备有限公司 | Powder raw material manufacturing control method and system based on MES system |
| CN112486128B (en) * | 2020-12-07 | 2021-12-03 | 东莞市琅菱机械有限公司 | Powder raw material manufacturing control method and system based on MES system |
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