CN102593457B - Preparation method of lithium iron phosphate-carbon material composite - Google Patents
Preparation method of lithium iron phosphate-carbon material composite Download PDFInfo
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Abstract
The invention belongs to the technical field of energy material preparation and relates to a preparation method of a lithium iron phosphate-carbon material composite. The preparation method provided by the invention comprises the step of adding a phosphate-source compound, an iron-source compound and a lithium-source compound into a dispersed liquid containing a carbon material. With the adoption of the preparation method provided by the invention, the lithium iron phosphate-carbon material composite with a mean particle size of 0.02-10mum, a tap density of 1.8-2.2g/cm<3> and a discharge specific capacity of 140-164mAh/g under 0.2C (2.4A of current) at room temperature can be prepared. The composite can be used as a cathode material of a lithium battery, which requires a high specific capacity and high cycling stability.
Description
Technical field
The present invention relates to energy and material technology, particularly, the present invention relates to the preparation method's of lithium iron phosphate-carbon material composite, particularly lithium ion battery anode material lithium iron phosphate preparation method and the lithium iron phosphate-carbon material composite of being prepared by the method.
Background technology
LiFePO4 (the LiFePO with regular olivine-type
4), its theoretical specific capacity relatively high (170mAh/g), can produce 3.4V (vs.Li/Li
+) voltage, meanwhile, it has again the features such as nontoxic, raw material sources are extensive, cost is low, Heat stability is good, thereby LiFePO4 is considered to the desirable positive electrode of lithium-ion-power cell development.
In research process, it is found that LiFePO
4when little electric current discharges and recharges, can reach higher specific capacity, during large electric current, capacity is but decayed comparatively fast; And, capacity 20% left and right of can decaying after circulation first.Pdaihi model is thought, general capacity attenuation is because electrode material granules is in charge and discharge process, and variation has occurred for volume and structure, has caused particle and particle, electrically contacting between particle and conductive agent is damaged, thereby caused that specific capacity irreversibly reduces.LiFePO
4capacity attenuation be because ion and electronic conductivity lower, Li
+less the causing of diffusion coefficient, be reversible, if reduce current density, capacity can recover again.The radius model of Andesrosn AS and mosaic model all propose in first charge-discharge, have a small amount of sluggish LiFePO in active particle
4and FePO
4there is not conversion mutually, thereby participate in electrochemical reaction in the circulation of failing afterwards, caused the capacity attenuation after circulation first.This impact is at large particle diameter LiFePO
4larger in material.Therefore, control grain growth, improve LiFePO
4electrical conductance become the emphasis of preparation research.
Although LiFePO
4aboundresources, cheap, environmentally friendly, is the anode material for lithium-ion batteries that has application potential, but LiFePO
4electronic conductivity is low, and the electrochemical process under high-multiplying power discharge condition is subject to again Li
+diffusion control, causes heavy-current discharge performance poor.For overcoming above-mentioned defect, to LiFePO
4the research work of preparation mainly comprises two key points: a) control grain growth, prepare the LiFePO of uniform particle diameter, tiny, good sphericity
4material, thus the accumulate capacity loss causing due to granule interior resistance to mass tranfer, the ionic conduction performance of strengthening material reduced; B) by means such as compound or doping, improve electronics, the ionic conductivity of material simultaneously, for example, prepare LiFePO
4the methods such as element doping such as-C composite material, employing Mg, Mn.
But because Liquid preparation methods technique is comparatively complicated, especially in product drying, calcination process, granularity is controlled more difficult; Nanometer agglomerate fluid bed has remarkable advantage for nano particle preparation process, and distribution of particles is easily controlled, is convenient to gas phase and is coated and reprocessing, but up to now, nanometer agglomerate fluidized-bed process is applied to LiFePO4 preparation and there is not yet bibliographical information.
