CN101494288B - Preparation method for lithium ion secondary battery anode material ferric lithium phosphate - Google Patents
Preparation method for lithium ion secondary battery anode material ferric lithium phosphate Download PDFInfo
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- CN101494288B CN101494288B CN2008100652071A CN200810065207A CN101494288B CN 101494288 B CN101494288 B CN 101494288B CN 2008100652071 A CN2008100652071 A CN 2008100652071A CN 200810065207 A CN200810065207 A CN 200810065207A CN 101494288 B CN101494288 B CN 101494288B
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Abstract
A method for preparing lithium iron phosphate which is a cathode material of lithium ion secondary battery, the method comprises the following procedures: A. a lithium source compound, a bivalence iron source compound, a phosphorus source compound and a small organic molecular carbon source additive are mixed, ball ground and sintered to obtain a sintering precursor; and B. the sintering precursor which is obtained from the procedure A and an organic high molecular polymer carbon source additive are mixed, ball ground, sintered and crushed to obtain the lithium iron phosphate power of finished products. In the method, the carbon source is added into the precursor in two steps: adding the organic small organic molecular carbon source first and then adding the organic high molecular polymercarbon source, thus obtaining a lithium iron phosphate carbon with good packing effect. The large current discharge performance of the battery made of the lithium iron phosphate is obviously raised.
Description
Technical field
The invention relates to a kind of preparation method of cell positive material, more particularly, is the preparation method about a kind of lithium ion secondary battery anode material ferric lithium phosphate.
Background technology
Lithium ion battery has been widely used in fields such as mobile communication, notebook computer, video camera, camera, portable instrument as the high-energy-density chemical power source, also be the electric automobile studied energetically of various countries, the first-selected supporting power supply of space power system, become the first-selection of the alternative energy.LiFePO4 (LiFePO
4) be the research focus of active substance of lithium ion battery anode.LiFePO
4Compare with other battery with positive active material as lithium ion battery and to have good electrochemical, charge and discharge platform is very steady, Stability Analysis of Structures in the charge and discharge process, and having nontoxic, pollution-free, advantage such as security performance is good, can use under hot environment, raw material wide material sources, is the competitively focus of developmental research of current battery circle.But LiFePO
4The poor electric conductivity of material is to have limited its commercial applications at the bottom of the tap density.
And at LiFePO
4The material poor electric conductivity has multiple improvement method, comprises carbon coating and metal ion mixing etc., and wherein the carbon coating is generally to adopt and the good a kind of method of effect.At present, preparation carbon coats LiFePO
4Method in, solid phase method technology is simple, use equipment realizes easily, realizes the earliest in industrialization.Mainly comprising two kinds in the existing solid phase synthesis process, a kind ofly be---the divalence source of iron is as the preparation method of reaction raw materials; Another kind is---ferric iron source is as the preparation method of reaction raw materials.
CN1401559A discloses a kind of method preparing phosphate iron lithium, and this method comprises the steps:
1) lithium salts, ferrous salt and phosphate are mixed in proportion, wherein Li: Fe: the mol ratio of P is (0.97-1.2) 1: 1;
2) mixture is milled 1-2 hour, mix an amount of alcohol when milling;
3) then the material that mixes is put into pyrolysis oven, flow velocity be the 0.01-50 liter/minute, be preferably in the 2-10 liter/minute inert gas protection in heat pre-treatment, heating rate is 1-20 ℃/minute, pretreatment temperature maintains 100-500 ℃, and pretreatment time was at 1-30 hour;
4) treat to take out material when temperature is reduced to room temperature, grind again behind adding alcohol and the carbon black, amounts of carbon black is 1-10%;
5) mix after, material is put into pyrolysis oven carries out high-temperature heat treatment, temperature maintenance is at 500-900 ℃, heat treatment time is 10-48 hour, is cooled to room temperature then.
