A high-silicon-loaded carbon nanotube composite thin film electrode and a preparation method and application thereof

Abstract

The application discloses a high-silicon-loaded carbon nanotube composite film electrode and a preparation method and application thereof. The preparation method comprises the following steps: providing a nanosilicon dispersion liquid containing nanosilicon, polyvinylpyrrolidone and a solvent; making a continuous carbon nanotube network fully contact with the nanosilicon dispersion liquid, so that the continuous carbon nanotube network and the nanosilicon are continuously and in situ dynamically and uniformly compounded, and are synchronously shrunk and fiberized; through continuous collection of layer-by-layer assembly and drying, a carbon nanotube / nanosilicon composite film is prepared; and then high-temperature carbonization and roller pressing treatment are carried out, so that the high-silicon-loaded carbon nanotube composite film electrode is prepared. The in-situ continuous compounding technology is adopted to prepare the high-silicon-loaded carbon nanotube composite film electrode; the long-range continuous and dense carbon nanotube conductive framework in the electrode can realize high-silicon loading and simultaneously enhance the structural stability of the electrode; and the prepared composite film electrode has excellent tensile and bending resistance, conductivity and lithium storage performance (specific capacity and cycle stability).

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of negative electrode materials, and particularly relates to a high-silicon-loaded carbon nanotube composite thin film electrode and a preparation method and application thereof. BACKGROUND

[0002] New energy in China is developing rapidly, especially new energy vehicles. The resulting "range anxiety" urgently needs to develop lithium ion batteries with higher energy density and cycle life. Using high-capacity silicon material as an active substance and developing high-load and high-performance negative electrodes are important ways to achieve this goal. However, the problems of electrode structure crushing and slow charge transport dynamics caused by the huge volume expansion (> 300%) and low conductivity of silicon material seriously restrict the development and application of high-load silicon negative electrodes.

[0003] Studies have shown that nano-silicon (< 150 nm) can effectively alleviate the volume expansion effect, and CNT is often used as a structural support and conductive framework for silicon-based negative electrodes due to its high mechanical strength, high conductivity, strong deformation adaptability, and high specific surface area. Although high-performance CNT network enhanced nano-silicon-based composite materials have been constructed by using in-situ gas deposition or slurry mixing methods, their excellent performance is usually obtained under the conditions of low silicon loading (< 1 mg / cm2) and low silicon content (< 50 wt.%), which is difficult to meet the demand for high energy density of lithium ion batteries. High loading of nano-silicon, including high silicon content and high loading per unit area, will inevitably increase the instability of the overall structure of the electrode, causing electrode crushing and accelerating capacity decay. Therefore, how to optimize the design of the CNT network framework to ensure high loading of nano-silicon while enhancing the stability of the electrode structure is the key to realizing high-load and high-performance silicon-based negative electrodes. SUMMARY

[0004] The main purpose of the present application is to provide a high-silicon-loaded carbon nanotube composite thin film electrode and a preparation method and application thereof to overcome the deficiencies in the prior art.

[0005] To achieve the aforementioned purposes, the technical solutions adopted by the present application include:

[0006] The present application provides a preparation method of a high-silicon-loaded carbon nanotube composite thin film electrode, which comprises:

[0007] Providing a nano-silicon dispersion liquid containing nano-silicon, polyvinylpyrrolidone, and a solvent;

[0008] Making the continuous carbon nanotube network fully contact with the nano-silicon dispersion liquid, continuously and in situ dynamically uniformly compounding the nano-silicon with the continuous carbon nanotube network, and synchronously shrinking and fiberizing, to prepare a carbon nanotube / nano-silicon composite thin film by continuously collecting layer-by-layer assembly and drying;

[0009] The carbon nanotube / nano-silicon composite film is subjected to high-temperature carbonization treatment and roller pressing treatment in an inert atmosphere to obtain a high-silicon-loaded carbon nanotube composite film electrode.

[0010] In some embodiments, the high-temperature carbonization treatment is performed at a temperature of 800-1000 DEG C for 1-3 hours.

[0011] The application also provides a high-silicon-loaded carbon nanotube composite film electrode prepared by the above preparation method.

[0012] Further, the content of nano-silicon in the high-silicon-loaded carbon nanotube composite film electrode is greater than 40 wt%, and the loading amount is 1-8 mg / cm 2 .

[0013] The application also provides an application of the above high-silicon-loaded carbon nanotube composite film electrode in preparing a lithium ion battery negative electrode material.

