CN102795611B - A kind of preparation method of LiFePO 4 material and a kind of lithium ion battery - Google Patents
A kind of preparation method of LiFePO 4 material and a kind of lithium ion battery Download PDFInfo
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- CN102795611B CN102795611B CN201110138709.4A CN201110138709A CN102795611B CN 102795611 B CN102795611 B CN 102795611B CN 201110138709 A CN201110138709 A CN 201110138709A CN 102795611 B CN102795611 B CN 102795611B
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Abstract
The invention provides a kind of preparation method of LiFePO 4 material, comprise the steps: step 1, ferric phosphate is scattered in alcohol solution, obtain the dispersion liquid of ferric phosphate; Step 2, lithium source is dissolved in alcohol solution, obtains the alcoholic solution in lithium source; Step 3, in the dispersion liquid of ferric phosphate, add the alcoholic solution in lithium source, then under reducing gas atmosphere or add reducing agent and react, after having reacted, obtain LiFePO 4 material.Present invention also offers a kind of lithium ion battery.The LiFePO 4 material particle adopting preparation method of the present invention to obtain is less, adopts that the specific capacity of the lithium ion battery of described LiFePO 4 material is higher and capability retention is better.
Description
Technical field
The present invention relates to technical field of lithium ion, more particularly, relate to a kind of preparation method of LiFePO 4 material.
Background technology
Lithium ion battery has been widely used in the fields such as mobile communication, notebook computer, video camera, camera, portable instrument as high-energy-density chemical power source, the electric automobile that Ye Shi various countries are studied energetically, the supporting power supply of the first-selection of space power system, become the first-selection of fungible energy source.In recent years, LiFePO
4become the study hotspot of active substance of lithium ion battery anode.LiFePO
4compared with other positive electrode active materials, there is good chemical property as positive electrode active material for lithium ion battery, charge and discharge platform is very steady, Stability Analysis of Structures in charge and discharge process, and there is the advantages such as nontoxic, pollution-free, security performance is good, can use in high temperature environments, raw material sources is extensive.
The preparation method of existing LiFePO 4 material mainly contains solid phase method, hydro thermal method, wherein, solid phase method technique is simple, realize the earliest in industrialization, and solid phase method can obtain the less and particle that capacity is higher of particle diameter, but solid phase method adopts traditional sand milling or ball-milling method and is mixed by raw material, the abrasion of equipment is inevitable, because equipment adopts steel or iron material to make usually, solid phase method inevitably introduces Fe impurity, and due to solid phase method be the reaction between solid and solid, there is the inhomogenous shortcoming of local reaction.Thus, the normal hydro thermal method that adopts prepares LiFePO 4 material at present, hydro thermal method can obtain the homogeneous material of performance, but hydro-thermal reaction inevitably can introduce iron hydroxide, phosphoric acid hydrogen is ferrous, lithium phosphate, the impurity such as phosphoric acid hydrogen two lithium, and due to the polarity of water larger, material is easy to reunite, thus makes that the capacity of obtained LiFePO 4 material is low, cycle efficieny is low.
Summary of the invention
The present invention be intended to solve existing LiFePO 4 material preparation method easily introduces impurity, raw material is easily reunited, make the obtained technical problem that LiFePO4 capacity is low, cycle efficieny is low.
The present inventor finds to adopt existing hydro thermal method to prepare LiFePO4, phosphoric acid there will be three grades and ionizes and introduce impurity in water, and because LiFePO4 is hydroaropic substance, it can be caused to reunite serious, unreacted material and impurity may be there is in the granule interior of reuniting together, the present inventor finds through long-term research, the hot legal system of alcohol is adopted to compensate for the deficiency of hydro thermal method for LiFePO4, because three grades of ionization can not appear in ferric phosphate in alcohol solution as in water, so there will not be impurity, and because the polarity of alcohol solution is less relative to water, solid particle dispersions is better, there will not be agglomeration, obtained LiFePO4 is made to have higher specific capacity and good capability retention.
The invention provides a kind of preparation method of LiFePO 4 material, described manufacture method comprises:
Step 1, ferric phosphate is scattered in alcohol solution, obtains the dispersion liquid of ferric phosphate;
Step 2, lithium source is scattered in alcohol solution, obtains the alcoholic solution in lithium source;
Step 3, in the dispersion liquid of ferric phosphate, add the alcoholic solution in lithium source, then under reducing gas atmosphere or add reducing agent and react, after having reacted, obtain LiFePO 4 material.