The LiFePO4 performance of this method preparation is unsatisfactory; the carbon covered effect is also bad; reason is that this method adds carbon source again after first sintering; owing to decomposing substantially fully through the material behind the first sintering; the LiFePO4 particle begins to take shape; the particle of this moment is very real basically; the carbon that deposits during sintering in the second time is difficult to be penetrated in the middle of the particle again; and can only deposit to the surface of particle; therefore be easy to break away from from LiFePO4; though material pattern for preparing like this and particle diameter etc. are all better; but because carbon is not mixed in the particle the inside, so such conductivity of electrolyte materials is still very low, chemical property was good when the battery that adopts this positive electrode to prepare carried out the low range discharge; but when this material was applied to the electrokinetic cell that requires high-multiplying power discharge, the heavy-current discharge performance of battery was poor.
Summary of the invention
The objective of the invention is defective, a kind of method preparing phosphate iron lithium that makes battery have good heavy-current discharge performance is provided for the heavy-current discharge performance difference that overcomes the battery that the LiFePO4 that adopts prior art for preparing prepares.
The invention provides a kind of preparation method of lithium ion secondary battery anode material ferric lithium phosphate, described method comprises the steps:
A, Li source compound, ferrous iron source compound, P source compound and organic molecule carbon source additive are mixed, ball milling carries out sintering in inert atmosphere, obtain sintered precursor; The molecular weight of described organic molecule carbon source additive is 60～500, and addition is that to make the theoretical phosphorus content of LiFePO4 of final generation be 0.5wt%～2.0wt%;
B, the sintered precursor that obtains in the steps A and organic high molecular polymer carbon source additive are mixed, ball milling carries out sintering in inert atmosphere, pulverize, and obtains the finished product lithium iron phosphate powder; The molecular weight of described organic high molecular polymer carbon source additive is 20000～300000, and addition is that to make the theoretical phosphorus content of LiFePO4 of final generation be 2.0wt%～6.0wt%.
Described organic molecule carbon source additive is one or several in glucose, sucrose, tartaric acid, urea, citric acid, gluconic acid, the cellobiose; Described organic high molecular polymer carbon source additive is one or several in polyethylene glycol, polyvinyl alcohol, POLYPROPYLENE GLYCOL, soluble starch, phenolic resins, the epoxy resin.It is 0.5wt%～1.0wt% that the addition of described organic molecule carbon source additive is preferably the theoretical carbon content of the LiFePO4 that makes final generation; It is 3.0wt%～5.0wt% that the addition of described organic high molecular polymer carbon source additive is preferably the theoretical carbon content of the LiFePO4 that makes final generation.
The carbon containing mass ratio of described organic high molecular polymer carbon source additive and described organic molecule carbon source additive is 1～12: 1, and promptly the carbon containing quality of organic molecule carbon source additive is 1～6: 1 on the carbon containing mass ratio of organic high molecular polymer carbon source additive.
Sintering temperature is 300-500 ℃ described in the inventive method steps A, is preferably 400-500 ℃, and the constant temperature sintering time is 5-15 hour, is preferably 6-10 hour; Sintering temperature is 600-800 ℃ among the step B, is preferably 650-750 ℃, and the constant temperature sintering time is 5-20 hour, is preferably 8-15 hour.
General small organic molecule just can reach complete pyrolysis about 350 ℃, decompose fully but this temperature can not guarantee other raw material.If raw material decompose not exclusively, so in the sintering process of step B, the remainder carbon source additive that plays the coating effect that adds behind the steps A sintering can be subjected to the influence that gas expands equally when deposition coats, the carbon structure that causes depositing out loosens, the out-of-flatness of the particle surface utmost point, and tap density is undesirable, therefore, the sintering temperature of described steps A is preferably about 400-500 ℃, can guarantee that like this raw material all decompose fully, simultaneously LiFePO
4Be in the critical stage of sinter molding under this temperature, the deposition of carbon coated when the state of material more helped step B sintering at this moment.
The mol ratio of Li in described lithium compound, iron compound and the phosphorus compound: Fe: P is (1-1.05): 1: 1.
Described iron compound can be selected from various ferrous iron source compound as the preparation LiFePO4 well known in the art, as, can be selected from Fe
2C
2O
4, Fe (CH
3COO)
2, FeCl
2, FeSO
4And Fe
3(PO
4)
2In one or more.
