CN100502103C - Core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material and method for preparing the same - Google Patents
Core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material and method for preparing the same Download PDFInfo
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- CN100502103C CN100502103C CNB2007100500290A CN200710050029A CN100502103C CN 100502103 C CN100502103 C CN 100502103C CN B2007100500290 A CNB2007100500290 A CN B2007100500290A CN 200710050029 A CN200710050029 A CN 200710050029A CN 100502103 C CN100502103 C CN 100502103C
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Abstract
The invention discloses a nucleocapsid type nanometer level carbon packing LiFePO4 composite anode material and preparation method thereof, the steps of which include that: 1) Fe<3+> compound, lithium resource compound, phosphorus resource compound and reducer are taken according to moore ratio; 2) Fe<3+> compound is mixed into solution, added with the reducer to reduce Fe<3+> to Fe<2+> and added with lithium resource compound and phosphorus resource compound to acquire a precursor solution; the modification starch with the quality occupying 10 percent to 15 percent of total quality of the base material is added into the precursor solution, heated and stirred so that the modification starch is pasted, heated and stirred more so as to evaporate the solvent of the solution to get the jasmine precursor powder; 3) the precursor powder is arranged in a vacuum welding furnace under the pressure of 5 Pa to 15 Pa vacuum degree, pre-decomposed for 2 hours to 6 hours in the temperature conditions of 300 DEG C to 400 DEG C and welded for 10 hours to 20 hours after the temperature rises to 600 DEG C to 800 DEG C, and the nucleocapsid type nanometer level carbon packing LiFePO4 composite anode material is acquired after cooling.
Description
(1) technical field:
The present invention relates to the anode material for lithium-ion batteries technical field, relating in particular to the modified starch is the core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material that carbon source is made; The invention still further relates to this preparation methods.
(2) background technology:
Lithium ion battery is as the green high-capacity battery of a new generation, have that operating voltage height, energy density height, good cycle, self discharge are little, numerous advantages such as memory-less effect, operating temperature range are wide, be widely used in mobile phone, notebook computer, UPS, video camera, various portable power tool, electronic instrument, weaponry etc., in electric motor car, also have a good application prospect, be considered to 21st century has the weight meaning to national economy and people's lives new high-tech product.Positive electrode is the important component part of lithium ion battery, numerous as LiCoO
2, LiNiO
2, LiMn
2O
4, LiCo
xNi
yMn
zO, LiFePO
4In the positive electrode Deng lithium battery, have the LiFePO4 of olivine structural because have that raw material sources are abundant, cost is low, environmental friendliness, nonhygroscopic, security performance is high, specific capacity higher (theoretical capacity is 170mAh/g), have about 3.4V stably that advantages such as discharge voltage plateau, thermal stability and cycle performance excellence are considered to the most promising positive electrode.But there is following significant disadvantages in LiFePO4: Fe during (1) is synthetic
2+Easily be oxidized to Fe
3+, be difficult to obtain single-phase LiFePO4; (2) lithium ion spreads difficulty in LiFePO4, causes the utilance of active material low; (3) conductivity of LiFePO4 itself is also very low, causes its high-rate discharge ability poor.These shortcomings have hindered the practical application of LiFePO 4 material.Existing corrective measure mainly contains: (1) adopts inert atmosphere protection Fe
2+(2) LiFePO4 of synthetic small particle diameter or carry out the diffusivity that doped metal ion improves lithium ion; (3) add conductive agent and improve conductivity.
The method of synthesizing iron lithium phosphate mainly contains high-temperature solid phase reaction method, sol-gel process, hydro thermal method and chemistry and inserts lithium method etc. at present.
High temperature solid-state method is with ferrous salt, mix with phosphate and lithium salts, under inert atmosphere protection respectively at 300 ℃ and 500-600 ℃ of following prepared in reaction LiFePO4, as (Optimized LiFePO such as Atsuo Yamada
4For Lithium Battery Cathodes[J] .Journal of TheElectrochemical Society, 2001,148 (3): be that raw material has synthesized LiFePO4 A224-A229) with ferric acetate, ammonium hydrogen phosphate and lithium carbonate, and with the influence to product property of XRD, BET surface area measuring technique, Mossbauer spectrum and grain size analysis technical research synthesis technique.Result of study shows that the product that adopts medium sintering temperature (500 ℃＜T＜600 ℃) and homogeneous phase presoma to obtain at room temperature can reach 95% theoretical capacity.Because temperature is bigger greater than the particle diameter of 600 ℃ of products, specific area is less; Temperature is less than 500 ℃ of Fe that have amorphous or nanometer state
3+Phase; The advantage of high temperature solid-state method is that technology simply, easily realizes industrialization, but reactant is difficult for mixing, and synthetic product particle diameter major part is a micron order, and skewness, often contains impurity, and pattern is irregular, and chemical property is also relatively poor.
