CN102244243B - Preparation method of lithium iron phosphate composite material with iron oxide as raw material - Google Patents
Preparation method of lithium iron phosphate composite material with iron oxide as raw material Download PDFInfo
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- CN102244243B CN102244243B CN201110149051.7A CN201110149051A CN102244243B CN 102244243 B CN102244243 B CN 102244243B CN 201110149051 A CN201110149051 A CN 201110149051A CN 102244243 B CN102244243 B CN 102244243B
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Abstract
The invention relates to a preparation method of lithium iron phosphate composite material with iron oxide as a raw material. Through adding a function additive, after a high temperature heat treatment, a lithium iron phosphate composite cathode material coated with a high conductivity substance on a surface is obtained, effective conductivity of the material is raised, and electrochemical performance of the material is greatly improved. Compared with other preparation methods of lithium iron phosphate, the method in the invention has the following advantages: cheap iron oxide is selected as a raw material, and cost of the raw material is greatly reduced; there is no release of toxic or harmful by-products in a reaction process, and the production method is environmental friendly; process route is simple and reliable, flow is short, technological parameter is easy to control, material batch consistency is good, and the method is suitable for industrial production.
Description
Technical field:
The invention belongs to the electrochemical power source technical field of material, particularly relate to and a kind ofly take cheap iron oxide and prepare the method for lithium ferrous phosphate composite material as raw material.
Background technology:
Along with the development of information technology, the miniaturization of electronic equipment, and the continuous appearance of novel electron instrument and equipment, make small-sized discrete movable power source demand maintained sustained and rapid growth, and battery industry is had higher requirement.Lithium rechargeable battery with a series of advantages such as volume is little, energy density is high, long service life has just received the concern of countries in the world since it comes out always.With traditional rechargeable batteries such as Ni/Cd, Ni/MH, compare, it has 3 times, operating voltage, the Ni/Cd battery that is equivalent to 3 times of Ni/Cd, Ni/MH battery, the energy density that the Ni/MH battery is 1.5 times, less self-discharge rate, the advantage such as the noxious substance such as leaded cadmium and memory-less effect not.Therefore it is widely used in the fields such as Portable movable instrument, digital product, artificial satellite, Aero-Space, and also has boundless prospect in the fields such as electric bicycle and automobile.
In lithium ion battery, positive electrode occupies very important status, is also one of emphasis of current lithium ion battery development.The positive electrode that lithium ion battery is used at present is mainly lithium transition-metal oxide, comprises the LiCoO of six side's layer structures
2, LiNiO
2and LiNi
1-x-yco
xmn
yo
2(0≤x, y≤1, x+y≤1), the LiMn of spinel structure
2o
4and polyanion class positive electrode is as the LiFePO of olivine structural
4(LiFePO 4).LiCoO wherein
2realized commercialization, but its selling at exorbitant prices, toxicity is larger, and the resource-constrained of cobalt; LiNiO
2synthetic more difficult; LiMn
2o
4lower, the cycle life of capacity especially the cycle life under high temperature is poor.
The LiFePO of olivine shape
4utmost point material as lithium ion battery is compared following advantage with other materials: (1) has the theoretical capacity of 170mAh/g; (2) there is the discharge platform of 3.4V (to Li/Li
+current potential), the range of application of organic electrolyte is enlarged; (3) good reversibility of electrode reaction; (4) thermal stability and chemical stability are high, use safety; (5) cost of material is low; (6) nontoxic.
Above-mentioned advantage receives much concern LiFePO 4, and many scholars conduct in-depth research it.Yet, at LiFePO
4there are some problems in the synthetic and practical process of positive electrode.On the one hand the electronic conductivity of this material is low by (approximately 10
-9s/cm) and the lithium ion diffusion coefficient little (about 1.8 * 10
-16-2.2 * 10
-14cm
2/ S); A difficult problem is how large-scale industrialization is synthetic on the other hand.The preparation method of ferrousphosphate lithium material mainly contains solid phase method, liquid phase method, microwave method and solid-liquid Xiang Fa etc. at present.In recent years, although multiple preparation method has been proposed,, the preparation method who has reported is not because raw materials used for ferrous iron makes preparation cost very high, is not suitable for exactly heavy industrialization because synthesis path is too complicated.
