Summary of the invention
The purpose of this invention is to provide a kind of cathode material lithium vanadium phosphate of lithium ion battery and preparation method thereof, the technical problem that solve is to improve the purity of positive electrode, simplifies the operating procedure in the synthetic method, reduces production costs.
The present invention is by the following technical solutions: a kind of cathode material lithium vanadium phosphate of lithium ion battery, described positive electrode has phosphoric acid vanadium lithium Li
3V
2(PO
4)
3Matrix, matrix is coated with material with carbon element, and positive electrode has almost spherical that sphere, major and minor axis are 5~30 μ m, rhombus, taper, sheet, stratiform or/and block microscopic feature, and its granularity is 5~30 μ m, and specific area is 5~15m
2/ g.
A kind of preparation method of cathode material lithium vanadium phosphate of lithium ion battery may further comprise the steps: one, the preparation of nano particle: respectively water-insoluble Li source compound, vanadium source compound, P source compound and complexing agent are passed through the wet method super-fine ball-milling treatment to sub-micron or nano-scale particle; Two, liquid-phase mixing reaction: by the ratio Li of amount of substance: V: P: L (complexing agent)=(3.0~3.3): 2: 3: (1.5~2.2) take by weighing Li source compound, vanadium source compound, P source compound and complexing agent and are dissolved in 40~90 ℃ of deionized waters, stir and obtain composite material in 1~3 hour; Three, the preparation of precursor: with composite material ball milling 0.5~12 hour under the rotating speed of 200~500r/min, spray drying obtains anode material precursor under 100~360 ℃ of conditions then, precursor be shaped as almost spherical that sphere, major and minor axis are 5~30 μ m, rhombus, taper, sheet, stratiform or/and block post forming particle; Four, preliminary treatment: the post forming particle under inert atmosphere protection, 200~450 ℃ of preliminary treatment 2~6 hours, is obtained the preliminary treatment powder behind the natural cooling; Five, calcination process: in corundum or graphite saggar, calcination process is 5~12 hours under inert atmosphere protection, in 600~950 ℃ with the preliminary treatment powder packing, is cooled to room temperature then naturally, obtains Li
3V
2(PO
4)
3Matrix; Six, with Li
3V
2(PO
4)
3But matrix surface coats the organic substance of charing, handles under 500~1200 ℃ temperature 1~12 hour then.
Li source compound of the present invention is lithium hydroxide LiOH, lithium carbonate Li
2CO
3, lithium acetate LiCH
3COO, lithium chloride, lithium sulfate, lithium nitrate, lithium iodide, tert-butyl alcohol lithium, lithium benzoate, lithium formate, lithium fluoride, lithium chromate, four water citric acid lithiums, tetrachloro-lithium aluminate, lithium bromide, LiBF4 or lithium oxalate; Described vanadium source compound is vanadic oxide V
2O
5, vanadium trioxide V
2O
3, vanadium dioxide VO
2, ammonium metavanadate NH
4VO
3, sodium metavanadate or carbonic acid vanadium; Described P source compound is phosphoric acid H
3PO
4, ammonium phosphate (NH
4)
3PO
4, diammonium hydrogen phosphate (NH
4)
2HPO
4, ammonium dihydrogen phosphate NH
4H
2PO
4, phosphorus pentoxide P
2O
5, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium hydrogen phosphate or dipotassium hydrogen phosphate; Described complexing agent is sucrose, glucose, tartaric acid, citric acid, urea, acrylic acid, fructose, ascorbic acid, polyethylene glycol or glycerol.
Wet method super-fine ball-milling treatment of the present invention adopts ball milling or disintegrating apparatus, and ball milling or disintegrating apparatus are stirring ball mill, sand mill, colloidal mill, airslide disintegrating mill, impact type micro ball-mill, air-flow spiral pulverizing mill, impact grinder or bar type mechanical crusher.
Method of the present invention is by the ratio Li of amount of substance: V: P: L (complexing agent)=(3.0~3.3): 2: 3: (1.5~2.2) take by weighing Li source compound, vanadium source compound, P source compound and complexing agent, earlier Li source compound, vanadium source compound and P source compound solids are mixed, complexing agent is dissolved in 40~90 ℃ of deionized waters, the solids that mixes is dissolved in the enveloping agent solution, 40~90 ℃ were stirred 1~3 hour down again; Or P source compound is dissolved in 40~90 ℃ of deionized waters, again complexing agent, Li source compound, vanadium source compound solids are added in the P source compound solution successively, 40~90 ℃ were stirred 1~3 hour down; Or be dissolved in 40~90 ℃ of deionized waters respectively Li source compound, vanadium source compound, P source compound and complexing agent and stirring, contain Li source compound, vanadium source compound and the enveloping agent solution that will prepare then add in the P source compound solution, and 40~90 ℃ were stirred 1~3 hour down.