Described lithium compound can be selected from various lithium compound as the preparation LiFePO4 well known in the art, as, can be selected from Li
2CO
3, LiOH, Li
2C
2O
4, CH
3COOLi, LiH
2PO
4And Li
3PO
4In one or more.
Described phosphorus compound can be selected from various phosphorus compound as the preparation LiFePO4 well known in the art, as, can be selected from NH
4H
2PO
4, (NH
4)
2HPO
4, Li
3PO
4(NH
4)
3PO
4In one or more.
According to the present invention, oxidized in order to prevent divalent iron salt, described sintering preferably carries out in inert atmosphere, described inert atmosphere refers to not any one gas or the admixture of gas with reactant and product generation chemical reaction, as in hydrogen, nitrogen, carbon monoxide, decomposed ammonia and the periodic table of elements zero group gas one or more.This inertia or reducing atmosphere can be static atmosphere, be preferably gas flow rate and be the 2-50 liter/minute flowing nitrogen atmosphere.
Beneficial effect of the present invention:
(1) the invention provides in two step of the LiFePO4 carbon method for coating, the organic molecule carbon source of adding during A step sintering is decomposed the carbon granules that obtains and is distributed in LiFePO4 intercrystalline and grain surface preferably, and the organic high molecular polymer carbon source of adding during B step sintering is decomposed the just in time complete fine and close coated LiFePO 4 for lithium ion batteries particle surface of carbochain that obtains, and therefore obtains LiFePO 4 material carbon covered effect and conductivity excellence.
(2) the LiFePO 4 material conductivity of method preparation provided by the invention is significantly improved, thereby the lithium battery heavy-current discharge performance that uses this material to make is very excellent.
(3) method provided by the invention has solved the problem of iron phosphide dephasign: in the LiFePO4 industrial processes, because the industrial atmosphere heating furnace body that sintering uses is longer, organic carbon source pyrolysis meeting produces reducibility gas (as hydrogen, carbon monoxide etc.) in sintering process, these reducibility gas can not in time be discharged to outside the body of heater than length owing to body of heater, therefore these reducibility gas at high temperature can reduce phosphorus in the phosphoric acid dihydro amine in the presoma and the iron in the ferrous oxalate, at high temperature generate dephasign ferrophosphorus compound.And adopting the present invention because steps A adds carbon source in a lower scope, the concentration of reducibility gas in body of heater that those carbon source pyrolysis produce is lower, does not enough reduce phosphorus and iron in the presoma, does not have dephasign ferrophosphorus compound and generates.Therefore our bright preparation LiFePO 4 material crystalline phase is single, does not contain dephasign.
Description of drawings:
Fig. 1 schemes for the SEM of the LiFePO4 that employing embodiments of the invention 1 prepare;
Fig. 2 is the XRD diffraction pattern of the LiFePO4 that adopts embodiments of the invention 1 and prepare;
The XRD diffraction pattern of the LiFePO4 that Fig. 3 prepares for the method for Comparative Examples 1 of the present invention.
Embodiment
Embodiment 1
This embodiment illustrates the preparation of anode active material of phosphate iron lithium provided by the invention
(1) with 50 moles of Li
2CO
3, 100 moles of FeC
2O
42H
2O, 50 moles of NH
4H
2PO
4Mix (Li: Fe: the P mol ratio is 1: 1: 1) with 438.6g glucose with the 10kg absolute ethyl alcohol, in ball grinder,, take out, 70 ℃ of oven dry with 300 rev/mins speed ball milling 12 hours; Be under 10 liters/minute the argon shield at flow velocity, the mixture of step (1) was warming up to 450 ℃ of constant temperature sintering 6 hours with 2 ℃/minute programming rate, obtain sintered precursor;
(2) sintered precursor is naturally cooled to room temperature, add the 584.28g polyvinyl alcohol then, and mix, in ball grinder,, take out, 70 ℃ of oven dry with 150 rev/mins speed ball milling 1 hour with the 5kg absolute ethyl alcohol; Be under 10 liters/minute the argon shield at flow velocity, mixture was warming up to 700 ℃ of constant temperature sintering 10 hours with 10 ℃/minute programming rate, naturally cool to room temperature, comminution by gas stream obtains the LiFePO of carbon coated
4Composite material.
