CN110299516B - Preparation method of carbon nanotube array loaded lithium titanate flexible electrode material - Google Patents

Preparation method of carbon nanotube array loaded lithium titanate flexible electrode material Download PDF

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CN110299516B
CN110299516B CN201910498127.3A CN201910498127A CN110299516B CN 110299516 B CN110299516 B CN 110299516B CN 201910498127 A CN201910498127 A CN 201910498127A CN 110299516 B CN110299516 B CN 110299516B
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carbon nanotube
nanotube array
lithium titanate
lithium
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CN110299516A (en
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赵乃勤
李乐
沙军威
马丽颖
李群英
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Tianjin University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • 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
    • H01M4/362—Composites
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H01M2004/027—Negative 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 preparation method of a carbon nanotube array loaded lithium titanate flexible electrode material, which is characterized in that a carbon nanotube array grows on a carbon cloth loaded with a catalyst by a chemical vapor deposition method, the carbon nanotube array is used as a flexible substrate, and the carbon nanotube array loaded lithium titanate flexible electrode material is prepared by a sol-gel method and a high-temperature calcination process, and the preparation method comprises the following steps: loading a carbon nano tube catalyst on the carbon cloth by using an impregnation method; vertically growing a carbon nanotube array in situ by using a chemical vapor deposition method; and preparing the carbon nano tube array loaded lithium titanate flexible electrode material by using a sol-gel method and a high-temperature calcination method.

Description

Preparation method of carbon nanotube array loaded lithium titanate flexible electrode material
Technical Field
The invention relates to a preparation method of a carbon nanotube array loaded lithium titanate flexible electrode material, in particular to a flexible electrode material for electrochemical energy storage, and belongs to the field of electrochemical energy storage.
Background
With the large consumption of non-renewable energy sources such as fossil fuels, the global ecological problem is increasingly prominent, and meanwhile, the energy crisis of each country is intensified, so that the development of novel green clean energy sources is particularly important. Lithium ion batteries are a new type of power source that has emerged in line with current forms of energy development. The lithium ion battery has the characteristics of high energy density, high working voltage, long cycle life, high charging speed, no memory effect, no environmental pollution and the like, so the lithium ion battery is rapidly and widely applied to the energy storage fields of electric automobiles, portable electronic equipment power supplies and the like.
The negative electrode material is an important component of the lithium ion battery, and has an extremely important influence on the performance and the cost of the lithium ion battery. Currently, most of the commercialized lithium ion battery negative electrode materials adopt various lithium intercalation carbon materials. However, such carbon materials have a problem that lithium dendrite precipitates, easily reacts with an electrolyte, and has a significant voltage lagSuch as the like. And spinel type lithium titanate (Li)4Ti5O2) As a 'zero strain material', the material has a stable charge-discharge voltage platform (1.55V), a proper theoretical capacity (175 mAh/g) and high coulombic efficiency (>96%), can effectively avoid the formation of lithium dendrites and SEI (solid electrolyte interface) films during the charging and discharging processes. Li in contrast to commercial graphitic carbon anode materials4Ti5O2Has more excellent electrochemical performance and use safety, and is considered to be an ideal lithium ion intercalation electrode material. However, its nearly insulating electronic conductivity (10)-13S/m) limits the exertion of its performance as a negative electrode material for lithium ion batteries, and thus materials with excellent conductivity are required to be compounded to improve the conductivity.