[0014] Compared with the prior art, the application has the following beneficial effects:

[0015] 1) The preparation method provided by the application adopts a continuous carbon nanotube network / nano-silicon in-situ continuous composite technology to realize continuous and uniform composite of nano-silicon in the carbon nanotube network, prepare a high-silicon-loaded carbon nanotube composite film electrode, construct a long-range ordered and oriented dense conductive carbon nanotube skeleton, and enhance the structural stability of the electrode while loading high silicon, thereby ensuring the stability of the composite film electrode structure and effectively improving the specific capacity and cycle stability of the silicon-based negative electrode.

[0016] 2) The silicon loading amount of the high-silicon-loaded carbon nanotube composite film electrode prepared by the application can be optimized and regulated by regulating the film thickness and the silicon content, and the prepared composite film electrode has excellent tensile and bending resistance, conductivity and lithium storage performance (specific capacity and cycle stability). BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0018] Figure 1 is a preparation flowchart of a high-silicon-loaded carbon nanotube composite film electrode in a typical embodiment of the application;

[0019] Figure 2 is a surface electron microscope image of a high-silicon-loaded carbon nanotube composite film electrode prepared in Example 1 of the application.

[0020] Figure 3 is a tensile curve of the high-silicon loaded carbon nanotube composite thin film electrode prepared in Example 1 of the present application;

[0021] Figure 4 is a 0.1C constant current charge-discharge curve of the high-silicon loaded carbon nanotube composite thin film electrode prepared in Example 1 of the present application;

[0022] Figure 5 is a surface electron microscope image of the high-silicon loaded carbon nanotube composite thin film electrode prepared in Example 2 of the present application;

[0023] Figure 6 is a 0.1C constant current charge-discharge curve of the high-silicon loaded carbon nanotube composite thin film electrode prepared in Example 2 of the present application;

[0024] Figure 7 is a surface electron microscope image of the high-silicon loaded carbon nanotube composite thin film electrode prepared in Example 3 of the present application;

[0025] Figure 8 is a 0.1C constant current charge-discharge curve of the high-silicon loaded carbon nanotube composite thin film electrode prepared in Example 3 of the present application;

[0026] Figure 9 is a surface electron microscope image of the composite thin film electrode prepared in Comparative Example 1;

[0027] Figure 10 is a 0.1C constant current charge-discharge curve of the composite thin film electrode prepared in Comparative Example 1;

[0028] Figure 11 is a surface electron microscope image of the composite thin film electrode prepared in Comparative Example 2;

[0029] Figure 12 is a stress-strain curve of the composite thin film electrode prepared in Comparative Example 2;

[0030] Figure 13 is a 0.1C constant current charge-discharge curve of the composite thin film electrode prepared in Comparative Example 2;

[0031] Figure 14 is a rate performance graph of the composite thin film electrode prepared in Comparative Example 2. DETAILED DESCRIPTION

[0032] In view of the above defects or improvement needs of the prior art, after long-term research and a large number of experiments, the inventors of the present case propose the technical solution, which mainly provides a high-silicon-loaded carbon nanotube composite thin film electrode and a preparation method thereof. Through a new type of carbon nanotube (CNT) network and nanosilicon continuous in-situ composite and assembly film process, a high-silicon-loaded carbon nanotube composite thin film electrode is constructed by means of high-temperature annealing, and the long-range continuous cross-linking structure of CNT and its network are used to anchor the nanosilicon, effectively solving the problem that the nanosilicon loading and structural strength of the electrode are difficult to be considered.

[0033] Compared with the short-range cross-linking network, the long-range continuous conductive network skeleton in the electrode is crucial to realize the high-loading and high-structural stability nanosilicon-based negative electrode. Therefore, how to optimize the design of the interface composite structure of CNT and nanosilicon to construct the long-range continuous cross-linking skeleton is a key core problem to be solved for realizing the design of high-loading and high-structural stability nanosilicon-based electrode.

[0034] The technical solution, its implementation process and principles will be further explained and described as follows.

