The preparation method of electrochemical active material
Technical field
The present invention relates to a kind of preparation method of electrochemical active material; particularly relate to the nano metal simple substance reduction high-valency metal compound generated in course of reaction; the nano carbon material generated can improve the electron conduction of final electrochemical active material; building-up process is without carbon consumption; the gas oxygen compound of carbon-free, nitrogen, phosphorus is discharged, and is conducive to the preparation method of environmental protection.
Background technology
Since Goodenough laboratory in 1997 reports that lithium ion is at LiFePO
4in the de-embedding process of electrochemistry reversible after, the olivine-type positive electrode LiMPO with ordered structure
4(M=Fe, Mn, Co, Ni, V) just has been subject to paying attention to widely, is regarded as the Postive electrode material of li-ion accumulator that the utmost point has application potential.
LiFePO 4 (LiFePO
4) cheap, material non-toxic environmental protection, crystal structure is stable, and overcharging resisting and the ability of excessively putting are strong, theoretical capacity higher (170mAh/g), cycle performance is good, but its electrochemistry platform lower (3.4V), tap density is lower, cause the volume and weight specific capacity lower, in addition, LiFePO
4electronic conductivity lower, cause high rate performance poor, limited its practical application.
With LiFePO
4liMnPO with identical olivine structural
4, LiCoPO
4, Li
3v
2(PO
4)
3also be subject in recent years extensive concern, the relatively high LiMnPO of the electrochemistry platform of this different materials
4(4.1V), LiCoPO
4(4.8V), Li
3v
2(PO
4)
3(4.6V), but because olivine structural is very stable, only have less change in volume (6%) in charge and discharge process, the oxygen of its approximate Hexagonal packing-metal ion is arranged closely, make the electron conductivity of material itself very low, and conductivity is to affect LiMPO
4the principal element of specific capacity and high rate capability, therefore improve LiMPO by the doping high conductive material
4conductive capability be the most effective solution route at present.
Nano carbon material determines because of the atomic structure of its unique one dimension the electrical conductivity performance that it is special, in the building-up process of anode material for lithium-ion batteries, add nano carbon material as the electrode material conductive agent, can improve the battery specific capacity, improve cycle performance of battery and high rate capability.But add carbon in synthetic, can produce great amount of carbon dioxide, be disposed in atmosphere and pollute.For overcoming the above problems, the present invention comes therefrom.
Summary of the invention
The object of the invention is to provide a kind of preparation method of electrochemical active material, the properties of product of preparing are good, adopt carbon-free synthesis technique simultaneously, utilize the nano metal simple substance reduction high-valency metal compound generated in course of reaction, avoid the gas oxygen compound of carbon, nitrogen, phosphorus to discharge, be conducive to environmental protection.
Technical scheme of the present invention is:
A kind of preparation method of electrochemical active material, is characterized in that, the molecular formula of described electrochemical active material is Li
ym
xn
1-x(PO
4)
y, wherein M and N are transition-metal Fe, Co, Ni, Mn or V, y=1~3, x=1~3; It is metallic catalyst that described preparation method selects one or more in the compound of manganese, iron, cobalt, nickel, vanadium, and above-mentioned metallic catalyst and carbon source, ,Lin source, lithium source, high-valency metal compound are made to slurry; By above-mentioned pulp jets, in the reacting furnace that inert gas shielding is arranged, reaction temperature is 500-800 ℃, 2~8 hours reaction time; Product is cooling in inert gas.
Generate rich metal simple-substance nano carbon material in above-mentioned electrochemical active material building-up process, wherein highly active nano metal simple substance is used for reducing the high-valency metal compound, and nano carbon material is for improving final electrochemical active material conductive capability.
In above-mentioned course of reaction; the generating principle of rich metal simple-substance nano carbon material is to pass through chemical vapour deposition technique; take excessive metallic compound as catalyst, hydro carbons and derivative thereof be carbon source; under inert gas shielding; in 500 ℃~800 ℃ scopes, the free carbon ion that the hydrocarbon cracking in carbon source produces can generate the rich metal simple-substance nano carbon material of single wall or many walls under catalyst action.
Preferably, described metallic catalyst is manganese, iron, cobalt, nickel, vanadium oxide, hydroxide, acylate, Metallocenic compound and derivative thereof, metal carbonyl and derivative.
Preferably, described carbon source be hydro carbons with and derivative, comprise one or more of liquid alkane class, methyl alcohol, ethanol, ethylene glycol, propyl alcohol, isopropyl alcohol, glycerol, acetone, benzene,toluene,xylene, polyethylene, polyvinyl alcohol, polyethylene glycol, oleic acid.
