A method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material

Abstract

This invention relates to a method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material, belonging to the field of composite electrode materials technology. The raw materials used in this invention are commercial GeO2, tin tetrachloride, and tetrabutyl titanate. A GeO2@C microsphere template is prepared using a hydrothermal method. Tin tetrachloride is added to the dispersion of the GeO2@C microsphere template, and after stirring at room temperature, solid-liquid separation and drying are performed to obtain GeO2@C@SnO2 composite powder. Using titanium-based tetrabutyl titanate and the GeO2@C@SnO2 composite powder, a GeO2@C@SnO2@TiO2 precursor powder is prepared using a sol-gel method. The GeO2@C@SnO2@TiO2 precursor powder is calcined in air to obtain the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material. The structure of the anode material of this invention can effectively solve the volume expansion problem of metal oxide anode materials and construct a rapid Li... + Transport pathways enhance the overall electrochemical performance of lithium-ion batteries.

Description

Technical Field

[0001] This invention relates to a method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material, belonging to the field of composite electrode material technology. Background Technology

[0002] Lithium-ion batteries are widely used in electric and plug-in hybrid electric vehicles due to their excellent portability, environmental friendliness, and strong independence, as well as their light weight, high capacity, and long cycle life. Therefore, there is an urgent need to develop higher-performance lithium-ion batteries. A lithium-ion battery consists of positive and negative electrodes, an electrolyte, and a separator, among which the negative electrode material plays a crucial role in the overall performance of the battery.

[0003] Metal oxides (such as SiO2, Fe3O4, SnO2, GeO2, and TiO2) are promising anode materials with advantages such as high specific capacity, high safety, ease of modification and composite formation, making them a viable alternative to traditional graphite anodes. However, they undergo significant volume changes during cycling, leading to electrode fragmentation, and the inherently low conductivity of oxides contributes to poor electrode stability and rate performance. Although studies have demonstrated ways to stabilize their performance, such as ultra-small size design (nanomaterials shorten lithium-ion diffusion paths and accelerate charge transfer during insertion / deintercalation) and protective layer structures (nanotubes, nanopores, hollow spheres, yolk-shell structures, etc.), further improvements are still needed for practical application. Summary of the Invention

[0004] To address the issues of significant volume expansion and poor electrochemical performance caused by the poor conductivity of oxide-based anode materials during cycling, this invention proposes a method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material. A GeO2@C microsphere template is prepared using a hydrothermal method. Tin tetrachloride is added to the dispersion of the GeO2@C microsphere template, and after stirring at room temperature, solid-liquid separation and drying are performed to obtain GeO2@C@SnO2 composite powder. Using tetrabutyl titanate as a titanium source and the GeO2@C@SnO2 composite powder, a GeO2@C@SnO2@TiO2 precursor powder is prepared via a sol-gel method. The GeO2@C@SnO2@TiO2 precursor powder is then calcined in air to obtain the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material. The structure of the anode material in this invention effectively solves the volume expansion problem of metal oxide anode materials and enables rapid Li-ray distillation. + Transport pathways enhance the overall electrochemical performance of lithium-ion batteries.

[0005] A method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material, the specific steps of which are as follows:

[0006] (1) Ammonia water was added dropwise to an aqueous solution containing GeO2. After the GeO2 was completely dissolved, glucose was added and the mixture was stirred at room temperature for 1-3 hours to obtain solution A. Solution A was added to a high-temperature and high-pressure reactor and reacted at 150-200℃ for 6-24 hours. Solid-liquid separation was performed, and the solid was dried to obtain product B (a microsphere template of GeO2@C).

[0007] (2) Disperse product B uniformly in a deionized water-ethanol mixed solution to obtain product B dispersion. Add tin tetrachloride to product B dispersion and mix evenly to obtain solution C. Stir solution C at room temperature for 2-4 hours. Wash the precipitate with ethanol by centrifugation and dry to obtain product D (GeO2@C@SnO2 composite powder).

