CN111129471A - Preparation method of lithium iron phosphate/graphene composite material - Google Patents
Preparation method of lithium iron phosphate/graphene composite material Download PDFInfo
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- CN111129471A CN111129471A CN201911418697.3A CN201911418697A CN111129471A CN 111129471 A CN111129471 A CN 111129471A CN 201911418697 A CN201911418697 A CN 201911418697A CN 111129471 A CN111129471 A CN 111129471A
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- iron phosphate
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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
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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
- 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
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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
- H01M4/58—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
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
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- 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
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- Y02E60/10—Energy storage using batteries
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Abstract
The invention discloses a preparation method of a lithium iron phosphate/graphene composite material, which comprises the following steps of (1) uniformly mixing high-boiling-point alcohol (ethylene glycol or glycerol), ethanol, iron phosphate, lithium carbonate and graphene; (2) filtering to obtain a solid mixture; (3) and (3) carrying out heat treatment on the solid mixture in an inert atmosphere, and cooling to room temperature to obtain the lithium iron phosphate/graphene composite material. According to the invention, high boiling point alcohol (ethylene glycol or glycerol) has a dispersion-assisting function of a surfactant, so that uniform mixing of iron phosphate, lithium carbonate and graphene is obtained, and meanwhile, the high boiling point alcohol (ethylene glycol or glycerol) adsorbed in the solid mixture can be polymerized, dehydrated and carbonized in a heat treatment process and serves as a reducing agent to reduce ferric iron, so that lithium iron phosphate is obtained. The graphene uniformly distributed in the lithium iron phosphate can greatly improve the electronic conductivity of the material, so that the charge and discharge performance of the lithium iron phosphate material is effectively improved.
Description
The technical field is as follows:
the invention designs a preparation method of lithium iron phosphate/graphene, and the prepared lithium iron phosphate/graphene material can be used as a lithium ion battery anode material, and belongs to the technical field of new energy materials.
Background
The lithium iron phosphate is a lithium ion battery anode material widely used for electric automobiles, and has the advantages of high safety, long cycle life, strong overshoot and overdischarge resistance, environmental protection, low price and the like. However, the lithium iron phosphate has a structural defect, the electronic conductivity is low and is 10 < -9 > to 10 < -10 > S/cm, and the application of the lithium iron phosphate in a lithium ion battery is greatly limited. In application, the main approaches to solve the problem are as follows: reducing the particle size of the lithium iron phosphate particles, modifying the surface with a chemically inert conductive material (such as a metal or carbon-based material), and performing lattice phase doping.
The carbon material has the advantage of strong electron conductivity, and is also a main material for improving the electron conductivity of the lithium iron phosphate in industry. In order to achieve the purpose of improving the electron conductivity of the lithium iron phosphate material by carbon coating, in research and industrialization processes, a common material is prepared by mixing an organic substance, such as sucrose, into a lithium iron phosphate raw material, converting the organic substance into carbon along with the preparation process of the lithium iron phosphate, and coating the carbon with the lithium iron phosphate to form the lithium iron phosphate composite material. However, carbon obtained in this way is substantially amorphous carbon, and has limited ability in improving electron conductivity, so that it is difficult to fundamentally change the electron conductivity of lithium iron phosphate, which greatly affects the electrochemical performance of lithium iron phosphate.
Disclosure of Invention
The invention aims to solve the defects in the technology, and the graphene is introduced in the preparation process to realize the composite material of lithium iron phosphate and graphene which are uniformly mixed, so that a novel method for preparing the lithium iron phosphate/graphene composite material is provided. The preparation process is simple and convenient, and the obtained lithium iron phosphate/graphene composite material has excellent charge and discharge performance. In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a Si/graphene composite flexible electrode of a lithium ion battery comprises the following steps:
1) measuring a certain volume of high-boiling-point organic alcohol and ethanol, and weighing a certain amount of iron phosphate, lithium carbonate and graphene according to the metering ratio in the molecular formula of the lithium iron phosphate, and carrying out solid-phase ball milling;
2) filtering the dispersion liquid obtained in the step 1), and separating a solid mixture from liquid;
3) and (3) placing the solid mixture obtained in the step 2) into an atmosphere furnace, and carrying out heat treatment for a period of time under the protection of a non-oxidizing atmosphere to obtain the lithium iron phosphate/graphene composite material.
