CN111293294B - Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step - Google Patents

Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step Download PDF

Info

Publication number
CN111293294B
CN111293294B CN202010109575.2A CN202010109575A CN111293294B CN 111293294 B CN111293294 B CN 111293294B CN 202010109575 A CN202010109575 A CN 202010109575A CN 111293294 B CN111293294 B CN 111293294B
Authority
CN
China
Prior art keywords
iron phosphate
lithium iron
solution
template
composite material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202010109575.2A
Other languages
Chinese (zh)
Other versions
CN111293294A (en
Inventor
徐静茹
徐天佑
吴孟强
冯婷婷
陈诚
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Electronic Science and Technology of China
Original Assignee
University of Electronic Science and Technology of China
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Electronic Science and Technology of China filed Critical University of Electronic Science and Technology of China
Priority to CN202010109575.2A priority Critical patent/CN111293294B/en
Publication of CN111293294A publication Critical patent/CN111293294A/en
Application granted granted Critical
Publication of CN111293294B publication Critical patent/CN111293294B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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
    • 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
    • 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 invention provides a method for synthesizing a lithium iron phosphate/graphene composite material by adopting a template method in one step, which comprises the following steps: (1) sequentially dissolving a lithium source material, a ferrous iron source material and a phosphorus source material in an organic solvent to obtain a precursor solution, (2) dissolving graphene oxide in the organic solvent to obtain a graphene oxide dispersion solution; (3) dissolving a specific template material in an organic solvent to obtain a template solution, adding the template solution into the lithium iron phosphate precursor solution, and stirring to obtain a mixed solution A; (4) pouring the graphene oxide dispersion solution into the mixed solution A to obtain a mixed solution B; (5) heating the mixed solution B and keeping the temperature and pressure constant to obtain a solid-phase precursor; (6) and (3) grinding the solid-phase precursor in a vacuum oven to obtain the lithium iron phosphate/graphene composite material. The shape characteristics and the particle size of the lithium iron phosphate can be controlled, the particle size is between 100 nm and 300nm, and the specific capacity of the lithium iron phosphate/graphene composite material reaches about 165 mAh/g.

