CN108529584A - The preparation method of high-density lithium iron phosphate positive material - Google Patents
The preparation method of high-density lithium iron phosphate positive material Download PDFInfo
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Abstract
The present invention provides a kind of preparation method of high-density lithium iron phosphate positive material, this method mainly includes the following steps that：It mixes reproducibility iron powder according to a certain percentage and ferric orthophosphate obtains compound source of iron；Then deionized water is added in ball-grinding machine, sequentially adds lithium source, compound source of iron, phosphorus source, carbon source and surfactant, slurry is formed after ball milling；Obtained slurry is squeezed into diaphragm filter press and is separated by solid-liquid separation, presoma of the solid content 85% or more is obtained；Presoma is placed in flash dryer and is dried, the powdered presoma that liquid content is less than 1% is obtained；Precursor powder is placed in the kiln with protective atmosphere and is sintered, iron phosphate powder is obtained through air-flow crushing again after cooling.The method and process of the present invention is simple, at low cost, and the chemical property of product is good.
Description
Technical field
The invention belongs to field of green energy resource material, specially technical field of lithium batteries more particularly to high density ferric phosphate
The preparation method of lithium anode material.
Background technology
Lithium ion battery has the advantages such as higher than energy, operating voltage is high, self-discharge rate is low, has extended cycle life, is pollution-free,
As the hot spot of power battery exploitation.Important component of the positive electrode as lithium ion battery is the safety for determining battery
Property, the key factor of capacity and price.Currently, industrialized power lithium-ion battery with positive electrode be mainly LiFePO4 and
The demand of nickelic ternary material, wherein LiFePO 4 material is larger.
LiFePO4 is produced using high temperature solid-state method, process route general in industry is with ferric phosphate, lithium carbonate at present
And carbon source be raw material, use deionized water for dispersant, by after wet ball grinding and high speed Ultrafine Grinding through centrifugal spray drying
After obtain spherical powdery presoma, due to after centrifugal spray drying gained presoma be in hollow ball-shape, after sintering gained phosphorus
Sour iron lithium material is in still hollow ball-shape, then after air-flow crushing, granularity larger hollow ball in part can be broken, but shattering process
In will appear LiFePO4 grain surface carbon coated peeling, part granularity it is small be still in hollow ball-shape.Due to hollow ball-shape
The presence of material causes material density small, occurs difficult dispersion, poor processability, pole piece two pairs of rollers in the process of battery core factory
Picking, the skin effect phenomenon occurred afterwards by rebound, and pole piece compaction density is low.Presoma crushing side is all made of in industry at present
Formula is to solve hollow ball and carbon stripping problem, but after presoma crushing, material is tiny bulk, can substantially reduce sintering production capacity, and
Since material is tiny, specific surface and gap are larger, and then influence the mass-and heat-transfer effect in sintering process.
Drying link in LiFePO4 preparation process need to be continued to explore, and especially prepares ferric phosphate in material by wet type mixing
During lithium, drying process is even more important.Drying is insufficient to cause material uneven, but will make to coagulate in sintering process
Shape is tied, the performance of lithium iron phosphate positive material is influenced.In addition, drying efficiency is low, production cost height will be led to indirectly.
Invention content
The purpose of the present invention is to provide a kind of methods for the high-density lithium iron phosphate positive material that processability is excellent, have
Effect solves the LiFePO4 poor performance that is prepared in the prior art, slurry solid content is low in preparation process, presoma drying not
Fully, manufacturing cost height, heavy-polluted technical problem.
Specifically, in view of the deficiencies of the prior art, the present invention provides following technical solutions：
A kind of preparation method of high-density lithium iron phosphate positive material, the preparation method include the following steps：
A, mechanical activation：Reproducibility iron powder and ferric orthophosphate are weighed first, in accordance with certain proportion, by load weighted reproducibility
Iron powder and ferric orthophosphate, which are uniformly mixed, obtains compound source of iron；Then a certain amount of deionized water is added in ball-grinding machine, according still further to
Lithium source, compound source of iron, phosphorus source, carbon source and surfactant is added in certain proportion, and slurry is formed after ball milling；
B, it is separated by solid-liquid separation：The obtained slurries of step A are squeezed into diaphragm filter press and are separated by solid-liquid separation, solid content is obtained and exists
85% or more filter cake shape presoma；
C, expansion drying：The obtained presomas of step B are placed in flash dryer and are dried, powdered forerunner is obtained
Body；
D, dynamic sinter：Precursor powder is placed in the kiln with protective atmosphere and is sintered, is passed through again after cooling
Air-flow crushing obtains iron phosphate powder.
