阅读说明：本技术 一种氮掺杂碳/二氧化锡柔性复合薄膜及其制备方法和应用 (Nitrogen-doped carbon/tin dioxide flexible composite film and preparation method and application thereof ) 是由 杨艳玲 孙瑜 薛帆 锁国权 侯小江 冯雷 张荔 叶晓慧 于 2021-07-15 设计创作，主要内容包括：本发明公开了一种氮掺杂碳/二氧化锡柔性复合薄膜及其制备方法和应用,属于钠离子电池技术领域。所述制备方法包括：将棉花压缩后剪裁,得到片状样品,将所得片状样品清洗后干燥,得到棉花片A；将K-(2)SnO-(3)·3H-(2)O均匀分散于水中,得到溶液B,将尿素均匀分散于所得溶液B中,得到溶液C；将所得棉花片A置于溶液C中进行超声处理,得到棉花片D,将所得棉花片D经冷冻干燥后,得到棉花片E,将所得棉花片E经碳化煅烧处理,得到氮掺杂碳/二氧化锡柔性复合薄膜。所制得的氮掺杂碳/二氧化锡柔性复合薄膜能够解缓SnO-(2)颗粒导电性差的问题,因此能够作为钠离子电池的负极材料的应用。(The invention discloses a nitrogen-doped carbon/tin dioxide flexible composite film and a preparation method and application thereof, and belongs to the technical field of sodium ion batteries. The preparation method comprises the following steps: compressing cotton, cutting to obtain a sheet sample, cleaning the sheet sample, and drying to obtain a cotton piece A; will K 2 SnO 3 ·3H 2 Uniformly dispersing O in water to obtain a solution B, and uniformly dispersing urea in the obtained solution B to obtain a solution C; placing the cotton piece A in the solution C for ultrasonic treatment to obtain cotton piece D, freeze-drying the cotton piece D, and packagingAnd carrying out carbonization and calcination treatment on the cotton piece E to obtain the nitrogen-doped carbon/tin dioxide flexible composite film. The prepared nitrogen-doped carbon/stannic oxide flexible composite film can relieve SnO 2 The particle has poor conductivity, so the particle can be used as the negative electrode material of the sodium ion battery.)

1. A preparation method of a nitrogen-doped carbon/tin dioxide flexible composite film is characterized by comprising the following steps:

compressing cotton, cutting to obtain a sheet sample, cleaning the sheet sample, and drying to obtain a cotton piece A; will K₂SnO₃·3H₂Uniformly dispersing O in water to obtain a solution B, and uniformly dispersing urea in the obtained solution B to obtain a solution C; and (3) placing the obtained cotton piece A in the solution C for ultrasonic treatment to obtain a cotton piece D, freeze-drying the obtained cotton piece D to obtain a cotton piece E, and carbonizing and calcining the obtained cotton piece E to obtain the nitrogen-doped carbon/stannic oxide flexible composite film.

2. The method for preparing the nitrogen-doped carbon/tin dioxide flexible composite film according to claim 1, wherein the specific operation of cleaning and drying the obtained sheet sample comprises the following steps:

and (3) alternately cleaning the obtained sheet sample by using deionized water, acetone and ethanol for 3 times, and naturally drying at room temperature or drying at 25 ℃.

3. The method for preparing the nitrogen-doped carbon/tin dioxide flexible composite film according to claim 1, wherein K is₂SnO₃·3H₂The material ratio of O to water is 0.2-1.5 g: 40-80 mL.

4. The method for preparing the nitrogen-doped carbon/tin dioxide flexible composite film according to claim 3, wherein K is₂SnO₃·3H₂The material ratio of O to urea is 0.2-1.5 g: 1.5-3.5 g.

5. The preparation method of the nitrogen-doped carbon/tin dioxide flexible composite film according to claim 1, wherein the time of ultrasonic treatment is 1-2 h.

6. The method for preparing the nitrogen-doped carbon/tin dioxide flexible composite film according to claim 1, wherein the operating parameters of the carbonization treatment comprise: carbonizing at 500-900 ℃ for 5-9 hours, wherein the atmosphere parameters of the carbonization treatment comprise: introducing 100-600 sccm of nitrogen.

