CN101973539B - Method for synthesizing lithium iron phosphate anode material at low cost - Google Patents
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- CN101973539B CN101973539B CN2010105230092A CN201010523009A CN101973539B CN 101973539 B CN101973539 B CN 101973539B CN 2010105230092 A CN2010105230092 A CN 2010105230092A CN 201010523009 A CN201010523009 A CN 201010523009A CN 101973539 B CN101973539 B CN 101973539B
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- 238000000034 method Methods 0.000 title claims abstract description 28
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 24
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 7
- 239000010405 anode material Substances 0.000 title abstract description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 36
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 34
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000000843 powder Substances 0.000 claims abstract description 28
- 239000002243 precursor Substances 0.000 claims abstract description 28
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 26
- 238000003756 stirring Methods 0.000 claims abstract description 20
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 18
- 238000005245 sintering Methods 0.000 claims abstract description 17
- 229910052742 iron Inorganic materials 0.000 claims abstract description 9
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 9
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 9
- 238000000227 grinding Methods 0.000 claims abstract description 6
- 239000011261 inert gas Substances 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 20
- 238000005303 weighing Methods 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 239000007789 gas Substances 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 8
- 239000007774 positive electrode material Substances 0.000 claims description 8
- 238000010790 dilution Methods 0.000 claims description 7
- 239000012895 dilution Substances 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- 239000006230 acetylene black Substances 0.000 claims description 6
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 5
- 229910052744 lithium Inorganic materials 0.000 claims description 5
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 4
- 229920000642 polymer Polymers 0.000 claims description 4
- 229920002472 Starch Polymers 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 239000006229 carbon black Substances 0.000 claims description 3
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 3
- 235000019698 starch Nutrition 0.000 claims description 3
- 239000008107 starch Substances 0.000 claims description 3
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 2
- 238000005469 granulation Methods 0.000 claims description 2
- 230000003179 granulation Effects 0.000 claims description 2
- YOBAEOGBNPPUQV-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe].[Fe] YOBAEOGBNPPUQV-UHFFFAOYSA-N 0.000 claims description 2
- 238000003801 milling Methods 0.000 claims description 2
- 239000007921 spray Substances 0.000 claims description 2
- 238000001694 spray drying Methods 0.000 claims description 2
- 238000009423 ventilation Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 29
- 239000002002 slurry Substances 0.000 abstract description 16
- 238000001035 drying Methods 0.000 abstract description 6
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 239000002994 raw material Substances 0.000 abstract description 6
- 239000011164 primary particle Substances 0.000 abstract description 4
- 238000006243 chemical reaction Methods 0.000 abstract description 3
- 238000005507 spraying Methods 0.000 abstract description 3
- 238000000746 purification Methods 0.000 abstract description 2
- 238000001953 recrystallisation Methods 0.000 abstract description 2
- 238000005253 cladding Methods 0.000 abstract 1
- 238000001816 cooling Methods 0.000 abstract 1
- SNKMVYBWZDHJHE-UHFFFAOYSA-M lithium;dihydrogen phosphate Chemical compound [Li+].OP(O)([O-])=O SNKMVYBWZDHJHE-UHFFFAOYSA-M 0.000 abstract 1
- 239000000203 mixture Substances 0.000 abstract 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 7
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- 239000002253 acid Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 238000012856 packing Methods 0.000 description 4
- 239000000725 suspension Substances 0.000 description 4
- 238000010792 warming Methods 0.000 description 4
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 2
- 244000208060 Lawsonia inermis Species 0.000 description 2
- 229910015645 LiMn Inorganic materials 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- LDHBWEYLDHLIBQ-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide;hydrate Chemical compound O.[OH-].[O-2].[Fe+3] LDHBWEYLDHLIBQ-UHFFFAOYSA-M 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000003836 solid-state method Methods 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910010710 LiFePO Inorganic materials 0.000 description 1
- 229910013290 LiNiO 2 Inorganic materials 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000005030 aluminium foil Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 235000011089 carbon dioxide Nutrition 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-M dihydrogenphosphate Chemical compound OP(O)([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-M 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 1
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 description 1
- 229910001386 lithium phosphate Inorganic materials 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000009768 microwave sintering Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
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- 239000002904 solvent Substances 0.000 description 1
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- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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Abstract
The invention discloses a method for synthesizing lithium iron phosphate anode material at low cost, which belongs to the technical field of energy materials. The method comprises the following steps: preparing a solution containing equimolar Li+ and H2PO4- from lithium salt and phosphoric acid directly; adding an iron source, an organic carbon source and an inorganic carbon source into the solution, and grinding the mixture in a stirring ball mill to obtain precursor slurry; spraying the precursor slurry, drying and granulating to obtain spherical precursor powder; and sintering the precursor powder in a rotary furnace under the protection of inert gas, and naturally cooling to the room temperature to obtain the product. As the solution containing equimolar Li+ and H2PO4- is directly prepared, the steps of reaction, purification, re-crystallization, drying and the like during the manufacturing of lithium dihydrogen phosphate are saved, and the cost of the raw materials is reduced by over 20%. Moreover, by adopting of a joint cladding means combining organic carbon and inorganic carbon, the method reduces the primary particle size (about 200 nm) of the lithium iron phosphate powder, improves the conductivity of the material and greatly enhances the electrochemical performance of the product.
