CN103022495A - Preparation method of high-electrical conductivity lithium iron phosphate - Google Patents
Preparation method of high-electrical conductivity lithium iron phosphate Download PDFInfo
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- CN103022495A CN103022495A CN2012105329247A CN201210532924A CN103022495A CN 103022495 A CN103022495 A CN 103022495A CN 2012105329247 A CN2012105329247 A CN 2012105329247A CN 201210532924 A CN201210532924 A CN 201210532924A CN 103022495 A CN103022495 A CN 103022495A
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- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to preparation of an anode active material for a lithium ion battery, and particularly relates to a preparation method of a high-electrical conductivity lithium iron phosphate. The preparation method is characterized by comprising the following steps of: (1) preparing LiFePO4; (2) making the LiFePO4 into spherical nanometer particles through spray drying, mixing the spherical nanometer particles with citric acid and glycol, and heating the mixed material in a rotary furnace; (3) heating to 130-140 DEG C, and preserving for 5-7 hours; (4) continuously heating the obtained material to 300 DEG C to 330 DEG C for carrying out thermal treatment for 2-3 hours, then heating to 400-450 DEG C, and preserving the temperature for 7-8 hours in air; and (5) preserving the temperature of 680 DEG C to 700 DEG C for 5-7 hours under the protective atmosphere of nitrogen, and the cooling. Due to the adoption of the preparation method, the electrical conductivity performance of the lithium iron phosphate anode material is increased on the basis of increasing the specific surface area of the lithium iron phosphate anode material, and carbon coating and carburization are completed at a time.
Description
Technical field
The present invention relates to the preparation of anode active material of lithium ion battery, especially a kind of preparation method of high conduction performance LiFePO 4.
Background technology
Lithium ion battery is the new generation of green high-energy battery, the advantage such as have that voltage height, energy density are large, good cycle, self discharge are little, memory-less effect, operating temperature range are wide, be widely used in portable electric appts, such as mobile phone, notebook computer, digital camera, MP3, MP4 etc., also have a good application prospect in electric automobile, lithium ion battery has good its development.
LiFePO
4It is a kind of Olivine-type Cathode Material in Li-ion Batteries that has just grown up in recent years, have security performance good, have extended cycle life, the advantage such as environmental friendliness, low price, lithium rechargeable battery is used widely in various portable type electronic products and communication tool in recent years, and progressively is developed as the electrical source of power of electric automobile.The development of this kind new electrode materials is most crucial.
People find LiFePO by deep research
4The characteristics of the structure of self and charge and discharge process thereof cause Li
+At LiFePO
4Diffusion rate in the particle is very low, and this has limited LiFePO greatly
4Chemical property.From this angle, LiFePO
4The particle diameter of particle will produce larger impact to electrode capacity.Particle radius is larger, Li
+The solid-state diffusion distance longer, Li
+Embedding deviate from just more difficult, LiFePO
4Capacity performance just more be restricted.Therefore, Effective Regulation LiFePO
4Particle size be to improve LiFePO
4One of method of middle lithium ion diffusivity.The present invention utilizes liquid phase method to synthesize LiFePO
4Particle diameter less, add a certain amount of organic substance and effectively controlled its LiFePO
4Growth and the size of particle diameter.
Along with deepening continuously of research, people change its performance by different technique and method, improve its conductivity and electron mobility, and then change its charge/discharge capacity and cyclical stability, also improve its charge-discharge magnification.Mainly be to realize by bag carbon and doping at present.But traditional ginseng carbon method is subject to certain restrictions the conductance raising of LiFePO 4 material, when making battery, also need to add conductive agent, this patent can disposable realization bag carbon and ginseng carbon, when making battery pole piece, do not need to add again conductive agent, and the more traditional bag carbon of conductance and ginseng carbon just improves greatly, can improve greatly the high rate during charging-discharging of ferric phosphate lithium cell.
Summary of the invention
The preparation method who the purpose of this invention is to provide a kind of high conduction performance LiFePO 4 can on the basis of improving the lithium iron phosphate positive material specific area, improve the electric conductivity of lithium iron phosphate positive material simultaneously.