7. The method for preparing the nitrogen-doped carbon/tin dioxide flexible composite film according to claim 1, wherein the solution C is obtained by uniformly dispersing urea in the solution B in a stirring manner, and the stirring time is 1-2 hours.

8. The nitrogen-doped carbon/tin dioxide flexible composite film prepared by the preparation method of any one of claims 1 to 7.

9. The use of the nitrogen-doped carbon/tin dioxide flexible composite film of claim 8 as a negative electrode material of a sodium ion battery.

Technical Field

The invention belongs to the technical field of sodium ion batteries, and relates to a nitrogen-doped carbon/tin dioxide flexible composite film, and a preparation method and application thereof.

Background

With the ever-increasing consumption of fossil fuels by modern life and industrial production, the world is facing global energy challenges and severe environmental issues. There is therefore a great interest in the use of renewable energy sources such as solar, wind and tidal energy. How to efficiently store intermittent renewable energy sources is one of the most important things people face today. As an electrochemical energy storage device, the lithium ion battery has the advantages of high energy density, long service life, low self-discharge characteristic, and the like, and is one of the most potential rechargeable energy storage devices. However, due to the limited natural reserves of lithium resources, it is not practical to pursue over-large scale production of lithium ion batteries in the long term. Because of abundant sodium resource reserves, sodium ion batteries have received increasing attention in recent years as a potential substitute for lithium ion batteries. The negative electrode material is used as an important component of the sodium ion battery, and the sodium storage performance of the sodium ion battery is determined to a great extent.

Tin and tin-based materials have become the focus of research in recent years due to their resource abundance and environmental friendliness. In addition, the research finds that the tin-based material has excellent sodium storage performance as the negative electrode material of the sodium-ion battery. Wherein the theoretical capacity is 782 mAh.g^-1SnO of₂Is considered to be the most promisingReplacing one of the candidate materials for commercial graphite anodes. SnO₂Can generate reversible alloying reaction with Na (4SnO₂+31Na⁺+31e^-＝Na₁₅Sn₄+8Na₂O), theoretically, the capacity of the alloy can reach 1378mAh g^-1. Further, SnO₂The lithium ion battery cathode material also has the advantages of low price, environmental friendliness and the like, and is likely to become an excellent cathode material of a sodium ion battery. However, the intercalation of sodium ions during charge and discharge is inevitably accompanied by a large volume expansion phenomenon of the host material, resulting in pulverization and aggregation of the electrode material, resulting in a sharp drop in sodium storage capacity. In addition, since the surface energy of the nanoparticle is large, its agglomeration is severe and the internal conductivity is poor. Therefore, how to effectively disperse SnO₂Particulate, increasing the internal conductivity of a material remains a challenge.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a nitrogen-doped carbon/tin dioxide flexible composite film, a preparation method and application thereof, and solves the problem of SnO₂The particles are difficult to disperse and the conductivity is poor.

The invention adopts the following technical scheme:

a preparation method of a nitrogen-doped carbon/tin dioxide flexible composite film comprises the following steps: compressing cotton, cutting to obtain a sheet sample, cleaning the sheet sample, and drying to obtain a cotton piece A; will K₂SnO₃·3H₂Uniformly dispersing O in water to obtain a solution B, and uniformly dispersing urea in the obtained solution B to obtain a solution C; and (3) placing the obtained cotton piece A in the solution C for ultrasonic treatment to obtain a cotton piece D, freeze-drying the obtained cotton piece D to obtain a cotton piece E, and carbonizing and calcining the obtained cotton piece E to obtain the nitrogen-doped carbon/stannic oxide flexible composite film.

Preferably, the specific operation of drying the obtained sheet sample after cleaning comprises: and (3) alternately cleaning the obtained sheet sample by using deionized water, acetone and ethanol for 3 times, and naturally drying at room temperature or drying at 25 ℃.

Preferably，K₂SnO₃·3H₂The material ratio of O to water is 0.2-1.5 g: 40-80 mL.

Further preferably, K₂SnO₃·3H₂The material ratio of O to urea is 0.2-1.5 g: 1.5-3.5 g.

Preferably, the time of ultrasonic treatment is 1-2 h.

