Preparation method and application of multi-shell layered titanate nanomaterial

Abstract

This invention provides a method for preparing and applying multi-shell layered titanate nanomaterials, wherein the multi-shell nanospheres have a layered phase crystal structure. The preparation method includes: dispersing a titanium source in a solvent at a controllable injection rate, followed by hydrothermal treatment to obtain layered titanic acid; further dispersing the layered titanic acid in a solution of other metal salts, followed by hydrothermal treatment to obtain layered titanates. This invention controls the ion diffusion and precipitation rates by adjusting the titanium source injection rate and injection temperature, and by matching appropriate ion diffusion and precipitation rates, thereby achieving the synthesis of multi-shell nanosphere structures. The number of shells in the multi-shell layered titanate nanosphere structure of this invention can be adjusted between two and three layers, and the size is controllable. It effectively combines the advantages of three-dimensional multi-shell structures and titanium-based layered materials, exhibiting excellent rate performance when applied to sodium-ion batteries, thus showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of energy and nanomaterials technology, and relates to a method for preparing multi-shell layered titanate nanomaterials and its application, particularly a simple and efficient one-pot hydrothermal preparation method for multi-shell layered titanate nanomaterials and its application. Background Technology

[0002] Titanium-based materials exhibit good catalytic activity, which is beneficial for accelerating electrode reaction kinetics. Their excellent chemical stability and diverse structures have led to extensive research in ion storage. However, the poor electronic / ionic conductivity of titanium-based materials makes them less than ideal for practical applications.

[0003] Compared with ordinary nanomaterials, multi-shell hollow nanomaterials have a higher specific surface area, larger internal space, and better buffering effect, thus showing great promise. The advantages of multi-shell hollow nanomaterials in the field of energy storage are mainly reflected in the following aspects: (1) Multi-shell hollow nanomaterials have a high specific surface area and abundant reactive sites: the high specific surface area ensures its high loading capacity, while the abundant active sites enhance its catalytic ability, and the abundant active sites can reduce resistance by fully contacting the electrolyte; (2) The hollow region inside the multi-shell hollow nanomaterial can alleviate the volume change of the electrode material during charging and discharging, thereby improving the cycle stability of the electrode material; (3) The short radial distance between different shells accelerates the diffusion of electrons / ions and makes the electrochemical reaction faster, thereby improving the rate performance of the electrode material; (4) Multi-shell hollow nanomaterials often have high porosity, and the electrolyte enters its core through the pores, thereby achieving a good wetting effect between the electrode material and the electrolyte.

[0004] Introducing multi-shell hollow nanomaterials into titanium-based materials can improve the ionic / electronic conductivity of titanium-based materials, while leveraging the advantages of both titanium-based materials and multi-shell hollow nanomaterials. Therefore, it holds promise for widespread application in energy storage, especially in sodium-ion battery energy storage devices. However, the actual synthesis of multi-shell hollow nanomaterials faces considerable challenges. First, current methods for synthesizing multi-shell hollow nanomaterials have limitations: the hard-template method uses monodisperse polymer or resin nanoparticles as templates, deposits chemical substances on their surfaces, and then removes the template through solvent extraction or calcination to form a uniform hollow material. This method is complex and cumbersome, and cannot achieve precise control over morphology and structure. The soft-template method uses micelles or emulsion droplets as templates, where a chemical reaction occurs at the interface between two phases, followed by separation and drying to obtain the hollow material. The template material in the soft-template method is easier to remove, thus avoiding structural collapse and damage caused by template removal. However, the soft-template method is costly and lacks universality. Second, although multi-shell hollow structures have a large specific surface area and good buffering performance, they face the dilemma of low structural strength and poor mechanical properties. Furthermore, the complex structure of multi-shell hollow nanomaterials makes large-scale production difficult, thus hindering their commercial application. Therefore, developing a simple, efficient, universal method for preparing multi-shell hollow nanomaterials with low equipment requirements is particularly important. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a template-free one-pot hydrothermal synthesis method for multi-shell layered titanate nanomaterials and its application.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] This invention provides a method for preparing multi-shell layered titanate nanomaterials. The method includes: preparing layered titanate nanomaterials using a hydrothermal method, dispersing the layered titanate nanomaterials in a metal salt solution for ion exchange, and calcining to obtain the multi-shell layered titanate nanomaterials.

