CN102903920A - Method for preparing carbon-coated LiFePO4/C composite cathode material with two-step sintering method - Google Patents
Method for preparing carbon-coated LiFePO4/C composite cathode material with two-step sintering method Download PDFInfo
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- CN102903920A CN102903920A CN2012104167936A CN201210416793A CN102903920A CN 102903920 A CN102903920 A CN 102903920A CN 2012104167936 A CN2012104167936 A CN 2012104167936A CN 201210416793 A CN201210416793 A CN 201210416793A CN 102903920 A CN102903920 A CN 102903920A
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a method for preparing a carbon-coated LiFePO4/C composite cathode material with a two-step sintering method. The method comprises the following steps that ferric nitrate, diammonium hydrogen phosphate and aniline are prepared to obtain a FePO4/PANI precursor with in-situ polymerization, and then the precursor is mixed with lithium acetate and a carbon source (ascorbic acid) and then is fully ground; and in an atmosphere sintering furnace using argon as shielding gas, the fully ground mixture is presintered for 5 hours at 200-500 DEG C, the mixture after cooling is taken out to be further ground and then is sintered for 8-15 hours at high temperature of 600-1000 DEG C, and finally the LiFePO4/C composite cathode material is obtained. The method is simple and convenient, the cost is low, and the prepared material has an ideal electrochemical performance.
Description
Technical field
The present invention relates to a kind of two-step method that adopts and prepare the LiFePO that carbon coats
4The method of/C composite positive pole.
Background technology
Present portable equipment often uses the transiens metal oxide as energy storage material, but the exploitation of novel polyanion type compound positive electrode has promoted development and the progress of lithium-ion battery systems, novel polyanion type positive electrode will replace positive electrode in the past, become at present anode material for lithium-ion batteries commonly used.What research was more at present is that phosphoric acid is polyanion-LiMPO
4(M=Mn, Fe, Co, or Ni) positive electrode, and tool application scenario surely belong to lithium iron phosphate positive material.After the people such as Padhi in 1997 had found the hydrogen storage property of LiFePO 4 material, the positive electrode of phosphate system had just caused the concern of vast researcher.According to the academic report situation of the 16th that holds at Korea S's Jizhou Island 17-22 day in June, 2012 international lithium electricity meeting as can be known, have the lithium iron phosphate positive material of better fail safe and have than the high magnification characteristic and better the nano-electrode material of cycle performance still be study hotspot.Relevant report shows, commercial LiFePO4 has eight large advantages: 1, meet the national policy guiding; 2, the following battery developing direction of representative; 3, super large market capacity; 4, stable fast-developing; 5, application is extensive; 6, industrial profit is abundant; 7, certain technology barriers are arranged; 8, be not limited by the overseas market.Therefore, LiFePO4 has wide market prospects, becomes at present the most promising positive electrode.
Lithium iron phosphate positive material is paid close attention to widely because of its advantage, but is subject to certain restrictions because there is the low shortcoming of electronic conductivity in it simultaneously.Shortcoming for the LiFePO4 electronic conductivity adopts carbon to coat to improve more at present.The research that carbon coats mainly concentrates in the selection and coating technology of carbon-source cpd: the kind of carbon source is varied, and commonly used have glucose, sucrose; In addition, organic carboxyl acid class material also can be used as carbon source, such as salicylic acid, and citric acid, ascorbic acid etc.Except adopting the carbon source degraded to produce carbon, also can directly add conductive black in the carbon coating process.The formed carbon network configuration of coating process has stoped the reunion of material, reduced to a certain extent the particle size of material, therefore shorten the diffusion length of lithium ion in the charge and discharge process, thereby improved the lithium ion diffusion rate of material, improved the electronic conductivity of material.The present invention focuses on performance two-step method technology, namely cools off after low-temperature sintering, carries out high temperature sintering after further grinding; Low-temperature sintering processes that the impact produce is to make that material is mixed to get more evenly, particle diameter consistency more; In the high-temperature sintering process, organic carbon decomposes the carbon that produces can be coated on LiFePO more uniformly
4Material surface.Fact proved that the carbon covered effect is better than the one-step method sintering, material granule is more even, and chemical property also is due for promotion mutually.
Summary of the invention
The purpose of this invention is to provide a kind of two-step method and prepare the LiFePO that carbon coats
4The method of/C composite positive pole.