Preferably, the operating parameters of the carbonization process include: carbonizing at 500-900 ℃ for 5-9 hours, wherein the atmosphere parameters of the carbonization treatment comprise: introducing 100-600 sccm of nitrogen.

Preferably, the urea is uniformly dispersed in the obtained solution B by stirring to obtain a solution C, and the stirring time is 1-2 hours.

The other technical scheme of the invention is that the nitrogen-doped carbon/tin dioxide flexible composite film is prepared by adopting the preparation method.

The invention also provides the application of the nitrogen-doped carbon/tin dioxide flexible composite film as a negative electrode material of a sodium ion battery.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides nitrogen-doped carbon/stannic oxide (N-C @ SnO)₂) The preparation method of the flexible composite film adopts simple dissolution dispersion impregnation treatment and carbonization calcination to prepare the N-C @ SnO₂The preparation method of the flexible composite film has simple synthesis process and easy operation. Wherein SnO can be relieved by using a biocarbon substrate and nitrogen doping₂The particle has poor conductivity, and the transmission path of electrons can be further shortened through the carbon fiber network, so that the reaction kinetics of the electrode are accelerated. And the carbon substrate is made of cotton which is common in nature, so that the method is green and environment-friendly, the materials are easy to obtain, the production cost is reduced, and the industrial popularization and use are facilitated.

The N-C @ SnO flexible composite film prepared by the preparation method is synthesized into an N-C @ SnO film with a shape similar to a octopus tail₂The flexible composite film can effectively disperse SnO₂Particles of sodium ions and SnO₂Reaction providingMore active sites are present. In addition, the carbonized cotton has a strong-conductivity carbon fiber network structure, which is beneficial to the rapid transmission of electrons and increases the conductivity inside the material. Therefore, the nitrogen-doped carbon/stannic oxide flexible composite film prepared by the preparation method effectively solves the problem of SnO₂The particles are difficult to disperse and the conductivity is poor.

The invention also discloses application of the nitrogen-doped carbon/tin dioxide flexible composite film as a negative electrode material of a sodium ion battery. The invention relates to N-C @ SnO₂A flexible composite film in which SnO is effectively dispersed by means of carbon fibers₂The particles and the carbon fibers have strong conductivity and can effectively make up SnO₂Poor conductivity of the particles. Therefore, the lithium iron phosphate can be directly used as a self-supporting electrode, and can be cut into a battery negative plate with the required size specification by a cutting machine under the actual use condition, and then the battery negative plate is assembled into a button cell.

Drawings

FIG. 1 is N-C @ SnO in example VI₂SEM pictures of the flexible composite film under different times; wherein (a) is × 500, (b) is × 2000, and (c) is × 2500;

FIG. 2 is N-C @ SnO in EXAMPLE VII₂SEM image of flexible composite film.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention provides nitrogen-doped carbon/stannic oxide (N-C @ SnO)₂) The preparation method of the flexible composite film comprises the following steps:

s1 Cotton flake pretreatment and non-carbonized Cotton flake/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces with deionized water, acetone and ethanol for 3 times, and naturally drying the cubic pieces at room temperature or drying the cubic pieces at 25 ℃ to obtain cotton pieces A; then, 0.2-1.5 g K₂SnO₃·3H₂Mixing O with 40-80 mL of deionized water, and stirring for 1 hour to obtain a solution B; then, adding 1.5-3.5 g of urea into the solution B, and continuing stirring for 1-2 hours to obtain a solution C; placing the cotton piece A into the solution C for mixing, and then carrying out ultrasonic treatment for 1-2 hours to obtain a cotton piece D, namely obtaining non-carbonized cotton piece/SnO₂Compounding a film;

s2, octopus-shaped nitrogen-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂) The preparation of (1):

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton slice E in a tubular furnace at 500-900 ℃ for 5-9 hours, and introducing 100-600 sccm nitrogen to obtain a carbonized cotton slice F, namely an octopus-tail-shaped N-C @ SnO₂A flexible composite film.