In the preparation method of LiFePO 4 material of the present invention, described lithium source is dissolve in one or more in the lithium source of alcohol solution.
In the preparation method of LiFePO 4 material of the present invention, described alcohol solution is selected from one or more in methyl alcohol, ethanol, propyl alcohol.
In the preparation method of LiFePO 4 material of the present invention, the consumption of described lithium source, ferric phosphate makes the mol ratio of Li:Fe:P for (0.95-1.05): 1:1.
In the preparation method of LiFePO 4 material of the present invention, in step 3, the condition of described reaction is: carry out in airtight reactor, be warming up to 120-220 DEG C, insulation 3-12 hour.
In the preparation method of LiFePO 4 material of the present invention, in step 3, the flow velocity controlling the alcoholic solution adding lithium source in the dispersion liquid of ferric phosphate is 100-1000ml/min.
In the preparation method of LiFePO 4 material of the present invention, in step 3, after the alcoholic solution adding lithium source, add pure water in proportion, then add alcohol solution to 5-10L.
In the preparation method of LiFePO 4 material of the present invention, the consumption of described pure water makes the mol ratio of H:P for (0.5-5): 1.
In the preparation method of LiFePO 4 material of the present invention, step 3 is carried out under reducing gas atmosphere, and the reducing gas passed into is CO, and flow velocity is 10-100L/h.
Present invention also offers a kind of lithium ion battery, the barrier film comprising positive pole, negative pole and be arranged between positive pole, negative pole, described positive pole comprises positive electrode collector and is coated on the positive electrode active materials on positive electrode collector, wherein, described positive electrode active materials adopts preparation method as above to prepare.
Ferric phosphate is scattered in alcohol solution by the preparation method of LiFePO 4 material of the present invention, and lithium source is scattered in alcohol solution, then the alcoholic solution in lithium source is added in the dispersion liquid of ferric phosphate and react, because ferric phosphate there will not be three grades of ionization in alcohol solution, so there will not be impurity, and because the polarity of alcohol solution is less relative to water, solid particle dispersions is better, there will not be agglomeration, obtained LiFePO 4 material particle is less, adopt the specific capacity of the lithium ion battery of described LiFePO 4 material higher, and capability retention is better.
Embodiment
The present inventor finds in water, to there will be three grades of ionization due to phosphoric acid, a lot of side reaction can be there is unavoidably in course of reaction, and the generation of side reaction will inevitably introduce impurity, such as: iron hydroxide, phosphoric acid hydrogen two lithium, phosphoric acid hydrogen is ferrous, lithium phosphate etc., the introducing of these impurity is verified will reduce discharging efficiency and the specific capacity of the material made greatly, and there is other uncertainty, reduce causing the performance of material significantly, and because LiFePO4 is hydroaropic substance, adopting existing hydro thermal method to prepare LiFePO4 can cause it to reunite seriously, unreacted material and impurity may be there is in the granule interior of reuniting together, the present inventor finds through long-term research, the hot legal system of alcohol is adopted to compensate for the deficiency of hydro thermal method for LiFePO4, because three grades of ionization can not appear in ferric phosphate in alcohol solution as in water, decrease the carrying out of side reaction, so there will not be impurity, and because the polarity of alcohol solution is less relative to water, solid particle dispersions is better, there will not be agglomeration, obtained LiFePO4 has higher specific capacity and good capability retention, and the performance of material is significantly promoted.
Accordingly, the invention provides a kind of preparation method of LiFePO 4 material, comprise the steps:
Step 1, prepare the alcoholic solution in lithium source: be scattered in by ferric phosphate in alcohol solution, obtain the dispersion liquid of ferric phosphate; In this step, joined by ferric phosphate in alcohol solution, then use dispersion machine, such as: Fluko dispersion machine high force dispersion, obtains the dispersion liquid of ferric phosphate, in the dispersion liquid of described ferric phosphate, the concentration of ferric phosphate is 1 ~ 5mol/L; Wherein, described ferric phosphate is nano ferric phosphate, and particle diameter is 50-500nm; In the present invention, adopt single ferric phosphate to replace phosphorus source, source of iron to prepare LiFePO 4 material, can avoid the generation of more side reaction, because raw-material kind is more, middle side reaction may increase, and to generating, final LiFePO 4 material is unfavorable; And if adopt Fe
2(PO
4)
3, because Fe/P ratio is less than 1, and solvent is nonaqueous solvents, can not form pure phase LiFePO4.One or more in described alcohol solution particular methanol, ethanol, propyl alcohol, ethylene glycol, isopropyl alcohol, one or more more preferably in absolute methanol, absolute ethyl alcohol, anhydrous propyl alcohol, make the dispersion effect of raw material better, and reduce the generation of side reaction.
