CN102795611A - Preparation method of lithium iron phosphate material and lithium ion battery - Google Patents
Preparation method of lithium iron phosphate material and lithium ion battery Download PDFInfo
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- CN102795611A CN102795611A CN2011101387094A CN201110138709A CN102795611A CN 102795611 A CN102795611 A CN 102795611A CN 2011101387094 A CN2011101387094 A CN 2011101387094A CN 201110138709 A CN201110138709 A CN 201110138709A CN 102795611 A CN102795611 A CN 102795611A
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Abstract
The invention provides a preparation method of a lithium iron phosphate material, comprising the following steps of: step 1, dispersing iron phosphate into an alcohol solution to obtain a dispersion solution of iron phosphate; step 2, dissolving a lithium source into the alcohol solution to obtain an alcohol solution of the lithium source; step 3, adding the alcohol solution of the lithium source into the dispersion solution of the iron phosphate; and reacting under a reduction gas atmosphere or adding a reducing agent to obtain the lithium iron phosphate material after the reaction. The invention further provides a lithium ion battery. The grain of the lithium iron phosphate material prepared by the preparation method disclosed by the invention is smaller; and the specific capacity of the lithium ion battery prepared from the lithium iron phosphate material is higher and the capacity keeping rate 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 fields such as mobile communication, notebook computer, pick up camera, photographic camera, portable instrument as the high-energy-density chemical power source; Also be the electromobile studied energetically of various countries, the first-selected supporting power supply of space power system, become the first-selection of the alternative energy.In recent years, LiFePO
4Become the research focus of active substance of lithium ion battery anode.LiFePO
4Compare with other positive electrode active materials with positive active material as lithium ion battery and to have good electrochemical; Charge and discharge platform very steadily; Stability Analysis of Structures in the charge and discharge process, and have nontoxic, pollution-free, advantage such as safety performance is good, can under hot environment, use, starting material wide material sources.
The preparation method of existing LiFePO 4 material mainly contains solid phase method, hydrothermal method, wherein; Solid phase method technology is simple, in industrialization, realize the earliest, and solid phase method can make the particle that particle diameter is less and capacity is higher; But solid phase method adopts traditional sand milling or ball milled and starting material is mixed; The abrasion of equipment is inevitable, because equipment adopts steel or iron material to process usually, solid phase method inevitably can be introduced Fe impurity; And, has the inhomogenous shortcoming of local reaction because solid phase method is the reaction between solid and the solid.Thereby normal at present employing hydrothermal method prepares LiFePO 4 material, and hydrothermal method can make the material of performance homogeneous; But hydro-thermal reaction can inevitably be introduced ironic hydroxide, and phosphoric acid hydrogen is ferrous; Trilithium phosphate, impurity such as phosphoric acid hydrogen two lithiums, and because the polarity of water is bigger; Material is easy to reunite, thereby makes the capacity of obtained LiFePO 4 material low, cycle efficiency is low.
Summary of the invention
The preparation method that the present invention is intended to solve existing LiFePO 4 material is prone to introduce impurity, raw material is reunited easily, makes the technical problem that prepared iron lithium phosphate capacity is low, cycle efficiency is low.
Contriver of the present invention finds to adopt existing Hydrothermal Preparation iron lithium phosphate, and phosphoric acid can three grades of ionization occur and introduce impurity in water, and because iron lithium phosphate is a hydroaropic substance; Can cause its serious agglomeration; The granule interior of reuniting together possibly exist unreacted matters and impurity, and contriver of the present invention finds through long term studies, adopts pure hot legal system to be equipped with the deficiency that iron lithium phosphate has remedied hydrothermal method; Because tertiary iron phosphate can be as three grades of ionization in water, occurring in alcohol solution; So impurity can not occur, and because the polar phase of alcohol solution is less for water, solid particulate is better dispersed; Agglomeration can not occur, make prepared iron lithium phosphate have higher specific storage and capability retention preferably.
