Lithium ion battery anode material as well as preparation method and application thereof

Abstract

The invention discloses a lithium ion battery anode material and a preparation method and application thereof, and the preparation method specifically comprises the following steps: (1) adding NaF and SnCl. 2H2O into water, stirring, carrying out a hydrothermal reaction, carrying out suction filtration washing, and drying to obtain a SnO2-x anode material; and (2) grinding and mixing the SnO2-x anode material and a carbon material to obtain the SnO2-x anode material. The lithium ion battery anode material provided by the invention has higher specific capacity and excellent rate capability, solves the problem of poor cycling stability caused by insufficient conductivity and volume expansion of the traditional SnO2 anode material, and has extremely potential production potential and practical application value.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and more specifically to a lithium ion battery anode material, a preparation method thereof, and an application thereof. Background Art

[0002] In the past decade, the application fields of lithium ion batteries have gradually expanded from portable electronic devices to the field of electric vehicles, which means that lithium ion batteries are developing towards high energy / power density, high safety, and long cycle life. Currently, graphite is widely used as an anode material for lithium ion batteries due to its excellent cycle performance. However, due to the relatively low theoretical specific capacity of graphite (≈372 mAh g -1 ), it cannot meet the growing application requirements of electric vehicles and large-scale energy storage systems. Therefore, researchers have shifted their attention to materials with higher specific capacities.

[0003] Among many anode materials, SnO2 is considered to be one of the most promising anode materials for next-generation lithium ion batteries due to its advantages such as rich reserves, relatively high theoretical capacity, and low price. However, SnO2 has poor intrinsic conductivity and serious volume expansion problems during the lithium ion insertion and extraction processes. The volume expansion will lead to the pulverization of the SnO2 anode material, destroy the original morphology and structure of the SnO2 anode material, make the formed solid electrolyte interface (SEI) unstable, and further affect the cycle life and performance of the battery, which seriously hinders the further application of the SnO2 anode material.

[0004] Studies have found that by introducing defect structures into SnO2, such as oxygen vacancies, the lithium storage performance can be significantly improved. This is because the introduction of oxygen vacancies can effectively increase the electronic conductivity of the material and the number of active sites. The emergence of more active sites is beneficial to the material anchoring more lithium ions, regulating the dynamic process of ion diffusion, and thus improving the battery capacity. For the introduction of oxygen vacancies in SnO2 materials, it is generally achieved through the doping of heteroelements, such as Zn, W, etc. The doping of such hetero-metal elements is often limited in improving the conductivity of SnO2. If SnO2 can be doped with its own element Sn 2+ to prepare SnO rich in oxygen vacancies 2-x , it can not only significantly improve the conductivity of SnO2, but also help to save production costs. Although the capacity of SnO2 lithium ion batteries can be improved by introducing oxygen vacancies, the introduction of oxygen vacancies cannot solve the volume expansion and limited cycle life problems of SnO2 anode materials.

[0005] The carbon coating technology is often used to alleviate the volume expansion problem of SnO2 anode materials. Usually, dopamine or glucose is used as the coating material, and then through high-temperature carbonization, a carbon protection layer is formed on the surface of the SnO2 material. It should be emphasized that during the high-temperature carbonization process of the coating material, SnO2 is prone to react with the formed carbon material to generate metallic Sn, resulting in the attenuation of battery capacity. In addition, this method has a complex process, high requirements for experimental conditions, and also requires a high-temperature environment, making it difficult to meet the needs of large-scale preparation. Therefore, the carbon coating strategy still has certain limitations in practical production applications.

[0006] Therefore, how to solve the problems of volume expansion and insufficient conductivity of SnO2 electrodes during charge and discharge through simpler and more effective methods has become a key technical problem that needs to be overcome by those skilled in the art. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide an anode material for a lithium-ion battery, its preparation method and application to solve the deficiencies in the prior art.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A preparation method of an anode material for a lithium-ion battery specifically includes the following steps:

[0010] (1) Add NaF and SnCl·2H2O to water, stir, perform hydrothermal reaction, filter and wash, and dry to obtain SnO 2-x anode material;

[0011] (2) Grind and mix the SnO 2-x anode material and the carbon material to obtain the anode material for a lithium-ion battery.

