LU509927B1

LU509927B1 - Single-walled carbon nanotube composite flexible positive electrode, and preparation method and use thereof

Info

Publication number: LU509927B1
Application number: LU509927A
Authority: LU
Inventors: Hailin Shen
Original assignee: Changzhou Inst Technology
Priority date: 2024-05-31
Filing date: 2025-05-29
Publication date: 2025-12-01
Also published as: CN118572019A

Abstract

The present invention relates to the technical field of flexible positive electrodes and zinc ion batteries, and specifically to a single-walled carbon nanotube composite flexible positive electrode, and a preparation method and a use thereof. In the present invention, a nano-dispersion is formed by single-walled carbon nanotubes, and γ-MnO2 particles and the single-walled carbon nanotube dispersion are ultrasonically dispersed in the presence of a binder to bond and intercalate the γ-MnO2 particles into a conductive network, resulting in a self-supporting single-walled carbon nanotube composite flexible positive electrode. The SWCNTs/γ-MnO2 composite flexible positive electrode of the present invention includes a single-walled carbon nanotube flexible conductive substrate, and a γ-MnO2 zinc-intercalated reactant, overcoming the problem of poor flexibility of titanium foil substrates while ensuring the electrochemical performance of γ-MnO2. The composite flexible positive electrode of the present invention can be applied to aqueous zinc ion batteries to manufacture flexible batteries. The preparation method of flexible electrodes according to the present invention is low in costs, simple in devices, and convenient in operation.

Description

SINGLE-WALLED CARBON NANOTUBE COMPOSITE FLEXIBLE POSITIVE LU509927

ELECTRODE, AND PREPARATION METHOD AND USE THEREOF

TECHNICAL FIELD

[0001] The present invention belongs to the technical field of flexible positive electrodes and zinc ion batteries, and specifically relates to a single-walled carbon nanotube composite flexible positive electrode, a preparation method and a use thereof.

BACKGROUND

[0002] With the rapid development of wearable electronic devices and flexible electronic technologies, the demand for high-performance, lightweight, and bendable flexible battery technologies is becoming increasingly urgent. Traditional rigid batteries, due to their inherent volume and shape limitations, are no longer able to meet the demands of modern electronic devices for flexible and bendable batteries. Therefore, the development of flexible batteries has become one of the current research hotspots.

[0003] In flexible batteries, flexible electrode materials are the key factor determining battery performance. Among them, flexible zinc ion batteries have shown great potential for application in large-scale energy storage systems due to their high safety, good stability, and cost-effectiveness. Especially the positive electrode of a zinc ion battery has a significant impact on the overall performance of the battery. Due to the similar hydrated ion radius of zinc to lithium, manganese dioxide as a positive electrode can achieve good ion intercalation and deintercalation performance in zinc ion batteries. In addition, manganese dioxide, as a traditional and high-performance positive electrode, has a high theoretical specific capacity and good environmental compatibility, making it an ideal choice for the positive electrode of the flexible zinc ion battery.

[0004] However, manganese dioxide materials themselves also have some limitations, such as relatively low electrical conductivity and insufficient mechanical flexibility. In order to overcome these limitations, researchers have begun to explore the combination of the excellent electrochemical performance of traditional manganese dioxide positive electrodes with the mechanical flexibility of flexible substrate materials, providing a possibility for the development of novel flexible batteries. Scientists are constantly exploring new synthesis methods and structural designs, such as the use of nanotechnologies to optimize the surface and pore structure of manganese dioxide, or combination with flexible conductive substrates, such as conductive polymers, carbon nanotubes, and grapheme, to enhance conductivity, and improve flexibility and cycling stability of the battery. However, the above-mentioned flexible conductive substrates are 1 prone to affect the electrochemical performance due to the inherent characteristics of the,509927 material.

[0005] For example, during the study on the performance of carbon nanotubes (CNTs), researchers found that there is a strong Van der Waals force among CNTs, and the CNTs have a high aspect ratio, making the CNTs prone to aggregation or entanglement, increasing the difficulty of dispersion and affecting the electrochemical performance. Based on this, the researchers used single-walled carbon nanotubes (SWCNTSs) as a matrix, and adopted graphene oxide (GO) to assist in the dispersion of SWCNTs. The GO was uniformly coated around the

SWCNTs, to prevent the SWCNTs from aggregating. Then, an SWCNTs-based electrode material was prepared by combining manganese dioxide with the modified SWCNTs. However, the introduced GO coated on the surface of the SWCNTS increased rigidity and hardness of the material, resulting in poor flexibility of the prepared electrode.