Composite material of the present invention ball milling under the rotating speed of 200~500r/min adopts stirring ball mill, circulating agitating ball mill, sand mill, colloid mill, planetary ball mill or impact type micro mist balling machine, and ball grinder and abrading-ball material are stainless steel, corundum, zirconia or agate.
Method of the present invention before the ball milling, adds the doping vario-property agent that accounts for composite material 1~3wt.% with composite material under the rotating speed of 200~500r/min.
Doping vario-property agent of the present invention is compound, conductive acetylene carbon black (Super-P), carbon fiber, carbon nano-tube or the nano-sized carbon microballoon of Fe, Zr, Zn, Ti, Al, Mg, Cu, Cr, Ni, Ge or Nb element.
Method of the present invention is spray drying under 100~360 ℃ of conditions, carries out in centrifugal spray granulating and drying machine.
Before preliminary treatment under the inert atmosphere protection, fusion treatment is 0.5~2 hour under the rotating speed of 200~1100r/min with the post forming particle for method of the present invention.
Inert protective gas of the present invention adopts helium He, argon Ar or nitrogen N
2
Method heat treatment of the present invention is carried out in enclosed vacuum drying oven, vacuum drier, box type furnace, tube furnace, vacuum furnace, middle cover stove, rotary furnace or tunnel cave.
Before the method calcination process of the present invention, on the fusion machine, fusion treatment is 0.5~4 hour under the rotating speed of 200~1100r/min with the preliminary treatment powder; The phosphoric acid vanadium lithium that obtains after the calcination process is with fusion machine fusion treatment 0.5~4 hour under the rotating speed of 200~1100r/min.
Pulverize after method roasting of the present invention, the fusion treatment and the classification processing.
Method of the present invention is pulverized and is adopted pulverizing at a high speed and low speed to pulverize the method that combines, and pulverizes at a high speed and adopts airslide disintegrating mill, high pressure flour mill or bar type mechanical crusher; Low speed is pulverized and is adopted low velocity impact formula nodularization pulverizer, air-flow vortex formula pulverizer, micronizer, ultra micro ball mill, internal classification impact type micro mist pulverizer or pendulum type ring roll pulverizer; Classification adopts gas flow sizing machine, jet classifying machine, sub-micron grader or ultra micro rice gas flow sizing machine to handle.
But but the organic substance of coating charing of the present invention adopts the matrix and the organic substance of charing to mix coating 0.5~6 hour on fusion machine, blade paddle mixer, conical agitator, twin-shaft mixer or planetary stirring machine mixing mixing plant, afterwards with compound carbonization treatment 1~12 hour under 500~1200 ℃ temperature.
But the organic substance of charing of the present invention is furane resins, Lauxite, ethyl-amine resin, phenolic resins, epoxy resin, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, Kynoar, polyacrylonitrile, butadiene-styrene rubber (SBR), cellulose (CMC), coke, coal tar pitch or petroleum asphalt, and covering amount is 1~3wt.% of matrix.
The present invention compared with prior art, utilize nano particle post forming liquid phase method to synthesize anode material vanadium lithium phosphate, little and the even dispersion of the particle of synthetic material, the purity height of product, carbon is full and uniform to the coating of active material, stoped particle agglomeration effectively, synthetic phosphoric acid vanadium lithium positive electrode has 4V above discharge voltage and 3 discharge voltage plateau zones, higher charge/discharge capacity, excellent cyclical stability, and this material is compared with lithium cobalt oxide as positive electrode material and is also had the low and safe advantage of cost, the synthetic phosphoric acid vanadium lithium of liquid phase method has guaranteed that reactant can carry out hybrid reaction on the molecule rank, sufficient reacting, need not the pH value of strict control solution, simplified operation sequence, reduced production cost, help the purity of processing procedure control and raising synthetic material, more be applicable to suitability for industrialized production.Phosphoric acid vanadium lithium positive electrode of the present invention is assembled into simulated battery with metal lithium sheet, with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage was 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reached respectively greater than 125mAh/g and 165mAh/g, coulombic efficiency is greater than 95% first, the capability retention after 40 weeks of circulating is greater than 96%.
Embodiment
Below in conjunction with embodiment the present invention is described in further detail.Cathode material lithium vanadium phosphate of lithium ion battery of the present invention has phosphoric acid vanadium lithium Li
3V
2(PO
4)
3Matrix, matrix is coated with material with carbon element, and positive electrode has almost spherical that sphere, major and minor axis are 5~30 μ m, rhombus, taper, sheet, stratiform or/and block microscopic feature, and its granularity is 5~30 μ m, and specific area is 5~15m
2/ g.
