CN101924204A - Method for preparing conducting film LiFePO4 cladding material containing nitrogen - Google Patents

Method for preparing conducting film LiFePO4 cladding material containing nitrogen Download PDF

Info

Publication number
CN101924204A
CN101924204A CN2010100398222A CN201010039822A CN101924204A CN 101924204 A CN101924204 A CN 101924204A CN 2010100398222 A CN2010100398222 A CN 2010100398222A CN 201010039822 A CN201010039822 A CN 201010039822A CN 101924204 A CN101924204 A CN 101924204A
Authority
CN
China
Prior art keywords
lifepo
output power
carbon film
film
microwave output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN2010100398222A
Other languages
Chinese (zh)
Other versions
CN101924204B (en
Inventor
李洲鹏
刘宾虹
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhejiang University ZJU
Original Assignee
Zhejiang University ZJU
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zhejiang University ZJU filed Critical Zhejiang University ZJU
Priority to CN201010039822A priority Critical patent/CN101924204B/en
Publication of CN101924204A publication Critical patent/CN101924204A/en
Application granted granted Critical
Publication of CN101924204B publication Critical patent/CN101924204B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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

Landscapes

  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention relates to a preparation method of a lithium ion battery anode material, aiming to provide a method for preparing a conducting film LiFePO4 cladding material containing nitrogen. The method comprises the following steps of: ball milling and mixing FePO4.4H2O, LiOH.H2O and a polyacrylonitrile emulsion, blending into a paste and putting the paste into a quartz reactor; regulating and controlling the microwave output power and controlling the reaction temperature to be at 150 DEG C; raising the microwave output power in an oxygen atmosphere and heating up to 300 DEG C from 150 DEG C; switching to a highly pure nitrogen atmosphere, raising the microwave output power and heating up to 600 DEG C from 300 DEG C; and continuously raising the microwave output power under the highly pure nitrogen atmosphere and annealing at 700-800 DEG C for denitrifying. Nitrogen atoms remain on the conducting carbon film formed by the invention, and lone pair electrons of the nitrogen atoms can effectively improve the conductivity of the carbon film so as to improve electrochemical and dynamic properties of the anode, reduce the electrode polarization and improve the velocity volume of the lithium cell, thus the invention can be applied to power cells of electric vehicles.