Step 2, prepare the dispersion liquid of ferric phosphate: be scattered in alcohol solution by lithium source, obtain the alcoholic solution in lithium source; In this step, by being dissolved in alcohol solution by lithium source, obtain the alcoholic solution in lithium source, in the alcoholic solution in described lithium source, the concentration in lithium source is 1 ~ 5mol/L; Described lithium source is selected from one or more that dissolve in the lithium source of alcohol solution, and preferably, described lithium source is lithium acetate and/or lithium nitrate.Described alcohol solution can be selected from one or more in methyl alcohol, ethanol, propyl alcohol, isopropyl alcohol, one or more more preferably in absolute methanol, absolute ethyl alcohol, anhydrous propyl alcohol, makes the dispersion effect of raw material better, and reduces the generation of side reaction.This step adopt alcohol solution can identical from step 1 also can be different.
Step 3, in the dispersion liquid of ferric phosphate, add the alcoholic solution in lithium source, then under reducing gas atmosphere or add reducing agent and react, after having reacted, obtain LiFePO 4 material.In this step, preferably, first the dispersion liquid of ferric phosphate is added reactor, such as: in magnetic drive reactor, then be added drop-wise to lentamente by the alcoholic solution in lithium source in the dispersion liquid of ferric phosphate and obtain mixed liquor, in this process, the flow velocity controlling the alcoholic solution in lithium source is 100-1000ml/min, then adding pure water (when adopting anhydrous alcohol liquid) in proportion, finally mixed liquor alcohol solution being settled to 5-10L; Such as: for the reactor of 10L volume, can take nano ferric phosphate, with absolute ethyl alcohol constant volume to 1-4L, wherein, the concentration of ferric phosphate is 1 ~ 5mol/L; Take nanometer lithium acetate, be settled to 1-4L with absolute ethyl alcohol, wherein, the concentration of lithium acetate is that then 1 ~ 5mol/L adds pure water in proportion, then is settled to 5-10L with alcohol solution.
Wherein, one or more in described alcohol solution particular methanol, ethanol, propyl alcohol, ethylene glycol, isopropyl alcohol, more preferably one or more in absolute methanol, absolute ethyl alcohol, anhydrous propyl alcohol, the dispersion effect obtaining raw material is better, and reduces the generation of side reaction.This step adopt alcohol solution can from step 1,2 identical also can be different.Pass at once subsequently reducibility gas or inert gas (when add be reducing agent react time), the flow velocity of described reducibility gas or inert gas can be 10-100L/h, after ensureing that in reactor, all air displacement totally, closed reactor, is warming up to 120-220 DEG C, after at this temperature, constant temperature keeps 3-12h, cooling reactor, be down to after at 40 DEG C when temperature and open reactor, through reprocessing, obtain LiFePO 4 material.In the present invention, the reducing agent that this area such as ascorbic acid, citric acid is conventional can be added in mixed liquor, and; the protective atmosphere in reactor is made to be that inert gas atmosphere reacts; but preferably, react and carry out under reducibility gas atmosphere, described reducibility gas can select CO, H
2deng the one in reducibility gas; the effect of reducing agent and protective gas can be played simultaneously; in the present invention, preferred CO, because CO is dissolved in alcohol; and in reaction system; gas-liquid diffusion ratio liquid liquid diffusion velocity is faster, and the uniformity is higher, and reducing agent; such as: ascorbic acid is just slightly soluble in ethanol, in the hot method of alcohol, CO is thus adopted the overall performance of material can be made better as reducing agent.When system adopts absolute alcohol, such as: during absolute ethyl alcohol, described pure water adds as reactant, its consumption makes the mol ratio of H:P for (0.5-5): 1, water participates in the obtained LiFePO4 of reaction as a kind of raw material, the amount controlling pure water can prevent reaction from changing hydro thermal method into by the hot method of alcohol, and excessive water can affect the performance of the final LiFePO 4 material generated.
