CN101752564A - Hydrothermal synthesis method of LiFePO4 of anode material of lithium ion battery with one-dimensional nanometer structure - Google Patents
Hydrothermal synthesis method of LiFePO4 of anode material of lithium ion battery with one-dimensional nanometer structure Download PDFInfo
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Abstract
The invention discloses a hydrothermal synthesis method of LiFePO4 of anode material of lithium ion battery with one-dimensional nanometer structure, which comprises the steps of: 1. respectively adding lithium hydroxide solution and phosphoric acid, evenly adding iron source solution with a certain speed, wherein the molar ratio of the proportion of the added materials Li: Fe: P is 3.0:1.0:1.0-1.15, stirring 10-30 for minutes, adding pH value adjusting agent, leading the initial pH value of a reaction system to be 6.5-8.0, and reacting for 60-480 minutes at 40-180 DEG C; 2. filtering, washing and drying resultant; and 3. packing carbon. The hydrothermal synthesis method can take raw material solution for generating ferrous sulfate as iron source, produces a product with good performance by adjusting the pH value of the reaction system and controlling the feeding speed, eliminates working procedures for crystallizing and drying the ferrous sulfate and the like, is good for reducing water electricity consumption, and has less equipment investment, simple and controllable technology and good batch stability of the product.
Description
Technical field
The invention belongs to the anode material for lithium-ion batteries preparation, specifically a kind of hydrothermal synthesis method of lithium ion battery anode material lithium iron phosphate of one-dimensional nano structure.
Technical background
LiFePO4 is used for the existing more than ten years of report of anode material for lithium-ion batteries, receives very big concern because of it has fail safe, inexpensive property, environment friendly.Because this shortcoming of low conductivity of material progressively is modified, therefore having had a certain amount of is that anodal battery puts goods on the market with the LiFePO4 in recent years.Yet its height charges and discharge the actual requirement of these performance index of high rate performance and still has certain gap.Reducing the coating of particle diameter and carbon is the most effective two kinds of methods.Reducing aspect the particle diameter, the particle diameter of material can be prepared into nanoscale, nanoscale level compound has been proved to be and it has been reached be bordering on its theoretical capacity, the electrochemical reaction of battery is long-pending to be increased but its significant surface area growth can make, side reaction (K.Zagbib, M.Dontigny, P.Charest in the aggravation battery, et al., Aging of LiFePO
4Upon exposure to H
2O[J] .Journal of Power Sources 185 (2008): 698-710), simultaneously, the demanding binder dosage of big surface area easily causes electrode coating performance variation or influences electric conductivity because of binder dosage increases.The synthetic LiFePO4 of hydro thermal method has one-dimensional nano structure, be flat crystal, fortunately, the thinnest direction is the dispersal direction of lithium ion, the material of this method preparation had both had the evolving path less than 100 nanometers, was unlikely to make the surface area increase of material very big again.In addition, the electrode plates technology of preparing is being developed water-based and slurry technology, is binding agent as replace traditional Kynoar PVDF with butadiene-styrene latex SBR in Chinese patent (application number is 200910064193.6), realizes the application of aqueous binders in positive pole.Compare with the LiFePO4 of solid phase method preparation, the product of hydro thermal method gained has the adaptability of better water-based processing pole piece.We in ZL200710058353.7 with the method that has proposed to prevent to generate the hydro thermal method synthesizing iron lithium phosphate of ferric iron impurity, and in ZL200710058352.2, illustrated with surfactant and controlled granular size, prevent the method for reuniting between particle.But, surfactant can have a negative impact to mother liquor processing and technique waste water processing subsequently, and along with quality difference as the ferrous sulfate of source of iron, the variation of operating conditions such as charging rate, the particle size and the granule-morphology of the product of gained have a great difference, and this will directly influence specific capacity, high rate performance and the bulk density of material.The procedure parameter of hydro-thermal synthesizing iron lithium phosphate comprises: the pH value of crystal growth (reaction system), synthesis temperature, reactant concentration, reducing agent etc.Wherein, this factor of pH value of crystal growth (reaction system) relates to the growth orientation of crystal in the dissolving, course of reaction of presoma intermediate ion, solubility of product etc., is factor the most key in the factors.In the present research or patent report, because of hydrothermal preparation condition difference, the LiFePO4 of preparation presents different patterns, as (Characteristics of lithium iron phosphate (LiFePO4) particles synthesized in subcritical andsupercritical water [J] .J Supercrit.Fluids such as Lee, 2005,35:83-90) with FeSO
