CN102034964A - Method for preparing lithium ion battery composite material - Google Patents

Method for preparing lithium ion battery composite material Download PDF

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CN102034964A
CN102034964A CN2009101963477A CN200910196347A CN102034964A CN 102034964 A CN102034964 A CN 102034964A CN 2009101963477 A CN2009101963477 A CN 2009101963477A CN 200910196347 A CN200910196347 A CN 200910196347A CN 102034964 A CN102034964 A CN 102034964A
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preparation
composite material
lifepo
fepo
carbon source
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余爱水
刘佳丽
黄桃
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Fudan University
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Fudan University
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention belongs to the technical field of electrochemistry, and relates to a lithium ion battery anode material, in particular to a method for preparing a LiFePO4/C composite material. In the method, a FePO4 precursor is prepared by taking tervalent ferric salt as an initial material and by a precipitation process, and a carbon source is introduced, high-temperature calcination is performed and thus, the LiFePO4/C composite material is obtained. The LiFePO4 particles prepared by the method are distributed uniformly, have high performance, and are low in cost, the post heat treatment can be performed according to requirements in the synthesis process and the steps are simple. A product with high electrochemical performance can be prepared by regulating and controlling a micro-appearance.

Description

A kind of preparation method of lithium ion battery composite material
Technical field
The invention belongs to technical field of electrochemistry, relate to anode material for lithium-ion batteries, relate in particular to a kind of preparation method of lithium ion battery composite material, be specifically related to a kind of LiFePO 4The preparation method of/C composite material.
Background technology
1997, Padhi and Goodenough etc. found olivine-type LiFePO 4Have the embedding of taking off behavior, its space group is Pnmb, and oxygen atom is arranged with a kind of hexagonal closs packing form of dislocation slightly, and phosphorus atoms occupies tetrahedral 4c position, and iron atom and lithium atom occupy octahedral 4c and 4a position respectively.If set out FeO with the axial visual angle of b 6Octahedron couples together with certain angle on the bc plane, and LiO 6Octahedron then is total to the limit along the b direction of principal axis, forms chain.A FeO 6Octahedron respectively with a PO 4Tetrahedron and two LiO 6Octahedra limit altogether, a PO simultaneously 4Tetrahedron also with two LiO 6Octahedra limit altogether, this has just formed the hole that can supply the free embedding of lithium ion to take off.So LiFePO 4Have lithium ion and take off the embedding passage, good electrochemical, discharge platform is very steady, Stability Analysis of Structures in the charge and discharge process, theoretical capacity is 170mAh/g, with traditional positive electrode LiMn 2O 4And LiCoO 2Compare, it has the following advantages: fail safe is good, and cycle performance is more stable, and cycle life can reach more than 2000 times, and high-temperature behavior is better, and is pollution-free, and environmental friendliness is cheap.
At present, LiFePO 4Synthetic method mainly contain high temperature solid-state method, hydrothermal synthesis method, microwave process for synthesizing etc.High temperature solid-state method is the method for more generally taking at present, Yamada Li 2CO 3, Fe (CH 3COO) 22H 2O, (NH 4) 2H 2PO 4As starting material, under the nitrogen atmosphere protection, high-temperature calcination obtains LiFePO 4M.Stanley Whittingham seminar has proposed hydrothermal synthesis method first, adopts FeSO 4As starting material, hydro-thermal reaction prepares LiFePO under HTHP 4(S.F.Yang, P.Y.Zavalij, M.S.Whittingham, Electrochem.Commun., 3 (2001) 505).People such as M.Iguchi are with Li 2CO 3, NH 4H 2PO 4, Fe (CH 3COO) 2Or contain the Fe (CH of Fe powder 3CHOCOO) 22H 2O is dissolved in ethanol, and the argon gas atmosphere protection adds reaction for preparation LiFePO down in microwave oven 4(M.Higuchi, K.Katayama, Y.Azuma, M.Yukawa, M.Suhara, J.Power Sources, 119-121 (2003) 258-261).The defective of the scarce existence that said method is common is, generally takes the comparatively expensive and easily oxidized Fe of price 2+As starting material, pyroreaction need be carried out, under inert atmosphere to prevent Fe 2+Be oxidized to Fe 3+, operate comparatively loaded down with trivial details.