That by vast researcher, adopted at present is high temperature solid-state method (A.Yamada et al.US Pat.5910382; CN1401559A) be by ferrous salt; with phosphate or lithium hydroxide, mix, under inert atmosphere protection through 300-350 ℃ and 500-800 ℃ roasting synthesizing lithium ferrous phosphate stage by stage.The advantage of high temperature method is that technique is simple, easily realizes industrialization, but the common mixing of reactant is inhomogeneous, and the product particle is easily grown up, and discharges ammonia in course of reaction, is difficult to obtain the pure phase LiFePO 4.
Liquid phase method comprises sol-gel process, coprecipitation, hydrothermal synthesis method etc.
Sol-gel process (Chinese patent CN1410349A, [J] Electrochemical and Solid-State Letters, 5 (3) A47-A50) is by compatible Li
+, Fe
2+or Fe
3+, PO
4 3-the aqueous solution select suitable organic sequestering agent, make it to add thermosetting colloidal sol and gel, then by sintering, obtain LiFePO 4.Sol-gal process can make iron, phosphate radical and lithium realize that molecular level mixes, and also easily realizes doping, and the resulting materials performance is also more satisfactory, but technique is comparatively complicated, is difficult for expanding production.
Coprecipitation (WO02/083555A2, CN1431147A) under certain condition, lithium hydroxide is joined in the solution that contains ferrous ion and phosphoric acid, from solution, co-precipitation goes out ferrous phosphate and lithium phosphate precursor, and precursor is made to LiFePO 4 650-800 ℃ of roasting.Chinese patent CN1431147A adopts closed container to prepare precursor, has removed protective atmosphere from, but technique is still comparatively complicated, is difficult to meet requirement prepared by large-scale industrialization.
Summary of the invention:
The object of the invention is, providing a kind of take iron oxide and prepares the method for lithium ferrous phosphate composite material as raw material, it is raw material that the method is chosen iron oxide, and the functional additive added, can obtain surface and be coated with the LiFePO 4 composite positive pole that high electricity is led material after high-temperature heat treatment, method of the present invention is compared with the method that other prepare LiFePO 4, its advantage shows as: the raw-material cost of decrease, the raw material of selecting in course of reaction without poisonous, harmful side product discharges, it is a kind of production method of very environmental protection, process route is simple and reliable, flow process is shorter, technological parameter is easier to control, the batches of materials high conformity, easily realize industrial-scale production.Overcome current existing methods deficiency.
Of the present inventionly take iron oxide and prepare the method for lithium ferrous phosphate composite material as raw material, choosing iron oxide is raw material, and the functional additive added, can obtain surface and be coated with the LiFePO 4 composite positive pole that high electricity is led material after high-temperature heat treatment, concrete operations follow these steps to carry out:
A, by lithium dihydrogen phosphate: iron oxide: functional additive oxalic acid, EDTA, citric acid, ascorbic acid, polyacrylic acid, formic acid, be 1 along the mol ratio of butyric acid or malonic acid: 0.4-0.6: 0.1-3 takes respectively, at first add decentralized medium absolute ethyl alcohol, deionized water or acetone in container, then after adding lithium dihydrogen phosphate, functional additive stirring and dissolving, add again croci, stir evaporation 3-8h at 30 ℃-90 ℃ of temperature, mixing speed is 100-800r/min, obtain colloidal mixture;
Or by lithium dihydrogen phosphate: iron oxide: functional additive oxalic acid, EDTA, citric acid, ascorbic acid, polyacrylic acid, formic acid, be 1 along the mol ratio of butyric acid or malonic acid: it is even that 0.4-0.6: 0.1-3 joins in mortar ground and mixed, add decentralized medium absolute ethyl alcohol, deionized water or acetone, continue to be ground to and obtain colloidal mixture;
Or by lithium dihydrogen phosphate: iron oxide: functional additive oxalic acid, EDTA, citric acid, ascorbic acid, polyacrylic acid, formic acid, be 1 along the mol ratio of butyric acid or malonic acid: 0.4-0.6: 0.1-3 and decentralized medium absolute ethyl alcohol, deionized water or acetone mixing and ball milling, wherein, the mass ratio of decentralized medium, raw material, mill ball is 1: 0.5-2: 3-6, rotating speed 100-800r/min, Ball-milling Time 5-20h, obtain mixed powder;
B, mixed powder that step a is obtained, at 60-120 ℃ of lower oven for drying or vacuum drying, obtain mixed powder;
C, mixed grinding, pressure forming, typed pressure is 10-40MPa, and heat treatment under Buchholz protection or vacuum condition, air velocity is 0.1-1.0L/min, rises to 300-400 ℃ with 1-20 ℃/min heating rate, constant temperature 1-10h;
D, after it is naturally cooling porphyrize briquetting again, typed pressure is 10-40MPa, heat treatment under protective gas; air velocity is 0.1-1.0L/min; be warming up to 500-900 ℃ with the 1-10 ℃/min rate of heat addition, roasting 2-24h, can obtain the olivine-type lithium ferrous phosphate composite material.