[0012] Furthermore, in the above step (1), the molar ratio of NaF to SnCl·2H2O is (1-4):1, preferably 1:1, 2:1, 3:1 or 4:1, and more preferably 3:1.

[0013] The beneficial effect of adopting the above is that the present invention uses NaF to inhibit the hydrolysis of SnCl2·2H2O and regulate the sample morphology.

[0014] Furthermore, in the above step (1), the stirring time is 30 min.

[0015] Furthermore, in the above step (1), the equipment for the hydrothermal reaction is a polytetrafluoroethylene hydrothermal autoclave, the temperature is 150-200 °C, preferably 180 °C, and the time is 6-24 h, preferably 12 h.

[0016] The further beneficial effects of the above are as follows. The present invention uses a hydrothermal synthesis method to prepare Sn with oxygen vacancies and high conductivity without introducing other hetero-metal elements. 2+ Self-doped SnO 2-x anode material.

[0017] Furthermore, in the above step (1), the reagents for suction filtration and washing are absolute ethanol and deionized water.

[0018] Furthermore, in the above step (1), the drying equipment is an oven, and the temperature is 80 °C.

[0019] Furthermore, in the above step (2), the carbon material is at least one of carbon nanotubes (CNTs), reduced graphene oxide, graphite fiber, biomass-derived carbon, and polymer-derived carbon, preferably carbon nanotubes.

[0020] The further beneficial effects of the above are as follows. The present invention utilizes the adsorption of carbon nanotubes on the surface of the SnO 2-x anode material and the interpenetration in the gaps to alleviate the problem of volume expansion of the SnO 2-x anode material, and prepares an oxygen-vacancy-containing SnO 2-x / CNTs anode material with better conductivity, and exhibits excellent lithium-ion battery performance.

[0021] Furthermore, in the above step (2), the mass ratio of the SnO 2-x anode material to the carbon material is 2:1.

[0022] The present invention also claims a lithium-ion battery anode material prepared by the above preparation method.

[0023] The present invention also claims the application of a lithium-ion battery anode material prepared by the above preparation method in the preparation of a lithium-ion battery, which can significantly improve the cycling performance of the lithium-ion battery.

[0024] Through the above technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention discloses an oxygen-vacancy-containing, highly conductive Sn 2+ self-doped SnO 2-x anode material and SnO 2-x / CNTs anode material. Using this as the anode material of a lithium-ion battery, it has a higher specific capacity and excellent rate performance, solves the problems of insufficient conductivity and poor cycling stability caused by volume expansion of traditional SnO2 anode materials, and has extremely potential production potential and practical application value.

[0026] 2. First, the present invention directly performs Sn 2+ self-doping during the synthesis of SnO2 by using hydrothermal synthesis technology. Without adding other heteroelements, oxygen vacancies are introduced to form SnO 2-x with a special defect structure. The introduction of oxygen vacancies not only effectively improves the electron transport performance of the material but also increases the surface active sites of SnO2, thus significantly enhancing its lithium storage performance. Through a simple physical grinding process, the modified SnO 2-x is uniformly mixed with carbon nanotubes (CNTs) with high conductivity and excellent mechanical properties to prepare a uniformly dispersed and structurally stable SnO 2-x / CNTs hybrid anode material. This material fully integrates the respective advantages of SnO 2-x and CNTs. On the one hand, the presence of oxygen vacancies increases the conductivity of SnO 2-x and accelerates the diffusion of lithium ions; on the other hand, the three-dimensional network structure constructed by CNTs on the surface of SnO 2-x can effectively alleviate the structural damage caused by volume expansion of SnO2 during charge and discharge, thus greatly improving the cycle stability and overall electrochemical performance of the battery. More importantly, the preparation process of the present invention is simple, only requiring hydrothermal treatment and a convenient physical grinding process, which can not only greatly reduce the production cost but also facilitate large-scale production and preparation, and has a very wide application prospect in the energy storage field. This simple and efficient preparation process can provide a new technical path for the research and industrialization of high-performance lithium-ion battery anode materials, and also bring valuable inspiration for the design and development of future new anode materials.