Description

Nitrogenous conducting film coats LiFePO 4Preparation methods
Technical field
The present invention relates to a kind of preparation method of anode material for lithium-ion batteries, particularly nitrogenous conducting polymer coats LiFePO 4Material, the LiFePO that utilizes the nitrogenous conductive carbon film of temperature control microwave prepared in reaction to coat 4Method.
Background technology
In light weight, advantages such as capacity big, memory-less effect that lithium ion battery has, thereby obtained widespread usage.Present many digital equipments have all adopted lithium ion battery to make power supply.The energy density of lithium ion battery is very high, and its capacity is 1.5～2 times with the Ni-MH battery of weight, and to have very low self-discharge rate, do not contain advantages such as Toxic matter be the major reason of its extensive use.Lithium ion battery is owing to use LiCoO at present 2As positive electrode, relatively more expensive comparatively speaking.
Since initiative proposition anode material for lithium-ion batteries LiFePO such as Padhi in 1997 4Since, LiFePO 4Become one of research focus of rechargeable lithium ion batteries positive electrode.With respect to other lithium ion cell positive alternative materials, LiFePO 4Advantage with self: (1) is high theoretical capacity (170mAh/g) relatively, and the charging/discharging voltage platform makes organic bath safer in battery applications stably; (2) good electrode reaction invertibity; (3) good chemical stability and thermal stability; (4) cheap and be easy to preparation; (5) pollution-free; Safer when (6) handling with operation.
Traditional viewpoint is thought, LiFePO 4Be two phase reaction when in battery, discharging and recharging:
Charging (taking off lithium): LiFePO 4-xLi +-xe -→ xFePO 4+ (1-x) LiFePO 4
Discharge (embedding lithium): FePO 4+ xe+xLi +→ xLiFePO 4+ (1-x) FePO 4
During electricity, Li +From FeO 6Layer moves out, enters negative pole, Fe through electrolyte 2+Be oxidized to Fe 3+, electronics then arrives negative pole through conductive agent and the collector that is in contact with one another from external circuit; Discharge process then in contrast.
Lithium ion battery is in charge and discharge process, and lithium ion takes off/the embedding process is at LiFePO 4/ FePO 4Taking off/the embedding process of two-phase interface.During charging, two-phase interface is inwardly nuclear propulsion constantly, outer field LiFePO 4Constantly change FePO into 4, constantly the two-phase interface by new formation is keeping effective current for lithium ion and electronics, but the diffusion rate of lithium ion is constant under certain condition, along with dwindling of two-phase interface, the diffusing capacity of lithium ion is not enough to keep effective current the most at last, like this, and the LiFePO of bulky grain kernel portion 4Can not be fully utilized, thereby cause capacitance loss.
There is report to utilize acrylic resin and LiOH and FePO 4The synthetic carbon of reaction coats LiFePO 4Synthetic method (JournalofThe Electrochemical Society, 152 (2005) A483-A487), can improve LiFePO 4The electrochemical reaction dynamics of electrode improves LiFePO 4Electrode life.But this method is with LiOH and FePO 4Mix and needed ball milling 2 hours, and need heat treatment at high temperature 10 hours, and inapplicable suitability for industrialized production LiFePO 4
The capacity of lithium ion battery is that positive electrode capacity limits, and the capacity of lithium ion battery depends on positive electrode capacity.Traditional LiFePO 4Preparation technology adopts dry powder blend, heat treatment at high temperature 10 hours.Because dry powder blend causes uneven components easily, and heat inhomogeneous or heat conduction inhomogeneous, finally all can cause product quality problem, thereby influence the capacity and the cycle life of lithium ion battery, and LiFePO 4The traditional handicraft production cycle also longer.Traditional electrical heating relies on outer heating by heat exchange pattern the material bed tempertaure to be raise heat, because FePO4 and LiOH poor thermal conductivity, the temperature distributing disproportionation that is easy to generate reaction bed is even and reaction speed that cause is unbalanced, causes LiFePO 4The rate of crystalline growth disunity is difficult to control LiFePO 4The shape of crystal and size.
Microwave heating is to heat by " dielectric loss ".Molecule with permanent dipole produces resonance frequency up to 4.9x10 in the electromagnetic field of 2450MHz 9Inferior/s, the ultrahigh speed rotation increases sharply (temperature rising) the molecule mean kinetic energy, and perhaps Ionized material because of friction produces thermal effect, is interior mode of heating in hyperfrequency electromagnetic field high speed vibration (conduction).The thermal effect that is produced depend on ionic size, electric charge what, conductive performance and with the interaction of solvent.Have the compound of big dielectric constant such as water, ethanol, LiOH, FePO 4, polyacrylonitrile, can be heated rapidly under microwave action; And little compound such as aromatic hydrocarbon, the aliphatic hydrocarbon of polarity or do not have compound such as carbon dioxide, dioxane, carbon tetrachloride and the highly crystalline carbon of clean dipole is poor to microwave energy absorption, is difficult for being heated.
In order to shorten LiFePO 4Generated time, reduce reaction temperature, control LiFePO 4The shape of crystal and size, the quality of raising product improves LiFePO 4The electrochemical reaction dynamics of electrode improves LiFePO 4Electrode life, there is Chinese invention patent " a kind of microwave synthesis method of carbon-coated LiFePO 4 for lithium ion batteries " (CN200510086594.3) to report: to press stoichiometry with lithium carbonate, ferrous oxalate and ammonium dihydrogen phosphate, an amount of thermal conducting agent and the organic substance that is used to carry out the carbon coating: the saccharide compound of poly-hydrocarbon compound such as polyethylene or sucrose, starch, make the abundant ground and mixed of dispersant with absolute ethyl alcohol, be pressed into bulk after drying, put into the crucible that active carbon is housed, crucible is placed the microwave field radiation heating, can make mutually the evenly LiFePO4 of carbon coating.
In electrode, add the conductivity that nitrogenous conducting polymer composite can significantly improve electrode material, have the carbon based cobaltous hydroxide of patent report (CN200910098410.3) polypyrrole modifying to have good electro catalytic activity.Compare with graphite, the nitrogen in polypyrrole, polyaniline or the polyacrylonitrile can increase the concentration of conjugated pi electron owing to the existence of its lone pair electrons, thereby can obtain surpassing the conductivity of graphite.