The carbon nano tube has the characteristics of large specific surface area, excellent conductivity and mechanical property and the like, and can be used as a conductive agent material for improving Li4Ti5O2Is used for the electrical conductivity of (1). For example, CN108878845A reports a lithium titanate microsphere carbon nanotube composite material and a preparation method thereof, in which a carbon nanotube is first acidified, butyl titanate is used as a titanium source, lithium hydroxide is used as a lithium source, ethylene glycol and water are used as solvents, a lithium titanate precursor is obtained by a hydrothermal method, a hydrothermal product is calcined in an air atmosphere to obtain a lithium titanate microsphere, the uniformly dispersed carbon nanotube and the prepared lithium titanate microsphere are ultrasonically dispersed, and a final product, namely the lithium titanate microsphere carbon nanotube composite material, is obtained by suction filtration, and when the lithium titanate microsphere carbon nanotube composite material is used as a negative electrode material of a lithium ion battery, the discharge specific capacity reaches 172mAh/g at a rate of 1C, and the 100C capacity still has 121mAh/g when the charge-discharge rate is high. However, larger Li4Ti5O2Particle size (>2 microns) are easy to generate the phenomenon of structure agglomeration in the charging and discharging processes, and are not beneficial to the infiltration of electrolyte and the transmission of lithium ions and electrons. CN105591082A reports a nano-sheet lithium titanate and multi-walled carbon nanotube composite material and a preparation method thereof, wherein isopropyl titanate is used as a titanium source, lithium hydroxide is used as a lithium source, diethylenetriamine is used as a surfactant, isopropanol and water are used as solvents, and carbon is prepared by surface in-situ reactionWhen the nanotube lithium titanate nanosheet composite negative electrode material is used as a negative electrode material of a lithium ion battery, the specific capacity of the nanotube lithium titanate nanosheet composite negative electrode material is about 172mAh/g after 100 cycles. However, the winding structure of the carbon nanotubes easily causes serious agglomeration problem of the carbon nanotubes, and the low specific surface area of the multi-walled carbon nanotubes also limits the performance of the multi-walled carbon nanotubes as an electrode material. Therefore, researchers prepare the carbon nanotubes into an array structure, and improve the orientation of the carbon nanotubes, so as to optimize an electron transmission path and improve the electrochemical performance of the material. And the carbon cloth replaces copper foil as a current collector, so that not only can good conductivity be improved, but also the electrode has flexible performance, can be applied to the fields of wearable equipment, foldable electronic equipment and the like, and has wide development prospect. CN106784692A reports a preparation method and application of a graphene array-supported lithium titanate/carbon nanotube composite array electrode material, in which a graphene array vertically grows on a carbon cloth by using a microwave plasma enhanced chemical vapor deposition technology, a vertical graphene-supported titanium dioxide composite electrode material is prepared by using an atomic layer deposition technology, lithium hydroxide is used as a lithium source solution to perform a hydrothermal reaction, and then washing, drying and calcining are performed to obtain a graphene array-supported lithium titanate composite array electrode. And finally, growing carbon nanotubes on the graphene array loaded lithium titanate composite array electrode by using a chemical vapor deposition technology, wherein the obtained graphene array loaded lithium titanate/carbon nanotube composite array electrode material has flexible support and high rate performance (89.5% of initial capacity is still obtained after 10000 cycles). Although the above patent improves Li to some extent4Ti5O2The reversible capacity and the cycle life of the cathode material are short, but the carbon nanotube array orientation is not high, the carbon nanotubes are easy to wind and agglomerate in the large-current charging and discharging process, the preparation process is complicated and complex, the process steps are difficult to control, and the application of the cathode material in the lithium ion battery is influenced. Thus, refining Li4Ti5O2The size of the nano-particles, the orientation of the carbon nano-tubes are improved to optimize the electron transmission path, and the improvement of the electrical conductivity of the material is to improve Li4Ti5O2The electrochemical performance of the cathode material is critical.
Disclosure of Invention
The invention aims to provide a preparation method of a carbon nanotube array loaded lithium titanate flexible electrode material to refine Li4Ti5O2The size of the nano particles improves the orientation of the carbon nano tubes. The carbon nanotube array loaded lithium titanate flexible electrode material prepared by the invention also has a self-supporting characteristic, does not need a binder or a conductive agent, improves the effective utilization rate of the material, and provides a new idea for developing flexible electronic devices. The technical scheme adopted by the invention for solving the technical problem is as follows:
a preparation method of a carbon nanotube array loaded lithium titanate flexible electrode material comprises the following steps of growing a carbon nanotube array on a carbon cloth loaded with a catalyst by a chemical vapor deposition method, taking the carbon nanotube array as a flexible substrate, and preparing the carbon nanotube array loaded lithium titanate flexible electrode material by a sol-gel method and a high-temperature calcination process:
(1) carbon nanotube catalyst loaded on carbon cloth by impregnation method
Selecting a proper amount of a first acetylacetone metal complex, a second acetylacetone metal complex, 1, 2-hexadecanediol, oleic acid and oleylamine, dissolving in a proper amount of a dibenzyl ether solution, and preparing a carbon nano tube catalyst by using a reflux method, wherein the reflux temperature is 120-300 ℃, so as to prepare the carbon nano tube catalyst; then soaking the carbon cloth in a carbon nano tube catalyst solution, taking out and drying to obtain the carbon cloth loaded with the carbon nano tube catalyst, wherein the first acetylacetone metal complex is one of acetylacetone complexes of iron, cobalt, nickel, molybdenum and tungsten; the second acetylacetone metal complex-is one of aluminum and magnesium acetylacetone complexes.
