A tin-based negative electrode material, preparation method thereof and application thereof

Abstract

An embodiment of the present invention provides a tin-based anode material, a preparation method thereof, and an application thereof, comprising the following steps: S1, taking tris(hydroxymethyl)aminomethane and dopamine hydrochloride and dissolving them in deionized water, stirring at room temperature, centrifuging and washing several times to obtain a precipitate, and dissolving the precipitate in deionized water to obtain a PDA nanosphere solution; S2, preparing an aqueous solution of SnCl2·2H2O, then adding the PDA nanosphere solution under stirring, mixing evenly, and performing a hydrothermal reaction; S3, after cooling, centrifuging and washing the reaction product, and freeze-drying to obtain SnO2-QDs / PDA hollow nanospheres, which are the tin-based anode material. The tin-based anode material can effectively adapt to volume expansion, maintain structural stability, and has good cycling performance and rate performance.

Description

Technical Field

[0001] The present invention relates to a tin-based anode material, a preparation method thereof and an application thereof, belonging to the technical field of anode materials. Background Art

[0002] A lithium-ion battery is a secondary battery (rechargeable battery), which mainly works by the movement of lithium ions between the positive electrode and the negative electrode. During the charge and discharge process, Li + intercalates and deintercalates back and forth between the two electrodes. Lithium-ion batteries have the advantages of high voltage, small volume, light weight, high specific energy, no memory effect, no pollution, small self-discharge, long life, etc., and have become a research hotspot in recent years and achieved rapid development. The performance of lithium-ion batteries depends to a large extent on the performance of their anode materials.

[0003] Currently, the most widely studied anode materials for lithium-ion batteries are graphite and various carbon materials. However, studies have shown that carbon materials have large capacity losses, poor high-rate discharge performance, and are prone to form a passivation film in organic electrolytes, causing irreversible losses of the initial capacity, etc. In recent years, researchers have found that tin-based materials have a very high theoretical specific capacity. The theoretical specific capacity of pure tin can reach 994 mAh / g, and it is a very promising anode material. However, the volume of tin metal will change during the process of lithium deintercalation and intercalation, and there will be a volume expansion of more than 300%. The material deformation caused by this volume expansion will generate a large impedance inside the battery, resulting in poor battery cycle performance and too fast specific capacity attenuation. Therefore, it is urgent to modify the tin-based materials to improve their performance. Summary of the Invention

[0004] The present invention provides a tin-based anode material, a preparation method thereof and an application thereof, which can effectively solve the above problems.

[0005] The present invention is implemented as follows:

[0006] A preparation method of a tin-based anode material, comprising the following steps:

[0007] S1, taking tris(hydroxymethyl)aminomethane and dopamine hydrochloride and dissolving them in deionized water, stirring at room temperature, centrifuging and washing several times to obtain a precipitate, and dissolving the precipitate in deionized water to obtain a PDA nanosphere solution;

[0008] S2, preparing an aqueous solution of SnCl2·2H2O, then adding the PDA nanosphere solution under stirring, mixing evenly, and performing a hydrothermal reaction;

[0009] S3, after cooling, centrifuging and washing the reaction product, and freeze-drying to obtain SnO2-QDs / PDA hollow nanospheres, which are the tin-based anode material.

[0010] In some embodiments, in step S1, the mass ratio of tris(hydroxymethyl)aminomethane to dopamine hydrochloride is 0.8 - 1.5:1.

[0011] In some embodiments, in step S1, the concentration of the PDA nanosphere solution is 4 - 6 mg / ml.

[0012] In some embodiments, in step S1, the time of stirring at room temperature is 10 - 15 h.

[0013] In some embodiments, in step S2, the mass ratio of SnCl₂·2H₂O to PDA nanospheres is 3 - 5:1.

[0014] In some embodiments, in step S2, the temperature of the hydrothermal reaction is 170 - 190 °C and the time is 4 - 48 h.

[0015] A tin-based anode material prepared by the above method.

[0016] An application of the above tin-based anode material in the preparation of lithium / sodium ion batteries.