Summary of the invention
For addressing the above problem, the present invention is in conjunction with the advantage of Liquid preparation methods LiFePO4 technique, in the LiFePO4 crystallization nucleation stage, add material with carbon element, make LiFePO4 degree of crystallinity and granular size obtain good control, strengthened the electric conductivity of lithium iron phosphate particles simultaneously, adopt fluidized-bed process to carry out particle calcining, surface treatment, can effectively reduce the sintering of controlling product, coalescence, thereby having obtained good granular size controls, gained lithium iron phosphate-carbon material composite has higher charge/discharge capacity, good structural stability and good cycle performance.
Therefore, the present invention mainly comprises following aspect.
1. a preparation method for lithium iron phosphate-carbon material composite, the method comprises the following steps:
1) in containing the dispersion liquid of material with carbon element, add P source compound, Fe source compound and Li source compound, obtain slurry product;
2) by by step 1) the slurry product that obtains carries out solvent heat treatment in closed container; With
3) by by step 2) product that obtains carries out powder calcination processing.
2. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 1, wherein, described material with carbon element is to be selected from one or more in carbon black, active carbon, carbon nano-tube, Graphene and composition thereof.
3. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 2, wherein, the solvent in the dispersion liquid of described carbonaceous material is the mixture of water, alcohol or water and alcohol, in described dispersion liquid, the concentration of material with carbon element is 0.001 grams per milliliter to 1 grams per milliliter.
4. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 3, wherein, described alcohol is selected from one or more in methyl alcohol, ethanol, ethylene glycol and composition thereof.
5. a preparation method for lithium iron phosphate-carbon material composite, the method comprises the following steps:
1) P source compound, Fe source compound and Li source compound are mixed in water, obtain slurry product;
2) by by step 1) the slurry product that obtains carries out solvent heat treatment in closed container; With
3) by by step 2) product that obtains carries out powder calcination processing, and this calcination processing is carried out under fluidized state, and introduces the air-flow that comprises ethene and/or acetylene.
6. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 1 to 5 any one, the method also comprises with next, two or 3 features:
In step 3) powder calcination processing procedure in, introducing the air-flow comprise ethene and/or acetylene, to carry out gas-phase carbon coated;
In step 3) also comprise before, by by step 2) product that the obtains step of mixing with one or more carbon-source cpd among being selected from sucrose, glucose, citric acid, starch, pitch, wax oil;
In step 1) in also comprise and add the step that is selected from one or more additives in ammoniacal liquor, citric acid, ascorbic acid, glucose, urea, neopelex, softex kw and composition thereof.
7. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 1 to 5 any one, wherein, described P source compound is phosphorous organic substance or inorganic matter, preferably phosphoric acid or phosphate; For example, described P source compound is to be selected from one or more in phosphoric acid, ferric phosphate, ferrous phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate and composition thereof; Described Fe source compound is to be selected from one or more in ferric sulfate, ferrous sulfate, ferrocene, iron chloride, ferrous oxalate and composition thereof; Described Li source compound is to be selected from one or more in lithium hydroxide, lithium carbonate, lithium acetate and composition thereof.
8. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 6, wherein, described in comprise ethene and/or acetylene air-flow comprise inert gas, as nitrogen and/or argon gas, the dividing potential drop of this inert gas is not less than 30% of air-flow total pressure.
9. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 7, wherein, in described step 1) in, described P source compound, Fe source compound and Li source compound be take independently respectively the aqueous solution form that molar concentration is 0.02 mol/L to 1 mol/L and are added.
10. the preparation method of the lithium iron phosphate-carbon material composite as described in above-mentioned 1 to 5 any one, wherein, in step 3) in, under fluidized state, carry out described powder calcination processing, this calcination processing possesses one or more in following characteristics:
E) adopt gas-solid fluidized pattern, air speed is 1-5000 hour
-1, the void tower flow velocity of gas is 0.005-1 meter per second, the bed density in reactor remains on 5-800 kilograms per cubic meter;
F) bed temperature is 200-900 ℃, preferred 300-800 ℃, more preferably 500-800 ℃, calcination processing time 2-36 hour, preferably 4-24 hour;
G) the equal granular size of the number of LiFePO4 used or lithium iron phosphate-carbon material composite is 0.02-10 micron, preferably 0.05-5 micron, more preferably 0.05-2 micron; And/or
H) adopt the mixture of inert gas or inert gas and reducibility gas as fluidizing gas, wherein, described inert gas is to be selected from one or more in argon gas, nitrogen, helium and composition thereof, and described reducibility gas is to be selected from one or more in hydrogen, methane, ethene, acetylene, propylene, butylene, butane and composition thereof.
