CN108987719B - Three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material and preparation method thereof - Google Patents

Abstract

The invention provides a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material and a preparation method thereof, and relates to the field of batteries. The preparation method includes: (1) preparing three-dimensional sulfur-doped porous carbon. (2) Mix and dissolve sulfur-doped porous carbon and tin chloride in a mass ratio of 1:0.2-5, assist ultrasonic for 0.5-2 h, transfer the mixed solution to a reaction kettle, and solvothermally heat it at 150-220° C. The temperature is kept for 1 to 10 hours, and a composite electrode material with a mass ratio of tin dioxide of 5% to 60% is obtained. The specific capacitance, power density, energy density, rate capability, cycle stability and other properties of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material prepared by this method have been greatly improved and improved. The electrode material is simple and easy to operate, can be used as an electrode material for a battery pack of a new energy electric vehicle, and promotes the development of a new energy vehicle.

Description

A three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material and its preparation method

technical field

The invention relates to the field of batteries, in particular to a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material and a preparation method thereof.

Background technique

As a new type of rechargeable power source, lithium-ion batteries have the advantages of high operating voltage, high energy density, low self-discharge rate, safety and no pollution, and have been widely used in portable electronic devices such as mobile phones and notebook computers. At present, the commercial anode materials for lithium-ion batteries are mainly graphite/carbon materials, which have high electrical conductivity, but their theoretical specific capacity is low and rate performance is poor, which restricts their application in next-generation lithium-ion batteries. Metal oxides have high theoretical specific capacity, but their electrical conductivity is poor, and they tend to agglomerate during the reaction process, resulting in poor cycle stability and low capacity retention.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material and a preparation method thereof. The electrode composite material has large specific capacity, good rate performance, high energy density and excellent energy storage performance, and can be used for New energy vehicle battery pack electrode materials to promote the development of new energy vehicles.

In order to realize the above-mentioned purpose of the present invention, the following technical solutions are specially adopted:

In a first aspect, the present invention provides a method for preparing a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material, comprising:

The sulfur-doped porous carbon and tin dichloride are mixed and dissolved in a mass ratio of 1:0.2-5, and the temperature is kept at 150-220° C. for 1-10 hours by a solvothermal method.

Further, in a preferred embodiment of the present invention, in the above-mentioned solvothermal process, the heating rate is 1-5°C/min.

Further, in a preferred embodiment of the present invention, the doping amount of sulfur atoms in the above-mentioned sulfur-doped porous carbon is 1-30%.

Further, in a preferred embodiment of the present invention, the above-mentioned sulfur-doped porous carbon is prepared by mixing a carbon source with sulfate, and carbonizing at 450-800° C. for 0.5-3 hours under an inert atmosphere.

Further, in a preferred embodiment of the present invention, the mass ratio of the carbon source to the sulfate is 1:0.5-6.

Further, in a preferred embodiment of the present invention, the above-mentioned carbon source is selected from at least one of oil slurry, pitch, sucrose, glucose, cellulose and starch. Further, in a preferred embodiment of the present invention, the above-mentioned sulfur source is selected from at least one of magnesium sulfate, sodium sulfate, aluminum sulfate, sodium bisulfate, calcium sulfate and zinc sulfate. Further, in a preferred embodiment of the present invention, the heating rate in the above-mentioned process of preparing the sulfur-doped porous carbon is 2˜10° C./min.

Further, in a preferred embodiment of the present invention, after the thermal insulation carbonization, the steps of acid washing and water washing of the obtained carbonized product are also included.

In a second aspect, the present invention provides a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material prepared by the above preparation method, the percentage content of sulfur atoms is 1-30%, and the lithium ion storage capacity is 1000-3000mAh/g , the energy density is 150 ~ 350wh/kg. Compared with the prior art, the beneficial effects of the present invention include:

The preparation method of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material provided by the present invention uses sulfur-doped carbon as a carrier, and the transition metal tin is introduced into the carbon nano-layers and pores by a solvothermal method, so that the Uniformly and tightly combined with the carbon carrier, a sulfur-doped carbon/tin dioxide nanocomposite is obtained, which can be used as an electrode material. By optimizing the reaction parameters in the preparation method, the effective regulation of the morphology, size and dispersion of tin dioxide is achieved, which is beneficial to further exert the synergistic effect of sulfur-doped carbon and tin dioxide.

The inventor's research found that compared with undoped carbon, sulfur atom doping can significantly affect the chemical environment of the carbon structure, including surface polarity and electronic state, thereby promoting the electrochemical process of carbon-based, enhancing electrochemical performance, and improving The storage capacity of lithium ions.

Compared with the existing electrode materials, the specific capacitance, power density, energy density, rate capability, cycle stability and other properties of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material prepared by this method are greatly improved. and raise.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are required in the description of the embodiments or the prior art.

1 is a transmission electron microscope image of the three-dimensional sulfur-doped porous carbon provided in Example 1.

