CN103606676B - A kind of lithium iron phosphate/carbon nanocomposite and preparation method thereof - Google Patents

A kind of lithium iron phosphate/carbon nanocomposite and preparation method thereof Download PDF

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CN103606676B
CN103606676B CN201310560442.7A CN201310560442A CN103606676B CN 103606676 B CN103606676 B CN 103606676B CN 201310560442 A CN201310560442 A CN 201310560442A CN 103606676 B CN103606676 B CN 103606676B
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lithium
iron phosphate
carbon
iron
carbon nanocomposite
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CN103606676A (en
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王张健
席小兵
杨顺毅
黄友元
任建国
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Jiangsu Beiteri Nano Technology Co ltd
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Shenzhen Battery Nanotechnology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The preparation method that the present invention relates to a kind of lithium iron phosphate/carbon nanocomposite, including: preparation nanoscale iron phosphate；By nanoscale iron phosphate and lithium source mix homogeneously, pass into CO2Gas or addition soluble carbonate salt, be deposited reaction, obtain nano-scale lithium iron phosphate precursor；Described LiFePO4 precursor is carried out chemical vapour deposition (CVD) cladding, prepares carbon-coated LiFePO 4 for lithium ion batteries material.Lithium uniform deposition on iron phosphate surface, can be reached the mixing of molecular level uniformity by the method for the invention, and compared with preparing LiFePO4 with direct hydro-thermal method, its response time is short, and energy consumption is little, and technique, pattern are more easy to control；Carry out carbon reduction and cladding finally by CVD, its covered effect is more more uniform than traditional bag carbon technique, well improves the electric conductivity of LiFePO4.

Description

A kind of lithium iron phosphate/carbon nanocomposite and preparation method thereof
Technical field
The present invention relates to field of lithium ion battery anode, in particular it relates to a kind of lithium iron phosphate/carbon nanocomposite, and the method preparing described carbon-coated LiFePO 4 for lithium ion batteries nano composite material that combines with liquid phase method and chemical vapour deposition technique.
Background technology
Along with the consideration of the factors such as the shortage of petroleum-based energy and global climate environment, various countries extremely pay attention to development EV(electric automobile) and HEV(hybrid-electric car).No matter EV or HEV, electrokinetic cell has become as the key technology bottleneck restricting its development.
One of key technology of development lithium-ion-power cell is to prepare to have high performance positive battery material.The positive pole material of lithium cobalt acid commonly used at present, under the occasion of high-power output, repeatedly discharge and recharge may result in analysis oxygen, there is serious potential safety hazard.And as the LiFePO4 of anode material for lithium-ion batteries, compared to cobalt acid lithium material, its high-temperature behavior is excellent, having extended cycle life, security performance is good, lower-cost feature, be it is believed that it is a kind of desirably lithium ion power battery cathode material.
The method of current synthesizing iron lithium phosphate mainly has high temperature solid-state method, liquid phase reactor method, hydro-thermal method etc..
High temperature solid-state method prepares the equipment needed for material and technique is simple, but the LiFePO 4 material chemical property obtained is general, and material uniformity coefficient is relatively low.
Liquid phase reactor method is that the lithium source of solubility, source of iron, phosphorus source are configured to solution according to a certain percentage, making each element is lewis' acid state, a kind of suitable precipitant of reselection, makes metal ion homogeneous precipitation, high-temperature roasting after filtration drying, prepares LiFePO 4 material.The method can reach intermolecular mixing, but obtained LiFePO 4 material morphology controllable is poor.
Hydro-thermal method is the lithium source of solubility, source of iron, phosphorus source solution to be joined together in closed reactor, makes it fully react prepared LiFePO4 by heating pressurization.The LiFePO 4 material good crystallinity for preparing by the method, uniform particle diameter, but hydro-thermal method General reactions time length, energy consumption are big, and cost is high.
Summary of the invention
For the deficiencies in the prior art, an object of the present invention is in that the preparation method providing a kind of lithium iron phosphate/carbon nanocomposite, namely, first prepare nanoscale iron phosphate by liquid phase reactor method, then lithium is deposited on iron phosphate surface, prepare nano-scale lithium iron phosphate precursor, finally deposit one layer of carbon by CVD (chemical vapour deposition technique) on LiFePO4 surface, prepare lithium iron phosphate/carbon nanocomposite.
