Preparation method and application of graphene composite silicon negative electrode material

Abstract

The invention discloses a preparation method and application of a graphene composite silicon negative electrode material. Comprising the following steps: (1) ultrasonically dispersing silicon powder in a solution, adding a controllable ammonium salt solution, controlling a certain temperature and pH value to react, and then separating and drying to obtain functionalized silicon powder; (2) ultrasonically dispersing graphene oxide in a solution, then weighing a certain amount of the functionalized silicon powder prepared in the step (1), dispersing the functionalized silicon powder in the graphene oxide solution, adding a catalyst, and regulating and controlling the temperature to form chemical bond action between the functionalized silicon powder and active groups on the surface of the graphene oxide, so as to obtain the graphene oxide composite material. And separating and drying the composite material, and carrying out low-temperature heat treatment to obtain the composite material. The prepared graphene composite silicon negative electrode material serves as an active material, then a button type lithium ion battery is assembled, the lithium storage performance of the button type lithium ion battery is tested, and the result shows that the negative electrode material prepared through the method has the excellent lithium storage performance and can be popularized to be applied to power batteries or energy storage batteries in the new energy industry.

Description

Technical Field

[0001] This invention belongs to the technical field of material preparation and application, specifically relating to a method for preparing graphene composite silicon anode material and its application in lithium storage performance. Background Technology

[0002] With rapid socio-economic development, the consumption of fossil fuels is accelerating. To meet human energy demands, clean energy will play an increasingly important role. However, new energy sources such as wind, hydro, and solar power have inherent uncertainties. Therefore, developing large-scale, long-life energy storage devices is crucial for better utilization of these energy sources. Furthermore, in the development of new energy vehicles, driving range has become a bottleneck for the industry. To overcome this bottleneck, developing high-energy-density lithium-ion batteries is extremely important, and developing anode materials with high reversible specific capacity is one of the key factors in achieving high-energy-density lithium-ion batteries.

[0003] Silicon is considered an ideal anode material for lithium-ion batteries due to its extremely high theoretical lithium storage capacity (~4200 mAh / g). However, the following reactions occur during silicon's lithiation (lithium insertion and desorption): During the charging process (lithium insertion): When x = 4.4, Li is formed. 15 Si4 alloy, corresponding to a theoretical specific capacity of 4200 mAh / g for silicon-based materials. Discharge process (lithiation): Extremely large volume alternations will occur in the two reaction processes mentioned above (Kasavajjula, U.; Appleby, AJ, et al. Nano-and bulk-silicon-based insertion anodes for lithium-ion secondary cells. J Power Sources 2007, 163, (2), 1003-1039.), resulting in the breakage of silicon itself and causing rapid capacity decay. To improve the lithium storage stability of silicon anode materials, composite carbon materials are a commonly used strategy. Among them, graphene is considered an ideal material to improve the lithium storage stability of silicon materials due to its two-dimensional sheet structure and electrical, thermal and mechanical properties (Rao, CNR; Govindaraj, A., et al. Graphene: The New Two-Dimensional Nanomaterial. Angewandte Chemie International Edition 2009, 48, (42), 7752-7777.). The literature already reported has demonstrated that the intervention of graphene can effectively improve the lithium storage stability of lithium-ion batteries (Shi, QT; Rummeli, MH, et al. Enhanced performance of Si-based Li-ion batteries through elastic cushioning with hollow graphene shells. Sci China Mater 2022, 65, (9), 2343-2353; Zhang, Y.; Yang, S., et al. Functionalization-assistant ball milling towards Si / graphene anodes in high performance Li-ion batteries). Carbon 2021, 181, 300-309.); Some researchers have also combined graphene with silicon to obtain anode materials for lithium-ion batteries and applied for related patents (Xie Yingpeng, A graphene-modified silicon anode material and its preparation method and application: CN114613955A; Peng Xiaoqiang, Liu Zhaoping, You Jiangfeng et al., A high-efficiency graphene composite silicon-carbon anode material and its preparation method and battery CN202210042443.1; Ma Jingjing, Zhang Huan, Xu Guangri et al., A three-dimensional graphene porous silicon composite anode material and its preparation method and application CN202111287611.5).