For this reason, several studies group begins to adopt Fe at present 3+As raw material, preparation LiFePO 4LiFePO 4Electronic conductivity own is lower, but carbon coats the conductance that can effectively improve material.Human FePO such as L.N.Wang 44H 2O is as starting material, and PEG prepares LiFePO as reducing agent and carbon source 4/ C (L.N.Wang, Z.G.Zhang, K.L.Zhang, J.Power Sources 167 (2007) 200).Human FePO such as Y.Q.Wang 4With (NH 4) 2SO 3Be the synthetic NH of starting material 4FePO 4, further synthetic again LiFePO 4(Y.Q.Wang, J.L.Wang, J.Yang, Y.Nuli, Adv.Funct.Mater, 16 (2006) 2135).With Fe 3+Prepare LiFePO as starting material 4Cost is lower, and is easy and simple to handle, and follow-up carbon source also can be used as reducing agent further with Fe 3+Be reduced to Fe 2+, have very extensive studies and application prospect.
Summary of the invention
The objective of the invention is to overcome the deficiencies in the prior art, a kind of preparation method of lithium ion battery composite material is provided, be specifically related to a kind of LiFePO 4The preparation method of/C composite material.
The present invention at first provides a kind of LiFePO 4The preparation method, it mainly solves in the existing in prior technology conventional solid-state method and adopts Fe 2+As starting material, and the difficult control of preparation LiFePO4 granular size, the agglomeration in the follow-up calcining; Prepare the FePO that particle is less and be evenly distributed by the precipitation method 4Precursor further prepares LiFePO 4/ C composite material.
Purpose of the present invention is achieved by the following technical programs:
Dissolve a certain amount of trivalent iron salt in deionized water, add surfactant, stir, add precipitation reagent NH as adjusting control agent 4H 2PO 4, continue to stir, suction filtration, oven dry obtains FePO 4Then with the FePO of gained 4Mix with lithium salts, carbon source, after 450 ℃ of preliminary treatment, high-temperature calcination again makes LiFePO 4/ C composite material.
Trivalent iron salt of the present invention comprises Fe 2(SO 4) 3, FeCl 3
Surfactant of the present invention is PEG, P123, CTAB.
Surfactant of the present invention and iron salt solutions volume ratio are 1: 1-2: 1.
It is 5-10 hour with the molysite incorporation time behind the adding surfactant of the present invention.
The post precipitation that obtains of the present invention continues to stir 3-5 hour.
Lithium salts of the present invention comprises LiOH, Li 2CO 3, LiCOOCH 3
Carbon source of the present invention comprises sucrose, glucose, citric acid or oxalic acid etc.
The addition of carbon source of the present invention is LiFePO 4The 1%-10wt% of theoretical yield.
Pre-burning of the present invention and reprocessing atmosphere are H 2, H 2/ Ar, N 2, gases such as Ar.
450 ℃ of pretreatment times of the present invention are 3-5 hour.
Back of the present invention calcining heat is 600-650 ℃.
Back of the present invention calcination time is 3-5 hour.
The inventive method prepares FePO by the aqueous solution precipitation method 4, add surfactant and can better disperse Fe 3+Fe 3+Be easy to be adsorbed on the surfactant surface, the backbone of activating agent can effectively be regulated and control the pattern of precipitation.Fe 3+Can further make Fe with the stirring of activating agent 3+Be dispersed on the long-chain of activating agent, the deposit seed that obtains is evenly distributed, and particle diameter is less.Choose the molysite of solubility, a certain amount of Fe of dissolving preparation 3+Solution adds surfactant, and the addition of activating agent is adjustable according to the iron salt solutions amount of configuration, because the activating agent kind difference of selecting for use, therefore proportioning also can regulate.
The introducing of carbon source in the inventive method can be played the effect that RESEARCH OF PYROCARBON coats, and can prepare LiFePO in high-temperature calcination simultaneously 4In/C the process as Fe 3+Reducing agent.
For anode material for lithium-ion batteries, its pattern, granular size all are the decisive factors of its chemical property, and the adding of activating agent can reduce the internal resistance between the ion in the precipitation process, the microscopic appearance of control product.And the different surfaces activating agent, the solvation effect difference, also different with the mating reaction between the metal ion, so also different to the regulating and controlling effect of product microscopic appearance.Therefore, this method can prepare the chemical property better products by the regulation and control to microscopic appearance.