Specifically, the preparation method of described lithium iron phosphate/carbon nanocomposite comprises the following steps:
(1) nanoscale iron phosphate is prepared；
(2) it is 1.0:(1.0～1.3 by nanoscale iron phosphate and lithium source according to nanoscale iron phosphate and lithium mol ratio) mix homogeneously in a solvent, pass into CO2Gas or addition soluble carbonate salt, regulate pH value of solution to 7～10, be deposited reaction, remove impurity, obtain nano-scale lithium iron phosphate precursor；
(3) described LiFePO4 precursor is warming up to 550～900 DEG C, is continually fed into organic compound gas, carry out chemical vapour deposition (CVD) cladding, prepare carbon-coated LiFePO 4 for lithium ion batteries material.
Preferably, described step (1) including: surfactant, solubility source of iron and soluble sources is added sequentially in solvent and dissolves, and obtains mixed liquor, adopts alkaline matter to regulate pH value of solution to 0.2～6.5, continues reaction, obtain nanoscale iron phosphate slurry；Preferably, described solubility source of iron and soluble sources add in form of an aqueous solutions；Preferably, described surfactant is the combination of a kind in cetyl trimethylammonium bromide, hexadecyltrimethylammonium chloride, sodium lauryl sulphate, dodecylbenzene sodium sulfonate, Polyethylene Glycol, polyethylene glycol oxide, polyacrylamide or carboxymethyl cellulose or at least 2 kinds；Preferably, described solubility source of iron is the combination of a kind in ferric chloride, ferric nitrate, ferrous sulfate, ferric oxalate or iron acetate or at least 2 kinds；Preferably, phosphorus source is the combination of a kind in phosphoric acid, ammonium dihydrogen phosphate, diammonium phosphate or ammonium phosphate or at least 2 kinds；Preferably, the concentration of described solubility source of iron and soluble sources independently be 0.1～5mol/L, more preferably 0.3～4mol/L, it is particularly preferred to is 0.5～3mol/L；Preferably, described solvent is water；Preferably, in described solubility source of iron and soluble sources, ferrum is 1.0:(1.0～2.0 with the mol ratio of phosphorus), more preferably 1.0:(1.0～1.8), it is particularly preferred to for 1.0:(1.0～1.5)；Preferably, the addition speed of described solubility source of iron aqueous solution and soluble sources aqueous solution independently be below 60ml/min, more preferably 1～55ml/min, it is particularly preferred to is 5～50ml/min；Preferably, in described mixed liquor, the concentration of surfactant is 0.05～25g/L, more preferably 0.08～20g/L, it is particularly preferred to be 0.1～15g/L；Preferably, described reaction temperature is 25～100 DEG C, more preferably 25～95 DEG C, it is particularly preferred to be 30～90 DEG C；Preferably, described pH is 0.3～6, it is particularly preferred to be 0.5～5；Preferably, described alkaline matter is the combination of a kind in ammonia, sodium hydroxide or potassium hydroxide or at least 2 kinds；Preferably, described reaction is stirred；Preferably, described speed of agitator is 0.5～45Hz, more preferably 0.8～35Hz, it is particularly preferred to be 1～25Hz；Preferably, the described continuation response time is at least 0.5h, more preferably 0.5～15h, it is particularly preferred to be 0.5～10h.
Preferably, the described lithium source of step (2) is the combination of a kind in Lithium hydrate, lithium nitrate, lithium sulfate, lithium oxalate or lithium acetate or at least 2 kinds.
Preferably, in step (2) described nanoscale iron phosphate and lithium source, the mol ratio of nanoscale iron phosphate and lithium is 1.0:(1.0～1.2), it is particularly preferred to for 1.0:(1.0～1.15).
Preferably, step (2) described solvent is water, it is particularly preferred to for deionized water.
Preferably, the described deposition reaction temperature of step (2) is 30～100 DEG C, more preferably 35～95 DEG C, it is particularly preferred to be 40～90 DEG C.
Preferably, step (2) described deposition reaction is stirred；Preferably, described mixing speed is 30～300r/min, more preferably 40～250r/min, it is particularly preferred to be 50～200r/min.
Preferably, step (2) described CO2The flow velocity of gas is 0.1～10L/min, such as: 0.11L/min, 0.12L/min, 0.15L/min, 0.2L/min, 0.5L/min, 1L/min, 2L/min, 3L/min, 4L/min, 6L/min, 7L/min, 9L/min, 9.5L/min, 9.8L/min or 9.9L/min etc., more preferably 0.1～8L/min, it is particularly preferred to be 0.1～5L/min.