(2) In-situ vertical growth of carbon nanotube array by chemical vapor deposition
And (2) placing the carbon cloth loaded with the carbon nanotube catalyst prepared in the step (1) in a tubular furnace constant-temperature area, heating the tubular furnace to 400-1200 ℃ under the protection of an inert gas atmosphere under a vacuum condition, then introducing hydrogen and a carbon source gas, carrying out in-situ growth of a carbon nanotube array on the carbon cloth, and after the growth is finished, cooling to room temperature under the protection of the inert gas, thus obtaining the vertical carbon nanotube array grown in situ on the carbon cloth.
(3) Preparing carbon nano tube array loaded lithium titanate flexible electrode material by using sol-gel method and high-temperature calcination method
Dissolving a lithium source and a titanium source with certain mass in an organic solvent according to a certain molar ratio of 4 (1-10) to obtain a uniform and clear lithium titanate precursor solution; dipping the vertical carbon nanotube array grown in situ on the carbon cloth obtained in the step (2) in a lithium titanate precursor solution, taking out and drying; and (3) placing the dried carbon nanotube array loaded lithium titanate precursor in a tube furnace, heating to 300-900 ℃ under the protection of inert atmosphere, preserving the temperature for a period of time, and cooling to room temperature to finally prepare the carbon nanotube array loaded lithium titanate flexible electrode material.
Preferably, in the step (1), the first acetylacetone metal complex, the second acetylacetone metal complex, 1, 2-hexadecanediol, oleic acid and oleylamine are weighed according to the mass ratio of 1 (0.1-10): (0.5-8): 0.1-5.
The inert gas is nitrogen or argon.
The flow rate of hydrogen is 50 to 1000mL/min, and the flow rate of carbon source gas is 2 to 50 mL/min.
The carbon source gas is one or more of acetylene, methane, natural gas and water gas which are mixed randomly.
The lithium source is one of lithium hydroxide, lithium acetate, lithium chloride and lithium nitrate.
The titanium source is one of titanium tetrachloride, isobutyl titanate, tetrabutyl titanate, isopropyl titanate and titanium acetylacetonate;
the organic solvent is one of methanol, ethanol and diethyl ether.
The organic solvent is one of methanol, ethanol and diethyl ether.
The obtained carbon nanotube array loaded lithium titanate flexible electrode material is used as a lithium ion battery cathode material.
The invention has the beneficial effects that: compared with the prior art, the method has the prominent substantive characteristics as follows:
(1) in the design process of the invention, main factors influencing the electrochemical performance of the flexible electrode material loaded with lithium titanate by the carbon nanotube array are considered to be the conductivity characteristic of lithium titanate, the particle size of lithium titanate particles and the microstructure of the lithium titanate loaded by the carbon nanotube array. Among them, the conductivity has a prominent influence on the electrochemical properties of the lithium titanate electrode material. In the design process of the invention, the influence of the conductivity of lithium titanate on the electrochemical performance of the cathode material is fully considered, a chemical vapor deposition method is innovatively adopted, a carbon nanotube array with high orientation, high conductivity and large specific surface area is grown in situ on a flexible conductive current collector, namely carbon cloth, and is used as a conductive agent, and the carbon nanotube array loaded lithium titanate flexible electrode material is prepared by utilizing a process combining a sol-gel method and high-temperature calcination. The carbon nanotube array loaded lithium titanate flexible electrode material can greatly improve the conductivity of lithium titanate nanoparticles, and has good structural stability due to the interpenetration of the carbon nanotubes; meanwhile, the particle size of lithium titanate nano particles prepared by the process combining the sol-gel method and high-temperature calcination is only 20-200 nm, the diffusion path of lithium ions can be obviously shortened, the lithium titanate nano particles are uniformly loaded on a vertically-oriented carbon nano tube array, and the carbon nano tube array is used as a conductive network for in-situ growth and a flexible current collector, so that the conductivity of a lithium titanate negative electrode material can be effectively improved, the contact resistance between the electrode material and the current collector material is reduced, and the rapid transmission of ions and electrons in the electrochemical reaction process is facilitated. Therefore, the carbon nanotube array loaded lithium titanate flexible negative electrode material prepared by the method has excellent electrochemical performance.