SUMMARY

[0006] An objective of the present invention is to provide a single-walled carbon nanotube composite flexible positive electrode, and a preparation method and a use thereof, in order to solve the problems of poor dispersibility in the preparation of positive electrodes by combining manganese dioxide with SWCNTs, and poor flexibility due to the introduction of GO in the prior art.

[0007] To achieve the above objective, the present invention provides the following technical solutions.

[0008] A first aspect of the present invention provides a preparation method of a single-walled carbon nanotube composite flexible positive electrode, including steps of:

[0009] dispersing single-walled carbon nanotubes in a solvent, to prepare a dispersion of the single-walled carbon nanotubes; and

[0010] mixing the dispersion of the single-walled carbon nanotubes with y-MnO, particles, conducting ultrasonic dispersion in presence of a binder, and performing physical film formation to bond the y-MnO- particles and intercalate the y-MnO; particles with the single-walled carbon nanotubes to form a conductive network, to obtain a self-supporting single-walled carbon nanotube composite flexible positive electrode.

[0011] In the present invention, a nano-dispersion is formed first with the single-walled carbon nanotubes, and the y-MnQ; particles and the nano-dispersion are ultrasonically dispersed in the presence of the binder. On the one hand, the high-frequency vibration of ultrasound can generate intense turbulence and tiny cavitation bubbles in the liquid, thereby producing high-strength shear and emulsification effects. The shear and emulsification effects can effectively destroy the surface tension of solid particles, allowing the solid particles to disperse in the liquid. On the 2 other hand, the added binder can stabilize the y-MnOz particles during the dispersion process, ;509927 and prevent the y-MnO, particles from aggregation. Through the physical film formation, the y-MnO; particles in the dispersion system are bonded, and intercalated with the single-walled carbon nanotubes to form the conductive network. Also, self-supporting can be achieved, namely, the flexible electrode does not need to have a metal substrate as a substrate. Therefore, this flexible electrode has excellent portability and flexibility.

[0012] By combining SWCNTs with y-MnO;, the present invention overcomes the disadvantages of poor dispersibility in the preparation of positive electrodes by combining manganese dioxide with single-walled carbon nanotubes, and poor flexibility due to the introduction of GO in the prior art, as well as the shortcoming of a low specific capacity of

SWCNTs. The advantages of both materials are fully utilized to improve the electrochemical performance of the positive electrodes.

[0013] In a preferred embodiment, a mass ratio of the single-walled carbon nanotubes to the y-MnO) particles is 1:(0.2 to 1). Preferably, the mass ratio of the single-walled carbon nanotubes to the y-MnO; particles is 1:(0.5 to 0.8), and further preferably 1:0.5. For example, the mass ratio of the single-walled carbon nanotubes to the y-MnOz particles is 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1, etc. With the increase of an amount of the y-MnO; particles, the initial discharge specific capacity of the battery shows an increasing trend, and the electrochemical cycling stability of the battery shows a basically increasing trend, reaching a maximum when the mass ratio of SWCNTS to y-MnO- is 1:0.5, followed by a slight decrease.

[0014] In a preferred embodiment, the binder is a polyvinylidene fluoride solution or a carboxymethyl cellulose solution; a mass percentage of the binder is 10% (w/w); and a ratio of the single-walled carbon nanotubes to the binder is 1 g : (15 mL to 25 mL), and preferably 1 g : mL. The binder functions to stabilize the y-MnO, particles during the dispersion process, and thus prevent aggregation of the y-MnQ; particles. During the film formation through filtration, the binder functions to connect various components, to prevent deintercalation among the various components.

[0015] In a preferred embodiment, a ratio of the single-walled carbon nanotubes to the solvent is (0.5 gto 1 g) : 1 L, for example, 0.5 g: 1L,0.6g:1L,0.7g:1L,08g:1L,0.9g:1L,0r1 g : 1 L. If the concentration of the single-walled carbon nanotubes is too high, it becomes difficult for the single-walled carbon nanotubes to disperse, and the single-walled carbon nanotubes are prone to aggregation; and if the concentration 1s too low, the later effect in the film formation through filtration will be affected, thereby affecting the battery performance.