Described reprocessing comprises releases suspension liquid, suction filtration from reactor, obtains solid sediment; Solid sediment is first used pure water, and suction filtration, change slurry, then use absolute ethanol washing, LiFePO 4 material is obtained after oven dry, described reprocessing is used for reacted product and all the other residual effective areas not to open, and described reprocessing has been conventionally known to one of skill in the art, does not repeat at this.
Using preferred lithium acetate as lithium source, CO is example as reducing agent, and the reaction mechanism of LiFePO 4 material is: 0.5H
2o+FePO
4+ LiAc+0.5CO → LiFePO
4+ 0.5CO
2+ HAc, obtains LiFePO 4 material by above-mentioned reaction, and described LiFePO 4 material can be used as the positive electrode active materials of lithium ion battery.
Those skilled in the art will appreciate that because the electric conductivity of LiFePO 4 material is poor, thus usually need the Surface coating one deck carbon at LiFePO 4 material.The present invention is by joining in the alcoholic solution of carbon source by LiFePO 4 material, and change is starched, be dried to slurry no longer flows, and under inert gas shielding, then carries out sintering (temperature of sintering is 780 ± 50 DEG C) obtain bag carbon LiFePO 4 material.Wherein, described carbon source can be selected from the additive that well known to a person skilled in the art and can play electric action, such as, the luxuriant and rich with fragrance terpolymer of benzene naphthalene, the luxuriant and rich with fragrance bipolymer of benzene, benzene anthracene bipolymer can be selected from, gather one or more in benzene, soluble starch, polyvinyl alcohol, sucrose, glucose, urea, phenolic resins, furfural resin, Delanium, native graphite, superconduction acetylene black, acetylene black, carbon black and mesocarbon bead.
Further, present invention also offers a kind of lithium ion battery, comprising: positive pole, negative pole and the barrier film be arranged between positive pole, negative pole.Described negative pole comprises negative electrode collector and is coated on the negative active core-shell material on negative electrode collector, and described negative electrode collector can adopt Copper Foil, the negative active core-shell material that described negative active core-shell material can adopt this area common, such as: material with carbon element.Described negative active core-shell material is formed slurry be coated on negative electrode collector by interpolation binding agent, solvent, described bonding agent and solvent have no particular limits, the known bonding agent normally prepared for the negative pole of lithium ion battery and solvent, such as: CMC(sodium carboxymethylcellulose commonly used by binding agent), SBR (butadiene-styrene rubber) commonly used by solvent.
Described positive pole comprises substrate and is attached to the positive electrode on substrate.Substrate can adopt aluminium foil or nickel screen.The preparation method of positive pole has no particular limits, and can be to be obtained by slurry.Described positive electrode contains positive electrode active materials, bonding agent, and can contain conductive agent.Described lithium ion battery difference with the prior art is that described positive electrode active materials is prepared by preparation method of the present invention, namely adopts following step to prepare: step 1, be scattered in alcohol solution by ferric phosphate, obtains the dispersion liquid of ferric phosphate; Step 2, lithium source is dissolved in alcohol solution, obtains the alcoholic solution in lithium source; Step 3, in the dispersion liquid of ferric phosphate, add the alcoholic solution in lithium source, then under reducing gas atmosphere or add reducing agent and react, obtain LiFePO 4 material after having reacted, as the positive electrode active materials of lithium ion battery of the present invention.
The negative pole of above-mentioned lithium ion battery, electrolyte and barrier film, all can adopt and well known to a person skilled in the art various negative pole, electrolyte and barrier film, the present invention is not particularly limited.
Further specific descriptions will be done to the present invention below by specific embodiment.
