CN111540887B

CN111540887B - Carbon-coated cobaltosic oxide and tin dioxide composite lithium battery material and preparation method thereof

Info

Publication number: CN111540887B
Application number: CN202010334747.6A
Authority: CN
Inventors: 李星; 张蓓蓓; 刘语舟; 仇晓阳
Original assignee: Ningbo University
Current assignee: Zhejiang New Era Zhongneng Technology Co ltd
Priority date: 2020-04-24
Filing date: 2020-04-24
Publication date: 2021-05-14
Anticipated expiration: 2040-04-24
Also published as: CN111540887A

Abstract

The invention discloses a carbon-coated tricobalt tetroxide and tin dioxide composite lithium battery material and a preparation method thereof. The invention uses cobalt acetate tetrahydrate and dibutyltin diacetate as main raw materials, and adds an appropriate amount of polymer (PVP) As a binder, electrospinning technology is used to prepare electrospinning products under high voltage conditions, and then sintered in a tube furnace under air and nitrogen atmospheres to obtain a carbon-coated tricobalt tetroxide and tin dioxide composite Lithium battery materials, in the whole preparation process, are simple in operation, low in cost, and low in equipment investment, and are suitable for mass production.

Description

Carbon-coated cobaltosic oxide and tin dioxide composite lithium battery material and preparation method thereof

Technical Field

The invention belongs to the field of material chemistry, and particularly relates to a carbon-coated cobaltosic oxide and tin dioxide composite lithium battery material and a preparation method thereof.

Background

Along with the continuous development of human economic society and the continuous promotion of the economic globalization process, the problems of environmental pollution and energy shortage caused by the consumption of fossil fuels are highlighted day by day, people begin to realize the importance of green and environment-friendly sustainable development, a clean and sustainable renewable new energy and an efficient energy storage system are developed in order to reduce the pollution of the fossil fuels in the using process, and the realization of reasonable configuration of the renewable energy has important strategic significance. Lithium Ion Batteries (LIBs) have the advantages of high specific energy, low self-discharge, good cycle performance, no memory effect, environmental protection and the like, and are high-efficiency secondary batteries with the greatest development prospect and chemical energy storage power sources with the most mature development at present. In the world, lithium ion batteries are widely used, and are small enough to be used in mobile phones, computers, electric vehicles and aerospace vehicles such as mars landers, unmanned aerial vehicles, earth orbit aircrafts, civil airliners and the like, the lithium ion batteries play an important role, along with the development of strategic emerging industries such as energy conservation, environmental protection, information technology, new energy vehicles, aerospace and the like, human beings put forward higher requirements on the performance of lithium secondary batteries, and research and development of efficient lithium secondary batteries with higher energy density and higher safety are urgently needed by scientific research workers on the basis of material innovation. At present, the main factors restricting the improvement of the performance of the high-performance lithium ion battery are the lack of systematic lithium ion battery electrochemical theory, a new lithium ion battery system and a high-performance lithium storage material. The core and key of the lithium ion battery are the development and application of novel lithium storage materials and electrolyte materials, and the nano materials attract wide attention due to the special effects such as small-size effect, quantum effect, surface effect, macroscopic quantum orbital effect and the like, and are expected to become the lithium storage materials of the high-performance lithium secondary battery.

The nano material is a material which is at least one dimension in a nano scale range in a three-dimensional space or is formed by taking a nano structure as a basic unit, and due to the characteristics, the nano material has the characteristics which are not possessed by common materials, can be used as optical materials, electronic materials, magnetic materials and high-strength and high-density materials, and is widely applied to the fields of catalysis, biomedicine, environmental protection, engineering materials and the like. The one-dimensional nano material synthesis method mainly comprises a phase transfer method, a hydrothermal method, an electrostatic spinning method, a chemical vapor deposition method, a vapor phase evaporation method and other methods, wherein the electrostatic spinning technology is the simplest and most effective method for preparing continuous nano fibers, and S.Agarwal et al (Progress in Polymer Science,2013,38: 963-. The electrostatic spinning device mainly comprises a spinning needle head, a high-pressure device, a spinning collector, a temperature and humidity control device and other device parts, wherein a spinning precursor solution is prepared by adding high molecules into a solution as a binder (PVP, PAN, PMMA and the like), in the electrostatic spinning process, the solution sprayed from the needle head is subjected to electrostatic field force and solution surface tension at the same time, when the electrostatic field force and the surface tension of small droplets are balanced, a Taylor cone (Taylor) is formed at the needle head, when the voltage is continuously increased to enable the electrostatic field force received by the droplets to be greater than the surface tension, the droplets are stretched into fibers and are continuously sprayed on the spinning collector under the action of the electrostatic field force to be collected, and the appearance of the electrostatic spinning fibers is mainly influenced by the following factors: system parameters (such as molecular weight of polymer, conductivity, viscosity, dielectric constant and the like of precursor solution), operation parameters (such as specification of a needle, voltage, flow rate, distance between a spinneret and a spinning collecting device and the like), environmental parameters (such as humidity, temperature and the like), and parameters (such as calcining temperature, atmosphere, heating rate and the like) in the annealing process of the spinning fiber have great influence on the structure, the appearance and the performance of the nanofiber material.