N-C @ SnO prepared by adopting preparation method₂The flexible composite film is green octopus-tail-shaped N-C @ SnO₂A flexible composite film. The N-C @ SnO₂Flexible compositeThe synthetic film is used as the cathode material of the sodium ion battery and assembled into the button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film has integrity and can be directly used as a self-supporting electrode and cut into a negative plate with the diameter of 10mm for an experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

The invention is described in further detail below with reference to the accompanying drawings:

octopus-tail-shaped N-C @ SnO₂The SEM of the flexible composite film is shown in fig. 1, and specifically in fig. 1 (a). It is evident from the figure that N-C @ SnO₂The flexible composite film is of a three-dimensional carbon fiber network structure, and is beneficial to the rapid transmission of electrons in the film.

The invention will be further illustrated with reference to specific examples:

example 1

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and drying the cubic pieces at 25 ℃ to obtain cotton pieces A; then, 0.2g K was added₂SnO₃·3H₂Mixing O with 40mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 1.5g of urea, and stirring for 1 hour to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and performing ultrasonic treatment for 1 hour to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton piece E in a tubular furnace at 500 ℃ for 5 hours, and introducing 100sccm nitrogen to obtain a carbonized cotton piece F, namely octopus-tail-shaped N-C @ SnO₂A flexible composite film.

The N-C @ SnO₂The flexible composite film is applied as a negative electrode material of a sodium ion battery and assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for the experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

Example 2

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and drying the cubic pieces at 25 ℃ to obtain cotton pieces A; then, 0.4g K₂SnO₃·3H₂Mixing O with 50mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 1.8g of urea, and stirring for 1.5 hours to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and performing ultrasonic treatment for 1 hour to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, the cotton piece E is carbonized in a tube furnace for 6 hours at 600 ℃, and nitrogen of 200sccm is introduced to obtain the carbonized cotton pieceCotton flake F, i.e. octopus-tail-shaped N-C @ SnO₂A flexible composite film.

The N-C @ SnO₂The flexible composite film is applied as a negative electrode material of a sodium ion battery and assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for the experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

Example 3

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and drying the cubic pieces at 25 ℃ to obtain cotton pieces A; then, 0.6g K₂SnO₃·3H₂Mixing O with 60mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 2.0g of urea, and stirring for 1.5 hours to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and then carrying out ultrasonic treatment for 1.5 hours to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton piece E in a tubular furnace at 650 ℃ for 7 hours, and introducing nitrogen of 300sccm to obtain a carbonized cotton piece F, namely octopus-tail-shaped N-C @ SnO₂A flexible composite film.

The N-C @ SnO₂Flexible composite film as sodium ionThe cathode material of the cell is applied to be assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for the experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

Example 4

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and drying the cubic pieces at 25 ℃ to obtain cotton pieces A; then, 1.0g K₂SnO₃·3H₂Mixing O with 65mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 2.2g of urea, and stirring for 2 hours to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and then carrying out ultrasonic treatment for 1.5 hours to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton slice E in a tube furnace at 700 ℃ for 6.5 hours, and introducing nitrogen of 400sccm to obtain a carbonized cotton slice F, namely an octopus-tail-shaped N-C @ SnO₂A flexible composite film. Octopus-tail-shaped N-C @ SnO₂The SEM of the flexible composite film is shown in fig. 1 (a).

The N-C @ SnO₂The flexible composite film is applied as a negative electrode material of a sodium ion battery and assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for the experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

Example 5

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and naturally drying the cubic pieces at room temperature to obtain cotton pieces A; then, 1.0g K₂SnO₃·3H₂Mixing O with 70mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 2.6g of urea, and stirring for 1 hour to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and performing ultrasonic treatment for 2 hours to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton piece E in a tubular furnace at 750 ℃ for 8 hours, and introducing nitrogen of 450sccm to obtain a carbonized cotton piece F, namely octopus-tail-shaped N-C @ SnO₂A flexible composite film.

The N-C @ SnO₂The flexible composite film is applied as a negative electrode material of a sodium ion battery and assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for an experimental battery by a cutting machine。

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

Example 6

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and drying the cubic pieces at 25 ℃ to obtain cotton pieces A; then, 1.2g K₂SnO₃·3H₂Mixing O with 80mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 2.8g of urea, and stirring for 2 hours to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and performing ultrasonic treatment for 2 hours to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton piece E in a tubular furnace at 800 ℃ for 8 hours, and introducing 500sccm of nitrogen to obtain a carbonized cotton piece F, namely an octopus-tail-shaped N-C @ SnO₂A flexible composite film. Under the condition, the octopus tail shape is N-C @ SnO₂SEM of the flexible film is shown in FIG. 1 (a).