Description
Technical field
The invention belongs to the energy and material preparing technical field, particularly be used for the method for a kind of low-cost synthesizing iron lithium phosphate positive electrode material of lithium ion battery.
Background technology
At present, lithium ion battery negative material and electrolyte system aspect obtain bigger progress, and the development of positive electrode material relatively lags behind, and this has had a strong impact on the motorization process of lithium ion battery.It mainly shows as: the one, and safety-problems, unique business-like positive electrode material LiCoO
2Stable inadequately, can decompose when overheated overcharging, possibly cause battery explosion, this shows particularly outstanding on power cell; The 2nd, the cost problem, the reserves of global cobalt are limited, thereby price is very high, has limited LiCoO
2Application in power cell; The 3rd, environmental problem, cobalt can cause certain infringement to environment and human body.Therefore, seek safety and stability more, raw material sources are extensive and cheap, and more the positive electrode material of environmental protection is pressing for of development lithium-ion-power cell.LiNiO
2Structure and LiCoO
2Similar, it has the advantage on price and the reserves, but has synthetic difficulty, structure is prone to undergo phase transition and shortcoming such as poor heat stability.Even through doping vario-property, its actual possibility of its application is also little.Spinel type LiMn
2O
4Have security good, be prone to advantages such as synthetic, be one of more anode material for lithium-ion batteries of research at present.But LiMn
2O
4Theoretical capacity is lower, and has the John-Teller effect in the lattice, in charge and discharge process, is prone to the recurring structure distortion, causes capacity to decay rapidly, and particularly under the working conditions of comparatively high temps, capacity attenuation is more outstanding.
Reported first such as Goodenough in 1997 have the iron lithium phosphate (LiFePO of olivine-type structure
4) can embed and the removal lithium embedded ion, have nontoxic, environmentally friendly, abundant, the advantages such as specific storage is high, Heat stability is good, cycle performance excellence in starting material source, be considered to the most promising positive electrode material. reversiblelyBut there is following significant disadvantages in iron lithium phosphate: Fe in (1) building-up process
2+Be oxidized to Fe easily
3+, be difficult to obtain the iron lithium phosphate of pure phase; (2) Li
+Rate of diffusion in iron lithium phosphate is low, causes the utilization ratio of active material low; (3) specific conductivity of iron lithium phosphate itself is low, causes its high-rate charge-discharge capability poor.These shortcomings have seriously hindered the practical application of LiFePO 4 material.In recent years, along with to the going deep into of the various method researchs that improve its electroconductibility, the electroconductibility of said material has reached realistic scale and received people to be paid close attention to greatly.Improve one's methods and mainly contain: the protection of inert gas sintering is adopted in (1), prevents Fe
2+Oxidation.(2) reduce the size of iron lithium phosphate crystal grain, shorten Li
+Diffusion length, improve the ionic conductivity of material.(3) surperficial coated with conductive material or bulk phase-doped high volence metal ion, the electron conduction of raising material.
The main method of synthesizing iron lithium phosphate is a high temperature solid-state method at present.Be characterized in that with Ferrox (source of iron), primary ammonium phosphate (phosphorus source) and three kinds of raw materials of Quilonum Retard (lithium source) through mixing and ball milling, sintering forms under inert atmosphere protection.This method has three significant disadvantages:
(1) the source of iron Ferrox (FeC that adopts
2O
42H
2O) unstable in air, ferrous iron is oxidized to ferric iron easily.In addition, it contains crystal water, is difficult for accurately metering.The instability of raw material can be brought to quality product and seriously influence.Because the restriction of technology and equipment is difficult to three kinds of raw materials are mixed by stoichiometric ratio, thereby influence batch stability of product.
