A core-shell structure iron tin oxide coated white carbon black lithium ion battery negative electrode material and a preparation method thereof

Abstract

The application discloses a preparation method of a core-shell structure iron tin oxide coated white carbon black lithium ion battery negative electrode material, and belongs to the field of energy storage materials. In view of the problem of poor lithium storage performance and cycle stability of the commonly used negative electrode material of a lithium ion battery in the prior art, in the technical scheme of the application, white carbon black is used as an inner core, a layer of Fe / Sn-MOF is grown on the surface of the white carbon black through plasma, and finally, the Fe / SnO2@SiO2 core-shell structure composite material is obtained by calcining at a certain temperature. The application has the advantages of simple process and convenient operation, the shell of the prepared silicon-based negative electrode material is iron tin oxide which is stable in structure during the process of deintercalating lithium, the inner core is silicon which can provide high specific capacity, and there is a cavity between the core and the shell which can buffer the volume effect during the process of deintercalating lithium, so that the silicon-based negative electrode material has good lithium storage performance and cycle stability.

Description

Technical Field

[0001] This invention relates to a core-shell structured iron-tin oxide coated silica lithium-ion battery anode material and its preparation method, belonging to the field of energy storage materials. Background Technology

[0002] Lithium-ion batteries have attracted widespread attention due to their advantages such as ease of use, low environmental pollution, lack of geographical limitations, high conversion efficiency, and high specific energy and specific power. With the rapid development of electronic devices and electric vehicles, higher performance requirements are being placed on lithium-ion batteries.

[0003] Graphite is a commonly used anode material in commercial lithium-ion batteries, but its theoretical specific capacity is only 372 mAh / g, which cannot meet the energy density requirements of the new energy industry and the new energy vehicle industry for energy storage devices. Compared to traditional graphite anodes, silicon can react with lithium at room temperature to form Li0... 15 Si4 alloys have a theoretical capacity of up to 3590 mAh / g, which is nearly ten times the theoretical specific capacity of graphite. Studies have shown that silica anode materials readily generate an electrochemically irreversible Li2O phase during lithium intercalation, providing a buffering effect. Furthermore, silica materials contain strong Si-O bonds, twice the strength of Si-Si bonds, resulting in a smaller volume effect during charge and discharge. In conclusion, silica has attracted significant attention due to its unique microstructure and high capacity (>1400 mAh / g). Summary of the Invention

[0004] To address the problem of poor lithium storage performance and cycle stability of commonly used lithium-ion battery anode materials in existing technologies, a core-shell structured iron-tin oxide coated silica lithium-ion battery anode material and its preparation method are proposed.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is a method for preparing a core-shell structured iron-tin oxide coated silica lithium-ion battery anode material, comprising the following steps:

[0006] 1) Add polyethylene terephthalate plastic granules to ethanol and mix well to obtain mixture A;

[0007] 2) Add ferric chloride and tin chloride to deionized water and mix well to obtain mixture B;

[0008] 3) Mix and stir the obtained mixture A and mixture B to obtain a mixed solution;

[0009] 4) Add silica to the mixed solution and sonicate until evenly dispersed to obtain mixture C;

[0010] 5) The mixture C is passed into a plasma reactor and reacted by discharge through the plasma reactor; after the discharge reaction, it is separated by centrifugation, then washed and dried to obtain solid product D;

[0011] 6) The solid product D is heat-treated to obtain a core-shell structured iron-tin oxide coated silica lithium-ion battery anode material.

[0012] In the optimized preparation method of the above-mentioned core-shell structure iron-tin oxide coated silica lithium-ion battery anode material, in step 1), the mass ratio of polyethylene terephthalate plastic particles to ethanol is 1:16.5, and the mass ratio of polyethylene terephthalate plastic particles to ferric chloride is 1:0.79.

[0013] In step 2), the molar ratio of ferric chloride to tin chloride is 1:1, and the concentration of mixture B is 0.0175 g / mL;

[0014] In step 4), the mass ratio of silica to ferric chloride is 1:1.09.

[0015] In the optimized preparation method of the above-mentioned core-shell structure iron-tin oxide coated silica lithium-ion battery anode material, in steps 1) and 2), the concentration of ethanol is 99.7%; and in steps 1) and 2, the volume ratio of ethanol to aqueous solution is 1:4.

[0016] In the optimized preparation method of the above-mentioned core-shell structure iron-tin oxide coated silica lithium-ion battery anode material, in step 4), when ultrasonication is performed until the dispersion is uniform, the ultrasonication temperature is room temperature and the ultrasonication time is 0.5 to 2 hours.

[0017] In the optimized preparation method of the above-mentioned core-shell structure iron-tin oxide coated silica lithium-ion battery anode material, in step 5), the discharge time for the reaction by discharging through the plasma reaction device is 1 to 2 hours, and the discharge voltage is 7 to 9 kV.