[0027] 3. The present invention uses NaF to inhibit the hydrolysis of SnCl2·2H2O and regulate the hydrolysis content of Sn 2+ in the precursor solution. By this way, the conversion amount of Sn 2+ to Sn 4+ during the hydrothermal reaction process is regulated. Without changing the semiconductor type, as much Sn 2+ as possible is made to replace Sn 4+ , and then the preparation of an oxygen vacancy-containing and highly conductive Sn 2+ self-doped SnO 2-x anode material is achieved. In order to be simpler, more effective, and avoid using methods with harsh and complex conditions to solve the volume expansion problem of SnO2 anode materials, the present invention introduces carbon nanotubes (CNTs) materials with excellent conductivity, high specific surface area, good physical adsorption performance, and mechanical strength into the SnO 2-x anode material. Through a simple physical grinding or stirring and mixing process, and using the strong physical adsorption ability of CNTs, it is adsorbed or interspersed in SnO 2-xOn the surface and in the gaps of the anode material, SnO is prepared 2-x / CNTs anode material, thus solving the problems of volume expansion and limited cycle life of the SnO2 anode material. The method provided by the present invention only requires simple processes such as hydrothermal treatment and physical grinding, which not only realizes the effective introduction of oxygen vacancies while avoiding the use of heterogeneous metal elements, enhances the electrical conductivity of the SnO2 material and the storage performance of the lithium-ion battery, but also fully solves the problems of volume expansion and poor cycle stability of the SnO2 anode material, thereby significantly improving the electrochemical performance of the SnO2 electrode.

[0028] 4. The method provided by the present invention has the characteristics of simple process, low cost, green and pollution-free, etc. The greatest advantage of this method is that it solves the volume expansion problem of the SnO2 anode material during the process of lithium-ion insertion and extraction, making the finally obtained SnO with oxygen vacancies and high electrical conductivity 2-x / CNTs anode material show more excellent electrochemical performance. Description of the Drawings

[0029] Figure 1 SEM image of the SnO 2-x anode material obtained in Example 1;

[0030] Figure 2 SEM image of the SnO 2-x / CNTs anode material obtained in Example 1;

[0031] Figure 3 XPS image of the SnO 2-x anode material obtained in Example 1 and the SnO2 anode material obtained in Comparative Example 1;

[0032] Figure 4 Impedance performance image of the batteries assembled using the SnO 2-x anode material obtained in Example 1 and the pure SnO2 anode material obtained in Comparative Example 1 respectively;

[0033] Figure 5 Cycling performance image of the batteries assembled using the SnO 2-x anode material obtained in Example 1 and the pure SnO2 anode material obtained in Comparative Example 1 respectively;

[0034] Figure 6 Impedance performance image of the batteries assembled using the SnO 2-x / CNTs anode materials obtained in Example 1 and Comparative Examples 2-3 respectively;

[0035] Figure 7 Cycling performance image of the batteries assembled using the SnO 2-xRate performance graph (a) and cycling performance graph (b) of the battery assembled with the CNTs anode material;

[0036] Figure 8 For the impedance performance graphs of the batteries assembled with the SnO 2-x / CNTs anode material obtained in Example 1 and the SnO2 / CNTs anode material obtained in Comparative Example 4 respectively;

[0037] Figure 9 For the rate performance graph (a) and cycling performance graph (b) of the batteries assembled with the SnO 2-x / CNTs anode material obtained in Example 1 and the SnO2 / CNTs anode material obtained in Comparative Example 4 respectively. Detailed implementation manners

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] Example 1

[0040] A preparation method of a lithium-ion battery anode material specifically includes the following steps:

[0041] (1) Weigh NaF and SnCl·2H2O with a molar ratio of 3:1. First, add NaF to deionized water. After complete dissolution, add SnCl·2H2O and stir for 30 min to obtain a mixed solution;

[0042] (2) Add the mixed solution to a polytetrafluoroethylene hydrothermal reactor and carry out a hydrothermal reaction at 180 °C for 12 h. After cooling, obtain a hydrothermal reaction product;

[0043] (3) Wash the hydrothermal reaction product by repeated suction filtration with absolute ethanol and deionized water three times to obtain a suction filtration and washing product;

[0044] (4) Put the suction filtration and washing product into an oven and dry it at 80 °C to obtain the SnO 2-x anode material;

[0045] (5) Weigh the SnO 2-x anode material and carbon nanotubes with a mass ratio of 2:1, grind and mix them for 1 h to obtain a lithium-ion battery anode material, denoted as SnO 2-x / CNTs(2:1).