[0004] As reported research findings indicate, there is still much work to be done in the research of obtaining graphene-silicon composite anode materials for lithium-ion batteries, aiming to obtain high-performance graphene-silicon composite anode materials for lithium-ion batteries (including solid-state batteries). Therefore, research on graphene-silicon composite anode materials has significant scientific and practical value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing nitrogen-doped manganese carbonate and its composites. This method utilizes chemical bonding to prepare graphene-silicon composite anode materials, promoting their widespread application in lithium-ion batteries (liquid electrolytes and subsequent all-solid-state batteries).

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

[0007] (a) Silicon powder is ultrasonically dispersed in a solution to form a uniform silicon powder solution. Then, an ammonium salt solution of controllable concentration is added. After reacting at a certain temperature and pH value, functionalized silicon powder is obtained through separation and drying.

[0008] (b) Graphene oxide is ultrasonically dispersed in a solution. Then, a certain amount of functionalized silicon powder prepared in step (a) is weighed and dispersed in the graphene oxide solution. The corresponding catalyst is added and the temperature is controlled to form chemical bonds between the functionalized silicon powder and the active groups on the surface of graphene oxide. The composite material is then separated, dried and subjected to low-temperature heat treatment to obtain a graphene composite silicon anode material with chemical bonding.

[0009] The silicon powder is commercially available or laboratory-prepared.

[0010] In step (a), the reaction temperature is 25-50 degrees Celsius and the pH value is 2-12.

[0011] The controllable concentration ammonium salt solution includes, but is not limited to: ammonium acetate (CH3COONH4), ammonium carbonate ((NH4)2CO3), ammonium bicarbonate (NH4HCO3), ammonium phosphate ((NH4)3PO4), diammonium hydrogen phosphate ((NH4)2HPO4), ammonium oxalate ((NH4)2C2O4), ammonium fluoride (NH4F), ammonia (NH4OH), and amino acids and their salts.

[0012] The graphene oxide includes samples with different degrees of oxidation prepared in the laboratory using a modified Hummer method, as well as commercially available samples with different degrees of oxidation.

[0013] The catalysts added include: Lewis acid-salt catalysts (such as AlCl3 / NH4Cl), basic catalysts (low-concentration NaOH or KOH aqueous solutions), enzyme catalysts (Fe(II) / α-ketoglutarate), metalloenzyme catalysts (pyridoxal derivatives), metal-based catalysts with different morphologies and structures (such as nano-copper or nano-nickel), and doped boron phosphate-supported catalysts, etc.

[0014] The chemical bonds referred to are covalent bonds or other chemical bonds formed between the active groups on the surface of silicon materials and the active groups on the surface of graphene.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] By chemically linking silicon and graphene through a chemical catalytic process, a composite anode material with a chemical bond structure is obtained. This material will have better lithium storage stability during lithium storage. The development of this material provides more options for its application in current lithium-ion batteries and future solid-state batteries. Attached Figure Description

[0017] Figure 1 This is a scanning electron microscope (SEM) image of silicon material.

[0018] Figure 2 This is a scanning electron microscope (SEM) image of the Si-graphene composite material.

[0019] Figure 3 This is a transmission electron microscope (TEM) image of the Si-graphene composite material.

[0020] Figure 4 This is an X-ray diffraction (XRD) image of the Si-graphene composite material.

[0021] Figure 5 This is a charge-discharge curve of the Si-graphene composite material.

[0022] Figure 6 This is a cycle curve of the Si-graphene composite material.

[0023] Figure 7 This is a cycle curve of the Si-graphene composite material. Detailed Implementation

[0024] The present invention will now be further described in detail with reference to specific embodiments.