The preparation method of cathode material lithium vanadium phosphate of lithium ion battery of the present invention, adopt following steps:
One, the preparation of nano particle: respectively water-insoluble Li source compound, vanadium source compound, P source compound and complexing agent are passed through the wet method super-fine ball-milling treatment to sub-micron or nano-scale particle; Adopt ball milling or disintegrating apparatus, ball milling or disintegrating apparatus are stirring ball mill, sand mill, colloidal mill, airslide disintegrating mill, impact type micro ball-mill, air-flow spiral pulverizing mill, impact grinder or bar type mechanical crusher.
Two, liquid-phase mixing reaction: by the ratio Li of amount of substance: V: P: L (complexing agent)=(3.0~3.3): 2: 3: (1.5~2.2) take by weighing Li source compound, vanadium source compound, P source compound and complexing agent and are dissolved in 40~90 ℃ of deionized waters, stir and obtain composite material in 1~3 hour; Or earlier Li source compound, vanadium source compound and P source compound solids are mixed, complexing agent is dissolved in 40~90 ℃ of deionized waters, the solids that mixes is dissolved in the enveloping agent solution again, and 40~90 ℃ were stirred 1~3 hour down; Or P source compound is dissolved in 40~90 ℃ of deionized waters, again complexing agent, Li source compound, vanadium source compound solids are added in the P source compound solution successively, 40~90 ℃ were stirred 1~3 hour down; Or Li source compound, vanadium source compound, P source compound and complexing agent divided or be dissolved in 40~90 ℃ of deionized waters respectively and stir, contain Li source compound, vanadium source compound and the enveloping agent solution that will prepare then add in the P source compound solution, and 40~90 ℃ were stirred 1~3 hour down.
Three, the preparation of precursor: add the doping vario-property agent that accounts for composite material 1~3wt.% in composite material, the doping vario-property agent is compound, conductive acetylene carbon black Super-P, carbon fiber, carbon nano-tube or the nano-sized carbon microballoon of Fe, Zr, Zn, Ti, Al, Mg, Cu, Cr, Ni, Ge or Nb element; Adopt stirring ball mill, circulating agitating ball mill, sand mill, colloid mill, planetary ball mill or impact type micro mist balling machine, ball grinder and abrading-ball material are stainless steel, corundum, zirconia or agate, with composite material ball milling 0.5~12 hour under the rotating speed of 200~500r/min, then under 100~360 ℃ of conditions, in centrifugal spray granulating and drying machine, carry out drying and obtain anode material precursor, precursor be shaped as sphere, major and minor axis is the almost spherical of 5~30 μ m, rhombus, taper, sheet, stratiform is or/and block post forming particle.
Four, preliminary treatment: with the post forming particle after fusion treatment 0.5~2 under the rotating speed of 200~1100r/min, in inert gas helium He, argon Ar or nitrogen N
2Under the protection, 200~450 ℃ of preliminary treatment 2~6 hours, obtain the preliminary treatment powder behind the natural cooling; Preliminary treatment is carried out in enclosed vacuum drying oven, vacuum drier, box type furnace, tube furnace, vacuum furnace, middle cover stove, rotary furnace or tunnel cave.
Five, fusion treatment: on the fusion machine, fusion treatment is 0.5~4 hour under the rotating speed of 200~1100r/min with the preliminary treatment powder, improves the uniformity of material.
Six, calcination process: in corundum or graphite saggar, calcination process is 5~12 hours under inert atmosphere protection, in 600~950 ℃ with the preliminary treatment powder packing, is cooled to room temperature then naturally, obtains Li
3V
2(PO
4)
3Matrix.
Seven, the Li that obtains after the calcination process
3V
2(PO
4)
3Matrix is with fusion machine fusion treatment 0.5~4 hour under the rotating speed of 200~1100r/min.
Eight, pulverize after the fusion treatment and classification is handled, pulverize to adopt earlier and pulverize at a high speed, the method that back low speed is pulverized is pulverized employing airslide disintegrating mill, high pressure flour mill or bar type mechanical crusher at a high speed; Low speed is pulverized and is adopted low velocity impact formula nodularization pulverizer, air-flow vortex formula pulverizer, micronizer, ultra micro ball mill, internal classification impact type micro mist pulverizer or pendulum type ring roll pulverizer; Classification adopts gas flow sizing machine, jet classifying machine, sub-micron grader or ultra micro rice gas flow sizing machine to handle.
Nine, with Li
3V
2(PO
4)
3But matrix surface coats the organic substance of charing, but matrix and the organic substance of charing mix on fusion machine, blade paddle mixer, conical agitator, twin-shaft mixer or planetary stirring machine mixing mixing plant and coated 0.5~6 hour, afterwards with compound carbonization treatment 1~12 hour under 500~1200 ℃ temperature.But the organic substance of charing is furane resins, Lauxite, ethyl-amine resin, phenolic resins, epoxy resin, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, Kynoar, polyacrylonitrile, styrene butadiene rubber sbr, cellulose CMC, coke, coal tar pitch or petroleum asphalt, and covering amount is 1~3wt.%. of matrix.