[0046] Comparative Example 1

[0047] Preparation method of SnO2 anode material, specifically including the following steps:

[0048] (1) Weigh NaF and SnCl·2H2O with a molar ratio of 3:1. First, add NaF to deionized water. After complete dissolution, add SnCl·2H2O and stir for 30 min to obtain a mixed solution;

[0049] (2) Add the mixed solution to a polytetrafluoroethylene hydrothermal autoclave and carry out hydrothermal reaction at 180 °C for 12 h, then cool to obtain a hydrothermal reaction product;

[0050] (3) Repeat suction filtration and washing of the hydrothermal reaction product 3 times with anhydrous ethanol and deionized water to obtain a suction filtration and washing product;

[0051] (4) Put the suction filtration and washing product into an oven and dry it at 80 °C to obtain SnO 2-x anode material;

[0052] (5) Put the SnO 2-x anode material into a muffle furnace, heat it to 600 °C at a rate of 10 °C / min in an air atmosphere and hold for 6 h (fully oxidize) to obtain a pure SnO2 anode material without oxygen vacancies.

[0053] Comparative Example 2

[0054] Preparation method of lithium-ion battery anode material, specifically including the following steps:

[0055] (1) Weigh NaF and SnCl·2H2O with a molar ratio of 3:1. First, add NaF to deionized water. After complete dissolution, add SnCl·2H2O and stir for 30 min to obtain a mixed solution;

[0056] (2) Add the mixed solution to a polytetrafluoroethylene hydrothermal autoclave and carry out hydrothermal reaction at 180 °C for 12 h, then cool to obtain a hydrothermal reaction product;

[0057] (3) Repeat suction filtration and washing of the hydrothermal reaction product 3 times with anhydrous ethanol and deionized water to obtain a suction filtration and washing product;

[0058] (4) Put the suction filtration and washing product into an oven and dry it at 80 °C to obtain SnO 2-x anode material;

[0059] (5) Weigh SnO 2-x anode material and carbon nanotubes with a mass ratio of 1:1, grind and mix for 1 h to obtain a lithium-ion battery anode material, denoted as SnO 2-x / CNTs(1:1).

[0060] Comparative Example 3

[0061] Preparation method of anode material for lithium-ion battery, specifically including the following steps:

[0062] (1) Weigh NaF and SnCl·2H2O with a molar ratio of 3:1. First, add NaF to deionized water. After complete dissolution, add SnCl·2H2O and stir for 30 min to obtain a mixed solution;

[0063] (2) Add the mixed solution to a polytetrafluoroethylene hydrothermal autoclave and conduct a hydrothermal reaction at 180 °C for 12 h, then cool to obtain a hydrothermal reaction product;

[0064] (3) Repeat suction filtration and washing of the hydrothermal reaction product 3 times with absolute ethanol and deionized water to obtain a suction filtration and washing product;

[0065] (4) Put the suction filtration and washing product into an oven and dry it at 80 °C to obtain SnO 2-x anode material;

[0066] (5) Weigh SnO 2-x anode material and carbon nanotubes with a mass ratio of 3:1, grind and mix them for 1 h to obtain the anode material for lithium-ion battery, denoted as SnO 2-x / CNTs(3:1).