Step a decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source.
The addition manner of carbon source is directly with step a Raw, to mix to add or add after step b is dried.
Carbon source is sucrose, glucose, polyethylene glycol or acetylene black.
The mist of the mist that in step c, protective gas is nitrogen, argon gas, argon gas and hydrogen or nitrogen and hydrogen, wherein in mist, hydrogen volume content is 1-4%.
The vacuum degree of vacuum condition described in step c is 133.322 * 10
-3-133.322 * 10
-5pa.
Of the present inventionly take iron oxide as raw material prepares the method for lithium ferrous phosphate composite material, there is following distinguishing feature:
The employing iron oxide is raw material: iron oxide has the advantages such as source is wide, price is low, thus preparation cost that can the decrease material.
Adopt lithium dihydrogen phosphate that lithium and phosphorus required in course of reaction is provided: in having avoided conventional high-temperature solid phase method or common carbothermic reduction reaction solid phase method in the high temperature sintering stage, to use ammonium dihydrogen phosphate or ammonium hydrogen phosphate for raw material produces the ammonia of environmental pollution, meet the requirement of Green Chemistry.
Employing will be added the method for functional additive in mixture (precursor).This additive at high temperature can provide the strong reducing property environment, thereby can obtain the lithium ferrous phosphate composite material that surface is coated with the high conductivity material, has improved its effective conductivity, and then increases substantially the performance of material.
In preparation process, raw material is mixed in liquid phase, and finally form colloidal mixture, reduced the composition segregation in the mixture dry run, improved the mixing uniformity between raw material.
Material composition and product formula are easily controlled, and synthetic LiFePO 4 anode material for compound lithium ion battery has good electrochemistry and physical property.
The advantage of maximum of the present invention is by add functional additive in preparation process, can obtain surface and be coated with the LiFePO 4 composite positive pole that high electricity is led material after high-temperature heat treatment, and simple, the applicable scale volume production of process route.Synthetic material is assembled into experimental cell, under its 0.1C multiplying power, specific discharge capacity can reach 169.3mAh/g, under the 1C multiplying power, specific discharge capacity can reach 141.6mAh/g, also can obtain the specific discharge capacity of 124.5mAh/g under the 5C high magnification, show that prepared material list reveals good electrochemical properties by adding suitable functional additive.
The accompanying drawing explanation
The XRD collection of illustrative plates that Fig. 1 is the prepared LiFePO 4 of the present invention
The scanning electron microscope (SEM) photograph that Fig. 2 is the prepared LiFePO 4 of the present invention
Fig. 3 is the prepared LiFePO 4 of the present invention during as anode material for lithium-ion batteries, the charging and discharging curve figure of battery under different multiplying
Fig. 4 is the prepared LiFePO 4 of the present invention during as anode material for lithium-ion batteries, the high rate performance figure of battery, wherein
for carbon cladded ferrous lithium phosphate
Embodiment
A, taking lithium dihydrogen phosphate, iron oxide, functional additive oxalic acid that mol ratio is 1: 0.5: 1.5, to join in mortar ground and mixed even, add the decentralized medium absolute ethyl alcohol, continue to be ground to and obtain colloidal mixture, the decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source;
B, colloidal mixture that step a is obtained, in 60 ℃ of oven dry of oven temperature, obtain mixed powder, then add the carbon source sucrose of 5wt%;
C, mixed grinding, pressure forming, typed pressure is 10MPa, and heat treatment under the gas nitrogen protection, air velocity is 0.1L/min, rises to 300 ℃ with 1 ℃/min heating rate, constant temperature 1h;
D, after it is naturally cooling porphyrize briquetting again, typed pressure is 10MPa, heat treatment under protective gas nitrogen; air velocity is 0.2L/min; be warming up to 650 ℃ with the 1 ℃/min rate of heat addition, roasting 12h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 2