Li source compound is lithium hydroxide LiOH, lithium carbonate Li
2CO
3, lithium acetate LiCH
3COO, lithium chloride, lithium sulfate, lithium nitrate, lithium iodide, tert-butyl alcohol lithium, lithium benzoate, lithium formate, lithium fluoride, lithium chromate, four water citric acid lithiums, tetrachloro-lithium aluminate, lithium bromide, LiBF4 or lithium oxalate; Described vanadium source compound is vanadic oxide V
2O
5, vanadium trioxide V
2O
3, vanadium dioxide VO
2, ammonium metavanadate NH
4VO
3, sodium metavanadate or carbonic acid vanadium; Described P source compound is phosphoric acid H
3PO
4, ammonium phosphate (NH
4)
3PO
4, diammonium hydrogen phosphate (NH
4)
2HPO
4, ammonium dihydrogen phosphate NH
4H
2PO
4, phosphorus pentoxide P
2O
5, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium hydrogen phosphate or dipotassium hydrogen phosphate; Described complexing agent is sucrose, glucose, tartaric acid, citric acid, urea, acrylic acid, fructose, ascorbic acid, polyethylene glycol or glycerol.
Embodiment 1
It is sub-micron or nanometer scale that raw material lithium carbonate, ammonium metavanadate, glucose are crushed to granularity through circulating agitating ball mill respectively, accurately takes by weighing lithium carbonate (Li
2CO
3) 54.4 the gram, ammonium metavanadate (NH
4VO
3) 114.8 the gram, phosphoric acid (H
3PO
4) 169.7 grams and glucose 176.6 gram be dissolved in 150 milliliters of 60 ℃ of deionized waters constant temperature stirring 3 hours respectively; Glucose solution is added in the phosphoric acid solution earlier, lithium carbonate and ammonium metavanadate solution are added successively again, 60 ℃ of constant temperature stirs and reacted completely to mixed solution in 2 hours, does not have bubble to produce.
Above-mentioned sample is added 1wt.%ZrO
2Back ball milling (QM-1SP4 planetary ball mill) 1 hour under the rotating speed of 300r/min; spray-drying process in centrifugal spray granulating and drying machine, under 100 ℃ of conditions; then product is placed under the argon shield and handled 4 hours down at 300 ℃, obtain the pretreatment sample powder behind the natural cooling at tube furnace.
Gained pretreatment sample powder is adopting fusion machine (the star technological development IQM-50 of Co., Ltd is opened in Luoyang) fusion treatment after 1 hour under the rotating speed of 200r/min; place under the argon shield and handled 9 hours down for 750 ℃ at tube furnace; naturally cool to room temperature, obtain the cathode material lithium vanadium phosphate of lithium ion battery matrix through pulverizing, shaping, classification after 1.5 hours through the 1000r/min fusion treatment.Above-mentioned phosphoric acid vanadium lithium matrix mixed coating 0.5 hour with 3wt%SBR, and 1000 ℃ of following carbonization treatment 5 hours.The modified phosphate vanadium lithium material for preparing ground and did X-ray diffraction X ' the PertPRO diffractometer of company (Dutch PANalytical) behind 200 mesh sieves, ESEM (the KYKY-2800B type ESEM of Beijing KYKY Technology Development Co., Ltd.) is analyzed and electrochemical property test.Synthetic phosphoric acid vanadium lithium positive electrode for the almost spherical spherical, that major and minor axis is 5~30 μ m, rhombus, taper, sheet, stratiform or/and bulk, particle mean size d
50=28.14 μ m, specific area is 8.286m
2/ g.The electrochemical property test of simulated battery carries out on the new Weir battery testing system in Shenzhen; the positive pole of button simulated battery that is used for electric performance test is by synthetic sample, conductive agent acetylene black, the binding agent PVdF ratio according to 90: 5: 5; making solvent with NMP is applied on the Al paper tinsel after evenly; 120 ℃ of dryings are after 12 hours; spreading and to be die-cut into diameter be the 8.4mm disk; simulated battery is assembled in the MBRAUN glove box of argon shield and carries out H
2O and O
2Content be lower than 2ppm, negative pole is a metal lithium sheet, barrier film is Celgard2400, electrolyte is 1molL
-1LiPF
6/ DMC+DEC (volume ratio is 1: 1) is with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reaches 126.67mAh/g and 170.47mAh/g respectively, and coulombic efficiency is respectively 95.6% and 97.5% first, and the capability retention after 40 weeks of circulating is respectively 98.2% and 83.9%.The X-ray diffracting spectrum of the phosphoric acid vanadium lithium that liquid phase method of the present invention is synthetic is seen Fig. 1; The SEM of synthetic sample presoma sees Fig. 2; Sample is seen Fig. 3-1 and Fig. 3-2 at 500 times and 2000 times of following stereoscan photographs; Charging and discharging curve in 3.0-4.3V, 3.0-4.9V charging/discharging voltage scope is seen Fig. 4; In 3.0-4.3V, 3.0-4.9V charging/discharging voltage scope, 0.45mA/cm
2Charging and discharging currents density under the capacity cyclic curve see Fig. 5.