Preferably, step (2) described soluble carbonate salt is the combination of a kind in sodium carbonate, potassium carbonate, ammonium hydrogen carbonate or ammonium carbonate or at least 2 kinds.
The pH of step (2) described deposition reaction can be such as 7.1,7.2,7.5,7.8,8,8.5,8.9,9.1,9.5,9.7 or 9.9 etc., it is preferred to 7～9.5, it is particularly preferred to be 7～9.
Preferably, step (2) the described deposition reaction time is at least 1h, for instance 1.1h, 1.2h, 1.5h, 2h, 3h, 5h, 7h, 9h, 10h, 11h, 13h, 15h or 20h etc., more preferably 1～12h, it is particularly preferred to be 1～8h.
Preferably, step (2) described remove impurity is filtration successively, dries.
Preferably, step (3) described chemical vapour deposition (CVD) is coated in rotary furnace to carry out；Preferably, the rotating speed of described rotary furnace is 0.5～20r/min, more preferably 0.8～15r/min, it is particularly preferred to be 1～10r/min.
Preferably, step (3) described programming rate is 20 DEG C/below min, more preferably 0.5～15 DEG C/min, it is particularly preferred to be 1～10 DEG C/min.
Preferably, the described chemical vapour deposition (CVD) temperature of plate of step (3) is 580～870 DEG C, it is particularly preferred to be 600～850 DEG C.
Preferably, the flow velocity of step (3) described organic compound gas is 0.2～10L/min, more preferably 0.3～8L/min, it is particularly preferred to be 0.5～5L/min.
Preferably, step (3) the described chemical vapour deposition (CVD) cladding time is at least 0.5h, more preferably 0.5～15h, it is particularly preferred to be 0.5～10h.
Preferably, step (3) described organic compound gas is the combination of a kind in methane, ethane, ethylene, acetylene, benzene or toluene or at least 2 kinds.
Preferably, the preparation method of described lithium iron phosphate/carbon nanocomposite comprises the following steps:
(1) solubility source of iron aqueous solution and soluble sources aqueous solution are added sequentially in surfactant solution and dissolve, obtain mixed liquor, at 25～100 DEG C, adopt alkaline matter to regulate pH value of solution to 0.2～6.5, continue to react at least 0.5h, obtain nanoscale iron phosphate slurry；
(2) it is 1.0:(1.0～1.3 by nanoscale iron phosphate slurry and lithium source according to nanoscale iron phosphate and lithium mol ratio) mix homogeneously in a solvent, pass into CO2Gas or addition soluble carbonate salt, at 30～100 DEG C, regulate pH value of solution to 7～10, be deposited reacting at least 1h, remove impurity, obtain nano-scale lithium iron phosphate precursor；
(3) described LiFePO4 precursor is warming up to 550～900 DEG C, is continually fed into organic compound gas with the flow velocity of 0.2～10L/min, carry out chemical vapour deposition (CVD) and be coated with at least 0.5h, prepare carbon-coated LiFePO 4 for lithium ion batteries material.
The two of the purpose of the present invention are in that to provide a kind of lithium iron phosphate/carbon nanocomposite, and described lithium iron phosphate/carbon nanocomposite is prepared by the method for the invention.
Preferably, the particle diameter of described lithium iron phosphate/carbon nanocomposite is 50-300nm.
Preferably, in described lithium iron phosphate/carbon nanocomposite, the content of carbon is 0.05～15.0wt%, more preferably 0.08～12.0wt%, it is particularly preferred to be 0.1～10.0wt%.
The three of the purpose of the present invention are in that to provide a kind of lithium ion battery, and described lithium ion battery comprises lithium iron phosphate/carbon nanocomposite of the present invention.
Compared with prior art, preparing iron phosphate by liquid phase reactor method, during reaction, pattern is more easy to control；By lithium uniform deposition on iron phosphate surface, reaching the mixing of molecular level uniformity, compared with preparing LiFePO4 with direct hydro-thermal method, its response time is short, and energy consumption is little, and technique, pattern are more easy to control；Carry out carbon reduction and cladding finally by CVD, its covered effect is more more uniform than traditional bag carbon technique, well improves the electric conductivity of LiFePO4.Material the method prepared is assembled into simulated battery, and 1C discharge capacity can reach more than 150mAh/g, it was shown that its chemical property is good.
Accompanying drawing explanation
Fig. 1 is the SEM figure of the lithium iron phosphate/carbon nanocomposite adopting the method for the invention to prepare.