[0008] (3) Disperse product D uniformly in ammonia-ethanol mixed solution to obtain product D dispersion, add tetrabutyl titanate, stir and react at room temperature for 1-3 h, wash the precipitate with ethanol by centrifugation, and dry to obtain precursor product E (GeO2@C@SnO2@TiO2 precursor powder).

[0009] (4) The precursor product E is calcined at 400~600℃ for 2~8h and then cooled to room temperature in the furnace to obtain a hollow core-shell structure SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material.

[0010] Preferably, in step (1), the mass concentration of GeO2 in solution A is 1-5%, the mass concentration of ammonia is 1-5%, and the mass concentration of glucose is 5-15%.

[0011] Preferably, in step (2), the volume ratio of ethanol to deionized water in the deionized water-ethanol mixed solution is 3:1~5, the mass concentration of product B in solution C is 1~6%, and the mass concentration of tin tetrachloride is 1~6%.

[0012] Preferably, in step (3), the mass concentration of ammonia in the ammonia-ethanol mixed solution is 1-5%, the mass concentration of product D in solution E is 2-7%, and the mass concentration of tetrabutyl titanate is 0.5-3%.

[0013] Preferably, the calcination temperature in step (4) is 400~600℃ and the time is 2~8h.

[0014] The beneficial effects of this invention are:

[0015] (1) The SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material of the present invention includes, from the inside out, a core of amorphous GeO2, an inner shell of SnO2 and a TiO2 outer shell covering amorphous GeO2. The hollow part between the core and the shell can achieve a large specific surface area, which promotes the full reaction between the electrolyte and the active material, and alleviates the volume change of GeO2 material during charging and discharging, thereby improving the cycle performance of GeO2 anode;

[0016] (2) The inner SnO2 shell of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material of the present invention is a P-type semiconductor and the GeO2 core is an N-type semiconductor. The two form a PN heterojunction to build a built-in electric field, which can significantly improve the conductivity of the material.

[0017] (3) The robust TiO2 shell of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material of the present invention can prevent the collapse of the hollow structure and enable the electrode to form a stable solid electrolyte interface film during cycling.

[0018] (4) The SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material of the present invention combines the advantages of GeO2, SnO2 and TiO2, and has a simple preparation process and superior performance. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope (SEM) image of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 1.

[0020] Figure 2 The charge-discharge curves of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 1 are shown.

[0021] Figure 3 The cycling performance spectrum of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 1 is shown.

[0022] Figure 4 The X-ray diffraction pattern of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 2 is shown.

[0023] Figure 5 The scanning electron microscope (SEM) image and its EDS spectrum of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 2 are shown.

[0024] Figure 6 The charge-discharge curves of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 2 are shown.

[0025] Figure 7The cycling performance spectrum of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 2 is shown.

[0026] Figure 8 This is a scanning electron microscope (SEM) image of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 3;

[0027] Figure 9 The charge-discharge curves of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 3 are shown.

[0028] Figure 10 The image shows the cycling performance spectrum of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in Example 3. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0030] Example 1: A method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material, the specific steps of which are as follows:

[0031] (1) Ammonia water was added dropwise to an aqueous solution containing commercial GeO2. After the GeO2 was completely dissolved, glucose was added and the mixture was stirred at room temperature for 1 hour to obtain solution A. Solution A was added to a high-temperature and high-pressure reactor and reacted at 150°C for 24 hours. Solid-liquid separation was performed, and the solid was dried to obtain product B (a microsphere template of GeO2@C). The mass concentration of GeO2 in solution A was 1%, the mass concentration of ammonia water was 1%, and the mass concentration of glucose was 5%.