The present invention has following characteristics:
The LiFePO that makes 4Even particle distribution, function admirable, cheap, can carry out after-baking as required in the synthesis technique, step is simple.
Description of drawings
Fig. 1 is the x-ray diffraction pattern of product,
Wherein, a is embodiment 1, and b is comparative example 1-1, and a is pure phase and degree of crystallinity LiFePO preferably 4Li appears in material among the b 3PO 4And Fe 2The trace impurity of P.
Fig. 2 is FePO 4Stereoscan photograph, wherein, a is embodiment 1, b is comparative example 1-2.
Fig. 3 is the transmission electron microscope photo of product, and wherein, a is embodiment 1, and b is comparative example 1-1.
Fig. 4 is the electrochemistry cycle performance of product, and wherein, a is embodiment 1, and b is comparative example 1-1.
Embodiment
Below in conjunction with accompanying drawing,, technical scheme of the present invention is described in further detail by embodiment.
Embodiment 1: preparation LiFePO 4Method, the steps include:
A. dissolve 5mmol Fe 2(SO 4) 3In the 15ml deionized water, add 15ml PEG-400 surfactant, magnetic agitation 15 hours.
B. with 1mmol NH 4H 2PO 4Be dissolved in the 15ml deionized water, add in the above-mentioned solution, produce FePO immediately 4Precipitation continues to stir 5 hours.
C. will precipitate suction filtration, with deionized water and acetone washing.
D. according to ICP or TG test, FePO in the analytic sample 4Content, add the LiOH of equimolar amounts, sucrose (is about LiFePO 4The 10wt% of ultimate output) after mortar mixes, hydrogen/450 ℃ of preliminary treatment of argon gas mist 5 hours.
E. after being cooled to room temperature, hydrogen argon gas mixed atmosphere continues 650 ℃ to be handled 3 hours.
Fig. 1 a has shown the X ray diffracting data of present embodiment product.
Fig. 2 a and Fig. 3 a have shown present embodiment FePO 4Sem photograph and product LiFePO 4The transmission electron microscope picture of/C.
Fig. 4 has shown the electrochemistry cycle performance of present embodiment product.
Comparative example 1-1
The calcining heat of removing among the step e is 700 ℃, and all the other steps are identical with embodiment 1 method.
Fig. 1 b has shown this comparative example X ray diffracting data.As can be seen from the figure, when calcining heat to 700 ℃, Fe is arranged in the product 2P (arrow logo among the figure), Li 3PO 4(asterisk sign among the figure).Preferred LiFePO among the present invention 4The follow-up calcining heat of/C is 600-650 ℃.
Fig. 3 b has shown this comparative example transmission electron microscope data.From its transmission electron microscope picture as can be seen, 700 ℃ of products obtained therefrom carbon coating layers do not have 650 ℃ carbon coating layer to be evenly distributed, because calcining heat is too high, coating layer are destroyed to some extent.
Fig. 4 has shown the electrochemistry cycle performance of present embodiment product:
Under the 0.1C discharge-rate, 650 ℃ of LiFePO that processing obtains 4/ C composite material shows good cycle performance, its first discharge capacity be 147.9mAh g -1, 40 ThDischarge capacity is 148.5mAh g -1And the sample that 700 ℃ of processing obtain can not effectively improve its lower electronic conductivity because the preceding coating layer of addressing is damaged, and causes its cycle performance relatively poor.
Comparative example 1-2
Except that not adding surfactant in step a, all the other steps are identical with embodiment 1 method.
Fig. 2 b has shown this comparative example ESEM picture,
From its sem photograph as can be seen, there is surfactant to have gained FePO 4The about 100nm of precipitation particle diameter, and do not have surfactant gained FePO 4Particle diameter is about 700nm.Display result can prove among the figure, and the adding surfactant described in the present invention is to regulation and control FePO 4The pattern effect.Long-chain by surfactant makes Fe 3+Be uniformly dispersed, obtain the FePO about the about 100nm of particle 4, by regulation and control FePO 4Pattern further regulate and control LiFePO 4The pattern of/C composite material can prevent in follow-up calcination process the appearance of the distribution of material non-uniform phenomenon that causes owing to reuniting.