The above-mentioned composite ferric lithium phosphate material that obtains is crossed 200 mesh sieves, record its median particle diameter D
50Be 2.2 microns, D
95Be 6.5 microns, tap density is 1.10 grams per milliliters.
The XRD diffraction pattern of this LiFePO4 that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records as shown in Figure 1; The SEM that adopts day SSX-550 type ESEM of island proper Tianjin company (Shimadzu) production to record this LiFePO4 schemes as shown in Figure 2.
This embodiment illustrates the preparation of anode active material of phosphate iron lithium provided by the invention
Method according to embodiment 1 prepares LiFePO4, and different is to change organic molecule carbon source additive in the step (1) into sucrose; Change organic high molecular polymer carbon source additive in the step (2) into polyethylene glycol, other step, each material usage ratio and condition are with embodiment 1.
The above-mentioned finished product lithium iron phosphate composite material that obtains is crossed 200 mesh sieves, record its median particle diameter D
50Be 2.5 microns, D
95Be 6.5 microns, tap density is 1.17 grams per milliliters.
Embodiment 3
This embodiment illustrates the preparation of anode active material of phosphate iron lithium provided by the invention
Method according to embodiment 1 prepares LiFePO4, and different is, changes the addition of organic molecule carbon source additive glucose in the step (1) into 217.7g; Change the addition of organic polymer carbon source additive polyvinyl alcohol in the step (2) into 1841.9g, other step, each material usage ratio and condition are with embodiment 1.
The above-mentioned composite ferric lithium phosphate material that obtains is crossed 200 mesh sieves, record its median particle diameter D
50Be 2.5 microns, D
95Be 6.8 microns, tap density is 1.06 grams per milliliters.
This embodiment illustrates the preparation of anode active material of phosphate iron lithium provided by the invention
(1) with 50 moles of Li
2CO
3, 100 moles of FeC
2O
42H
2O, 100 moles of NH
4H
2PO
4Mix (Li: Fe: the P mol ratio is 1: 1: 1) with 377.9g sucrose with the 10kg absolute ethyl alcohol, in ball grinder,, take out, 70 ℃ of oven dry with 300 rev/mins speed ball milling 12 hours; Be under 10 liters/minute the argon shield at flow velocity, the mixture of step (1) was warming up to 500 ℃ of constant temperature sintering 6 hours with 2 ℃/minute programming rate, obtain sintered precursor;
(2) sintered precursor is naturally cooled to room temperature, add 517.52 polypropylenes then, and mix, in ball grinder,, take out, 70 ℃ of oven dry with 150 rev/mins speed ball milling 1 hour with the 5kg absolute ethyl alcohol; Be under 10 liters/minute the argon shield at flow velocity, mixture was warming up to 750 ℃ of constant temperature sintering 10 hours with 10 ℃/minute programming rate, naturally cool to room temperature, comminution by gas stream obtains mixing and the LiFePO of carbon coated
4Composite material.
The above-mentioned composite ferric lithium phosphate material that obtains is crossed 200 mesh sieves, record its median particle diameter D
50Be 2.6 microns, D
95Be 7.1 microns, tap density is 1.14 grams per milliliters.
