A kind of LiFePO
4The preparation method of spherical powder
Technical field
The present invention relates to a kind of high electrochemical performance secondary lithium battery or power source battery anode material spherical LiFePO
4The preparation method of powder belongs to material science.
Background technology
LiFePO
4That material has is cheap, nontoxic, nonhygroscopic, Environmental compatibility is fine, rich in mineral resources, characteristics such as capacity is higher (theoretical capacity is 170mAh/g, and energy density is 550Wh/Kg), stability is fine.It is a kind of positive electrode material equivalent material of tool potentiality.Be with a wide range of applications and the very big market requirement.Existing several synthetic methods are arranged at present:
1) solid phase method, JP2000294238, are calcined under inert atmosphere as raw material with Ferrox, Secondary ammonium phosphate and Quilonum Retard.EP1193784 is with Fe
3(PO
4)
2And Li
3PO
4As raw material and add hydrocarbon polymer and carry out solid phase synthesis; This method synthetic material granule is thick, and form is irregular, and material electrochemical performance is low.
2) sol-gel method, publication number: CN1410349 is with Fe (Ac)
2, FeSO
4, 7H
2O, Ba (Ac)
2And organic acid is a raw material; Technology is comparatively complicated, the improper easy introducing Ba of process control
2+, Fe
3+Deng impurity.
3) reversed phase lithium inserting process, publication number: CN1469499, with normal heptane-ST80 system, the microreactor synthesis of nano FePO that utilizes micro emulsion to form
4, utilize LiI to insert lithium then.This method technical process complexity, the flow process time is longer.
4) spray-drying process, S.L.Bewlay, K.Konstantinov, G.X.Wang, Materials Letters, 58 (11), 2004,1788.This method is mainly utilized and is contained Li
+, Fe
2+And PO
4 3-Isoionic nitrate solution is as spray-dired slip, and spray-dried back is as the presoma of synthetic materials.This technology can obtain the material of controllable grain size, and technology is simple, but causes the oxidation of ferrous ion in the building-up process easily, is unfavorable for the improvement of material property.And, require very high to processing unit owing to contain strong acid in the solution.
5) coprecipitation method, G.Arnold, J.Garche, R.Hemmer, et al.Journal of Power Sources 2003,119-121:247.This method is introduced impurity easily, is unfavorable for the improvement of material electrochemical performance.
6) emulsion desiccating method S.T.Myung, S.Komaba, R.Takagai, et al., Chemistry Letters, 32 (7), 2003,566.This method complicated process of preparation, the flow process time is longer.
7) hydrothermal method, Yang S.F, Zavalij P.Y et al.electrochemistry communications.3,2001,505.This side is unfavorable for the improvement of material electrochemical performance.
Summary of the invention
The object of the invention provides a kind of LiFePO
4The preparation method of spherical powder, this method can solve the density of material of conventional preparation method preparation little and specific surface area is little and the problem of poorly conductive can to have crystallinity in fairly large preparation down good, powder is a spherical morphology, narrowly distributing, and the purity height (removes LiFePO
4Do not have dephasign outward with the rigid carbon that coats), the material good conductivity, specific surface area is big, and has the LiFePO of bigger mass density
4Spherical powder, this powder also helps LiFePO
4The manufacture craft of material cell.