Preferably, the grain size D50 of the reproducibility iron powder in the compound source of iron is 1~2 μm, the primary particle of ferric orthophosphate
For 50~200nm, the mixing molar ratio of reproducibility iron powder and ferric orthophosphate is 1：10~1：1, preferably 1：5~1：1.
Preferably, Ball-milling Time is 4~8 hours in the step A, the solid content of the slurry that ball milling obtains is 52~
68%, the granularity of slurry is controlled at 1.0-2.0 μm, the Li in the slurry：Fe：P molar ratios are (1~1.2)：(0.96~
1.2)：1.
Preferably, the liquid content of the presoma after step C expansion dryings is less than 1%.
Preferably, by weight, the carbon source weight being added in step A is the 8-12% of LiFePO4 theory production quantity, table
The addition of face activating agent is the 8-20% of lithium source addition.
Preferably, the lithium source in step A is selected from one or more of lithium carbonate, lithium stearate and lithium dihydrogen phosphate；Phosphorus
Ferric orthophosphate of the source in lithium dihydrogen phosphate and/or compound source of iron, the carbon source are selected from lithium stearate, magnesium stearate, tristearin
One or more of acid, glucose and phenolic resin；The surfactant is selected from cetyl trimethylammonium bromide, poly- mountain
One or more of pear ester, alkyl phenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether.
Preferably, the protective atmosphere described in step D is selected from one or more of nitrogen, argon gas and helium.
Preferably, the sintering described in step D is divided into two sections of high-temperature calcinations, and first segment is 400~500 DEG C of calcining at constant temperature 2~4
Hour, second segment is that 650~800 DEG C of heat preservations are calcined 6~10 hours.
Preferably, the granularity D50 controls of the iron phosphate powder crushed in step D exist in 1.5~4um, D90 controls
12um hereinafter, carbon content control in 1.4 ± 0.3wt%.
The present invention also provides a kind of lithium iron phosphate positive material, which is by above-mentioned preparation method
It is prepared.
Compared with prior art, it effect of the invention and has an advantage that：
(1) present invention uses grain size D50 in the reproducibility iron powder and primary particle of 1~2um for the orthophosphoric acid of 50~200nm
Iron is used with obtain compound source of iron in proportion, and iron powder has higher density, the LiFePO4 with its synthesis and other raw material phases
Than, there is higher tap density, then coordinate a nanometer level ferric orthophosphate, not only there is excellent chemical property, simultaneously because
Size particles grading can further increase LiFePO 4 material density.
(2) it is added with surfactant in raw material, the viscosity of raw mixture can be reduced so that the slurry after ball milling is solid
Content is high, is conducive to subsequent separation of solid and liquid and drying process, shortens the production cycle.In addition, surfactant can also be more
Promote being uniformly distributed for particle well, improves the chemical property of lithium iron phosphate positive material.
(3) the precursor powder liquid content that expansion drying obtains is low, while it is hollow to solve spray drying gained presoma
Ball problem, gained presoma are highdensity spherical or irregular spheric granules, the LiFePO4 being prepared by the presoma
The electrochemical performance of positive electrode.
(4) present invention has the characteristics that production process is continuous, product property is uniform, stable quality, and simple for process easy
Row is suitble to industrialized production.
Description of the drawings
Fig. 1 is the electron-microscope scanning figure (SEM figures) for the iron phosphate powder that embodiment 1 is prepared；
Fig. 2 is the SEM figures for the iron phosphate powder that embodiment 2 is prepared；
Fig. 3 is the SEM figures for the iron phosphate powder that comparative example 1 is prepared.