(2) owing to produce a large amount of gases in the production process, solid burns the mistake rate greater than 50%, and product structure is fluffy, and tap density is extremely low (has only 0.5g/cm
3).Improved high temperature solid-state method adopts sintering twice, all needs protection of inert gas.Be low temperature (about 350 ℃) sintering for the first time, remove gas a large amount of in the raw material reaction thing, form the fluffy midbody of structure.After midbody was handled through pulverizing, compound stalk forming etc., high temperature (about 700 ℃) double sintering 10 ~ 20h under protection of inert gas generated iron lithium phosphate again.
(3) for improving material activity, adopt wet ball grinding usually.Make solvent with inflammable organism such as absolute ethyl alcohol or acetone, the organic solvent volatilization can produce strong smell in the drying process, and causes disaster hidden-trouble easily; Except producing water and carbonic acid gas, the primary ammonium phosphate decomposition can generate the ammonia that has intense stimulus property smell in a large number, and atmosphere is polluted in the sintering process.
How low cost prodn goes out steady quality and the good iron lithium phosphate of chemical property, and the application in new-energy automobile has very significant meaning for the propulsion power battery.The method that this paper author proposes to adopt spraying drying to combine with microwave sintering in patent " a kind of method for preparing lithium iron phosphate positive material " (application number is 201010161398.9) prepares iron lithium phosphate, this method have technology simply, advantages such as environmental protection and steady quality.But because monometallic (LiH
2PO
4) on the high side, and its proportion in material cost causes the iron lithium phosphate price not reach reasonable levels above 60%.Actual production process is with LiH
2PO
4Pressed powder is dissolved in the water and with other starting material and mixes into uniform slurry, LiH in slurry
2PO
4Meeting ionization is with lithium ion (Li
+) and dihydrogen phosphate ions (H
2PO
4 -) the form existence.That therefore, really need in the production process is not LiH
2PO
4Pressed powder, but mole Li such as contain
+And H
2PO
4 -Solution.This paper such as proposes to adopt suitable lithium salts and phosphoric acid to be mixed with to contain at mole Li
+And H
2PO
4 -Solution, replace expensive LiH
2PO
4Pressed powder, thus material cost reduced significantly.In addition, the method coated LiFePO 4 for lithium ion batteries particle that adopts inorganic carbon and organic carbon to combine can effectively reduce the primary particle particle diameter and improve the electroconductibility of material, thereby increases substantially the large current discharging capability of material.
Summary of the invention
The purpose of this invention is to provide that a kind of technology that is used for lithium ion battery is simple, with low cost, environmental protection, be fit to the method for the stable high-performance iron phosphate lithium material of the quality of production.
Technical scheme of the present invention is following: a kind of method of low-cost synthesizing iron lithium phosphate positive electrode material is carried out according to the following steps:
(1) takes by weighing lithium salts, source of iron and phosphoric acid by a certain percentage.Wherein elemental lithium, ferro element and phosphoric mol ratio Li:Fe:P=1:1:1.
(2) a certain amount of deionized water is placed acid-resistant reacting kettle, under condition of stirring, slowly pour whole phosphoric acid into, the massfraction of dilution back phosphoric acid is 20～40%.
(3) under condition of stirring, lithium salts is slowly added in the above-mentioned solution, add continued and stir 30min, refilter the colourless transparent solution that obtains homogeneous, and it all is transferred in the agitating ball mill.
(4) take by weighing organic carbon source and inorganic carbon source by a certain percentage, wherein the mass ratio of organic carbon source and phosphoric acid is 0.02～0.05, and the mass ratio of inorganic carbon source and phosphoric acid is 0.05～0.10.
(5) with grinding in source of iron, organic carbon source and the inorganic carbon source adding agitating ball mill, obtain the precursor slurry.
(6) the precursor slurry is transported to spray-drier through volume pump and carries out spray drying granulation, obtain the spherical precursor powder particle.
(7) place rotary kiln to carry out sintering in the precursor powder, naturally cool to room temperature and obtain product with protection of inert gas.