Description

Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step
Technical Field
The invention relates to the field of lithium iron phosphate anode materials, in particular to a method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method.
Background
In the oil crisis period of the 20 th century 70 years, the decrease of dependence on oil and fossil fuel, the vigorous development of clean renewable energy is becoming urgent, and the development of renewable energy is not free from the research of energy storage technology. Batteries have been receiving much attention and research because they can effectively store electrical energy in chemical energy and release it as needed, among which, lithium ion batteries have been widely used because of their high energy density, long life and environmental friendliness.
The lithium iron phosphate used as the anode material in the lithium ion battery has the advantages of low cost, no toxic elements, long cycle life and the like, so the lithium iron phosphate becomes one of the commercialized anode materials in the current lithium ion materials. But due to the low conductivity of lithium iron phosphate itself (10)-9S/cm), low ion diffusivity (10)-3～10-6cm2S), resulting in a limited capacity ratio and lower rate performance of the battery. In order to improve the embarrassment and improve the performance of the material, many researchers generally perform improvement research by three methods, namely ion doping, surface coating and material nanocrystallization. However, most of the modification methods use a high-temperature solid-phase method to sinter the synthetic materials, so that the experiment period is prolonged, and the experiment cost is consumed.
The invention discloses a method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method, which adopts a specific template agent and a solvothermal method to synthesize a lithium iron phosphate material with larger specific surface area and smaller particle size in one step, and the control on the appearance and the size of the lithium iron phosphate material can influence the electrochemical performance of the lithium iron phosphate material to different degrees. When the particle size is small, the diffusion time of lithium ions is shortened, and the diffusion speed of the lithium ions is increased, so that the electrochemical performance of the lithium iron phosphate material is directly improved. The graphene material has high conductivity, the low conductivity of the lithium iron phosphate material can be improved by utilizing the graphene material, most experimenters generally coat the graphene material after synthesizing the lithium iron phosphate material, and the method not only makes the experimental process more complicated and the experimental period longer, but also hardly coats the graphene in the lithium iron phosphate material, and further cannot improve the low conductivity of the material. The method for synthesizing the lithium iron phosphate/graphene composite material by adopting the template method in one step can induce the synthetic morphology and the large specific surface area of the material through the template agent, which not only can be beneficial to the infiltration of the electrolyte, but also can properly modify the circulation capacity of the material. The graphene can be synthesized and coated on the surface of the lithium iron phosphate in one step by a template method, so that the material has better conductivity, and the material can play better electrochemical performance under the condition of no other metal doping and no carbon coating.
Disclosure of Invention
Aiming at the problems of low cycle capacity, non-uniform particle size, long modification preparation period and complexity of the conventional synthesis of lithium iron phosphate materials, the invention aims to rapidly and simply prepare a high-capacity lithium iron phosphate anode material by adopting a template method to synthesize a lithium iron phosphate/graphene composite material in one step.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following steps:
(1) lithium iron phosphate precursor solution: sequentially dissolving a lithium source material, a ferrous iron source material and a phosphorus source material in an organic solvent, stirring until the materials are completely dissolved to obtain a light blue precursor solution, and adjusting the pH value of the solution to be neutral by acid; the molar ratio of the iron source, the lithium source and the phosphorus source in the step (1) is as follows: n isFe:nLi:nP＝1:3:1；
(2) Dissolving graphene oxide accounting for 2% -7% of the theoretical generation amount of the lithium iron phosphate obtained by calculation according to the source material in an organic solvent, stirring for 10-20 min, and then dispersing for 1-3 h by adopting ultrasonic to obtain a graphene oxide dispersion solution;
(3) dissolving a specific template material in an organic solvent to obtain a template solution, adding the template solution into the lithium iron phosphate precursor solution obtained in the step (1), and stirring to obtain a mixed solution A; the dosage of the specific template material is 5 to 7 percent of the theoretical generation amount of the lithium iron phosphate; the specific template agent can induce finally synthesized ferric phosphateThe specific surface area of the lithium material is more than 35m2The/g and particle size are in the nanometer level;
(4) pouring the graphene oxide dispersion solution obtained in the step (2) into the mixed solution A obtained in the step (3) to obtain a mixed solution B;
(5) placing the mixed solution B in the step (4) in a hydrothermal reaction kettle under a protective atmosphere, heating to 180-200 ℃, keeping at a constant temperature and a constant pressure for 18-24 hours, cooling, and performing suction filtration or centrifugation to obtain a solid-phase precursor;
(6) and (3) placing the solid-phase precursor in the step (5) into a vacuum oven, keeping the temperature of 60-80 ℃ for 10-15 h, and then grinding to obtain the lithium iron phosphate/graphene composite material synthesized in one step by a template method.
Preferably, the lithium source, the iron source and the phosphorus source of the material in the step (1) are respectively LiOH & H2O、FeSO4·7H2O、H3PO4Or Li2CO3、FeC2O4·2H2O、NH4H2PO4。
Preferably, the specific template in step (3) is polyvinylpyrrolidone or cetyltrimethylammonium bromide.
Preferably, the organic solvent used in step (1), step (2) and step (3) is ethylene glycol or N, N-dimethylformamide having reducing property.
Preferably, hydrochloric acid or nitric acid with the pH value of 5-6 is used as the acid in the step (1).
Preferably, in the step (2), the optimum addition amount of the graphene oxide is 2% to 3% of the theoretical production amount of the lithium iron phosphate.
