Network-shaped silicon-tin disulfide-carbon negative electrode material and preparation method and application thereof

Abstract

The invention relates to the technical field of nanometer lithium battery negative electrode materials, and particularly discloses a network-shaped silicon, tin disulfide and carbon negative electrode material and a preparation method and application thereof. A preparation method of a network-shaped silicon-tin disulfide-carbon negative electrode material comprises the following steps: stirring and mixing soluble organic silicon, sodium hydroxide and deionized water, then adding ethanol, stirring and mixing to obtain a reaction solution, and post-treating the reaction solution to obtain three-dimensional aerogel network-shaped silicon dioxide; calcining the three-dimensional aerogel network-shaped silicon dioxide and a reducing agent to obtain network-shaped silicon; the preparation method comprises the following steps: mixing network-shaped silicon, tin salt and oleylamine, firstly adding mercaptan, and then stirring and mixing at 180-200 DEG C to obtain a reaction solution; and carrying out post-treatment on the reaction liquid to obtain the network-shaped silicon-tin disulfide-carbon negative electrode material. The network-shaped silicon is subjected to double-layer coating, so that the inner core can be protected from external chemical erosion, the reaction active sites are improved, the silicon content is reduced, and the electrochemical performance of the material is improved.

Description

Technical Field

[0001] This application relates to the technical field of nano lithium-ion battery anode materials. More specifically, it relates to a network-like silicon@tin disulfide@carbon anode material and its preparation method and application. Background Art

[0002] In order to meet the development of industry, it is necessary to vigorously develop energy storage devices. As one of the mainstream energy storage devices, lithium-ion batteries have received extensive attention in society. Due to the low theoretical capacity (372 mAh / g) of traditional graphite anodes, they can no longer meet the development of current electric vehicles or smart grids. Therefore, higher-capacity electrode materials are needed to achieve batteries with higher energy density.

[0003] Silicon is currently the anode material with the highest known capacity (4200 mAh / g). It has a relatively low lithium deintercalation potential and is relatively abundant in source. It is one of the best anode materials for developing high-energy-density batteries at present.

[0004] However, although silicon has a high theoretical capacity, it will undergo a huge volume change (>300%) during the charge and discharge process. This change will cause the destruction of the material structure and particle pulverization, and then lead to rapid attenuation of the electrode capacity and electrode failure. Summary of the Invention

[0005] In order to improve the stability of silicon materials during the charge and discharge process, this application provides a network-like silicon@tin disulfide@carbon anode material and its preparation method and application.

[0006] In the first aspect, this application provides a preparation method for a network-like silicon@tin disulfide@carbon anode material, adopting the following technical solution: A preparation method for a network-like silicon@tin disulfide@carbon anode material, comprising the following steps: (1) Add 4 - 8 g of soluble organosilicon and 0.6 - 1.0 g of sodium hydroxide to 60 - 80 mL of deionized water, stir and mix for 80 - 150 min to obtain a mixed solution; after introducing an inert gas into the mixed solution, add 80 - 100 μL of ethanol and stir and mix for 15 - 20 min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid, and wash it to obtain three-dimensional aerogel network-like silica; (2) Under an inert atmosphere condition, calcine the three-dimensional aerogel network-like silica obtained in step (1) and a reducing agent at a heating rate of 0.5 - 1.0 °C / min from 25 °C to 700 - 900 °C for 3 - 6 h to obtain network-like silicon; (3) Add the network-like silicon and tin salt obtained in step (2) to oleylamine, stir and mix to obtain a mixture; after introducing an inert gas into the mixture, stir and mix at 120-150 °C for 20-30 min to obtain a mixed solution; add thiol to the mixed solution, stir and mix for 30-60 min, and then stir and mix at 180-200 °C for 20-30 min to obtain a reaction solution; naturally cool the reaction solution, filter, collect the solid, wash it to obtain a network-like silicon@tin disulfide@carbon anode material.

[0007] By adopting the above technical solution, a certain amount of soluble organosilicon is first hydrolyzed under alkaline conditions to obtain three-dimensional aerogel network-like silica, and then high-temperature reduction is carried out under specific temperature conditions. The obtained network-like silicon has a large specific surface area and can be in full contact with the electrolyte, which is beneficial to improving the electrochemical performance of the anode material.