Concrete steps are:
(1) in-situ polymerization prepares presoma FePO
4/ PANI: by stoichiometric proportion, respectively with the Fe (NO of 0.0125mol-0.05mol
3)
3Be dissolved in the beaker 1 that 50ml-200ml distilled water is housed the (NH of 0.0125mol-0.05mol
4)
2HPO
4Be dissolved in the beaker 2 that 100ml-400ml distilled water is housed, and add 0.5ml-2ml aniline in beaker 2, magnetic agitation dropwise added solution in the beaker 1 in the beaker 2 after 5 minutes, added 0.5ml-2mlNH after dropwising again
3H
2O regulates the pH value; Magnetic agitation is after 12 hours at normal temperatures, and vacuum filtration, and clean 2-3 time with distilled water is transferred to that drying namely got corresponding FePO in 24 hours in 60 ℃ of baking ovens
4/ PANI presoma.
(2) LiFePO
4/ C composite manufacture: take by weighing 0.0125mol-0.05mol CH by stoichiometric proportion
3COOLi2H
2O is put in the agate mortar, adds the 10ml-20ml absolute ethyl alcohol and dissolves, and further grinds in the presoma adding mortar with step (1) preparation, grinds after 1 hour presoma and CH
3COOLi2H
2The 10%-30%(0.375g-4.500g of O quality summation) ascorbic acid adds together and grinds, and adds simultaneously the 15ml-30ml absolute ethyl alcohol, treats to stop to grind and being transferred to the sintering that carries out next stage in the porcelain boat when batch mixing in the mortar is worn into jelly; Under the protection of argon gas, sintering carries out in two steps, takes out after 200 ℃ of-500 ℃ of lower pre-burning 3-5 hours first and grinds, and the material after will grinding again namely gets LiFePO through 600 ℃-1000 ℃ after sintering 8-15 hour
4/ C composite material.
Described Fe (NO
3)
3,(NH
4)
2HPO
4,Aniline, NH
3H
2O, CH
3COOLi2H
2It is pure that O and ascorbic acid are analysis.
The present invention prepares the LiFePO4 that carbon coats/C positive electrode with two-step method, and ferric nitrate is source of iron, and diammonium hydrogen phosphate is the phosphorus source, lithium acetate is the lithium source, and ascorbic acid is carbon source, and cost of material is cheap, and do not produce toxic gas in the preparation process, environment is not polluted.The utilization of two-step sintering method makes the growth of particle in the material sintering process more even, and crystal property is better.Adopt the material of two-step sintering method preparation to have more satisfactory chemical property, such as higher charge/discharge capacity and good cycle performance are arranged.
Description of drawings
Fig. 1 is embodiment of the invention 1LiFePO
4The XRD figure of/C.
Fig. 2 is embodiment of the invention 1LiFePO
4The first charge-discharge curve of/C.
Fig. 3 is embodiment of the invention 1LiFePO
4The AC impedance figure of/C.
Embodiment
Embodiment 1:
(1) in-situ polymerization prepares presoma FePO
4/ PANI: by stoichiometric proportion, respectively with the Fe (NO of 0.025mol
3)
3Be dissolved in the beaker 1 that 100ml distilled water is housed the (NH of 0.025mol
4)
2HPO
4Be dissolved in the beaker 2 that 200ml distilled water is housed, add 1ml aniline in the beaker 2, magnetic agitation dropwise added solution in the beaker 1 in the beaker 2 after 5 minutes, added 1mlNH after dropwising
3H
2O regulates the pH value; Magnetic agitation is after 12 hours at normal temperatures, and vacuum filtration, and clean 2 times with distilled water is transferred in 60 ℃ of baking ovens dry 24 hours and namely gets corresponding FePO
4/ PANI presoma.
(2) LiFePO
4/ C composite manufacture: the CH that takes by weighing 0.025mol by stoichiometric proportion
3COOLi2H
2O is put in the agate mortar, adds the 15ml absolute ethyl alcohol and dissolves, and further grinds in the presoma adding mortar with step (1) preparation, grinds after 1 hour presoma and CH
3COOLi2H
2The 20%(1.5g of O quality summation) ascorbic acid adds together and grinds, and adds simultaneously the 20ml absolute ethyl alcohol, treats to stop to grind and being transferred to the sintering that carries out next stage in the porcelain boat when batch mixing in the mortar is worn into jelly; Under the protection of argon gas, sintering carries out in two steps, and first 350 ℃ of lower pre-burnings 5 hours, cooling is taken out and ground, and the material after will grinding again namely gets the LiFePO4/C composite material through 650 ℃ of sintering after 10 hours.
Described Fe (NO
3)
3,(NH
4)
2HPO
4,Aniline, NH
3H
2O, CH
3COOLi2H
2It is pure that O and ascorbic acid are analysis.
X-ray powder diffraction analytical technology (XRD) test result (see figure 1) shows that sample belongs to rhombic system, the Pnmb space group.Prepared sample preparation is become positive plate, then be assembled into CR2025 type button cell.