Specific implementation mode
The present invention provides a kind of preparation methods of high-density lithium iron phosphate positive material, and this approach includes the following steps：
A, mechanical activation：A certain amount of deionized water is added in ball-grinding machine, is then proportionally added into lithium source, compound iron
Source, phosphorus source, carbon source and surfactant, wherein Li：Fe：P molar ratios are (1~1.2)：(0.96~1.2)：1, carbon source weight
For the 8-12wt% of LiFePO4 theory production quantity, the weight of surfactant is the 8-20wt% of lithium source addition；It is described multiple
Source of iron is closed to be ferric orthophosphate that the reproducibility iron powder and the primary particle that are 1~2 μm by D50 are 50~200nm according to 1:10~1:1
(preferably 1：5~1：1) molar ratio is mixed to get, and high speed ball milling forms mixed slurry, the solid content of slurry after 4~8 hours
52~68%；
B, it is separated by solid-liquid separation：Obtained slurry is squeezed into diaphragm pump in diaphragm filter press and is separated by solid-liquid separation, solid content is obtained
In 85% or more filter cake shape presoma；
C, expansion drying：The filter cake shape presoma that step B is obtained is placed in flash dryer and is dried, obtains containing liquid
Powdered presoma of the amount less than 1%；
D, dynamic sinter：Precursor powder is placed in the kiln with protective atmosphere and is sintered, sintering is divided into two
Section, first segment are 400~500 DEG C and calcine 2~4 hours that second segment is 650~800 DEG C and calcines 6~10 hours.After calcining,
Material cooled to room temperature, then iron phosphate powder is obtained through air-flow crushing, the granularity D50 controls of the iron phosphate powder exist
1.5~4um, D90 are less than 12um, and carbon content control is in 1.4 ± 0.3wt%.
Using the density height for the lithium iron phosphate positive material that the method for the present invention is prepared, it is prepared into using the positive electrode
The capacitance of the battery arrived is high.
The present invention is illustrated with specific embodiment below.It should be noted that the materials such as reagent that the present invention uses and equipment
Material is commercially available.
Embodiment 1
By the ferric orthophosphate (FePO that primary particle is 50nm4) 300.00 kilograms with metal iron powder that grain size D50 is 2um
11.14 kilograms are mixed to get compound source of iron, are added 400 kilograms of deionized water in the ball mill, then by 73.52 kilograms of lithium carbonate,
Compound source of iron, 20.68 kilograms of lithium dihydrogen phosphate, 41.47 kilograms of stearic acid, surfactant cetyl trimethylammonium bromide
18.84 kilograms are placed in ball mill, carry out ball milling and slurry is made, Ball-milling Time is 4 hours, and slurry granularity controls 1.5 microns, obtains
The homogeneous mixed slurry for being 65% to solid content.Then ball milling slurry is squeezed into diaphragm pump in membrane pressure filter again and is pressed
Filter, time of filter pressing 1.5 hours, it is 15% presoma below to obtain moisture content；Presoma is conveyed into flash dryer again
Mixing, dry 150 DEG C of inlet air temperature is dried, 70 DEG C of leaving air temp obtains the forerunner that water content is 0.8% after drying
Body powder；Precursor powder is placed in the kiln with protective atmosphere nitrogen and is sintered, sintering schedule is two sections of high temperature
Calcining, first segment are 500 DEG C, constant temperature time 2 hours；Second segment is 740 DEG C, heat preservation sintering 10 hours；Cooled to room temperature,
Iron phosphate powder is obtained through air-flow crushing.LiFePO4 tap density 1.28g/cm3, powder compacted density is 2.75g/
cm3, carbon content 1.42%, specific surface area 12.65g/m2, granularity D50 is 2.52 μm, and D90 is less than 12 μm.Fig. 1 is this implementation
The SEM figures for the iron phosphate powder that example is prepared, material surface rounding is smooth as seen from the figure, and particle diameter distribution is uniform, is conducive to
Improve the properties for follow of material.