[0017] The beneficial effects of the present invention are as follows:

[0018] In the present invention, the steric hindrance effect and self-sacrificing template behavior of the polymer are utilized to induce the formation of hollow nanospheres assembled from ultrafine SnO₂ quantum dots (SnO₂-QDs) and nitrogen-doped carbon, which contain residual polydopamine (PDA) cores. The SnO₂-QDs / PDA hollow nanospheres can effectively adapt to volume expansion and maintain structural stability. More importantly, the PDA core can capture oxygen free radicals generated during charge and discharge processes and participate in the formation of the SEI layer, realizing the coupling effect of enhancing electrochemical reaction kinetics and improving Coulomb efficiency. The SnO₂-QDs / PDA hollow nanospheres of the present invention have high reversible capacity, excellent rate performance, and long cycle stability. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1It is the morphology and structure characterization diagram of the nanospheres provided in Embodiment 1 of the present invention. Among them, a, b) SEM and TEM diagrams of PDA solid nanospheres; c, d) SEM and TEM diagrams of SnO2-QDs / PDA hollow nanospheres; e-h) HRTEM and SAED images of SnO2-QDs / PDA hollow nanospheres; i) HADDF and EDX spectra of SnO2-QDs / PDA hollow nanospheres.

[0021] Figure 2 It is the electrochemical performance diagram of three materials, SnO2-QDs / PDA, Pure SnO2 and PDA, provided in Test Example 1 of the present invention. Among them, a) The cycling performance of pure SnO2, SnO2-QDs / PDA and PDA electrodes at a current density of 0.3 a g -1 The rate performance of the three electrodes at different current densities; c) The long-term cycling performance of the three electrodes at a current density of 1.0 A g -1 The current density. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. 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. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. 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.

[0023] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0024] The embodiments of the present invention provide a preparation method for a tin-based anode material, including the following steps:

[0025] S1. Take tris(hydroxymethyl)aminomethane and dopamine hydrochloride, dissolve them in deionized water, stir at room temperature, wash by centrifugation several times to obtain a precipitate, dissolve the precipitate in deionized water to obtain a PDA nanosphere solution; use tris(hydroxymethyl)aminomethane to polymerize dopamine hydrochloride under alkaline conditions to form smooth-surfaced PDA solid nanospheres with a diameter of about 300 nm.

[0026] S2. Prepare an aqueous solution of SnCl₂·2H₂O, then add the PDA nanosphere solution under stirring, mix evenly, and adsorb Sn 2+ onto the PDA nanospheres and carry out a hydrothermal reaction, during which part of the PDA polymer decomposes into nitrogen-doped carbon and penetrates into the tin oxide quantum dots.

[0027] S3. After cooling, centrifuge and wash the reaction product, and freeze-dry it to obtain SnO₂-QDs / PDA hollow nanospheres, which are the tin-based anode materials.

[0028] In some embodiments, in step S1, the mass ratio of tris(hydroxymethyl)aminomethane to dopamine hydrochloride is 0.8 - 1.5:1.

[0029] In some embodiments, in step S1, the concentration of the PDA nanosphere solution is 4 - 6 mg / ml.

[0030] In some embodiments, in step S1, the time of stirring at room temperature is 10 - 15 h. This stirring time is very crucial. If the stirring time is too short, the yield of PDA spheres is low and the product size is non-uniform. If the stirring time is too long, the product will aggregate into blocks, which is not conducive to subsequent use as a reaction template.

[0031] In some embodiments, in step S2, the mass ratio of SnCl₂·2H₂O to PDA nanospheres is 3 - 5:1.

[0032] In some embodiments, in step S2, the temperature of the hydrothermal reaction is 170 - 190 °C and the time is 4 - 48 h. This temperature and time are the key conditions for the formation of SnO₂ quantum dots. Outside this range, it is easy to cause an unsatisfactory material structure.

[0033] The embodiments of the present invention also provide a tin-based anode material prepared by the above method.

