CN101948102A - Preparation method of lithium iron phosphate positive electrode material - Google Patents
Preparation method of lithium iron phosphate positive electrode material Download PDFInfo
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- CN101948102A CN101948102A CN2010102930609A CN201010293060A CN101948102A CN 101948102 A CN101948102 A CN 101948102A CN 2010102930609 A CN2010102930609 A CN 2010102930609A CN 201010293060 A CN201010293060 A CN 201010293060A CN 101948102 A CN101948102 A CN 101948102A
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- iron phosphate
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a preparation method of a lithium iron phosphate positive electrode material. The method comprises the following steps: firstly weighting iron source, lithium source and phosphoric acid source to prepare solutions respectively; secondly mixing the three solutions to heat in the 100-120 DEG C of oil bath for 2-3 hours and ensure that dark green precipitate appears at the bottom; then filtering to separate and obtain nanoscale lithium iron phosphate primary particles; performing spray treatment to the lithium iron phosphate primary particles with a sprayer to obtain lithium iron phosphate secondary particles; and roasting the secondary particles at 500-800 DEG C for 5-8 hours, finally cooling the furnace to the room temperature to obtain the lithium iron phosphate positive electrode material.
Description
Technical field
The invention belongs to the preparation method of anode material for lithium-ion batteries technical field, particularly a kind of lithium iron phosphate positive material.
Background technology
Since the phase at the end of the nineties in last century, olivine-type LiFePO
4The research of positive electrode material causes numerous investigators' concern.Iron lithium phosphate has high theoretical capacity (170mAh/g), high working voltage (voltage platform about 3.5V), suitable mass density (3.64g/cm3), self-discharge lampet advantage, LiFePO under low current density
4In Li
+Almost can 100% embed/take off embedding, have extended cycle life, good cycle, memory-less effect, cheap, Heat stability is good, advantage such as environmentally friendly, be expected to become anode material for lithium-ion batteries of new generation.
The lithium ion battery quilt widely should be in making various electronicss, as notebook computer, lithium-base battery, digital camera, portable lighting equipment etc.Simultaneously, it also is used to power tool, electric bicycle and electromobile.Along with the consumption gradually of world petroleum resource, and the society requirement on environmental protection is improved gradually, power truck has obtained unprecedented opportunity to develop.As electric vehicle power sources, is the direction of power truck development with lithium ion battery.
In lithium ion battery, positive electrode material occupies important status, and this also is the emphasis of current lithium ion battery development.Traditional positive electrode material has: 1) cobalt acid lithium, its advantage are that energy height, good cycle, preparation are simple, technology maturation, Technological adaptability are good, and shortcoming is that price is too high, poor safety performance; 2) lithium manganate low price, but cycle performance and high-temperature behavior have much room for improvement./ 2nd materials that partly substitute cobalt with manganese and nickel are materials of acid energy of lithium manganate and cobalt and price compromise, and its cobalt contents can not fall very lowly, and the price of nickel is also very high, so its cost performance is undesirable.And the iron lithium phosphate cost is low, aboundresources, good cycle, is the ideal anode material for lithium-ion batteries.
Yet, LiFePO
4Positive electrode material also has very big defective, and its ion and electronic conductivity are not good, causes the charge-discharge magnification performance not good.This shortcoming has greatly influenced LiFePO
4Replace LiCoO
2Become anode material for lithium-ion batteries of new generation.LiFePO
4This defective of positive electrode material can overcome by the preparation ultra-fine grain; By increasing the material specific surface area, promote being in contact with one another or the coated with conductive charcoal between the particle, can improve LiFePO
4The conductivity of positive electrode material.
But new problem has thereupon appearred: along with the increase of specific surface area again, the amount that is coated with required caking agent and solvent also increases greatly, bring very big difficulty for the coating of pole piece, and after pole piece is prepared into electric core or battery, be easy to occur falling the material phenomenon.At present, LiFePO 4 material ubiquity coating difficult problem.
The J.B.Goodenough of U.S. Texas university in 1999 etc. discloses a kind of lithium battery anode LiFePO 4 material, and its current discharge is: 0.05mA/cm
2, capacity is 110mAh/g, and it reaches the theoretical capacity of 170mAh/g far away, and reason is: iron lithium phosphate electronics and ionic specific conductivity are low.Be head it off, people such as N.Ravet and M.Armand adopt that charcoal coats, metal-doped and phosphate potential alternate method improves the iron lithium phosphate specific conductivity greatly.The US2004/005265A1 of the Yet-Ming Chiang of Massachusetts Institute Technology in 2002 etc. application, its metal ion more than+2 of mixing in the lithium position to be increasing substantially electronic conductivity, thereby improved the multiplying power property of iron lithium phosphate.More than provide fundamental basis for the application in the power lithium-ion battery.
