Doped lithium aluminum titanium phosphate solid electrolyte material, preparation method and lithium ion battery containing the same

Abstract

The present invention relates to the field of battery electrode materials, and in particular to a doped lithium aluminum titanium phosphate solid electrolyte material, a preparation method and a lithium ion battery containing the same. The chemical composition of the doped solid electrolyte material is Li 1+z M y Al x Ti 2‑x‑y P3O 12‑b F a , where 0≤x,y≤0.4,0≤a,b≤0.8,0

Description

Technical Field

[0001] The present invention relates to the field of battery electrode materials, and in particular to a doped lithium aluminum titanium phosphate solid electrolyte material, a preparation method and a lithium ion battery containing the same. Background Art

[0002] The continued use of traditional fossil fuels has inevitably led to environmental pollution and the gradual destruction of the Earth's ecological environment. The development of efficient and environmentally friendly green energy has become a major trend. Lithium-ion batteries (LIBs) have been widely developed and applied due to their high energy density and environmental friendliness.

[0003] At present, although liquid lithium-ion batteries have been used on a large scale, traditional organic electrolyte lithium-ion batteries have flammable and explosive safety hazards. Among them, lithium aluminum titanium phosphate (LATP) oxide solid electrolyte has been studied intensively due to its safety and green characteristics, but it still has problems such as low ion conductivity and low particle density that limit its development. In order to make up for the defects of lithium aluminum titanium phosphate solid electrolyte materials themselves, researchers have provided many improvement solutions to solve such problems. At this stage, doping of lithium aluminum titanium phosphate solid electrolyte materials is the most commonly used improvement method. Doping with elements can make the crystal structure denser and increase lithium ion transmission channels, thereby improving the ionic conductivity of the material. In addition, element doping can also stabilize the crystal structure and inhibit Ti 4+ The reduction of ions reduces side reactions, thereby contributing to the uniform deposition of lithium, inhibiting dendrite formation, and preventing the battery from short-circuiting during cycling.

[0004] However, there are still many defects in the doping of lithium aluminum titanium phosphate materials at this stage. The silicon-doped lithium aluminum titanium phosphate material prepared by the molten salt method has low ionic conductivity; the tin-doped lithium aluminum titanium phosphate material has low particle density; the high ionic conductivity silicon-doped lithium aluminum titanium phosphate material prepared by the solution method and subsequent sintering, as the sintering temperature increases, the impurity phase in the material gradually increases.

[0005] Therefore, how to provide a new type of doped lithium aluminum titanium phosphate solid electrolyte material with high ionic conductivity and particle density is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention addresses the problems of low ionic conductivity, low particle density and increased impurity phases of current materials, and provides a doped lithium aluminum titanium phosphate solid electrolyte material, a preparation method and a lithium ion battery containing the same.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The first technical object of the present invention is to provide a doped lithium titanium aluminum phosphate solid electrolyte material, characterized in that the chemical composition of the doped lithium titanium aluminum phosphate solid electrolyte material is Li 1+z M y Al x Ti 2-x-y P3O 12-b F a ; wherein,

[0009] 0 ≤ x, y ≤ 0.4, 0 ≤ a, b ≤ 0.8, 0 < z ≤ 0.8, and M is one or a combination of more than one of the elements Zn, Mg, Ca, Sr, Si, and Sn.

[0010] The second technical object of the present invention is to provide a preparation method for the doped lithium titanium aluminum phosphate solid electrolyte material as described above.

[0011] A preparation method for a doped lithium titanium aluminum phosphate solid electrolyte material specifically includes the following steps:

[0012] (1) Mix an excessive lithium source and aluminum source, titanium source, phosphorus source, fluorine source, and compound containing doping elements weighed according to stoichiometric ratios. Weigh zirconia balls and add the mixed raw materials into a ball milling tank, add an appropriate amount of solvent to submerge the raw materials, then perform wet ball milling, and then obtain uniformly mixed raw materials through drying and sieving;

[0013] ((2) Pelletize the uniformly mixed raw materials obtained in step (1) to obtain a dense precursor;

[0014] (3) Transfer the uniformly mixed raw materials obtained in step (1) or the dense precursor after pelletizing in step (2) to a corundum crucible for calcination to obtain an intermediate; <了

[0015] (4) Crush, wet ball mill, dry, and sieve the intermediate obtained in step (3) to obtain an intermediate powder; ]

[0016] (5) Pelletize the intermediate powder obtained in step (4) to obtain a dense intermediate;

[0017] (6) Calcinate the intermediate obtained in step (3), the intermediate powder obtained in step (4), or the dense intermediate obtained in step (5) again, and cool to room temperature to obtain the doped lithium titanium aluminum phosphate solid electrolyte material.