A kind of LiFePO
4The preparation method of spherical powder, this method may further comprise the steps:
The 1st step: pre-synthesizing blender or blank LiFePO
4Nano-powder A
, Quilonum Retard ferrous with 2 oxalic acid hydrates, primary ammonium phosphate are that main precursor takes by weighing some according to 1: 0.5: 1 mole of proportioning; If the adulterated LiFePO of preparation
4Material is that 0~0.8at% takes by weighing dopant according to atomic percentage conc then; With the above material that takes by weighing is the ball-milling medium ball milling with the dehydrated alcohol, through pre-treatment 8~16 hours in 300~400 ℃ of following inert atmospheres or reducing atmosphere after the cryodrying, obtains nano-powder A;
The 2nd step: according to nano-powder A: tackiness agent: dispersion agent: water=(60~65kg): (6~6.5kg): (720~780mL): (54~58.5L) mixed, ball milling obtains having good fluidity and the stable slurry B that is suitable for mist projection granulating;
The 3rd step: use slurry B, mist projection granulating as requested in the mist projection granulating tower obtains the spherical powder of different-grain diameter;
The 4th step: with the porcelain boat of packing into after the 3rd spherical powder drying that obtains of step, 400 ℃ of pre-treatment are 2~8 hours under reducing atmosphere or inert atmosphere, and powder is cracking lentamente in this atmosphere;
The 5th step: the 4th powder that obtains of step is burnt till in reduction or the inert atmosphere down at 550~850 ℃, be incubated 8~36 hours, promptly obtain the spherical LiFePO with nano level primary particle size of carbon black coating
4Powder.
With above step, if the adulterated LiFePO of preparation
4Material is that 0~0.8at% takes by weighing dopant according to atomic percentage conc then, and its doping way can be singly to mix, and also can be two mixing or the mixed doping of more hotchpotchs.Its dopant can be as 2 oxalic acid hydrate magnesium, many materials such as aluminum isopropylate.
Principle of the present invention is: synthetic in advance LiFePO
4Powder A can improve powder ferrous ion anti-oxidant in the technical process process; Pre-synthetic nano-powder is difficult in calcination process that after organism coats particle takes place grows up, thereby has kept material to have nano level primary particle size; Utilize atomizing granulating technology to make nanoparticle agglomerates become needed bead form, guaranteed that material has bigger specific surface area and bigger powder density; Utilize polymer substance (dispersion agent and the tackiness agent) carbon black that cracking forms in inertia or reducing atmosphere effectively to solve LiFePO
4The problem that the material electronics specific conductivity is low.
Beneficial effect of the present invention: preparation process time of the present invention is short, firing temperature is low, energy consumption is low, the polycrystalline LiFePO of preparation
4The diameter of particle narrowly distributing, and form spherical in shape, directly under inertia or reducing atmosphere, burn till, the LiFePO that rigid carbon coats can be obtained
4Powder.Therefore also need not to carry out the coating in later stage and handle the electronic conductivity that can improve material.Synthetic materials has nano level primary particle size, has guaranteed that material has bigger specific surface area; Synthetic materials has bigger density, is fit to the making of lithium ion battery, and adjustable between 550 ℃~850 ℃ of the synthesis temperatures, the material diameter of particle is adjustable, and the material preparation process is simple, and the flow process time is of short duration, and the material productive rate is higher.
Description of drawings
Figure (1) is the XRD figure spectrum of pre-treatment powder A1, wherein (200), and (101), (210), (011), (111), (211), (301), (311), (121), (410), (401), diffraction peaks such as (022) is LiFePO
4The characteristic peak of material.
Figure (2) is to use the XRD diffractogram of the powder of preparation among present method embodiment 1.
Figure (3) is to use the SEM figure of the powder of preparation among present method embodiment 1.
Figure (4) is to use the XRD diffractogram of the powder of preparation among present method embodiment 2.
Figure (5) is to use the SEM figure of the powder of preparation among present method embodiment 2.
Figure (6) is to use the XRD diffractogram of the powder of preparation among present method embodiment 3.
Figure (7) is to use the SEM figure of the powder of preparation among present method embodiment 3.
Figure (8) is to use the XRD diffractogram of the powder of preparation among present method embodiment 4.
Figure (9) is to use the SEM figure of the powder of preparation among present method embodiment 4.
Figure (10) is to use the XRD diffractogram of the powder of preparation among present method embodiment 5.
Embodiment
Below by embodiment, further illustrate the present invention.