The N-C @ SnO₂The flexible composite film is applied as a negative electrode material of a sodium ion battery and assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for the experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

Example 7

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and drying the cubic pieces at 25 ℃ to obtain cotton pieces A; then, 1.4g K₂SnO₃·3H₂Mixing O with 75mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 3.0g of urea, and stirring for 1.3 hours to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and performing ultrasonic treatment for 2 hours to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton slice E in a tubular furnace at 850 ℃ for 8.5 hours, and introducing 550sccm nitrogen to obtain a carbonized cotton slice F, namely an octopus-tail-shaped N-C @ SnO₂A flexible composite film. Under the condition, the octopus tail shape is N-C @ SnO₂The SEM of the flexible composite film is shown in fig. 2.

The N-C @ SnO₂The flexible composite film is applied as a negative electrode material of a sodium ion battery and assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for the experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1;the diaphragm is a celgard 2400 film; the order of assembling the battery is that a negative electrode shell, a sodium sheet, a diaphragm, a negative electrode sheet, a gasket, a spring piece and a positive electrode shell are assembled into a button battery in a glove box filled with inert atmosphere.

Example 8

Step 1, pretreatment of cotton piece and non-carbonized cotton piece/SnO₂Preparing a composite film:

firstly, pretreating cotton, peeling and compressing the cotton, then cutting the cotton into cubic pieces of 2cm multiplied by 0.1cm, alternately cleaning the cubic pieces for 3 times by using deionized water, acetone and ethanol, and naturally drying the cubic pieces at room temperature to obtain cotton pieces A; then, 1.5g K₂SnO₃·3H₂Mixing O with 80mL of deionized water, and stirring for 1 hour to obtain a solution B; mixing the solution B with 3.5g of urea, and stirring for 1.7 hours to obtain a solution C; and (3) placing the cotton piece A into the solution C, mixing, and performing ultrasonic treatment for 2 hours to obtain a cotton piece D. Thus obtaining the non-carbonized cotton piece/SnO₂And (3) compounding the film.

Step 2, octopus-shaped N-doped carbon/SnO₂Flexible composite film (N-C @ SnO)₂Flexible composite film) preparation:

carrying out freeze drying on the cotton piece D to obtain a cotton piece E; finally, carbonizing the cotton piece E in a tubular furnace at 900 ℃ for 9 hours, and introducing nitrogen of 600sccm to obtain a carbonized cotton piece F, namely an octopus-tail-shaped N-C @ SnO₂A flexible composite film.

The N-C @ SnO₂The flexible composite film is applied as a negative electrode material of a sodium ion battery and assembled into a button cell.

The specific method for assembling the button cell is as follows: N-C @ SnO₂The flexible composite film is directly used as a self-supporting electrode and is cut into a negative plate with the diameter of 10mm for the experimental battery by a cutting machine.

Taking metal sodium as a counter electrode; the electrolyte is NaPF₆Mixing the ethyl carbonate and the dimethyl carbonate solution according to the volume ratio of 1: 1; the diaphragm is a celgard 2400 film; the order of assembling the battery is cathode shell, sodium sheet, diaphragm, cathode sheet, gasket, spring sheet, anode shell and glove filled with inert atmosphereThe box is assembled into a button cell.

In conclusion, the invention provides green octopus-tail-shaped N-C @ SnO₂Flexible composite film and preparation method thereof, wherein simple impregnation and tubular furnace calcination are adopted to prepare N-C @ SnO₂The flexible composite film has simple synthesis process and easy operation. And moreover, the carbon substrate is made of cotton which is common in nature, so that the carbon substrate is green and environment-friendly, and the materials are easily available. Synthesized N-C @ SnO with shape similar to octopus tail₂The flexible composite film can effectively disperse SnO₂Particles of sodium ions and SnO₂The reaction provides more active sites. In addition, the carbonized cotton has a strong-conductivity carbon fiber network structure, which is beneficial to the rapid transmission of electrons and increases the conductivity inside the material.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.