[0008] At the same time, after mixing network-like silicon, tin salt and oleylamine and heating to form a prepolymer, by controlling the reaction temperature with thiol, the generated tin disulfide and carbon can be successively coated on the surface of the network-like silicon to obtain a double-layer coated network-like silicon@tin disulfide@carbon anode material. On the one hand, the network-like silicon has a large specific surface area, increasing the contact area with the electrolyte, increasing the reaction sites, and improving the electrochemical performance of the anode material; the coated tin disulfide and carbon can not only increase the conductivity of the anode material, but also form a unique closed microenvironment to protect the inner core from external chemical erosion, which is beneficial to improving the electrochemical performance of the anode material; on the other hand, the double-layer coating can reduce the silicon content in the anode material, enabling the anode material to have a reasonable volume expansion range.

[0009] Therefore, the network-like silicon@tin disulfide@carbon anode material prepared by the preparation method of the present application has both high specific capacity and cycle stability, has good electrochemical performance and broad commercial prospects.

[0010] Preferably, in the step (1), the soluble organosilicon includes one or both of tetraethyl orthosilicate and tetrabutyl orthosilicate.

[0011] By adopting the above technical solution, tetraethyl orthosilicate and tetrabutyl orthosilicate have high reaction activities and can be rapidly hydrolyzed in an alkaline environment to obtain three-dimensional aerogel network-like silica with a high specific surface area, which is beneficial to increasing.

[0012] Preferably, in the step (2), the reducing agent is one or more of magnesium powder, aluminum powder and boron.

[0013] By adopting the above technical solution, magnesium powder, aluminum powder and boron have the advantages of strong reduction ability, high reaction activity and mild reaction conditions, etc. They can reduce three-dimensional aerogel network silica into network silicon within a relatively low temperature range, which is beneficial to improving the yield of network silicon and the safety of the reaction.

[0014] Preferably, in the step (3), the tin salt is one or more of tin acetate, tin tetrachloride and tin sulfate.

[0015] Preferably, in the step (3), the thiol is one or more of n-dodecyl mercaptan, tert-dodecyl mercaptan and 1,10-decane dithiol.

[0016] Preferably, in the step (3), the molar ratio of network silicon to tin salt is 50:1.

[0017] Preferably, in the step (3), the molar ratio of tin salt to thiol is 1:20.

[0018] In the second aspect, the present application provides a network silicon@tin disulfide@carbon anode material, adopting the following technical solution: A network silicon@tin disulfide@carbon anode material is prepared by the preparation method of the above network silicon@tin disulfide@carbon anode material.

[0019] By adopting the above technical solution, the network silicon@tin disulfide@carbon anode material has a multiple-core structure. On the one hand, it can form a special active-site closed structure to protect the core from external chemical erosion, which is beneficial to improving the electrochemical performance of the anode material. On the other hand, it can reduce the silicon content in the anode material and control the volume expansion of the anode material within a reasonable range, which is beneficial to further improving the electrochemical performance of the anode material.

[0020] In the third aspect, the present application provides an application of a network silicon@tin disulfide@carbon anode material, adopting the following technical solution: An application of a network silicon@tin disulfide@carbon anode material in a lithium-ion battery anode.

[0021] By adopting the above technical solution, the network silicon@tin disulfide@carbon anode material of the present application has both a relatively high specific capacity and cycle stability. When applied to a lithium-ion battery anode, it has broad commercial prospects.

[0022] In summary, the present application has the following beneficial effects: 1. By double-layer coating the network silicon, the present application prepares a silicon-carbon material with multiple cores. Due to the multiple-core structure having a special active-site closed structure, a unique closed microenvironment is formed, which can protect the core from external chemical erosion, thus improving the electrochemical performance of the material; 2. By controlling the dosages of soluble organosilicon and sodium hydroxide, the hydrolysis rate of organosilicon can be adjusted in this application to obtain three-dimensional aerogel network silica with uniform particle size and high specific surface area. It has many reaction sites and is easy to be coated with tin disulfide after reduction, further improving the electrochemical performance of the anode material. 3. The networked silicon@tin disulfide@carbon anode material of this application has both high specific capacity and cycle stability, has good electrochemical performance, and has broad commercial prospects in lithium-ion battery anodes. Description of the Drawings

[0023] Figure 1 It is the cycle life diagram of the networked silicon@tin disulfide@carbon anode material of Example 1; Figure 2 It is the cycle life diagram of the networked silicon@tin disulfide@carbon anode material of Example 2; Figure 3 It is the cycle life diagram of the networked silicon@tin disulfide@carbon anode material of Example 3. Detailed Description of the Embodiments

[0024] The following further elaborates on this application in detail with reference to the drawings and embodiments.