As a preferable technical means: in the step 1), the high-boiling-point alcohol is ethylene glycol or glycerol.
As a preferable technical means: in the step 1), the volume ratio of the high-boiling-point alcohol to the ethanol is 1: 1-3.
As a preferable technical means: in the step 1), the addition amount of the lithium carbonate is 105% of the theoretical amount.
As a preferable technical means: in the step 1), the volume of the mixed alcohol is 5-10 times of the volume of the raw material powder.
As a preferable technical means: in the step 1), the addition amount of the graphene is 2-5% of the mass of the lithium iron phosphate.
As a preferable technical means: in the step 1), the ball milling time is 2-5 hours.
As a preferable technical means: in the step 3), the gas used in the inert atmosphere is nitrogen or argon;
the heating rate in the heat treatment process is 1-5 ℃/min. In the step 3), the heat treatment temperature is 500-800 ℃; the heat treatment time is 2-5 h.
According to the method, firstly, high-boiling-point alcohol, ethanol, iron phosphate, lithium carbonate and graphene are subjected to ball milling dispersion, the iron phosphate, iron carbonate and graphene are uniformly dispersed by utilizing the good affinity of ethylene glycol or glycerol, a solid mixture precursor is obtained after filter pressing, and then the iron phosphate/graphene composite material is prepared through heat treatment.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) in the technology, the high-boiling-point alcohol not only can be used as a surfactant and has the function of uniformly mixing auxiliary raw materials, but also has good affinity with iron phosphate, lithium carbonate and graphene in the structure, and is adhered to the surfaces of the high-boiling-point alcohol and the graphene. The ethylene glycol adhered to the surface of the iron phosphate can be dehydrated and carbonized in the subsequent heat treatment process, plays the role of a reducing agent to reduce ferric iron and promote the formation of the lithium iron phosphate material, and the process is simple, low in cost and suitable for industrial production;
(2) the ethylene glycol and the glycerol have good affinity with the graphene, which greatly contributes to uniform dispersion of the graphite in the raw material, so that the graphene in the lithium iron phosphate material is uniformly dispersed, the electronic conduction capability of the composite material can be greatly improved, and the excellent charge and discharge performance of the material is realized.
Drawings
Fig. 1 is an XRD pattern of the lithium iron phosphate/graphene composite material prepared in example 1.
Fig. 2 is a charge-discharge curve of the lithium iron phosphate/graphene composite material prepared in example 1.
Detailed Description
The invention is further described with reference to the accompanying drawings and the detailed description below:
example 1
A preparation method of a lithium iron phosphate/graphene composite material comprises the following steps:
1) weighing 1.5g of anhydrous iron phosphate, 777mg of anhydrous lithium carbonate and 80mg of graphene by using 10 mL of ethylene glycol and 20 mL of ethanol, placing the mixture in a ball milling tank, and carrying out ball milling for 5 hours;
2) filtering the dispersion liquid after ball milling, and separating to obtain a solid mixture;
3) and (3) placing the solid mixture in a tubular furnace, heating to 700 ℃ at the speed of 5 ℃/min in a nitrogen atmosphere for heat treatment for 2h, and cooling to room temperature to obtain the lithium iron phosphate/graphene composite material.
The XRD pattern of the lithium iron phosphate/graphene composite material obtained through the process is shown in figure 1; the material has a specific discharge capacity of about 155mAh/g at a current density of 17mA/g, as shown in FIG. 2.
Example 2
A preparation method of a lithium iron phosphate/graphene composite material comprises the following steps:
1) mixing 5mL of glycerol and 20 mL of ethanol, weighing 1.5g of anhydrous iron phosphate, 777mg of anhydrous lithium carbonate and 32mg of graphene, placing the mixture in a ball milling tank, and carrying out ball milling for 2 hours;
2) filtering the dispersion liquid after ball milling, and separating to obtain a solid mixture;
3) and (3) placing the solid mixture in a tubular furnace, heating to 800 ℃ at the speed of 2 ℃/min in a nitrogen atmosphere for heat treatment for 2h, and cooling to room temperature to obtain the lithium iron phosphate/graphene composite material.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (8)
1. A preparation method of a lithium iron phosphate/graphene composite material is characterized by comprising the following steps: the method comprises the following steps:
1) measuring a certain volume of high-boiling-point organic alcohol and ethanol, and weighing a certain amount of iron phosphate, lithium carbonate and graphene according to the metering ratio in the molecular formula of the lithium iron phosphate, and carrying out solid-phase ball milling;
2) filtering the dispersion liquid obtained in the step 1), and separating a solid mixture from liquid;
3) and (3) placing the solid mixture obtained in the step 2) into an atmosphere furnace, and carrying out heat treatment for a period of time under the protection of a non-oxidizing atmosphere to obtain the lithium iron phosphate/graphene composite material.