Preferably, the protective atmosphere in the step (5) is Ar, N2Or H2Either, the purity was 99.999%.
Preferably, the solid-liquid separation is performed by suction filtration or centrifugation in the step (5), and the process is repeated washing and filtration using absolute ethyl alcohol or absolute methyl alcohol.
Compared with the prior art, the invention has the advantages that: (1) the lithium iron phosphate/graphene composite material is synthesized by adopting a template agent in one step: the composite material is obtained by adding graphene and a template dispersion solution into a lithium iron phosphate precursor solution and performing hydrothermal treatment, so that the time and the energy consumption cost can be saved, and the anode material with uniform particle size and stable performance capacity of 150-165 mAh/g can be prepared. (2) The raw materials are green and environment-friendly, cheap and easy to obtain. (3) The preparation method is synthesized in one step, the experimental process is simple and easy to operate, and the time-consuming period is short. (4) By adopting the specific template agent, the shape characteristics and the particle size of the lithium iron phosphate can be controlled, and the particle size is 100-300 nm. (5) The lithium iron phosphate/graphene composite material synthesized by the template method in one step has high specific capacity which is about 165mAh/g, is close to the theoretical capacity and has good cycle performance.
Drawings
Fig. 1 is an SEM image and a mapping image of a lithium iron phosphate/graphene composite material in example 1 of the present invention, where a is an SEM image of the material at an enlargement of 8 ten thousand times, b is an SEM image of the material at an enlargement of 20 ten thousand times, c is a mapping image of the distribution of iron in the material, and d is a mapping image of the distribution of phosphorus in the material.
Fig. 2 is an XRD pattern of the lithium iron phosphate/graphene composite material in embodiment 1 of the present invention.
Fig. 3 is a graph showing adsorption and desorption curves of the lithium iron phosphate/graphene composite material in embodiment 1 of the present invention.
Fig. 4 is a cycle capacity diagram of the lithium iron phosphate/graphene composite material in embodiment 1 of the present invention.
Fig. 5 is a graph showing adsorption and desorption curves of the lithium iron phosphate/graphene composite material in embodiment 2 of the present invention.
Fig. 6 is a cycle capacity diagram of the lithium iron phosphate/graphene composite material in embodiment 2 of the present invention.
Fig. 7 is a rate capability diagram of the lithium iron phosphate/graphene composite material in embodiment 2 of the present invention.
Detailed Description
Comparative example
In the prior art, a two-step solid phase method is generally adopted to synthesize the lithium iron phosphate/graphene composite material: (1) firstly, preparing a lithium iron phosphate material, namely preparing a lithium iron phosphate material by mixing the following components in a molar ratio of 1: 1: 1, weighing a lithium source, mixing a phosphorus source and an iron source, performing ball milling for 2-4 h, and calcining at 600-700 ℃ for 5-8 h to obtain the lithium iron phosphate material. (2) And preparing a lithium iron phosphate/graphene composite material: and coating the graphene on the surface of the lithium iron phosphate material by adopting a high-temperature solid phase method or a hydrothermal method to obtain the composite material.
The lithium iron phosphate/graphene composite material obtained by the two-step synthesis method is unstable in performance, the circulation capacity is only about 130-150 mAh/g, the particle size of the material is not uniform, and the experiment period is long in time consumption and high in energy consumption.
Example 1
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 1.58g of lithium iron phosphate material:
(1) 1.47g of H are weighed3PO42.78g of FeSO4·7H2O, 1.1313g of LiOH. H2O(nFe:nLi:nP1:3:1), dissolving in 50ml of ethylene glycol solvent, uniformly stirring for 2h to obtain a light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by adopting hydrochloric acid with the pH value of 5.
(2) 0.0316g of graphene oxide (2% of the total amount of 1.58g of lithium iron phosphate material) is dissolved in 40ml of ethylene glycol, and the graphene oxide dispersion solution is obtained by stirring for 15min and then ultrasonically dispersing for 3 h.
(3) Dissolving 0.079g of template agent polyvinylpyrrolidone (5% of the total amount of 1.58g of lithium iron phosphate material) in 10ml of ethylene glycol, fully stirring to obtain a template agent solution, adding the template agent solution into the lithium iron phosphate precursor solution obtained in the step (1), and stirring to obtain a mixed solution A;
(4) pouring the graphene oxide dispersion solution into the mixed solution A to obtain 100ml of mixed solution B;
(5) pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 180 ℃ for 18h, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 60 ℃ for 10h, taking out, and grinding for 1h by using a mortar to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 40m2(ii)/g, particle size 200nm, and a circulating capacity of 165mAh/g at a current density of 0.1C, as shown in FIG. 4. SEM and mapping graphs of the material are shown in figure 1, XRD graph is shown in figure 2, and absorption and desorption curves are shown in figure 3.
Example 2
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 1.58g of lithium iron phosphate material:
(1) 1.47g of H are weighed3PO42.78g of FeSO4·7H2O, 1.1313g of LiOH. H2O(nFe:nLi:nP1:3:1), dissolving in 50ml of ethylene glycol solvent, uniformly stirring for 2h to obtain a light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by adopting hydrochloric acid with the pH value close to 6.
(2) 0.0316g of graphene oxide (2% of the total amount of 1.58g of lithium iron phosphate material) is dissolved in 40ml of ethylene glycol, and the graphene oxide dispersion solution is obtained by stirring for 10min and then ultrasonically dispersing for 1 h.
(3) 0.1106g of a template polyvinylpyrrolidone (7% of the total amount of 1.58g of lithium iron phosphate material) was dissolved in 10ml of ethylene glycol, and the mixture was sufficiently stirred to obtain a template solution. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) pouring the graphene oxide dispersion solution into the mixed solution A to obtain 100ml of mixed solution B;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 200 ℃ for 24 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 80 ℃ for 15h, taking out, and grinding for 1h by using a mortar to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 44m2(ii)/g, particle size 200nm, and cycle capacity of 155mAh/g at a current density of 0.5C, as shown in FIG. 6. The absorption and desorption curves of the material are shown in fig. 5, and the rate performance is shown in fig. 7.