Lithium salts described in the step (1) is Lithium Hydroxide MonoHydrate (LiOHH
2O), Quilonum Retard (Li
2CO
3) in a kind of; Source of iron is red iron oxide (Fe
2O
3), iron oxide black (Fe
3O
4), yellow oxide of iron (Fe
2O
3H
2O) a kind of in; Phosphoric acid is industrial phosphoric acid (massfraction is 75% or 85%).
The said organic carbon source of step (4) is a kind of in Vinylpyrrolidone polymer (PVP), Zulkovsky starch, the Z 150PH (PVA); Inorganic carbon source is a kind of in acetylene black, the superconduction carbon black.The effect of organic carbon source has two: one is that cracking at high temperature forms reducing gas, and ferric iron is reduced into ferrous iron; One is the residual particle surface that is coated on of carbonization, hinders grain growth.The effect of inorganic carbon source is to be coated on particle surface, improves the electroconductibility of material.
Agitating ball mill has surge pump that slurry is done the pressure circulation in the step (5), and grinding condition is 100～400 rev/mins of revolutions, and milling time is 2～6h.
Spraying drying is in constantly stirring, to carry out in the step (6), and spray inlet temperature is 240～350 ℃, and temperature out is 100～150 ℃, and input speed is 0.2～1L/min.
The rare gas element that adopts is high pure nitrogen or argon gas in the step (7), and ventilation flow rate is 1～4L/min, and temperature rise rate is 2～6 ℃/min, and sintering temperature is 600～750 ℃, and the constant temperature sintering time is 2～8h.
This method biggest advantage is with low cost, and the product powder granule primary particle size of preparing in addition is little, has better machining property, is particularly suitable for heavy-current discharge.Because this law adopts that directly the preparation of lithium salts and phosphoric acid contains etc. mole Li
+And H
2PO
4 -Solution, save and make reaction in the monometallic manufacturing processed, purification, recrystallization, drying and other steps, make material cost reduce more than 20%.In addition, the means that adopt organic carbon to combine with inorganic carbon and coat have jointly reduced iron lithium phosphate primary particle size (about 200nm), have improved the electroconductibility of material, thereby have increased substantially the chemical property of product.
Description of drawings
Fig. 1 is the XRD figure spectrum of embodiment 1 gained lithium iron phosphate positive material.
Fig. 2 is the SEM image of embodiment 1 gained lithium iron phosphate positive material.
The multiplying power discharging curve of Fig. 3 embodiment 1 gained lithium iron phosphate positive material.
Embodiment
Embodiment 1
Take by weighing the 12000g deionized water and place acid-resistant reacting kettle, under condition of stirring, slowly pour 5000g H into
3PO
4(massfraction 85%), dilution back H
3PO
4Massfraction be 25%.Take by weighing 1820g LiOHH
2O slowly adds in the above-mentioned solution and stirs 30min, obtains colourless solution.Colourless solution all is transferred in the agitating ball mill, adds 3469g Fe successively
2O
3, 170g Vinylpyrrolidone polymer (PVP), 374g acetylene black.Agitating ball mill grinds 3h with 300 rev/mins, obtains the red-brown suspension liquid, i.e. the precursor slurry.With the precursor slurry under continuous condition of stirring through volume pump with the flow volume delivery of 0.6L/min atomizing disk to spray-drier, inlet temperature is set at 300 ℃, temperature out is set at 120 ℃, can obtain henna precursor powder from the powder scoop.With the precursor powder saggar of packing into, place rotary kiln with high pure nitrogen protection (gas flow is 2L/min), be warming up to 700 ℃ with the speed of 5 ℃/min, constant temperature sintering 3h naturally cools to room temperature, can obtain black LiFePO 4 powder material.
Take by weighing the LiFePO 4 powder of 0.4g embodiment 1 gained; Adding 0.05g acetylene black static eliminator and 0.05g are dissolved in PVDF (PVDF) sticker of N-Methyl pyrrolidone (NMP); Being mixed into slurry evenly is coated on Φ 15 aluminium foils and processes positive plate; As negative pole, PP SHEET FOR OPP TAPE (celgard2400) is a barrier film, the LiPF of 1mol/L with metal lithium sheet
6EC+DEC (1:1) solution be electrolytic solution, in being full of the glove box of argon gas, be assembled into button cell.At normal temperatures, the 0.1C constant current charge is to 4.2V, and constant voltage is to 0.02C, and the 0.1C constant-current discharge is to 2.5V again, and the specific storage that records lithium iron phosphate positive material is 159mAh/g.Similarly discharge and recharge system, 0.5C, 1C and 3C specific discharge capacity are respectively 151mAh/g, 143mAh/g, 135mAh/g.