Detailed description of the invention
For ease of understanding the present invention, it is as follows that the present invention enumerates embodiment.Those skilled in the art understand the present invention it will be clearly understood that described embodiment is only help, are not construed as the concrete restriction to the present invention.
Embodiment 1
First prepare lauryl sodium sulfate aqueous solution, join in reactor；Then ferric nitrate and phosphate aqueous solution that the concentration prepared is 2.0mol/L are added sequentially in reactor with the flow velocity of 20ml/min, reactor is warming up to 40 DEG C, with 18Hz rotating speed stirring reaction 8h, by adding ammonia adjustment pH value of solution to 3.8 in course of reaction, after filtration drying, prepare nanoscale iron phosphate precursor.
By the ratio mix homogeneously in deionized water of above-mentioned nanoscale iron phosphate, Lithium hydrate 1.0:1.1 in molar ratio；Be subsequently placed in temperature be 70 DEG C, mixing speed be 80r/min closed reactor in, pass into sodium carbonate liquor with 2L/min flow velocity, regulate pH value of solution to 8, be deposited reaction 4h；Then reacted material filtered, dry, obtain nano-scale lithium iron phosphate precursor.
Above-mentioned nano-scale lithium iron phosphate precursor is placed in rotary furnace, rotates with 5r/min, be warming up to 750 DEG C with 3 DEG C/min, continue to pass into toluene 6h with 2L/min flow velocity, carry out vapour deposition cladding, prepare carbon-coated LiFePO 4 for lithium ion batteries nano composite material；The lithium iron phosphate/carbon nanocomposite prepared by the method is assembled into simulated battery, and 0.1C first discharge specific capacity is 166.7mAh/g；1C first discharge specific capacity is 156.3mAh/g, it was shown that this material has good chemical property.
Embodiment 2
First prepare Aqueous Solutions of Polyethylene Glycol, join in reactor；Then ferric chloride and ammonium dihydrogen phosphate aqueous solution that the concentration prepared is 0.1mol/L are added sequentially in reactor with the flow velocity of 60ml/min, reactor is warming up to 60 DEG C, with 45Hz rotating speed stirring reaction 5h, by adding sodium hydrate regulator solution pH to 6.5 in course of reaction, after filtration drying, prepare nanoscale iron phosphate precursor.
By the ratio mix homogeneously in deionized water of above-mentioned nanoscale iron phosphate, lithium acetate 1.0:1.0 in molar ratio；Be subsequently placed in temperature be 30 DEG C, mixing speed be 30r/min closed reactor in, pass into CO continuously with 0.1L/min flow velocity2Gas, regulates pH value of solution to 7, is deposited reaction 12h；Then reacted material filtered, dry, obtain nano-scale lithium iron phosphate precursor.
Above-mentioned nano-scale lithium iron phosphate precursor is placed in rotary furnace, rotates with 3r/min, be warming up to 800 DEG C with 3 DEG C/min, continue to pass into acetylene gas 10h with 1.5L/min flow velocity, carry out vapour deposition cladding, prepare lithium iron phosphate/carbon nanocomposite.Similarly, the lithium iron phosphate/carbon nanocomposite prepared by the method is assembled into simulated battery, and 0.1C first discharge specific capacity can reach 164.5mAh/g；1C first discharge specific capacity is 154.7mAh/g, also has good chemical property.
Embodiment 3
First prepare cetyl trimethylammonium bromide aqueous solution, join in reactor；Then iron acetate and ammonium dibasic phosphate aqueous solution that the concentration prepared is 5mol/L are added sequentially in reactor with the flow velocity of 1ml/min, reactor is warming up to 25 DEG C, with 0.5Hz rotating speed stirring reaction 15h, by adding potassium hydroxide adjustment pH value of solution to 4 in course of reaction, after filtration drying, prepare nanoscale iron phosphate precursor.
By the ratio mix homogeneously in deionized water of above-mentioned nanoscale iron phosphate, lithium nitrate 1.0:1.3 in molar ratio；Be subsequently placed in temperature be 100 DEG C, mixing speed be 80r/min closed reactor in, pass into solution of potassium carbonate continuously with 10L/min flow velocity, regulate pH value of solution to 10, be deposited reaction 1h；Then reacted material filtered, dry, obtain nano-scale lithium iron phosphate precursor.
