A SnO2 nanorod, its preparation method and application

Abstract

The application discloses a SnO2 nanorod, a preparation method and application thereof; the SnO2 nanorod is a self-assembled nanorod, the structure of the SnO2 nanorod is rod-shaped in the radial direction and is irregular petal-shaped in the interface direction; the preparation method comprises the following steps: mixing and stirring tin source material and polyethylene glycol, then constant-temperature stirring and cooling to obtain a tin source solution; centrifugal washing and drying the tin source solution after cooling to obtain a precursor product, and high-temperature annealing treatment is conducted on the precursor product to obtain the self-assembled SnO2 nanorod; the SnO2 nanorod is applied to a lithium / sodium ion negative electrode material; the PEG steric hindrance effect is used for realizing nanosynthesis of SnO2 material and simultaneously constructing a nanorod structure; based on nanosynthesis and the self-assembled structure, the SnO2 energy storage material is relieved from the existing defects, and the conductivity, structural stability, reaction activity and other energy storage performances of the SnO2 are improved.

Description

Technical Field

[0001] This invention relates to the field of SnO2 electrode materials technology, and in particular to a SnO2 nanorod, its preparation method, and its application. Background Technology

[0002] The fossil fuel crisis is becoming increasingly severe, and future energy utilization and development are constantly facing new challenges. Among numerous energy development technologies, green energy (wind, tidal, solar, etc.) has become the preferred choice due to its environmental friendliness and sustainability. However, the utilization of green energy is cyclical and cannot provide continuous energy supply directly, making energy storage devices a crucial link in the development of green energy. Among various energy storage devices, lithium-ion batteries have become the preferred choice due to their high energy density and high output voltage. However, the scarcity and uneven distribution of lithium resources make sodium-ion batteries the most powerful transitional and successor to lithium-ion batteries in the future. Lithium / sodium-ion batteries mostly use carbonaceous materials as negative electrode materials (lithium-ion batteries: graphite; sodium-ion batteries: hard carbon or soft carbon). Although carbonaceous materials have considerable capacity stability, their theoretical capacity is generally below 400 mAh g. -1 Therefore, developing innovative, high-performance anode materials is one of the key aspects of improving the performance of lithium / sodium-ion batteries. Furthermore, given the current need for further development of sodium-ion batteries, my country has proposed a "lithium-sodium synergy" energy storage development strategy. Developing dual-purpose anode materials is of great significance for promoting the development of lithium / sodium-ion batteries and advancing the "lithium-sodium synergy" strategy.

[0003] Among many anode materials, SnO2 possesses the advantages of abundant crustal elements, non-toxicity, environmental friendliness, and high theoretical specific capacity (1494 mAh g). -1 Its advantages, such as [missing information], make it a promising alternative to carbon-based materials (lithium / sodium-ion batteries). However, there are aspects of SnO2 that need improvement when used directly as an electrode material. On the one hand, SnO2 has poor conductivity, and its low intrinsic conductivity reduces the reversible capacity of the anode material. On the other hand, SnO2 undergoes significant volume changes during energy storage, and the volume effect causes a rapid decrease in reversible capacity. Furthermore, the formation of the lithium-depleted phase during lithium storage requires high formation energy, which also leads to significant reversible capacity loss.

[0004] To address the issue of volume expansion of SnO2 materials during charge and discharge, existing technologies, such as the tin oxide-based composite anode material and its preparation method and application disclosed in patent number CN202310009786.2, involve coating the surface of tin dioxide to form a firmly bonded whole, thereby solving the material performance problem caused by volume expansion after cyclic charge and discharge. Summary of the Invention

[0005] The purpose of this invention is to provide a SnO2 nanorod, its preparation method, and its application, which solves the problems of insufficient energy storage performance of SnO2 energy storage materials in the prior art, such as conductivity, structural stability, and reactivity.

[0006] The present invention is achieved as follows: a SnO2 nanorod, wherein the SnO2 nanorod is a self-assembled nanorod, and the structure of the SnO2 nanorod is rod-shaped in the radial direction and irregular petal-shaped in the interfacial direction.