A kind of preparation method of high conduction performance LiFePO 4, its special feature is, comprises the steps:
(1) take iron containing compounds, LiOH and the mass fraction phosphoric acid H as 50%～70%
3PO
4Be raw material, make LiFePO
4
(2) will be with the LiFePO after the deionized water washing
4Be prepared into spherical nano particle by spray drying, then with LiFePO
4Nano particle and citric acid and glycol are by (1 ((～200): (15～30): the mass ratio of (15～30) mixes, and then mixed material is heated to 50 ℃～60 ℃ and continuous stirring 3～5 hours in rotary furnace;
(3) temperature is heated to 130 ℃～140 ℃, keeps 5～7 hours to promote the carrying out of polymerization reaction, make citric acid and glycol in mixed material, form gel pack and overlay on the LiFePO 4 particle surface;
(4) material that obtains is continued to be heated to 300 ℃～330 ℃ heat treatment 2h～3h and become to burn sprills, this powder is heated to 400 ℃～450 ℃ again and in air, is incubated 7～8 hours;
(5) with the iron phosphate powder behind the above-mentioned sintering bag carbon under nitrogen protection atmosphere, made LiFePO4 carry out recrystallization in 5～7 hours 680 ℃～700 ℃ insulations again, then be cooled to and namely obtain the bag carbon LiFePO4 that formed by carbon nano-tube after the room temperature.
Wherein iron containing compounds is FeSO
4, FeCl
2Or FeNO
3
In the step (1) by Li:Fe:P=(1.0～1.1): (9.95～1.0): it is 50%～70% phosphoric acid H that 1 mol ratio takes by weighing a certain amount of iron containing compounds, LiOH and mass fraction
3PO
4, then first with H
3PO
4Mix with iron containing compounds, and in mixed solution, add the DMSO account for total liquor capacity 1/10～2/10 and the ascorbic acid that accounts for iron containing compounds weight 0.5-1%, add again LiOH and stir 30～50min, then mixed liquor is incubated 5h～7h at 110 ℃～130 ℃, Separation of Solid and Liquid is carried out in filtration, obtains LiFePO
4
Through evidence, after adopting the inventive method, on the basis of improving the lithium iron phosphate positive material specific area, improved simultaneously the electric conductivity of lithium iron phosphate positive material, and realize simultaneously bag carbon and carburizing is disposable finishes, thereby improve the high rate performance of its material, reduce the internal resistance of battery, improve the high rate during charging-discharging of ferric phosphate lithium cell and the capacity of battery.
Description of drawings
Fig. 1 is the LiFePO4 SEM figure of 20000 times of amplifications behind the carbon nano-tube bag carbon of the inventive method preparation;
Fig. 2 is the LiFePO4 SEM figure of 50000 times of amplifications behind the carbon nano-tube bag carbon of the inventive method preparation;
Fig. 3 is the curve chart with the 10C rate charge-discharge for the button cell electric performance test that the lithium iron phosphate positive material by embodiment 1 preparation prepares, and wherein charging and discharging capacity is respectively 157mAh/g and 141mAh/g.
Embodiment
Adopting the grain diameter of the inventive method preparation is 500-800nm, median particle diameter d
50Be about 600nm; Distribute (d from particle diameter
90-d
10)/d
50Be about 0.5, the particle diameter narrow distribution.The resistivity of product between the 100 Ω cm, is respectively 157mAh/g and 141mAh/g with the specific capacity of 10C rate charge-discharge at 10 Ω cm, and its charging and discharging curve as shown in Figure 2.
Embodiment 1:
1) mol ratio by Li:Fe:P=1.05:9.95:1 takes by weighing FeSO
47H
2O, LiOH and mass fraction are 60% phosphoric acid H
3PO
4, its process is first with H
3PO
4And FeSO
4Solution mixes, and adds 1/10 the DMSO (dimethyl sulfoxide (DMSO)) that accounts for total liquor capacity and account for FeSO in mixed solution
47H
2The ascorbic acid of O weight 0.5% adds LiOH again and stirs 30min, then this mixed liquor is carried out Separation of Solid and Liquid 120 ℃ of insulation 5h, filtrations, generates LiFePO
4
Wherein adding ascorbic acid is in order to prevent Fe
2+Oxidized, adding DMSO is in order to control LiFePO
4Synthesis rate, and control crystal grain size.
2) will be with the LiFePO after the deionized water washing
4Be prepared into spherical nano particle by spray drying, then with LiFePO
4With citric acid and glycol in mass ratio for the mass ratio of 100:15:15 mixes, with mixed material 50 ℃ of agitating heating 3 hours in rotary furnace, this moment, mixture had certain gloss.
3) temperature is heated to 135 ℃, keeps promoting polymerization reaction in 5 hours, the more and more thickness that material becomes in this process makes citric acid and glycol form gel pack in mixed material and overlays on the LiFePO 4 particle surface.
4) material that certain viscosity is arranged of the brown that obtains is continued to be heated to 300 ℃ of heat treatment 2.5h and become to burn sprills, more this powder is heated to 400 ℃ of insulations 8 hours in air;
At this moment in iron phosphate powder, produce a certain amount of multi-walled carbon nano-tubes (diameter 5-20 nanometer, about 1 micron of length), coated one deck carbon on the LiFePO4 surface simultaneously.