[0016] In a preferred embodiment, the single-walled carbon nanotubes are dispersed in a solvent as follows.

[0017] The single-walled carbon nanotubes are mixed with the solvent for ultrasonic dispersion 3 at an ultrasonic power of 200 W to 400 W, for example, 200 W, 300 W, or 400 W, PU509927 fragmentation dispersion. When a dispersion of the single-walled carbon nanotubes is prepared through the ultrasonic dispersion, a shear dispersion effect will affect the subsequent dispersion and bonding of the y-MnO> particles. Preferably, the ultrasonic dispersion in the preparation of the dispersion of the single-walled carbon nanotubes is conducted for 1 hour to 3 hours.

[0018] In a preferred embodiment, the solvent is any one of N-methylpyrrolidone, ethanol, and water, and preferably N-methylpyrrolidone. The solvent is selected mainly according to a concentration and stability of the dispersion that can be achieved.

[0019] In a preferred embodiment, the ultrasonic dispersion is conducted in the presence of the binder at an ultrasonic power of 400 W to 600 W, for example, 400 W, 500 W, or 600 W.

Preferably, the ultrasonic dispersion is conducted in the presence of the binder for 1 hour to 3 hours.

[0020] In a preferred embodiment, an average particle diameter of the single-walled carbon nanotubes in the dispersion of the single-walled carbon nanotubes is 1 nm to 6 nm.

[0021] In a preferred embodiment, the y-MnO; particles have a particle diameter of 0.5 um to 3 um, and an average particle diameter of 0.5 um to 0.6 um.

[0022] In a preferred embodiment, the physical film formation is achieved by forming a film on a surface of a filter layer from an ultrasonically dispersed liquid through vacuum filtration. The filter layer can be selected as actually required, and is preferably any one of dust-free filter cloth, filter paper, and a filter membrane.

[0023] In a preferred embodiment, after the physical film formation, drying is further included to separate the self-supporting single-walled carbon nanotube composite flexible positive electrode from the filter layer. Preferably, the drying is conducted at a temperature of 60°C to 70°C for 5 minutes to 15 minutes.

[0024] A second aspect of the present invention provides a single-walled carbon nanotube composite flexible positive electrode prepared by the preparation method described in the first aspect. The composite flexible positive electrode of the present invention is mainly prepared by bonding and intercalating y-MnO, together through SWCNTS to form a conductive network, and self-supporting, lightweight and flexible characteristics are also achieved.

[0025] A third aspect of the present invention provides a use of the single-walled carbon nanotube composite flexible positive electrode described in the second aspect, as positive electrode, in preparation of a flexible aqueous zinc ion battery.

[0026] In a preferred embodiment, the flexible aqueous zinc ion battery is assembled with an

SWCNTs/y-MnO,, flexible positive electrode as a positive electrode, a Zn sheet as a negative electrode, a zinc sulfate aqueous solution as an electrolyte, and a glass fiber separator as a separator. 4

[0027] Compared with the prior art, the present invention has advantages as follows: LU509927

[0028] 1. The method of the present invention mainly utilizes the SWCNTS dispersion and the y-MnO; particles for ultrasonic dispersion in the presence of the binder, to bond and intercalate y-MnO; together, and form a conductive network. This overcomes the disadvantages of the poor dispersibility in the preparation of a positive electrode by combining manganese dioxide with single-walled carbon nanotubes and the poor flexibility after the introduction of GO in the prior art, as well as a shortcoming of the low specific capacity of SWCNTs. On the basis of meeting the flexibility requirement, the present method improves the electrochemical performance of the aqueous zinc ion battery.

[0029] 2. By adjusting the mass ratio of SWCNTs to y-MnO, particles, the present invention prepares a flexible composite positive electrode with a good specific capacity, for use as a positive electrode of the flexible aqueous zinc ion battery. Therefore, the present invention has advantages of low costs, simple operation steps, safety, and controllability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 shows morphology of an SWCNTs/y-MnQO; flexible positive electrode prepared in Example 1.

[0031] FIG. 2 shows electrochemical performance of an aqueous zinc ion battery assembled with the SWCNTs/y-MnO, flexible positive electrode prepared in Example 1.

[0032] FIG. 3 shows a scanning electron microscope (SEM) image of single-walled carbon nanotubes.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to clarify the objective, the technical solutions, and the advantages of the present invention, the present invention will be further explained below in detail in conjunction with the examples. It should be understood that the specific examples described here are only intended to explain the present invention but not to limit the present invention.