Embodiment 5
This embodiment illustrates the preparation of anode active material of phosphate iron lithium provided by the invention
(1) with 50 moles of Li
2CO
3, 100 moles of FeC
2O
42H
2O, 100 moles of NH
4H
2PO
4Mix (Li: Fe: the P mol ratio is 1: 1: 1) with 100.42g tartaric acid with 8kg acetone, in ball grinder,, take out, 50 ℃ of oven dry with 300 rev/mins speed ball milling 12 hours; Be under 10 liters/minute the argon shield at flow velocity, the mixture of step (1) was warming up to 450 ℃ of constant temperature sintering 6 hours with 2 ℃/minute programming rate, obtain sintered precursor;
(2) sintered precursor is naturally cooled to room temperature, add 961.73g soluble starch epoxy resin then, and mix, in ball grinder,, take out, 50 ℃ of oven dry with 150 rev/mins speed ball milling 1 hour with 4kg acetone; Be under 10 liters/minute the argon shield at flow velocity, mixture was warming up to 700 ℃ of constant temperature sintering 10 hours with 10 ℃/minute programming rate, naturally cool to room temperature, comminution by gas stream obtains mixing and the LiFePO of carbon coated
4Composite material
The above-mentioned composite ferric lithium phosphate material that obtains is crossed 200 mesh sieves, record its median particle diameter D
50Be 2.6 microns, D
95Be 8.0 microns, tap density is 1.04 grams per milliliters.
Comparative Examples 1
The reference preparation method of this Comparative Examples explanation anode active material of phosphate iron lithium
(1) with 50 moles of Li
2CO
3, 100 moles of FeC
2O
42H
2O and 100 moles of NH
4H
2PO
4Mix (Li: Fe: the P mol ratio is 1: 1: 1) with the 10kg absolute ethyl alcohol, in ball grinder,, take out, 70 ℃ of oven dry with 300 rev/mins speed ball milling 12 hours; Be under 10 liters/minute the argon shield at flow velocity, the mixture of step (1) was warming up to 450 ℃ of constant temperature sintering 6 hours with 2 ℃/minute programming rate, obtain sintered precursor;
(2) sintered precursor is naturally cooled to room temperature, add glucose 2765.2g then and mix, in ball grinder,, take out, 70 ℃ of oven dry with 150 rev/mins speed ball milling 1 hour with the 5kg absolute ethyl alcohol; Be under 10 liters/minute the argon shield at flow velocity, mixture was warming up to 700 ℃ of constant temperature sintering 10 hours with 10 ℃/minute programming rate, naturally cool to room temperature, comminution by gas stream obtains mixing and the LiFePO of carbon coated
4Composite material.
The above-mentioned composite ferric lithium phosphate material that obtains is crossed 200 mesh sieves, record its median particle diameter D
50Be 2.5 microns, D
95Be 7.0 microns, tap density is 1.18 grams per milliliters.
Comparative Examples 2
The reference preparation method of this Comparative Examples explanation anode active material of phosphate iron lithium
(1) with 0.1 mole of Li
2CO
3, 0.2 mole of FeC
2O
42H
2O, 0.2 mole of NH
4H
2PO
4Mix (Li: Fe: the P mol ratio is 1: 1: 1) with 2765.2g glucose with the 10kg absolute ethyl alcohol, in ball grinder,, take out, 70 ℃ of oven dry with 300 rev/mins speed ball milling 12 hours; Be under 10 liters/minute the argon shield at flow velocity, the mixture of step (1) was warming up to 450 ℃ of constant temperature sintering 6 hours with 2 ℃/minute programming rate, obtain sintered precursor;
(2) sintered precursor is naturally cooled to room temperature, add the 5kg absolute ethyl alcohol then and mix, in ball grinder,, take out, 70 ℃ of oven dry with 150 rev/mins speed ball milling 1 hour; Be under 10 liters/minute the argon shield at flow velocity, mixture was warming up to 700 ℃ of constant temperature sintering 10 hours with 10 ℃/minute programming rate, naturally cool to room temperature, comminution by gas stream obtains mixing and the LiFePO of carbon coated
4Composite material.
The above-mentioned composite ferric lithium phosphate material that obtains is crossed 200 mesh sieves, record its median particle diameter D
50Be 4.2 microns, D
95Be 9.8 microns, tap density is 0.78 grams per milliliter.
Comparative Examples 3
The preparation method of the anode active material of phosphate iron lithium of this Comparative Examples explanation prior art
Method according to the disclosed embodiment 1 of CN1401559A prepares LiFePO4.