[0032] (2) Product B was uniformly dispersed in a deionized water-ethanol mixed solution to obtain a product B dispersion. Tin tetrachloride was added to the product B dispersion and mixed evenly to obtain solution C. Solution C was stirred and reacted at room temperature for 2 hours. The precipitate was washed by centrifugation with ethanol and dried to obtain product D (GeO2@C@SnO2 composite powder). The volume ratio of ethanol to deionized water in the deionized water-ethanol mixed solution was 3:5. The mass concentration of product B in solution C was 1%, and the mass concentration of tin tetrachloride was 1%.

[0033] (3) Under stirring conditions, product D was uniformly dispersed in an ammonia-ethanol mixed solution to obtain a product D dispersion. Tetrabutyl titanate was added, and the mixture was stirred at room temperature for 1 h. The precipitate was washed by centrifugation with ethanol and dried to obtain precursor product E (GeO2@C@SnO2@TiO2 precursor powder). The mass concentration of ammonia in the ammonia-ethanol mixed solution was 1%, the mass concentration of product D in solution E was 2%, and the mass concentration of tetrabutyl titanate was 0.5%.

[0034] (4) The precursor product E was calcined in air at 400°C for 8 hours and then cooled to room temperature in the furnace to obtain a hollow core-shell structure SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material.

[0035] The scanning electron microscope (SEM) morphology of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in this embodiment is shown below. Figure 1 ,from Figure 1 It can be seen that the prepared anode material has a hollow core-shell structure, with a core diameter of about 1.5µm, a microsphere diameter of about 5µm, and nanoparticles attached to the outer shell;

[0036] In this embodiment, SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material is used as the anode of a lithium-ion half-cell. The active material, acetylene black, and PVDF are ground in a mass ratio of 7:2:1 and then uniformly coated onto copper foil. After vacuum drying, it is used as the battery anode. A lithium metal sheet is used as the counter electrode. The electrolyte is 1 mol / L LiPF6 with 10% FEC solution added. The charge-discharge curves of the first three cycles of the lithium-ion half-cell are shown below. Figure 2 For performance after 130 cycles, see [link to performance chart]. Figure 3 ,Depend on Figure 2 and 3 It can be seen that the charge / discharge specific capacities for the first, second, and third charges are 629 / 800, 597 / 689, and 576 / 640 mAh g, respectively. −1 The coulombic efficiencies were 78.6%, 86.7%, and 90.0%, respectively, with the coulombic efficiency increasing with the number of cycles. At a current density of 0.2C, after 130 cycles, it still maintained a coulombic efficiency of 400.15 mAh g⁻¹. −1 The reversible capacity indicates that the anode material in this embodiment has excellent reversibility and cycle stability.

[0037] Example 2: A method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material, the specific steps of which are as follows:

[0038] (1) Ammonia water was added dropwise to an aqueous solution containing commercial GeO2. After the GeO2 was completely dissolved, glucose was added and the mixture was stirred at room temperature for 2 hours to obtain solution A. Solution A was added to a high-temperature and high-pressure reactor and reacted at 180°C for 14 hours. Solid-liquid separation was performed, and the solid was dried to obtain product B (a microsphere template of GeO2@C). The mass concentration of GeO2 in solution A was 3%, the mass concentration of ammonia water was 3%, and the mass concentration of glucose was 10%.

[0039] (2) Product B was uniformly dispersed in a deionized water-ethanol mixed solution to obtain a product B dispersion. Tin tetrachloride was added to the product B dispersion and mixed evenly to obtain solution C. Solution C was stirred and reacted at room temperature for 3 hours. The precipitate was washed by centrifugation with ethanol and dried to obtain product D (GeO2@C@SnO2 composite powder). The volume ratio of ethanol to deionized water in the deionized water-ethanol mixed solution was 3:3. The mass concentration of product B in solution C was 4%, and the mass concentration of tin tetrachloride was 4%.