47H2O, o-Li
3PO
4With LiOH be raw material in 200 ℃, the synthetic LiFePO of 1h hydro-thermal
4, by regulating the H that adds
2SO
4With the amount of LiOH, investigated the pH value to product LiFePO
4The influence of thing phase shows the LiFePO that only could obtain pure phase under neutrality or weak basic condition with XRD analysis
4Particle is than impurity F e is arranged under the strong alkaline condition
3O
4And Li
3PO
4With LiFePO
4Thing coexists mutually.At optimal conditions pH=9.2, lithium: iron: the mol ratio of phosphorus is 3: 1: 1,190 ℃ of reaction 1h, when reactant concentration is 0.1M, obtaining the length of side is the hexagon flaky crystal of 1 μ m, when reactant concentration surpassed 0.3M, intergranular reunion increased, and the chemical property of prepared material is not reported in this research.Yang etc. (Reactivity, stability and electrochemical behavior of lithiumiron phosphate[J] .Electrochem Commun, 2002,4 (3): 239-244.) with FeSO
4, H
3PO
4Carried out hydrothermal synthesis reaction in 1: 1: 3 in molar ratio with LiOH solution, earlier with FeSO
4, H
3PO
4Solution mixes stirring, adds LiOH solution then to prevent Fe (OH)
2Oxidation, the pH value of solution keeps 7.56 behind the mixing, then mixed liquor is heated more than the 5h down at 120 ℃.Reacting the cooling back pH value of solution value that finishes is 6.91, obtains the diamond platy crystallization, and average grain diameter is about 3 μ m.Sample after the carbon coated is at 0.14mAcm
-2The current density charge/discharge capacity is 100mAhg
-1, the low range capacity of this material is lower, and high rate capability more can't be expected.(Electrochemical properties of LiFePO such as Dokko
4Prepared via hydrothermalroute[J] .Journal of Power Sources 2007,165:656-659) with LiOH, FeSO
47H
2O and (NH
4)
2HPO
4For raw material in synthetic Li: Fe: the P=x of 170 ℃, 12h hydro-thermal: the LiFePO of 1: 1 (x=1,2,3)
4, the pH value of precursor solution is respectively 8.04,8.99,9.54.When x=1 and 2, LiFePO
4No dephasign generates; When x=3, under strong alkaline condition, there is dephasign Li
3PO
4And Fe
2(PO
4) OH; When x=1 and 2, obtain square sheet and diamond platy crystallization respectively, all exist agglomeration, particle size to be respectively 3 μ m and 0.5 μ m between particle, the pH value of visible particle pattern and size and precursor solution is closely related, the LiFePO of x=2
4Sample behind 400 ℃, 1h high-temperature calcination, the discharge capacity of the specific capacity of material under the 0.1C multiplying power is 150mAhg
-1Under this condition, though the low range capacity of the material that obtains is higher, the high rate capability of material is not good, and the discharge capacity under 1C, 2C multiplying power is 110mAhg
-1, 80mAhg
-1Chen etc. (Hydrothermalsynthesis of lithium iron phosphate[J] .Journal of Power Sources 174 (2007): 442-448) with H
3PO
4, FeSO
47H
2O, LiOH and hydrazine are raw material, with 200 ℃ of mixed liquors, the synthetic LiFePO of 6h hydro-thermal
4, add H
3PO
4The pH value of regulating mixed solution is 6.00 (faintly acids), and the pH value of solution value is 5.67 behind the hydrothermal synthesis reaction.From SEM figure as can be seen during pH=6, the particle sheet that is rectangle, during pH=10, the particle sheet that assumes diamond in shape.By in the above document as seen, the difficult control of the crystal morphology of LiFePO4, existing technology is synthesized under different condition (temperature, raw material), can obtain the crystal of different-shape in same pH value scope, but the high rate performance of resulting crystal is relatively poor.Another problem that can not be ignored is; ferrous sulfate is a heptahydrate; because crystallization condition and drying condition is different; usually can cause that water content and acid content have bigger difference in the ferrous sulfate; it is the raw material batch instability; directly influence the pH value of reaction system when being used for synthesizing iron lithium phosphate, and then the pattern of product and performance, cause batch instability of product.In fact, be in the process of raw material synthesizing iron lithium phosphate with phosphoric acid, lithium hydroxide, soluble ferrite, lithium ion in the material liquid is surpassing theoretical ratio 1 o'clock with the mol ratio of phosphate anion, and the part that surpasses mainly plays pH value regulating action except that increasing lithium ion intensity.Therefore, control pH value and crystal nucleation speed are the keys of control product pattern and granular size.