[0034] Based on the examples of the present invention, all other examples obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present invention.

[0035] It should be understood that the terms used in the present invention are only intended to describe specific examples but not to limit the present invention. Additionally, it is to be understood that, for the numerical range in the present invention, each in-between value between an upper limit and a lower limit of the range is also specifically disclosed. Any in-between value within any stated values or range, as well as any smaller range between the in-between values between any other stated values or the range are also included in the present invention. Upper limits and lower limits in these smaller ranges can be independently included within or excluded,509927 from the range.

[0036] Manganese dioxide, as a traditional and high-performance positive electrode material, has high theoretical specific capacity and good environmental compatibility, and can achieve good ion intercalation and deintercalation performance in zinc ion batteries, becoming an ideal choice for the positive electrode material in the flexible zinc ion battery.

[0037] However, manganese dioxide materials themselves also suffer from some limitations, such as relatively low conductivity and insufficient mechanical flexibility. To overcome these limitations, researchers have begun to explore the combination of manganese dioxide with materials having high conductivity and excellent mechanical flexibility, to prepare high-performance flexible electrode materials.

[0038] SWCNTs, as a material with excellent physical and chemical properties, have become an ideal material for manufacturing high-performance flexible electronic devices due to the high specific surface area, excellent electrical conductivity and thermal conductivity, and outstanding mechanical flexibility. SWCNTs can provide a large number of active sites, to contribute to electrochemical reactions. Meanwhile, the high electrical conductivity and thermal conductivity of SWCNTS can accelerate the transfer of electrons and ions, improving the charge and discharge efficiency of the battery. The strength and the flexibility ensure that the electrode can maintain stable performance even when bent or stretched.

[0039] Therefore, the applicant proposes the idea of combining SWCNTs with manganese dioxide to prepare an SWCNTs/manganese dioxide composite flexible positive electrode, which will become an effective way to improve the performance of flexible zinc ion batteries. This composite material not only combines the electrochemical activity of manganese dioxide with the high electrical conductivity of SWCNTS, but also enhances the mechanical flexibility of the electrode through the introduction of SWCNTs, providing a possibility for achieving more efficient and stable flexible batteries.

[0040] In summary, based on the development needs of flexible electronic devices and zinc ion batteries, and respective advantages of manganese dioxide and SWCNTS, it is of great research significance and application prospects to develop novel SWCNTs/manganese dioxide composite flexible positive electrodes.

[0041] However, it has been found in research processes of CNTs that, there is a strong Van der

Waals force among the CNTs, and the CNTs have a high aspect ratio, making the CNTs prone to aggregation or entanglement, increasing the difficulty of dispersion and affecting the electrochemical performance. SWCNTs face the same problem. Based on this, researchers use

SWCNTs as a matrix and use GO to assist in the dispersion of the SWCNTs, so that the GO is uniformly coated around the SWCNTs to prevent the SWCNTs from aggregating. Then, an 6

SWCNT-based electrode material is prepared by combining manganese dioxide with the,509927 modified SWCNTs. However, the introduced GO coated on the surface of the SWCNTs increases rigidity and hardness of the material, resulting in poor flexibility of the prepared electrode. Moreover, the researchers have also found during the preparation process of the

SWCNT-based electrode material that, manganese dioxide loaded on the surface of GO is very uneven. In some areas, large agglomerates of manganese dioxide appear, making it difficult to achieve efficient and uniform deposition of manganese dioxide on the GO surface. The uneven deposition of manganese dioxide may easily affect the relevant electrochemical performance of the electrode material.

[0042] In addition, titanium foil is commonly used as a substrate in the prior art to prepare manganese dioxide positive electrode materials, but this positive electrode material also has the problem of poor flexibility.

[0043] Accordingly, the present invention utilizes the SWCNTs dispersion and the y-MnO2 particles for ultrasonic dispersion in the presence of the binder to bond and intercalate y-MnO, together, to form a conductive network. This overcomes the problems of poor dispersibility in the preparation of a positive electrode by combining manganese dioxide with SWCNTs, and poor flexibility after the introduction of GO in the prior art, as well as the shortcomings of poor flexibility of the manganese dioxide positive electrode on a titanium foil substrate and a low specific capacity of the SWCNTSs. On the basis of meeting the flexibility requirement, the present invention improves the electrochemical performance of aqueous zinc ion batteries.