[0008] In this invention, the multi-shell layered titanate nanomaterial refers to a nanosphere with at least two shells and a shell wall composed of stacked nanosheets. Exemplarily, the multi-shell layered titanate nanomaterial refers to layered titanate or layered titanate having two or three shells.

[0009] In this invention, the multi-shell layered titanate includes any one of layered magnesium titanate, layered lanthanum titanate, or layered calcium titanate.

[0010] According to an embodiment of the present invention, the preparation method of the multi-shell layered titanate nanomaterial includes the following steps:

[0011] (1) The titanium source is injected into the solvent and stabilizer, stirred, and the mixed solution is subjected to hydrothermal reaction. After washing, drying and calcining, layered titanate nanomaterials are obtained.

[0012] (2) The layered titanate nanomaterials described in step (1) are dispersed in other metal salt solutions, and after hydrothermal reaction, they are washed, dried and calcined to obtain multi-shell layered titanate nanospheres.

[0013] Preferably, in step (1), the titanium source is either isopropyl titanate (TIP) or tetrabutyl titanate (TBT), with TIP being preferred.

[0014] Preferably, the solvent is isopropanol (IPA).

[0015] Preferably, the stabilizer is diethylenetriamine (DETA).

[0016] Preferably, the ratio of the titanium source to the solvent and stabilizer is (1-5) mL:(30-50) mL:(5-160) μL, more preferably (1-3) mL:(20-45) mL:(20-40) μL, and an example is 3 mL:42 mL:20 μL.

[0017] Preferably, the injection rate of the titanium source is 0.02 to 1 mL / min, more preferably 0.06 to 0.8 mL / min, for example, it can be 0.02 mL / min, 0.06 mL / min, 0.08 mL / min, 0.1 mL / min, 0.2 mL / min or 0.8 mL / min.

[0018] Preferably, the stirring temperature can be 0-60℃, more preferably 20-30℃, and exemplary values ​​are 5℃, 20℃, 30℃, and 60℃.

[0019] Preferably, the stirring time is 0 to 30 minutes, more preferably 5 to 10 minutes, and exemplarily 0 minutes, 5 minutes, 10 minutes or 30 minutes.

[0020] Preferably, in step (1), the temperature of the hydrothermal reaction is 160 to 200°C; for example, 160°C, 180°C, and 200°C.

[0021] Preferably, in step (1), the hydrothermal reaction time is 0 to 24 hours, more preferably 20 to 24 hours, and exemplarily 6 hours, 12 hours, 18 hours, and 24 hours.

[0022] Preferably, in step (1), the roasting temperature is 300-700℃, more preferably 350-400℃; for example, it can be 300℃, 350℃, 400℃, 500℃, or 700℃.

[0023] Preferably, in step (1), the roasting time is 0.5 to 10 hours, more preferably 2 to 6 hours; for example, it can be 1 hour, 2 hours, or 4 hours.

[0024] Preferably, in step (1), the heating rate of the roasting is 0.5 to 10 °C / min, more preferably 0.5 to 1 °C / min; for example, it can be 0.5 °C / min, 1 °C / min, or 2 °C / min.

[0025] Preferably, in step (1), the roasting atmosphere is at least one of air, nitrogen and hydrogen, preferably air.

[0026] Preferably, in step (2), the metal salt is any one of magnesium salt, lanthanate salt or calcium salt, preferably any one of Mg(NO3)2·6H2O, La(NO3)3·6H2O or Ca(NO3)2·4H2O.

[0027] Preferably, in step (2), the concentration of the metal salt solution is 1 to 270 mM, more preferably 1 to 18 mM; for example, it can be 1 mM, 2 mM, 3 mM, 4 mM, 5 mM, 6 mM, 7 mM, 8 mM, 10 mM, 12 mM, 14 mM, 15 mM, 16 mM, 18 mM, 30 mM, 54 mM, 72 mM, 90 mM, 108 mM, 144 mM, 162 mM or 270 mM.

[0028] Preferably, in step (2), the temperature of the hydrothermal reaction is 160 to 200°C; for example, 160°C, 180°C, and 200°C.

[0029] Preferably, in step (2), the hydrothermal reaction time is 0 to 24 hours, more preferably 1 to 6 hours, with 1 hour, 3 hours, and 6 hours as examples.

