Lithium titanium aluminum phosphate ceramic nanofiber material as well as preparation method and application thereof

Abstract

The invention provides a titanium aluminum lithium phosphate ceramic nanofiber material and a preparation method and application thereof. The preparation method comprises the following steps: preparing a spinning solution from a lithium source, a titanium source, an aluminum source, a phosphorus source and a high-molecular polymer; performing electrostatic spinning to obtain a fiber membrane; calcining the fiber membrane in an inert atmosphere and an air atmosphere in sequence to obtain a lithium titanium aluminum phosphate ceramic nanofiber material; raw materials are cheap and easily available; compared with a particle material prepared by a traditional sol-gel method and the like, the obtained titanium-aluminum-lithium phosphate ceramic nanofiber material is more beneficial to migration of lithium ions; the conductivity is improved; as a high-performance solid electrolyte, the electrolyte can effectively meet the actual requirements of various applications of lithium batteries.

Description

Technical Field

[0001] This application belongs to the field of new energy materials and technology, and in particular relates to a lithium titanium aluminum phosphate ceramic nanofiber material, its preparation method and application. Background Technology

[0002] Currently, most commercial lithium batteries use organic liquid electrolytes. Firstly, these electrolytes pose safety risks such as leakage, flammability, and explosiveness, requiring airtight packaging to prevent leakage. Secondly, liquid electrolytes are prone to chemical reactions with the electrodes, leading to electrode structural damage and battery short circuits. Thirdly, organic liquid electrolytes are heavy, increasing the overall battery weight and hindering significant improvements in energy density.

[0003] Solid-state electrolytes can precisely overcome the shortcomings of traditional organic liquid electrolytes. Solid-state electrolytes combine advantages such as good safety, high voltage resistance, and light weight; they allow batteries to be made into various shapes, thus providing advantages such as pressure resistance, impact resistance, low production cost, and ease of processing; solid-state electrolytes can suppress the growth of lithium dendrites, allowing the use of lithium metal as the negative electrode, thereby greatly improving the battery's energy density. The NASICON-structured lithium-ion conductor Li... 1+x Al x Ti 2-x (PO4)3 (LATP) possesses advantages such as high electrical conductivity, relative stability in air, high mechanical strength, simple synthesis process, inexpensive raw materials, and a wide operating temperature range. Furthermore, the NASICON-structured lithium-ion conductor can be used in novel high-energy-density electrochemical energy storage devices based on lithium metal anodes. As an excellent solid-state electrolyte material, LATP has great potential in optimizing battery structure and improving battery stability. However, currently, LATP is mostly present in a particulate structure, and its practical applications are mainly achieved through high-temperature solid-phase synthesis, sol-gel methods, and plasma sintering. Defects such as low purity and large particle size in these particulate powders reduce their room-temperature ionic conductivity, severely impacting the application of LATP in battery energy. Summary of the Invention

[0004] This application provides a lithium aluminum titanium phosphate ceramic nanofiber material, its preparation method, and its application, to solve the problems existing in related technologies. The technical solution is as follows: In a first aspect, embodiments of this application provide a method for preparing lithium titanium aluminum phosphate ceramic nanofibers, wherein the chemical formula of lithium titanium aluminum phosphate is Li. 1+x Al x Ti 2-x (PO4)3, x = 0.3~0.5; The preparation process includes the following steps: The spinning solution is prepared by dissolving lithium, titanium, aluminum and phosphorus sources with polymers in a solvent according to stoichiometric ratios. Electrospinning of spinning solution yields fiber membranes; The fiber membrane was calcined sequentially in an inert atmosphere and an air atmosphere to obtain lithium titanium aluminum phosphate ceramic nanofiber material.

[0005] In one embodiment, the lithium source is one or a combination of two or more of lithium hydroxide, lithium perchlorate, lithium carbonate, lithium acetate, lithium nitrate, lithium sulfate, or lithium chloride.

[0006] In one embodiment, the titanium source is tetrabutyl titanate.

[0007] In one embodiment, the aluminum source is aluminum nitrate and / or aluminum chloride.

[0008] In one embodiment, the phosphorus source is ammonium dihydrogen phosphate.

[0009] In one embodiment, the polymer is one or more of polyvinylpyrrolidone, polyethylene oxide, or polyvinyl alcohol.