Sony company adopts Li
3PO and Fe
3(PO)
2-8H
20Be raw material, add amorphous carbon black or carbon precursor ball milling together, in preparing iron lithium phosphate below 6000 ℃.This method biggest advantage is to have only water to discharge in the tail gas, the productive rate height, and shortcoming is: need preparation ferrous phosphate presoma earlier, and if other elements that mix need to add in addition in proportion the balance that phosphoric acid could keep each element metering ratio.
Based on pyrocarbon thermal reduction synthetic technology, the cheap ferric iron sources such as ferric oxide of U.S. Valence Technology Inc. company, it is excessive to add weight ratio 100% when starting material mix, and is prepared iron lithium phosphate in ferric iron by the amorphous carbon black that carbon black is reduced to ferrous consumption.
Prior art generally adopts solid phase method or wet chemical method to prepare positive active material LiFePO
4, for example Chinese patent CN discloses a kind of iron lithium phosphate (LiFePO for 1401559A number
4) the preparation method, this method is the even back high-temperature calcination of lithium salts, ferrous salt and phosphoric acid salt ground and mixed, the calcining back that finishes adds the conductive agent ground and mixed and makes iron lithium phosphate.But when adopting solid phase method, various solids components are difficult to thorough mixing, therefore in the iron phosphate lithium positive pole active substance that obtains various compositions especially the conductive agent dispersion is inhomogeneous, directly influence the electroconductibility of positive active material.
Summary of the invention
It is abundant, cheap that technical problem to be solved by this invention provides a kind of raw material sources, synthesis technique is simple, safe and reliable, production cost is low, productive rate is high, non-environmental-pollution, product have the preparation method of the lithium iron phosphate positive material of better chemical property.
For solving above technical problem, the invention provides a kind of preparation method of lithium iron phosphate positive material, may further comprise the steps:
(1) preparation nano-scale lithium iron phosphate primary particle
According to mol ratio is respectively to take by weighing source of iron, lithium source and source of phosphoric acid at 1: 1: 1, and be mixed with the solution of 0.002mol/ml respectively, then three solution being mixed the back heated in 100～120 ℃ oil bath 2～3 hours, blackish green precipitation appears until the bottom, last filtering separation promptly gets the nano-scale lithium iron phosphate primary particle;
(2): preparation iron lithium phosphate second particle
The iron lithium phosphate primary particle that step (1) obtains is sprayed with spraying machine, and the inlet temperature of spraying is 100～150 ℃, and 50～80 ℃ of temperature outs after spraying is finished, promptly get the iron lithium phosphate second particle;
(3) roasting
During roasting, under the condition of room temperature, kept 5～8 hours after being increased to 500～800 ℃ with the temperature rise rate of 2～3 ℃/min in box-type furnace, last stove is chilled to room temperature, promptly gets lithium iron phosphate positive material, wherein during roasting, is doped with excessive reduction carbon.
As the preferred embodiments of the present invention, described lithium source is selected from Quilonum Retard, lithium hydroxide or lithium fluoride;
As the preferred embodiments of the present invention, described source of iron is selected from Iron diacetate, iron nitrate or ironic hydroxide;
As the preferred embodiments of the present invention, described source of phosphoric acid is selected from monometallic, primary ammonium phosphate or triammonium phosphate;
As the preferred embodiments of the present invention, in the described step (1), source of iron, lithium source and source of phosphoric acid before the oil bath heating, are regulated PH and are 7 after being mixed with solution;
As the preferred embodiments of the present invention, in the process of described oil bath heating, keep mechanical stirring;
As the preferred embodiments of the present invention, described source of iron, lithium source and source of phosphoric acid during mixing, join in the container respectively according to source of iron, lithium source and source of phosphoric acid after being mixed with solution smoothly;
As the preferred embodiments of the present invention, the adding speed in described lithium source is less than the adding speed of source of iron and source of phosphoric acid;
As the preferred embodiments of the present invention, described roasting is carried out in air atmosphere.
Compared with prior art, the preparation method of lithium iron phosphate positive material of the present invention has the following advantages at least: various raw materials fully contact in the coprecipitation method, and can obtain nano level deposit seeds in solution.
Even by the product cut size that the present invention makes, and surface bag carbon, therefore, conductivity is good.
Description of drawings
Fig. 1 is sem photograph (SEM) figure according to the iron lithium phosphate of example 1 preparation;
Fig. 2 is sem photograph (SEM) figure according to the iron lithium phosphate of example 2 preparations;
Fig. 3 is sem photograph (SEM) figure according to the iron lithium phosphate of example 3 preparations.