[0030] Preferably, in step (2), the roasting temperature is 300-700℃, more preferably 350-400℃; for example, it can be 300℃, 350℃, 400℃, 500℃, or 700℃.

[0031] Preferably, in step (2), the roasting time is 0.5 to 10 hours, more preferably 1 to 4 hours, with 1 hour, 2 hours, and 4 hours as examples.

[0032] Preferably, in step (2), the heating rate of the roasting is 0.5 to 10 °C / min, more preferably 0.5 to 1 °C / min; for example, 0.5 °C / min, 1 °C / min, and 2 °C / min.

[0033] Preferably, in step (2), the roasting atmosphere is air, nitrogen and hydrogen, preferably air.

[0034] The present invention also provides multi-shell layered titanate nanomaterials prepared by the above preparation method.

[0035] According to an embodiment of the present invention, the multi-shell layered titanate nanomaterial is a multi-shell layered titanate nanosphere.

[0036] According to an embodiment of the present invention, the multi-shell layered titanate nanospheres have at least two shells, and the shell walls are formed by stacking nanosheets. Exemplarily, the number of shells in the multi-shell layered titanate nanospheres can be arbitrarily varied between two and three layers.

[0037] According to an embodiment of the present invention, the particle size of the multi-shell layered titanate nanospheres is 500 nm to 3 μm, with exemplary sizes being 500 nm, 800 nm, 1 μm, 2 μm, and 3 μm.

[0038] According to an embodiment of the present invention, the multi-shell layered titanate nanospheres are any one of layered magnesium titanate, layered lanthanum titanate, or layered calcium titanate.

[0039] The present invention also provides the application of the above-mentioned multi-shell layered titanate nanomaterials in batteries, preferably in sodium-ion batteries, and more preferably in sodium-ion battery cathode materials.

[0040] The present invention also provides a sodium-ion battery, wherein the positive electrode material of the sodium-ion battery comprises the above-mentioned multi-shell layered titanate nanomaterial.

[0041] According to an embodiment of the present invention, the sodium-ion battery has a discharge specific capacity of 80-90 mAh / g under charge-discharge test conditions of 0.05-3V and a rapid charge-discharge time of 1 minute.

[0042] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0043] The beneficial effects of this invention are:

[0044] 1. This invention provides a template-free one-pot hydrothermal synthesis method for preparing multi-shell layered titanate nanospheres. By controlling the titanium source injection rate, titanium source concentration, and stirring temperature, and matching appropriate ion diffusion and precipitation rates, solid, bilayer, and trilayer titanate nanospheres were prepared, respectively. Existing techniques for synthesizing multi-shell structures mainly involve hard template methods and soft template methods, which are relatively cumbersome and complex, making them difficult to apply in practice. The template-free method of this invention has the advantages of reducing redundant steps such as template preparation and removal, requiring less equipment, and being simple and efficient, with the potential for mass production and capacity expansion.

[0045] 2. The multi-shell layered titanate nanospheres prepared in this invention exhibit excellent rate performance as a cathode material for sodium-ion batteries. The multi-shell layered titanate nanospheres of this invention combine the structural advantages of a three-dimensional multi-shell structure with the intrinsic advantages of titanium-based materials, mainly manifested in: excellent electronic / ionic conductivity, rapid ion diffusion rate, excellent electrode kinetics, sufficient electrolyte penetration and diffusion, and buffering effect during sodium ion insertion and extraction. When the multi-shell layered titanate material of this invention is used as a cathode material for sodium-ion batteries, under charge-discharge test conditions of 0.05-3V, the discharge specific capacity is 80-90 mAh / g during a 1-minute rapid charge-discharge cycle. Attached Figure Description

[0046] Figure 1 These are field emission scanning electron microscope (FESEM) images (left) and high resolution transmission electron microscope (HRTEM) images (right) of the solid titanate (1S-HTO) nanospheres prepared in Example 1 of this invention.

[0047] Figure 2 These are FESEM (left) and HRTEM (right) images of the bilayer titanate (2S-HTO) nanospheres prepared in Example 2 of this invention.

[0048] Figure 3 These are FESEM (left) and HRTEM (right) images of the three-layer titanate (3S-HTO) nanospheres prepared in Example 3 of this invention.

[0049] Figure 4 This is the X-ray diffraction (XRD) pattern of the three-layer titanate nanospheres prepared in Example 3 of this invention.