[0040] (3) Under stirring conditions, product D was uniformly dispersed in an ammonia-ethanol mixed solution to obtain a product D dispersion. Tetrabutyl titanate was added, and the mixture was stirred at room temperature for 2 hours. The precipitate was washed by centrifugation with ethanol and dried to obtain precursor product E (GeO2@C@SnO2@TiO2 precursor powder). The mass concentration of ammonia in the ammonia-ethanol mixed solution was 3%, the mass concentration of product D in solution E was 5%, and the mass concentration of tetrabutyl titanate was 1.5%.

[0041] (4) The precursor product E was calcined in air at 500°C for 6 hours and then cooled to room temperature in the furnace to obtain a hollow core-shell structure SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material.

[0042] The X-ray diffraction pattern of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in this embodiment is shown below. Figure 4 ,from Figure 4 It can be seen that the anode material corresponds to the standard diffraction card of TiO2 at 2θ=25.3°, 37.9°, and 48.1°, and to the standard diffraction card of SnO2 at 2θ=33.8° and 51.8°. A peak appears at 2θ=26.4°, indicating that GeO2 has an amorphous structure.

[0043] The morphology and elemental distribution of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in this embodiment are shown in [reference needed]. Figure 5 ,from Figure 5 It can be seen that the anode material is composed of four elements: O, Ge, Sn, and Ti. Sn and Ti elements are evenly distributed on the inner and outer shells of the hollow microspheres. The core is amorphous GeO2, while the SnO2 inner shell and TiO2 outer shell cover amorphous GeO2.

[0044] In this embodiment, SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material is used as the anode of a lithium-ion half-cell. The active material, acetylene black, and PVDF are ground in a mass ratio of 7:2:1 and then uniformly coated onto copper foil. After vacuum drying, it is used as the battery anode. A lithium metal sheet is used as the counter electrode. The electrolyte is 1 mol / L LiPF6 with 10% FEC solution added. The charge-discharge curves of the first three cycles of the lithium-ion half-cell are shown below. Figure 6For performance after 130 cycles, see [link to performance chart]. Figure 7 ,Depend on Figure 6 and 7 It can be seen that the charge / discharge specific capacities for the first, second, and third charges are 746 / 952, 702 / 815, and 677 / 756 mAh g, respectively. −1 The coulombic efficiencies were 78.4%, 86.1%, and 89.6%, respectively, with the coulombic efficiency increasing with the number of cycles. At a current density of 0.2C, after 130 cycles, it still maintained a capacity of 429 mAh g / L. −1 The reversible capacity indicates that the anode material in this embodiment has excellent reversibility and cycle stability.

[0045] Example 3: A method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material, the specific steps of which are as follows:

[0046] (1) Ammonia water was added dropwise to an aqueous solution containing commercial GeO2. After the GeO2 was completely dissolved, glucose was added and the mixture was stirred at room temperature for 3 hours to obtain solution A. Solution A was added to a high-temperature and high-pressure reactor and reacted at 200°C for 7 hours. Solid-liquid separation was performed, and the solid was dried to obtain product B (a microsphere template of GeO2@C). The mass concentration of GeO2 in solution A was 5%, the mass concentration of ammonia water was 5%, and the mass concentration of glucose was 15%.

[0047] (2) Product B was uniformly dispersed in a deionized water-ethanol mixed solution to obtain a product B dispersion. Tin tetrachloride was added to the product B dispersion and mixed evenly to obtain solution C. Solution C was stirred and reacted at room temperature for 4 hours. The precipitate was washed by centrifugation with ethanol and dried to obtain product D (GeO2@C@SnO2 composite powder). The volume ratio of ethanol to deionized water in the deionized water-ethanol mixed solution was 2:1. The mass concentration of product B in solution C was 6%, and the mass concentration of tin tetrachloride was 6%.

[0048] (3) Under stirring conditions, product D was uniformly dispersed in an ammonia-ethanol mixed solution to obtain a product D dispersion. Tetrabutyl titanate was added, and the mixture was stirred at room temperature for 3 hours. The precipitate was washed by centrifugation with ethanol and dried to obtain precursor product E (GeO2@C@SnO2@TiO2 precursor powder). The mass concentration of ammonia in the ammonia-ethanol mixed solution was 5%, the mass concentration of product D in solution E was 7%, and the mass concentration of tetrabutyl titanate was 3%.