The invention provides a kind of preparation method of LiFePO 4 material, said making method comprises:
Step 1, tertiary iron phosphate is scattered in the alcohol solution, obtains the dispersion liquid of tertiary iron phosphate;
Step 2, the lithium source is scattered in the alcohol solution, obtains the alcoholic solution in lithium source;
Step 3, in the dispersion liquid of tertiary iron phosphate, add the alcoholic solution in lithium source, under reducing gas atmosphere or add reductive agent and react, reaction obtains LiFePO 4 material after accomplishing then.
In the preparation method of LiFePO 4 material of the present invention, said lithium source is to dissolve in the lithium source of alcohol solution one or more.
In the preparation method of LiFePO 4 material of the present invention, said alcohol solution is selected from one or more in methyl alcohol, ethanol, the propyl alcohol.
In the preparation method of LiFePO 4 material of the present invention, the consumption of said lithium source, tertiary iron phosphate makes the mol ratio of Li:Fe:P be (0.95-1.05): 1:1.
In the preparation method of LiFePO 4 material of the present invention, in step 3, the condition of said reaction is: in closed reaction kettle, carry out, be warming up to 120-220 ℃, be incubated 3-12 hour.
In the preparation method of LiFePO 4 material of the present invention, in step 3, being controlled at the flow velocity that adds the alcoholic solution in lithium source in the dispersion liquid of tertiary iron phosphate is 100-1000ml/min.
In the preparation method of LiFePO 4 material of the present invention, in step 3, after the alcoholic solution that adds the lithium source, add pure water in proportion, add alcohol solution then to 5-10L.
In the preparation method of LiFePO 4 material of the present invention, the consumption of said pure water makes the mol ratio of H:P be (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 of feeding is CO, and flow velocity is 10-100L/h.
The present invention also provides a kind of lithium ion battery; Comprise positive pole, negative pole and be arranged at the barrier film between positive pole, the negative pole; Said positive pole comprises positive electrode collector and is coated on the positive electrode active materials on the positive electrode collector; Wherein, said positive electrode active materials adopts aforesaid preparation method to prepare.
The preparation method of LiFePO 4 material of the present invention is scattered in tertiary iron phosphate in the alcohol solution, and the lithium source is scattered in the alcohol solution, the alcoholic solution in lithium source is added in the dispersion liquid of tertiary iron phosphate react then; Because three grades of ionization can not appear in tertiary iron phosphate in alcohol solution; So impurity can not occur, and because the polar phase of alcohol solution is less for water, solid particulate is better dispersed; Agglomeration can not appear; Prepared LiFePO 4 material particle is less, adopt the specific storage of lithium ion battery of said LiFePO 4 material higher, and capability retention is better.
Embodiment
Contriver of the present invention finds in reaction process, unavoidably a lot of side reactions can take place, and the generation of side reaction will inevitably be introduced impurity because phosphoric acid three grades of ionization can occur in water; For example: ironic hydroxide, phosphoric acid hydrogen two lithiums, phosphoric acid hydrogen is ferrous; Trilithium phosphate etc., the verified discharging efficiency and the specific storage that will reduce the material of processing greatly of the introducing of these impurity, and have other uncertainty; To cause the performance of material to reduce significantly; And because iron lithium phosphate is a hydroaropic substance, adopt existing Hydrothermal Preparation iron lithium phosphate can cause its serious agglomeration, the granule interior of reuniting together possibly exist unreacted matters and impurity; Contriver of the present invention finds through long term studies; Tertiary iron phosphate adopt pure hot legal system to be equipped with the deficiency that iron lithium phosphate has remedied hydrothermal method, owing to can not reduce the carrying out of side reaction as three grades of ionization in water, occurring in alcohol solution; So impurity can not occur; And because the polar phase of alcohol solution is less for water, solid particulate is better dispersed, agglomeration can not occur; Prepared iron lithium phosphate has higher specific storage and capability retention preferably, and the performance of material is significantly promoted.