[0035] As an aspect of the technical solution of the present application, a preparation method of a high-silicon-loaded carbon nanotube composite thin film electrode includes:

[0036] Providing a nanosilicon dispersion liquid containing nanosilicon, polyvinylpyrrolidone (PVP) and a solvent;

[0037] Making the continuous carbon nanotube network fully contact with the nanosilicon dispersion liquid, so that the continuous carbon nanotube network and the nanosilicon are continuously and in-situ dynamically and uniformly compounded, and are simultaneously shrunk and fiberized, and through continuous collection of layer-by-layer assembly and drying, a carbon nanotube / nanosilicon composite thin film is prepared;

[0038] In an inert atmosphere, the carbon nanotube / nanosilicon composite thin film is subjected to high-temperature carbonization treatment and roll pressing treatment, and a high-silicon-loaded carbon nanotube composite thin film electrode is prepared.

[0039] In some embodiments, the nanosilicon dispersion liquid includes nanosilicon, polyvinylpyrrolidone and a solvent.

[0040] In some embodiments, the particle size of the nanosilicon is 20-100 nm.

[0041] Further, the solvent includes any one or a combination of two of ethanol (anhydrous ethanol), methanol and the like, but is not limited thereto.

[0042] In some embodiments, the content of nanosilicon in the nanosilicon dispersion liquid is 0.1-0.5wt%, and the content of polyvinylpyrrolidone is 0.01-0.05wt%.

[0043] In some embodiments, the preparation method specifically comprises: preparing the nanosilicon dispersion liquid by at least any one of ball milling, ultrasonic, and homogenization.

[0044] In some embodiments, the continuous carbon nanotube network is continuously prepared by a floating catalysis method.

[0045] Further, the collecting speed of the continuous collecting layer layer assembly is 5-7 m / min.

[0046] In some embodiments, the drying temperature is 50-80 ℃, and the time is 5-10 h.

[0047] In some embodiments, the thickness of the carbon nanotube / nanosilicon composite thin film is 30-80 μm.

[0048] In some embodiments, the high-temperature carbonization treatment temperature is 800-1000 ℃, and the time is 1-3 h.

[0049] Further, the roll processing adopts a roll spacing of 5-60 μm and a roll speed of 3-5 r / min.

[0050] Further, the inert gas used in the inert atmosphere can include at least one of nitrogen and argon, but is not limited thereto.

[0051] In some more preferred embodiments, the preparation method of the high-silicon-loaded carbon nanotube composite thin film electrode comprises the following steps: first, preparing nanosilicon dispersion liquids of different concentrations; then, in-situ compounding and synchronous fiber shrinkage of a continuous carbon nanotube (CNT) network prepared by a floating catalysis method in the nanosilicon dispersion liquid, realizing continuous in-situ dynamic uniform compounding of CNT and nanosilicon by using the capillary force between CNT network tubes and the interaction between nanosilicon, and preparing a CNT / nanosilicon composite thin film through a continuous collecting layer layer assembly process, and then, through high-temperature carbonization treatment and roll processing, a high-silicon-loaded CNT composite thin film electrode can be controllably constructed.

[0052] The preparation mechanism of the present application can be that: a continuous carbon nanotube network prepared by a floating catalysis method is used as a conductive framework, in-situ compounding and fiber shrinkage are used to realize in-situ compounding of nanosilicon, a long-range ordered and oriented dense carbon nanotube network framework is constructed, and the electrode conductivity and structural cycle stability are improved; in a high-temperature carbonization annealing process, PVP polymers are converted into amorphous carbon, which is anchored between carbon nanotube networks to enhance the structural stability of the conductive framework, and is coated on the surface of nanosilicon to form a nanosilicon carbon coating, improve the conductivity of nanosilicon, and relieve the volume expansion stress of nanosilicon in the charging and discharging process.

[0053] Among some more preferred embodiments, please refer to Figure 1 As shown in the preparation method of the high-silicon-loaded carbon nanotube composite thin film electrode, the method specifically comprises the following steps:

[0054] (1) A nano-silicon / polyvinylpyrrolidone (PVP) dispersion solution is prepared by ball milling, ultrasonic or homogenization or a combination of the above two processes, i.e., the aforementioned nano-silicon dispersion solution;

[0055] (2) A continuous carbon nanotube (CNT) network is in-situ compounded and simultaneously shrunk and fiberized in the nano-silicon dispersion solution, realizing continuous in-situ dynamic and uniform compounding of the CNT and the nano-silicon, and through continuous layer-by-layer assembly, drying (temperature: 50-80℃, drying time: 5-10h) processes, a CNT / nano-silicon composite thin film is prepared;

[0056] (3) After the CNT / nano-silicon composite thin film is subjected to high-temperature carbonization in an inert gas and roll pressing treatment, a high-silicon-loaded carbon nanotube composite thin film electrode is obtained; wherein the high-temperature carbonization treatment is performed at a temperature of 800-1000℃ for 1-3h, and the inert gas is nitrogen or argon.