Embodiment
Embodiment one
1. prepare the nano-scale lithium iron phosphate primary particle
According to mol ratio is respectively to take by weighing primary ammonium phosphate, iron nitrate and Quilonum Retard at 1: 1: 1, is dissolved in respectively in the 500ml water then, utilizes whipping appts to make it abundant dissolving, approximately stirs 10 minutes, and material dissolves fully, forms the solution of transparent even attitude respectively; Then utilize the pH tester to measure the potential of hydrogen of this solution, making the pH value is 7, then, under the effect of mechanical stirring slurry (rotating speed=300 rev/min), in whipping process, pour these three kinds of solution into big round bottom flask successively, heating is 2.5 hours in 120 ℃ oil bath, wherein Quilonum Retard is poured into and to pour speed into slower at last, treat that oil bath heating finishes the blackish green precipitation of appearance in the flask of back, repeatedly after the filtering separation, promptly get the nano-scale lithium iron phosphate primary particle at last;
2. prepare the iron lithium phosphate second particle
The iron lithium phosphate primary particle that step 1 is obtained uses spraying machine to spray, and the inlet temperature during spraying is 120 ℃, and 70 ℃ of temperature outs after spraying is finished, promptly get the iron lithium phosphate second particle, and it is shaped as sphere, and size is even, and fine powder content is low;
3. roasting
The iron lithium phosphate second particle that step 2 is formed is passed to and carries out roasting in the box-type furnace, wherein be placed with excessive reduction carbon in the box-type furnace, keep temperature 6.5h after being warmed up to 800 ℃ with the speed of 2 ℃/min then, last stove is as cold as room temperature, promptly gets the spheric lithium iron phosphate positive material.
Seeing also shown in Figure 1ly, is that as we know from the figure, particle diameter is even according to sem photograph (SEM) figure of the iron lithium phosphate of embodiment 1 preparation, and impurity is few, and spheroidal particle has so effectively increased tap density and gram volume.
Embodiment two
1. prepare the nano-scale lithium iron phosphate primary particle
According to mol ratio is respectively to take by weighing monometallic, Iron diacetate and lithium fluoride at 1: 1: 1, is dissolved in respectively in the 500ml water then, utilizes whipping appts to make it abundant dissolving, approximately stirs 10 minutes, and material dissolves fully, forms the solution of transparent even attitude respectively; Then utilize the pH tester to measure the potential of hydrogen of this solution, making the pH value is 7, then, under the effect of mechanical stirring slurry (rotating speed=400 rev/min), in whipping process, pour these three kinds of solution into big round bottom flask successively, heating is 3 hours in 120 ℃ oil bath, wherein lithium fluoride is poured into and to pour speed into slower at last, treat that oil bath heating finishes the blackish green precipitation of appearance in the flask of back, filtering separation is shouted repeatedly at last, promptly gets the nano-scale lithium iron phosphate primary particle;
2. prepare the iron lithium phosphate second particle
The iron lithium phosphate primary particle that step 1 is obtained uses spraying machine to spray, and the inlet temperature during spraying is 130 ℃, and 60 ℃ of temperature outs after spraying is finished, promptly get the iron lithium phosphate second particle, and it is shaped as sphere, and size is even, and fine powder content is low;
3. sintering
The iron lithium phosphate second particle that step 2 is formed is passed to and carries out roasting in the box-type furnace, wherein be placed with excessive reduction carbon in the box-type furnace, keep temperature 5h after being warmed up to 750 ℃ with the speed of 3 ℃/min then, last stove is as cold as room temperature, promptly gets the spheric lithium iron phosphate positive material.
Seeing also shown in Figure 2ly, is that as we know from the figure, particle diameter is even according to sem photograph (SEM) figure of the iron lithium phosphate of embodiment 2 preparation, and impurity is few, and spheroidal particle has so effectively increased tap density and gram volume.
Embodiment three
1. prepare the nano-scale lithium iron phosphate primary particle
According to mol ratio is respectively to take by weighing phosphoric acid triamine, ironic hydroxide and lithium hydroxide at 1: 1: 1, is dissolved in respectively in the 500ml water then, utilizes whipping appts to make it abundant dissolving, approximately stirs 10 minutes, and material dissolves fully, forms the solution of transparent even attitude respectively; Then utilize the pH tester to measure the potential of hydrogen of this solution, making the pH value is 7, then, under the effect of mechanical stirring slurry (rotating speed=300 rev/min), in whipping process, pour these three kinds of solution into big round bottom flask successively, heating is 3 hours in 115 ℃ oil bath, wherein lithium hydroxide is poured into and to pour speed into slower at last, treat that oil bath heating finishes the blackish green precipitation of appearance in the flask of back, filtering separation is shouted repeatedly at last, promptly gets the nano-scale lithium iron phosphate primary particle;
2. prepare the iron lithium phosphate second particle
The iron lithium phosphate primary particle that step 1 is obtained uses spraying machine to spray, and the inlet temperature during spraying is 110 ℃, and 65 ℃ of temperature outs after spraying is finished, promptly get the iron lithium phosphate second particle, and it is shaped as sphere, and size is even, and fine powder content is low;
3. sintering
The iron lithium phosphate second particle that step 2 is formed is passed to and carries out roasting in the box-type furnace, wherein be placed with excessive reduction carbon in the box-type furnace, keep temperature 6h after being warmed up to 700 ℃ with the speed of 3 ℃/min then, last stove is as cold as room temperature, promptly gets the spheric lithium iron phosphate positive material.