[0050] Figure 5 This is an FESEM image of the three-layer magnesium titanate nanospheres prepared in Example 4 of this invention.

[0051] Figure 6 These are the XRD patterns of the three-layer magnesium titanate nanospheres prepared for different hydrothermal durations in Examples 4, 5, and 6 of this invention.

[0052] Figure 7 This is an FESEM image of the three-layer lanthanum titanate nanospheres prepared in Example 7 of this invention.

[0053] Figure 8 This is a FESEM image of the three-layer calcium titanate nanospheres prepared in Example 8 of this invention.

[0054] Figure 9 These are the XRD patterns of the three-layer calcium titanate nanospheres prepared by hydrothermal treatment with different concentrations of Ca(NO3)2·4H2O in Examples 8, 9 and 10 of this invention.

[0055] Figure 10 This is a battery rate performance diagram of sodium-ion batteries assembled using solid titanate nanospheres, three-layer titanate nanospheres, and titanium dioxide particles as positive electrode materials in Test Examples 1, 2, and 3 of this invention.

[0056] Figure 11 This is a battery cycle performance diagram of a sodium-ion battery assembled using the three-layer calcium titanate nanospheres prepared in Test Example 4 of this invention as the positive electrode material. Detailed Implementation

[0057] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0058] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0059] Example 1 Preparation of solid layered titanate nanospheres

[0060] (1) Add 40 μL of DETA dropwise to 42 mL of IPA at 30 °C, and add 1 mL of TIP to the above solution at an injection rate of 0.8 mL / min. Stir for 10 min.

[0061] (2) Transfer the solution from step (1) to a 100 mL reactor, perform hydrothermal reaction at 200 °C for 24 h, wash three times with ethanol, and dry the product in a 60 °C oven for 6 h.

[0062] (3) The dried product in step (2) was placed in an air atmosphere and calcined for 2 hours at a calcination temperature of 350°C and a heating rate of 1°C / min. After cooling, solid titanate nanospheres were obtained.

[0063] Figure 1These are field emission scanning electron microscope (FESEM) images (left) and high resolution transmission electron microscope (HRTEM) images (right) of the solid titanate (1S-HTO) nanospheres prepared in Example 1 of this invention. As can be seen from the images, the product prepared in this example is a solid sphere with a particle size of 1 μm, and its surface is composed of stacked nanosheets, which is beneficial for increasing the specific surface area of ​​the solid titanate nanospheres.

[0064] Example 2 Preparation of bilayered layered titanate nanospheres

[0065] (1) Add 20 μL of DETA dropwise to 42 mL of IPA at 20 °C, and add 3 mL of TIP to the above solution at an injection rate of 0.2 mL / min. Stir for 10 min.

[0066] (2) Transfer the solution from step (1) to a 100 mL reactor, perform hydrothermal reaction at 200 °C for 24 h, wash three times with ethanol, and dry the product in a 60 °C oven for 6 h.

[0067] (3) The dried product from step (2) was placed in an air atmosphere and calcined for 2 hours at a temperature of 350°C and a heating rate of 0.5°C / min. After cooling, bilayer titanate nanospheres were obtained.

[0068] Figure 2 These are FESEM (left) and HRTEM (right) images of the bilayer titanate (2S-HTO) nanospheres prepared in Example 2 of this invention. As can be seen from the images, the product prepared in this example is a bilayer nanosphere with a particle size of 500 nm. The nanosheets and bilayer structure on its surface further increase the specific surface area of ​​the bilayer titanate. Simultaneously, the gaps between the layers facilitate electrolyte penetration.

[0069] Example 3 Preparation of three-layered titanate nanospheres

[0070] (1) Add 20 μL DETA dropwise to 42 mL IPA at 30 °C, and add 3 mL L TIP to the above solution at an injection rate of 0.06 mL / min. Stir for 10 min.

[0071] (2) Transfer the solution from step (1) to a 100 mL reactor, perform hydrothermal reaction at 200 °C for 24 h, wash three times with ethanol, and dry the product in a 60 °C oven for 6 h.

[0072] (3) The dried product from step (2) was placed in an air atmosphere and calcined for 2 hours at a temperature of 350°C and a heating rate of 0.5°C / min. After cooling, three-layer titanate nanospheres were obtained.