A. lithium dihydrogen phosphate, iron oxide, functional additive EDTA that to take mol ratio be 1: 0.4: 0.1, at first in container, add in the decentralized medium deionized water, then after adding lithium dihydrogen phosphate, functional additive formic acid stirring and dissolving, add again croci, stir evaporation 5h under temperature 70 C, mixing speed is 200r/min, obtains colloidal mixture, and wherein the decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source;
B, then by colloidal mixture in 80 ℃ of oven dry of oven temperature, obtain mixed powder, then add the glucose of 12wt%;
C, mixing porphyrize, and pressure forming, typed pressure is 15MPa, and heat treatment under the gas argon shield, air velocity is 0.1L/min, rises to 350 ℃ with 5 ℃/min heating rate, constant temperature 3h;
D, after it is naturally cooling porphyrize briquetting again, typed pressure is 15MPa, heat treatment under the protective gas argon gas; air velocity is 0.4L/min; be warming up to 750 ℃ with the 5 ℃/min rate of heat addition, roasting 5h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 3
A, take the mol ratio lithium dihydrogen phosphate of 1: 0.5: 2, iron oxide, citric acid and decentralized medium deionized water mixing and ball milling, wherein decentralized medium, raw material and mill ball mass ratio are 1: 1: 4, rotating speed 350r/min, and Ball-milling Time 8h, obtain mixed powder;
B, mixed powder that step a is obtained, in 80 ℃ of oven dry of oven temperature, obtain mixed powder, then add the carbon source polyethylene glycol of 14wt%;
C, mixed grinding, pressure forming, typed pressure is 20MPa, and heat treatment under the gas nitrogen protection, air velocity is 0.5L/min, rises to 320 ℃ with 8 ℃/min heating rate, constant temperature 4h;
D, after it is naturally cooling porphyrize briquetting again, typed pressure is 20MPa, heat treatment under protective gas nitrogen; air velocity is 0.5L/min; be warming up to 700 ℃ with the 5 ℃/min rate of heat addition, roasting 10h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 4 (carbon source directly adds in raw material)
A, take lithium dihydrogen phosphate, iron oxide, functional additive ascorbic acid that mol ratio is 1: 0.6: 1.5, the carbon source sucrose of lithium dihydrogen phosphate, functional additive ascorbic acid and 10wt% is added in the decentralized medium deionized water, after stirring and dissolving, then add croci; Stir evaporation 7h under temperature 70 C, mixing speed is 100r/min, obtains colloidal mixture, and wherein the decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source;
B, then by this colloidal mixture vacuum drying, obtain mixed powder;
C, mixing porphyrize, and pressure forming, typed pressure is 25MPa, and heat treatment (in mist, hydrogen volume content is 2%) under argon gas and hydrogen gas mixture protection, air velocity is 0.6L/min, rises to 360 ℃ with 8 ℃/min heating rate, constant temperature 6h;
D, after it is naturally cooling porphyrize briquetting again; typed pressure is 25MPa; heat treatment (in mist, hydrogen volume content is 2%) under argon gas and hydrogen gas mixture protection; air velocity is 0.5L/min; be warming up to 700 ℃ with the 8 ℃/min rate of heat addition; roasting 15h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 5 (carbon source directly adds in raw material)
It is even that a, the acetylene black that takes lithium dihydrogen phosphate, iron oxide, functional additive polyacrylic acid and 20wt% that mol ratio is 1: 0.55: 3 join in mortar ground and mixed, the mixed solution that adds again decentralized medium absolute ethyl alcohol and deionized water, continue to be ground to and obtain colloidal mixture, wherein the decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source;
B, this colloidal mixture is placed in to 120 ℃ of dryings of baking oven temperature, time 12h, obtain mixed powder;
C, mixing porphyrize, and pressure forming, typed pressure is 40MPa, and heat treatment (in mist, hydrogen volume content is 60%) under nitrogen and hydrogen gas mixture protection, air velocity is 10L/min, rises to 400 ℃ with 20 ℃/min heating rate, constant temperature 10h;