[0034] The embodiments of the present invention also provide an application of the above tin-based anode material in the preparation of lithium / sodium ion batteries. The above tin-based anode material has a high reversible capacity, excellent rate performance and long cycle stability, and is an ideal anode material for lithium / sodium ion batteries.

[0035] Example 1

[0036] Preparation of tin-based anode material:

[0037] Preparation of dopamine nanospheres: Dissolve 0.6 g of tris(hydroxymethyl)aminomethane and 0.5 g of dopamine hydrochloride in 500 ml of deionized water, control the pH to 8.0, place it on a magnetic stirrer and stir at room temperature for 13 hours, centrifuge and wash several times to obtain the required precipitate. Dissolve the precipitate in 30 ml of deionized water to obtain a 5.5 mg / ml PDA nanosphere solution.

[0038] Preparation of SnO2 / PDA composite nanomaterials: Weigh 0.1709 g of SnCl2·2H2O and dissolve it in 5 ml of deionized water to obtain solution A. Then, pour 10 ml of PDA nanosphere solution into A under stirring and mix. After half an hour, pour the mixed solution into a Teflon inner liner, seal it in a stainless steel autoclave, and place it in an oven at 180 °C for 8 h. After cooling, centrifuge and wash the reaction product, and freeze-dry it to obtain SnO2-QDs / PDA hollow nanospheres, which are the tin-based anode material.

[0039] The morphology and structure of the nanospheres are characterized as Figure 1 shown. As Figure 1 can be seen, in this example, first, tris(hydroxymethyl)aminomethane is used to polymerize dopamine hydrochloride under alkaline conditions to form PDA solid nanospheres with a diameter of about 300 nm and a smooth surface ( Figure 1 a, b); then, Sn 2+ is adsorbed on the PDA nanospheres, and the PDA polymer has a steric hindrance effect on restricting the growth of tin oxide quantum dots; at the same time, during the hydrothermal process, part of the PDA polymer decomposes into nitrogen-doped carbon and penetrates into the tin oxide quantum dots. Therefore, the PDA nanospheres act as a self-sacrificing template and steric hindrance, and finally induce SnO2-QDs / PDA hollow nanospheres assembled by tin oxide quantum dots, with the tin oxide quantum dots confined in the nitrogen-doped carbon and containing residual PDA cores ( Figure 1 c - e).

[0040] The distribution of tin oxide quantum dots and PDA in the SnO2-dot / PDA hollow nanospheres was further observed using a high-resolution transmission electron microscope. As Figure 1 e, f shows, there is a small amount of residual PDA inside the SnO2-dot / PDA hollow nanospheres, with a thickness of about 20 nm, which is composed of SnO2 quantum dots with a size of about 2 - 5 nm confined in the dopamine PDA matrix. The PDA at the edge is amorphous and acts as a protective medium for the stable structure. The tin oxide quantum dots have clear diffraction fringes with a spacing of 0.32 nm ( Figure 1g). The selected area electron diffraction (SAED) pattern of the SnO2-dot / PDA composite (Figure 1h) shows four distinct bright diffraction rings, representing the typical (110), (101), (220), and (311) crystal phases of tin oxide from the inside out, suggesting its polycrystalline nature. Figure 1 i is the STEM image of the SnO2-dot / PDA hollow nanospheres and the elemental mapping images of the C, N, Sn, and O elements of SnO2 / PDA by EDX, which also illustrate the highly uniform distribution characteristics of carbon, nitrogen, tin, and oxygen elements in the composite material, and also mark the successful preparation of the SnO2-dot / PDA hollow nanospheres.

[0041] Test Examples

[0042] In this test example, three materials, SnO2-QDs / PDA, Pure SnO2, and PDA, were used to prepare a sodium-ion full battery, and their performance was tested. The test results are as Figure 2 shown.