[0073] Figure 3The images show the FESEM (left) and HRTEM (right) images of the trilayer titanate (3S-HTO) nanospheres prepared in Example 3 of this invention. As can be seen from the images, the product prepared in this example is a trilayer nanosphere with a particle size of 1 μm. Further FESEM observation of the microstructure of the broken nanospheres reveals its trilayer structure. Compared to solid titanate nanospheres and bilayer titanate nanospheres, trilayer titanate nanospheres have a larger specific surface area; the distance between layers is shorter, thus facilitating electron / ion transport; and the larger internal hollow volume is more conducive to its contact with the electrolyte, thereby optimizing the electrochemical reaction process.

[0074] Figure 4 This is the X-ray diffraction (XRD) pattern of the three-layer titanate nanospheres prepared in Example 3 of this invention. Analysis of the image shows that the product matches the standard cards for H₂Ti₂O₅·H₂O (JCPDS No. 47-1272) and anatase TiO₂ (JCPDS No. 21-1272), indicating that the product prepared in this example is titanate, and also contains anatase TiO₂.

[0075] Example 4 Preparation of three-layered magnesium titanate nanospheres

[0076] (1) Add 20 μL DETA dropwise to 42 mL IPA at 30 °C, and add 3 mL L TIP to the above solution at an injection rate of 0.06 mL / min. Stir for 10 min.

[0077] (2) Transfer the solution from step (1) to a 100 mL reactor, perform hydrothermal reaction at 200 °C for 24 h, wash three times with ethanol, and dry the product in a 60 °C oven for 6 h.

[0078] (3) Disperse 30 mg of the product from step (2) in 20 mL of 2 mM Mg(NO3)2·6H2O (magnesium nitrate hexahydrate) solution, sonicate to make the three-layer titanate nanospheres evenly dispersed, put them into a 160℃ reaction vessel for hydrothermal reaction for 6 h, wash with ethanol three times, and place the product in a 60℃ oven for drying for 6 h.

[0079] (4) The dried product from step (3) was placed in an air atmosphere and calcined for 2 hours at a temperature of 350°C and a heating rate of 0.5°C / min. After cooling, three-layer magnesium titanate nanospheres were obtained.

[0080] Figure 5 This is an FESEM image of the three-layer magnesium titanate nanospheres prepared in Example 4 of this invention. As can be seen from the image, the morphology and structure of the three-layer magnesium titanate nanospheres are similar to those of the three-layer titanate nanospheres, indicating that the structure and morphology of the surface nanosheets of the three-layer titanate nanospheres can still be maintained after hydrothermal treatment with magnesium nitrate hexahydrate.

[0081] Example 5 Preparation of three-layered magnesium titanate nanospheres

[0082] The difference from Example 4 is that in step (3), the mixture is placed in a 160°C reactor for hydrothermal reaction for 1 hour. The rest is the same as in Example 4.

[0083] Example 6 Preparation of three-layered magnesium titanate nanospheres

[0084] The difference from Example 4 is that in step (3), the mixture is placed in a 160°C reactor for hydrothermal reaction for 3 hours. The rest is the same as in Example 4.

[0085] Figure 6 These are the XRD patterns of three-layer magnesium titanate nanospheres prepared for different hydrothermal times in Examples 4, 5, and 6 of this invention. As can be seen from the figures, the characteristic peaks in the XRD pattern of the three-layer magnesium titanate nanospheres prepared with a hydrothermal time of 6 hours are more pronounced and the peak intensity is stronger than that of the three-layer magnesium titanate nanospheres prepared with hydrothermal times of 1 hour and 3 hours.

[0086] Example 7 Preparation of three-layered lanthanum titanate nanospheres

[0087] (1) Add 20 μL DETA dropwise to 42 mL IPA at 30 °C, and add 3 mL L TIP to the above solution at an injection rate of 0.06 mL / min. Stir for 10 min.

[0088] (2) Transfer the solution from step (1) to a 100 mL reactor, perform hydrothermal reaction at 200 °C for 24 h, wash three times with ethanol, and dry the product in a 60 °C oven for 6 h.

[0089] (3) Disperse 30 mg of the product from step (2) in 20 mL of 1 mM La(NO3)3·6H2O (lanthanum nitrate hexahydrate) solution, sonicate to make the three layers of titanate evenly dispersed, put it into a 160℃ reaction vessel for hydrothermal reaction for 6 h, wash it three times with ethanol, and place the product in a 60℃ oven to dry for 6 h.