[0018] The optimized preparation method of the above-mentioned core-shell structured iron-tin oxide coated silica lithium-ion battery anode material is as follows:

[0019] In step 6), the solid product D is heat-treated at a temperature of 400–700°C for 0.5–24 h to obtain the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material.

[0020] In the optimized preparation method of the above-mentioned core-shell structure iron-tin oxide coated silica lithium-ion battery anode material, the heat treatment in step 6) is carried out under a nitrogen or air atmosphere.

[0021] A core-shell structured iron-tin oxide-coated silica lithium-ion battery anode material is prepared using the method described above. The outer shell is iron-tin oxide, the core is silica, and a cavity exists between the outer shell and the core.

[0022] The beneficial effects of this application are as follows:

[0023] The present invention relates to the preparation of a core-shell structured iron-tin oxide-coated silica lithium-ion battery anode material. This material uses polyethylene terephthalate (PET) plastic particles as the organic ligand source and ferric chloride and tin chloride as metal salts. Silica is coated with an iron-tin bimetallic organic framework material via plasma methods. Subsequently, it is calcined under a specific temperature and atmosphere. The metal-organic framework collapses, generating porous iron-tin bimetallic oxides, while simultaneously producing gas. This causes the iron-tin bimetallic oxides to coat the silica surface, creating a cavity structure of a certain volume.

[0024] Compared with existing core-shell structured silicon-based composite materials, the preparation method of this application is simple and effective, featuring low reaction temperature, simple process, high efficiency, and industrial-scale production capability. The silica used in this invention is fumed silica, which is inexpensive, has small particle size, high purity, good dispersibility, and porosity, resulting in silica anode materials with advantages such as small particle size and large specific surface area. A precursor for the target structure product can be obtained through a one-step plasma reaction, and subsequent heat treatment steps can further regulate the lithium storage performance of the product. The final product obtained according to the preparation method of this invention has a porous iron-tin oxide shell, exhibiting a stable structure during lithium insertion / extraction; the internal core is silica, providing high specific capacity; and a certain cavity volume between the core and shell buffers the volume effect during silicon lithium insertion / extraction, thus giving the anode material excellent electrochemical performance. Attached Figure Description

[0025] Figure 1 TEM image of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material of this application;

[0026] Figure 2 XRD pattern of the core-shell structure iron-tin oxide coated silica lithium-ion battery anode material of this application;

[0027] Figure 3 Cyclic performance diagram of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material prepared in Example 4. Detailed Implementation

[0028] This application provides a method for preparing a core-shell structured iron-tin oxide coated silica lithium-ion battery anode material, comprising the following steps:

[0029] 1) Add polyethylene terephthalate plastic granules to ethanol and mix well to obtain mixture A;

[0030] 2) Add ferric chloride and tin chloride to deionized water and mix well to obtain mixture B;

[0031] 3) Mix and stir the obtained mixture A and mixture B to obtain a mixed solution;

[0032] 4) Add silica to the mixed solution and sonicate until evenly dispersed to obtain mixture C;

[0033] 5) The mixture C is passed into a plasma reactor and reacted by discharge through the plasma reactor; after the discharge reaction, it is separated by centrifugation, then washed and dried to obtain solid product D;

[0034] 6) The solid product D is heat-treated to obtain a core-shell structured iron-tin oxide coated silica lithium-ion battery anode material.

[0035] In step 1), the mass ratio of polyethylene terephthalate plastic particles to ethanol is 1:16.5, the mass ratio of polyethylene terephthalate plastic particles to ferric chloride is 1:0.79, and the concentration of ethanol is 99.7%.

[0036] In step 2), the molar ratio of ferric chloride to tin chloride is 1:1, and the concentration of mixture B is 0.0175 g / mL;

[0037] In step 4), the weight ratio of silica to ferric chloride is 1:1.09.

[0038] In steps 1) and 2), the volume ratio of ethanol to aqueous solution is 1:4.

[0039] In step 4), when the ultrasonication is performed until the dispersion is uniform, the ultrasonication temperature is room temperature and the ultrasonication time is 0.5 hours.

[0040] In step 5), the discharge time for the reaction via the plasma reaction device is 1 hour, and the discharge voltage is 7 kV.

[0041] In step 6), the solid product D is heat-treated at a temperature of 400-700°C for 0.5 hours to obtain the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material.

[0042] In step 6), the heat treatment is carried out under a nitrogen atmosphere.

[0043] This application also includes a core-shell structured iron-tin oxide-coated silica lithium-ion battery anode material, prepared using the above-described preparation method. The outer shell of the core-shell structured iron-tin oxide-coated silica lithium-ion battery anode material is iron-tin oxide, the core is silica, and a cavity exists between the outer shell and the core.