Preferably, described lithium source is one or more in lithium hydroxide, lithium dihydrogen phosphate, phosphoric acid hydrogen two lithiums, lithium phosphate, lithium oxalate, lithium acetate.
Preferably, described high-valency metal compound is respectively manganese oxide, manganese dioxide; Iron oxide, tri-iron tetroxide; Cobalt oxide, cobalt sesquioxide; Vanadic oxide, vanadium dioxide.
Preferably, described phosphorus source is one or more in ammonium di-hydrogen phosphate, DAP, lithium dihydrogen phosphate, phosphorus pentoxide.
Preferably, described reacting furnace is the reacting furnace with the sprayed feed system.The ball milling rotary furnace of the described pulp jets charging of Chinese invention patent ZL201010572490.4 that is the inventor with the reacting furnace of sprayed feed system.
Preferably, described metallic catalyst and carbon source are by 5~1:1 mixed in molar ratio.
Preferably, described inert gas is preferably one or more combination of gases of argon gas, nitrogen, helium, ammonia, hydrogen.
Preferably, one or more mixing that the nano carbon material generated in described course of reaction is CNT (carbon nano-tube), nano carbon microsphere, nanometer carbon plate.
Preparation method of the present invention is from general to adopt carbon to reduce high valence state oxide processing LiFePO 4 different, adopt the nano metal simple substance reduction high-valency metal compound generated in course of reaction, carry out redox reaction without carbon, can not produce carbon dioxide, thereby be conducive to environmental protection, the stable nano carbon material simultaneously generated contributes to improve the conductivity of finished electrode material, and chemical property is better.
Advantage of the present invention is:
1. generate rich nano metal simple substance carbon material in course of reaction, prepare the nano carbon material of required tenor by mixed proportion, generated time and the temperature of controlling metallic catalyst and carbon source.
2. material is synthetic in the reacting furnace with the sprayed feed system, is subject to the inert gas shielding metal not oxidized, and be beneficial to material and fully react synthetic,
3. the appearance structure of synthetic material, particle size distribution, tap density, specific area and chemical property are good.
4. the present invention selects the environmental friendliness material to be processed, and meets the environmental protection needs.
5. the electrochemical active material that prepared by the present invention, compare existing LiMPO4 material list and reveal and have good electrochemical stability, and charge/discharge capacity is high, energy is high, high rate performance is good.
The accompanying drawing explanation
Below in conjunction with drawings and Examples, the invention will be further described:
Fig. 1 is the reacting furnace with the sprayed feed system that course of reaction of the present invention is used;
Wherein: 1 baffle plate; 2 sprayed feed systems; 3 boiler tubes; 4 ball milling heating intervals; 5 conventional heating intervals; 6 discharge systems; 7 baffle plates; 8 ball-milling mediums; 9 bases.
Fig. 2 is specific embodiment 1 resulting materials X-ray diffraction spectrogram;
Fig. 3 is specific embodiment 1 resulting materials charge discharge curve chart;
Fig. 4 is specific embodiment 2 resulting materials X-ray diffraction spectrograms;
Fig. 5 is specific embodiment 2 resulting materials charge discharge curve charts;
Fig. 6 is specific embodiment 3 resulting materials X-ray diffraction spectrograms;
Fig. 7 is specific embodiment 3 resulting materials charge discharge curve charts;
Concrete methods of realizing:
Below in conjunction with specific embodiment, such scheme is described further.Should be understood that these embodiment are not limited to restriction system scope of the present invention for the present invention is described.The implementation condition adopted in embodiment can be done further adjustment according to physical condition, and not marked implementation condition is generally the condition in normal experiment.
Embodiment 1
Two luxuriant manganese, di-iron trioxide, lithium dihydrogen phosphate, benzene are mixed according to mol ratio 4:1:6:1; grinding machine for grinding 10h in inert gas shielding; make slurry; above-mentioned slurry is passed through to the sprayed feed system; be ejected into the front end pre-reaction zone of reacting furnace with the 100mL/min flow, course of injection and reacting furnace all have inert gas shielding.Slurry is wink-dry in the reacting furnace of high temperature anaerobic, and volatile benzene and the luxuriant manganese of catalyst two generates rich manganese carbon material at baffle plate 1 place, and oarse-grained di-iron trioxide and lithium dihydrogen phosphate drop on ball-milling medium 8 places and generate ferric lithium phosphate precursors.Along with material in stove evenly mixes, pulverizes, rich manganese carbon material and ferric lithium phosphate precursor enter into the reative cell of 650 ℃, and after constant temperature 4h, product was both obtained by the inert gas shielding cool to room temperature at the reacting furnace afterbody.