(2) In the design process of the invention, the key problems of the preparation process, the period and the like of the flexible electrode material of the lithium titanate loaded by the carbon nano tube array are fully considered, and the lithium titanate nano particles are loaded on the carbon nano tube array by innovatively adopting the process of combining the sol-gel method and high-temperature calcination. The flexible electrode material of the carbon nanotube array loaded lithium titanate finally prepared by the process method has good electrochemical performance, and also has the advantages of simple preparation process, short process period and high preparation efficiency.
Compared with the prior art, the method provided by the invention has the following remarkable improvements:
(1) compared with the prior art CN1O3594694A, the method disclosed by the invention overcomes the problems that the reversible capacity of the reaction is reduced too fast in the electrochemical reaction process, the rate capability and the cycle performance of the lithium titanate material are influenced and the like due to poor conductivity and low electronic conductivity of the lithium titanate material in the prior art.
(2) Compared with the prior art CN108878845A, the method of the invention overcomes the problems that the lithium titanate prepared by the prior art has large particle size, no effective electric contact is available in the lithium titanate particles, the exertion of the electrochemical performance of the lithium titanate is limited, the lithium storage capacity and the stability of the electrode material are influenced and the like,
(3) compared with the prior art which uses CN105591082A and CN106784692A, the method of the invention overcomes the problems that the carbon nano tube in the lithium titanate and carbon nano tube composite material prepared by the prior art has low orientation and winding structure, and the carbon nano tube is easy to cause serious agglomeration, so that the performance of the carbon nano tube as an electrode material is limited, and the like, and the problems of complicated steps, long time consumption and the like of preparing the lithium titanate and carbon nano tube composite material.
(4) The carbon nanotube array loaded lithium titanate flexible electrode material prepared by the invention is controlled by a synthesis process at 0.1mA/cm2After the battery is circulated for 100 weeks, the specific discharge capacity of the battery can reach 0.420-0.120 mAh/cm2After the battery is circulated for 500 weeks, the specific discharge capacity of the battery can still reach 0.402-0.108 mAh/cm2Has high reversible capacity and excellent cycle performance.
In a word, the flexible electrode material of the carbon nanotube array loaded lithium titanate prepared by the invention overcomes the defects of large particle size of the lithium titanate prepared in the prior art, low orientation and winding structure of the carbon nanotube in the lithium titanate and carbon nanotube composite material, poor electrochemical performance of the lithium ion battery cathode material prepared by the flexible electrode material, complex preparation process and long time consumption.
Drawings
The invention is further illustrated with reference to the following figures and examples.
Fig. 1(a) is a scanning electron microscope photograph of an original carbon cloth, and fig. 1(b) is a scanning electron microscope photograph of a vertical carbon nanotube array grown in situ on a carbon cloth prepared in example 1 of the present invention.
Fig. 2 is a scanning electron microscope photograph of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention.
Fig. 3 is an XRD spectrum of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention.
Fig. 4 is a charge-discharge curve of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention as a negative electrode material.
Fig. 5 is a cycle performance curve of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention as a negative electrode material.
Detailed Description
Example 1
(1) Loading a carbon nano tube catalyst on the carbon cloth by using an impregnation method;
dissolving 3.00g of iron acetylacetonate, 1.14g of aluminum acetylacetonate, 1.61g of 1, 2-hexadecanediol, 0.9g of oleic acid and 0.9g of oleylamine in 50mL of a mixed solution of benzyl ether, and preparing the carbon nanotube catalyst by using a reflux method, wherein the reflux temperature is 200 ℃ and the reflux time is 60min, thus obtaining the carbon nanotube catalyst. And then soaking the carbon cloth in the carbon nano tube catalyst solution, taking out and drying to obtain the carbon cloth loaded with the carbon nano tube catalyst.