Embodiment 1: pre-burning LiFePO
4Presoma: according to 1: 0.5: 1 mole of proportioning take by weighing that 2 oxalic acid hydrates are ferrous, Quilonum Retard, primary ammonium phosphate, be ball-milling medium with the dehydrated alcohol with mixture ball milling 4 hours; Through after the cryodrying in 300 ℃ of following inert atmospheres or reducing atmosphere pre-treatment can obtain solid matter pre-treatment powder A1 in 8 hours, figure (1) is the XRD figure of pre-treatment powder A1 spectrum.Take by weighing 6 kilograms of A1,0.6 kilogram of PVA, 5.4 liters of deionized waters, 72 milliliters of dispersion agents place container, and ball milling is 48 hours on the mill that rolls, and can obtain slip mobile and that have good stability.Slip is sent in the mist projection granulating tower, and input speed is controlled at 12 ± 2ml/min, and the nozzle air current amount is 0.08~0.1Mpa by compressed-air actuated pressure-controlling, and temperature of inlet air is about 300 ℃, and temperature out is 100~130 ℃.Collect dried powder, and powder has been put into porcelain boat, inserted in the atmosphere furnace under nitrogen atmosphere 400 ℃ of pre-treatment 2 hours, obtained the black LiFePO of good fluidity then 550 ℃ of insulations in 8 hours
4Spherical powder.As Fig. 2, shown in Figure 3, figure (2) is to use the XRD diffractogram of the powder for preparing in this example of present method, and figure (3) is to use the SEM figure of the powder for preparing in this example of present method.
Embodiment 2: pre-burning LiFePO
4Presoma: according to the mole proportioning take by weighing that 2 oxalic acid hydrates are ferrous, Quilonum Retard, primary ammonium phosphate, and add the 2 oxalic acid hydrate magnesium of 0.8at%; With the dehydrated alcohol ball-milling medium with mixture ball milling 8 hours; Through after the cryodrying in 400 ℃ of following inert atmospheres or reducing atmosphere pre-treatment can obtain solid matter A2 in 16 hours; Take by weighing solid matter A26.5 kilogram, 0.65 kilogram of PVA, 5.85 liters of deionized waters, 78 milliliters of dispersion agents place container, and ball milling is 4 days on the mill that rolls, and can obtain slip mobile and that have good stability; Slip is sent in the mist projection granulating tower, and input speed is controlled at 12 ± 2ml/min, and the nozzle air current amount is 0.08~0.1Mpa by compressed-air actuated pressure-controlling, and temperature of inlet air is about 300 ℃, and temperature out is 100~130 ℃; Collect dried powder, and powder has been put into porcelain boat, inserted in the atmosphere furnace under nitrogen atmosphere 400 ℃ of pre-treatment 8 hours, obtained the black LiFePO of good fluidity then 850 ℃ of insulations in 36 hours
4Spherical powder.As Fig. 4, shown in Figure 5, figure (4) is to use the XRD diffractogram of the powder for preparing in this example of present method, and figure (5) is to use the SEM figure of the powder for preparing in this example of present method.
Embodiment 3: pre-burning LiFePO
4Presoma: according to the mole proportioning take by weighing that 2 oxalic acid hydrates are ferrous, Quilonum Retard, primary ammonium phosphate, and add the aluminum isopropylate of 0.4at%.With the dehydrated alcohol ball-milling medium with mixture ball milling 6 hours.Through after the cryodrying in 350 ℃ of following inert atmospheres or reducing atmosphere pre-treatment can obtain solid matter A3 in 10 hours.Take by weighing solid matter A36.2 kilogram, 0.62 kilogram of PVA, 5.25 liters of deionized waters, 73 milliliters of dispersion agents place container, and ball milling is 3 days on the mill that rolls, and can obtain slip mobile and that have good stability.Slip is sent in the mist projection granulating tower, and input speed is controlled at 12 ± 2ml/min, and the nozzle air current amount is 0.08~0.1Mpa by compressed-air actuated pressure-controlling, and temperature of inlet air is about 300 ℃, and temperature out is 100~130 ℃.Collect dried powder, and powder has been put into porcelain boat, inserted in the atmosphere furnace under nitrogen atmosphere 400 ℃ of pre-treatment 4 hours, obtained the black LiFePO of good fluidity then 700 ℃ of insulations in 16 hours
4Spherical powder.As Fig. 6, shown in Figure 7, figure (6) is to use the XRD diffractogram of the powder for preparing in this example of present method, and figure (7) is to use the SEM figure of the powder for preparing in this example of present method.