D, after it is naturally cooling porphyrize briquetting again; typed pressure is 40MPa; heat treatment (in mist, hydrogen volume content is 60%) under nitrogen and hydrogen gas mixture protection; air velocity is 0.6L/min; be warming up to 900 ℃ with the 10 ℃/min rate of heat addition; roasting 2h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 6
A, taking lithium dihydrogen phosphate, iron oxide, functional additive formic acid that mol ratio is 1: 0.45: 2, to join in mortar ground and mixed even, add the decentralized medium deionized water, continue to be ground to and obtain colloidal mixture, wherein the decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source;
B, this colloidal mixture is placed in to baking oven in 85 ℃ of dryings of temperature, time 10h, obtain mixed powder, then add the sucrose of 12wt%;
C, mixing porphyrize, and pressure forming, typed pressure is 35MPa, and heat treatment (in mist, hydrogen volume content is 4%) under nitrogen and hydrogen gas mixture protection, air velocity is 0.8L/min, rises to 380 ℃ with 15 ℃/min heating rate, constant temperature 8h;
D, after it is naturally cooling porphyrize briquetting again; typed pressure is 35MPa; heat treatment (in mist, hydrogen volume content is 4%) under nitrogen and hydrogen gas mixture protection; air velocity is 0.5L/min; be warming up to 800 ℃ with the 8 ℃/min rate of heat addition; roasting 10h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 7
A, taking lithium dihydrogen phosphate, iron oxide, functional additive malonic acid that mol ratio is 1: 0.55: 1.5, to join in mortar ground and mixed even, the mixed solution that adds decentralized medium absolute ethyl alcohol and deionized water, continue to be ground to and obtain colloidal mixture, wherein the decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source;
B, this colloidal mixture is placed in to baking oven, 110 ℃ of dryings of temperature, time 12h, obtain mixed powder, then add the glucose of 18wt%;
C, mix porphyrize, and pressure forming, typed pressure is 25MPa, and heat treatment under vacuum condition (vacuum degree is 133.322 * 10
-3-133.322 * 10
-5pa), rise to 360 ℃ with 18 ℃/min heating rate, constant temperature 7h;
D, after it is naturally cooling porphyrize briquetting again, typed pressure is 25MPa, (vacuum degree is 133.322 * 10 in heat treatment under vacuum condition
-3-133.322 * 10
-5pa), with the 6 ℃/min rate of heat addition, be warming up to 750 ℃, roasting 12h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 8
A, to take mol ratio be 1: 0.5-: 1.2 lithium dihydrogen phosphate, iron oxide, functional additive are along butyric acid, add decentralized medium deionized water mixing and ball milling, wherein decentralized medium, raw material and mill ball mass ratio are 1: 1: 4, rotating speed 350r/min, Ball-milling Time 8h, obtain mixed powder;
B, the ball milling mixed powder is placed in to baking oven, in 85 ℃ of oven dry of temperature, then in add the sucrose of 16wt%;
C, mix porphyrize, and pressure forming, typed pressure is 15MPa, and heat treatment under vacuum condition (vacuum degree is 133.322 * 10
-3-133.322 * 10
-5pa), rise to 340 ℃ with 8 ℃/min heating rate, constant temperature 3h;
D, after it is naturally cooling porphyrize briquetting again, typed pressure is 15MPa, (vacuum degree is 133.322 * 10 in heat treatment under vacuum condition
-3-133.322 * 10
-5pa), with the 7 ℃/min rate of heat addition, be warming up to 650 ℃, roasting 10h, can obtain the olivine-type lithium ferrous phosphate composite material.
Embodiment 9 (carbon source directly adds in raw material)
A, take lithium dihydrogen phosphate, iron oxide, functional additive oxalic acid that mol ratio is 1: 0.5: 1.5, the carbon source sucrose of lithium dihydrogen phosphate, functional additive oxalic acid and 20wt% is added in the decentralized medium deionized water, after stirring and dissolving, then add croci; Stir evaporation 7h under temperature 70 C, mixing speed is 100r/min, obtains colloidal mixture, and wherein the decentralized medium quality is 1: 1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source;
B, then by this colloidal mixture vacuum drying, obtain mixed powder;
C, mixing porphyrize; and pressure forming; typed pressure is 25MPa; heat treatment (in mist, hydrogen volume content is 2%) under nitrogen and hydrogen gas mixture protection; air velocity is 0.5L/min; be warming up to 700 ℃ with the 8 ℃/min rate of heat addition, roasting 15h, can obtain the olivine-type lithium ferrous phosphate composite material.