(2) Vertically growing a carbon nanotube array in situ by using a chemical vapor deposition method;
and (2) placing the carbon cloth loaded with the carbon nanotube catalyst prepared in the step (1) in a tubular furnace constant-temperature area, heating the tubular furnace to 850 ℃ under the protection of an argon gas atmosphere under a vacuum condition, then introducing hydrogen (the flow rate is 500mL/min) and acetylene gas (the flow rate is 8mL/min), carrying out in-situ growth of the carbon nanotube array on the carbon cloth for 10min, and after the growth is finished, cooling to room temperature under the protection of the argon gas, thus obtaining the vertical carbon nanotube array grown in situ on the carbon cloth.
(3) Preparing a carbon nano tube array loaded lithium titanate flexible electrode material by using a sol-gel method and a high-temperature calcination method;
dissolving 0.44g of lithium acetate and 2.1g of isopropyl titanate (the molar ratio is 4:5) in 50mL of absolute ethanol to obtain a uniform and clear lithium titanate precursor solution; dipping the vertical carbon nanotube array grown in situ on the carbon cloth obtained in the step (2) in a lithium titanate precursor solution, taking out and drying; and (3) placing the dried carbon nanotube array loaded lithium titanate precursor in a tube furnace, heating to 700 ℃ under the protection of argon atmosphere, preserving heat for 12 hours, and cooling to room temperature to finally prepare the carbon nanotube array loaded lithium titanate flexible electrode material.
Fig. 1(a) is a scanning electron microscope photograph of an original carbon cloth, and fig. 1(b) is a scanning electron microscope photograph of a vertical carbon nanotube array grown in situ on a carbon cloth prepared in example 1 of the present invention. As can be seen from fig. 1, the carbon nanotube array with high orientation and high density uniformly and vertically grows on the carbon cloth substrate, while maintaining the original microscopic morphology of the carbon cloth.
Fig. 2 is a scanning electron microscope photograph of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention. As can be seen from the figure, the lithium titanate nanoparticles are uniformly distributed among the carbon nanotube arrays and have small sizes, the size of the particles is about 200nm, and the lithium titanate nanoparticles are connected by the carbon nanotubes without obvious bonding agglomeration.
Fig. 3 is an XRD spectrum of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention. Because the synthesized carbon nanotube array-supported lithium titanate composite material has carbon nanotubes, a diffraction peak of carbon is observed at 26.4 ℃; by comparison, the diffraction peak in the figure is matched with the labeled pdf card of lithium titanate, which shows that the composite material contains a lithium titanate phase.
The carbon nanotube array loaded lithium titanate flexible electrode material prepared in the embodiment 1 of the invention is cut into small pieces to be used as a lithium ion battery cathode material, namely a working electrode, a metal lithium piece is used as an auxiliary electrode, and lithium hexafluorophosphate (lithium hexafluorophosphate) (with the concentration of 1 mol/L) is adoptedLiPF6) The solution (dissolved in a mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1: 1) is used as an electrolyte, and a microporous polypropylene membrane is used as a diaphragm. The cell is assembled in a glove box filled with argon and with the humidity less than 1%, and a working electrode, a diaphragm filled with electrolyte and an auxiliary electrode are assembled into a button type CR2025 half cell. And (3) standing the assembled lithium ion battery for 12 hours to perform constant current charge and discharge test, wherein the charge and discharge voltage is 1.0-3.0V, and the capacity, rate characteristics and charge and discharge cycle performance of the lithium ion battery cathode are measured in a room temperature environment.
Fig. 4 is a charge-discharge curve of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention as a negative electrode material. As can be seen from the figure, the first charge capacity and the discharge capacity of the carbon nanotube array-supported lithium titanate composite material prepared in the embodiment are respectively 0.205mAh/cm2And 0.198mAh/cm2The irreversible capacity was 3.41% of the first discharge capacity.
Fig. 5 is a cycle performance curve of the carbon nanotube array-supported lithium titanate composite material prepared in example 1 of the present invention as a negative electrode material. As can be seen from the figure, the reversible capacity of the carbon nanotube array-supported lithium titanate composite material prepared in the embodiment reaches 0.162mAh/cm after 100 cycles2And the coulombic efficiency of the electrode material is as high as 101.2%, the reversible capacity of the electrode material is greatly improved, and the cycle performance is stable.