Summary of the invention
Technical problem to be solved by this invention is: at the crystal morphology that exists in the current techniques, granularity be difficult to control, the reluctant problem of high rate performance waste water relatively poor, that contain surfactant of product, a kind of method of hydro-thermal synthesizing lithium ionic cell positive pole material lithium iron phosphate is provided.The present invention is by the generation quantity and then the control granular size of control charging rate control nucleus; By the pH value control crystal morphology of conditioned reaction system, obtain having nano-sheet crystallization---the lithium ion battery anode material lithium iron phosphate of one-dimensional nano structure of similar round.
The technical solution adopted in the present invention is:
A kind of hydrothermal synthesis method of lithium ion battery anode material lithium iron phosphate of one-dimensional nano structure may further comprise the steps:
The first step, hydrothermal synthesis reaction
Lithium hydroxide is water-soluble, be made into 3.2～4.8mol/L lithium hydroxide solution, add in the autoclave, add phosphoric acid again, behind the air in the dead volume in the inert gas purge still, sealing autoclave, stir down and be heated to 40～50 ℃ from room temperature, open inlet valve and vent valve, at the uniform velocity added source of iron solution again in 9～13 minutes, the proportioning that wherein adds material is mol ratio Li: Fe: P=3.0: 1.0: 1.0～1.15, stir after 10～30 minutes, add pH value conditioning agent, continue to stir, the initial pH value that makes reaction system is 6.5～8.0, and then sealing autoclave, in 140～180 ℃ of reactions 60～480 minutes, this moment, the self-generated pressure corresponding to system was 0.36～1.0Mpa; Wherein, pH value conditioning agent is lithium hydroxide solution or sulfuric acid;
Second step, the filtration of product, washing and drying
After above-mentioned reaction was finished, autoclave was cooled fast to 80 ℃ by cooling water, opens bleeder valve, product was filtered and washed till the sulfate radical-free ion, obtained filter cake and mother liquor, and filter cake obtains canescence LiFePO in 60～120 ℃ of vacuumizes 12 hours
4Powder; Mother liquid evaporation concentrates back reclaim sulfuric acid lithium;
In the 3rd step, carbon coats to be handled
LiFePO with the second step gained
4Powder and glucose are pressed mass ratio LiFePO
4Powder: glucose=100: 10～20 mixings under inert gas shielding, in 600～750 ℃ of roastings 4～6 hours, obtains the LiFePO4 product that carbon coats.
Above-mentioned source of iron is by the ferrous sulfate crystal or produces the solution that the material liquid of ferrous sulfate is mixed with that concentration is 0.8～1.2mol/L Fe
2+
The concentration of above-mentioned pH value conditioning agent sulfuric acid is mass percent 1～3%.
The concentration of above-mentioned pH value conditioning agent lithium hydroxide is mass percent 3～5%.
The invention has the beneficial effects as follows:
(1) high-rate discharge ability of product and capacity circulation conservation rate improve.
(2) with lithium hydroxide or sulfuric acid as the pH value conditioning agent of reaction system, do not introduce heterogeneous ion.Use lithium hydroxide as alkaline pH value conditioning agent, avoid using ammoniacal liquor or other alkaline matter to introduce heterogeneous cation; Use sulfuric acid as the acid ph value conditioning agent, have the effect of not introducing heterogeneous ion equally, avoid using phosphoric acid to cause simultaneously and produce the impurity lithium phosphate in the product.
(3) by the pH value of conditioned reaction system, come the pattern of crystallization control, product has the one-dimensional nano structure feature.Avoided taking place the phenomenon of nanoparticle agglomerates at the product that does not generate nanostructure under the low excessively pH value condition with under too high pH value condition.The sheet of product is thick in 100 nanometers, helps the shortening of lithium ion the evolving path, fundamentally helps the raising of high rate performance of material and the prolongation of cycle life.The sheet shape of product is tending towards the circle shape, helps the raising of the compacted density of electrode material, and compacted density can reach 2.2g/ml.