In view of the above, the invention provides a kind of preparation method of LiFePO 4 material, comprise the steps:
The alcoholic solution in step 1, preparation lithium source: tertiary iron phosphate is scattered in the alcohol solution, obtains the dispersion liquid of tertiary iron phosphate; In this step, tertiary iron phosphate is joined in the alcohol solution, use dispersion machine then, for example: the Fluko dispersion machine is powerful to be disperseed, and obtains the dispersion liquid of tertiary iron phosphate, and in the dispersion liquid of said tertiary iron phosphate, the concentration of tertiary iron phosphate is 1 ~ 5mol/L; Wherein, said tertiary iron phosphate is a nano ferric phosphate, and particle diameter is 50-500nm; In the present invention, adopt single tertiary iron 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 many more, the intermediary side reaction may increase, and is unfavorable to generating final LiFePO 4 material; And if employing Fe
2(PO
4)
3, because Fe/P is than less than 1, and solvent is non-aqueous solvent, can not form pure phase lithium iron phosphate.In said alcohol solution particular methanol, ethanol, propyl alcohol, terepthaloyl moietie, the Virahol one or more, more preferably one or more in anhydrous methanol, absolute ethyl alcohol, the anhydrous propyl alcohol make that the dispersion effect of raw material is better, and reduce the generation of side reaction.
The dispersion liquid of step 2, preparation tertiary iron phosphate: the lithium source is scattered in the alcohol solution, obtains the alcoholic solution in lithium source; In this step, through the lithium source is dissolved in the alcohol solution, obtain the alcoholic solution in lithium source, in the alcoholic solution in said lithium source, the concentration in lithium source is 1 ~ 5mol/L; Said lithium source is selected from one or more in the lithium source that dissolves in alcohol solution, and preferably, said lithium source is lithium acetate and/or lithium nitrate.Said alcohol solution can be selected from one or more in methyl alcohol, ethanol, propyl alcohol, the Virahol, and more preferably one or more in anhydrous methanol, absolute ethyl alcohol, the anhydrous propyl alcohol make that the dispersion effect of raw material is better, and reduces the generation of side reaction.The alcohol solution that this step adopts can be identical with step 1 also can be different.
Step 3, in the dispersion liquid of tertiary iron phosphate, add the alcoholic solution in lithium source, under reducing gas atmosphere or add reductive agent and react, reaction obtains LiFePO 4 material after accomplishing then.In this step, preferably, the dispersion liquid with tertiary iron phosphate adds reaction kettle earlier; For example: in the magnetically-actuated reaction kettle; Then the alcoholic solution in lithium source is added drop-wise in the dispersion liquid of tertiary iron phosphate lentamente and obtains mixed solution, in this process, the flow velocity of the alcoholic solution in control lithium source is 100-1000ml/min; Add pure water (when adopting anhydrous pure liquid) then in proportion, at last mixed solution is settled to 5-10L with alcohol solution; For example: for 10L volumetrical reaction kettle, can take by weighing nano ferric phosphate, to 1-4L, wherein, the concentration of tertiary iron phosphate is 1 ~ 5mol/L with the absolute ethyl alcohol constant volume; Take by weighing the nanometer lithium acetate, be settled to 1-4L with absolute ethyl alcohol, wherein, the concentration of lithium acetate is that 1 ~ 5mol/L adds pure water then in proportion, is settled to 5-10L with alcohol solution again.