[0044] The technical solutions of the present invention are further explained below in conjunction with specific examples.

[0045] All the methods described in the following examples are conventional methods unless otherwise specified. All the reagents and materials are commercially available unless otherwise specified.

[0046] In the following examples, “SWCNTs” represents single-walled carbon nanotubes; and “y-MnO2” represents y-manganese dioxide. The SWCNTs were purchased from a Russian company OCSiAl, with a purity of over 99.9%. An SEM image of the SWCNTS is shown in FIG. 3. y-Manganese dioxide was purchased from Chizhou Jinyan New Energy Technology Co., Ltd.

The y-manganese dioxide particles had a particle diameter of 0.5 um to 3 um, and an average particle diameter of 0.5 um to 0.6 um.

[0047] Example 1

[0048] A preparation method of an SWCNTs/y-MnO, composite flexible positive electrode included the following steps:

[0049] Step S1. Preparation of SWCNTS suspension

[0050] 1 g of high-purity SWCNTs and 1000 mL of N-methylpyrrolidone were mixed, stirred 7 uniformly, and ultrasonically treated with a cell disruptor at a 200 W power for 1 hour, to obtai 599927 an SWCNTs suspension.

[0051] Step S2. Formulation of SWCNTs/y-MnO; mixture

[0052] The SWCNTSs suspension obtained in the Step S1 and 500 mg of y-MnO, particles were mixed, and mechanically stirred for 30 minutes to obtain a mixture; and a 10% (w/w) polyvinylidene fluoride solution was formulated as a binder, 20 mL of the binder was added dropwise into the mixture, and dispersion was conducted for 1 hour at a 300 W ultrasonic power, to obtain an SWCNTs/y-MnO; suspension.

[0053] Step S3. Preparation of SWCNTs/y-MnOz flexible positive electrode

[0054] The SWCNTs/y-MnO; suspension obtained in the Step S2 was formed into a film through vacuum filtration as follows. À dust-free filter cloth with an area of 40 cm” was cut and placed inside a funnel in a manner of fully adhering to the funnel wall without bubbles. 50 mL of the SWCNTs/y-MnO; suspension obtained in the Step S2 was slowly poured into the funnel, and a pump was turned on for filtration. The SWCNTs/y-MnOz suspension was filtered onto a side of the dust-free filter cloth, and dried for 10 minutes. The SWCNTs/y-MnO; film was removed from the dust-free filter cloth, to obtain a pure SWCNTs/y-MnO, flexible positive electrode.

[0055] Example 2

[0056] A preparation method of an SWCNTs/y-MnO;2 composite flexible positive electrode included the following steps:

[0057] Step S1. Preparation of SWCNTS suspension

[0058] 1 g of high-purity SWCNTs and 1000 mL of N-methylpyrrolidone were mixed, stirred uniformly, and ultrasonically treated with a cell disruptor at a 400 W power for 1 hour, to obtain an SWCNTs suspension.

[0059] Step S2. Formulation of SWCNTs/y-MnO; mixture

[0060] The SWCNTSs suspension obtained the Step S1 and 200 mg of y-MnO, particles were mixed, and mechanically stirred for 30 minutes to obtain a mixture; and a 10% (w/w) polyvinylidene fluoride solution was formulated as a binder, 20 mL of the binder was added dropwise into the mixture, and dispersion was conducted for 1 hour at a 300 W ultrasonic power, to obtain an SWCNTs/y-MnO; suspension.

[0061] Step S3. Preparation of SWCNTs/y-MnOz flexible positive electrode

[0062] The SWCNTs/y-MnO; suspension obtained in the Step S2 was formed into a film through vacuum filtration as follows. À dust-free filter cloth with an area of 40 cm” was cut and placed inside a funnel in a manner of fully adhering to the funnel wall without bubbles. 50 mL of the SWCNTs/y-MnO; suspension obtained in the Step S2 was slowly poured into the funnel, and a pump was turned on for filtration. The SWCNTs/y-MnOz suspension was filtered onto a side of the dust-free filter cloth, and dried for 10 minutes. The SWCNTs/y-MnO; film was removed 8 from the dust-free filter cloth, to obtain a pure SWCNTs/y-MnO; flexible positive electrode. | 599927

[0063] Example 3

[0064] A preparation method of an SWCNTs/y-MnO, composite flexible positive electrode included the following steps:

[0065] Step S1. Preparation of SWCNTS suspension

[0066] 1 g of high-purity SWCNTs and 1000 mL of N-methylpyrrolidone were mixed, stirred uniformly, and ultrasonically treated with a cell disruptor at a 400 W power for 1 hour, to obtain an SWCNTs suspension.