[0049] (4) The precursor product E was placed in an air atmosphere and calcined at 600℃ for 2 hours, and then cooled to room temperature in the furnace to obtain a hollow core-shell structure SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material.

[0050] The scanning electron microscope (SEM) morphology of the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material in this embodiment is shown below. Figure 8 ,from Figure 8 It can be seen that the prepared anode material has a hollow core-shell structure, with a core diameter of about 2µm, a microsphere diameter of about 6µm, and nanoparticles attached to the outer shell.

[0051] In this embodiment, SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material is used as the anode of a lithium-ion half-cell. The active material, acetylene black, and PVDF are ground in a mass ratio of 7:2:1 and then uniformly coated onto copper foil. After vacuum drying, it is used as the battery anode. A lithium metal sheet is used as the counter electrode. The electrolyte is 1 mol / L LiPF6 with 10% FEC solution added. The charge-discharge curves of the first three cycles of the lithium-ion half-cell are shown below. Figure 9 For performance after 100 cycles, see [link to performance chart]. Figure 10 ,Depend on Figure 9 and 10 It can be seen that the charge / discharge specific capacities for the first, second, and third charges are 894 / 1026, 864 / 948, and 839 / 905 mAh g, respectively. −1 The coulombic efficiencies were 87%, 91%, and 93%, respectively, with the coulombic efficiency increasing with the number of cycles. At a current density of 0.2C, after 100 cycles, it still maintained a capacity of 371 mAh g / L. −1 The reversible capacity indicates that the anode material in this embodiment has excellent reversibility and cycle stability.

[0052] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing a SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material, characterized in that, The specific steps are as follows: (1) Ammonia water is added dropwise to an aqueous solution containing GeO2. After the GeO2 is completely dissolved, glucose is added and the mixture is stirred at room temperature for 1-3 hours to obtain solution A. Solution A is added to a high-temperature and high-pressure reactor and reacted at 150-200℃ for 6-24 hours. Solid and liquid are separated and the solid is dried to obtain product B. (2) Disperse product B uniformly in a deionized water-ethanol mixed solution to obtain product B dispersion. Add tin tetrachloride to product B dispersion and mix evenly to obtain solution C. Stir solution C at room temperature for 2-4 hours. Wash the precipitate with ethanol by centrifugation and dry to obtain product D. (3) Disperse product D uniformly in ammonia-ethanol mixed solution to obtain product D dispersion. Add tetrabutyl titanate to product D dispersion and mix evenly to obtain solution E. Stir the reaction at room temperature for 1-3 h, wash the precipitate with ethanol by centrifugation, and dry to obtain precursor product F. (4) The precursor product F is placed in an air atmosphere for calcination and cooled to room temperature in the furnace to obtain a hollow core-shell structure SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material. The calcination temperature is 400~600℃ and the time is 2~8h.

2. The method for preparing the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material according to claim 1, characterized in that: In step (1), the mass concentration of GeO2 in solution A is 1-5%, the mass concentration of ammonia is 1-5%, and the mass concentration of glucose is 5-15%.

3. The method for preparing the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material according to claim 1, characterized in that: In step (2), the volume ratio of ethanol to deionized water in the deionized water-ethanol mixed solution is 3:1~5, the mass concentration of product B in solution C is 1~6%, and the mass concentration of tin tetrachloride is 1~6%.

4. The method for preparing the SnO2@TiO2 double-shell encapsulated amorphous GeO2 ternary anode material according to claim 1, characterized in that: In step (3), the mass concentration of ammonia in the ammonia-ethanol mixed solution is 1-5%, the mass concentration of product D in solution E is 2-7%, and the mass concentration of tetrabutyl titanate is 0.5-3%.

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