Wherein, In said alcohol solution particular methanol, ethanol, propyl alcohol, terepthaloyl moietie, the Virahol one or more; More preferably one or more in anhydrous methanol, absolute ethyl alcohol, the anhydrous propyl alcohol, the dispersion effect of raw material is better, and reduce the generation of side reaction.The alcohol solution that this step adopts can with step 1,2 identical also can be different.Feed reducing gas or rare gas element (is that reductive agent is when reacting when what add) subsequently at once, the flow velocity of said reducing gas or rare gas element can be 10-100L/h, guarantee in the reaction kettle that all air displacement are clean after; Closed reactor is warming up to 120-220 ℃, after constant temperature under this temperature keeps 3-12h; The cooling reaction still; Open reaction kettle after under temperature is reduced to 40 ℃,, obtain LiFePO 4 material through aftertreatment.In the present invention, can in mixed solution, add this areas such as xitix, Hydrocerol A reductive agent commonly used, and; Making the protective atmosphere in the reaction kettle is that inert gas atmosphere reacts; But preferably, be reflected under the reducing gas atmosphere and carry out, said reducing gas can be selected CO, H
2A kind of Deng in the reducing gas can play the effect of reductive agent and shielding gas, in the present invention simultaneously; Preferred CO, because CO is dissolved in alcohol, and in reaction system; Gas-liquid diffusion ratio liquid liquid velocity of diffusion is faster, and uniformity coefficient is higher, and reductive agent; For example: xitix just is slightly soluble in ethanol, thereby in the hot method of alcohol, adopts CO can make that as reductive agent the overall performance of material is better.When system adopts absolute alcohol; For example: during absolute ethyl alcohol; Said pure water adds as reactant, and its consumption makes the mol ratio of H:P be (0.5-5): 1, and water is participated in reaction as a kind of starting material and is made iron lithium phosphate; The amount of control pure water can prevent that reaction from changing hydrothermal method into by the hot method of alcohol, and excessive water can influence the performance of the LiFePO 4 material of final generation.
Said aftertreatment comprises emits suspension liquid from reaction kettle, suction filtration obtains solid sediment; Earlier with the pure water washing, suction filtration, change slurry are used absolute ethanol washing then with solid sediment; Obtain LiFePO 4 material after the oven dry; Said aftertreatment is used for differentiating effectively reacted product and all the other are residual, and said aftertreatment has been conventionally known to one of skill in the art, does not do at this and gives unnecessary details.
As the lithium source, CO is an example as reductive agent with preferred lithium acetate, and the reaction mechanism of LiFePO 4 material is: 0.5H
2O+FePO
4+ LiAc+0.5CO → LiFePO
4+ 0.5CO
2+ HAc makes LiFePO 4 material through above-mentioned reaction, and said 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 conductivity of LiFePO 4 material is relatively poor, thereby need coat one deck carbon on the surface of LiFePO 4 material usually.The present invention is through joining LiFePO 4 material in the alcoholic solution of carbon source, changes slurry, to be dried to slurry no longer mobile, under protection of inert gas, carries out sintering (the agglomerating temperature is 780 ± 50 ℃) then and obtains wrapping the carbon LiFePO 4 material.Wherein, Said carbon source can be selected from and well known to a person skilled in the art the additive that can play electric action; For example, can be selected from the luxuriant and rich with fragrance terpolymer of benzene naphthalene, benzene luxuriant and rich with fragrance copolymer, benzene anthracene copolymer, gather in benzene, Zulkovsky starch, Z 150PH, sucrose, glucose, urea, resol, furfuryl resin, synthetic graphite, natural graphite, superconduction acetylene black, acetylene black, carbon black and the mesocarbon bead one or more.
Further, the present invention also provides a kind of lithium ion battery, comprising: anodal, negative pole and be arranged at the barrier film between positive pole, the negative pole.Said negative pole comprises negative electrode collector and is coated on the negative active core-shell material on the negative electrode collector, and said negative electrode collector can adopt Copper Foil, and said negative active core-shell material can adopt the common negative active core-shell material in this area, for example: carbon material.Said negative active core-shell material forms slurry and is coated on the negative electrode collector through interpolation sticker, solvent; Said caking agent and solvent have no particular limits; The known caking agent and the solvent that normally are used for the negative pole preparation of lithium ion battery, for example: sticker is used CMC (Xylo-Mucine), solvent SBR (styrene-butadiene rubber(SBR)) commonly used always.