[0025] Example 1

[0026] The preparation process and application examples of this material include the following steps: (a) Weigh 0.2 g of silicon powder and disperse it in 100 mL of deionized water to form a homogeneous silicon powder solution. Then, add 0.10 g of ammonium bicarbonate (NH4HCO3) to the homogeneous silicon powder solution. Control the temperature at 30°C and react for 30 min. After filtration, washing, and drying, obtain silicon powder material with amino functional groups. (b) Take 30 mg of commercial graphene oxide and add it to 60 mL of deionized water. After stirring and sonicating for 30 min, obtain a homogeneous graphene oxide solution. Then, weigh 0.2 g of the amino functional group silicon powder material prepared in step (a) and gradually add it to the homogeneous graphene oxide solution prepared above. Add 20 mg of NaOH as a catalyst, control the temperature at 40°C, and react for 30 min under mechanical stirring. Following filtration, washing, and drying, a silicon / graphene functionalized material (Si / RGN-F) was obtained after low-temperature heat treatment at 300℃. During morphological and property characterization, scanning electron microscopy (SEM) revealed that the silicon powder size was approximately 300 nm (see...). Figure 1 The silicon powder and graphene treated with chemical bonding reactions exhibit excellent bonding properties. Figure 2 The results of transmission electron microscopy also show that Si has good distribution on the surface of functional graphene. Figure 3 The X-ray diffraction (XRD) results show that the material has distinct carbon peaks and peaks similar to those of pure silicon (see...). Figure 4 After coating the Si / RGN-F material prepared above to prepare coin-type lithium-ion batteries, the initial cycle efficiency was tested to be 74.2%. Figure 5 Cycling tests revealed that the material's reversible capacity after 100 cycles at a current density of 5 A / g was 225 mAh / g. Figure 6 ).

[0027] Example 2

[0028] The preparation process and application examples of this material include the following steps: (a) Weigh 0.3 g of silicon powder and disperse it in 120 mL of deionized water to form a uniform silicon powder solution. Then, add 0.10 g of ammonium oxalate ((NH4)2C2O4) to the uniform silicon powder solution. Control the temperature at 40°C and react for 30 min. After filtration, washing, and drying, obtain silicon powder material with amino functional groups. (b) Take 40 mg of laboratory-prepared graphene oxide and add it to 80 mL of deionized water. After stirring and sonicating for 30 min, obtain a uniform graphene oxide solution. Then, weigh 0.3 g of the amino functional group silicon powder material prepared in step (a) and gradually add it to the uniform graphene oxide solution prepared above. Add 10 mg of nano-nickel as a catalyst. Control the temperature at 50°C and react for 60 min under mechanical stirring. Following filtration, washing, drying, and removal of nano-nickel, a silicon / graphene functionalized material (Si / RGN-F) was obtained after low-temperature heat treatment at 300℃. After coating the prepared Si / RGN-F material to fabricate coin-type lithium-ion batteries, the initial cycle efficiency was tested to be 76.6%. Cycling performance tests revealed that the material's reversible capacity after 100 cycles at a current density of 5 A / g was 236 mAh / g. Figure 7 ).

[0029] Example 3

[0030] The preparation process and application examples of this material include the following steps: (a) Weigh 0.4 g of silicon powder and disperse it in 120 mL of deionized water to form a uniform silicon powder solution. Then, add 0.10 g of ammonium carbonate ((NH4)2CO3) to the uniform silicon powder solution. Control the temperature at 30°C and react for 30 min. After filtration, washing, and drying, obtain silicon powder material with amino functional groups. (b) Take 60 mg of commercially prepared graphene oxide and add it to 120 mL of deionized water. After stirring and sonicating for 30 min, obtain a uniform graphene oxide solution. Then, weigh 0.4 g of the silicon powder material with carboxylate functional groups prepared in step (a) and gradually add it to the uniform graphene oxide solution prepared above. Add 10 mg of potassium hydroxide as a catalyst. Control the temperature at 40°C and react for 30 min under mechanical stirring. Following filtration, washing, drying, and removal of nano-nickel, a silicon / graphene functionalized material (Si / RGN-F) was obtained after low-temperature heat treatment at 300℃. When the prepared Si / RGN-F material was coated to fabricate coin-type lithium-ion batteries, its initial cycle efficiency was 75.2%. Cyclic performance testing revealed that the material had a reversible capacity of 382 mAh / g after 200 cycles at a current density of 2 A / g.