[0057] In some more preferred embodiments, in step (2), the continuous carbon nanotube network is prepared by a floating catalyst method, and the continuous in-situ compounding of the carbon nanotube / nano-silicon is realized by using the capillary force between the macroporous CNT network and the nano-silicon and the interaction between them.

[0058] In some more preferred embodiments, in step (2), the thickness of the CNT / nano-silicon composite thin film can be regulated by the number of layers in the continuous layer-by-layer assembly, and the thickness is 30-80μm.

[0059] In some more preferred embodiments, in step (3), during the high-temperature carbonization treatment, the PVP macromolecules are converted into amorphous carbon, which is anchored between the carbon nanotube networks on the one hand to enhance the structural stability, and on the other hand forms a carbon-coated (Si@C) with the nano-silicon to improve the conductivity of the nano-silicon while reducing the huge volume expansion stress of the nano-silicon during the charging and discharging process.

[0060] In summary, the continuous carbon nanotube network / nano-silicon continuous compounding technology is adopted to realize the continuous and uniform compounding of the nano-silicon in the carbon nanotube network, and at the same time, a long-range ordered and oriented dense conductive carbon nanotube skeleton is constructed to ensure the stability of the structure of the composite thin film electrode.

[0061] As another aspect of the technical scheme of the present application, it also relates to a high-silicon-loaded carbon nanotube composite thin film electrode prepared by the aforementioned preparation method.

[0062] In some embodiments, the content of nanosilicon in the high-silicon loaded carbon nanotube composite thin film electrode is greater than 40wt%, and the loading amount is 1-8mg / cm 2 .

[0063] Further, the thickness of the high-silicon loaded carbon nanotube composite thin film electrode is 30-80μm.

[0064] In some embodiments, the carbon nanotube network of the present application is uniformly compounded with nanosilicon, and is compactly oriented, so that the obtained high-silicon loaded carbon nanotube composite thin film electrode is resistant to tensile bending, the tensile strength is greater than 100MPa, and the conductivity is greater than 200S / cm.

[0065] Correspondingly, as another aspect of the technical scheme of the present application, it also relates to the application of the aforementioned high-silicon loaded carbon nanotube composite thin film electrode in preparing a lithium ion battery negative electrode material.

[0066] Specifically, the application of the high-silicon loaded carbon nanotube composite thin film electrode of the present application in a lithium ion battery negative electrode material can exhibit excellent lithium storage performance, and the specific capacity is greater than 2800mAh / g.

[0067] By the above technical scheme, the silicon loading amount of the high-silicon loaded composite thin film electrode prepared by the present application can be optimized by adjusting the thickness of the thin film and the content of silicon, and the prepared composite thin film electrode has excellent tensile bending resistance, conductivity and lithium storage performance (specific capacity and cycle stability).

[0068] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with examples and drawings. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application; all modifications derived from the disclosure of the present application are considered to be within the protection scope of the present application.

[0069] The experimental methods in the following examples are all conventional methods unless otherwise specified. The raw materials involved in the following examples are all ordinary commercially available products unless otherwise specified, and can be purchased on the market.

[0070] The above technical features of the present application and the technical features described in detail in the following (such as examples) can be combined with each other to form new or preferred technical schemes.

[0071] The raw materials involved in each embodiment of the present application are either existing commercially available products or can be prepared according to existing methods.

[0072] Example 1

[0073] A preparation method of a high-silicon loaded carbon nanotube composite thin film electrode comprises the following specific steps:

[0074] (1) Adopting ball milling process to configure nano-silicon / polyvinylpyrrolidone (PVP) dispersion liquid, the content of PVP in the dispersion liquid is 0.01wt%, the concentration of nano-silicon is 0.1wt%, and the solvent is anhydrous ethanol.

[0075] (2) In-situ compounding and synchronous shrinkage fiberization of continuous carbon nanotube (CNT) network in nano-silicon dispersion liquid are carried out to realize continuous in-situ dynamic uniform compounding of CNT and nano-silicon, and through continuous collection layer-by-layer assembly (collection speed is 5m / min), drying (temperature is 50℃, drying time is 10h) process, CNT / nano-silicon composite film is prepared.