The preparation method of 11. lithium iron phosphate-carbon material composites as described in above-mentioned 1 to 5 any one, wherein, in described step 2) solvent heat treatment in, by described slurry product in closed container at 80-200 ℃, preferably 120-200 ℃ is carried out solvent heat treatment, processing time 1-36 hour, preferably 2-24 hour; And/or
In described step 3) before, will be through step 2) product after solvent heat treatment is at 60-120 ℃, and preferably 80-120 ℃ is dried and pulverizes.
Lithium iron phosphate-carbon material composite prepared by the method described in 12. above-mentioned 1 to 11 any one.
By preparation method of the present invention, can prepare average grain diameter is 0.02-10 μ m (micron), tap density 1.8-2.2g/cm
3, under room temperature, 0.2C specific discharge capacity can reach the lithium iron phosphate-carbon material composite of 140-165mAh/g, and this compound can be used as the anode material for lithium-ion batteries of high-volume and capacity ratio, high cyclical stability.
Accompanying drawing explanation
The present invention by reference to the accompanying drawings and following embodiment and embodiment will be better understood:
Fig. 1 shows the ESEM picture of LiFePO4-graphene complex of embodiment 1.
Fig. 2 shows X-ray diffraction (XRD) spectrogram of LiFePO4-graphene complex of embodiment 1.
LiFePO4-graphene complex that Fig. 3 shows embodiment 1 relation curve of specific capacity and voltage in charge and discharge process under 0.2C current condition.
Fig. 4 shows the specific discharge capacity of selecting LiFePO4-carbon composite that agglomerate multi-walled carbon nano-tubes prepares as material with carbon element in embodiment 4.
Fig. 5 shows the ESEM picture of embodiment 5 LiFePO4 samples.
Embodiment
Object of the present invention comprises for example provides LiFePO4 or the preparation method of lithium iron phosphate-carbon material composite and the lithium iron phosphate-carbon material composite of being prepared by the method that technique is simple, with low cost, be suitable for suitability for industrialized production.
In said method of the present invention, by the solvent heat treatment at 80-200 ℃, obtain slurry product, after drying in inert atmosphere at 60-120 ℃ after vacuum filtration, pulverizing, utilize nanometer agglomerate fluid bed under inertia or reducing atmosphere, carrying out a step or the calcining of two steps and reprocessing, thereby obtain the lithium iron phosphate-carbon material composite with homogeneous particle size distribution.
Specifically, the invention provides the preparation method of lithium iron phosphate-carbon material composite, it comprises following steps:
A) material with carbon element is scattered in water and/or alcohol, obtains dispersion liquid;
B) phosphorus source, source of iron, Li source compound (and additive) respectively in the mixed liquor of water-soluble, alcohol or water and alcohol, are obtained respectively to corresponding solution;
C) dispersion liquid step a) being obtained and step b) in the various solution that obtain mix, obtain slurry product; With
D) described slurry product is carried out to solvent heat treatment in the temperature raising in closed container;
Optionally:
E) by steps d) in after products therefrom suction filtration, oven dry, pulverizing with carbon-source cpd solid phase mixing or be immersed in the solution of carbon-source cpd, then filter and oven dry obtains powder, wherein carbon-source cpd comprises one or more the mixture among sucrose, glucose, citric acid, starch, pitch, wax oil, be immersed in solvent that the solution of carbon-source cpd uses and comprise one or more the mixture among water, ethanol, acetone, benzene,toluene,xylene, this solution comprises about 0.01 % by weight or more described carbon-source cpd in carbon;
With
F) to steps d) or product e) obtaining in the temperature raising, carry out powder calcination processing, it is coated that the air-flow that wherein optional introducing comprises ethene and/or acetylene in this calcination processing process carries out gas-phase carbon, and this air-flow comprises about 0.01 % by weight or more described ethene and/or acetylene in carbon.