Example 2
(1) Loading a carbon nano tube catalyst on the carbon cloth by using an impregnation method;
dissolving 3.00g of iron acetylacetonate, 0.57g of aluminum acetylacetonate, 3.22g of 1, 2-hexadecanediol, 0.30g of oleic acid and 2.25g of oleylamine in 50mL of a mixed solution of benzyl ether, and preparing the carbon nanotube catalyst by a reflux method, wherein the reflux temperature is 220 ℃ and the reflux time is 240 min. And then soaking the carbon cloth in the carbon nano tube catalyst solution, taking out and drying to obtain the carbon cloth loaded with the carbon nano tube catalyst.
(2) Vertically growing a carbon nanotube array in situ by using a chemical vapor deposition method;
and (2) placing the carbon cloth loaded with the carbon nanotube catalyst prepared in the step (1) in a tubular furnace constant temperature area, heating the tubular furnace to 700 ℃ under the protection of an argon gas atmosphere under a vacuum condition, then introducing hydrogen (the flow rate is 200mL/min) and acetylene gas (the flow rate is 20mL/min), carrying out in-situ growth of the carbon nanotube array on the carbon cloth for 120min, and after the growth is finished, cooling to room temperature under the protection of the argon gas, thus obtaining the vertical carbon nanotube array grown in situ on the carbon cloth.
(3) Preparing a carbon nano tube array loaded lithium titanate flexible electrode material by using a sol-gel method and a high-temperature calcination method;
dissolving 2.2g of lithium acetate and 5.25g of isopropyl titanate (the molar ratio is 4:2.5) in 50mL of absolute ethanol to obtain a uniform and clear lithium titanate precursor solution; dipping the vertical carbon nanotube array grown in situ on the carbon cloth obtained in the step (2) in a lithium titanate precursor solution, taking out and drying; and (3) placing the dried carbon nanotube array loaded lithium titanate precursor in a tube furnace, heating to 500 ℃ under the protection of argon atmosphere, preserving heat for 4 hours, and cooling to room temperature to finally prepare the carbon nanotube array loaded lithium titanate flexible electrode material.
The carbon nanotube array loaded lithium titanate flexible electrode material prepared in the embodiment 2 of the invention is cut into small pieces to be used as a lithium ion battery cathode material, namely a working electrode, a metal lithium piece is used as an auxiliary electrode, and lithium hexafluorophosphate (LiPF) with the concentration of 1mol/L is adopted6) The solution (dissolved in a mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1: 1) is used as an electrolyte, and a microporous polypropylene membrane is used as a diaphragm. The cell is assembled in a glove box filled with argon and with the humidity less than 1%, and a working electrode, a diaphragm filled with electrolyte and an auxiliary electrode are assembled into a button type CR2025 half cell. And (3) standing the assembled lithium ion battery for 12 hours to perform constant current charge and discharge test, wherein the charge and discharge voltage is 1.0-3.0V, and the capacity, rate characteristics and charge and discharge cycle performance of the lithium ion battery cathode are measured in a room temperature environment.
Example 3
(1) Loading a carbon nano tube catalyst on the carbon cloth by using an impregnation method;
0.6g of iron acetylacetonate, 0.57g of aluminum acetylacetonate, 4.385g of 1, 2-hexadecanediol, 1.8g of oleic acid and 0.2g of oleylamine are dissolved in 200mL of a mixed solution of benzyl ether, and a carbon nanotube catalyst is prepared by a reflux method, wherein the reflux temperature is 300 ℃ and the reflux time is 1 min. And then soaking the carbon cloth in the carbon nano tube catalyst solution, taking out and drying to obtain the carbon cloth loaded with the carbon nano tube catalyst.
(2) Vertically growing a carbon nanotube array in situ by using a chemical vapor deposition method;
and (2) placing the carbon cloth loaded with the carbon nanotube catalyst prepared in the step (1) in a tubular furnace constant-temperature area, heating the tubular furnace to 1200 ℃ under the protection of an argon gas atmosphere under a vacuum condition, then introducing hydrogen (the flow rate is 1000mL/min) and acetylene gas (the flow rate is 50mL/min), carrying out in-situ growth of the carbon nanotube array on the carbon cloth for 720min, and after the growth is finished, cooling to room temperature under the protection of the argon gas, thus obtaining the vertical carbon nanotube array grown in situ on the carbon cloth.