Shoufeng Yang etc. (Hydrothermal synthesis of lithium iron phosphatecathodes[J] .Electrochemistry Communications 2001 3:505-508) are raw material with divalent iron salt, lithium hydroxide and the phosphoric acid of solubility, with (120 ℃ of hydro thermal methods, 5 hours) synthesized single-phase LiFePO4, average grain diameter is 3 microns.(LiFePO such as S.Frange
4Synthesis routes forenhanced electrochemical performance[J] .Electrochemical and Solid-StateLetters, 2002,5 (10): A231-A223) with LiFe (PO
4)
25H
2O and Li
3PO
4Be raw material, with Hydrothermal Preparation LiFePO4.Compare with high temperature solid-state method, hydro thermal method can directly obtain LiFePO4, does not need inert atmosphere protection, crystal formation and particle diameter that can control material, but hydro thermal method needs high-temperature high-pressure apparatus, is difficult for suitability for industrialized production.
Sol-gel process can make Fe
2+, Li
+And PO
4 3+Realize the mixing of molecule rank, also realize easily mixing, the gained material property is more satisfactory, as application number is 03102665.6, the name be called＜＜a kind of wet chemical method for preparing LiFePO4 Chinese invention patent, disclose a kind of presoma that directly obtains with precipitation reaction and prepared lithium ion battery anode material lithium iron phosphate (LiFePO
4) wet chemical method; It is that Li source compound, Fe source compound, P source compound are made into the solution that concentration is 0.1-3.0mol/L; The solution or the suspension that will contain Li source compound, Fe source compound, P source compound, doping element compound or conductive agent and precipitation reagent again mix, in 5-120 ℃ airtight stirred reactor, reacted 0.5-24 hour, and obtained the nanometer presoma after filtering, wash, drying; Again the nanometer presoma of gained is put into high temperature furnace, in non-air or non-oxidizing atmosphere, with the heating rate heating of 1-30 ℃/min, at 500-800 ℃ of constant temperature calcining 5-48 hour, and, make the lithium iron phosphate nano powder with the rate of temperature fall cooling of 1-20 ℃/min or with the stove cooling; The method has been controlled LiFePO effectively
4Chemical composition, phase constituent and particle diameter, improved its uniformity and electric conductivity, improved its chemical property, but its synthesis cycle is longer, preparation technology is comparatively complicated.
It is the ferric phosphate for preparing nanoscale with the precipitation method that chemistry is inserted the lithium method, adopts LiI to carry out the slotting lithium of chemistry then and makes armorphous nano-grade lithium iron phosphate, can make the good olivine-type LiFePO4 of chemical property through handling then.As (synthetic route for preparing LiFePO such as Pier Paolo
4With enhanced electrochemical performance[J] .Journal of the ElectrochemicalSociety, 2002,149 (7): A886-A890), use earlier hydrogen peroxide oxidation Fe
2+The compound LiFePO4 with lithium iodide reduction preparation LiFePO4, after heat treatment obtains the LiFePO4 crystal again.(A novel concept for The synthesis of an improved LiFePO such as F.Croce
4Lithium batteries cathode[J] .Electrochemical and Solid-State Letters, 2002,5 (3): A47-A50) reduce Fe with ascorbic acid
3+Compound LiFePO4.In this class synthetic method, technical process is comparatively cumbersome, and owing to used reagent such as the more expensive hydrogen peroxide of price, lithium iodide, thereby increased production cost of products.
In the above-mentioned existing synthetic method, the LiFePO4 particle diameter that high temperature solid-state method synthesizes is bigger, and chemical property is not ideal enough, though hydro thermal method can be controlled particle diameter, the difficulty of suitability for industrialized production is bigger; It is more satisfactory that sol-gel process and chemistry are inserted the synthetic LiFePO 4 material performance of lithium method, but its preparation technology is complicated, and the production cycle is longer, and production cost is also higher.
(3) summary of the invention.
It is carbon source, the good core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material of chemical property with the modified starch that the present invention discloses a kind of, and this preparation methods.