Above-mentioned nano-scale lithium iron phosphate precursor is placed in rotary furnace, rotates with 10 turns/min, be warming up to 700 DEG C with 20 DEG C/min, continue to pass into methane gas 5h with 4L/min flow velocity, carry out vapour deposition cladding, prepare lithium iron phosphate/carbon nanocomposite.In the same manner as in Example 1, the lithium iron phosphate/carbon nanocomposite prepared by the method is assembled into simulated battery, and 0.1C first discharge specific capacity can reach 163.8mAh/g；1C first discharge specific capacity is 152.4mAh/g, it was shown that its chemical property is good.
Embodiment 4
First prepare hexadecyltrimethylammonium chloride aqueous solution, join in reactor；Then ferrous sulfate and phosphate aqueous solution that the concentration prepared is 1.5mol/L are added sequentially in reactor with the flow velocity of 60ml/min, reactor is warming up to 100 DEG C, with 20Hz rotating speed stirring reaction 0.5h, by adding ammonia adjustment pH value of solution to 0.2 in course of reaction, after filtration drying, prepare nanoscale iron phosphate precursor.
By the ratio mix homogeneously in deionized water of above-mentioned nanoscale iron phosphate, Lithium hydrate 1.0:1.1 in molar ratio；Be subsequently placed in temperature be 45 DEG C, mixing speed be 300r/min closed reactor in, pass into ammonium bicarbonate soln with 2L/min flow velocity, regulate pH value of solution to 8.5, be deposited reaction 4h；Then reacted material filtered, dry, obtain nano-scale lithium iron phosphate precursor.
Above-mentioned nano-scale lithium iron phosphate precursor is placed in rotary furnace, rotates with 0.5r/min, be warming up to 550 DEG C with 1 DEG C/min, continue to pass into ethane 15h with 0.2L/min flow velocity, carry out vapour deposition cladding, prepare carbon-coated LiFePO 4 for lithium ion batteries nano composite material；The lithium iron phosphate/carbon nanocomposite prepared by the method is assembled into simulated battery, and 0.1C first discharge specific capacity is 161.5mAh/g；1C first discharge specific capacity is 151.3mAh/g, it was shown that this material has good chemical property.
Embodiment 5
First prepare sodium dodecyl benzene sulfonate aqueous solution, join in reactor；Then ferric chloride and ammonium dihydrogen phosphate aqueous solution that the concentration prepared is 0.5mol/L are added sequentially in reactor with the flow velocity of 50ml/min, reactor is warming up to 60 DEG C, with 25Hz rotating speed stirring reaction 5h, by adding sodium hydrate regulator solution pH to 3.5 in course of reaction, after filtration drying, prepare nanoscale iron phosphate precursor.
By the ratio mix homogeneously in deionized water of above-mentioned nanoscale iron phosphate, lithium nitrate 1.0:1.2 in molar ratio；Be subsequently placed in temperature be 50 DEG C, mixing speed be 100r/min closed reactor in, pass into CO continuously with 0.8L/min flow velocity2Gas, regulates pH value of solution to 7.5, is deposited reaction 10h；Then reacted material filtered, dry, obtain nano-scale lithium iron phosphate precursor.
Above-mentioned nano-scale lithium iron phosphate precursor is placed in rotary furnace, rotates with 20r/min, be warming up to 900 DEG C with 5 DEG C/min, continue to pass into ethylene gas 0.5h with 10L/min flow velocity, carry out vapour deposition cladding, prepare lithium iron phosphate/carbon nanocomposite.In like manner, the lithium iron phosphate/carbon nanocomposite prepared by the method is assembled into simulated battery, and 0.1C first discharge specific capacity can reach 161.8mAh/g；1C first discharge specific capacity is 150.6mAh/g, also has good chemical property.
Comparative example 1
The ratio of ferrous sulfate, phosphoric acid, Lithium hydrate 1.0:1.0:1.1 in molar ratio is mixed in deionized water, adds 0.8mol% ascorbic acid, mix homogeneously；Be subsequently placed in temperature be 100 DEG C, pressure is 5MPa, mixing speed be 500r/min closed reactor in, carry out hydrothermal synthesis reaction 4h；By adding ammonia adjustment pH value of solution in course of reaction, reacted material is filtered, dries, obtain LiFePO4 precursor.Then the LiFePO 4 material obtained is mixed with glucose ball milling, more under nitrogen protection 750 DEG C calcining 12h, obtain carbon-coated LiFePO 4 for lithium ion batteries material.In the same manner as in Example 1, the carbon-coated LiFePO 4 for lithium ion batteries material prepared by the method is assembled into simulated battery, and 0.1C first discharge specific capacity only has 154.9mAh/g；1C first discharge specific capacity is 133.7mAh/g, compared with embodiment 1-5, its discharge capacity, high rate performance are substantially far short of what is expected, also indicate that simultaneously and use lithium iron phosphate/carbon nanocomposite prepared by the present invention to have its obvious advantage: capacity is high, high rate performance is excellent.