Test experiments：
Charge-discharge test is carried out to the iron phosphate powder material prepared in embodiment 1, half-cell test condition is as follows：Electricity
The test in pond carries out under room temperature (25 DEG C), test voltage 2.5-4.0v；Preparing for positive plate is as follows：With NMP (N-2- methyl
Pyrrolidones) it is solvent and dispersant, by the LiFePO 4 powder positive electrode being prepared of 80% (mass ratio), 10%
Slurry is made in super P (super conductive black), 10% bonding agent (Kynoar, PVDF) mixing, and the solid content of slurry is
45%, then slurry is coated on the aluminium foil of 20 μ m-thicks and is made film, then by film through 120 DEG C of vacuum drying backlash at 10mm
Positive plate is made in thin slice.Using metal lithium sheet as cathode, using 2400 films of Celgard (from market buy diaphragm) as every
Film, electrolyte are the LiPF of 1mol/L6/ (EC+DME) assembles half electricity simulated in the glove box filled with high-purity argon gas
Pond.The half-cell of preparation is subjected to charge-discharge test, the results showed that, half-cell capacity 0.2C is 161.3mAh/g, and 1C is
151.6mAh/g。
Embodiment 2
By the ferric orthophosphate (FePO that primary particle is 100nm4) 150.00 kilograms with metal iron powder that grain size D50 is 1um
11.14 kilograms are mixed to get compound source of iron, are added 250 kilograms of deionized water in the ball mill, then by 44.33 kilograms of lithium carbonate,
Compound source of iron, 15.78 kilograms of stearic acid, 6.65 kilograms of cetyl trimethylammonium bromide are placed in ball mill, carry out ball milling system
At slurry, Ball-milling Time is 6 hours, and slurry granularity controls 1.0 microns, obtains the homogeneous mixed slurry that solid content is 60%.So
Ball milling slurry is squeezed into again with diaphragm pump afterwards and carries out press filtration in membrane pressure filter, time of filter pressing 2.0 hours, obtaining liquid holdup is
12% presoma；Presoma is conveyed into flash dryer again, mixing is dried, dry 150 DEG C of inlet air temperature, outlet air
Temperature 70 C obtains the precursor powder that liquid content is 0.5% after drying；Precursor powder is placed in protectiveness gas
It is sintered in the kiln of atmosphere nitrogen, sintering is divided into two sections of high-temperature calcinations, and first segment is 400 DEG C, constant temperature time 4 hours；Second
Section is 800 DEG C, heat preservation sintering 6 hours；Cooled to room temperature obtains iron phosphate powder through air-flow crushing.The LiFePO4
Tap density 1.32g/cm3, powder compacted density is 2.78g/cm3, carbon content is 1.30%, specific surface area 12.31g/m2,
Granularity D50 is 2.64 μm, and D90 is less than 12 μm.Fig. 2 is the SEM figures for the iron phosphate powder that the present embodiment is prepared, can by figure
See that material surface rounding is smooth, particle diameter distribution is uniform, is conducive to the properties for follow for improving material.
Carry out charge-discharge test to the iron phosphate powder material prepared in embodiment 2 simultaneously, half-cell test condition
With embodiment 1.Test result shows that half-cell capacity 0.2C is 157.8mAh/g, 1C 148.1mAh/g.
Embodiment 3
By 150.00 kilograms of ferric orthophosphate (FePO4) that primary particle is 200nm and metal iron powder that grain size D50 is 1um
56.00 kilograms are mixed to get compound source of iron, are added 200 kilograms of deionized water in the ball mill, then by 38.64 kilograms of lithium carbonate,
Compound source of iron, 15.78 kilograms of lithium stearate, 4.35 kilograms of polysorbate are placed in ball mill, carry out ball milling and slurry, ball milling is made
Time is 8 hours, and slurry granularity controls 1.0 microns, obtains the homogeneous mixed slurry that solid content is 68%.Then ball milling is starched again
Material is squeezed into diaphragm pump carries out press filtration in membrane pressure filter, time of filter pressing 2.0 hours, obtains the forerunner that liquid holdup is 15%
Body；Presoma is conveyed into flash dryer again, mixing is dried, dry 150 DEG C of inlet air temperature, 70 DEG C of leaving air temp is done
The precursor powder that liquid content is 0.5% is obtained after dry；Precursor powder is placed in the kiln with protective atmosphere nitrogen
It is sintered in stove, sintering is divided into two sections of high-temperature calcinations, and first segment is 450 DEG C, constant temperature time 4 hours；Second segment is 650 DEG C,
Heat preservation sintering 10 hours；Cooled to room temperature obtains iron phosphate powder through air-flow crushing.The LiFePO4 tap density
1.18g/cm3, powder compacted density is 2.68g/cm3, carbon content is 1.37%, specific surface area 12.70g/m2, granularity D50 is
2.26 μm, D90 is less than 12 μm.