The present invention is a kind of core-shell type nano-scale carbon-covered iron lithium phosphate compound anode preparation methods, and its step is as follows:
1) takes by weighing Fe in molar ratio
3+Compound, Li source compound, P source compound and reducing agent;
Described Fe
3+Compound: Li source compound: P source compound: the mol ratio of reducing agent can be 2:1.95-2.05:2:1-2; Fe wherein
3+Compound can be ferric nitrate, or ferric acetate; Li source compound can be lithium hydroxide, or lithium carbonate, or lithium nitrate; P source compound can be phosphoric acid; Reducing agent can be ascorbic acid or other can be reduced into ferric ion the reducing agent of ferrous ion;
2) with Fe
3+The compound wiring solution-forming makes Fe to wherein adding reducing agent
3+Be reduced into Fe
2+, add Li source compound and P source compound then, obtain LiFePO
4Precursor solution; In precursor solution, add the modified starch that quality accounts for above-mentioned basic material gross mass 10-15%, add thermal agitation 80 ℃ of-110 ℃ of temperature ranges then, make the modified starch gelatinization, continue to add thermal agitation, solvent evaporation in solution is complete, obtains flaxen precursor powder;
When described precursor solution is prepared, earlier with Fe
3+Compound is made into the aqueous solution of 0.3-0.8mol/L, slowly to wherein adding ascorbic acid, the ferric ion in the solution is reduced into ferrous ion in the whipping process, adds phosphoric acid and Li source compound again, and stirring and dissolving obtains clarifying the light green color precursor solution; Because the electric conductivity of LiFePO4 itself is relatively poor, in order to improve its conductivity, adopt the modified starch that in precursor solution, adds the 10-15% that accounts for above-mentioned basic material gross mass as carbon source among the present invention, in heat treatment process, the carbon original position that the modified starch cracking generates is wrapped in the LiFePO4 particle surface, reaches the purpose that improves the LiFePO4 electric conductivity; Described modified starch is to utilize physics, chemistry or enzymatic treatment, changes the natural character of starch, increase its some functional or introduce new characteristic, make it more be adapted to certain requirement of using; Modified starch commonly used among the present invention can be oxidized starch, or oxidative crosslinked starch, or carboxyl grafting starch, or CMS; After adding modified starch, add thermal agitation, make starch gelatinization, modified starch after the gelatinization is because imbibition, the hydrogen bond rupture between its molecule, and being dispersed in becomes hydrophilic colloidal solution in the water, because above-mentioned modified starch all has active group carboxyl and hydroxyl, carboxyl and hydroxyl can with metal ion generation complexing, can realize that so not only the molecule rank mixes, and can guide LiFePO
4The growth of crystal makes starch granules be wrapped in the LiFePO4 particle surface equably, and in pre-building-up process, the space steric effect of macromolecular chain and the iris action of macromolecule network have hindered the reunion of particle; Secondly, in heat treatment process, the carbon original position that the starch cracking generates is wrapped in the LiFePO4 particle surface, not only hindered the reunion of particle in the high temperature building-up process, reach the purpose of refinement particle, and between the LiFePO4 particle surface, formed the good carbon network of conductivity, strengthened its electric conductivity; The temperature of described heating preferably is controlled at 80-110 ℃, and the moisture content evaporate to dryness in solution obtains flaxen precursor powder;
3) precursor powder is placed vacuum sintering furnace, in vacuum degree is under the pressure of 5-15Pa, under 300-400 ℃ of temperature conditions predecomposition 2-6 hour earlier, be warming up to again under the 600-800 ℃ of temperature conditions and calcined 10-20 hour, obtain the core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material after the cooling; Wherein, precursor powder places that the speed with 2-5 ℃/min is warming up to 300-400 ℃ behind the vacuum sintering furnace, is warming up to 600-800 ℃ with equal speed again.
The present invention also comprises the iron phosphate compound anode material of lithium that is formed by method for preparing.