[0010] In one embodiment, the solvent is one or a combination of two or more of N-methylpyrrolidone, acetone, N,N-dimethylformamide, ethanol, or deionized water.

[0011] In one embodiment, the process of preparing the spinning solution is as follows: A first solution is obtained by dissolving a polymer in a solvent; a second solution is obtained by dissolving a lithium source, a titanium source, an aluminum source, and a phosphorus source in a solvent. The second solution is mixed evenly with the first solution to obtain the spinning solution.

[0012] In one embodiment, the mass concentration of the polymer in the first solution is 8-13%; the mass ratio of the polymer to the lithium source is (8-12):1.

[0013] In one embodiment, the electrospinning parameters are: relative humidity 20%–70%, voltage 8–20 kV, distance between the receiving device and the spinneret 10–20 cm; and a constant temperature thermal field of 20–50°C is applied in the spinning zone. The receiving device is a metal drum, and the rotation speed of the receiving device is 50 to 2000 r / min.

[0014] In one embodiment, the inert atmosphere is a nitrogen atmosphere; The calcination process of the fiber membrane in an inert atmosphere is as follows: the temperature is gradually increased from room temperature to 700℃~900℃, and the heating rate is 0.1~5℃ / min; The calcination process of the fiber membrane in air atmosphere is as follows: the temperature is gradually increased from room temperature to 450℃~600℃, and the heating rate is 2~10℃ / min.

[0015] Secondly, this application provides a lithium titanium aluminum phosphate nanofiber material, which is prepared by the method for preparing the lithium titanium aluminum phosphate nanofiber material.

[0016] In one embodiment, the average diameter of the fiber is 50–700 nm.

[0017] Thirdly, embodiments of this application provide the application of lithium titanium aluminum phosphate nanofibers as solid electrolyte materials in solid-state lithium metal batteries.

[0018] The advantages or beneficial effects of the above technical solutions include at least the following: This application uses lithium, titanium, aluminum, and phosphorus sources with polymers to prepare a spinning solution; a fiber membrane is obtained through electrospinning; the fiber membrane is then calcined sequentially under an inert atmosphere and an air atmosphere to obtain lithium titanium aluminum phosphate ceramic nanofibers. The raw materials are inexpensive and readily available. Compared with particulate materials prepared by traditional sol-gel methods, the obtained lithium titanium aluminum phosphate ceramic nanofibers are more conducive to lithium ion migration and have improved conductivity. As a high-performance solid electrolyte, it can effectively meet the practical requirements of various lithium battery applications.

[0019] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0020] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0021] Figure 1 This is a SEM image of the LATP nanofiber material prepared by electrospinning according to the present invention; Figure 2 This is a TEM image of the LATP nanofiber material prepared by electrospinning according to the present invention; Figure 3 The XRD pattern of LATP nanofibers prepared by electrospinning at 700℃ according to the present invention; Figure 4 The XRD pattern of LATP nanofibers prepared by electrospinning at 800℃ according to the present invention.

[0022] Figure 5 This is a product appearance drawing.

[0023] Figure 6 Impedance spectrum of LATP nanofibers prepared by electrospinning at 800℃ according to the present invention; Figure 7 SEM image of the material prepared by the gelation method in Comparative Example 1; Figure 8 The XRD pattern of the material prepared by the gel method in Comparative Example 1; Figure 9 Impedance spectra of the material prepared by the gel method in Comparative Example 1. Detailed Implementation

[0024] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0025] Example 1 A lithium titanium aluminum phosphate Li 1.3 Al 0.3 Ti 1.7 The preparation method of (PO4)3 ceramic nanofiber materials includes the following specific steps: (1) Dissolve the polymer polyvinylpyrrolidone in ethanol at room temperature and stir for 40 min to prepare a polyvinylpyrrolidone solution with a mass concentration of 10%; prepare a precursor solution consisting of 0.96 g lithium nitrate (10% excess), 5.78 g tetrabutyl titanate, 1.12 g aluminum nitrate nonahydrate, 4.60 g ammonium dihydrogen phosphate and 30 mL ethanol, and then mix the precursor solution with the polyvinylpyrrolidone solution.