[0076] (3) After CNT / nano-silicon composite film is treated by inert gas high-temperature carbonization and roller pressing, high-silicon-loaded carbon nanotube composite film electrode is obtained; the high-temperature carbonization temperature is 900℃, the time is 1h, the inert gas is nitrogen, and the roller pressing interval is 20μm when roller pressing is carried out, and the roller pressing speed is 4r / min.

[0077] The tensile strength of the high-silicon-loaded carbon nanotube composite film electrode prepared in the embodiment is about 350MPa, and the conductivity is 319S / cm. As shown in FIG. 1, it is a surface electron microscope graph of the high-silicon-loaded carbon nanotube composite film electrode, Figure 2 As shown in FIG. 2, it is a tensile curve graph of the high-silicon-loaded carbon nanotube composite film electrode. Figure 3

[0078] The thickness of the high-silicon-loaded carbon nanotube composite film electrode prepared in the embodiment is 31μm, the content of nano-silicon is greater than 40.1wt.%, and the loading amount is 1 mg / cm 2 .

[0079] Using the high-silicon-loaded carbon nanotube composite film electrode as a negative electrode, a lithium metal sheet as a counter electrode, 1M LiPF6 dissolved in a mixture of ethylene carbonate (EC) / diethyl carbonate (DEC) / ethyl carbonate (EMC) (volume is 1:1:1), and 5.0% fluorocarbon acid ethylene (FEC) as an electrolyte, a button cell is assembled, the specific capacity is as high as 3722mAh / g at 0.1C, and excellent lithium storage performance and reversibility are exhibited, as shown in FIG. 3, which is a 0.1C constant current charge-discharge curve graph of the high-silicon-loaded carbon nanotube composite film electrode. Figure 4

[0080] Embodiment 2

[0081] A preparation method of a high-silicon-loaded carbon nanotube composite film electrode includes the following specific steps:

[0082] ​​(1) A nano-silicon / polyvinylpyrrolidone (PVP) dispersion was prepared using an ultrasonic process. The PVP content in the dispersion was 0.02 wt%, the nano-silicon concentration was 0.2 wt%, and the solvent was anhydrous ethanol.

[0083] (2) The continuous carbon nanotube (CNT) network was in situ composited and simultaneously shrunken and fibroped in a nano-silicon dispersion to achieve continuous in situ dynamic uniform composite of CNT and nano-silicon. The CNT / nano-silicon composite film was prepared by continuous collection and layer-by-layer assembly (collection speed of 5 m / min) and drying (temperature of 80℃ and drying time of 5 h).

[0084] (3) The CNT / nano-silicon composite film was subjected to high-temperature carbonization and rolling treatment with inert gas to obtain a high-silicon-loaded carbon nanotube composite film electrode. The high-temperature carbonization temperature was 1000℃, the time was 1 h, the inert gas was nitrogen, the rolling gap was 10 μm, and the rolling speed was 3 r / min.

[0085] The high-silicon-loaded carbon nanotube composite thin film electrode prepared in this embodiment has a tensile strength of approximately 250 MPa and a conductivity of 282 S / cm. For example... Figure 5 The image shown is a surface electron microscope (SEM) image of a high-silicon-loaded carbon nanotube composite thin film electrode.

[0086] The high-silicon-loaded carbon nanotube composite thin film electrode prepared in this embodiment has a thickness of 70 μm, wherein the nano-silicon content is greater than 50.5 wt.% and the loading is 4 mg / cm³. 2 .

[0087] A button cell was assembled using a high-silicon-loaded carbon nanotube composite thin-film electrode as the negative electrode and a lithium metal sheet as the counter electrode. 1M LiPF6 was dissolved in a mixture of ethylene carbonate (EC) / diethyl carbonate (DEC) / ethyl methyl carbonate (EMC) (volume ratio 1:1:1), and 5.0% fluoroethylene carbonate (FEC) was added as the electrolyte. The specific capacity was measured to be as high as 3684 mAh / g at 0.1C, demonstrating excellent lithium storage performance and reversibility. Figure 6 The figure shows the 0.1C constant current charge-discharge curve of the high silicon-loaded carbon nanotube composite thin film electrode.

[0088] Example 3

[0089] A method for preparing a high-silicon-loaded carbon nanotube composite thin film electrode includes the following specific steps:

[0090] (1) A nano-silicon / polyvinylpyrrolidone (PVP) dispersion was prepared by ultrasonic or homogenization mixing process. The PVP content in the dispersion was 0.05 wt%, the concentration of nano-silicon was 0.5 wt%, and the solvent was methanol.

[0091] (2) In-situ compounding and synchronous shrinkage fiberization of continuous carbon nanotube (CNT) network in nanosilicon dispersion liquid to realize continuous in-situ dynamic uniform compounding of CNT and nanosilicon, and through continuous collection layer-by-layer assembly (collection speed is 6 m / min), drying (temperature is 80 ℃, drying time is 5 h) process, CNT / nanosilicon composite film is prepared.

[0092] (3) High-silicon-loaded carbon nanotube composite film electrode is obtained after CNT / nanosilicon composite film is subjected to inert gas high-temperature carbonization and roller pressing treatment; high-temperature carbonization temperature is 1000 ℃, time is 1 h, inert gas is nitrogen, roller pressing interval is 5 μm, and roller pressing speed is 4 r / min.

[0093] The tensile strength of the high-silicon-loaded carbon nanotube composite film electrode prepared in the embodiment is 150 MPa, and the conductivity is 230 S / cm. As shown in FIG. 4, it is a surface electron microscope graph of the high-silicon-loaded carbon nanotube composite film electrode. Figure 7

[0094] The thickness of the high-silicon-loaded carbon nanotube composite film electrode prepared in the embodiment is 61 μm, the content of nanosilicon is greater than 61.2 wt.%, and the loading amount is 3 mg / cm 2 .

[0095] A high-silicon-loaded carbon nanotube composite film electrode is used as a negative electrode, a lithium metal sheet is used as a counter electrode, 1M LiPF6 is dissolved in a mixture of ethylene carbonate (EC) / diethyl carbonate (DEC) / methyl ethyl carbonate (EMC) (volume is 1:1:1), 5.0% of fluorine ethylene carbonate (FEC) is added as an electrolyte, a button cell is assembled, the specific capacity is as high as 3000 mAh / g at 0.1C, and excellent lithium storage performance and reversibility are exhibited. As shown in FIG. 5, it is a 0.1C constant current charge-discharge curve graph of the high-silicon-loaded carbon nanotube composite film electrode. Figure 8

[0096] Embodiment 4

[0097] A preparation method of a high-silicon-loaded carbon nanotube composite film electrode includes the following specific steps:

[0098] (1) An ultrasonic or homogenizing mixing process is used to configure a nanosilicon / polyvinylpyrrolidone (PVP) dispersion liquid, the content of PVP in the dispersion liquid is 0.05 wt.%, the concentration of nanosilicon is 0.5 wt.%, and the solvent is methanol.

[0099] ​​(2) In-situ compounding and synchronous shrinkage fiberization of continuous carbon nanotube (CNT) network in nanosilicon dispersion liquid to realize continuous in-situ dynamic and uniform compounding of CNT and nanosilicon, and through continuous collection layer-by-layer assembly (collection speed is 7 m / min), drying (temperature is 80 ℃, drying time is 5 h) process, CNT / nanosilicon composite film is prepared.

[0100] (3) High-silicon-loaded carbon nanotube composite film electrode is obtained after CNT / nanosilicon composite film is treated by inert gas high-temperature carbonization and rolling.

[0101] The tensile strength of the high-silicon-loaded carbon nanotube composite film electrode prepared in the embodiment is about 155 MPa, and the conductivity is 220 S / cm. As shown in FIG. 4, it is a surface electron microscope graph of the high-silicon-loaded carbon nanotube composite film electrode. Figure 7

[0102] The thickness of the high-silicon-loaded carbon nanotube composite film electrode prepared in the embodiment is 60 μm, the content of nanosilicon is greater than 61.1 wt.%, and the loading amount is 3.2 mg / cm 2 .

[0103] The high-silicon-loaded carbon nanotube composite film electrode is used as a negative electrode, a lithium metal sheet is used as a counter electrode, 1M LiPF6 is dissolved in a mixture of ethylene carbonate (EC) / diethyl carbonate (DEC) / ethyl carbonate (EMC) (volume is 1:1:1), 5.0% of fluoroethylene carbonate (FEC) is added as an electrolyte, a button cell is assembled, the specific capacity is as high as 2910 mAh / g at 0.1C, and excellent lithium storage performance and reversibility are exhibited.

