Network-like silicon@tin disulfide@carbon anode material, preparation method therefor, and use thereof

Abstract

The present application relates to the technical field of nano-anode materials for lithium batteries, and specifically disclosed are a network-like silicon@tin disulfide@carbon anode material, a preparation method therefor, and use thereof. The preparation method for a network-like silicon@tin disulfide@carbon anode material comprises: stirring and mixing soluble organosilicon, sodium hydroxide, and deionized water; then adding ethanol, and stirring and mixing to obtain a reaction solution; post-treating the reaction solution to obtain three-dimensional aerogel network-like silica; calcining the three-dimensional aerogel network-like silica with a reducing agent to obtain network-like silicon; mixing the network-like silicon, a tin salt, and oleylamine, then first adding thiol, and then stirring and mixing at 180-200 °C to obtain a reaction solution; and post-treating the reaction solution to obtain the network-like silicon@tin disulfide@carbon anode material. In the present application, by means of double-layer coating of the network-like silicon, the inner core can be protected from external chemical attack, the reactive active sites are increased, and the silicon content is reduced, thereby improving the electrochemical performance of the material.

Description

A network-structured silicon@tin disulfide@carbon anode material, its preparation method and application Technical Field

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

[0002] To meet the needs of industrial development, there is a strong demand for energy storage devices, and lithium-ion batteries, as one of the mainstream energy storage devices, have received widespread attention. Traditional graphite anodes, due to their relatively low theoretical capacity (372 mAh / g), can no longer meet the demands 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 (4200mAh / g). It has a low lithium insertion / extraction potential and is relatively abundant, making it one of the best anode materials for developing high-energy-density batteries.

[0004] However, despite silicon's high theoretical capacity, it undergoes a huge volume change (>300%) during charging and discharging. This change causes material structure damage and particle pulverization, which in turn leads to rapid capacity decay and electrode failure. Summary of the Invention

[0005] To improve the stability of silicon materials during charge and discharge processes, this application provides a network silicon@tin disulfide@carbon anode material, its preparation method, and its application.

[0006] In a first aspect, this application provides a method for preparing a network-like silicon@tin disulfide@carbon anode material, employing the following technical solution:

[0007] A method for preparing a network-like silicon@tin disulfide@carbon anode material includes the following steps:

[0008] (1) Add 4-8g of soluble organosilicon and 0.6-1.0g of sodium hydroxide to 60-80mL of deionized water and stir for 80-150min to obtain a mixed solution; after passing an inert gas into the mixed solution, add 80-100μL of ethanol and stir for 15-20min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid, wash it, and obtain a three-dimensional aerogel network silica.

[0009] (2) The three-dimensional aerogel network silica from step (1) and the reducing agent are calcined at 700-900℃ for 3-6 hours under an inert atmosphere by heating from 25℃ to 700-900℃ at a heating rate of 0.5-1.0℃ / min to obtain network silica.

[0010] (3) Add the network silicon and tin salt from step (2) to oleylamine, stir and mix to obtain a mixture; after passing an inert gas into the mixture, stir and mix at 120-150℃ 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℃ for 20-30 min to obtain a reaction solution; cool the reaction solution naturally, filter, collect the solid, wash, and obtain the network silicon@tin disulfide@carbon anode material.

[0011] By adopting the above technical solution, a certain amount of soluble organosilicon is first hydrolyzed under alkaline conditions to obtain a three-dimensional aerogel network of silica, and then reduced at high temperature under specific temperature conditions. The resulting network silica has a large specific surface area and can fully contact the electrolyte, which is beneficial to improving the electrochemical performance of the negative electrode material.

[0012] Simultaneously, a prepolymer is formed by mixing network silicon, tin salt, and oleylamine and heating. Then, by controlling the reaction temperature with thiol, the resulting tin disulfide and carbon can be sequentially coated onto the surface of the network silicon, resulting in a double-layer coated network silicon@tin disulfide@carbon anode material. On the one hand, the network silicon has a large specific surface area, increasing the contact area with the electrolyte, increasing reaction sites, and improving the electrochemical performance of the anode material. The coated tin disulfide and carbon not only increase the conductivity of the anode material but also form a unique closed microenvironment to protect the core from external chemical corrosion, which is beneficial to improving the electrochemical performance of the anode material. On the other hand, the double coating can reduce the silicon content in the anode material, allowing the anode material to have a reasonable volume expansion range.

[0013] Therefore, the network silicon@tin disulfide@carbon anode material prepared by the method of this application has both high specific capacity and cycle stability, and has good electrochemical performance and broad commercial prospects.

[0014] Preferably, in step (1), the soluble organosilicon includes one or both of tetraethyl orthosilicate and tetrabutyl orthosilicate.

[0015] By adopting the above technical solution, tetraethyl orthosilicate and tetrabutyl orthosilicate have high reactivity and can be rapidly hydrolyzed in an alkaline environment to obtain a three-dimensional aerogel network of silica with a high specific surface area, which is beneficial to increase...

[0016] Preferably, in step (2), the reducing agent is one or more of magnesium powder, aluminum powder and boron.

[0017] By adopting the above technical solution, magnesium powder, aluminum powder and boron have advantages such as strong reducing ability, high reactivity and mild reaction conditions. They can reduce three-dimensional aerogel network silica into network silicon in a lower temperature range, which is beneficial to improving the yield of network silicon and the safety of the reaction.

[0018] Preferably, in step (3), the tin salt is one or more of tin acetate, tin tetrachloride and tin sulfate.

[0019] Preferably, in step (3), the thiol is one or more of n-dodecylthiol, tert-dodecylthiol, and 1,10-decanedithiol.

[0020] Preferably, in step (3), the molar ratio of network silicon to tin salt is 50:1.

[0021] Preferably, in step (3), the molar ratio of tin salt to thiol is 1:20.

[0022] Secondly, this application provides a network-structured silicon@tin disulfide@carbon anode material, employing the following technical solution:

[0023] A network silicon@tin disulfide@carbon anode material is prepared by the above-mentioned preparation method of network silicon@tin disulfide@carbon anode material.

[0024] By adopting the above technical solution, the network silicon@tin disulfide@carbon anode material has a multi-core structure. On the one hand, it can form a special closed structure of active sites, protecting the core from external chemical corrosion, 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.

[0025] Thirdly, this application provides an application of a network-structured silicon@tin disulfide@carbon anode material, employing the following technical solution:

[0026] Application of a network-structured silicon@tin disulfide@carbon anode material in lithium-ion battery anodes.

[0027] By adopting the above technical solution, the network silicon@tin disulfide@carbon anode material of this application has both high specific capacity and cycle stability, and has broad commercial prospects when applied to lithium battery anodes.

[0028] In summary, this application has the following beneficial effects:

[0029] 1. This application prepares a silicon-carbon material with multiple cores by double-coating a network of silicon. Due to the special closed structure of the active sites of the multi-core structure, a unique closed microenvironment is formed, which can protect the core from external chemical erosion, thus improving the electrochemical performance of the material.

[0030] 2. By controlling the amount of soluble organosilicon and sodium hydroxide, this application can adjust the hydrolysis rate of organosilicon to obtain a three-dimensional aerogel network of silica with uniform particle size and high specific surface area. It has many reaction sites and is easily coated by tin disulfide after reduction, which further improves the electrochemical performance of the negative electrode material.

[0031] 3. The network silicon@tin disulfide@carbon anode material of this application has both high specific capacity and cycle stability, and good electrochemical performance, and has broad commercial prospects in lithium battery anodes. Attached Figure Description

[0032] Figure 1 shows the cycle life of the network silicon@tin disulfide@carbon anode material in Example 1;

[0033] Figure 2 shows the cycle life of the network silicon@tin disulfide@carbon anode material in Example 2;

[0034] Figure 3 shows the cycle life of the network silicon@tin disulfide@carbon anode material in Example 3. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0036] Performance testing

[0037] The specific capacity of the network silicon@tin disulfide@carbon anode material prepared in the embodiments of this application and the anode material prepared in the comparative example were tested for the first discharge specific capacity and the specific capacity after 100 cycles, and the capacity retention rate was calculated.

[0038] The detection method is as follows:

[0039] The constant current charge-discharge test, under a current density of 1A / g, showed a charge-discharge voltage window of 0.005-2V.

[0040] The formula for calculating capacity retention is:

[0041] Capacity retention rate = (discharge specific capacity after 100 cycles / initial discharge specific capacity) × 100%. Example

[0042] Example 1

[0043] A method for preparing a network-like silicon@tin disulfide@carbon anode material includes the following steps:

[0044] (1) Add 4g of soluble tetraethyl orthosilicate and 0.6g of sodium hydroxide to 60ml of deionized water and stir for 80min to obtain a mixed solution; after purging argon gas into the mixed solution for 20min, add 80μL of ethanol and stir for 15min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it three times with deionized water and anhydrous ethanol to obtain a three-dimensional aerogel network of silica.

[0045] (2) 0.6g of the three-dimensional aerogel network silica from step (1) and 0.25g of magnesium powder were calcined at 25°C to 700°C for 6h under an inert atmosphere at a heating rate of 0.5°C / min to obtain network silica.

[0046] (3) Add 0.28g of the network silicon from step (2) and 0.0472g of tin acetate to 20ml of oleylamine and stir magnetically to obtain a mixture; purge argon gas into the mixture for 20min, and then stir and mix at 120℃ for 20min to obtain a mixed solution; add 1ml of n-dodecyl mercaptan to the mixed solution at 120℃, stir and mix for 30min, and then stir and mix at 180℃ for 20min to obtain a reaction solution; cool the reaction solution naturally to room temperature, filter, collect the solid and wash it 5 times with ethanol and deionized water to obtain the network silicon@tin disulfide@carbon anode material.

[0047] Example 2

[0048] A method for preparing a network-like silicon@tin disulfide@carbon anode material includes the following steps:

[0049] (1) Add 6g of soluble tetraethyl orthosilicate and 0.8g of sodium hydroxide to 60ml of deionized water and stir for 90min to obtain a mixed solution; after purging argon gas into the mixed solution for 30min, add 100μL of ethanol and stir for 15min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it three times with deionized water and anhydrous ethanol to obtain a three-dimensional aerogel network silica.

[0050] (2) 0.9g of the three-dimensional aerogel network silica from step (1) and 0.16g of boron were calcined at 25°C to 800°C for 5h under an inert atmosphere at a heating rate of 1.0°C / min to obtain network silica.

[0051] (3) Add 0.42g of the network silicon from step (2) and 0.0708 tin acetate to 20ml of oleylamine and stir magnetically to obtain a mixture; purge argon gas into the mixture for 30 min, and then stir and mix at 150℃ for 30 min to obtain a mixed solution; add 1.3mL of 1,10-decanedithiol to the mixed solution at 150℃, stir and mix for 30 min, and then stir and mix at 180℃ for 30 min to obtain a reaction solution; cool the reaction solution naturally to room temperature, filter, collect the solid and wash it 5 times with ethanol and deionized water to obtain the network silicon@tin disulfide@carbon anode material.

[0052] Example 3

[0053] A method for preparing a network-like silicon@tin disulfide@carbon anode material includes the following steps:

[0054] (1) Add 8g of soluble tetrabutyl orthosilicate and 1g of sodium hydroxide to 80ml of deionized water and stir for 150min to obtain a mixed solution; after purging the mixed solution with argon gas for 30min, add 100μL of ethanol and stir for 15min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it three times with deionized water and anhydrous ethanol to obtain a three-dimensional aerogel network silica.

[0055] (2) 1.2g of the three-dimensional aerogel network silica from step (1) and 0.55g of aluminum powder were calcined at 25℃ to 900℃ for 3h under an inert atmosphere at a heating rate of 1.0℃ / min to obtain network silica.

[0056] (3) Add 0.56g of the network silicon from step (2) and 1.042g of tin acetate to 20ml of oleylamine and stir magnetically to obtain a mixture; purge argon gas into the mixture for 30 min, and then stir and mix at 150℃ for 30 min to obtain a mixed solution; add tert-dodecyl mercaptan to the mixed solution at 150℃, stir and mix for 60 min, and then stir and mix at 200℃ for 30 min to obtain a reaction solution; cool the reaction solution naturally to room temperature, filter, collect the solid and wash it 5 times with ethanol and deionized water to obtain the network silicon@tin disulfide@carbon anode material.

[0057] The network silicon@tin disulfide@carbon anode materials prepared in Examples 1-3 of this application were tested for their initial discharge specific capacity and discharge specific capacity after 100 cycles under a current density of 1 A / g. The test results are shown in the table below.

[0058]

[0059] Analysis of the data in the table above, combined with Figures 1-3, shows that the network silicon@tin disulfide@carbon anode materials prepared in Examples 1-3 exhibit an initial discharge specific capacity of 2336-2460 mAh / g, a discharge specific capacity of 1996-2182 mAh / g after 100 cycles, and a capacity retention rate of 85.4-89.1%. This indicates that the network silicon@tin disulfide@carbon anode materials prepared in Examples 1-3 of this application possess high electrochemical performance.

[0060] Comparative Example

[0061] Comparative Example 1

[0062] A method for preparing a negative electrode material includes the following steps:

[0063] (1) Add 3g of soluble tetraethyl orthosilicate and 0.5g of sodium hydroxide to 60ml of deionized water and stir for 80min to obtain a mixed solution; after purging argon gas into the mixed solution for 20min, add 80μL of ethanol and stir for 15min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it three times with deionized water and anhydrous ethanol to obtain a three-dimensional aerogel network of silica.

[0064] (2) 0.6g of the three-dimensional aerogel network silica from step (1) and 0.25g of magnesium powder were calcined at 25℃ to 600℃ for 7h under an inert atmosphere at a heating rate of 0.4℃ / min to obtain network silica.

[0065] (3) Add 0.28g of the network silicon from step (2) and 0.0472g of tin acetate to 20ml of oleylamine and stir magnetically to obtain a mixture; purge argon gas into the mixture for 20min, and then stir and mix at 120℃ for 20min to obtain a mixed solution; add 1ml of n-dodecyl mercaptan to the mixed solution at 120℃, stir and mix for 60min, and then stir and mix at 160℃ for 40min to obtain a reaction solution; cool the reaction solution naturally to room temperature, filter, collect the solid and wash it 5 times with ethanol and deionized water to obtain the network silicon@tin disulfide@carbon anode material.

[0066] Comparative Example 2

[0067] A method for preparing a negative electrode material includes the following steps:

[0068] (1) Add 9g of soluble tetraethyl orthosilicate and 1.2g of sodium hydroxide to 80ml of deionized water and stir for 80min to obtain a mixed solution; purge argon gas into the mixed solution for 20min, then add 80μL of ethanol and stir for 15min to obtain a reaction solution; finally, centrifuge the reaction solution, collect the solid and wash it three times with deionized water and anhydrous ethanol to obtain a three-dimensional aerogel network of silica.

[0069] (2) 0.6g of the three-dimensional aerogel network silica from step (1) and 0.25g of magnesium powder were calcined at 25℃ to 950℃ for 2.5h under an inert atmosphere at a heating rate of 1.5℃ / min to obtain network silica.

[0070] (3) Add 0.28g of the network silicon from step (2) and 0.0472g of tin acetate to 20ml of oleylamine and stir magnetically to obtain a mixture; purge argon gas into the mixture for 20min, and then stir and mix at 150℃ for 20min to obtain a mixed solution; add 1ml of n-dodecyl mercaptan to the mixed solution at 150℃, stir and mix for 30min, and then stir and mix at 200℃ for 10min to obtain a reaction solution; cool the reaction solution naturally to room temperature, filter, collect the solid and wash it 5 times with ethanol and deionized water to obtain the network silicon@tin disulfide@carbon anode material.

[0071] The network silicon@tin disulfide@carbon anode materials prepared in Comparative Examples 1-2 of this application were tested for their initial discharge specific capacity and discharge specific capacity after 100 cycles under a current density of 1 A / g. The test results are shown in the table below.

[0072]

[0073] Data analysis of the table above shows that, compared with Comparative Examples 1 and 2, the network silicon@tin disulfide@carbon anode material prepared in Example 1 has a relatively higher initial discharge specific capacity of 9.81–12.71%, a relatively higher discharge specific capacity of 17.30–23.96% after 100 cycles, and a relatively higher capacity retention rate of 6.76–9.92%. This indicates that in the preparation method of the network silicon@tin disulfide@carbon anode material of this application, a certain amount of soluble organosilicon is first hydrolyzed under alkaline conditions, and then reduced at high temperature under specific temperature conditions. The resulting network silicon has a large specific surface area, which not only allows for full contact with the electrolyte, but also facilitates 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 corrosion, which is beneficial to improving the electrochemical performance of the anode material.

[0074] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

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

2. The method for preparing the network 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 method for preparing the network silicon@tin disulfide@carbon anode material according to claim 1, characterized in that, In step (2), the reducing agent is one or more of magnesium powder, aluminum powder and boron.

4. The method for preparing the network silicon@tin disulfide@carbon anode material according to claim 1, characterized in that, In step (3), the tin salt is one or more of tin acetate, tin tetrachloride and tin sulfate.

5. The method for preparing the network silicon@tin disulfide@carbon anode material according to claim 1, characterized in that, In step (3), the thiol is one or more of n-dodecylthiol, tert-dodecylthiol and 1,10-decanedithiol.

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

1.

7. The method for preparing the network silicon@tin disulfide@carbon anode material according to claim 1, characterized in that, In step (3), the molar ratio of tin salt to thiol is 1:

20.

8. A network silicon@tin disulfide@carbon anode material, prepared by the preparation method of the network silicon@tin disulfide@carbon anode material according to any one of claims 1 to 7.

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

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