Said positive pole comprises substrate and is attached to the positive electrode material on the substrate.Substrate can adopt aluminium foil or nickel screen.Anodal is the preparation method have no particular limits, and can be to obtain through slurry.Said positive electrode material contains positive electrode active materials, caking agent, and can contain static eliminator.Said lithium ion battery difference with the prior art is that said positive electrode active materials prepares through preparation method of the present invention, promptly adopts following step to prepare: step 1, tertiary iron phosphate is scattered in the alcohol solution, obtains the dispersion liquid of tertiary iron phosphate; Step 2, the lithium source is dissolved in the alcohol solution, obtains the alcoholic solution in lithium source; Step 3, in the dispersion liquid of tertiary iron phosphate, add the alcoholic solution in lithium source, under reducing gas atmosphere or add reductive agent and react, reaction obtains LiFePO 4 material after accomplishing, as the positive electrode active materials of lithium ion battery of the present invention then.
The negative pole of above-mentioned lithium ion battery, electrolytic solution and barrier film all can adopt to well known to a person skilled in the art various negative poles, electrolytic solution and barrier film, the not special restriction of the present invention.
To do further specific descriptions to the present invention through specific embodiment below.
Embodiment 1
1), the alcoholic solution in preparation lithium source: take by weighing the 2mol lithium acetate, to 2L, fully after the stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid with the absolute ethyl alcohol constant volume;
2), the dispersion liquid of preparation tertiary iron phosphate: take by weighing the 2mol nano ferric phosphate, be settled to 1L, disperse 20min, obtain the dispersion liquid of tertiary iron phosphate, be designated as B liquid with Fluko high speed shear dispersion machine with absolute ethyl alcohol;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity of control A liquid is 100ml/min, adds the 1.2mol pure water afterwards; With absolute ethyl alcohol above-mentioned mixed solution is settled to 5L after finishing; Feed CO gas subsequently at once, flow control is at 100L/h, behind the 20min, and closed reactor; Be warming up to 180 ℃, behind constant temperature 3h under this temperature, the cooling reaction still is when temperature is reduced to below 40 ℃; Open reaction kettle, emit suspension liquid, suction filtration obtains solid sediment; Earlier with 5L pure water washing 2 times, suction filtration, change slurry are used absolute ethanol washing 2 times then with solid sediment, dry 2h down at 80 ℃, obtain LiFePO 4 material, and note is made A1;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g then; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 8h in the roller-way stove under 700 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material C1 then.
Embodiment 2
1), the alcoholic solution in preparation lithium source: take by weighing the 2mol lithium acetate, to 2L, fully after the stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid with the absolute ethyl alcohol constant volume;
2), the dispersion liquid of preparation tertiary iron phosphate: take by weighing 2mol nano ferric phosphate and 2mol xitix, be settled to 1L, disperse 20min, obtain the dispersion liquid of tertiary iron phosphate, be designated as B liquid with Fluko high speed shear dispersion machine with absolute ethyl alcohol;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity 100ml/min of control A liquid adds the 1.2mol pure water then; With absolute ethyl alcohol above-mentioned mixed solution is settled to 5L after finishing; Feed nitrogen gas subsequently at once, flow control is at 100L/h, behind the 20min, and closed reactor; Be warming up to 180 ℃, behind constant temperature 3h under this temperature, the cooling reaction still is when temperature is reduced to below 40 ℃; Open reaction kettle, emit suspension liquid, suction filtration gets solid sediment;
Earlier with 5L pure water washing 2 times, suction filtration, change slurry are used absolute ethanol washing 2 times then with throw out, dry 2h down at 80 ℃, obtain LiFePO 4 material, and note is made A2;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g then; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 8h in the roller-way stove under 700 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material C2 then.
Embodiment 3
1), the alcoholic solution in preparation lithium source: take by weighing the lithium acetate of 2mol, to 2L, fully after the stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid with the anhydrous methanol constant volume;
2), the dispersion liquid of preparation tertiary iron phosphate: accurately take by weighing the 2mol nano ferric phosphate, be settled to 1L, disperse 20min, obtain the dispersion liquid of tertiary iron phosphate, be designated as B liquid with Fluko high speed shear dispersion machine with anhydrous methanol;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity of control A liquid is 100ml/min, adds the 1.2mol pure water afterwards, and the back that finishes is settled to 5L with anhydrous methanol with above-mentioned mixed solution; Feed CO gas subsequently at once, flow control is at 100L/h, behind the 20min, and closed reactor; Be warming up to 180 ℃, behind constant temperature 3h under this temperature, the cooling reaction still is when temperature is reduced to below 40 ℃; Open reaction kettle, emit suspension liquid, suction filtration obtains solid sediment;
Earlier with 5L pure water washing 2 times, suction filtration, change slurry wash 2 times with anhydrous methanol then with solid sediment, and oven dry 2h obtains LiFePO 4 material under 80 ℃, and note is made A3;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 8h in the roller-way stove under 700 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material C3 then.