Embodiment 4: first pre-burning LiFePO
4Presoma: according to the mole proportioning take by weighing that 2 oxalic acid hydrates are ferrous, Quilonum Retard, primary ammonium phosphate, and add aluminum isopropylate and the 0.4at%2 oxalic acid hydrate magnesium of 0.4at%; With the dehydrated alcohol ball-milling medium with mixture ball milling 4 hours; Through after the cryodrying in 400 ℃ of following inert atmospheres or reducing atmosphere pre-treatment can obtain solid matter A4 in 8 hours; Take by weighing 6 kilograms of A4,0.6 kilogram of PVA, 5.4 liters of deionized waters, 72 milliliters of dispersion agents place container, and ball milling is 48 hours on the mill that rolls, and can obtain slip mobile and that have good stability.Slip is sent in the mist projection granulating tower, and input speed is controlled at 12 ± 2ml/min, and the nozzle air current amount is 0.08~0.1Mpa by compressed-air actuated pressure-controlling, and temperature of inlet air is about 300 ℃, and temperature out is 100~130 ℃.Collect dried powder, and powder has been put into porcelain boat, inserted in the atmosphere furnace under nitrogen atmosphere 400 ℃ of pre-treatment 4 hours, obtained the black LiFePO of good fluidity then 800 ℃ of insulations in 8 hours
4Spherical powder.As Fig. 8, shown in Figure 9, figure (8) is to use the XRD diffractogram of the powder for preparing in this example of present method, and figure (9) is to use the SEM figure of the powder for preparing in this example of present method.
Embodiment 5: pre-burning LiFePO
4Presoma: according to the mole proportioning take by weighing that 2 oxalic acid hydrates are ferrous, Quilonum Retard, primary ammonium phosphate, and add the 2 oxalic acid hydrate magnesium of 0.3at%; With the dehydrated alcohol ball-milling medium with mixture ball milling 8 hours; Through after the cryodrying in 400 ℃ of following inert atmospheres or reducing atmosphere pre-treatment can obtain solid matter A2 in 10 hours; Take by weighing 6.5 kilograms of solid matter A2,0.6 kilogram of PVA, 5.6 liters of deionized waters, 82 milliliters of dispersion agents place container, and ball milling is 50 hours on the mill that rolls, and can obtain slip mobile and that have good stability; Slip is sent in the mist projection granulating tower, and input speed is controlled at 12 ± 2ml/min, and the nozzle air current amount is 0.08~0.1Mpa by compressed-air actuated pressure-controlling, and temperature of inlet air is about 300 ℃, and temperature out is 100~130 ℃; Collect dried powder, and powder has been put into porcelain boat, inserted in the atmosphere furnace under nitrogen atmosphere 400 ℃ of pre-treatment 2 hours, obtained the black LiFePO of good fluidity then 650 ℃ of insulations in 24 hours
4Spherical powder.As shown in figure 10, figure (10) is to use the XRD diffractogram of the powder for preparing in this example of present method.
Although the present invention is described in each preferred embodiment, but the heat of this area white silk technician understands the present invention easily and is not limited to foregoing description, it can be changed in multiple other modes or be improved, and does not break away from the spirit and scope of illustrating in the claim of the present invention.