Embodiment 2
Feed hydrogen lithia, vanadic oxide, ammonium dihydrogen phosphate and the ball mill grinding of citric acid process to sub-micron or nanoscale, are accurately taken by weighing lithium hydroxide (LiOHH
2O) 48.76 grams, vanadic oxide (V
2O
5) 69.05 the gram, ammonium dihydrogen phosphate (NH
4H
2PO
4) 128.26 grams and citric acid 154.66 grams.Citric acid is dissolved in 800 milliliters of 80 ℃ of deionized waters, and constant temperature stirred 3 hours; Lithium hydroxide, vanadic oxide and ammonium dihydrogen phosphate are mixed back ball milling 0.5 hour under the rotating speed of 300r/min, then mixture is added in the citric acid solution, stirred 3 hours at 80 ℃ of following constant temperature, until reacting completely.
With above-mentioned sample and the Al that accounts for sample 3wt.%
2O
3Mix back ball milling 1 hour under the rotating speed of 400r/min, spray-drying process under 300 ℃ of conditions places product then under the argon shield and handled 4 hours down at 350 ℃ at tube furnace, obtains the presoma of phosphoric acid vanadium lithium behind the natural cooling.
The presoma of gained phosphoric acid vanadium lithium is adopting fusion machine fusion treatment after 1 hour under the rotating speed of 300r/min; place under the argon shield and handled 8 hours down for 800 ℃ at tube furnace; naturally cool to room temperature, through the 900r/min fusion treatment after 1.5 hours through obtaining the cathode material lithium vanadium phosphate of lithium ion battery matrix after pulverizing, shaping, the classification.Above-mentioned phosphoric acid vanadium lithium matrix mixed coating 4 hours with the 1wt% coal tar pitch, and 500 ℃ of following carbonization treatment 12 hours.The modified phosphate vanadium lithium material for preparing ground electrochemical property test behind 200 mesh sieves, synthetic phosphoric acid vanadium lithium positive electrode particle mean size d
50=23.42 μ m, specific area is 7.613m
2/ g, itself and metal lithium sheet are done negative pole and electrode are assembled into simulated battery (method and embodiment 1 are together), with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reaches 127.45mAh/g and 168.14mAh/g respectively, and coulombic efficiency is respectively 96.6% and 97.3% first, and the capability retention after 40 weeks of circulating is respectively 98.1% and 88.9%.
Embodiment 3
Lithium hydroxide, ammonium metavanadate, ammonium dihydrogen phosphate, citric acid raw material are milled to nanometer or submicron particles with sand mill respectively, accurately take by weighing lithium hydroxide (LiOHH
2O) 6.50 grams, ammonium metavanadate (NH
4VO
3) 11.59 the gram, ammonium dihydrogen phosphate (NH
4H
2PO
4) 17.11 grams and citric acid 15.47 grams.Lithium hydroxide, ammonium metavanadate and ammonium dihydrogen phosphate are dissolved in respectively in 60 milliliters of 70 ℃ of deionized waters, after the dissolving three kinds of solution are mixed, add citric acid then, constant temperature stirred 1.5 hours; Mixed liquor stirred 1 hour at 80 ℃ of following constant temperature, to reacting completely.
With above-mentioned solution ball milling 1 hour under the rotating speed of 300r/min, spray-drying process under 130 ℃ of conditions places product then under the nitrogen protection and handled 5 hours down at 350 ℃ at tube furnace, obtains the pretreatment sample powder behind the natural cooling.
Gained pretreatment sample powder is adopting fusion machine fusion treatment after 1.5 hours under the rotating speed of 300r/min; place under the nitrogen protection and handled 10 hours down for 800 ℃ at tube furnace; naturally cool to room temperature, the 1000r/min fusion treatment obtained the cathode material lithium vanadium phosphate of lithium ion battery matrix through pulverizing, shaping, classification after 1 hour.Above-mentioned phosphoric acid vanadium lithium matrix mixed coating 6 hours with the 2wt% coal tar pitch, and 1200 times carbonization treatment 1 hour.The phosphoric acid vanadium lithium material for preparing was done physical property test and electrochemical property test after grinding 200 mesh sieves.Synthetic phosphoric acid vanadium lithium positive electrode particle mean size d
50=17.14 μ m, specific area is 9.347m
2/ g, itself and metal lithium sheet are done negative pole and electrode are assembled into simulated battery (method and embodiment 1 are together), with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reaches 126.03mAh/g and 171.25mAh/g respectively, and coulombic efficiency is respectively 95.8% and 96.5% first, and the capability retention after 40 weeks of circulating is respectively 97.1% and 86.9%.