Transition metal oxide Co₃O₄Is an important magnetic p-type semiconductor, has wide application in the fields of lithium ion batteries, supercapacitors, gas sensors, catalysts and the like, and can be prepared by a thermal decomposition method, a chemical spray thermal decomposition method, a chemical vapor deposition method, an electrostatic spinning method, a sol-gel method and the like, because of Co₃O₄The preparation method is different, the shapes are also different, and the shapes are nanospheres, nanocubes, nanorods, nanosheets, nanofibers and the like, so that the properties of the material are different due to different shapes. Yang et al (Applied Surface Science,2018,443:401-406) report on Co₃O₄The carbon nanofiber is coated in the carbon nanofiber to be used as a lithium ion battery cathode material, and the lithium ion battery cathode material is maintained at 1024.1mA h after 100 cycles of charge and discharge^-1Capacity of (2), metal oxide SnO₂Is an n-type wide band gap semiconductor material, has wide application in the aspects of catalysis, gas sensitive devices, lithium ion batteries and the like, and J.Liu et al (Chemical Cumminations, 2010,46:1437-₂The @ C core-shell structure is used as a lithium ion battery cathode material and is controlled at 100mA g^-1The capacity is kept at 630mA h after 50 cycles of charge and discharge under the current density^-1. Liu Yu boat et al reported a composite nanowire of cobaltosic oxide and tin oxide, but its capacity as a lithium battery material was too low (application No. 201910990193.2), and it showed good catalytic performance in organic synthesis catalytic oxidation. Carbon coating is beneficial to improving the conductivity and electrochemical properties of the material, so that the technology is widely used.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art, and provides a carbon-coated cobaltosic oxide and tin dioxide composite lithium battery material and a preparation method thereof by combining an electrostatic spinning technology and a high-temperature sintering technology.

The technical scheme adopted by the invention to solve the technical problems is as follows: a preparation method of a carbon-coated cobaltosic oxide and tin dioxide compound lithium battery material comprises the following steps of using an electrostatic spinning technology to prepare an electrostatic spinning product under a high voltage condition by using cobalt acetate-tetrahydrate and dibutyltin diacetate as main raw materials and adding a proper amount of high polymers as an adhesive and stirring for a period of time to obtain a clear and transparent spinning precursor solution, and then sintering in a muffle furnace under the air and nitrogen atmosphere to obtain the carbon-coated cobaltosic oxide and tin dioxide compound lithium battery material, wherein the preparation method specifically comprises the following steps:

(1) adding N, N-Dimethylformamide (DMF) and absolute ethyl alcohol into a beaker, and adding a proper amount of dibutyltin diacetate ((C)₄H₉)₂Sn(OOCCH₃)₂) And cobalt acetate tetrahydrate (C)₄H₆CoO₄·4H₂O), regulating the pH value of the solution to be 4-6 by using glacial acetic acid, and stirring for 2 hours to obtain a clear transparent solution A;

(2) adding a proper amount of PVP (K-130, polyvinylpyrrolidone) into a beaker containing the solution A, and stirring for 3 hours to obtain a clear and transparent spinning precursor solution B;

(3) filling the clear transparent precursor solution B into an injector, and flowing at the voltage of 15-18 kV and the vertical distance between a spinning needle and a receiver of 13-16 cmThe rate is 0.7-1.0 mL h^-1Carrying out electrostatic spinning under the conditions that the temperature of a spinning box body is 30-40 ℃ and the humidity is 20-30% to obtain an electrostatic spinning product, and drying for 5 hours at 80 ℃;

(4) transferring the dried electrostatic spinning product to a tubular furnace in an air atmosphere, sintering at the temperature of 400-500 ℃ for 3h, and then sintering at the temperature of 700-800 ℃ for 1-2 h in a nitrogen atmosphere to obtain a carbon-coated cobaltosic oxide and tin dioxide composite lithium battery material;

the composite lithium battery material contains 5-10% of carbon by mass;

the chemical formula of the composite lithium battery material is abbreviated as Co₃O₄·SnO₂@C；

The solvent and the synthetic raw materials are all chemically pure.

