阅读说明：本技术 一种超薄碳包覆二氧化锡纳米复合材料的制备方法 (Preparation method of ultrathin carbon-coated tin dioxide nanocomposite ) 是由 赵永男 高海燕 黄志强 于 2019-04-02 设计创作，主要内容包括：本发明公开了一种超薄碳包覆二氧化锡纳米复合材料的制备方法,具体制备过程如下：1.将一定比例的碳源,锡源和萘溶解于去离子水中,加入适量盐酸调节pH值,然后将混合溶液进行水热反应；2.将水热反应得到的产物置于管式炉中氩气气氛下煅烧,得到超薄碳包覆二氧化锡纳米复合材料。本发明中制备的超薄碳包覆二氧化锡纳米复合材料作为锂离子负极材料具有良好的循环稳定性,优异的倍率性能和高的放电比容量。(The invention discloses a preparation method of an ultrathin carbon-coated tin dioxide nano composite material, which comprises the following specific preparation processes of: 1. dissolving a carbon source, a tin source and naphthalene in a certain proportion in deionized water, adding a proper amount of hydrochloric acid to adjust the pH value, and then carrying out hydrothermal reaction on the mixed solution; 2. and calcining the product obtained by the hydrothermal reaction in a tubular furnace under the argon atmosphere to obtain the ultrathin carbon-coated tin dioxide nano composite material. The ultrathin carbon-coated tin dioxide nanocomposite prepared by the method has good cycling stability, excellent rate performance and high specific discharge capacity when being used as a lithium ion negative electrode material.)

1. A preparation method of an ultrathin carbon-coated tin dioxide nano composite material is characterized by comprising the following steps:

(1) dissolving a carbon source, a tin source and a proper amount of naphthalene and hydrochloric acid in a certain proportion in deionized water, stirring completely, and then placing in a reaction kettle for hydrothermal reaction.

(2) And (3) centrifugally drying the product obtained by hydrothermal preparation, and then carrying out heat treatment in a tubular furnace to obtain the ultrathin carbon-coated tin dioxide nanocomposite.

2. The method for preparing the ultra-thin carbon-coated tin dioxide nanocomposite material as claimed in claim, wherein the molar ratio of the carbon source to the tin source in the step (1) is 1: 0.0018-0.018.

3. The method for preparing the ultra-thin carbon-coated tin dioxide nanocomposite as claimed in claim, wherein the amount of naphthalene added in step (1) is 3-50 mg.

4. The method for preparing the ultra-thin carbon-coated tin dioxide nanocomposite as claimed in claim, wherein the amount of hydrochloric acid added in step (1) is 0.1-2 mL.

5. The method for preparing the ultra-thin carbon-coated tin dioxide nanocomposite material as claimed in claim, wherein the hydrothermal product of the step (2) is subjected to the following heat treatment conditions: the heating rate is 2-8 ℃/min, the heat treatment temperature is 400-.

6. The ultra-thin carbon-coated tin dioxide nanocomposite prepared according to claims 1 to 5 has excellent rate capability, high specific discharge capacity and good cycling stability.

Technical Field

The invention relates to the field of preparation of lithium ion battery electrode materials, and particularly provides a simple preparation method of an ultrathin carbon-coated tin dioxide nano negative electrode material.

Background

Lithium ion batteries are widely used in the fields of portable electronic devices and the like with their remarkable advantages, and are gradually developed into the fields of high-power electric vehicles, large-scale energy storage power stations, smart power grids and the like. Accordingly, the performance requirements for lithium ion batteries are increasing. The electrode material is the most important composition of the lithium ion battery, and the structure and the property of the electrode material determine the core indexes of the lithium ion battery, such as capacity, safety, rate capability, cycling stability and the like. Therefore, there is a need to develop a novel lithium ion battery electrode material that meets the requirements of high energy, high power, high stability and safety.