The present invention proposes the wet-mixed raw material, the LiFePO that utilizes synthetic nitrogenous conductive carbon film with high conductivity of one step of temperature control microwave heating to coat 4Material.Be with the difference of patent (CN200510086594.3): the conducting film of formation is different, and synthesis step is different with conducting film formation mechanism, and the unreal trip temperature control of patent (CN200510086594.3) is difficult to guarantee product quality.And temperature is controlled at LiFePO 4Synthesis technique in, no matter be at control LiFePO 4Granularity, vpg connection, still aspect control of product quality, all play decisive action.Use polyacrylonitrile to carry out temperature control microwave and add the LiFePO that the nitrogenous conductive carbon film of thermal synthesis coats as raw material 4Material does not still have successful precedent, does not see the LiFePO that has nitrogenous conductive carbon film to coat yet 4The report of material.
Summary of the invention
The technical problem to be solved in the present invention is, a kind of efficient energy-saving is provided, and synthetic have a LiFePO that high-performance, high-quality nitrogenous conductive carbon film coat 4Preparation methods.
For the technical solution problem, the preparation method in the technical scheme provided by the invention comprises step:
(1) getting purity is 99.99% FePO 44H 2O and purity are 99.99% LiOH H 2O and polyacrylonitrile emulsion (40wt%) are pressed mass ratio 9.31: 1: 5～20, and ball milling mixed 10～30 minutes, was modulated into paste, put into quartz reactor, and the regulation and control microwave output power makes temperature of charge be controlled at 150 ℃.Partial melting takes place in this moment, begins to take place dehydration, forms anhydrous FePO 4With the LiOH mixture, polyacrylonitrile emulsion dehydration back forms polyacrylonitrile film and covers FePO 4On LiOH mixture particle.By adjusting FePO 44H 2O, LiOHH 2O and polyacrylonitrile emulsion blending ratio and ball milling speed (200～800rpm) and time may command dehydration back form FePO 4Shape and size with LiOH mixture particle.
(2) strengthen microwave output power gradually under oxygen atmosphere, the temperature rise control that makes reactant is heated to 300 ℃ at 1～2 ℃/min from 150 ℃, and cyclization, dehydrogenation reaction and the oxidation reaction of polyacrylonitrile takes place this moment, and the stabilization procedures of polyacrylonitrile film takes place.Molecular structure changes carbon-to-nitrogen double bon (C=N) ring structure that contracts, promptly so-called trapezium structure into by polyene structure.In stabilization procedures, the attached cyano group group of polyacrylonitrile, commissure macromolecular structure in echelon at first, this process can add a small amount of 2-methylene-succinic acid and carry out catalysis.In stabilization procedures, oxygen molecule also participates in the ladderlike polymer reaction, thereby several trapezoidal molecular structures may occur.Polyacrylonitrile film causes film to shrink after process cyclization and stabilisation, because polyacrylonitrile film coats FePO 4On LiOH mixture particle, stoped the contraction of film on area to take place, but therefore the thickness of film reduce.
(3) oxygen atmosphere is switched to continuation increasing microwave output power under the high pure nitrogen atmosphere, the temperature rise control that makes reactant is heated to 600 ℃, the carbonisation of generation polyacrylonitrile film, formation graphite-like structure at 3～5 ℃/min from 300 ℃.High purity nitrogen among the present invention is meant that purity is 99.99% nitrogen.At the carburizing reagent initial stage, temperature is 400～500 ℃ of scopes, and the hydroxy that is present in the already oxidised polyacrylonitrile begins to carry out the commissure condensation reaction, helps cyclisation partly to recombinate and engage, this cross-linking reaction is fixed the macromolecular structure of silicon carbide/polypropylene nitrile film, as shown in Figure 1.Remaining linear structure partly becomes cyclisation or carries out chain splitting and discharge reducibility gas such as hydrogen.These cyclized structure carry out dehydrogenation reaction, and begin to connect in side surface direction, produce three hexagons that side surface direction forms by the nitrogen-atoms bond and form and so on graphite-structure, the conductive carbon film coating layer, as shown in Figure 2.Meanwhile, FePO 4In being reduced property of ferric iron gas such as the hydrogen reducing LiFePO that forms ferrous iron and LiOH reaction generation olivine structural 4:
2FePO 4+2LiOH+H 2→2LiFePO 4+2H 2O
(4) under the high pure nitrogen atmosphere, continue to strengthen microwave output power, make temperature of charge reach 700～800 ℃ of denitrogenations of annealing, make the conductive carbon film growth more complete, as shown in Figure 3, eliminate the stress in the conductive carbon film coating layer, finally form the LiFePO that conductive carbon film coats 4Material.
Among the present invention, in the conductive carbon film that forms, nitrogen content depends on the time of 700～800 ℃ of denitrogenations of annealing, and the time, long more nitrogen content was low more.Because nitrogen has lone pair electrons, it has facilitation for the conduction of the conjugated pi electron of graphite-like structure.But nitrogen content is too high, will cause the incomplete of conductive carbon film growth, and is unfavorable to the conductivity of electrode.Therefore for the positive electrode of different purposes, the time that should control corresponding denitrogenation is 1～5 hour.Among the present invention, the percentage by weight of nitrogen in conducting film is 0.1～1wt.%.
Among the present invention, adopt temperature control microwave to add thermal synthesis, effectively controlled the LiFePO that conductive carbon film coats 4Shape and size, can obtain the LiFePO of particle diameter less than 100nm 4Spheroidal particle, residual LiFePO in the time of can avoiding charging 4The appearance of phase improves charge/discharge capacity.
Among the present invention, adopt accurate infrared measurement of temperature method, by infrared signal controlled microwave power output, to arrive the purpose of accurate control programming rate and reaction temperature.