[0018] Optionally, the method further includes: crushing and pulverizing the intermediate obtained in step (3) or the doped lithium titanium aluminum phosphate solid electrolyte material obtained in step (6), performing ultra-fine ball milling, then drying and sieving to obtain an ultra-fine doped lithium titanium aluminum phosphate solid electrolyte material.

[0019] Furthermore, the particle size of the ultrafine doped lithium titanium aluminum phosphate solid electrolyte material is 0.02 to 2 microns.

[0020] Optionally, in step (1), the fluorine source is one or more combinations of aluminum fluoride, magnesium fluoride, calcium fluoride, zinc fluoride, tin fluoride, zirconium fluoride, silicon fluoride, and lithium fluoride, the lithium source has a molar excess of 10%-20%, and the solvent is one or more combinations of water or alcohol solvents, preferably water, alcohol, and isopropanol.

[0021] Optionally, the calcination process parameters in step (3) are: heating to 400-600°C at a heating rate of 1-10°C / min and keeping warm for 2-4 hours, then heating to 800-1000°C at a heating rate of 1-5°C / min and keeping warm for 2 to 12 hours.

[0022] Optionally, in step (2) and step (5), the briquetting pressure is 5-30 MPa and the briquetting time is 3-30 min.

[0023] Optionally, the temperature of the re-calcination in step (6) is 800-1200° C., and the holding time is 2 to 12 hours.

[0024] The third technical purpose of the present invention is to provide a lithium-ion battery, which includes the doped lithium aluminum titanium phosphate solid electrolyte material as described above or the doped lithium aluminum titanium phosphate solid electrolyte material prepared by the method as described above.

[0025] It can be seen from the above technical solutions that, compared with the prior art, the doped lithium aluminum titanium phosphate solid electrolyte material, preparation method and lithium ion battery containing the same provided by the present invention have the following excellent effects:

[0026] 1. The present invention synthesizes doped lithium aluminum titanium phosphate (LATP) by adding raw materials containing doping elements during the preparation process, calcining and synthesizing it. The materials are then crushed, pulverized, and ultrafinely ball-milled to produce an ultrafine doped lithium aluminum titanium phosphate solid electrolyte material. The high-temperature solid-phase method is suitable for large-scale industrial production, features a simple doping process, and a short cycle time. It also addresses the current issues of low ionic conductivity, low particle density, and low purity (formation of impurity phases) in lithium aluminum titanium phosphate (LATP).

[0027] 2. In the doped lithium titanium aluminum phosphate solid electrolyte material disclosed in the present invention, aluminum fluoride in the raw material serves as a flux to reduce the sintering temperature and energy consumption; fluorine doped into the lattice oxygen sites of the lithium titanium aluminum phosphate material can reduce the lattice spacing and form defects in the lattice, which helps to form lithium ion diffusion channels; the addition of fluorine promotes grain growth, thereby increasing the particle density of the lithium titanium aluminum phosphate electrolyte; fluorine doping can also inhibit the formation of the impurity phase LiTiPO5 to a certain extent, thereby improving the purity of the lithium titanium aluminum phosphate electrolyte, which is beneficial to improving the ion transport performance and particle density of the lithium titanium aluminum phosphate solid electrolyte.

[0028] 3. The doped lithium aluminum titanium phosphate solid electrolyte material disclosed in the present invention makes the unstable Ti 4+ The ion part is replaced by metal cations with large ionic radius and high electronegativity (Zn 2+ Mg 2+ , Ca 2+ 、Sr 2+ 、Si 4+ 、Sn 4+ ) replacement makes the crystal structure dense and improves the ionic conductivity of the solid electrolyte.