embodiment 1
1) alcoholic solution in lithium source, is prepared: take 2mol lithium acetate, with absolute ethyl alcohol constant volume to 2L, after abundant stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid;
2) dispersion liquid of ferric phosphate, is prepared: take 2mol nano ferric phosphate, be settled to 1L with absolute ethyl alcohol, with Fluko high speed shear dispersion machine dispersion 20min, obtain the dispersion liquid of ferric phosphate, be designated as B liquid;
3), by B liquid join in magnetic drive autoclave, then join in B liquid slowly by A liquid, the flow velocity of control A liquid is 100ml/min, adds 1.2mol pure water afterwards; After with absolute ethyl alcohol, above-mentioned mixed liquor is settled to 5L; Pass into CO gas at once subsequently, flow control after 100L/h, 20min, closed reactor, be warming up to 180 DEG C, at this temperature after constant temperature 3h, cooling reactor, when temperature is down to less than 40 DEG C, open reactor, release suspension liquid, suction filtration, obtains solid sediment; Solid sediment is first used 5L pure water 2 times, suction filtration, change slurry, then use absolute ethanol washing 2 times, dry 2h, obtain LiFePO 4 material, be denoted as A1 at 80 DEG C;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; then A1 powder 100g is taken; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 8h in the roller furnace then under 700 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material C1.
embodiment 2
1) alcoholic solution in lithium source, is prepared: take 2mol lithium acetate, with absolute ethyl alcohol constant volume to 2L, after abundant stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid;
2) dispersion liquid of ferric phosphate, is prepared: take 2mol nano ferric phosphate and 2mol ascorbic acid, be settled to 1L with absolute ethyl alcohol, with Fluko high speed shear dispersion machine dispersion 20min, obtain the dispersion liquid of ferric phosphate, be designated as B liquid;
3), by B liquid join in magnetic drive autoclave, then join in B liquid slowly by A liquid, the flow velocity 100ml/min of control A liquid, then adds 1.2mol pure water; After with absolute ethyl alcohol, above-mentioned mixed liquor is settled to 5L; Pass into nitrogen gas at once subsequently, flow control after 100L/h, 20min, closed reactor, be warming up to 180 DEG C, at this temperature after constant temperature 3h, cooling reactor, when temperature is down to less than 40 DEG C, open reactor, release suspension liquid, suction filtration, obtains solid sediment;
Sediment is first used 5L pure water 2 times, suction filtration, change slurry, then use absolute ethanol washing 2 times, dry 2h, obtain LiFePO 4 material, be denoted as A2 at 80 DEG C;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; then A1 powder 100g is taken; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 8h in the roller furnace then under 700 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material C2.
embodiment 3
1) alcoholic solution in lithium source, is prepared: the lithium acetate taking 2mol, with absolute methanol constant volume to 2L, after abundant stirring and dissolving, obtains the alcoholic solution in lithium source, be designated as A liquid;
2) dispersion liquid of ferric phosphate, is prepared: accurately take 2mol nano ferric phosphate, be settled to 1L with absolute methanol, with Fluko high speed shear dispersion machine dispersion 20min, obtain the dispersion liquid of ferric phosphate, be designated as B liquid;
3), by B liquid join in magnetic drive autoclave, then join in B liquid slowly by A liquid, the flow velocity of control A liquid is 100ml/min, adds 1.2mol pure water afterwards, after with absolute methanol, above-mentioned mixed liquor is settled to 5L; Pass into CO gas at once subsequently, flow control after 100L/h, 20min, closed reactor, be warming up to 180 DEG C, at this temperature after constant temperature 3h, cooling reactor, when temperature is down to less than 40 DEG C, open reactor, release suspension liquid, suction filtration, obtains solid sediment;
Solid sediment is first used 5L pure water 2 times, suction filtration, change slurry, then wash 2 times with absolute methanol, dry 2h, obtain LiFePO 4 material, be denoted as A3 at 80 DEG C;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; take A1 powder 100g; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 8h in the roller furnace then under 700 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material C3.
embodiment 4
1) alcoholic solution in lithium source, is prepared: the lithium nitrate taking 2mol, with absolute ethyl alcohol constant volume to 1L, after abundant stirring and dissolving, obtains the alcoholic solution in lithium source, be designated as A liquid;
2) dispersion liquid of ferric phosphate, is prepared: accurately take 2mol nano ferric phosphate, be settled to 2L with absolute ethyl alcohol, with Fluko high speed shear dispersion machine dispersion 20min, obtain the dispersion liquid of ferric phosphate, be designated as B liquid;
3), by B liquid join in magnetic drive autoclave, then join in B liquid slowly by A liquid, the flow velocity of control A liquid is 100ml/min, adds 1mol pure water afterwards, after with absolute ethyl alcohol, above-mentioned mixed liquor is settled to 5L; Pass into CO gas at once subsequently, flow control after 20L/h, 20min, closed reactor, be warming up to 120 DEG C, at this temperature after constant temperature 11h, cooling reactor, when temperature is down to less than 40 DEG C, open reactor, release suspension liquid, suction filtration, obtains solid sediment; Solid sediment is first used 5L pure water 2 times, suction filtration, change slurry, then wash 2 times with absolute methanol, dry 2h, obtain LiFePO 4 material, be denoted as A4 at 80 DEG C;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; take A1 powder 100g; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 8h in the roller furnace then under 700 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material C4.