Example 3
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 1.58g of lithium iron phosphate material:
(1) 1.47g of H are weighed3PO42.78g of FeSO4·7H2O, 1.1313g of LiOH. H2O(nFe:nLi:nPDissolving the solution in 50ml of N, N-dimethylformamide solvent, uniformly stirring for 2h to obtain light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by hydrochloric acid with the pH value close to 6.
(2) 0.0474g of graphene oxide (3% of the total amount of 1.58g of lithium iron phosphate material) is dissolved in 40ml of N, N-dimethylformamide, and the graphene oxide dispersion solution is obtained by stirring for 10min and then ultrasonically dispersing for 1 h.
(3) 0.1106g of template polyvinylpyrrolidone (7% of the total amount of 1.58g of lithium iron phosphate material) was dissolved in 10ml of N, N-dimethylformamide, and sufficiently stirred to obtain a template solution. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) pouring the graphene oxide dispersion solution into the mixed solution A to obtain 100ml of mixed solution B;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 180 ℃ for 24 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 80 ℃ for 15h, taking out, and grinding for 1h by using a mortar to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 43m2Particle size per gram200nm, and a circulating capacity of 162mAh/g at a current density of 0.1C.
Example 4
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 1.58g of lithium iron phosphate material:
(1) 1.47g of H are weighed3PO42.78g of FeSO4·7H2O, 1.1313g of LiOH. H2O(nFe:nLi:nPDissolving the solution in 50ml of N, N-dimethylformamide solvent, uniformly stirring for 2h to obtain light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by hydrochloric acid with the pH value close to 6.
(2) 0.0948g of graphene oxide (6% of the total amount of 1.58g of lithium iron phosphate material) is dissolved in 40ml of N, N-dimethylformamide, and the graphene oxide dispersion solution is obtained by stirring for 10min and then ultrasonically dispersing for 1 h.
(3) 0.1106g of template polyvinylpyrrolidone (7% of the total amount of 1.58g of lithium iron phosphate material) was dissolved in 10ml of N, N-dimethylformamide, and sufficiently stirred to obtain a template solution. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) pouring the graphene oxide dispersion solution into the mixed solution A to obtain 100ml of mixed solution B;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 200 ℃ for 24 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 60 ℃ for 15h, taking out, and grinding for 1h by using a mortar to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 38m2(ii)/g, particle size 300nm, and a circulating capacity of 152mAh/g at a current density of 0.1C.
Example 5
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 1.58g of lithium iron phosphate material:
(1) 1.47g of H are weighed3PO42.78g of FeSO4·7H2O, 1.1313g of LiOH. H2O(nFe:nLi:nP1:3:1), dissolving in 50ml of ethylene glycol solvent, uniformly stirring for 2h to obtain a light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by adopting hydrochloric acid with the pH value close to 6.
(2) 0.1106g of graphene oxide (7% of the total amount of 1.58g of lithium iron phosphate material) is dissolved in 40ml of ethylene glycol, and the graphene oxide dispersion solution is obtained by stirring for 10min and then ultrasonically dispersing for 1 h.
(3) 0.1106g of cetyltrimethylammonium bromide (1.58g of 7% of the total amount of lithium iron phosphate material) as a template agent was dissolved in 10ml of ethylene glycol, and sufficiently stirred to obtain a solution of the template agent. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) pouring the graphene oxide dispersion solution into the mixed solution A to obtain 100ml of mixed solution B;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 190 ℃ for 24 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 80 ℃ for 15h, taking out, and grinding for 1h by using a mortar to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 37m2Per g, particle size 300nm, and a circulation capacity of 150mAh/g at a current density of 0.1C.
Example 6
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 1.58g of lithium iron phosphate material:
(1) 1.47g of H are weighed3PO42.78g of FeSO4·7H2O, 1.1313g of LiOH. H2O(nFe:nLi:nP1:3:1), dissolving in 50ml of ethylene glycol solvent, uniformly stirring for 2h to obtain a light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by adopting hydrochloric acid with the pH value close to 6.
(2) 0.1106g of graphene oxide (7% of the total amount of 1.58g of lithium iron phosphate material) is dissolved in 40ml of ethylene glycol, and the graphene oxide dispersion solution is obtained by stirring for 10min and then ultrasonically dispersing for 1 h.
(3) 0.079g of a templating agent polyvinylpyrrolidone (5% of the total amount of 1.58g of lithium iron phosphate material) was dissolved in 10ml of ethylene glycol and sufficiently stirred to obtain a solution of the templating agent. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) pouring the graphene oxide dispersion solution into the mixed solution A to obtain 100ml of mixed solution B;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 180 ℃ for 24 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 80 ℃ for 15h, taking out, and grinding for 1h by using a mortar to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 38m2(iv)/g, particle size 250nm, and a circulating capacity of 153mAh/g at a current density of 0.1C.
Example 7
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 2.21g of a lithium iron phosphate material:
(1) 1.15g of NH are weighed4H2PO41.8g of FeC2O4·2H2O, 1.108g of Li2CO3(nFe:nLi:nP1:3:1) is dissolved in 50ml of glycol solvent and is evenly stirred for 2h to obtain light blue lithium iron phosphate precursor solution, and the solution is measuredThe pH of the test solution was adjusted to neutral with hydrochloric acid at a pH of approximately 6.
(2) 0.0442g of graphene oxide (2.21g of lithium iron phosphate material accounting for 2% of the total weight) is dissolved in 40ml of ethylene glycol, and the graphene oxide dispersion solution is obtained by stirring for 20min and then ultrasonically dispersing for 2 h.
(3) 0.1105g of cetyltrimethylammonium bromide (2.21g of 5% of the total amount of lithium iron phosphate material) as a template agent was dissolved in 10ml of ethylene glycol, and sufficiently stirred to obtain a solution of the template agent. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) obtaining 100ml of mixed solution B from the graphene oxide dispersion solution mixed solution A;