Embodiment 4
1), the alcoholic solution in preparation lithium source: take by weighing the lithium nitrate of 2mol, to 1L, fully after the stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid with the absolute ethyl alcohol constant volume;
2), the dispersion liquid of preparation tertiary iron phosphate: accurately take by weighing the 2mol nano ferric phosphate, be settled to 2L, disperse 20min, obtain the dispersion liquid of tertiary iron phosphate, be designated as B liquid with Fluko high speed shear dispersion machine with absolute ethyl alcohol;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity of control A liquid is 100ml/min, adds the 1mol pure water afterwards, and the back that finishes is settled to 5L with absolute ethyl alcohol with above-mentioned mixed solution; Feed CO gas subsequently at once, flow control is at 20L/h, behind the 20min, and closed reactor; Be warming up to 120 ℃, behind constant temperature 11h under this temperature, the cooling reaction still is when temperature is reduced to below 40 ℃; Open reaction kettle, emit suspension liquid, suction filtration obtains solid sediment; Earlier with 5L pure water washing 2 times, suction filtration, change slurry wash 2 times with anhydrous methanol then with solid sediment, and oven dry 2h obtains LiFePO 4 material under 80 ℃, and note is made A4;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 8h in the roller-way stove under 700 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material C4 then.
Embodiment 5
1), the alcoholic solution in preparation lithium source: take by weighing the lithium nitrate of 2mol, to 3L, fully after the stirring and dissolving, obtain the alcoholic solution in lithium source, be designated as A liquid with anhydrous propyl alcohol constant volume;
2), the dispersion liquid of preparation tertiary iron phosphate: take by weighing 2mol nano ferric phosphate and 2mol xitix, be settled to 2L, disperse 20min, obtain the dispersion liquid of tertiary iron phosphate, be designated as B liquid with Fluko high speed shear dispersion machine with anhydrous propyl alcohol;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity of control A liquid is 500ml/min, adds the 3mol pure water afterwards, and the back that finishes is settled to 8L with anhydrous propyl alcohol with above-mentioned mixed solution; Feed nitrogen gas subsequently at once, flow control is at 500L/h, behind the 20min, and closed reactor; Be warming up to 200 ℃, behind constant temperature 4h under this temperature, the cooling reaction still is when temperature is reduced to below 40 ℃; Open reaction kettle, emit suspension liquid, suction filtration obtains solid sediment; Earlier with 5L pure water washing 2 times, suction filtration, change slurry wash 2 times with anhydrous methanol then with solid sediment, and oven dry 3h obtains LiFePO 4 material under 70 ℃, and note is made A5;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 6h in the roller-way stove under 750 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material C5 then.
Comparative Examples 1
1), take by weighing the lithium acetate of 2mol, to 2L, fully the stirring and dissolving postscript is an A liquid with the pure water constant volume;
2), take by weighing 2mol nano ferric phosphate and 2mol xitix, be settled to 1L with pure water, disperse 20min with Fluko high speed shear dispersion machine, be designated as B liquid;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity 100ml/min of control A liquid is settled to 5L with mixing liquid with pure water after finishing; Feed nitrogen gas subsequently at once, flow control is at 100L/h, behind the 20min, and closed reactor; Be warming up to 180 ℃, behind constant temperature 3h under this temperature, the cooling reaction still is opened reaction kettle after temperature is reduced to below 40 ℃; Emit suspension liquid, suction filtration gets solid sediment; Earlier with 5L pure water washing 2 times, suction filtration is changed slurry, uses absolute ethanol washing then 2 times with throw out.Dry 2h down at 80 ℃, obtain LiFePO 4 material, note is made B1;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g then; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 8h in the roller-way stove under 700 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material D1 then.