Claims (4)
1. take iron oxide and prepare the method for lithium ferrous phosphate composite material as raw material for one kind, it is characterized in that choosing iron oxide is raw material, and interpolation functional additive, can obtain surface and be coated with the LiFePO 4 composite positive pole that high electricity is led material after high-temperature heat treatment, concrete operations follow these steps to carry out:
A, by lithium dihydrogen phosphate: iron oxide: functional additive oxalic acid, EDTA, citric acid, ascorbic acid, polyacrylic acid, formic acid, be that 1:0.4-0.6:0.1-3 takes respectively along the mol ratio of butyric acid or malonic acid, at first add decentralized medium absolute ethyl alcohol, deionized water or acetone in container, then after adding lithium dihydrogen phosphate, functional additive stirring and dissolving, add again croci, stir evaporation 3-8h at 30 ℃-90 ℃ of temperature, mixing speed is 100-800r/min, obtains colloidal mixture;
Or by lithium dihydrogen phosphate: iron oxide: functional additive oxalic acid, EDTA, citric acid, ascorbic acid, polyacrylic acid, formic acid, to be along the mol ratio of butyric acid or malonic acid that 1:0.4-0.6:0.1-3 joins in mortar ground and mixed even, add decentralized medium absolute ethyl alcohol, deionized water or acetone, continue to be ground to and obtain colloidal mixture;
Or by lithium dihydrogen phosphate: iron oxide: functional additive oxalic acid, EDTA, citric acid, ascorbic acid, polyacrylic acid, formic acid, be 1:0.4-0.6:0.1-3 and decentralized medium absolute ethyl alcohol, deionized water or acetone mixing and ball milling along the mol ratio of butyric acid or malonic acid, wherein the mass ratio of decentralized medium, raw material and mill ball is 1:0.5-2:3-6, rotating speed 100-800r/min, Ball-milling Time 5-20h, obtain mixture;
B, mixed powder that step a is obtained, at 60-120 ℃ of lower oven for drying or vacuum drying, obtain mixed powder;
C, mixed grinding; pressure forming; typed pressure is 10-40MPa; and heat treatment under Buchholz protection or vacuum condition, air velocity is 0.1-1.0L/min, with 1-20 ℃/min heating rate, rises to 300-400 ℃; constant temperature 1-10h; the mist that wherein protective gas is nitrogen, argon gas, argon gas and hydrogen or the mist of nitrogen and hydrogen, wherein in mist, hydrogen volume content is 1-4%, the vacuum degree of vacuum condition is 133.322 * 10
-3-133.322 * 10
-5pa;
D, after it is naturally cooling porphyrize briquetting or directly by step b gained powder porphyrize briquetting again; typed pressure is 10-40MPa; heat treatment under protective gas; air velocity is 0.1-1.0L/min; be warming up to 500-900 ℃ with the 1-10 ℃/min rate of heat addition; roasting 2-24h, can obtain the olivine-type lithium ferrous phosphate composite material.
2. method according to claim 1, is characterized in that adding carbon source in step a, and in step a, the decentralized medium quality is 1:1 with the ratio of the gross mass of raw material lithium dihydrogen phosphate, iron oxide and carbon source.
3. method according to claim 2, is characterized in that the addition manner of carbon source is for directly to mix interpolation with step a Raw.
4. method according to claim 3, is characterized in that added carbon source is sucrose, glucose, polyethylene glycol or acetylene black.
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| CN101630731A (en) * | 2009-07-27 | 2010-01-20 | 深圳市德方纳米科技有限公司 | Nanoscale lithium iron phosphate used as cathode material of lithium ion battery and preparation method thereof |
| CN101798075A (en) * | 2009-04-02 | 2010-08-11 | 宜昌欧赛科技有限公司 | Method for preparing positive electrode material lithium iron phosphate of lithium ion battery |
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| CN101798075A (en) * | 2009-04-02 | 2010-08-11 | 宜昌欧赛科技有限公司 | Method for preparing positive electrode material lithium iron phosphate of lithium ion battery |
| CN101630731A (en) * | 2009-07-27 | 2010-01-20 | 深圳市德方纳米科技有限公司 | Nanoscale lithium iron phosphate used as cathode material of lithium ion battery and preparation method thereof |
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