Applicant states, the present invention illustrates detailed process equipment and the technological process of the present invention by above-described embodiment, but the invention is not limited in above-mentioned detailed process equipment and technological process, namely do not mean that the present invention has to rely on above-mentioned detailed process equipment and technological process could be implemented.The equivalence of each raw material of product of the present invention, it will be clearly understood that any improvement in the present invention, is replaced and the interpolation of auxiliary element, concrete way choice etc. by person of ordinary skill in the field, all falls within protection scope of the present invention and open scope.

Claims (76)

1. a preparation method for lithium iron phosphate/carbon nanocomposite, comprises the following steps:
(1) nanoscale iron phosphate is prepared, dissolve comprising: surfactant, solubility source of iron and soluble sources are added sequentially in solvent, obtain mixed liquor, adopt alkaline matter to regulate pH value of solution to 0.2～6.5, continue reaction, obtain nanoscale iron phosphate slurry；
(2) it is 1.0:(1.0～1.3 by nanoscale iron phosphate and lithium source according to nanoscale iron phosphate and lithium mol ratio) mix homogeneously in a solvent, pass into CO2Gas or addition soluble carbonate salt, regulate pH value of solution to 7～10, be deposited reaction, remove impurity, obtain nano-scale lithium iron phosphate precursor；
(3) described LiFePO4 precursor is warming up to 550～900 DEG C, is continually fed into organic compound gas, carry out chemical vapour deposition (CVD) cladding, prepare carbon-coated LiFePO 4 for lithium ion batteries material.
2. the method for claim 1, it is characterised in that the described solubility source of iron of step (1) and soluble sources add in form of an aqueous solutions.
3. the method for claim 1, it is characterized in that, step (1) described surfactant is the combination of a kind in cetyl trimethylammonium bromide, hexadecyltrimethylammonium chloride, sodium lauryl sulphate, dodecylbenzene sodium sulfonate, Polyethylene Glycol, polyethylene glycol oxide, polyacrylamide or carboxymethyl cellulose or at least 2 kinds.
4. the method for claim 1, it is characterised in that the described solubility source of iron of step (1) is the combination of a kind in ferric chloride, ferric nitrate, ferrous sulfate, ferric oxalate or iron acetate or at least 2 kinds.
5. the method for claim 1, it is characterised in that step (1) described soluble sources is the combination of a kind in phosphoric acid, ammonium dihydrogen phosphate, diammonium phosphate or ammonium phosphate or at least 2 kinds.
6. the method for claim 1, it is characterised in that the concentration of the described solubility source of iron of step (1) and soluble sources independently be 0.1～5mol/L.
7. the method for claim 1, it is characterised in that the concentration of the described solubility source of iron of step (1) and soluble sources independently be 0.3～4mol/L.
8. the method for claim 1, it is characterised in that the concentration of the described solubility source of iron of step (1) and soluble sources independently be 0.5～3mol/L.
9. the method for claim 1, it is characterised in that step (1) described solvent is water.
10. the method for claim 1, it is characterised in that in the described solubility source of iron of step (1) and soluble sources, ferrum is 1.0:(1.0～2.0 with the mol ratio of phosphorus).
11. the method for claim 1, it is characterised in that in the described solubility source of iron of step (1) and soluble sources, ferrum is 1.0:(1.0～1.8 with the mol ratio of phosphorus).
12. the method for claim 1, it is characterised in that in the described solubility source of iron of step (1) and soluble sources, ferrum is 1.0:(1.0～1.5 with the mol ratio of phosphorus).
13. the method for claim 1, it is characterised in that the addition speed of the described solubility source of iron aqueous solution of step (1) and soluble sources aqueous solution independently be below 60ml/min.
14. the method for claim 1, it is characterised in that the addition speed of the described solubility source of iron aqueous solution of step (1) and soluble sources aqueous solution independently be 1～55ml/min.
15. the method for claim 1, it is characterised in that the addition speed of the described solubility source of iron aqueous solution of step (1) and soluble sources aqueous solution independently be 5～50ml/min.
16. the method for claim 1, it is characterised in that in step (1) described mixed liquor, the concentration of surfactant is 0.05～25g/L.