5) with the iron phosphate powder behind the above-mentioned sintering bag carbon under nitrogen protection atmosphere, 700 ℃ of insulations 5 hours, LiFePO4 carried out recrystallization again, was cooled to and just obtained the bag carbon LiFePO4 that carbon nano-tube forms after the room temperature.
Embodiment 2:
1) mol ratio by Li:Fe:P=1.0:1.0:1.0 takes by weighing a certain amount of FeCl
2, LiOH and mass fraction be 60% phosphoric acid H
3PO
4, its process is first with H
3PO
4And FeCl
2Solution mixes, and adds 2/10 the DMSO that accounts for total liquor capacity and account for FeCl in mixed solution
20.7% ascorbic acid of weight adds LiOH again and stirs 40min, then this mixed liquor at 120 ℃ of insulation 6h, filter and carry out Separation of Solid and Liquid, generate LiFePO
4
Wherein adding ascorbic acid is in order to prevent Fe
2+Be oxidized to Fe
3+, adding DMSO is in order to control LiFePO
4Synthesis rate, and control crystal grain size.
2) will be with the LiFePO after the deionized water washing
4Be prepared into spherical nano particle by spray drying, then with LiFePO
4With citric acid and glycol in mass ratio for the mass ratio of 150:20:20 mixes, mixed material is heated to 55 ℃ and constantly stirred 3.5 hours in rotary furnace, this moment, mixture had certain glossiness.
3) temperature is heated to 135 ℃, keeps promoting polymerization reaction in 6 hours, the more and more thickness that material becomes in this process makes citric acid and glycol form gel pack in mixed material and overlays on the LiFePO 4 particle surface.
4) material that certain viscosity is arranged of the brown that forms is above continued to be heated to 310 ℃ of heat treatment 3h and become to burn sprills, more this powder is heated to 450 ℃ of insulations 7 hours in air.At this moment in iron phosphate powder, produce a certain amount of multi-walled carbon nano-tubes (diameter 5-20 nanometer, about 1 micron of length), coated one deck carbon on the LiFePO4 surface simultaneously.
5) with the iron phosphate powder behind the above-mentioned sintering bag carbon under the protective atmosphere of nitrogen again 690 ℃ of insulations 6 hours, LiFePO4 carries out recrystallization, is cooled to and just obtains the bag carbon LiFePO4 that carbon nano-tube forms after the room temperature.
Embodiment 3:
1) mol ratio by Li:Fe:P=1.1:9.9:1 takes by weighing a certain amount of Fe (NO
3)
2, LiOH and mass fraction be 70% phosphoric acid H
3PO
4, its process is first with H
3PO
4And Fe (NO
3)
2Solution mixes, and adds 1/10 the DMSO that accounts for total liquor capacity and account for Fe (NO in mixed solution
3)
21% ascorbic acid of weight adds LiOH again and stirs 50min, then this mixed liquor at 120 ℃ of insulation 7h, filter and carry out Separation of Solid and Liquid, generate LiFePO
4
Wherein adding ascorbic acid is in order to prevent Fe
2+Be oxidized to Fe
3+, adding DMSO is in order to control LiFePO
4Synthesis rate, and control crystal grain size.
2) will be with the LiFePO after the deionized water washing
4Be prepared into spherical nano particle by spray drying, then with LiFePO
4With citric acid and glycol in mass ratio for the mass ratio of 150:15:15 mixes, mixed material is heated to 55 ℃ and constantly stirred 3 hours in rotary furnace, this moment, mixture had certain glossiness.
3) temperature is heated to 140 ℃, keeps promoting polymerization reaction in 5 hours, the more and more thickness that material becomes in this process makes citric acid and glycol form gel pack in mixed material and overlays on the LiFePO 4 particle surface.
4) material that certain viscosity is arranged of the brown that forms is above continued to be heated to 310 ℃ of heat treatment 3.0h and become to burn sprills, more this powder is heated to 430 ℃ of insulations 7 hours in air.At this moment in iron phosphate powder, produce a certain amount of multi-walled carbon nano-tubes (diameter 5-20 nanometer, about 1 micron of length), coated one deck carbon on the LiFePO4 surface simultaneously.
5) with the iron phosphate powder behind the above-mentioned sintering bag carbon under the protective atmosphere of nitrogen again 700 ℃ of insulations 6 hours, LiFePO4 carries out recrystallization, is cooled to and just obtains the bag carbon LiFePO4 that carbon nano-tube forms after the room temperature.