[0044] Example 2

[0045] The difference between this embodiment and embodiment 1 is that in step 4), when the ultrasonication is performed until the dispersion is uniform, the ultrasonication temperature is room temperature and the ultrasonication time is 2 hours.

[0046] In step 5), the discharge time for the reaction via the plasma reaction device is 2 hours, and the discharge voltage is 9 kV.

[0047] In step 6), the solid product D is heat-treated at 700°C for 24 hours to obtain the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material.

[0048] In step 6), the heat treatment is carried out in an air atmosphere.

[0049] Example 3

[0050] The difference between this embodiment and embodiment 1 is that in step 4), when the ultrasonication is performed until the dispersion is uniform, the ultrasonication temperature is room temperature and the ultrasonication time is 1.5 hours.

[0051] In step 5), the discharge time for the reaction via the plasma reaction device is 1.5 hours, and the discharge voltage is 8 kV.

[0052] In step 6), the solid product D is heat-treated at 600°C for 18 hours.

[0053] In step 6), the heat treatment is carried out under a nitrogen atmosphere.

[0054] Example 4

[0055] The difference between this embodiment and the previous embodiments is that:

[0056] Add 1.92g of polyethylene terephthalate plastic granules to 40mL of ethanol, and add 1.52g of ferric chloride and 1.28g of tin chloride to 160mL of aqueous solution. Stir each separately until well mixed, then mix them together.

[0057] Add 1.4g of silica to the above mixed solution and sonicate for 40 minutes until evenly dispersed to obtain the mixture;

[0058] The mixture was passed into a plasma reactor and discharged at a voltage of 7.8 kV for 2 hours. Then, it was centrifuged, the resulting solid product was washed, and dried in an oven at 60°C for 24 hours.

[0059] The dried solid product was heat-treated at 400°C in a nitrogen atmosphere for 2 hours, and then cooled to room temperature to obtain the final product.

[0060] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A method for preparing a core-shell structured iron-tin oxide-coated silica lithium-ion battery anode material, characterized in that: Includes the following steps: 1) Add polyethylene terephthalate plastic granules to ethanol and mix well to obtain mixture A; 2) Add ferric chloride and tin chloride to deionized water and mix well to obtain mixture B; 3) Mix and stir the obtained mixture A and mixture B to obtain a mixed solution; 4) Add silica to the mixed solution and sonicate until evenly dispersed to obtain mixture C; 5) The mixture C is passed into a plasma reactor and reacted by discharge through the plasma reactor; after the discharge reaction, it is separated by centrifugation, then washed and dried to obtain solid product D; 6) The solid product D is heat-treated to obtain a core-shell structured iron-tin oxide coated silica lithium-ion battery anode material.

2. The preparation method of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material according to claim 1, characterized in that: In step 1), the weight ratio of polyethylene terephthalate plastic particles to ethanol is 1:16.5, the mass ratio of polyethylene terephthalate plastic particles to ferric chloride is 1:0.79, and the concentration of ethanol is 99.7%. In step 2), the molar ratio of ferric chloride to tin chloride is 1:1, and the concentration of mixture B is 0.0175 g / mL; In step 4), the mass ratio of silica to ferric chloride is 1:1.

09.

3. The preparation method of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material according to claim 1, characterized in that: In steps 1) and 2), the concentration of ethanol is 99.7%; in steps 1) and 2), the volume ratio of ethanol to aqueous solution is 1:

4.

4. The preparation method of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material according to claim 1, characterized in that: In step 4), when the ultrasonic waves are sonicated until the dispersion is uniform, the ultrasonic temperature is room temperature and the ultrasonic time is 0.5 to 2 hours.

5. The preparation method of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material according to claim 4, characterized in that: In step 5), the discharge time for the reaction via the plasma reaction device is 1 to 2 hours, and the discharge voltage is 7 to 9 kilovolts.

6. The preparation method of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material according to claim 1, characterized in that: In step 6), the solid product D is heat-treated at a temperature of 400–700°C for 0.5–24 h to obtain the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material.

7. The preparation method of the core-shell structured iron-tin oxide coated silica lithium-ion battery anode material according to claim 6, characterized in that: In step 6), the heat treatment is carried out in a nitrogen or air atmosphere.

8. A core-shell structured iron-tin oxide-coated silica lithium-ion battery anode material, characterized in that: Prepared using the preparation method according to any one of claims 1 to 7.

9. The core-shell structured iron-tin oxide coated silica lithium-ion battery anode material according to claim 8, characterized in that: The outer shell is made of iron-tin oxide, the core is made of silica, and there is a cavity between the outer shell and the core.

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