FIG. 2 is a transmission electron microscope image of the three-dimensional sulfur-doped porous carbon/tin dioxide provided in Example 2. FIG.

FIG. 3 is a transmission electron microscope image of the three-dimensional sulfur-doped porous carbon/tin dioxide provided in Example 3. FIG.

FIG. 4 is an X-ray photoelectron spectrum diagram of the three-dimensional sulfur-doped porous carbon/tin dioxide composite material provided in Example 3. FIG.

FIG. 5 is a transmission electron microscope image of the three-dimensional sulfur-doped porous carbon/tin dioxide provided in Example 4. FIG.

FIG. 6 is a rate performance diagram of the three-dimensional sulfur-doped porous carbon/tin dioxide provided in Example 4. FIG.

FIG. 7 is a charge-discharge curve diagram of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material provided in Example 4. FIG.

FIG. 8 is a power density-energy density curve diagram of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material of Example 4. FIG.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

This embodiment provides a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material, and a preparation method thereof includes:

The sulfur-doped porous carbon and tin dichloride are mixed and dissolved in a mass ratio of 1:0.2-5, and the temperature is kept at 150-220° C. for 1-10 hours by a solvothermal method.

Further, in the process of adopting the solvothermal method, the heating rate is 1-5°C/min, or 1.5-2.5°C/min, or 1.8-2.2°C/min.

Wherein, the doping amount of sulfur atoms in the sulfur-doped porous carbon is 0.1-30%, or 3-22%, or 5-20%, or 7-18%, or 9-16%, or 11% ~14%.

The preparation method of the sulfur-doped porous carbon is as follows:

It is prepared by mixing carbon source and sulfate, and carbonizing for 0.5-3 hours at 450-800 DEG C under inert gas.

Through this method, sulfur-doped carbon can be prepared in a controllable manner, and the doping modification of carbon materials can be realized, and then its electron holes can be effectively adjusted, the energy gap can be widened, and more topological defects can be induced. The lower voltage platform has more excellent electrochemical performance.

In this method, the carbon source is oil slurry, pitch, sucrose, glucose, cellulose and starch; sulfate is used as the sulfur source and template precursor, including but not limited to magnesium sulfate, sodium sulfate, aluminum sulfate, sodium bisulfate, sulfuric acid Calcium and zinc sulfate, more preferably, the template agent is magnesium sulfate.

Preferably, the mass ratio of carbon source to sulfate is 1:0.5-6, or 1:0.7-5; or 1:0.8-4; or 1:0.9-3; or 1:1.1.

More preferably, the preparation method of the sulfur-doped porous carbon further includes the steps of acid washing and water washing on the obtained carbonized product to remove the template agent and obtain pure sulfur-doped porous carbon. More preferably, citric acid solution is used for pickling.

More preferably, the heating rate in the process of preparing the sulfur-doped porous carbon is 2-10°C/min, or 3-8°C/min, or 5-7°C/min. The temperature program is adopted and the temperature program is strictly controlled, so that the carbonized substrate is slowly carbonized during the heating process, which is beneficial to further improve the performance of sulfur-doped carbon.

The features and performance of the present invention are described in further detail below in conjunction with the embodiments:

Example 1

This embodiment provides a three-dimensional sulfur-doped porous carbon material, and the preparation method includes:

The oil slurry and magnesium sulfate were mixed and stirred at a mass ratio of 1:3 until uniform, the mixture was transferred to a horizontal tube furnace, argon was introduced as a protective atmosphere, and the temperature was raised to 700°C at a heating rate of 5°C/min. After 1 h, a three-dimensional sulfur-doped porous carbon material was obtained, and its TEM photo is shown in Fig. 1. This method does not require template precursor, and obtains a three-dimensional sulfur-doped porous carbon material containing a porous structure in one step, and the method is simple.

Example 2

This embodiment provides a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material, and the preparation method includes:

The sulfur-doped porous carbon prepared in Example 1 was mixed with tin dichloride in a mass ratio of 1:1 and dissolved in water, the solution was transferred to an autoclave, the autoclave was placed in an oven, and the oven was allowed to dissolve. The temperature was raised to 150°C at a heating rate of 1°C/min and kept for 10h.

After cooling to room temperature, washing and drying are performed to obtain a three-dimensional sulfur-doped porous carbon/tin dioxide composite material. The particle size of the three-dimensional sulfur-doped porous carbon/tin dioxide composite material obtained by this method is 3-5 nm, the loading is 45%, and the distribution is uniform.

Example 3

This embodiment provides a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material, and the preparation method includes:

A. Mix sucrose and magnesium sulfate, heat up to 450°C at a heating rate of 2°C/min under an inert gas, keep carbonized for 0.5h, wash with citric acid solution, and then wash with water to obtain sulfur-doped porous carbon.

B. Mix sulfur-doped porous carbon and tin dichloride in a mass ratio of 1:5 and dissolve in water, transfer this solution to an autoclave, put the autoclave into an oven and set the oven to 5°C/ The heating rate of min was heated to 220 °C and kept for 1 h.