[0026] (2) The above mixed solution was used to prepare a precursor fiber membrane by electrospinning. During electrospinning, a constant temperature hot field of 30°C was applied in the spinning zone. The parameters of electrospinning were: relative humidity 30%, injection speed 3 mL / h, voltage 18 kV, distance between receiving device and spinneret 15 cm, and rotation speed of receiving device 100 r / min. (3) The precursor fiber membranes were calcined in an inert atmosphere, with the calcination temperature gradually increased from room temperature to 800℃ at a rate of 2℃ / min, and held at the highest calcination temperature for 120 min. Then, the samples were calcined in an inert atmosphere, with the calcination temperature gradually increased from room temperature to 500℃ at a rate of 5℃ / min, and held at the highest calcination temperature for 30 min. Lithium aluminum titanium phosphate ceramic nanofibers were thus prepared. The morphology is as follows: Figure 5 As shown.

[0027] SEM images of lithium aluminum phosphate ceramic nanofibers are shown below. Figure 1 As shown, the TEM image is as follows Figure 2 As shown, the XRD pattern is as follows Figure 3 As shown in the figure. Electron microscopy reveals that the lithium aluminum titanium phosphate ceramic material prepared in this application exhibits distinct nanofibers, with the fibers interwoven and overlapping to form a fiber network. Electron microscopy measurements indicate that the fiber diameter is approximately 600 nm, and XRD patterns confirm the successful preparation of LATP.

[0028] Lithium aluminum titanium phosphate ceramic nanofibers are used as solid electrolytes; impedance spectra are as follows. Figure 6 As shown, the calculated lithium-ion migration rate is 7.7 × 10⁻⁶. -7 S / cm.

[0029] Example 2 A method for preparing lithium aluminum titanium phosphate (LATP) ceramic nanofibers, comprising the following steps: (1) Dissolve the polymer polyvinylpyrrolidone in ethanol at room temperature and stir for 40 min to prepare a precursor solution consisting of 0.96 g lithium nitrate (10% excess), 5.78 g tetrabutyl titanate, 1.12 g aluminum nitrate nonahydrate, 4.60 g ammonium dihydrogen phosphate and 30 mL ethanol. Then mix the precursor solution with the polymer solution.

[0030] (2) The above mixed solution was used to prepare a precursor fiber membrane by electrospinning. During electrospinning, a constant temperature hot field of 30°C was applied in the spinning zone. The parameters of electrospinning were: relative humidity 30%, injection speed 3 mL / h, voltage 18 kV, distance between receiving device and spinneret 15 cm, and rotation speed of receiving device 100 r / min. (3) The precursor fiber membranes were calcined in an inert atmosphere, with the calcination temperature gradually increased from room temperature to 700℃ at a rate of 2℃ / min, and held at the highest calcination temperature for 120 min. Then, the samples were calcined in an inert atmosphere, with the calcination temperature gradually increased from room temperature to 500℃ at a rate of 5℃ / min, and held at the highest calcination temperature for 30 min. The XRD patterns of the nanofibers are shown below. Figure 4 As shown, the XRD pattern indicates that LATP was successfully prepared.

[0031] Comparative Example 1 A method for preparing particulate materials using the sol-gel method: 38.4 g of citric acid was dissolved in 500 mL of deionized water, and 11.6 g of tetrabutyl titanate was dissolved in the same solution. In another portion of the same citric acid aqueous solution, 1.92 g of lithium nitrate (10% excess), 2.24 g of aluminum nitrate nonahydrate, and 9.2 g of ammonium dihydrogen phosphate were added in stoichiometric proportions until completely dissolved. The pH of both solutions was adjusted to approximately 7 using ammonia. The two solutions were then mixed and stirred thoroughly, and a measured amount of ethylene glycol was added. The final solution was dried overnight at 80°C in a forced-air drying oven. The oven temperature was then increased to 150°C to obtain a black, fluffy sample. This sample was ground and placed in a crucible, then calcined at 500°C for 3 hours in a tube furnace. Subsequently, it was calcined at 800°C for 2 hours in a muffle furnace at a heating rate of 5°C / min. After cooling, a white LATP sample was obtained. The LATP was ball-milled for 10 hours and sieved through a 325-mesh sieve to obtain the white LATP sample.