(3) Preparing a carbon nano tube array loaded lithium titanate flexible electrode material by using a sol-gel method and a high-temperature calcination method;
dissolving 5.0g of lithium acetate and 4.76g of isopropyl titanate (the molar ratio is 4:1) in 100mL of absolute ethanol to obtain a uniform and clear lithium titanate precursor solution; dipping the vertical carbon nanotube array grown in situ on the carbon cloth obtained in the step (2) in a lithium titanate precursor solution, taking out and drying; and (3) placing the dried carbon nanotube array loaded lithium titanate precursor in a tube furnace, heating to 900 ℃ under the protection of argon atmosphere, preserving heat for 1h, and cooling to room temperature to finally prepare the carbon nanotube array loaded lithium titanate flexible electrode material.
The carbon nanotube array-supported lithium titanate flexible electrode material prepared in the embodiment 3 of the invention is cut into small pieces to be used as a lithium ion battery cathode material, namely a working electrode, a metal lithium piece is used as an auxiliary electrode, and lithium hexafluorophosphate (LiPF) with the concentration of 1mol/L is adopted6) The solution (dissolved in a mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1: 1) is used as an electrolyte, and a microporous polypropylene membrane is used as a diaphragm. Battery assemblyThe process is carried out in a glove box filled with argon and with the humidity less than 1%, and a working electrode, a diaphragm filled with electrolyte and an auxiliary electrode are assembled into a button type CR2025 half cell. And (3) standing the assembled lithium ion battery for 12 hours to perform constant current charge and discharge test, wherein the charge and discharge voltage is 1.0-3.0V, and the capacity, rate characteristics and charge and discharge cycle performance of the lithium ion battery cathode are measured in a room temperature environment.
Example 4
(1) Loading a carbon nano tube catalyst on the carbon cloth by using an impregnation method;
dissolving 0.15g of iron acetylacetonate, 1.40g of aluminum acetylacetonate, 0.1g of 1, 2-hexadecanediol, 0.75g of oleic acid and 0.75g of oleylamine in 10mL of benzyl ether, and preparing the carbon nanotube catalyst by a reflux method, wherein the reflux temperature is 120 ℃ and the reflux time is 720min, thus obtaining the carbon nanotube catalyst. And then soaking the carbon cloth in the carbon nano tube catalyst solution, taking out and drying to obtain the carbon cloth loaded with the carbon nano tube catalyst.
(2) Vertically growing a carbon nanotube array in situ by using a chemical vapor deposition method;
and (2) placing the carbon cloth loaded with the carbon nanotube catalyst prepared in the step (1) in a tubular furnace constant-temperature area, heating the tubular furnace to 400 ℃ under the protection of an argon gas atmosphere under a vacuum condition, then introducing hydrogen (the flow rate is 50mL/min) and acetylene gas (the flow rate is 2mL/min), carrying out in-situ growth of the carbon nanotube array on the carbon cloth for 1min, and after the growth is finished, cooling to room temperature under the protection of the argon gas, thus obtaining the vertical carbon nanotube array grown in situ on the carbon cloth.
(3) Preparing a carbon nano tube array loaded lithium titanate flexible electrode material by using a sol-gel method and a high-temperature calcination method;
dissolving 0.1g of lithium acetate and 4.8g of isopropyl titanate (the molar ratio is 4:10) in 1mL of absolute ethanol to obtain a uniform and clear lithium titanate precursor solution; dipping the vertical carbon nanotube array grown in situ on the carbon cloth obtained in the step (2) in a lithium titanate precursor solution, taking out and drying; and (3) placing the dried carbon nanotube array loaded lithium titanate precursor in a tube furnace, heating to 300 ℃ under the protection of argon atmosphere, preserving the heat for 48 hours, and cooling to room temperature to finally prepare the carbon nanotube array loaded lithium titanate flexible electrode material.