2. The method for preparing a lithium iron phosphate/graphene composite material according to claim 1, wherein the method comprises the following steps: in the step 1), the high-boiling-point alcohol is ethylene glycol or glycerol.
3. The method for preparing a lithium iron phosphate/graphene composite material according to claim 1, wherein the method comprises the following steps: in the step 1), the volume ratio of the high-boiling-point alcohol to the ethanol is 1: 1-3.
4. The method for preparing a lithium iron phosphate/graphene composite material according to claim 1, wherein the method comprises the following steps: in the step 1), the addition amount of the lithium carbonate is 105% of the theoretical amount.
5. The method for preparing a lithium iron phosphate/graphene composite material according to claim 1, wherein the method comprises the following steps: in the step 1), the volume of the mixed alcohol is 5-10 times of the volume of the raw material powder.
6. The method for preparing a lithium iron phosphate/graphene composite material according to claim 1, wherein the method comprises the following steps: in the step 1), the addition amount of the graphene is 2-5% of the mass of the lithium iron phosphate.
7. The method for preparing a lithium iron phosphate/graphene composite material according to claim 1, wherein the method comprises the following steps: in the step 1), the ball milling time is 2-5 hours.
8. The method for preparing a lithium iron phosphate/graphene composite material according to claim 1, wherein the method comprises the following steps: in the step 3), the gas used in the inert atmosphere is nitrogen or argon; the heat treatment temperature is 500-800 ℃, and the heat treatment time is 2-5 h; the heating rate in the heat treatment process is 1-5 ℃/min.
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| CN201911418697.3A CN111129471A (en) | 2019-12-31 | 2019-12-31 | Preparation method of lithium iron phosphate/graphene composite material |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102169986A (en) * | 2011-04-02 | 2011-08-31 | 江苏乐能电池股份有限公司 | Preparation method of lithium ferric phosphate / grapheme composite positive electrode material |
| CN102683702A (en) * | 2012-05-31 | 2012-09-19 | 卧龙电气集团股份有限公司 | Preparation method of lithium iron phosphate with surface being uniformly coated by carbon |
| CN103943864A (en) * | 2014-04-15 | 2014-07-23 | 中南大学 | Lithium iron phosphate-based composite positive electrode material as well as preparation method and application thereof |
| CN105514432A (en) * | 2016-01-13 | 2016-04-20 | 李震祺 | Lithium iron phosphate composite cathode material and preparation method thereof |
| CN109326777A (en) * | 2018-08-28 | 2019-02-12 | 北京泰丰先行新能源科技有限公司 | A kind of preparation method of lithium iron phosphate cell material |
-
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- 2019-12-31 CN CN201911418697.3A patent/CN111129471A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102169986A (en) * | 2011-04-02 | 2011-08-31 | 江苏乐能电池股份有限公司 | Preparation method of lithium ferric phosphate / grapheme composite positive electrode material |
| CN102683702A (en) * | 2012-05-31 | 2012-09-19 | 卧龙电气集团股份有限公司 | Preparation method of lithium iron phosphate with surface being uniformly coated by carbon |
| CN103943864A (en) * | 2014-04-15 | 2014-07-23 | 中南大学 | Lithium iron phosphate-based composite positive electrode material as well as preparation method and application thereof |
| CN105514432A (en) * | 2016-01-13 | 2016-04-20 | 李震祺 | Lithium iron phosphate composite cathode material and preparation method thereof |
| CN109326777A (en) * | 2018-08-28 | 2019-02-12 | 北京泰丰先行新能源科技有限公司 | A kind of preparation method of lithium iron phosphate cell material |
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Application publication date: 20200508 |