Carry out charge-discharge test to the iron phosphate powder material prepared in embodiment 3 simultaneously, half-cell test condition
With embodiment 1.Test result shows that half-cell capacity 0.2C is 154.2mAh/g, 1C 146.5mAh/g.
Embodiment 4
By 200.00 kilograms of ferric orthophosphate (FePO4) that primary particle is 200nm and metal iron powder that grain size D50 is 1um
31.59 kilograms are mixed to get compound source of iron, are added 350 kilograms of deionized water in the ball mill, then by 49.15 kilograms of lithium carbonate,
66.38 kilograms of compound source of iron, lithium dihydrogen phosphate, 12.12 kilograms of phenolic resin, 11.55 kilograms of polysorbate are placed in ball mill,
Carry out ball milling and be made slurry, Ball-milling Time is 5 hours, and slurry granularity controls 1.5 microns, obtain solid content be 65% it is homogeneous mixed
Close slurry.Then ball milling slurry is squeezed into again with diaphragm pump and carries out press filtration in membrane pressure filter, time of filter pressing 1.5 hours obtains
The presoma for being 10% to liquid holdup；Presoma is conveyed into flash dryer again, mixing is dried, dry inlet air temperature
150 DEG C, 70 DEG C of leaving air temp；Precursor powder is placed in the kiln with protective atmosphere nitrogen and is sintered, sintering point
For two sections of high-temperature calcinations, first segment is 500 DEG C, constant temperature time 3 hours；Second segment is 750 DEG C, heat preservation sintering 8 hours；Naturally cold
But to room temperature, iron phosphate powder is obtained through air-flow crushing.LiFePO4 tap density 1.29g/cm3, powder compacted density
For 2.77g/cm3, carbon content is 1.39%, specific surface area 12.95g/m2, granularity D50 is 1.60 μm, and D90 is less than 12 μm.
Carry out charge-discharge test to the iron phosphate powder material prepared in embodiment 4 simultaneously, half-cell test condition
With embodiment 1.Test result shows that half-cell capacity 0.2C is 157.8mAh/g, 1C 148.5mAh/g.
Embodiment 5
By the ferric orthophosphate (FePO that primary particle is 100nm4) 200.00 kilograms with metal iron powder that grain size D50 is 2um
31.59 kilograms are mixed to get compound source of iron, are added 300 kilograms of deionized water in the ball mill, then by 44.35 kilograms of lithium carbonate,
Compound source of iron, 18.94 kilograms of glucose, 8.87 kilograms of alkyl phenol polyoxyethylene ether, are placed in ball mill, carry out ball milling and material is made
Slurry, Ball-milling Time are 6 hours, and slurry granularity controls 1.5 microns, obtain the homogeneous mixed slurry that solid content is 62%.Then again
Ball milling slurry is squeezed into diaphragm pump and carries out press filtration in membrane pressure filter, time of filter pressing 2.0 hours, it is 10% to obtain liquid holdup
Presoma；Presoma is conveyed into flash dryer again, mixing is dried, dry 150 DEG C of inlet air temperature, leaving air temp
70 DEG C, the precursor powder that liquid content is 0.6% is obtained after drying；Precursor powder is placed in protective atmosphere nitrogen
It is sintered in the kiln of gas, sintering is divided into two sections of high-temperature calcinations, and first segment is 400 DEG C, constant temperature time 4 hours；Second segment is
760 DEG C, heat preservation sintering 5 hours；Cooled to room temperature obtains iron phosphate powder through air-flow crushing.The LiFePO4 jolt ramming
Density 1.31g/cm3, powder compacted density is 2.79g/cm3, carbon content is 1.43%, specific surface area 11.97g/m2, granularity
D50 is 3.50 μm, and D90 is less than 12 μm.