embodiment 5
1) alcoholic solution in lithium source, is prepared: the lithium nitrate taking 2mol, with anhydrous propyl alcohol constant volume to 3L, after abundant stirring and dissolving, obtains the alcoholic solution in lithium source, be designated as A liquid;
2) dispersion liquid of ferric phosphate, is prepared: take 2mol nano ferric phosphate and 2mol ascorbic acid, be settled to 2L with anhydrous propyl alcohol, with Fluko high speed shear dispersion machine dispersion 20min, obtain the dispersion liquid of ferric phosphate, be designated as B liquid;
3), by B liquid join in magnetic drive autoclave, then join in B liquid slowly by A liquid, the flow velocity of control A liquid is 500ml/min, adds 3mol pure water afterwards, after with anhydrous propyl alcohol, above-mentioned mixed liquor is settled to 8L; Pass into nitrogen gas at once subsequently, flow control after 500L/h, 20min, closed reactor, be warming up to 200 DEG C, at this temperature after constant temperature 4h, cooling reactor, when temperature is down to less than 40 DEG C, open reactor, release suspension liquid, suction filtration, obtains solid sediment; Solid sediment is first used 5L pure water 2 times, suction filtration, change slurry, then wash 2 times with absolute methanol, dry 3h, obtain LiFePO 4 material, be denoted as A5 at 70 DEG C;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; take A1 powder 100g; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 6h in the roller furnace then under 750 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material C5.
comparative example 1
1), take the lithium acetate of 2mol, with pure water constant volume to 2L, abundant stirring and dissolving postscript is A liquid;
2), take 2mol nano ferric phosphate and 2mol ascorbic acid, be settled to 1L with pure water, with Fluko high speed shear dispersion machine dispersion 20min, be designated as B liquid;
3), by B liquid join in magnetic drive autoclave, then A liquid joined in B liquid slowly, the flow velocity 100ml/min of control A liquid, after mixing material pure water is settled to 5L; Pass into nitrogen gas at once subsequently, flow control after 100L/h, 20min, closed reactor, be warming up to 180 DEG C, at this temperature after constant temperature 3h, cooling reactor, is down to after below 40 DEG C when temperature and opens reactor, release suspension liquid, suction filtration, obtains solid sediment; Sediment is first used 5L pure water 2 times, suction filtration, change slurry, then use absolute ethanol washing 2 times.At 80 DEG C, dry 2h, obtain LiFePO 4 material, be denoted as B1;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; then A1 powder 100g is taken; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 8h in the roller furnace then under 700 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material D1.
comparative example 2
1), take 6mol anhydrous lithium hydroxide, be settled to 2L with pure water, dissolving postscript is completely A liquid;
2), take 2mol phosphoric acid, 2mol green vitriol, 1.2mol ascorbic acid, be settled to 2L with pure water, abundant stirring and dissolving postscript is B liquid;
3), by B liquid join in magnetic drive autoclave, then join in B liquid slowly by A liquid, the flow velocity of control A liquid is 100ml/min, after mixed liquor pure water is settled to 5L; Pass into nitrogen gas at once subsequently, flow control after 100L/h, 20min, closed reactor, be warming up to 180 DEG C, at this temperature after constant temperature 3h, cooling reactor, when temperature is down to less than 40 DEG C, open reactor, release suspension liquid, suction filtration, obtains solid sediment; Solid sediment is first used 5L pure water 2 times, suction filtration, change slurry, then use absolute ethanol washing 2 times.At 80 DEG C, dry 2h, be denoted as B2;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; then A1 powder 100g is taken; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 8h in the roller furnace then under 700 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material D2.