Among the present invention, because at LiFePO 4Particle shape has become the nitrogenous carbon film of high conductivity, because the lone pair electrons of nitrogen have been strengthened the flowability of conjugated pi electron in the carbon film graphite-like structure, improve the conductivity of carbon film, played the function of current collection effectively, anodal conductivity is greatly improved, need not in the preparation process of electrode, to add conductive agent in addition, thereby improved anodal capacity.Limit because the capacity of lithium ion battery is a positive electrode capacity, therefore also just improved the capacity of lithium ion battery.
Among the present invention, the LiFePO that conductive carbon film coats 4During as the positive electrode of lithium ion battery, because LiFePO 4Particle is among the coating of conductive carbon film, and lithium ion battery is LiFePO in charge and discharge process 4The change in volume that the taking off of lithium ion/embedding caused all coats in the capsule at conductive carbon film and takes place, and can not cause coming off of positive electrode, stable anodal structure, thereby the life-span of improving lithium ion battery.This point is showing particularly outstandingly aspect the high power charging-discharging cycle life that improves lithium ion battery.
The beneficial effect that the present invention has:
The present invention utilizes microwave can only heat the characteristics of polar molecule, carries out FePO 4With the individuality heating of LiOH mixture particle, eliminate FePO 4The even reaction speed that causes of temperature distributing disproportionation of the reaction bed that produces because of poor thermal conductivity with LiOH is unbalanced, LiFePO 4The skimble-scamble problem of rate of crystalline growth accurately and fast control reaction temperature and reaction time, forms LiFePO thereby control effectively 4Shape and size.And in the conductive carbon film forming process, in case form nonpolar complete carbon film, microwave heating is just ineffective, and therefore, microwave heating always forms the forward position at carbon film and plays heat effect.And microwave action causes resonance on oxygen, hydrogen and the nitrogen-atoms of polar binding, helps the cyclization of polyacrylonitrile and dehydrogenation subsequently and denitrification reaction, helps the formation of conductive carbon film.Can not occur because the inhomogeneous or incomplete defective that causes of the inhomogeneous reaction that occurs of heat conduction of heating.
Adopt accurate infrared measurement of temperature method,, can accurately control programming rate and reaction temperature, thereby avoid causing LiFePO when reacting by infrared signal controlled microwave power output 4The crystal forming core is inhomogeneous, avoids non-spherical LiFePO 4The formation of crystal, the LiFePO of formation 4The crystalline size consistency is better.Accurately the control programming rate can make carbon film grow up fully, forms and coats LiFePO fully 4The carbon film of particle makes the nitrogen content in the carbon film controlled, and the carbon film conductivity that obtains is better.Use the synthetic LiFePO of temperature control microwave heating of the present invention 4, form and coat LiFePO fully 4The carbon film of particle, LiFePO 4The LiFePO that the size of crystal more consistent (as shown in Figure 4), its capacity and speed capabilities are all synthetic than traditional heating or common microwave is synthetic 4Want high (as shown in Figure 5).
Remaining on the conductive carbon film that forms among the present invention have a nitrogen-atoms, its lone pair electrons can effectively improve the conductivity of carbon film, thereby improve anodal electrochemical kinetics performance, reduce electrode polarization, improve the speed capabilities of lithium battery, can be applicable to the electrokinetic cell of electric automobile.
Description of drawings
Fig. 1 is the film stabilization procedures of polyacrylonitrile film through generation dehydration behind the cyclization.
Fig. 2 is the dehydrogenation carbonisation of polyacrylonitrile film through film stabilization procedures caudacoria.
Fig. 3 is the denitrogenation growth course of polyacrylonitrile film through film stabilization procedures, dehydrogenation carbonisation caudacoria.
The ball shaped nano LiFePO that Fig. 4 coats for the nitrogenous conductive carbon film for preparing among the embodiment 4The material transmission electron microscope photo.
The ball shaped nano LiFePO that Fig. 5 coats for the nitrogenous conductive carbon film for preparing among the embodiment 4Synthesize LiFePO for the capacity result of positive electrode and with common microwave 4And the synthetic LiFePO of traditional heating 4Capacity Ratio.
Embodiment
Below in conjunction with embodiment the present invention is described in further detail:
Embodiment one: Paste Preparation
Getting 222.9 gram purity is 99.99% FePO 44H 2O and purity are 99.99% LiOH H 2O, polyacrylonitrile emulsion (40wt%) were pressed mass ratio 9.31: 1: 5, placed ball grinder to mix 10 minutes with the 800rpm ball milling, were modulated into paste.
Embodiment two: the lotion dehydration
Getting 222.9 gram purity is 99.99% FePO 44H 2O and purity are 99.99% LiOH H 2O and polyacrylonitrile emulsion (40wt%) were pressed mass ratio 9.31: 1: 15, placed ball grinder to mix 20 minutes with the rotating speed ball milling of 600rpm, were modulated into paste, put into quartz reactor, and the adjustment microwave output power is 1KW, makes temperature of charge be controlled at 150 ℃.FePO takes place 44H 2O and LiOHH 2The emulsion polymerisation of O and polyacrylonitrile and dehydration form the spherical FePO that polyacrylonitrile film coats 4With the LiOH mixture.FePO 4With the particle diameter of LiOH less than 100nm.
Embodiment three: the formation blank of carbonized film
Getting 222.9 gram purity is 99.99% FePO 44H 2O and purity are 99.99% LiOH H 2O and polyacrylonitrile emulsion (40wt%) were pressed mass ratio 9.31: 1: 20, placed ball grinder to mix 30 minutes with the rotating speed ball milling of 200rpm, were modulated into paste, put into quartz reactor, and the adjustment microwave output power is 1KW, makes temperature of charge be controlled at 150 ℃.FePO takes place 44H 2O and LiOHH 2The emulsion polymerisation of O and polyacrylonitrile and dehydration form the FePO that polyacrylonitrile film coats 4With the LiOH mixture.With the speed aerating oxygen of 10mL/min, strengthen microwave output power in the reactor, the temperature rise control that makes reactant is heated to 300 ℃ at 1 ℃/min from 150 ℃, and this moment is at spherical FePO 4Cyclization and stabilization procedures with polyacrylonitrile film takes place on the LiOH mixture particle form incomplete carbonized film.
Embodiment four: LiFePO 4Formation and the growth of carbonized film