[0029] In summary, the present invention synthesizes doped lithium titanium aluminum phosphate by adding raw materials containing doping elements during the preparation process, calcining it, and then crushing and pulverizing it to obtain a solid electrolyte material with high conductivity and particle density. This solid electrolyte material improves ionic conductivity and particle density, meeting market demands for high ionic conductivity and high particle density. The preparation method and modification steps are simple, with a short cycle time, making it suitable for industrial-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0031] Figure 1 This is an SEM image of the fluorine-doped intermediate in Example 1 of the present invention.

[0032] Figure 2 This is an SEM image of fluorine-doped lithium aluminum titanium phosphate in Example 1 of the present invention.

[0033] Figure 3 This is the XRD pattern of fluorine-doped lithium aluminum titanium phosphate in Example 1 of the present invention.

[0034] Figure 4 This is the XRD pattern of lithium aluminum titanium phosphate in Comparative Example 2 of the present invention.

[0035] Figure 5 This is the AC impedance diagram of fluorine-doped lithium aluminum titanium phosphate in Example 1 of the present invention.

[0036] Figure 6 This is the AC impedance diagram of lithium aluminum titanium phosphate in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] The embodiments of the present invention disclose a doped lithium aluminum titanium phosphate solid electrolyte material, a preparation method, and a lithium ion battery containing the same.

[0039] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0040] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0041] Example 1

[0042] 3.25g of lithium hydroxide monohydrate, 0.09g of aluminum oxide, 7.04g of titanium dioxide, 17.9g of ammonium dihydrogen phosphate, and 1.16g of aluminum fluoride were mixed with anhydrous ethanol and added with 150g of zirconium oxide balls. The mixture was ball-milled at 300rpm for 5h. The mixture was then dried at 80°C for 5h and sieved to obtain a uniformly mixed precursor. The precursor was placed in a corundum crucible and heated to 500°C at a rate of 5°C / min and held for 2h. The temperature was then further increased to 800°C and held for 8h to obtain an intermediate. The intermediate was crushed, ball-milled, dried, and sieved to obtain an intermediate powder. The powder was maintained at a pressure of 10MPa for 10min to obtain a dense intermediate. The temperature was then increased to 800°C at a rate of 5°C / min and held for 8h to obtain a fluorine-doped lithium aluminum titanium phosphate material. The above materials were crushed, mixed with anhydrous ethanol, and ball-milled at 300 rpm for 5 hours with the addition of zirconia balls. The mixture was then dried at 80° C. for 5 hours and sieved to obtain a fluorine-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0043] The room temperature ionic conductivity of the above materials reaches 1.0*10 -3S / cm, and the particle density reaches 95%.

[0044] Example 2

[0045] 8.14g of lithium hydroxide monohydrate, 0.66g of aluminum oxide, 17.6g of titanium dioxide, 44.8g of ammonium dihydrogen phosphate, and 2.18g of aluminum fluoride were mixed with anhydrous ethanol and added with 370g of zirconium oxide balls. The mixture was ball-milled at 400rpm for 4 hours. The mixture was then dried at 100°C for 4 hours and sieved to obtain a uniform precursor powder. The powder was then held at a pressure of 15MPa for 4 minutes to obtain a dense precursor. The precursor was placed in a corundum crucible and pre-calcined at 400°C for 4 hours. After that, it was sintered at 850°C and held for 12 hours to obtain an intermediate. The intermediate was then crushed, ball-milled, dried, sieved, and sintered at 850°C and held for 12 hours to obtain a fluorine-doped lithium aluminum titanium phosphate material. The heating rate for these steps was 3°C / min. The material was then crushed, ball-milled, dried, and sieved to obtain a fluorine-doped ultrafine lithium aluminum titanium phosphate solid electrolyte material.

[0046] Example 3

[0047] 16.3g of lithium hydroxide monohydrate, 2.2g of aluminum oxide, 35.3g of titanium dioxide, 89.7g of ammonium dihydrogen phosphate, and 2.91g of aluminum fluoride were mixed with deionized water, and 730g of zirconium oxide balls were added. The mixture was ball-milled at 500rpm for 3h. The mixture was then dried at 120°C for 3h and sieved to obtain a uniform precursor powder. The powder was maintained at a pressure of 20MPa for 3min to obtain a dense precursor. The precursor was then placed in a corundum crucible, pre-calcined at 600°C, held at this temperature for 4h, and then sintered at 900°C and held at this temperature for 8h to obtain an intermediate. The intermediate was crushed, ball-milled, dried, and sieved. The powder was then pressed into a dense intermediate, which was then sintered at 900°C and held at this temperature for 8h to obtain a fluorine-doped lithium aluminum titanium phosphate material. The heating rate for these steps was 10°C / min. Subsequently, the above materials are crushed, ball-milled, dried, and sieved to obtain fluorine-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0048] Example 4