(5) pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 180 ℃ for 20 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 70 ℃ for 12h, taking out, and grinding the solid-phase precursor by a mortar for 1h to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 42m2Per g, particle size 300nm, and a circulating capacity of 155mAh/g at a current density of 0.1C.
Example 8
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 2.21g of a lithium iron phosphate material:
(1) 1.15g of NH are weighed4H2PO41.8g of FeC2O4·2H2O, 1.108g of Li2CO3(nFe:nLi:nPDissolving the solution in 50ml of N, N-dimethylformamide solvent, uniformly stirring for 2h to obtain light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by hydrochloric acid with the pH value close to 6.
(2) 0.0442g of graphene oxide (2.21g of lithium iron phosphate material accounting for 2% of the total weight) is dissolved in 40ml of N, N-dimethylformamide, and the graphene oxide dispersion solution is obtained by stirring for 20min and then ultrasonically dispersing for 2 h.
(3) 0.1547g of cetyltrimethylammonium bromide (7% of the total amount of 2.21g of lithium iron phosphate material) as a template agent was dissolved in 10ml of N, N-dimethylformamide, and sufficiently stirred to obtain a solution of the template agent. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) obtaining 100ml of mixed solution B from the graphene oxide dispersion solution mixed solution A;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 190 ℃ for 20 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 70 ℃ for 12h, taking out, and grinding the solid-phase precursor by a mortar for 1h to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 40m2(ii)/g, particle size 300nm, and a circulating capacity of 153mAh/g at a current density of 0.1C.
Example 9
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 2.21g of a lithium iron phosphate material:
(1) 1.15g of NH are weighed4H2PO41.8g of FeC2O4·2H2O, 1.108g of Li2CO3(nFe:nLi:nPDissolving the solution in 50ml of N, N-dimethylformamide solvent, uniformly stirring for 2h to obtain light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by hydrochloric acid with the pH value close to 6.
(2) 0.0663g of graphene oxide (3% of the total amount of 2.21g of lithium iron phosphate material) is dissolved in 40ml of N, N-dimethylformamide, and the graphene oxide dispersion solution is obtained by stirring for 20min and then ultrasonically dispersing for 2 h.
(3) 0.1547g of template polyvinylpyrrolidone (7% of the total amount of 2.21g of lithium iron phosphate material) was dissolved in 10ml of N, N-dimethylformamide, and sufficiently stirred to obtain a template solution. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) obtaining 100ml of mixed solution B from the graphene oxide dispersion solution mixed solution A;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 200 ℃ for 20 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 70 ℃ for 12h, taking out, and grinding the solid-phase precursor by a mortar for 1h to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 42m2(ii)/g, particle size 300nm, and a circulating capacity of 152mAh/g at a current density of 0.1C.
Example 10
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 2.21g of a lithium iron phosphate material:
(1) 1.15g of NH are weighed4H2PO41.8g of FeC2O4·2H2O, 1.108g of Li2CO3(nFe:nLi:nPDissolving the solution in 50ml of N, N-dimethylformamide solvent, uniformly stirring for 2h to obtain light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by hydrochloric acid with the pH value close to 6.
(2) 0.1105g of graphene oxide (5% of the total amount of 2.21g of lithium iron phosphate material) is dissolved in 40ml of N, N-dimethylformamide, and the graphene oxide dispersion solution is obtained by stirring for 20min and then ultrasonically dispersing for 2 h.
(3) 0.1326g of cetyltrimethylammonium bromide as a template (6% of the total amount of 2.21g of lithium iron phosphate material) was dissolved in 10ml of N, N-dimethylformamide, and sufficiently stirred to obtain a solution of the template. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) obtaining 100ml of mixed solution B from the graphene oxide dispersion solution mixed solution A;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 190 ℃ for 20 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 60 ℃ for 12h, taking out, and grinding for 1h by using a mortar to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 38m2Per g, particle size 300nm, and a circulation capacity of 150mAh/g at a current density of 0.1C.
Example 11
A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method comprises the following specific steps:
this example prepares 2.21g of a lithium iron phosphate material:
(1) 1.15g of NH are weighed4H2PO41.8g of FeC2O4·2H2O, 1.108g of Li2CO3(nFe:nLi:nPDissolving the solution in 50ml of N, N-dimethylformamide solvent, uniformly stirring for 2h to obtain light blue lithium iron phosphate precursor solution, testing the pH value of the solution, and adjusting the pH value to be neutral by using nitric acid with the pH value close to 6.
(2) 0.1547g of graphene oxide (7% of the total amount of 2.21g of lithium iron phosphate material) is dissolved in 40ml of N, N-dimethylformamide, and the graphene oxide dispersion solution is obtained by stirring for 20min and then ultrasonically dispersing for 2 h.
(3) 0.1547g of cetyltrimethylammonium bromide (7% of the total amount of 2.21g of lithium iron phosphate material) as a template agent was dissolved in 10ml of N, N-dimethylformamide, and sufficiently stirred to obtain a solution of the template agent. Adding the precursor solution into the lithium iron phosphate precursor solution obtained in the step (1) and stirring to obtain a mixed solution A;
(4) obtaining 100ml of mixed solution B from the graphene oxide dispersion solution mixed solution A;
(5) and pouring the mixed solution B into a hydrothermal reaction kettle filled with argon protective gas, keeping the temperature at 200 ℃ for 20 hours, and then carrying out centrifugation and washing with absolute ethyl alcohol for 6 times to obtain a solid-phase precursor for solid-liquid separation.
(6) And (3) putting the solid-phase precursor into a vacuum oven, keeping the temperature at 80 ℃ for 12h, taking out, and grinding the solid-phase precursor by a mortar for 1h to obtain the lithium iron phosphate/graphene composite material.
The specific surface area of the prepared composite material is 36m2Per g, particle size 300nm, and a circulation capacity of 150mAh/g at a current density of 0.1C.
While the present invention has been particularly shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (7)