Comparative Examples 2
1), take by weighing the 6mol anhydrous lithium hydroxide, be settled to 2L with pure water, dissolving postscript fully is A liquid;
2), take by weighing 2mol phosphoric acid, 2mol Presfersul, 1.2mol xitix, be settled to 2L with pure water, fully the stirring and dissolving postscript is a B liquid;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity of control A liquid is 100ml/min, after finishing mixed solution is settled to 5L with pure water; Feed nitrogen gas subsequently at once, flow control is at 100L/h, behind the 20min, and closed reactor; Be warming up to 180 ℃, behind constant temperature 3h under this temperature, the cooling reaction still is when temperature is reduced to below 40 ℃; Open reaction kettle, emit suspension liquid, suction filtration gets solid sediment; Earlier with 5L pure water washing 2 times, suction filtration, change slurry are used absolute ethanol washing 2 times then with solid sediment.Dry 2h down at 80 ℃, note is made B2;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g then; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 8h in the roller-way stove under 700 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material D2 then.
Comparative Examples 3
1), take by weighing the 2mol lithium acetate, to 2L, fully after the stirring and dissolving, obtain the alcoholic solution in lithium source with the absolute ethyl alcohol constant volume, be designated as A liquid;
2), take by weighing the 2mol Iron diacetate, 2mol phosphoric acid, 1.2mol xitix are settled to 1L with absolute ethyl alcohol, disperse 20min with Fluko high speed shear dispersion machine, are designated as B liquid;
3), B liquid is joined in the magnetically-actuated autoclave, then A liquid is joined in the B liquid slowly, the flow velocity of control A liquid is 100ml/min; With absolute ethyl alcohol above-mentioned mixed solution is settled to 5L after finishing; Feed nitrogen gas subsequently at once, flow control is at 100L/h, behind the 20min, and closed reactor; Be warming up to 180 ℃, behind constant temperature 3h under this temperature, the cooling reaction still is when temperature is reduced to below 40 ℃; Open reaction kettle, emit suspension liquid, suction filtration obtains solid sediment; Earlier with 5L pure water washing 2 times, suction filtration, change slurry are used absolute ethanol washing 2 times then with solid sediment, dry 2h down at 80 ℃, obtain LiFePO 4 material, and note is made B3;
4), take by weighing glucose 15g, obtain the glucose ethanolic soln after adding the heat of solution of 100g absolute ethyl alcohol, take by weighing A1 powder 100g then; Join in the glucose ethanolic soln, change slurry, stir 10min with Fluko high speed shear dispersion machine; And maintenance thickness state; 100 degree vacuum-drying to slurries are no longer mobile, and sintering 8h in the roller-way stove under 700 ℃ of nitrogen protections remembers and makes bag carbon LiFePO 4 material D3 then.
Test performance
1, the preparation of test battery:
(1) preparation of positive plate: with the bag carbon LiFePO 4 material D1-D3 of the bag carbon LiFePO 4 material C1-C5 of embodiment 1-5 preparation and Comparative Examples 1-3 preparation respectively as positive electrode active materials; With positive electrode material, acetylene black and PVDF is that 100:4:5 is dissolved in the N-Methyl pyrrolidone with the weight ratio; Be coated in after stirring on the aluminium foil, baking, temperature is 100 ± 5 ℃; Use tabletting machine to roll certain thickness, rolling cut becomes positive plate;
(2) preparation of negative plate: with graphite, acetylene black and PVDF is that 100:3:6 is dissolved in the N-Methyl pyrrolidone with the weight ratio; Be coated in after stirring on the Copper Foil, baking, temperature is 100 ± 5 ℃; Use tabletting 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 electricity core, place in battery case and weld, inject the LiPF of 1.0mol/L subsequently
6/ EC+EMC+DMC (wherein, EC, EMC and DMC mass ratio are 1:1:1) electrolytic solution, test battery is processed in sealing.