[0043] The cycling performance of three materials, SnO2-QDs / PDA, Pure SnO2, and PDA, at a current density of 0.3 Ag -1 was compared during 300 charge-discharge cycles. As Figure 2 shown in a, Pure SnO2 showed severe capacity decay in the first 10 cycles, and SnO2-QDs / PDA significantly alleviated this phenomenon. The capacity generated by the SnO2-QDs / PDA composite after 300 cycles was approximately 898.1 mAh g -1 , and the capacity retention was 86.5%. While the capacity retention rate of Pure SnO2 was only 23.7% after 300 cycles. The discharge capacity of PDA initially showed an upward trend and then remained stable, indicating the active interaction of PDA with lithium ions, enhancing the ion diffusion rate in SnO2-QDs / PDA and maintaining a high and stable reversible specific capacity. The morphology of SnO2-QDs / PDA maintained the complete structure of uniformly dispersed hollow spheres. Obviously, the SnO2-QDs / PDA electrode effectively alleviated the rapid capacity decay of tin oxide particles. In addition, the SnO2-QDs / PDA electrode maintained a high CE of nearly 99% throughout the cycle, indicating the formation of a stable SEI.

[0044] Figure 2 b shows the rate capabilities of the three materials at different current densities. At rate currents of 0.2, 0.5, 1.0, 2.0, and 5.0 Ag -1 , SnO2-QDs / PDA obtained 959, 768, 639, 562, and 445 mAh g -1Specific capacity, and then as the rate current gradually decreases, the specific capacity has good recoverability, indicating excellent rate performance and structural stability. In contrast, the capacity recovery performance of Pure SnO2 is very poor.

[0045] The long-term cycling performance of the SnO2-QDs / PDA composite at 1 A g -1 is shown in Figure 2 c. The discharge capacity of the SnO2-QDs / PDA composite gradually increases at the 200th cycle and reaches 771 mAh g -1 after 1500 cycles. This additional capacity may be attributed to the role of PDA in the SEI of the SnO2-QDs / PDA hollow nanosphere electrode during the lithiation process. In contrast, the capacity of the pure tin oxide electrode rapidly decreases under different discharge rates and with the extension of charge-discharge cycles, and the final specific capacity rapidly drops to 189 mAh g -1 . The specific capacity of PDA remains at 290 mAh g -1 after 300 cycles. Therefore, the SnO2-QDs / PDA hollow nanospheres assembled from ultrafine tin oxide quantum dots (SnO2-QDs) and polydopamine (PDA) have a high reversible capacity, excellent rate performance, and long-term cycling stability.

[0046] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a tin-based anode material, characterized in that, It includes the following steps: S1. Take tris(hydroxymethyl)aminomethane and dopamine hydrochloride, dissolve them in deionized water, stir at room temperature, centrifuge and wash several times to obtain a precipitate. Dissolve the precipitate in deionized water to obtain a PDA nanosphere solution; the mass ratio of tris(hydroxymethyl)aminomethane to dopamine hydrochloride is 0.8-1.5:1; the concentration of the PDA nanosphere solution is 4-6 mg / ml; the time of the room temperature stirring is 10-15 h; S2. Prepare an aqueous solution of SnCl2·2H2O, then add the PDA nanosphere solution under stirring, mix evenly, and carry out a hydrothermal reaction; the mass ratio of SnCl2·2H2O to the PDA nanosphere is 3-5:1; the temperature of the hydrothermal reaction is 170-190 °C and the time is 4-48 h; S3. After cooling, centrifuge and wash the reaction product, and freeze-dry to prepare SnO2-QDs / PDA hollow nanospheres, which are the tin-based anode materials; During the hydrothermal process, part of the PDA polymer decomposes into nitrogen-doped carbon and penetrates into the tin oxide quantum dots. The PDA nanospheres act as self-sacrificing templates and steric hindrances, and finally induce SnO2-QDs / PDA hollow nanospheres assembled from tin oxide quantum dots. The tin oxide quantum dots are confined in the nitrogen-doped carbon and contain residual PDA cores.

2. A tin-based anode material prepared by the method according to claim 1.

3. Use of the tin-based anode material according to claim 2 in the preparation of a lithium / sodium ion battery.

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