[0067] Comparative Example 4

[0068] Preparation method of anode material for lithium-ion battery, specifically including the following steps:

[0069] (1) Weigh NaF and SnCl·2H2O with a molar ratio of 3:1. First, add NaF to deionized water. After complete dissolution, add SnCl·2H2O and stir for 30 min to obtain a mixed solution;

[0070] (2) Add the mixed solution to a polytetrafluoroethylene hydrothermal autoclave and conduct a hydrothermal reaction at 180 °C for 12 h, then cool to obtain a hydrothermal reaction product;

[0071] (3) Repeat suction filtration and washing of the hydrothermal reaction product 3 times with absolute ethanol and deionized water to obtain a suction filtration and washing product;

[0072] (4) Put the suction filtration and washing product into an oven and dry it at 80 °C to obtain SnO 2-x anode material;

[0073] (5) Put the SnO 2-x anode material into a muffle furnace, heat it from room temperature to 600 °C at a rate of 10 °C / min in an air atmosphere and hold for 6 h (fully oxidized) to obtain a pure SnO2 anode material without oxygen vacancies;

[0074] (6) Weigh the pure SnO2 anode material and carbon nanotubes with a mass ratio of 2:1, grind and mix them for 1 h to obtain the anode material for lithium-ion batteries, denoted as SnO2 / CNTs(2:1).

[0075] Performance test

[0076] 1. SEM characterization test of SnO 2-x anode material and SnO 2-x / CNTs(2:1) anode material

[0077] Place the SnO 2-x anode material obtained in Example 1 and the SnO 2-x / CNTs(2:1) anode material under the scanning electron microscope for scanning respectively. The SEM images are as Figure 1-2 shown.

[0078] It can be seen from Figure 1-2 that compared with the SnO 2-x anode material, after grinding and mixing it with carbon nanotubes, the nanotubes and SnO 2-x nanosheets are arranged in an interleaved manner, and the carbon nanotubes are adsorbed or interspersed on the surface of the SnO 2-x nanosheets. This oxygen vacancy-containing and unique structure can not only provide a large number of active sites for the adsorption of lithium ions, but also effectively inhibit the volume expansion phenomenon of the SnO 2-x nanosheets during the charge and discharge process, thus contributing to further improving the electrochemical performance.

[0079] 2. XPS characterization of SnO 2-x anode material and pure SnO2 anode material

[0080] Place the SnO 2-x anode material obtained in Example 1 and the pure SnO2 anode material obtained in Comparative Example 1 in the X-ray photoelectron spectrometer for analysis respectively. The XPS images are as Figure 3 shown.

[0081] It can be seen from Figure 3 in (a) that Sn 2-x has been successfully doped into the SnO 2+ anode material obtained in Example 1, where the peak positions of Sn 2+ and Sn 4+ are 487.1 eV and 495.6 eV respectively. It can be seen from Figure 3 in (c) that no Sn 2+ is observed in the pure SnO2 anode material obtained in Comparative Example 1, and only Sn 4+ is present, indicating that the sample obtained in Comparative Example 1 is pure SnO2.

[0082] Figure 3In (b) and (d) are the O1s spectra of two samples. From Figure 3 In (b), it can be seen that SnO 2-x The anode material contains lattice oxygen (OL), vacancy oxygen (VO), and adsorbed oxygen (OC), and their peak positions are 530.6 eV, 531.3 eV, and 532.4 eV respectively, indicating that the SnO 2-x obtained in Example 1 successfully introduced oxygen vacancies into the anode material.

[0083] 3. Impedance performance test of SnO 2-x anode material and pure SnO2 anode material

[0084] The SnO 2-x anode material obtained in Example 1 and the pure SnO2 anode material obtained in Comparative Example 1 were respectively assembled into lithium-ion batteries. The impedance performance diagrams of the assembled batteries are as shown in Figure 4 .

[0085] It can be seen from Figure 4 that compared with the two assembled batteries, the semicircle diameter of the SnO 2-x anode material is significantly smaller than that of the pure SnO2 anode material, indicating that its charge transfer resistance (R ct ) is lower and the electron transfer is faster, which will help improve the electrochemical performance of the electrode. The equivalent circuit model in the lower right corner is used to fit the experimental data to further analyze the impedance characteristics. The results show that the presence of oxygen vacancies will make the SnO 2-x anode material show better electrochemical performance in lithium-ion batteries.