Embodiment 6-10
The following examples explanation is carried out performance test to battery after adopting anode active material of phosphate iron lithium provided by the invention to be prepared into battery.
(1) preparation of battery
Anodal preparation
Restrain the positive active material LiFePO that makes by embodiment 1-5 with 80 respectively
4Composite material, 10 gram binding agent Kynoar (PVDF) and 10 gram conductive agent acetylene blacks join in the 50 gram N-methyl pyrrolidones, stir in de-airing mixer then and form uniform anode sizing agent.
This anode sizing agent is coated on the both sides that thickness is 20 microns aluminium foil equably, 150 ℃ of following oven dry, roll-ins then, cuts to make and be of a size of 540 * 43.5 millimeters positive pole, wherein contain the 2.8 gram active component LiFePO that have an appointment
4
The preparation of negative pole
100 gram negative electrode active composition native graphites, 5 gram conductive agent acetylene blacks, 5 gram bonding agent Kynoar are joined in the 100 gram N-methyl pyrrolidones, in de-airing mixer, stir then and form uniform cathode size.
This cathode size is coated on the both sides that thickness is 12 microns Copper Foil equably, then in 90 ℃ of following oven dry, roll-in, cut to make and be of a size of 500 * 44 millimeters negative pole, wherein contain the 2.6 gram active component native graphites of having an appointment.
The assembling of battery
Respectively above-mentioned positive and negative electrode and polypropylene screen are wound into the pole piece of a square lithium ion battery, subsequently with LiPF
6Concentration by 1 mol is dissolved in EC/EMC/DEC=1: form nonaqueous electrolytic solution in 1: 1 the mixed solvent, this electrolyte is injected the battery aluminum hull with the amount of 3.8g/Ah, lithium rechargeable battery A1-A5 is made in sealing respectively.
(2) battery performance test
The cycle performance test:
The above-mentioned lithium ion A1-A5 battery that makes is placed on test respectively cashier's office in a shop, and carrying out the supreme pressure of rationing the power supply of constant current charge with 0.1C earlier is 3.8 volts, and constant voltage charge is 2.5 hours then; After shelving 20 minutes, be discharged to 3.0 volts, the discharge capacity first of record battery from 3.8 volts with the electric current of 0.1C, after repeating above-mentioned steps 50 times then, obtain the capacity after the battery charging and discharging circulation 50 times, the discharge capacity of record battery, by capacity sustainment rate before and after the following formula computation cycles:
Capacity sustainment rate=(the 50th cyclic discharge capacity/cyclic discharge capacity) first * 100%
The heavy-current discharge performance test:
Earlier battery being carried out the supreme pressure of rationing the power supply of constant current charge with the 0.1C electric current is 3.8 volts, and constant voltage charge is 2.5 hours then; After shelving 20 minutes, be discharged to 3.0 volts with the electric current of 1C, 2C and 5C from 3.8 volts respectively, the ratio of the discharge capacity when writing down the discharge capacity of each battery and calculating respectively with the 0.1C discharge, that is:
C
1C/ C
0.1C: the electric current with 1C is discharged to the discharge capacity of 3.0V and the ratio that is discharged to the discharge capacity of 3.0V with the electric current of 0.1C from 3.8V from 3.8V;
C
2C/ C
0.1C: the electric current with 2C is discharged to the discharge capacity of 3.0V and the ratio that is discharged to the discharge capacity of 3.0V with the electric current of 0.1C from 3.8V from 3.8V;
C
5C/ C
0.1C: the electric current with 5C is discharged to the discharge capacity of 3.0V and the ratio that is discharged to the discharge capacity of 3.0V with the electric current of 0.1C from 3.8V from 3.8V.
The result is as shown in table 1 below.
Comparative Examples 4-6
After the anode active material of phosphate iron lithium that following Comparative Examples explanation adopts prior art to obtain is prepared into battery battery is carried out performance test.