Embodiment 4
Lithium acetate, vanadic oxide and tartaric acid raw material are milled to the sub-micron order of magnitude or nanometer scale with impact type micro mist balling machine.Accurately take by weighing lithium acetate (LiCH
3COO2H
2O) 752.2 grams, vanadic oxide (V
2O
5) 451.1 the gram, phosphoric acid (H
3PO
4) 850.3 grams and tartaric acid 736.4 grams.Phosphoric acid is dissolved in 250 milliliters of 70 ℃ of deionized waters, and constant temperature stirred 2.5 hours; The tartaric acid that takes by weighing is added while stirring; Subsequently lithium acetate and vanadic oxide are stirred in the above-mentioned solution of adding successively, stirred 1.5 hours at 70 ℃ of following constant temperature, until reacting completely; Mixed solution is placed 100 ℃ dry 24 hours of baking oven, and this moment, solution parched fully.
Doping 1.5wt.% carbon nano-fiber after the above-mentioned dry sample fragmentation of crossing was adopted fusion machine fusion treatment 1 hour under the rotating speed of 800r/min; spray-drying process under 260 ℃ of conditions; then product is placed under the nitrogen protection and handled 3 hours down at 350 ℃, obtain the pretreatment sample powder behind the natural cooling at box type furnace.
Gained pretreatment sample powder is at ball milling under the rotating speed of 300r/min after 1 hour; place under the nitrogen protection and handled 10 hours down for 800 ℃ at box type furnace; naturally cool to room temperature, through the 900r/min fusion treatment after 1.5 hours through obtaining the cathode material lithium vanadium phosphate of lithium ion battery matrix after pulverizing, shaping, the classification.Above-mentioned phosphoric acid vanadium lithium matrix mixed coating 4 hours with the 2wt% coal tar pitch, and 700 ℃ of following carbonization treatment 9 hours.The phosphoric acid vanadium lithium material for preparing ground electrochemical property test behind 200 mesh sieves, synthetic phosphoric acid vanadium lithium positive electrode particle mean size d
50=15.68 μ m, specific area is 13.562m
2/ g, itself and metal lithium sheet are done negative pole and electrode are assembled into simulated battery (method and embodiment 1 are together), with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reaches 128.50mAh/g and 171.24mAh/g respectively, and coulombic efficiency is respectively 97.1% and 96.9% first, and the capability retention after 40 weeks of circulating is respectively 97.7% and 87.2%.
Embodiment 5
Lithium oxalate, vanadium trioxide and urea raw material are milled to submicron order with stirring ball mill.Accurately take by weighing lithium oxalate 408.0 grams, vanadium trioxide 367.7 grams, phosphorus pentoxide 522.4 grams and urea 147.3 grams.Phosphorus pentoxide is dissolved in 500 milliliters of 60 ℃ of warm water, stirred 1.5 hours; Again lithium oxalate, vanadium trioxide are stirred successively and add in the above-mentioned solution; Add urea at last; Constant temperature stirred 3 hours, reacted completely to mixed solution, did not have bubble to produce.
With above-mentioned solution spray-drying process under 280 ℃ of conditions, then product is placed under the nitrogen protection and handled 6 hours down at 300 ℃ at box type furnace, obtain the pretreatment sample powder behind the natural cooling.
Gained pretreatment sample powder is adopting fusion machine fusion treatment after 1 hour under the rotating speed of 600 r/min; place under the argon shield and handled 12 hours down for 800 ℃ at tube furnace; naturally cool to room temperature, add 2wt.%CMC and obtain the cathode material lithium vanadium phosphate of lithium ion battery matrix through 1000r/min fusion coating processing pulverizing again after 1.5 hours, shaping, classification.Above-mentioned phosphoric acid vanadium lithium matrix mixed coating 2 hours with 2wt%SBR, and 1000 ℃ of following carbonization treatment 4 hours.After grinding 200 mesh sieves, the phosphoric acid vanadium lithium material for preparing did electrochemical property test.Synthetic phosphoric acid vanadium lithium positive electrode particle mean size d
50=14.23 μ m, specific area is 7.286m
2/ g does negative pole and electrode is assembled into simulated battery (method and embodiment 1 are together) with metal lithium sheet, with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reaches 128.75mAh/g and 174.23mAh/g respectively, and coulombic efficiency is respectively 95.7% and 96.3% first, and the capability retention after 40 weeks of circulating is respectively 97.5% and 89.9%.