[0049] 81.7g of lithium hydroxide monohydrate, 15.5g of aluminum oxide, 176.8g of titanium dioxide, 449.3g of ammonium dihydrogen phosphate and 7.3g of aluminum fluoride were mixed with deionized water, and 3700g of zirconium oxide balls were added. The mixture was ball-milled, dried and sieved to obtain a uniformly mixed precursor raw material. The ball-milling and drying parameters of this embodiment were the same as those of Example 1. The above precursor was placed in a corundum crucible, then pre-fired at 500°C, kept warm for 4 hours, and then sintered at 1000°C and kept warm for 12 hours to obtain an intermediate. The above intermediate was crushed, ball-milled, dried and sieved, and sintered at 1000°C and kept warm for 12 hours to obtain a fluorine-doped lithium titanium aluminum phosphate material. The heating rate of the above steps was 1°C / min. The above material was then crushed, ball-milled, dried and sieved to obtain a fluorine-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0050] Example 5

[0051] 9.32g of lithium hydroxide monohydrate, 0.66g of aluminum oxide, 1.05g of zinc oxide, 16.5g of titanium dioxide, 44.4g of ammonium dihydrogen phosphate and 2.16g of aluminum fluoride were mixed with anhydrous ethanol, and 370g of zirconium oxide balls were added, ball milled, dried and sieved to obtain a uniform precursor, wherein the ball milling and drying parameters were the same as in Example 2. The above powder was briquette to obtain a dense precursor, and the briquetting pressure and time were 15MPa and 5min respectively. The above precursor was placed in a corundum crucible, then pre-fired at 400℃, kept warm for 4h, and sintered at 850℃ for 12h to obtain an intermediate. The above intermediate was then crushed, ball milled, dried, sieved, sintered at 850℃ and kept warm for 12h to obtain a lithium titanium aluminum phosphate material doped with fluorine and zinc, and the heating rate of the above steps was 3℃ / min. Subsequently, the above materials are crushed, ball-milled, dried and sieved to obtain fluorine and zinc co-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0052] Example 6

[0053] 21g of lithium hydroxide monohydrate, 1.3g of aluminum oxide, 4.16g of zinc oxide, 30.6g of titanium dioxide, 88.3g of ammonium dihydrogen phosphate and 4.3g of aluminum fluoride were mixed with deionized water, and 750g of zirconium oxide balls were added, and the mixture was ball-milled, dried and sieved to obtain a uniform precursor powder. The ball milling and drying parameters of this embodiment are the same as those of Example 3 to obtain a uniform precursor powder. The above powder was briquette to obtain a dense precursor. The above briquetting pressure and time were 20MPa and 3min respectively. The above precursor was placed in a corundum crucible, and then pre-fired at 600℃, kept warm for 4h, heated to 900℃, sintered and kept warm for 8h to obtain an intermediate. The heating rate of this embodiment is 10℃ / min. The above intermediate was then crushed, ball-milled, dried and sieved, and the powder was briquette to obtain a dense intermediate. The dense intermediate was sintered at 900°C and kept at this temperature for 8 hours to obtain a fluorine- and zinc-co-doped lithium titanium aluminum phosphate material. The material was then crushed, ball-milled, dried, and sieved to obtain a fluorine- and zinc-co-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0054] Example 7

[0055] 110.6g of lithium hydroxide monohydrate, 8.65g of aluminum oxide, 31.1g of zinc oxide, 152.5g of titanium dioxide, 439.3g of ammonium dihydrogen phosphate, and 7.13g of aluminum fluoride were mixed with deionized water, and 3750g of zirconium oxide balls were added. The mixture was ball-milled, dried, and sieved to obtain a uniform precursor. The ball-milling and drying parameters of this embodiment were the same as those of Example 3. The precursor was placed in a corundum crucible and then pre-sintered at 500°C. After holding the temperature for 4 hours, the temperature was further increased to 1000°C and held for 12 hours to obtain an intermediate. The heating rate of this embodiment was 3°C / min. The intermediate was then crushed, ball-milled, dried, and sieved. The powder was briquette to obtain a dense intermediate. The briquetting pressure and time were 30MPa and 3min, respectively, and sintered at 1000°C and held for 12 hours to obtain a fluorine- and zinc-co-doped lithium aluminum titanium phosphate material. Subsequently, the above materials are crushed, ball-milled, dried and sieved to obtain fluorine and zinc co-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0056] Example 8