Embodiment 2
Take by weighing the 10000g deionized water and place acid-resistant reacting kettle, under condition of stirring, slowly pour 5000g H into
3PO
4(massfraction 85%), dilution back H
3PO
4Massfraction be 28.3%.Take by weighing 1820g LiOHH
2O slowly adds in the above-mentioned solution and stirs 30min, obtains colourless solution.Colourless solution all is transferred in the agitating ball mill, adds 3347g Fe successively
3O
4, 204g Zulkovsky starch, 272g superconduction carbon black.Agitating ball mill grinds 4h with 200 rev/mins, obtains black suspension, i.e. the precursor slurry.With the precursor slurry under continuous condition of stirring through volume pump with the flow volume delivery of 0.4L/min atomizing disk to spray-drier, inlet temperature is set at 280 ℃, temperature out is set at 110 ℃, can obtain the precursor powder of black from the powder scoop.With the precursor powder saggar of packing into, place rotary kiln with high pure nitrogen protection (gas flow is 2L/min), be warming up to 650 ℃ with the speed of 3 ℃/min, constant temperature sintering 3h naturally cools to room temperature, can obtain black LiFePO 4 powder material.Record this material 0.1C, 0.5C, 1C and 3C specific discharge capacity and be respectively 157mAh/g, 147mAh/g, 139mAh/g, 130mAh/g.
Embodiment 3
Take by weighing the 11000g deionized water and place acid-resistant reacting kettle, under condition of stirring, slowly pour 5000g H into
3PO
4(massfraction 85%), dilution back H
3PO
4Massfraction be 26.6%.Take by weighing 1602g Li
2CO
3Slowly add in the above-mentioned solution and stir 30min, obtain colourless solution.Colourless solution all is transferred in the agitating ball mill, adds 3469g Fe successively
2O
3, 136g Z 150PH (PVA), 374g acetylene black.Agitating ball mill grinds 3h with 300 rev/mins, obtains the red-brown suspension liquid, i.e. the precursor slurry.With the precursor slurry under continuous condition of stirring through volume pump with the flow volume delivery of 0.4L/min atomizing disk to spray-drier, inlet temperature is set at 320 ℃, temperature out is set at 135 ℃, can obtain henna precursor powder from the powder scoop.With the precursor powder saggar of packing into, place rotary kiln with high pure nitrogen protection (gas flow is 1L/min), be warming up to 700 ℃ with the speed of 4 ℃/min, constant temperature sintering 4h naturally cools to room temperature, can obtain black LiFePO 4 powder material.Record this material 0.1C, 0.5C, 1C and 3C specific discharge capacity and be respectively 157mAh/g, 149mAh/g, 142mAh/g, 133mAh/g.
Embodiment 4
Take by weighing the 9000g deionized water and place acid-resistant reacting kettle, under condition of stirring, slowly pour 6000g H into
3PO
4(massfraction 75%), dilution back H
3PO
4Massfraction be 30%.Take by weighing 1696g Li
2CO
3Slowly add in the above-mentioned solution and stir 30min, obtain colourless solution.Colourless solution all is transferred in the agitating ball mill, adds 4087g Fe successively
2O
3H
2O, 180g Vinylpyrrolidone polymer (PVP), 360g acetylene black.Agitating ball mill grinds 3h with 400 rev/mins, obtains yellow suspension liquid, i.e. the precursor slurry.With the precursor slurry under continuous condition of stirring through volume pump with the flow volume delivery of 0.5L/min atomizing disk to spray-drier, inlet temperature is set at 300 ℃, temperature out is set at 120 ℃, can obtain xanchromatic precursor powder from the powder scoop.With the precursor powder saggar of packing into, place rotary kiln with high pure nitrogen protection (gas flow is 2L/min), be warming up to 680 ℃ with the speed of 4 ℃/min, constant temperature sintering 3h naturally cools to room temperature, can obtain black LiFePO 4 powder material.Record this material 0.1C, 0.5C, 1C and 3C specific discharge capacity and be respectively 160mAh/g, 152mAh/g, 146mAh/g, 138mAh/g.