(4) thus by control nucleus formation speed control crystal growth control granular size, rather than adopt surfactant to control granular size, overcome the reluctant problem of the waste water that contains surfactant, greatly simplify the control difficulty of the evaporation technology of mother liquor, do not produce technique waste water COD and handle problems, help production control and reduce cost.
(5) can be source of iron with the material liquid of producing ferrous sulfate in the production process,, produce the product of function admirable, save the operations such as crystallization, drying of ferrous sulfate, help reducing water power consumption by the pH value of conditioned reaction system.
(6) equipment investment is little, technology simple controllable, batch good stability of product.
The above-mentioned beneficial effect of the inventive method is proved in the following example.
Description of drawings
The present invention is further described below in conjunction with drawings and Examples.
The stereoscan photograph of Fig. 1 product, wherein, 1a is embodiment 1, and 1b is a comparative example 1, and 1c is a comparative example 2, and 1d is a comparative example 3.
The discharge curve of Fig. 2 embodiment 1 product
The cyclic discharge capacity conservation rate curve of Fig. 3 embodiment 1 product.
Specific implementation method
The first step, hydrothermal synthesis reaction (Li: Fe: P=3: 1: 1.03)
To contain 223.4g Fe
2+The pure approaching saturated copperas solution of (being 4mol) is diluted to 3.5L (the pH value of this solution is about 0.5); 475.0g 85% phosphoric acid that will contain pure phosphoric acid and be 4.12mol is diluted to 1L; With 503.3g is the LiOHH of 12mol
2O is soluble in water and be diluted to 3L.
Above-mentioned phosphoric acid solution and lithium hydroxide solution are added in the autoclave of 10L band sealing charge pipe and cooling coil, behind the air in the dead volume in inert gas (nitrogen) the purging still, sealing autoclave, rotating speed 200rpm stirs down and is heated to 40 ℃ from room temperature, open inlet valve and vent valve, stir the copperas solution that adding is down prepared above, charging rate is 300ml/min, 11.6 minutes times spent.Sealing autoclave stirred after 20 minutes, opened inlet valve and vent valve, added the lithium hydroxide solution as pH value conditioning agent that has prepared again, and this solution is with 16g LiOHH
2O is dissolved in 300ml water formulated (3%LiOH).Fully stir, this moment, the initial pH value of system was 7.3, sealing autoclave, and in 160 ℃ of reactions 360 minutes, this moment, the self-generated pressure corresponding to system was 0.62Mpa.
Second step, the filtration of product, washing and drying
After above-mentioned reaction was finished, autoclave with water quench to 80 ℃, was opened bleeder valve by coil pipe, product is filtered and washing to using BaCl
2The no SO of solution check
4 2-Till, get 1102g filter cake, 7.3L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 621g LiFePO
4The canescence powder.Mother liquor is gone into recycling can and is used for evaporative crystallization and goes out lithium sulfate.
In the 3rd step, carbon coats to be handled
The product of the second step gained is mixed by mass ratio with glucose at 100: 10, under 700 ℃, nitrogen protection, calcined 4 hours, obtain the LiFePO4 (LiFePO of carbon coating
4/ C) product.
Fig. 1 a is the electron scanning micrograph of present embodiment product, and product is the crystallization with one-dimensional nano structure.The granule-morphology of product is the sheet of similar round, thick about 60～80 nanometers of sheet.Prolonging the thick direction of sheet is the dispersal direction of lithium ion, like this, has shortened the lithium ion the evolving path, thereby helps improving material electrochemical performance and high-rate charge-discharge capability.Results of grain size analysis sees Table 1.