Core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material of the present invention, its synthesis technique is simple, and raw material sources are extensive, and wherein ferric nitrate is as source of iron, and compares as source of iron with ferrous iron, greatly reduces production cost; Each raw material mixes under solution state, makes Fe
2+, Li
+And PO
4 3+Realize the molecule level mixture; As carbon source, also is polymerization inhibitor simultaneously with modified starch, and the carbon original position that its cracking at high temperature generates is wrapped in the LiFePO4 particle surface, has hindered LiFePO4 particle growing up in the high-temperature calcination process, reaches the purpose of refinement particle; Meanwhile, the carbon that the modified starch cracking generates has also played the effect of reducing agent, in the high-temperature calcination process, has suppressed the oxidation of ferrous ion, has reduced the difficulty of control reaction condition, has improved the purity and the performance of product; In addition, modified starch has also played the effect of dispersant, and the space steric effect of its macromolecular chain and the iris action of macromolecule network suppress the reunion of particle in the pre-building-up process of material; Presoma is calcined in vacuum atmosphere, the core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material of obtain that nanoscale and particle size range are narrow, pattern is regular, conduct electricity very well, chemical property is good.
(4) description of drawings:
Fig. 1 is for making the XRD figure spectrum of material by embodiment 1 technology;
Fig. 2 is the TEM collection of illustrative plates of single material making by embodiment 1 technology;
Fig. 3 is for making the charging and discharging curve figure of material under 0.1C by embodiment 1 with Comparative Examples 1 technology respectively;
Fig. 4 is for making the charging and discharging curve figure of material under 5C by embodiment 1 with Comparative Examples 1 technology respectively;
Fig. 5 is for making the curve chart of the different multiplying and the specific discharge capacity relation of material respectively by embodiment 1 and Comparative Examples 1 technology;
Fig. 6 is for making the 1C cycle performance curve chart of material respectively by embodiment 1 and Comparative Examples 1 technology.
(5) embodiment:
Embodiment 1
Take by weighing 72.72g Fe (NO
3)
39H
2O places the beaker of 1000ml, adds 400ml distilled water, and stirring and dissolving adds the 15.85g ascorbic acid again, and stirring and dissolving obtains light green solution, adds 20.76gH more successively
3PO
4And 7.56gLiOHH
2O obtains containing the Li of equimolar amounts
+, Fe
2+And PO
4 3+Precursor solution, add the 16.44g oxidized starch again, 90 ℃ add thermal agitation, oxidized starch gelatinization, Li
+, Fe
2+And PO
4 3+Coexist as in the macromolecular network of oxidized starch, evenly disperse, obtain the starch base LiFePO of homogeneous
4Precursor solution continues to add thermal agitation, until the moisture evaporate to dryness, obtains flaxen precursor powder.Precursor powder is put into crucible, place vacuum sintering furnace, under 10Pa vacuum degree, heating rate with 2 ℃/min heats up, and locates to be incubated 4 hours at 320 ℃, and same speed is warming up to 700 ℃, be incubated 12 hours again, sample cools to room temperature with the furnace, obtains core-shell type nano carbon and coats composite positive pole, and the phosphorus content that records product with carbon sulphur instrument is 7.07%.
Take by weighing the LiFePO of 0.4g embodiment 1 preparation
4/ C powder, adding 0.05g acetylene black and 0.05g are dissolved in the polyvinylidene fluoride binding agent of N-N ' dimethyl pyrrolidone, be applied to after mixing and make positive plate on the aluminium foil, in the argon gas atmosphere dry glove box, with metal lithium sheet is to electrode, with Celgard2300 is barrier film, and 1mol/L LiPF6/EC:DMC (1:1) is an electrolyte, is assembled into 2025 button cell.
Comparative Examples 1
Take by weighing 72.72g Fe (NO
3)
39H
2O places the beaker of 1000ml, adds 400ml distilled water, and stirring and dissolving adds the 15.85g ascorbic acid again, and stirring and dissolving obtains light green solution, adds 20.76gH more successively
3PO
4And 7.56gLiOHH
2O obtains containing the Li of equimolar amounts
+, Fe
2+And PO
4 3+Precursor solution, add 16.44g native starch (tapioca) again, 90 ℃ add thermal agitation, starch gelatinization continues to add thermal agitation, until the moisture evaporate to dryness, obtains flaxen precursor powder.Precursor powder is put into crucible, place vacuum sintering furnace, under 10Pa vacuum degree, heating rate with 2 ℃/min heats up, and locates predecomposition 4 hours at 320 ℃, and same speed is warming up to 700 ℃, calcined 12 hours, sample cools to room temperature with the furnace, obtains LiFePO
4/ C composite material.