[0090] (4) The dried product from step (3) was placed in an air atmosphere and calcined for 2 hours at a temperature of 350°C and a heating rate of 0.5°C / min. After cooling, three-layer lanthanum titanate nanospheres were obtained.

[0091] Figure 7This is an FESEM image of the trilayer lanthanum titanate nanospheres prepared in Example 7 of this invention. As can be seen from the image, the morphology of the trilayer lanthanum titanate is similar to that of the trilayer titanate nanospheres, indicating that the structure and morphology of the surface nanosheets of the trilayer titanate nanospheres can still be maintained after hydrothermal treatment with lanthanum nitrate hexahydrate.

[0092] Example 8 Preparation of three-layered calcium titanate nanospheres

[0093] (1) Add 20 μL DETA dropwise to 42 mL IPA at 30 °C, and add 3 mL L TIP to the above solution at an injection rate of 0.06 mL / min. Stir for 10 min.

[0094] (2) Transfer the solution from step (1) to a 100 mL reactor, perform hydrothermal reaction at 200 °C for 24 h, wash three times with ethanol, and dry the product in a 60 °C oven for 6 h.

[0095] (3) Disperse 30 mg of the product from step (2) in 20 mL of 18 mM Ca(NO3)2·4H2O (calcium nitrate tetrahydrate) solution, sonicate to make the three-layer titanate nanospheres evenly dispersed, put them into a 160℃ reaction vessel for hydrothermal reaction for 6 h, wash with ethanol three times, and place the product in a 60℃ oven for drying for 6 h.

[0096] (4) The dried product from step (3) was placed in an air atmosphere and calcined for 2 hours at a temperature of 350°C and a heating rate of 0.5°C / min. After cooling, three-layer calcium titanate nanospheres were obtained.

[0097] Figure 8 This is an FESEM image of the three-layer calcium titanate nanospheres prepared in Example 8 of this invention. As can be seen from the image, the morphology and structure of the three-layer calcium titanate nanospheres are similar to those of the three-layer titanate nanospheres, indicating that the structure and morphology of the surface nanosheets of the three-layer titanate nanospheres can still be maintained after hydrothermal treatment with calcium nitrate tetrahydrate.

[0098] Example 9 Preparation of three-layered calcium titanate nanospheres

[0099] The difference from Example 8 is that in step (3), 30 mg of the product from step (2) is dispersed in 20 mL of a 72 mM Ca(NO3)2·4H2O (calcium nitrate tetrahydrate) solution. Everything else is the same as in Example 8.

[0100] Example 10 Preparation of three-layered calcium titanate nanospheres

[0101] The difference from Example 8 is that in step (3), 30 mg of the product from step (2) is dispersed in 20 mL of a 90 mM Ca(NO3)2·4H2O (calcium nitrate tetrahydrate) solution. Everything else is the same as in Example 8.

[0102] Example 11 Preparation of three-layered calcium titanate nanospheres

[0103] The difference from Example 8 is that in step (3), 30 mg of the product from step (2) is dispersed in 20 mL of a 108 mM Ca(NO3)2·4H2O (calcium nitrate tetrahydrate) solution. Everything else is the same as in Example 8.

[0104] Example 12 Preparation of three-layered calcium titanate nanospheres

[0105] The difference from Example 8 is that in step (3), 30 mg of the product from step (2) is dispersed in 20 mL of a 144 mM Ca(NO3)2·4H2O (calcium nitrate tetrahydrate) solution. Everything else is the same as in Example 8.

[0106] Example 13 Preparation of three-layered calcium titanate nanospheres

[0107] The difference from Example 8 is that in step (3), 30 mg of the product from step (2) is dispersed in 20 mL of a 162 mM Ca(NO3)2·4H2O (calcium nitrate tetrahydrate) solution. Everything else is the same as in Example 8.

[0108] Example 14 Preparation of three-layered calcium titanate nanospheres

[0109] The difference from Example 8 is that in step (3), 30 mg of the product from step (2) is dispersed in 20 mL of a 270 mM Ca(NO3)2·4H2O (calcium nitrate tetrahydrate) solution. Everything else is the same as in Example 8.