The stannic oxide-based negative electrode material has high lithium storage capacity (1494mAh g)^-1) Low voltage platform, safety, low price and the like, and is expected to replace graphite to realize a commercial cathode material. However, the volume of the tin dioxide-based material is greatly changed in the charging and discharging processes, so that the cycle performance and the reversible capacity of the tin dioxide-based material are reduced. At present, in order to improve the electrochemical performance of tin dioxide-based materials, nanometer-scale tin dioxide particles are mainly loaded in carbon-based materials. Although the method can relieve the volume change of the tin dioxide-based composite material in the charging and discharging process to a certain extent, the problems that the electrode material keeps stable cycle performance and high discharge capacity under high-rate charging and discharging cannot be solved.

The invention provides a simple method for preparing an ultrathin carbon-coated tin dioxide nano composite material, the thickness of a carbon coating layer is about 1.7nm, wherein tin dioxide nano particles coated by an ultrathin carbon layer are confined on a submicron carbon sphere substrate, and the ultrathin carbon-coated tin dioxide nano composite material used as a lithium ion negative electrode material shows excellent rate capability, good cycle stability and high specific discharge capacity. The preparation method has the advantages of simple preparation process, low energy consumption, low preparation cost, large-scale production and no environmental pollution, and is expected to be commercially applied.

Disclosure of Invention

The invention provides a simple preparation method of an ultrathin carbon-coated tin dioxide nano negative electrode material, aiming at the problems of the existing tin dioxide-based negative electrode material.

The invention is realized by the following steps:

weighing a carbon source and a tin source according to the mol ratio of 1: 0.0018-0.018, and dissolving the carbon source and the tin source in 60mL of deionized water, wherein the carbon source is glucose or sucrose, and the tin source is stannic chloride, stannous chloride or stannous sulfate. And after the tin source and the carbon source are completely dissolved, adding a proper amount of additive naphthalene, adding a proper amount of hydrochloric acid to adjust the pH value of the mixed solution, stirring for 30min, putting the mixed solution into a kettle, and placing the kettle in an air-blowing drying oven at 120-180 ℃ for hydrothermal reaction, wherein the reaction time is controlled to be 3-12 h. Centrifugally cleaning a product after the hydrothermal reaction, and drying the product in a blast drying oven; and then placing the product in a tubular furnace, and carrying out heat treatment in a nitrogen atmosphere at the heating rate of 2-8 ℃/min, the heat treatment temperature of 400-.

Compared with other synthesis methods, the preparation method of the ultrathin carbon-coated tin dioxide nanocomposite provided by the invention has the advantages of simple preparation process, low energy consumption, low preparation cost, large-scale production and no environmental pollution, and the prepared composite material as a lithium ion cathode material shows excellent rate capability, good cycling stability and high specific discharge capacity. The method is mainly characterized in that tin dioxide nanoparticles coated by the ultrathin carbon layer in the prepared composite material are confined on a submicron carbon sphere substrate, the volume change of the tin dioxide particles in the charge and discharge process is effectively relieved in the long-cycle charge and discharge process, the structural stability of the composite material is ensured, and meanwhile, the diffusion distance of lithium ions and electrons is shortened by the ultrathin carbon layer, so that the multiplying power performance of the composite material in large-current charge and discharge is improved. The preparation method has the advantages of simple preparation process, low energy consumption, low preparation cost, large-scale production and no environmental pollution, and is expected to be commercially applied.

Drawings

FIG. 1 is an X-ray diffraction (XRD) pattern of the prepared ultra-thin carbon-coated tin dioxide nanocomposite;

FIG. 2 is a high power transmission electron microscope (HR-TEM) image of the prepared ultra-thin carbon-coated tin dioxide nanocomposite;

FIG. 3 shows that the ultra-thin carbon-coated tin dioxide nanocomposite material prepared in the step 1A g^-1A high current density cyclic charge-discharge diagram;

FIG. 4 shows that the prepared ultrathin carbon-coated tin dioxide nanocomposite material is 5A g^-1A high current density cyclic charge-discharge diagram;

fig. 5 is a graph of the rate capability of the ultra-thin carbon-coated tin dioxide nanocomposite prepared in the process.