[0057] 16.4g of lithium hydroxide monohydrate, 2.22g of aluminum oxide, 35.5g of titanium dioxide, 90.3g of ammonium dihydrogen phosphate, 2.93g of aluminum fluoride, and 1.06g of magnesium oxide were mixed with isopropyl alcohol and 750g of zirconium oxide balls were added. The mixture was ball-milled, dried, and sieved to obtain a uniform precursor. The ball-milling and drying parameters of this embodiment were the same as those of Example 1. The precursor was placed in a corundum crucible and then pre-sintered at 600°C. After holding the temperature for 2 hours, the temperature was further increased to 900°C for sintering and held for 8 hours to obtain an intermediate. The heating rate of this embodiment was 1°C / min. The intermediate was sintered at 800°C and held for 8 hours to obtain a fluorine- and magnesium-co-doped lithium titanium aluminum phosphate material. The material was then crushed, ball-milled, dried, and sieved to obtain an ultrafine fluorine- and magnesium-co-doped lithium titanium aluminum phosphate solid electrolyte material.

[0058] Example 9

[0059] 16.5g of lithium hydroxide monohydrate, 0.45g of aluminum oxide, 35.6g of titanium dioxide, 90.5g of ammonium dihydrogen phosphate, 5.9g of aluminum fluoride and 2.1g of magnesium oxide were mixed with isopropyl alcohol, and 750g of zirconium oxide balls were added, and the mixture was ball-milled, dried and sieved to obtain a uniform precursor powder. The ball milling and drying parameters of this embodiment are the same as those of Example 2. The above powders were pressed into blocks to obtain a dense precursor. The pressing pressure and time of this embodiment were 10MPa and 10min, respectively. The above precursor was placed in a corundum crucible, and then pre-burned at 500°C. After keeping the temperature for 4h, the temperature was continued to be raised to 800°C for sintering, and kept warm for 12h to obtain an intermediate. The heating rate of this embodiment was 3°C / min. The above intermediate was then crushed, ball-milled, dried and sieved, and the above powder was pressed into blocks to obtain a dense intermediate. The dense intermediate was sintered at 900°C and kept at this temperature for 12 hours to obtain a fluorine- and magnesium-doped lithium titanium aluminum phosphate material. The material was crushed, ball-milled, dried, and sieved to obtain a fluorine- and magnesium-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0060] Example 10

[0061] 10.5g of lithium hydroxide monohydrate, 1.96g of aluminum oxide, 2.09g of zinc oxide, 15.4g of titanium dioxide, and 44.3g of ammonium dihydrogen phosphate were mixed with anhydrous ethanol and 370g of zirconium oxide balls were added. The mixture was ball-milled, dried, and sieved to obtain a uniform precursor. The ball-milling and drying parameters of this example were the same as those of Example 3. The precursor was placed in a corundum crucible and pre-calcined at 600°C. After holding at this temperature for 2 hours, the temperature was raised to 900°C and held at this temperature for 8 hours to obtain an intermediate. The heating rate in this example was 5°C / min. The intermediate was then crushed, ball-milled, dried, sieved, and briquette-pressed to obtain a dense intermediate. The pressure and time of the briquetting step were 20 MPa and 3 minutes, respectively. The dense intermediate was heated to 1000°C and held at this temperature for 8 hours to obtain a zinc-doped lithium aluminum titanium phosphate material. The above material was crushed, ball-milled, dried, and sieved to obtain a zinc-doped ultrafine lithium aluminum titanium phosphate solid electrolyte material.