Carry out charge-discharge test to the iron phosphate powder material prepared in embodiment 5 simultaneously, half-cell test condition
With embodiment 1.Test result shows that half-cell capacity 0.2C is 156.8mAh/g, 1C 144.2mAh/g.
Comparative example 1
By 66.62 kilograms of lithium carbonate, 300 kilograms of ferric orthophosphate, 54.02 kilograms of lithium stearate, it is placed in ball mill, then
400 kilograms of progress ball millings of deionized water are added, slurry is made, Ball-milling Time is 2 hours, obtains homogeneous mixed slurry.Then again will
Ball milling slurry is squeezed into diaphragm pump carries out press filtration in membrane pressure filter, time of filter pressing 1.0 hours, obtain moisture content be 20% with
Under presoma；Presoma is conveyed into flash dryer again, mixing is dried, dry 150 DEG C of inlet air temperature goes out wind-warm syndrome
70 DEG C of degree；Precursor powder is placed in the kiln with protective atmosphere nitrogen and is sintered, sintering is divided into two sections of high temperature and forges
It burns, first segment is 500 DEG C, constant temperature time 2 hours；Second segment is 740 DEG C, heat preservation sintering 10 hours；Cooled to room temperature, warp
Air-flow crushing obtains iron phosphate powder.LiFePO4 tap density 0.83g/cm3, powder compacted density is 2.35g/cm3,
Carbon content is 1.72%, specific surface area 14.65g/m2, granularity D50 is 3.5 μm.It is surveyed using the identical half-cell of same embodiment
Strip part, the results showed that, half-cell capacity 0.2C is 164.5mAh/g, 1C 154.8mAh/g.Fig. 3 is that this comparative example is prepared into
The SEM of the iron phosphate powder arrived schemes, and material surface corner angle are more, and particle diameter distribution differs, hence it is evident that reunite, influence material
Properties for follow.
Comparative example 2
By 74.43 kilograms of lithium carbonate, 300 kilograms of ferric orthophosphate, 30 kilograms of stearic acid, 10 kilograms of phenolic resin, surface is lived
Property 9 kilograms of agent, be placed in ball mill, 300 kilograms of deionized water is then added carries out ball millings slurry is made, ball milling obtains for 2 hours
Homogeneous mixed slurry.Then ball milling slurry is squeezed into again with diaphragm pump and carries out press filtration in membrane pressure filter, time of filter pressing 1.5 is small
When, obtain the presoma that moisture content is 18%；Presoma is conveyed into spray dryer again, mixing is dried；It will be dry
To precursor powder be placed in the kiln with protective atmosphere nitrogen and be sintered, sintering schedule is two sections of high-temperature calcinations,
First segment is 400 DEG C, constant temperature time 4 hours；Second segment is 800 DEG C, heat preservation sintering 6 hours；Cooled to room temperature, through air-flow
Crushing obtains iron phosphate powder.LiFePO4 tap density 0.94g/cm3, powder compacted density is 2.47g/cm3, carbon contains
Amount is 1.15%, specific surface area 11.8g/m2, granularity D50 is 3.6 μm.Using the identical half-cell test-strips of same embodiment
Part, the results showed that, half-cell capacity 0.2C is 160.5mAh/g, 1C 149.2mAh/g.
The shape characteristic data for the iron phosphate powder that comparing embodiment and comparative example are prepared, and corresponding half electricity
The chemical property parameter in pond is it is found that the carbon for the lithium iron phosphate positive material being prepared using preparation method of the present invention is contained
It measures moderate, conducts electricity very well；The lithium iron phosphate positive material is also equipped with high tap density and pressure while ensureing capacitance
Real density is conducive to subsequent processing.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
Any one skilled in the art in the technical scope disclosed by the present invention, the change or replacement that can be readily occurred in,
It should be covered by the protection scope of the present invention.