comparative example 3
1), take 2mol lithium acetate, with absolute ethyl alcohol constant volume to 2L, after abundant stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid;
2), take 2mol ferrous acetate, 2mol phosphoric acid, 1.2mol ascorbic acid, be settled to 1L with absolute ethyl alcohol, with Fluko high speed shear dispersion machine dispersion 20min, is designated as B liquid;
3), by B liquid join in magnetic drive autoclave, then join in B liquid slowly by A liquid, the flow velocity of control A liquid is 100ml/min; After with absolute ethyl alcohol, above-mentioned mixed liquor is settled to 5L; Pass into nitrogen gas at once subsequently, flow control after 100L/h, 20min, closed reactor, be warming up to 180 DEG C, at this temperature after constant temperature 3h, cooling reactor, when temperature is down to less than 40 DEG C, open reactor, release suspension liquid, suction filtration, obtains solid sediment; Solid sediment is first used 5L pure water 2 times, suction filtration, change slurry, then use absolute ethanol washing 2 times, dry 2h, obtain LiFePO 4 material, be denoted as B3 at 80 DEG C;
4) glucose 15g, is taken; glucose ethanolic solution is obtained after adding the heat of solution of 100g absolute ethyl alcohol; then A1 powder 100g is taken; join in glucose ethanolic solution, change slurry, stir 10min with Fluko high speed shear dispersion machine; and keep viscous pasty state; 100 degree of vacuumizes are no longer flowed to slurry, sinter 8h in the roller furnace then under 700 DEG C of nitrogen protections, are denoted as bag carbon LiFePO 4 material D3.
test performance
1, the preparation of test battery:
(1) preparation of positive plate: bag carbon LiFePO 4 material D1-D3 prepared by the bag carbon LiFePO 4 material C1-C5 and comparative example 1-3 prepared by embodiment 1-5 is as positive electrode active materials, be that 100:4:5 is dissolved in 1-METHYLPYRROLIDONE with weight ratio by positive electrode, acetylene black and PVDF, be coated in after stirring on aluminium foil, baking, temperature is 100 ± 5 DEG C, use tablet press machine to roll certain thickness, rolling cut becomes positive plate;
(2) preparation of negative plate: be that 100:3:6 is dissolved in 1-METHYLPYRROLIDONE with weight ratio by graphite, acetylene black and PVDF, be coated in after stirring on Copper Foil, baking, temperature is 100 ± 5 DEG C, use tablet press machine to roll certain thickness, rolling cut becomes negative plate;
(3) above-mentioned positive and negative plate and polypropylene diaphragm are wound into rectangular lithium ion battery battery core, are placed in battery case and weld, injecting the LiPF of 1.0mol/L subsequently
6/ EC+EMC+DMC (wherein, EC, EMC and DMC mass ratio is 1:1:1) electrolyte, sealing, makes test battery.
2.1, specific capacity test:
At room temperature, test battery is shelved 5min, first with 0.8mA constant current charge, by voltage 3.8V, at 3.8V constant voltage charge, by electric current 0.1mA, shelve 5min, with 0.8mA constant-current discharge, deboost 2.5V.Calculate its specific capacity, the results are shown in Table 1;
2.2, cycle performance test
At room temperature, by test battery first with 0.8mA constant current charge, deboost 3.8V, at 3.8V constant voltage charge, by electric current 0.1mA, shelves 5min, with 0.8mA constant-current discharge.Repeat 500 times, calculate 500 capability retentions, the results are shown in Table 1.
Table 1
| 3.0-4.2V specific capacity (mAh/g) | 500 capability retentions | Discharging efficiency | |
| Embodiment 1 | 164 | 97% | 99% |
| Embodiment 2 | 158 | 95% | 95% |
| Embodiment 3 | 160 | 94% | 99% |
| Embodiment 4 | 162 | 96% | 99% |
| Embodiment 5 | 157 | 95% | 94% |
| Comparative example 1 | 144 | 85% | 81% |
| Comparative example 2 | 150 | 82% | 88% |
| Comparative example 3 | 155 | 90% | 91% |
Can see from table 1, the LiFePO 4 material adopting the preparation method of embodiment of the present invention 1-5 to obtain makes lithium ion battery, compared to the lithium ion battery that the LiFePO 4 material adopting comparative example 1-3 to prepare makes, the lithium ion battery adopting the LiFePO 4 material of embodiment of the present invention 1-5 to obtain has higher specific capacity and good capability retention.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (8)
1. a preparation method for LiFePO 4 material, is characterized in that, described preparation method comprises the steps:
Step 1, ferric phosphate is scattered in alcohol solution, obtains the dispersion liquid of ferric phosphate;
Step 2, lithium source is dissolved in alcohol solution, obtains the alcoholic solution in lithium source;
Step 3, in the dispersion liquid of ferric phosphate, add the alcoholic solution in lithium source, then react under reducing gas atmosphere, after having reacted, obtain LiFePO 4 material; Wherein, after adding the alcoholic solution in lithium source, add pure water in proportion, the consumption of described pure water makes the mol ratio of H:P for (0.5-5): 1;
In step 3, the condition of described reaction is: carry out in airtight reactor, be warming up to 120-220 DEG C, insulation 3-12 hour.