In some embodiments of the invention, the molar ratio of dibutyltin diacetate and cobalt acetate tetrahydrate is 1: 1, the mass ratio of PVP to dibutyltin diacetate is 2: 0.7.

furthermore, the invention also provides a carbon-coated cobaltosic oxide and tin dioxide composite lithium battery material obtained by the preparation method, and the composite nanorod is used as a lithium battery cathode material and has a current density of 800mA g^-1Then, the discharge specific capacity can be maintained at 91mAh g after the circulation for 400 times^-1Above, the coulombic efficiency can be maintained at 93%.

Compared with the prior art, the carbon-coated cobaltosic oxide and tin dioxide composite lithium battery material synthesized by the electrostatic spinning technology has the characteristics that:

(1) adopts electrostatic spinning and high-temperature sintering technology to prepare carbon-coated Co₃O₄·SnO₂A complex;

(2) the composite lithium battery material has nanometer size, increased contact area between the electrode material and the electrolyte, and shortened Li content⁺The transmission path of (2) improves the transmission rate of lithium ions;

(3) the carbon coating can effectively relieve the volume expansion effect of the metal oxide in the charging and discharging processes, simultaneously increase the conductivity of the composite material and improve the theoretical specific capacity of the composite material.

Drawings

FIG. 1 is an XRD pattern of a composite lithium battery material prepared by the invention;

FIG. 2 is an SEM image of a composite lithium battery material prepared by the invention;

FIG. 3 shows that the prepared composite is used as the negative electrode material of the lithium ion battery at 800mA g^-1A charge-discharge cycle performance diagram under current density and a coulombic efficiency diagram.

Detailed Description

The present invention is further described in detail with reference to the following examples, and the technical solution of the present invention is not limited to the specific embodiments listed below, but includes any combination of the specific embodiments.

Example 1:

5.0mL of N, N-dimethylformamide and 5.0mL of absolute ethanol were added to a beaker, and 0.498g (2mmoL) of cobalt acetate tetrahydrate (C)₄H₆CoO₄·4H₂O) and 0.70g (2mmoL) dibutyltin diacetate ((C)₄H₉)₂Sn(OOCCH₃)₂) Regulating the pH value of the solution to be 4 by using glacial acetic acid, stirring for 2h to obtain a transparent clear solution A, adding 2.0g of PVP (K-130, polyvinylpyrrolidone) into the solution A, stirring for 3h to form a clear transparent spinning precursor solution B, filling the clear transparent spinning precursor solution B into an injector, and controlling the voltage to be 15kV, the vertical distance between a spinning needle head and a receiver to be 13cm and the flow rate to be 0.7mL h^-1Carrying out electrostatic spinning under the conditions that the box temperature of a spinning machine is 30 ℃ and the air humidity in the box is 20%, collecting electrostatic spinning products after 10 hours of spinning, and drying for 5 hours at 80 ℃; transferring the dried electrostatic spinning product into a crucible of a tubular furnace, sintering for 3h at the temperature of 400 ℃ in the air atmosphere, and then sintering for 1h at the temperature of 700 ℃ in the nitrogen atmosphere to obtain a black powder product, namely a carbon-coated cobaltosic oxide and tin dioxide compound; the obtained product is analyzed by elements to show that the mass percentage content of carbon is 10 percent; the test analysis is carried out by X-ray powder diffraction, and the result shows that the prepared product is carbon-coated Co₃O₄And SnO₂The complex of (1); the scanning electron microscope observation and analysis shows that the prepared product has the shape of a nano rod (figure 2), and the obtained product is used as the negative electrode material of the lithium ion battery and is added with the solvent at 800mA g^-1Under the current density, the charge and discharge test shows that the cycle performance is tested, the result shows that the cycle is 400 times, and the specific discharge capacity can be kept at 91 mAh.g^-1Above, the coulombic efficiency can be kept at 93% (fig. 3).

Example 2:

5.0mL of N, N-dimethylformamide and 5.0mL of absolute ethanol were added to a beaker, and 0.498g (2mmoL) of cobalt acetate tetrahydrate (C)₄H₆CoO₄·4H₂O) and 0.70g (2mmoL) dibutyltin diacetate ((C)₄H₉)₂Sn(OOCCH₃)₂) Regulating the pH value of the solution to be 6 by using glacial acetic acid, stirring for 2h to obtain a transparent clear solution A, adding 2.0g of PVP (K-130, polyvinylpyrrolidone) into the solution A, stirring for 3h to form a clear transparent spinning precursor solution B, filling the clear transparent spinning precursor solution B into an injector, controlling the voltage to be 18kV, the vertical distance between a spinning needle head and a receiver to be 16cm, and the flow rate to be 1.0mL h^-1Carrying out electrostatic spinning under the conditions that the box body temperature of a spinning machine is 40 ℃ and the air humidity in the box body is 30 percent, collecting electrostatic spinning products after 10 hours of spinning, and drying for 5 hours at 80 ℃; transferring the dried electrostatic spinning product into a crucible of a tubular furnace, sintering for 3h at 500 ℃ in the air atmosphere, and then sintering for 2h at 800 ℃ in the nitrogen atmosphere to obtain a black powder product, and performing element analysis on the obtained product to show that the mass percentage content of carbon is 5%; analyzing the composition structure of the product by X-ray powder diffraction; and analyzing the appearance of the test product by using a scanning electron microscope, and testing the charge-discharge cycle performance and the coulombic efficiency of the product as a lithium ion battery cathode material under a certain current density.

Example 3:

5.0mL of N, N-dimethylformamide and 5.0mL of absolute ethanol were added to a beaker, and 0.498g (2mmoL) of cobalt acetate tetrahydrate (C)₄H₆CoO₄·4H₂O) and 0.70g (2mmoL) dibutyltin diacetate ((C)₄H₉)₂Sn(OOCCH₃)₂) Regulating the pH value of the solution to be 5 by using glacial acetic acid, stirring for 2h to obtain a transparent clear solution A, adding 2.0g of PVP (K-130, polyvinylpyrrolidone) into the solution A, stirring for 3h to form a clear transparent spinning precursor solution B, filling the clear transparent spinning precursor solution B into an injector, and controlling the voltage to be 16.5kV, the vertical distance between a spinning needle head and a receiver to be 15cm and the flow rate to be 0.8mL h^-1Carrying out electrostatic spinning under the conditions that the box temperature of a spinning machine is 35 ℃ and the air humidity in the box is 25 percent, collecting electrostatic spinning products after 10 hours of spinning, and drying for 5 hours at 80 ℃; transferring the dried electrostatic spinning product into a crucible of a tubular furnace, sintering for 3h at the temperature of 450 ℃ in the air atmosphere, and then sintering for 1.5h at the temperature of 750 ℃ in the nitrogen atmosphere to obtain a black powder product, and performing element analysis on the obtained product to show that the mass percentage content of carbon is 7%; analyzing the composition structure of the product by X-ray powder diffraction; and analyzing the appearance of the test product by using a scanning electron microscope, taking the obtained product as a lithium ion battery cathode material, and testing the charge-discharge cycle performance and the coulombic efficiency of the lithium ion battery cathode material under a certain current density.

Claims

1. a preparation method of carbon-coated tricobalt tetroxide and tin dioxide composite lithium battery material, is characterized in that, described preparation method comprises the following steps:

(1) Add N,N-dimethylformamide and absolute ethanol to a beaker, add dibutyltin diacetate and cobalt acetate tetrahydrate, adjust the pH of the solution to 4-6 with glacial acetic acid, stir for 2 h, A clear and transparent solution A was obtained;

(2) Add PVP into the beaker containing solution A and stir for 3 h to obtain clear and transparent spinning precursor solution B;

(3) Load the clear and transparent precursor solution B into the syringe, and spin at a voltage of 15 to 18 kV, a vertical distance between the spinning needle and the receiver of 13 to 16 cm, and a flow rate of 0.7 to 1.0 mL h ^-1 . Electrospinning was carried out under the conditions of box temperature of 30-40 ℃ and humidity of 20%-30% to obtain electrospinning products, which were dried at 80 ℃ for 5 h;

(4) Transfer the dried electrospinning product to the air atmosphere of a tube furnace, sintered at 400-500 °C for 3 h, and then sintered at 700-800 °C for 1-2 h in a nitrogen atmosphere to obtain a carbon coating Cobalt tetroxide and tin dioxide composite lithium battery material;

The carbon content in the composite lithium battery material is 5-10% by mass;

The chemical formula of the composite lithium battery material is abbreviated as Co ₃ O ₄ ·SnO ₂ @C;

The solvents and synthetic raw materials used are all chemically pure;

The molar ratio of the dibutyltin diacetate to the cobalt acetate tetrahydrate is 1:1, and the mass ratio of the PVP to the dibutyltin diacetate is 2:0.7.

2. a carbon-coated tricobalt tetroxide and tin dioxide composite lithium battery material that preparation method as claimed in claim 1 obtains, it is characterized in that, this composite nanorod is used as lithium battery negative electrode material, at current density 800 mA g Under the condition of ^-1 , after 400 charge-discharge cycles, the discharge specific capacity can be maintained above 91 mAh·g ^-1 , and the Coulomb efficiency can be maintained at 93%.