Concrete operations are as follows: according to active material: the respectively weighing of the ratio of acetylene black (C): PVDF=80:10:10, at first an amount of NMP (METHYLPYRROLIDONE) is added in the mortar, again load weighted PVDF (poly-inclined to one side tetrafluoroethene) is added and wherein grind, dissolve rear adding acetylene black fully and active material grinds together until PVDF, to be mixed relatively evenly after, roll into the thin slice of even thickness at aluminium foil with simple and easy applicator, place 120 ℃ of vacuum drying chambers after 4 hours, with its circular pole piece that is washed into diameter 14mm, the quality of each pole piece is between 2mg-4mg.Take metal lithium sheet as negative pole, the Celgard2300 microporous polypropylene membrane is barrier film, uses lmol/LiPF
6/ E C+DMC+EMC (l:l:l volume ratio) is electrolyte, be lower than 5% in relative humidity, oxygen forces down and be assembled into CR2025 type button cell in the glove box that is full of argon gas of 10ppm, place vacuum drying chamber after 12 hours until battery, can carry out charge-discharge test, ac impedance measurement (EIS), cyclic voltammetry (CV) to battery.Charging voltage 2.5V-4.2V, charge-discharge magnification are 0.2C, its first discharge capacity be 144.8 mAh/g, circulating still remains on 126.9mAh/g after 30 times, discharge curve and AC impedance curve are seen Fig. 2-3 first for they.As can be seen from the figure, synthetic sample has preferably discharge platform, and the battery impedance value is less.
Embodiment 2:
(1) in-situ polymerization prepares presoma FePO
4/ PANI: by stoichiometric proportion, respectively with the Fe (NO of 0.025mol
3)
3Be dissolved in the beaker 1 that 100ml distilled water is housed the (NH of 0.025mol
4)
2HPO
4Be dissolved in the beaker 2 that 200ml distilled water is housed, add 1ml aniline in the beaker 2, magnetic agitation dropwise added solution in the beaker 1 in the beaker 2 after 5 minutes, added 1mlNH after dropwising
3H
2O regulates the pH value; Magnetic agitation is after 12 hours at normal temperatures, and vacuum filtration, and clean 3 times with distilled water is transferred in 60 ℃ of baking ovens dry 24 hours and namely gets corresponding FePO
4/ PANI presoma.
(2) LiFePO
4/ C composite manufacture: the CH that takes by weighing 0.025mol by stoichiometric proportion
3COOLi2H
2O is put in the agate mortar, adds the 15ml absolute ethyl alcohol and dissolves, and further grinds in the presoma adding mortar with step (1) preparation, grinds after 1 hour presoma and CH
3COOLi2H
2The 20%(1.5g of O quality summation) ascorbic acid adds together and grinds, and adds simultaneously the 20ml absolute ethyl alcohol, treats to stop to grind and being transferred to the sintering that carries out next stage in the porcelain boat when batch mixing in the mortar is worn into jelly; Under the protection of argon gas, sintering carries out in two steps, and first 350 ℃ of lower pre-burnings 3 hours, cooling is taken out and ground, and the material after will grinding again namely gets LiFePO through 750 ℃ of sintering after 10 hours
4/ C composite material.
Described Fe (NO
3)
3,(NH
4)
2HPO
4,Aniline, NH
3H
2O, CH
3COOLi2H
2It is pure that O and ascorbic acid are analysis.
X-ray powder diffraction analytical technology (XRD) test result (see figure 1) shows that sample belongs to rhombic system, the Pnmb space group.Prepared sample preparation is become positive plate, then be assembled into CR2025 type button cell.
Concrete operations are as follows: according to active material: the respectively weighing of the ratio of acetylene black (C): PVDF=80:10:10, at first an amount of NMP (METHYLPYRROLIDONE) is added in the mortar, again load weighted PVDF is added and wherein grind, adding acetylene black and active material grind together after PVDF (poly-inclined to one side tetrafluoroethene) dissolves fully, to be mixed relatively evenly after, roll into the thin slice of even thickness at aluminium foil with simple and easy applicator, place 120 ℃ of vacuum drying chambers after 4 hours, with its circular pole piece that is washed into diameter 14mm, the quality of each pole piece is between 2mg-4mg.Take metal lithium sheet as negative pole, the Celgard2300 microporous polypropylene membrane is barrier film, uses lmol/LiPF
6/ E C+DMC+EMC (l:l:l volume ratio) is electrolyte, be lower than 5% in relative humidity, oxygen forces down and be assembled into CR2025 type button cell in the glove box that is full of argon gas of 10ppm, place vacuum drying chamber after 12 hours until battery, can carry out charge-discharge test, ac impedance measurement (EIS), cyclic voltammetry (CV) to battery.Charging voltage 2.5V-4.2V, charge-discharge magnification are 0.2C, its first discharge capacity be 142.7mAh/g, first charge-discharge efficiency is 86.7%, circulates that capacity is 141.6 mAh/g after 30 times, material has preferably chemical property.