C. After cooling to room temperature, washing and drying to obtain a three-dimensional sulfur-doped porous carbon/tin dioxide composite material.

The TEM image of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material provided in this example is shown in FIG. 3 , from which it can be clearly seen that the tin dioxide nanoparticles are uniformly dispersed in the sulfur-doped porous carbon surface and inside the pores. The mass percentage of tin dioxide loading is 85%. FIG. 4 is the corresponding X-ray photoelectron spectrum. It can be seen from the figure that the content of S is 8.1%, and the atomic content of Sn is 15.4%. It is proved that S is bonded into carbon materials in the form of compound bonds, and SnO ₂ is successfully incorporated into the pores and surfaces of porous carbon.

Example 4

This embodiment provides a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material, and the preparation method includes:

A. Mix sucrose and magnesium sulfate, heat up at 600°C at a heating rate of 2°C/min under an inert gas, keep carbonized for 2 hours, wash with citric acid solution, and then wash with water to obtain sulfur-doped porous carbon.

B. Mix sulfur-doped porous carbon and tin dichloride in a mass ratio of 1:2 and dissolve in water, transfer this solution to an autoclave, put the autoclave into an oven and make the oven run at 2°C/ The temperature was increased to 200 °C at a heating rate of min, and the temperature was kept for 5 h.

C. After cooling to room temperature, washing and drying to obtain a three-dimensional sulfur-doped porous carbon/tin dioxide composite material.

The TEM image of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material provided in this embodiment is shown in FIG. 5 , from which it can be clearly seen that the tin dioxide nanoparticles are uniformly dispersed in the sulfur-doped porous carbon surface and inside the pores. The mass percentage of tin dioxide loading is 65%.

The sulfur-doped porous carbon/tin dioxide composite electrode material prepared by this method has a high lithium storage capacity, and Figure 6 is a rate performance diagram. The capacity of the sulfur-doped porous carbon/tin dioxide composite electrode material is 1490mAh/g when the current density is 200mA/g, and the capacity can still be maintained at 800mAh/g when the current density is 1600mA/g. The lithium storage capacity of the sulfur-doped porous carbon is 1305 mAh/g at a current density of 200 mA/g, and the capacity can still be maintained at 580 mAh/g at a current density of 1600 mA/g. It can be seen from Figure 6 that the sulfur-doped porous carbon/tin dioxide composite electrode material has higher lithium storage capacity and excellent electrochemical performance.

The charge-discharge curve of the sulfur-doped porous carbon/tin dioxide composite electrode material is shown in FIG. 7 , and it can be seen from the figure that the material has good cycle performance.

The power density-energy density curve of the sulfur-doped porous carbon/tin dioxide composite electrode material is shown in Figure 8. It can be seen from the figure that the energy density can reach 341Wh/Kg when the current density is 0.2C, and the sulfur-doped porous carbon /SnO2 composite electrode material has higher energy density and power density. It can be applied to new energy electric vehicles, paving the way for the development of new energy power batteries.

Although specific embodiments of the present invention have been illustrated and described, it should be understood that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications as fall within the scope of this invention be included in the appended claims.

Claims (7)

1. A preparation method of a three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material is characterized by comprising the following steps:

mixing sulfur-doped porous carbon and tin dichloride in a mass ratio of 1: 0.2-5, mixing and dissolving, and preserving heat for 1-10 hours at 150-220 ℃ by adopting a solvothermal method;

in the process of adopting the solvothermal method, the heating rate is 1-5 ℃/min, and the mass fraction of sulfur atoms in the sulfur-doped porous carbon is 1-30%;

the sulfur-doped porous carbon is prepared by mixing a carbon source and a sulfur source, and carrying out heat preservation and carbonization for 0.5-3 h at 450-800 ℃ under inert gas.

2. The preparation method of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material according to claim 1, wherein the mass ratio of the carbon source to the sulfur source is 1: 0.5 to 6.

3. The method for preparing the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material according to claim 2, wherein the carbon source is at least one selected from oil slurry, asphalt, sucrose, glucose, cellulose and starch.

4. The method for preparing the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material according to claim 2, wherein the sulfur source is selected from at least one of magnesium sulfate, sodium sulfate, aluminum sulfate, sodium bisulfate, calcium sulfate and zinc sulfate.

5. The preparation method of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material according to claim 1, wherein the temperature rise rate in the process of preparing the sulfur-doped porous carbon is 2-10 ℃/min.

6. The preparation method of the three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material according to claim 1, further comprising the steps of acid washing and water washing of the obtained carbonized product after the heat preservation carbonization.

7. The three-dimensional sulfur-doped porous carbon/tin dioxide composite electrode material prepared by the preparation method disclosed by any one of claims 1-6 is characterized in that the mass fraction of sulfur atoms is 1-30%, the lithium ion storage capacity is 1000-3000mAh/g, and the energy density is 150-350 wh/kg.

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