Detailed Description

The preparation method of the ultrathin carbon-coated tin dioxide nano composite material comprises the following specific steps:

0.018mol of stannic chloride, 1mol of glucose and 3mg of naphthalene are weighed and dissolved in 60mL of deionized water, then 0.8mL of hydrochloric acid is added, magnetic stirring is carried out for 30min, the obtained mixed solution is put into a kettle and is placed in an air-blowing drying oven for hydrothermal reaction at 180 ℃, and the reaction time is controlled to be 12 h. And centrifugally cleaning a product after the hydrothermal reaction, and drying the product in a blast drying oven.

And then placing a product obtained by the hydrothermal reaction in a tubular furnace, carrying out heat treatment in a nitrogen atmosphere, heating to 500 ℃ at the heating rate of 5 ℃/min, and keeping the temperature for 4 hours, thereby obtaining the ultrathin carbon-coated tin dioxide nanocomposite.

The research result of the ultrathin carbon-coated tin dioxide nano composite material is as follows:

(1) structural analysis of materials

XRD characterization shows that the diffraction peak of the prepared composite material is completely consistent with that of standard card PDF #41-1445 (shown in attached figure 1), which indicates that the tin dioxide in the prepared composite material is a typical rutile phase and is calculated by a Sherre formula, and the particle size of the tin dioxide is 6.9 nm.

(2) And analyzing the test result of the morphology structure.

FIG. 2 is a transmission electron microscope image of the prepared ultrathin carbon-coated tin dioxide nanocomposite. It can be seen that the tin dioxide nanoparticles are confined to a carbon sphere substrate with a diameter of about 400nm, and it can be further seen in high power transmission electron microscopy that the tin dioxide particle size is about 7nm, which is consistent with XRD data. Meanwhile, the surface of the tin dioxide nano-particles is coated with a carbon coating layer with the thickness of about 1.7 nm.

(3) Analysis of electrochemical Properties

Figures 3-4 are graphs of long cycle data for ultra-thin carbon-coated tin dioxide nanocomposites as lithium ion battery cathodes at high current density. At 1A g^-1Under the current density, after 300 cycles of charge and discharge, the capacity is still maintained at 905.4mAh g^-1. Even at 5A g^-1Under the condition of high current density, the capacity can be kept at 413.4mAh g after 1000 cycles of charge and discharge^-1. FIG. 5 is a graph of the rate capability of the ultrathin carbon-coated tin dioxide nano-anode material, which is 0.1A g^-1，0.2Ag^-1，0.5A g^-1，1A g^-1，2A g^-1，5A g^-1At a current density, the capacity was 1242.3mAh g^-1，1116.5mAh g^-1，1004.8mAh g^-1，878mAh g^-1，745.8mAh g^-1，488.7mAh g^-1. The current density returns to 0.1A g^-1When the discharge capacity is increased, the discharge capacity can still be maintained at 1093.6mAh g^-1. The ultra-thin carbon-coated tin dioxide nano composite material shows excellent electrochemical performance mainly due to the fact that tin dioxide nano particles coated by the ultra-thin carbon layer in the prepared composite material are limited on a submicron carbon sphere substrate, volume change of the tin dioxide particles in the charging and discharging process is effectively relieved in the long-cycle charging and discharging process, structural stability of the composite material is guaranteed, meanwhile, the ultra-thin carbon layer shortens the diffusion distance of lithium ions and electrons, and therefore the rate performance of the composite material in large-current charging and discharging is improved.

The ultrathin carbon-coated tin dioxide nanocomposite is prepared by adopting glucose with low cost as a carbon source, the thickness of a carbon coating layer is about 1.7nm, the ultrathin carbon-coated tin dioxide nanocomposite is used as a lithium ion negative electrode material and has excellent rate performance, good cycling stability and high discharge specific capacity, the preparation process is simple, the energy consumption is low, the preparation cost is low, the repeatability is high, no pollution is caused to the environment, and the ultrathin carbon-coated tin dioxide nanocomposite is expected to be applied in commercialization.