Claims (1)
1. a two-step method prepares the LiFePO that carbon coats
4The method of/C composite positive pole is characterized in that concrete steps are:
(1) in-situ polymerization prepares presoma FePO
4/ PANI: by stoichiometric proportion, respectively with the Fe (NO of 0.0125mol-0.05mol
3)
3Be dissolved in the beaker 1 that 50ml-200ml distilled water is housed; (NH with 0.0125mol-0.05mol
4)
2HPO
4Be dissolved in the beaker 2 that 100ml-400ml distilled water is housed, and add the 0.5ml-2ml aniline solution in beaker 2, magnetic agitation dropwise added solution in the beaker 1 in the beaker 2 after 5 minutes, added 0.5ml-2mlNH after dropwising again
3H
2O regulates the pH value; The normal temperature lower magnetic force stirred after 12 hours subsequently, and vacuum filtration, and clean 2-3 time with distilled water is transferred to that drying namely got corresponding FePO in 24 hours in 60 ℃ of baking ovens
4/ PANI presoma;
(2) LiFePO
4/ C composite manufacture: take by weighing 0.0125mol-0.05mol CH by stoichiometric proportion
3COOLi2H
2O adds the 10ml-20ml absolute ethyl alcohol and dissolves in agate mortar, further grinds in the presoma adding mortar with step (1) preparation, grinds after 1 hour presoma and CH
3COOLi2H
2The ascorbic acid of the 10%-30% of O quality summation adds together and grinds, and adds simultaneously the 15ml-30ml absolute ethyl alcohol, treats to stop to grind and being transferred to the sintering that carries out next stage in the porcelain boat when material in the mortar becomes jelly; Under the protection of argon gas, sintering carries out in two steps in the sintering process, first takes out grinding after 5 hours 200 ℃ of-500 ℃ of lower pre-burnings, and the material after will grinding again namely gets LiFePO through 600 ℃-1000 ℃ after sintering 8-15 hour
4/ C composite material;
Described Fe (NO
3)
3,(NH
4)
2HPO
4,Aniline, NH
3H
2O, CH
3COOLi2H
2It is pure that O and ascorbic acid are analysis.
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|---|---|---|---|
| CN2012104167936A CN102903920A (en) | 2012-10-28 | 2012-10-28 | Method for preparing carbon-coated LiFePO4/C composite cathode material with two-step sintering method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103647078A (en) * | 2013-12-19 | 2014-03-19 | 山东精工电子科技有限公司 | Preparation method of porous LiFePO4/C composite material |
| CN111146439A (en) * | 2018-11-06 | 2020-05-12 | 北京泰丰先行新能源科技有限公司 | Preparation method of lithium iron phosphate cathode material |
| CN112436132A (en) * | 2020-12-10 | 2021-03-02 | 桂林理工大学 | Method for preparing in-situ carbon-coated porous ferric phosphate material by adopting sweet osmanthus |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102208618A (en) * | 2010-03-31 | 2011-10-05 | 比亚迪股份有限公司 | Preparation method of lithium ion phosphate used as positive electrode active material |
-
2012
- 2012-10-28 CN CN2012104167936A patent/CN102903920A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102208618A (en) * | 2010-03-31 | 2011-10-05 | 比亚迪股份有限公司 | Preparation method of lithium ion phosphate used as positive electrode active material |
Non-Patent Citations (1)
| Title |
|---|
| YONGGANG WANG，ET AL.: "The Design of a LiFePO4/Carbon Nanocomposite With a Core-Shell Structure and Its Synthesis by an In Situ Polymerization Restriction", 《ANGEWANDTE CHEMIE INTERNATIONAL EDITION》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103647078A (en) * | 2013-12-19 | 2014-03-19 | 山东精工电子科技有限公司 | Preparation method of porous LiFePO4/C composite material |
| CN103647078B (en) * | 2013-12-19 | 2015-09-16 | 山东精工电子科技有限公司 | A kind of poroid LiFePO 4the preparation method of/C composite |
| CN111146439A (en) * | 2018-11-06 | 2020-05-12 | 北京泰丰先行新能源科技有限公司 | Preparation method of lithium iron phosphate cathode material |
| CN111146439B (en) * | 2018-11-06 | 2021-10-15 | 北京泰丰先行新能源科技有限公司 | Preparation method of lithium iron phosphate cathode material |
| CN112436132A (en) * | 2020-12-10 | 2021-03-02 | 桂林理工大学 | Method for preparing in-situ carbon-coated porous ferric phosphate material by adopting sweet osmanthus |
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Application publication date: 20130130 |