[0007] The synthesized SnO2 material belongs to the nanoscale material category and forms a self-assembled nanorod structure under steric hindrance. Self-assembled nanostructures are one of the more effective means to improve the shortcomings of tin dioxide materials. On the one hand, the self-assembled nanoscale structure shortens the conductive path of the electrode material, making electron transport smoother and thus improving the material's conductivity. Simultaneously, the nanoscale structure possesses strong structural stability, preventing agglomeration and delamination of the electrode material due to volume effect, thereby improving the material's cycle stability and capacity retention. On the other hand, the self-assembled structure can form ordered electron transport channels in the material, increasing electron migration rate and conductivity. This helps improve the electron transport efficiency of energy storage materials, and enhances the charge-discharge rate and cycle life of energy storage devices. Furthermore, the self-assembled structure endows the electrode material with rich pore structure and pore size distribution, increasing the specific surface area of ​​the electrode material, thereby regulating the ion diffusion rate and charge transport rate of the electrode material, improving the material's energy storage performance and electrochemical performance. In summary, SnO2 can achieve advantages such as optimized conductivity, increased specific surface area, improved stability, and enhanced energy storage performance through self-assembled structures. These advantages can improve the energy density, cycle life, and charge / discharge rate of SnO2 electrode materials, which is beneficial to improving the performance and application range of energy storage materials, and thus has a positive impact on promoting the development of lithium / sodium ion batteries and advancing the "lithium-sodium co-operation" strategy.

[0008] This invention also provides a method for preparing SnO2 nanorods, the method comprising the following steps: Step 1: Mix the tin source material with polyethylene glycol and stir, then keep it at a constant temperature and stir before cooling to obtain a tin source solution; Step 2: After cooling, the tin source solution is washed by centrifugation and dried to obtain the precursor product. After high-temperature annealing, self-assembled SnO2 nanorods are obtained.

[0009] The synthesized SnO2 material belongs to the nanoscale material category and forms a self-assembled nanorod structure under steric hindrance. Self-assembled nanostructures are one of the more effective means to improve the shortcomings of tin dioxide materials. On the one hand, the self-assembled nanoscale structure shortens the conductive path of the electrode material, making electron transport smoother and thus improving the material's conductivity. Simultaneously, the nanoscale structure possesses strong structural stability, preventing agglomeration and delamination of the electrode material due to volume effect, thereby improving the material's cycle stability and capacity retention. On the other hand, the self-assembled structure can form ordered electron transport channels in the material, increasing electron migration rate and conductivity. This helps improve the electron transport efficiency of energy storage materials, and enhances the charge-discharge rate and cycle life of energy storage devices. Furthermore, the self-assembled structure endows the electrode material with rich pore structure and pore size distribution, increasing the specific surface area of ​​the electrode material, thereby regulating the ion diffusion rate and charge transport rate of the electrode material, improving the material's energy storage performance and electrochemical performance. In summary, SnO2 can achieve advantages such as optimized conductivity, increased specific surface area, improved stability, and enhanced energy storage performance through self-assembled structures. These advantages can improve the energy density, cycle life, and charge / discharge rate of SnO2 electrode materials, which is beneficial to improving the performance and application range of energy storage materials, and thus has a positive impact on promoting the development of lithium / sodium ion batteries and advancing the "lithium-sodium co-operation" strategy.

[0010] Based on the principle of self-assembly of nanorods caused by steric hindrance, it is speculated that this is due to a certain interaction between tin salt and polyethylene glycol (PEG) within the temperature range described in this invention; a Sn-PEG complex is formed under chemical bonding and weak interactions (see...). Figure 1 The composite constructed with PEG chains can effectively prevent the intrusion of other tin sources and components. At the same time, it can form Sn-PEG coated state under the guidance of functional groups or chemical bonds at the end of PEG chains, and grow and accumulate in a preferred direction, thereby inducing assembly to form a precursor of nanorod structure. Then, the coated state is transformed into SnO2 nanorods through heat treatment process.

[0011] A further technical solution of the present invention is that the number of polyethylene glycol molecules is 100-1000; and the concentration of the tin source solution is 10-50 mM.

[0012] A further technical solution of the present invention is that the tin source material is at least one of tin acetate, stannous chloride, trimethyltin acetate, and tetramethyltin chloride.

[0013] The tin source is selected from salts that are soluble in ethylene glycol.

[0014] A further technical solution of the present invention is: the mixing and stirring in step one is ultrasonic stirring for 15-30 minutes; the constant temperature stirring temperature is 100℃-180℃, the stirring time is 60 minutes-120 minutes, and the cooling is natural cooling.

[0015] Ultrasonic stirring is beneficial for material dispersion, while constant temperature stirring is beneficial for the reaction between tin source material and polyethylene glycol.