Claims (10)
1. a kind of preparation method of high-density lithium iron phosphate positive material, which is characterized in that the preparation method includes following step
Suddenly：
A, mechanical activation：Reproducibility iron powder and ferric orthophosphate are weighed first, in accordance with certain proportion, by load weighted reproducibility iron powder
It is uniformly mixed with ferric orthophosphate and obtains compound source of iron；Then a certain amount of deionized water is added in ball-grinding machine, according still further to certain
Lithium source, compound source of iron, phosphorus source, carbon source and surfactant is added in ratio, and slurry is formed after ball milling；
B, it is separated by solid-liquid separation：The obtained slurries of step A are squeezed into diaphragm filter press and are separated by solid-liquid separation, obtain solid content 85% with
On filter cake shape presoma；
C, expansion drying：The obtained presomas of step B are placed in flash dryer and are dried, powdered presoma is obtained；
D, dynamic sinter：Precursor powder is placed in the kiln with protective atmosphere and is sintered, again through air-flow after cooling
Crushing obtains iron phosphate powder.
2. the preparation method of lithium iron phosphate positive material according to claim 1, which is characterized in that in the compound source of iron
The grain size D50 of reproducibility iron powder be 1~2 μm, the primary particle of ferric orthophosphate is 50~200nm, reproducibility iron powder and positive phosphorus
The mixing molar ratio of sour iron is 1：10~1：1, preferably 1：5~1：1.
3. the preparation method of lithium iron phosphate positive material according to claim 1 or 2, which is characterized in that in the step A
Ball-milling Time is 4~8 hours, and the solid content for the slurry that ball milling obtains is 52~68%, and the granularity of slurry is controlled in 1.0-2.0 μ
M, the Li in the slurry：Fe：P molar ratios are (1~1.2)：(0.96~1.2)：1.
4. according to the preparation method of claim 1-3 any one of them lithium iron phosphate positive materials, which is characterized in that step C
The liquid content of presoma after expansion drying is less than 1%.
5. according to the preparation method of claim 1-4 any one of them lithium iron phosphate positive materials, which is characterized in that with weight
It counts, the carbon source weight being added in step A is the 8-12% of LiFePO4 theory production quantity, and the addition of surfactant is lithium source
The 8-20% of addition.
6. the preparation method of lithium iron phosphate positive material according to claim 5, which is characterized in that the lithium source in step A
Selected from one or more of lithium carbonate, lithium stearate and lithium dihydrogen phosphate；Phosphorus source is selected from lithium dihydrogen phosphate and/or compound source of iron
In ferric orthophosphate, one kind in lithium stearate, magnesium stearate, stearic acid, glucose and phenolic resin of the carbon source or
It is several；The surfactant is selected from cetyl trimethylammonium bromide, polysorbate, alkyl phenol polyoxyethylene ether and fatty alcohol
One or more of polyoxyethylene ether.
7. the preparation method of lithium iron phosphate positive material according to claim 6, which is characterized in that the guarantor described in step D
Shield property atmosphere is selected from one or more of nitrogen, argon gas and helium.
8. the preparation method of lithium iron phosphate positive material according to claim 7, which is characterized in that the burning described in step D
Knot is divided into two sections of high-temperature calcinations, and first segment is 400~500 DEG C of calcining at constant temperature 2~4 hours, and second segment is 650~800 DEG C of heat preservations
Calcining 6~10 hours.
9. the preparation method of lithium iron phosphate positive material according to claim 8, which is characterized in that crushed in step D
The granularity D50 control of the iron phosphate powder arrived in 1.5~4um, D90 controls in 12um hereinafter, carbon content control 1.4 ±
0.3wt%.
10. a kind of lithium iron phosphate positive material, which is characterized in that use claim 1-9 any one of them preparation method systems
.
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| CN114497505A (en) * | 2022-01-28 | 2022-05-13 | 佛山市德方纳米科技有限公司 | Method and device for continuously preparing anode material by spray drying |
| CN114497505B (en) * | 2022-01-28 | 2024-05-10 | 佛山市德方纳米科技有限公司 | Method and device for continuously preparing positive electrode material by spray drying |
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