The charge-discharge performance test of present embodiment product: the LiFePO4 LiFePO that the carbon that will obtain above coats
4/ C, acetylene black, 60% ptfe emulsion are pressed 7: 2: 1 mixed of mass ratio, are rolled into the sheet that thickness is 0.10～0.15mm, and press together with aluminium foil, in 120 ℃ of vacuumizes 12 hours, make anode.LiPF with metal lithium sheet negative pole, 1M
6Solution is that electrolyte, cell gard 2300 is barrier film, is assembled into button cell with above-mentioned positive pole, discharges and recharges with 0.2C, 1C, 3C multiplying power, and discharges and recharges with 3C and to carry out cyclic test, and the voltage range that discharges and recharges is 4.2～2.3V.Test result is seen Fig. 2, Fig. 3.The 0.2C of material, 1C, 3C specific capacity are respectively 152.4,143.5 and 135.2mAh/g, and 3C discharges and recharges, after 100 circulations, and capability retention 98.3%.
Comparative example 1
Lithium hydroxide solution as pH value conditioning agent among the embodiment 1 is not added reactor, and the initial pH value of reaction system is 5.0, and other is with embodiment 1.
After synthetic the finishing, filter, washing gets 1089g filter cake, 7.4L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 619g LiFePO4 canescence powder.
Fig. 1 b is the electron scanning micrograph of present embodiment product, and the granule-morphology of product is the sharp-pointed diamond platy of angle, and sheet is thick in 250 nanometers, is unfavorable for the diffusion of lithium ion in material.Electrochemical property test result and results of grain size analysis see Table 1.
Comparative example 2
With the quantitative change as the lithium hydroxide of pH value conditioning agent among the embodiment 1 is 26g, and the initial pH value of reaction system is 10, and other is with embodiment 1.
After synthetic the finishing, filter, washing gets 1098g filter cake, 7.4L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 625g LiFePO
4The canescence powder.
Fig. 1 c is the electron scanning micrograph of present embodiment product, and the granule-morphology of product is four clearly more demarcated limits of corner angle (square or rectangular) shape sheets, thick about 80 nanometers of sheet, but intergranular reunion is more serious.Electrochemical property test result and results of grain size analysis see Table 1.
Comparative example 3
Change the speed that adds copperas solution among the embodiment 1 into 100ml/min, 35 minutes times spent, other is with embodiment 1
After synthetic the finishing, filter, washing gets 1009g filter cake, 7.4L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 620g LiFePO
4The canescence powder.
Fig. 1 d is the electron scanning micrograph of this comparative example product, and the granule-morphology of product is the hexagon sheet of corner angle fuzzy, and thick about 150 nanometers of sheet are not reunited though have between particle, and thicker sheet is unfavorable for the diffusion of lithium ion.Electrochemical property test result and results of grain size analysis see Table 1.
Comparative example 4
Change the speed that adds copperas solution among the embodiment 1 into 600ml/min, 5.8 minutes times spent, other is with embodiment 1
After synthetic the finishing, filter, washing gets 1065g filter cake, 7.4L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 625g LiFePO
4The canescence powder.
The granule-morphology of product is the hexagon sheet of corner angle fuzzy, thick about 100 nanometers of sheet, but the reunion degree is bigger between particle.
Electrochemical property test result and results of grain size analysis see Table 1.
Embodiment 2
With the quantitative change as the lithium hydroxide of pH value conditioning agent among the embodiment 1 is 8g, and the initial pH value of reaction system is 6.5, and other is with embodiment 1.
After synthetic the finishing, filter, washing gets 1080g filter cake, 7.4L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 617g LiFePO
4The canescence powder.
The granule-morphology of product is the hexagon sheet of corner angle fuzzy, and thick about 100 nanometers of sheet do not have reunion substantially between particle.Electrochemical property test result and results of grain size analysis see Table 1.
Embodiment 3
With the quantitative change as the lithium hydroxide of pH value conditioning agent among the embodiment 1 is 22g, and the initial pH value of reaction system is 8.0, and other is with embodiment 1.
After synthetic the finishing, filter, washing gets 1091g filter cake, 7.4L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 619g LiFePO
4The canescence powder.
The granule-morphology of product is the hexagon sheet of corner angle fuzzy, and thick about 90 nanometers of sheet have the agglomeration of less degree between particle.Electrochemical property test result and results of grain size analysis see Table 1.
Embodiment 4
With 1112g is the FeSO of 4mol
47H
2O is soluble in water, and is diluted to 4L, leave standstill 12 hours after, filter, remove a spot of sediment (the pH value of this solution is about 4.0); Take by weighing 484g 85% phosphoric acid (phosphoric acid is 4.2mol); With 502.8g is the LiOHH of 12.0mol
2O is soluble in water and be diluted to 3L; The 5g concentrated sulfuric acid is dissolved in 300ml water (1.6%), as pH value conditioning agent.