1. A method for synthesizing a lithium iron phosphate/graphene composite material in one step by adopting a template method is characterized by comprising the following steps:
(1) lithium iron phosphate precursor solution: sequentially dissolving a lithium source material, a ferrous iron source material and a phosphorus source material in an organic solvent, stirring until the materials are completely dissolved to obtain a light blue precursor solution, and adjusting the pH value of the solution to be neutral by acid; the molar ratio of the iron source, the lithium source and the phosphorus source in the step (1) is as follows: n isFe:nLi:nP=1:3:1；
(2) Dissolving graphene oxide accounting for 2% -7% of the theoretical generation amount of the lithium iron phosphate obtained by calculation according to the source material in an organic solvent, stirring for 10-20 min, and then dispersing for 1-3 h by adopting ultrasonic to obtain a graphene oxide dispersion solution;
(3) dissolving a template material by an organic solvent to obtain a template solution, adding the template solution into the lithium iron phosphate precursor solution obtained in the step (1), and stirring to obtain a mixed solution A; the amount of the template agent material is 5% -7% of the theoretical generation amount of the lithium iron phosphate; the above-mentionedThe template agent can induce the specific surface area of the finally synthesized lithium iron phosphate material to be more than 35m2The/g and particle size are in the nanometer level; the template material is polyvinylpyrrolidone or cetyl trimethyl ammonium bromide;
(4) pouring the graphene oxide dispersion solution obtained in the step (2) into the mixed solution A obtained in the step (3) to obtain a mixed solution B;
(5) placing the mixed solution B in the step (4) in a hydrothermal reaction kettle under a protective atmosphere, heating to 180-200 ℃, keeping at a constant temperature and a constant pressure for 18-24 hours, cooling, and performing suction filtration or centrifugation to obtain a solid-phase precursor;
(6) and (3) placing the solid-phase precursor in the step (5) into a vacuum oven, keeping the temperature of 60-80 ℃ for 10-15 h, and then grinding to obtain the lithium iron phosphate/graphene composite material synthesized in one step by a template method.
2. The method for synthesizing the lithium iron phosphate/graphene composite material by one step through the template method according to claim 1, wherein the method comprises the following steps: the lithium source, the iron source and the phosphorus source of the material in the step (1) are respectively LiOH. H2O、FeSO4·7H2O、H3PO4Or Li2CO3, FeC2O4 & 2H2O, NH4H2PO 4.
3. The method for synthesizing the lithium iron phosphate/graphene composite material by one step through the template method according to claim 1, wherein the method comprises the following steps: the organic solvent adopted in the step (1), the step (2) and the step (3) is glycol or N, N-dimethylformamide with reducibility.
4. The method for synthesizing the lithium iron phosphate/graphene composite material by one step through the template method according to claim 1, wherein the method comprises the following steps: and (2) the acid in the step (1) is hydrochloric acid or nitric acid with the pH value of 5-6.
5. The method for synthesizing the lithium iron phosphate/graphene composite material by one step through the template method according to claim 1, wherein the method comprises the following steps: the optimal addition amount of the graphene oxide in the step (2) is 2% -3% of the theoretical generation amount of the lithium iron phosphate.
6. The method for synthesizing the lithium iron phosphate/graphene composite material by one step through the template method according to claim 1, wherein the method comprises the following steps: the protective atmosphere in the step (5) is Ar, N2Or H2Either, the purity was 99.999%.
7. The method for synthesizing the lithium iron phosphate/graphene composite material by one step through the template method according to claim 1, wherein the method comprises the following steps: and (5) carrying out suction filtration or centrifugation to separate solid from liquid, and repeatedly cleaning and filtering by adopting absolute ethyl alcohol or absolute methyl alcohol.
CN202010109575.2A 2020-02-22 2020-02-22 Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step Active CN111293294B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010109575.2A CN111293294B (en) 2020-02-22 2020-02-22 Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010109575.2A CN111293294B (en) 2020-02-22 2020-02-22 Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step