In described method, according to step c) preferred version one, first by step b) in the P source compound solution that obtains be added drop-wise in the material with carbon element dispersion liquid that step obtains in a), stir about 10-60 minute, then drip step b) in the Fe source compound solution that obtains, stir about 10-60 minute, drip again step b) in the Li source compound solution that obtains, stir about 10-60 minute, finally drip step b) in the additive solution that obtains, obtain slurry product;
In described method, according to step c) preferred version two, first by step b) in the additive solution that obtains be added drop-wise in the material with carbon element dispersion liquid that step obtains in a), stir about 10-60 minute, then drip step b) in the Fe source compound solution that obtains, stir about 10-60 minute, then drip step b) in the Li source compound solution that obtains, finally drip step b) in the P source compound solution that obtains, obtain slurry product;
In described method, according to step c) preferred version three, respectively, by step b) in the solution of the additive 1 that obtains be added drop-wise in the material with carbon element dispersion liquid that step obtains in a), by step b) in the Fe source compound solution that obtains be added drop-wise in P source compound solution, stir about 10-60 minute, then solution obtained above or dispersion liquid are mixed, stir about 10-60 minute, drip again step b) in the Li source compound solution that obtains, finally drip step b) in the solution of the additive 2 that obtains, obtain slurry product; Additive 1 and additive 2 are one or more in ammoniacal liquor, citric acid, ascorbic acid, glucose, urea, neopelex, softex kw and composition thereof independently of one another.
In described method, preferably, in steps d) in, by described slurry product in closed container about 200 ℃ of about 80-, preferably approximately about 200 ℃ of 120-carries out solvent heat treatment, about 36 hours of about 1-of processing time, preferably approximately 2-is about 24 hours;
In described method, preferably, at step e) in, to the product after solvent heat treatment about 120 ℃ of about 60-, preferably approximately dry at about 120 ℃ of 80-, pulverize, then about 900 ℃ of about 200-, preferably approximately 300-is about 800 ℃, more preferably approximately about 800 ℃ of 500-carries out powder calcination processing, about 36 hours of the about 2-of calcination time, and preferably approximately 4-is about 24 hours.
In described method, preferably, step a) in, in dispersion liquid, the content of material with carbon element is the about 1g/ml of about 0.001-.
In described method, preferably, at step b) in, in solution, the molar concentration of solute is the about 1mol/L of about 0.02-.
In described method, in slurry product, each component proportion is for being approximately: material with carbon element: P source compound: Fe source compound: Li source compound (: additive)=0.05-3: 1: 1: 1-3 (: 0.01-1) (mol ratio).
Described alcohol is to be selected from one or more in methyl alcohol, ethanol, ethylene glycol and composition thereof, and the mixture that forms of methyl alcohol, ethanol, ethylene glycol or its mixture and water.
Described P source compound can be the conventional any P source compound in this area, comprises phosphorous organic substance or inorganic matter, preferably phosphoric acid or phosphate that any this area is applicable.For example, described P source compound is to be selected from one or more in phosphoric acid, ferric phosphate, ferrous phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate and composition thereof.
Described Fe source compound can be the conventional any Fe source compound in this area, but it is preferably selected from one or more in ferric sulfate, ferrous sulfate, ferrocene, iron chloride, ferrous oxalate and composition thereof.
Described Li source compound can be the conventional any Li source compound in this area, but it is preferably selected from one or more in lithium hydroxide, lithium carbonate, lithium acetate and composition thereof.
Described additive can be the conventional any additive in this area, but it is preferably selected from one or more in citric acid, ascorbic acid, glucose, urea, neopelex, softex kw and composition thereof.