[0032] SEM image as follows Figure 7 As shown, the XRD pattern is as follows Figure 8 As shown in the SEM image, the lithium aluminum titanium phosphate material prepared by the gel method appears to be in the form of sheets or blocks, stacked together. The impedance spectrum is shown in the image. Figure 9 As shown, the calculated lithium-ion migration rate is 5.6 × 10⁻⁶. -7 S / cm.

[0033] In summary, this application prepares a spinning solution using lithium, titanium, aluminum, and phosphorus sources and a polymer; obtains a fiber membrane through electrospinning; and calcines the fiber membrane sequentially under an inert atmosphere and an air atmosphere to obtain lithium titanium aluminum phosphate ceramic nanofiber material, which is more conducive to lithium ion migration and improves electrical conductivity.

[0034] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a lithium aluminum titanium phosphate ceramic nanofiber material, characterized in that, The chemical formula of lithium titanium aluminum phosphate is Li. 1+x Al x Ti 2-x (PO4)3, x = 0.3~0.5; The preparation process includes the following steps: The spinning solution is prepared by dissolving lithium, titanium, aluminum and phosphorus sources with polymers in a solvent according to stoichiometric ratios. Electrospinning of spinning solution yields fiber membranes; The fiber membrane was calcined sequentially in an inert atmosphere and an air atmosphere to obtain lithium titanium aluminum phosphate ceramic nanofiber material.

2. The method for preparing lithium aluminum titanium phosphate ceramic nanofibers according to claim 1, characterized in that, The lithium source is one or a combination of two or more of lithium hydroxide, lithium perchlorate, lithium carbonate, lithium acetate, lithium nitrate, lithium sulfate, or lithium chloride. The titanium source is tetrabutyl titanate; the aluminum source is aluminum nitrate and / or aluminum chloride; and the phosphorus source is ammonium dihydrogen phosphate.

3. The method for preparing lithium aluminum titanium phosphate ceramic nanofibers according to claim 1, characterized in that, The polymer is one or more of polyvinylpyrrolidone, polyethylene oxide, or polyvinyl alcohol; The solvent is one or a combination of two or more of N-methylpyrrolidone, acetone, N,N-dimethylformamide, ethanol, or deionized water.

4. The method for preparing lithium aluminum titanium phosphate ceramic nanofibers according to claim 1, characterized in that, The process of preparing spinning solution is as follows: A first solution is obtained by dissolving a polymer in a solvent; a second solution is obtained by dissolving a lithium source, a titanium source, an aluminum source, and a phosphorus source in a solvent. The second solution is mixed evenly with the first solution to obtain the spinning solution.

5. The method for preparing lithium aluminum titanium phosphate ceramic nanofibers according to claim 1, characterized in that, The mass concentration of the polymer in the first solution is 8-13%; the mass ratio of the polymer to the lithium source is (8-12):

1.

6. The method for preparing lithium aluminum titanium phosphate ceramic nanofibers according to claim 1, characterized in that, The parameters for electrospinning are: relative humidity 20%–70%, voltage 8–20 kV, distance between receiving device and spinneret 10–20 cm; and a constant temperature thermal field of 20–50°C is applied in the spinning zone. The receiving device is a metal drum, and the rotation speed of the receiving device is 50 to 2000 r / min.

7. The method for preparing lithium aluminum titanium phosphate nanofibers according to claim 1, characterized in that: The inert atmosphere is a nitrogen atmosphere; The calcination process of the fiber membrane in an inert atmosphere is as follows: the temperature is gradually increased from room temperature to 700℃~900℃, the heating rate is 0.1~5℃ / min; the calcination time is 1.5-3h; The calcination process of the fiber membrane in air atmosphere is as follows: the temperature is gradually increased from room temperature to 450℃~600℃, the heating rate is 2~10℃ / min; the calcination time is 15-60min.

8. A lithium aluminum titanium phosphate nanofiber material, characterized in that, It is prepared by the method for preparing lithium aluminum titanium phosphate nanofibers according to any one of claims 2 to 7. 9.The lithium aluminum titanium phosphate nanofiber material of claim 1, wherein, The average diameter of the fiber is 50–700 nm.

10. The application of the lithium titanium aluminum phosphate nanofiber material as described in claim 8 or 9 as a solid electrolyte material in solid-state lithium metal batteries.

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