[0067] Step S2. Formulation of SWCNTs/y-MnO; mixture

[0068] The SWCNTSs suspension obtained in the Step S1 and 800 mg of y-MnO, particles were mixed, and mechanically stirred for 30 minutes to obtain a mixture; and a 10% (w/w) polyvinylidene fluoride solution was formulated as a binder, 20 mL of the binder was added dropwise into the mixture, and dispersion was conducted for 1 hour at a 300 W ultrasonic power, to obtain an SWCNTs/y-MnO; suspension.

[0069] Step S3. Preparation of SWCNTs/y-MnOz flexible positive electrode

[0070] The SWCNTs/y-MnO; suspension obtained in the Step S2 was formed into a film through vacuum filtration as follows. À dust-free filter cloth with an area of 40 cm” was cut and placed inside a funnel in a manner of fully adhering to the funnel wall without bubbles. 50 mL of the SWCNTs/y-MnO; suspension obtained in the Step S2 was slowly poured into the funnel, and a pump was turned on for filtration. The SWCNTs/y-MnOz suspension was filtered onto a side of the dust-free filter cloth, and dried for 10 minutes. The SWCNTs/y-MnO; film was removed from the dust-free filter cloth, to obtain a pure SWCNTs/y-MnO, flexible positive electrode.

[0071] Example 4

[0072] A preparation method of an SWCNTs/y-MnO;2 composite flexible positive electrode included the following steps:

[0073] Step S1. Preparation of SWCNTS suspension

[0074] 1 g of high-purity SWCNTs and 1000 mL of N-methylpyrrolidone were mixed, stirred uniformly, and ultrasonically treated with a cell disruptor at a 400 W power for 1 hour, to obtain an SWCNTs suspension.

[0075] Step S2. Formulation of SWCNTs/y-MnO; mixture

[0076] The SWCNTs suspension obtained in the Step S1 and 1000 mg of y-MnQ,; particles were mixed, and mechanically stirred for 30 minutes to obtain a mixture; and a 10% (w/w) polyvinylidene fluoride solution was formulated as a binder, 20 mL of the binder was added dropwise into the mixture, and dispersion was conducted for 1 hour at a 300 W ultrasonic power, to obtain an SWCNTs/y-MnO; suspension.

[0077] Step S3. Preparation of SWCNTs/y-MnOz flexible positive electrode 9

[0078] The SWCNTs/y-MnO, suspension obtained in the Step S2 was formed into a film,509927 through vacuum filtration as follows. A dust-free filter cloth with an area of 40 cm? was cut and placed inside a funnel in a manner of fully adhering to the funnel wall without bubbles. 50 mL of the SWCNTs/y-MnO; suspension obtained in the Step S2 was slowly poured into the funnel, and a pump was turned on for filtration. The SWCNTs/y-MnOz suspension was filtered onto a side of the dust-free filter cloth, and dried for 10 minutes. The SWCNTs/y-MnO; film was removed from the dust-free filter cloth, to obtain a pure SWCNTs/y-MnO, flexible positive electrode.

[0079] Comparative example 1

[0080] A preparation method of an SWCNTs positive electrode included the following steps:

[0081] Step S1. Preparation of SWCNTS suspension

[0082] 1 g of high-purity SWCNTs and 1000 mL of N-methylpyrrolidone were mixed, stirred uniformly, and ultrasonically treated with a cell disruptor at a 200 W power for 1 hour, to obtain an SWCNTs suspension.

[0083] Step S2. Preparation of SWCNTS positive electrode

[0084] The SWCNTs suspension was formed into a film through vacuum filtration. A dust-free filter cloth with an area of 40 cm” was cut and placed inside a funnel in a manner of fully adhering to the funnel wall without bubbles. 50 mL of the SWCNTs suspension was slowly poured into the funnel, and a pump was turned on for filtration. The SWCNTSs suspension was filtered onto a side of the dust-free filter cloth, and dried for 10 minutes. The SWCNTS film was removed from the dust-free filter cloth, to obtain a pure SWCNTs positive electrode.