The carbon nanotube array-supported lithium titanate flexible electrode material prepared in the embodiment 4 of the invention is cut into small pieces to be used as a lithium ion battery negative electrode material, namely a working electrode, a metal lithium piece is used as an auxiliary electrode, and lithium hexafluorophosphate (LiPF) with the concentration of 1mol/L is adopted6) The solution (dissolved in a mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1: 1) is used as an electrolyte, and a microporous polypropylene membrane is used as a diaphragm. The cell is assembled in a glove box filled with argon and with the humidity less than 1%, and a working electrode, a diaphragm filled with electrolyte and an auxiliary electrode are assembled into a button type CR2025 half cell. And (3) standing the assembled lithium ion battery for 12 hours to perform constant current charge and discharge test, wherein the charge and discharge voltage is 1.0-3.0V, and the capacity, rate characteristics and charge and discharge cycle performance of the lithium ion battery cathode are measured in a room temperature environment.
The raw materials referred to in the above examples are commercially available and the equipment and processes used are well known to those skilled in the art.

Claims (8)

1. A preparation method of a carbon nanotube array loaded lithium titanate flexible electrode material comprises the following steps of growing a carbon nanotube array on a carbon cloth loaded with a catalyst by a chemical vapor deposition method, taking the carbon nanotube array as a flexible substrate, and preparing the carbon nanotube array loaded lithium titanate flexible electrode material by a sol-gel method and a high-temperature calcination process:
(1) carbon nanotube catalyst loaded on carbon cloth by impregnation method
Weighing a first acetylacetone metal complex, a second acetylacetone metal complex, 1, 2-hexadecanediol, oleic acid and oleylamine according to the mass ratio of (0.1-10) to (0.5-8) to (0.1-5) of 1.1-5, dissolving in a proper amount of dibenzyl ether solution, and preparing a carbon nano tube catalyst by using a reflux method, wherein the reflux temperature is 120-300 ℃, so as to prepare the carbon nano tube catalyst; then soaking the carbon cloth in a carbon nano tube catalyst solution, taking out and drying to obtain the carbon cloth loaded with the carbon nano tube catalyst, wherein the first acetylacetone metal complex is one of acetylacetone complexes of iron, cobalt, nickel, molybdenum and tungsten; the second acetylacetone metal complex-is one of aluminum and magnesium acetylacetone complexes;
(2) in-situ vertical growth of carbon nanotube array by chemical vapor deposition
Placing the carbon cloth loaded with the carbon nanotube catalyst prepared in the step (1) in a tubular furnace constant-temperature area, heating the tubular furnace to 400-1200 ℃ under the protection of an inert gas atmosphere under a vacuum condition, then introducing hydrogen and a carbon source gas, carrying out in-situ growth of a carbon nanotube array on the carbon cloth, and after the growth is finished, cooling to room temperature under the protection of the inert gas, so as to obtain a vertical carbon nanotube array growing in situ on the carbon cloth;
(3) preparing carbon nano tube array loaded lithium titanate flexible electrode material by using sol-gel method and high-temperature calcination method
Dissolving a lithium source and a titanium source with certain mass in an organic solvent according to a certain molar ratio of 4 (1-10) to obtain a uniform and clear lithium titanate precursor solution; dipping the vertical carbon nanotube array grown in situ on the carbon cloth obtained in the step (2) in a lithium titanate precursor solution, taking out and drying; and (3) placing the dried carbon nanotube array loaded lithium titanate precursor in a tube furnace, heating to 300-900 ℃ under the protection of inert atmosphere, preserving the temperature for a period of time, and cooling to room temperature to finally prepare the carbon nanotube array loaded lithium titanate flexible electrode material.
2. The method of claim 1, wherein the inert gas is nitrogen or argon.
3. The method according to claim 1, wherein in the step (2), the flow rate of the hydrogen gas is 50 to 1000mL/min, and the flow rate of the carbon source gas is 2 to 50 mL/min.
4. The method of claim 1, wherein the carbon source gas in the step (2) is one or more of acetylene, methane, natural gas and water gas, which are optionally mixed.
5. The method of claim 1, wherein the lithium source in step (3) is one of lithium hydroxide, lithium acetate, lithium chloride, and lithium nitrate.
6. The method of claim 1, wherein the titanium source in step (3) is one of titanium tetrachloride, isobutyl titanate, tetrabutyl titanate, isopropyl titanate, and titanium acetylacetonate; the organic solvent is one of methanol, ethanol and diethyl ether.
7. The method according to claim 1, wherein the organic solvent in step (3) is one of methanol, ethanol and diethyl ether.
8. The method of claim 1, wherein the obtained carbon nanotube array-supported lithium titanate flexible electrode material is used as a lithium ion battery negative electrode material.
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