[0062] Example 11

[0063] 8.28g of lithium hydroxide monohydrate, 2.0g of aluminum oxide, 17.9g of titanium dioxide, 45.6g of ammonium dihydrogen phosphate and 1.07g of magnesium oxide were mixed with deionized water, and 370g of zirconium oxide balls were added, and the mixture was ball-milled, dried and sieved to obtain a uniform precursor. The ball-milling and drying parameters of this embodiment are the same as those of Example 3. The above powders were briquette to obtain a dense precursor. The briquetting pressure and time of this embodiment were 30MPa and 3min, respectively. The above precursor was placed in a corundum crucible, pre-fired at 500°C and kept warm for 4h, then heated to 900°C for sintering, and kept warm for 12h to obtain an intermediate. The heating rate of this embodiment was 10°C / min. The above materials were crushed, ball-milled, dried and sieved to obtain a magnesium-doped ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0064] Example 12

[0065] 18.8g of lithium hydroxide monohydrate, 4.0g of aluminum oxide, 2.1g of zinc oxide, 1.1g of magnesium oxide, 33.3g of titanium dioxide, and 89.8g of ammonium dihydrogen phosphate were mixed with anhydrous ethanol and 750g of zirconium oxide balls were added. The mixture was ball-milled, dried, and sieved to obtain a uniform precursor. The ball-milling and drying parameters in this example were the same as those in Example 1. The precursor was placed in a corundum crucible and pre-sintered at 500°C and held for 2 hours. The temperature was then raised to 900°C and sintered for 8 hours to obtain an intermediate. The heating rate in this example was 5°C / min. The above materials were crushed, ball-milled, dried, and sieved to obtain an ultrafine lithium titanium aluminum phosphate solid electrolyte material co-doped with zinc and magnesium.

[0066] Comparative Example 1

[0067] 8.18g of lithium hydroxide monohydrate, 2.0g of aluminum oxide, 17.7g of titanium dioxide, and 45.0g of ammonium dihydrogen phosphate were mixed with anhydrous ethanol, and 370g of zirconium oxide balls were added. The mixture was ball-milled at 300rpm for 3h, then dried at 80°C for 5h and sieved to obtain a uniformly mixed precursor. The above precursor was placed in a corundum crucible, heated to 450°C at a heating rate of 5°C / min, kept at this temperature for 2h, and then continued to heat to 950°C and kept at this temperature for 4h to obtain an intermediate. The above materials were crushed, ball-milled, dried, and sieved to obtain an ultrafine lithium titanium aluminum phosphate solid electrolyte material.

[0068] Comparative Example 2

[0069] 8.18g of lithium hydroxide monohydrate, 2.0g of aluminum oxide, 17.7g of titanium dioxide and 45.0g of ammonium dihydrogen phosphate were mixed with anhydrous ethanol, and 370g of zirconium oxide balls were added. The mixture was ball-milled at 300rpm for 3h, then dried at 80℃ for 5h and sieved to obtain a uniformly mixed precursor. The above precursor was placed in a corundum crucible, heated to 450℃ at a heating rate of 5℃ / min, kept warm for 2h, and then continued to heat to 950℃ and kept warm for 4h to obtain an intermediate. The above intermediate was crushed, ball-milled, dried, and sieved, and then kept at 10MPa for 10min to obtain a dense intermediate. The temperature was then increased to 800℃ at a heating rate of 5℃ / min and kept warm for 8h to obtain a lithium aluminum titanium phosphate material. The above materials were crushed, ball-milled, dried, and sieved to obtain an ultrafine lithium aluminum titanium phosphate solid electrolyte material.

[0070] The following is a structural characterization and performance measurement of the materials prepared in the above examples and comparative examples. The specific experimental contents are as follows:

[0071] Figure 1 This is the SEM image of the intermediate of Example 1. It can be seen from the figure that the particle size of the material is below 2 μm and the particle size distribution is relatively uniform.

[0072] Figure 2 is the SEM image of fluorine-doped lithium aluminum titanium phosphate in Example 1, and Figure 1 Comparison shows that while the grains grow, the lithium aluminum titanium phosphate still maintains a dense structure without generating pores. This shows that fluorine doping can not only promote grain growth, but also make the material structure more dense.

[0073] Figure 3 The XRD pattern of fluorine-doped lithium aluminum titanium phosphate in Example 1 is compared with Figure 4 In the XRD pattern of lithium aluminum titanium phosphate in comparative example 2, the peak intensity of the LiTiPO5 diffraction peak at 27.5° to 28.5° in Example 1 is significantly lower than that in comparative example 2. This shows that fluorine doping can effectively inhibit the formation of impurity phases and improve the purity of lithium aluminum titanium phosphate materials.