Method according to embodiment 6-10 prepares reference cell AC1-AC3, and the discharge capacity first of test battery and the cycle performance of battery, and the specific discharge capacity of counting cell and volume and capacity ratio, different is the reference anode active material of phosphate iron lithium that the positive active material of preparation used in battery obtains for Comparative Examples 1-3.
The result is as shown in table 1 below.
Table 1
With embodiment 1 is example, Fig. 1 serves as reasons and adopts method of the present invention to obtain the stereoscan photograph of 5000 times of the amplifications of LiFePO4, as can be seen from the figure, and the crystalline particle of LiFePO4 size homogeneous, particle size distribution is even, and the diameter of most of particle is between the 1-3 micron.
As can be seen from Figure 2, olivine-type structure and the crystal formation of above-mentioned LiFePO4 with standard physically well develops.
With Comparative Examples 1 is example, and Fig. 3 is the XRD figure that adopts the LiFePO4 that Comparative Examples 1 method prepares, and as can be seen from the figure this LiFePO 4 material possesses olivine structural, but it contains Fe
2The impurity peaks of P.
Data from last table 1 as can be seen, the initial discharge specific discharge capacity of the battery A1-A5 that the LiFePO4 that adopts the inventive method to prepare is made all is higher than the reference cell AC1-AC3 of Comparative Examples; Circulate capacity sustainment rate after 50 times all more than 98%, the more important thing is, the heavy-current discharge performance of battery is especially good, respectively with 1C, 2C and 5C current discharge capacity with 0.1C current discharge Capacity Ratio, the capacity sustainment rate of battery is respectively more than 96%, 92% and 89%, all be higher than reference cell, therefore, illustrate that the heavy-current discharge performance of the battery that the LiFePO4 that adopts method preparation of the present invention prepares is significantly improved.
Claims (8)
1. the preparation method of a lithium ion secondary battery anode material ferric lithium phosphate, described method comprises the steps:
A, Li source compound, ferrous iron source compound, P source compound and organic molecule carbon source additive are mixed, ball milling carries out sintering in inert atmosphere, obtain sintered precursor; The molecular weight of described organic molecule carbon source additive is 60～500, and addition is that to make the theoretical phosphorus content of finished product lithium iron phosphate of final generation be 0.5wt%～2.0wt%;
B, the sintered precursor that obtains in the steps A and organic high molecular polymer carbon source additive are mixed, ball milling carries out sintering in inert atmosphere, pulverize, and obtains the finished product lithium iron phosphate powder; The molecular weight of described organic high molecular polymer carbon source additive is 20000～300000, and addition is that to make the theoretical phosphorus content of finished product lithium iron phosphate of final generation be 2.0wt%～6.0wt%.
2. method according to claim 1, wherein, described organic molecule carbon source additive is one or several in glucose, sucrose, tartaric acid, urea, citric acid, gluconic acid, the cellobiose.
3. method according to claim 1, wherein, described organic high molecular polymer carbon source additive is one or several in polyethylene glycol, polyvinyl alcohol, POLYPROPYLENE GLYCOL, soluble starch, phenolic resins, the epoxy resin.
4. according to claim 1,2 or 3 described methods, wherein, the addition of described organic molecule carbon source additive is that to make the theoretical phosphorus content of finished product lithium iron phosphate of final generation be 0.5wt%～1.0wt%; The addition of described organic high molecular polymer carbon source additive is that to make the theoretical phosphorus content of LiFePO4 of final generation be 3.0wt%～5.0wt%.
5. method according to claim 1, wherein, the carbon containing mass ratio of described organic high molecular polymer carbon source additive and described organic molecule carbon source additive is 1～12: 1.
6. method according to claim 1, wherein, sintering temperature is 300-500 ℃ in the described steps A, the constant temperature sintering time is 5-15 hour; Sintering temperature is 600-800 ℃ among the described step B, and the constant temperature sintering time is 5-20 hour.
7. method according to claim 1, wherein, the mol ratio of Li: Fe: P is (1-1.05) in described Li source compound, ferrous iron source compound and the P source compound: 1: 1.