Getting 222.9 gram purity is 99.99% FePO 44H 2O and purity are 99.99% LiOHH 2O and polyacrylonitrile emulsion (40wt%) were pressed mass ratio 9.31: 1: 20, placed ball grinder to mix 30 minutes with the rotating speed ball milling of 400rpm, were modulated into paste, put into quartz reactor, and the adjustment microwave output power is 1KW, makes temperature of charge be controlled at 150 ℃.FePO takes place 44H 2O and LiOHH 2The emulsion polymerisation of O and polyacrylonitrile and dehydration form FePO4 and LiOH mixture that polyacrylonitrile film coats.With the speed aerating oxygen of 10mL/min, strengthen microwave output power to 1.5KW in the reactor, the temperature rise control that makes reactant is heated to 300 ℃ at 2 ℃/min from 150 ℃, and this moment is at FePO 4With cyclization and stabilization procedures that polyacrylonitrile film takes place on the LiOH mixture particle.Oxygen atmosphere is switched to (10mL/min) continuation increasing microwave output power (1.6KW) under the high pure nitrogen atmosphere, the temperature rise control that makes reactant is at 4 ℃/min, be heated to 600 ℃, the carbonisation of generation polyacrylonitrile film, formation graphite-like structure release reducibility gas hydrogen from 300 ℃.FePO 4In ferric iron formed the LiFePO of ferrous iron and LiOH reaction generation olivine structural by hydrogen reducing 4, particle diameter is less than 100nm.Begin to take shape the spherical LiFePO that nitrogenous carbonized film coats 4
Embodiment five: the ball shaped nano LiFePO that nitrogenous carbonized film coats 4Preparation
Getting 222.9 gram purity is 99.99% FePO 44H 2O and purity are 99.99% LiOHH 2O and polyacrylonitrile emulsion (40wt%) were pressed mass ratio 9.31: 1: 20, placed ball grinder to mix 30 minutes with the rotating speed ball milling of 400rpm, were modulated into paste, put into quartz reactor, and the adjustment microwave output power is 1KW, makes temperature of charge be controlled at 150 ℃.FePO takes place 44H 2O and LiOHH 2The emulsion polymerisation of O and polyacrylonitrile and dehydration form the FePO that polyacrylonitrile film coats 4With the LiOH mixture.With the speed aerating oxygen of 10mL/min, strengthen microwave output power to 1.5KW in the reactor, the temperature rise control that makes reactant is heated to 300 ℃ at 2 ℃/min from 150 ℃, and this moment is at FePO 4With cyclization and stabilization procedures that polyacrylonitrile film takes place on the LiOH mixture particle.Oxygen atmosphere is switched to (10mL/min) continuation increasing microwave output power (1.6KW) under the high pure nitrogen atmosphere, the temperature rise control that makes reactant is at 5 ℃/min, be heated to 600 ℃, the carbonisation of generation polyacrylonitrile film, formation graphite-like structure release reducibility gas hydrogen from 300 ℃.FePO 4In ferric iron formed the LiFePO of ferrous iron and LiOH reaction generation olivine structural by hydrogen reducing 4, particle diameter is less than 100nm.Under the high pure nitrogen atmosphere, continue to strengthen microwave output power (2KW), make temperature of charge reach 800 ℃ of denitrogenations 1 hour of annealing, make the conductive carbon film growth more complete, form the ball shaped nano LiFePO that nitrogenous conductive carbon film coats 4Material, as shown in Figure 4.Detect through XPS, the content of nitrogen in the nitrogenous film of conduction is 0.1wt.%.
Embodiment six: the ball shaped nano LiFePO that nitrogenous carbonized film coats 4Lithium ion battery for positive pole
Getting 222.9 gram purity is 99.99% FePO 44H 2O and purity are 99.99% LiOHH 2O and polyacrylonitrile emulsion (40wt%) were pressed mass ratio 9.31: 1: 20, placed ball grinder to mix 30 minutes with the rotating speed ball milling of 400rpm, were modulated into paste, put into quartz reactor, and the adjustment microwave output power is 1KW, makes temperature of charge be controlled at 150 ℃.FePO takes place 44H 2O and LiOHH 2The emulsion polymerisation of O and polyacrylonitrile and dehydration form the FePO that polyacrylonitrile film coats 4With the LiOH mixture.With the speed aerating oxygen of 10mL/min, strengthen microwave output power to 1.5KW in the reactor, the temperature rise control that makes reactant is heated to 300 ℃ at 2 ℃/min from 150 ℃, and this moment is at FePO 4With cyclization and stabilization procedures that polyacrylonitrile film takes place on the LiOH mixture particle.Oxygen atmosphere is switched to (10mL/min) continuation increasing microwave output power (1.6KW) under the high pure nitrogen atmosphere, the temperature rise control that makes reactant is at 5 ℃/min, be heated to 600 ℃, the carbonisation of generation polyacrylonitrile film, formation graphite-like structure release reducibility gas hydrogen from 300 ℃.FePO 4In ferric iron formed the LiFePO of ferrous iron and LiOH reaction generation olivine structural by hydrogen reducing 4, particle diameter is less than 100nm.Under the high pure nitrogen atmosphere, continue to strengthen microwave output power (1.8KW), make temperature of charge reach 700 ℃ of denitrogenations 5 hours of annealing, make the conductive carbon film growth more complete, form the ball shaped nano LiFePO that nitrogenous conductive carbon film coats 4Material.Detect through XPS, the content of nitrogen in conductive carbon film is 1wt.%.
Getting 1 gram above-mentioned positive electrode and PVDF and ethanol is to mix at 90: 10: 20 to add ethanol and be modulated into slurry according to mass ratio, is coated on the aluminium foil, dries to make electrode after suppressing.With the lithium metal is negative pole, and the PP nonwoven fabrics is a barrier film, and electrolyte is 1mol/L LiPF 6Ethylene carbonate (EC)+dimethyl carbonate (DMC)+methyl ethyl carbonate (EMC) (volume ratio is 1: 1: 1) mixed solution, in glove box, be assembled into button cell, carry out volume test under the electric current of 0.1～10C, Fig. 5 is the ball shaped nano LiFePO of the nitrogenous conductive carbon film coating of preparation 4The volume test result.Coat LiFePO with the synthetic carbon film of common microwave 4And traditional electrical adds thermal synthesis carbon film coating LiFePO 4Compare the ball shaped nano LiFePO that the synthetic nitrogenous conductive carbon film of temperature control microwave coats 4The capacity high-rate discharge ability be improved significantly, be that the synthetic carbon film of common microwave coats LiFePO 41.47 times, be that traditional electrical adds the thermal synthesis carbon film and coats LiFePO 41.36 times.
What more than announce at last, only is specific embodiments of the invention.All distortion that those of ordinary skill in the art can directly derive or associate from content disclosed by the invention all should be thought protection scope of the present invention.