[0025] Performance Detection The networked silicon@tin disulfide@carbon anode material prepared in the embodiments of this application and the anode material prepared in the comparative example are subjected to the detection of the initial discharge specific capacity and the discharge specific capacity after 100 cycles, and the capacity retention rate is calculated.

[0026] The detection method is as follows: Constant current charge-discharge test, under the condition of a current density of 1 A / g, the charge-discharge voltage window is 0.005 - 2 V.

[0027] The calculation formula for the capacity retention rate is as follows: Capacity retention rate = (discharge specific capacity after 100 cycles / initial discharge specific capacity) × 100%. Embodiments

[0028] Example 1 A preparation method of a networked silicon@tin disulfide@carbon anode material, comprising the following steps: (1) Add 4 g of soluble tetraethyl orthosilicate and 0.6 g of sodium hydroxide to 60 ml of deionized water, stir and mix for 80 min to obtain a mixed solution; after introducing argon into the mixed solution for 20 min, then add 80 μL of ethanol and stir and mix for 15 min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it 3 times with deionized water and absolute ethanol to obtain three-dimensional aerogel network silica; (2) Under an inert atmosphere condition, 0.6 g of the three-dimensional aerogel network silica obtained in step (1) and 0.25 g of magnesium powder were heated from 25 °C to 700 °C at a heating rate of 0.5 °C / min and calcined for 6 h to obtain network silicon; (3) 0.28 g of the network silicon obtained in step (2) and 0.0472 g of tin acetate were added to 20 ml of oleylamine, and magnetic stirring was carried out to obtain a mixture; after introducing argon into the mixture for 20 min, stirring and mixing were carried out at 120 °C for 20 min to obtain a mixed solution; 1 ml of n-dodecyl mercaptan was added to the mixed solution at 120 °C, stirring and mixing were carried out for 30 min, and then stirring and mixing were carried out at 180 °C for 20 min to obtain a reaction solution; the reaction solution was naturally cooled to room temperature, filtered, the solid was collected and washed 5 times with ethanol and deionized water to obtain a network silicon@tin disulfide@carbon anode material.

[0029] Example 2 A preparation method of a network silicon@tin disulfide@carbon anode material, comprising the following steps: (1) 6 g of soluble tetraethyl orthosilicate and 0.8 g of sodium hydroxide were added to 60 ml of deionized water, and stirring and mixing were carried out for 90 min to obtain a mixed solution; after introducing argon into the mixed solution for 30 min, 100 μL of ethanol was added and stirring and mixing were carried out for 15 min to obtain a reaction solution; finally, the reaction solution was centrifuged, the solid was collected and washed 3 times with deionized water and absolute ethanol to obtain three-dimensional aerogel network silica; (2) Under an inert atmosphere condition, 0.9 g of the three-dimensional aerogel network silica obtained in step (1) and 0.16 g of boron were heated from 25 °C to 800 °C at a heating rate of 1.0 °C / min and calcined for 5 h to obtain network silicon; (3) 0.42 g of the network silicon obtained in step (2) and 0.0708 acetic acid tin were added to 20 ml of oleylamine, and magnetic stirring was carried out to obtain a mixture; after introducing argon into the mixture for 30 min, stirring and mixing were carried out at 150 °C for 30 min to obtain a mixed solution; 1.3 mL of 1,10-decanedithiol was added to the mixed solution at 150 °C, stirring and mixing were carried out for 30 min, and then stirring and mixing were carried out at 180 °C for 30 min to obtain a reaction solution; the reaction solution was naturally cooled to room temperature, filtered, the solid was collected and washed 5 times with ethanol and deionized water to obtain a network silicon@tin disulfide@carbon anode material.