Earlier lithium hydroxide solution and phosphoric acid are added reactor, behind the air in the dead volume in the inert gas purge still, sealing autoclave, under stirring, rotating speed 200rpm is heated to 45 ℃ from room temperature, open inlet valve and vent valve, the speed with 400ml/min adds the refining copperas solution of above-mentioned process, 10 minutes times spent again, to add reactor as the above-mentioned sulfuric acid solution of pH value conditioning agent again, the initial pH value of reaction system is 7.8.Sealing autoclave, in 180 ℃ of reactions 60 minutes, this moment, the self-generated pressure corresponding to system was 1.0Mpa.
Second step, the filtration of product, washing and drying
After above-mentioned reaction was finished, autoclave with water quench to 80 ℃, was opened bleeder valve by coil pipe, product is filtered and washing to using BaCl
2The no SO of solution check
4 2-Till, get 1120g filter cake, 7.3L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 624g LiFePO
4The canescence powder.Mother liquor is gone into recycling can and is used for evaporative crystallization and goes out lithium sulfate.
In the 3rd step, carbon coats to be handled
The product of the second step gained is mixed by mass ratio with glucose at 100: 10, under 700 ℃, nitrogen protection, calcined 4 hours, obtain the LiFePO4 (LiFePO of carbon coating
4/ C) product.
The granule-morphology of product is the hexagon/similar round sheet of corner angle fuzzy, thick about 100 nanometers of sheet.Electrochemical property test result and results of grain size analysis see Table 1.
With the quantitative change as the sulfuric acid of pH value conditioning agent among the embodiment 4 is 8g, and the adding speed of copperas solution becomes 350ml/min, i.e. 11.4 minutes times spent.The initial pH value of reaction system is 7.0, and other is with embodiment 4.
After synthetic the finishing, filter, washing gets 1098g filter cake, 7.4L mother liquor.Filter cake is in 120 ℃ of vacuum dryings 12 hours, 618g LiFePO
4The canescence powder.
The granule-morphology of product is the hexagon/similar round sheet of corner angle fuzzy, thick about 90 nanometers of sheet.Electrochemical property test result and results of grain size analysis see Table 1.
From following data as can be seen, the generation quantity of charging rate decision nucleus, charging rate is too fast, and moment generates a large amount of nucleus, easily causes the reunion between nucleus, causes the product particle to become big; Charging rate is too small, and the nucleus amount of generation is few, and it is big that crystalline size becomes, and product does not have the one-dimensional nano structure feature.Under the condition that charging rate is fit to, by the pH value of conditioned reaction system, the pattern of may command crystallization.Under low excessively pH value condition, do not generate the product of nanostructure, the phenomenon of nanoparticle agglomerates takes place under too high pH value condition.The initial pH value of reaction system be 6.5～8.0 and the concentration of source of iron solution be 0.8～1.2mol/L, reinforced time spent are 9～13 minutes (in the 10L still, when the charging rate of source of iron solution is 300～400ml/min), product has the one-dimensional nano structure feature, and respective table reveals splendid chemical property.