Claims (4)

1. a nitrogenous conductive carbon film coats LiFePO 4Preparation methods may further comprise the steps:
(1) with mass ratio is 9.31: 1: 5～20 FePO 44H 2O, LiOHH 2The polyacrylonitrile emulsion of O and 40wt% was mixed 10～30 minutes with the speed ball milling of 200～800rpm, put into quartz reactor after being modulated into paste, and the regulation and control microwave output power makes temperature of charge be controlled at 150 ℃ and dewaters and the polyacrylonitrile emulsion polymerisation;
(2) strengthen microwave output power under oxygen atmosphere, the temperature rise of control reactant is 1～2 ℃/min, is heated to 300 ℃, formation carbonized film blank from 150 ℃;
(3) switch to the high pure nitrogen atmosphere from oxygen atmosphere, continue to strengthen microwave output power, the temperature rise of control reactant is 3～5 ℃/min, be heated to 600 ℃ from 300 ℃, the carbonization that polyacrylonitrile film takes place forms graphite-like structure, at the carburizing reagent initial stage of temperature, begin to take shape the spherical LiFePO that carbonized film coats at 400～500 ℃ 4
(4) be to continue under 99.99% the blanket of nitrogen to strengthen microwave output power in purity, make temperature of charge reach 700～800 ℃ of denitrogenations of annealing, form the LiFePO that nitrogenous conductive carbon film coats 4Material product.
2. coat LiFePO according to the described nitrogenous conductive carbon film of claim 1 4Preparation methods is characterized in that, in the step (4), the time of control annealing denitrogenation is 1～5 hour.
3. coat LiFePO according to the described nitrogenous conductive carbon film of claim 1 4Preparation methods is characterized in that, described FePO 44H 2O, LiOHH 2O purity is 99.99%.
4. coat LiFePO according to the described nitrogenous conductive carbon film of claim 1 4Preparation methods is characterized in that, the percentage by weight of nitrogen in conducting film is 0.1～1wt.%.
CN201010039822A 2010-01-21 2010-01-21 Method for preparing conducting film LiFePO4 cladding material containing nitrogen Expired - Fee Related CN101924204B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201010039822A CN101924204B (en) 2010-01-21 2010-01-21 Method for preparing conducting film LiFePO4 cladding material containing nitrogen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201010039822A CN101924204B (en) 2010-01-21 2010-01-21 Method for preparing conducting film LiFePO4 cladding material containing nitrogen