8. according to claim 1,2 or 3 described methods, wherein, described Li source compound is selected from Li
2CO
3, LiOH, Li
2C
2O
4, CH
3COOLi, LiH
2PO
4And Li
3PO
4In one or more; Described ferrous iron source compound is selected from Fe
2C
2O
4, Fe (CH
3COO)
2, FeCl
2, FeSO
4And Fe
3(PO
4)
2In one or more; Described P source compound is selected from NH
4H
2PO
4, (NH
4)
2HPO
4, Li
3PO
4(NH
4)
3PO
4In one or more.
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| CN101789502A (en) * | 2010-03-12 | 2010-07-28 | 江苏工业学院 | Metal ion doping and carbon coating jointly modified lithium ion battery anode material |
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| CN102024944A (en) * | 2010-11-17 | 2011-04-20 | 上海纳米技术及应用国家工程研究中心有限公司 | Method used for preparing anode material lithium titanate of lithium ion secondary battery |
| CN102064324A (en) * | 2010-12-14 | 2011-05-18 | 上海纳米技术及应用国家工程研究中心有限公司 | Lithium titanate anode material for modified lithium ion power batteries and preparation method thereof |
| CN102126715A (en) * | 2011-02-12 | 2011-07-20 | 新乡市中科科技有限公司 | Preparation method of spherical lithium iron phosphate |
| CN102403495A (en) * | 2011-11-25 | 2012-04-04 | 昆明理工大学 | Method for preparation of composite anode material of carbon-coated lithium-ion battery |
| CN102522546B (en) * | 2011-12-27 | 2014-11-19 | 连云港华海诚科电子材料有限公司 | Method for preparing lithium iron phosphate serving as cathode material of nano-level lithium ion battery |
| CN102751495B (en) * | 2012-07-09 | 2014-05-21 | 四川九驰能源科技股份有限公司 | Method for controlling shape and carbon content of iron phosphate material |
| CN102881904A (en) * | 2012-10-28 | 2013-01-16 | 桂林理工大学 | Method for preparing double-carbon-source coated LiFePO4/C composite anode material through two-step sintering |
| CN103456924B (en) * | 2013-08-29 | 2015-10-28 | 合肥国轩高科动力能源股份公司 | Take high molecular polymer as the preparation method of carbon source secondary carbon-coated LiFePO 4 for lithium ion batteries compound |
| CN104466174A (en) * | 2013-09-23 | 2015-03-25 | 华东理工大学 | Cathode active substance for lithium ion battery and preparation method thereof |
| CN103794760B (en) * | 2013-12-20 | 2016-10-12 | 中国科学院理化技术研究所 | Ternary carbon source coated lithium iron phosphate composite material and preparation method thereof |
| CN107240696A (en) * | 2017-07-12 | 2017-10-10 | 北方奥钛纳米技术有限公司 | The preparation method and carbon-coated LiFePO 4 for lithium ion batteries and lithium ion battery of carbon-coated LiFePO 4 for lithium ion batteries |
| CN108675276A (en) * | 2018-05-24 | 2018-10-19 | 深圳市毓丰新材料有限公司 | LiFePO4 and preparation method thereof |
| CN108899540A (en) * | 2018-05-25 | 2018-11-27 | 佛山市德方纳米科技有限公司 | Composite ferric lithium phosphate material and preparation method thereof and lithium ion battery |
| CN110380025B (en) * | 2019-06-27 | 2021-10-08 | 湖南雅城新材料有限公司 | Carbon-coated lithium iron phosphate process, prepared carbon-coated lithium iron phosphate and application thereof |
| CN111129492A (en) * | 2019-12-26 | 2020-05-08 | 中天新兴材料有限公司 | Preparation method of lithium iron phosphate material |
| CN111342015B (en) * | 2020-03-06 | 2022-05-06 | 合肥国轩高科动力能源有限公司 | High-compaction low-resistance lithium iron phosphate and preparation method thereof |
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| CN1649189A (en) * | 2004-12-29 | 2005-08-03 | 浙江大学 | Method for preparing carbon coated lithium ferrous phosphate composite material including metal conductive agent |
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