Claims (6)
1. the method for a synthesizing iron lithium phosphate positive electrode material is characterized in that carrying out according to the following steps:
(1) take by weighing lithium salts, source of iron and phosphoric acid by a certain percentage, wherein the mol ratio of elemental lithium, ferro element and phosphoric is Li:Fe:P=1:1:1;
(2) a certain amount of deionized water is placed acidproof stirred autoclave, under condition of stirring, slowly pour whole phosphoric acid into, the massfraction of dilution back phosphoric acid is 20～40%;
(3) under condition of stirring, lithium salts is slowly added in the phosphoric acid solution after the dilution, add continued and stir 30min, refilter the colourless transparent solution that obtains homogeneous, and all be transferred to it in agitating ball mill;
(4) take by weighing organic carbon source and inorganic carbon source by a certain percentage, wherein the mass ratio of organic carbon source and phosphoric acid is 0.02～0.05, and the mass ratio of inorganic carbon source and phosphoric acid is 0.05～0.10;
(5) with grinding in source of iron, organic carbon source and the inorganic carbon source adding agitating ball mill, obtain precursor pulp;
(6) precursor pulp is transported to spray-drier through volume pump and carries out spray drying granulation, obtain spherical precursor powder particle;
(7) place rotary kiln to carry out sintering precursor powder, naturally cool to room temperature and obtain product with protection of inert gas.
2. the method for claim 1 is characterized in that the lithium salts described in the step (1) is Quilonum Retard (Li
2CO
3); Source of iron is red iron oxide (Fe
2O
3), iron oxide black (Fe
3O
4), yellow oxide of iron (Fe
2O
3H
2O) a kind of in; Phosphoric acid is that massfraction is 75% or 85% industrial phosphoric acid.
3. the method for claim 1 is characterized in that organic carbon source described in the step (4) is a kind of in Vinylpyrrolidone polymer (PVP), Zulkovsky starch, the Z 150PH (PVA); Inorganic carbon source is a kind of in acetylene black, the superconduction carbon black.
4. the method for claim 1 is characterized in that grinding condition is 100～400 rev/mins of revolutions in the step (5), and milling time is 2～6h.
5. the method for claim 1 is characterized in that spray inlet temperature is 240～350 ℃ in the step (6), and temperature out is 100～150 ℃, and input speed is 0.2～1L/min.
6. the method for claim 1 is characterized in that the rare gas element that adopts is high pure nitrogen or argon gas in the step (7), and ventilation flow rate is 1～4L/min, and temperature rise rate is 2～6 ℃/min, and sintering temperature is 600～750 ℃, and the constant temperature sintering time is 2～8h.
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| CN103367750A (en) * | 2012-03-30 | 2013-10-23 | 北京当升材料科技股份有限公司 | Preparation method of carbon-coated lithium iron phosphate material |
| CN103247804A (en) * | 2013-04-27 | 2013-08-14 | 湖南大学 | Preparation method of nanocarbon coated lithium iron phosphate |
| CN103553016B (en) * | 2013-10-25 | 2015-09-02 | 浙江南都电源动力股份有限公司 | A kind of lithium iron phosphate preparation method that is compound phosphorus source with polyphosphoric acid and primary ammonium phosphate |
| CN109904431A (en) * | 2019-03-14 | 2019-06-18 | 浙江瑞邦科技有限公司 | A kind of method of the modified cell positive material of mixed carbon source |
| CN110970618A (en) * | 2019-12-20 | 2020-04-07 | 贝特瑞（天津）纳米材料制造有限公司 | Preparation method of low-cost lithium iron phosphate composite material |
| CN111533108A (en) * | 2020-05-11 | 2020-08-14 | 蒋达金 | Method for preparing lithium cobalt phosphate by using waste lithium cobalt oxide |
| CN112028045A (en) * | 2020-09-07 | 2020-12-04 | 厦门厦钨新能源材料股份有限公司 | Conductive lithium iron phosphate and preparation method and application thereof |
| CN115196612B (en) * | 2022-09-01 | 2023-05-16 | 中国长江三峡集团有限公司 | Lithium iron phosphate positive electrode material, preparation method thereof and lithium ion battery positive electrode sheet |
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