[0031] Example 4

[0032] The preparation process and application examples of this material include the following steps: (a) Weigh 0.25 g of silicon powder and disperse it in 100 mL of deionized water to form a uniform silicon powder solution. Then, add 0.30 g of glycine to the uniform silicon powder solution. Control the temperature at 30°C and react for 30 min. After filtration, washing, and drying, obtain silicon powder material with amino functional groups. (b) Take 45 mg of laboratory-prepared graphene oxide and add it to 90 mL of deionized water. After stirring and sonicating for 30 min, obtain a uniform graphene oxide solution. Then, weigh 0.25 g of the silicon powder material with carboxylate functional groups prepared in step (a) and gradually add it to the uniform graphene oxide solution prepared above. Add 15 mg of AlCl3 / NH4Cl as a catalyst. Control the temperature at 40°C and react for 30 min under mechanical stirring. Following filtration, washing, drying, and catalyst removal, a silicon / graphene functionalized material (Si / RGN-F) was obtained after low-temperature heat treatment at 300℃. When the prepared Si / RGN-F material was coated to fabricate coin-type lithium-ion batteries, its initial cycle efficiency was 74.6%. Cyclic performance testing revealed that the material had a reversible capacity of 378 mAh / g after 200 cycles at a current density of 2 A / g.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A method for preparing a graphene-composite silicon anode material, characterized in that... It includes the following steps: (a) Silicon powder is ultrasonically dispersed in a solution to form a uniform silicon powder solution. Then, an ammonium salt solution of controllable concentration is added. After reacting at a certain temperature and pH value, functionalized silicon powder is obtained through separation and drying. (b) Graphene oxide is ultrasonically dispersed in a solution. Then, a certain amount of functionalized silicon powder prepared in step (a) is weighed and dispersed in the graphene oxide solution. The corresponding catalyst is added and the temperature is controlled to form chemical bonds between the functionalized silicon powder and the active groups on the surface of graphene oxide. The composite material is then separated, dried and subjected to low-temperature heat treatment to obtain a graphene composite silicon anode material with chemical bonding.

2. The method for preparing the graphene-composite silicon anode material according to claim 1, characterized in that: The silicon powder is commercially available or laboratory-prepared.

3. The method for preparing the graphene-composite silicon anode material according to claim 2, characterized in that: In step (a), the reaction temperature is 25-50 degrees Celsius and the pH value is 2-12.

4. The method for preparing the graphene-composite silicon anode material according to claim 3, characterized in that: The controllable concentration ammonium salt solution includes, but is not limited to: ammonium acetate, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, diammonium hydrogen phosphate, ammonium oxalate, ammonium fluoride, ammonia water, and amino acids and their salts.

5. The method for preparing the graphene-composite silicon anode material according to claim 1, characterized in that: The graphene oxide includes samples with different degrees of oxidation prepared in the laboratory using a modified Hummer method, as well as commercially available samples with different degrees of oxidation.

6. The method for preparing the graphene-composite silicon anode material according to claim 1, characterized in that: The catalysts added include: Lewis acid-salt catalysts, basic catalysts, enzyme catalysts, metalloenzyme catalysts, metal-based catalysts with different morphologies and structures, and doped boron phosphate-supported catalysts.

7. The method for preparing the graphene-composite silicon anode material according to claim 1, characterized in that: The chemical bonds referred to are covalent bonds or other chemical bonds formed between the active groups on the surface of silicon materials and the active groups on the surface of graphene.

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