[0016] The temperature for constant temperature stirring is constant heating, and stirring can be done by mechanical stirring or magnetic stirring. The temperature for constant temperature stirring is 100℃-180℃. Based on the principle of self-assembly of nanorods caused by steric hindrance, it is speculated that this is caused by a certain interaction between tin salt and polyethylene glycol (PEG) at this temperature.

[0017] A further technical solution of the present invention is as follows: in step two, the centrifugation speed is 7000-10000 rpm, the washing is performed by alternating washing with deionized water and ethanol, and the drying temperature is 70-100℃; the high-temperature annealing treatment is performed in a hydrogen or / and argon atmosphere, heating to 300℃-700℃ and maintaining for 1 h-4 h.

[0018] This invention also provides an application of SnO2 nanorods in lithium / sodium ion anode materials.

[0019] The beneficial effects of this invention are as follows: The SnO2 material synthesized in this invention belongs to the nanoscale material category and forms a self-assembled nanorod structure under steric hindrance. Self-assembled nanostructures are one of the more effective means to improve the shortcomings of tin dioxide materials. On the one hand, the self-assembled nanoscale structure makes the conductive path of the electrode material shorter and the electron transport smoother, thereby improving the conductivity of the material. Simultaneously, the nanoscale structure possesses strong structural stability, preventing agglomeration and delamination of the electrode material due to volume effect, thus improving the cycle stability and capacity retention of the material. On the other hand, the self-assembled structure can form ordered electron transport channels in the material, increasing the electron migration rate and conductivity. This helps to improve the electron transport efficiency of energy storage materials and increase the charge-discharge rate and cycle life of energy storage devices. Furthermore, the self-assembled structure can endow the electrode material with rich pore structure and pore size distribution, increasing the specific surface area of ​​the electrode material, thereby regulating the ion diffusion rate and charge transport rate of the electrode material, and improving the energy storage performance and electrochemical performance of the material. In summary, SnO2 can achieve advantages such as optimized conductivity, increased specific surface area, improved stability, and improved energy storage performance through its self-assembled structure. These advantages can improve the energy density, cycle life, and charge / discharge rate of SnO2 electrode materials, which is beneficial to improving the performance and application range of energy storage materials, and thus has a positive impact on promoting the development of lithium / sodium ion batteries and advancing the "lithium-sodium co-operation" strategy.

[0020] Based on the principle of self-assembly of nanorods caused by steric hindrance, it is speculated that this is due to a certain interaction between tin salt and polyethylene glycol (PEG) within the temperature range described in this invention; a Sn-PEG complex is formed under chemical bonding and weak interactions (see...). Figure 1The composite constructed with PEG chains can effectively prevent the intrusion of other tin sources and components. At the same time, it can form Sn-PEG coated state under the guidance of functional groups or chemical bonds at the end of PEG chains, and grow and accumulate in a preferred direction, thereby inducing assembly to form a precursor of nanorod structure. Then, the coated state is transformed into SnO2 nanorods through heat treatment process. Attached Figure Description

[0021] Figure 1 (a) is a schematic diagram of the molecular structure of the Sn-PEG complex provided by the present invention; (b) is a schematic diagram of the Sn-PEG coated state provided by the present invention; Figure 2 (a) is the X-ray diffraction (XRD) phase diagram of the SnO2 nanorods provided by the present invention; (bc) is the scanning electron microscope (SEM) morphology of the SnO2 nanorods provided by the present invention; (df) is the elemental distribution map of the SnO2 nanorods provided by the present invention. Figure 3 (a) shows the application of SnO2 nanorods in lithium-ion batteries at 100 mA g. -1 Cyclic performance at current density; Figure 3 (b) shows the application of SnO2 nanorods in lithium-ion batteries at 2 A g. -1 Cyclic performance at current density. Detailed Implementation

[0022] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention. Example

[0024] The method for synthesizing SnO2 nanorods by self-assembly according to the present invention includes the following steps: Step S1: Mix 1 mmol Sn(OOCCH3)2 with 40 mL PEG-200 and sonicate for 15 min.

[0025] Step S2: Stir vigorously at 180°C for 40 minutes, then allow to cool naturally.

[0026] In step S3, the precipitate was centrifuged at 8,000 rpm, washed three times alternately with deionized water and ethanol, and dried overnight in a 70°C oven to obtain the intermediate.

[0027] In step S4, the obtained intermediate is annealed in nitrogen at 600℃ for 2 h to obtain the final product, namely the assembled SnO2 nanorods.