[0085] Comparative example 2

[0086] A preparation method of a CNTs/y-MnO, composite flexible positive electrode included the following steps:

[0087] Step S1. Preparation of SWCNTS suspension

[0088] 1 g of CNTs and 1000 mL of N-methylpyrrolidone were mixed, stirred uniformly, and ultrasonically treated with a cell disruptor at a 200 W power for 1 hour, to obtain a CNTs suspension.

[0089] Step S2. Formulation of CNTs/y-MnOz mixture

[0090] The CNTs suspension obtained in the Step S1 and 500 mg of y-MnO; particles were mixed, and mechanically stirred for 30 minutes to obtain a mixture; and a 10% (w/w) polyvinylidene fluoride solution was formulated as a binder, 20 mL of the binder was added dropwise into the mixture, and dispersion was conducted for 1 hour at a 300 W ultrasonic power, to obtain a CNTs/y-MnO; suspension.

[0091] Step S3. Preparation of CNTs/y-MnOz flexible positive electrode

[0092] The CNTs/y-MnO; suspension obtained in the Step S2 was formed into a film through vacuum filtration as follows. A dust-free filter cloth with an area of 40 cm” was cut and placed inside a funnel in a manner of fully adhering to the funnel wall without bubbles. 50 mL of the,509927

CNTs/y-MnO; suspension obtained in the Step S2 was slowly poured into the funnel, and a pump was turned on for filtration. The CNTs/y-MnO; suspension was filtered onto a side of the dust-free filter cloth, and dried for 10 minutes. The CNTs/y-MnO, film was removed from the dust-free filter cloth, to obtain a pure CNTs/y-MnO; flexible positive electrode.

[0093] Test 1: Morphology of flexible positive electrode

[0094] FIG. 1 shows the morphology of the SWCNTs/y-MnO; flexible positive electrode prepared in Example 1.

[0095] From FIG. 1, it can be seen that the SWCNTs/y-MnO; flexible positive electrode has a very thin composite film structure, and also has excellent flexibility, allowing for bending well.

[0096] Test 2: Electrochemical performance testing

[0097] A button-type zinc ion battery was assembled with the SWCNTs/y-MnO, flexible positive electrode prepared in the above example as the positive electrode, a Zn sheet as the negative electrode, a 1 M zinc sulfate aqueous solution as the electrolyte, and a glass fiber separator as the separator.

[0098] Within a voltage range of 1.0 V to 1.8 V, and at a current density of 260 mA/g, the initial discharge specific capacity, the discharge specific capacity after 150 cycles, and the discharge specific capacity at a current density of 2 A/g were tested, to evaluate the electrochemical performance of the positive electrodes of the examples. Test results are shown in FIG. 2, and

Table 1 and Table 2.

[0099] FIG. 2 shows the electrochemical performance of the aqueous zinc ion battery assembled with the SWCNTs/y-MnOz flexible positive electrode prepared in Example 1. Where, (a) is a specific capacity - voltage relationship curve of the assembled aqueous zinc ion battery; and (b) is a cycle specific capacity curve and a cycle columbic efficiency curve of the assembled aqueous zinc ion battery.

[0100] From the specific capacity - voltage relationship curve in FIG. 2(a), it can be seen that the shape of the curve is relatively flat, indicating that the capacity decay rate of the battery is relatively slow, the cycle life of the battery is relatively long, and the curves of cycles 22, 23, and 24 overlap each other due to relatively good reversibility.

[0101] From FIG. 2(b), it can be seen that the aqueous zinc ion battery assembled with the

SWCNTs/y-MnQO,, flexible positive electrode of Example 1 has an initial discharge specific capacity of 142 mAh/g, a discharge specific capacity after 150 cycles of 80 mAh/g, and a capacity retention rate after 150 cycles of 56%. This indicates that the flexible positive electrode of Example 1 of the present invention improves the electrochemical performance of the aqueous zinc ion battery while meeting the flexibility requirement.

[0102] Table 1. Comparison of electrochemical performance of SWCNTs/y-MnO, flexible 11 positive electrodes with different mass ratios LU509927

[0103]

Mass ratio“ Initial discharge Discharge specific Capacity retention specific capacity capacity after 150 ratio after 150 cycles (mAh/g) cycles (mAh/g) (%) pee | 0 [ww

[0104] Note: The mass ratio” represents a mass ratio of SWCNTS to y-MnO,.