[0110] Figure 9 The figures show the XRD patterns of the three-layer calcium titanate nanospheres prepared by hydrothermal treatment with different concentrations of Ca(NO3)2·4H2O in Examples 3, 9, 10, 11, 12, 13, and 14 of this invention. As can be seen from the figures, compared with the XRD pattern of the three-layer titanate nanospheres, the peak at 2θ = 10° shifts to the left, indicating that the introduction of calcium ions expands the interlayer spacing of the three-layer titanate material.

[0111] Example 15 Preparation of titanium dioxide particles

[0112] (1) Disperse 0.4 mL of ammonia water and 0.2 g of hexadecylamine (95%) in 42 mL of ethanol at 30 °C, then add 3 mL of LTIP and stir for 10 min;

[0113] (2) Wash the product from step (1) three times with ethanol and dry the product in a 60°C oven for 6 hours.

[0114] (3) The dried product from step (2) was placed in an air atmosphere and calcined for 2 hours at a temperature of 350°C and a heating rate of 0.5°C / min. After cooling, titanium dioxide particles were obtained.

[0115] Test Example 1 :

[0116] The solid titanate nanospheres prepared in Example 1 were used as the active material for the positive electrode and sodium metal were used to compose a sodium-ion battery for rate performance testing. The mass ratio of the positive electrode material was active material: conductive carbon black (Super P): carboxymethyl cellulose (CMC) = 7:2:1. The battery model was KELOUDE CR2032. The electrolyte used was sodium trifluoromethanesulfonate (NaCF3SO3) dissolved in diethylene glycol dimethyl ether (Diglyme) at a concentration of 1M. The separator was a glass fiber separator. The assembly and sealing processes were all completed in a glove box with oxygen and water content of less than 0.05ppm.

[0117] Test Example 2 :

[0118] The three-layer titanate nanospheres prepared in Example 3 were used as the active material for the positive electrode and sodium metal were used to compose a sodium-ion battery for rate performance testing. The mass ratio of the positive electrode material was active material: conductive carbon black (Super P): carboxymethyl cellulose (CMC) = 7:2:1. The battery model was KELOUDE CR2032. The electrolyte used was sodium trifluoromethanesulfonate (NaCF3SO3) dissolved in diethylene glycol dimethyl ether (Diglyme) at a concentration of 1M. The separator was a glass fiber separator. The assembly and sealing processes were all completed in a glove box with oxygen and water content of less than 0.05ppm.

[0119] Test Example 3 :

[0120] The titanium dioxide particles prepared in Example 15 were used as the active material for the positive electrode and sodium metal were used to compose a sodium-ion battery for rate performance testing. The mass ratio of the positive electrode material was active material: conductive carbon black (Super P): carboxymethyl cellulose (CMC) = 7:2:1. The battery model was KELOUDE CR2032. The electrolyte used was sodium trifluoromethanesulfonate (NaCF3SO3) dissolved in diethylene glycol dimethyl ether (Diglyme) at a concentration of 1M. The separator was a glass fiber separator. The assembly and sealing processes were all completed in a glove box with oxygen and water content of less than 0.05ppm.

[0121] Figure 10 This is a rate performance graph of sodium-ion batteries assembled using solid titanate nanospheres, trilayer titanate nanospheres, and titanium dioxide particles as positive electrode materials in Test Examples 1, 2, and 3 of this invention. As can be seen from the graph, the rate performance of sodium-ion batteries assembled with trilayer titanate nanospheres and solid titanate nanospheres is superior to that of sodium-ion batteries assembled with titanium dioxide particles, with the trilayer titanate nanospheres exhibiting the best rate performance; when using 4 A·g... -1 At a current density during charging and discharging, the specific capacity of the sodium-ion battery assembled from three layers of titanate can still reach 84 mAh g. -1 This indicates that the multi-shell structure facilitates sufficient contact between the electrolyte and electrode materials, and that the multi-shell structure can shorten the electron / ion transport path, thereby optimizing the electrochemical kinetics and improving the rate performance of sodium-ion batteries assembled from it.