The generating principle of rich manganese carbon material is: the two luxuriant manganese of take are catalyst, and benzene is carbon source, by the chemical vapour deposition (CVD) principle, and the synthetic nano carbon material that is rich in metal simple-substance;
Phosphatic generating principle:
Sample XRD diffraction analysis: as shown in Figure 2, in the X ray collection of illustrative plates, there is no dephasign, is iron manganese phosphate for lithium pure phase monocline, and crystal grain is on average in 80 nanometers.
Electrochemical property test: the iron manganese phosphate for lithium prepared is above made to pole piece, and electro-chemical test is selected metal lithium sheet to electrode.Through electro-chemical test, the material initial discharge capacity that the present embodiment is prepared is 160mAh/g.
Embodiment 2
Ferrocene, di-iron trioxide, lithium dihydrogen phosphate, benzene are mixed according to mol ratio 3:3:9:1; grinding machine for grinding 10h in inert gas shielding; make slurry; above-mentioned slurry is passed through to the sprayed feed system; be ejected into the front end pre-reaction zone of reacting furnace with the 100mL/min flow, course of injection and reacting furnace all have inert gas shielding.Slurry is wink-dry in the reacting furnace of high temperature anaerobic, and volatile benzene and catalyst ferrocene generate rich iron carbon material at baffle plate 1 place, and oarse-grained di-iron trioxide and lithium dihydrogen phosphate drop on ball-milling medium 8 places and generate ferric lithium phosphate precursors.Along with material in stove evenly mixes, pulverizes, rich iron carbon material and ferric lithium phosphate precursor enter into the reative cell of 650 ℃, and after constant temperature 4h, product was both obtained by the inert gas shielding cool to room temperature at the reacting furnace afterbody.
The generating principle of rich iron carbon material is: take ferrocene as catalyst, benzene is carbon source, by the chemical vapour deposition (CVD) principle, and the synthetic nano carbon material that is rich in metal simple-substance;
Phosphatic generating principle:
3LiH
2PO
4+Fe
2O
3+Fe→3LiFePO
4+3H
2O
Sample XRD diffraction analysis: as shown in Figure 2, in the X ray collection of illustrative plates, there is no dephasign, is LiFePO4 pure phase monocline, and crystal grain is on average in 60 nanometers.
Electrochemical property test: the LiFePO4 prepared is above made to pole piece, and electro-chemical test is selected metal lithium sheet to electrode.Through electro-chemical test, the material initial discharge capacity that the present embodiment is prepared is 160mAh/g.
Embodiment 3
Two luxuriant vanadium, vanadic oxide, lithium dihydrogen phosphate, benzene are mixed according to mol ratio 4:3:15:1; grinding machine for grinding 10h in inert gas shielding; make slurry; above-mentioned slurry is passed through to the sprayed feed system; be ejected into the front end pre-reaction zone of reacting furnace with the 100mL/min flow, course of injection and reacting furnace all have inert gas shielding.Slurry is wink-dry in the reacting furnace of high temperature anaerobic, and volatile benzene and the luxuriant vanadium of catalyst two generate rich vanadium carbon material at baffle plate 1 place, and oarse-grained vanadic oxide and lithium dihydrogen phosphate drop on ball-milling medium 8 places and generate the phosphoric acid vanadium lithium presomas.Along with material in stove evenly mixes, pulverizes, rich vanadium carbon material and phosphoric acid vanadium lithium presoma enter into the reative cell of 700 ℃, and after constant temperature 4h, product was both obtained by the inert gas shielding cool to room temperature at the reacting furnace afterbody.
The generating principle of rich vanadium carbon material is: the two luxuriant vanadium of take are catalyst, and benzene is carbon source, by the chemical vapour deposition (CVD) principle, and the synthetic nano carbon material that is rich in metal simple-substance;
Phosphatic generating principle:
15LiH
2PO
4+3V
2O
5+4V→5Li
3V
2(PO
4)
3+15H
2O
Sample XRD diffraction analysis: as shown in Figure 2, in the X ray collection of illustrative plates, there is no dephasign, is phosphoric acid vanadium lithium pure phase structure, and crystal grain is on average in 70 nanometers.
Electrochemical property test: the phosphoric acid vanadium lithium pole piece prepared in the above, electro-chemical test is selected metal lithium sheet to electrode.Through electro-chemical test, the material initial discharge capacity that the present embodiment is prepared is 178mAh/g.
Above-mentioned example is only explanation technical conceive of the present invention and characteristics, and its purpose is to allow the person skilled in the art can understand content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalent transformations that Spirit Essence is done according to the present invention or modification, within all should being encompassed in protection scope of the present invention.