Claims (3)
1. the preparation method of a high conduction performance LiFePO 4 is characterized in that, comprises the steps:
(1) take iron containing compounds, LiOH and the mass fraction phosphoric acid H as 50%～70%
3PO
4Be raw material, make LiFePO
4
(2) will be with the LiFePO after the deionized water washing
4Be prepared into spherical nano particle by spray drying, then with LiFePO
4Nano particle and citric acid and glycol are by (100～200): (15～30): the mass ratio of (15～30) mixes, and then mixed material is heated to 50 ℃～60 ℃ and continuous stirring 3～5 hours in rotary furnace;
(3) temperature is heated to 130 ℃～140 ℃, keeps 5～7 hours to promote the carrying out of polymerization reaction, make citric acid and glycol in mixed material, form gel pack and overlay on the LiFePO 4 particle surface;
(4) material that obtains is continued to be heated to 300 ℃～330 ℃ heat treatment 2h～3h and become to burn sprills, this powder is heated to 400 ℃～450 ℃ again and in air, is incubated 7～8 hours;
(5) with the iron phosphate powder behind the above-mentioned sintering bag carbon under nitrogen protection atmosphere, made LiFePO4 carry out recrystallization in 5～7 hours 680 ℃～700 ℃ insulations again, then be cooled to and namely obtain the bag carbon LiFePO4 that formed by carbon nano-tube after the room temperature.
2. the preparation method of a kind of high conduction performance LiFePO 4 as claimed in claim 1, it is characterized in that: wherein iron containing compounds is FeSO
4, FeCl
2Or FeNO
3
3. the preparation method of a kind of high conduction performance LiFePO 4 as claimed in claim 1 is characterized in that: in the step (1) by Li:Fe:P=(1.0～1.1): (9.95～1.0): it is 50%～70% phosphoric acid H that 1 mol ratio takes by weighing a certain amount of iron containing compounds, LiOH and mass fraction
3PO
4, then first with H
3PO
4Mix with iron containing compounds, and in mixed solution, add the DMSO account for total liquor capacity 1/10～2/10 and the ascorbic acid that accounts for iron containing compounds weight 0.5-1%, add again LiOH and stir 30～50min, then mixed liquor is incubated 5h～7h at 110 ℃～130 ℃, Separation of Solid and Liquid is carried out in filtration, obtains LiFePO
4
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105226280A (en) * | 2015-10-20 | 2016-01-06 | 四川科能锂电有限公司 | The preparation technology of LiFePO4 |
Citations (5)
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|---|---|---|---|---|
| CN1889290A (en) * | 2005-06-28 | 2007-01-03 | 中国科学院物理研究所 | Olivine carbon bobbles composite material and use thereof |
| WO2009061845A1 (en) * | 2007-11-05 | 2009-05-14 | Board Of Regents, The University Of Texas System | Rapid microwave-solvothermal synthesis and surface modification of nanostructured phospho-olivine cathodes for lithium ion batteries |
| CN101572301A (en) * | 2008-10-30 | 2009-11-04 | 喻维杰 | Method for preparing lithium iron phosphate material and cladding the material with carbon |
| CN102024945A (en) * | 2010-11-05 | 2011-04-20 | 华南理工大学 | Method for preparing carbon-coated lithium iron phosphate anode material of lithium ion battery |
| US20110104551A1 (en) * | 2009-11-05 | 2011-05-05 | Uchicago Argonne, Llc | Nanotube composite anode materials suitable for lithium ion battery applications |
-
2012
- 2012-12-11 CN CN2012105329247A patent/CN103022495A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1889290A (en) * | 2005-06-28 | 2007-01-03 | 中国科学院物理研究所 | Olivine carbon bobbles composite material and use thereof |
| WO2009061845A1 (en) * | 2007-11-05 | 2009-05-14 | Board Of Regents, The University Of Texas System | Rapid microwave-solvothermal synthesis and surface modification of nanostructured phospho-olivine cathodes for lithium ion batteries |
| CN101572301A (en) * | 2008-10-30 | 2009-11-04 | 喻维杰 | Method for preparing lithium iron phosphate material and cladding the material with carbon |
| US20110104551A1 (en) * | 2009-11-05 | 2011-05-05 | Uchicago Argonne, Llc | Nanotube composite anode materials suitable for lithium ion battery applications |
| CN102024945A (en) * | 2010-11-05 | 2011-04-20 | 华南理工大学 | Method for preparing carbon-coated lithium iron phosphate anode material of lithium ion battery |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105226280A (en) * | 2015-10-20 | 2016-01-06 | 四川科能锂电有限公司 | The preparation technology of LiFePO4 |
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Effective date of abandoning: 20160928 |
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