Described material with carbon element can be the conventional any material with carbon element in this area, but it is preferably selected from one or more in carbon black, active carbon, carbon nano-tube, Graphene and composition thereof.
In described method, the air-flow that comprises ethene and/or acetylene described in preferably comprises inert gas, as nitrogen and/or argon gas.In one embodiment, make the dividing potential drop of inert gas be not less than 30% of air-flow total pressure.
The invention provides the preparation method of a kind of LiFePO4 or lithium iron phosphate-carbon material composite, it is characterized in that comprising following steps: adopt fluidized-bed reactor, under fluidized state, carry out powder calcination and particle surface and process.
In one embodiment, in the preparation method of described LiFePO4 or lithium iron phosphate-carbon material composite, under fluidized state, carry out described powder calcination and particle surface and process, and possess one or more in following characteristics:
A) adopt gas-solid fluidized pattern, air speed is about 5000 hours of about 1-
-1, the void tower flow velocity of gas is about 1 meter per second of about 0.005-, the bed density in reactor remains on about 800 kilograms per cubic meter of about 5-;
B) bed temperature is about 900 ℃ of about 200-, and preferably approximately 300-is about 800 ℃, and more preferably about 500-is about 800 ℃, about 36 hours of calcining and about 2-of surface treatment time, and preferably approximately 4-is about 24 hours;
C) mean particle size of LiFePO4 used or lithium iron phosphate-carbon material composite is about 10 microns of about 0.02-, and preferably approximately 0.05-is about 5 microns, and more preferably about 0.05-is about 2 microns;
D) adopt the mixture of inert gas or inert gas and reducibility gas as fluidizing gas, wherein, inert gas is to be selected from one or more in argon gas, nitrogen, helium and composition thereof, and reducibility gas is to be selected from one or more in hydrogen, methane, ethene, acetylene, propylene, butylene, butane and composition thereof.
Below by specific embodiment, the specific embodiment of the present invention is described in detail, following embodiment is only for the present invention is described, but the practical range being not intended to limit the present invention.
Embodiment 1
(preparation method of this kind of Graphene is shown in Ning, G. to weigh 1.2g Graphene; Fan, Z.; Wang, G.; Gao, J.; Qian, W.; Wei, F.Chemical Communications 2011,47,5976), add in the mixed solution (ethanol: water=1: 3, volume ratio) of 100mL second alcohol and water, 5 minutes (Ultrasound Instrument model KH-2200 of ultrasonic dispersion, power 600W, Kechuang supermarket, Kunshan Instrument Ltd.), the dispersion liquid of formation homogeneous.Weigh respectively 9.8g phosphoric acid, 27.8g ferrous sulfate hydrate, 4.2g lithium hydroxide and 5g citric acid, add respectively and in 500mL deionized water, obtain solution separately.Under agitation, first phosphate aqueous solution is added drop-wise in the dispersion liquid of Graphene and continues and stir 10 minutes, then drip ferrous sulfate aqueous solution and continue and stir 10 minutes, drip again lithium hydroxide aqueous solution and continue and stir 10 minutes, finally drip aqueous citric acid solution and continue and stir 10 minutes, obtain slurry product.Gained slurry is transferred in seal-off pressure container, and heat treatment is 12 hours at 110 ℃, takes out slurry after being down to room temperature, suction filtration, in inert atmosphere, dries, is ground to powder.Finally described powder is put in horizontal pipe furnace reactor (quartz ampoule, long 1000mm, diameter 50mm), under 0.2L/min Ar entraining air stream, be warming up to 600 ℃, calcination processing 6 hours, is down to room temperature powder sample is taken out, and products obtained therefrom is LiFePO4-graphene complex.