[0105] It can be seen from the results in Table 1 that, as the amount of y-MnO, increases, the initial discharge specific capacity shows an increasing trend, and both the discharge specific capacity after 150 cycles and the capacity retention rate after 150 cycles show an increasing trend and reach their maximums at a mass ratio of SWCNTs to y-MnO; of 1:0.5, followed by a slight decrease.

[0106] Table 2. Comparison of electrochemical performance of different flexible positive electrodes

[0107]

Flexible positive | Initial discharge Discharge specific Capacity retention electrode specific capacity capacity after 150 ratio after 150 (mAh/g) cycles (mAh/g) cycles (%) anger [wore | we | www

Comparati SWCNTs ve example 1

Comparati CNTs/y-MnO, 146 25 17% ve example 2

[0108] “-” indicates that the SWCNTS could not be used for the positive electrode.

[0109] It can be seen from the results in Table 2 that, although the SWCNTs in Example 1 were replaced with CNTs in Comparative Example 2 to prepare the composite flexible positive electrode, the discharge specific capacity after 150 cycles and the capacity retention ratio after 12

150 cycles of the composite flexible positive electrode of Comparative example 2 were lowef,509927 than those of the composite flexible positive electrode of Example 1. This indicates that, in the above examples of the present invention, the use of the SWCNTs/y-MnQ; flexible positive electrode prepared as follows, as a positive electrode of a flexible aqueous zinc ion battery can improve the electrochemical performance of the aqueous zinc ion battery: ultrasonically dispersing an SWCNTS dispersion and y-MnO; particles in the presence of the binder to bond and intercalate y-MnO, together to form a conductive network, and subjecting the ultrasonically dispersed liquid to film formation on a surface of a filter layer through vacuum filtration.

[0110] The above only shows preferred examples of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. 13

Claims

CLAIMS LU509927

1. À preparation method of a single-walled carbon nanotube composite flexible positive electrode, characterized by comprising the following steps: dispersing single-walled carbon nanotubes in a solvent to prepare a dispersion of the single-walled carbon nanotubes; and mixing the dispersion of the single-walled carbon nanotubes with y-MnO» particles, followed by ultrasonic dispersion in a presence of a binder, and performing physical film formation to bond the y-MnO» particles and intercalate the y-MnOz particles with the single-walled carbon nanotubes to form a conductive network, to obtain a self-supporting single-walled carbon nanotube composite flexible positive electrode.

2. The preparation method of the single-walled carbon nanotube composite flexible positive electrode according to claim 1, characterized in that a mass ratio of the single-walled carbon nanotubes to the y-MnO, particles is 1:(0.2 to 1).

3. The preparation method of the single-walled carbon nanotube composite flexible positive electrode according to claim 2, characterized in that the mass ratio of the single-walled carbon nanotubes to the y-MnO; particles is 1:(0.5 to 0.8).

4. The preparation method of the single-walled carbon nanotube composite flexible positive electrode according to claim 1, characterized in that the binder is a polyvinylidene fluoride solution or a carboxymethyl cellulose solution; and a mass percentage of the binder is 10% (w/w); and a ratio of the single-walled carbon nanotubes to the binder is 1 g : (15 mL to 25 mL).

5. The preparation method of the single-walled carbon nanotube composite flexible positive electrode according to claim 1, characterized in that a ratio of the single-walled carbon nanotubes to the solvent is (0.5 gto 1g): 1 L.

6. The preparation method of the single-walled carbon nanotube composite flexible positive electrode according to claim 1, characterized in that the single-walled carbon nanotubes are dispersed in the solvent by the following steps: mixing the single-walled carbon nanotubes with the solvent, followed by ultrasonic dispersion or fragmentation dispersion; wherein an ultrasonic power is 200 W to 400 W.

7. The preparation method of the single-walled carbon nanotube composite flexible positive electrode according to claim 1, characterized in that the solvent is one of N-methylpyrrolidone, ethanol, and water.

8. The preparation method of the single-walled carbon nanotube composite flexible positive electrode according to claim 1, characterized in that the ultrasonic dispersion is performed in the presence of the binder at an ultrasonic power of 400 W to 600 W. 14

9. A single-walled carbon nanotube composite flexible positive electrode prepared by the LU509927 preparation method according to any one of claims 1 to 8.

10. À use of the single-walled carbon nanotube composite flexible positive electrode according to claim 9 as a positive electrode in a preparation of a flexible aqueous zinc ion battery.