Take by weighing the LiFePO of 0.4g Comparative Examples 1 preparation
4/ C powder, adding 0.05g acetylene black and 0.05g are dissolved in the polyvinylidene fluoride binding agent of N-N ' dimethyl pyrrolidone, be applied to after mixing and make positive plate on the aluminium foil, in the argon gas atmosphere dry glove box, with metal lithium sheet is to electrode, with Celgard2300 is barrier film, and 1mol/L LiPF6/EC:DMC (1:1) is an electrolyte, is assembled into 2025 button cell.
(25 ℃) at normal temperatures carry out the constant current charge-discharge test to battery in the 2.5V-4.2V voltage range.Fig. 3 is respectively by the 0.1C multiplying power (17mAg of embodiment 1 with the sample of Comparative Examples 1 preparation
-1) charging and discharging curve, wherein, a, b are the charging and discharging curve of embodiment 1; C, d is the charging and discharging curve of Comparative Examples 1, as known in the figure, the discharge voltage plateau of the sample of embodiment 1 preparation is about 3.39V, specific discharge capacity is up to 166mAh/g, near theoretical specific capacity, the discharge voltage plateau of the sample of Comparative Examples 1 preparation is about 3.34V, and specific discharge capacity is 151mAh/g.Fig. 4 is by the 5C multiplying power (850mA.g of embodiment 1 with the sample of Comparative Examples 1 preparation
-1) charging and discharging curve, wherein, a, b are the charging and discharging curve of embodiment 1; C, d are the charging and discharging curve of Comparative Examples 1, as known in the figure, the discharge voltage plateau of embodiment 1 preparation sample is about 3.3V, and specific discharge capacity is 101mAh/g, and Comparative Examples 1 preparation sample does not have tangible discharge voltage plateau, specific discharge capacity is less, is 78mAh/g.Fig. 5 is embodiment 1 and the different discharge-rates of Comparative Examples 1 preparation sample and the curve of specific discharge capacity, and wherein, a is the different multiplying of embodiment 1 sample and the curve of specific discharge capacity; B is the different multiplying of Comparative Examples 1 sample and the curve of specific discharge capacity, as can be seen from Figure, the specific discharge capacity of sample under each multiplying power of embodiment 1 preparation is higher than the specific discharge capacity of the sample of Comparative Examples 1 preparation, along with the increase of discharge-rate, the degree of the specific discharge capacity decay of embodiment 1 preparation sample is less than the decay of the specific discharge capacity of Comparative Examples 1 preparation sample.Fig. 6 is embodiment 1 and the cycle performance curve of Comparative Examples 1 preparation sample with the 1C multiplying power discharging, and wherein, a is the 1C cycle performance curve of embodiment 1 sample; B is the 1C cycle performance of Comparative Examples 1 sample.As can be seen from Figure, the cycle performance of the sample of embodiment 1 preparation is better than the cycle performance of Comparative Examples 1 preparation sample, after embodiment 1 preparation sample circulates through 50 times, attenuation rate is very little, only be 0.7%, after Comparative Examples 1 preparation sample circulated through 50 times, attenuation rate was 7.6%.Can find out that from Fig. 3-6 the chemical property excellence of the sample of embodiment 1 preparation is in the chemical property of the sample of Comparative Examples 1 preparation.
Embodiment 2
Take by weighing 72.72g Fe (NO
3)
39H
2O places the beaker of 1000ml, adds 400ml distilled water, and stirring and dissolving adds the 15.85g ascorbic acid again, and stirring and dissolving obtains light green solution, adds 20.76gH more successively
3PO
4And 13.30gLi
2CO
3, obtain containing the Li of equimolar amounts
+, Fe
2+And PO
4 3+Precursor solution, add the 16.44g oxidative crosslinked starch again, 110 ℃ add thermal agitation, starch gelatinization, Li
+, Fe
2+And PO
4 3+Coexist as in the macromolecular network of starch, evenly disperse, obtain the starch base LiFePO of homogeneous
4Precursor solution continues to add thermal agitation, until the moisture evaporate to dryness, obtains flaxen precursor powder; Precursor powder is put into crucible, place vacuum sintering furnace, under 10Pa vacuum degree, heating rate with 2 ℃/min heats up, located predecomposition 4 hours at 300 ℃, same speed is warming up to 700 ℃, calcines 12 hours, sample cools to room temperature with the furnace, obtains core-shell type nano-scale carbon and coats LiFePO
4Composite positive pole.