17. the method for claim 1, it is characterised in that in step (1) described mixed liquor, the concentration of surfactant is 0.08～20g/L.
18. the method for claim 1, it is characterised in that in step (1) described mixed liquor, the concentration of surfactant is 0.1～15g/L.
19. the method for claim 1, it is characterised in that the described continuation reaction temperature of step (1) is 25～100 DEG C.
20. the method for claim 1, it is characterised in that the described continuation reaction temperature of step (1) is 25～95 DEG C.
21. the method for claim 1, it is characterised in that the described continuation reaction temperature of step (1) is 30～90 DEG C.
22. the method for claim 1, it is characterised in that step (1) described pH is 0.3～6.
23. the method for claim 1, it is characterised in that step (1) described pH is 0.5～5.
24. the method for claim 1, it is characterised in that step (1) described alkaline matter is the combination of a kind in ammonia, sodium hydroxide or potassium hydroxide or at least 2 kinds.
25. the method for claim 1, it is characterised in that the described continuation reaction of step (1) is stirred.
26. method as claimed in claim 25, it is characterised in that described speed of agitator is 0.5～45Hz.
27. method as claimed in claim 25, it is characterised in that described speed of agitator is 0.8～35Hz.
28. method as claimed in claim 25, it is characterised in that described speed of agitator is 1～25Hz.
29. the method for claim 1, it is characterised in that step (1) the described continuation response time is at least 0.5h.
30. the method for claim 1, it is characterised in that step (1) the described continuation response time is 0.5～15h.
31. the method for claim 1, it is characterised in that step (1) the described continuation response time is 0.5～10h.
32. the method for claim 1, it is characterised in that the described lithium source of step (2) is the combination of a kind in Lithium hydrate, lithium nitrate, lithium sulfate, lithium oxalate or lithium acetate or at least 2 kinds.
33. the method for claim 1, it is characterised in that in step (2) described nanoscale iron phosphate and lithium source, the mol ratio of nanoscale iron phosphate and lithium is 1.0:(1.0～1.2).
34. the method for claim 1, it is characterised in that in step (2) described nanoscale iron phosphate and lithium source, the mol ratio of nanoscale iron phosphate and lithium is 1.0:(1.0～1.15).
35. the method for claim 1, it is characterised in that step (2) described solvent is water.
36. the method for claim 1, it is characterised in that step (2) described solvent is deionized water.
37. the method for claim 1, it is characterised in that the described deposition reaction temperature of step (2) is 30～100 DEG C.
38. the method for claim 1, it is characterised in that the described deposition reaction temperature of step (2) is 35～95 DEG C.
39. the method for claim 1, it is characterised in that the described deposition reaction temperature of step (2) is 40～90 DEG C.
40. the method for claim 1, it is characterised in that step (2) described deposition reaction is stirred.
41. method as claimed in claim 40, it is characterised in that described mixing speed is 30～300r/min.
42. method as claimed in claim 40, it is characterised in that described mixing speed is 40～250r/min.
43. method as claimed in claim 40, it is characterised in that described mixing speed is 50～200r/min.
44. the method for claim 1, it is characterised in that step (2) described CO2The flow velocity of gas is 0.1～10L/min.
45. the method for claim 1, it is characterised in that step (2) described CO2The flow velocity of gas is 0.1～8L/min.
46. the method for claim 1, it is characterised in that step (2) described CO2The flow velocity of gas is 0.1～5L/min.
47. the method for claim 1, it is characterised in that step (2) described soluble carbonate salt is the combination of a kind in sodium carbonate, potassium carbonate, ammonium hydrogen carbonate or ammonium carbonate or at least 2 kinds.
48. the method for claim 1, it is characterised in that the pH of step (2) described deposition reaction is 7～9.5.
49. the method for claim 1, it is characterised in that the pH of step (2) described deposition reaction is 7～9.
50. the method for claim 1, it is characterised in that step (2) the described deposition reaction time is at least 1h.
51. the method for claim 1, it is characterised in that step (2) the described deposition reaction time is 1～12h.
52. the method for claim 1, it is characterised in that step (2) the described deposition reaction time is 1～8h.
53. the method for claim 1, it is characterised in that step (2) described remove impurity is filtration successively, dries.
54. the method for claim 1, it is characterised in that step (3) described chemical vapour deposition (CVD) is coated in rotary furnace to carry out.
55. method as claimed in claim 54, it is characterised in that the rotating speed of described rotary furnace is 0.5～20r/min.