Embodiment 6
It is sub-micron or nanometer scale that raw material lithium carbonate, vanadic oxide and glucose are crushed to granularity through circulating agitating ball mill respectively, accurately takes by weighing lithium carbonate (Li
2CO
3) 81.6 the gram, vanadic oxide (V
2O
5) 135.4 the gram, phosphoric acid (H
3PO
4) 254.6 grams and glucose 264.9 restrains and be dissolved in respectively in 200 milliliters of 40 ℃ of deionized waters; Glucose solution is added in the phosphoric acid solution earlier, lithium carbonate and vanadic oxide solution are added successively again, 40 ℃ of constant temperature stirs and reacted completely to mixed solution in 3 hours, does not have bubble to produce.
With above-mentioned sample ball milling 12 hours under the rotating speed of 200r/min, spray-drying process under 180 ℃ of conditions places product then under the argon shield and handled 2 hours down at 450 ℃ at tube furnace, obtains the pretreatment sample powder behind the natural cooling.
Gained pretreatment sample powder is adopting fusion machine fusion treatment after 0.5 hour under the rotating speed of 1100r/min; place under the argon shield and handled 8 hours down for 600 ℃ at tube furnace; naturally cool to room temperature, obtain the cathode material lithium vanadium phosphate of lithium ion battery matrix through pulverizing, shaping, classification after 4 hours through the 200r/min fusion treatment.Above-mentioned phosphoric acid vanadium lithium matrix mixed coating with the 2wt%S polyacrylonitrile 3.5 hours,, did rerum natura and electrochemical property test after the modified phosphate vanadium lithium material for preparing grinds 200 mesh sieves 1200 ℃ of following carbonization treatment 1 hour.Synthetic phosphoric acid vanadium lithium positive electrode particle mean size d
50=18.22 μ m, specific area is 9.213m
2/ g.Do negative pole and electrode is assembled into simulated battery (method and embodiment 1 are together) with metal lithium sheet, with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reaches 126.54mAh/g and 170.12mAh/g respectively, and coulombic efficiency is respectively 96.6% and 97.8% first, and the capability retention after 40 weeks of circulating is respectively 97.8% and 86.7%.
Embodiment 7
Raw material lithium oxalate, vanadic oxide, ammonium dihydrogen phosphate and the ball mill grinding of citric acid process to sub-micron or nanoscale, are accurately taken by weighing lithium oxalate 75.0 grams, vanadic oxide 90.2 grams, ammonium dihydrogen phosphate 169.3 grams and citric acid 206.2 grams.Citric acid is dissolved in 800 milliliters of 90 ℃ of deionized waters, and constant temperature stirred 1 hour; Lithium oxalate, vanadic oxide and ammonium dihydrogen phosphate are mixed back ball milling 0.5 hour under the rotating speed of 500r/min, then mixture is added in the citric acid solution, stirred 1 hour at 90 ℃ of following constant temperature, until reacting completely.
With above-mentioned sample ball milling 0.5 hour under the rotating speed of 500r/min, spray-drying process under 360 ℃ of conditions places product then under the argon shield and handled 4 hours down at 200 ℃ at tube furnace, obtains the presoma of phosphoric acid vanadium lithium behind the natural cooling.
The presoma of gained phosphoric acid vanadium lithium is adopting fusion machine fusion treatment after 0.5 hour under the rotating speed of 1100r/min; place under the argon shield and handled 5 hours down for 950 ℃ at tube furnace; naturally cool to room temperature, through the 1100r/min fusion treatment after 0.5 hour through obtaining cathode material lithium vanadium phosphate of lithium ion battery after pulverizing, shaping, the classification.Above-mentioned phosphoric acid vanadium lithium mixed coating 4.5 hours with 2wt% epoxy resin, the back is 550 ℃ of following carbonization treatment 12 hours, and the modified phosphate vanadium lithium material for preparing ground electrochemical property test behind 200 mesh sieves, synthetic phosphoric acid vanadium lithium positive electrode particle mean size d
50=7.42 μ m, specific area is 14.34m
2/ g, itself and metal lithium sheet are done negative pole and electrode are assembled into simulated battery (method and embodiment 1 are together), with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, 3.0-4.9V, maximum discharge capacity reaches 127.05mAh/g and 169.54mAh/g respectively, coulombic efficiency is respectively 96.9% and 97.5% first, and the capability retention after 40 weeks of circulating is respectively 97.2.1% and 87.9%.
Comparative example
Make simulated battery as positive electrode according to embodiment 1 described simulated battery manufacture method with present commercialization cobalt acid lithium, with 0.45mA/cm
2Charging and discharging currents density discharge and recharge, when charging/discharging voltage is 3.0-4.3V, maximum discharge capacity is 146.35mAh/g, cobalt acid lithium only has discharge platform zone between the 3.0-4.3, average discharge volt is 3.7, the charging cut-ff voltage does not have capacity to increase when being higher than 4.3V, and coulombic efficiency is respectively 92.3% first, and the capability retention after 40 weeks of circulating is 95.2%.This shows that phosphoric acid vanadium lithium is at maximum discharge capacity, effect all is better than business-like lithium cobaltate cathode material aspect coulombic efficiency, average discharge volt and the circulation volume conservation rate first.