Seeing also shown in Figure 3ly, is that as we know from the figure, particle diameter is even according to sem photograph (SEM) figure of the iron lithium phosphate of embodiment 3 preparation, and impurity is few, and spheroidal particle has so effectively increased tap density and gram volume.
The above only is one embodiment of the present invention, it or not whole or unique embodiment, the conversion of any equivalence that those of ordinary skills take technical solution of the present invention by reading specification sheets of the present invention is claim of the present invention and contains.
Claims (9)
1. the preparation method of a lithium iron phosphate positive material may further comprise the steps:
(1) preparation nano-scale lithium iron phosphate primary particle
According to mol ratio is respectively to take by weighing source of iron, lithium source and source of phosphoric acid at 1: 1: 1, and be mixed with the solution of 0.002mol/ml respectively, then three solution being mixed the back heated in 100～120 ℃ oil bath 2～3 hours, blackish green precipitation appears until the bottom, last filtering separation promptly gets the nano-scale lithium iron phosphate primary particle;
(2) preparation iron lithium phosphate second particle
The iron lithium phosphate primary particle that step (1) obtains is sprayed with spraying machine, and the inlet temperature of spraying is 100～150 ℃, and 50～80 ℃ of temperature outs after spraying is finished, promptly get the iron lithium phosphate second particle;
(3) roasting
During roasting, under the condition of room temperature, kept 5～8 hours after being increased to 500～800 ℃ with the temperature rise rate of 2～3 ℃/min in box-type furnace, last stove is chilled to room temperature, promptly gets lithium iron phosphate positive material, wherein during roasting, is doped with excessive reduction carbon.
2. the preparation method of lithium iron phosphate positive material as claimed in claim 1, it is characterized in that: described lithium source is selected from Quilonum Retard, lithium hydroxide or lithium fluoride.
3. the preparation method of lithium iron phosphate positive material as claimed in claim 2, it is characterized in that: described source of iron is selected from Iron diacetate, iron nitrate or ironic hydroxide.
4. the preparation method of lithium iron phosphate positive material as claimed in claim 3, it is characterized in that: described source of phosphoric acid is selected from monometallic, primary ammonium phosphate or triammonium phosphate.
5. as the preparation method of claim 1 or 4 described lithium iron phosphate positive materials, it is characterized in that: in the described step (1), source of iron, lithium source and source of phosphoric acid are after being mixed with solution, and before the oil bath heating, regulating PH is 7.
6. the preparation method of lithium iron phosphate positive material as claimed in claim 1 is characterized in that: in the process of described oil bath heating, keep mechanical stirring.
7. the preparation method of lithium iron phosphate positive material as claimed in claim 1, it is characterized in that: described source of iron, lithium source and source of phosphoric acid are after being mixed with solution, during mixing, according to joining in the container respectively smoothly of source of iron, lithium source and source of phosphoric acid.
8. the preparation method of lithium iron phosphate positive material as claimed in claim 7, it is characterized in that: the adding speed in described lithium source is less than the adding speed of source of iron and source of phosphoric acid.
9. the preparation method of lithium iron phosphate positive material as claimed in claim 8, it is characterized in that: described roasting is carried out in air atmosphere.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102299319A (en) * | 2011-07-20 | 2011-12-28 | 彩虹集团公司 | Preparation method of lithium ion battery anode material LiFePO4 |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1298621C (en) * | 2004-12-17 | 2007-02-07 | 清华大学 | Method for preparing Li Fe PO4 ball shape powder |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1298621C (en) * | 2004-12-17 | 2007-02-07 | 清华大学 | Method for preparing Li Fe PO4 ball shape powder |
Non-Patent Citations (2)
| Title |
|---|
| 《化工新型材料》 20070930 李庆余等 纳米LiFePO4/C复合正极材料的制备及其性能研究 第3-5页 1-9 第35卷, 第9期 2 * |
| 《材料科学与工程学报》 20080630 李昕洋等 化学沉淀法制备锂离子电池正极材料LiFePO4 第385-389页 1-9 第26卷, 第3期 2 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102299319A (en) * | 2011-07-20 | 2011-12-28 | 彩虹集团公司 | Preparation method of lithium ion battery anode material LiFePO4 |
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Application publication date: 20110119 |