The chemical property of table 1 product and results of grain size analysis
| 0.2C specific capacity/ |
1C specific capacity/ |
3C specific capacity/mAhg -1 | 3C100 circulation back capability retention/% | ??D50??/ | |
| Embodiment | |||||
| 1 | ??152.4 | ??143.5 | ??135.2 | ??98.3 | ??1.47 |
| Comparative example 1 | ??1261 | ??108.5 | ??55.1 | ??- | ??3.12 |
| Comparative example 2 | ??130.4 | ??113.5 | ??90.2 | ??- | ??4.87 |
| Comparative example 3 | ??132.6 | ??115.8 | ??88.6 | ??- | ??3.34 |
| Comparative example 4 | ??135.9 | ??118.7 | ??92.5 | ??62.1 | ??3.56 |
| Embodiment 2 | ??150.0 | ??140.3 | ??128.6 | ??98.5 | ??2.05 |
| Embodiment 3 | ??151.2 | ??141.5 | ??129.2 | ??98.3 | ??2.24 |
| Embodiment 4 | ??151.3 | ??140.2 | ??130.0 | ??98.0 | ??1.68 |
| |
??152.0 | ??141.1 | ??130.6 | ??98.6 | ??1.45 |
Claims (4)
1. the hydrothermal synthesis method of the lithium ion battery anode material lithium iron phosphate of an one-dimensional nano structure is characterized by and may further comprise the steps:
The first step, hydrothermal synthesis reaction
Lithium hydroxide is water-soluble, be made into 3.2～4.8mol/L lithium hydroxide solution, add in the autoclave, add phosphoric acid again, behind the air in the dead volume in the inert gas purge still, sealing autoclave, stir down and be heated to 40～50 ℃ from room temperature, open inlet valve and vent valve, at the uniform velocity added source of iron solution again in 9～13 minutes, the proportioning that wherein adds material is mol ratio Li: Fe: P=3.0: 1.0: 1.0～1.15, stir after 10～30 minutes, add pH value conditioning agent, continue to stir, the initial pH value that makes reaction system is 6.5～8.0, and then sealing autoclave, in 140～180 ℃ of reactions 60～480 minutes, this moment, the self-generated pressure corresponding to system was 0.36～1.0Mpa; Wherein, pH value conditioning agent is lithium hydroxide solution or sulfuric acid;
Second step, the filtration of product, washing and drying
After above-mentioned reaction was finished, autoclave was cooled fast to 80 ℃ by cooling water, opens bleeder valve, product was filtered and washed till the sulfate radical-free ion, obtained filter cake and mother liquor, and filter cake obtains canescence LiFePO in 60～120 ℃ of vacuumizes 12 hours
4Powder; Mother liquid evaporation concentrates back reclaim sulfuric acid lithium;
In the 3rd step, carbon coats to be handled
LiFePO with the second step gained
4Powder and glucose are pressed mass ratio LiFePO
4Powder: glucose=100: 10～20 mixings under inert gas shielding, in 600～750 ℃ of roastings 4～6 hours, obtains the LiFePO4 product that carbon coats.
2. as the hydrothermal synthesis method of the lithium ion battery anode material lithium iron phosphate of one-dimensional nano structure in the claim 1, it is characterized by above-mentioned source of iron and be by the ferrous sulfate crystal or produce the solution that the material liquid of ferrous sulfate is mixed with, concentration is for containing ferrous ion 0.8～1.2mol/L.
3. as the hydrothermal synthesis method of the lithium ion battery anode material lithium iron phosphate of one-dimensional nano structure in the claim 1, the concentration that it is characterized by above-mentioned pH value conditioning agent sulfuric acid is mass percent 1～3%.
4. as the hydrothermal synthesis method of the lithium ion battery anode material lithium iron phosphate of one-dimensional nano structure in the claim 1, the concentration that it is characterized by above-mentioned pH value conditioning agent lithium hydroxide is mass percent 3～5%.
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| CN102593428A (en) * | 2011-01-11 | 2012-07-18 | 同济大学 | Method for preparing cathode material of lithium ion battery |
| CN102637853A (en) * | 2011-02-12 | 2012-08-15 | 同济大学 | Preparation method of lithium ion battery anode composite material |
| CN103236532A (en) * | 2013-04-17 | 2013-08-07 | 河北工业大学 | Preparation method for lithium ion battery positive electrode material with 4.5 V voltage platform |
| CN103400984A (en) * | 2013-08-05 | 2013-11-20 | 营口航盛科技实业有限责任公司 | Lattice growth-control hydro-thermal synthesis method for preparing lithium iron phosphate anode material |
| CN104037410A (en) * | 2013-03-08 | 2014-09-10 | 中国科学院大连化学物理研究所 | Preparation method of lithium ion battery positive pole material LiFePO4/C |
| CN104051732A (en) * | 2014-04-10 | 2014-09-17 | 魏宏政 | Method for preparing lithium iron phosphate by clathration technology |
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| CN112028045A (en) * | 2020-09-07 | 2020-12-04 | 厦门厦钨新能源材料股份有限公司 | Conductive lithium iron phosphate and preparation method and application thereof |
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| CN115448283A (en) * | 2022-09-27 | 2022-12-09 | 常州百利锂电智慧工厂有限公司 | Phosphate anode material and production process and application thereof |
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