Publications (2)

Publication Number Publication Date
CN111293294A CN111293294A (en) 2020-06-16
CN111293294B true CN111293294B (en) 2022-04-22

Family

ID=71023417

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010109575.2A Active CN111293294B (en) 2020-02-22 2020-02-22 Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step

Country Status (1)

Country Link
CN (1) CN111293294B (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102544489A (en) * 2012-01-09 2012-07-04 上海交通大学 Method for preparing graphene-coated olivine type lithium ferric phosphate composite material
CN102790216A (en) * 2012-08-24 2012-11-21 广州市香港科大霍英东研究院 Supercritical solvent thermal preparation method of cathode material lithium iron phosphate of lithium ion battery
CN103904325A (en) * 2014-03-21 2014-07-02 天津大学 High-multiplying-power type lithium iron phosphate/carbon composite material and preparation method thereof
CN105226274A (en) * 2015-07-01 2016-01-06 合肥国轩高科动力能源有限公司 A kind of preparation method of LiFePO4/graphene composite material of graphene uniform dispersion
CN105390682A (en) * 2015-12-08 2016-03-09 广东石油化工学院 Preparation method for lithium iron phosphate microsphere/three-dimensional graphene composite electrode material and application of composite electrode material
CN105977465A (en) * 2016-06-29 2016-09-28 上海应用技术学院 Method for preparing graphene/lithium iron phosphate composite anode materials