[0086] 4. Cycling performance test of SnO 2-x anode material and pure SnO2 anode material

[0087] The SnO 2-x anode material obtained in Example 1 and the pure SnO2 anode material obtained in Comparative Example 1 were respectively assembled into lithium-ion batteries. The cycling performance of the assembled batteries at a current density of 0.1 A g -1 is as shown in Figure 5 .

[0088] It can be seen from Figure 5 that the cycling performance of the electrode prepared from the SnO 2-x anode material is better than that of the electrode prepared from the pure SnO2 anode material.

[0089] 5. Impedance performance test of SnO 2-x / CNTs anode materials with different ratios

[0090] The SnO 2-x / CNTs anode materials are assembled into lithium-ion batteries. The impedance performance of the assembled battery is shown in the figure Figure 6 shown.

[0091] Depend on Figure 6 It can be seen that different ratios of SnO 2-x / CNTs anode materials have obvious differences in the diameter of the semicircle in the high frequency range, among which SnO 2-x When the mass ratio of SnO to CNTs is 2:1, the semicircle radius of the electrode is the smallest, indicating that its charge transfer impedance is the lowest, which is conducive to the interfacial reaction. At the same time, the slope of the electrode in the low-frequency range is relatively smaller, indicating that its ion diffusion resistance is lower. 2-x When the mass ratio of CNTs / CNTs is 1:1 and 3:1, the semicircular diameter of the electrode is larger, suggesting that its interfacial charge transfer kinetics is limited.

[0092] 6. SnO with different ratios 2-x Rate performance and cycle performance test of CNTs anode materials

[0093] The SnO obtained in Example 1 and Comparative Examples 2-3 were used respectively. 2-x / CNTs anode materials were assembled into lithium-ion batteries. The rate performance of the assembled batteries at different current densities and the -1 The cycling performance diagram under current density is shown in Figure 7 shown.

[0094] Depend on Figure 7 As shown in (a), different ratios of SnO 2-x There is a significant difference in the rate performance between the / CNTs electrodes. -1 When the battery assembled from the materials of Example 1 and Comparative Examples 2-3 showed 1128 mAh g -1 , 848mAh g -1 , 823mAh g -1 As the current density increases, the specific capacity of all samples decreases. When the current density returns to 0.1A g -1 When the battery capacity of the sample of Example 1 is 1100 mAh g -1 .

[0095] Depend on Figure 7 As shown in (b), SnO 2-x The / CNT (2:1) composite electrode still maintains 600 mAh g after 450 cycles. -1 The specific capacity of SnO 2-x / CNT(3:1) and SnO 2-x / CNT(1:1) has a relatively fast capacity decay, with specific capacities of 300 mAh g -1 and 200 mAh g -1 . The results show that the optimal ratio of SnO 2-x to carbon nanotubes is 2:1.

[0096] 7. Impedance performance test of SnO 2-x / CNTs anode material and SnO2 / CNTs anode material

[0097] The SnO 2-x / CNTs anode material obtained in Example 1 and the SnO2 / CNTs anode material obtained in Comparative Example 4 were respectively used to assemble lithium-ion batteries. The impedance performance diagrams of the assembled batteries are as shown in Figure 8 .

[0098] As can be seen from Figure 8 , the difference between the SnO 2-x / CNTs(2:1) and SnO2 / CNTs(2:1) electrodes is more prominent in the EIS spectrum. The semicircle diameter of the SnO 2-x / CNTs(2:1) electrode in the high-frequency range is significantly smaller than that of the SnO2 / CNTs(2:1) electrode, indicating a lower charge transfer impedance brought about by the synergistic effect of oxygen vacancies and CNTs. In addition, the impedance characteristics of this electrode in the low-frequency range are also better, meaning it has a faster ion diffusion rate.

[0099] 8. Rate performance and cycling performance test of SnO 2-x / CNTs anode material and SnO2 / CNTs anode material

[0100] The SnO 2-x / CNTs anode material obtained in Example 1 and the SnO2 / CNTs anode material obtained in Comparative Example 4 were respectively used to assemble lithium-ion batteries. The rate performance of the assembled batteries at different current densities and the cycling performance diagram at a current density of 1 A g -1 are as shown in Figure 9 .