[0122] Test Example 4 :

[0123] The three-layer calcium titanate nanospheres prepared in Example 8 were used as the active material for the positive electrode and sodium metal were used to form a sodium-ion battery for cycle performance testing. The mass ratio of the positive electrode material was active material: conductive carbon black (Super P): carboxymethyl cellulose (CMC) = 7:2:1. The battery model was KELOUDE CR2032. The electrolyte used was sodium trifluoromethanesulfonate (NaCF3SO3) dissolved in diethylene glycol dimethyl ether (Diglyme) at a concentration of 1M. The separator was a glass fiber separator. The assembly and sealing processes were all completed in a glove box with oxygen and water content of less than 0.05ppm.

[0124] Figure 11 This is a battery cycle performance graph of a sodium-ion battery assembled using the trilayer calcium titanate nanospheres prepared in Test Example 4 of this invention as the positive electrode material. As can be seen from the graph, the sodium-ion battery assembled using the trilayer calcium titanate nanospheres as the positive electrode material can stably cycle for over 700 times, thus exhibiting excellent cycle stability. This indicates that the trilayer calcium titanate nanospheres have a stable structure during cycling.

[0125] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., 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 multi-shell layered titanate nanomaterials, characterized in that, Includes the following steps: (1) The titanium source is injected into the solvent and stabilizer, stirred, and the mixed solution is subjected to hydrothermal reaction. After washing, drying and calcining, layered titanate nanomaterials are obtained. The ratio of the titanium source to the solvent and stabilizer is (1~5) mL: (30~50) mL: (5~160) μL; The injection rate of the titanium source is 0.02~1 mL / min; The temperature of the hydrothermal reaction is 160~200℃. o C; The hydrothermal reaction time is 0~24 h; (2) The layered titanate nanomaterials described in step (1) are dispersed in other metal salt solutions, and after hydrothermal reaction, they are washed, dried and calcined to obtain multi-shell layered titanate nanomaterials.

2. The preparation method according to claim 1, characterized in that, In step (1), the titanium source is either isopropyl titanate (TIP) or tetrabutyl titanate (TBT).

3. The preparation method according to claim 1, characterized in that, The solvent is isopropanol (IPA); And / or, the stabilizer is diethylenetriamine (DETA).

4. The preparation method according to claim 1, characterized in that, The ratio of the titanium source to the solvent and stabilizer is (1~3) mL : (20~45) mL : (20~40) μL; And / or, the injection rate of the titanium source is 0.06~0.8 mL / min; And / or, in step (1), the calcination temperature is 300~700℃. o C, the roasting time is 0.5~10 h.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the metal salt is any one of magnesium salt, lanthanate, or calcium salt.

6. The preparation method according to claim 5, characterized in that, In step (2), the metal salt is any one of Mg(NO3)2·6H2O, La(NO3)3·6H2O or Ca(NO3)2·4H2O; And / or, in step (2), the concentration of the metal salt solution is 1~270 mM.

7. The preparation method according to claim 6, characterized in that, The concentration of the metal salt solution is 1~18 mM.

8. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the temperature of the hydrothermal reaction is 160~200℃. o C; The hydrothermal reaction time is 0~24 h; And / or, in step (2), the calcination temperature is 300~700℃. o C, the roasting time is 0.5~10 h.

9. The multi-shell layered titanate nanomaterial prepared by the preparation method according to any one of claims 1-8.

10. The multi-shell layered titanate nanomaterial as described in claim 9, characterized in that, The multi-shell layered titanate nanomaterial is a multi-shell layered titanate nanosphere.

11. The multi-shell layered titanate nanomaterial as described in claim 10, characterized in that, The multi-shell layered titanate nanospheres have at least two shells, and the shell walls are formed by stacking nanosheets. And / or, the particle size of the multi-shell layered titanate nanospheres is 500 nm ~ 3 μm; And / or, the multi-shell layered titanate nanospheres are any one of layered magnesium titanate, layered lanthanum titanate, or layered calcium titanate.

12. The application of the multi-shell layered titanate nanomaterials according to any one of claims 9-11 in batteries.

13. The application as described in claim 12, characterized in that, The application of the multi-shell layered titanate nanomaterials according to any one of claims 9-11 in sodium-ion batteries.

14. The application as described in claim 13, characterized in that, The application of the multi-shell layered titanate nanomaterials according to any one of claims 9-11 as cathode materials for sodium-ion batteries.

15. A sodium-ion battery, characterized in that, The cathode material of the sodium-ion battery includes the multi-shell layered titanate nanomaterials as described in any one of claims 9-11.

Images