[0028] Please refer to the documentation for the self-assembled SnO2 nanorod features and structure described in this embodiment. Figure 2 and Table 1, in which Figure 2 (a) X-ray diffraction (XRD) phase diagram of SnO2 nanorods; Figure 2 (b, c) show the morphology obtained from scanning electron microscopy (SEM). Figure 2 (df) is a distribution map of Mapping elements.

[0029] Table 1. Mapping Element Analysis Results

[0030] Performance testing: The SnO2 nanorods prepared in Example 1 were mixed with a conductive agent (acetylene black) and a binder (polyvinylidene fluoride PVDF) in a ratio of 7:2:1 to form an active material slurry. This slurry was then coated onto a copper foil and dried (vacuum drying conditions: temperature 90 °C, time 12 h) to obtain the negative electrode material. The negative electrode sheet is cut, a lithium metal sheet is used as the counter electrode, and the button cell is assembled in a glove box using a separator, electrolyte, and button cell package (CR2032).

[0031] The electrochemical performance of the negative electrode material in Example 1 was tested using the Newway testing system. The testing methods included: (1) 100 mA g -1 The cycling performance of SnO2 nanorod anode material was measured at current density; (2) 1 A g -1 Cycling performance of SnO2 nanorod anode materials at current density was measured. Please refer to the following: Figure 3 3(a) shows the application of SnO2 nanorods in lithium-ion batteries at 100 mA g.-1 Cyclic performance at current density. From Figure 3 As can be seen in (a), the SnO2 nanorods exhibit a first cycle strength of 1380 mA hg. -1 High specific capacity, with a preferred coulombic efficiency of 71%, maintaining 1060 mA hg after 120 charge-discharge cycles. -1 3(b) shows the application of SnO2 nanorods in lithium-ion batteries at 2 A g. -1 Cyclic performance at current density. From Figure 3 As shown in (b), the SnO2 nanorods exhibit excellent long-term cycling performance, maintaining 466 mA hg after 400 charge-discharge cycles. -1 The material exhibits a reversible specific capacity and maintains a high coulombic efficiency (99%), demonstrating excellent lithium storage performance and outstanding structural stability.

[0032] In summary, based on the principle of self-assembly of nanorods caused by steric hindrance, it is speculated that this is due to a certain interaction between tin salt and polyethylene glycol (PEG) at the temperature described in this invention; a Sn-PEG complex is formed under chemical bonds and weak interactions (see...). Figure 1 The composite constructed with PEG chains can effectively prevent the intrusion of other tin sources and components. At the same time, it can form Sn-PEG coated state under the guidance of functional groups or chemical bonds at the end of PEG chains, and grow and accumulate in a preferred direction, thereby inducing assembly to form a precursor of nanorod structure. Then, the coated state is transformed into SnO2 nanorods through heat treatment process.

[0033] The above description is only a preferred embodiment 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 protection scope of the present invention.

Claims

1. A method for preparing SnO2 nanorods, characterized in that, The method includes the following steps: Step 1: Mix the tin source material with polyethylene glycol and stir using ultrasonic stirring for 15-30 minutes; maintain a constant temperature of 100℃-180℃ for 40-120 minutes, then cool after stirring at a constant temperature to obtain the tin source solution. Step 2: After cooling, the tin source solution is centrifuged, washed, and dried to obtain the precursor product. After high-temperature annealing, SnO2 nanorods are obtained. The SnO2 nanorods are self-assembled nanorods. The structure of the SnO2 nanorods is rod-shaped in the radial direction and irregular petal-shaped in the interfacial direction.

2. The method for preparing SnO2 nanorods according to claim 1, characterized in that, The number of polyethylene glycol molecules is 100-1000; the concentration of the tin source solution is 10-50 mM.

3. The method for preparing SnO2 nanorods according to claim 1, characterized in that, The tin source material is at least one of tin acetate, stannous chloride, trimethyltin acetate, and tetramethyltin chloride.

4. The method for preparing SnO2 nanorods according to claim 1, characterized in that, The cooling described in step one is natural cooling.

5. The method for preparing SnO2 nanorods according to claim 1, characterized in that, In step two, the centrifugation speed is 7000-10000 rpm, the washing is done by alternating between deionized water and ethanol, and the drying temperature is 70-100℃; the high-temperature annealing treatment is carried out in a hydrogen or / and argon atmosphere, heated to 300℃-700℃ and held for 1-4 hours.

6. An application of SnO2 nanorods, characterized in that, The application of the SnO2 nanorods according to claim 1 in the preparation of lithium / sodium ion anode materials.

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