[0101] As can be seen from Figure 9 (a) in, it can be clearly seen from the figure that the rate performance of the SnO 2-x / CNTs sample containing oxygen vacancies is better than that of the SnO2 / CNTs sample. The results show that introducing oxygen vacancies into SnO2 and mixing it with an appropriate amount of carbon nanotubes to obtain an anode material has better rate performance.

[0102] As can be seen from Figure 9 (b) in, SnO 2-x / The CNT electrode exhibits higher specific capacity and better cycling stability during long cycling, which may be attributed to the presence of oxygen defects, improving the electron / ion transport ability and enhancing the structural stability. This indicates that introducing oxygen vacancies into SnO2 and mixing it with an appropriate amount of carbon nanotubes results in an anode material with better cycling performance.

[0103] In the above experiments, the assembly steps of the lithium-ion battery are as follows:

[0104] (1) First, prepare an electrode slurry by mixing the prepared material, conductive agent (Super P), and binder (DMF) in a mass ratio of 8:1:1, coat it on a copper foil, and place it in a vacuum oven to dry at 120 °C for 12 h;

[0105] (2) Then, cut the copper foil into a disc-shaped electrode with a diameter of 14.0 mm, and the loading mass of the active material is 1.2 mg cm -2 ;

[0106] (3) Finally, use the prepared copper foil with the active material as the working electrode, a Li foil as the negative electrode, and ethylene carbonate / methyl ethyl carbonate / dimethyl carbonate (volume ratio 1:1:1) dissolved with 1.0 M LiPF6 as the electrolyte to assemble a coin cell in an argon-filled glove box.

[0107] In the above experiments, the testing method of the lithium-ion battery is as follows:

[0108] (1) Perform cyclic voltammetry (CV) on the battery using an integrated test system (Solartron 1470E);

[0109] (2) Perform impedance (EIS) testing on the battery using a Solartron Analytical (1455 / 1451) system in the frequency range of 0.01 - 100 kHz;

[0110] (3) The galvanostatic charge-discharge (GCD) test of the battery is carried out on a LAND CT2001A test system.

[0111] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of an anode material for a lithium-ion battery, characterized in that, Specifically, it includes the following steps: (1) Add NaF and SnCl·2H2O to water, stir, conduct a hydrothermal reaction, perform suction filtration and washing, and then dry to obtain SnO 2-x Anode material; (2) Grind and mix the SnO 2-x anode material and the carbon material to obtain the anode material for the lithium-ion battery.

2. The preparation method of a lithium-ion battery anode material according to claim 1, characterized in that, In step (1), the molar ratio of NaF to SnCl·2H2O is (1 - 4):

1.

3. The preparation method of a lithium-ion battery anode material according to claim 1, characterized in that, In step (1), the stirring time is 30 min.

4. The preparation method of a lithium-ion battery anode material according to claim 1, characterized in that, In step (1), the hydrothermal reaction device is a polytetrafluoroethylene hydrothermal autoclave, the temperature is 150 - 200 °C, and the time is 6 - 24 h.

5. The preparation method of a lithium-ion battery anode material according to claim 1, characterized in that, In step (1), the reagents for suction filtration and washing are absolute ethanol and deionized water.

6. The preparation method of a lithium-ion battery anode material according to claim 1, characterized in that In step (1), the drying device is an oven, and the temperature is 80 °C.

7. The preparation method of a lithium-ion battery anode material according to claim 1, characterized in that In step (2), the carbon material is at least one of carbon nanotubes, reduced graphene oxide, graphite fibers, biomass-derived carbon, and polymer-derived carbon.

8. The preparation method of a lithium-ion battery anode material according to claim 1, characterized in that, In step (2), the SnO 2-x The mass ratio of the anode material to the carbon material is 2:

1.

9. A lithium-ion battery anode material prepared by the preparation method according to any one of claims 1 - 8.

10. Use of a lithium-ion battery anode material prepared by the preparation method according to any one of claims 1 - 8 in the preparation of a lithium-ion battery.

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