[0104] Comparative Example 1

[0105] The difference between the comparative example and the embodiment 1 is that no polyvinylpyrrolidone is added in the dispersion liquid of step (1).

[0106] In the comparative example, no PVP is added, and the dispersibility and stability of the nanosilicon dispersion liquid are poor. As can be seen from the electron microscope graph Figure 9 , the silicon particles are unevenly distributed and seriously agglomerated. Figure 10 is a 0.1C constant current charge-discharge curve graph of the composite film electrode.

[0107] Comparative Example 2

[0108] The difference between the comparative example and the embodiment 1 is that no high-temperature carbonization treatment in step (3) is performed.

[0109] In the comparative example, no high-temperature carbonization is performed, and the electron microscope graph​Figure 11 The mechanical property of the polymer is decreased, the capacity is low (only about 1000), the initial efficiency is poor, the carbon-coated structure is not formed, the silicon particle volume is expanded seriously, the capacity attenuation is obvious, and the rate performance is poor, such as Figure 12 The stress-strain curve of the composite thin film electrode is shown in FIG. 2, Figure 13 The 0.1C constant current charge-discharge curve of the composite thin film electrode is shown in FIG. 3, Figure 14 The rate performance of the composite thin film electrode is shown in FIG. 4.

[0110] In addition, the inventors of the present application also carried out tests on other raw materials and conditions listed in the specification in the manner of the foregoing examples, and also prepared a high-silicon-loaded carbon nanotube composite thin film electrode with excellent tensile and bending resistance, electrical conductivity, and lithium storage performance.

[0111] Finally, it should be emphasized that the above description is only the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a high-silicon-supported carbon nanotube composite thin film electrode, characterized in that, The preparation method comprises the following steps: providing a nanosilicon dispersion liquid containing nanosilicon, polyvinylpyrrolidone and a solvent; making a continuous carbon nanotube network contact with the nanosilicon dispersion liquid, so that the continuous carbon nanotube network is uniformly and dynamically in-situ compounded with the nanosilicon, and is simultaneously shrunk and fiberized, and a carbon nanotube / nanosilicon composite film is prepared by continuously collecting layer-by-layer assembly and drying; carrying out high-temperature carbonization treatment and roller pressing treatment on the carbon nanotube / nanosilicon composite film in an inert atmosphere to obtain a high-silicon-loaded carbon nanotube composite film electrode.

2. The method of claim 1, wherein: The particle size of the nanosilicon is 20-100 nm; and / or the solvent comprises ethanol and / or methanol.

3. The method of claim 1, wherein: The content of nanosilicon in the nanosilicon dispersion liquid is 0.1-0.5 wt%, and the content of polyvinylpyrrolidone is 0.01-0.05 wt%.

4. The production method according to claim 1, characterized by, The preparation method comprises the following steps: The nanosilicon dispersion liquid is prepared by at least any one of ball milling, ultrasonic treatment and homogenization.

5. The method of claim 1, wherein: The continuous carbon nanotube network is continuously prepared by a floating catalyst method; and / or the collection speed of the continuous layer-by-layer assembly is 5-7 m / min; The drying temperature is 50-80 ℃, and the drying time is 5-10 h.

6. The method of claim 1, wherein: The thickness of the carbon nanotube / nanosilicon composite film is 30-80 μm.

7. The method of claim 1, wherein: The high-temperature carbonization treatment is carried out at a temperature of 800-1000 ℃ for 1-3 h; The inert gas used in the inert atmosphere comprises at least one of nitrogen and argon; The roller pressing interval used in the roller pressing treatment is 5-60 μm, and the roller pressing speed is 3-5 r / min.

8. A high-silicon-loaded carbon nanotube composite film electrode prepared by the preparation method in any one of claims 1-7.

9. The high-silicon loaded carbon nanotube composite thin film electrode according to claim 8, wherein: The high-silicon-loaded carbon nanotube composite film electrode has a content of nanosilicon greater than 40wt%, and a loading amount of 1-8mg / cm 2 ; The thickness of the high-silicon-loaded carbon nanotube composite film electrode is 30-80 μm; The tensile strength of the high-silicon-loaded carbon nanotube composite film electrode is greater than 100 MPa, and the electrical conductivity is greater than 200 S / cm.

10. Application of the high-silicon-loaded carbon nanotube composite film electrode in claim 8 or 9 to preparation of a lithium ion battery negative electrode material.

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