Fig. 1 shows the ESEM picture of LiFePO4-graphene complex of embodiment 1.As shown in Figure 1, sample prepared by said process contains uniform nano particle, the about 50nm of average grain diameter.Adopt the anode of the LiFePO4-graphene complex making lithium ion battery prepare above, obtained higher charge/discharge capacity, good multiplying power property and cycle performance.Fig. 2 shows X-ray diffraction (XRD) spectrogram of LiFePO4-graphene complex of embodiment 1.LiFePO4-graphene complex that Fig. 3 shows embodiment 1 relation curve of specific capacity and voltage in charge and discharge process under 0.2C current condition.Charge and discharge platform voltage very close (being respectively 3.45V and 3.39V) as can be seen from Figure 3, illustrate that electrode material pattern in charge and discharge process, structure are more stable, not along with the remarkable deformation of producing of electrode reaction, this is very important for the stability and the useful life that increase electrode.Under 0.2C charging and discharging currents condition, specific discharge capacity can reach 155mAh/g, and under 5C charging and discharging currents condition, specific discharge capacity can reach 135mAh/g.Under 1C charging and discharging currents condition, charge and discharge cycles 100 times, capability retention can reach 85%.
Embodiment 2
Adopt same proportioning and slurry solvent heat treatment process with embodiment 1, the powder obtaining after solvent heat treatment is added in vertical fluidized bed, first pass into 1L/min argon gas, be warming up to 600 ℃, then pass into 1L/min ethene, after 30 minutes, close ethene, pass into 0.03L/min hydrogen, calcine 6 hours.Be cooled to and take out gained powder sample after room temperature and be final products.
Gained lithium iron phosphate-carbon material composite tap density 2.2g/cm
3, under 0.2C charging and discharging currents condition, specific discharge capacity can reach 163mAh/g, and under 5C charging and discharging currents condition, specific discharge capacity can reach 145mAh/g.Under 1C charging and discharging currents condition, charge and discharge cycles 100 times, capability retention can reach 89%.
Embodiment 3
Adopt same proportioning and slurry solvent heat treatment process with embodiment 1; the powder obtaining after solvent heat treatment is mixed with 3g sucrose; in high speed disintegrator, stir; then putting into diameter is the horizontal tube reactor of 30mm; under 0.2L/min Ar air-flow protection, carry out 200 ℃ of calcining 2h; again gained pressed powder is added in vertical fluidized bed and calcined and reprocessing: first pass into 1L/min argon gas; be warming up to 600 ℃; then pass into 1L/min ethene; after 30 minutes, close ethene; pass into 0.03L/min hydrogen, calcine 6 hours.Be cooled to and take out gained powder sample after room temperature and be final products.
Gained lithium iron phosphate-carbon material composite tap density 2.1g/cm
3, under 0.2C charging and discharging currents condition, specific discharge capacity can reach 160mAh/g, and under 5C charging and discharging currents condition, specific discharge capacity can reach 145mAh/g.Under 1C charging and discharging currents condition, charge and discharge cycles 100 times, capability retention can reach 91%.
Embodiment 4
Identical with embodiment 1, just material with carbon element is selected carbon nano-tube, carbon black or activated carbon, directly prepares LiFePO4-carbon mano-tube composite, LiFePO4-carbon black compound or LiFePO4-active carbon compound.
(preparation method is shown in Y.Wang, F.Wei, G.Luo to select agglomerate multi-walled carbon nano-tubes, H.YuandG.Gu, Chem.Phys.Lett., 2002,364,568.) LiFePO4-carbon composite preparing as material with carbon element has higher charging and discharging capacity and good cycle life.As shown in Figure 4, under 0.2C charging and discharging currents condition, specific discharge capacity can reach 161mAh/g, and under 1C charging and discharging currents condition, specific discharge capacity can reach 147mAh/g, and under 5C charging and discharging currents condition, specific discharge capacity can reach 121mAh/g.