Publications (2)

Publication Number Publication Date
CN101924204A true CN101924204A (en) 2010-12-22
CN101924204B CN101924204B (en) 2012-09-19

Family

ID=43338963

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201010039822A Expired - Fee Related CN101924204B (en) 2010-01-21 2010-01-21 Method for preparing conducting film LiFePO4 cladding material containing nitrogen

Country Status (1)

Country Link
CN (1) CN101924204B (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102074692A (en) * 2010-12-31 2011-05-25 深圳大学 Preparation method for similar graphene doped lithium ion battery positive electrode material
CN102709553A (en) * 2012-05-28 2012-10-03 深圳市贝特瑞新能源材料股份有限公司 Positive electrode material and synthetic method thereof
CN104009232A (en) * 2014-06-10 2014-08-27 湖北工程学院 Preparation method of lithium iron phosphate composite anode material
CN107858829A (en) * 2017-11-28 2018-03-30 东华大学 A kind of method that microwave oxidizing process prepares preoxidized polyacrylonitrile silk
CN108878822A (en) * 2018-06-22 2018-11-23 宜春学院 Coat the preparation method of nano ferric phosphate composite material
CN110093688A (en) * 2018-01-29 2019-08-06 永虹先进材料股份有限公司 Fiber preoxidation equipment