56. method as claimed in claim 54, it is characterised in that the rotating speed of described rotary furnace is 0.8～15r/min.
57. method as claimed in claim 54, it is characterised in that the rotating speed of described rotary furnace is 1～10r/min.
58. the method for claim 1, it is characterised in that step (3) described programming rate is 20 DEG C/below min.
59. the method for claim 1, it is characterised in that step (3) described programming rate is 0.5～15 DEG C/min.
60. the method for claim 1, it is characterised in that step (3) described programming rate is 1～10 DEG C/min.
61. the method for claim 1, it is characterised in that the described chemical vapour deposition (CVD) temperature of plate of step (3) is 580～870 DEG C.
62. the method for claim 1, it is characterised in that the described chemical vapour deposition (CVD) temperature of plate of step (3) is 600～850 DEG C.
63. the method for claim 1, it is characterised in that the flow velocity of step (3) described organic compound gas is 0.2～10L/min.
64. the method for claim 1, it is characterised in that the flow velocity of step (3) described organic compound gas is 0.3～8L/min.
65. the method for claim 1, it is characterised in that the flow velocity of step (3) described organic compound gas is 0.5～5L/min.
66. the method for claim 1, it is characterised in that step (3) the described chemical vapour deposition (CVD) cladding time is at least 0.5h.
67. the method for claim 1, it is characterised in that step (3) the described chemical vapour deposition (CVD) cladding time is 0.5～15h.
68. the method for claim 1, it is characterised in that step (3) the described chemical vapour deposition (CVD) cladding time is 0.5～10h.
69. the method for claim 1, it is characterised in that step (3) described organic compound gas is the combination of a kind in methane, ethane, ethylene, acetylene, benzene or toluene or at least 2 kinds.
70. the method for claim 1, it is characterised in that said method comprising the steps of:
(1) solubility source of iron aqueous solution and soluble sources aqueous solution are added sequentially in surfactant solution and dissolve, obtain mixed liquor, at 25～100 DEG C, adopt alkaline matter to regulate pH value of solution to 0.2～6.5, continue to react at least 0.5h, obtain nanoscale iron phosphate slurry；
(2) it is 1.0:(1.0～1.3 by nanoscale iron phosphate slurry and lithium source according to nanoscale iron phosphate and lithium mol ratio) mix homogeneously in a solvent, pass into CO2Gas or addition soluble carbonate salt, at 30～100 DEG C, regulate pH value of solution to 7～10, be deposited reacting at least 1h, remove impurity, obtain nano-scale lithium iron phosphate precursor；
(3) described LiFePO4 precursor is warming up to 550～900 DEG C, is continually fed into organic compound gas with the flow velocity of 0.2～10L/min, carry out chemical vapour deposition (CVD) and be coated with at least 0.5h, prepare carbon-coated LiFePO 4 for lithium ion batteries material.
71. a lithium iron phosphate/carbon nanocomposite, it is characterised in that prepared by described lithium iron phosphate/carbon nanocomposite method described in any one of claim 1-70.
72. the lithium iron phosphate/carbon nanocomposite as described in claim 71, it is characterised in that the particle diameter of described lithium iron phosphate/carbon nanocomposite is 50-300nm.
73. the lithium iron phosphate/carbon nanocomposite as described in claim 71, it is characterised in that in described lithium iron phosphate/carbon nanocomposite, the content of carbon is 0.05～15.0wt%.
74. the lithium iron phosphate/carbon nanocomposite as described in claim 71, it is characterised in that in described lithium iron phosphate/carbon nanocomposite, the content of carbon is 0.08～12.0wt%.
75. the lithium iron phosphate/carbon nanocomposite as described in claim 71, it is characterised in that in described lithium iron phosphate/carbon nanocomposite, the content of carbon is 0.1～10.0wt%.
76. a lithium ion battery, it is characterised in that described lithium ion battery comprises lithium iron phosphate/carbon nanocomposite described in claim 71.
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CN105047952A (en) * 2015-06-02 2015-11-11 哈尔滨工业大学 Dendritic nanowire catalyst carrier with metal oxide/carbon core-sheath structure and preparation method of supported catalyst
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CN106229505B (en) * 2016-08-17 2019-10-25 深圳市贝特瑞纳米科技有限公司 A kind of high-density spherical nano lithium iron phosphate material and preparation method thereof and lithium ion battery comprising it
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CN107069005A (en) * 2017-04-19 2017-08-18 龙能科技如皋市有限公司 A kind of preparation method of double-carbon-source coated LiFePO 4 material
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