Claims (14)

1. the preparation method of a lithium ion battery composite material is characterized in that, is starting material with the trivalent iron salt, prepares FePO with the precipitation method 4Precursor is introduced carbon source then, and high-temperature calcination makes LiFePO 4/ C composite material.
2. by the described preparation method of claim 1, it is characterized in that, comprise the steps:
Dissolve a certain amount of trivalent iron salt in deionized water, add surfactant, stir, add precipitation reagent NH as adjusting control agent 4H 2PO 4, continue to stir, suction filtration, oven dry obtains FePO 4Then with the FePO of gained 4Mix with lithium salts, carbon source, after 450 ℃ of preliminary treatment, high-temperature calcination again makes LiFePO 4/ C composite material.
3. preparation method according to claim 1 and 2 is characterized in that described trivalent iron salt is selected from Fe 2(SO 4) 3Or FeCl 3
4. preparation method according to claim 1 and 2 is characterized in that described surfactant is selected from PEG, P123 or CTAB.
5. preparation method according to claim 2 is characterized in that, described surfactant and iron salt solutions volume ratio are 1: 1-2: 1, stir.
6. preparation method according to claim 5 is characterized in that, mixing time is 5-10 hour.
7. preparation method according to claim 2 is characterized in that, obtains post precipitation, continues to stir 3-5 hour.
8. preparation method according to claim 2 is characterized in that described lithium salts is selected from LiOH, Li 2CO 3Or LiCOOCH 3
9. preparation method according to claim 2 is characterized in that described carbon source is selected from sucrose, glucose or citric acid.
10. preparation method according to claim 9 is characterized in that, the addition of described carbon source is LiFePO 4The 1-10wt% of theoretical yield.
11. preparation method according to claim 2 is characterized in that, described pre-burning and reprocessing atmosphere are H 2, H 2/ Ar, N 2Or Ar gas.
12. preparation method according to claim 2 is characterized in that, is 3-5 hour between described 450 ℃ of preliminary treatment are real.
13., it is characterized in that the temperature of described high-temperature calcination again is 600-650 ℃ according to claims 2 described preparation methods.
14., it is characterized in that the described time of high-temperature calcination again is 3-10 hour according to claims 13 described preparation methods.
CN2009101963477A 2009-09-24 2009-09-24 Method for preparing lithium ion battery composite material Pending CN102034964A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102390824A (en) * 2011-08-10 2012-03-28 朱叙国 Preparation method of lithium ion phosphate
CN102655233A (en) * 2011-12-14 2012-09-05 中聚电池研究院有限公司 Preparation method of LiFePO4/C anode material of lithium ion battery
CN105185993A (en) * 2015-10-21 2015-12-23 山东精工电子科技有限公司 Synthetic method for high-purity iron phosphate and doped metallic element thereof

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102390824A (en) * 2011-08-10 2012-03-28 朱叙国 Preparation method of lithium ion phosphate
CN102390824B (en) * 2011-08-10 2013-02-20 朱叙国 Preparation method of lithium iron phosphate
CN102655233A (en) * 2011-12-14 2012-09-05 中聚电池研究院有限公司 Preparation method of LiFePO4/C anode material of lithium ion battery
CN102655233B (en) * 2011-12-14 2014-05-07 中聚电池研究院有限公司 Preparation method of LiFePO4/C anode material of lithium ion battery
CN105185993A (en) * 2015-10-21 2015-12-23 山东精工电子科技有限公司 Synthetic method for high-purity iron phosphate and doped metallic element thereof
CN105185993B (en) * 2015-10-21 2017-12-19 山东精工电子科技有限公司 A kind of synthetic method of high-purity phosphoric acid iron and its doped metallic elements

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Application publication date: 20110427