[0030] Example 3 A preparation method of a network silicon@tin disulfide@carbon anode material, comprising the following steps: (1) 8 g of soluble tetrabutyl orthosilicate and 1 g of sodium hydroxide were added to 80 ml of deionized water, and the mixture was stirred for 150 min to obtain a mixed solution. After purging argon into the mixed solution for 30 min, 100 μL of ethanol was added and stirred for 15 min to obtain a reaction solution. Finally, the reaction solution was centrifuged, and the solid was collected and washed three times with deionized water and absolute ethanol to obtain three-dimensional aerogel network-like silica; (2) 1.2 g of the three-dimensional aerogel network-like silica obtained in step (1) and 0.55 g of aluminum powder were calcined at a heating rate of 1.0 °C / min from 25 °C to 900 °C for 3 h under an inert atmosphere condition to obtain network-like silicon; (3) 0.56 g of the network-like silicon obtained in step (2) and 1.042 g of tin acetate were added to 20 ml of oleylamine, and magnetic stirring was carried out to obtain a mixture. After purging argon into the mixture for 30 min, the mixture was stirred at 150 °C for 30 min to obtain a mixed solution. tert-Dodecyl mercaptan was added to the mixed solution at 150 °C, and the mixture was stirred for 60 min and then stirred at 200 °C for 30 min to obtain a reaction solution. The reaction solution was naturally cooled to room temperature, filtered, and the solid was collected and washed five times with ethanol and deionized water to obtain a network-like silicon@tin disulfide@carbon anode material.

[0031] For the network-like silicon@tin disulfide@carbon anode materials prepared in Examples 1 to 3 of this application, the initial discharge specific capacity and the discharge specific capacity after 100 cycles were detected under a current density of 1 A / g, and the detection results are shown in the following table.

[0032] By analyzing the data in the above table and combining Figures 1 to 3 It can be seen that for the network-like silicon@tin disulfide@carbon anode materials prepared in Examples 1 to 3, the initial discharge specific capacity is as high as 2336 - 2460 mAh / g, the discharge specific capacity after 100 cycles is as high as 1996 - 2182 mAh / g, and the capacity retention rate is as high as 85.4 - 89.1%. This shows that the network-like silicon@tin disulfide@carbon anode materials prepared in Examples 1 to 3 of this application have high electrochemical performance.

[0033] Comparative Example Comparative Example 1 A method for preparing an anode material includes the following steps: (1) Add 3 g of soluble tetraethyl orthosilicate and 0.5 g of sodium hydroxide to 60 ml of deionized water, stir and mix for 80 min to obtain a mixed solution; after introducing argon gas into the mixed solution for 20 min, add 80 μL of ethanol and stir and mix for 15 min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it with deionized water and absolute ethanol three times to obtain three-dimensional aerogel network silica; (2) Under an inert atmosphere condition, heat 0.6 g of the three-dimensional aerogel network silica obtained in step (1) and 0.25 g of magnesium powder from 25 °C to 600 °C at a heating rate of 0.4 °C / min and calcine for 7 h to obtain network silica; (3) Add 0.28 g of the network silica obtained in step (2) and 0.0472 g of tin acetate to 20 ml of oleylamine, carry out magnetic stirring to obtain a mixture; after introducing argon gas into the mixture for 20 min, stir and mix at 120 °C for 20 min to obtain a mixed solution; add 1 ml of n-dodecyl mercaptan to the mixed solution at 120 °C, stir and mix for 60 min, and then stir and mix at 160 °C for 40 min to obtain a reaction solution; naturally cool the reaction solution to room temperature, filter, collect the solid and wash it with ethanol and deionized water five times to obtain a network silica@tin disulfide@carbon anode material.

[0034] Comparative Example 2 A method for preparing an anode material, comprising the following steps: (1) Add 9 g of soluble tetraethyl orthosilicate and 1.2 g of sodium hydroxide to 80 ml of deionized water, stir and mix for 80 min to obtain a mixed solution; after introducing argon gas into the mixed solution for 20 min, add 80 μL of ethanol and stir and mix for 15 min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it with deionized water and absolute ethanol three times to obtain three-dimensional aerogel network silica; (2) Under an inert atmosphere condition, heat 0.6 g of the three-dimensional aerogel network silica obtained in step (1) and 0.25 g of magnesium powder from 25 °C to 950 °C at a heating rate of 1.5 °C / min and calcine for 2.5 h to obtain network silica; (3) Add 0.28 g of the network silica obtained in step (2) and 0.0472 g of tin acetate to 20 ml of oleylamine, carry out magnetic stirring to obtain a mixture; after introducing argon gas into the mixture for 20 min, stir and mix at 150 °C for 20 min to obtain a mixed solution; add 1 ml of n-dodecyl mercaptan to the mixed solution at 150 °C, stir and mix for 30 min, and then stir and mix at 200 °C for 10 min to obtain a reaction solution; naturally cool the reaction solution to room temperature, filter, collect the solid and wash it with ethanol and deionized water five times to obtain a network silica@tin disulfide@carbon anode material.

[0035] For the networked silicon@tin disulfide@carbon anode materials prepared in Comparative Examples 1-2 of this application, the initial discharge specific capacity and the discharge specific capacity after 100 cycles were detected under a current density of 1 A / g, and the detection results are shown in the following table.

[0036] By analyzing the data in the above table, it can be seen that compared with Comparative Examples 1 and 2, for the networked silicon@tin disulfide@carbon anode material prepared in Example 1, the initial discharge specific capacity was relatively increased by 9.81-12.71%, the discharge specific capacity after 100 cycles was relatively increased by 17.30-23.96%, and the capacity retention rate was relatively increased by 6.76-9.92%. This shows that in the preparation method of the networked silicon@tin disulfide@carbon anode material of this application, a certain amount of soluble organosilicon is first hydrolyzed under alkaline conditions, and then high-temperature reduction is carried out under specific temperature conditions. The obtained networked silicon has a large specific surface area, which can not only be in full contact with the electrolyte, but also facilitate the coating of tin disulfide and carbon under the specific temperature conditions in step (3), forming a unique closed microenvironment to protect the core from external chemical erosion, which is beneficial to improving the electrochemical performance of the anode material.

[0037] This specific embodiment is only an explanation of this application and does not limit this application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of this application, they are protected by the patent law.

Claims

1. A preparation method of a network-like silicon@tin disulfide@carbon anode material, characterized in that It includes the following steps: (1) After stirring and mixing 4 - 8 g of soluble organosilicon, 0.6 - 1.0 g of sodium hydroxide, and 60 - 80 mL of deionized water for 80 - 150 min, under an inert atmosphere condition, add 80 - 100 μL of ethanol and stir and mix for 15 - 20 min to obtain a reaction solution; centrifuge the reaction solution, collect the solid, and wash it to obtain three-dimensional aerogel network-like silica; (2) Under an inert atmosphere condition, heat the three-dimensional aerogel network-like silica obtained in step (1) and a reducing agent from 25 °C to 700 - 900 °C at a heating rate of 0.5 - 1.0 °C / min and calcine for 3 - 6 h to obtain network-like silicon; (3) Mix the network-like silicon obtained in step (2), a tin salt, and oleylamine, and stir and mix at 120 - 150 °C for 20 - 30 min to obtain a mixed solution; add thiol to the mixed solution, first stir and mix for 30 - 60 min, and then stir and mix at 180 - 200 °C for 20 - 30 min to obtain a reaction solution; naturally cool the reaction solution, filter it, collect the solid, and wash it to obtain a network-like silicon@tin disulfide@carbon anode material.

2. The preparation method of the network-like silicon@tin disulfide@carbon anode material according to claim 1, characterized in that, In step (1), the soluble organosilicon includes one or both of tetraethyl orthosilicate and tetrabutyl orthosilicate.

3. The preparation method of the network-shaped silicon@tin disulfide@carbon anode material according to claim 1, wherein In step (2), the reducing agent is one or more of magnesium powder, aluminum powder, and boron.

4. The preparation method of the network-shaped silicon@tin disulfide@carbon anode material according to claim 1, wherein, In step (3), the tin salt is one or more of tin acetate, tin tetrachloride, and tin sulfate.

5. The preparation method of the network-like silicon@tin disulfide@carbon anode material according to claim 1, wherein In step (3), the thiol is one or more of n-dodecyl mercaptan, tert-dodecyl mercaptan, and 1,10-decanedithiol.

6. The preparation method of the network-like silicon@tin disulfide@carbon anode material according to claim 1, characterized in that, In step (3), the molar ratio of the network-like silicon to the tin salt is 50:

1.

7. The preparation method of the networked silicon@tin disulfide@carbon anode material according to claim 1, wherein, In step (3), the molar ratio of the tin salt to the thiol is 1:

20.

8. A network-like silicon@tin disulfide@carbon anode material prepared by the preparation method of the network-like silicon@tin disulfide@carbon anode material according to any one of claims 1 - 8.

9. Application of a network-like silicon@tin disulfide@carbon anode material in a lithium battery anode.

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