2.1, specific storage test:
At room temperature, test battery is shelved 5min,,,,, shelve 5min by electric current 0.1mA at the 3.8V constant voltage charge by voltage 3.8V earlier with the 0.8mA constant current charge, with the 0.8mA constant-current discharge, deboost 2.5V.Calculate its specific storage, the result sees table 1;
2.2, cycle performance test
At room temperature, earlier with the 0.8mA constant current charge, deboost 3.8V at the 3.8V constant voltage charge, by electric current 0.1mA, shelves 5min, with the 0.8mA constant-current discharge with test battery.Repeat 500 times, calculate 500 times capability retention, the result sees table 1.
Table 1
| ? | 3.0-4.2V specific storage (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 Examples 1 | 144 | 85% | 81% |
| Comparative Examples 2 | 150 | 82% | 88% |
| Comparative Examples 3 | 155 | 90% | 91% |
From table 1, can see; The LiFePO 4 material that the preparation method of employing embodiment of the invention 1-5 makes is made lithium ion battery; Compared to the lithium ion battery that the LiFePO 4 material that adopts Comparative Examples 1-3 preparation is made, the lithium ion battery that adopts the LiFePO 4 material of embodiment of the invention 1-5 to make has higher specific storage and capability retention preferably.
The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. the preparation method of a LiFePO 4 material is characterized in that, said preparation method comprises the steps:
Step 1, tertiary iron phosphate is scattered in the alcohol solution, obtains the dispersion liquid of tertiary iron phosphate;
Step 2, the lithium source is dissolved in the alcohol solution, obtains the alcoholic solution in lithium source;
Step 3, in the dispersion liquid of tertiary iron phosphate, add the alcoholic solution in lithium source, under reducing gas atmosphere or add reductive agent and react, reaction obtains LiFePO 4 material after accomplishing then.
2. preparation method according to claim 1 is characterized in that, said lithium source is to dissolve in the lithium source of alcohol solution one or more.
3. preparation method according to claim 1 is characterized in that said alcohol solution is selected from one or more in methyl alcohol, ethanol, the propyl alcohol.
4. preparation method according to claim 1 is characterized in that, the consumption of said lithium source, tertiary iron phosphate makes the mol ratio of Li:Fe:P be (0.95-1.05): 1:1.
5. preparation method according to claim 1 is characterized in that, in step 3, the condition of said reaction is: in closed reaction kettle, carry out, be warming up to 120-220 ℃, be incubated 3-12 hour.
6. according to claim 1 or 5 described preparing methods, it is characterized in that in step 3, being controlled at the flow velocity that adds the alcoholic solution in lithium source in the dispersion liquid of tertiary iron phosphate is 100-1000ml/min.
7. according to claim 1 or 5 described preparing methods, it is characterized in that, in step 3, after the alcoholic solution that adds the lithium source, add pure water in proportion, add alcohol solution then to 5-10L.
8. preparation method according to claim 7 is characterized in that, the consumption of said pure water makes the mol ratio of H:P be (0.5-5): 1.
9. according to claim 1 or 5 described preparing methods, it is characterized in that step 3 is carried out under reducing gas atmosphere, the reducing gas of feeding is CO, and flow velocity is 10-100L/h.
10. lithium ion battery; Comprise positive pole, negative pole and be arranged at the barrier film between positive pole, the negative pole; Said positive pole comprises positive electrode collector and is coated on the positive electrode active materials on the positive electrode collector; It is characterized in that said positive electrode active materials adopts and prepares like any described preparation method of claim 1-9.
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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 |
| CN107785570A (en) * | 2016-08-24 | 2018-03-09 | 德阳威旭锂电科技有限责任公司 | A kind of preparation method for improving olivine structural electrode material hydro-thermal method yield |
| CN112928268A (en) * | 2021-04-01 | 2021-06-08 | 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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