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102683697B (en) * 2012-05-14 2014-12-17 国光电器股份有限公司 Preparation method of graphene-based LiFePO4/C composite material

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102544489A (en) * 2012-01-09 2012-07-04 上海交通大学 Method for preparing graphene-coated olivine type lithium ferric phosphate composite material
CN102790216A (en) * 2012-08-24 2012-11-21 广州市香港科大霍英东研究院 Supercritical solvent thermal preparation method of cathode material lithium iron phosphate of lithium ion battery
CN103904325A (en) * 2014-03-21 2014-07-02 天津大学 High-multiplying-power type lithium iron phosphate/carbon composite material and preparation method thereof
CN105226274A (en) * 2015-07-01 2016-01-06 合肥国轩高科动力能源有限公司 A kind of preparation method of LiFePO4/graphene composite material of graphene uniform dispersion
CN105390682A (en) * 2015-12-08 2016-03-09 广东石油化工学院 Preparation method for lithium iron phosphate microsphere/three-dimensional graphene composite electrode material and application of composite electrode material
CN105977465A (en) * 2016-06-29 2016-09-28 上海应用技术学院 Method for preparing graphene/lithium iron phosphate composite anode materials

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
3D porous LiFePO4/graphene hybird cathodes with enhanced performance for Li-ion batteries;Yang Jinli等;《JOURNAL OF POWER SOURCES》;20120615;第208卷;第340-344页 *
液相法合成磷酸铁锂正极材料;杜远超等;《化学进展》;20170124(第01期);第137-148页 *
磷酸铁锂/石墨烯复合材料的合成及电化学性能;南文争等;《材料工程》;20180430;第46卷(第4期);第43-50页 *

Also Published As

Publication number Publication date
CN111293294A (en) 2020-06-16

Similar Documents

Publication Publication Date Title
CN108511714B (en) Transition metal phosphide-carbon composite material and preparation method and application thereof
CN108735997B (en) Lithium iron phosphate-based composite material, and preparation method and application thereof
CN110943213B (en) MOF-derived porous carbon box loaded with Co 3 V 2 O 8 Composite negative electrode material and preparation method and application thereof
CN104752718B (en) A kind of LiMnxFe1‑xPO4Positive electrode active materials and preparation method thereof
CN102593427B (en) A kind of method of preparing carbon-coated spherical nano lithium iron phosphate by liquid phase
CN102583292A (en) Ferric phosphate having micro-nano structure and preparation method thereof as well as lithium iron phosphate material
CN102790216A (en) Supercritical solvent thermal preparation method of cathode material lithium iron phosphate of lithium ion battery
CN113651303B (en) Preparation method of nano flaky ferric phosphate and LiFePO prepared by using same 4 C positive electrode active material
CN106564867A (en) Method for preparing iron phosphate material by adding reducing organic matters
CN104577072A (en) Preparation method of graphene-oxide-based MoO2 high-performance electrode material of lithium/sodium ion battery
CN114864896A (en) In-situ carbon-coated nano lithium iron phosphate cathode material and preparation method thereof
CN107887583A (en) A kind of doped lithium iron phosphate anode material and preparation method thereof
CN113991112A (en) Preparation method of nano-titanium dioxide doped lithium iron phosphate cathode material
CN111525123A (en) Cathode material of water-based lithium ion battery and preparation method and application thereof
CN102502562B (en) Preparation method of lithium iron phosphate, lithium ion battery and anode material and anode thereof
CN105932274A (en) Preparation method of titanium-dioxide-coated spinel lithium-rich lithium manganite positive electrode material
CN103441249B (en) Lithium ion battery ternary cathode material modified by nanometer SnO2 and preparation method of lithium ion battery ternary cathode material
CN110112371A (en) A kind of method of surface coating modification Spinel positive electrode
CN116936771A (en) Hollow spherical shell structure ferric sodium sulfate composite positive electrode material, preparation method and sodium ion battery
CN106159220B (en) Two-step method prepares anode material for lithium-ion batteries LiNi0.80Co0.15Al0.05O2Method
CN114933292B (en) Preparation method and application of lithium iron phosphate
CN105932264A (en) Preparation method of lithium-rich spinel lithium manganite compound
CN111293294B (en) Method for synthesizing lithium iron phosphate/graphene composite material by template method in one step
CN107394188B (en) Preparation method of hollow spherical niobium oxide electrode material for lithium ion battery
CN103553064A (en) Preparation method of lithium ion battery anode material lithium fluoborate

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant