A graphene-based double-carbon negative electrode material for a sodium-ion battery and a preparation method and application thereof

Abstract

The application discloses a graphene-based double-carbon negative electrode material for a sodium ion battery and a preparation method and application thereof. The graphene-based double-carbon negative electrode material comprises the following steps: S1, mixing nano silicon dioxide, polyvinylpyrrolidone, pyrrole and silane coupling agent in an alcohol aqueous solution, and then adding an initiator to perform a polymerization reaction to obtain Si-NH2@PPy; S2, mixing Si-NH2@PPy, silane coupling agent, graphene oxide and pyrrole in an alcohol aqueous solution, and then adding an initiator to perform a polymerization reaction to obtain a solid product SiO2@C@RGO@C; S3, high-temperature calcining SiO2@C@RGO@C in a protective atmosphere, and then etching, washing and drying to obtain the graphene-based double-carbon negative electrode material. The graphene-based double-carbon negative electrode material has high specific capacity, good electrical conductivity and chemical stability, and has excellent electrochemical lithium storage and sodium storage performance.

Description

Technical Field

[0001] This invention belongs to the field of nano-carbon materials technology, and particularly relates to a graphene-based dual-carbon anode material for sodium-ion batteries, its preparation method and application. Background Technology

[0002] With the rapid development of renewable energy and the increasing demand for energy transition, electrochemical energy storage, as a key energy storage and management technology, has received widespread research attention. Lithium-ion batteries, as the current mainstream electrochemical energy storage technology, have achieved commercial success in mobile devices, electric vehicles, and other fields, driving the development and focus of electrochemical energy storage research. Although lithium-ion batteries have advantages such as high energy density and long cycle life, they still face challenges in terms of cost, resource scarcity, and safety. Since sodium-ion batteries share some similarities with lithium-ion batteries in ion transport mechanisms and material properties, the successful application of hard carbon as a negative electrode material for lithium-ion batteries provides a foundation and inspiration for the research of hard carbon negative electrode materials for sodium-ion batteries. Hard carbon materials have a high specific surface area, good electrical conductivity, and chemical stability, enabling them to carry and store sodium ions, and exhibit low volume change, which helps improve the cycle life and capacity retention of sodium-ion batteries. The development needs of sodium-ion battery technology and the continuous pursuit of higher performance for negative electrode materials aim to achieve high-performance, low-cost, and sustainable energy storage solutions.

[0003] There are various methods for preparing hard carbon anode materials. Common methods include: 1. Heat treatment: Precursor materials containing carbon sources are subjected to high-temperature heat treatment in an inert atmosphere to achieve a carbonization reaction. Common carbon sources include natural graphite, graphene, and carbon nanotubes. The heat treatment temperature and time can be controlled according to specific requirements; 2. Hydrothermal method: Carbon sources are treated in a high-temperature, high-pressure aqueous solution to induce a carbonization reaction. This method can prepare nanoscale hard carbon materials; 3. Carbonizing agent-assisted method: A carbonizing agent, such as a polymer or glucose, is added to the carbon source. After heat treatment, the carbonizing agent can promote the carbonization reaction and form hard carbon materials; 4. Chemical vapor deposition method: The carbon source precursor is introduced into the reaction chamber in gaseous form at high temperature. Under the action of a catalyst, hard carbon materials are generated through a chemical reaction; 5. Biomass conversion method: Biomass is used as a carbon source and converted into hard carbon materials through pyrolysis or oxidation.

[0004] However, the hard carbon anode materials prepared by these methods have problems such as low specific capacity, insufficient electrical conductivity and chemical stability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a graphene-based dual-carbon anode material with high specific capacity that can carry and store lithium ions and sodium ions, and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a graphene-based dual-carbon anode material includes the following steps:

[0008] S1 mixes nano-silica, polyvinylpyrrolidone, pyrrole and silane coupling agent in an alcohol-water solution, and then adds an initiator to carry out a polymerization reaction to obtain the solid product Si-NH2@PPy.

[0009] S2) Si-NH2@PPy, silane coupling agent, graphene oxide and pyrrole are mixed in an alcohol aqueous solution, and then an initiator is added to carry out a polymerization reaction to obtain the solid product SiO2@C@RGO@C;

[0010] S3) The solid product SiO2@C@RGO@C was calcined at high temperature in a protective atmosphere, then etched, washed and dried to obtain the graphene-based dual carbon anode material C@RGO@C.

[0011] Preferably, in the above preparation method, the temperature at which the nano-silica and polyvinylpyrrolidone are mixed in an alcohol-water solution in step S1 is 0°C to 30°C, and the mixing time is 30 to 90 min.

[0012] In step S2, the temperature at which the silane coupling agent and pyrrole monomer are added to the mixture solution 2 is 0°C to 30°C, and the mixing time is 30 to 90 minutes.

[0013] Preferably, in the above preparation method, the silane coupling agent is triethoxysilane; and the initiator is potassium persulfate.

[0014] Preferably, in the above preparation method, the polymerization reaction temperature in step S1 or step S2 is 0℃~30℃; the polymerization reaction time is 6~12h; and the high-temperature calcination temperature in step S3 is 600℃~1000℃.

[0015] Preferably, in the above preparation method, the etching in step S3 is performed using an alkaline solution; the temperature of the alkaline solution etching is 20℃~80℃, and the etching time is 1~4h.

[0016] Preferably, in the above preparation method, the mass ratio of nano-silica to polyvinylpyrrolidone in step S1 is (20-60):(6-9), the mass-volume ratio of nano-silica to alcohol-water solution is (400-1200) mg:(40-60) ml, and the volume ratio of alcohol to water in the alcohol-water solution is (2-3):(2-3).

[0017] The mass-to-volume ratio of the nano-silica to pyrrole is (400-1200) mg: (0.2-2) ml; the volume ratio of the pyrrole to the silane coupling agent is (0.2-2): (0.05-0.2); the molar ratio of the pyrrole to the initiator is (0.003-0.03): (0.0004-0.0012).

[0018] In step S2, the ratio of Si-NH2@PPy to graphene oxide solution is (200-1200) mg: (20-60) ml, the concentration of graphene oxide solution is 0.5-5 mg / ml, the mass-to-volume ratio of Si-NH2@PPy to pyrrole is (400-1200) mg: (0.2-2) ml, the volume ratio of pyrrole to silane coupling agent is (0.2-2): (0.05-0.2), and the molar ratio of pyrrole to initiator is (0.003-0.03): (0.0004-0.0012).

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The method for preparing graphene-based dual-carbon anode materials of this invention is precise, controllable, and efficient. It utilizes polypyrrole-derived hollow carbon spheres and polypyrrole-derived coated carbon films as rigid hard carbon, and reduced graphene oxide as flexible soft carbon. This method combines rigidity and flexibility, achieving the preparation of graphene-based dual-carbon anode materials. The resulting materials exhibit high specific capacity, good conductivity, and chemical stability, as well as excellent electrochemical lithium and sodium storage performance. This invention provides a suitable anode material for lithium-ion batteries at 1Ag... -1 After 800 cycles of current density cycling, the discharge capacity reaches 945 mAh g. -1 As a negative electrode material for sodium-ion batteries in 1Ag -1 After 1000 current density cycles, the discharge capacity reaches 195mAhg. -1 The excellent conductivity of this invention is mainly reflected in its superior rate performance, making it suitable for use as a 5Ag lithium-ion battery. -1 The average discharge capacity at current density is as high as 481 mAhg. -1 The excellent chemical stability of this invention is mainly reflected in the small volume change of the electrode material during charging and discharging, which still maintains a stable carbon skeleton structure. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the graphene-based dual carbon anode material C@RGO@C-200 obtained in Example 1 of this invention;

[0022] Figure 2This is a transmission electron microscope (TEM) image of the graphene-based dual-carbon anode material C@RGO@C-200 obtained in Example 1 of this invention.

[0023] Figure 3 This is a scanning electron microscope image of the core-shell structured graphene-based dual carbon anode material SiO2@C@RGO@C obtained in Example 2 of the present invention;

[0024] Figure 4 This is a transmission electron microscope (TEM) image of the core-shell structured graphene-based dual-carbon anode material SiO2@C@RGO@C obtained in Example 2 of this invention.

[0025] Figure 5 This is a scanning electron microscope image of the graphene-based carbon anode material C@RGO obtained in Example 3 of the present invention;

[0026] Figure 6 This is a transmission electron microscope (TEM) image of the graphene-based carbon anode material C@RGO obtained in Example 3 of the present invention.

[0027] Figure 7 This is a scanning electron microscope image of the graphene-based dual carbon anode material C@RGO@C-500 obtained in Example 4 of this invention;

[0028] Figure 8 This is a transmission electron microscope (TEM) image of the graphene-based dual-carbon anode material C@RGO@C-500 obtained in Example 4 of this invention.

[0029] Figure 9 This is a graph showing the lithium storage performance of the graphene-based dual-carbon anode material C@RGO@C-200;

[0030] Figure 10 This is a graph showing the sodium storage performance of the graphene-based dual-carbon anode material C@RGO@C-200;

[0031] Figure 11 The graphene-based dual-carbon anode material C@RGO@C-200 is used as a lithium-ion electrode material in 1Ag. -1 Transmission electron microscope image after 800 cycles at current density. Detailed Implementation

[0032] All reagents used in the following examples are commercially available.

[0033] Example 1

[0034] Add 6 mL of concentrated ammonia and 4 mL of deionized water to a three-necked flask containing 70 mL of anhydrous ethanol and stir magnetically in a room temperature water bath for 10 min. Then, slowly add a mixed solution containing 3 mL of tetraethyl orthosilicate and 40 mL of ethanol using a constant pressure funnel, and continue stirring for 4 h until the reaction is complete. After centrifugation and washing, silica spheres with a particle size of approximately 200 nm are obtained. Disperse 800 mg of silica spheres in 60 mL of ethanol-water solution with a volume ratio of 1:1, add 0.4 mL of silane coupling agent KH550, and sonicate for 90 min to obtain a SiO2-NH2 sample with surface aminated modification. Place the above dispersed solution in an ice-water bath and stir continuously, then add 0.8 mL of pyrrole monomer. After stirring for 30 min, add 20 mL of potassium persulfate solution, continue stirring, and react fully for 12 h. Centrifuge, wash, and dry to obtain a black solid product SiO2-NH2@PPy. 400 mg of SiO2-NH2@PPy was dispersed in 40 mL of 2 mg / mL GO solution, 0.4 mL of silane coupling agent KH550 was added, and the mixture was sonicated for 90 min. Then, 0.8 mL of pyrrole monomer was added. After stirring for 30 min, 20 mL of potassium persulfate solution was added, and the mixture was stirred continuously and allowed to react completely for 12 h. The product was then centrifuged, washed, and dried to obtain a black solid product, SiO2@PPy@GO@PPy. Finally, the solid product was carbonized at 800 °C for 2 h under a N2 atmosphere to obtain the silicon dioxide carbon anode core-shell material SiO2@C@RGO@C. This material was then etched in a 70 °C sodium hydroxide solution for 4 h. After washing and drying the final solid product, the graphene-based dual carbon anode material C@RGO@C was obtained.

[0035] Scanning electron microscope image of graphene-based dual carbon anode material C@RGO@C-200 as shown below Figure 1 As shown.

[0036] Transmission electron microscope image of graphene-based dual carbon anode material C@RGO@C-200 as shown below Figure 2 As shown.

[0037] Example 2

[0038] Add 6 mL of concentrated ammonia and 4 mL of deionized water to a three-necked flask containing 70 mL of anhydrous ethanol and stir magnetically in a room temperature water bath for 10 min. Then, slowly add a mixed solution containing 3 mL of tetraethyl orthosilicate and 40 mL of ethanol using a constant pressure funnel, and continue stirring for 4 h until the reaction is complete. After centrifugation and washing, silica spheres with a particle size of approximately 200 nm are obtained. Disperse 800 mg of silica spheres in 60 mL of ethanol-water solution with a volume ratio of 1:1, add 0.4 mL of silane coupling agent KH550, and sonicate for 90 min to obtain a SiO2-NH2 sample with surface aminated modification. Place the above dispersed solution in an ice-water bath and stir continuously, then add 0.8 mL of pyrrole monomer. After stirring for 30 min, add 20 mL of potassium persulfate solution, continue stirring, and react fully for 12 h. Centrifuge, wash, and dry to obtain a black solid product SiO2-NH2@PPy. 400 mg of SiO2-NH2@PPy was dispersed in 40 mL of 2 mg / mL GO solution, 0.4 mL of silane coupling agent KH550 was added, and the mixture was sonicated for 90 min. Then, 0.8 mL of pyrrole monomer was added. After stirring for 30 min, 20 mL of potassium persulfate solution was added, and the mixture was stirred continuously and allowed to react completely for 12 h. The product was then centrifuged, washed, and dried to obtain a black solid product, SiO2@PPy@GO@PPy. Finally, the solid product was carbonized at 800 °C for 2 h under a N2 atmosphere to obtain the silicon dioxide carbon anode core-shell material SiO2@C@RGO@C.

[0039] Scanning electron microscope image of core-shell structured graphene-based dual-carbon anode material SiO2@C@RGO@C as shown below Figure 3 As shown.

[0040] Transmission electron microscopy image of SiO2@C@RGO@C core-shell structured graphene-based dual-carbon anode material, as shown below. Figure 4 As shown.

[0041] Example 3

[0042] Add 6 mL of concentrated ammonia and 4 mL of deionized water to a three-necked flask containing 70 mL of anhydrous ethanol and stir magnetically in a room temperature water bath for 10 min. Then, slowly add a mixed solution containing 3 mL of tetraethyl orthosilicate and 40 mL of ethanol using a constant pressure funnel, and continue stirring for 4 h until the reaction is complete. After centrifugation and washing, silica spheres with a particle size of approximately 200 nm are obtained. Disperse 800 mg of silica spheres in 60 mL of ethanol-water solution with a volume ratio of 1:1, add 0.4 mL of silane coupling agent KH550, and sonicate for 90 min to obtain a SiO2-NH2 sample with surface aminated modification. Place the above dispersed solution in an ice-water bath and stir continuously, then add 0.8 mL of pyrrole monomer. After stirring for 30 min, add 20 mL of potassium persulfate solution, continue stirring, and react fully for 12 h. Centrifuge, wash, and dry to obtain a black solid product SiO2-NH2@PPy. 400 mg of SiO2-NH2@PPy was dispersed in 40 mL of 2 mg / mL GO solution, stirred continuously, and reacted completely for 12 h. After centrifugation, washing, and drying, a black solid product, SiO2@PPy@GO, was obtained. The solid product was then carbonized at 800 °C for 2 h under a N2 atmosphere to obtain the silicon dioxide carbon anode core-shell material SiO2@C@RGO. This material was then etched in a 70 °C sodium hydroxide solution for 4 h. After washing and drying, the graphene-based dual carbon anode material C@RGO was obtained.

[0043] Scanning electron microscope image of graphene-based carbon anode material C@RGO as shown below Figure 5 As shown.

[0044] Transmission electron microscope image of graphene-based carbon anode material C@RGO as shown below Figure 6 As shown.

[0045] Example 4

[0046] 12 mL of concentrated ammonia and 4 mL of deionized water were added to a three-necked flask containing 70 mL of anhydrous ethanol, and the flask was placed in a room temperature water bath and magnetically stirred for 10 min. Then, a mixed solution containing 3 mL of tetraethyl orthosilicate and 40 mL of ethanol was slowly added using a constant pressure funnel, and stirring was continued for 4 h until the reaction was complete. After centrifugation and washing, silica spheres with a particle size of approximately 500 nm were obtained. 800 mg of silica spheres were dispersed in 60 mL of a 1:1 volume ratio ethanol-water solution, and 0.4 mL of silane coupling agent KH550 was added. After sonication for 90 min, a surface-aminated SiO2-NH2 sample was obtained. The dispersed solution was then placed in an ice-water bath and stirred continuously, and 0.8 mL of pyrrole monomer was added. After stirring for 30 min, 20 mL of potassium persulfate solution was added, and stirring was continued until the reaction was complete for 12 h. After centrifugation, washing, and drying, a black solid product, SiO2-NH2@PPy, was obtained. 400 mg of SiO2-NH2@PPy was dispersed in 40 mL of 2 mg / mL GO solution, and 0.8 mL of pyrrole monomer was added. After stirring for 30 min, 20 mL of potassium persulfate solution was added, and the mixture was stirred continuously and allowed to react completely for 12 h. After centrifugation, washing, and drying, a black solid product SiO2@PPy@GO@PPy was obtained. Finally, the solid product was carbonized at 800 °C for 2 h under a N2 atmosphere to obtain the silicon dioxide carbon anode core-shell material SiO2@C@RGO@C, which was then etched in a sodium hydroxide solution at 70 °C for 4 h. After washing and drying the final solid product, the graphene-based dual carbon anode material C@RGO@C-500 was obtained.

[0047] Scanning electron microscope image of graphene-based dual carbon anode material C@RGO@C-500 as shown below Figure 7 As shown.

[0048] Transmission electron microscope image of graphene-based dual carbon anode material C@RGO@C-500 as shown below Figure 8 As shown.

[0049] Example 5: Electrochemical Performance Testing

[0050] (1) Preparation of working electrode: The graphene-based dual-carbon anode material obtained in Example 1 was ground and mixed with conductive carbon black and PVDF at a mass ratio of 75:15:10, with N-methylpyrrolidone (NMP) as the solvent to form a slurry, which was then uniformly coated onto a copper foil current collector (coating amount of 1.0 mg / cm²). 2 After being dried in a vacuum drying oven at 120℃ for 12 hours, the material was sliced ​​to make a working electrode.

[0051] (2) Assemble the battery: use lithium (or sodium) sheet as counter electrode, glass fiber as separator, use 1M LiPF6 (1M NaPF6) as electrolyte and dissolve it in a mixed solution of ethylene carbonate and dimethyl carbonate in a mass ratio of 1:1, and assemble the CR2032 button battery in a glove box filled with argon gas.

[0052] (3) Performance testing: at 0.01V~3V vs Li + / Li (or vs Na) + At a voltage range of / Na), with 1Ag -1 The current density is used to test the cycle performance of the battery.

[0053] Figure 9 It refers to the lithium storage performance of graphene-based dual-carbon anode materials. Figure 10 This refers to the sodium storage performance of graphene-based dual-carbon anode materials. From... Figure 9 and 10 It can be seen that the graphene-based dual-carbon anode material obtained in Example 1 exhibits excellent electrochemical lithium and sodium storage performance. Examples 2-4 were tested using the same method, and they also showed excellent electrochemical lithium and sodium storage performance. Figure 11 The graphene-based dual-carbon anode material C@RGO@C-200 is used as a lithium-ion electrode material in 1Ag. -1 Transmission electron microscopy images obtained after 800 cycles at current density show that the present invention has a high discharge capacity as a negative electrode material for lithium-ion batteries.

Claims

1. A method for preparing a graphene-based double carbon negative electrode material, characterized in that Comprising the following steps: S1 mixing nano-silicon dioxide, polyvinylpyrrolidone, pyrrole and silane coupling agent in alcohol aqueous solution, then adding initiator to carry out polymerization reaction to obtain solid product Si-NH2@PPy. S2) mixing Si-NH2@PPy, silane coupling agent, graphene oxide and pyrrole in alcohol aqueous solution, then adding initiator to carry out polymerization reaction to obtain solid product SiO2@C@RGO@C; S3) calcining solid product SiO2@C@RGO@C at high temperature in a protective atmosphere, then etching, washing and drying to obtain graphene-based double-carbon negative electrode material C@RGO@C.

2. The production method according to claim 1, characterized by, The temperature for mixing nano-silicon dioxide and polyvinylpyrrolidone in alcohol aqueous solution in step S1 is 0-30℃, and the mixing time is 30-90 min.

3. The production method according to claim 1, characterized by, The silane coupling agent is triethoxysilane; and the initiator is potassium persulfate.

4. The method of claim 1, wherein, The temperature for polymerization reaction in step S1 or step S2 is 0-30℃, and the polymerization reaction time is 6-12 h; and the temperature for high-temperature calcination in step S3 is 600-1000℃.

5. The preparation method according to claim 1, characterized in that, The etching in step S3 is carried out by using alkaline solution, and the etching temperature is 20-80℃, and the etching time is 1-4 h.

6. The method of claim 1, wherein, The mass ratio of nano-silicon dioxide to polyvinylpyrrolidone in step S1 is (20-60):(6-9), the mass-volume ratio of nano-silicon dioxide to alcohol aqueous solution is (400-1200)mg:(40-60)ml, and the volume ratio of alcohol to water in alcohol aqueous solution is (2-3):(2-3); The mass-volume ratio of nano-silicon dioxide to pyrrole is (400-1200)mg:(0.2-2)ml, the volume ratio of pyrrole to silane coupling agent is (0.2-2):(0.05-0.2), and the molar ratio of pyrrole to initiator is (0.003-0.03):(0.0004-0.0012); The ratio of Si-NH2@PPy to graphene oxide solution in step S2 is (200-1200)mg:(20-60)ml, the concentration of graphene oxide solution is 0.5-5mg / ml, the mass-volume ratio of Si-NH2@PPy to pyrrole is (400-1200)mg:(0.2-2)ml, the volume ratio of pyrrole to silane coupling agent is (0.2-2):(0.05-0.2), and the molar ratio of pyrrole to initiator is (0.003-0.03):(0.0004-0.0012).

7. The graphene-based double-carbon negative electrode material prepared by the preparation method of any one of claims 1-6.

8. The application of the graphene-based double-carbon negative electrode material of claim 7 as a lithium ion or sodium ion battery negative electrode material.

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