2. preparation method according to claim 1, is characterized in that, described lithium source is dissolve in one or more in the lithium source of alcohol solution.
3. preparation method according to claim 1, is characterized in that, described alcohol solution is selected from one or more in methyl alcohol, ethanol, propyl alcohol.
4. preparation method according to claim 1, is characterized in that, the consumption of described lithium source, ferric phosphate makes the mol ratio of Li:Fe:P for (0.95-1.05): 1:1.
5. preparation method according to claim 1, is characterized in that, in step 3, the flow velocity controlling the alcoholic solution adding lithium source in the dispersion liquid of ferric phosphate is 100-1000mL/min.
6. preparation method according to claim 1, is characterized in that, in step 3, adds alcohol solution to 5-10L after the alcoholic solution adding lithium source and pure water.
7. preparation method according to claim 1, is characterized in that, the reducing gas passed in step 3 is CO, and flow velocity is 10-100L/h.
8. a lithium ion battery, the barrier film comprising positive pole, negative pole and be arranged between positive pole, negative pole, described positive pole comprises positive electrode collector and is coated on the positive electrode active materials on positive electrode collector, it is characterized in that, described positive electrode active materials adopts the preparation method as described in claim 1-7 any one to prepare.
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| CN105789605A (en) * | 2014-12-22 | 2016-07-20 | 深圳市比克电池有限公司 | Carbon coated LiFePO4, preparing method of the carbon coated LiFePO4 and power lithium ion cell |
| CN107785570B (en) * | 2016-08-24 | 2021-02-02 | 德阳威旭锂电科技有限责任公司 | Preparation method for improving yield of olivine structure electrode material by hydrothermal method |
| CN112928268B (en) * | 2021-04-01 | 2022-09-02 | 神华准能资源综合开发有限公司 | Preparation method of carbon-coated lithium iron phosphate composite material and carbon-coated lithium iron phosphate composite material |
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| CN1803591A (en) * | 2005-12-22 | 2006-07-19 | 上海交通大学 | Method for preparing lithium ion battery anode material lithium ion phosphate |
| CN101152960A (en) * | 2006-09-27 | 2008-04-02 | 比亚迪股份有限公司 | Method of producing active compound lithium iron phosphate of lithium ion secondary battery anode |
| CN101373831A (en) * | 2007-08-24 | 2009-02-25 | 深圳市比克电池有限公司 | Method for preparing lithium ion battery anode material lithium iron phosphate |
| CN101399341A (en) * | 2007-09-25 | 2009-04-01 | 深圳市比克电池有限公司 | Producing method for large granule lithium iron phosphate battery positive pole material |
| CN101966986A (en) * | 2010-11-19 | 2011-02-09 | 中南大学 | Preparation method of lithium iron phosphate cathode material for lithium ion battery |
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| CN1803591A (en) * | 2005-12-22 | 2006-07-19 | 上海交通大学 | Method for preparing lithium ion battery anode material lithium ion phosphate |
| CN101152960A (en) * | 2006-09-27 | 2008-04-02 | 比亚迪股份有限公司 | Method of producing active compound lithium iron phosphate of lithium ion secondary battery anode |
| CN101373831A (en) * | 2007-08-24 | 2009-02-25 | 深圳市比克电池有限公司 | Method for preparing lithium ion battery anode material lithium iron phosphate |
| CN101399341A (en) * | 2007-09-25 | 2009-04-01 | 深圳市比克电池有限公司 | Producing method for large granule lithium iron phosphate battery positive pole material |
| CN101966986A (en) * | 2010-11-19 | 2011-02-09 | 中南大学 | Preparation method of lithium iron phosphate cathode material for lithium ion battery |
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