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1775666A (en) * 2005-10-12 2006-05-24 北京科技大学 Method for synthesizing carbon-cladded ironic lithium phosphate
CN1911792A (en) * 2006-08-22 2007-02-14 南京大学 Microwave synthesis method for carbon coated iron phosphate of ion battery composite anode material
CN101237043A (en) * 2008-01-31 2008-08-06 东北师范大学 Method for making ferrous lithium phosphate/carbon compound material of high active disorderly ferric phosphate

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102074692A (en) * 2010-12-31 2011-05-25 深圳大学 Preparation method for similar graphene doped lithium ion battery positive electrode material
WO2012089085A1 (en) * 2010-12-31 2012-07-05 深圳大学 Method for preparing graphene-like doped positive electrode material of lithium-ion battery
CN102074692B (en) * 2010-12-31 2013-10-30 深圳大学 Preparation method for similar graphene doped lithium ion battery positive electrode material
CN102709553A (en) * 2012-05-28 2012-10-03 深圳市贝特瑞新能源材料股份有限公司 Positive electrode material and synthetic method thereof
CN102709553B (en) * 2012-05-28 2015-05-20 深圳市贝特瑞新能源材料股份有限公司 Positive electrode material and synthetic method thereof
CN104009232A (en) * 2014-06-10 2014-08-27 湖北工程学院 Preparation method of lithium iron phosphate composite anode material
CN107858829A (en) * 2017-11-28 2018-03-30 东华大学 A kind of method that microwave oxidizing process prepares preoxidized polyacrylonitrile silk
CN110093688A (en) * 2018-01-29 2019-08-06 永虹先进材料股份有限公司 Fiber preoxidation equipment
CN108878822A (en) * 2018-06-22 2018-11-23 宜春学院 Coat the preparation method of nano ferric phosphate composite material
CN108878822B (en) * 2018-06-22 2021-04-09 宜春学院 Preparation method of coated nano iron phosphate composite material

Also Published As

Publication number Publication date
CN101924204B (en) 2012-09-19

Similar Documents

Publication Publication Date Title
CN102610862B (en) Preparation method for lithium battery taking polypyrrole-coated magnesium borate as anode material
CN102598388B (en) Lithium secondary battery
CN104918887B (en) Method for preparing the lithium iron phosphate nano powder through carbon coating
CN109888246B (en) Silicon monoxide composite negative electrode material with gradient structure and preparation method and application thereof
CN102468515B (en) Lithium ion battery and preparation method thereof
CN1280185C (en) Preparation process of lithium ferrous phosphate for positive pole of lithium ion cell
CN102244241B (en) Preparation method of lithium iron phosphate composite material modified by lithium pyrophosphate
CN102034971B (en) Lithium-ion battery lithium iron phosphate/polypyrrole pyridine composite anode material and preparation method thereof
CN101924204B (en) Method for preparing conducting film LiFePO4 cladding material containing nitrogen
CN102361073B (en) Preparation method of lithium ion battery silicon aluminium carbon composite cathode material
CN101504979A (en) A novel preparation method for LiFePO4/C composite positive pole material
CN103384001B (en) A kind of graphene combination electrode material and solid catalysis preparation method thereof
CN106602038B (en) A kind of hot method of colloidal sol secondary solvent prepares grain rod mixing pattern phosphoric acid vanadium lithium/carbon composite anode material and preparation method thereof
US20160218354A1 (en) Hybrid Electrode For Non-Aqueous Electrolyte Secondary Battery
CN102074686A (en) Method for synthesizing manganese lithium phosphate/carbon serving as positive material of lithium ion battery
CN102104144A (en) Method for preparing lithium iron phosphate compound anode material
CN107437617A (en) A kind of surface modification method, gained richness lithium material and application for improving rich lithium material chemical property
CN104124453A (en) Lithium iron manganese phosphate composite positive electrode material and preparation method, positive electrode and lithium battery
CN101555004A (en) Method for rapidly preparing lithium iron phosphate by intermittent microwave
CN102177606A (en) Cathode composite material with improved electrode efficiency and energy density characteristics
CN102324519A (en) High-conductivity ferrous phosphate lithium cathode material for lithium ion battery and preparation method thereof
CN105742592B (en) A kind of carbon-coated method for preparing anode material of lithium-ion battery of W/W2C/ activity
CN102280625A (en) Method for manufacturing carbon-coated vanadate composite fiber of lithium ion battery anode material
CN114455563B (en) Modified lithium iron phosphate material and preparation method and application thereof
CN101527370A (en) Power lithium ion battery

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant
C17 Cessation of patent right
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20120919

Termination date: 20140121