[0074] Figure 5 , Figure 6 The AC impedance diagrams are for the fluorine-doped lithium titanium aluminum phosphate in Example 1 and the lithium titanium aluminum phosphate in Comparative Example 2. The diagrams show that the resistance of Example 1 is significantly lower than that of Comparative Example 2. Combined with Table 1, the ionic conductivities of Examples 1, 2, and 5 are higher than those of Comparative Example 2. This demonstrates that doping can effectively improve the ionic conductivity of the lithium titanium aluminum phosphate solid electrolyte material.

[0075] Table 1 Performance of electrolyte blocks of examples and comparative examples

[0076] Serial number <![CDATA[Ionic conductivity (10 -4 S / cm)]]> Particle density Example 1 10.1 94.7％ Example 2 8.8 94.3％ Example 5 5.9 94.1％ Example 6 5.2 95.2％ Comparative Example 2 3.5 91.1％

[0077] In addition, it can be seen from Table 1 that the particle density of Examples 1, 2, and 5 is significantly higher than that of Comparative Example 2. This indicates that doping can increase the particle density of the material by making the crystal structure denser.

[0078] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A doped lithium titanium aluminum phosphate solid electrolyte material, characterized in that: The chemical composition of the doped lithium aluminum titanium phosphate solid electrolyte material is Li 1+z M y Al x Ti 2-x-y P3O 12-b F a ; Among them, 0 < x, y ≤ 0.4, a > 0, b ≤ 0.8, 0 < z ≤ 0.8, and M is one or more combinations of Zn, Mg, Ca, Sr, Si, and Sn elements; The preparation method of the doped lithium titanium aluminum phosphate solid electrolyte material specifically includes the following steps: (1) Mix an excessive lithium source and the aluminum source, titanium source, phosphorus source, fluorine source, and doping element-containing compound weighed according to the above stoichiometric ratio, add a solvent to submerge the raw materials, then perform wet ball milling, and then obtain uniformly mixed raw materials through drying and screening; (2) Pelletize the uniformly mixed raw materials in step (1) to obtain a dense precursor; (3) Calcinate the uniformly mixed raw materials in step (1) or the dense precursor after pelletizing in step (2) to obtain an intermediate; (4) Crush, wet ball mill, dry, and screen the intermediate obtained in step (3) to obtain an intermediate powder; (5) Pelletize the intermediate powder obtained in step (4) to obtain a dense intermediate; (6) Calcinate the intermediate obtained in step (3), the intermediate powder obtained in step (4), or the dense intermediate obtained in step (5) again, and cool to room temperature to obtain the doped lithium titanium aluminum phosphate solid electrolyte material; In step (3), the calcination process is: heat up to 400 - 600 °C at a heating rate of 1 - 10 °C / min and hold for 2 - 4 h, and then heat up to 800 - 850 °C at a heating rate of 1 - 5 °C / min, and the holding time is 2 - 12 h; In step (6), the temperature of the re-calcination is 800 - 850 °C, and the holding time is 2 - 12 hours; It also includes: crushing, pulverizing the doped lithium titanium aluminum phosphate solid electrolyte material obtained in step (6), performing ultra-fine ball milling, then drying and screening to obtain an ultra-fine doped lithium titanium aluminum phosphate solid electrolyte material; The particle size of the ultra-fine doped lithium titanium aluminum phosphate solid electrolyte material is 0.02 - 2 microns.

2. The doped lithium aluminum titanium phosphate solid electrolyte material according to claim 1, characterized in that In step (1), the fluorine source is one or more combinations of aluminum fluoride, magnesium fluoride, calcium fluoride, zinc fluoride, tin fluoride, zirconium fluoride, silicon fluoride, and lithium fluoride. The molar ratio of the lithium source is excessive by 10% - 20%, and the solvent is one or more combinations of water or alcohol solvents.

3. The doped lithium aluminum titanium phosphate solid electrolyte material according to claim 1, characterized in that In steps (2) and (5), the pelletizing pressure is 5 - 30 MPa, and the pelletizing time is 3 - 30 min.

4. A lithium-ion battery, characterized in that: The lithium ion battery includes the doped lithium titanium aluminum phosphate solid electrolyte material as described in claim 1.

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