Embodiment 5
Weigh 11.5g ammonium dihydrogen phosphate, 40.4g ferric nitrate, 6.6g lithium acetate, 1.76g ascorbic acid and 1.8g softex kw, be dissolved in respectively in 100mL water, obtain the aqueous solution of each compound.Under agitation, softex kw solution is added drop-wise in ammonium dihydrogen phosphate and is continued and stir 30 minutes, then dripping iron nitrate solution is added drop-wise in said mixture and continues stirring 30 minutes, drip again lithium acetate solution and continue and stir 30 minutes, finally drip ascorbic acid solution and continue and stir 30 minutes, obtain slurry product.Products therefrom is transferred in seal-off pressure container, and solvent heat treatment is 8 hours at 200 ℃, takes out slurry after being down to room temperature, in inert atmosphere, dries 12 hours for 80 ℃, is then ground to powder.Finally described powder is added in fluidized-bed reactor, at 500 ℃, fluidisation 20min in the mixed airflow of 0.5L/min argon gas and 0.9L/min acetylene, then closes acetylene, is warming up to 700 ℃ of calcinings 2 hours.After being down to room temperature, gained powder is taken out and is final products.
LiFePO4-carbon composite prepared by described process contains the spindle particle shown in Fig. 5, and under 0.2C charging and discharging currents condition, specific discharge capacity can reach 150mAh/g, and under 5C charging and discharging currents condition, specific discharge capacity can reach 135mAh/g.Under 1C charging and discharging currents condition, charge and discharge cycles 100 times, capability retention can reach 88%.
Embodiment 6
(preparation method of this kind of Graphene is shown in Ning, G. to weigh 1.5g Graphene sample; Fan, Z.; Wang, G.; Gao, J.; Qian, W.; Wei, F.Chemical Communications 2011,47,5976), be under agitation dispersed in 100mL ethylene glycol, weigh respectively 9.8g phosphoric acid, 27.8g green vitriol, 11.3g hydronium(ion) oxidation lithium, be dissolved in respectively in 100mL ethylene glycol.Under agitation, first copperas solution is added drop-wise in graphene dispersing solution and continues and stir 30 minutes, then drip lithium hydroxide solution and continue and stir 30 minutes, finally drip phosphoric acid solution and continue and stir 60 minutes.Gained slurry is transferred in seal-off pressure container, and solvent heat treatment is 10 hours at 180 ℃, takes out slurry after being down to room temperature, after suction filtration, rinsing, in inert atmosphere, dries, and is ground to powder.Described powder is added in fluidized-bed reactor, at 550 ℃, in the mixed airflow of 5L/min nitrogen and 0.05L/min hydrogen, calcine 2 hours, be then cooled to room temperature, gained powder is has LiFePO4-graphene complex.
This LiFePO4-graphene complex has the particle size that is less than 100nm, and 0.1C discharges and recharges specific discharge capacity 165mAh/g under condition.
Claims (10)
1. the preparation method of lithium iron phosphate-carbon material composite, the method comprises the following steps:
1) in containing the dispersion liquid of material with carbon element, add P source compound, Fe source compound and Li source compound, obtain slurry product,
Wherein, described material with carbon element is to be selected from one or more in carbon black, active carbon, carbon nano-tube, Graphene and composition thereof;
Solvent in the dispersion liquid of described carbonaceous material is the mixture of water, alcohol or water and alcohol, and in described dispersion liquid, the concentration of material with carbon element is 0.001 grams per milliliter to 1 grams per milliliter;
2) will be by step 1) the slurry product that obtains at 80-200 ℃, carries out solvent heat treatment, processing time 1-36 hour in closed container; With
3) will be by step 2) the product suction filtration or the centrifugal post-drying that obtain, bake out temperature is 60-120 ℃, then under fluidized state, carries out powder calcination processing, this calcination processing condition is:
Adopt gas-solid fluidized pattern, air speed is 1-5000 hour
-1, the void tower flow velocity of gas is 0.005-1 meter per second, the bed density in reactor remains on 5-800 kilograms per cubic meter;
Bed temperature is 200-900 ℃, calcination processing time 2-36 hour;
The equal granular size of number of LiFePO4 used or lithium iron phosphate-carbon material composite is 0.02-10 micron;
In powder calcination processing procedure, introducing the air-flow comprise ethene and/or acetylene, to carry out gas-phase carbon coated, described in comprise ethene and/or acetylene air-flow comprise inert gas, the dividing potential drop of this inert gas is not less than 30% of air-flow total pressure.
2. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 1, wherein, described alcohol is selected from one or more in methyl alcohol, ethanol, ethylene glycol and composition thereof.
3. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 2, wherein
In step 3) also comprise before, by by step 2) product that the obtains step of mixing with one or more carbon-source cpd among being selected from sucrose, glucose, citric acid, starch, pitch, wax oil; And/or
In step 1) in also comprise and add the step that is selected from one or more additives in ammoniacal liquor, citric acid, ascorbic acid, glucose, urea, neopelex, softex kw and composition thereof.
4. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 3, wherein, described P source compound is to be selected from one or more in phosphoric acid, ferric phosphate, ferrous phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate and composition thereof; Described Fe source compound is to be selected from one or more in ferric sulfate, ferrous sulfate, ferrocene, iron chloride, ferrous oxalate and composition thereof; Described Li source compound is to be selected from one or more in lithium hydroxide, lithium carbonate, lithium acetate and composition thereof.
5. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 1, wherein, described inert gas is nitrogen and/or argon gas.
6. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 5, wherein, in described step 1) in, described P source compound, Fe source compound and Li source compound be take independently respectively the aqueous solution form that molar concentration is 0.02 mol/L to 1 mol/L and are added.
7. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 1, wherein, described bed temperature is 300-800 ℃, calcining 4-24 hour; The equal granular size of number of LiFePO4 used or lithium iron phosphate-carbon material composite is 0.05-5 micron.
8. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 7, wherein, described bed temperature is 500-800 ℃, the equal granular size of number of LiFePO4 used or lithium iron phosphate-carbon material composite is 0.05-2 micron.
9. the preparation method of lithium iron phosphate-carbon material composite as claimed in claim 1, wherein, in described step 2) solvent heat treatment in, described slurry product is carried out to solvent heat treatment at 120-200 ℃ in closed container, processing time 2-24 hour; And/or
In described step 3) in, bake out temperature is 80-120 ℃.
10. the lithium iron phosphate-carbon material composite that prepared by the method described in claim 1 to 9 any one.
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| CN103204486B (en) * | 2013-04-16 | 2015-02-25 | 成都牧甫科技有限公司 | Grapheme lithium iron phosphate in composite polycrystalline structure and preparation method thereof |
| CN103359701B (en) * | 2013-06-28 | 2015-10-21 | 清华大学 | The preparation method of iron lithium phosphate |
| CN103427079A (en) * | 2013-08-09 | 2013-12-04 | 中物院成都科学技术发展中心 | Preparation method of lithium ion phosphate/carbon composite material for high-rate-capability lithium ion battery |
| CN103456956B (en) * | 2013-09-29 | 2015-12-23 | 东华大学 | A kind of preparation method of carbon nano tube modified manganese phosphate lithium ion cell anode |
| CN103779540A (en) * | 2014-01-15 | 2014-05-07 | 合肥国轩高科动力能源股份公司 | Lithium-ion cell material synthesis device and synthesis method thereof |
| CN105098152B (en) * | 2015-06-25 | 2018-11-06 | 中国航发北京航空材料研究院 | A kind of preparation method of lithium iron phosphate battery positive material |
| CN106654264A (en) * | 2017-01-12 | 2017-05-10 | 吉林大学 | Solvothermal assisted preparation method of LiFePO4/C multistage composite microspheres |
| CN110165203A (en) * | 2019-07-11 | 2019-08-23 | 兰州理工大学 | A method of improving lithium iron phosphate positive material cryogenic property |
| CN115172718A (en) * | 2022-08-01 | 2022-10-11 | 湖北万润新能源科技股份有限公司 | Method for preparing lithium iron manganese phosphate by solid-phase coating method |
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| CN101699639A (en) * | 2009-07-01 | 2010-04-28 | 北京高盟化工有限公司 | Method for preparing carbon-coated nano-grade lithium iron phosphate composite anode material |
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