The present invention adopts nano particle (precursor) liquid phase reactor to prepare cathode material lithium vanadium phosphate of lithium ion battery.Nano particle has solved synthetic middle maximum difficult point---the homogeneity question of dispersing and mixing of material, feasible synthetic material high conformity, the synthetic phosphoric acid vanadium lithium of liquid phase method has guaranteed that reactant can carry out hybrid reaction on the molecule rank, sufficient reacting, need not the pH value of strict control solution, the primary particle granularity of synthetic material is at the nanometer or the sub-micron order of magnitude, and second particle is spherical in shape or class is spherical, even particle size distribution.Complexing agent plays the reducing agent effect in the roasting reaction, unnecessary complexing agent then evenly is coated on the effect of playing enhancing conductivity on the active material after the carbonization.By adding Fe, Zr, Zn, Ti, Al, Mg, Cu, Cr, Ni, Ge, the compound of elements such as Nb and the conductive carbon material of high-specific surface area, as conductive acetylene carbon black Super-P, carbon fiber, carbon nano-tube or nano-sized carbon microballoon etc. carry out doping vario-property to material, perhaps material being carried out surface coating modification handles, but clad material is the organic substance of charing, as furane resins, Lauxite, ethyl-amine resin, phenolic resins, epoxy resin, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, Kynoar, polyacrylonitrile; styrene butadiene rubber sbr; cellulose CMC; coke; coal tar pitch or petroleum asphalt, covering amount are 1~3wt.%.The synthetic phosphoric acid vanadium lithium of liquid phase method has been simplified operation sequence, has reduced production cost, has been helped the purity that synthetic material was controlled and improved to processing procedure.
Li source compound only give an example out lithium hydroxide LiOH, lithium carbonate Li among the embodiment
2CO
3, lithium acetate LiCH
3COO and lithium oxalate, because lithium chloride, lithium sulfate, lithium nitrate, lithium iodide, tert-butyl alcohol lithium, lithium benzoate, lithium formate, lithium fluoride, lithium chromate, four water citric acid lithiums, tetrachloro-lithium aluminate, lithium bromide, LiBF4 has and above-mentioned four kinds of chemical property that material is similar, the chemical reaction type that participates in is identical, in preparation method's of the present invention reaction, all can provide the lithium ion of target compound phosphoric acid vanadium lithium, and then Li source compound is suitable for the present invention.
The vanadium source compound vanadic oxide V that only gives an example out among the same embodiment
2O
5, vanadium trioxide V
2O
3, ammonium metavanadate NH
4VO
3, because vanadium dioxide VO
2, sodium metavanadate is identical with above-mentioned three kinds of materials with electrochemical properties with the reaction type that the carbonic acid vanadium participates in chemical reaction in the method for the invention, all can provide the target compound phosphoric acid vanadium lithium required v element, and then the vanadium source compound is suitable for the present invention.
The P source compound phosphoric acid H that only gives an example out among the embodiment
3PO
4, ammonium dihydrogen phosphate NH
4H
2PO
4, phosphorus pentoxide P
2O
5, because ammonium phosphate (NH
4)
3PO
4, diammonium hydrogen phosphate (NH
4)
2HPO
4, that triammonium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium hydrogen phosphate or dipotassium hydrogen phosphate participate in the reaction type of chemical reaction in the present invention is identical with above-mentioned three kinds of materials with electrochemical properties, and the PO of target compound phosphoric acid vanadium lithium all can be provided by reaction
4 3-Group, and then P source compound is suitable for the present invention.
Only give an example out glucose, citric acid, urea, tartaric acid of complex compound among the embodiment, because it is identical with above-mentioned four kinds of materials with role that sucrose, acrylic acid, fructose, ascorbic acid, polyethylene glycol or glycerol participate in the reaction type of chemical reaction in the present invention, and then complexing agent is suitable for the present invention.
Only give an example out among the embodiment compound of doping vario-property agent Zr, Al, Fe,, compound, conductive acetylene carbon black Super-P, carbon fiber, carbon nano-tube or the nano-sized carbon microballoon of Zn, Ti, Mg, Cu, Cr, Ni, Ge or Nb element have the effect that improves the phosphoric acid vanadium lithium performance equally, so be suitable for the present invention.
Only give an example out styrene butadiene rubber sbr, cellulose CMC, pitch, polyacrylonitrile, epoxy resin of clad material among the embodiment, because furane resins, Lauxite, ethyl-amine resin, phenolic resins, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, Kynoar, coke product in carbonization reaction are identical or similar with above-mentioned five kinds of materials, can improve the electronic conductance of preparation material, and then improve the chemical property of material, so be suitable for the present invention.