Take by weighing 24.24g Fe (NO
3)
39H
2O places the beaker of 500ml, adds 200ml distilled water, and stirring and dissolving adds the 5.28g ascorbic acid again, and stirring and dissolving obtains light green solution, adds 6.92gH more successively
3PO
4And 2.52gLiOH.H
2O adds the 5.48g CMS again after the stirring and dissolving, 80 ℃ add thermal agitation, starch gelatinization, Li
+, Fe
2+And PO
4 3+Coexist as in the macromolecular network of starch, evenly disperse, obtain the starch base LiFePO of homogeneous
4Precursor solution continues to add thermal agitation, until the moisture evaporate to dryness, obtains flaxen precursor powder.Precursor powder is put into crucible, place vacuum sintering furnace, under 10Pa vacuum degree, heating rate with 2 ℃/min heats up, located predecomposition 4 hours at 320 ℃, same speed is warming up to 650 ℃, calcines 15 hours, sample cools to room temperature with the furnace, obtains core-shell type nano-scale carbon and coats LiFePO
4Composite positive pole.
Embodiment 4
Take by weighing 24.24g Fe (NO
3)
39H
2O places the beaker of 500ml, adds 200ml distilled water, and stirring and dissolving adds the 5.28g ascorbic acid again, and stirring and dissolving obtains light green solution, adds 6.92gH again
3PO
4And 2.52gLiOHH
2O adds 5.48g carboxyl grafting starch again after the stirring and dissolving, 100 ℃ add thermal agitation, starch gelatinization, Li
+, Fe
2+And PO
4 3+Coexist as in the macromolecular network of starch, evenly disperse, obtain the starch base LiFePO of homogeneous
4Precursor solution continues to add thermal agitation, until the moisture evaporate to dryness, obtains flaxen precursor powder; Precursor powder is put into crucible, place vacuum sintering furnace, under 10Pa vacuum degree, heating rate with 3 ℃/min heats up, and locates predecomposition 3 hours at 350 ℃, and same speed is warming up to 750 ℃, be incubated 10 hours again, be cooled to room temperature, obtain core-shell type nano-scale carbon and coat LiFePO
4Composite positive pole.
Claims (4)
1, a kind of core-shell type nano-scale carbon-covered iron lithium phosphate compound anode preparation methods, its step is as follows:
1) takes by weighing Fe in molar ratio
3+Compound, Li source compound, P source compound and ascorbic acid;
2) with Fe
3+The compound wiring solution-forming makes Fe to wherein adding ascorbic acid
3+Be reduced into Fe
2+, add lithium source and P source compound then, get precursor solution; Add the modified starch that quality accounts for above-mentioned basic material gross mass 10-15% in precursor solution, heating is also stirred, and makes the modified starch gelatinization, continues to add thermal agitation, makes the solvent evaporation in the solution, obtains faint yellow precursor powder;
3) precursor powder is placed vacuum sintering furnace, in vacuum degree is under the pressure of 5-15Pa, under 300-400 ℃ of temperature conditions predecomposition 2-6 hour earlier, be warming up to again under the 600-800 ℃ of temperature conditions and calcined 10-20 hour, obtain the core-shell type nano-scale carbon-covered iron lithium phosphate compound anode material after the cooling;
In step 1), described Fe
3+Compound: Li source compound: P source compound: the mol ratio=2:1.95-2.05:2:1-2 of ascorbic acid; Wherein,
Described Fe
3+Compound is a ferric nitrate, or ferric acetate;
Described Li source compound is a lithium hydroxide, or lithium nitrate;
Described P source compound is a phosphoric acid.
2, core-shell type nano-scale carbon-covered iron lithium phosphate compound anode preparation methods according to claim 1 is characterized in that: step 2) in, described modified starch is an oxidized starch, or oxidative crosslinked starch, or carboxyl grafting starch, or CMS.
3, core-shell type nano-scale carbon-covered iron lithium phosphate compound anode preparation methods according to claim 1, it is characterized in that: step 2) in, be heated to 80-110 ℃ after adding modified starch, in heating, stir, make the modified starch gelatinization, after the gelatinization, continue to add thermal agitation, the solvent in solution evaporates fully.
4, core-shell type nano-scale carbon-covered iron lithium phosphate compound anode preparation methods according to claim 1 is characterized in that: in the step 3), vacuum sintering furnace heats up with the speed of 2-5 ℃/min.
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| US9209461B2 (en) | 2009-06-24 | 2015-12-08 | Basf Se | Process for the preparation of LiFePO4-carbon composites |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US9209461B2 (en) | 2009-06-24 | 2015-12-08 | Basf Se | Process for the preparation of LiFePO4-carbon composites |
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